We investigated the fundamental function of the lung cancer tumour microenvironment. Proteasome inhibition has emerged as a clinically successful anti-cancer therapeutic strategy, with the antineoplastic medication bortezomib showing high efficacy against multiple cancers. Tumour-associated macrophages (TAMs), which migrate to tumour stroma, are known to promote cell proliferation, apoptosis, and metastasis within the lung cancer microenvironment. However, the specific interaction of macrophages, lung cancer cells, and bortezomib are still unclear. Most in vitro cell cultures are traditionally grown in a two-dimensional (2D) culture system, although 3D cultures have demonstrated greater success in terms of drug response, gene expression and viability. Therefore, to elucidate the role of macrophages, we aimed to establish a co-culture model in both 2D and 3D cultures using A549 human lung cancer cells and THP-1 derived macrophages. Apoptotic effects were analysed using the Annexin V-PI method. Since NF-kB and TNF-α play important roles in the anti-proliferation and apoptosis pathways, the levels of NF-kB and TNF-α mRNA expression were measured. As a result, bortezomib significantly increased cell apoptosis in cells co-cultured with M0 macrophages. IL-1β cytokine levels also increased, and NF-kB mRNA expression levels decreased. Understanding the mechanisms that modulate the tumour microenvironment may facilitate the development of novel anticancer therapies. The utilisation of TAMs may improve the successful treatment of lung cancer and warrants further study.
Lung cancer is a leading cause of cancer-related deaths, primarily as a result of metastases. In this metastasis, the epithelial-to-mesenchymal transition (EMT) is essential. Interaction with the cancer cell microenvironment is primarily dependent on M1- and M2-polarized macrophage. In this study, we revealed the EMT-associated activity of M1, M2a and M2c macrophages in A549 lung cancer cells. We established a co-culture model of A549 lung cancer cells utilizing THP-1-derived M1/M2 polarised macrophages to explore the involvement of macrophages in the immune response, apoptosis, and EMT in lung cancer. Although multiple polarising agents are routinely used for M1 and M2 conversion, we assessed a new possible polarising agent, hydrocortisone. M1 increased A549 cell sensitivity to proteasome inhibitors and decreased A549 cell viability by inducing apoptosis. EMT was induced in the presence of M2c macrophages in A549 cells by the levels of vimentin, fibronectin, E-cadherin, NF-kB, CCL-17. We also revealed the antiproliferative effects of bortezomib and ixazomib on A549 cells in both 2D and 3D cultures. Our findings could help develop an immunotherapeutic strategy by shedding light on a previously undiscovered part of the EMT pathway. Furthermore, additional investigation may reveal that polarising tumour-associated macrophages to M1 and eliminating the M2a or particularly the M2c subtype are effective anti-cancer strategies.
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