PT - JOURNAL ARTICLE AU - AYA ONO AU - RYO OIKE AU - YUKI OKUHASHI AU - YUSUKE TAKAHASHI AU - MAI ITOH AU - NOBUO NARA AU - SHUJI TOHDA TI - Comparative Effects of PP242 and Rapamycin on mTOR Signalling and NOTCH Signalling in Leukemia Cells DP - 2013 Mar 01 TA - Anticancer Research PG - 809--813 VI - 33 IP - 3 4099 - http://ar.iiarjournals.org/content/33/3/809.short 4100 - http://ar.iiarjournals.org/content/33/3/809.full SO - Anticancer Res2013 Mar 01; 33 AB - Aim: PP242 is a compound which inhibits both mammalian target of rapamycin complex-1 (mTORC1) and mTORC2. We examined the effects of PP242 and rapamycin on mTOR signalling and evaluated potential crosstalk with the NOTCH signalling in eight leukemia cell lines. Materials and Methods: We examined the effects of treatment with these inhibitors on cell growth and protein expression. Results: PP242 suppressed growth more potently than did rapamycin. In two cell lines poorly sensitive to PP242, PP242 failed to inhibit v-akt murine thymoma viral oncogene homolog (AKT) phosphorylation. Suppression of mTOR phosphorylation was weaker in myeloid cell lines. Rapamycin induced eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) hyperphosphorylation in three cell lines. Phosphorylation of both isoforms (p70 and p85) of S6 kinase (S6K) was suppressed in three cell lines; only p70 was suppressed in the others. NOTCH1 expression and activation were up-regulated by PP242 in one cell line but down-regulated in another. Conclusion: PP242 is a candidate for molecular-targeted leukemia therapy, although its effects must be evaluated on a case-by-case basis. Crosstalk was found between the mTOR and NOTCH signalling pathways.