The Transcriptional Regulation and Ubiquitination Dependent Regulation of Hnrnpk Oncogenic Function in Prostate Tumorigenesis

Abstract

Background Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is a nucleic acid-binding protein that regulates diverse biological events. Pathologically, hnRNPK proteins are frequently overexpressed and clinically correlated with poor prognosis to various types of human cancers, therefore pursued as attractive therapeutic targets for selective patients. However, both the transcriptional regulation and degradation of hnRNPK in prostate cancer are remain poorly understood. Methods qRT-PCR was used to detect the expression of hnRNPK and miRNA; Immunoblots and immunohistochemical assays were used to determine the levels of hnRNPK and other proteins. Flow cytometry was used to investigate cell cycle stage. MTS and clonogenic assays were used to investigate cell proliferation. Immunoprecipitation was used to analyze the interaction between SPOP and hnRNPK. A prostate carcinoma xenograft mouse model was used to detect the in vivo effects of hnRNPK and miRNA. Results In the present study, we observed that hnRNPK emerged as an important player in carcinogenesis process of PrCa. miR-206 and miR-613 suppressed hnRNPK expression by targeting the 3’-UTR of hnRNPK in PrCa cell lines, where hnRNP K is overexpressed. In biological effects studies, proliferation and colony formation of PrCa cells in vitro, and tumor growth in vivo, were also dramatically suppressed upon reintroduction of miR-206/ miR-613. We have further provided clear evidence that Cullin 3 SPOP as a novel upstream E3 ubiquitin ligase complex that governs hnRNPK proteins stability and oncogenic functions through promoting the degradation of HnRNP K in a poly-ubiquitinaion dependent proteolysis in the prostate cancer setting. Moreover, prostate cancer-associated SPOP mutants fail to interact with and promote the destruction of hnRNPK proteins. Conclusion Our finding reveal new post-transcriptional and post-translational modifications mechanism of hnRNPK regulation via miR-206/ miR-613 and SPOP, respectively. More important, given the critical oncogenic role of hnRNPK and high frequency of SPOP mutation in prostate cancer, our results provide a molecular rationale for the clinical investigation of novel strategies to combat prostate cancer based on SPOP genetic status.

Early-life origin of prostate cancer through deregulation of miR-206 networks in maternally malnourished offspring rats

“…, hepatocellular carcinoma[76], and prostate cancer[77]. Regarding miR-206, although this miRNA has been described as a tumor suppressor miRNA, that modulates cell proliferation, migration, and aggressiveness in various types of cancer, including prostate cancer[33, 78,79], recently it has been demonstrated that miR-206 can act as an important "DOHaD miR"[80]. In this study,Yamazaki et al (2020) showed that maternal exposure to fructose resulted in deregulation of the miR-206-Lxra network in the liver offspring rat and associated this result with a reduction in serum HDL-C level and metabolic syndrome in these animals[80].…”