Figure 3.

Tamoxifen induces cellular senescence in IMR90‐Ras cells. (A and B) IMR90‐Ras cells were treated with 500 nm of tamoxifen (4OHT), and IMR90 cells were transfected with control siRNA (NC) or Snail siRNA (#1). Seven days later, the cells were subjected to immunoblotting using the indicated antibodies (A and B). α‐Tubulin levels were monitored as a loading control. Results are representative of at least three experiments. (C) IMR90‐Ras cells treated with 500 nm of tamoxifen (4OHT) for 7 days were subjected to qRT‐PCR. *P < 0.05, ANOVA test. (D) Replicatively senescent, Ras‐induced senescent, and doxorubicin‐induced (DNA damage‐induced) senescent TIG‐3 cells were subjected to qRT‐PCR analyses. Young, young cells (<30 passage), replicative senescence (>70 population doubling). Young cells were treated with 250 ng·mL⁻¹ doxorubicin for 10 days. **P < 0.01, ANOVA test. (E) IMR90‐Ras cells treated with 1 ng·mL⁻¹ of TGF‐β and 500 nm of tamoxifen (4OHT) for 7 days were stained for SA‐β‐gal, and the positive cells were counted. Each value in (C–E) represents the mean ± SD of triplicate determinations from a representative experiment. Similar results were obtained at least three independent experiments. *P < 0.05, **P < 0.01, ANOVA test. (F) IMR90 cells infected with control (cont.) or HA‐tagged Snail (Snail‐HA) were cultured for 7 days and then were subjected to immunoblotting using the indicated antibodies. α‐Tubulin levels were monitored as a loading control. Results are representative of at least three experiments.