Red Raspberry Extracts Inhibit A549 Lung Cancer Cell Migration, Invasion, and Epithelial-Mesenchymal Transition Through the Epidermal Growth Factor Receptor/Signal Transducer and Activator of Transcription-3 Signaling Pathway

The incidence and mortality of lung cancer ranks first among all malignant tumors in the world. Because it is relatively asymptomatic at early stages, most patients do not become aware of the disease until it has progressed to an advanced stage. Advanced lung cancer metastasis results in systemic cachexia and effective treatment becomes challenging, leading to poor response and outcome. Therefore, the development of new drugs for the treatment of lung cancer is paramount. In this study, A549 cells were treated with different concentrations of red raspberry extract and the proliferation, migration, and invasion of cells were evaluated. The results indicated that red raspberry extract reduced the proliferation, migration, and invasion of A549 cells. Western blot analysis was used to detect the expression of the cyclin D1, N-cadherin, vimentin, E-cadherin, EGFR, and STAT3 proteins. Treatment with red raspberry extract reduced the expression of cyclin D1, N-cadherin, vimentin, EGFR, and STAT3, whereas the expression of E-cadherin increased. Following transfection of an EGFR overexpression vector into A549 cells, we observed a reduced inhibitory effect of the red raspberry extract on the proliferation, migration, and invasion of A549 cells. In addition, EGFR overexpression abrogated the increased expression of cyclin D1, N-cadherin, vimentin, EGFR, and STAT3 protein expression in A549 cells following extract treatment. In contrast, E-cadherin protein expression was decreased under these treatment conditions. Overall, this study suggests that red raspberry extract may reduce the proliferation, migration, invasion, and epithelialmesenchymal transition of A549 lung cancer cells by inhibiting the activation of the EGFR/STAT3 signaling pathway. These findings may lead to the development of new strategies to treat advanced lung cancer.