title: Cdk2 deficiency decreases ras/CDK4-dependent malignant progression, but not myc-induced tumorigenesis.
abstract: We have previously shown that forced expression of CDK4 in mouse skin (K5CDK4 mice) results in increased susceptibility to squamous cell carcinoma (SCC) development in a chemical carcinogenesis protocol. This protocol induces skin papilloma development, causing a selection of cells bearing activating Ha-ras mutations. We have also shown that myc-induced epidermal proliferation and oral tumorigenesis (K5Myc mice) depends on CDK4 expression. Biochemical analysis of K5CDK4 and K5Myc epidermis as well as skin tumors showed that keratinocyte proliferation is mediated by CDK4 sequestration of p27Kip1 and p21Cip1, and activation of CDK2. Here, we studied the role of CDK2 in epithelial tumorigenesis. In normal skin, loss of CDK2 rescues CDK4-induced, but not myc-induced epidermal hyperproliferation. Ablation of CDK2 in K5CDK4 mice results in decreased incidences and multiplicity of skin tumors as well as malignant progression to SCC. Histopathologic analysis showed that K5CDK4 tumors are drastically more aggressive than K5CDK4/CDK2-/- tumors. On the other hand, we show that CDK2 is dispensable for myc-induced tumorigenesis. In contrast to our previous report of K5Myc/CDK4-/-, K5Myc/CDK2-/- mice developed oral tumors with the same frequency as K5Myc mice. Overall, we have established that ras-induced tumors are more susceptible to CDK2 ablation than myc-induced tumors, suggesting that the efficacy of targeting CDK2 in tumor development and malignant progression is dependent on the oncogenic pathway involved.
authors.affiliation: Center for Comparative Medicine and Translational Research, Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina 27606, USA.
authors.forename: Everardo
authors.initials: E
authors.lastname: Macias
authors.forename: Yongbaek
authors.initials: Y
authors.lastname: Kim
authors.forename: Paula L
authors.initials: PL
authors.lastname: Miliani de Marval
authors.forename: Andres
authors.initials: A
authors.lastname: Klein-Szanto
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Rodriguez-Puebla
mesh_terms: D000818:Animals; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology*; D051357:Cyclin-Dependent Kinase 2 / Q000172:deficiency* / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D018450:Disease Progression; D004789:Enzyme Activation; D005260:Female; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology*; D013755:Tetradecanoylphorbol Acetate; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D002273:Carcinogens; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D050760:Cyclin-Dependent Kinase Inhibitor p27; C495893:Cdk2 protein, mouse; C495902:Cdk4 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018631:ras Proteins; D013755:Tetradecanoylphorbol Acetate