Background:Colorectal cancer (CRC) is the third leading cause of cancer death worldwide,
and its incidence is steadily rising in developing nations. Cell cycle aberrations due to deregulation
of cyclin dependent kinases (CDKs) and cyclins are common events during colorectal carcinogenesis.
Yet, efficacy of multitarget CDK inhibitors as therapeutic agents has not been much
explored against CRC.Objective:The anticancer potential of multitarget CDK inhibitor riviciclib (also known as
P276-00), was investigated against CRC cell lines of varied genetic background.Method:Cytotoxicity of riviciclib - potent CDK1, CDK4 and CDK9-specific inhibitor was evaluated
in vitro. Further, its effect on clonogenic potential, cell cycle, apoptosis and transcription was
tested using colony forming assay, flow cytometry and western blot analysis, respectively. Also, efficacy
of riviciclib in combination with standard chemotherapeutic agents was assessed. Dependency
of CRC cells on specific CDKs for their survival was confirmed using siRNA studies.Results:Riviciclib exerted significant cytotoxicity against CRC cells and inhibited their colony
forming potential. It induced apoptosis along with inhibition of cell cycle CDKs and cyclins as
well as transcriptional CDKs and cyclins. Moreover, dual combination of riviciclib with standard
chemotherapeutic drugs exhibited synergism in CRC cells. siRNA studies indicated that CRC cells
are dependent on specific CDKs for their survival which are targets of riviciclib.Conclusion:This study provides evidence that multitarget CDK inhibitors can serve as promising
therapeutic agents against CRC alone or in combination.