27-hydroxycholesterol and DNA damage repair: implication in prostate cancer

Gloria Cecilia Galvan; Nadine A Friedrich; Sanjay Das; James P Daniels; Sara Pollan; Shweta Dambal; Ryusuke Suzuki; Sergio E Sanders; Sungyong You; Hisashi Tanaka; Yeon-Joo Lee; Wei Yuan; Johann S de Bono; Irina Vasilevskaya; Karen E Knudsen; Michael R Freeman; Stephen J Freedland

doi:10.3389/fonc.2023.1251297

27-hydroxycholesterol and DNA damage repair: implication in prostate cancer

Front Oncol. 2023 Dec 21:13:1251297. doi: 10.3389/fonc.2023.1251297. eCollection 2023.

Authors

Gloria Cecilia Galvan^#¹, Nadine A Friedrich^#¹, Sanjay Das^{1

2

3}, James P Daniels¹, Sara Pollan¹, Shweta Dambal⁴, Ryusuke Suzuki⁵, Sergio E Sanders¹, Sungyong You¹, Hisashi Tanaka^{5

6}, Yeon-Joo Lee¹, Wei Yuan⁷, Johann S de Bono^{7

8}, Irina Vasilevskaya⁹, Karen E Knudsen⁹, Michael R Freeman¹, Stephen J Freedland^{1

3}

Affiliations

¹ Department of Urology, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States.
² Department of Urology, University of California, Los Angeles, Los Angeles, CA, United States.
³ Urology Section, Department of Surgery, Veterans Affairs Health Care System, Durham, NC, United States.
⁴ Department of Pathology, Duke University School of Medicine, Durham, NC, United States.
⁵ Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States.
⁶ Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States.
⁷ Cancer Biomarkers Team, Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.
⁸ Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust, London, United Kingdom.
⁹ Department of Cancer Biology at Thomas Jefferson University, Philadelphia, PA, United States.

^# Contributed equally.

Abstract

Introduction: We previously reported that cholesterol homeostasis in prostate cancer (PC) is regulated by 27-hydroxycholesterol (27HC) and that CYP27A1, the enzyme that converts cholesterol to 27HC, is frequently lost in PCs. We observed that restoring the CYP27A1/27HC axis inhibited PC growth. In this study, we investigated the mechanism of 27HC-mediated anti-PC effects.

Methods: We employed in vitro models and human transcriptomics data to investigate 27HC mechanism of action in PC. LNCaP (AR+) and DU145 (AR-) cells were treated with 27HC or vehicle. Transcriptome profiling was performed using the Affymetrix GeneChip™ microarray system. Differential expression was determined, and gene set enrichment analysis was done using the GSEA software with hallmark gene sets from MSigDB. Key changes were validated at mRNA and protein levels. Human PC transcriptomes from six datasets were analyzed to determine the correlation between CYP27A1 and DNA repair gene expression signatures. DNA damage was assessed via comet assays.

Results: Transcriptome analysis revealed 27HC treatment downregulated Hallmark pathways related to DNA damage repair, decreased expression of FEN1 and RAD51, and induced "BRCAness" by downregulating genes involved in homologous recombination regulation in LNCaP cells. Consistently, we found a correlation between higher CYP27A1 expression (i.e., higher intracellular 27HC) and decreased expression of DNA repair gene signatures in castration-sensitive PC (CSPC) in human PC datasets. However, such correlation was less clear in metastatic castration-resistant PC (mCRPC). 27HC increased expression of DNA damage repair markers in PC cells, notably in AR+ cells, but no consistent effects in AR- cells and decreased expression in non-neoplastic prostate epithelial cells. While testing the clinical implications of this, we noted that 27HC treatment increased DNA damage in LNCaP cells via comet assays. Effects were reversible by adding back cholesterol, but not androgens. Finally, in combination with olaparib, a PARP inhibitor, we showed additive DNA damage effects.

Discussion: These results suggest 27HC induces "BRCAness", a functional state thought to increase sensitivity to PARP inhibitors, and leads to increased DNA damage, especially in CSPC. Given the emerging appreciation that defective DNA damage repair can drive PC growth, future studies are needed to test whether 27HC creates a synthetic lethality to PARP inhibitors and DNA damaging agents in CSPC.

Keywords: 27-hydroxycholesterol (27HC); CYP27A1; DU145 (prostate) cancer cell line; LNCaP (prostate cancer cell); hydroxycholesterol; prostate cancer.

Abstract

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