Twenty-six patients with UC-related cancer were classified into groups according to the length of sulfasalazine treatment as follows: (1) long-term (LT) (≥ 5 years) and (2) short-term (ST) (< 5 years). Using immunohistochemistry, we compared CD44v9 and Ki-67 expression and pathological characteristics of each group's tumors. In vitro assay was performed to investigate the effect of sulfasalazine on epithelial differentiation and proliferation of CD44+ cancer cells.
Immunohistochemical analysis revealed that CD44v9 expression tended to be lower in the LT group (LT:ST = 15.4%:46.2%, P = 0.20), and Ki-67/CD44v9 double-stained cells were significantly lower in the LT group (LT:ST = 0%:6.9%, P = 0.01). Pathologically, the frequency of well-differentiated adenocarcinomas was higher in the LT group (LT:ST = 84.6%:38.5%, P = 0.04). In vitro assay revealed that sulfasalazine promoted the expression of epithelial differentiation markers (E-cadherin and CDX2) and inhibited the proliferation of CD44+ cancer cells.
Long-term sulfasalazine administration reduced proliferative CD44v9+ cells and increased the degree of differentiation of adenocarcinomas. These findings indicate the importance of CD44v9+ cells in UC-related cancer progression and suggest that sulfasalazine may serve as a novel therapeutic agent that targets CD44v9+ cells.