Co-occurrence of cfdna brafv600e mutation and rassf1/slc5a8 genes promoter hypermethylation in papillary thyroid carcinomas

Fatemeh Khatami,1,* Ladanteimoori-toolabi,2 Bagher larijani,3 Ramin heshmat,4 Mohammad haddadi aghdam,5 Seyed mohammad tavangar,6

1. Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute,TUMS
3. Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, TUMS
5. Molecular Medicine Departments, Pasteur Institute of Iran, Tehran, Iran
6. Departments of Pathology, Dr. Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran

Abstract

Introduction

The circulating cell-free dna (cfdna) has been considered as a non-invasive biomarker for cancer diagnosis and progression. both genetic (mutations) and epigenetic alteration (methylations) in cfdna can be evaluated in order to access the thyroid tumors markers. in addition to braf mutation, rassf1 and slc5a8 promoter methylation can be used for early diagnosis and prognosis of papillary thyroid cancers (ptc).in this research we assess the use of circulating plasma cfdna and tissue dna for brafv600e mutation, five promoter regions of rassf1 and slc5a8 methylation in the diagnosis, and management of ptc patients and goiter samples as controls.

Methods

Both plasma cfdna and tissue dna of 57 ptc and 45 goiter samples were extracted. brafv600e mutation of cf-dnas and their counterpart tissue dnas were measured by quantitative real-time pcr. moreover, we analyze the state of hypermethylation of five promoter regions of rassf1 and slc5a8 genes by methylation specific high resolution melting (ms-hrm), in order to evaluate their involvement in the ptc pathogenesis.

Results

The mutation brafv600e was found in 39 (68.4%) out of 57 ptc tissue dna samples, and 33(49.1 %) of cfdna. the circulating cfdna brafv600e mutation and clinico-pathologic features showed a significant difference between metastatic and non-metastatic ptc ones (22 of 33 vs. 5 of 34, p-value: <0.001). among three promoter region of slc5a8 and two promoter regions of rassf1 (b) (66.6% of ptc cases vs. 20.0 % of goiter samples, p-value: 0.001) and slc5a8 (c) (61.4% of ptc cases vs. 17.7 % of goiter samples, p-value: 0.005) as the core promoter regions showed the significant difference between ptc cases and goiter controls. the methylation level of tissues was the same as the methylation level of cfdna.

Conclusion

There is promising evidence that brafv600e somatic mutation and rassf1 (b) and slc5a8 (c) promoter hypermethylation in papillary thyroid cancer can be detected in circulating cfdna and are associated with more advanced ptc disease

Keywords

Cfdna, methylation, braf mutation