Induction of apoptosis by Galectin-9 in liver metastatic cancer cells: In vitro study

Liver metastasis from gastrointestinal cancer defines a patient's prognosis. Despite medical developments, pancreatic cancer with liver metastasis confers a very poor prognosis. Galectin-9 (Gal‑9) is a tandem-repeat-type galectin that has recently been demonstrated to exert antitumor effects on various types of cancer cells by inducing apoptosis. However, the apoptotic pathway of Gal‑9 in solid tumors is unclear. The aim of the present study was to evaluate the effects of Gal‑9 on human liver metastasis from pancreatic cancer. Gal‑9 suppressed cell proliferation in metastatic liver cancer cell lines derived from pancreatic cancer (KMP2, KMP7, and KMP8) and increased the levels of caspase-cleaved keratin 18 and fluorescein isothiocyanate (FITC)-conjugated Annexin V. Furthermore, expression of apoptosis-related molecules such as caspase-7, cleaved caspase-3, cleaved PARP, cytochrome c, Smac/Diablo and HtrA2/Omi was enhanced. However, Gal‑9 did not affect expression of various cell cycle-related proteins. The microRNA (miRNA) expression profile was markedly altered by Gal‑9, and various miRNAs might contribute to tumor growth suppression. Our data reveal that Gal‑9 suppresses the growth of liver metastasis, possibly by inducing apoptosis through a mechanism involving mitochondria and changes in miRNA expression. Thus, Gal‑9 might serve as a therapeutic agent for the treatment of liver metastasis from pancreatic cancer.