Drug Resistance of Endocardial Endothelial Cells is Related to Higher Endogenous ABCG2

9567 Background: Angiosarcoma (AS) is a malignant neoplasm of endothelial cells. AS has an extremely poor outcome since it can metastasize widely and rapidly becomes chemoresistant. Understanding the mechanism of this resistance is important not only because of the critical need for new therapeutic strategies in sarcoma, but also since it sheds light on important pathways in endothelial growth that may help understand tumor angiogenesis. Methods/Results: We have established and characterized stable pre-chemotherapy (named B8) and chemotherapy-resistant (named D3) angiosarcoma cell lines from an individual patient with primary (non radiated) breast angiosarcoma prior to initiation of chemotherapy and later after development of resistance to adriamycin, ifosfamide, gemcitabine, docetaxel, paclitaxel, interferon, thalidomide and bevacizumab. D3 cells differ dramatically from B8s in morphology and function. Prechemotherapy B8 cells assume a polygonal morphology reminiscent of native endothelial cells, the D3 cells throw out long processes that span several cell lengths, and do not appear to contact-inhibit. Migration and invasion assays confirm the highly motile nature of these cells. Although it is not surprising that the D3 cells were doxorubicin resistant, we found that unlike the B8 cells, the D3 cells actively transcribe VEGF. In keeping with this, D3 cells are relatively more sensitive to growth inhibition by the anti-VEGF drug bevacizumab than chemonaïve B8 cells. Conclusion: These studies reveal two avenues to target chemoresistant human angiosarcoma; via agents affecting cell migration and those agents that target the VEGF pathway. No significant financial relationships to disclose.

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

Journal of Clinical Oncology ◽

10.1200/jco.2009.27.15_suppl.e14643 ◽

2009 ◽

Vol 27 (15_suppl) ◽

pp. e14643-e14643

Author(s):

A. Rebbaa ◽

E. Dyskin ◽

E. Dier ◽

C. Gallati ◽

C. Honko ◽

...

Keyword(s):

Drug Resistance ◽

Endothelial Cells ◽

Tumor Growth ◽

Anticancer Agents ◽

Cellular Proliferation ◽

Cathepsin L ◽

Neuroblastoma Cell ◽

Drug Candidate ◽

Dependent Manner

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.

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