Aim: TYMS gene encodes for TS enzyme involved in 5-fluorouracil (5-FU) and capecitabine (CAP) metabolism. This study assessed the association of TYMS-TSER and 3RG>C polymorphisms with 5-FU/CAP adve...

Liquid biopsy enables real-time monitoring of tumor development and response to therapy through the analysis of CTCs and ctDNA. NALCN is a sodium leak channel that is frequently involved in tumor evolution and immunity and acts as a tumor suppressor. Deletion of NALCN has been shown to increase cancer metastasis and the number of CTCs in peripheral blood. In this study, we investigated for the first time NALCN promoter methylation in (a) Aza-treated cell lines (A549, TE671, BT20, and MDA-MB-468), (b) paired NSCLC tissues (n = 22), and (c) plasma cell-free DNA (ctDNA) from patients with NSCLC (early stage n = 39, metastatic n = 39) and DNA from 10 healthy donors (HD) using a newly developed highly specific and sensitive real-time MSP method. Treatment with 5′-aza-dC induced the expression of NALCN only in the A549 cell line, suggesting that DNA methylation regulates its expression in certain cancers. The mRNA expression levels of NALCN were quantified in non-small cell lung cancer (NSCLC) and adjacent non-cancerous tissues, and it was found to be underexpressed in 54.5% of tumor tissues, with significantly higher expression in recurrence-free patients (p = 0.009) than in patients who relapsed. The NALCN methylation level was not statisticallysignificantlycorrelated with the corresponding expression (p = 0.439), while Kaplan–Meier analysis showed an association between NALCN promoter hypermethylation and worse disease-free intervals (DFIs) (p = 0.017). Evaluation of NALCN methylation in ctDNA revealed that it was detected in 5.1% of early and 10.2% of advanced cases. Our results strongly suggest that epigenetic inactivation of NALCN may be a predictor of metastasis in NSCLC. Our results should be validated in further studies based on a larger patient cohort to further investigate whether DNA methylation of the NALCN promoter could serve as a potential prognostic DNA methylation biomarker and predictor of metastasis in NSCLC.

Background: Cancer of the stomach represents one of the most common cancers all over the world. In these patients, several tumor suppressor genes are deactivated leading to tumor development. The deactivation of tumor suppressor genes, caused by hypermethylation of its promoters, has been correlated with poor prognosis in gastric cancer patients. Materials and methods: In this study, the methylation status of the tumor suppressor gene RASSF1A was determined in the cell free DNA (cfDNA) of 55 patients with metastatic gastric cancer, using methylation specific polymerase chain reaction (PCR). Results: The promoter region of RASSF1A gene was found to be methylated in 42 patients, but in none of the healthy control samples. Methylation of the promoter region of this gene was found to be correlated with shorter progression free survival (PFS, p=0.026) and overall survival (OS, p=0.001) as compared to that of patients without promoter methylation. Conclusions: These results are of interest and further studies are necessary to clarify whether hypermethylation of the RASSF1A tumor suppressor gene, could take a place as a biomarker for the early diagnosis, prognosis and prediction of response to treatment in patients with metastatic gastric cancer.