Tumor-associated macrophages favor C26 murine colon carcinoma cell proliferation in an oxidative stress-dependent manner

Abstract

The role of tumor-associated macrophages (TAMs) in the development of colon carcinoma is still controversial. Therefore, the present study aimed to investigate the TAM‑driven processes that may affect colon cancer cell proliferation. To achieve this purpose, murine macrophages were co-cultured with C26 murine colon carcinoma cells at a cell density ratio that approximates physiological conditions for colon carcinoma development in vivo. In this respect, the effects of TAM-mediated angiogenesis, inflammation and oxidative stress on the proliferative capacity of C26 murine colon carcinoma cells were studied. To gain insight into the TAM-driven oxidative stress, NADPH oxidase, the main pro-oxidant enzyme in macrophages, was inhibited. Our data revealed that the stimulatory effects of TAMs on C26 cell proliferation may be related mainly to their pro-oxidant actions exerted by NADPH oxidase activity, which maintains the redox status and the angiogenic capacity of the tumor microenvironment. Additionally, the anti-inflammatory and pro-angiogenic effects of TAMs on tumor cells were found to create a favorable microenvironment for C26 colon carcinoma development and progression. In conclusion, our data confirmed the protumor role of TAMs in the development of colon carcinoma in an oxidative stress-dependent manner that potentiates the angiogenic capacity of the tumor microenvironment. These data may offer valuable information for future tumor-targeted therapies based on TAM 're-education' strategies.

The Role of Tumor-Associated Macrophages in Colorectal Carcinoma Progression

“…One study confirmed that TAMs-driven oxidative stress, the pro-oxidant enzyme NADPH oxidase in macrophages, was significantly reduced. TAMs contributed to the development of colon carcinoma in an oxidative stress-dependent manner that potentiated the redox status and the angiogenic capacity of the tumor microenvironment [51]. It was found that after co-culturing TAMs with SW480 colon cancer cells, MMP-9 expression was increased, and the epithelial-mesenchymal transition proteins E-cadherin, β-catenin, vimentin, and snail were induced in SW480 cells.…”

Liposomal simvastatin sensitizes C26 murine colon carcinoma to the antitumor effects of liposomal 5‐fluorouracil in vivo

“…Tumor tissues from each experimental group were lysed as previously described, and the protein concentration was measured using the biuret method . The production of the active form of nuclear factor [NF]‐κB (2 µg total protein) (polyclonal rabbit IgG anti‐mouse pNF‐kB‐p65; Santa Cruz Biotechnology), Bcl‐2 (40 µg total protein) (monoclonal anti‐rabbit Bcl‐2; Cell Signaling Technology), and Bax (25 µg total protein) (rabbit polyclonal IgG anti‐Bcl‐2‐associated X protein; Cell Signaling Technology) were determined by western blot analysis, along with β‐actin (rabbit polyclonal IgG anti‐mouse β‐actin; Sigma‐Aldrich) as the loading control, as described previously . The secondary Ab used was goat anti‐rabbit IgG‐HRP‐conjugated (Santa Cruz Biotechnology).…”

“…To determine the effects of the combined therapy on the production levels of angiogenic/inflammatory proteins in tumor tissue, we undertook screening for 24 proteins involved in angiogenesis using the RayBio Mouse Angiogenic Cytokine Antibody Array kit (RayBiotech) as described previously . The production of each angiogenic/inflammatory protein in tumor tissue lysates was determined in duplicate, and represented as mean ± SD of 2 independent experiments.…”

“…To assess the levels of oxidative stress in tumors treated with different regimens of the combined therapy, we measured malondialdehyde (MDA) by HPLC, as we previously described . The results were expressed as nanomoles of MDA, normalized per milligram of protein from tumor lysates.…”

“…The catalytic activity of catalase was assessed using the method described by Aebi . We measured catalase activity of different treated tumor lysates as we previously described . Catalase activity is expressed as units of catalytic activity normalized per milligram of protein.…”