Abstract
Pancreatic cancer is a devastating malignancy, characterized by intrinsic or acquired resistance to conventional chemotherapies. Recent evidences suggest an involvement of tyrosine kinase pathway in the regulation of multidrug resistance (MDR) protein gene expression. The aim of this study was to test whether gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor could regulate the MDR protein gene expression and sensitize the resistant cancer cells to chemotherapy. The gene expression of MDR proteins (MRP1, MRP2, MRP3, and PGP) were evaluated by quantitative RT-PCR, and expression levels of various tyrosine kinases were investigated by quantitative RT-PCR and Western blot in pancreatic cancer cell line. MTT assay was used for evaluating the effect of chemotherapeutic agents. Chemotherapeutics induced drug resistance by regulating the gene expression of MDR proteins (MRP1, MRP2, and MRP3), and increased the gene expression of RAF1/ERK and the phosphorylation of ERK in pancreatic cancer Bxpc-3 cells. Gefitinib caused an inhibition of p-ERK tyrosine kinase activation in a dose-dependent manner, and reversed gemcitabine-induced RAF1/ERK gene expression and p-ERK activation. In addition, a reversal of MDR proteins gene expression was achieved by gefitinib, which sensitized resistant cells to gemcitabine. This study demonstrated that MDR of Bxpc-3 cell is involved in the RAF1/ERK tyrosine kinase pathway. Gefitinib reverses the MDR protein gene expression and restores sensitivity of resistant cells to gemcitabine via RAF1/ERK signaling pathway. Combination of gefitinib with conventional chemotherapeutic agents may offer a new approach for the treatment of patients with pancreatic cancer.
Copyright © 2012 Wiley Periodicals, Inc.
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / drug effects
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
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Antineoplastic Agents / pharmacology*
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Blotting, Western
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Cell Line, Tumor
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Dose-Response Relationship, Drug
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Doxorubicin / pharmacology
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Drug Resistance, Multiple / drug effects*
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Drug Resistance, Multiple / genetics
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Drug Resistance, Neoplasm / drug effects*
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Drug Resistance, Neoplasm / genetics
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Enzyme Activation
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Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors*
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Gefitinib
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Gene Expression Regulation, Neoplastic
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Humans
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MAP Kinase Signaling System / drug effects*
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Multidrug Resistance-Associated Protein 2
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Multidrug Resistance-Associated Proteins / drug effects
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Multidrug Resistance-Associated Proteins / genetics
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Multidrug Resistance-Associated Proteins / metabolism
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Pancreatic Neoplasms / enzymology*
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Pancreatic Neoplasms / genetics
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Pancreatic Neoplasms / pathology
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Phosphorylation
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Protein Kinase Inhibitors / pharmacology*
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Proto-Oncogene Proteins c-raf / genetics
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Proto-Oncogene Proteins c-raf / metabolism*
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Quinazolines / pharmacology*
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RNA, Messenger / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
Substances
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ABCC2 protein, human
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ATP Binding Cassette Transporter, Subfamily B, Member 1
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Antineoplastic Agents
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Multidrug Resistance-Associated Protein 2
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Multidrug Resistance-Associated Proteins
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Protein Kinase Inhibitors
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Quinazolines
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RNA, Messenger
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multidrug resistance-associated protein 3
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Doxorubicin
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Proto-Oncogene Proteins c-raf
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Extracellular Signal-Regulated MAP Kinases
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Gefitinib
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multidrug resistance-associated protein 1