以HIF-1为靶点的新型小分子化合物在乳腺癌中的抗肿瘤作用机制研究

Breast cancer is the most common type of cancer, and the second leading cause of cancer deaths, in women.Intratumoral hypoxia, a frequent finding in breast cancer, results in the activation of hypoxia-inducible factors (HIFs). HIFs are implicated in many steps of breast cancer metastasis.The hypoxia-inducible factor-1 (HIF-1) is a critical regulator of breast cancer response to hypoxia that include increased angiogenesis, glycolytic metabolism, and resistance to chemotherapy and radiation. LXY6006 was obtained by the structural modification and optimization of manassantin A as a high potent HIF-1 inhibitor. Antitumor activity and mechanisms of LXY6006 were observed in this study. LXY6006 showed more sensitive inhibition activity to HIF-1 than that of Manassantin A using reporter gene assay (>100 folds). It showed potent inhibition on the growth of human breast cancer cell lines. LXY6006 exhibited significant antitumor activity against established human tumor xenografts in nude mice with treatment of MX-1 breast cancer and MX-1/Taxol. Further more, the HIF-1 inhibition and antitumor mechanism needs to be studied.The relationship between the expression level of HIF-1 and the metastasis of breast cancer will be processed using HIF-1 knockdown method. The objective of this study is to indicate that LXY6006 is an attractive anti-breast cancer agent as an HIF-1α targeting inhibitor.

乳腺癌是女性排名第一的常见恶性肿瘤。而几乎所有的乳腺癌都包含有缺氧区域。缺氧诱导因子-1(HIF-1）作为其中关键的转录因子，能激活大量基因的表达，使乳腺肿瘤适应缺氧环境，包括肿瘤血管新生，肿瘤侵袭转移，放化疗耐受。因此以HIF-1为靶点的小分子靶向药物的研究无疑为乳腺癌和难治性乳腺癌的治疗提供新的有效途径。我们在前期的研究中已经证实新型三白草脂素-8衍生物LXY6006能特异性抑制HIF-1活性和抑制多种乳腺癌细胞的生长，并且在动物水平能有效抑制乳腺肿瘤的生长。在本研究中，我们将LXY6006作为先导化合物，在评价其体内外抗肿瘤药效学的同时，着重研究其对HIF-1活性抑制的作用机制和对乳腺癌细胞的抗肿瘤作用机制，进一步将通过基因敲除技术研究HIF1表达量和乳腺细胞侵袭转移能力的关系，以期发展新的小分子乳腺癌靶向药物，为乳腺癌特别是难治性乳腺癌提供新的治疗方法。

微环境缺氧是实体瘤发生发展中持续存在的重要病理特征之一。缺氧诱导因子-1（HIF-1）是调控缺氧效应的关键核转录因子，在很多实体瘤中都持续高表达，是国际上目前比较热门的抗肿瘤药物研究靶点。但是HIF-1抑制剂的研发总体还处于起步阶段，至今尚没有上市的药物，并且针对HIF-1抑制剂的敏感瘤谱及其作用机制的研究也不完善。在前期的研究中我们已经发现一个强效的HIF-1抑制剂LXY6006，在本研究中，我们进一步发现LXY6006对乳腺癌相对敏感，并且对不同乳腺癌细胞株的生长抑制作用与细胞HIF-1α的表达成正相关。通过体外的克隆形成、血管新生，transwell等实验均证实LXY6006对乳腺癌具有较好的抗肿瘤作用。通过对其作用机制的详细研究证实LXY6006最终是通过促进HIF-1α蛋白的降解和抑制HIF-1α和P300蛋白相互作用这两个方面来同时抑制HIF-1的活性。最终我们在裸鼠皮下移植瘤试验中进一步证实了LXY6006的抗乳腺癌作用和机制。本研究完整的阐述了LXY6006的作用机制和体内外抗乳腺癌的效果，为创制小分子HIF-1抗肿瘤靶向药物奠定一定基础。

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