Sublethal Heat Treatment Inhibits Malignant Potential Of MCF-7 Breast Cancer Cells

Background: Breast cancer is the most common malignant tumor of the female. The main therapeutic strategy of breast cancer is surgical resection combining with chemotherapy, radiotherapy, adjuvant hormonal therapy and targeted therapy.Currently, thermal ablation technologies, including microwave ablation(MWA) and radio frequency ablation(RFA), have been tried in the treatment of breast cancer in early stage, and the efficacy and safety have been preliminarily approved. For larger volume of locally advanced breast cancer, one main disadvantage of the above methods may be local residual. Sublethal temperature during the process of ablation may change the biological behavior of the residual cells in the peripheral area of the ablation lesion. So the influence of thermal ablation technologies on the residual cells in the marginal zone deserves our attention. The research of the influence focuses on liver, pancreas and other organs in abdominal cavity except breast at present.Purpose: The study was designed to evaluate the effect of sublethal heat treatment on proliferation, migration and invasion of MCF-7 breast cancer cells and explore the change of the expression of epithelial-mesenchymal transition(EMT)-related factors.Materials and methods: The MCF-7 cells were exposed to different temperature gradients(44?C、47?C、50?C) for 10 minutes, simulating the marginal zone of thermal ablation therapy. We then evaluated whether or not sublethal heat treatment changed the proliferation, migration and invasion, and the expression of EMT-related factors of residual cells.Results: After being exposed in sublethal heat, the morphology in some MCF-7 cells changed from a typical epithelium to spindle shape; Sublethal heat-exposed MCF-7cells showed inhibited proliferation by CCK-8 method; The cell number under the membrane of the well is 180±20、154±12、43±8(migration);126±16、86±7、47±10(invasion) in control group(37?C) and experimental groups(44?C、47?C)respectively. All MCF-7 cells treated with 44?C and 47?C exhibited significantly decreased migration potential and invasion ability than that in control group, P<0.001;While the expression of E-cadherin and Vimentin of the heat-treated cells was not significantly changed compared with the control(37?C).Conclusions: Sublethal heat treatment inhibits the potential of proliferation,invasiveness and metastasis in MCF-7 cells, without accompanying with EMT-like phenotype changes. It is suggested thermal ablation therapy is safe for breast cancer,which could inhibit proliferation, invasion and migration of residual tumor cells survived from the ablation therapy, gaining time for the further treatment.