CpG island status as an epigenetic alteration for NIS promoter in thyroid neoplasms; a cross-sectional study with a systematic review

Maryam Zarkesh; Noman Arab; Raziyeh Abooshahab; Shabnam Heydarzadeh; Sara Sheikholeslami; Zahra Nozhat; Marziyeh Salehi Jahromi; Seyed Ahmad Fanaei; Mehdi Hedayati

doi:10.1186/s12935-022-02720-w

CpG island status as an epigenetic alteration for NIS promoter in thyroid neoplasms; a cross-sectional study with a systematic review

Cancer Cell Int. 2022 Oct 11;22(1):310. doi: 10.1186/s12935-022-02720-w.

Authors

Maryam Zarkesh¹, Noman Arab², Raziyeh Abooshahab³, Shabnam Heydarzadeh¹, Sara Sheikholeslami¹, Zahra Nozhat⁴, Marziyeh Salehi Jahromi⁵, Seyed Ahmad Fanaei⁶, Mehdi Hedayati⁷

Affiliations

¹ Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
² Department of Clinical Biochemistry, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
³ Curtin Medical School, Curtin University, Bentley, 6102, Australia.
⁴ Institute of Smart Biomedical Materials, School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China. zahranozhat85@zstu.edu.cn.
⁵ Department of Physiology and Pharmacology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH, USA.
⁶ Erfan Hospital, Tehran, Iran.
⁷ Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, PO Box: 19395-4763, Tehran, Iran. hedayati@endocrine.ac.ir.

Abstract

Background: Gene silence via methylation of the CpG islands is cancer's most common epigenetic modification. Given the highly significant role of NIS in thyroid cancer (TC) differentiation, this cross-sectional study aimed to investigate the DNA methylation pattern in seven CpG islands (CpG1-7 including +846, +918, +929, +947, +953, +955, and +963, respectively) of the NIS promoter in patients diagnosed with papillary (PTC), follicular (FTC), and multinodular goiter (MNG). Additionally, a systematic review of the literature was conducted to compare our results with studies concerning methylation of the NIS gene promoter.

Methods: Thyroid specimens from 64 patients met the eligibility criteria, consisting of 28 PTC, 9 FTC, and 27 benign MNG cases. The mRNA of NIS was tested by qRT-PCR. The bisulfite sequencing PCR (BSP) technique was performed to evaluate the promoter methylation pattern of the NIS gene. Sequencing results were received in chromatograph, FASTA, SEQ, and pdf formats and were analyzed using Chromas. The methylation percentage at each position and for each sample was calculated by mC/(mC+C) formula for all examined CpGs; following that, the methylation percentage was also calculated at each CpG site. Besides, a literature search was conducted without restricting publication dates. Nine studies met the eligibility criteria after removing duplicates, unrelated articles, and reviews.

Results: NIS mRNA levels decreased in tumoral tissues of PTC (P = 0.04) and FTC (P = 0.03) patients compared to their matched non-tumoral ones. The methylation of NIS promoter was not common in PTC samples, but it was frequent in FTC (P < 0.05). Significant differences were observed in the methylation levels in the 4th(+ 947), 6th(+ 955), and 7th(+ 963) CpGs sites in the forward strand of NIS promoter between FTC and MNG tissues (76.34 ± 3.12 vs 40.43 ± 8.42, P = 0.004, 69.63 ± 3.03 vs 23.29 ± 6.84, P = 0.001 and 50.33 ± 5.65 vs 24 ± 6.89, P = 0.030, respectively). There was no significant correlation between the expression and methylation status of NIS in PTC and FTC tissues.

Conclusion: Perturbation in NIS promoter's methylation individually may have a potential utility in differentiating MNG and FTC tissues. The absence of a distinct methylation pattern implies the importance of other epigenetic processes, which may alter the production of NIS mRNA. In addition, according to the reversibility of DNA methylation, it is anticipated that the design of particular targeted demethylation medicines will lead to a novel cancer therapeutic strategy.

Keywords: CpG islands; DNA methylation; Epigenetics; Follicular thyroid cancer; Multinodular goiter; Papillary thyroid cancer; Sodium/iodide symporter.