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Heat shock protein 70 (HSP70) is a key member of the HSP family that contributes to a pre-cancerous environment; however, its role in lung cancer remains poorly understood. The present study used geranylgeranylacetone (GGA) to induce HSP70 expression, and transforming growth factor-β (TGF-β) was used to construct an epithelial-mesenchymal transition (EMT) model by stimulating A549 cells in vitro. Western Blot was performed to detect protein levels of NADPH oxidase 4 (NOX4) and the EMTassociated proteins E-cadherin and vimentin both before and after HSP70 expression. Cell morphological changes were observed, and the effect of HSP70 on cell migration ability was detected via the wound healing. The results demonstrated that GGA at 50 and 200 μmol/L could significantly induce HSP70 expression in A549 cells (P < 0.05). Furthermore, HSP70 induced by 200 μmol/L GGA significantly inhibited the changes of E-cadherin, vimentin, and cell morphology induced by TGF-β (P < 0.05), while HSP70 induced by 50 μmol/L GGA did not. The results of the wound healing assay indicated that 200 μmol/L GGA significantly inhibited A549 cell migration induced by TGF-β. Taken together, the results of the present study demonstrated that overexpression of HSP70 inhibited the TGF-β induced EMT process and changed the cell morphology and migratory ability induced by TGF-β in A549 cells.

Background: Heat-shock protein 70 (HSP70) is a member of the heat-shock protein family which is expressed in various types of cancer and associated with apoptosis in cancer cells. However, the role of HSP70 in the regulation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK)-dependent growth and apoptosis in lung cancer cells remains largely unknown.Methods: In this study, we conducted in vitro experiments. First, we examined the effect of HSP70 by treatment with mild heat and JNK/p38 MAPK inhibitors on cell proliferation in A549 cells by MTT assay.And then, through the use of flow cytometric assay, we examined the effect of HSP70 by treatment with mild heat and JNK/p38 MAPK inhibitors on cell apoptosis in A549 cells. Finally, we determined the role of HSP70 in the regulation of JNK and p38 MAPK-dependent growth and apoptosis in A549 cells by siRNA HSPAIA-2009 and Western blot. Results:We found that treatment of the cells with mild heat and JNK/p38 MAPK pathway inhibitors (SP600125 and SB203580) promoted cell proliferation in the presence of actinomycin D (ActD) in A549 cells. We also showed that treatment with mild heat or SP600125 and SB203580 significantly slowed the steps of apoptosis induced by ActD in A549 cells. Moreover, we found that HSP70 overexpression induced by mild heat markedly decreased the expression of cell growth and apoptosis-related protein p-JNK, p38 and caspase-3. By contrast, knockdown of HSP70 by siRNA HSPAIA-2009 effectively promoted the expression of the JNK and p38 MAPK. Conclusions:Our results indicate that HSP70 plays an important role in lung cancer growth and apoptosis through the activation of JNK and p38 MAPK signaling in actinomycin-D-treated lung cancer A549 cells.