Fig. 2.

Cooperative effect of Src and EGFR inhibition with gemcitabine on cell signaling. BxPC3 vector control-shRNA, Src shRNA and EGFR shRNA cells were investigated with dasatinib (5 nmol/L) or erlotinib (100 nmol/L) for anti-proliferative activity by MTT assay and anti-invasion by matrigel invasion assay. Significantly reduction in (A) cell viability and (B) invasion was seen with combined targeting of Src and EGFR signalling. Individual data point represents the mean ± SD of three independent wells. *p<0.05; **p<0.01; ***p<0.001. (C) BxPC3 cells were treated with dasatinib (5 nmol/L) and/or gemcitabine (30 nmol/L) and/or erlotinib (100 nmol/L); PANC1 cells were treated with dasatinib (25 nmol/L) and/or gemcitabine (75 nmol/L) and/or erlotinib (500 nmol/L) for 12 h, lysed, and analyzed by Western blotting with indicated antibodies. At doses that had minimal effects on inhibition of any signaling pathway, only the triple combination of dasatinib, erlotinib and gemcitabine showed inhibition of pSrc, pEGFR, pFAK, pAKT, pSTAT3, pERK, pJNK or pMAPK. Furthermore, only this triple combination overcomes constitutive activation of STAT3-mediating signaling seen in PANC1 cells. Blots are representative of at least two separate experiments with similar results.