Limited overlapping roles of P15INK4b and P18INK4c cell cycle inhibitors in proliferation and tumorigenesis

AUTOR(ES)

Latres, Esther

FONTE

Oxford University Press

RESUMO

Entry of quiescent cells into the cell cycle is driven by the cyclin D-dependent kinases Cdk4 and Cdk6. These kinases are negatively regulated by the INK4 cell cycle inhibitors. We report the generation of mice defective in P15INK4b and P18INK4c. Ablation of these genes, either alone or in combination, does not abrogate cell contact inhibition or senescence of mouse embryo fibroblasts in culture. However, loss of P15INK4b, but not of P18INK4c, confers proliferative advantage to these cells and makes them more sensitive to transformation by H-ras oncogenes. In vivo, ablation of P15INK4b and P18INK4c genes results in lymphoproliferative disorders and tumor formation. Mice lacking P18INK4c have deregulated epithelial cell growth leading to the formation of cysts, mostly in the cortical region of the kidneys and the mammary epithelium. Loss of both P15INK4b and P18INK4c does not result in significantly distinct phenotypic manifestations except for the appearance of cysts in additional tissues. These results indicate that P15INK4b and P18IKN4c are tumor suppressor proteins that act in different cellular lineages and/or pathways with limited compensatory roles.

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