Androgen Receptor-mediated Gene Regulatory Networks And Protein Phosphatase 2c¦Ê Further Functional Study

This article is composed of two parts:The first part is about the androgen receptor mediated miRNA signaling network in prostate cancer. miRNAs are short, endogenous RNAs in cells, promoting translational repression and/or destabilization of target mRNAs, to'fine tune'protein level in numerous biological processes. The role of miRNAs in prostate cancer signaling remains largely unknown. Based on microarray and bioinformatics analyses, our cooperation researchers have predicted about some androgen receptor regulated miRNA, which is assessed by the value Response score (RS), and some miRNA regulated mRNA, which is assessed by the value of modulation score (MS). Based on this, we identified miR-19a, miR-27a, miR-133b and miR-421 as primary androgen responsive targets. Their androgen response elements on genome were located. Meanwhile, we validated that miR-19a, miR-27a, miR-133b and miR-421 may regulate cell proliferation by repressing 24 target mRNAs directly in LNCaP cells. Specially, miR-19a introduced a feedback loop by down-regulating PSAP, an activator of androgen receptor on the levels of both expression and activity. To further understand the function of androgen receptor as a transcription factor during the pathology and transformation of prostate cancer, we choose another well characterized miRNA, miR-125B2 as a model to study the androgen induced transcription initiation. We found that miR-125B2 is an early and slightly up-regulated target of androgen receptor. The real enhancer element located at-3kb upstream of transcription start site. Upon androgen treatment, there will be dynamic gene looping between miR-125B2 enhancer and transcription start site. These results may give us a new sight to the relationship between androgen receptor triggered oxidation and transcription complex formation.Meanwhile, to investigate the biological function of AR correlated gene network in the level of cancer susceptibility. We have chosen a series of AR related genes according to current reports. After library retrieving in pubmed database we finally focus on the cytokine TNFA and its single nucleotide polymorphisms on-308 and-857 sites. Through papers collecting and data extraction, we carried a meta-analysis on the relationship between TNFA polymorphisms and cancer risk. A significant correlation between TNFA-308 variants and gastric cancer risk was observed in world wide population and Caucasian population. This finding extended our understanding on the biological function of AR related gene network. The second part is to study the interaction between the human novel Ser/Thr specific phophatase PP2Cκand the heat shock factor HSF1, which is a transcription factor in the pathway of heat shock response element. We find that the over-expression of PP2Cκwould significantly induce the expression of heat shock proteins HSP27 and HSP70, while HSP90 was not affected. We further explored the biological phenotype after endogenous PP2Cκwas knock-out by siRNA expression constructs. The results indicated that the knock-out of PP2Cκwould reduce the cell survival rate after heat shock stress, whereas PP2Cκdid not have a effect on cell proliferation after proteasome inhibitor MG132 treatment. By protein interaction assay, we explored the mechanism under the control of heat shock response by PP2Cκ. We find that PP2Cκdid not have an effect on the phosphorylation of protein kinase p-38, JNK, GSK3β,ERK1 which are upstream of HSFl activity regulation. We have also validated that PP2Cκdirectly interacted with HSFl by immunoprecipitation and pull-down assay, which indicate HSFl may be one of the PP2Cκsubstrates.