P3-17-07: EGCG, a Green Tea Antioxidant Suppresses Breast Tumor Angiogenesis and Growth Via Inhibiting the Activation of HIF-1a and NFκB, and VEGF Expression.

1064 Background: Nanoparticle albumin-bound (nab-) paclitaxel (ABX) has shown greater efficacy and less toxicity than solvent-based paclitaxel (TAX) in xenograft models and clinical trials. The goal of this study was to determine the effects of VEGF modulation in human MDA-MB-231 breast tumor cell line and the effects of ABX and VEGF-neutralizing antibody bevacizumab (AVA) combination on the growth and metastasis of orthotopically implanted MDA-MB-231 tumors. Methods: VEGF expression was evaluated by ELISA in MDA-MB-231 tumor extract one week after treatment (qdx5) with saline, doxorubicin (10 mg/kg), TAX (10 mg/kg), or ABX (15 mg/kg). VEGF-receptor expression in MDA-MB-231 was quantitated by RT-PCR. MDA-MB-231 cytotoxicity with ABX, VEGF, AVA alone or in combination was measured by cytotoxicity and clonogenic assays. Implanted MDA-MB-231 tumors expressing luciferase were treated with saline, 2 cycles of ABX (10 mg/kg, two qdx5 cycles separated by 1 week, N=5) alone or in combination with AVA (2, 4 and 8 mg/kg, 2/wkx6). Tumor lymph node and pulmonary metastasis was determined by measuring luciferase activity. Results: Compared with saline, MDA-MB-231 tumors following chemotherapies exhibited significant tumor shrinkage (p≤0.006, t-test) and VEGF induction (p<0.0001, t-test). MDA-MB-231 was shown to express VEGFR2. Exogenous VEGF had a protective effect on MDA-MB-231 tumor cells by reducing cytotoxicity of ABX in both cytotoxicity and clonogenic assays. Sequestration of VEGF with AVA increased cytotoxicity of ABX in vitro. Treatment of MDA-MB-231 breast tumors with ABX and AVA combination resulted in greater than additive antitumor response and significantly reduced metastasis to the lungs (p=0.025 vs control) and LN (p=0.022) at the highest AVA dose. Conclusions: Chemotherapies induced VEGF expression in MDA-MD-231 breast tumor in vivo. In vitro, VEGF exerted a protective effect against ABX chemotherapy in VEGFR2-expressing MDA-MD-231 cells, which was abrogated by addition of AVA. In vivo, ABX and AVA combination significantly inhibited the metastatic potential of MDA-MB-231 tumor cells. These data provide a rational basis for the combination of nab- paclitaxel and bevacizumab in VEGF-receptor expressing tumors. [Table: see text]

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Oncometabolite succinate to promote angiogenesis by upregulating VEGF expression through GPR91-mediated STAT3 and ERK activation.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e23000 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e23000-e23000

Author(s):

Xianmin Mu ◽

Ting Zhao ◽

Che Xu ◽

Wei Shi ◽

Biao Geng ◽

...

Keyword(s):

Gastric Cancer ◽

Cancer Cells ◽

Structure Formation ◽

Tumor Angiogenesis ◽

Cancer Metabolism ◽

Vascular Endothelial ◽

Vegf Expression ◽

Vessel Formation

e23000 Background: Altered cellular metabolism is now generally acknowledged as a hallmark of cancer cells, the resultant abnormal oncometabolites cause both metabolic and nonmetabolic dysregulation and potential transformation to malignancy. A subset of cancers has been found to be associated with mutations in succinate dehydrogenase genes which result in the accumulation of succinate. However, the function of succinate in tumorigenesis remains unclear. In the present study, we aim to investigate the role of oncometabolite succinate in tumor angiogenesis. Methods: Succinate levels were measured in gastric cancer and paracancerous tissues as well as cell culture supernatants from normal cells and gastric cancer cells. Chemotactic motility, capillary structure formation and proliferation of primary human umbilical vascular endothelial cells (pHUVECs) were determined in the presence of succinate in vitro. Moreover, the vessel formation in zebrafish embryo was also used to examine the effect of succinate on angiogenesis. The activation of STAT3 and ERK signaling by succinate was checked by Western Blot. Results: Our data demonstrated the accumulation of markedly elevated succinate in gastric cancer tissues compared with that in paracancerous tissues. Moreover, succinate was able to increase the chemotactic motility, tube-like structure formation and proliferation of pHUVECs in vitro, as well as promote the blood vessel formation in transgenic zebrafish. Our mechanistic studies reveal that succinate upregulates vascular endothelial growth factor (VEGF) expression by activation of signal transducer and activator of transcription 3 (STAT3) and extracellular regulated kinase (ERK)1/2 via its receptor GPR91 in a HIF-1α independent mechanism. Conclusions: These data indicate an important role of the succinate-GPR91 axis in tumor angiogenesis, which may enable development of a novel therapeutic strategy that targets cancer metabolism.

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