Synergistic Antitumor Activity of ZD6474, An Inhibitor of Vascular Endothelial Growth Factor Receptor and Epidermal Growth Factor Receptor Signaling, with Gemcitabine and Ionizing Radiation against Pancreatic Cancer

Abstract

Purpose: Standard treatments have modest effect against pancreatic cancer, and current research focuses on agents targeting molecular pathways involved in tumor growth and angiogenesis. This study investigated the interactions between ZD6474, an inhibitor of tyrosine kinase activities of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor (EGFR), gemcitabine, and ionizing radiation in human pancreatic cancer cells and analyzed the molecular mechanisms underlying this combination. Experimental Design: ZD6474, ionizing radiation, and gemcitabine, alone or in combination, were given in vitro to MIA PaCa-2, PANC-1, and Capan-1cells and in vivo to MIA PaCa-2 tumor xenografts. The effects of treatments were studied by the evaluation of cytotoxicity, apoptosis, cell cycle, EGFR and Akt phosphorylation, modulation of gene expression of enzymes related to gemcitabine activity (deoxycytidine kinase and ribonucleotide reductase), as well as vascular endothelial growth factor immunohistochemistry and microvessel count. Results: In vitro, ZD6474 dose dependently inhibited cell growth, induced apoptosis, and synergistically enhanced the cytotoxic activity of gemcitabine and ionizing radiation. Moreover, ZD6474 inhibited phosphorylation of EGFR and Akt and triggered cell apoptosis. PCR analysis showed that ZD6474 increased the ratio between gene expression of deoxycytidine kinase and ribonucleotide reductase. In vivo, ZD6474 showed significant antitumor activity alone and in combination with radiotherapy and gemcitabine, and the combination of all three modalities enhanced MIA PaCA-2 tumor growth inhibition compared with gemcitabine alone. Conclusions: ZD6474 decreases EGFR and Akt phosphorylation, enhances apoptosis, favorably modulates gene expression in cancer cells, and acts synergistically with gemcitabine and radiotherapy to inhibit tumor growth. These findings support the investigation of this combination in the clinical setting.Pancreatic cancer is a highly malignant illness that has steadily increased in incidence over recent decades, and it is now the fourth leading cause of death from cancer in the Western world. Despite this, there has been little improvement in prognosis over the past 20 years (1). Due to the delay of clinical symptoms, pancreatic cancer is usually detected at an advanced stage, and survival ranges between 4 and 6 months after diagnosis. Moreover, because of its aggressive biological behavior, this malignancy has a grim prognosis even following surgical resection, and the 5-year survival for all stages of the disease remains below 4% (2). Therefore, pancreatic cancer represents a clinical challenge and novel therapeutic approaches are warranted.Several studies showed that pancreatic cancer is characterized by dysregulation of molecular mechanisms involved in cell proliferation, invasiveness, and angiogenesis (3). Epidermal growth factor receptor (EGFR) is a key driver of cell proliferation, and

Synergistic antitumor activity of pro‐apoptotic agent PAC‐1 with cisplatinum by the activation of CASP3 in pulmonary adenocarcinoma cell line H1299

“…18 In other reports, several sequential combination procedures had been used. Examples include addition of the first drug for 24 h followed by the second drug for a further 48 h, 26 treatment of the first drug for 24 h followed by its removal and addition of the second drug for a further 48 h, 27 targeted therapy for 72 h followed by chemo treatment for 24 h or chemo treatment for 24 h followed by targeted therapy for 48 h, 28 and the first drug for 24 h followed by a second single or add-on drug for 24 h. 29,30 Different means of administration of the drugs may affect the anti-proliferative outcome. Here we used PAC-1 treatment for 48 h and Cis treatment for 24 h (72 h total).…”

Is the resistance of gemcitabine for pancreatic cancer settled only by overexpression of deoxycytidine kinase?

“…Treatment in accordance with the characteristics of the pancreatic cancer cells is needed. Many studies have reported the effectiveness of combination treatment of anticancer drug and inhibitor or gene transduction (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32). There is no treatment that is effective for all carcinomas with various characteristics.…”

Molecular Mechanisms Underlying the Synergistic Interaction of Erlotinib, an Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor, with the Multitargeted Antifolate Pemetrexed in Non-Small-Cell Lung Cancer Cells

“…To study the effect of drug treatments on the activation of EGFR and of ERK1/2 and Akt, cells were exposed to IC 50 values of erlotinib, pemetrexed, and erlotinib-pemetrexed combination and stimulated with EGF (10 ng/ml), as described previously (Janmaat et al, 2003). After protein extraction from cell pellets, EGFR phosphorylation at the tyrosine residue at position 1173 [EGFR (pY1173)], dual phosphorylation of ERK2 at threonine 185 and tyrosine 187 [ERK2 (pTpY185/187)] and ERK1 at threonine 202 and tyrosine 204 [ERK1 (pTpY202/204)] and Akt phosphorylation at serine residue 473 [Akt (pS473)] were evaluated with specific enzyme-linked immunosorbent assays (BioSource International, Camarillo, CA), and normalized, respectively, to the total EGFR, ERK1/2 and Akt, and protein content (Bianco et al, 2006). Pharmacological Interaction Study with the PI3K Inhibitor LY294002.…”

“…Targeted therapies should have limited overlapping toxicities in combination with conventional chemotherapy, and preclinical studies have shown that coadministration with EGFR-TKIs enhanced the effect of different cytotoxic agents against various tumor models (Magné et al, 2003;Morelli et al, 2005;Bianco et al, 2006), including NSCLC cells (Van Schaeybroeck et al, 2006;Li et al, 2007).…”