Abstract 4779: Circulating and tumor-infiltrating CD4+IL-17+ T-cells in mice bearing orthotopic and heterotopic prostate tumors

Abstract

Abstract Helper T-cells expressing interleukin-17 are classified as TH17 cells, which are important in autoimmune disease and inflammatory responses. However, there are limited studies on their role and effects on cancer development and progression. Here we used a syngeneic murine model for prostate cancer, RM1(BM)-B4H7-Luc, to evaluate the proportion of TH17 cells in various organs (spleen, lymph nodes, prostate) and peripheral blood of tumour-bearing mice compared to normal mice. The number of tumour-infiltrating TH17 cells in tumours located at different sites (subcutaneous and prostate) were also compared. The proportion of TH17 cells in the peripheral blood of prostate tumour-bearing mice was significantly higher than in age-matched control mice (p<0.05) or mice bearing subcutaneous tumours (p<0.05). Additionally, an increase in the proportion of tumour-infiltrating CD4+ T cells expressing IL-17 was observed in both subcutaneous (9.28%) and prostate tumours (10.2%) compared to lymphoid organs (spleen and lymph node, <1%) from these mice, suggesting sequestration of these cells within the tumour. In addition, significantly higher numbers of TH17 cells were detected in prostate tumours compared to normal prostates (p=0.0357). Finally, the percentage TH17 in the peripheral blood of mice with prostate tumours correlated with the size of the tumour ((R2=0.84, p=0.0014). In conclusion, in our model, we show that TH17 cells are a significant proportion of tumour infiltrating T-cells and, as proposed in recent studies, they are likely to be involved in the anti-tumour immunity/tumour rejection. Importantly, the number of circulating TH17 cells correlates with tumour size for prostatic tumours, but not subcutaneous tumours. Thus, assessment of peripheral blood TH17 cells may be an effective tool for diagnosis/prognosis of prostate cancer. This relationship does not hold if subcutaneous models are used for preclinical studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4779.