吲哚胺2,3-雙加氧酶蛋白在子宮頸癌幹細胞表現的調節機制研究

子宮頸癌是一種局部性、緩慢而逐漸進展的疾病，為全世界女性中第四大常見的癌症，並且根據國內衛生署統計，子宮頸癌在台灣婦科癌症中死亡率排名第十。越來越多的證據表明癌症幹細胞(cancer stem cells)是負責腫瘤的起始和維持，也被認為是癌症治療中亟需靶標的細胞群。吲哚胺2,3-雙加氧酶(indoleamine 2,3-dioxygenase 1, IDO1)是一種調控色胺酸的單鏈氧化還原酶，使色胺酸代謝成犬尿胺酸等具有免疫抑制活性的產物，這些產物能抑制T細胞的生長，使腫瘤微環境呈現免疫抑制。Notch1主要是調控胚胎發育或成體組織中自我更新、細胞增生及分化，近幾年的研究指出Notch1的過度表現會降低癌細胞對放射線的敏感性。本研究的目的為探討子宮頸癌癌幹細胞內IDO1的表現與其調控之分子機制。首先我們透過癌症球體培養的方式，將子宮頸癌細胞培養成具有幹細胞特性的子宮頸癌症球體，接著經由西方點墨法的結果發現，子宮頸癌症球體中IDO1蛋白和Notch intracellular domain (NICD)蛋白的表現增加，同時子宮頸癌癌症球體細胞內，IDO1的活性確實較一般子宮頸癌細胞明顯增加，並且發現子宮頸癌癌症球體的條件式培養液，更有效降低Jurkat T細胞的增生。我們進一步發現敲落子宮頸癌細胞中Notch1基因的表現後會降低IDO1的表現，而抑制IDO1基因表現後也會降低NICD的表現，顯示兩者具有相互調控的機制。此外，具放射線抗性的子宮頸癌細胞內，其IDO1的表現與Notch1路徑的活化情形增加，當抑制IDO1的表現則會增加子宮頸癌細胞對放射線的敏感性。我們的研究結果顯示Notch1所活化的IDO1在子宮頸癌中具有非免疫調節的活性並且可能促使抗放射線治療的情況發生。

關鍵字

吲哚胺2,3-雙加氧酶蛋白

並列摘要

Cervical cancer is a disease with a partial, slow and gradual progression and is the fourth common cancer in female around the world.According to the statistical data from the Department of Health and Statistics,the mortality of cervical cancer is ranked as tenth in Taiwanese female. There are evidences suggesting that cancer stem cells (CSCs) are responsible for the initiation, maintenance, drug resistance and metastasis of tumors and these particular cancer cellsare considered as an urgent target in future cancer therapy. Indoleamine 2,3-dioxygenase 1 (IDO1) is a single chain oxidoreductase that catalyzes tryptophan metabolizing to kynurenineand plays a role in immunosuppressive microenvironment within cancers through diminishing T cell activation.Notch1 playsan important role in development and determination of cell fate. The recent study shows that theoverexpression of Notch1 in cancer cells will lead to decreasing radiation sensitivity. The purpose of this study is to explore the molecular mechanism in regulating of IDO1 expression in cervical CSCs.We first found that the IDO1, as well as Notch intracellular domain (NICD) was increased in tumorsphere cells derived from human cervical cancer cells by western blot analysis. Using the IDO1 activity assay, we also found that the IDO1 activity in total cell lysates was significantly increased in cervical tumorsphere cells than those of parental counterparts. Using Jurkat T cellsas a model, the growth rate of T cells was significantly decreased in conditional medium after cervicaltumorsphere cultivation when compared to those from parental adherent culture. In addition, wefound that knockdown of Notch1 decreasedIDO1 expressionin SiHa cervical cancer cells, and vice versa.In addition,IDO1 expression and the activation of Notch1 pathway was increased in radioresistant cervical cancer cells. The knockdownof IDO1enhanced the sensitivity of SiHa cervical cancer cells to radiation treatment.Our results suggest that IDO1 activated byNotch1in cervical cancermay displaya non-immune regulation role during cancer progression.We hope these results will provide new insights in the development of immunotherapy in against cervical cancer.

並列關鍵字

IDO1

參考文獻

1. Ferns, D.M., Kema, I.P., Buist, M.R., Nijman, H.W., Kenter, G.G., and Jordanova, E.S. (2015). Indoleamine-2,3-dioxygenase (IDO) metabolic activity is detrimental for cervical cancer patient survival. Oncoimmuno. 4, e981457.

2. Gu, W., Yeo, E., McMillan, N., and Yu, C. (2011). Silencing oncogene expression in cervical cancer stem-like cells inhibits their cell growth and self-renewal ability. Cancer Gene Ther 18, 897-905.

3. Hou, T., Zhang, W., Tong, C., Kazobinka, G., Huang, X., Huang, Y., and Zhang, Y. (2015). Putative stem cell markers in cervical squamous cell carcinoma are correlated with poor clinical outcome. BMC Cancer 15, 785.

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5. Korkaya, H., Liu, S., and Wicha, M.S. (2011). Breast cancer stem cells, cytokine networks, and the tumor microenvironment. J Clin Invest 121, 3804-3809.

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吲哚胺2,3-雙加氧酶蛋白在子宮頸癌幹細胞表現的調節機制研究

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