- 學位論文
HER2及其相關路徑在黏液性卵巢癌的相關研究
Investigation of HER2 expression and HER2 related pathway in ovarian mucinous carcinoma
摘要
卵巢癌為婦科癌症的第二位，在婦癌中發生率僅次於子宮頸癌，由於卵巢位於骨盆腔，初期症狀不明顯，難以提早發現；且沒有如子宮頸癌一樣有適當的篩檢工具，診斷時通常較為晚期。卵巢癌最常見的為上皮性癌，其中又可依組織學分類分為漿液癌，黏液癌，類子宮內膜癌及亮細胞癌。黏液癌根據其分子基因的致病機轉為第一型卵巢癌(基因相對穩定，少有p53突變)。第一型占約上皮性卵巢癌的25%，通常腫瘤細胞長的較慢，診斷時通常腫瘤還侷限在卵巢，但一旦擴散出去對化療的反應較不好。針對第一型對化療反應不好的卵巢癌，標靶治療可能是其治療的方向。 之前研究顯示，屬於第一型卵巢癌的黏液癌有HER2的過度表現(8-66%)，而針對HER2的標靶治療藥在治療乳癌及胃癌已有顯著的成效，HER2路徑的相關研究也許可提供黏液癌的治療方向。本研究使用49例亞洲女性黏液癌組織晶片進行HER2免疫組織化學染色及HER2螢光原位雜交，利用ToGA的判讀方式判讀，HER2陽性率為20.4%，HER2蛋白表現與HER2基因擴增結果的一致性達97.56%，HER2基因數目的擴增與HER2蛋白表現的強度有正相關(P<0.001)，且不論HER2基因數目是否有經過染色體17(cep17)數目校正，HER2免疫染色的結果與cep17 校正前的HER2基因數及校正後的HER2/cep17比值，皆成正相關(ρ = 0.630, P < 0.001; ρ = 0.558, P<0 .001)。另外有21例個案做HER2、KRAS、 BRAF及PIK3CA基因分析，其中33.3%有HER2基因突變，61.9%有KRAS基因突變，80.0%有BRAF基因突變，0% PIK3CA基因突變；HER2基因擴增同時有HER2基因突變有14.29%，HER2基因擴增同時有KRAS基因突變有9.52%；50.0%同時有BRAF及KRAS基因突變，4.76%同時有KRAS，HER2及BRAF基因突變。 此研究顯示使用ToGA判讀標準，HER2免疫組織化學染色可有效找出HER2過度表現的卵巢黏液癌，單看HER2基因數或是經染色體17(cep17)數目校正，都可用來評估黏液癌的HER2基因狀態，且HER2基因擴增可合併有HER2基因，KRAS基因或BRAF基因突變，這暗示RAS路徑雙活化突變在卵巢黏液癌是一重要路徑。此結果可提供臨床試驗將anti-HER2標靶治療及抑制RAS路徑藥物治療應用於HER2陽性卵巢黏液癌病人的研究方向。
並列摘要
HER2 gene amplification and protein over-expression are important factors in predicting clinical sensitivity to anti-HER2 therapies in breast, gastric or gastroesophageal junction cancer patients. The aim of this study was to evaluate the correlation between HER2 gene copy numbers and HER2 protein expressions in mucinous epithelial ovarian cancer (EOC). Of the 49 tissue microarray samples of mucinous EOC, we applied 2010 ToGA trial (Trastuzumab for Gastric Cancer) surgical specimen scoring criteria to analyze the HER2 protein expression by an immunohistochemistry (IHC) test and the HER2 gene amplification by the fluorescence in situ hybridization (FISH) test. We achieved a high overall concordance of 97.56% between nonequivocal HER2 results by IHC and FISH tests. In addition, HER2 gene copies before chromosome-17 correction increased significantly in a stepwise order through the negative, equivocal and positive IHC result categories (P<0 .001), as did the HER2 gene copies after chromosome-17 correction (P <0 .001). On the other hand, HER2 IHC results correlated significantly with both chromosome-17–uncorrected HER2 gene copy numbers (ρ = 0.630, P<0.001) and chromosome-17 corrected HER2 gene copy numbers (ρ = 0.558, P <0.001). We use direct sequencing for gene analysis.The HER2 gene, KRAS gene, BRAF and PIK3CA gene mutation rate is 33.3%, 61.9%, 80.0% and 0% respectively. Concurrent HER2 amplification and HER2 gene mutation rate was 14.29% and concurrent HER2 amplification and KRAS gene mutation rate was 9.52%. Co-occurrence rate of BRAF and KRAS gene mutation is 50.0 %. One case (4.76%) had KRAS, HER2 and BRAF gene mutation. We concluded that both chromosome-17 corrected and uncorrected HER2 gene copies correlated significantly with HER2 IHC results. Tests for the HER2 gene copies per tumor cell either before or after correction of chromosome-17 can be applied as a potentially valuable tool to analyze the HER2 status in mucinous EOC. Double activating mutation of RAS pathway was detected in mucinous EOC and anti-HER2 therapy or anti-RAS pathway therapy maybe a possible treatment choice of HER2 positive mucinous EOC.