CTC-537E7.3 as a Liver-Specific Biomarker for Hepatocellular Carcinoma: Diagnostic and Prognostic Implications

Hepatocellular carcinoma (HCC) critically lacks reliable biomarkers for early detection. By mining the TCGA_LIHC and two GEO cohorts, we identified the liver-specific long non-coding RNA CTC-537E7.3 as the most consistently down-regulated transcript in tumors. This finding was validated in 97 paired tissues, with CTC-537E7.3 expression lost in 95% of cases (*** p < 0.0001). It demonstrated excellent diagnostic performance in discriminating tumor from non-tumor tissue (AUC = 0.95), which was maintained in early-stage (I/II) disease. Low CTC-537E7.3 expression correlated with shorter overall and disease-free survival and was inversely associated with serum α-fetoprotein (AFP) levels, highlighting its complementary clinical value. Mechanistic investigation revealed a potential competing endogenous RNA (ceRNA) axis. The microRNA miR-190b-5p was highly expressed in tumors and predicted to bind CTC-537E7.3, while its target, PLGLB1, was significantly suppressed. Survival analysis confirmed that concurrent high expression of CTC-537E7.3 and PLGLB1 conferred superior outcomes. These findings establish CTC-537E7.3 as a liver-specific, ceRNA-mediated tumor suppressor with robust diagnostic and prognostic potential. It represents a promising adjunct to existing HCC surveillance strategies, such as ultrasound and AFP measurement, for high-risk populations.