Insulin-like growth factor binding protein-5 influences pancreatic cancer cell growth

Figure 6 PI3K or MEK1/2 inhibition decreases IGFBP-5-enhanced growth of serum-starved PaC cells. Stable transfectants (empty vector/Vec-closed square or high /BP5H-closed triangle) were seeded in growth media. The serum-containing medium was changed to SFM 24 h post-seeding. After 24 h in serum-free conditions, a PI3K inhibitor (LY294002, A and B) or MEK1/2 inhibitor (U0126, C and D) was added to the medium. After 48 h, an MTT assay (B and D) was performed to assess cell viability. Cell lysates were prepared at this time for immunoblot analysis of Akt or ERK1/2 activation (A and C, respectively) using phospho-specific antibodies. For immunoblots, cells were treated with 25 &mgr;mol/L LY294002 or 10 &mgr;mol/L U0126, as indicated. Membranes were subsequently stripped and reprobed for total Akt or ERK1/2 (A and C, respectively). Actin level was monitored to normalize protein loading. Data shown represent the mean ± SE from 4 separate experiments performed in triplicate. The percentage of viable cells was determined relative to control-treated cells (100%). ^aP < 0.05, ^bP < 0.01, ^dP < 0.001.