Novel Branched-Chain Amino Acid-Catabolism Related Gene Signature for Overall Survival Prediction of Pancreatic Carcinoma

Branched-chain amino acid (BCAA) metabolism plays an important role in the pancreatic carcinogenesis, but its mechanism remains unclear. Hence, this study was performed to investigate the value of genes related to BCAA catabolism in pancreatic cancer. The online Gene Expression Omnibus database, The Cancer Genome Atlas, and International Cancer Genome Consortium data sets were searched for bioinformatic analysis. Univariate Cox and Lasso regression were applied to construct a predictive model. Human cancer cell lines and tissue microarray (TMA) were applied for validation. From the 48 BCAA-catabolism enzyme (BCE) genes, a 5-gene risk-score (ABAT, ACAT1, BCAT1, BCAT2, and DBT) was constructed. Patients in high-risk and low-risk groups stratified by risk-score indicated significantly different overall survival. Given the clinical parameters, the risk-score was an independent predictor for prognosis. Among the five genes, BCAT2 and ABAT were hub genes with favorable prognosis value, which was validated by TMA immunohistochemistry (IHC) staining. Immune infiltration analysis indicated high-risk group enriched macrophage, and decreased positive cell density of stromal CD68(+) macrophage in TMA was observed for BCAT2 with low-expression versus high-expression cases. In conclusion, a risk-score involving five BCE genes was proposed to predict the poor prognosis of pancreatic cancer. On the basis of the immune infiltration analysis, the underlying mechanism might be BCAT2 associated stromal macrophage infiltration.