The Mechanism Of Regulation Of P300on Fatty Acid Synthesis And Its Role In Prostate Cancer

Prostate cancer (PCa) shows a strong requirement for de novo fatty acid synthesis.Cancer cells de novo synthesize a large amount of Fatty acids (FAs), which is usuallysuppressed in normal tissues, and take the benefits for survival and progression. Thus, fattyacid metabolism has become a potential focus for treatment of PCa. Fatty acid synthase(FASN) as a key enzyme in the fatty acid synthesis, is often overexpressed in human PCas,and correlates with worse prognosis and poor survival. However, the regulatory mechanism ofFASN in PCa is not fully understood. P300is a transcription co-activator and with its intrinsicacetyltransferase activity, it functions as a cancer promoter in the prostate. It is unclearwhether p300is involved in the regulation of FASN and the Fatty acid synthesis in PCa.Objective: Study the relationship between FASN and p300, and the mechanism of theregulation of p300on the expression of FASN and the fatty acid synthesis in PCa; then furtherstudy the biological function of p300-FASN pathway in PCa. Methods: We analyzed thep300CHIP-seq data and employed CHIP assay to verify the binding of p300to FASN and toexamine the changing of the level of histone acetylation in the same region. We knockeddown p300with p300-specific siRNA or treated the cells with different concentrations ofp300inhibitors to silence the expression of p300in different PCa cell lines, to see theexpression of FASN on mRNA and protein levels with RT-PCR or western blot analysis. Weused oil red o staining to test the lipid accumulation in PCa cells or fresh frozen tissues. MTSassay was used to find the changing of cell viability under different situations. And theexpression level of proteins of p300and FASN in human tissues was studied by IHC staining.Produced the p300gene knockout mice though cross breeding, and monitored the changes ofFASN expression and lipid accumulation in prostate tissue. In order to detect the biological function of p300-FASN pathway, we established and cultured the stable cell line whichexpressed low level of p300or FASN or both p300and FASN. The xenograft model was gotwith the subcutaneous injection, monitored the growth curve, and the tumor grafts wereharvested for preparation of the frozen and paraffin sections. Results:(1) P300binds to theFASN promoter in PCa cells and upregulates the level of histone acetylation.(2) P300regulates FASN mRNA and protein expression in PCa cells.(3) Expression of p300positivelycorrelates with FASN protein levels in human PCa specimens.(4) P300affects the lipidaccumulation in PCa both in vitro and in vivo.(5) P300regulates the cell growth of PCathough FASN. Conclusion: Our study identifies p300, as an important molecular determinant,is positively correlated with FASN. It regulates FASN expression and lipid accumulation inPCa, further regulates the cell growth of PCa though FASN. It plays a decisive significance inthe development of PCa treatment targeting lipid metabolism.