The Genomic and Proteomic Profiles of NTRK Genes and Trk Receptors in Liver Hepatocellular Carcinoma

BACKGROUND: The neurotrophic tyrosine kinase (NTRK) gene family includes NTRK1, NTRK2, and NTRK3, which encode tropomyosin receptor kinases TrkA, TrkB, and TrkC, respectively. This study aimed to initially assess the genomic and proteomic profiles of NTRK genes and Trk receptors in liver hepatocellular carcinoma (LIHC). METHODS: The ONCOMINE, UALCAN, GEPIA, cBioPortal, FusionGDB, SurvivalMeth, and the Human Protein Atlas databases were searched for NTRK gene expression and protein data in LIHC. Immunohistochemistry was used to detect pan-Trk expression across a commercial microarray containing 96 hepatocellular carcinoma (HCC) and 94 para-cancerous tissue spots. A modified histological score (H-score) with a maximum score of 300 was used to quantify immunohistochemical staining for pan-Trk. Student’s t- and chi-square tests were the main statistical analyses used. RESULTS: The transcriptional levels of NTRK genes in LIHC were not significantly different from healthy controls. Using UALCAN and GEPIA, only high expression of NTRK2 was significantly associated with longer disease-free survival (P = 0.004). The alteration frequencies were low (7% in NTRK1, 1.7% in NTRK2, and 2% in NTRK3). The methylation levels of NTRK genes were all significantly different as analyzed by UALCAN; the high-risk group displayed an unfavorable prognosis compared with the low-risk group for NTRK1 (P = 0.033) and NTRK3 (P = 0.005). The median H-score of pan-Trk in HCC and para-cancerous tissues was not statistically different (186.31 ± 23.86 and 192.38 ± 21.06, P = 0.065). No differences were observed in clinicopathological features of HCC with the median H-score for pan-Trk expression (p > 0.05). The survival rate of patients with pan-Trk expression was also not significantly different. CONCLUSION: The alteration frequency was low in NTRK genes, including gene fusion and methylation levels. Therefore, pan-Trk expression in HCC tissue has limited value in clinicopathological features and prognosis.