Search

Introduction: Among older adults with cancer receiving chemotherapy, frailty indices predict OS and toxicity. Given the increased use of immunotherapy and targeted therapy for advanced non-small cell lung cancer (aNSCLC), we evaluated frailty and Karnofsky Performance Status (KPS) among older adults with aNSCLC receiving chemotherapy, immunotherapy, and/or targeted therapy., Methods: Patients aged ≥ 65 with aNSCLC starting systemic therapy with non-curative intent underwent geriatric assessments over 6 months. We developed a deficit-accumulation frailty index to categorize patients as robust, pre-frail, or frail. To evaluate associations between frailty and KPS with OS, we used Cox proportional hazards models adjusted for race, insurance, and treatment. We used logistic regression to evaluate hospitalizations, functional decline, and severe toxicity., Results: Among 155 patients (median age 73), 45.8% were robust, 36.1% pre-frail, and 18.2% frail; 34.8% had a KPS ≥ 90, 32.9% had a KPS of 80, and 32.3% had a KPS ≤ 70. The median OS was 17.9 months. Pre-frail/frail patients had worse OS compared to robust patients (adjusted hazard ratio [HR] 2.09, 95% CI, 1.31-3.34) and were more likely to be hospitalized (adjusted odds ratio [OR] 2.21, 95% CI, 1.09-4.48), functionally decline (adjusted OR 2.29, 95% CI, 1.09-4.78), and experience grade ≥ 3 hematologic toxicity (adjusted OR 5.18, 95% CI, 1.02-26.03). KPS was only associated with OS., Conclusions: Our frailty index was associated with OS, hospitalization, functional decline, and hematologic AEs among older adults with aNSCLC receiving systemic therapies, while KPS was only associated with OS. Pretreatment frailty assessment may help identify older adults at risk for poor outcomes to optimize decision-making and supportive care., (© The Author(s) 2024. Published by Oxford University Press.)

Although programmed cell death ligand 1 (PD-L1) is best known for its role in immune suppression, tumor-intrinsic functions are emerging. Here, we report that tumor cells that express PD-L1 are sensitive to ferroptosis inducers such as imidazole ketone erastin (IKE). PD-L1 promotes ferroptosis sensitivity because it suppresses SLC7A11 expression and diminishes glutathione levels. Although the use of anti-PD-L1 antibody drug conjugates (ADCs) could be effective for the delivery of ferroptosis inducers to specific tumor populations, the chemistry of most ferroptosis inducers precludes their incorporation in ADCs. To overcome this challenge, we synthesized an antibody nanogel conjugate (ANC) comprised of an anti-PD-L1 antibody conjugated to a nanogel encapsulated with IKE. This ANC targets PD-L1-expressing cells in vitro and in vivo and induces ferroptosis, resulting in tumor suppression. Importantly, this approach is superior to systemic administration of IKE because it enables enhanced delivery of IKE specifically to tumor cells and it requires lower drug doses for efficacy., Competing Interests: Declaration of interests M.W. and A.M.M are founders and shareholders of RedPoint Oncology, Inc., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The high rate of recurrence after radiation therapy in triple-negative breast cancer (TNBC) indicates that novel approaches and targets are needed to enhance radiosensitivity. Here, we report that neuropilin-2 (NRP2), a receptor for vascular endothelial growth factor (VEGF) that is enriched on subpopulations of TNBC cells with stem cell properties, is an effective therapeutic target for sensitizing TNBC to radiotherapy. Specifically, VEGF/NRP2 signaling induces nitric oxide synthase 2 (NOS2) transcription by a mechanism dependent on Gli1. NRP2-expressing tumor cells serve as a hub to produce nitric oxide (NO), an autocrine and paracrine signaling metabolite, which promotes cysteine-nitrosylation of Kelch-like ECH-associated protein 1 (KEAP1) and, consequently, nuclear factor erythroid 2-related factor 2-mediated (NFE2L2-mediated) transcription of antioxidant response genes. Inhibiting VEGF binding to NRP2, using a humanized mAb, results in NFE2L2 degradation via KEAP1, rendering cell lines and organoids vulnerable to irradiation. Importantly, treatment of patient-derived xenografts with the NRP2 mAb and radiation resulted in significant tumor necrosis and regression compared with radiation alone. Together, these findings reveal a targetable mechanism of radioresistance, and they support the use of NRP2 mAb as an effective radiosensitizer in TNBC.

Background: The Accreditation Council for Graduate Medical Education (ACGME) requires that all graduate medical education (GME) programs provide at least 6 paid weeks off for medical, parental, and caregiver leave to residents. However, it is unclear whether all orthopaedic residency programs have adapted to making specific parental leave policies web-accessible since the ACGME's mandate in 2022. This gap in policy knowledge leaves both prospective and current residents in the dark when it comes to choosing residency programs, and knowing what leave benefits they are entitled to when having children during training via birth, surrogacy, adoption, or legal guardianship., Questions/purposes: (1) What percentage of ACGME-accredited orthopaedic surgery residency programs provide accessible parental leave policies on their program's website, their GME website, and through direct contact with their program's administration? (2) What percentage of programs offer specific parental leave policies, generic leave policies, or defer to the Family and Medical Leave Act (FMLA)?, Methods: As indicated in the American Medical Association's 2022 Freida Specialty Guide, 207 ACGME-accredited orthopaedic residency programs were listed. After further evaluation using previous literature's exclusion criteria, 37 programs were excluded based on osteopathic graduate rates. In all, 170 ACGME-accredited allopathic orthopaedic surgery residency programs were identified and included in this study. Three independent reviewers assessed each program website for the presence of an accessible parental leave policy. Each reviewer accessed the program's public webpage initially, and if no parental leave policy was available, they searched the institution's GME webpage. If no policy was found online, the program administrator was contacted directly via email and phone. Available leave policies were further classified into five categories by reviewers: parental leave, generic leave, deferred to FMLA, combination of parental and FMLA, and combination of parental and generic leave., Results: Our results demonstrated that 6% (10 of 170) of orthopaedic residency programs had policy information available on their program's main orthopaedic web page. Fifty nine-percent (101 of 170) of orthopaedic residency programs had a clearly stated policy on their institution's GME website. The remaining 35% (59 of 170) had no information on their public website and required direct communication with program administration to obtain policy information. After directly contacting program administration, 12% (21 of 170) of programs responded to researchers request with a PDF explicitly outlining their policy. Twenty-two percent (38 of 170) of programs did not have an accessible policy available. Of the programs that had available policies, a total of 53% (70 of 132) of programs were categorized as offering explicit parental leave policies, 9% (12 of 132) were categorized as offering general leave policies, and 27% (36 of 132) deferred to FMLA. Seven percent (9 of 132) offered combined parental leave policies with FMLA, and 4% (5 of 132) offered combined general leave policies with FMLA., Conclusion: Although most ACGME-accredited allopathic orthopaedic surgery residency programs met the ACGME requirement of written parental leave policies in 2023, a small minority of programs have clear, accessible parental leave policies provided on their webpage., Clinical Relevance: Parental leave policies should be easily accessible to prospective and current trainees and should clearly state compensation and length of leave. Ensuring orthopaedic surgery residency programs provide accessible and transparent parental leave policies is important for maintaining diversity in prospective applicants and supporting the work-life balance of current residents., Competing Interests: Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 by the Association of Bone and Joint Surgeons.)

Background: Readiness for return to sports involves both physical and psychological aspects of recovery; however, the relationship between psychological and physical variables after anterior cruciate ligament (ACL) reconstruction (ACLR) is poorly understood., Hypothesis: ACLR patients with a higher psychological readiness would demonstrate better functional testing results at 6 months., Study Design: Cross-sectional study; Level of evidence, 3., Methods: Participants were evaluated at 6 months after ACLR with various patient-reported outcome metrics: Hospital for Special Surgery Pediatric Functional Activity Brief Scale, pediatric or adult International Knee Documentation Committee Questionnaire (IKDC), Patient-Reported Outcomes Measurement Information System (PROMIS) - Psychological Stress Experience and ACL - Return to Sport After Injury (ACL-RSI) scale. Functional testing included quadriceps, hamstrings, and gluteal strength testing; Y-balance test; single-leg single hop, crossover hop, and triple hop tests; and timed 6-m hop test. Pearson correlation coefficient and multivariable regression were used to determine associations between the limb symmetry index (LSI) on functional testing and patient-reported outcomes. Those with LSI deficits <20% (better performance) were compared with those with deficits >20% (worse performance)., Results: A total of 229 participants (89 male, 140 female) with a median age of 17 years (range, 10.3-30.6 years) were enrolled. IKDC had a moderate negative correlation with PROMIS - Psychological Stress Experience ( r = -0.39; 95% CI = -0.49, -0.27; P < .001) and a moderate positive correlation with ACL-RSI ( r = 0.55; 95% CI = 0.46, 0.64; P < .001). A total of 151 patients completed functional testing. ACL-RSI demonstrated a positive correlation with single-hop LSI ( r = 0.21; 95% CI = 0.05, 0.35; P = .01) and timed 6-m hop ( r = 0.28; 95% CI, 0.42; P = .001). When adjusting for sex, age, and graft type, patients who had <20% deficit on the single-hop test scored 16.6 points higher on ACL-RSI ( P = .001), and those with <20% deficit on crossover hop testing scored a mean 13.9 points higher on ACL-RSI ( P = .04)., Conclusion: Higher psychological readiness for return to sport was associated with better performance and greater symmetry on hop testing 6 months after ACLR, suggesting a potential link between physical and psychological recovery., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: M.D.M. has received royalties from Elsevier and serves on the board of directors for PRiSM. M.A.C. has received royalties from Springer Inc and serves on the board of directors for PRiSM. Y-M.Y. is a consultant for Smith+Nephew and serves on the editorial board for the American Journal of Sports Medicine. E.J.S. has received education payments from Smith+Nephew and hospitality payments from Stryker and Zimmer Biomet Holdings. M.S.K. has received royalties from OrthoPediatrics and education payments from Kairos Surgical. D.E.K. has received education payments from Kairos Surgical and consulting fees from DePuy Synthes Products. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2024.)

Purpose: Patients from diverse racial, ethnic, and socio-economic backgrounds may be particularly vulnerable to experiencing undue social and financial burdens ("collateral damage") from a metastatic breast cancer (mBC) diagnosis; however, these challenges have not been well explored in diverse populations., Methods: From May 2022 to May 2023, English- or Spanish-speaking adults with mBC treated at four New York-Presbyterian (NYP) sites were invited to complete a survey that assessed collateral damage, social determinants of health, physical and psychosocial well-being, and patient-provider communication. Fisher's exact and the Kruskal-Wallis rank-sum tests assessed differences by race and ethnicity., Results: Of 87 respondents, 14% identified as Hispanic, 28% non-Hispanic Black (NHB), 41% non-Hispanic White (NHW), 7% Asian American Pacific Islander (AAPI), and 10% other/multiracial. While 100% of Hispanic, NHW, and AAPI participants reported stable housing, 29% of NHB participants were worried about losing housing (p = 0.002). Forty-two percent of Hispanic and 46% of NHB participants (vs. 8%, NHW and 0%, AAPI, p = 0.005) were food insecure; 18% of Hispanic and 17% of NHB adults indicated lack of reliable transportation in the last year (vs. 0%, NHW/AAPI, p = 0.033). Participants were generally satisfied with the quality of communication that they had with their healthcare providers and overall physical and mental well-being were modestly poorer relative to healthy population norms., Conclusions: In our study, NHB and Hispanic mBC patients reported higher levels of financial concern and were more likely to experience food and transportation insecurity compared to NHW patients. Systematically connecting patients with resources to address unmet needs should be prioritized to identify feasible approaches to support economically vulnerable patients following an mBC diagnosis., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Patients with castration-resistant prostate cancer (CRPC) are generally unresponsive to tumor targeted and immunotherapies. Whether genetic alterations acquired during the evolution of CRPC impact immune and immunotherapy responses is largely unknown. Using our innovative electroporation-based mouse models, we generated distinct genetic subtypes of CRPC found in patients and uncovered unique immune microenvironments. Specifically, mouse and human prostate tumors with MYC amplification and p53 disruption had weak cytotoxic lymphocyte infiltration and an overall dismal prognosis. MYC and p53 cooperated to induce tumor intrinsic secretion of VEGF, which by signaling through VEGFR2 expressed on CD8 + T cells, could directly inhibit T cell activity. Targeting VEGF-VEGFR2 signaling in vivo led to CD8 + T cell-mediated tumor and metastasis growth suppression and significantly increased overall survival in MYC and p53 altered CPRC. VEGFR2 blockade also led to induction of PD-L1, and in combination with PD-L1 immune checkpoint blockade produced anti-tumor efficacy in multiple preclinical CRPC mouse models. Thus, our results identify a genetic mechanism of immune suppression through VEGF signaling in prostate cancer that can be targeted to reactivate immune and immunotherapy responses in an aggressive subtype of CRPC., Significance: Though immune checkpoint blockade (ICB) therapies can achieve curative responses in many treatment-refractory cancers, they have limited efficacy in CRPC. Here we identify a genetic mechanism by which VEGF contributes to T cell suppression, and demonstrate that VEGFR2 blockade can potentiate the effects of PD-L1 ICB to immunologically treat CRPC., Competing Interests: DECLARATION OF INTERESTS M.R. is a consultant for Boehringer Ingelheim.

Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: J.N.K. has received honoraria from Pfizer. E.G.M. has received support for education from Peerless Surgical and Kairos Surgical. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Purpose: A metastatic breast cancer (mBC) diagnosis can affect physical and emotional well-being. However, racial and ethnic differences in receipt of outpatient psychosocial care and supportive care medications in adults with mBC are not well described., Methods: Adults with mBC were identified in the INSIGHT-Clinical Research Network, a database inclusive of >12 million patients receiving care across six New York City health systems. Outpatient psychosocial care was operationalized using Common Procedure Terminology codes for outpatient psychotherapy or counseling. Psychosocial/supportive care medications were defined using Rx Concept Unique Identifier codes. Associations between race/ethnicity and outpatient care and medication use were evaluated using logistic regression., Results: Among 5,429 adults in the analytic cohort, mean age was 61 years and <1% were male; 53.6% were non-Hispanic White (NHW), 21.4% non-Hispanic Black (NHB), 15.9% Hispanic, 6.1% Asian/Native Hawaiian/Pacific Islander (A/NH/PI), and 3% other or unknown. Overall, 4.1% had ≥one outpatient psychosocial care visit and 63.4% were prescribed ≥one medication. Adjusted for age, compared with NHW, Hispanic patients were more likely (odds ratio [OR], 2.14 [95% CI, 1.55 to 2.92]) and A/NH/PI patients less likely (OR, 0.35 [95% CI, 0.12 to 0.78]) to have an outpatient visit. NHB (OR, 0.59 [95% CI, 0.51 to 0.68]) and Asian (OR, 0.36 [95% CI, 0.29 to 0.46]) patients were less likely to be prescribed medications., Conclusion: Despite the prevalence of depression, anxiety, and distress among patients with mBC, we observed low utilization of psychosocial outpatient care. Supportive medication use was more prevalent, although differences observed by race/ethnicity suggest that unmet needs exist.

Background: Shoulder instability in pediatric and adolescent patients can be treated operatively via arthroscopic or open procedures, but there a paucity of evidence to support the incidence of these treatment modalities over time. It is hypothesized that the overall rate of arthroscopic shoulder stabilization procedures will increase over time. Given advances in open stabilization techniques, we also hypothesized that the rate of open procedures may be increasing., Methods: The Pediatric Health Information System database was queried for patients 19 years or younger who underwent arthroscopic or open surgery for shoulder instability and pediatric orthopedic surgeries between 2009 and 2019. Data from 37 of the 52 pediatric hospitals with Pediatric Health Information System data was included in the analysis. Annual and overall incidence rates were estimated for arthroscopic and open procedures, along with 95% confidence intervals. The yearly incidence for secondary (homolateral revisions) or primary contralateral arthroscopic and open procedures was also examined., Results: 4747 patients underwent primary arthroscopic procedures and 384 patients had primary open procedures. There were 8.2 primary open shoulder stabilization procedures per 10,000 orthopedic surgical patients in 2009, which decreased by 19% to 6.7 per 10,000 orthopedic surgical patients in 2019. There was an increase seen in both arthroscopic and open secondary stabilization procedures. In 2009, there were 0.97 secondary arthroscopic procedures per 10,000 orthopedic surgical patients. This increased by 672% to 7.5 per 10,000 orthopedic surgical patients in 2019. No secondary open procedures were recorded in 2009; however, an increase to 2.6 secondary open procedures per 10,000 orthopedic surgical patients was seen by 2019., Conclusion: This study shows a rise in primary arthroscopic pediatric shoulder stabilization surgeries across the U.S. over the last decade. There was a slight decrease in the rate of primary open shoulder stabilization surgeries and an increase in both arthroscopic and open secondary (homolateral revisions or primary contralateral) shoulder stabilization surgeries, implying an increasing revision burden in this population., (© 2024 The Author(s).)

We are interested in the contribution of integrins and the extracellular matrix to epithelial differentiation in carcinomas. This study was motivated by our finding that the Hippo effectors YAP and TAZ can sustain the expression of laminin 332 (LM332), the predominant ECM ligand for the integrin β4, in breast carcinoma cells with epithelial differentiation. More specifically, we observed that YAP and TAZ regulate the transcription of the LAMC2 subunit of LM332. Given that the β4-LM332 axis is associated with epithelial differentiation and YAP/TAZ have been implicated in carcinoma de-differentiation, we sought to resolve this paradox. Here, we observed that the β4 integrin sustains the expression of miR-200s that target the transcription factor ZEB1 and that ZEB1 has a pivotal role in determining the nature of YAP/TAZ-mediated transcription. In the presence of β4, ZEB1 expression is repressed enabling YAP/TAZ/TEAD-mediated transcription of LAMC2. The absence of β4, however, induces ZEB1, and ZEB1 binds to the LAMC2 promoter to inhibit LAMC2 transcription. YAP/TAZ-mediated regulation of LAMC2 has important functional consequences because we provide evidence that LM332 enables carcinoma cells to resist ferroptosis in concert with the β4 integrin., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative risk factors contributing to poor outcomes after arthroscopic partial meniscectomy (APM) have not yet been consolidated and codified into an index scoring system used to predict APM success., Purpose: To create an index score using available preoperative factors to predict the likelihood of favorable postoperative outcomes after APM., Study Design: Case-control study; Level of evidence, 3., Methods: A consecutive cohort of patients undergoing primary APM were enrolled in this study. Patients completed pre- and postoperative patient-reported outcome measure (PROM) questionnaires that included the Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, Veterans RAND 12-Item Health Survey (VR-12 Physical and Mental), and Marx Activity Rating Scale (MARS). Multivariable logistic regression models were performed to evaluate independent predictors of KOOS Pain, Symptoms, and Activities of Daily Living scores and achievement of the minimal clinically important difference (MCID) and substantial clinical benefit (SCB). The authors assigned points to each variable proportional to its odds ratio, rounded to the nearest integer, to generate the index score., Results: In total, 468 patients (mean age, 49 years [SD, 10.4 years; range, 19-81 years]) were included in this study. In the univariate analysis, shorter symptom duration, lower Kellgren-Lawrence (KL) grade, lower preoperative KOOS Pain value, and lower VR-12 Physical score were associated with a higher likelihood of clinical improvement at 1 year. In the multivariable model for clinical improvement with MCID, symptom duration (<3 months: OR, 3.00 [95% CI, 1.45-6.19]; 3-6 months: OR, 2.03 [95% CI, 1.10-3.72], compared with >6 months), KL grade (grade 0: OR, 3.54 [95% CI, 1.66-7.54]; grade 1: OR, 3.04 [95% CI, 1.48-6.26]; grade 2: OR, 2.31 [95% CI, 1.02-5.27], compared with grade 3), and preoperative KOOS Pain value (score <45: OR, 3.00 [95% CI, 1.57-5.76]; score of 45-60: OR, 2.80 [95% CI, 1.47-5.35], compared with score >60) were independent significant predictors for clinical improvement. The scoring algorithm demonstrated that a higher total score predicted a higher likelihood of achieving the MCID: 0 = 40%, 1 = 68%, 2 = 80%, 3 = 89%, and 4 = 96%., Conclusion: Using this model, the authors developed an index score that, using preoperative factors, can help identify which patients will achieve clinical improvement after APM. Longer symptom duration and higher KL grade were associated with a decreased likelihood of clinical improvement as measured by KOOS Pain at 1 year postoperatively., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: J.N.K. has received honoraria from Pfizer. E.G.M. has received support for education from Peerless Surgical and Kairos Surgical. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Understanding the cell biological mechanisms that enable tumor cells to persist after therapy is necessary to improve the treatment of recurrent disease. Here, we demonstrate that transient receptor potential channel 6 (TRPC6), a channel that mediates calcium entry, contributes to the properties of breast cancer stem cells, including resistance to chemotherapy, and that tumor cells that persist after therapy are dependent on TRPC6. The mechanism involves the ability of TRPC6 to regulate integrin α6 mRNA splicing. Specifically, TRPC6-mediated calcium entry represses the epithelial splicing factor ESRP1 (epithelial splicing regulatory protein 1), which enables expression of the integrin α6B splice variant. TRPC6 and α6B function in tandem to facilitate stemness and persistence by activating TAZ and, consequently, repressing Myc. Therapeutic inhibition of TRPC6 sensitizes triple-negative breast cancer (TNBC) cells and tumors to chemotherapy by targeting the splicing of α6 integrin mRNA and inducing Myc. These data reveal a Ca 2+ -dependent mechanism of chemotherapy-induced persistence, which is amenable to therapy, that involves integrin mRNA splicing., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Identifying metabolic steps that are specifically required for the survival of cancer cells but are dispensable in normal cells remains a challenge 1 . Here we report a therapeutic vulnerability in a sugar nucleotide biosynthetic pathway that can be exploited in cancer cells with only a limited impact on normal cells. A systematic examination of conditionally essential metabolic enzymes revealed that UXS1, a Golgi enzyme that converts one sugar nucleotide (UDP-glucuronic acid, UDPGA) to another (UDP-xylose), is essential only in cells that express high levels of the enzyme immediately upstream of it, UGDH. This conditional relationship exists because UXS1 is required to prevent excess accumulation of UDPGA, which is produced by UGDH. UXS1 not only clears away UDPGA but also limits its production through negative feedback on UGDH. Excess UDPGA disrupts Golgi morphology and function, which impedes the trafficking of surface receptors such as EGFR to the plasma membrane and diminishes the signalling capacity of cells. UGDH expression is elevated in several cancers, including lung adenocarcinoma, and is further enhanced during chemoresistant selection. As a result, these cancer cells are selectively dependent on UXS1 for UDPGA detoxification, revealing a potential weakness in tumours with high levels of UGDH., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Prostate cancers are largely unresponsive to immune checkpoint inhibitors (ICIs), and there is strong evidence that programmed death-ligand 1 (PD-L1) expression itself must be inhibited to activate antitumor immunity. Here, we report that neuropilin-2 (NRP2), which functions as a vascular endothelial growth factor (VEGF) receptor on tumor cells, is an attractive target to activate antitumor immunity in prostate cancer because VEGF-NRP2 signaling sustains PD-L1 expression. NRP2 depletion increased T cell activation in vitro. In a syngeneic model of prostate cancer that is resistant to ICI, inhibition of the binding of VEGF to NRP2 using a mouse-specific anti-NRP2 monoclonal antibody (mAb) resulted in necrosis and tumor regression compared with both an anti-PD-L1 mAb and control immunoglobulin G. This therapy also decreased tumor PD-L1 expression and increased immune cell infiltration. We observed that the NRP2 , VEGFA , and VEGFC genes are amplified in metastatic castration-resistant and neuroendocrine prostate cancer. We also found that individuals with NRP2 High PD-L1 High metastatic tumors had lower androgen receptor expression and higher neuroendocrine prostate cancer scores than other individuals with prostate cancer. In organoids derived from patients with neuroendocrine prostate cancer, therapeutic inhibition of VEGF binding to NRP2 using a high-affinity humanized mAb suitable for clinical use also diminished PD-L1 expression and caused a substantial increase in immune-mediated tumor cell killing, consistent with the animal studies. These findings provide justification for the initiation of clinical trials using this function-blocking NRP2 mAb in prostate cancer, especially for patients with aggressive disease.

Although blocking the binding of vascular endothelial growth factor (VEGF) to neuropilin-2 (NRP2) on tumor cells is a potential strategy to treat aggressive carcinomas, a lack of effective reagents that can be used clinically has hampered this potential therapy. Here, we describe the generation of a fully humanized, high-affinity monoclonal antibody (aNRP2-10) that specifically inhibits the binding of VEGF to NRP2, conferring antitumor activity without causing toxicity. Using triple-negative breast cancer as a model, we demonstrated that aNRP2-10 could be used to isolate cancer stem cells (CSCs) from heterogeneous tumor populations and inhibit CSC function and epithelial-to-mesenchymal transition. aNRP2-10 sensitized cell lines, organoids, and xenografts to chemotherapy and inhibited metastasis by promoting the differentiation of CSCs to a state that is more responsive to chemotherapy and less prone to metastasis. These data provide justification for the initiation of clinical trials designed to improve the response of patients with aggressive tumors to chemotherapy using this monoclonal antibody.

Aim: Stakeholder engagement is central to comparative effectiveness research yet there are gaps in definitions of success. We used a framework developed by Lavallee  et al. defining effective engagement criteria to evaluate stakeholder engagement during a pragmatic cluster-randomized trial. Methods: Semi-structured interviews were developed from the framework and completed to learn about members' experiences. Interviews were analyzed in a deductive approach for themes related to the effective engagement criteria. Results: Thirteen members participated and described: respect for ideas, time to achieve consensus, access to information and continuous feedback as areas of effective engagement. The primary criticism was lack of diversity. Discussion: Feedback was positive, particularly among themes of respect, trust and competence, and led to development of a list of best practices for engagement. The framework was successful for evaluating engagement. Conclusion: Standardized frameworks allow studies to formally evaluate their stakeholder engagement approach and develop best practices for future research.

Background: The rate of anterior cruciate ligament (ACL) reconstruction is increasing over time in pediatric/adolescent populations, but there is less evidence to support how concomitant meniscal procedures are changing over time. There are also less data to suggest which characteristics are associated with meniscectomy versus meniscal repair treatment., Hypothesis: Age, sex, race/ethnicity, income, and insurance type may independently affect the rate of concomitant meniscal procedures and treatment modalities in pediatric patients with ACL reconstruction., Study Design: Descriptive epidemiology study., Methods: The Pediatric Health Information System database was queried for all patients aged ≤18 years who underwent ACL reconstruction with or without concomitant meniscal procedures from 2015 to 2019. Basic demographic data including age, sex, self-identified race/ethnicity, rural-urban commuting area code, predicted median income, and insurance status were collected. Linear regression was used to model trends and multiple logistic regression modeling was used to test for associations., Results: A total of 14,398 patients aged ≤18 years underwent ACL reconstruction during the study period, with 8337 patients (58%) having concomitant meniscal procedures with a 1.24-fold increase over 5 years. Of the concomitant meniscal treatment cohort, 41% had a meniscectomy and 59% had meniscal repair. There was a 0.82-fold change in meniscectomy and a 1.67-fold increase in meniscal repair during the study period. Male patients, older patients, Black race, living in an urban area, and those with nonprivate insurance had increased odds of undergoing a concomitant meniscal procedure (all P < .05). Patients of non-White race and those with nonprivate insurance had increased odds of having a meniscectomy versus meniscal repair (all P < .05). There were no associations detected between income bracket and the outcomes in this study., Conclusion: This study shows that in pediatric and adolescent patients undergoing ACL reconstruction, there was a rise in concomitant meniscal procedures from 2015 to 2019. In addition, patients of non-White race and those with nonprivate insurance have increased odds of undergoing meniscectomy versus meniscal repair.

Background: The negative effects of bullying, discrimination, harassment, and sexual harassment (BDHS) on well-being and productivity of surgical residents in training have been well documented. Despite this, little has changed over the past decade and these behaviors continue. The purpose of this study was to determine the prevalence of each abusive behavior experienced by residents, identify the perpetrators, and examine the reporting tendency., Methods: A systematic review of articles published between 2010 and 2020 in the MEDLINE, EMBASE, and Cochrane databases was performed following PRISMA guidelines. The following search terms were used: bullying, harassment, sexual harassment, discrimination, abuse, residency, surgery, orthopedic surgery, general surgery, otolaryngology, obstetrics, gynecology, urology, plastic surgery, and training., Results: Twenty-five studies with 29,980 surgical residents were included. Sixty-three percent, 43, 29, and 27% of surgical residents experienced BDHS, respectively. Female residents reported experiencing all BDHS behaviors more often. Thirty-seven percent of resident respondents reported burnout, and 33% reported anxiety/depression. Attending surgeons, followed by senior co-residents, were the most common perpetrators. Seventy-one percent did not report the behavior to their institution. Fifty-one percent stated this was due to fear of retaliation. Of those who reported their experiences, 56% stated they had a negative experience reporting., Conclusion: Our review demonstrates high prevalence rates of BDHS experienced by residents during surgical training, which have been associated with burnout, anxiety, and depression. The majority of residents did not report BDHS due to fear of retaliation. Residency programs need to devise methods to have a platform for residents to safely voice their complaints., (© 2022. The Author(s) under exclusive licence to Société Internationale de Chirurgie.)

Although the immune checkpoint function of PD-L1 has dominated its study, we report that PD-L1 has an unanticipated intrinsic function in promoting the dynamics of persistent cell migration. PD-L1 concentrates at the rear of migrating carcinoma cells where it facilitates retraction, resulting in the formation of PD-L1-containing retraction fibers and migrasomes. PD-L1 promotes retraction by interacting with and localizing the β4 integrin to the rear enabling this integrin to stimulate contractility. This mechanism involves the ability of PD-L1 to maintain cell polarity and lower membrane tension at the cell rear compared with the leading edge that promotes the localized interaction of PD-L1 and the β4 integrin. This interaction enables the β4 integrin to engage the actin cytoskeleton and promote RhoA-mediated contractility. The implications of these findings with respect to cell-autonomous functions of PD-L1 and cancer biology are significant., (© 2022 Wang et al.)

We pursued the hypothesis that specific glycans can be used to distinguish breast cancer stem cells (CSCs) and influence their function. Comparison of CSCs and non-CSCs from multiple breast cancer models revealed that CSCs are distinguished by expression of α2,3 sialylated core2 O-linked glycans. We identified a lectin, SLBR-N, which binds to O-linked α2,3 sialic acids, that was able to enrich for CSCs in vitro and in vivo. This O-glycan is expressed on CD44 and promotes its interaction with hyaluronic acid, facilitating CD44 signaling and CSC properties. In contrast, FUT3, which contributes to sialyl Lewis X (sLeX) production, is preferentially expressed in the non-CSC population, and it antagonizes CSC function. Collectively, our data indicate that SLBR-N can be more efficient at enriching for CSCs than CD44 itself because its use avoids the issues of CD44 splicing and glycan status. These data also reveal how differential glycosylation influences CSC fate.

The purpose of this study was to provide an overview of the available evidence on peroneal tendon tears and the outcomes after surgical intervention. A systematic review of the literature was performed using MEDLINE, Embase, and Cochrane. Criteria for inclusion were clinical studies reporting outcomes after treatment for peroneal tendon tear within the last 10 years. Nine studies evaluating 336 patients (146 males/190 females) and 336 ankles were included in this review. The mean age of included patients was 46.3 years (range, 46-56.9 years). The weighted mean follow-up was 23.82 months (range 9.2-78 months. Five surgical interventions were reported: primary repair with tenodesis, primary repair without tenodesis, FDL tendon transfer, FHL tendon transfer, and allograft reconstruction. Four studies recorded the AOFAS score, with a weighted mean preoperative score of 69.58 and a weighted mean postoperative score of 88.82. Six studies measured the VAS score showing an improvement from a mean weighted preoperative score of 4.68 to a mean weighted postoperative score of 1.2. FAAM score was measured in 3 studies, which showed an improvement from 41.1 preoperatively to 84.4 postoperatively. The average overall complication rate was 38.7% (130/336) with the most commonly reported minor complication being ankle pain, which made up 46.2% of all minor complications (56/121). Primary repair without tenodesis was associated with a higher complication rate compared to any other surgical intervention (p=.001176). The current systematic review showed that overall clinical outcomes were positive in lieu of the different modalities of surgical intervention for peroneal tendon tears., (Copyright © 2021 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Understanding how cancer cells resist ferroptosis is a significant problem that impacts ongoing efforts to stimulate ferroptosis as a therapeutic strategy. We reported that prominin2 is induced by ferroptotic stimuli and functions to resist ferroptotic death. Although this finding has significant implications for therapy, specific prominin2 inhibitors are not available. We rationalized that the mechanism by which prominin2 expression is induced by ferroptotic stress could be targeted, expanding the range of options to overcome ferroptosis resistance. Here, we show that that 4-hydroxynonenal (4HNE), a specific lipid metabolite formed from the products of lipid peroxidation stimulates PROM2 transcription by a mechanism that involves p38 MAP kinase-mediated activation of HSF1 and HSF1-dependent transcription of PROM2. HSF1 inhibitors sensitize a wide variety of resistant cancer cells to drugs that induce ferroptosis. Importantly, the combination of a ferroptosis-inducing drug and an HSF1 inhibitor causes the cytostasis of established tumors in mice, although neither treatment alone is effective. These data reveal a novel approach for the therapeutic induction of ferroptosis in cancer., (© 2021 The Authors. Published under the terms of the CC BY 4.0 license.)

Extracellular vesicles (EVs) play key roles in transporting key molecular constituents as cargo for extracellular trafficking. While several approaches have been developed to extract EVs from mammalian cells, the specific method of EV isolation can have a profound effect on membrane integrity and yield. Here, we describe a step-by-step procedure to separate EVs from adherent epithelial cells using differential ultracentrifugation. Separated EVs can be further analyzed by immunoblotting, mass spectrometry, and transmission electron microscopy to derive EV yield and morphology. For complete details on the use and execution of this protocol, please refer to Brown et al. (2019)., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Cancer stem cells (CSCs) are a crucial therapeutic target because of their role in resistance to chemo- and radiation therapy, metastasis, and tumor recurrence. Differentiation therapy presents a potential strategy for "defanging" CSCs. To date, only a limited number of small-molecule and nanomaterial-based differentiating agents have been identified. We report here the integrated use of nanoparticle engineering and hypothesis-free sensing to identify nanoparticles capable of efficient differentiation of CSCs into non-CSC phenotypes. Using this strategy, we identified a nanoparticle that induces CSC differentiation by increasing intracellular reactive oxygen species levels. Importantly, this unreported phenotype is more susceptible to drug treatment than either CSCs or non-CSCs, demonstrating a potentially powerful strategy for anticancer therapeutics.

Competing Interests: Conflict of InterestAngela Mercurio, BS, and Arianna L. Gianakos, DO, declare that they have no conflict of interest. Mary K. Mulcahey reports being a paid consultant, presenter, or speaker to Arthrex, Inc., and Arthroscopy Association of North America, and a board or committee member at AAOS, ACSM Translational Journal, American Orthopaedic Society for Sports Medicine, Ortho Info, Ruth Jackson Orthopaedic Society, and The Forum. Karen Sutton, MD, reports being paid a consultant, presenter, or speaker to Johnson and Johnson; an unpaid consultant to ESPN-W and SportsMD; and a board or committee member at AAOS, American Orthopaedic Society for Sports Medicine, Bassett Society, Ruth Jackson Orthopaedic Society, The Forum, US Lacrosse, and World Lacrosse.

Ewing sarcoma (EWS) is the second most common bone and soft tissue-associated malignancy in children and young adults. It is driven by the fusion oncogene EWS/FLI1 and characterized by rapid growth and early metastasis. We have previously discovered that the mRNA binding protein IGF2BP3 constitutes an important biomarker for EWS as high expression of IGF2BP3 in primary tumors predicts poor prognosis of EWS patients. We additionally demonstrated that IGF2BP3 enhances anchorage-independent growth and migration of EWS cells suggesting that IGF2BP3 might work as molecular driver and predictor of EWS progression. The aim of this study was to further define the role of IGF2BP3 in EWS progression. We demonstrated that high IGF2BP3 mRNA expression levels correlated with EWS metastasis and disease progression in well-characterized EWS tumor specimens. EWS tumors with high IGF2BP3 levels were characterized by a specific gene signature enriched in chemokine-mediated signaling pathways. We also discovered that IGF2BP3 regulated the expression of CXCR4 through CD164. Significantly, CD164 and CXCR4 colocalized at the plasma membrane of EWS cells upon CXCL12 stimulation. We further demonstrated that IGF2BP3, CD164, and CXCR4 expression levels correlated in clinical samples and the IGF2BP3/CD164/CXCR4 signaling pathway promoted motility of EWS cells in response to CXCL12 and under hypoxia conditions. The data presented identified CD164 and CXCR4 as novel IGF2BP3 downstream functional effectors indicating that the IGF2BP3/CD164/CXCR4 oncogenic axis may work as critical modulator of EWS aggressiveness. In addition, IGF2BP3, CD164, and CXCR4 expression levels may constitute a novel biomarker panel predictive of EWS progression., (Copyright © 2020 Mancarella, Caldoni, Ribolsi, Parra, Manara, Mercurio, Morrione and Scotlandi.)

Understanding how cells resist ferroptosis is necessary for exploiting this iron-dependent mode of cell death for the treatment of cancer and other diseases. We discovered that cells resist ferroptosis by enabling a PROMININ2-dependent iron export pathway involving multivesicular body/exosome trafficking of iron out of the cell, diminishing the intracellular iron needed for ferroptosis., (© 2020 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Tumors can undergo long periods of dormancy, with cancer cells entering a largely quiescent, nonproliferative state before reactivation and outgrowth. To understand the role of the extracellular matrix (ECM) in regulating tumor dormancy, we created an in vitro cell culture system with carefully controlled ECM substrates to observe entrance into and exit from dormancy with live imaging. We saw that cell populations capable of surviving entrance into long-term dormancy were heterogeneous, containing quiescent, cell cycle-arrested, and actively proliferating cells. Cell populations capable of entering dormancy formed an organized, fibrillar fibronectin matrix via α v β 3 and α 5 β 1 integrin adhesion, ROCK-generated tension, and TGFβ2 stimulation, and cancer cell outgrowth after dormancy required MMP-2-mediated fibronectin degradation. We propose this approach as a useful, in vitro method to study factors important in regulating dormancy, and we used it here to elucidate a role for fibronectin deposition and MMP activation., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Understanding how progenitor cell function is regulated in the mammary gland is an important developmental problem that has significant implications for breast cancer. Although it had been assumed that the expression the α6β4 integrin (β4) is restricted to the basal lineage, we report that alveolar progenitor cells in the mouse mammary gland also express this integrin based on analysis of single cell RNA-Seq data. Subsequent experiments using a mouse mammary epithelial cell line (NMuMG) confirmed this finding and revealed that β4 is essential for maintaining progenitor function as assessed by serial passage mammosphere assays. These data were substantiated by analyzing the alveolar progenitor population isolated from nulliparous mouse mammary glands. Based on the finding that the alveolar progenitor cells express Whey Acidic Protein (WAP), WAP-Cre mice were crossed with itgβ4 flox/flox mice to generate conditional knock-out of β4 in alveolar progenitor cells. These itgβ4 flox/flox WAP-Cre + mice exhibited significant defects in alveologenesis and milk production during pregnancy compared to itgβ4 flox/flox WAP-Cre - mice, establishing a novel role for the β4 integrin in alveolar progenitor function and alveologenesis., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Ferroptosis, regulated cell death characterized by the iron-dependent accumulation of lethal lipid reactive oxygen species, contributes to tissue homeostasis and numerous pathologies, and it may be exploited for therapy. Cells differ in their sensitivity to ferroptosis, however, and a key challenge is to understand mechanisms that contribute to resistance. Using RNA-seq to identify genes that contribute to ferroptosis resistance, we discovered that pro-ferroptotic stimuli, including inhibition of the lipid hydroperoxidase GPX4 and detachment from the extracellular matrix, induce expression of prominin2, a pentaspanin protein implicated in regulation of lipid dynamics. Prominin2 facilitates ferroptosis resistance in mammary epithelial and breast carcinoma cells. Mechanistically, prominin2 promotes the formation of ferritin-containing multivesicular bodies (MVBs) and exosomes that transport iron out of the cell, inhibiting ferroptosis. These findings reveal that ferroptosis resistance can be driven by a prominin2-MVB-exosome-ferritin pathway and have broad implications for iron homeostasis, intracellular trafficking, and cancer., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The ability to monitor changes in the expression and localization of integrins is essential for understanding their contribution to development, tissue homeostasis and disease. Here, we pioneered the use of Crispr/Cas9 genome editing to tag an allele of the β4 subunit of the α6β4 integrin. A tdTomato tag was inserted with a linker at the C-terminus of integrin β4 in mouse mammary epithelial cells. Cells harboring this tagged allele were similar to wild-type cells with respect to integrin β4 surface expression, association with the α6 subunit, adhesion to laminin and consequent signaling. These integrin β4 reporter cells were transformed with YAP (also known as YAP1), which enabled us to obtain novel insight into integrin β4 dynamics in response to a migratory stimulus (scratch wound) by live-cell video microscopy. An increase in integrin β4 expression in cells proximal to the wound edge was evident, and a population of integrin β4-expressing cells that exhibited unusually rapid migration was identified. These findings could shed insight into integrin β4 dynamics during invasion and metastasis. Moreover, these integrin β4 reporter cells should facilitate studies on the contribution of this integrin to mammary gland biology and cancer.This article has an associated First Person interview with the first author of the paper., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

Vascular endothelial growth factor (VEGF) signaling in tumor cells mediated by neuropilins (NRPs) contributes to the aggressive nature of several cancers, including triple-negative breast cancer (TNBC), independently of its role in angiogenesis. Understanding the mechanisms by which VEGF-NRP signaling contributes to the phenotype of such cancers is a significant and timely problem. We report that VEGF-NRP2 promote homologous recombination (HR) in BRCA1 wild-type TNBC cells by contributing to the expression and function of Rad51, an essential enzyme in the HR pathway that mediates efficient DNA double-strand break repair. Mechanistically, we provide evidence that VEGF-NRP2 stimulates YAP/TAZ-dependent Rad51 expression and that Rad51 is a direct YAP/TAZ-TEAD transcriptional target. We also discovered that VEGF-NRP2-YAP/TAZ signaling contributes to the resistance of TNBC cells to cisplatin and that Rad51 rescues the defects in DNA repair upon inhibition of either VEGF-NRP2 or YAP/TAZ. These findings reveal roles for VEGF-NRP2 and YAP/TAZ in DNA repair, and they indicate a unified mechanism involving VEGF-NRP2, YAP/TAZ, and Rad51 that contributes to resistance to platinum chemotherapy., Competing Interests: The authors declare no conflict of interest.

Although changes in alternative splicing have been observed in cancer, their functional contributions still remain largely unclear. Here we report that splice isoforms of the cancer stem cell (CSC) marker CD44 exhibit strikingly opposite functions in breast cancer. Bioinformatic annotation in patient breast cancer in The Cancer Genome Atlas (TCGA) database reveals that the CD44 standard splice isoform (CD44s) positively associates with the CSC gene signatures, whereas the CD44 variant splice isoforms (CD44v) exhibit an inverse association. We show that CD44s is the predominant isoform expressed in breast CSCs. Elimination of the CD44s isoform impairs CSC traits. Conversely, manipulating the splicing regulator ESRP1 to shift alternative splicing from CD44v to CD44s leads to an induction of CSC properties. We further demonstrate that CD44s activates the PDGFRβ/Stat3 cascade to promote CSC traits. These results reveal CD44 isoform specificity in CSC and non-CSC states and suggest that alternative splicing provides functional gene versatility that is essential for distinct cancer cell states and thus cancer phenotypes., (© 2019 Zhang et al.; Published by Cold Spring Harbor Laboratory Press.)

The function of vascular endothelial growth factor (VEGF) in cancer extends beyond angiogenesis and vascular permeability. Specifically, VEGF-mediated signaling occurs in tumor cells and this signaling contributes to key aspects of tumorigenesis including the self-renewal and survival of cancer stem cells (CSCs). In addition to VEGF receptor tyrosine kinases, the neuropilins (NRPs) are critical for mediating the effects of VEGF on CSCs, primarily because of their ability to impact the function of growth factor receptors and integrins. VEGF/NRP signaling can regulate the expression and function of key molecules that have been implicated in CSC function including Rho family guanosine triphosphatases (GTPases) and transcription factors. The VEGF/NRP signaling axis is a prime target for therapy because it can confer resistance to standard chemotherapy, which is ineffective against most CSCs. Indeed, several studies have shown that targeting either NRP1 or NRP2 can inhibit tumor initiation and decrease resistance to other therapies.

Vascular endothelial growth factor (VEGF) stimulates endothelial cells to promote both developmental and pathological angiogenesis. VEGF also directly affects tumor cells and is associated with the initiation, progression, and recurrence of tumors, as well as the emergence and maintenance of cancer stem cells (CSCs). Studies have uncovered the importance of the transcriptional regulators YAP and TAZ in mediating VEGF signaling. For example, VEGF stimulates the GTPase activity of Rho family members and thereby alters cytoskeletal dynamics, which contributes to the activation of YAP and TAZ. In turn, YAP- and TAZ-mediated changes in gene expression sustain Rho family member activity and cytoskeletal effects to promote both vascular growth and remodeling in endothelial cells and the acquisition of stem-like traits in tumor cells. In this Review, we discuss how these findings further explain the pathophysiological roles of VEGF and YAP/TAZ, identify their connections to other receptor-mediated pathways, and reveal ways of therapeutically targeting their convergent signals in patients., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Ferroptosis is an iron-dependent form of programmed cell death characterized by the accumulation of lipid-targeting reactive oxygen species that kill cells by damaging their plasma membrane. The lipid repair enzyme GSH peroxidase 4 (GPX4) protects against this oxidative damage and enables cells to resist ferroptosis. Recent work has revealed that matrix-detached carcinoma cells can be susceptible to ferroptosis and that they can evade this fate through the signaling properties of the α6β4 integrin, which sustains GPX4 expression. Although these findings on ferroptosis are provocative, they differ from those in previous studies indicating that matrix-detached cells are prone to apoptosis via a process referred to as anoikis. In an effort to reconcile these discrepant findings, here we observed that matrix-detached epithelial and carcinoma cells cluster spontaneously via a mechanism that involves the cell adhesion protein PVRL4 (also known as Nectin-4). We found that this clustering process allows these cells to survive by stimulating a PVRL4/α6β4/Src signaling axis that sustains GPX4 expression and buffers against lipid peroxidation. In the absence of α6β4, PVRL4-mediated clustering induced an increase in lipid peroxidation that was sufficient for triggering ferroptosis. When the clustering was inhibited, single cells did not exhibit a significant increase in lipid peroxidation in the absence of α6β4, and they were more susceptible to apoptosis than to ferroptosis. These results indicate that ferroptosis induction depends on cell clustering in matrix-detached cells that lack α6β4 and imply that the fate of matrix-detached cells can be determined by the state of their cell-cell interactions., (© 2018 Brown et al.)

Cancer stem cells (CSCs) contribute to multidrug resistance, tumor recurrence and metastasis, making them prime therapeutic targets. Their ability to differentiate and lose stem cell properties makes them challenging to study. Currently, there is no simple assay that can quickly capture and trace the dynamic phenotypic changes on the CSC surface. Here, we report rapid discrimination of breast CSCs from non-CSCs using a nanoparticle-fluorescent-protein based sensor. This nanosensor was employed to discriminate CSCs from non-CSCs, as well as CSCs that had differentiated in vitro in two breast cancer models. Importantly, the sensor platform could also discriminate CSCs from the bulk population of cells in patient-derived xenografts of human breast cancer. Taken together, the results obtained demonstrate the feasibility of using the nanosensor to phenotype CSCs and monitor their fate. Furthermore, this approach provides a novel area for therapeutic interventions against these challenging targets., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Insulin-like growth factor-2 mRNA-binding protein 3 (IMP3) is an oncofetal protein associated with many aggressive cancers and implicated in the function of breast cancer stem cells (CSCs). The mechanisms involved, however, are poorly understood. We observed that IMP3 facilitates the activation of TAZ, a transcriptional co-activator of Hippo signaling that is necessary for the function of breast CSCs. The mechanism by which IMP3 activates TAZ involves both mRNA stability and transcriptional regulation. IMP3 stabilizes the mRNA of an alternative WNT ligand (WNT5B) indirectly by repressing miR145-5p, which targets WNT5B, resulting in TAZ activation by alternative WNT signaling. IMP3 also facilitates the transcription of SLUG, which is necessary for TAZ nuclear localization and activation, by a mechanism that is also mediated by WNT5B. These results demonstrate that TAZ can be regulated by an mRNA-binding protein and that this regulation involves the integration of Hippo and alternative WNT-signaling pathways., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

The role of vascular endothelial growth factor (VEGF) signaling in cancer is not only well known in the context of angiogenesis but also important in the functional regulation of tumor cells. Autocrine VEGF signaling mediated by its co-receptors called neuropilins (NRPs) appears to be essential for sustaining the proliferation and survival of cancer stem cells (CSCs), which are implicated in mediating tumor growth, progression, and drug resistance. Therefore, understanding the mechanisms involved in VEGF-mediated support of CSCs is critical to successfully treating cancer patients. The expression of the Hippo effector TAZ is associated with breast CSCs and confers stem cell-like properties. We found that VEGF-NRP2 signaling contributed to the activation of TAZ in various breast cancer cells, which mediated a positive feedback loop that promoted mammosphere formation. VEGF-NRP2 signaling activated the GTPase Rac1, which inhibited the Hippo kinase LATS, thus leading to TAZ activity. In a complex with the transcription factor TEAD, TAZ then bound and repressed the promoter of the gene encoding the Rac GTPase-activating protein (Rac GAP) β2-chimaerin. By activating GTP hydrolysis, Rac GAPs effectively turn off Rac signaling; hence, the TAZ-mediated repression of β2-chimaerin resulted in sustained Rac1 activity in CSCs. Depletion of β2-chimaerin in non-CSCs increased Rac1 activity, TAZ abundance, and mammosphere formation. Analysis of a breast cancer patient database revealed an inverse correlation between β2-chimaerin and TAZ expression in tumors. Our findings highlight an unexpected role for β2-chimaerin in a feed-forward loop of TAZ activation and the acquisition of CSC properties., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Increases in lipid peroxidation can cause ferroptosis, a form of cell death triggered by inhibition of glutathione peroxidase 4 (GPX4), which catalyzes the reduction of lipid peroxides and is a target of ferroptosis inducers, such as erastin. The α6β4 integrin protects adherent epithelial and carcinoma cells from ferroptosis induced by erastin. In addition, extracellular matrix (ECM) detachment is a physiologic trigger of ferroptosis, which is evaded by α6β4. The mechanism that enables α6β4 to evade ferroptosis involves its ability to protect changes in membrane lipids that are proferroptotic. Specifically, α6β4-mediated activation of Src and STAT3 suppresses expression of ACSL4, an enzyme that enriches membranes with long polyunsaturated fatty acids and is required for ferroptosis. Adherent cells lacking α6β4 require an inducer, such as erastin, to undergo ferroptosis because they sustain GPX4 expression, despite their increase in ACSL4. In contrast, ECM detachment of cells lacking α6β4 is sufficient to trigger ferroptosis because GPX4 is suppressed. This causal link between α6β4 and ferroptosis has implications for cancer biology and therapy., (© 2017 Brown et al.)

Metastasis, drug resistance and recurrence in cancer are regulated by the tumor microenvironment. This review describes recent advances in understanding how cancer cells respond to extracellular environmental cues via integrins, how to build engineered microenvironments to study these interactions in vitro and how nanomaterials can be used to detect and target tumor microenvironments., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Autocrine VEGF signaling is critical for sustaining prostate and other cancer stem cells (CSCs), and it is a potential therapeutic target, but we observed that CSCs isolated from prostate tumors are resistant to anti-VEGF (bevacizumab) and anti-VEGFR (sunitinib) therapy. Intriguingly, resistance is mediated by VEGF/neuropilin signaling, which is not inhibited by bevacizumab and sunitinib, and it involves the induction of P-Rex1, a Rac GEF, and consequent Rac1-mediated ERK activation. This induction of P-Rex1 is dependent on Myc. CSCs isolated from the PTEN(pc-/-) transgenic model of prostate cancer exhibit Rac1-dependent resistance to bevacizumab. Rac1 inhibition or P-Rex1 downregulation increases the sensitivity of prostate tumors to bevacizumab. These data reveal that prostate tumors harbor cells with stem cell properties that are resistant to inhibitors of VEGF/VEGFR signaling. Combining the use of available VEGF/VEGFR-targeted therapies with P-Rex1 or Rac1 inhibition should improve the efficacy of these therapies significantly., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)