Abstract 5074: Anti-angiogeneic glycotherapy tunicamycin induces ER stress mediated unfolded protein response in beast cancer cells.

Abstract

Abstract Tumor growth is angiogenesis dependent. Most of the current therapeutics targets either the tumor cells or the microvasculature but not necessarily the both. As a consequence, the patients enjoy disease free survival only for a limited period of time, irrespective of a good initial prognosis and pathological response rates. Aberrant glycosylation has been observed in experimental and human tumors and we have hypothesized that a good asparagine-linked (N-linked) protein glycosylation inhibitor could target both endothelial cells and tumor cells and eliminate the tumor progression. Our objective is therefore to test the efficacy of such an inhibitor, tunicamycin. The results support that tunicamycin inhibits angiogenesis in vitro and in vivo, and the breast tumor microvasculature. There is cell cycle arrest followed by apoptosis due to ER (endoplasmic reticulum)stress-mediated unfolded protein response (upr). To evaluate the intracellular protein status under upr, the proteome was analyzed by Raman spectroscopy focusing on bands at 1672, 1684 and 1694 cm−1, which are characteristics of proteins and originate from C=O stretching vibrations of mono-substituted amides. In tunicamycin-treated cells these bands decreased in area. Thus, in the presence of tunicamycin, newly synthesized protein chains fail to arrange properly into their final secondary and/or tertiary structures, and the random coils they form had undergone further degradation. Tunicamycin treatment (i) prevents the colony formation, and (ii) fails to reverse the inhibition of angiogenesis by VEGF165. VEGF-specific protein tyrosine phosphorylation in capillary endothelial cells is also inhibited. When tested, tunicamycin indiscriminately inhibited the progression of a double negative (MDA-MB-435) and a triple negative (MDA-MB-231) breast cancer by ∼55-65% in three weeks in athymic nude mice, Balb/c(nu/nu). High GRP-78/Bip expression evidenced ER stress in tumor tissue. To evaluate the specificity and efficacy of tunicamycin on tumor cells, five different breast cancer cell lines with distinct genotypic and phenotypic characteristics were analyzed. Cellular proliferation of MDA-MB-231, MDA-MB-468, BT-20, BT-474 and ZR-731 cells is inhibited almost to the same extent and the cells also failed to colonize. High protein and mRNA levels for GRP-78/Bip in MDA-MB-231 breast cancer cells indicate ER stress. Down regulation of cyclin D1 expression indicates cell cycle impairment irrespective of high F2F1, Bcl-2 and phospho-p53 expression with no change in CDK4. Total Rb is increased in tunicamycin treated cells but pRb is down-regulated. Cell death due to apoptosis was evidenced and concluded that upr signaling causes a translational attenuation in MDA-MB-231 breast cancer cells. Supported in part by grants from Susan G. Komen for the Cure BCTR0600582 (DKB) and NIH/NIMHD 8G12MD007583 (KB). Citation Format: Dipak K. Banerjee, Aditi Banerjee, Lydia Espinoza, Neyshari Sanchez, Krishna Baksi, Maria O. Longas. Anti-angiogeneic glycotherapy tunicamycin induces ER stress mediated unfolded protein response in beast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5074. doi:10.1158/1538-7445.AM2013-5074