Gefitinib Inhibits the Proliferation of Pancreatic Cancer Cells via Cell Cycle Arrest

Department of Biochemistry and Molecular Biology, Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, People's Republic of China.
The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology (Impact Factor: 1.54). 08/2009; 292(8):1122-7. DOI: 10.1002/ar.20938
Source: PubMed


High expression of the epidermal growth factor receptor (EGFR) has been implicated in the development of pancreatic cancer. Gefitinib is an orally active and selective EGFR-TKI (EGFR-tyrosine kinase inhibitor) that blocks signal transduction pathways responsible for the proliferation and survival of cancer cells, and other host-dependent processes promoting cancer growth. This study investigated the anticancer effect of gefitinib on human pancreatic cancer cells and the molecular mechanism involved. We first evaluated the effect of gefitinib on cell proliferation with MTT assay and the results demonstrated that gefitinib significantly inhibited the proliferation of pancreatic cancer cells. Flow cytometric analysis showed that gefitinib induced a delay in cell cycle progression and a G0/G1 arrest together with a G2/M block; these were associated with increased expression of p27(Kip1) cyclin-dependent kinase inhibitor combined with decreased expression of aurora B. Besides, luciferase reporter assay revealed that transcriptional mechanism was responsible for the down-regulation of aurora B protein by gefitinib. Overall, the results suggest a mechanistic connection among these events to provide new insights into the mechanism underlying the antiproliferative effect of gefitinib on pancreatic cancer and supplement a theory basis of gefitinib in clinical treatment of pancreatic cancer.

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Available from: Yunxia Zhu, Sep 29, 2015
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    • "We showed that icotinib triggered cell cycle G1 phase arrest in HCC827 cells. Gefitinib induces significant G1/S blockade in ER-positive breast cells [17], G0/G1 arrest together with G2/M block in pancreatic cancer cells [18], and block cell cycle progression at G1 phase in sensitized hepatocellular carcinoma cells [19]. This may be attributed to the different regulatory mechanism of cell cycle progress in different types of tumor cells. "
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    ABSTRACT: Epidermal growth factor receptor (EGFR) is one of the most promising targets for non-small-cell lung cancer (NSCLC). Icotinib, a highly selective EGFR tyrosine kinase inhibitor (EGFR-TKI), has shown promising clinical efficacy and safety in patients with NSCLC. The exact molecular mechanism of icotinib remains unclear. In this study, we first investigated the antiproliferative effect of icotinib on NSCLC cells. Icotinib significantly inhibited proliferation of the EGFR-mutated lung cancer HCC827 cells. The IC50 values at 48 and 72 h were 0.67 and 0.07 μ M, respectively. Flow cytometric analysis showed that icotinib caused the G1 phase arrest and increased the rate of apoptosis in HCC827 cells. The levels of cyclin D1 and cyclin A2 were decreased. The apoptotic process was associated with activation of caspase-3, -8, and poly(ADP-ribose) polymerase (PARP). Further study revealed that icotinib inhibited phosphorylation of EGFR, Akt, and extracellular signal-regulated kinase. In addition, icotinib upregulated ubiquitin ligase Cbl-b expression. These observations suggest that icotinib-induced upregulation of Cbl-b is responsible, at least in part, for the antitumor effect of icotinib via the inhibition of phosphoinositide 3-kinase (PI3K)/Akt and mitogen-activated protein kinase pathways in EGFR-mutated NSCLC cells.
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    • "These pathways influence the expression, activity, or subcellular localization of key components of the cell-cycle machinery such as cyclins, CDKs, and CDK inhibitors, leading to the appropriate activation of E2F-1 transcription factors. Several agents have been described that regulate the G1 traverse and transition into the S-phase in pancreatic cancer cells, and p27Kip1 has been reported to be increased by these agents [22], [23], [24], [25], [26]. We therefore determined the kinetics of p27Kip1 levels and RAF-MEK-ERK pathway activity in pancreatic cancer cells and in HPDE6 C7 cells exposed to δ-tocotrienol. "
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    ABSTRACT: Vitamin E δ-tocotrienol has been shown to have antitumor activity, but the precise molecular mechanism by which it inhibits the proliferation of cancer cells remains unclear. Here, we demonstrated that δ-tocotrienol exerted significant cell growth inhibition pancreatic ductal cancer (PDCA) cells without affecting normal human pancreatic ductal epithelial cell growth. We also showed that δ-tocotrienol-induced growth inhibition occurred concomitantly with G(1) cell-cycle arrest and increased p27(Kip1) nuclear accumulation. This finding is significant considering that loss of nuclear p27(Kip1) expression is a well-established adverse prognostic factor in PDCA. Furthermore, δ-tocotrienol inactivated RAF-MEK-ERK signaling, a pathway known to suppress p27(Kip1) expression. To determine whether p27(Kip1) induction is required for δ-tocotrienol inhibition of PDCA cell proliferation, we stably silenced the CDKN1B gene, encoding p27(Kip1), in MIAPaCa-2 PDCA cells and demonstrated that p27(Kip1) silencing suppressed cell-cycle arrest induced by δ-tocotrienol. Furthermore, δ-tocotrienol induced p27(Kip1) mRNA expression but not its protein degradation. p27(Kip1) gene promoter activity was induced by δ-tocotrienol through the promoter's E2F-1 binding site, and this activity was attenuated by E2F-1 depletion using E2F-1 small interfering RNA. Finally, decreased proliferation, mediated by Ki67 and p27(Kip1) expression by δ-tocotrienol, was confirmed in vivo in a nude mouse xenograft pancreatic cancer model. Our findings reveal a new mechanism, dependent on p27(Kip1) induction, by which δ-tocotrienol can inhibit proliferation in PDCA cells, providing a new rationale for p27(Kip1) as a biomarker for δ-tocotrienol efficacy in pancreatic cancer prevention and therapy.
    Full-text · Article · Feb 2013 · PLoS ONE
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    • "This is consistent with the findings from Gaikwad et al. (2009) who have shown a decreased expression of MDR- 1 mRNA with combinative treatment of gefitinib and cisplatin, when compared to monotherapy of cisplatin in endometrial cancer cell lines. Interestingly, monotherapy with gefitinib (5 lM) did not influence the pancreatic carcinoma cells survival ratio (Zhou et al., 2009), but combination of gefitinib and gemcitabine showed synergistic effect on cells survival, as compared to gemcitabine monotherapy. This explains the phenomenon of gefitinib decreasing the MDR proteins expression and facilitating the retention of chemotherapeutic agents in cells, which killed the cells or inhibited the proliferation of cells. "
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    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. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
    Preview · Article · Dec 2012 · The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology
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