Association between RCAS1 expression and microenvironmental immune cell death in uterine cervical cancer

Objective. The presence of regional lymph node metastasis is one of the prognostic factors for uterine cervical cancer. The development of metastasis requires that cancer cells avoid lymphocyte attack. Impaired lymphocyte function is mediated by apoptotic factors including receptor-binding cancer antigen expressed on SiSo cells (RCAS1), Fas ligand (FasL), and tumor necrosis factor-α (TNF-α). Our aim was to evaluate the association between expression of these factors and microenvironmental lymphocyte apoptosis in this disease. Methods. Immunohistochemical methods were used to determine the relationship between the expression of RCAS1, FasL, and TNF-α, and the number of apoptotic lymphocytes in primary lesions and metastatic lymph nodes in patients with cervical cancer. Results. Expression of these apoptosis-inducing molecules was quite different in primary tumors and metastatic lymph nodes: RCAS1 expression in lymph nodes was significantly higher than that in primary lesions (P < 0.0001), whereas FasL and TNF-α expressions at these two locations were not significantly different. The number of cells with positive expression of RCAS1, but not of FasL or TNF-α, was significantly correlated with the number of apoptotic lymphocytes in uterine cervix and metastatic lymph nodes (P < 0.0001 for both). Conclusion. RCAS1 expression may be related to tumor cell evasion of immune surveillance via induction of lymphocyte apoptosis in primary lesions and metastatic lymph nodes in uterine cervical cancer.