Open AccessNOL4 is Downregulated and Hyper-Methylated in Papillary Thyroid Carcinoma Suggesting Its Role as a Tumor Suppressor Gene
Author(s) -
Sara Sheikholeslami,
Fereidoun Azizi,
Asghar Ghasemi,
Abbas Alibakhshi,
Hossein Parsa,
Seyed Mohammad Tavangar,
Setareh Shivaee,
Marjan Zarif Yeganeh,
Ladan TeimooriToolabi
Publication year - 2020
Publication title -
international journal of endocrinology and metabolism/international journal of endocrinology and metabolism.
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 23
eISSN - 1726-9148
pISSN - 1726-913X
DOI - 10.5812/ijem.108510
Subject(s) - methylation , dna methylation , thyroid carcinoma , epigenetics , cancer research , tumor suppressor gene , thyroid cancer , papillary thyroid cancer , cancer , medicine , thyroid , promoter , cpg site , microbiology and biotechnology , gene , gene expression , biology , carcinogenesis , genetics
Background: Thyroid cancer is the fourth most common cancer in the world. Papillary thyroid carcinoma (PTC) accounts for 80% of all types of thyroid neoplasm. Epigenetic alterations such as DNA methylation are known as the main cause of different types of cancers through inactivation of tumor suppressor genes. Objectives: In the present study, the expression and methylation of suggested gene namely nucleolar protein 4 (NOL4) in PTC in comparison to multi nodular goiter (MNG) have been studied. Methods: Forty-one patients with PTC and 38 patients affected by MNG were recruited. Thyroid tissues were obtained during thyroidectomy. RNA and DNA were extracted from thyroid tissues. Quantitative RT-PCR assay was performed for determining the mRNA level of NOL4 while methylation-sensitive high resolution methylation was applied for assessing the methylation status with designing six pairs primers for six regions on gene promoter which were named from NOL4 (a) to NOL4 (f). Results: Methylation assessment of 81 CpG islands in the promoter region of NOL4 gene revealed that NOL4 (f), the nearest region to the start codon, was significantly hypermethylated in PTC cases compared to MNG cases. NOL4 level in PTC cases in comparison with MNG cases were downregulated. The methylation status and mRNA level of NOL4 (f) were associated with age of diagnosis (Age of the patient at the time of diagnosis), lymph node metastasis, and advanced stages of disease. Conclusions: These data suggested an aberrant promoter hyper-methylation of NOL4 in PTC cases may be linked with its downregulation. Therefore, NOL4 gene can be proposed as a potential tumor suppressor gene in PTC tissues.