William C. Reinhold

Advanced and treatment-refractory prostate cancer remains a major clinical challenge and requires new therapeutic strategies. The calcium-activated monovalent cation channel TRPM4 regulates cell volume and has been implicated in cancer progression. TRPM4 was recently identified as a determinant of sensitivity to Acetalax (oxyphenisatin acetate) in triple-negative breast cancer and prostate cancer; however, whether TRPM4 also determines sensitivity to ErSO in prostate cancer cells had not been tested. Here, we investigate the relationship between ErSO, which induces TRPM4-associated cytotoxicity and ERα-positive breast cancer cell death, and TRPM4 expression in prostate cancer models. The Cancer Genome Atlas (TCGA) shows a broad range of TRPM4 expression in prostate cancers, and an integrated analysis of drug-response datasets reveals a positive association between TRPM4 expression and ErSO sensitivity in prostate cancer. Functional studies demonstrate that ErSO induces rapid cellular swelling, nuclear enlargement, and membrane blebbing selectively in TRPM4-high prostate cancer cells, consistent with early oncosis-like morphological responses, whereas TRPM4-low cells are less sensitive. Time-course analyses show a downregulation of TRPM4 following ErSO treatment. Chronic ErSO exposure results in the acquisition of resistance accompanied by loss of TRPM4 expression, and ErSO-resistant cells fail to undergo ErSO-induced morphological changes. Flow cytometry analyses further show that ErSO induces loss of membrane integrity and oncosis-like cell death-associated features in TRPM4-expressing cells. These findings establish TRPM4 as a functional determinant of ErSO responsiveness in prostate cancer cells and support its potential utility as a biomarker of ErSO sensitivity.

Advanced and treatment-refractory prostate cancer, including castration-resistant disease, requires new therapeutic strategies. Transient receptor potential melastatin 4 (TRPM4), a calcium-activated monovalent cation channel, regulates cell volume and promotes cancer progression. Acetalax induces oncosis-like death in TRPM4-positive triple-negative breast cancers, suggesting a TRPM4-dependent vulnerability. In this study, we investigated whether TRPM4 expression defines Acetalax sensitivity in prostate cancer. We compared Acetalax sensitivity in TRPM4-high and -low prostate cancer cell lines, including androgen-dependent (LNCaP), castration-resistant (22Rv1), and androgen-independent (PC3 and DU145) models. We evaluated TRPM4 dynamics and oncosis-associated phenotypes using Western blotting and immunofluorescence. Resistant clones were developed through continuous drug exposure. TRPM4 expression in patient samples was analyzed using prostate cancer tissue microarray and The Cancer Genome Atlas. Transcriptional changes following TRPM4 loss were examined by RNA sequencing (RNA-seq). Antitumor activity and tolerability were evaluated in TRPM4-positive patient-derived xenograft (PDX) models. TRPM4-high cells (PC3, LNCaP, and 22Rv1) underwent oncosis-like swelling and TRPM4 degradation upon Acetalax exposure, whereas TRPM4-low cell and resistant clones (DU145 and chronic exposure cells) remained insensitive and lacked TRPM4 expression. RNA-seq revealed transcriptomic remodeling associated with TRPM4 loss. TRPM4 was significantly increased in tumors compared with normal tissues and was unchanged across stages or Gleason scores. In TRPM4-positive PDX models, Acetalax (300 mg/kg) significantly suppressed tumor growth without body weight loss, indicating antitumor efficacy without overt toxicity. TRPM4 is a mechanistic driver and predictive biomarker of Acetalax response in prostate cancer, supporting TRPM4-dependent targeting and providing a rationale for the clinical development of Acetalax for TRPM4-expressing and treatment-refractory prostate cancer.

This file contains supplementary figures and tables, including analyses of TRPM4 expression in TCGA and SU2C cohorts, additional characterization of Acetalax-induced morphological changes in prostate cancer cell lines, comparative analyses of prostate cancer cell lines with patient tumors, transcriptomic and pathway enrichment analyses, a conceptual model of TRPM4 regulation, and supporting correlation and gene expression data tables.

Advanced and treatment-refractory prostate cancer, including castration-resistant disease, requires new therapeutic strategies. Transient receptor potential melastatin 4 (TRPM4), a calcium-activated monovalent cation channel, regulates cell volume and promotes cancer progression. Acetalax induces oncosis-like death in TRPM4-positive triple-negative breast cancers, suggesting a TRPM4-dependent vulnerability. In this study, we investigated whether TRPM4 expression defines Acetalax sensitivity in prostate cancer. We compared Acetalax sensitivity in TRPM4-high and -low prostate cancer cell lines, including androgen-dependent (LNCaP), castration-resistant (22Rv1), and androgen-independent (PC3 and DU145) models. We evaluated TRPM4 dynamics and oncosis-associated phenotypes using Western blotting and immunofluorescence. Resistant clones were developed through continuous drug exposure. TRPM4 expression in patient samples was analyzed using prostate cancer tissue microarray and The Cancer Genome Atlas. Transcriptional changes following TRPM4 loss were examined by RNA sequencing (RNA-seq). Antitumor activity and tolerability were evaluated in TRPM4-positive patient-derived xenograft (PDX) models. TRPM4-high cells (PC3, LNCaP, and 22Rv1) underwent oncosis-like swelling and TRPM4 degradation upon Acetalax exposure, whereas TRPM4-low cell and resistant clones (DU145 and chronic exposure cells) remained insensitive and lacked TRPM4 expression. RNA-seq revealed transcriptomic remodeling associated with TRPM4 loss. TRPM4 was significantly increased in tumors compared with normal tissues and was unchanged across stages or Gleason scores. In TRPM4-positive PDX models, Acetalax (300 mg/kg) significantly suppressed tumor growth without body weight loss, indicating antitumor efficacy without overt toxicity. TRPM4 is a mechanistic driver and predictive biomarker of Acetalax response in prostate cancer, supporting TRPM4-dependent targeting and providing a rationale for the clinical development of Acetalax for TRPM4-expressing and treatment-refractory prostate cancer.

Chromosome instability (CIN) remains among the most important problems in modern cancer research. In this study, we conducted a genome-wide RNAi screen to identify genes that contribute to CIN. To achieve this, we used a human artificial chromosome in a novel sensitized screen to measure CIN. We screened 18,658 genes for their roles in maintaining chromosomal stability and identified 834 candidates as potential CIN genes. A secondary RNAi screen identified 44 genes with the most pronounced CIN phenotypes. In guilt-by-association analysis using a published set of 8,498 proteins across a panel of 949 cancer cell lines, this cohort of 44 genes displayed a striking correlation with mitotic regulators. Furthermore, altered expression of these proteins was associated with a poor prognosis across multiple cancer types. Specifically, downregulation of AMY2B, ALAD, PDGFRA, PPIE, VEZ1, and TTC19 is associated with poor survival in two or more of the following: small cell lung cancer, lung adenocarcinoma, adrenocortical carcinoma, ovarian cancer, and breast cancer. The genes identified in this screen hold potential as prognostic markers for patient survival across several cancer types and could potentially serve as targets for the development of new therapeutic approaches aimed at mitigating CIN.

CellMiner Cross-Database (CellMinerCDB) (https://discover.nci.nih.gov/cellminercdb/) is an established interactive application providing direct access and enabling exploration of cancer cell line pharmacogenomics without extensive programming experience. Data are compiled from many sources, including the National Cancer Institute(NCI), Broad Institute Dependency Map (DepMap), Sanger/MGH Genomics of DrugSensitivity in Cancer (GDSC), MD Anderson Cell Lines Project (MCLP), andNational Center for Advancing Translational Sciences (NCATS). In the version 2.2 update, our collection has expanded to pharmacogenomics data for 1916 cancer cell lines and over 25 000 drugs. Drug screening data include many additional compounds for potential drug repurposing from the Broad PRISM, NCATS, and NCI. The user interface facilitates uncovering specific samples of interest and identifying drug and cell lines across databases. We also expanded the annotations for cross-referencing other databases and downloading our data for further cancer biology and drug discovery studies. Herein, we provide use cases for CellMinerCDB, including (i) data reproducibility given overlaps of cell lines, genes, and drugs across databases; (ii) candidate biomarker discovery; and (iii) cross-dataset analyses.