Research Paper Volume 9, Issue 11 pp 2352—2375

Targeted elimination of senescent Ras-transformed cells by suppression of MEK/ERK pathway

Figure 3. MEK/ERK suppression activates autophagy, which cancels the senescence program in control cells and attenuates senescence markers in NaBut-exposed cells. (A) Senescence-associated β-galactosidase activity is high in senescent cells, but decreases upon MEK/ERK suppression. Visualized using Pascal LSM 5 microscope (images) and estimated by colorimetric assay (histogram). (B) Cell size and protein level decrease upon MEK/ERK suppression in intact cells and almost does not change in senescent cells where cytoprotective autophagy is disrupted. Cells were treated with inhibitors for 72 h. To evaluate cell size, cells were harvested and proceeded for flow cytometry to measure forward scattering. For protein content, 1x106 cells were harvested, lysed and the protein amount was measured using Bradford assay. Data are presented as mean ±S.E.M. of three independent experiments (n=3). (C) Lactate level in culture medium decreases upon MEK/ERK suppression. Cells were treated with inhibitors for indicated time points, medium was collected and proceeded for measurement of lactate. Data are presented as mean ±S.E.M. of three independent experiments (n=3).