PSPH induces cell autophagy and promotes cell proliferation and invasion in the hepatocellular carcinoma cell line Huh7 via the AMPK/mTOR/ULK1 signaling pathway.

Zhang, Jianli; Wang, Erhao; Zhang, Lei; Zhou, Bo

Phosphoserine phosphatase (PSPH), a key enzyme of the L-serine synthesis pathway, has been involved in cancer progression and survival. However, limited evidence revealed the PSPH influence on hepatocellular carcinoma (HCC). Herein, we observed that PSPH expression was upregulated in both HCC tissues and cell lines, which was determined by Western blotting. TCGA database showed that the PSPH protein levels were significantly upregulated and affected patient survival rates in HCC. Then gain- and loss-of-function manipulations were performed by transfection with a pcDNA-PSPH expression vector or a specific siRNA against PSPH in Huh7 cells. Huh7 cell proliferation, stemness, invasion and apoptosis were assessed by using CCK-8 test, colony formation assay, Transwell assay and Flow cytometry analysis, respectively, and levels of autophagy-related proteins were detected by using Western blotting. The results showed that PSPH could induce Huh7 cell autophagy, promote cell proliferation and invasion, and inhibit apoptosis. Knockdown of PSPH could inhibit Huh7 cell proliferation, invasion, and autophagy. Furthermore, PSPH activated Liver kinase B1 (LKB1) and TGF beta-activated kinase 1 (TAK1), affected the AMPK/mTOR/ULK1 signaling pathway, but could not activate calcium/calmodulin-dependent protein kinase kinase (CaMKK) in Huh7 cells. Inhibition of either LKB1, TAK1, or AMPK could eliminate the effect of PSPH overexpression on Huh7 cell behaviors. However, inhibition of CaMKK could not influence the effect of PSPH overexpression on Huh7 cell behaviors. In conclusion, PSPH could induce autophagy, promote proliferation and invasion, and inhibit apoptosis in HCC cell via the AMPK/mTOR/ULK1 signaling pathway. This article is protected by copyright. All rights reserved.