利用系統性體外研究方法鑑定腫瘤抑制基因與 EGFR-TKI抗藥性基因

Abstract

肺癌是世界各地導致死亡人數最多的癌症。我們藉由微陣列生物晶片去比較一群具有不同侵襲能力的肺腺癌細胞株之轉錄本之差異，發現一個新穎的腫瘤抑制基因，FAM198B，它是在人類研究中從未被報導過的基因。我們發現在臨床肺腺癌病人中，具有高度表現FAM198B轉錄本之病人組別，其整體存活期較低表現FAM198B轉錄本之病人組別來的長。在體外細胞實驗中發現，高度表現FAM198B可以抑制細胞侵襲、移動、生長速度、與非接觸性貼附生長；並且體內動物實驗也證實FAM198B能抑制老鼠腫瘤之生長與轉移。此外，我們發現FAM198B是屬於N醣基化蛋白質，其第 98與289號胺基酸為其醣基化位點。藉由去醣基化實驗可證實醣基化能延長FAM198B蛋白質的半衰期並且抑制腫瘤轉移。進一步利用生物晶片及生物途徑分析FAM198B抑制腫瘤轉移的機制，是透過抑制下游细胞外信號调節蛋白激酶（ERK）與基質金屬蛋白酶-1(MMP-1)的表現。總結以上結果，我們可以證實FAM198B具有抑癌基因的能力，並且本研究可以提供在癌症診斷與治療上一個全新的思維。

Metastasis is a major cause of cancer-related death. Here, we identify a novel tumor suppressor gene, FAM198B, which has never been characterized in humans previously, by comparing the transcriptional profiles of a high metastatic lung adenocarcinoma cell line and its isogenic low metastatic cell line. The high expression of FAM198B was associated with favorable survival in lung adenocarcinoma patients. Enforced expression of FAM198B suppressed cell invasion, migration, mobility, proliferation and anchorage-independent growth in vitro and reduced tumor growth and metastasis in in vivo mouse models. Additionally, we found that FAM198B is an N-glycosylated protein with two extracellular N-linked glycosylation sites (Asn98 and Asn289). Deglycosylation nearly eliminated the metastasis suppression activity of FAM198B due to a decrease in stability. A microarray analysis was used to examine the underlying mechanism of FAM198B in metastasis suppression and identified MMP1 as a critical downstream target of FAM198B. The FAM198B-mediated MMP-1 downregulation was via inhibition of the phosphorylation of extracellular signal-regulated kinase (ERK). Taken together, these results indicate that FAM198B acts as a tumor suppressor to inhibit cancer cell invasion and metastasis via the ERK/MMP1 signaling pathways and may serve as a potential therapeutic target for lung adenocarcinoma.