離胺酸氧化酶樣蛋白2於口腔鱗狀細胞癌中之表現

Expression of Lysyl Oxidase-Like Protein 2 in Oral Squamous Cell Carcinoma

陳里奈(Li-Nai Chen)

指導教授 ： 鄭世榮

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202200654

摘要

背景
離胺酸(lysyl oxidase, LOX)家族為分泌型蛋白，對細胞外間質(extracellular matrix, ECM)的交叉鏈結以及上皮-間質細胞轉換(epithelial-mesenchymal transition, EMT)有重大影響。所有LOX family成員中，離胺酸氧化酶樣蛋白2 (lysyl oxidase-like protein 2, LOXL2)在纖維化與癌化扮演最重要的角色。
過去研究顯示，LOXL2在纖維化疾病，例如肝硬化、肺纖維化、口腔黏膜下纖維化有增加。另外LOXL2表現量與許多癌症的預後呈現負相關，例如喉癌、乳癌、胃癌，及肺癌。
此研究重點在LOXL2於口腔鱗狀細胞癌(oral squamous cell carcinoma, OSCC)的表現，以及與各種臨床參數之間的關聯。
材料與方法
本研究利用LOXL2多株抗體進行免疫組織化學(immunohistochemistry, IHC)染色，探討LOXL2於98例OSCC及28例正常口腔黏膜(normal oral mucosa, NOM)中的表現，並以陽性染色指標(labeling index, LI)記錄其染色程度。利用、Student’s t-test、ANOVA、Kaplan-Meier存活分析以及Cox proportional hazard regression model來分析LOXL2的表現與OSCC患者臨床病理參數及存活率之相關性。
結果
細胞核中LOXL2的陽性染色指標在正常口腔黏膜的表現顯著高於OSCC標本(p=0.001)，而細胞質中LOXL2的陽性染色指標在則是在OSCC的表現顯著高於正常口腔黏膜(p-value<0.001)。
細胞質中LOXL2在OSCC標本的平均陽性染色指標為61%，在正常口腔黏膜則只有10%。另外，較高的細胞質LOXL2表現量出現於腫瘤大小較大(T3, 4)、有淋巴結轉移(N1-3)、癌症期別較後期(stage III, IV)、患者有嚼食檳榔之習慣者，具有統計學上顯著差異(Student’s t-test，p-value<0.05)
Kaplan-Mier存活分析顯示，當腫瘤大小較大(T3, 4)、有淋巴結轉移、細胞質LOXL2表現量高(LI>61%)時，有較低存活率(p-value<0.05)。
結論
在本研究中，細胞質內LOXL2表現量在OSCC中較大，而細胞核內LOXL2表現量則是在正常口腔黏膜較大。細胞質內LOXL2的LI和一些臨床病理參數(T status、N status、期別、嚼食檳榔與否)及存活時間有顯著相關。在OSCC病患中，較高的細胞質LOXL2表現量和較低存活率有關。根據上述結果，LOXL2可能作為預測OSCC的預後的指標。

關鍵字

離胺酸氧化酶樣蛋白2 ； 口腔鱗狀細胞癌 ； 交叉鏈結 ； 上皮-間質細胞轉換 ； 預後

並列摘要

Background
The lysyl oxidase (LOX) family is a group of secretory proteins and it contributes to crosslinking of extracellular matrix (ECM) and epithelial-mesenchymal transition (EMT). Among all proteins of the lysyl oxidase family, lysyl oxidase-like protein 2 (LOXL2) plays the most important role in fibrosis and carcinogenesis.
Previous researches showed upregulation of LOXL2 in fibrotic diseases such as liver cirrhosis, pulmonary fibrosis, and oral submucous fibrosis. Moreover, Cytoplasmic LOXL2 expression was positively correlated with cancer progression but nuclear LOXL2 expression inversely correlated with prognosis of several cancers including laryngeal cancer, breast cancer, gastric cancer, and lung cancer.
This research focused on expression of LOXL2 and its correlation with clinicopathological parameters in oral squamous cell carcinoma (OSCC).
Materials and Methods
In this study, 98 specimens of OSCC and 28 specimens of normal oral mucosa (NOM) were examined. Immunohistochemistry (IHC) stain using a LOXL2 polyclonal antibody was performed for detecting the cytoplasmic and nuclear expression of LOXL2 in these tissue sections. The degree of positive staining was recorded and graded as labeling index (LI). Finally, the correlations between expression of LOXL2 and clinicopathological parameters, or the overall survival of OSCC patients were statistically analyzed via Student’s t-test, ANOVA, Kaplan-Meier plots, and Cox proportional hazard regression model.
Results
LI of nuclear LOXL2 expression was significantly higher in NOM specimens than in OSCC specimens (p=0.001), but LI of cytoplasmic LOXL2 was significantly higher in OSCC specimens than in NOM specimens (p<0.001). The average LI of cytoplasmic expression of LOXL2 in OSCC specimens was 61%, in contrast to only 10% in NOM. In addition, there was significantly higher LIs of cytoplasmic expression of LOXL2 in larger tumor (T3-4), metastatic lymph nodes (N1-3), later clinical stage (Stage III-IV), and betel quid chewing habit (p<0.05).
Furthermore, Kaplan-Meier survival analysis showed that patients had shorter survival time in patients with advanced tumor sizes, nodal metastasis, and higher LIs of cytoplasmic LOXL2 expression (p<0.05).
Conclusions
In our research, the cytoplasmic expression of LOXL2 was higher in OSCC samples, while the nuclear expression of LOXL2 was higher in NOM samples. The labeling index of cytoplasmic expression of LOXL2 is significantly correlated with some clinicopathological parameters (T and N, stage, betel quid chewing) and survival time. OSCC patients with higher cytoplasmic expression of LOXL2 has significantly shorter overall survival. Therefore, we conclude that LOXL2 may be a valuable prognostic factor of OSCC patients.

並列關鍵字

LOXL2 ； oral squamous cell carcinoma ； crosslinking ； epithelial-mesenchymal transition ； prognosis

參考文獻

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