Inhibitory Effects of LOXL2 Knockdown On Cellular Functions of Liver Cancer Stem Cells

Abstract:

Background and aim: 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 knock down in CD133⁺HepG2 and CD133⁺Hep3B cells. Protein and mRNA levels were quantified by Western blotting, Immunofluorescence and real-time 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 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 (LC3) 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.