The expression of IFN-γ and FOXP3 in the microenvironment of renal cell cancer, and its role in the tumor infiltrating lymphocytes distribution

Abstract

Objective To investigate the role of IFN-γ and FOXP3 expression in subpopulation distribution and functions of tumor-infiltrating lymphocytes (TILs) in the microenvironment of renal cell cancer. Methods 30 renal cell cancer tissue samples were freshly collected from the laparoscopic radical nephrectomy in the first hospital of Jiaxing. After frozen sectioning, immunofluorescent staining was conducted to detect the infiltrating CD4 positive and CD8 positive cells, and the expression of FOXP3 and IFN-γ as well. In addition, TILs were isolated from the tumor tissues by density-gradient centrifugation. TILs from tumor center or tumor invasive edge were purified independently and measured for the mRNA levels of FOXP3 and IFN-γ by qRT (quantitative reverse transcription)-PCR. Results Tumor-infiltrating CD4+ and CD8+ T cells were concentrated in the invasive edge of renal cell cancer tissues. The expression of FOXP3 was found to be inversely related to that of IFN-γ from the immunofluorescent staining. The relative FOXP3 mRNA levels for the TILs from tumor center and invasive edge were 64.6±9.4 and 36.2±1.8, respectively, with significant difference(P<0.05). The relative IFN-γ mRNA levels were 631.8±151.4 and 1 726.0±344.1 (P<0.05). The trend of relative expression of FOXP3 was reversed in terms of IFN-γ. Conclusions The study on the renal cell cancer tissue samples suggested that the tumor-specific cytotoxic immune cells relatively concentrated in the tumor invasive edge. Key words: Renal cell cancer; Tumor microenvironment; Tumor-infiltrating lymphocytes; Interferon-γ; FOXP3