Receptor proteins were precipitated from mobile lysates with a commercial antibody against HER2 or with a non commercial antibody against HER1/EGFR. Lapatinib blocks EGFR and HER2 service We’ve pan Aurora Kinase inhibitor shown previously that both lapatinib and erlotinib, an EGFR selective tyrosine kinase inhibitor, prevent the growth agar soft of many pancreatic cancer cell lines1. . Because EGFR 5 inhibition has been proven to radiosensitize other cancers, including head and neck squamous cell carcinomas and breast cancer, we sought to find out whether these substances could also radiosensitize pancreatic cancer cells and whether this radiosensitization correlated with EGFR and HER2 expression. We first evaluated by qRT PCR the relative expression levels of all four members of the family of receptors among a panel of four pancreatic cancer cell lines. EGFR levels were 10-17 fold greater in the PANC 1 and T3M4 cells relative to that seen in the Capan 2 and MIA PaCa 2 cells, while HER2 levels were similar among all four lines. Appearance of HER3, a member of family that lacks kinase activity, was approximately 10-fold higher in the T3M4 cells and Capan 2. HER4, the last relative, had really low mRNA expression levels across all four cell lines. All cell lines showed an anti proliferative effect in response to increasing concentrations of both lapatinib and erlotinib. The dual EGFR/HER2 messenger RNA (mRNA) inhibitor lapatinib demonstrated improved growth inhibitory activity in comparison to erlotinib in 2 and MIA PaCa 2 cell lines, a finding consistent with low levels of EGFR mRNA in these cell lines. T3M4 cells and PANC 1 had higher degrees of EGFR than HER2 expression, and exhibited equivalent growth inhibition by erlotinib and lapatinib. To show that lapatinib blocks ligand stimulated EGFR and HER2 activation in our pancreatic cells activation of receptors was assessed by immunoprecipitation adopted by western blot analysis. In keeping with what we Bicalutamide Cosudex and others have previously reported using in vitro, in vivo, and individual samples and reviewed in, lapatinib blocked activation of both EGFR and HER2 in every four pancreatic cell lines. . Pancreatic cancer cell lines harboring K ras mutations are resistant to lapatinib mediated radiosensitization Because of the improved anti proliferative and ligand triggered receptor inhibition of lapatinib inside the examined cell lines, we made a decision to examine whether lapatinib could radiosensitize pancreatic cancer cells. Clonogenic success assays were performed on our panel of cells that were both treated with lapatinib or vehicle alone for your 2 hours previous and 2 hours after irradiation. We chose this short duration of drug therapy since the clonogenic survival and cell cycle distribution of non irradiated cell lines that were pretreated in this style with either lapatinib or DMSO control weren’t statistically different, suggesting that the 4 hour exposure to lapatinib didn’t radiosensitize cells only by inhibiting proliferation or by redistributing cells to a more radiosensitive phase of the cell cycle.