Abstract
Simple SummaryMedullary thyroid cancer (MTC) is often discovered in its advanced stage. Although a rare disease, advanced MTC cases have poor prognosis and the treatment is often palliative. Several studies have reported the existence of an association between copy number alterations (CNAs) burden and cancer progression. Moreover, the accumulation of broad CNAs, which contribute to intra-tumor heterogeneity, might be required for immune evasion. The identification of the recurrent CNAs associated with tumor phenotype aided in discovering new therapeutics options in several cancer types. To our knowledge, CNA is not well characterized in MTC. We analyzed recurrent focal CNAs on MTC. Our analysis provides a novel insight on MTC biology and may help in uncovering novel potential therapeutic targets.Medullary thyroid carcinoma (MTC) is a malignant tumor originating from thyroid C-cells that can occur either in sporadic (70–80%) or hereditary (20–30%) form. In this study we aimed to identify recurrent copy number alterations (CNA) that might be related to the pathogenesis or progression of MTC. We used Affymetrix SNP array 6.0 on MTC and paired-blood samples to identify CNA using PennCNV and Genotyping Console software. The algorithms identified recurrent copy number gains in chromosomes 15q, 10q, 14q and 22q in MTC, whereas 4q cumulated losses. Coding genes were identified within CNA regions. The quantitative PCR analysis performed in an independent series of MTCs (n = 51) confirmed focal recurrent copy number gains encompassing the DLK1 (14q32.2) and AIFM3 (22q11.21) genes. Immunohistochemistry confirmed AIFM3 and DLK1 expression in MTC cases, while no expression was found in normal thyroid tissues and few MTC samples were found with normal copy numbers. The functional relevance of CNA was also assessed by in silico analysis. CNA status correlated with protein expression (DLK1, p = 0.01), tumor size (DLK1, p = 0.04) and AJCC staging (AIFM3 p = 0.01 and DLK1 p = 0.05). These data provide a novel insight into MTC biology, and suggest a common CNA landscape, regardless of if it is sporadic or hereditary MTC.
Highlights
Medullary thyroid carcinoma (MTC) is a malignant thyroid tumor originating from the parafollicular C-cells of the thyroid, which accounts for 1–5% of all thyroid cancers worldwide [1]
PennCNV analysis revealed that MTC samples presented from 8 to 41 copy number alterations (CNA), while Genotyping Console uncovered that MTC samples
Multiple somatic events have been reported in sporadic MTC, which have been associated with clinical outcome [20], none of these studies have identified recurrent genetic alterations that were associated with MTC development and progression
Summary
Medullary thyroid carcinoma (MTC) is a malignant thyroid tumor originating from the parafollicular C-cells of the thyroid, which accounts for 1–5% of all thyroid cancers worldwide [1]. MTC may occur either in a sporadic (75%) or in a hereditary (25%) form. Germline gain-of-function mutations in the RET gene have been associated with inherited predisposition to MEN2A and MEN2B [1,4]. It has been suggested that somatic or germline mutations on the RET gene are not the only determinant of the MTC phenotype. In the hereditary form, it represents a favorable genetic background to develop C-cell hyperplasia, which precedes the development of MTC. The classical progression from C-cell hyperplasia to MTC, to loco-regional lymph nodes, and to distant metastasis, has been observed in man, and is largely associated with the type of RET mutation [1]. In one or few preneoplastic C-cells, may confer clonal advantages and tumorigenic properties to the cells
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