論文名稱:

染色體3q26-27 重要致癌基因在口腔癌之增幅與過度表現

 

The Amplification and Over-expression of Oncogenes at 3q26-27 in Oral Squamous Cell Carcinoma

研究生:

張筱清  Hsiao-Ching Chang

 

(以作者名查詢陽明大學館藏系統)

 

(以作者名查詢全國圖書書目資訊網)

指導教授:

張國威  Kuo-Wei Chang

        學位類別:

碩士

        學校名稱:

國立陽明大學

系所名稱:

口腔生物研究所

            學號:

39117005

          學年度:

92

          語文別:

中文

          出版年:

93

關鍵字:

口腔鱗狀上皮癌  OSCC

 

增幅  Amplification

 

染色體3q26-27  3q26-27

全文說明:

電子全文

        論文頁數:

70

摘要:

    近年來口腔癌的發生率和死亡率有逐漸增加的趨勢;雖然二十多年來對口腔癌的各種外科技術,化學藥物及放射線治療都有長足的進步,但口腔癌的存活率仍未見改善。患者治療後五年存活率和臨床分期有密切的關係,因此迫切的需要口腔癌的診斷及癌化機轉的了解。先前以比較基因雜合術 (Comparative genomic hybridization, 簡稱CGH) 分析口腔鱗狀上皮癌的染色體變化,其中發現在染色體3q尾端有明顯的變異,其中最小重疊區域在3q26-27。進一步以微陣列比較基因體雜合術 (Array-CGH) 發現,3q26-27上之TERCPIK3CATP63為基因增幅極高之基因座 (genomic loci),已知這些基因的改變在口腔癌有其重要性,若在口腔癌發展的各時期能發現相同的增幅,則可推測這些基因對口腔癌之癌化機轉有絕對關係。

 

    ZASC1為新近發現於食道鱗狀上皮癌常有增幅之潛在致癌基因,故本研究先以即時定量聚合酶連鎖反應(Q-PCR)來分析染色體 3q (主要為3q26-27)上的 TERCPIK3CAZASC1TP63 等重要致癌基因在細胞株、口腔鱗狀細胞癌與淋巴轉移組織的基因套數異常。結果顯示PIK3CAZASC1口腔鱗狀細胞癌與淋巴轉移經顯微擷取之組織中,分別佔有81% (37/46) 100% (12/12) 有顯著基因套數異常增幅的情形;再與臨床及病理資料交叉分析,其中PIK3CAZASC1基因增幅與患者是否有淋巴轉移顯著相關 (P<0.02-0.04)。在蛋白質表現上,我們利用免疫組織染色法觀察PIK3CA蛋白在49口腔鱗狀細胞癌、17組非癌配對組織、11組口腔癌前病變和7組淋巴轉移組織是否過度表現的情形。發現:PIK3CA在口腔癌組織其蛋白表現大多為強陽性;而在非癌配對組織和口腔癌前病變大多為陰性和弱陽性;口腔鱗狀上皮癌PIK3CA強陽性明顯高於非癌配對組織及口腔癌前病變(P<0.0001)。而在淋巴轉移部份,PIK3CA蛋白表現呈異質性。進一步觀察染色體3q26-27相關致癌基因在嚼食檳榔 (屬於高危險族群) 而未病變人們及口腔癌前病變 (大多為口腔白斑症)病人其口腔抹片之基因套數的變化。發現各基因在口腔癌前病變及口腔癌高危險群中增幅異常之發生率遠比在口腔鱗狀上皮癌低,但卻可以偵測的到。

 

    本研究中發現在口腔癌發展的各時期3q26-27致癌基因的漸近增幅支持著這些基因對於口腔癌的生成有重要的影響,而初步發現這些基因的增幅可望作為早期口腔癌篩檢之潛在標誌。

   
 

  In recent years, the incidence and mortality rate of oral squamous cell carcinoma (OSCC) have a gradual increasing trend. Although the technologies of surgery, chemical therapy and radiation therapy have improved, but survival rates of OSCC are still poor and have remained at the same level for over two decades. The 5-year survival rate of OSCC and clinic stage have a close relation ship. Therefore it is important to understand the molecular change and the application to diagnosis of OSCC. Using comparative genomic hybridization (CGH), it was found that the amplification of 3q end with minimal overlapping region is 3q 26-27. The advanced array-CGH studies also identified that TERC, PI3KCA and TP63 genes on 3q26-27 as gene loci highly amplified. These alterations were known in OSCC. However, if amplification of these genes is related to each stage of oral cancer development, then it is very likely that these oncogenes play an important role in oral tumorgenesis.

 

  ZASC1 is a novel proto-oncogene frequently amplificatied in esophageal squamous cell carcinomas. This study used the real-time PCR (quantitative PCR) to analyze the gene amplification of TERC, PIK3CA, ZASC1 and TP63 of chromosome 3q in oral cancer cell-lines, OSCC and lymph node metastasis tissues. The results indicated that PIK3CA and ZASC1 have frequent a gene mplification in microdissected OSCC and lymph node metastasis tissues (81% and 100%, respectively). A significant correlation was found between amplification of PIK3CA, ZASC1 and lymph node meatastasis (P=0.02-0.04). The expression of PIK3CA protein was investigated on tissue specimens from 49 OSCC, 17 non-matched cancer tissue (NCMT), 11 oral precancerous lesion (OPL) and 7 lymph node metastasis using immunohistochemistry. It was found that nearly 100% strong expression of PIK3CA in OSCC tissues, while negative or with low expression in NCMT and OPL tissues, respectively. There were significant differences between OSCC and NCMT or OPL (P<0.0001). Protein expression of PIK3CA In metastastic lesions was heterogeneous.

 

  To identify the DNA copy number changes of chromosome 3q26 -27 oncogenes in person had chew betel nut habit (high risk population for oral cancer, HRP) and OPL (we sampled the oral epithelial cell using buccal brush). It was found that these genes have low rate of DNA copy number amplification in OPL and HRP than in OSCC, but the amplification is detectable.

 

  In this study, It was identified copy number    amplification of 3q26-27 oncogenes is related to progression in oral cancer development. Besides, these genes copy number amplification will have potential in early stage of oral cancer as important biomarkers.