Abstract 3274: VEGF─receptor antagonist, Sugen 5416, sensitizes pulmonary endothelial stem-like cells to estrogens: A microvascular model for the progression of lung cancer

Proliferative vascular lesions are an aggressive angiogenic phenotype associated with a poor prognosis in non-small cell lung cancer (NSCLC). Recent studies suggest that CD133+ endothelial stem-like cells are recruited to the angiogenic vascular system of NSCLC; and are associated with tumor stage and progression. Epidemiological studies have reported that women who received hormone replacement therapy (HRT) show an overall lower survival to lung cancer especially NSCLC when compared to women with no HRT. Proliferative vascular lesions have been studied extensively using the VEGF─receptor antagonist, Sugen 5416 (SU5416), plus chronic hypoxia (SuHx) rodent model. Therefore, the aim of this study was to determine whether SU5416 exposure of human pulmonary vascular endothelial cells (ECs) become more sensitive to estrogen-induced cell growth. We exposed human pulmonary endothelial cell line HPMEC-ST1.6R to SU5416 to select for a sub-population of cells which were then treated with 17β-estradiol and/or estrogenic polychlorinated biphenyl 153 (PCB153). We observed a significant increase of 2-3 fold change in cell growth and proliferation as determined by MTT, SRB, BrdU, and FACS analysis when SU5416 treated cells were exposed to estrogenic chemicals. Sugen 5416 treatment of ECs showed an increase in the inhibitor of DNA binding and differentiation protein 3 (ID3) along with stem cell markers CD133, Oct-4, and Sox-2. Immunohistochemistry of lung tissue samples from SuHx rodent model showed increased expression of ID3 in pulmonary vascular lesions that correlated with an increase in stem cell markers Oct-4 and Nanog; and increased VEGFR3+ cells surrounding vessel obliterating lesions from SuHx lung tissue. Our findings demonstrate that SU5416 sensitized cells to estrogens resulting in higher cell growth compared to control. Since VEGFR3 expression levels are reported to correlate with metastasis in NSCLC patients, our findings may be used as a model to study how VEGFR3 signaling can promote the aggressive growth and spread of lung cancer when exposed to estrogenic chemicals. Furthermore, we showed that stem cell markers Oct-4, Sox-2, and Nanog are inducible molecular targets of Sugen 5416 treatment. This finding is significant in that it points toward a potential mechanism of chemical-induced pluripotent stem-like cells. A better understanding of how vascular lesions depend on SU5416 may open new avenues for the prevention and treatment of lung cancer. The presence of stem cell markers does not imply that these cells actually function as stem cells. Instead, we propose that the combination of stem cell marker expression and chemical exposure to Sugen 5416 re-program terminally differentiated ECs to a pluripotent cell that gives rise to a clonal pulmonary vascular lesion that supports the aggressive growth of NSCLC. Citation Format: Mayur Doke, Quentin H. Felty. VEGF─receptor antagonist, Sugen 5416, sensitizes pulmonary endothelial stem-like cells to estrogens: A microvascular model for the progression of lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3274.