Role of p21 and p27 in carcinogenesis and drug resistance

Human cancers arise from an imbalance of cell growth and cell death.Critical factors that control the balance are those regulate the cell cycle.Several molecular effectors have been identified to be able to regulate specific phases of the cell cycle,including cyclins,cyclin-dependent kinases (CDKs) and CDK inhibitors.Notably,deficiency of two G1-checkpoint CDK inhibitors-p21 (CDKN1A) and p27 (CDKN1B)-has been implicated to be correlated with initiation or progression of many human malignancies or cancer cells drug-resistance.However,contradict reports also suggested that p21 and p27 could promote tumor progression.Here,we summarized the historic and recent studies on these two CDK inhibitors,including their identification as well as their roles in carcinogenesis and drug resistance. Key words: Cyclin-dependent kinase inhibitor p21 ;  Cyclin-dependent kinase inhibitor p27;  Drug resistance,neoplasm