DNA Methylation of PITX2 and PANCR Is Prognostic for Overall Survival in Patients with Resected Adenocarcinomas of the Biliary Tract

Abstract

Biliary tract cancers (BTC) are rare but highly aggressive malignant epithelial tumors. In order to improve the outcome in this lethal disease, novel biomarkers for diagnosis, prognosis, and therapy response prediction are urgently needed. DNA promoter methylation of PITX2 variants (PITX2ab, PITX2c) and intragenic methylation of the PITX2 adjacent non-coding RNA (PANCR) were investigated by methylations-specific qPCR assays in formalin-fixed paraffin-embedded tissue from 80 patients after resection for BTC. Results were correlated with clinicopathologic data and outcome. PITX2 variants and PANCR showed significant hypermethylation in tumor vs. normal adjacent tissue (p < 0.001 and p = 0.015), respectively. In survival analysis, dichotomized DNA methylation of variant PITX2c and PANCR were significantly associated with overall survival (OS). Patients with high tumor methylation levels of PITX2c had a shorter OS compared to patients with low methylation (12 vs. 40 months OS; HR 2.48 [1.38–4.48], p = 0.002). In contrast, PANCR hypermethylation was associated with prolonged survival (25 vs. 19 months OS; HR 0.54 [0.30–0.94], p = 0.015) and qualified as an independent prognostic factor on multivariate analysis. The biomarkers investigated in this study may help to identify BTC subpopulations at risk for worse survival. Further studies are needed to evaluate if PITX2 might be a clinically useful biomarker for an optimized and individualized treatment.

Gene body methylation in cancer: molecular mechanisms and clinical applications

“…However, a retrospective study found that AREG gene body methylation levels are not as predictive as AREG mRNA levels and cannot yet be used as a clinically reliable biomarker, but they still provide an important clue for further research [ 124 ]. In addition, in patients with cholangiocarcinoma, patients with higher methylation levels of PITX2-adjacent noncoding RNAs had relatively longer survival and could be an independent prognostic factor [ 125 ] (Table 3 ).…”

“…In addition, in patients with cholangiocarcinoma, patients with higher methylation levels of PITX2-adjacent noncoding RNAs had relatively longer survival and could be an independent prognostic factor [ 125 ] (Table 3 ).…”

Clinical performance validation of PITX2 DNA methylation as prognostic biomarker in patients with head and neck squamous cell carcinoma

“…In recent years, PITX2 has attracted interest as a potential biomarker in malignant tumors, i.e. non-small cell lung cancer (NSCLC), biliary tract cancers, prostate cancer, and breast cancer [ 16 , 19 – 27 ]. In NSCLC, PITX2 hypermethylation was identified as significant predictor of progression-free survival [ 28 ].…”