ABSTRACT: About 10% of all NSCLC patients respond to gefitnib treatment and all of these patients will acquire resistance to the EGFR TKI. We used microarray to look at global gene expression changes in untreated cells vs gefitinib treated cells to identify key characters for the acquisition of resistance. NSCLC cells, H322c, were cultured 4 days in media containing 1μM gefitinib or 0.1% DMSO as a control. On day 4, RNA was extracted and submitted for microarray hybridization.
Project description:About 10% of all NSCLC patients respond to gefitnib treatment and all of these patients will acquire resistance to the EGFR TKI. We used microarray to look at global gene expression changes in untreated cells vs gefitinib treated cells to identify key characters for the acquisition of resistance.
Project description:About 10% of all NSCLC patients respond to gefitnib treatment and all of these patients will acquire resistance to the EGFR TKI. We used microarray to look at global gene expression changes in untreated cells vs gefitinib treated cells to identify key characters for the acquisition of resistance. NSCLC cells, H322c, were cultured 4 days in media containing 1?M gefitinib or 0.1% DMSO as a control. On day 4, RNA was extracted and submitted for microarray hybridization.
Project description:Gefitinib (Gef) provides clinical benefits to non-small cell lung cancer (NSCLC) patients with activating EGFR mutations. However, acquired resistance (AR) is a major obstacle to effective Gef therapy. This study demonstrated that resveratrol (Res) could synergize with Gef to inhibit the proliferation of Gef-resistant NSCLC cells. The underlying mechanisms of synergism were investigated, and the results showed that cotreatment with Gef and Res could inhibit EGFR phosphorylation by increasing intracellular Gef accumulation through the impairment of Gef elimination from PC9/G cells. Consistently, CYP1A1 and ABCG2 expression were inhibited. Meanwhile, the cotreatment significantly induced cell apoptosis, autophagy, cell cycle arrest and senescence accompanied by increased expression of cleaved caspase-3, LC3B-II, p53 and p21. Further studies revealed that autophagy inhibition enhanced apoptosis and abrogated senescence while apoptosis inhibition had no notable effect on cell autophagy and senescence during cotreatment with Gef and Res. These results indicated that in addition to apoptosis, senescence promoted by autophagy contributes to the antiproliferation effect of combined Gef and Res on PC9/G cells. In conclusion, combined treatment with Gef and Res may represent a rational strategy to overcome AR in NSCLC cells.
Project description:Eleven NSCLC cell lines with widely divergent gefitinib sensitivities were compared using gene expression. Genes associated with gefitinib response were used to classify additional NSCLC lines with unknown gefitnib sensitivity. A subset of the test set data was tested for gefitinib sensitivity, and results correlated strongly with the gene expression-based predictions All eleven training set lines, and seven test set lines had both HGU133A and B chips done, while other test set lines had only HGU133As. Keywords: cell response comparison
Project description:Lung cancer has the highest incidence and mortality rates among the malignant tumor types worldwide. Platinum?based chemotherapy is the main treatment for advanced non?small?cell lung cancer (NSCLC), and epidermal growth factor receptor?tyrosine kinase inhibitors (EGFR?TKIs) have greatly improved the survival of patients with EGFR?sensitive mutations. However, there is no standard therapy for treating patients who are EGFR?TKI resistant. Combining EGFR?TKIs and platinum?based chemotherapy is the most popular strategy in the clinical practice. However, the synergistic mechanism between EGFR?TKIs and platinum remains unknown. Therefore, the aim of the present study was to determine the synergistic mechanism of gefitinib (an EGFR?TKI) and cisplatin (a main platinum?based drug). MTT assay, apoptosis analysis, tumorsphere formation and an orthotropic xenograft mouse model were used to examine the combination effects of gefitinib and cisplatin on NSCLC. Co?immunoprecipitation and immunofluorescence were used to identify the underlying mechanism. It was found that gefitinib could selectively inhibit EGFR from entering the nucleus, decrease DNA?PK activity and enhance the cytotoxicity of cisplatin on NSCLC. Collectively, the results suggested that inhibition of DNA?dependent protein kinase by gefitinib may be due to the synergistic mechanism between gefitinib and cisplatin. Thus, the present study provides a novel insight into potential biomarkers for the selection of combination therapy of gefitinib and cisplatin.
Project description:Introduction: G-protein coupled receptor 30 (GPR30) is associated with cell metastasis and drug resistance in many different cancer cells. The present study aimed to reveal the sensitivity of GPR30 to gefitinib in non-small cell lung cancer (NSCLC) cells.Methods: Cell viability and proliferation were detected using cell counting kit 8 and 5-ethynyl-2'-deoxyuridine assays, respectively. Western blotting and quantitative real-time reverse transcription PCR were used to detect GPR30 or epithelial-mesenchyme transition (EMT)-related mRNA and protein expression.Results: The results showed that GPR30 expression is associated with gefitinib sensitivity. G15, as a GPR30 antagonist, reduced GPR30 expression. We chose the maximum concentration of G15 with minimal cytotoxicity to detect cell viability after combined treatment with gefitinib in NSCLC cells, which indicated that G15 could increase sensitivity to gefitinib. However, the effect of G15 on gefitinib sensitivity disappeared after treatment with a small interfering RNA targeting GPR30. Further research showed that G15 or GPR30 siRNA treatment could upregulate E-cadherin and downregulate vimentin levels.Conclusion: Taken together, these data suggested that G15 could enhance NSCLC sensitivity to gefitinib by inhibition of GPR30 and EMT.
Project description:MET overactivation is one of the crucial reasons for tyrosine kinase inhibitor (TKI) resistance, but the mechanisms are not wholly clear. Here, COX2, TOPK, and MET expression were examined in EGFR-activating mutated NSCLC by immunohistochemical (IHC) analysis. The relationship between COX2, TOPK, and MET was explored in vitro and ex vivo. In addition, the inhibition of HCC827GR cell growth by combining COX2 inhibitor (celecoxib), TOPK inhibitor (pantoprazole), and gefitinib was verified ex vivo and in vivo. We found that COX2 and TOPK were highly expressed in EGFR-activating mutated NSCLC and the progression-free survival (PFS) of triple-positive (COX2, MET, and TOPK) patients was shorter than that of triple-negative patients. Then, we observed that the COX2-TXA2 signaling pathway modulated MET through AP-1, resulting in an inhibition of apoptosis in gefitinib-resistant cells. Moreover, we demonstrated that MET could phosphorylate TOPK at Tyr74 and then prevent apoptosis in gefitinib-resistant cells. In line with these findings, the combination of celecoxib, pantoprazole, and gefitinib could induce apoptosis in gefitinib-resistant cells and inhibit tumor growth ex vivo and in vivo. Our work reveals a novel COX2/MET/TOPK signaling axis that can prevent apoptosis in gefitinib-resistant cells and suggests that a triple combination of FDA-approved drugs would provide a low-cost and practical strategy to overcome gefitinib resistance.
Project description:We have employed a transcriptomic approach to find a molecular target that could compensate for the loss of EGFR signaling in NSCLC cell lines with acquired resistance to gefitinib with an EMT phenotype.
Project description:We aimed to explore the molecular substrate underlying EGFR-TKI resistance and investigate the effects of N-acetylcysteine (NAC) on reversing EGFR-TKI resistance. In the current research, the effects of NAC in combination with gefitinib on reversing gefitinib resistance were examined using CCK-8 assay, combination index (CI) method, matrigel invasion assay, wound-healing assay, flow cytometry, western blot, and quantitative real-time PCR (qRT-PCR). CCK8 assay showed that NAC plus gefitinib combination overcame EGFR-TKI resistance in non-small cell lung cancer (NSCLC) cells by lowering the value of half maximal inhibitory concentration (IC50). CI calculations demonstrated a synergistic effect between the two drugs (CI < 1). Matrigel invasion assay and wound healing assay demonstrated a decrease in migration and invasion ability of PC-9/GR cells after NAC and gefitinib treatment. Flow cytometry displayed enhanced apoptosis in the combination group. Western blot and qRT-PCR revealed that increased E-cadherin and decreased vimentin in the combination group. When PP2 was administered with gefitinib, the same effects were seen. Our findings suggest that NAC could restore the sensitivity of gefitinib-resistant NSCLC cells to gefitinib via suppressing Src activation and reversing epithelial-mesenchymal transition.
Project description:Non-small cell lung cancer (NSCLC) patients with EGFR mutations initially respond well to EGFR tyrosine kinase inhibitors (TKIs) but eventually exhibit acquired or innate resistance to the therapies typically due to gene mutations, such as EGFR T790M mutation or a second mutation in the downstream pathways of EGFR. Importantly, a significant portion of NSCLC patients shows TKI resistance without any known mechanisms, calling more comprehensive studies to reveal the underlying mechanisms. Here, we investigated a synthetic lethality with gefitinib using a genome-wide RNAi screen in TKI-resistant EGFR-mutant NSCLC cells, and identified RNF25 as a novel factor related to gefitinib resistance. Depletion of RNF25 expression substantially sensitized NSCLC cells to gefitinib treatment, while forced expression of RNF25 augmented gefitinib resistance in sensitive cells. We demonstrated that RNF25 mediates NF-κB activation in gefitinib-treated cells, which, in turn, induces reactivation of ERK signal to cause the drug resistance. We identified that the ERK reactivation occurs via the function of cytokines, such as IL-6, whose expression is transcriptionally induced in a gefitinib-dependent manner by RNF25-mediated NF-κB signals. These results suggest that RNF25 plays an essential role in gefitinib resistance of NSCLC by mediating cross-talk between NF-κB and ERK pathways, and provide a novel target for the combination therapy to overcome TKI resistance of NSCLC.