Cathepsin B protein levels in endometrial cancer: Potential value as a tumour biomarker

Lysosomal cysteine protease Cathepsin-B has been implicated in the progression of various human tumours. We examined Cathepsin-B protein levels in endometrial carcinoma patients-mainly post-menopausal-and investigated their possible association with clinical and pathological parameters in order to assess Cathepsin-B's significance as a potential tumour biomarker.

The indirect immunoperoxidase method was used for Cathepsin-B immunohistochemical staining of 64 paraffin-embedded endometrial tumour tissues, having follow-up period of 18-240 months. Steroid hormone receptors were measured as well. Tissue samples were staged following the FIGO criteria.

Positive Cathepsin-B immunostaining was observed in 27 patients (42.2%) and was significantly associated with the FIGO stage of the disease (p=0.006), as well as cervical and stromal invasion (p=0.001 and p=0.037, respectively) and progesterone receptor status (p=0.027). Positive Cathepsin-B expression was also inversely related to Disease-free Survival (p=0.034) and Overall Survival (p=0.035) in univariate analysis, as well as in multivariate analysis (p=0.022 and p=0.035, respectively).

Increased Cathepsin-B expression was found to be predictive of more aggressive tumour behaviour over time and can be regarded as an unfavourable and independent tumour marker for endometrial cancer patients with a long follow-up.