PHF5A coordinates p300 for epigenetic regulation of lipogenesis to promote hepatocellular carcinoma progression

PHD-finger protein 5A (PHF5A) is a component of U2snRNP, which plays a critical role in mRNA splicing for recognizing the branch site. However, whether it also plays other functions independent of RNA splicing remains elusive. Here, we find that expression levels of PHF5A are significantly upregulated in hepatocellular carcinoma (HCC). Down-regulation of PHF5A restrains liver cancer cell proliferation in vitro and in vivo. RNA-sequencing analysis reveals that fatty-acid biosynthetic enzymes are major downstream targets of PHF5A in HCC. Through metabolomics analysis, we find that inhibition of PHF5A reduces free fatty acid and phospholipid synthesis, further suppressing plasma membrane function. Mechanistically, PHF5A acts as a transcription co-factor of the p300 acetyltransferase for the H3K27 acetylation (Ac) and promotes H3K27Ac-dependent lipogenic genes expression. Our findings demonstrated a surprising splicing-independent role of PHF5A in transcriptional regulation of lipid metabolism for HCC progression and provided a new strategy for HCC therapy by blocking the interaction of PHF5A and p300. Overall design: 4 samples. HepG2 liver cancer cells were transfected with siControl or siPHF5A, Cells' RNA was harvested using Trizol reagent. 3 ug of total RNA is used for the construction of sequencing libraries by Hiseq 4000 PE150.