Altered cyclin-dependent kinase activity is observed in many human malignancies. Cyclin-dependent kinases that promote cell cycle progression may be promising targets in the treatment of cancer. The therapeutic effects of roniciclib, a cyclin-dependent kinase inhibitor for medullary thyroid cancer were investigated in the present study. Roniciclib inhibited medullary thyroid cancer cell proliferation in a dose-dependent manner. Roniciclib induced caspase-3 activity and contributed to apoptosis. Cell cycle progression was arrested in the G2 phase. In vivo, roniciclib treatment retarded the growth of tumors of medullary thyroid cancer xenografts. In addition, roniciclib in combination with sorafenib was more effective than either single treatment in a xenograft model. No morbidity was observed in animals treated with single roniciclib therapy and combination treatment of roniciclib and sorafenib. These data provide a rationale for clinical assessment of using roniciclib in the treatment of patients with medullary thyroid cancer.
Keywords: cyclin-dependent kinase; medullary thyroid cancer; roniciclib.