Abstract 1441: Elevated HOXC gene expression in castration-resistant prostate cancer

Abstract Background: Androgen deprivation therapy or Androgen receptor-targeted therapies are used to treat metastatic Prostate Cancer (PCa). However, nearly all cases eventually progress to castration-resistant prostate cancer (CRPC). The molecular pathways associated with CRPC development and progression remain incompletely defined. This study aims to identify new drivers and delineate the underlying mechanisms in CRPC. Methods: Three isogenic castration-sensitive and castration-resistant prostate cancer cell lines were analyzed by miRNA and RNA sequencing. Gene transcripts associated with castration resistance were further characterized by RT-PCR and bioinformatic analyses. Gene knockout and knockdown in CRPC cell lines were carried out using the CRISPR/Cas9 technology and RNA interference (RNAi) technique. In addition, the HOXC gene cluster was overexpressed in castration-sensitive prostate cancer cell lines using predesigned synthetic sgRNAs and the CRISPR activation (CRISPRa) system. Cell growth and survival were assessed using the IncuCyte®-SX5 live cell analysis system. Results: Differential gene expression analysis identified significantly elevated miR-196a expression in CRPC cell lines. Visualization of RNA sequencing read density peaks in IGV revealed pri-miR-196a-2 as the source of elevated miR-196a expression in CRPC cells. MIR196A2 is located within the HOXC gene cluster. Transcriptional analyses demonstrate that miR-196a-2 is an intronic miRNA co-transcribed within HOXC gene transcripts. Multiple HOXC gene transcripts were more active in CRPC cell lines. Bioinformatic analyses demonstrated significantly higher HOXC gene expression in a subset of metastatic and CRPC tumors. The elevated expression was further validated in clinical samples by RT-qPCR. HOXC8 gene over-expression using plasmid gene expression vectors and CRISPRa enhanced prostate cancer cell proliferation, and HOXC8 gene knockout attenuated CRPC cell proliferation. Conclusions: HOXC gene cluster is activated in in a subset of metastatic and castration-resistant prostate cancer with HOXC8 playing a crucial role in regulating cell proliferation. Citation Format: Isaacson B. Adelani, Akira Kurozumi, Tobiloba Owojuyigbe, Sanchit Sanyal, Su Mi Choi, Srinivasan Yegnasubramanian, Shawn E. Lupold. Elevated HOXC gene expression in castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1441.