Crosstalk of NF-κB/P65 and LncRNA HOTAIR-Mediated Repression of MUC1 Expression Contribute to Synergistic Inhibition of Castration-Resistant Prostate Cancer by Polyphyllin 1–Enzalutamide Combination Treatment

Abstract

Background/Aims: Polyphyllin I (PPI), one of the steroidal saponins in Paris polyphylla, reportedly exhibits antitumor effects. However, the detailed mechanism underlying PPI, particularly in enhancing the effect of the androgen receptor inhibitor enzalutamide in controlling castration-resistant prostate cancer (CRPC) has not been explored. Methods: Cell viability and cell cycle distribution were measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. Long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) expression was measured by quantitative real time-PCR (qRT-PCR). Western blot analysis was performed to determine the protein expression levels of MUC1, p65, and p50. Silencing of HOTAIR was evaluated using the siRNA procedure. The promoter activity of the MUC1 gene was determined using Secrete-Pair Dual Luminescence Assay Kit. Exogenous expression of HOTAIR, p65, and MUC1 was conducted by transient transfection assay. A xenograft tumor model in nude mice was used to further evaluate the effect of the combination of PPI and enzalutamide in vivo. Results: We showed that PPI significantly inhibited growth and induced cell cycle arrest in CRPC cells. PPI also decreased p65 and MUC1 protein expression and reduced HOTAIR expression. Exogenously expressed p65 resisted the PPI-inhibited expression of HOTAIR, whereas silenced HOTAIR reduced MUC1 protein but exerted no effect on the expression of p65 and p50 proteins. Conversely, exogenously expressed HOTAIR resisted the PPI-inhibited MUC1 protein expression, and excessive expression of MUC1 antagonized the PPI-inhibited cell growth. Notably, PPI combined with enzalutamide exerted a synergistic effect. Consistent with this finding, PPI inhibited tumor growth, HOTAIR expression, as well as p65 and MUC1 protein expressions in vivo. Conclusions: Our results indicate that PPI inhibits the growth of CRPC cells by inhibiting p65 protein and concomitantly reducing HOTAIR expression, thereby suppressing MUC1 gene expression. The novel regulatory interaction of p65 and HOTAIR converge in the inhibition of MUC1 expression and overall PPI response. The combination of PPI and enzalutamide exhibits synergy. This study reveals a novel mechanism underlying the synergistic inhibitory effect of PPI and enzalutamide on the growth of CRPC cells.

Dysregulated expression but redundant function of the long non-coding RNA HOTAIR in diabetic kidney disease

“…In considering how high glucose may upregulate HOTAIR, we were cognisant of work reporting a role for the p65 subunit of NF-κB in regulating the expression of human HOTAIR [33,34]. We performed in silico analysis of the mouse Hotair promoter and identified three potential binding sites for NF-κB (ESM Fig.…”

β-Elemene suppresses tumor growth of diffuse large B-cell lymphoma through regulating lncRNA HULC-mediated apoptotic pathway

“…HULC silencing suppressed angiogenesis by regulating ESM-1 via the PI3K/Akt/mTOR signaling pathway in human gliomas [34]. Recently, a growing number of novel treatment strategies, such as compounds derived from natural products, have been developed for cancer therapy by targeting lncRNAs [35][36][37]. Previous study reported that β-elemene inhibited the growth of esophageal cancer by modulating lncRNA-mediated inhibition of hTERT [38].…”

A double safety lock tumor-specific device for suicide gene therapy in breast cancer

“…The 5TR1 aptamer binds to the aberrantly hypoglycosilated MUC1 located on the breast cancer-cell surface. The second lock corresponds to the hMUC1 promoter, which ensures expression of the cytotoxic ricin with the preprotrypsin leader only in MUC1 overexpressing cells [53,54].…”