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As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer.

Outcomes for poor-risk localized prostate cancers treated with radiation are still insufficient. Targeting the "non-oncogene" addiction or stress response machinery is an appealing strategy for cancer therapeutics. Heat-shock-protein-90 (Hsp90), an integral member of this machinery, is a molecular chaperone required for energy-driven stabilization and selective degradation of misfolded "client" proteins, that is commonly overexpressed in tumor cells. Hsp90 client proteins include critical components of pathways implicated in prostate cancer cell survival and radioresistance, such as androgen receptor signaling and the PI3K-Akt-mTOR pathway. We examined the effects of a novel non-geldanamycin Hsp90 inhibitor, AUY922, combined with radiation (RT) on two prostate cancer cell lines, Myc-CaP and PC3, using in vitro assays for clonogenic survival, apoptosis, cell cycle distribution, γ-H2AX foci kinetics and client protein expression in pathways important for prostate cancer survival and radioresistance. We then evaluated tumor growth delay and effects of the combined treatment (RT-AUY922) on the PI3K-Akt-mTOR and AR pathways in a hind-flank tumor graft model. We observed that AUY922 caused supra-additive radiosensitization in both cell lines at low nanomolar doses with enhancement ratios between 1.4-1.7 (p < 0.01). RT-AUY922 increased apoptotic cell death compared with either therapy alone, induced G 2-M arrest and produced marked changes in client protein expression. These results were confirmed in vivo, where RT-AUY922 combination therapy produced supra-additive tumor growth delay compared with either therapy by itself in Myc-CaP and PC3 tumor grafts (both p < 0.0001). Our data suggest that combined RT-AUY922 therapy exhibits promising activity against prostate cancer cells, which should be investigated in clinical studies.

Aim: To compare the measured surface temperature of variable size ensembles of cells heated by intracellular magnetic fluid hyperthermia with heat diffusion model predictions., Materials & Methods: Starch-coated Bionized NanoFerrite (Micromod Partikeltechnologie GmbH, Rostock, Germany) iron oxide magnetic nanoparticles were loaded into cultured DU145 prostate cancer cells. Cell pellets of variable size were treated with alternating magnetic fields. The surface temperature of the pellets was measured in situ and the associated cytotoxicity was determined by clonogenic survival assay., Results & Conclusion: For a given intracellular nanoparticle concentration, a critical minimum number of cells was required for cytotoxic hyperthermia. Above this threshold, cytotoxicity increased with increasing cell number. The measured surface temperatures were consistent with those predicted by a heat diffusion model that ignores intercellular thermal barriers. These results suggest a minimum tumor volume threshold of approximately 1 mm(3), below which nanoparticle-mediated heating is unlikely to be effective as the sole cytotoxic agent.

Purpose: Direct-to-consumer advertising by industry has been criticized for encouraging overuse of unproven therapies, but advertising by health care providers has not been as carefully scrutinized. Stereotactic radiation therapy is an emerging technology that has sparked controversy regarding the marketing campaigns of some manufacturers. Given that this technology is also being heavily advertised on the Web sites of health care providers, the accuracy of providers' marketing claims should be rigorously evaluated., Methods: We reviewed the Web sites of all U.S. hospitals and private practices that provide stereotactic radiation using two leading brands of stereotactic radiosurgery technology. Centers were identified by using data from the manufacturers. Centers without Web sites were excluded. The final study population consisted of 212 centers with online advertisements for stereotactic radiation. Web sites were evaluated for advertisements that were inconsistent with advertising guidelines provided by the American Medical Association., Results: Most centers (76%) had individual pages dedicated to the marketing of their brand of stereotactic technology that frequently contained manufacturer-authored images (50%) or text (55%). Advertising for the treatment of tumors that have not been endorsed by professional societies was present on 66% of Web sites. Centers commonly claimed improved survival (22%), disease control (20%), quality of life (17%), and toxicity (43%) with stereotactic radiation. Although 40% of Web sites championed the center's regional expertise in delivering stereotactic treatments, only 15% of Web sites provided data to support their claims., Conclusion: Provider advertisements for stereotactic radiation were prominent and aggressive. Further investigation of provider advertising, its effects on quality of care, and potential oversight mechanisms is needed.

Purpose: Solenoid coils that generate time-varying or alternating magnetic fields (AMFs) are used in biomedical devices for research, imaging and therapy. Interactions of AMF and tissue produce eddy currents that deposit power within tissue, thus limiting effectiveness and safety. We aim to develop methods that minimise excess heating of mice exposed to AMFs for cancer therapy experiments., Materials and Methods: Numerical and experimental data were obtained to characterise thermal management properties of water using a continuous, custom water jacket in a four-turn simple solenoid. Theoretical data were obtained with method-of-moments (MoM) numerical field calculations and finite element method (FEM) thermal simulations. Experimental data were obtained from gel phantoms and mice exposed to AMFs having amplitude >50 kA/m and frequency of 160 kHz., Results: Water has a high specific heat and thermal conductivity, is diamagnetic, polar, and nearly transparent to magnetic fields. We report at least a two-fold reduction of temperature increase from gel phantom and animal models when a continuous layer of circulating water was placed between the sample and solenoid, compared with no water. Thermal simulations indicate the superior efficiency in thermal management by the developed continuous single chamber cooling system over a double chamber non-continuous system. Further reductions of heating were obtained by regulating water temperature and flow for active cooling., Conclusions: These results demonstrate the potential value of a contiguous layer of circulating water to permit sustained exposure to high intensity alternating magnetic fields at this frequency for research using small animal models exposed to AMFs.

Aim: To assess the potential for injury to normal tissues in mice due to heating systemically delivered magnetic nanoparticles in an alternating magnetic field (AMF)., Materials & Methods: Twenty three male nude mice received intravenous injections of dextran-superparamagnetic iron oxide nanoparticles on days 1-3. On day 6, they were exposed to AMF. On day 7, blood, liver and spleen were harvested and analyzed., Results: Iron deposits were detected in the liver and spleen. Mice that had received a high-particle dose and a high AMF experienced increased mortality, elevated liver enzymes and significant liver and spleen necrosis. Mice treated with low-dose superparamagnetic iron oxide nanoparticles and a low AMF survived, but had elevated enzyme levels and local necrosis in the spleen., Conclusion: Magnetic nanoparticles producing only modest heat output can cause damage, and even death, when sequestered in sufficient concentrations. Dextran-superparamagnetic iron oxide nanoparticles are deposited in the liver and spleen, making these the sites of potential toxicity. Original submitted 16 August 2011; Revised submitted 21 March 2012; Published online 26 July 2012.

Purpose: We have previously shown that the antimalarial agent chloroquine can abrogate the lethal cellular effects of low-dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo., Methods and Materials: C57BL/6 mice were irradiated with a total of 12.8 Gy delivered at 9.4 cGy/hour. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 μg per 17 g of body weight, 24 hours and 4 hours before irradiation. Bone marrow cells isolated from tibia, fibula, and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retroorbital injection. Chimerism was assessed by flow cytometry. In vitro methylcellulose colony-forming assay of whole bone marrow cells and fluorescence activated cell sorting analysis of lineage depleted cells were used to assess the effect of chloroquine on progenitor cells., Results: Mice pretreated with chloroquine before radiation exhibited a significantly higher survival rate than did mice treated with radiation alone (80% vs. 31%, p = 0.0026). Chloroquine administration before radiation did not affect the survival of ATM null mice (p = 0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after transplantation (4.2% vs. 0.4%, p = 0.015)., Conclusion: Chloroquine administration before radiation had a significant effect on the survival of normal but not ATM null mice, strongly suggesting that the in vivo effect, like the in vitro effect, is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR-irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection against the harmful effects of LDR radiation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Purpose: To describe outcomes with the use of neoadjuvant pelvic chemoradiation followed by prostate interstitial brachytherapy for the treatment of synchronous prostate and rectal cancers., Methods and Materials: An Internal Review Board approved retrospective review was undertaken of 4 patients with synchronous prostate and rectal cancer treated between 2006 and 2008. Patients underwent pelvic chemoradiation followed by prostate brachytherapy, then low anterior resection of the rectum with diverting loop ileostomy and adjuvant chemotherapy. Follow-up evaluation included imaging and laboratory analysis of cancer markers in addition to routine interval history and physical examination., Results: At 38-62 months postdiagnosis (24-53 months post-treatment), 6 of 8 cancers remained without evidence of relapse. One patient had rising carcinoembryonic antigen levels but no clinically evident rectal cancer relapse; another developed bony metastasis of his high-risk prostate cancer. Three patients experienced grade 1-2 treatment-related toxicity; one patient had grade 3 gastrointestinal toxicity from radiation and surgery, which precluded his receiving adjuvant chemotherapy and ileostomy reversal., Conclusions: Chemoradiation followed by prostate brachytherapy, surgery, and adjuvant chemotherapy may be utilized to manage patients with synchronous prostate and rectal cancers., (Copyright © 2012 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

In this paper, we describe a modified solenoid coil that efficiently generates high amplitude alternating magnetic fields (AMF) having field uniformity (≤10%) within a 125-cm 3 volume of interest. Two-dimensional finite element analysis (2D-FEA) was used to design a coil generating a targeted peak AMF amplitude along the coil axis of ~100 kA/m (peak-to-peak) at a frequency of 150 kHz while maintaining field uniformity to >90% of peak for a specified volume. This field uniformity was realized by forming the turns from cylindrical sections of copper plate and by adding flux concentrating rings to both ends of the coil. Following construction, the field profile along the axes of the coil was measured. An axial peak field value of 95.8 ± 0.4 kA/m was measured with 650 V applied to the coil and was consistent with the calculated results. The region of axial field uniformity, defined as the distance over which field ≥90% of peak, was also consistent with the simulated results. We describe the utility of such a device for calorimetric measurement of nanoparticle heating for cancer therapy and for magnetic fluid hyperthermia in small animal models of human cancer.

Prostate cancer is the most common cancer and second leading cause of cancer deaths among men in the United States. Most men have localized disease diagnosed following an elevated serum prostate specific antigen test for cancer screening purposes. Standard treatment options consist of surgery or definitive radiation therapy directed by clinical factors that are organized into risk stratification groups. Current clinical risk stratification systems are still insufficient to differentiate lethal from indolent disease. Similarly, a subset of men in poor risk groups need to be identified for more aggressive treatment and enrollment into clinical trials. Furthermore, these clinical tools are very limited in revealing information about the biologic pathways driving these different disease phenotypes and do not offer insights for novel treatments which are needed in men with poor-risk disease. We believe molecular biomarkers may serve to bridge these inadequacies of traditional clinical factors opening the door for personalized treatment approaches that would allow tailoring of treatment options to maximize therapeutic outcome. We review the current state of prognostic and predictive tissue-based molecular biomarkers which can be used to direct localized prostate cancer treatment decisions, specifically those implicated with definitive and salvage radiation therapy.

Background: Tasquinimod is a novel inhibitor of tumor angiogenesis which enhances therapeutic efficacy when combined with androgen ablation and/or taxane-based chemotherapies in pre-clinical prostate cancer models. It has entered registration Phase III evaluation for the treatment of castration resistant prostate cancer. Since tasquinimod suppresses the angiogenic switch induced by tumor hypoxia as prostate cancers outgrow their blood supply, this raises the issue of whether tasquinimod also suppresses the angiogenic rebound induced by fractionated radiation thereby enhancing therapeutic response to fractionated radiation., Methods: Human endothelial and prostate cancer cells in culture and human prostate cancer xenografts growing in castrated male nude mice were evaluated for their response to radiation alone and in combination with tasquinimod., Results: At clinically relevant drug levels, tasquinimod significantly (P < 0.05) enhances anti-cancer efficacy of fractionated radiation with optimal timing for initiating daily tasquinimod treatment being after completion of the fractionated radiation., Conclusions: Based upon cell culture studies and tumor tissue oxygenation (i.e., pO(2)), tumor vascular volume, and tumor blood vessel density measurements, the mechanism for such enhancement and optimal timing involves tasquinimod's ability to prevent the angiogenic rebound induced by fractionated radiation., (Copyright © 2011 Wiley Periodicals, Inc.)

Objective: To evaluate the pathologic outcome of prostate-specific antigen-screened patients with high-grade (Gleason score ≥ 8) prostate cancer limited to 1 biopsy core, without clinical evidence of disease., Methods: Ninety-two patients with only 1 biopsy core with cancer and treated by radical prostatectomy were divided into 4 groups according to the biopsy Gleason score: 3 + 3 = 6 (23 cases), 3 + 4 = 7 (25 cases), 4 + 3 = 7 (20 cases), and ≥ 8 (24 cases)., Results: Cases with Gleason score ≥ 8 showed a significantly higher proportion of extraprostatic extension (50%), positive surgical margins (21%), and seminal vesicle invasion (12%) when compared with the other groups. Patients with Gleason score ≥ 8 in the biopsy had a 25-fold increased in the odds ratio for extraprostatic extension in the prostatectomy. The incidence of extraprostatic extension was higher in those with prostatic cancer involving ≥ 50% of one core (88%) compared with cases involving <50% (32%)., Conclusion: In patients with prostate cancer limited to 1 biopsy core, the presence of Gleason score ≥ 8 significantly increased the incidence of extraprostatic extension, positive surgical margins, and seminal vesicle invasion. The odds ratio was substantially higher in patients with ≥ 50% of Gleason ≥ 8 in the biopsy core. These data might be taken into account for proper clinical management of this set of patients., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Purpose: We report on a novel preclinical pancreatic cancer research model that uses bioluminescence imaging (BLI)-guided irradiation of orthotopic xenograft tumors, sparing of surrounding normal tissues, and quantitative, noninvasive longitudinal assessment of treatment response., Materials and Methods: Luciferase-expressing MiaPaCa-2 pancreatic carcinoma cells were orthotopically injected in nude mice. BLI was compared to pathologic tumor volume, and photon emission was assessed over time. BLI was correlated to positron emission tomography (PET)/computed tomography (CT) to estimate tumor dimensions. BLI and cone-beam CT (CBCT) were used to compare tumor centroid location and estimate setup error. BLI and CBCT fusion was performed to guide irradiation of tumors using the small animal radiation research platform (SARRP). DNA damage was assessed by γ-H2Ax staining. BLI was used to longitudinally monitor treatment response., Results: Bioluminescence predicted tumor volume (R = 0.8984) and increased linearly as a function of time up to a 10-fold increase in tumor burden. BLI correlated with PET/CT and necropsy specimen in size (P < .05). Two-dimensional BLI centroid accuracy was 3.5 mm relative to CBCT. BLI-guided irradiated pancreatic tumors stained positively for γ-H2Ax, whereas surrounding normal tissues were spared. Longitudinal assessment of irradiated tumors with BLI revealed significant tumor growth delay of 20 days relative to controls., Conclusions: We have successfully applied the SARRP to a bioluminescent, orthotopic preclinical pancreas cancer model to noninvasively: 1) allow the identification of tumor burden before therapy, 2) facilitate image-guided focal radiation therapy, and 3) allow normalization of tumor burden and longitudinal assessment of treatment response.

Dose-escalated radiation therapy for localized prostate cancer (PCa) has a clear therapeutic benefit; however, escalated doses may also increase injury to noncancerous tissues. Radiosensitizing agents can improve ionizing radiation (IR) potency, but without targeted delivery, these agents will also sensitize surrounding normal tissues. Here we describe the development of prostate-targeted RNAi agents that selectively sensitized prostate-specific membrane antigen-positive (PSMA-positive) cells to IR. siRNA library screens identified DNA-activated protein kinase, catalytic polypeptide (DNAPK) as an ideal radiosensitization target. DNAPK shRNAs, delivered by PSMA-targeting RNA aptamers, selectively reduced DNAPK in PCa cells, xenografts, and human prostate tissues. Aptamer-targeted DNAPK shRNAs, combined with IR, dramatically and specifically enhanced PSMA-positive tumor response to IR. These findings support aptamer-shRNA chimeras as selective sensitizing agents for the improved treatment of high-risk localized PCa.

Real-time stereovision-guidance has been introduced for efficient and convenient fractionated stereotactic radiotherapy (FSR) and image-guided intensity-modulated radiation therapy (IMRT). This first pilot study is to clinically evaluate its accuracy and precision as well as impact on treatment doses. Sixty-one FSR patients wearing stereotactic masks (SMs) and nine IMRT patients wearing flexible masks (FMs), were accrued. Daily target reposition was initially based-on biplane-radiographs and then adjusted in six degrees of freedom under real-time stereovision guidance. Mean and standard deviation of the head displacements measured the accuracy and precision. Head positions during beam-on times were measured with real-time stereovisions and used for determination of delivered doses. Accuracy ± ± precision in direction with the largest errors shows improvement from 0.4 ± 2.3 mm to 0.0 ± 1.0 mm in the inferior-to-superior direction for patients wearing SM or from 0.8 ± 4.3 mm to 0.4 ± 1.7 mm in the posterior-to-anterior direction for patients wearing FM. The image-guidance increases target volume coverage by >30% for small lesions. Over half of head position errors could be removed from the stereovision-guidance. Importantly, the technique allows us to check head position during beam-on time and makes it possible for having frameless head refixation without tight masks.

Background: Histone deacetylase inhibitors (HDACis) re-express silenced tumor suppressor genes and are currently undergoing clinical trials. Although HDACis have been known to induce gene expression, an equal number of genes are downregulated upon HDAC inhibition. The mechanism behind this downregulation remains unclear. Here we provide evidence that several DNA repair genes are downregulated by HDAC inhibition and provide a mechanism involving the E2F1 transcription factor in the process., Methodology/principal Findings: Applying Analysis of Functional Annotation (AFA) on microarray data of prostate cancer cells treated with HDACis, we found a number of genes of the DNA damage response and repair pathways are downregulated by HDACis. AFA revealed enrichment of homologous recombination (HR) DNA repair genes of the BRCA1 pathway, as well as genes regulated by the E2F1 transcription factor. Prostate cancer cells demonstrated a decreased DNA repair capacity and an increased sensitization to chemical- and radio-DNA damaging agents upon HDAC inhibition. Recruitment of key HR repair proteins to the site of DNA damage, as well as HR repair capacity was compromised upon HDACi treatment. Based on our AFA data, we hypothesized that the E2F transcription factors may play a role in the downregulation of key repair genes upon HDAC inhibition in prostate cancer cells. ChIP analysis and luciferase assays reveal that the downregulation of key repair genes is mediated through decreased recruitment of the E2F1 transcription factor and not through active repression by repressive E2Fs., Conclusions/significance: Our study indicates that several genes in the DNA repair pathway are affected upon HDAC inhibition. Downregulation of the repair genes is on account of a decrease in amount and promoter recruitment of the E2F1 transcription factor. Since HDAC inhibition affects several pathways that could potentially have an impact on DNA repair, compromised DNA repair upon HDAC inhibition could also be attributed to several other pathways besides the ones investigated in this study. However, our study does provide insights into the mechanism that governs downregulation of HR DNA repair genes upon HDAC inhibition, which can lead to rationale usage of HDACis in the clinics.

Purpose: In radiotherapy for prostate cancer, the rectum is the major dose-limiting structure. Physically separating the rectum from the prostate (e.g., by injecting a spacer) can reduce the rectal radiation dose. Despite pilot clinical studies, no careful analysis has been done of the risks, benefits, and dosimetric effects of this practice., Methods and Materials: Using cadaveric specimens, 20 mL of a hydrogel was injected between the prostate and rectum using a transperineal approach. Imaging was performed before and after spacer placement, and the cadavers were subsequently dissected. Ten intensity-modulated radiotherapy plans were generated (five before and five after separation), allowing for characterization of the rectal dose reduction. To quantify the amount of prostate-rectum separation needed for effective rectal dose reduction, simulations were performed using nine clinically generated intensity-modulated radiotherapy plans., Results: In the cadaveric studies, an average of 12.5 mm of prostate-rectum separation was generated with the 20-mL hydrogel injections (the seminal vesicles were also separated from the rectum). The average rectal volume receiving 70 Gy decreased from 19.9% to 4.5% (p < .05). In the simulation studies, a prostate-rectum separation of 10 mm was sufficient to reduce the mean rectal volume receiving 70 Gy by 83.1% (p <.05). No additional reduction in the average rectal volume receiving 70 Gy was noted after 15 mm of separation. In addition, spacer placement allowed for increased planning target volume margins without exceeding the rectal dose tolerance., Conclusion: Prostate-rectum spacers can allow for reduced rectal toxicity rates, treatment intensification, and/or reduced dependence on complex planning and treatment delivery techniques., (Copyright 2010 Elsevier Inc. All rights reserved.)

Purpose: Conditionally Replicative Adenovirus (CRAd) has been previously demonstrated to augment the activity of radiation, resulting in synergy of cell kill. However, previous models combining radiation with CRAd have not focused on the methods of radiation delivery., Materials and Methods: We model the combination of a novel prostate-specific CRAd, Ad5 PSE/PBN E1A-AR (Ad5: adenovirus 5; PSE: prostate-specific enhancer; PBN: rat probasin promoter; E1A: early region 1A; AR: androgen receptor), with radiation delivered both acutely and continuously, in an effort to better mimic the potential clinical modes of prostate cancer radiotherapy., Results: We demonstrate that pre-treatment of cells with acute single high dose rate (HDR) radiation 24 hours prior to viral infection results in significantly enhanced viral replication and virus-mediated cell death. In addition, this combination causes increased level of gamma-H2AX (Phosphorylated histone protein H2AX on serine 139), a marker of double-stranded DNA damage and an indirect measure of nuclear fragmentation. In contrast, continuous low dose rate (LDR) radiation immediately following infection of the same CRAd results in no enhancement of viral replication, and only additive effects in virus-mediated cell death., Conclusions: These data provide the first direct assessment of the real-time impact of radiation on viral replication and the first comparison of the effect of radiation delivery on the efficacy of CRAd virotherapy. Our data demonstrate substantial differences in CRAd efficacy based on the mode of radiation delivery.

Purpose: Cyclooxygenase-2 (COX-2) is a potential pharmacologic target for the prevention of various malignancies, including prostate cancer. We conducted a randomized, double-blind trial to examine the effect of celecoxib on drug-specific biomarkers from prostate tissue obtained at prostatectomy., Patients and Methods: Patients with localized prostate cancer and Gleason sum > or = 7, prostate-specific antigen (PSA) > or = 15 ng/mL, clinical stage T2b or greater, or any combination with greater than 45% risk of capsular penetration were randomly assigned to celecoxib 400 mg by mouth twice daily or placebo for 4 to 6 weeks before prostatectomy. The primary end point was the difference in prostatic prostaglandin levels between the two groups. Secondary end points were differences in COX-1 and -2 expressions; oxidized DNA bases; and markers of proliferation, apoptosis and angiogenesis. Tissue celecoxib concentrations also were measured. Tertiary end points were drug safety and compliance., Results: Seventy-three patients consented, and 64 were randomly assigned and included in the intention-to-treat analysis. There were no treatment differences in any of the primary or secondary outcomes. Multivariable regression revealed that tumor tissue had significantly lower COX-2 expression than benign prostatic tissue (P = .01) and significantly higher levels of the proliferation marker Ki-67 (P < .0001). Celecoxib was measurable in prostate tissue of patients on treatment, demonstrating that celecoxib reached its target. Celecoxib was safe and resulted in only grade 1 toxicities., Conclusion: Treatment with 4 to 6 weeks of celecoxib had no effect on intermediate biomarkers of prostate carcinogenesis, despite the achievement of measurable tissue levels. We caution against using celecoxib 400 mg twice daily as a preventive agent for prostate cancer in additional studies.

Purpose: Failure mode and effects analysis (FMEA) is a widely used tool for prospectively evaluating safety and reliability. We report our experiences in applying FMEA in the setting of radiation oncology., Methods and Materials: We performed an FMEA analysis for our external beam radiation therapy service, which consisted of the following tasks: (1) create a visual map of the process, (2) identify possible failure modes; assign risk probability numbers (RPN) to each failure mode based on tabulated scores for the severity, frequency of occurrence, and detectability, each on a scale of 1 to 10; and (3) identify improvements that are both feasible and effective. The RPN scores can span a range of 1 to 1000, with higher scores indicating the relative importance of a given failure mode., Results: Our process map consisted of 269 different nodes. We identified 127 possible failure modes with RPN scores ranging from 2 to 160. Fifteen of the top-ranked failure modes were considered for process improvements, representing RPN scores of 75 and more. These specific improvement suggestions were incorporated into our practice with a review and implementation by each department team responsible for the process., Conclusions: The FMEA technique provides a systematic method for finding vulnerabilities in a process before they result in an error. The FMEA framework can naturally incorporate further quantification and monitoring. A general-use system for incident and near miss reporting would be useful in this regard.

Base excision repair (BER) is the major pathway for removing mutagenic and cytotoxic oxidative and alkylation DNA modifications. Using a catalytically inactive, dominant negative protein form of human APE1, termed ED, which binds with high affinity to substrate DNA and blocks subsequent repair steps, we assessed the role of BER in mediating cellular resistance to clinically relevant alkylating drugs and antimetabolites. Colony formation assays revealed that ED expression enhanced cellular sensitivity to melphalan not at all; to decarbazine, thiotepa, busulfan and carmustine moderately (1.2- to 2.4-fold); and to streptozotocin and temozolomide significantly (2.0- to 5.3-fold). The effectiveness of ED to promote enhanced cytotoxicity generally correlated with the agent's (a) monofunctional nature, (b) capacity to induce N(7)-guanine and N(3)-adenine modifications, and (c) inability to generate O(6)-guanine adducts or DNA cross-links. ED also enhanced the cell killing potency of the antimetabolite troxacitabine, apparently by blocking the processing of DNA strand breaks, yet had no effect on the cytotoxicity of gemcitabine, results that agree well with the known efficiency of APE1 to excise these nucleoside analogues from DNA. Most impressively, ED expression produced an approximately 5- and 25-fold augmentation of the cell killing effect of 5-fluorouracil and 5-fluorodeoxyuridine, respectively, implicating BER in the cellular response to such antimetabolites; the increased 5-fluorouracil sensitivity was associated with an accumulation of abasic sites and active caspase-positive staining. Our data suggest that APE1, and BER more broadly, is a potential target for inactivation in anticancer treatment paradigms that involve select alkylating agents or antimetabolites.

Objectives: It is unclear whether postoperative salvage radiation therapy (SRT) and early adjuvant radiotherapy (ART) after radical prostatectomy lead to equivalent long-term tumor control. We studied a group of patients undergoing ART by comparing them with a matched control group undergoing SRT after biochemical failure., Methods: Using a multi-institutional database of 2299 patients, 449 patients with pT3-4N0 disease were eligible for inclusion, including 211 patients receiving ART and 238 patients receiving SRT. Patients were matched in a 1:1 ratio according to preoperative prostate-specific antigen Gleason score, seminal vesicle invasion, surgical margin status, and follow-up from date of surgery., Results: A total of 192 patients were matched (96:96). The median follow-up was 94 months from surgery and 73 months from RT completion. There was a significant reduction in biochemical failure with ART compared with SRT. The 5-year freedom from biochemical failure (FFBF) from surgery was 75% after ART, compared with 66% for SRT (hazard ratio [HR] = 1.6, P = .049). The 5-year FFBF from the end of RT was 73% after ART, compared with 50% after SRT (HR = 2.3, log rank [LR] P = .0007). From the end of RT, SRT and Gleason score >or=8 were independent predictors of diminished FFBF. From the date of surgery, Gleason score >or=8 was a significant predictor of FFBF., Conclusions: Early ART for pT3-4N0 prostate cancer significantly reduces the risk of long-term biochemical progression after radical prostatectomy compared with SRT. Gleason score >or=8 was the only factor on multivariate analysis associated with metastasic progression.

Hypomethylation of CpG dinucleotides in genomic DNA was one of the first somatic epigenetic alterations discovered in human cancers. DNA hypomethylation is postulated to occur very early in almost all human cancers, perhaps facilitating genetic instability and cancer initiation and progression. We therefore examined the nature, extent, and timing of DNA hypomethylation changes in human prostate cancer. Contrary to the prevailing view that global DNA hypomethylation changes occur extremely early in all human cancers, we show that reductions in (5me)C content in the genome occur very late in prostate cancer progression, appearing at a significant extent only at the stage of metastatic disease. Furthermore, we found that, whereas some LINE1 promoter hypomethylation does occur in primary prostate cancers compared with normal tissues, this LINE1 hypomethylation is significantly more pronounced in metastatic prostate cancer. Next, we carried out a tiered gene expression microarray and bisulfite genomic sequencing-based approach to identify genes that are silenced by CpG island methylation in normal prostate cells but become overexpressed in prostate cancer cells as a result of CpG island hypomethylation. Through this analysis, we show that a class of cancer testis antigen genes undergoes CpG island hypomethylation and overexpression in primary prostate cancers, but more so in metastatic prostate cancers. Finally, we show that DNA hypomethylation patterns are quite heterogeneous across different metastatic sites within the same patients. These findings provide evidence that DNA hypomethylation changes occur later in prostate carcinogenesis than the CpG island hypermethylation changes and occur heterogeneously during prostate cancer progression and metastatic dissemination.

Background: Cancer immunotherapy refers to an array of strategies intended to treat progressive tumors by augmenting a patient's anti-tumor immune response. As immunotherapy is eventually incorporated into oncology treatment paradigms, it is important to understand how these therapies interact with established cancer treatments such as chemotherapy or Radiotherapy (RT). To address this, we utilized a well-established, autochthonous murine model of prostate cancer to test whether RT could augment (or diminish) the CD4 T cell response to a tumor vaccine., Methods: Transgenic mice that develop spontaneous prostate cancer (TRAMP) which also express a unique tumor associated antigen (Influenza hemagglutinin) under the control of a prostate-specific promoter were given local RT in combination with immunotherapy. The immunological outcome of this combinatorial strategy was assayed by monitoring the effector response of adoptively transferred, prostate-specific CD4 T cells., Results: Neither RT nor immunotherapy alone was capable of priming an anti-tumor immune response in animals with evolving tumors. The combination of immunotherapy with RT resulted in anti-tumor T cell activation--this effect was profoundly dependent on the relative timing of RT and immunotherapy. Anti-tumor immune responses occurred when immunotherapy was administered 3-5 weeks post-RT, but such responses were undetectable when immunotherapy was administered either earlier (peri-radiotherapy) or later., Conclusions: The therapeutic temporal window of immunotherapy post-RT suggests that highly aggressive, immuno-suppressive tumors might be most sensitive to immunotherapy in a fairly narrow time window; these results should help to guide future development of clinical combinatorial strategies., ((c) 2008 Wiley-Liss, Inc.)

Purpose: To demonstrate the computed tomography, conformal irradiation, and treatment planning capabilities of a small animal radiation research platform (SARRP)., Methods and Materials: The SARRP uses a dual-focal spot, constant voltage X-ray source mounted on a gantry with a source-to-isocenter distance of 35 cm. Gantry rotation is limited to 120 degrees from vertical. X-rays of 80-100 kVp from the smaller 0.4-mm focal spot are used for imaging. Both 0.4-mm and 3.0-mm focal spots operate at 225 kVp for irradiation. Robotic translate/rotate stages are used to position the animal. Cone-beam computed tomography is achieved by rotating the horizontal animal between the stationary X-ray source and a flat-panel detector. The radiation beams range from 0.5 mm in diameter to 60 x 60 mm(2). Dosimetry is measured with radiochromic films. Monte Carlo dose calculations are used for treatment planning. The combination of gantry and robotic stage motions facilitate conformal irradiation., Results: The SARRP spans 3 ft x 4 ft x 6 ft (width x length x height). Depending on the filtration, the isocenter dose outputs at a 1-cm depth in water were 22-375 cGy/min from the smallest to the largest radiation fields. The 20-80% dose falloff spanned 0.16 mm. Cone-beam computed tomography with 0.6 x 0.6 x 0.6 mm(3) voxel resolution was acquired with a dose of <1 cGy. Treatment planning was performed at submillimeter resolution., Conclusion: The capability of the SARRP to deliver highly focal beams to multiple animal model systems provides new research opportunities that more realistically bridge laboratory research and clinical translation.

Context: Biochemical disease recurrence after radical prostatectomy often prompts salvage radiotherapy, but no studies to date have had sufficient numbers of patients or follow-up to determine whether radiotherapy improves survival, and if so, the subgroup of men most likely to benefit., Objectives: To quantify the relative improvement in prostate cancer-specific survival of salvage radiotherapy vs no therapy after biochemical recurrence following prostatectomy, and to identify subgroups for whom salvage treatment is most beneficial., Design, Setting, and Patients: Retrospective analysis of a cohort of 635 US men undergoing prostatectomy from 1982-2004, followed up through December 28, 2007, who experienced biochemical and/or local recurrence and received no salvage treatment (n = 397), salvage radiotherapy alone (n = 160), or salvage radiotherapy combined with hormonal therapy (n = 78)., Main Outcome Measure: Prostate cancer-specific survival defined from time of recurrence until death from disease., Results: With a median follow-up of 6 years after recurrence and 9 years after prostatectomy, 116 men (18%) died from prostate cancer, including 89 (22%) who received no salvage treatment, 18 (11%) who received salvage radiotherapy alone, and 9 (12%) who received salvage radiotherapy and hormonal therapy. Salvage radiotherapy alone was associated with a significant 3-fold increase in prostate cancer-specific survival relative to those who received no salvage treatment (hazard ratio [HR], 0.32 [95% confidence interval {CI}, 0.19-0.54]; P<.001). Addition of hormonal therapy to salvage radiotherapy was not associated with any additional increase in prostate cancer-specific survival (HR, 0.34 [95% CI, 0.17-0.69]; P = .003). The increase in prostate cancer-specific survival associated with salvage radiotherapy was limited to men with a prostate-specific antigen doubling time of less than 6 months and remained after adjustment for pathological stage and other established prognostic factors. Salvage radiotherapy initiated more than 2 years after recurrence provided no significant increase in prostate cancer-specific survival. Men whose prostate-specific antigen level never became undetectable after salvage radiotherapy did not experience a significant increase in prostate cancer-specific survival. Salvage radiotherapy also was associated with a significant increase in overall survival., Conclusions: Salvage radiotherapy administered within 2 years of biochemical recurrence was associated with a significant increase in prostate cancer-specific survival among men with a prostate-specific antigen doubling time of less than 6 months, independent of other prognostic features such as pathological stage or Gleason score. These preliminary findings should be validated in other settings, and ultimately, in a randomized controlled trial.

Recent technological advances in radiation treatment delivery have allowed relatively higher doses of radiation to be delivered safely to the prostate. Emerging data suggest improvements in disease control with higher doses of radiation in subsets of patients with prostate cancer.

Purpose: To determine the rate and magnitude of late genitourinary (GU) and gastrointestinal (GI) toxicities after salvage or adjuvant radiotherapy (RT) for prostate cancer, and to determine predictive factors for these toxicities., Methods and Materials: A large multi-institutional database that included 959 men who received postoperative RT after radical prostatectomy (RP) was analyzed: 19% received adjuvant RT, 81% received salvage RT, 78% were treated to the prostate bed only, and 22% received radiation to the pelvis., Results: The median follow-up time was 55 months. At 5 years, 10% of patients had Grade 2 late GU toxicity and 1% had Grade 3 late GU toxicity, while 4% of patients had Grade 2 late GI toxicity and 0.4% had Grade 3 late GI toxicity. Multivariate analysis demonstrated that adjuvant RT (p = 0.03), androgen deprivation (p < 0.0001), and prostate bed-only RT (p = 0.007) predicted for Grade 2 or higher late GU toxicity. For GI toxicity, although adjuvant RT was significant in the univariate analysis, no significant factors were found in the multivariate analysis., Conclusions: Overall, the number of high-grade toxicities for postoperative RT was low. Therefore, adjuvant and salvage RT can safely be used in the appropriate settings.

Objectives: To assess the prognostic effect of perineural invasion (PNI) for patients undergoing external beam radiotherapy for prostate cancer., Methods: We evaluated 657 consecutive patients who had undergone external beam radiotherapy for clinically localized prostate cancer. The clinical/treatment parameters used for analysis included PNI, clinical stage, biopsy Gleason score, pretreatment prostate-specific antigen, radiation dose, and androgen deprivation. The primary endpoint was biochemical recurrence defined by the Radiation Therapy Oncology Group-American Society for Therapeutic Radiology Oncology Phoenix consensus; the secondary endpoint was prostate cancer death., Results: Of 586 men with a minimum of 24 months of follow-up, 112 (19.1%) had PNI present in the biopsy specimen. When patients were stratified into risk groups using the National Comprehensive Cancer Network criteria, PNI was more prevalent in patients within higher risk groups (6.8% in low-risk versus 18.3% in intermediate-risk versus 30.1% in high-risk groups; P <0.001). The presence of PNI was associated with lower biochemical recurrence-free (P = 0.003) and cancer-specific (P = 0.040) survival rates by Kaplan-Meier analysis. Cox regression analysis showed that PNI was a statistically significant prognostic factor of biochemical recurrence on both univariate (hazard ratio [HR] 1.71, 95% confidence interval [CI] 1.19 to 2.46, P = 0.004) and multivariate (HR 1.57, 95% CI 1.06 to 2.32, P = 0.025) analyses. Regression analysis after stratification by risk group and adjustment for treatment covariates demonstrated a significant association between PNI and the risk of biochemical recurrence for low-risk (HR 4.14, 95% CI 1.55 to 11.02, P = 0.005) and intermediate/high-risk patients (HR 1.53, 95% CI 1.02 to 2.29, P = 0.040)., Conclusions: The results of our study have shown that the presence of PNI is an independent risk factor associated with an increased risk of biochemical recurrence in patients with prostate cancer undergoing external beam radiotherapy.

Purpose: To evaluate the preclinical pharmacokinetics and antitumor efficacy of a novel orally bioavailable poly(ADP-ribose) polymerase (PARP) inhibitor, ABT-888., Experimental Design: In vitro potency was determined in a PARP-1 and PARP-2 enzyme assay. In vivo efficacy was evaluated in syngeneic and xenograft models in combination with temozolomide, platinums, cyclophosphamide, and ionizing radiation., Results: ABT-888 is a potent inhibitor of both PARP-1 and PARP-2 with K(i)s of 5.2 and 2.9 nmol/L, respectively. The compound has good oral bioavailability and crosses the blood-brain barrier. ABT-888 strongly potentiated temozolomide in the B16F10 s.c. murine melanoma model. PARP inhibition dramatically increased the efficacy of temozolomide at ABT-888 doses as low as 3.1 mg/kg/d and a maximal efficacy achieved at 25 mg/kg/d. In the 9L orthotopic rat glioma model, temozolomide alone exhibited minimal efficacy, whereas ABT-888, when combined with temozolomide, significantly slowed tumor progression. In the MX-1 breast xenograft model (BRCA1 deletion and BRCA2 mutation), ABT-888 potentiated cisplatin, carboplatin, and cyclophosphamide, causing regression of established tumors, whereas with comparable doses of cytotoxic agents alone, only modest tumor inhibition was exhibited. Finally, ABT-888 potentiated radiation (2 Gy/d x 10) in an HCT-116 colon carcinoma model. In each model, ABT-888 did not display single-agent activity., Conclusions: ABT-888 is a potent inhibitor of PARP, has good oral bioavailability, can cross the blood-brain barrier, and potentiates temozolomide, platinums, cyclophosphamide, and radiation in syngeneic and xenograft tumor models. This broad spectrum of chemopotentiation and radiopotentiation makes this compound an attractive candidate for clinical evaluation.

Objectives: Patients with biochemical recurrence of prostate cancer after definitive or salvage local therapy in the absence of metastatic disease represent a group well suited to a novel therapeutic intervention. Imatinib mesylate (Gleevec) is a protein-tyrosine kinase inhibitor that has previously been tested in men with androgen-independent and metastatic prostate cancer. This Phase II study was undertaken to determine the safety and efficacy of imatinib mesylate in men with biochemical relapse of nonmetastatic, androgen-sensitive prostate cancer after local therapy., Methods: Twenty-seven patients were treated with imatinib mesylate 400 mg twice daily for up to 12 months. Three patients (11%) completed less than 4 weeks of therapy and were included in the intent-to-treat analysis of the response to therapy., Results: Of the 27 patients treated, 5 (18.5%) had a stable prostate-specific antigen (PSA) during the course of treatment; 2 patients (7.4%) experienced a partial response. The remaining 20 patients (74.1%) demonstrated PSA progression. The median progression-free survival was 3 months. The proportion of patients achieving a partial PSA response during therapy did not significantly differ from the null rate of 5% (P = 0.394). Seven patients (25.9%) discontinued therapy secondary to grade 1 to 3 toxicities. No irreversible National Institutes of Health Common Toxicity Criteria grade 3 or 4 toxicities occurred. Grade 3 and 4 toxicity included leukopenia (3.7%), serum glutamic-oxaloacetic transaminase (3.7%) and serum glutamic-pyruvic transaminase (3.7%) elevation, and rash (18.5%)., Conclusions: The results of our study have demonstrated that imatinib mesylate delivered at a dose of 400 mg twice daily is associated with a moderate degree of toxicity and a limited PSA response in this patient population.

Despite the significance of oxidative damage for carcinogenesis, the molecular mechanisms that lead to increased susceptibility of tissues to oxidative stress are not well-understood. We now report a link between loss of protection against oxidative damage and loss-of-function of Nkx3.1, a homeobox gene that is known to be required for prostatic epithelial differentiation and suppression of prostate cancer. Using gene expression profiling, we find that Nkx3.1 mutant mice display deregulated expression of several antioxidant and prooxidant enzymes, including glutathione peroxidase 2 and 3 (GPx2 and GPx3), peroxiredoxin 6 (Prdx6), and sulfyhydryl oxidase Q6 (Qscn6). Moreover, the formation of prostatic intraepithelial neoplasia in these mutant mice is associated with increased oxidative damage of DNA, as evident by increased levels of 8-hydroxy-2'-deoxyguanosine. We further show that progression to prostate adenocarcinoma, as occurs in compound mutant mice lacking Nkx3.1 as well as the Pten tumor suppressor, is correlated with a further deregulation of antioxidants, including superoxide dismutase enzymes, and more profound accumulations of oxidative damage to DNA and protein, the latter manifested by increased levels of 4-hydroxynonenal. We propose that the essential role of Nkx3.1 in maintaining the terminally differentiated state of the prostate epithelium provides protection against oxidative damage and, thereby, suppression of prostate cancer. Thus, our findings provide a molecular link between a gene whose inactivation is known to be involved in prostate carcinogenesis, namely Nkx3.1, and oxidative damage of the prostatic epithelium.

Purpose: To evaluate the safety and biological activity of three different doses of marimastat given for 6 months to patients with biochemically relapsed prostate cancer., Experimental Design: Patients with a biochemical relapse within 2 years of primary therapy, a prostate-specific antigen (PSA) increase of at least 50% within 6 months of study entry, and no prior systemic therapy were eligible. Patients were randomized to receive marimastat at total daily doses of 5, 20, or 40 mg for 6 months unless dose-limiting toxicity or new evidence of disease occurred., Results: Thirty-nine patients were treated. Grade 3-4 reversible musculoskeletal toxicity was the only dose-limiting toxicity. Increasing dose was associated with increased probability of experiencing dose-limiting toxicity (5.9%, 42.9% and 88.9% for the 5, 20, and 40 mg groups, respectively; P = 0.03). Accrual was discontinued early on the two higher dose levels due to toxicity. A significant decrease in PSA slope was shown in the 20 mg group when compared with the 5 mg group (0.117 and -0.0046, respectively; P = 0.03) The 40 mg group (versus the 5 mg group) showed a similar change (0.109) with a trend towards significance (P = 0.07). An increased serum matrix metalloproteinase 2 level at month 3 compared with the baseline correlated with a decrease in PSA slopes (Slope, 0.001; 95% confidence interval, 0.0002-0.0018; P = 0.02)., Conclusion: These data suggest that marimastat has a biological effect and may effectively delay progression in patients with biochemical relapsed prostate cancer, as shown by the change in PSA slope; however, dose-limiting toxicity at active doses is significant. Confirmatory studies with less toxic matrix metalloproteinase inhibitors employing more conventional end points are indicated. This design is feasible and potentially efficient for screening antimetastatic agents.

Double-strand breaks (DSBs) arise endogenously during normal cellular processes and exogenously by genotoxic agents such as ionizing radiation (IR). DSBs are one of the most severe types of DNA damage, which if left unrepaired are lethal to the cell. Several different DNA repair pathways combat DSBs, with nonhomologous end-joining (NHEJ) being one of the most important in mammalian cells. Competent NHEJ catalyses repair of DSBs by joining together and ligating two free DNA ends of little homology (microhomology) or DNA ends of no homology. The core components of mammalian NHEJ are the catalytic subunit of DNA protein kinase (DNA-PK(cs)), Ku subunits Ku70 and Ku80, Artemis, XRCC4 and DNA ligase IV. DNA-PK is a nuclear serine/threonine protein kinase that comprises a catalytic subunit (DNA-PK(cs)), with the Ku subunits acting as the regulatory element. It has been proposed that DNA-PK is a molecular sensor for DNA damage that enhances the signal via phosphorylation of many downstream targets. The crucial role of DNA-PK in the repair of DSBs is highlighted by the hypersensitivity of DNA-PK(-/-) mice to IR and the high levels of unrepaired DSBs after genotoxic insult. Recently, DNA-PK has emerged as a suitable genetic target for molecular therapeutics such as siRNA, antisense and novel inhibitory small molecules. This review encompasses the recent literature regarding the role of DNA-PK in the protection of genomic stability and focuses on how this knowledge has aided the development of specific DNA-PK inhibitors, via both small molecule and directed molecular targeting techniques. This review promotes the inhibition of DNA-PK as a valid approach to enhance the tumor-cell-killing effects of treatments such as IR.

DNA damage that is not repaired with high fidelity can lead to chromosomal aberrations or mitotic cell death. To date, it is unclear what factors control the ultimate fate of a cell receiving low levels of DNA damage (i.e. survival at the risk of increased mutation or cell death). We investigated whether DNA damage could be introduced into human cells at a level and frequency that could evade detection by cellular sensors of DNA damage. To achieve this, we exposed cells to equivalent doses of ionizing radiation delivered at either a high dose rate (HDR) or a continuous low dose rate (LDR). We observed reduced activation of the DNA damage sensor ataxia-telangiectasia mutated (ATM) and its downstream target histone H2A variant (H2AX) following LDR compared with HDR exposures in both cancerous and normal human cells. This lack of DNA damage signaling was associated with increased amounts of cell killing following LDR exposures. Increased killing by LDR radiation has been previously termed the "inverse dose rate effect," an effect for which no clear molecular processes have been described. These LDR effects could be abrogated by the preactivation of ATM or simulated in HDR-treated cells by inhibiting ATM function. These data are the first to demonstrate that DNA damage introduced at a reduced rate does not activate the DNA damage sensor ATM and that failure to activate ATM-associated repair pathways contributes to the increased lethality of continuous LDR radiation exposures. This inactivation may reflect one strategy by which cells avoid accumulating mutations as a result of error-prone DNA repair and may have a broad range of implications for carcinogenesis and, potentially, the clinical treatment of solid tumors.

Purpose: A new hypothesis for the etiology of prostate cancer is that chronic or recurrent prostate inflammation may initiate and promote prostate cancer development., Materials and Methods: We reviewed the current direct and indirect evidence from epidemiology, genetics, molecular biology and histopathology implicating inflammation in the pathogenesis of prostate cancer., Results: The case for prostate inflammation as a cause of prostate cancer is compelling. Epidemiology data have correlated prostatitis and sexually transmitted infections with increased prostate cancer risk and intake of anti-inflammatory drugs and antioxidants with decreased prostate cancer risk. Genetic studies have identified RNASEL, encoding an interferon inducible ribonuclease, and MSR1, encoding subunits of the macrophage scavenger receptor, as candidate inherited susceptibility genes for familial prostate cancer. Somatic silencing of GSTP1, encoding a glutathione S-transferase capable of defending against oxidant cell and genome damage, has been found in almost all prostate cancer cases. Proliferative inflammatory atrophy lesions containing activated inflammatory cells and proliferating epithelial cells appear likely to be precursors to prostatic intraepithelial neoplasia lesions and prostatic carcinomas., Conclusions: Emerging hints that prostate inflammation may contribute to prostatic carcinogenesis will provide opportunities for the discovery and development of new drugs and strategies for prostate cancer prevention.

In both the pre- and post-human genome sequencing eras, there has been an increase in the understanding of the molecular mechanisms influencing cellular sensitivity to DNA damaging agents such as ionizing radiation. Out of this work have arisen many cellular factors that could be specifically targeted, at the molecular level, to alter the functionality of a single protein or pathway involved in the response to radiation damage as a means to increase cell killing following radiation treatment. As such, there are many promising new combination radio-gene therapy approaches being developed and assessed in pre-clinical and clinical studies for several different malignancies. Combination of such modalities aims to increase the therapeutic index, giving rise to increased tumor cell killing with a simultaneous reduction in normal cell toxicity. Restricted delivery and/or targeting modalities combined with conformal radiotherapy regimes could provide significant local control of tumors, impeding their development into metastatic disease, which poses a greater challenge for palliative and curative treatments. This review will summarize current and novel gene therapy strategies that are being developed aimed at enhancing the effects of radiotherapy through the use of directed molecular targeting approaches.

It has recently been shown that specific lineage-depleted murine hematopoietic stem cells that home to the bone marrow 2 days after transplantation of ablated primary recipients are capable of long-term engraftment and repopulation of secondary recipients. We were interested in determining whether the rate at which the ablating radiation dose was delivered to the mice affected the homing of lineage-depleted stem cells to the bone marrow and/or sites of tissue damage. Fractionated, lineage-depleted donor marrow cells were isolated and labeled with the membrane dye PKH26. Recipient mice were lethally irradiated with 11 Gy ionizing radiation using varying dose rates and were immediately injected with PKH26-labeled progenitor stem cells. With the exception of the lowest dose-rate group, all irradiated mice had an approximately fivefold (P = 0.014 to 0.025) reduction in stem cell homing to the bone marrow compared to unirradiated control animals. A fivefold reduction of stem cell homing to the spleen compared to unirradiated animals was also observed, though this was not statistically significant for any dose-rate group (P = 0.072 to 0.233). This difference in homing could not be explained by increased stem cell apoptosis/necrosis or non-marrow tissue homing to the intestine, lung or liver. We show that the dose rate at which a lethal dose of total-body radiation is delivered does not augment hematopoietic progenitor stem cell homing to the bone marrow, spleen or sites of early radiation-mediated tissue damage at either 2 or 5 days postirradiation/transplantation. The observation that greater homing was seen in unirradiated control mice calls into question the concept that adequate bone marrow stem cell homing requires radiation-induced "space" to be made in the marrow, certainly for the enriched early progenitor hematopoietic stem cells used for this set of experiments. Further experiments will be needed to determine whether these homed cells are as capable of giving rise to long-term engraftment/repopulation of the marrow of secondary recipients as they are in irradiated recipients.

Prostate cancer is an increasing threat throughout the world. As a result of a demographic shift in population, the number of men at risk for developing prostate cancer is growing rapidly. For 2002, an estimated 189,000 prostate cancer cases were diagnosed in the U.S., accompanied by an estimated 30,200 prostate cancer deaths [Jemal et al., 2002]. Most prostate cancer is now diagnosed in men who were biopsied as a result of an elevated serum PSA (>4 ng/ml) level detected following routine screening. Autopsy studies [Breslow et al., 1977; Yatani et al., 1982; Sakr et al., 1993], and the recent results of the Prostate Cancer Prevention Trial (PCPT) [Thompson et al., 2003], a large scale clinical trial where all men entered the trial without an elevated PSA (<3 ng/ml) were subsequently biopsied, indicate the prevalence of histologic prostate cancer is much higher than anticipated by PSA screening. Environmental factors, such as diet and lifestyle, have long been recognized contributors to the development of prostate cancer. Recent studies of the molecular alterations in prostate cancer cells have begun to provide clues as to how prostate cancer may arise and progress. For example, while inflammation in the prostate has been suggested previously as a contributor to prostate cancer development [Gardner and Bennett, 1992; Platz, 1998; De Marzo et al., 1999; Nelson et al., 2003], research regarding the genetic and pathological aspects of prostate inflammation has only recently begun to receive attention. Here, we review the subject of inflammation and prostate cancer as part of a "chronic epithelial injury" hypothesis of prostate carcinogenesis, and the somatic genome and phenotypic changes characteristic of prostate cancer cells. We also present the implications of these changes for prostate cancer diagnosis, detection, prevention, and treatment., (Copyright 2003 Wiley-Liss, Inc.)

Background: Paclitaxel is one of the few chemotherapeutics effective in patients with advanced protstate cancer. Paclitaxel has also been reported to have radiosensitizing effects in prostate cancer. Local delivery of a controlled-release paclitaxel product may allow for increase local concentrations of paclitaxel at the tumor site and, in conjunction with radiation, may enhance cell kill by its radiosensitization mechanism., Methods: Orthotopic LNCaP tumors were injected with 40% PACLIMER Microspheres (40% loading; w:w) when tumors were 100-200 mm(3). Twenty-eight days post cell injection, mice were sacrificed, tumors weighed, and serum measured for PSA. TSU-xenografts were injected with PACLIMER Microspheres (10% and 40% loaded; w:w) or placebo microspheres when the tumors were approximately 100 mm(3). Half of xenograft tumors were irradiated with a single dose (10 Gy) of radiation. Tumor volume was followed over time., Results: Forty percent PACLIMER Microspheres significantly reduced tumor growth in the LNCaP orthotopic model. PSA was a good indicator of response. Forty percent PACLIMER Microspheres had a significant effect on slowing TSU growth compared to placebo microspheres. Addition of a single acute dose of radiation significantly enhanced the effect of 10% PACLIMER Microspheres (P < 0.05), had minimal effect on 40% PACLIMER Microspheres, and no enhancing effect on tumors treated with placebo microspheres., Conclusions: A controlled-release formulation of paclitaxel can be very effective in the treatment of prostate cancer. Additionally, PACLIMER Microspheres may be effectively used as a radiosensitizer in genitourinary cancers., (Copyright 2003 Wiley-Liss, Inc.)

Oxidative DNA damage can generate a variety of cytotoxic DNA lesions such as 8-oxoguanine (8-oxoG), which is one of the most mutagenic bases formed from oxidation of genomic DNA because 8-oxoG can readily mispair with either cytosine or adenine. If unrepaired, further replication of A.8-oxoG mispairs results in C:G to A:T transversions, a form of genomic instability. We reported previously that repair of A.8-oxoG mispairs was defective and that 8-oxoG levels were elevated in several microsatellite stable human colorectal cancer cell lines lacking MutY mutations (human MutY homolog gene, hmyh, MYH MutY homolog protein). In this report, we provide biochemical evidence that the defective repair of A.8-oxoG may be due, at least in part, to defective phosphorylation of the MutY protein in these cell lines. In MutY-defective cell extracts, but not extracts with functional MutY, A.8-oxoG repair was increased by incubation with protein kinases A and C (PKA and PKC) and caesin kinase II. Treatment of these defective cells, but not cells with functional MutY, with phorbol-12-myristate-13-acetate also increased the cellular A.8-oxoG repair activity and decreased the elevated 8-oxoG levels. We show that MutY is serine-phosphorylated in vitro by the action of PKC and in the MutY-defective cells by phorbol-12-myristate-13-acetate but that MutY is already phosphorylated at baseline in proficient cell lines. Finally, using antibody-isolated MutY protein, we show that MutY can be directly phosphorylated by PKC that directly increases the level of MutY catalyzed A.8-oxoG repair.

We report a case of a 50-year-old man with two synchronous second malignancies 25 years after orchiectomy and adjuvant radiotherapy for seminoma. An annual health examination revealed an elevated prostate-specific antigen level. A biopsy was performed revealing Gleason score 9 adenocarcinoma of the prostate. Computed tomography of the abdomen revealed a 2-cm solid mass in the right kidney consistent with renal cell carcinoma. Both of these lesions were within the nonstandard radiation field for seminoma with which this patient was treated. Second malignancies, including prostate cancer, are a very uncommon occurrence but an important consideration in long-term survivors of seminoma treated with radiotherapy.

Recent developments in the use of small inhibitory RNA molecules (siRNAs) to inhibit specific protein expression have highlighted the potential use of siRNA as a therapeutic agent. The double-strand break signaling/repair proteins ATM, ATR, and DNA-dependent protein kinase catalytic subunit (DNA-PK(cs)) are attractive targets to confer enhanced radio and chemosensitivity to tumor cells. We have designed and exogenously delivered plasmids encoding siRNAs targeting these critical kinases to human cancer cells to assess the feasibility of this concept as a clinically translatable experimental therapeutic. siRNA led to a approximately 90% reduction in target protein expression. siRNAs targeting ATM and DNA-PK(cs) gave rise to a dose-reduction factor of approximately 1.4 compared with untransfected and control vector-transfected cells at the clinically relevant radiation doses. This was greater than the radiosensitivity achieved using the phosphatidylinositol 3'-kinase inhibitor Wortmannin or DNA-PK(cs) competitive inhibitor LY294002. A similar increased sensitivity to the alkylating agent methyl methanesulfonate (MMS) was also observed for siRNA-mediated ATR silencing. Together, these data provide strong evidence for the potential use of siRNA as a novel radiation/chemotherapy-sensitizing agent.