Cancer-testis antigen lactate dehydrogenase C4 in hepatocellular carcinoma: a promising biomarker for early diagnosis, efficacy evaluation and prognosis prediction.

Expressions and clinical implications of cancer-testis antigen (CTA) lactate dehydrogenase (LDH)-C4 in hepatocellular carcinoma (HCC) have not been fully elucidated. Herein, expressions of LDHC mRNA in the serum and serum-derived exosomes of early-stage HCC patients were determined using qRT-PCR, and the expression of LDH-C4 protein in HCC tissues was detected using high-throughput tissue microarray analysis. It was found that positive rates of LDHC mRNA expressions in the serum and serum exosomes of HCC patients were 68% and 60%, respectively. The AUCs of serum and exosomal LDHC in differentiating HCC patients from healthy controls were 0.8382 and 0.9451, respectively. The serum and exosomal LDHC levels in HCC patients in the treatment group were higher than the levels in the preliminary diagnosis group, but lower than those in the recurrence group. Survival analysis showed that the expression of LDH-C4 was negatively correlated with the prognosis of HCC. The Cox regression analysis showed that an LDH-C4 level was an independent risk factor for the prognosis of HCC patients. Therefore, serum and exosomal LDHC can be used as a biomarker for early diagnosis, efficacy evaluation and recurrence prediction of HCC. Moreover, LDH-C4 can be used as an important reference indicator for monitoring the prognosis of HCC.