Rapamycin Inhibits Constitutive p70s6k Phosphorylation, Cell Proliferation, and Colony Formation in Small Cell Lung Cancer Cells

摘要: The serine/threonine kinase p70s6k was found to be constitutively phosphorylated in H 69, 345, and 510 small cell lung cancer cells as judged by the retarded electrophoretic mobility of both isoforms this kinase. Pretreatment with potent immunosuppressant rapamycin led dephosphorylation a concentration-dependent manner; half-maximum maximum effects were achieved at 0.3 3 nm rapamycin, respectively. Rapamycin inhibited growth liquid culture similar concentrations those required for inducing p70s6k. Furthermore, markedly reduced basal colony forming ability semisolid media. Thus, phosphorylated/active plays an important role promoting cells. rapamycin-sensitive pathway may provide novel target therapeutic intervention cancer.