Unfolded Protein Response Is Required in nu/nu Mice Microvasculature for Treating Breast Tumor with Tunicamycin

Abstract

Up-regulation of the dolichol pathway, a "hallmark" of asparagine-linked protein glycosylation, enhances angiogenesis in vitro. The dynamic relationship between these two processes is now evaluated with tunicamycin. Capillary endothelial cells treated with tunicamycin were growth inhibited and could not be reversed with exogenous VEGF(165). Inhibition of angiogenesis is supported by down-regulation of (i) phosphorylated VEGFR1 and VEGFR2 receptors; (ii) VEGF(165)-specific phosphotyrosine kinase activity; and (iii) Matrigel(TM) invasion and chemotaxis. In vivo, tunicamycin prevented the vessel development in Matrigel(TM) implants in athymic Balb/c (nu/nu) mice. Immunohistochemical analysis of CD34 (p < 0.001) and CD144 (p < 0.001) exhibited reduced vascularization. A 3.8-fold increased expression of TSP-1, an endogenous angiogenesis inhibitor in Matrigel(TM) implants correlated with that in tunicamycin (32 h)-treated capillary endothelial cells. Intravenous injection of tunicamycin (0.5 mg/kg to 1.0 mg/kg) per week slowed down a double negative (MDA-MB-435) grade III breast adenocarcinoma growth by ∼50-60% in 3 weeks. Histopathological analysis of the paraffin sections indicated significant reduction in vessel size, the microvascular density and tumor mitotic index. Ki-67 and VEGF expression in tumor tissue were also reduced. A significant reduction of N-glycan expression in tumor microvessel was also observed. High expression of GRP-78 in CD144-positive cells supported unfolded protein response-mediated ER stress in tumor microvasculature. ∼65% reduction of a triple negative (MDA-MB-231) breast tumor xenograft in 1 week with tunicamycin (0.25 mg/kg) given orally and the absence of systemic and/or organ failure strongly supported tunicamycin's potential for a powerful glycotherapeutic treatment of breast cancer in the clinic.

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

“…Multiple evidences from our study link VEGFR2 with blebbishield biology such as, tunicamycin inhibit sphere formation (Figure 5d) and also reported to downregulate VEGFR2. 37 Heparin binds VEGFR2 at the same motif where VEGF-A binds, 38 hence heparin might block sphere formation by interfering VEGF-A engagement with VEGFR2. Furthermore, acidic pH is known to influence VEGF production and bioavailability.…”

The unfolded protein response in retinal vascular diseases: Implications and therapeutic potential beyond protein folding

“…Sustained activation of XBP1 results in apoptosis of endothelial cells by activation of a caspase-dependent pathway, inhibition VE-cadherin transcription (Zeng, Zampetaki et al 2009), and increasing Beclin-1-mediated autophagy (Margariti, Li et al 2013). Banerjee and coworkers demonstrated that induction of the UPR by tunicamycin inhibits angiogenesis both in vitro and in vivo via up-regulating thrombospondin-1 (TSP-1, an endogenous angiogenic inhibitor) and by suppressing VEGF-induced activation of VEGF receptor 1 (VEGFR1) and VEGF receptor 2 (VEGFR2) (Banerjee, Lang et al 2011). These results are consistent with our finding (S.X.…”

Upregulation of RASSF1A in Colon Cancer by Suppression of Angiogenesis Signaling and Akt Activation

“…The MVC were analyzed as previously described [22]. Five hot spots from each group were evaluated under 200X magnification and microscopic images from each area were collected (ASI C-203) using an Olympus BX53 with the use of bioquant lifescience 2017 program and recorded as MVC.…”