ABSTRACT
BACKGROUND: Macrophages promote angiogenesis, metastasis, and drug resistance in several cancers. Similarly, TonEBP/NFAT5 induces metastasis in renal carcinoma and colon cancer cells. However, the role of this transcription factor and that of macrophages in lung cancer cells remains unclear. Therefore, this study investigated the effects of macrophages and TonEBP/NFAT5 expression on cisplatin resistance and migration in A549 lung adenocarcinoma cells. RESULTS: A549 cells were cultured alone or indirectly co-cultured with THP-1-derived macrophages using a transwell culture chamber. Cisplatin-induced cell death was markedly decreased and migration increased in co-cultured A549 cells. Macrophage-conditioned media (CM) showed a similar effect on drug resistance and migration. Cisplatin-induced apoptosis, DNA fragmentation, and cleaved apoptotic proteins PARP and caspase-3 were markedly reduced in macrophage CM-induced A549 cells. Here, ERK, p38, JNK, and NF-κB activities were increased by macrophage CM. Furthermore, the proteins involved in cisplatin resistance and cancer cell migration were identified using specific inhibitors of each protein. ERK and NF-κB inhibition considerably reduced cisplatin resistance. The increase in macrophage CM-induced migration was partially reduced by treatment with ERK, JNK, and NF-κB inhibitors. TonEBP/NFAT5 expression was increased by macrophages, resulting in increased cisplatin resistance, cell migration, and invasion. Moreover, RNAi-mediated knockdown of TonEBP/NFAT5 reduced cisplatin resistance, migration, and invasion in macrophage CM-induced A549 cells. CONCLUSIONS: These findings demonstrate that paracrine factors secreted from macrophages can change A549 cells, resulting in the induction of drug resistance against cisplatin and migration. In addition, the TonEBP/NFAT5 ratio, increased by macrophages, is an important regulator of the malignant transformation of cells.
Subject(s)
Cisplatin , Lung Neoplasms , Humans , Cisplatin/pharmacology , NF-kappa B , A549 Cells , Transcription Factors , Lung Neoplasms/drug therapyABSTRACT
BACKGROUND/AIM: Macrophages prevail in the microenvironment of several tumors, including non-small-cell lung cancer (NSCLC), where they secrete pro-tumorigenic factors that contribute to cancer progression. This study investigated the role of macrophages on the resistance of epidermal growth factor receptor (EGFR)-mutated NSCLC cells to tyrosine kinase inhibitors (TKIs). MATERIALS AND METHODS: EGFR-mutated cell lines PC-9 and HCC827 were cocultured with macrophages and treated with TKIs (erlotinib and gefitinib). The effects of the macrophage-conditioned medium (macrophage CM) on gefitinib resistance and cell migration were also evaluated. RESULTS: Co-culture with macrophages significantly enhanced the resistance to erlotinib and gefitinib in PC-9 and HCC827 cells compared to that in cells cultured independently. Macrophage CM markedly induced gefitinib resistance in PC-9 cells, with maximum resistance observed at 50% CM concentration. This resistance persisted for up to 48 h post-CM removal. Macrophage CM inhibited gefitinib-induced apoptosis, as evidenced by the decreased expression of cleaved caspase-3, PARP, and BIM. Additionally, macrophage CM increased the migration ability of PC-9 cells, as shown by the wound healing and transwell migration assays. Studies have shown that TonEBP is crucial in cancer metastasis and drug resistance; we found that inhibition of TonEBP/NFAT5 expression reduced gefitinib resistance and migration in macrophage CM-induced PC-9 cells, indicating its role as mediator of these effects. CONCLUSION: Macrophages contribute to TKI resistance and enhance the migration of EGFR-mutated NSCLC cells through mechanisms involving TonEBP/NFAT5. Therefore, targeting TonEBP/NFAT5 represents a potential therapeutic strategy for overcoming macrophage-induced TKI resistance in NSCLC cells.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Cell Movement , Drug Resistance, Neoplasm , Gefitinib , Lung Neoplasms , Macrophages , Humans , Gefitinib/pharmacology , Cell Movement/drug effects , Macrophages/metabolism , Macrophages/drug effects , Cell Line, Tumor , Carcinoma, Non-Small-Cell Lung/pathology , Carcinoma, Non-Small-Cell Lung/metabolism , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/pathology , Lung Neoplasms/metabolism , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , ErbB Receptors/metabolism , ErbB Receptors/genetics , Apoptosis/drug effects , Transcription Factors/metabolism , Transcription Factors/genetics , Antineoplastic Agents/pharmacology , Culture Media, Conditioned/pharmacology , Protein Kinase Inhibitors/pharmacology , Coculture Techniques , Erlotinib Hydrochloride/pharmacology , Gene Expression Regulation, Neoplastic/drug effectsABSTRACT
Lung cancer has the highest mortality rate among all cancers, in part because it readily metastasizes. The tumor microenvironment, comprising blood vessels, fibroblasts, immune cells, and macrophages [including tumor-associated macrophages (TAMs)], is closely related to cancer cell growth, migration, and invasion. TAMs secrete several cytokines, including interleukin (IL)-1ß, which participate in cancer migration and invasion. p21-activated kinase 1 (PAK1), an important signaling molecule, induces cell migration and invasion in several carcinomas. Tonicity-responsive enhancer-binding protein (TonEBP) is also known to participate in cancer cell growth, migration, and invasion. However, the mechanisms by which it increases lung cancer migration remain unclear. Therefore, in this study, we aimed to elucidate the mechanisms by which IL-1ß and TonEBP affect lung cancer cell migration and invasion. We found that A549 cocultured-MΦ-secreted IL-1ß induced A549 cell migration and invasion via the PAK1 pathway. TonEBP deficiency reduced A549 cell migration and invasion and increased responsiveness to IL-1ß-induced migration and invasion. PAK1 phosphorylation, which was promoted by IL-1ß, was reduced when TonEBP was depleted. These results suggest that TonEBP plays an important role in IL-1ß induction and invasiveness of A549 cells via the PAK1 pathway. These findings could be valuable in identifying potential targets for lung cancer treatment.