PDF - 2987KB, Tumor growth was established by subcutaneous injection of parental HeLa cells into athymic nude mice (nu/nu) followed by the oral administration of tiplaxtinin at two different doses as described in Materials and Methods. Corn oil administered orally served as control. A, HeLa tumor sizes were recorded over five weeks. The relative tumor size was plotted as mean + SD from the three treatment groups per cell line (n=10/group). Treatment with tiplaxtinin (5 mg/kg and 20 mg/kg) was associated with a reduction in HeLa tumor burden. B, H&E and PAI-1 staining of HeLa tumors are shown (images 200X). A reduction in PAI-1 expression was noted in HeLa tumors treated with tiplaxtinin. C, Microvessel density (MVD) was quantified based on CD31 staining as previously reported (22). Proliferative index (PI) was quantified based on Ki-67 staining as previously reported (22). Apoptotic index (AI) was quantified based on cleaved caspase-3 staining as previously reported (22). Tiplaxtinin treatment of xenografts was associated with a reduction in angiogenesis and proliferation with an accompanied induction of apoptosis. Data from one representative experiment are presented as mean + SD. *, p < 0.05.
ARTICLE ABSTRACT
Cancers of the urinary bladder result in aggressive and highly angiogenic tumors for which standard treatments have only limited success. Patients with advanced disease have a 5-year survival rate of less than 20%, and no new anticancer agent has been successfully introduced into the clinic armamentarium for the treatment of bladder cancer in more than 20 years. Investigations have identified plasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor, as being highly expressed in several malignancies, including bladder cancer, in which high expression is associated with a poor prognosis. In this study, we evaluated PAI-1 as a potential therapeutic target for bladder cancer. PAI-1 expression was manipulated in a panel of cell lines and functional inhibition was achieved using the small molecule tiplaxtinin. Reduction or inhibition of PAI-1 resulted in the reduction of cellular proliferation, cell adhesion, and colony formation, and the induction of apoptosis and anoikis in vitro. Treatment of T24 xenografts with tiplaxtinin resulted in inhibition of angiogenesis and induction of apoptosis, leading to a significant reduction in tumor growth. Similar results were obtained through evaluation of the human cervical cancer HeLa cell line, showing that PAI-1–mediated effects are not restricted to tumor cells of bladder origin. Collectively, these data show that targeting PAI-1 may be beneficial and support the notion that novel drugs such as tiplaxtinin could be investigated as anticancer agents. Mol Cancer Ther; 12(12); 2697–708. ©2013 AACR.
