Abstract
Trastuzumab has been successfully employed for the treatment of Her-2-positive gastric cancer. However, there are problems with both primary and secondary resistance to trastuzumab. In this study, we employed the human gastric carcinoma cell line NCI-N87 with high Her-2 expression to create trastuzumab-resistant NCI-N87/TR cells by stepwise exposure to increasing doses of trastuzumab. Western blotting and Real-time PCR were conducted to detect protein and gene levels. Compared with NCI-N87 cells, the expression of P-IGF-1R and P-AKT proteins was significantly increased in NCI-N87/TR cells (both P = 0.000), while PTEN gene and protein expression showed a significant decrease (both P = 0.000). In addition, mutations of the PTEN gene were detected at exons 5, 7, and 8. The sensitivity of NCI-N87/TR cells to trastuzumab was increased by transfection with the PTEN gene, or by incubation with a PI3K inhibitor (LY294002) or an IGF-IR inhibitor (AG1024), as well as siRNA targeting PI3K p110 or IGF-1R. Taken together, our findings showed that activation of the PI3K-AKT signaling pathway was one of the major mechanisms leading to resistance of NCI-N87/TR gastric cancer cells to trastuzumab, which was probably associated with PTEN gene down-regulation and mutation, as well as with over-activity of the IGF-1R signaling pathway.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Antineoplastic Agents / pharmacology
-
Blotting, Western
-
Cell Line, Tumor
-
Cell Survival / drug effects
-
Cell Survival / genetics
-
Chromones / pharmacology
-
Class Ia Phosphatidylinositol 3-Kinase / genetics
-
Class Ia Phosphatidylinositol 3-Kinase / metabolism
-
Dose-Response Relationship, Drug
-
Drug Resistance, Neoplasm / drug effects*
-
Drug Resistance, Neoplasm / genetics*
-
Enzyme Inhibitors / pharmacology
-
Gene Expression Regulation, Neoplastic / drug effects*
-
Humans
-
Morpholines / pharmacology
-
PTEN Phosphohydrolase / genetics
-
PTEN Phosphohydrolase / metabolism
-
Phosphoinositide-3 Kinase Inhibitors
-
Proto-Oncogene Proteins c-akt / genetics
-
Proto-Oncogene Proteins c-akt / metabolism
-
RNA Interference
-
Receptor, IGF Type 1 / antagonists & inhibitors
-
Receptor, IGF Type 1 / genetics
-
Receptor, IGF Type 1 / metabolism
-
Reverse Transcriptase Polymerase Chain Reaction
-
Signal Transduction / drug effects
-
Signal Transduction / genetics
-
Stomach Neoplasms / genetics
-
Stomach Neoplasms / metabolism
-
Stomach Neoplasms / pathology
-
Trastuzumab / pharmacology*
-
Tyrphostins / pharmacology
Substances
-
Antineoplastic Agents
-
Chromones
-
Enzyme Inhibitors
-
Morpholines
-
Phosphoinositide-3 Kinase Inhibitors
-
Tyrphostins
-
tyrphostin AG 1024
-
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
-
Class Ia Phosphatidylinositol 3-Kinase
-
Receptor, IGF Type 1
-
Proto-Oncogene Proteins c-akt
-
PTEN Phosphohydrolase
-
Trastuzumab