CUL4B, NEDD4, and UGT1As involve in the TGF-β signalling in hepatocellular carcinoma

Introduction and Aim. TGF-β signalling is involved in pathogenesis and progress of hepatocellular carcinoma (HCC). This bioinformatics study consequently aims to determine the underlying molecular mechanism of TGF- β activation in HCC cells.

Dataset GSE10393 was downloaded from Gene Expression Omnibus, including 2 Huh-7 (HCC cell line) samples treated by TGF- β (100 pmol/L, 48 h) and 2 untreated samples. Differentially expressed genes (DEGs) were screened using Limma package (false discovery rate < 0.05 and |log2 fold change| > 1.5), and then enrichment analyses of function, pathway, and disease were performed. In addition, protein-protein interaction (PPI) network was constructed based on the PPI data from multiple databases including INACT, MINT, BioGRID, UniProt, BIND, BindingDB, and SPIKE databases. Transcription factor (TF)-DEG pairs (Bonferroni adjusted p-value < 0.01) from ChEA database and DEG-DEG pairs were used to construct TF-DEG regulatory network. Furthermore, TF-pathway-DEG complex network was constructed by integrating DEG-DEG pairs, TF-DEG pairs, and DEG-pathway pairs.

Totally, 209 DEGs and 30 TFs were identified. The DEGs were significantly enriched in adhesion-related functions. PPI network indicted hub genes such as CUL4B and NEDD4. According to the TF-DEG regulatory network, the two hub genes were targeted by SMAD2, SMAD3, and HNF4A. Besides, the 11 pathways in TF-pathway-DEG network were mainly enriched by UGT1A family and CYP3A7, which were predicted to be regulated by SMAD2, SMAD3, SOX2, TP63, and HNF4A.

TGF- β might influence biological processes of HCC cells via SMAD2/SMAD3-NEDD4, HNF4A-CUL4B/NEDD4, SOX2/TP63/HNF4A-CYP3A7, and SMAD2/SMAD3/SOX2/TP63/HNF4A-UGT1As regulatory pathways.