Chun, P. Y. et al. Synergistic effects of gemcitabine and gefitinib in the treatment of head and neck carcinoma. Cancer Res. 66, 981-988

University of Michigan, Ann Arbor, Michigan, United States
Cancer Research (Impact Factor: 9.33). 02/2006; 66(2):981-8. DOI: 10.1158/0008-5472.CAN-05-2665
Source: PubMed


Although the combination of gemcitabine and radiation produces a high frequency of complete responses in the treatment of locally advanced head and neck cancer, substantial toxicity suggests that an improvement in the therapeutic index is required. The purpose of this study was to determine if gefitinib could improve the efficacy of gemcitabine and if drug schedule is important. We hypothesized that gemcitabine followed by gefitinib would be superior to the opposite order because of both cell cycle and growth factor signaling interactions. Using UMSCC-1 cells in vitro, we confirmed that gefitinib arrested cells in G(1) and suppressed phospho-epidermal growth factor receptor (p(Y845)EGFR) and that gemcitabine arrested cells in S phase and stimulated p(Y845)EGFR. The schedule of gemcitabine followed by gefitinib caused arrest of cells in S phase. Gefitinib suppressed gemcitabine-mediated p(Y845)EGFR stimulation. This schedule caused decreased p(S473)AKT, increased poly(ADP-ribose) polymerase cleavage, and increased apoptosis compared with gemcitabine alone. The schedule of gefitinib followed by gemcitabine also caused suppression of p(Y845)EGFR but arrested cells in G(1). This schedule in which gefitinib was used first was associated with stable levels of p(S473)AKT and minimal poly(ADP-ribose) polymerase cleavage and apoptosis. These results were reflected in experiments in nude mice bearing UMSCC-1 xenografts, in which there was greater tumor regression and apoptosis when animals received gemcitabine followed by gefitinib during the first week of therapy. These findings suggest that the schedule of gemcitabine followed by gefitinib may increase the therapeutic index over gemcitabine alone and, combined with clinical data, encourage exploration of combination of gemcitabine, EGFR inhibitors, and radiation.

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    • "Akt was phosphorylated 48 h following gemcitabine exposure but was not inhibited by gemcitabine within 72 h of exposure. Although previous studies have reported that gemcitabine downregulates EGFR (22) or inhibits the EGFR downstream signaling by inhibiting the phosphorylation of Akt (21), no such results were observed in the cell lines examined in the present study. "
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    ABSTRACT: Head and neck squamous cell carcinoma (HNSCC) may be curable with surgery, radiation and chemotherapy in its early stages. However, recurrence and metastasis often prevail following primary treatment in advanced stage cases and are associated with significant morbidity and mortality. In this study we investigated the combination therapy of gemcitabine and cetuximab for HNSCC. The UM-SCC-6 and UM-SCC-23 HNSCC cell lines were analyzed following treatment with gemcitabine and cetuximab. To determine the mechanism of action of this combination treatment, the cell cycle distributions following gemcitabine and/or cetuximab treatment were analyzed by flow cytometry and apoptosis assay. Gemcitabine and cetuximab combination treatment exerted an enhanced cytotoxic effect. The cell cycle analysis demonstrated that cells accumulated in the S phase following gemcitabine treatment and G1 arrest occurred following cetuximab treatment. An increase in sub-G1 phase cells was also observed following treatment with the two drugs. In an apoptosis assay, caspase 3/7 activity was found to be higher when administering a combination of gemcitabine and cetuximab compared to each agent administered alone. Gemcitabine and cetuximab are individually effective against HNSCC and an enhanced growth inhibitory effect may be expected when these agents are used in combination.
    Molecular and Clinical Oncology 09/2013; 1(5):918-924. DOI:10.3892/mco.2013.159
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    • "This is consistent with another in vitro study that showed a reversal of drug resistance by gefitinib in breast and lung cancer cells expressing MDR proteins (Yang et al., 2005). Although synergistic effects of gefitinib and chemotherapeutic agents have been reported in previous studies in vivo (Sirotnak et al., 2000; Chun et al., 2006), no such effect has been observed in clinical trials (Giaccone et al., 2004; Herbst et al., 2004). "
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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.
    The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 12/2012; 295(12). DOI:10.1002/ar.22552 · 1.54 Impact Factor
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    • "The molecular mechanisms behind the synergism between erlotinib and gemcitabine most likely involved the decreased p-Akt expression caused by gemcitabine. In addition, other investigators have also shown that the administration of gemcitabine first followed by gefitinib increased the therapeutic index of such therapy over that of gemcitabine alone18, and cytotoxic synergism was also found to result when cells were exposed to concurrent pemetrexed and erlotinib or sequential pemetrexed followed by erlotinib in both erlotinib-sensitive and erlotinib-resistant human non-small cell lung cancer cell lines. These studies support the importance of drug scheduling in the treatment of cancer7. "
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    ABSTRACT: A phase III clinical trial showed gemcitabine chemotherapy combined with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib significantly improved overall survival in patients with advanced pancreatic cancer. Therefore, we studied whether addition of gemcitabine to erlotinib in cancer cells having intrinsic or acquired erlotinib resistance could restore chemosensitization in these cells. We studied the synergistic effect of erlotinib and gemcitabine in EGFR-overexpressing A-431 cells with acquired erlotinib resistance and in intrinsic erlotinib-resistant triple negative breast cancer (TNBC) BT-549, MDA-MB-231 and MDA-MB-468 cell lines. Erlotinib and gemcitabine were synergistic in both parental intrinsically erlotinib-sensitive A-431 cells (combination index = 0.69 at the effective dose [ED(50)]) and in two A-431 cell pools that had acquired erlotinib resistance (combination indices = 0.63 and 0.49 at ED(50)). The synergistic effect of erlotinib and gemcitabine on cancer cells did not require sensitivity to erlotinib provided that erlotinib can inhibit EGFR. The restoration of sensitivity by gemcitabine occurred through downregulation of phosphorylated Akt (p-Akt), which suggests that PI3K-PTEN-Akt activity is important to the synergism between the two agents. In A-431 parental cells, treatment with gemcitabine followed by erlotinib - but not the reverse sequence - was superior to erlotinib alone. The importance of the order of administration maybe due to the downregulation of p-Akt by gemcitabine in a dose- and time-dependent manner in cells with intrinsic or acquired erlotinib resistance. Our data show that gemcitabine increased the cytotoxic effect of erlotinib by downregulating p-Akt in EGFR-overexpressing cells with either intrinsic or acquired erlotinib resistance.
    Journal of Cancer 08/2011; 2:435-42. · 3.27 Impact Factor
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