Figure 4

PI3K/Akt signaling is required for VPA-induced upregulation of MICA and MICB in pancreatic cancer cells. (A, B) Quantitative real-time RT-PCR analysis. The VPA-induced upregulation of MICA and MICB mRNA expression were inhibited by the HER2/HER3 inhibitor lapatinib and the PI3K inhibitor LY294002, but not by the ATM/ATR inhibitor caffeine. Data are mean ± SD of a single experiment performed in triplicate, all results were reproducible in three independent experiments. * P < 0.05; ** P < 0.01; ns P > 0.05. (C) Flow cytometry analysis. The VPA-induced upregulation of MICA and MICB protein expression on the cell surface were inhibited by the PI3K inhibitor LY294002. MFI, mean fluorescence intensity; * P < 0.05. (D) Western blotting analysis. Transfection of the PI3KCA siRNA inhibited PI3KCA protein expression at 48 h post-transfection. NC, negative control; siR1-3, PI3KCA_siR sequence 1-3; ** P < 0.01. (E) Quantitative real-time RT-PCR analysis. VPA-induced upregulation of MICA and MICB mRNA expression were attenuated in PI3KCA-knockdown cells; Data are mean ± SD of a single experiment performed in triplicate, all results were reproducible in three independent experiments. ** P < 0.01. (F) Flow cytometric analysis. VPA-induced upregulation of MICA and MICB protein expression on the cell surface were attenuated in PI3KCA-knockdown cells. MFI, mean fluorescence intensity; * P < 0.05; ** P < 0.01. (G) LDH release assay. The VPA-induced susceptibility of cancer cells to NK cell-mediated cell lysis was reduced in PI3KCA-knockdown cells. Data are mean ± SD of a single experiment performed in triplicate, all results were reproducible in three independent experiments. ** P < 0.01 and * P < 0.05 for NC vs. siR2; ▲▲ P < 0.01 and ▲ P < 0.05 for NC vs. siR3. siR2, PI3KCA siR sequence 2; siR3, PI3KCA siR sequence 3.