Resistance to gefitinib in malignant melanoma cells is related to increased expression of Met and the insulin receptor and sustained Akt signaling
2012 (English)Manuscript (preprint) (Other academic)
Background: Acquired resistance to cancer therapy, including targeted therapies such as epidermal growth factor receptor (ErbB) tyrosine kinase inhibitors (TKIs), constitutes a major clinical problem in treating patients with malignant disease. Several drug resistance mechanisms for ErbB1 TKIs involving abnormal activation of growth factor receptors or activation of intracellular signaling pathways have been discovered. ErbB TKIs have recently been shown to inhibit growth in melanoma cells. This study was undertaken to develop a gefitinib-resistant melanoma cell line in order to find any resistance mechanism to gefitinib in melanoma cells lacking activating mutation in BRAF or NRAS.
Material and methods: A malignant melanoma cell line (RaH5) was made resistant to the ErbB1 TKI gefitinib by continuous culture with stepwise increasing concentrations of the drug up to 10 μM. The phosphorylation status of 42 different human receptor tyrosine kinases was screened in a protein array in resistant (RaH5ZDR) and wild-type RaH5 cells treated with or without gefitinib. The PI3K, MAPK and Stat3 signaling pathways were studied in an analogous way by Western blot analysis; 2-D gel electrophoresis was performed to determine other potential proteins involved in gefitinib resistance in RaH5 cells. In addition, the effect of the pan-ErbB TKI canertinib on gefitinib-resistant cells was investigated.
Results: Protein array experiments showed that only Met and the insulin receptor (IR) exhibited substantially increased activation in RaH5ZDR cells as compared to their nonresistant counterparts. Interestingly, following gefitinib treatment ErbB2 and ErbB3 receptor signaling in resistant cells were equally well suppressed as in non-resistant cells. However, downstream Akt and Erk1/2 phosphorylation was inhibited to a greater extent in non-resistant RaH5 cells.
Conclusion: Resistance to gefitinib in RaH5 cells appears to be related to an increased expression of Met and IR and linked to a more persistent signaling through Akt and Erk1/2. However, additional studies are required to further elucidate the resistance to gefitinib in our experimental system.
Place, publisher, year, edition, pages
Malignant melanoma, gefitinib, canertinib, gefitinib resistance, ErbB, Erk1/2, Akt, Stat3, Met, IR
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-85664OAI: oai:DiVA.org:liu-85664DiVA: diva2:572432