Figure 5.

Activation of SMAD signaling at low cell density and contribution of ROS signaling. (A) Smad7 overexpression changes the gene expression profile of LNCaP* cells under LD_hypo conditions. Ratios of mRNA species levels measured by RT-qPCR in pTRIP-mSMAD7 and pTRIP-control transduced cell populations cultured under LD_hypo conditions were averaged from 2 experiments using independent cell populations. Stars indicate significance of the decreased mRNA species accumulation upon murine Smad7 overexpression. (B) Glutathione supplementation reduces the activation of SMAD signaling at low density. Relative mRNA levels measured by RT-qPCR under LD_hypo, LD_hypo+glutathione and MD_hypo conditions were averaged from 4–5, 2 and 7–9 cell culture experiments, respectively. Stars indicate statistical significance of the difference in mRNA levels between cells cultured in LD_hypo and LD_hypo+glutathione. (C) Lack of additive effects between Smad7 overexpression and glutathione treatment on cloning efficiency. Cloning efficiency of pTRIP-control and pTRIP-mSmad7 transduced cell populations were measured under the indicated cell culture conditions. Data were averaged from 2 to 5 experiments made with 2 independent control and 2 independent Smad7 transduced cell populations processed in parallel. Stars indicate significance of the differences in cloning efficiency. Data are presented as mean ± s.d.