Figure 2. GDF-15 promotes pancreatic cancer cell proliferation in vitro and enhances the chemosensitivity of cells to gemcitabine. (A) The expression level of GDF-15 secreted by pancreatic cancer cell lines (AsPC-1, BxPC-3, Panc-1, Hs766t), was analyzed by ELISA. (B–E) Different concentrations of recombinant human GDF-15 protein, 0ng/ml, 5ng/ml, 10ng/ml, 20ng/ml, 40ng/ml, were added to the culture of the pancreatic cancer cell lines, AsPC-1, BxPC-3, Panc-1 and Hs766t. (F, G) The effect of recombinant human GDF-15 on pancreatic cancer cell lines (AsPC-1, BxPC-3) was detected by CCK-8 assay. The results are presented as the mean ± s.d. Significance was analyzed using GraphPad Prism. (H, I) The efficiency of lentivirus infection was detected by fluorescence microscope in AsPC-1 cells, and the results from ELISA assay indicated that GDF-15 expression was downregulated significantly. (J, K) The effect of GDF-15 knockdown on the proliferation of AsPC-1 and BxPC-3 cells was detected by CCK-8 assay. (L) WB assay for cleaved PARP in Lv-RNAi-NC- and Lv-RNAi-GDF-15-infected AsPC-1 cells after gemcitabine (20μM) for 48h using GAPDH as a loading control. ***P<0.0001.