Rhamnazin Inhibits Malignant Progression of Prostate Cancer Cells via DPP4/JAK/STAT Signaling Pathway

Abstract

Background: Rhamnazin is a natural dimethoxyflavonoid compound and Rhamnazin has been reported to have antitumor activity. This work is performed to study the function of Rhamnazin in prostate cancer (PCa) cells and its mechanism. Methods: Rhamnazin (20 µM) was used to treat 22Rv1 and C4-2B cells, and the cells treated with dimethyl sulfoxide (DMSO) were set as the control group. To investigate the role of dipeptidyl peptidase 4 (DPP4) in mediating the biological effects of Rhamnazin, DPP4 overexpression plasmids were transfected into the PCa cell lines. Cell counting kit-8 method was employed to detect the proliferation; apoptosis and cell cycle were detected by flow cytometry. the target genes of Rhamnazin were predicted in Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis of target genes of Rhamnazin was performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID database). Human Protein Atlas database was utilized to identify genes associated with poor PCa prognosis. GEPIA database was used to validate the expression and prognosis of DPP4 in PCa. The LinkedOmics database was used to analyze the signaling pathway related to DPP4 in PCa. Quantitative polymerase chain reaction was performed to detect DPP4 mRNA levels. Western blot assays were performed to detect the expression levels of DPP4, phosphorylated (p-) Janus kinase 1 (JAK1) and p-signal transducer and activator of transcription 3 (STAT3). Results: Functional assays confirmed that Rhamnazin inhibited the proliferation of PCa cells (p < 0.05), and promoted apoptosis (p < 0.05) and blocked the cell cycle progression (p < 0.05). In addition, Rhamnazin significantly inhibited the expression of DPP4 (p < 0.05), and up-regulating DPP4 reversed the effects of Rhamnazin (p < 0.05). It was further found that DPP4 was associated with JAK/STAT signaling and Rhamnazin inhibited the expression of p-JAK1 (p < 0.05) and p-STAT3 (p < 0.05) through DPP4. Conclusion: Rhamnazin has the potential to kill PCa cells via DPP4/JAK/STAT axis.