Diterpene glycosides from Fructus Rubi ameliorates benign prostatic hyperplasia in rats through the androgen and TGF-β/Smad signaling pathway

Abstract

Ethnopharmacological relevance: Fructus Rubi (FR), a food material with medicinal value, is used in traditional Chinese medicine (TCM) for treatment of various kidney-related problems, such as impotence, spermatorrhea, and frequent urination. It is also frequently used to produce diverse functional foods in China.

Aim of study: The purpose of this research was to assess the therapeutic effects of FR diterpene glycosides on RWPE-1 epithelial cell (RWPE-1), a human normal prostatic epithelial cell, and benign prostate hyperplasia (BPH) rats, both of which had been exposed to dihydrotestosterone (DHT) and testosterone propionate (TP), respectively, and to investigate the mechanism of action.

Methods: Target proteins that could stably bind to certain diterpene glycosides were screened through drug affinity responsive target stability combined with mass spectrometry (DARTS/MS). DHT-induced RWPE-1 cells were used to detect drug activity. TP was subcutaneously injected to induce BPH in rats. The extract of diterpene glycosides from FR (FDS) was orally administered for 28 days. The DHT levels in the serum and prostate tissue of the rats were measured through enzyme-linked immunosorbent assay (ELISA), and to analyze cell proliferation and epithelial-mesenchymal transition (EMT), the protein expression of prostate-specific antigen (PSA), androgen receptor (AR), steroid 5α-reductase type 2 (SRD5A2), proliferating cell nuclear antigen (PCNA), S100 calcium-binding protein A2 (S100A2), transforming growth factor-β1 (TGF-β1), E-cadherin, vimentin, and Smad4 was determined through western blotting (WB), immunohistochemistry (IHC), or immunofluorescence (IF).

Results: FDS reduced the proliferation of DHT-induced RWPE-1 cells. It also significantly inhibited rat prostate enlargement; decreased DHT levels in the serum and prostate tissue; inhibited the protein expression of AR, PSA, PCNA, S100A2, TGF-β1, E-cadherin, and Smad4; and increased the protein expression of E-cadherin.

Conclusion: The present study is the first to report that diterpene glycosides isolated from FR inhibited BPH at the cellular level, regulated the proliferation of prostate cells through the androgen signaling pathway, and prevented EMT in the prostate through the S100A2-mediated TGF-β/Smad signaling pathway. These results indicate that FDS is a promising multitarget therapy for BPH.

Keywords: Androgen signaling pathway; Benign prostate hyperplasia; Diterpene glycosides; Rructus Rubi; TGF-β/Smad signaling pathway.