TERT啟動子突變與GATA3、CK20、CK5/6及p53之表現於膀胱泌尿上皮腫瘤之生物學意義

Biological Significance of TERT Promoter Mutation and Expression of GATA3, CK20, CK5/6 and P53 in Urothelial Neoplasm of the Urinary Bladder

王中傑(Chung-Chieh Wang)

指導教授 ： 鄭永銘

國立臺灣大學/醫學院/病理學研究所/博士(2020年)

https://doi.org/10.6342/NTU202000056

摘要

膀胱泌尿腫瘤是泌尿科的常見疾病，而其治療主要依據為腫瘤分期與形態學上的分化程度。近期分子病理研究發現了不少重要的腫瘤生物標記，但它們尚未被整合到臨床的治療指引中。本篇論文包含兩部分，分別闡述相關標記於兩類膀胱泌尿腫瘤中的生物學意義：早期的低度非侵襲性泌尿上皮腫瘤，以及晚期的肌肉侵犯性膀胱癌(MIBC)。
在第一部分，我們在低度非侵襲性泌尿上皮腫瘤檢測TERT、FGFR3及HRAS三種基因的突變狀態，並分析其預後意義。TERT基因之啟動子突變在膀胱癌頗為常見，但是在低惡性度乳突狀泌尿上皮腫瘤(PUNLMP)的相關資料並不多。本研究中，我們收集了21例良性之倒生性乳突瘤、30例PUNLMP，以及34例低度非侵襲性乳突狀泌尿上皮癌(NIPUC)。TERT基因之啟動子突變出現於10 (33%)例之PUNLMP與17 (50%)例之低度NIPUC，但未出現於倒生性乳突瘤。相對於倒生性乳突瘤，PUNLMP與低度NIPUC較常出現FGFR3基因之突變(p = 0.009)，HRAS基因突變則較為少見(p < 0.001)。在預後方面，PUNLMP病例有TERT啟動子突變者較容易復發(p = 0.024)，但是低度NIPUC並無此現象(p = 0.530)。此外，PUNLMP病例有TERT啟動子突變者，其復發率與低度NIPUC無顯著差異(p = 0.487)。
在第二部分，我們分析了GATA3、CK20、CK5/6及p53在MIBC的表現與其生物學意義。近期基因研究將MIBC區分為數種子分類，而上述之免疫組織化學染色(IHC)標記與這些子分類有關。其中，GATA3與CK5/6分別被視為管腔型與類基底-鱗狀型的代表性標記；p53染色常被用於代替TP53基因突變檢測，而傳統上一般將細胞核染色比例高者視為異常。本研究共收集了91名MIBC病人的膀胱全切除術組織檢體。在這些病例中，GATA3表現量較低及CK20陰性者，其Ki-67增殖指數較高(p值分別為0.006與0.002)。相對地，CK5/6呈廣泛性表現者，Ki-67增殖指數較高(p = 0.001)。P53染色則有三種類型與高Ki-67指數相關：完全陰性、廣泛的細胞核強染色，以及廣泛的細胞質強染色。此外，CK20與CK5/6的染色結果通常呈現互補關係，但91例中的13例(14.29%)同時有廣泛的GATA3與CK5/6表現。在78名未接受術前化學治療的病人裡，GATA3表現量較低者於單變項與多變項分析均有顯著較高的復發率(p值分別為0.008與0.002)。CK20、CK5/6及p53的表現則與預後無關。
總結來說，根據我們的研究結果，TERT基因的啟動子突變可做為PUNLMP病人的預後標記。在MIBC病患，GATA3的表現量則可做為膀胱切除術後的復發危險性指標。此外，由Ki-67增殖指數的關聯性來看，以前述三種染色類型做為判斷p53染色異常的標準，應比傳統上的核染色比例準則更佳。

關鍵字

膀胱癌 ； 泌尿上皮腫瘤 ； TERT啟動子 ； GATA3 ； CK20 ； CK5/6 ； p53

並列摘要

Clinical management of bladder urothelial neoplasm depends mainly on the tumor stage and grade. Recent advances in molecular pathology discovered several essential biomarkers, and their value in clinical application warrants investigation. In our study, we focused on the relevant biomarkers in two separate fields of bladder tumors: the early low-grade noninvasive papillary urothelial neoplasm, and the advanced muscle-invasive bladder cancer (MIBC).
In the first part, we investigated the mutation status of the TERT promoter, FGFR3 gene, and HRAS gene in low-grade papillary urothelial neoplasms and evaluated their prognostic significance. Mutations in the promoter region of the TERT gene have been frequently found in urothelial carcinoma of the urinary bladder, but related data for papillary urothelial neoplasm of low malignant potential (PUNLMP) are limited. In our study, we included 21 cases of inverted papillomas, 30 PUNLMPs, and 34 low-grade noninvasive papillary urothelial carcinomas (NIPUCs). TERT promoter mutations were observed in 10 (33%) PUNLMPs and 17 (50%) low-grade NIPUCs, but not in any inverted papilloma. FGFR3 mutations were more frequently observed in PUNLMP and low-grade NIPUC than in inverted papillomas (p = 0.009), whereas the opposite trend was noted for HRAS mutations (p < 0.001). Regarding the clinical outcome, TERT promoter mutation was associated with a higher recurrence rate in PUNLMP (p = 0.024) but not in low-grade NIPUC (p = 0.530). Notably, PUNLMP cases with TERT promoter mutations had a similar recurrence rate to that in low-grade NIPUC cases (p = 0.487). Our results suggest that the status of the TERT promoter mutation may serve as a biomarker of prognostic stratification in patients with PUNLMP.
In the second part, we investigated the biological and prognostic significance of GATA3, cytokeratin (CK) 20, CK5/6 and p53 in MIBCs from 91 patients who underwent radical cystectomy. Genetic profiling studies on muscle-invasive bladder cancers (MIBCs) have discovered several subtypes with different biological characteristics, and these markers were found to be associated with the molecular subtypes. According to our results, high Ki-67 indices were associated with negative CK20 (p = 0.002) and diffuse CK5/6 (p = 0.001) staining. By contrast, tumors with diffuse GATA3 expression had low Ki-67 index (p = 0.006). Regarding p53, three staining patterns were associated with a high Ki-67 index: (1) complete absence, (2) diffusely strong nuclear reactivity, and (3) diffusely strong cytoplasmic staining (p < 0.001 compared with other patterns). CK5/6 and CK20 expression was typically present in a reciprocal fashion; however, diffuse GATA3 and CK5/6 coexpression was observed in 13 (14.29%) cases. Among 78 chemotherapy-naïve patients, low GATA3 staining was associated with worse recurrence-free survival in both univariate (p = 0.008) and multivariate analyses (p = 0.002). CK20, CK5/6, or p53 expressionwas not associated with clinical outcome. Based on our results, IHC staining for GATA3 may help risk stratification in patients with MIBC receiving radical cystectomy. In addition, the differences in Ki-67 indices suggested that aberrant p53 expression was better defined by the three aforementioned patterns, rather than percentage of nuclear staining alone.

並列關鍵字

Bladder cancer ； urothelial neoplasm ； TERT promoter ； GATA3 ； cytokeratin 20 ； cytokeratin 5/6 ； p53

參考文獻

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