ku-0063794 and Kidney-Neoplasms

The objective of this study was to characterise the mechanism underlying acquired resistance to temsirolimus, an inhibitor of mammalian target of rapamycin (mTOR), in renal cell carcinoma (RCC).. A parental human RCC cell line, ACHN (ACHN/P), was continuously exposed to increasing doses of up to 20 μM of temsirolimus, and a cell line resistant to temsirolimus (ACHN/R), showing a sixfold higher IC50 than that of ACHN/P, was developed.. Following treatment with temsirolimus, phosphorylation of S6 kinase in ACHN/P was markedly inhibited, whereas there was no detectable expression of phosphorylated S6 in ACHN/R before and after temsirolimus treatment. However, AKT and p44/42 mitogen-activated protein kinase (MAPK) were constitutively phosphorylated even after temsirolimus treatment in ACHN/R, but not in ACHN/P. There was no significant difference between the sensitivities of ACHN/P and ACHN/R to KU0063794, a dual inhibitor of mTOR complex 1 (mTORC1) and mTORC2. Similar sensitivities to temsirolimus in ACHN/P and ACHN/R could be achieved by additional treatment with specific inhibitors of AKT- and MAPK-signaling pathways.. The activation of signal transduction pathways via mTORC2, but not via mTORC1, may have an important role in the acquisition of a resistant phenotype to temsirolimus in RCC.

Topics: Animals; Apoptosis; Butadienes; Carcinoma, Renal Cell; Cell Line, Tumor; Chromones; Drug Resistance, Neoplasm; Humans; Kidney Neoplasms; Male; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice, Inbred BALB C; Mice, Nude; Mitogen-Activated Protein Kinases; Morpholines; Multiprotein Complexes; Nitriles; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Pyrimidines; Ribosomal Protein S6 Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases