Inhibitory effects of LOXL2 knockdown on cellular functions of liver cancer stem cells

BACKGROUND: Lysyl oxidase-like 2 (LOXL2) plays a role in tumor microenvironment formation and metastasis of hepatocellular carcinoma (HCC), which has a high mortality burden. Liver cancer stem cells (LCSCs) are related with the major malignant phenotypes of HCC. The function of LOXL2 in regulation of LCSCs remains unknown. METHODS: CD133(+)HepG2 and CD133(+)Hep3B cells were sorted by fluorescence-activated cell sorting (FACS) from two human hepatoblastoma cell lines. Spheroid formation, apoptosis, cell cycle, as well as transwell assays were performed upon LOXL2 knockdown in CD133(+)HepG2 and CD133(+)Hep3B cells. Protein and mRNA levels were quantified by Western blotting, immunofluorescence and reverse transcription-PCR (RT-PCR). RESULTS: Knockdown of LOXL2 decreased spheroid formation, migration and invasion (P<0.05), also induced apoptosis (P<0.05) and cell cycle arrest (P<0.05) in CD133(+)HepG2 and CD133(+)Hep3B cells. Knockdown of LOXL2 effectively inhibited expression of the anti-apoptosis proteins baculoviral inhibitor of apoptosis protein (IAP) repeat-containing 3 (BIRC3) and murine double minute 2 (MDM2) (P<0.01), as well as autophagy marker microtubule-associated protein 1 light chain 3 B (LC3B) and autophagy gene ATG5 in CD133(+)HepG2 and CD133(+)Hep3B cells (P<0.01). CONCLUSIONS: The results revealed that LOXL2 inhibition could reduce the proliferation and expansion of LCSCs, making LOXL2 inhibitors an attractive and novel therapeutic strategy of HCC.