Se-Allylselenocysteine induces autophagy by modulating the AMPK/mTOR signaling pathway and epigenetic regulation of PCDH17 in human colorectal adenocarcinoma cells.

Abstract

Selenium (Se)-conjugated compounds have been established as anti-carcinogenic compounds. The use of chemicals as cancer chemotherapeutic agents to induce programmed cell death (PCD) involves genetic and epigenetic modifications. In this study, we investigated the underlying molecular mechanisms of Se-allylselenocysteine (ASC)-induced PCD and protocadherin 17 (PCDH17) expression in HT-29 cells. Cell viability analysis indicated that the ability of ASC to induce cancer cell death was greater than that of Se-methylselenocysteine in colorectal cancer cells. ASC also decreased global DNA methylation levels via downregulation of DNA methyltransferase 1 expression. The autophagic cell death is the cause in ASC-induced cytotoxicity that was inhibited by pretreatment with autophagy inhibitor. At the molecular level, ASC induced PCDH17 expression through decreased PCDH17 promoter hypermethylation. PCDH17 is also an important role in ASC-induced autophagy by HT-29 transfected with PCDH17 shRNA or expression plasmid. Our western blot analysis showed that ASC significantly induced autophagy via the AMPK/mTOR pathway that was also regulated PCDH17 expression. Additionally, we used the HT-29 tumor xenograft models to confirm the ability of ASC inhibited tumor growth. These results reveal that ASC is an effective inducer of autophagy through regulating the AMPK/mTOR and PCDH17 expression via epigenetic modification.