Sesamin induces autophagy in colon cancer cells by reducing tyrosine phosphorylation of EphA1 and EphB2

Receptor tyrosine kinase EphB2 and autophagic machinery are known as tumor suppressors; however, the connection remains to be elucidated. Here, we show the link between EphB2 and autophagy. Sesamin, a major lignan in sesame oil, induced autophagy in the human colon cancer cell lines HT29 and LS180, as shown by electron microscopy, as well as Western blotting and immunofluorescence imaging using an anti-LC3 antibody. Receptor tyrosine kinase array analysis revealed that sesamin treatment increased the levels of unphosphorylated -EphAl and -EphB2 in HT29 cells. Silencing of EphAl and EphB2 blocked sesamin-induced autophagy as well as sesamin-induced loss of cell viability. These results show that EphAl and EphB2 play a critical role in this process. The present study reveals a novel function for EphA1 and EphB2 in the induction of autophagy, suggesting a tumor suppressor role for these proteins in colorectal cancer.