Antiproliferative, antiangiogenesis, and reversal of chemoresistance by specific cathepsin L inhibitors

• Published in: Journal of clinical oncology Vol. 27; no. 15_suppl; p. e14643
• Main Authors: Rebbaa, A., Dyskin, E., Dier, E., Gallati, C., Honko, C., Simone, T., Yalcin, M., Sudha, T., Mousa, S. A.
• Format: Journal Article
• Language: English
• Published: 20.05.2009
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2009.27.15_suppl.e14643

Abstract only e14643 Background: Uncontrolled proliferation, enhanced angiogenesis and the development of resistance to therapy are hallmarks of cancer; therefore, the development of approaches to simultaneously target these three processes would be the most desirable. Previous work from our laboratory has demonstrated that NapSul-Ile-Trp-CHO (NSITC), a specific inhibitors of cathepsin L, and its analogs strongly inhibited cancer cell proliferation and suppressed the development of drug resistance in vitro (Zheng X. et al., 2004 Cancer Res. 64:1773–80). In the present study, we sought to investigate the validity of these observations in vivo, and to dissect the underlying mechanism(s). Methods: Nude mice (Strain CD1) bearing xenografts of doxorubicin resistant neuroblastoma cell line SKN-SH/R were challenged with doxorubicin (1.5 mg/Kg) alone, NSITC (20 mg/kg) alone or the combination of both. The effect of NSITC on tumor angiogenesis was also investigated using the Chick Chorioallantoic Membrane (CAM). Putative mechanisms by which NSITC inhibits cellular proliferation, drug resistance and angiogenesis were studied using cancer and endothelial cells maintained in culture. Results: The in vivo data indicated that doxorubicin alone had no effect on tumor growth, however NSITC alone exerted 40% inhibition and the combination of both drugs reduced tumor growth by about 90%. NSITC also caused a 125% inhibition of blood vessel branching in the CAM model (at 1 μg/CAM). Investigation of the underlying mechanisms of its action revealed that at low concentration, NSITC forces cancer cells into senescence, preventing them from developing resistance to classical anticancer agents, and at high concentrations, it induced autophagic cell death. NSITC also strongly inhibited the proliferation and invasion of endothelial cells in a dose dependent manner with more than 90% inhibition at 20 μM. Conclusions: Overall, these findings suggest that NSITC has multi-anticancer functions and thus, may represent a potential drug candidate for the treatment of aggressive malignancies. No significant financial relationships to disclose.