Regulation of glucose metabolism by p62/SQSTM1 through HIF1α

The signaling adaptor sequestosome 1 (SQSTM1)/p62 is frequently overexpressed in tumors and plays an important role in the regulation of tumorigenesis. Although great progress has been made, biological roles of p62 and relevant molecular mechanisms responsible for its pro-tumor activity remain largely unknown. Here, we show that p62 knockdown reduces cell growth and the expression of glycolytic genes in a manner that depends on HIF1 alpha activity in renal cancer cells. Knockdown of p62 decreases HIF1 alpha levels and transcriptional activity by regulating mTORC1 activity and NF-kappa B nuclear translocation. Furthermore, p62 interacts directly with the von Hippel-Lindau (VHL) E3 ligase complex to modulate the stability of HIF1 alpha. Mechanistically, p62 binds to the VHL complex and competes with HIF1 alpha. Expression of p62 inhibits the interaction of DCNL1 (also known as DCUN1D1) with CUL2 and attenuates the neddylation of CUL2, and thus downregulates the VHL E3 ligase complex activity. Functionally, HIF1 alpha expression is required for p62-induced glucose uptake, lactate production and soft agar colony growth. Taken together, our findings demonstrate that p62 is a crucial positive regulator of HIF1 alpha, which is a facilitating factor in p62-enhanced tumorigenesis.