42 results on '"Hamstra D"'
Search Results
2. Fusion of the HSV-1 tegument protein vp22 to cytosine deaminase confers enhanced bystander effect and increased therapeutic benefit
- Author
-
Lee, K C, Hamstra, D A, Bullarayasamudram, S, Bhojani, M S, Moffat, B A, Dornfeld, K J, Ross, B D, and Rehemtulla, A
- Published
- 2006
- Full Text
- View/download PDF
3. Counseling patients about sexual health when considering post-prostatectomy radiation treatment
- Author
-
Wittmann, D, Montie, J E, Hamstra, D A, Sandler, H, and Wood, D P, Jr
- Published
- 2009
4. High-throughput transcriptomic analysis nominates proteasomal genes as age-specific biomarkers and therapeutic targets in prostate cancer.
- Author
-
Zhao, S G, Jackson, W C, Kothari, V, Schipper, M J, Erho, N, Evans, J R, Speers, C, Hamstra, D A, Niknafs, Y S, Nguyen, P L, Schaeffer, E M, Ross, A E, Den, R B, Klein, E A, Jenkins, R B, Davicioni, E, and Feng, F Y
- Subjects
DIAGNOSIS ,PROSTATE cancer treatment ,PROSTATE cancer ,PROTEASOMES ,PROSTATECTOMY - Abstract
Background:Although prostate cancer (PCa) is hypothesized to differ in nature between younger versus older patients, the underlying molecular distinctions are poorly understood. We hypothesized that high-throughput transcriptomic analysis would elucidate biological differences in PCas arising in younger versus older men, and would nominate potential age-specific biomarkers and therapeutic targets.Methods:The high-density Affymetrix GeneChip platform, encompassing >1 million genomic loci, was utilized to assess gene expression in 1090 radical prostatectomy samples from patients with long-term follow-up. We identified genes associated with metastatic progression by 10 years post-treatment in younger (age<65) versus older (age⩾65) patients, and ranked these genes by their prognostic value. We performed Gene Set Enrichment Analysis (GSEA) to nominate biological concepts that demonstrated age-specific effects, and validated a target by treating with a clinically available drug in three PCa cell lines derived from younger men.Results:Over 80% of the top 1000 prognostic genes in younger and older men were specific to that age group. GSEA nominated the proteasome pathway as the most differentially prognostic in younger versus older patients. High expression of proteasomal genes conferred worse prognosis in younger but not older men on univariate and multivariate analysis. Bortezomib, a Food and Drug Administration approved proteasome inhibitor, decreased proliferation in three PCa cell lines derived from younger patients.Conclusions:Our data show significant global differences in prognostic genes between older versus younger men. We nominate proteasomeal gene expression as an age-specific biomarker and potential therapeutic target specifically in younger men. Limitations of our study include clinical differences between cohorts, and increased comorbidities and lower survival in older patients. These intriguing findings suggest that current models of PCa biology do not adequately represent genetic heterogeneity of PCa related to age, and future clinical trials would benefit from stratification based on age. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
5. Diffusion MRI detects early events in the response of a glioma model to the yeast cytosine deaminase gene therapy strategy.
- Author
-
Stegman, L D, Rehemtulla, A, Hamstra, D A, Rice, D J, Jonas, S J, Stout, K L, Chenevert, T L, and Ross, B D
- Subjects
GLIOMAS ,ADENOSINE deaminase ,GENE therapy ,MAGNETIC resonance imaging - Abstract
Detection of a therapeutic response early in the course of cancer treatment, before tumor growth delay or regression, is not currently possible in experimental models or clinical medicine. New interim measures of therapeutic response would be particularly useful in the development of cancer chemosensitization gene therapy by facilitating optimization of gene transfer protocols and prodrug dosing schedules. Diffusion MRI is a sensitive technique producing quantitative and noninvasive images of the apparent mobility of water within a tissue. We investigated the utility of diffusion MRI for detecting early changes associated with a refined cytosine deaminase (CD)/5-fluorocytosine (5FC) chemosensitization gene therapy paradigm in orthotopic 9L gliomas stably expressing the recently cloned S. cerevisiae CD gene. Mean tumor diffusion increased 31% within 8 days of initiating 5FC treatment, preceding tumor growth arrest and regression. Complete regression of the intracranial tumor was observed in four of five treated animals, and recurrent tumor in the remaining animal exhibited water diffusion behavior similar to primary, untreated tumors. These results demonstrate the efficacy of the yCD/5FC strategy for glioma and suggest that increased tumor water diffusion is an indicator of active therapeutic intervention. [ABSTRACT FROM AUTHOR]
- Published
- 2000
- Full Text
- View/download PDF
6. The role of the maximum involvement of biopsy core in predicting outcome for patients treated with dose-escalated radiation therapy for prostate cancer
- Author
-
Murgic Jure, Stenmark Matthew H, Halverson Schuyler, Blas Kevin, Feng Felix Y, and Hamstra Daniel A
- Subjects
Prostate cancer ,Biopsy ,prognostic factors ,Maximum involvement ,Tumor in Core ,Radiotherapy ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Purpose To evaluate the influence of the maximum involvement of biopsy core (MIBC) on outcome for prostate cancer patients treated with dose-escalated external beam radiotherapy (EBRT). Methods and materials The outcomes of 590 men with localized prostate cancer treated with EBRT (≥75 Gy) at a single institution were retrospectively analyzed. The influence of MIBC on freedom from biochemical failure (FFBF), freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival (OS) was compared to other surrogates for biopsy tumor volume, including the percentage of positive biopsy cores (PPC) and the total percentage of cancer volume (PCV). Results MIBC correlated with PSA, T-stage, Gleason score, NCCN risk group, PPC, PCV, and treatment related factors. On univariate analysis, MIBC was prognostic for all endpoints except OS; with greatest impact in those with Gleason scores of 8–10. However, on multivariate analysis, MIBC was only prognostic for FFBF (hazard ratio [HR] 1.9, p = 0.008), but not for FFM (p = 0.19), CSS (p = 0.16), and OS (p = 0.99). Conclusions In patients undergoing dose-escalated EBRT, MIBC had the greatest influence in those with Gleason scores of 8–10 but provided no additional prognostic data as compared to PPC and PCV, which remain the preferable prognostic variables in this patient population.
- Published
- 2012
- Full Text
- View/download PDF
7. Randomized phase II trial of urethral sparing intensity modulated radiation therapy in low-risk prostate cancer: implications for focal therapy
- Author
-
Vainshtein Jeffrey, Abu-Isa Eyad, Olson Karin B, Ray Michael E, Sandler Howard M, Normolle Dan, Litzenberg Dale W, Masi Kathryn, Pan Charlie, and Hamstra Daniel A
- Subjects
Urethral-sparing IMRT ,Focal therapies ,Low risk prostate cancer ,Urinary quality-of-life ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Low-risk prostate cancer (PCa) patients have excellent outcomes, with treatment modality often selected by perceived effects on quality of life. Acute urinary symptoms are common during external beam radiotherapy (EBRT), while chronic symptoms have been linked to urethral dose. Since most low-risk PCa occurs in the peripheral zone (PZ), we hypothesized that EBRT using urethral sparing intensity modulated radiation therapy (US-IMRT) could improve urinary health-related quality of life (HRQOL) while maintaining high rates of PCa control. Methods Patients with National Comprehensive Cancer Network (NCCN) defined low-risk PCa with no visible lesion within 5 mm of the prostatic urethra on MRI were randomized to US-IMRT or standard (S-) IMRT. Prescription dose was 75.6 Gy in 41 fractions to the PZ + 3–5 mm for US-IMRT and to the prostate + 3 mm for S-IMRT. For US-IMRT, mean proximal and distal urethral doses were limited to 65 Gy and 74 Gy, respectively. HRQOL was assessed using the Expanded Prostate Cancer Index (EPIC) Quality of Life questionnaire. The primary endpoint was change in urinary HRQOL at 3 months. Results From June 2004 to November 2006, 16 patients were randomized, after which a futility analysis concluded that continued accrual was unlikely to demonstrate a difference in the primary endpoint. Mean change in EPIC urinary HRQOL at 3 months was −0.5 ± 11.2 in the US-IMRT arm and +3.9 ± 15.3 in the S-IMRT arm (p = 0.52). Median PSA nadir was higher in the US-IMRT arm (1.46 vs. 0.78, p = 0.05). At 4.7 years median follow-up, three US-IMRT and no S-IMRT patients experienced PSA failure (p = 0.06; HR 8.8, 95% CI 0.9–86). Two out of 3 patients with PSA failure had biopsy-proven local failure, both located contralateral to the original site of disease. Conclusions Compared with S-IMRT, US-IMRT failed to improve urinary HRQOL and resulted in higher PSA nadir and inferior biochemical control. The high rate of PSA failure and contralateral local failures in US-IMRT patients, despite careful selection of MRI-screened low-risk patients, serve as a cautionary tale for focal PCa treatments.
- Published
- 2012
- Full Text
- View/download PDF
8. ChemInform Abstract: Photochemistry of 1-Alkoxy- and 1-(Benzyloxy)-9,10-anthraquinones in Methanol: A δ-Hydrogen Atom Abstraction Process That Exhibits a Captodative Effect.
- Author
-
BLANKESPOOR, R. L., DE JONG, R. L., DYKSTRA, R., HAMSTRA, D. A., ROZEMA, D. B., VANMEURS, D. P., and VINK, P.
- Published
- 1991
- Full Text
- View/download PDF
9. Is the Fear of Postprostatectomy Radiation Therapy Justified?: An Analysis of Patient-Reported Quality of Life Following Adjuvant or Salvage Radiation.
- Author
-
Shumway, D., Daignault, S., Feng, F., Jackson, W., Johnson, S., Miller, D., Wei, J., and Hamstra, D.
- Subjects
- *
PROSTATE cancer treatment , *PROSTATECTOMY , *SALVAGE therapy , *ADJUVANT treatment of cancer , *CANCER radiotherapy , *QUALITY of life - Published
- 2014
- Full Text
- View/download PDF
10. Patient-Reported Outcomes for Quality of Life (QOL) by Expanded Prostate Cancer Index (EPIC) 15 Years Posttreatment.
- Author
-
Zhou, J., Daignault-Newton, S., Miller, D., Wei, J., Dunn, R., Johnson, S., Jackson, W., Imam, H., Kazzi, N., McLaughlin, P., Sandler, H., Sanda, M., and Hamstra, D.
- Subjects
- *
PROSTATE cancer treatment , *PROSTATE cancer patients , *QUALITY of life , *HEALTH outcome assessment , *CANCER radiotherapy - Published
- 2014
- Full Text
- View/download PDF
11. Assessment of Bone Growth Effects Among Medulloblastoma (MB) Patients Treated With Electron Versus Photon Spinal Irradiation
- Author
-
Kapadia, N.S., Oh, K., Hung, J., and Hamstra, D.
- Published
- 2012
- Full Text
- View/download PDF
12. Perineural Invasion Predicts for Increased Recurrence, Metastasis, and Death from Prostate Cancer following Treatment with Dose-Escalated Radiation Therapy
- Author
-
Kapadia, N.S., Qian, Y., Stenmark, M.H., Halverson, S., Blas, K., Vance, S., Sandler, H., Hamstra, D., and Feng, F.
- Published
- 2011
- Full Text
- View/download PDF
13. Serum PDGF Decreases during Combined Radiation and Androgen Deprivation Therapy for Prostate Cancer
- Author
-
Contessa, J.N., Wang, G., Pienta, K., Chinnaiyan, A., Wei, J., Hamstra, D., and Sandler, H.
- Published
- 2009
- Full Text
- View/download PDF
14. Parametric Response Map Analysis as an Imaging Biomarker for Distinguishing Progression from Pseudo-progression in High Grade Gliomas
- Author
-
Tsien, C., Galban, C.J., Chenevert, T.L., Hamstra, D., Gomez-Hassan, D., Junck, L., Rogers, L., Meyer, C.R., Rehemtulla, A., and Ross, B.D.
- Published
- 2008
- Full Text
- View/download PDF
15. Testicular Dysfunction in Male Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review.
- Author
-
Baliga S, Patel S, Naqa IE, Li XA, Cohen LE, Howell RM, Hoppe BS, Constine LS, Palmer JD, Hamstra D, and Olch AJ
- Subjects
- Adolescent, Adult, Child, Humans, Male, Young Adult, Follicle Stimulating Hormone blood, Luteinizing Hormone blood, Luteinizing Hormone metabolism, Neoplasms radiotherapy, Organs at Risk radiation effects, Radiotherapy Dosage, Sperm Count, Testosterone blood, Testosterone metabolism, Cancer Survivors statistics & numerical data, Infertility, Male blood, Infertility, Male epidemiology, Infertility, Male etiology, Infertility, Male pathology, Oligospermia blood, Oligospermia epidemiology, Oligospermia etiology, Oligospermia pathology, Radiation Injuries blood, Radiation Injuries epidemiology, Radiation Injuries etiology, Radiation Injuries pathology, Testis metabolism, Testis pathology, Testis radiation effects
- Abstract
Purpose: The male reproductive task force of the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative performed a comprehensive review that included a meta-analysis of publications reporting radiation dose-volume effects for risk of impaired fertility and hormonal function after radiation therapy for pediatric malignancies., Methods and Materials: The PENTEC task force conducted a comprehensive literature search to identify published data evaluating the effect of testicular radiation dose on reproductive complications in male childhood cancer survivors. Thirty-one studies were analyzed, of which 4 had testicular dose data to generate descriptive scatter plots. Two cohorts were identified. Cohort 1 consisted of pediatric and young adult patients with cancer who received scatter radiation therapy to the testes. Cohort 2 consisted of pediatric and young adult patients with cancer who received direct testicular radiation therapy as part of their cancer therapy. Descriptive scatter plots were used to delineate the relationship between the effect of mean testicular dose on sperm count reduction, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) levels., Results: Descriptive scatter plots demonstrated a 44% to 80% risk of oligospermia when the mean testicular dose was <1 Gy, but this was recovered by >12 months in 75% to 100% of patients. At doses >1 Gy, the rate of oligospermia increased to >90% at 12 months. Testosterone levels were generally not affected when the mean testicular dose was <0.2 Gy but were abnormal in up to 25% of patients receiving between 0.2 and 12 Gy. Doses between 12 and 19 Gy may be associated with abnormal testosterone in 40% of patients, whereas doses >20 Gy to the testes were associated with a steep increase in abnormal testosterone in at least 68% of patients. FSH levels were unaffected by a mean testicular dose <0.2 Gy, whereas at doses >0.5 Gy, the risk was between 40% and 100%. LH levels were affected at doses >0.5 Gy in 33% to 75% of patients between 10 and 24 months after radiation. Although dose modeling could not be performed in cohort 2, the risk of reproductive toxicities was escalated with doses >10 Gy., Conclusions: This PENTEC comprehensive review demonstrates important relationships between scatter or direct radiation dose on male reproductive endpoints including semen analysis and levels of FSH, LH, and testosterone., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
16. Validation of the Combination Gleason Score as an Independent Favorable Prognostic Factor in Prostate Cancer Treated With Dose-Escalated Radiation Therapy.
- Author
-
Quinn TJ, Chapman D, Parzen J, Wahl DR, McNamara A, Dess R, Chan J, Feng F, Jackson WC, and Hamstra D
- Subjects
- Male, Humans, Neoplasm Grading, Prognosis, Prostate-Specific Antigen, Prostate pathology, Prostatic Neoplasms pathology
- Abstract
Purpose: Prognostic factors for prostate cancer include tumor, node, metastases stage, pretreatment prostate-specific antigen, and pathology (via Gleason score [GS] or grade group). Of these, GS yields the largest effect on prostate cancer specific mortality. It was previously determined that those with cores with a mix of higher and lower GS at biopsy (which was termed a "ComboGS") had decreased risk for prostate cancer specific mortality after either surgical or radiation treatment. We validate the effect of ComboGS in an independent cohort of patients with prostate cancer treated with definitive dose-escalated radiation therapy (DE-RT) at 2 institutions., Methods and Materials: DE-RT was administered to 2539 men, of which 687 men had a ComboGS. To further ascertain the ComboGS effect we employed the modified Cancer of the Prostate Risk Assessment (mCAPRA) score. Rates of biochemical event-free survival and distant metastasis-free survival were compared across CAPRA scores, with and without modification, and the prognostic value of the CAPRA scores was compared using Harrel's concordance index., Results: On univariate analysis in Gleason 7 to 10 patients the presence of ComboGS improved 10-year biochemical event-free survival from 76.6% to 82.4% (hazard ratio [HR], 0.75; confidence interval [CI], 0.59-0.96; P = .021), 10-year distant metastasis-free survival from 89.3% to 93.2% (HR, 0.57; CI, 0.39-0.85; P = .005), 10-year prostate cancer specific survival from 93.9% to 97.4% (HR, 0.39; CI, 0.21-0.7; P = .001), and 10-year overall survival from 65.7% to 75.6% (HR, 0.69; CI, 0.57-0.83; P < .001). Multivariable analysis also supported that ComboGS is protective for biochemical failure (HR, 0.64; CI, 0.50-0.83; P < .001), distant metastasis (HR, 0.42; CI, 0.28-0.63; P < .001), death from prostate cancer (HR, 0.32; CI, 0.17-0.58; P < .001), and overall mortality (HR, 0.65; CI, 0.54-0.79; P < .001). Additionally, adjusting the mCAPRA score for ComboGS decreased the risk of biochemical failure by nearly 30% (HR, 0.70; 95% CI, 0.55-0.88; P = .003) and by 50% (HR, 0.54; 95% CI, 0.37-0.80; P = .002) for distant metastasis., Conclusions: ComboGS is a useful and readily available independent prognostic factor for all clinical endpoints evaluated. Moreover, the ComboGS can be used in conjunction with the extensively validated CAPRA scoring to better risk stratify patients being treated with definitive DE-RT for GS 7 to 10 disease., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
17. Hormonal status effects on the electrophysiological correlates of performance monitoring in women.
- Author
-
Jansen M, Van der Does AJW, De Rover M, De Bruijn ERA, and Hamstra DA
- Subjects
- Humans, Female, Electroencephalography, Affect physiology, Anxiety Disorders, Progesterone pharmacology, Estradiol pharmacology
- Abstract
Fluctuations in ovarian hormones are thought to play a role in the increased prevalence of mood and anxiety disorders in women. Error-related negativity (ERN) and error positivity (Pe) are two putative electrophysiological biomarkers for these internalizing disorders. We investigated whether female hormonal status, specifically menstrual cycle phase and oral contraceptive (OC) use, impact ERN and Pe. Additionally, we examined whether the relationship between the ERN and negative affect (NA) was moderated by hormonal status and tested whether the ERN mediated the relation between ovarian hormones and NA. Participants were healthy, pre-menopausal women who were naturally cycling (NC) or using OCs. Using a counterbalanced within-subject design, all participants performed a speeded-choice reaction-time task twice while undergoing electroencephalography measurements. NC women (N = 42) performed this task during the early follicular and midluteal phase (when estrogen and progesterone are both low and both high, respectively), while OC users (N = 42) performed the task during active OC use and during their pill-free week. Estradiol and progesterone levels were assessed in saliva. Comparing the two cycle phases within NC women revealed no differences in the (Δ)ERN, (Δ)Pe or NA. We did observe a negative relation between phase-related changes in the ΔERN and changes in NA. Mediation analysis additionally showed that phase-related changes in estradiol were indirectly and negatively related to NA through a reduction of ΔERN amplitudes. When comparing active OC users with NC women, we observed increased ΔPe- but not (Δ)ERN amplitudes in the former group. No evidence was found for moderating effects of menstrual cycle phase or OC use on the relation between the ERN and NA. These findings suggest that hormonal status may impact the neural correlates of performance monitoring and error sensitivity, and that this could be a potential mechanism through which ovarian hormones influence mood., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
18. Two Specialists, Two Recommendations: Discordance Between Urologists' & Radiation Oncologists' Prostate Cancer Treatment Recommendations.
- Author
-
Delaney RK, Sisco-Taylor BL, Wang X, Scherr K, Ubel PA, Haaland B, Kahn VC, Hamstra D, Wei JT, Madanay F, Davis JK, Greeno TU, and Fagerlin A
- Subjects
- Male, Humans, Middle Aged, Urologists, Radiation Oncologists, Practice Patterns, Physicians', Urology, Radiation Oncology, Prostatic Neoplasms radiotherapy, Prostatic Neoplasms surgery
- Abstract
Objective: To examine the treatment recommendation patterns among urologists and radiation oncologists, the level of concordance or discordance between physician recommendations, and the association between physician recommendations and the treatment that patients received., Method: The study was a secondary analysis of data from a randomized clinical trial conducted November 2010 to April 2014 (NCT02053389). Eligible participants were patients from the trial who saw both specialists. The primary outcome was physician recommendations that were scored using an adapted version of the validated PhyReCS coding system. Secondary outcomes included concordance between physician recommendations and the treatment patients received., Results: Participants were 108 patients (Mean age 61.9 years; range 43-82; 87% non-Hispanic White). Urologists were more likely to recommend surgery (79% of recommendations) and radiation oncologists were more likely to recommend radiation (68% of recommendations). Recommendations from the urologists and radiation oncologists were concordant for only 33 patients (30.6%). Most patients received a treatment that both physicians recommended (59%); however, 35% received a treatment that only one of their physicians recommended. When discordant, urologists more often recommended surgery and radiation oncologists recommended radiation and surgery as equally appropriate options., Conclusion: Urologists and radiation oncologists are more likely to differ than agree in their treatment recommendations for the same patients with clinically localized prostate cancer and more likely to favor treatment aligned with their specialty. Additional studies are needed to better understand how patients make decisions after meeting with two different specialists to inform the development of best practices within oncology clinics., (Published by Elsevier Inc.)
- Published
- 2022
- Full Text
- View/download PDF
19. Oral D-methionine protects against cisplatin-induced hearing loss in humans: phase 2 randomized clinical trial in India.
- Author
-
Campbell KC, Rehemtulla A, Sunkara P, Hamstra D, Buhnerkempe M, and Ross B
- Subjects
- Adult, Auditory Threshold, Cisplatin toxicity, Humans, India, Ototoxicity prevention & control, Hearing Loss chemically induced, Hearing Loss diagnosis, Hearing Loss prevention & control, Methionine therapeutic use
- Abstract
Objective: This exploratory Phase 2 clinical trial is the first determining safety and efficacy of oral D-methionine (D-met) in reducing cisplatin-induced ototoxicity. Design: Randomised parallel double-blind placebo-controlled exploratory Phase 2 study. Study samples: Fifty adult cancer patients received oral D-met or placebo before each cisplatin dose. Physical examination, blood collection and audiometry occurred at baseline and subsequent visits plus post-treatment audiometry. After attrition, final analysis included 27 patients. Results: Significant treatment group by ear and time (baseline vs. post-treatment) interactions occurred at 10 kHz and 11.2 kHz. Placebo and D-met groups differed in threshold shift for left ear at 11.2 kHz (mean difference = 22.97 dB [9.59, 36.35]). Averaging across ears, placebo group showed significant threshold shifts from baseline to post-treatment at 10 kHz (mean shift= -13.65 dB [-21.32,-5.98]), 11.2 kHz (-16.15 dB [-25.19,-7.12]), and 12.5 kHz (-11.46 dB [-19.18,-3.74]) but not 8 kHz (-8.65 dB [-17.86, 0.55]). The D-met group showed no significant threshold shifts (8 kHz: -1.25 dB [-7.75, 5.25]; 10 kHz:-3.93 dB [-8.89, 1.03]; 11.2 kHz:-4.82 dB [-11.21, 1.57]; 12.5 kHz:-3.68 dB [-11.57, 4.21]). Side effects did not significantly differ between groups. Conclusion: Oral D-met reduces cisplatin-induced ototoxicity in humans.
- Published
- 2022
- Full Text
- View/download PDF
20. Preparing Patients with Early Stage Prostate Cancer to Participate in Clinical Appointments Using a Shared Decision Making Training Video.
- Author
-
Scherr K, Delaney RK, Ubel P, Kahn VC, Hamstra D, Wei JT, and Fagerlin A
- Subjects
- Decision Making, Decision Making, Shared, Humans, Male, Patient Participation, Physicians, Prostatic Neoplasms therapy
- Abstract
Background: Rates of shared decision making (SDM) are relatively low in early stage prostate cancer decisions, as patients' values are not well integrated into a preference-sensitive treatment decision. The study objectives were to develop a SDM training video, measure usability and satisfaction, and determine the effect of the intervention on preparing patients to participate in clinical appointments., Methods: A randomized controlled trial was conducted to compare a plain-language decision aid (DA) to the DA plus a patient SDM training video. Patients with early stage prostate cancer completed survey measures at baseline and after reviewing the intervention materials. Survey items assessed patients' knowledge, beliefs related to SDM, and perceived readiness/intention to participate in their upcoming clinical appointment., Results: Of those randomized to the DA + SDM video group, most participants (91%) watched the video and 93% would recommend the video to others. Participants in the DA + SDM video group, compared to the DA-only group, reported an increased desire to participate in the decision (mean = 3.65 v. 3.39, P < 0.001), less decision urgency (mean = 2.82 v. 3.39, P < 0.001), and improved self-efficacy for communicating with physicians (mean = 4.69 v. 4.50, P = 0.05). These participants also reported increased intentions to seek a referral from a radiation oncologist (73% v. 51%, P = 0.004), to take notes (mean = 3.23 v. 2.86, P = 0.004), and to record their upcoming appointments (mean = 1.79 v. 1.43, P = 0.008)., Conclusions: A novel SDM training video was accepted by patients and changed several measures associated with SDM. This may be a scalable, cost-effective way to prepare patients with early stage prostate cancer to participate in their clinical appointments.[Box: see text].
- Published
- 2022
- Full Text
- View/download PDF
21. Ethical Allocation of Proton Therapy and the Insurance Review Process.
- Author
-
Grzywacz V, Quinn TJ, Wilson T, Reitemeier P, Navin M, Hamstra D, Anderson J, Chinnaiyan P, Stevens C, and Kabolizadeh P
- Subjects
- Aged, Humans, Medicare, Odds Ratio, United States, Proton Therapy
- Abstract
Purpose: The purpose of this study was to delineate a scoring system to maximize the ethical allocation of proton beam therapy (PBT) and determine what factors are associated with receipt of PBT, including the role of specific insurance providers., Methods and Materials: Our scoring system was developed in collaboration with a multidisciplinary panel of experts. Patients submitted for PBT consideration were assigned a score by committee at a weekly peer-reviewed session at a time when our center was operating at capacity. Univariate analysis and multivariable analysis of initial and final insurance response were performed., Results: One hundred ninety-seven patients were prospectively reviewed. Ninety-three percent of patients with Medicaid coverage, 88% of patients with Medicare, and 78% of patients with private insurance were ultimately approved for PBT. Median time to final insurance response was 12 days (interquartile range, 9-18 days) for patients who were ultimately denied PBT coverage. Having primary provider C (odds ratio [OR], 14; 95% confidence interval [CI], 1.20-1.96; P = .033) or third party providers A (OR, 4.22; 95% CI, 1.71-10.9; P = .002) or B (OR, 5.28; 95% CI, 1.56-17.2; P = .006) was significantly associated with final insurance denial for PBT on univariate analysis. Total score (OR, 0.79; 95% CI, 0.67-0.90; P = .002) and having coverage through third party provider A (OR, 24.2; 95% CI, 9.51-68.9; P < .001) were associated with final insurance response on multivariable analysis., Conclusions: Our scoring system was significantly associated with receipt of proton beam therapy. Certain insurance providers are less likely to approve PBT for patients, all else being equal. Such a scoring system could be implemented effectively at other PBT facilities, and additional work is needed in ensuring patients with the most to gain from PBT will be approved by their insurance providers., (Copyright © 2021 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
22. VA-Radiation Oncology Quality Surveillance Program.
- Author
-
Hagan M, Kapoor R, Michalski J, Sandler H, Movsas B, Chetty I, Lally B, Rengan R, Robinson C, Rimner A, Simone C, Timmerman R, Zelefsky M, DeMarco J, Hamstra D, Lawton C, Potters L, Valicenti R, Mutic S, Bosch W, Abraham C, Caruthers D, Brame R, Palta JR, Sleeman W, and Nalluri J
- Subjects
- Carcinoma, Non-Small-Cell Lung radiotherapy, Evidence-Based Medicine standards, Humans, Lung Neoplasms radiotherapy, Male, Peer Review, Program Evaluation standards, Prostatic Neoplasms radiotherapy, Quality Assurance, Health Care methods, Quality Improvement standards, Quality Indicators, Health Care standards, Small Cell Lung Carcinoma radiotherapy, Societies, Medical standards, United States, Veterans, Cancer Care Facilities standards, Hospitals, Veterans standards, Program Development, Quality Assurance, Health Care standards, Radiation Oncology standards
- Abstract
Purpose: We sought to develop a quality surveillance program for approximately 15,000 US veterans treated at the 40 radiation oncology facilities at the Veterans Affairs (VA) hospitals each year., Methods and Materials: State-of-the-art technologies were used with the goal to improve clinical outcomes while providing the best possible care to veterans. To measure quality of care and service rendered to veterans, the Veterans Health Administration established the VA Radiation Oncology Quality Surveillance program. The program carries forward the American College of Radiology Quality Research in Radiation Oncology project methodology of assessing the wide variation in practice pattern and quality of care in radiation therapy by developing clinical quality measures (QM) used as quality indices. These QM data provide feedback to physicians by identifying areas for improvement in the process of care and identifying the adoption of evidence-based recommendations for radiation therapy., Results: Disease-site expert panels organized by the American Society for Radiation Oncology (ASTRO) defined quality measures and established scoring criteria for prostate cancer (intermediate and high risk), non-small cell lung cancer (IIIA/B stage), and small cell lung cancer (limited stage) case presentations. Data elements for 1567 patients from the 40 VA radiation oncology practices were abstracted from the electronic medical records and treatment management and planning systems. Overall, the 1567 assessed cases passed 82.4% of all QM. Pass rates for QM for the 773 lung and 794 prostate cases were 78.0% and 87.2%, respectively. Marked variations, however, were noted in the pass rates for QM when tumor site, clinical pathway, or performing centers were separately examined., Conclusions: The peer-review protected VA-Radiation Oncology Surveillance program based on clinical quality measures allows providers to compare their clinical practice to peers and to make meaningful adjustments in their personal patterns of care unobtrusively., (Copyright © 2019. Published by Elsevier Inc.)
- Published
- 2020
- Full Text
- View/download PDF
23. Hypofractionation in Prostate Cancer Using Proton Beam.
- Author
-
Quinn TJ and Hamstra D
- Subjects
- Humans, Male, Prospective Studies, Protons, Radiation Dose Hypofractionation, Prostatic Neoplasms, Proton Therapy
- Published
- 2019
- Full Text
- View/download PDF
24. Application of a Prognostic Stratification System for High-risk Prostate Cancer to Patients Treated With Radiotherapy: Implications for Treatment Optimization.
- Author
-
Foster B, Jackson W, Foster C, Dess R, Abu-Isa E, McLaughlin PW, Merrick G, Hearn J, Spratt D, Liauw S, and Hamstra D
- Subjects
- Aged, Follow-Up Studies, Humans, Male, Prognosis, Prostatic Neoplasms blood, Prostatic Neoplasms radiotherapy, Radiotherapy Dosage, Retrospective Studies, Risk Factors, Survival Rate, Brachytherapy mortality, Brachytherapy standards, Prostate-Specific Antigen blood, Prostatic Neoplasms pathology
- Abstract
Objectives: We applied an established prognostic model to high-risk prostate cancer (HRPC) patients treated with radiotherapy (RT) and evaluated the influence of clinical and treatment variables on treatment outcomes., Methods: In total, 1075 HRPC patients undergoing definitive radiotherapy (RT) between 1995 and 2010 were retrospectively reviewed. Median follow-up was 62.3 months. Patients received either dose-escalated external beam radiotherapy (n=628, EBRT) or combined-modality radiotherapy (n=447, pelvic RT and low-dose rate brachytherapy boost, CMRT). 82.9% received androgen-deprivation therapy (ADT). A prognostic model stratified patients into predefined groups (good, intermediate, and poor). Kaplan-Meier methods and Cox proportional hazards regressions assessed biochemical failure (BF), distant metastasis (DM), prostate cancer-specific mortality (PCSM) and overall mortality (OM). C-indices analyzed predictive value., Results: The model was prognostic; C-indices for BF, DM, PCSM and OM were: 0.62, 0.64, 0.61, and 0.57. On multivariate analysis, CMRT and longer ADT (≥24 mo) were associated with improved BF, DM, and PCSM. Gleason score (GS) 9-10 was the strongest predictor of PCSM. C-indices for BF, DM, PCSM, and OM using a 4-compartment model incorporating GS 9-10 were: 0.62, 0.65, 0.68, and 0.56. In poor-prognosis patients (GS 8-10+additional risk factors), CMRT+LTADT (>12 mo) had 10-year PCSM (3.7%±3.6%), comparing favorably to 25.8%±9.2% with EBRT+LTADT., Conclusions: The model applies to high-risk RT patients; GS 9-10 remains a powerful predictor of PCSM. Comparing similar prognosis patients, CMRT is associated with improved disease-specific outcomes relative to EBRT. In poor-prognosis patients, CMRT+LTADT yields superior 10-year PCSM, potentially improving RT treatment personalization for those with HRPC.
- Published
- 2019
- Full Text
- View/download PDF
25. Quality of life is not compromised with intensification of androgen therapy in recurrent prostate cancer.
- Author
-
Seymour Z and Hamstra D
- Subjects
- Androgen Antagonists, Humans, Male, Neoplasm Recurrence, Local, Quality of Life, Thiohydantoins, Prostatic Neoplasms, Prostatic Neoplasms, Castration-Resistant
- Published
- 2018
- Full Text
- View/download PDF
26. Knowledge-based treatment planning and its potential role in the transition between treatment planning systems.
- Author
-
Masi K, Archer P, Jackson W, Sun Y, Schipper M, Hamstra D, and Matuszak M
- Subjects
- Humans, Male, Prostatic Neoplasms radiotherapy, Radiotherapy Planning, Computer-Assisted
- Abstract
Commissioning a new treatment planning system (TPS) involves many time-consuming tasks. We investigated the role that knowledge-based planning (KBP) can play in aiding a clinic's transition to a new TPS. Sixty clinically treated prostate/prostate bed intensity-modulated radiation therapy (IMRT) plans were exported from an in-house TPS and were used to create a KBP model in a newly implemented commercial application. To determine the benefit that KBP may have in a TPS transition, the model was tested on 2 groups of patients. Group 1 consisted of the first 10 prostate/prostate bed patients treated in the commercial TPS after the transition from the in-house TPS. Group 2 consisted of 10 patients planned in the commercial TPS after 8 months of clinical use. The KBP-generated plan was compared with the clinically used plan in terms of plan quality (ability to meet planning objectives and overall dose metrics) and planning efficiency (time required to generate clinically acceptable plans). The KBP-generated plans provided a significantly improved target coverage (p = 0.01) compared with the clinically used plans for Group 1, but yielded plans of comparable target coverage to the clinically used plans for Group 2. For the organs at risk, the KBP-generated plans produced lower doses, on average, for every normal-tissue objective except for the maximum dose to 0.1 cc of rectum. The time needed for the KBP-generated plans ranged from 6 to 15 minutes compared to 30 to 150 and 15 to 60 minutes for manual planning in Groups 1 and 2, respectively. KBP is a promising tool to aid in the transition to a new TPS. Our study indicates that high-quality treatment plans could have been generated in the newly implemented TPS more efficiently compared with not using KBP. Even after 8 months of the clinical use, KBP still showed an increase in plan quality and planning efficiency compared with manual planning., (Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
27. Effect of Standard vs Dose-Escalated Radiation Therapy for Patients With Intermediate-Risk Prostate Cancer: The NRG Oncology RTOG 0126 Randomized Clinical Trial.
- Author
-
Michalski JM, Moughan J, Purdy J, Bosch W, Bruner DW, Bahary JP, Lau H, Duclos M, Parliament M, Morton G, Hamstra D, Seider M, Lock MI, Patel M, Gay H, Vigneault E, Winter K, and Sandler H
- Subjects
- Adult, Aged, Aged, 80 and over, Dose-Response Relationship, Radiation, Follow-Up Studies, Gastrointestinal Diseases etiology, Humans, Kaplan-Meier Estimate, Male, Male Urogenital Diseases etiology, Middle Aged, Neoplasm Grading, Neoplasm Metastasis, Prostate-Specific Antigen blood, Prostatic Neoplasms blood, Prostatic Neoplasms mortality, Prostatic Neoplasms pathology, Radiation Injuries epidemiology, Radiation Injuries etiology, Radiotherapy, Intensity-Modulated, Salvage Therapy statistics & numerical data, Treatment Outcome, Prostatic Neoplasms radiotherapy, Radiotherapy Dosage, Radiotherapy, Conformal
- Abstract
Importance: Optimizing radiation therapy techniques for localized prostate cancer can affect patient outcomes. Dose escalation improves biochemical control, but no prior trials were powered to detect overall survival (OS) differences., Objective: To determine whether radiation dose escalation to 79.2 Gy compared with 70.2 Gy would improve OS and other outcomes in prostate cancer., Design, Setting, and Participants: The NRG Oncology/RTOG 0126 randomized clinical trial randomized 1532 patients from 104 North American Radiation Therapy Oncology Group institutions March 2002 through August 2008. Men with stage cT1b to T2b, Gleason score 2 to 6, and prostate-specific antigen (PSA) level of 10 or greater and less than 20 or Gleason score of 7 and PSA less than 15 received 3-dimensional conformal radiation therapy or intensity-modulated radiation therapy to 79.2 Gy in 44 fractions or 70.2 Gy in 39 fractions., Main Outcomes and Measures: Time to OS measured from randomization to death due to any cause. American Society for Therapeutic Radiology and Oncology (ASTRO)/Phoenix definitions were used for biochemical failure. Acute (≤90 days of treatment start) and late radiation therapy toxic effects (>90 days) were graded using the National Cancer Institute Common Toxicity Criteria, version 2.0, and the RTOG/European Organisation for the Research and Treatment of Cancer Late Radiation Morbidity Scoring Scheme, respectively., Results: With a median follow-up of 8.4 (range, 0.02-13.0) years in 1499 patients (median [range] age, 71 [33-87] years; 70% had PSA <10 ng/mL, 84% Gleason score of 7, 57% T1 disease), there was no difference in OS between the 751 men in the 79.2-Gy arm and the 748 men in the 70.2-Gy arm. The 8-year rates of OS were 76% with 79.2 Gy and 75% with 70.2 Gy (hazard ratio [HR], 1.00; 95% CI, 0.83-1.20; P = .98). The 8-year cumulative rates of distant metastases were 4% for the 79.2-Gy arm and 6% for the 70.2-Gy arm (HR, 0.65; 95% CI, 0.42-1.01; P = .05). The ASTRO and Phoenix biochemical failure rates at 5 and 8 years were 31% and 20% with 79.2 Gy and 47% and 35% with 70.2 Gy, respectively (both P < .001; ASTRO: HR, 0.59; 95% CI, 0.50-0.70; Phoenix: HR, 0.54; 95% CI, 0.44-0.65). The high-dose arm had a lower rate of salvage therapy use. The 5-year rates of late grade 2 or greater gastrointestinal and/or genitourinary toxic effects were 21% and 12% with 79.2 Gy and 15% and 7% with 70.2 Gy (P = .006 [HR, 1.39; 95% CI, 1.10-1.77] and P = .003 [HR, 1.59; 95% CI, 1.17-2.16], respectively)., Conclusions and Relevance: Despite improvements in biochemical failure and distant metastases, dose escalation did not improve OS. High doses caused more late toxic effects but lower rates of salvage therapy., Trial Registration: clinicaltrials.gov Identifier: NCT00033631.
- Published
- 2018
- Full Text
- View/download PDF
28. Point: Which Treatment Modality for Localized Prostate Cancer Yields Superior Quality of Life: Radiotherapy or Prostatectomy? Quality of Life is Better After Modern Radiotherapy Compared With Surgery.
- Author
-
Yu JB and Hamstra D
- Subjects
- Humans, Male, Prostatic Neoplasms psychology, Prostatectomy, Prostatic Neoplasms radiotherapy, Prostatic Neoplasms surgery, Quality of Life
- Published
- 2017
29. Defining a standard set of patient-centered outcomes for men with localized prostate cancer.
- Author
-
Martin NE, Massey L, Stowell C, Bangma C, Briganti A, Bill-Axelson A, Blute M, Catto J, Chen RC, D'Amico AV, Feick G, Fitzpatrick JM, Frank SJ, Froehner M, Frydenberg M, Glaser A, Graefen M, Hamstra D, Kibel A, Mendenhall N, Moretti K, Ramon J, Roos I, Sandler H, Sullivan FJ, Swanson D, Tewari A, Vickers A, Wiegel T, and Huland H
- Subjects
- Consensus, Delphi Technique, Disease Progression, Disease-Free Survival, Drug-Related Side Effects and Adverse Reactions etiology, Humans, Male, Postoperative Complications etiology, Practice Patterns, Physicians' standards, Predictive Value of Tests, Prostatic Neoplasms mortality, Prostatic Neoplasms pathology, Quality Improvement standards, Quality of Life, Radiation Injuries etiology, Risk Assessment, Risk Factors, Time Factors, Treatment Outcome, Health Status, Health Status Indicators, Medical Oncology standards, Patient-Centered Care standards, Process Assessment, Health Care standards, Prostatic Neoplasms therapy, Quality Indicators, Health Care standards
- Abstract
Background: Value-based health care has been proposed as a unifying force to drive improved outcomes and cost containment., Objective: To develop a standard set of multidimensional patient-centered health outcomes for tracking, comparing, and improving localized prostate cancer (PCa) treatment value., Design, Setting, and Participants: We convened an international working group of patients, registry experts, urologists, and radiation oncologists to review existing data and practices., Outcome Measurements and Statistical Analysis: The group defined a recommended standard set representing who should be tracked, what should be measured and at what time points, and what data are necessary to make meaningful comparisons. Using a modified Delphi method over a series of teleconferences, the group reached consensus for the Standard Set., Results and Limitations: We recommend that the Standard Set apply to men with newly diagnosed localized PCa treated with active surveillance, surgery, radiation, or other methods. The Standard Set includes acute toxicities occurring within 6 mo of treatment as well as patient-reported outcomes tracked regularly out to 10 yr. Patient-reported domains of urinary incontinence and irritation, bowel symptoms, sexual symptoms, and hormonal symptoms are included, and the recommended measurement tool is the Expanded Prostate Cancer Index Composite Short Form. Disease control outcomes include overall, cause-specific, metastasis-free, and biochemical relapse-free survival. Baseline clinical, pathologic, and comorbidity information is included to improve the interpretability of comparisons., Conclusions: We have defined a simple, easily implemented set of outcomes that we believe should be measured in all men with localized PCa as a crucial first step in improving the value of care., Patient Summary: Measuring, reporting, and comparing identical outcomes across treatments and treatment centers will provide patients and providers with information to make informed treatment decisions. We defined a set of outcomes that we recommend being tracked for every man being treated for localized prostate cancer., (Copyright © 2014 European Association of Urology. Published by Elsevier B.V. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
30. Mineralocorticoid receptor haplotype, oral contraceptives and emotional information processing.
- Author
-
Hamstra DA, de Kloet ER, van Hemert AM, de Rijk RH, and Van der Does AJ
- Subjects
- Adult, Cross-Sectional Studies, Decision Making physiology, Emotions physiology, Facial Expression, Female, Haplotypes, Humans, Mental Recall physiology, Recognition, Psychology physiology, Young Adult, Contraceptives, Oral, Hormonal adverse effects, Decision Making drug effects, Emotions drug effects, Mental Recall drug effects, Receptors, Mineralocorticoid genetics, Recognition, Psychology drug effects
- Abstract
Background: Oral contraceptives (OCs) affect mood in some women and may have more subtle effects on emotional information processing in many more users. Female carriers of mineralocorticoid receptor (MR) haplotype 2 have been shown to be more optimistic and less vulnerable to depression., Aim: To investigate the effects of oral contraceptives on emotional information processing and a possible moderating effect of MR haplotype., Methods: Cross-sectional study in 85 healthy premenopausal women of West-European descent., Results: We found significant main effects of oral contraceptives on facial expression recognition, emotional memory and decision-making. Furthermore, carriers of MR haplotype 1 or 3 were sensitive to the impact of OCs on the recognition of sad and fearful faces and on emotional memory, whereas MR haplotype 2 carriers were not., Limitations: Different compounds of OCs were included. No hormonal measures were taken. Most naturally cycling participants were assessed in the luteal phase of their menstrual cycle., Conclusions: Carriers of MR haplotype 2 may be less sensitive to depressogenic side-effects of OCs., (Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
31. A comprehensive assessment of the prognostic utility of the Stephenson nomogram for salvage radiation therapy postprostatectomy.
- Author
-
Johnson S, Jackson W, Speers C, Feng F, and Hamstra D
- Subjects
- Aged, Cohort Studies, Humans, Male, Middle Aged, Neoadjuvant Therapy, Prognosis, Prostatectomy, Prostatic Neoplasms mortality, Prostatic Neoplasms pathology, Radiotherapy, Adjuvant, Nomograms, Prostatic Neoplasms radiotherapy, Salvage Therapy methods
- Abstract
Purpose: To investigate the prognostic utility of the Stephenson nomogram for clinically relevant endpoints, freedom from metastasis (FFM), and prostate cancer-specific survival (PCSS) in patients treated with salvage external beam radiation therapy (SRT) following a rising prostate-specific antigen (PSA) after radical prostatectomy (RP)., Methods and Materials: From an institutional cohort of 575 patients treated with SRT between 1986 and 2010, the Stephenson nomogram variables were retrospectively collected and available for 179 patients. The prognostic impact of the Stephenson nomogram on 6-year freedom from biochemical failure (FFBF), FFM, and PCSS was assessed on univariate and multivariate analysis using Kaplan-Meier and Cox proportional hazards models. The prognostic utility of the Stephenson nomogram was compared with individual pretreatment, treatment, and clinical characteristics using concordance indices., Results: In the 179 patients with all available nomogram variables, median follow-up was 85.0 months (interquartile range [IQR], 53-113) and 6-year FFBF, FFM, and PCSS were 38% (95% confidence interval [CI], 30-46), 79% (95% CI, 73-85), and 96% (95% CI, 92-100), respectively. Univariate analysis, demonstrated that the Stephenson nomogram, as a continuous variable and as a risk stratified group, was prognostic of FFBF (both, P < .0001), FFM (both, P < .0001), and PCSS (both, P ≤ .0005). When analyzing individual Stephenson nomogram variables, multivariate analysis revealed that positive surgical margins (P = .02; hazard ratio [HR], 0.4; 95% CI, 0.2-0.8) and pre-RT PSA (P = .0001; HR, 1.6; 95% CI, 1.3-2.0) were prognostic for FFM, while pre-RT PSA (P = .03; HR, 1.2; 95% CI, 1.0-1.4) was the only prognostic variable for PCSS. Concordance indices revealed the Stephenson nomogram to have superior prognostic capability for biochemical failure (0.71), distant metastasis (0.75), and prostate cancer-specific mortality (0.75) when compared with individual variables (BF all ≤ 0.65, DM all ≤ 0.67, PCSM all ≤ 0.71)., Conclusions: For patients treated with SRT for a rising PSA postprostatectomy, the Stephenson nomogram is an appropriate prognostic tool for estimating the response to treatment; however, there remains a need for improvement in current and future nomograms.
- Published
- 2014
- Full Text
- View/download PDF
32. Concurrent whole brain radiotherapy and bortezomib for brain metastasis.
- Author
-
Lao CD, Friedman J, Tsien CI, Normolle DP, Chapman C, Cao Y, Lee O, Schipper M, Van Poznak C, Hamstra D, Lawrence T, Hayman J, and Redman BG
- Subjects
- Adult, Aged, Antineoplastic Agents administration & dosage, Antineoplastic Agents adverse effects, Boronic Acids administration & dosage, Boronic Acids adverse effects, Bortezomib, Brain pathology, Cranial Irradiation adverse effects, Cranial Irradiation methods, Dose-Response Relationship, Drug, Female, Humans, Male, Maximum Tolerated Dose, Middle Aged, Pyrazines administration & dosage, Pyrazines adverse effects, Brain Neoplasms secondary, Brain Neoplasms therapy, Chemoradiotherapy methods
- Abstract
Background: Survival of patients with brain metastasis particularly from historically more radio-resistant malignancies remains dismal. A phase I study of concurrent bortezomib and whole brain radiotherapy was conducted to determine the tolerance and safety of this approach in patients with previously untreated brain metastasis., Methods: A phase I dose escalation study evaluated the safety of bortezomib (0.9, 1.1, 1.3, 1.5, and 1.7 mg/m2) given on days 1, 4, 8 and 11 of whole brain radiotherapy. Patients with confirmed brain metastasis were recruited for participation. The primary endpoint was the dose-limiting toxicity, defined as any ≥ grade 3 non-hematologic toxicity or grade ≥ 4 hematologic toxicity from the start of treatment to one month post irradiation. Time-to-Event Continual Reassessment Method (TITE-CRM) was used to determine dose escalation. A companion study of brain diffusion tensor imaging MRI was conducted on a subset of patients to assess changes in the brain that might predict delayed cognitive effects., Results: Twenty-four patients were recruited and completed the planned therapy. Patients with melanoma accounted for 83% of all participants. The bortezomib dose was escalated as planned to the highest dose of 1.7 mg/m2/dose. No grade 4/5 toxicities related to treatment were observed. Two patients had grade 3 dose-limiting toxicities (hyponatremia and encephalopathy). A partial or minor response was observed in 38% of patients. Bortezomib showed greater demyelination in hippocampus-associated white matter structures on MRI one month after radiotherapy compared to patients not treated with bortezomib (increase in radial diffusivity +16.8% versus 4.8%; p = 0.0023)., Conclusions: Concurrent bortezomib and whole brain irradiation for brain metastasis is well tolerated at one month follow-up, but MRI changes that have been shown to predict delayed cognitive function can be detected within one month of treatment.
- Published
- 2013
- Full Text
- View/download PDF
33. The interval to biochemical failure is prognostic for metastasis, prostate cancer-specific mortality, and overall mortality after salvage radiation therapy for prostate cancer.
- Author
-
Johnson S, Jackson W, Li D, Song Y, Foster C, Foster B, Zhou J, Vainshtein J, Feng F, and Hamstra D
- Subjects
- Aged, Analysis of Variance, Androgen Antagonists therapeutic use, Cause of Death, Humans, Male, Middle Aged, Prognosis, Proportional Hazards Models, Prostatectomy, Prostatic Neoplasms blood, Prostatic Neoplasms pathology, Radiotherapy, Conformal, Retrospective Studies, Time Factors, Treatment Failure, Prostate-Specific Antigen blood, Prostatic Neoplasms mortality, Prostatic Neoplasms radiotherapy, Salvage Therapy mortality
- Abstract
Purpose: To investigate the utility of the interval to biochemical failure (IBF) after salvage radiation therapy (SRT) after radical prostatectomy (RP) for prostate cancer as a surrogate endpoint for distant metastasis (DM), prostate cancer-specific mortality (PCSM), and overall mortality (OM)., Methods and Materials: A retrospective analysis of 575 patients treated with SRT after RP from a single institution. Of those, 250 patients experienced biochemical failure (BF), with the IBF defined as the time from commencement of SRT to BF. The IBF was evaluated by Kaplan-Meier and Cox proportional hazards models for its association with DM, PCSM, and OM., Results: The median follow-up time was 85 (interquartile range [IQR] 49.8-121.1) months, with a median IBF of 16.8 (IQR, 8.5-37.1) months. With a cutoff time of 18 months, as previously used, 129 (52%) of patients had IBF ≤18 months. There were no differences among any clinical or pathologic features between those with IBF ≤ and those with IBF >18 months. On log-rank analysis, IBF ≤18 months was prognostic for increased DM (P<.0001, HR 4.9, 95% CI 3.2-7.4), PCSM (P<.0001, HR 4.1, 95% CI 2.4-7.1), and OM (P<.0001, HR 2.7, 95% CI 1.7-4.1). Cox proportional hazards models with adjustment for other clinical variables demonstrated that IBF was independently prognostic for DM (P<.001, HR 4.9), PCSM (P<.0001, HR 4.0), and OM (P<.0001, HR 2.7). IBF showed minimal change in performance regardless of androgen deprivation therapy (ADT) use., Conclusion: After SRT, a short IBF can be used for early identification of patients who are most likely to experience progression to DM, PCSM, and OM. IBF ≤18 months may be useful in clinical practice or as an endpoint for clinical trials., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
34. The extent and severity of vascular leakage as evidence of tumor aggressiveness in high-grade gliomas.
- Author
-
Cao Y, Nagesh V, Hamstra D, Tsien CI, Ross BD, Chenevert TL, Junck L, and Lawrence TS
- Subjects
- Adult, Aged, Glioma blood supply, Glioma mortality, Glioma radiotherapy, Humans, Magnetic Resonance Imaging, Middle Aged, Neovascularization, Pathologic pathology, Predictive Value of Tests, Radiotherapy, Conformal, Survival Analysis, Survivors, Capillary Permeability, Glioma pathology
- Abstract
Magnetic resonance imaging reveals heterogeneous regions within high-grade gliomas, such as a contrast-enhanced rim, a necrotic core, and non-contrast-enhanced abnormalities. It is unclear which of these regions best describes tumor aggressiveness. We hypothesized that the vascular leakage volume, reflecting disorganized angiogenesis typical of glioblastoma, would be a strong predictor of clinical outcome. The FLAIR tumor volume, post-gadolinium T1 tumor volume, tumor vascular leakage volume determined by dynamic contrast-enhanced imaging, and volume of the contrast-enhanced rim seen on post-gadolinium T1-weighted images were defined for 20 patients about to undergo treatment for newly diagnosed high-grade gliomas. The potential for imaging characteristics to improve prediction of survival and time to progression over clinical variables was tested by using Cox regression analysis. Single-variable Cox regression analysis of each of the four tumor subvolumes revealed that the vascular leakage volume was the only significant predictor of survival. When the joint effect of clinical variables and the vascular leakage volume were tested for prediction of survival, only the age and the vascular leakage volume were selected as significant predictors. However, when time to progression was tested as a dependent variable, both the vascular leakage volume and the vascular permeability were selected as copredictors, along with surgical status. Our findings suggest that for patients with high-grade glioma, time to progression after radiation therapy is influenced by both underlying biological aggressiveness (vascularity) and volume of aggressive tumor. In contrast, survival depends chiefly on the volume of aggressive tumor at the time of presentation.
- Published
- 2006
- Full Text
- View/download PDF
35. Combined effect of tumor necrosis factor-related apoptosis-inducing ligand and ionizing radiation in breast cancer therapy.
- Author
-
Chinnaiyan AM, Prasad U, Shankar S, Hamstra DA, Shanaiah M, Chenevert TL, Ross BD, and Rehemtulla A
- Subjects
- Animals, Apoptosis drug effects, Apoptosis Regulatory Proteins, Cell Division drug effects, Cell Division radiation effects, DNA Fragmentation drug effects, DNA Fragmentation radiation effects, Female, Humans, In Situ Nick-End Labeling, Magnetic Resonance Imaging, Membrane Glycoproteins genetics, Mice, Mice, Inbred Strains, Neoplasm Transplantation, Radiation, Ionizing, Receptors, TNF-Related Apoptosis-Inducing Ligand, Receptors, Tumor Necrosis Factor metabolism, Recombinant Proteins, TNF-Related Apoptosis-Inducing Ligand, Tumor Cells, Cultured, Tumor Necrosis Factor-alpha genetics, Breast Neoplasms drug therapy, Breast Neoplasms radiotherapy, Membrane Glycoproteins therapeutic use, Tumor Necrosis Factor-alpha therapeutic use
- Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent endogenous activator of the cell death pathway and functions by activating the cell surface death receptors 4 and 5 (DR4 and DR5). TRAIL is nontoxic in vivo and preferentially kills neoplastically transformed cells over normal cells by an undefined mechanism. Radiotherapy is a common treatment for breast cancer as well as many other cancers. Here we demonstrate that ionizing radiation can sensitize breast carcinoma cells to TRAIL-induced apoptosis. This synergistic effect is p53-dependent and may be the result of radiation-induced up-regulation of the TRAIL-receptor DR5. Importantly, TRAIL and ionizing radiation have a synergistic effect in the regression of established breast cancer xenografts. Changes in tumor cellularity and extracellular space were monitored in vivo by diffusion-weighted magnetic resonance imaging (diffusion MRI), a noninvasive technique to produce quantitative images of the apparent mobility of water within a tissue. Increased water mobility was observed in combined TRAIL- and radiation-treated tumors but not in tumors treated with TRAIL or radiation alone. Histological analysis confirmed the loss of cellularity and increased numbers of apoptotic cells in TRAIL- and radiation-treated tumors. Taken together, our results provide support for combining radiation with TRAIL to improve tumor eradication and suggest that efficacy of apoptosis-inducing cancer therapies may be monitored noninvasively, using diffusion MRI.
- Published
- 2000
- Full Text
- View/download PDF
36. Expression of endogenously activated secreted or cell surface carboxypeptidase A sensitizes tumor cells to methotrexate-alpha-peptide prodrugs.
- Author
-
Hamstra DA, Pagé M, Maybaum J, and Rehemtulla A
- Subjects
- Carboxypeptidases A, Carcinoma, Squamous Cell enzymology, Dose-Response Relationship, Drug, Enzyme Activation, Humans, Methotrexate metabolism, Methotrexate pharmacology, Phenylalanine metabolism, Phenylalanine pharmacology, Time Factors, Trypsin pharmacology, Tumor Cells, Cultured, Antineoplastic Agents pharmacology, Carboxypeptidases physiology, Methotrexate analogs & derivatives, Phenylalanine analogs & derivatives, Prodrugs pharmacology
- Abstract
Methotrexate (MTX) is one of the most commonly used agents in the treatment of solid malignancies; however, the toxicities of MTX to bone marrow and gastrointestinal tract complicate this therapy. We, therefore, propose a gene-dependent enzyme prodrug therapy to limit these toxicities by localizing the production of MTX to the site of the tumor. The combination of MTX-alpha-peptide prodrugs, which cannot be internalized by the cellular reduced folate carrier, with carboxypeptidase A (CPA), which can remove the blocking peptide, has been demonstrated previously in vitro using antibody-dependent enzyme prodrug therapy. CPA is normally synthesized as a zymogen that is inactive without proteolytic removal of its propeptide by trypsin. Therefore, to adapt this system to gene-dependent enzyme prodrug therapy, a mutant form of CPA was engineered, CPA(ST3), that does not require trypsin-dependent zymogen cleavage but is instead activated by ubiquitously expressed intracellular propeptidases. Purification, peptide sequencing, and kinetic analysis indicated that mature CPA(ST3) is structurally and functionally similar to the trypsin-activated, wild-type enzyme. In addition, CPA(ST3)-expressing tumors cells were sensitized to MTX prodrugs in a dose- and time-dependent manner. To limit diffusion of CPA, a cell surface localized form was generated by constructing a fusion protein between CPA(ST3) and the phosphatidylinositol linkage domain from decay accelerating factor. SDS-PAGE and flow cytometric analysis of infected tumor cells indicated that CPA(DAF) was cell surface localized. Finally, after retroviral transduction, this enzyme/prodrug strategy exhibited a potent bystander effect, even when <10% of the cells were transduced, because extracellular production of MTX sensitized both transduced and nontransduced cells.
- Published
- 2000
37. Combined radiation and enzyme/prodrug treatment for head and neck cancer in an orthotopic animal model.
- Author
-
Hamstra DA, Rice DJ, Pu A, Oyedijo D, Ross BD, and Rehemtulla A
- Subjects
- Animals, Antimetabolites, Antineoplastic therapeutic use, Carcinoma, Squamous Cell drug therapy, Carcinoma, Squamous Cell radiotherapy, Cell Division, Combined Modality Therapy, Cytosine Deaminase, Disease Models, Animal, Head and Neck Neoplasms drug therapy, Head and Neck Neoplasms radiotherapy, Mice, Retroviridae genetics, Transduction, Genetic, Tumor Cells, Cultured, Carcinoma, Squamous Cell therapy, Flucytosine therapeutic use, Head and Neck Neoplasms therapy, Nucleoside Deaminases therapeutic use, Prodrugs therapeutic use
- Abstract
In an effort to improve the therapeutic outcome for squamous cell cancer of the head and neck, we have used the enzyme cytosine deaminase (CD) and the prodrug 5-fluorocytosine (5-FC) as a means to deliver the chemotherapeutic agent 5-fluorouracil (5-FU) in a tumor-specific manner and have evaluated the use of this treatment in combination with external-beam radiation. Infection of SCCVII cells in culture with a CD-expressing retrovirus and treatment with 5-FC was cytotoxic depending on the time of treatment and dose of 5-FC. An orthotopic model of squamous cell cancer of the head and neck was used in vivo to study the CD/5-FC system both alone and with concurrent radiation due to the radiosensitizing properties that 5-FU generates in situ. Treated mice were imaged using magnetic resonance imaging (MRI), and their survival was evaluated. Neither 5-FU nor radiation either alone or combined provided a survival advantage. In contrast, 5-FC treatment prolonged survival and decreased tumor burden compared to control animals, but the tumors recurred after the treatment ceased. Finally, combined treatment with concurrent administration of 5-FC and radiation resulted in a synergistic decrease in tumor growth and enhanced survival over treatment with 5-FC or radiation alone.
- Published
- 1999
38. Enzyme/prodrug therapy for head and neck cancer using a catalytically superior cytosine deaminase.
- Author
-
Hamstra DA, Rice DJ, Fahmy S, Ross BD, and Rehemtulla A
- Subjects
- Animals, Antifungal Agents administration & dosage, COS Cells, Cytosine Deaminase, Escherichia coli enzymology, Flucytosine administration & dosage, Genetic Vectors, Mice, Retroviridae genetics, Saccharomyces cerevisiae enzymology, Tumor Cells, Cultured, Carcinoma, Squamous Cell therapy, Genetic Therapy methods, Head and Neck Neoplasms therapy, Nucleoside Deaminases genetics, Prodrugs administration & dosage
- Abstract
The use of cytosine deaminase (CD) in conjunction with 5-fluorocytosine (5-FC) has been studied for cancer gene therapy as a means of achieving tumor-specific generation of the toxic metabolite 5-fluorouracil (5-FU). Since 5-FC is frequently used as an antifungal agent, and because it has little or no efficacy as an antibacterial agent, we hypothesized that yeast CD (YCD) might be more efficient at utilizing 5-FC as a substrate and hence be a better choice for a CD/5-FC gene therapy strategy than the typically utilized bacterial CD (BCD). To that end Saccharomyces cerevisiae CD was cloned from yeast genomic DNA and expressed in vitro. Functional analysis of BCD and YCD expressed in COS-1 cells indicated that BCD and YCD both utilized cytosine with equal efficacy; however, 5-FC was an extremely poor substrate for BCD, with an apparent catalytic efficiency 280-fold lower than that observed for YCD. Retroviral infection of tumor cell lines in vitro indicated that the IC50 of 5-FC was 30-fold lower in YCD-infected cultures as compared with cultures infected with BCD retrovirus. In addition, when SCCVII murine squamous cell carcinoma cells were infected in vitro at low rates of infection (< or =10%) there was no significant cytotoxicity toward BCD-expressing cells while there was potent cytotoxicity to both YCD-expressing cells and "bystander cells" even at this low level of expression. Finally, stable BCD- or YCD-expressing SCCVII clones were developed and used in an orthotopic immune-competent model of head and neck cancer. Subsequent treatment with 5-FC followed by monitoring of tumor growth by noninvasive magnetic resonance imaging (MRI) and survival of animals indicated a growth delay during the course of 5-FC treatment for BCD-expressing tumors, which quickly regrew at the end of treatment. In contrast, YCD-expressing tumors exhibited not only a growth delay, which was of longer duration, but also in some cases frank tumor regression and complete cures occurred.
- Published
- 1999
- Full Text
- View/download PDF
39. Carboxy-terminal conversion of profibrillin to fibrillin at a basic site by PACE/furin-like activity required for incorporation in the matrix.
- Author
-
Raghunath M, Putnam EA, Ritty T, Hamstra D, Park ES, Tschödrich-Rotter M, Peters R, Rehemtulla A, and Milewicz DM
- Subjects
- Animals, COS Cells, DNA Primers, Dose-Response Relationship, Drug, Egtazic Acid pharmacology, Fibrillins, Furin, Microscopy, Confocal, Models, Biological, Mutagenesis, Site-Directed, Recombinant Proteins, Subtilisins antagonists & inhibitors, Transforming Growth Factor beta metabolism, Extracellular Matrix metabolism, Microfilament Proteins metabolism, Protein Precursors metabolism, Subtilisins metabolism
- Abstract
Fibrillin-1, the main component of 10-12 nm microfibrils of the extracellular matrix, is synthesized as profibrillin and proteolytically processed to fibrillin. The putative cleavage site has been mapped to the carboxy-terminal domain of profibrillin-1, between amino acids arginine 2731 and serine 2732, by a spontaneous mutation in this recognition site that prevents profibrillin conversion. This site contains a basic amino acid recognition sequence (R-G-R-K-R-R) for proprotein convertases of the furin/PACE family. In this study, we use a mini-profibrillin protein to confirm the cleavage in the carboxy-terminal domain by both fibroblasts and recombinantly expressed furin/PACE, PACE4, PC1/3 and PC2. Site-directed mutagenesis of amino acids in the consensus recognition motif prevented conversion, thereby identifying the scissile bond and characterizing the basic amino acids required for cleavage. Using a PACE/furin inhibitor, we show that wild-type profibrillin is not incorporated into the extracellular matrix until it is converted to fibrillin. Therefore, profibrillin-1 is the first extracellular matrix protein to be shown to be a substrate for subtilisin-like proteases, and the conversion of profibrillin to fibrillin controls microfibrillogenesis through exclusion of uncleaved profibrillin.
- Published
- 1999
- Full Text
- View/download PDF
40. Toward an enzyme/prodrug strategy for cancer gene therapy: endogenous activation of carboxypeptidase A mutants by the PACE/Furin family of propeptidases.
- Author
-
Hamstra DA and Rehemtulla A
- Subjects
- Animals, Base Sequence, COS Cells, Carboxypeptidases genetics, Carboxypeptidases A, Catalytic Domain, Cloning, Molecular, DNA Primers, Enzyme Activation, Mice, Mutagenesis, Protein Processing, Post-Translational, Rats, Recombinant Proteins genetics, Recombinant Proteins metabolism, Tumor Cells, Cultured, Carboxypeptidases metabolism, Genetic Therapy, Neoplasms, Experimental therapy, Prodrugs therapeutic use, Subtilisins metabolism
- Abstract
In an effort to develop a gene-dependent enzyme/prodrug therapy (GDEPT) for tumor-specific delivery of methotrexate (MTX) we have chosen to construct mutant forms of carboxypeptidase A1 (CPA) that circumvent the requirement for trypsin-dependent activation. The basis of this strategy is that methotrexate-alpha-peptides are inefficient substrates for the reduced folate carrier (RFC) and hence cannot be internalized by cells. However, the blocking amino acid can be cleaved by CPA to liberate MTX, which is then internalized by the RFC, resulting in inhibition of dihydrofolate reductase and cytotoxicity. A battery of mutant CPAs was generated, in which the putative trypsin cleavage sites in the propeptide were mutated to the consensus recognition sequence for mammalian subtilisin-like propeptidases. These mutant forms of CPA were evaluated for expression, activation, and catalytic activity by transiently transfecting them into COS-1 cells both in the absence and in the presence of cotransfected propeptidases. CPA95 was identified as the most efficiently cleaved mutant, and further studies of this mutant indicated that the endogenously activated enzyme had kinetic parameters identical to those of the trypsin-activated wild-type protein. In addition, endogenously activated CPA95 could effectively sensitize cells to MTX-Phe in culture, decreasing the IC50 of MTX-Phe from 25- to 250-fold in squamous cell carcinoma cells expressing active CPA as compared with the parental lines.
- Published
- 1999
- Full Text
- View/download PDF
41. Lack of cell surface Fas/APO-1 expression in pulmonary adenocarcinomas.
- Author
-
Nambu Y, Hughes SJ, Rehemtulla A, Hamstra D, Orringer MB, and Beer DG
- Subjects
- Aged, Animals, Antigens, Surface immunology, Antigens, Surface metabolism, Apoptosis immunology, Blotting, Northern, Blotting, Southern, Blotting, Western, COS Cells, Cytoplasm metabolism, DNA genetics, DNA isolation & purification, DNA, Complementary, Female, Flow Cytometry, Gene Expression, Genetic Vectors, Humans, Immunohistochemistry, Male, Microscopy, Confocal, Middle Aged, Oligopeptides, Peptides immunology, Polymerase Chain Reaction, RNA, Messenger analysis, RNA, Messenger metabolism, Transfection, Tumor Cells, Cultured, fas Receptor genetics, fas Receptor immunology, Adenocarcinoma immunology, Adenocarcinoma metabolism, Lung Neoplasms immunology, Lung Neoplasms metabolism, fas Receptor metabolism
- Abstract
The Fas receptor and ligand initiate an apoptotic pathway. Alterations in this pathway within tumor cells can result in escape from apoptosis and immune surveillance. We evaluated Fas protein expression in 42 primary pulmonary adenocarcinomas, and Fas expression and function in the lung adenocarcinoma cell lines A549 and A427. Immunohistochemical analysis demonstrated Fas protein expression in 47.6% of the tumors; however, Fas-positive tumors demonstrated cytoplasmic staining without cell surface expression. Northern blot analysis indicated that levels of Fas mRNA were similar in Fas protein-positive tumors to levels in normal lung tissue, but were reduced in Fas protein-negative tumors. Soluble form Fas was not detected in the majority of these tumors either by RT-PCR or Western blot analysis. Cell surface Fas protein expression was minimal in A549 and A427 cell lines as determined by flow cytometry. Both cell lines demonstrated Fas mRNA expression by Northern blot analysis and abundant protein expression by Western blot analysis. Transfection of the Fas cDNA derived from A549 cells induced surface Fas protein in COS cells; however, stable transfection of a native Fas cDNA into A549 cells failed to induce surface Fas protein expression. Parental A549 cells and A549 cells transfected with a Fas expression vector were resistant to Fas-mediated apoptosis. Transgenic expression of a FLAG-tagged Fas cDNA in A549 cells, with visualization of the Fas-FLAG protein using confocal microscopy, demonstrated that the Fas-FLAG protein was retained within cytoplasmic portions of the cell and was not translocated to the cell surface. These findings suggest that the Fas protein is reduced or not present on the cell surface in the primary lung tumors and is sequestered within A549 tumorigenic lung cells, and these alterations directly affect the cells resistance to Fas-mediated apoptosis.
- Published
- 1998
- Full Text
- View/download PDF
42. Fas/APO-1 (CD95) is not translocated to the cell membrane in esophageal adenocarcinoma.
- Author
-
Hughes SJ, Nambu Y, Soldes OS, Hamstra D, Rehemtulla A, Iannettoni MD, Orringer MB, and Beer DG
- Subjects
- Adenocarcinoma pathology, Animals, Apoptosis physiology, Barrett Esophagus complications, Barrett Esophagus metabolism, Blotting, Southern, COS Cells metabolism, Cell Membrane metabolism, DNA analysis, DNA genetics, DNA, Neoplasm analysis, DNA, Neoplasm genetics, Epithelium metabolism, Esophageal Neoplasms pathology, Humans, Immunohistochemistry, Risk Factors, Tumor Cells, Cultured, fas Receptor biosynthesis, fas Receptor genetics, Adenocarcinoma metabolism, Esophageal Neoplasms metabolism, fas Receptor metabolism
- Abstract
This study describes Fas (CD95) expression in Barrett's esophagus, adenocarcinomas of the esophagus, and three esophageal adenocarcinoma cell lines. Immunohistochemical analysis of Barrett's esophagus demonstrated cell surface expression of Fas protein. In contrast, 30.5% of esophageal adenocarcinomas examined by immunohistochemical analysis demonstrated faint cytoplasmic staining, and 69.5% were negative for Fas. Similar levels of Fas mRNA were identified in tumors compared to mRNA levels in esophageal squamous mucosa or Barrett's esophagus. An approximately Mr 48,000 Fas protein was identified by Western blot analysis in tumors that were negative for Fas expression by immunohistochemical analysis. The esophageal adenocarcinoma cell line Seg-1 was negative for Fas expression by immunohistochemical analysis, but Western blot analysis demonstrated abundant, appropriately sized Fas protein. In agreement with the immunohistochemical analysis, flow cytometry of Seg-1 showed minimal amounts of Fas on the cell surface, which correlated with resistance to Fas-mediated apoptosis. No mutations in the Seg-1 Fas coding sequence or exon 1 were identified by sequence analysis. This was confirmed by transient transfection of COS cells with expression vectors generated from the Seg-1 Fas cDNA, which resulted in cell surface expression of the Fas protein. Stable transfection of Seg-1 with a Fas expression vector did not result in efficient Fas expression on the cell surface. Seg-1 cells, transiently transfected with a Fas-FLAG expression vector and examined for protein expression using confocal microscopy and an anti-FLAG antibody, showed that the Fas-FLAG protein was not present on the cell surface but was present in the cytoplasm. Taken together, these results indicate that expression of Fas on the cell surface by esophageal adenocarcinoma is reduced. In an esophageal adenocarcinoma cell line, wild-type Fas protein is retained in the cytoplasm, and this correlates with resistance to Fas-mediated apoptosis. The retention of wild-type Fas protein within the cytoplasm may represent a mechanism by which malignant cells evade Fas-mediated apoptosis.
- Published
- 1997
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.