05). The similarity of the results was found in HPAC cells (data not shown). This result further suggests the enhanced cell proliferation ability and survival efficiency of GW-572016 datasheet mesothelin overexpressed cells. We next investigated Selleck AR-13324 the signal transduction mechanism of cell survival and proliferation in these cells of mesothelin-overexpression. To identify signals activated by mesothelin, we examined transcription factors p53, bcl-2,bax and PUMA level in stable mesothelin overexpressed cells.In the

HPAC (wt-p53) and Capan-2(wt-p53) cells, mesothelin significantly decreased the p53,bax and increased bcl-2 levels (Figures 3C and D). Although PUMA was a little decrease,no significant different was seen(data eFT-508 order not shown). This data indicated mesothelin

promotes cell survival and proliferation by p53dependent pathway in HPAC and Capan-2 cells with wt-p53. Overexpression of mesothelin increases cell proliferation in pancreatic cancer cells with mt-p53 by p53- independent pathway In the MIA PaCa-2(mutant p53) cells, mesothelin increases bcl-2 levels and decreased bax level,however,the level of p53 and PUMA was not affected (Figure 4E). This data indicated mesothelin promotes cell survival and proliferation by p53-independent pathway in MIA PaCa-2 cells with mt-p53 Figure 4 Mesothelin sliencing suppresses cell survival, proliferation and promotes apoptosis. A, Cell viability was reduced upon mesothelin sliencing in ASPC-1 and Capan-2 cells. B, Number of colony formation was reduced upon mesothelin sliencing in ASPC-1 and Capan-2 cells. C, Apoptotic Adenylyl cyclase percentages of FCM assays in mesothelin sliencing in ASPC-1 and Capan-2 cells. D, Apoptotic percentages of

TUNEL assays in mesothelin sliencing in ASPC-1 and Capan-2 cells. Results are means±S.E.M. *P < 0.05. Knockdown of mesothelin expression by shRNA inhibited cell growth and induced apoptosis To determine whether mesothelin could be an effective therapeutic target for pancreatic cancer, the effect of mesothelin shRNA on cell growth of the pancreatic cancer cells was examined in ASPC-1 and CaPan-1/2 pancreatic cancer cells. The reason for choosing these pancreatic cancer cell lines was due to the fact that these cell lines showed much higher expression of mesothelin. The cell viability was determined by MTT, and the effect of mesothelin shRNA on the growth of cancer cells is shown in Figure 4A. We found that down-regulation of mesothelin expression significantly caused cell growth inhibition in the ASPC-1 and CaPan-2 pancreatic cancer cell lines (Figure 4A, P<0.05,respectively). Similar results was shown in CaPan-1 cells (data not shown). Colony formation assay shown mesothelin knockdown of mesothelin caused 50% and 60% decrease in colony formation in mesothelin -sliencing ASPC-1 and Capan-2 stable cell line compared to mock transfected cells,respectively (Figure 4B, P<0.05,respectively).