Comparison of receptor tyrosine kinase (RTK) family gene expression between normoxic cells and hypoxia-induced gefitinib resistant clones
ABSTRACT: In this study, we explored the mechanisms of hypoxia-induced EGFR TKI resistance in non-small cell lung cancer (NSCLC) harbored activating EGFR mutation. The NSCLC cell lines were exposed to normorxia or 1% oxygen for 4 weeks, and then we tested EGFR TKI sensitivity in normoxic and hypoxic NSCLC cell lines. In this microarray experiment, we used normoxic HCC827 and hypoxia-induced gefitinib resistant clones, C2-3 and C2-10. Those clones were selected with gefitinib treatment after the HCC827 were exposed to 1% oxygen for 4 weeks, and the HCC827 C2-3 and C2-10 clones were selected at random for this study.
Project description:In this study, we explored the mechanisms of hypoxia-induced EGFR TKI resistance in non-small cell lung cancer (NSCLC) harbored activating EGFR mutation. The NSCLC cell lines were exposed to normorxia or 1% oxygen for 4 weeks, and then we tested EGFR TKI sensitivity in normoxic and hypoxic NSCLC cell lines. In this microarray experiment, we used normoxic HCC827 and hypoxia-induced gefitinib resistant clones, C2-3 and C2-10. Those clones were selected with gefitinib treatment after the HCC827 were exposed to 1% oxygen for 4 weeks, and the HCC827 C2-3 and C2-10 clones were selected at random for this study.
Project description:Accumulating evidence indicates that a small population of cancer stem cells (CSCs) is involved in intrinsic resistance to cancer treatment. The hypoxic microenvironment is an important stem cell niche that promotes the persistence of CSCs in tumors. Our aim here was to elucidate the role of hypoxia and CSCs in the resistance to gefitinib in non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutation. NSCLC cell lines, PC9 and HCC827, which express the EGFR exon 19 deletion mutations, were exposed to high concentration of gefitinib under normoxic or hypoxic conditions. Seven days after gefitinib exposure, a small fraction of viable cells were detected, and these were referred to as "gefitinib-resistant persisters" (GRPs). CD133, Oct4, Sox2, Nanog, CXCR4, and ALDH1A1-all genes involved in stemness-were highly expressed in GRPs in PC9 and HCC827 cells, and PC9 GRPs exhibited a high potential for tumorigenicity in vivo. The expression of insulin-like growth factor 1 (IGF1) was also upregulated and IGF1 receptor (IGF1R) was activated on GRPs. Importantly, hypoxic exposure significantly increased sphere formation, reflecting the self-renewal capability, and the population of CD133- and Oct4-positive GRPs. Additionally, hypoxia upregulated IGF1 expression through hypoxia-inducible factor 1? (HIF1?), and markedly promoted the activation of IGF1R on GRPs. Knockdown of IGF1 expression significantly reduced phosphorylated IGF1R-expressing GRPs under hypoxic conditions. Finally, inhibition of HIF1? or IGF1R by specific inhibitors significantly decreased the population of CD133- and Oct4-positive GRPs, which were increased by hypoxia in PC9 and HCC827 cells. Collectively, these findings suggest that hypoxia increased the population of lung CSCs resistant to gefitinib in EGFR mutation-positive NSCLC by activating IGF1R. Targeting the IGF1R pathway may be a promising strategy for overcoming gefitinib resistance in EGFR mutation-positive NSCLC induced by lung CSCs and microenvironment factors such as tumor hypoxia.
Project description:Somatic mutations in the epidermal growth factor receptor (EGFR) gene, such as exon 19 deletion mutations, are important factors in determining therapeutic responses to gefitinib in non-small-cell lung cancer (NSCLC). However, some patients have activating mutations in EGFR and show poor responses to gefitinib. In this study, we examined three NSCLC cell lines, HCC827, PC9, and HCC2935, that expressed an EGFR exon 19 deletion mutation. All cells expressed mutant EGFR, but the PC9 and HCC2935 cells also expressed wild-type EGFR. The HCC827 cells were highly sensitive to gefitinib under both normoxia and hypoxia. However, the PC9 and HCC2935 cells were more resistant to gefitinib under hypoxic conditions compared to normoxia. Phosphorylation of EGFR and ERK was suppressed with gefitinib treatment to a lesser extent under hypoxia. The expression of transforming growth factor-? (TGF?) was dramatically upregulated under hypoxia, and the knockdown of TGF? or hypoxia-inducible factor-1? (HIF1?) reversed the resistance to gefitinib in hypoxic PC9 and HCC2935 cells. Finally, introduction of the wild-type EGFR gene into the HCC827 cells caused resistance to gefitinib under hypoxia. This phenomenon was also reversed by the knockdown of TGF? or HIF1?. Our results indicate that hypoxia causes gefitinib resistance in EGFR-mutant NSCLC through the activation of wild-type EGFR mediated by the upregulation of TGF?. The presence of wild-type and mutant EGFR along with tumor hypoxia are important factors that should be considered when treating NSCLC patients with gefitinib.
Project description:Background: The efficacy of an EGFR-targeted treatment strategy for non-small cell lung cancer (NSCLC) is reduced by drug resistance. IL-22 enhances tumor growth and induces chemotherapy resistance in human lung cancer cells. The present study elucidated the IL-22-induced mechanism underlying EGFR-tyrosine kinase inhibitor (TKI) resistance in NSCLC. Methods: The plasma and tissues of patients who received EGFR-TKIs were utilized to determine the association between IL-22 expression and gefitinib efficacy. The IL-22 effect on the EGFR/ERK/AKT pathways in NSCLC HCC827 and PC-9 cells was determined using the CCK-8 assay, western blot, and flow cytometric analysis. A PC-9 xenograft model of IL-22 exposure was established. Gefitinib was administered to mice in combination with IL-22 or vehicle. Results: We showed that IL-22 expression was higher in the EGFR-TKI-resistant group compared to EGFR-TKI-sensitive group. IL-22 expression was associated with EGFR-TKI efficacy in plasma. Additional treatment of IL-22 induced gefitinib resistance and reduced apoptosis in PC-9 and HCC827 cell lines. Furthermore, we showed that the effects of IL-22 attributed to p-ERK, p-EGFR, and p-AKT up-regulation. IL-22 neutralizing antibody completely abrogated the effects of IL-22 on apoptosis and AKT/EGFR/ERK signaling. Finally, we showed that IL-22 enhanced tumor growth and induced gefitinib resistance in the PC-9 xenograft model. Moreover, compared with gefitinib alone, the combination of IL-22 and gefitinib led to an increase in Ki67-positive staining and a reduction in TUNEL staining. Conclusions: Our findings indicate that IL-22 plays a role in tumor progression and EGFR-TKI resistance in NSCLC. Thus, IL-22 might serve as a novel biomarker to overcome resistance of EGFR-TKI.
Project description:Analysis of gefitinib short-term resistance at gene expression level. The hyposthesis tested in the present study was that short-term resistance towards gefitinib in NSCLC cells influences pathways that associates with resistance towards EGFR-TKI treatment. Results provide important information of the response of EGFR mutant NSCLC cells to gefitinib and also to resistance towards gefitinib resistance, up-or down-regulated specific resistance pathways and cellular functions. Total RNA obtained from HCC827 cell line (n=3), co-cultured HCC827 (with MRC-5 cells)(n=3), gefitinib treated (0.5µM) HCC827 (n=3), and co-cultured (MRC-5) + gefitinib treated HCC827 cells (n=3) for 48h after gefitinib treatment
Project description:BACKGROUND:Although many studies have defined mechanisms of resistance to EGFR-TKIs, acquired resistance remains the major limitation of monotherapy with EGFR-TKIs. METHODS:Cell viability was analyzed using a Cell Counting Kit-8 (CCK-8) assay. EGFR T790M mutation was sequenced on a HiSeq 4000 platform. mRNAs from HCC827 and HCC827 gefitinib-resistant (GR) cells were analyzed by genome analyzer-based deep sequencing. The effect of anlotinib on apoptosis and cell cycle arrest of HCC827 GR was detected by fluorescence-activated cell sorting (FACS) analysis. A mouse xenograft model was used to assess the effect of anlotinib on HCC827 GR cells. RESULTS:The T790M mutation was found in the PC-9 GR cell line but not in the HCC827 GR cell line. Anlotinib could suppress the growth of HCC827 GR cells by inhibiting FGFR1 in vitro and in a mouse xenograft model. Moreover, FGFR1 was overexpressed in HCC827 GR cells, and the knockdown of FGFR1 reversed gefitinib resistance in HCC827 GR cells. Furthermore, anlotinib induced apoptosis and cell cycle arrest in HCC827 GR cells by increasing the activity of Caspase-3. CONCLUSIONS:FGFR1 overexpression could be the mechanism of EGFR-TKI acquired resistance and anlotinib can suppresse the growth of EGFR-TKI-resistant NSCLC cells without T790M mutation.
Project description:To identify novel miRNAs involved in acquired EGFR TKI resistance in NSCLC, genome-wide miRNA expression analysis was performed in gefitinib-resistant sub-cell lines and gefitinib-sensitive parental cell lines. Overall design: Gefitinib-resistant sub-cell lines were generated by growing gefitinib-sensitive EGFR-mutant NSCLC cell lines (PC9 and HCC827) in increasing concentrations of gefitinib to a final concentration of 10 uM up to 6 months.
Project description:Tyrosine kinase inhibitors (TKIs) are currently the first-line treatment for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. These patients receive platinum-based chemotherapy as the second-line treatment after they develop resistance to TKIs. Many patients regain sensitivity to the TKIs used in the first-line treatment after the failure of chemotherapy. However, the molecular mechanism for the regain of TKI sensitivity is largely unknown. In this study, we established gefitinib-resistant PC9 and HCC827 cell lines, which did not harbor the EGFR T790M mutation and MET amplification but exhibited the epithelial-mesenchymal transition (EMT) phenotype. Overexpression of EMT inducers, Snail or Slug, in the parental lines promoted their resistance to gefitinib. The gefitinib-resistant cell lines regained their sensitivity to gefitinib and displayed reverse EMT phenotypes after long-term culture in gefitinib-free culture medium. Blockage of reverse EMT by stable expression of Snail or Slug prevented the regain of TKI sensitivity. In conclusion, reverse EMT is one of the major mechanisms for the regain of TKI sensitivity in TKI-resistant NSCLC cells, suggesting that the development of small molecules targeting the EMT process may prolong the efficacy of TKIs in NSCLC patients with EGFR mutations.
Project description:Chemotherapy combined concurrently with TKIs produced a negative interaction and failed to improve survival when compared with chemotherapy or TKIs alone in the treatment of non-small cell lung cancer (NSCLC). The present study investigated the sequence-dependent interaction between paclitaxel and gefitinib and clarified the underlying mechanism.The effects on cell proliferation, EGFR signaling pathway, and TGF? expression were evaluated in a panel of human NSCLC cell lines harboring EGFR mutations with three different combination sequences: sequential treatment with paclitaxel followed by gefitinib (T?G), sequential treatment with gefitinib followed by paclitaxel (G?T), or concomitant treatment (T + G).The sequence-dependent anti-proliferative effects differed between EGFR-TKI-sensitive and -resistant cell lines carrying EGFR mutations. A synergistic anti-proliferative activity was obtained with paclitaxel treatment followed by gefitinib in all cell lines, with mean CI values of 0.63 in Hcc827, 0.54 in PC-9, 0.81 in PC-9/GR, and 0.77 in H1650 cells for the T?G sequence. The mean CI values for the G?T sequence were 1.29 in Hcc827, 1.16 in PC-9, 1.52 in PC-9/GR, and 1.5 in H1650 cells. The mean CI values for T+G concomitant treatment were 0.88 in Hcc827, 0.91 in PC-9, 1.05 in PC-9/GR, and 1.18 in H1650 cells. Paclitaxel produced a dose-dependent increase in EGFR phosphorylation. Paclitaxel significantly increased EGFR phosphorylation compared with that in untreated controls (mean differences: +50% in Hcc827, + 56% in PC-9, + 39% in PC-9/GR, and + 69% in H1650 cells; p < 0.05). The T?G sequence produced significantly greater inhibition of EGFR phosphorylation compared with the opposite sequence (mean differences: -58% in Hcc827, -38% in PC-9, -35% in PC-9/GR, and -30% in H1650 cells; p < 0.05). Addition of a neutralizing anti-TGF? antibody abolished paclitaxel-induced activation of the EGFR pathway in PC-9 and H1650 cells. Sequence-dependent TGF? expression and release are responsible for the sequence-dependent EGFR pathway modulation.The data suggest that the sequence of paclitaxel followed by gefitinib is an appropriate treatment combination for NSCLC cell lines harboring EGFR mutations. Our results provide molecular evidence to support clinical treatment strategies for patients with lung cancer.