Cyclic RGD Pentapeptide Cilengitide Enhances Efficacy of Gefitinib on TGF-β1-Induced Epithelial-to-Mesenchymal Transition and Invasion in Human Non-Small Cell Lung Cancer Cells

Abstract

During non-small cell lung cancer (NSCLC) progression, transforming growth factor (TGF)-β mediated epithelial-to-mesenchymal transition (EMT) is an important process leading to high mortality and poor prognosis. The EMT is a fundamental process for morphogenesis characterized by the transformation of cancer cells into invasive forms that can be transferred to other organs during human lung cancer progression. Gefitinib, an epidermal growth factor receptor (EGFR) inhibitor, has shown anti-proliferative effects in EGFR-mutated NSCLC cells and an inhibitory effect on migration and invasion of NSCLC cells to other organs. In this study, we evaluated the combinatorial treatment effect of cilengitide, a cyclic RGD pentapeptide, on TGF-β1-induced EMT phenotype and invasion. Gefitinib suppressed the expression of TGF-β1-induced mesenchymal markers by inhibiting Smad and non-Smad signaling pathways. Cilengitide enhanced the inhibitory effect of gefitinib on TGF-β1-induced expression of mesenchymal markers, phosphorylation of Smad2/3, and invasion of NSCLC A549 cells. We suggested that the use of cilengitide can improve the efficacy of anti-cancer drugs in combination drug-based chemotherapy. These results provide an improved therapeutic strategy for treating and preventing EMT-related disorders, such as NSCLC, lung fibrosis, cancer metastasis, and relapse.

Combination Effect of Cilengitide with Erlotinib on TGF-β1-Induced Epithelial-to-Mesenchymal Transition in Human Non-Small Cell Lung Cancer Cells

“…In a previous report on cilengitide combined with the EGFR inhibitor gefitinib, we confirmed their cytotoxicity in CPAE cells and a synergistic effect on NSCLC cell viability and TGF-β1–induced EMT phenotype changes [ 36 ]. Based on that study, we investigated the combined treatment effect of cilengitide with erlotinib on NSCLC cell viability and TGF-β1–induced EMT marker expression.…”

“…We also tested the effect of cilengitide with erlotinib on TGF-β1–induced invasion in A549 cells. In our previous report, we confirmed that cilengitide has an inhibitory effect and that combined treatment with gefitinib yielded a synergistic effect [ 36 ]. As shown in Figure 6 A, either erlotinib or cilengitide inhibited the TGF-β1–induced invasion of A549 cells across the gelatin-coated membrane, and their combination increased this inhibitory effect.…”

“…Although studies on cilengitide co-administration with various drugs are underway, the mechanism for EMT inhibition and the combination effects in NSCLC have not yet been examined. In a pair of studies on NSCLC cells, we have confirmed the inhibitory effect of cilengitide co-administration and the EGFR inhibitor gefitinib [ 36 ] or erlotinib (the current work) on EMT. Collectively, our findings show that the combination of cilengitide and EGFR inhibitors could represent a new chemotherapeutic option for modulating growth and invasive changes in EMT-associated NSCLC cell changes.…”

“…In addition, we recently described an enhancing effect of cilengitide with gefitinib on limiting TGF-β–mediated EMT in NSCLC cells. By inhibiting Smad and non-Smad signaling, cilengitide enhanced the effect of gefitinib on NSCLC cell death and TGF-β–induced EMT phenotype change without severe cytotoxicity in normal cells [ 36 ].…”

TGF-beta signal transduction: biology, function and therapy for diseases

“…Cilengitide is supposed to enhance the inhibition of erlotinib on TGF-β1-induced EMT and phosphorylation of SMAD2/3 [304,305]. In a phase I study, continuous infusion of cilengitide plus chemoradiotherapy for patients with stage III non-small cell lung cancer is potentially tolerable.…”