Abstract 460: Diagnostic and prognostic value of expression of CCND1 splice variant cyclin D1b in papillary thyroid carcinoma

Abstract

Abstract Background: An active cyclin D1 isoform, cyclin D1b, arises as a result of a failure to splice the fourth intron of the CCND1 pre-mRNA transcript. The expression of cyclin D1b has been associated with tumorigenesis and tumor progression in many types of human cancer. However, no studies with cyclin D1b have yet been reported in the thyroid cancer. Methods: We investigated the CCND1 rs9344 (cDNA 870) polymorphism by TaqMan SNP genotyping assay and expression profiles of mRNA and protein of full-length cyclin D1 (cyclin D1a) and cyclin D1b by quantative real-time PCR and immunohistochemistry in 286 thyroid tumors including 16 nodular hyperplasias, 33 follicular adenomas (FA), 179 papillary thyroid carcinomas (PTC), 32 follicular thyroid carcinomas (FTC), 5 poorly differentiated carcinomas (PDC), 4 anaplastic thyroid carcinomas (ATC), and 17 medullary thyroid carcinomas (MTC). The relationships between cyclin D1 expression levels and clinicopathological features were analyzed. Results: The cyclinD1b mRNA expression level in all thyroid tumors was significantly higher in the AA and GA genotype groups compared with the GG genotype group (p<0.001 and p = 0.006, respectively). The mRNA expression levels of cyclin D1b was significantly higher in PTCs when compared to benign or other malignant tumors (p<0.001) while no significant difference in cyclin D1a mRNA expression was observed according to the genotypes or tumor types. PTCs showed similar expression levels of cyclin D1b mRNA regardless of histologic subtypes, even when compared with follicular variant. In immunohistochemistry analysis, cyclin D1b overexpression was observed in PTC, PDC, ATC, and MTC, but not in FA and FTC. Cytoplasmic overexpression of cyclin D1b was significantly associated with advanced tumor stage in all PTCs (p = 0.025). Nuclear overexpression of cyclin D1b was associated with an increased incidence of lymph node metastases (p = 0.014) in classic PTCs. Conclusion: The A allele of the rs9344 polymorphism predisposes for cyclin D1b production in thyroid cancer. Cyclin D1b overexpression has a diagnostic biomarker utility to differentiate PTC from benign follicular nodules and may be functionally involved in the progression of the disease. Citation Format: Chan Kwon Jung, Sora Jeon, Yourha Kim, Ahwon Lee, Gyeong Sin Park. Diagnostic and prognostic value of expression of CCND1 splice variant cyclin D1b in papillary thyroid carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 460.