Saha Akata, Nandi Partha, Dasgupta Shayani, Bhuniya Avishek, Ganguly Nilanjan, Ghosh Tithi, Guha Ipsita, Banerjee Saptak, Baral Rathindranath, Bose Anamika
Department of Immunoregulation and Immunodiagnostics, Chittaranjan National Cancer Institute (CNCI), Kolkata, India.
Front Oncol. 2020 Mar 6;10:260. doi: 10.3389/fonc.2020.00260. eCollection 2020.
Neem Leaf Glycoprotein (NLGP) is a natural immunomodulator, have shown sustained tumor growth restriction as well as angiogenic normalization chiefly by activating CD8 T cells. Here, we have investigated the direct role of NLGP as a regulator of tumor microenvironmental hypoxia and associated vascular endothelial growth factor (VEGF) production. We observed a significant reduction in VEGF level in both murine tumor and cancer cells (B16Mel, LLC) and macrophages after NLGP treatment. Interestingly, NLGP mediated VEGF downregulation in tumor cells or macrophages within hypoxic chamber was found at an early 4 h and again at late 24 h in mRNA level. Our data suggested that NLGP prevented hypoxia-induced strong binding of HIF1α with its co-factors, CBP/p300 and Sp3, but not with Sp1, which eventually limit the binding of HIF1α-transcriptional complex to hypoxia responsive element of VEGF promoter and results in restricted early VEGF transcription. On the otherhand, suppressed phosphorylation of Stat3 by NLGP results reduction of HIF1α at 24 h of hypoxia that further support sustained VEGF down-regulation. However, NLGP fails to regulate VHL activity as observed by both and studies. Therefore, this study for the first time reveals a mechanistic insight of NLGP mediated inhibition of angiogenesis by suppressing VEGF, which might help in vascular normalization to influence better drug delivery.
印楝叶糖蛋白（NLGP）是一种天然免疫调节剂，主要通过激活CD8 T细胞显示出持续的肿瘤生长抑制以及血管生成正常化作用。在此，我们研究了NLGP作为肿瘤微环境缺氧和相关血管内皮生长因子（VEGF）产生调节剂的直接作用。我们观察到，NLGP处理后，小鼠肿瘤、癌细胞（B16Mel、LLC）和巨噬细胞中的VEGF水平均显著降低。有趣的是，在缺氧箱内的肿瘤细胞或巨噬细胞中，NLGP介导的VEGF下调在mRNA水平上于早期4小时出现，在晚期24小时再次出现。我们的数据表明，NLGP可阻止缺氧诱导的HIF1α与其辅因子CBP/p300和Sp3强烈结合，但不与Sp1结合，这最终限制了HIF1α转录复合物与VEGF启动子缺氧反应元件的结合，导致早期VEGF转录受限。另一方面，NLGP抑制Stat3磷酸化导致缺氧24小时时HIF1α减少，这进一步支持了VEGF的持续下调。然而，如 和 研究所观察到的，NLGP未能调节VHL活性。因此，本研究首次揭示了NLGP通过抑制VEGF介导血管生成抑制的机制，这可能有助于血管正常化以影响更好的药物递送。
