脂联素与子宫内膜癌发生和发展的在体研究

Adiponectin (APN) is an endogenous collagen-like protein that is exclusively expressed and secreted by adipocytes. Blood levels of adiponectin are paradoxically lower in the obese than in normal and lean individuals. Clinical studies indicate that there is an inverse correlation between human blood APN levels and the incidence as well as progress of endometrial carcinoma, breast cancer, colon cancer, and prostate cancer. Interestingly, obesity also elevates the risk of development of these cancers, particularly endometrial carcinoma. Our previous cellular studies have shown that adiponectin directly inhibits human endometrial cell proliferation and induced their apoptosis. However, the direct in vivo evidence that adiponectin deficiency promotes the development of endometrial carcinoma is still sorely needed. Such in vivo evidence will be critical to defining a completely new aspect of adiponectin function in preventing cancer growth. To address this issue, we deployed adiponectin knockout (APN KO) mice to investigate the impact of adiponectin deficiency on an estrogen analog (DES)-induced endometrial carcinogenesis as well as on the development of endogenous endometrial carcinoma in the heterozygotic deficiency of tumor suppressor gene, PTEN(+/-). In the latter model, we have created APN(-/-);PTEN(+/-) or APN(+/-);PTEN(+/-) double genetic knockout mice. After DES-treatment, we have observed sharply elevated endometrial gland hyperplaysia with some showing atypical hyperplasia. Through these designed research, we will be able to definitively define adiponectin-deficiency as a primary cause of endometrial carcinoma. Furthermore, we will reveal systematically the signaling pathways underlying these phenotypes. Our studies will also help to establish adiponectin-deficiency as a crucial molecular link between obesity and increased risk of certain types of malignancy, such as breast cancer, colon cancer, and prostate cancer; they may help lay the foundation of using adiponectin levels as one of the early diagnostic markers of these cancers.

脂联素是由脂肪细胞特异表达并分泌的多肽激素,其血液水平随着肥胖的发生反而下降。临床研究表明，脂联素水平的降低与子宫内膜癌、乳腺癌，前列腺癌等癌症的高发密切相关，而肥胖也增强这些癌症的风险。我们的研究显示：脂联素可抑制子宫内膜癌细胞的增生并促进其凋亡。尽管有临床和细胞水平的研究，国内外还缺乏相应动物模型的在体研究，因而还无法确定脂联素的降低是否是直接促进这些癌症发生。此研究将利用分子遗传学手段解决这个问题。在脂联素基因敲除小鼠模型上，我们进一步引入了抑癌基因PTEN单敲除小鼠，形成独特的PTEN+/-;APN-/-子宫内膜癌症发生模型。我们也在脂联素基因敲除雌鼠上，研究雌激素类似物－乙烯雌酚诱导子宫内膜癌的发生和发展的机制。通过这些研究，我们将确立脂联素的缺失是子宫内膜癌发生的重要原因之一，并揭示相应的分子机制。此研究也将脂联素水平的降低作为子宫内膜癌的前期诊断标准提供理论依据。

脂联素（APN）是由脂肪细胞特异分泌的内源性多肽，临床研究证明脂联素水平的降低与子宫内膜癌、乳腺癌等癌症的高发密度相关，而抑癌基因Pten的突变和缺失是导致子宫内膜癌发生的重要原因之一。本课题在脂联素基因敲除小鼠模型（APN-/-）上，通过与Pten杂合子(Pten+/-)小鼠杂交，构建出PTEN+/-;APN-/-子宫内膜癌发生模型，在此模型基础上我们通过蛋白免疫印迹、免疫组织化学以及酶联免疫吸附测定等方法检测各基因型小鼠中PAX2、Ki-67、p-Erk等子宫内膜癌相关分子标志蛋白的含量，发现脂联素缺失可协同Pten缺失促进子宫内膜癌的发生发展，而这一发生是通过MAPK p-44/42信号通路的活化来刺激子宫内膜腺体细胞的过度增殖。同时，我们还在脂联素缺失的情况下，研究了脂联素对雌激素类似物－己烯雌酚（DES）诱导子宫内膜癌的发生和发展的影响，发现脂联素缺失可以提高子宫内膜对雌激素的敏感性。此外，我们还观察到子宫内膜癌细胞在脂联素缺失的裸鼠上生长更不容易受到抑制，证明了脂联素对子宫内膜癌发生发展具有直接的抑制作用。本课题在国内外首次利用脂联素缺失小鼠模型来研究脂联素在子宫内膜癌发生发展中的抑制作用，为脂联素作为子宫内膜癌诊断和治疗的分子标志物提供了直接的证据和理论依据。在此项目执行期间，研究成果发表了论文12篇。其中含在国际专业权威SCI期刊（如Endocrinology, Molecular Endocrinology, JCI, Cellular Physiology and Biochemistry等）上发表论文8篇，核心期刊发表4篇。通讯作者两篇，共同通讯或第一作者4篇，共同作者6篇。另外有两篇文章在投。