BUB1 Predicts Poor Prognosis and Immune Status in Liver Hepatocellular Carcinoma

Abstract

Background: Accurate assessment of the tumour immune microenvironment helps develop individualised immunotherapy regimens and screen dominant populations suitable for immunotherapy. Therefore, potential molecular markers were investigated to make an overall assessment of the immune microenvironment status of liver hepatocellular carcinoma (LIHC). Methods: Differentially expressed genes (DEGs) in LIHC were extracted from the International Cancer Genome Consortium and The Cancer Genome Atlas databases. Gene set enrichment analysis was employed to assess the function of DEGs. Hub genes were identified using the STRING tool. The prognostic value of the hub genes was evaluated through Kaplan–Meier analysis and Cox regression. The correlation between genes and immunity was analysed using the TIMER tool. Further, tissue samples from 42 LIHC patients were collected for immunohistochemistry. HuH7 and SKP1 cells were analysed via western blotting, Cell Counting kit-8 assay, and Transwell assay. Results: A total of 121 DEGs were identified, and DEGs were enriched in the epithelial-mesenchymal transition, hypoxia, myogenesis, and p53 pathways. A total of 20 hub genes were selected and a strong correlation was identified between these hub genes and prognosis. The expression of budding uninhibited by benzimidazoles 1 (BUB1), which is known to play a role in cancer progression, was found to be upregulated in LIHC (compared to normal tissues). Furthermore, BUB1 expression was strongly related to immune cells and immune checkpoint molecule expression. Immunohistochemistry indicated that BUB1 expression was higher in LIHC tissues than in normal liver tissues. Western blotting showed that BUB1 expression was the highest in HuH7 and SKP1 cells. BUB1 knockdown resulted in reduced proliferation and vertical migration ability of LIHC cells, and reduced the expression of phospho-SMAD family member 2 and phospho-SMAD family member 3 proteins. Immunohistochemistry showed that BUB1 expression was accompanied by immune cell infiltration into LIHC tissues.Conclusions: These results suggest that BUB1 may serve as a potential prognostic biomarker for LIHC and as an indicator of its immune status.