Ectopic Expression of Sortilin 1 (NTR-3) in Patients with Ovarian Carcinoma

Gene expression profiling of ovarian carcinoma tissues has shown an increase of four-fold expression of SORT1 gene. Sortilin 1 (NTR-3) is a 95-100 kDa protein normally expressed in heart, brain, placenta, skeletal muscle, spinal cord, thyroid, and testis. However, its expression has never been reported in normal ovary. Here, we report expression of sortilin 1 in ovarian carcinoma tissues both at gene and protein levels. Sortilin 1 was expressed in all ovarian carcinoma patients (n=15) as well as ovarian carcinoma cell lines (n=5) regardless of their phenotypic characteristics. Non-malignant ovaries (n=6) did not express sortilin 1. The molecular basis for this ectopic expression is not yet clear. Our results showed a major cell surface expression of sortilin 1 rather than ER-Golgi compartment where it is mainly expressed. This finding may introduce sortilin 1 as a novel tumor marker for diagnosis of ovarian carcinoma and may signify its therapeutic value in targeted therapy.