Correlation between sigma2 receptor protein expression and histopathologic grade in human bladder cancer

Sigma2 (σ2) receptor proteins are overexpressed in several tissues and tumour cell lines. Although the biomolecular mechanism of this overexpression must be elucidated, σ2 receptor was considered a potential biomarker for monitoring solid tumour proliferation. In this study, we verified first σ2 receptor overexpression by saturation analysis with radioligand in six human bladder cancer specimens, then if a possible correlation could be established between σ2 overexpression and tumour tissue stage and grade. The results displayed that σ2 receptor protein was normally expressed in human bladder and overexpressed in the case of high-grade transitional cell carcinomas. Moreover, these receptors were undetected in a low-grade squamous cell carcinoma and in a very rare form of anaplastic, large cells plasmacytoid cancer.