Low expression of LACTB promotes tumor progression and predicts poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major life threatening malignancy worldwide. HCC has an unfavorable prognosis, mainly due to late diagnosis, early metastasis, and post-surgical recurrence. Recent studies have demonstrated that beta-lactamases (LACTB) plays a pivotal role in the pathogenesis and progression of several malignant tumors, but its expression and functional role in HCC has not been reported. In this study, we explored the expression of LACTB using The Cancer Genome Atlas datasets and two independent tissues microarrays. We then analyzed the correlation between LACTB expression and clinical outcomes in HCC. We demonstrated that LACTB mRNA and protein levels were both down-regulated in HCC, and decreased LACTB expression was associated with TNM stage, histologic grade, and overall survival of patients. Additionally, through Gene Set Enrichment Analysis, we found that the genes negatively related to the survival of HCC patients were enriched in the low LACTB expression group. Furthermore, we confirmed that overexpression of LACTB inhibited HCC cell proliferation, invasion, and migration in vitro, as well as decreased tumor growth in vivo. Online prediction results suggested that the LACTB gene was markedly correlated with genes involved in the lipid metabolism pathway. In conclusion, these findings suggest that down-regulated LACTB could function as a novel biomarker for diagnosis and prognosis prediction, and LACTB could serve as a promising target in HCC therapy.