Rapamycin-resistant and torin-sensitive mTOR signaling promotes the survival and proliferation of leukemic cells

• Published in: BMB reports Vol. 49; no. 1; pp. 63 - 68
• Main Authors: Park, Seohyun, Sim, Hyunsub, Lee, Keunwook
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Society for Biochemistry and Molecular Biology 01-01-2016; 생화학분자생물학회
• Subjects: Animals; Apoptosis Regulatory Proteins - metabolism; Bcl-2-Like Protein 11; Blood Proteins - pharmacology; Cell Proliferation - drug effects; Cell Survival - drug effects; Cells, Cultured; Forkhead Box Protein O1; Forkhead Transcription Factors - antagonists & inhibitors; Forkhead Transcription Factors - genetics; Forkhead Transcription Factors - metabolism; Humans; Jurkat Cells; K562 Cells; Membrane Proteins - metabolism; Mice; Mice, Inbred C57BL; Phosphatidylinositol 3-Kinases - metabolism; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; RNA Interference; Signal Transduction - drug effects; Sirolimus - pharmacology; TOR Serine-Threonine Kinases - antagonists & inhibitors; TOR Serine-Threonine Kinases - metabolism; 화학
• ISSN: 1976-6696; 1976-670X
• DOI: 10.5483/BMBRep.2016.49.1.201

The serine/threonine kinase mTOR is essential for the phosphoinositide 3-kinases (PI3K) signaling pathway, and regulates the development and function of immune cells. Aberrant activation of mTOR signaling pathway is associated with many cancers including leukemia. Here, we report the contributions of mTOR signaling to growth of human leukemic cell lines and mouse T-cell acute leukemia (T-ALL) cells. Torin, an ATP-competitive mTOR inhibitor, was found to have both cytotoxic and cytostatic effects on U-937, THP-1, and RPMI-8226 cells, but not on Jurkat or K-562 cells. All cells were relatively resistant to rapamycin even with suppressed activity of mTOR complex 1. Growth of T-ALL cells induced by Notch1 was profoundly affected by torin partially due to increased expression of Bcl2l11 and Bbc3. Of note, activation of Akt or knockdown of FoxO1 mitigated the effect of mTOR inhibition on T-ALL cells. Our data provide insight on the effect of mTOR inhibitors on the survival and proliferation of leukemic cells, thus further improving our understanding on cell-context-dependent impacts of mTOR signaling.