In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 13_Supplement ( 2017-07-01), p. 2695-2695
Abstract:
Insufficiency in tumor perfusion and high rate glycolysis combine to reduce the pH of tumor microenvironment. In a TRAMP model of prostate cancer, we had shown that carcinogenesis is associated with increasing acidification of the microenvironment and that neutralization of this acidity can prevent cancer emergence or metastases. Carcinogenesis in the TRAMP model is also associated with increased fibrosis and immune cells infiltration. We thus sought to determine if fibrosis drives immune infiltration in early tumorigenesis or vice-versa; and whether this dynamics is affected by tumor acidity. To investigate this, we harvested prostates from TRAMP mice or their matching non-transgenic controls at different time points and stained serial prostate tissue sections with F4/80 (macrophages), SMA (cancer-associated fibroblasts, CAFs), and Masson’s Trichome (collagen). Quantitative image analysis reveals that increase in fibrosis occur prior to macrophage infiltration and that both events preceded tumor development. However, the relative amount of collagen fibers was unchanged across all time points. Notably, neither fibrosis nor macrophage infiltration occurred in mice treated with buffer, suggesting an involvement of acidity in this immune stromal interactions. Interestingly, macrophages isolated from latter time points in the untreated group as well as macrophages co-cultured with prostate tumor cells at acidic pH, possessed an M2-like phenotype by expressing immunosuppressive genes (e.g. Arginase 1, Arg1) and a range of scavenging receptors (e.g. mannose receptor, Cd206), as well as releasing more angiogenic factors (e.g. VEGF and MMPs). Similar results were recapitulated when M2 macrophages were stimulated at acidic pH by showing enhanced Cd206 and Arg1 expression. On the functional level, macrophages activated at acidic pH had a higher ability to uptake fluorescently labelled ovalbumin and collagen, as examples of mannosylated ligands that prevail the fibrotic microenvironment. In summary, these results suggest that tumor acidity may promote fibrosis, with subsequent macrophage infiltration and phenotypic switching, leading to increased collagen turnover. It is suspected that this extracellular matrix remodeling may be permissive for tumor progression. Citation Format: Asmaa El-Kenawi, Jasreman Dhillon, Arig Ibrahim-Hashim, Dominique Abrahams, Shari Pilon-Thomas, Brian Ruffell, Robert Gatenby, Robert Gillies. Role of tumor generated acidity in immune stromal interactions during prostate carcinogenesis [abstract] . In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2695. doi:10.1158/1538-7445.AM2017-2695
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/1538-7445.AM2017-2695
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2017
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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