Silencing of CDK2, but not CDK1, separates mitogenic from anti-apoptotic signaling, sensitizing p53 defective cells for synthetic lethality

Abstract

Small molecule inhibitors targeting CDK1/CDK2 have been clinically proven effective against a variety of tumors, albeit at the cost of profound off target toxicities. To separate potential therapeutic from toxic effects, we selectively knocked down CDK1 or CDK2 in p53 mutated HACAT cells by siRNA silencing. Using dynamic, cell cycle wide proteome arrays, we observed minor changes in overall abundance of proteins critically involved in cell cycle transition despite profound G 2 /M or G 1 /S arrest, respectively. Employing phospho site specific analyses, we identified uncoupled mitogenic, yet pro-apoptotic signaling from counter balancing anti-apoptotic activity in CDK2 disrupted cells. Moreover, a crucial role of CDK2 activity in early serum response was observed, extending well-established roles of CDKs outside their cell cycle regulating functions. In contrast, disruption of CDK1 only marginally affected phosphorylation events of crucial signaling nodes prior to G 2 /S transition. The data presented here suggest that the temporal separation of pro-and anti-apoptotic pathways by selective inhibition of CDK2 disrupts coherent signaling modules and may synergize with anti-proliferative drugs, averting toxic side effects from CDK1 inhibition.

Cyclin-dependent kinases-based synthetic lethality: Evidence, concept, and strategy

“…In addition, BCL2-associated agonist of cell death (BAD) reduces Ser-155 phosphorylation, which implies that BAD can effectively form a dimer with BCL-xL and thus induce apoptosis. This discovery reveals that CDK2 is correlated with the PI3K/AKT/mTOR signaling pathway and shows additional potential for CDK inhibitors in P53-independent apoptosis 48 . Furthermore, CDK1/2 and PI3K are a pair of powerful synthetic lethality targets in the treatment of malignant glioma, and the cooperation of CDK1/2 and PI3K inhibitors leads to the depletion of the antiapoptotic protein survivin and shows clinical therapeutic potential in glioma xenografts 49 .…”

Synthetic Lethality-based Identification of Targets for Anticancer Drugs in the Human Signaling Network

“…In the MYC-dependent breast cancer, another alternative is to target MYC’s SL partner gene CDK1, as reported in some small interfering RNA (siRNA) experiment 31 . Secondly, CDK2 was predicted to be SL partner gene with p53 and MYCN by RNA interference techniques 32 , 33 . In p53 defective cells, CDK2 can separate mitogenic from anti-apoptotic signaling for SL 33 .…”

“…Secondly, CDK2 was predicted to be SL partner gene with p53 and MYCN by RNA interference techniques 32 , 33 . In p53 defective cells, CDK2 can separate mitogenic from anti-apoptotic signaling for SL 33 . The SL relationship between CDK2 and MYCN indicates CDK2 inhibitors as potential MYCN-selective cancer therapeutics 32 .…”

Comprehensive analysis of differential expression profiles reveals potential biomarkers associated with the cell cycle and regulated by p53 in human small cell lung cancer

“…By comparison, the dysfunctional p53 fails to suppress formation of the CDK1-CCNB1 complex, and this newly formed CCK1-CCNB1 complex promotes the dissociation of the E2F-Rb complex via phosphorylation of Rb in the G1 phase. Subsequently, the E2F obtained may accelerate cell cycle progression from the G2 to the M phase ( 56 , 57 ).…”