Research Paper Volume 10, Issue 11 pp 3574—3589

Suppression of mTORC1 activity in senescent Ras-transformed cells neither restores autophagy nor abrogates apoptotic death caused by inhibition of MEK/ERK kinases

Figure 1. mTORC1 suppression does not rescue viability of senescent ERas cells exposed to the MEK/ERK inhibitor. (A)Viability of control and senescent ERas cells exposed to mTOR inhibitor pp242 (200 nM, 500 nM, 750 nM, 1500 nM), as assayed by MTT test. (B) Suppression of 4E-BP1 phosphorylation by pp242 in senescent ERas cells monitored by Western-blotting. Numbers below represent densitometry of the bands. (C) Viability of senescent ERas cells exposed to pp242 (200 nM) and MEK/ERK inhibitor PD0325901 (PD, 1 µM) assayed by MTT test. (D) Senescent cells are unable to restore proliferation after MEK/ERK suppression. Cells were exposed to NaBut, PD0325901 and pp242 for 72h then supplemented with a medium without inhibitors for 48 h. Cells were stained with Crystal Violet. (E) Senescent ERas cells undergo apoptosis upon mTORC1 and MEK/ERK suppression. DNA fragmentation analysis in 1,5% agarose gel electrophoresis. Serum- starved ERas (LS) were used as positive control for apoptotic DNA fragmentation.