Investigation of selective CDK4/6 inhibitor (Abemaciclib) cytotoxicity effects on human anaplastic thyroid cancer

Background: Thyroid cancer is one of the most common endocrine malignancies. Anaplastic thyroid cancer is a rare and dead full cancer among types of the thyroid cancer. Despite the conventional chemotherapy, a considerable number of the patients show developing chemo resistance. Therefore, there is a necessary need to find the novel therapeutic approaches in the anaplastic thyroid cancer patients. The aim of this study was to study anti-tumor effect of Abemaciclib on the anaplastic thyroid carcinoma cell lines. Materials and methods: The human anaplastic thyroid cancer (SW1736 and C643) were cultured according to ATCC recommendations. The MTT assay was used to assess the chemo sensitivity of the cell lines in exposure to the desire concentration of Abemaciclib. Colony formation assay was used to determine the ability of the cell line colony formation in exposure to the drug. Quantitative real-time PCR was applied to analyze the mRNA expression of the apoptotic and anti-apoptotic genes. Results: The cell viability and proliferation of the thyroid cancer cell lines were remarkably inhibited in doses of 10 and 20 μM of Abemaciclib (p<0.0001). Also, Abemaciclib reduced the number of the SW1736 and C643 colonies in doses of 1 and 2.5 μM, respectively. Moreover, Abemaciclib significantly reduced anti-apoptotic gene expression levels, including BCL2 and CMYC, and increased pro-apoptotic gene expression levels, including p21 and BAX (p<0.05). Conclusion: Our study suggests that Abemaciclib could be used as a therapeutic agent in anaplastic thyroid cancer. Further laboratory and animal studies are needed and recommended to evaluate the exact molecular and clinical properties of Abemaciclib.