人類腫瘤抑制基因在肺細胞老化之研究

The role of a potential tumor suppressor in premature cellular senescence in a primary lung fibroblast cell line, WI-38

邱有朋(You-Pen Chiu)

指導教授 ： 顏伯勳

國立臺灣大學/醫學院/生物化學暨分子生物學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.10867

摘要

肺癌是由於肺組織中不受控制的細胞增生所引發的疾病。基於早期診斷的困難度以及不良預後的結果，肺癌平均的五年後存活率約只有15%，且每年造成約一百三十萬人死亡。LCTS1是一個轉錄因子（transcriptional factor）。因為LCTS1亦在肺細胞中表現，且在本實驗室先前的研究中，LCTS1的過度表現抑制了肺癌細胞株的發展（progression）。因此我們推測LCTS1在肺癌中依然是個腫瘤抑制者。為研究LCTS1在肺癌所扮演的角色，我們在無突變的正常肺細胞株中造成LCTS1的功能喪失來探討LCTS1的功能。我們在人類肺纖維細胞株WI-38中引進調控LCTS1之小髮夾核醣核酸（short hairpin RNA）慢病毒，造成LCTS1表現降低。LCTS1表現降低並無造成惡性轉化（malignant transformation）; 但替代地，我們觀察到細胞型態上的改變，並經由細胞衰老β-半乳糖苷酶染色（senescence-associated β-galactosidase staining）證明其與細胞老化相關的生長制止（growth arrest）現象有關。本研究亦發現p53蛋白的總量和磷酸化的增加，推論細胞的衰老表徵是經由p53受去氧核醣核酸損壞反應的調控所引起。此外，衰老細胞內下游蛋白p21的表現量與RB蛋白的磷酸化亦受到影響。我們的發現顯示LCTS1是一個有潛力的腫瘤抑制者，其功能喪失會造成去氧核醣核酸損壞的壓力並因此導致細胞的衰老。

關鍵字

肺癌 ； 細胞老化 ； p53

並列摘要

Lung cancer is characterized as a disease caused by uncontrolled cell growth that occurs in lung tissue. The overall five-year survival rate for lung adenocarcinoma is probably 15% due to the difficulty of early diagnosis and the worse outcome of therapy, and the disease is responsible for about 1.3 million deathsannually.LCTS1(Lung Cancer Tumor Suppressor 1) is a transcriptional factor that is also expressed in lung, and the previous study in our lab demonstrated that overexpression of LCTS1 inhibits the progression of lung cancer cell lines. Therefore, we speculate that LCTS1 also functions as a tumor suppressor in the lung. To investigatethe roles of LCTS1 in lung cancer, we modeled loss of function of LCTS1 in the normal lung cell line. We knocked down LCTS1 by lentivirus-mediated introduction of LCTS1shRNA in WI-38, a human lung fibroblast cell line, and demonstrated that LCTS1 knockdown didn’t cause malignant transformation and, instead, the cell with LCTS1 knockdown showed morphologic change and growth arrest corresponded with cellular senescence that was proved by senescence associated β-galactosidase staining. Moreover, thelevels of expression and phosphorylation of p53 were up-regulated, suggesting that senescent phonotype was mediated by p53, which is induced by DNA damage response. The studies also revealed that the levels of p21expression as well as RB phosphorylation were changed in the senescent cells. Our findings suggest that LCTS1is a potential tumor suppressor and loss of which contributes to oncogenic stress thereby cells become senescent.

並列關鍵字

lung cancer ； cellular senescence ； p53

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