Chemical-genetic analysis of cyclin dependent kinase 2 function reveals an important role in cellular transformation by multiple oncogenic pathways

Abstract

A family of conserved serine/threonine kinases known as cyclindependent kinases (CDKs) drives orderly cell cycle progression in mammalian cells. Prior studies have suggested that CDK2 regulates S-phase entry and progression, and frequently shows increased activity in a wide spectrum of human tumors. Genetic KO/ knockdown approaches, however, have suggested that lack of CDK2 protein does not prevent cellular proliferation, both during somatic development in mice as well as in human cancer cell lines. Here, we use an alternative, chemical-genetic approach to achieve specific inhibition of CDK2 kinase activity in cells. We directly compare small-molecule inhibition of CDK2 kinase activity with siRNA knockdown and show that small-molecule inhibition results in marked defects in proliferation of nontransformed cells, whereas siRNA knockdown does not, highlighting the differences between these two approaches. In addition, CDK2 inhibition drastically diminishes anchorage-independent growth of human cancer cells and cells transformed with various oncogenes. Our results establish that CDK2 activity is necessary for normal mammalian cell cycle progression and suggest that it might be a useful therapeutic target for treating cancer.analog-sensitive kinase | cyclin-dependent kinase

Cyclin-Dependent Kinase Inhibitors as Anticancer Therapeutics

“…There are not currently enough CDK-selective agents available to comprehensively assess which of the many CDKs should be inhibited and in which combinations to block tumor growth. In this regard, the results of chemical-genetic screens (Bishop et al, 2000;Elphick et al, 2009;Enserink et al, 2009;Zimmermann et al, 2011;Horiuchi et al, 2012;Gravells et al, 2013) may be more informative than findings from knockout animals, since drug-inhibited CDKs may more closely resemble dominantnegative than null alleles because they likely still engage their cyclin partners and the rest of the CDK regulatory machinery. Additionally, future studies will be required to determine which combinations of subset-selective CDK inhibitors must be combined to overcome primary and acquired tumor resistance to these agents.…”

Why minimal is not optimal: Driving the mammalian cell cycle—and drug discovery—with a physiologic CDK control network

“…32 Cancer cells might have increased requirements for Cdk2 activity, however, as suggested by the ability of inhibitory analogs to impede anchorageindependent growth of Cdk2 as/as HCT116 cells and of Cdk2 -/-MEFs overexpressing Cdk2 as after transformation by multiple oncogenes. 43 Moreover, Cdk2 might be a potential target for "synthetic lethal" chemotherapy, which exploits vulnerability to DNA damage-either caused by intrinsic mutations or induced by drugs-in cancer cells. 44 The availability of both transformed (HCT116) and non-transformed (RPE-hTERT) Cdk2…”

Reinforcing targeted therapeutics with phenotypic stability factors

“…In addition, CDK2 inhibition drastically diminishes anchorage-independent growth of human cancer cells and cells transformed with various oncogenes. 22 Resistance to palbociclib is also associated with constitutive CDK2 activity. Induced palbociclib resistance in breast cancer cell lines resulted in decreased levels of endogenous CDK2 inhibitors, p21 and p27.…”