Determinants of widespread metastases and of metastatic tropism in patients with prostate cancer: A genomic analysis of primary and metastatic tumors.

INTRODUCTION: Emerging evidence suggests that metastasis is better described as a spectrum of disease rather than a binary state. A greater understanding of the genomic features that determine extent and location of metastatic spread may inform risk stratification and monitoring. Here, we identify genomic alterations from primary prostate carcinomas that are predictive of wide-spread metastatic potential. METHODS: Genomic and clinical data from 1,312 patients with primary prostate carcinoma were extracted from the MSK-MET cohort through cBioPortal. Metastatic site counts and overall survival (OS) data were publicly available and used as the primary outcomes. Primary tumor samples were profiled using the MSK-IMPACT targeted sequencing platform. We focused on 58 genes frequently altered in prostate cancer. Cox proportional hazard analyses defined hazard ratios (HRs) and 95% confidence intervals (CIs) for overall mortality in patients with different metastatic outcomes. RESULTS: Out of the 1,312 patients in our cohort, 939 (71%) developed metastases, of whom 113 (8.6%) had metastases to 5 or more distinct anatomical sites (defining wide-spread metastases, WSM). Bone was the most common site of metastasis (36%), and 80% of patients with liver metastases had 4 or more additional sites of metastasis. Among patients with metastasis, increasing number of metastatic sites was associated with increased risk of death (HR: 1.8, 95%CI: 1.63-1.99, P < 0.001). Alterations in the following genes were enriched in tumors from patients with WSM vs. others: TP53 (40% vs. 20%, P < 0.0001), FOXA1-amplification (8% vs. 3%, P = 0.02), AR-amplification (4.4% vs. 1%, P = 0.01), RB1-deletion (5.3% vs. 0.7%, P = 0.001), and BRCA2-deletion (4.4% vs. 0.7%, P = 0.01). Univariable survival analysis showed all these alterations were predictive of OS (P < 0.05). On multivariable analysis, only TP53 mutations, and FOXA1 and AR amplifications were independent prognostic factors. FOXA1 (n = 37) and AR (n = 13) amplifications were mutually exclusive and patients with these experienced very poor OS (HR: 3.57, 95%CI:2.26-5.6, P < 0.001]. CONCLUSIONS: We identified genomic alterations (TP53 mutations, FOXA1/AR amplification, RB1/BRCA2 deletion) from primary prostate carcinomas that are predictive of wide-spread metastases and poor outcome.

Dynamic Mutational Landscape of Cerebrospinal Fluid Circulating Tumor DNA and Predictors of Survival after Proton Craniospinal Irradiation for Leptomeningeal Metastases.

PURPOSE: Proton craniospinal irradiation (pCSI) is a promising treatment for patients with solid tumor leptomeningeal metastasis (LM). We hypothesize that genetic characteristics before and changes resulting after pCSI will reflect clinical response to pCSI. We analyzed the cerebrospinal fluid (CSF) circulating tumor DNA (ctDNA) from patients receiving pCSI for LM and explored genetic variations associated with response. EXPERIMENTAL DESIGN: We subjected CSF from 14 patients with LM before and after pCSI to cell-free DNA sequencing using a targeted-sequencing panel. In parallel, plasma ctDNA and primary tumors were subjected to targeted sequencing. Variant allele frequency (VAF) and cancer cell fraction (CCF) were calculated; clonality of observed mutations was determined. Kaplan-Meier analysis was used to associate genomic changes with survival. RESULTS: The median overall survival (OS) for the cohort was 9 months [interquartile range (IQR), 5-21 months]. We showed clonal evolution between tumor and ctDNA of the CSF and plasma with unique mutations identified by compartment. Higher CSF ctDNA mean VAF before pCSI (VAFpre) had worse OS (6 months for VAFpre ≥ 0.32 vs. 9 months for VAFpre < 0.32; P = 0.05). Similarly, increased VAF after pCSI portended worse survival (6 vs. 18 months; P = 0.008). Higher mean CCF of subclonal mutations appearing after pCSI was associated with worse OS (8 vs. 17 months; P = 0.05). CONCLUSIONS: In patients with solid tumor LM undergoing pCSI, we found unique genomic profiles associated with pCSI through CSF ctDNA analyses. Patients with reduced genomic diversity within the leptomeningeal compartment demonstrated improved OS after pCSI suggesting that CSF ctDNA analysis may have use in predicting pCSI response.

Towards 'end-to-end' analysis and understanding of biological timecourse data.

Petabytes of increasingly complex and multidimensional live cell and tissue imaging data are generated every year. These videos hold large promise for understanding biology at a deep and fundamental level, as they capture single-cell and multicellular events occurring over time and space. However, the current modalities for analysis and mining of these data are scattered and user-specific, preventing more unified analyses from being performed over different datasets and obscuring possible scientific insights. Here, we propose a unified pipeline for storage, segmentation, analysis, and statistical parametrization of live cell imaging datasets.

Radiation Oncology Alternative Payment Model and Large Urban Academic Centers: Future Implications for Patients and Providers.

The radiation oncology alternative payment model (RO-APM) was developed by the Center for Medicare and Medicaid Innovation, a part of the Centers for Medicare & Medicaid Services, as a vehicle to optimize value for patients undergoing radiation therapy. By shifting reimbursement away from fee-for-service and toward a prospective bundled payment system, the RO-APM is intended to bend the cost curve in radiation oncology while preserving or even enhancing outcomes. As with prior large-scale policy initiatives, the nature and magnitude of the RO-APM's impact on care delivery will vary substantially depending on a host of local factors, including practice setting. Urban academic centers play a key role in radiation oncology by spearheading innovation, managing the most complicated cases, training the next generation of radiation oncologists, and often caring for vulnerable patient populations. Thus, to protect patients' access to this high-quality cancer care, it will be crucial to characterize the RO-APM's projected impact on large urban academic institutions before its implementation, including possible unintended adverse consequences. Here, we provide an overview of this seismic change in radiation oncology reimbursement and discuss its unique potential implications for large urban academic institutions as a means to facilitate necessary preparations and inform future revisions to the model.

Impact of the Coronavirus Disease of 2019 Pandemic on Radiation Oncology Clinical Decision Making in a High-Prevalence Environment.

PURPOSE: This study aimed to define how the coronavirus disease of 2019 (COVID-19) pandemic affected the role, timing, and delivery of radiation therapy (RT) in a high-prevalence region at the height of the initial U.S. outbreak. METHODS AND MATERIALS: We performed a retrospective review of all patients seen at 3 radiation oncology departments within the Rutgers Robert Wood Johnson Barnabas Health system in New Jersey during the initial COVID-19 surge. The primary endpoints were to define and quantify COVID-related, radiation-specific care changes, and identify predictive factors of experiencing COVID-related care changes. RESULTS: A total of 545 patients with cancer were seen during the study period, 99 of whom (18.1%) experienced ≥1 COVID-related care change. RT delays were the most common, accounting for 51.5% of all care changes. Physician-directed delays accounted for 41.2% of RT delays, and patient fears, COVID testing, and access barriers were responsible for 27.5%, 17.6%, and 13.7%, respectively. Patient age (P = .040), intent of treatment (P = .047), and cancer type (P < .001) were significantly associated with experiencing a COVID-related care change, as we found that older, curative intent and patients with rectal cancer were more likely to experience care changes. On multivariate analysis, patient age remained significant when controlling for treatment intent and cancer type. CONCLUSIONS: Our study provides a perspective on how care was adapted to protect patients with cancer during a pandemic while maximizing disease control. The positive correlation between age and likelihood of care changes may reflect extra precaution taken with older patients given their vulnerability to severe COVID illness. The lower observed likelihood of COVID-related care changes among patients undergoing palliative RT may reflect either the more urgent needs addressed by palliative RT or simply be logistical, because palliative radiation is often delivered in short courses with less exposure risk. Assessing adaptations others have implemented and monitoring how they affect patient outcomes will be crucial.

Optogenetic control of protein binding using light-switchable nanobodies.

A growing number of optogenetic tools have been developed to reversibly control binding between two engineered protein domains. In contrast, relatively few tools confer light-switchable binding to a generic target protein of interest. Such a capability would offer substantial advantages, enabling photoswitchable binding to endogenous target proteins in cells or light-based protein purification in vitro. Here, we report the development of opto-nanobodies (OptoNBs), a versatile class of chimeric photoswitchable proteins whose binding to proteins of interest can be enhanced or inhibited upon blue light illumination. We find that OptoNBs are suitable for a range of applications including reversibly binding to endogenous intracellular targets, modulating signaling pathway activity, and controlling binding to purified protein targets in vitro. This work represents a step towards programmable photoswitchable regulation of a wide variety of target proteins.

Temporal Arteritis and Vision Loss in Microscopic Polyangiitis: A Case Report and Literature Review.

Microscopic polyangiitis (MPA) is an idiopathic autoimmune disease characterized by systemic vasculitis. While the lungs and kidneys are the major organs affected by MPA, it is known to involve multiple organ systems throughout the body. Temporal artery involvement is a very rare finding in MPA. This report presents a patient whose initial presentation was consistent with giant cell arteritis but was ultimately found to have microscopic polyangiitis. It highlights the importance of considering alternative types of vasculitis in the differential diagnosis for patients with atypical temporal artery biopsy findings.

A Live-Cell Screen for Altered Erk Dynamics Reveals Principles of Proliferative Control.

Complex, time-varying responses have been observed widely in cell signaling, but how specific dynamics are generated or regulated is largely unknown. One major obstacle has been that high-throughput screens are typically incompatible with the live-cell assays used to monitor dynamics. Here, we address this challenge by screening a library of 429 kinase inhibitors and monitoring extracellular-regulated kinase (Erk) activity over 5 h in more than 80,000 single primary mouse keratinocytes. Our screen reveals both known and uncharacterized modulators of Erk dynamics, including inhibitors of non-epidermal growth factor receptor (EGFR) receptor tyrosine kinases (RTKs) that increase Erk pulse frequency and overall activity. Using drug treatment and direct optogenetic control, we demonstrate that drug-induced changes to Erk dynamics alter the conditions under which cells proliferate. Our work opens the door to high-throughput screens using live-cell biosensors and reveals that cell proliferation integrates information from Erk dynamics as well as additional permissive cues.

A bright future: optogenetics to dissect the spatiotemporal control of cell behavior.

Cells sense, process, and respond to extracellular information using signaling networks: collections of proteins that act as precise biochemical sensors. These protein networks are characterized by both complex temporal organization, such as pulses of signaling activity, and by complex spatial organization, where proteins assemble structures at particular locations and times within the cell. Yet despite their ubiquity, studying these spatial and temporal properties has remained challenging because they emerge from the entire protein network rather than a single node, and cannot be easily tuned by drugs or mutations. These challenges are being met by a new generation of optogenetic tools capable of directly controlling the activity of individual signaling nodes over time and the assembly of protein complexes in space. Here, we outline how these recent innovations are being used in conjunction with engineering-influenced experimental design to address longstanding questions in signaling biology.

P-Rex1 is dispensable for Erk activation and mitogenesis in breast cancer.

Phosphatidylinositol-3,4,5-Trisphosphate Dependent Rac Exchange Factor 1 (P-Rex1) is a key mediator of growth factor-induced activation of Rac1, a small GTP-binding protein widely implicated in actin cytoskeleton reorganization. This Guanine nucleotide Exchange Factor (GEF) is overexpressed in human luminal breast cancer, and its expression associates with disease progression, metastatic dissemination and poor outcome. Despite the established contribution of P-Rex1 to Rac activation and cell locomotion, whether this Rac-GEF has any relevant role in mitogenesis has been a subject of controversy. To tackle the discrepancies among various reports, we carried out an exhaustive analysis of the potential involvement of P-Rex1 on the activation of the mitogenic Erk pathway. Using a range of luminal breast cancer cellular models, we unequivocally showed that silencing P-Rex1 (transiently, stably, using multiple siRNA sequences) had no effect on the phospho-Erk response upon stimulation with growth factors (EGF, heregulin, IGF-I) or a GPCR ligand (SDF-1). The lack of involvement of P-Rex1 in Erk activation was confirmed at the single cell level using a fluorescent biosensor of Erk kinase activity. Depletion of P-Rex1 from breast cancer cells failed to affect cell cycle progression, cyclin D1 induction, Akt activation and apoptotic responses. In addition, mammary-specific P-Rex1 transgenic mice (MMTV-P-Rex1) did not show any obvious hyperproliferative phenotype. Therefore, despite its crucial role in Rac1 activation and cell motility, P-Rex1 is dispensable for mitogenic or survival responses in breast cancer cells.

Four Key Steps Control Glycolytic Flux in Mammalian Cells.

Altered glycolysis is a hallmark of diseases including diabetes and cancer. Despite intensive study of the contributions of individual glycolytic enzymes, systems-level analyses of flux control through glycolysis remain limited. Here, we overexpress in two mammalian cell lines the individual enzymes catalyzing each of the 12 steps linking extracellular glucose to excreted lactate, and find substantial flux control at four steps: glucose import, hexokinase, phosphofructokinase, and lactate export (and not at any steps of lower glycolysis). The four flux-controlling steps are specifically upregulated by the Ras oncogene: optogenetic Ras activation rapidly induces the transcription of isozymes catalyzing these four steps and enhances glycolysis. At least one isozyme catalyzing each of these four steps is consistently elevated in human tumors. Thus, in the studied contexts, flux control in glycolysis is concentrated in four key enzymatic steps. Upregulation of these steps in tumors likely underlies the Warburg effect.

Optogenetic Control of Ras/Erk Signaling Using the Phy-PIF System.

The Ras/Erk signaling pathway plays a central role in diverse cellular processes ranging from development to immune cell activation to neural plasticity to cancer. In recent years, this pathway has been widely studied using live-cell fluorescent biosensors, revealing complex Erk dynamics that arise in many cellular contexts. Yet despite these high-resolution tools for measurement, the field has lacked analogous tools for control over Ras/Erk signaling in live cells. Here, we provide detailed methods for one such tool based on the optical control of Ras activity, which we call "Opto-SOS." Expression of the Opto-SOS constructs can be coupled with a live-cell reporter of Erk activity to reveal highly quantitative input-to-output maps of the pathway. Detailed herein are protocols for expressing the Opto-SOS system in cultured cells, purifying the small molecule cofactor necessary for optical stimulation, imaging Erk responses using live-cell microscopy, and processing the imaging data to quantify Ras/Erk signaling dynamics.

Identification of novel radiosensitizers in a high-throughput, cell-based screen for DSB repair inhibitors.

Most cancer therapies involve a component of treatment that inflicts DNA damage in tumor cells, such as double-strand breaks (DSBs), which are considered the most serious threat to genomic integrity. Complex systems have evolved to repair these lesions, and successful DSB repair is essential for tumor cell survival after exposure to ionizing radiation (IR) and other DNA-damaging agents. As such, inhibition of DNA repair is a potentially efficacious strategy for chemo- and radiosensitization. Homologous recombination (HR) and nonhomologous end-joining (NHEJ) represent the two major pathways by which DSBs are repaired in mammalian cells. Here, we report the design and execution of a high-throughput, cell-based small molecule screen for novel DSB repair inhibitors. We miniaturized our recently developed dual NHEJ and HR reporter system into a 384-well plate-based format and interrogated a diverse library of 20,000 compounds for molecules that selectively modulate NHEJ and HR repair in tumor cells. We identified a collection of novel hits that potently inhibit DSB repair, and we have validated their functional activity in a comprehensive panel of orthogonal secondary assays. A selection of these inhibitors was found to radiosensitize cancer cell lines in vitro, which suggests that they may be useful as novel chemo- and radio sensitizers. Surprisingly, we identified several FDA-approved drugs, including the calcium channel blocker mibefradil dihydrochloride, that demonstrated activity as DSB repair inhibitors and radiosensitizers. These findings suggest the possibility for repurposing them as tumor cell radiosensitizers in the future. Accordingly, we recently initiated a phase I clinical trial testing mibefradil as a glioma radiosensitizer.

Androgen receptor signaling regulates DNA repair in prostate cancers.

UNLABELLED: We demonstrate that the androgen receptor (AR) regulates a transcriptional program of DNA repair genes that promotes prostate cancer radioresistance, providing a potential mechanism by which androgen deprivation therapy synergizes with ionizing radiation. Using a model of castration-resistant prostate cancer, we show that second-generation antiandrogen therapy results in downregulation of DNA repair genes. Next, we demonstrate that primary prostate cancers display a significant spectrum of AR transcriptional output, which correlates with expression of a set of DNA repair genes. Using RNA-seq and ChIP-seq, we define which of these DNA repair genes are both induced by androgen and represent direct AR targets. We establish that prostate cancer cells treated with ionizing radiation plus androgen demonstrate enhanced DNA repair and decreased DNA damage and furthermore that antiandrogen treatment causes increased DNA damage and decreased clonogenic survival. Finally, we demonstrate that antiandrogen treatment results in decreased classical nonhomologous end-joining. SIGNIFICANCE: We demonstrate that the AR regulates a network of DNA repair genes, providing a potential mechanism by which androgen deprivation synergizes with radiotherapy for prostate cancer.

Development of an assay to measure mutagenic non-homologous end-joining repair activity in mammalian cells.

Double-strand break (DSB) repair pathways are critical for the maintenance of genomic integrity and the prevention of tumorigenesis in mammalian cells. Here, we present the development and validation of a novel assay to measure mutagenic non-homologous end-joining (NHEJ) repair in living cells, which is inversely related to canonical NHEJ and is based on the sequence-altering repair of a single site-specific DSB at an intrachromosomal locus. We have combined this mutagenic NHEJ assay with an established homologous recombination (HR) assay such that both pathways can be monitored simultaneously. In addition, we report the development of a ligand-responsive I-SceI protein, in which the timing and kinetics of DSB induction can be precisely controlled by regulating protein stability and cellular localization in cells. Using this system, we report that mutagenic NHEJ repair is suppressed in growth-arrested and serum-deprived cells, suggesting that end-joining activity in proliferating cells is more likely to be mutagenic. Collectively, the novel DSB repair assay and inducible I-SceI will be useful tools to further elucidate the complexities of NHEJ and HR repair.