Synergistic Effect between Erlotinib and MEK Inhibitors in KRAS Wild-Type Human Pancreatic Cancer Cells

Abstract

Purpose The combination of gemcitabine plus erlotinib has shown a small but statistically significant survival advantage when compared to gemcitabine alone in patients with advanced pancreatic cancer. However, the overall survival rate with the erlotinib and gemcitabine combination is still low. In this study we sought to identify gene targets that, when inhibited, would enhance the activity of EGFR-targeted therapies in pancreatic cancer cells. Experimental Design A high-throughput RNAi screen was carried out to identify candidate genes. Selected gene hits were further confirmed and mechanisms of action were further investigated using various assays. Results Six gene hits from siRNA screening were confirmed to significantly sensitize BxPC-3 pancreatic cancer cells to erlotinib. One of the hits, MAPK1, was selected for further mechanistic studies. Combination treatments of erlotinib plus two MAP kinase kinase (MEK) inhibitors, RDEA119 and AZD6244, showed significant synergistic effect for both combinations (RDEA119-erlotinib and AZD6244-erlotinib) compared to the corresponding single drug treatments in pancreatic cancer cell lines with wild-type KRAS (BxPC-3 and Hs 700T) but not in cell lines with mutant KRAS (MIA PaCa-2 and PANC-1). The enhanced antitumor activity of the combination treatment was further verified in the BxPC-3 and MIA PaCa-2 mouse xenograft model. Examination of the MAPK signaling pathway by Western blotting indicated effective inhibition of the EGFR signaling by the drug combination in KRAS wildtype cells but not in KRAS mutant cells. Conclusions Overall, our results suggest that combination therapy of an EGFR and MEK inhibitors may have enhanced efficacy in patients with pancreatic cancer.

Amiloride sensitizes human pancreatic cancer cells to erlotinib in vitro through inhibition of the PI3K/AKT signaling pathway

“…Diep et al reported that combination treatments with erlotinib and MEK inhibitors RDEA119 or AZD6244 had significant synergistic effects only in pancreatic cancer cells with wild-type K-Ras but not in cells with mutant K-Ras [27] . Amiloride was found to potentiate the growth inhibition of erlotinib in all the selected pancreatic cancer cell lines independent of K-Ras gene status.…”

Carboxyl-terminal domain of MUC16 imparts tumorigenic and metastatic functions through nuclear translocation of JAK2 to pancreatic cancer cells

“…MiaPaCa-2 cells were established from the tumor in pancreas of a Caucasian male and harbors the most commonly found KRAS G12D oncogenic mutations observed in PC patients. Phenotypically, these cells are large with abundant cytoplasm, display aneuploidy and possess a tendency to grow in multiple layers [55,56]. T3M4 cells were established from a primary exocrine pancreatic carcinoma of a Japanese male and were also found to harbor KRAS G61H oncogenic mutations.…”

Select Biomarkers for Tumors of the Gastrointestinal Tract: Present and Future

“…Activation of RAS leads to phosphorylation of RAF, which phosphorylates MEK, and then ERK. Diep et al 149 found a synergistic effect between erlotinib and 2 MEK inhibitors, compared to monotherapy, in pancreatic cell lines with wild-type KRAS. Others 150 found that MEK inhibition in pancreatic cancer leads to EGFR-mediated PI3K activation and sensitivity to combinations of MEK and EGFR inhibitors in pancreatic adenocarcinoma cell lines.…”