Augmenter of Liver Regeneration Enhances Hepatocellular Carcinoma Cell Growth Through COX-2-associated Signaling

The expression of augmenter of liver regeneration (ALR), a potent growth factor, is significantly up-regulated in hepatocellular carcinoma (HCC). This study aims to investigate the potential functions and mechanisms of ALR in HCC.

ALR expression in Huh7 cells was silenced using an RNA interference (RNAi) lentiviral vector, and differentially expressed genes (DEGs) were identified through DNA microarray analysis. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were performed to explore the functional roles and mechanisms of ALR in HCC. A protein-protein interaction (PPI) network was constructed based on the identified DEGs, and hub genes with high connectivity were identified. The relationship between these hub genes, ALR, and HCC cell proliferation was further analyzed.

A total of 299 DEGs were identified, including 171 up-regulated and 128 down-regulated genes. GO, KEGG, and GSEA analyses revealed that ALR is closely associated with receptor protein signaling pathways, cell proliferation, metabolism, mitochondrial homeostasis, and cell migration. Furthermore, ALR expression was associated with the enrichment of oncogenic pathways, including KRAS, Hedgehog, and IL-6/JAK/STAT3 signaling. Analysis of the PPI network and hub gene analysis identified Cyclooxygenase-2 [COX-2, also known as prostaglandin-endoperoxide synthase 2 (PTGS2)] as a key hub gene, which was selected for further investigation. Real-time quantitative PCR and Western blot results indicated that COX-2 is a downstream target of ALR. Additionally, ALR was shown to promote Huh7 cell proliferation by regulating COX-2.

These findings connect ALR to the dysregulation of multiple oncogenic signaling pathways in HCC. Additionally, ALR may promote the proliferation of HCC by modulating the downstream pro-inflammatory factor COX-2, suggesting that ALR could serve as a potential therapeutic target for HCC.