RNA-binding protein 14 promotes phase separation to sustain prostate specific antigen expression under androgen deprivation in human prostate cancer

Kentaro Tsuji; Hirotoshi Kawata; Tomoko Kamiakito; Takeo Nakaya; Akira Tanaka

doi:10.1016/j.jsbmb.2023.106407

RNA-binding protein 14 promotes phase separation to sustain prostate specific antigen expression under androgen deprivation in human prostate cancer

J Steroid Biochem Mol Biol. 2023 Dec:235:106407. doi: 10.1016/j.jsbmb.2023.106407. Epub 2023 Oct 6.

Authors

Kentaro Tsuji¹, Hirotoshi Kawata¹, Tomoko Kamiakito¹, Takeo Nakaya¹, Akira Tanaka²

Affiliations

¹ Department of Pathology, Division of Human Pathology, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
² Department of Pathology, Division of Human Pathology, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan. Electronic address: atanaka@jichi.ac.jp.

PMID: 37806532
DOI: 10.1016/j.jsbmb.2023.106407

Abstract

Castration-resistant prostate cancer (CRPC) is a big challenge in managing prostate cancer patients. The androgen receptor (AR) pathway is a major driver even in CRPC under androgen deprivation. The mechanism in maintaining of the AR pathway under androgen deprivation remains elusive. The recent discovery of biomolecular condensate, a membrane-less intracellular construct formed by liquid-liquid phase separation (LLPS), that facilitate molecular assembly, encouraged the re-screening of our previous microarray data list. We selected Rbm14 as a target molecule for further analysis because it works as a coactivator of nuclear receptors as well as it facilitates formation of biomolecular condensates via its intrinsically disordered region. GFP-tagged Rbm14 transfected into HEK293T cells formed droplet-like puncta, which diminished following treatment with 1,6-hexanediol. Droplet-like structures were also observed in immunofluorescence for endogenous RBM14 of PC-3 and DU145 cells. Luciferase assay revealed that Rbm14 enhanced androgen-responsive element (ARE)-mediated reporter activity in all conditions with or without testosterone and AR. Co-immunoprecipitation confirmed the Rbm14-AR interaction. Long non-coding RNAs, including NEAT1, SRA1, and HOTAIR, were also interacted with Rbm14. Small interfering RNAs of NEAT1 reduced ARE-mediated reporter activity, while transfection of SRA1 and HOTAIR enhance the reporter activity. Treatment with 1,6-hexanediol as well as transfection with a dominant-negative splice variant of Rbm14 reduced expression of prostate specific antigen (PSA), a prototype of androgen-regulated gene, in LNCaP, PC-3, and DU145 cells under androgen deprivation. Immunohistochemically, RBM14 expression was substantially upregulated in prostate cancer tissues after androgen deprivation therapy than in untreated tumors. In conclusion, RBM14 is a novel factor involved in maintenance of PSA expression via phase separation under androgen deprivation in prostate cancer.

Keywords: Androgen deprivation therapy; Biomolecular condensate; PSA; Prostate cancer; RBM14.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Androgens* / metabolism
Cell Line, Tumor
HEK293 Cells
Humans
Male
Prostate-Specific Antigen* / metabolism
Prostatic Neoplasms* / drug therapy
Prostatic Neoplasms* / genetics
Prostatic Neoplasms* / metabolism
Prostatic Neoplasms, Castration-Resistant* / pathology
RNA-Binding Proteins* / genetics
Receptors, Androgen / metabolism

Substances

Androgens
hexamethylene glycol
Prostate-Specific Antigen
Receptors, Androgen
RNA-Binding Proteins