人類口腔黏膜癌前期病灶惡性轉變為口腔癌及抑制細胞自戕家族(IAP family)於口腔癌化表現與p53及外基因(epigenetics)之研究

A study of malignant transformation in Patients with potentially malignant oral mucosal disorders and the expression of inhibitors of apoptosis (IAP) family in oral carcinogenesis and its implication with p53 and epigenetics

薛水上(Shui-sang Haue)

指導教授 ： 林立民

高雄醫學大學/口腔醫學院/牙醫學研究所/博士(2007年)

摘要

一般認為口腔黏膜惡性腫瘤來自於原本即存在的可辨識但是仍不具侵犯性的病灶，然而口腔鱗狀上皮細胞癌(OSCC)是否來自於原先之病灶或是正常的口腔黏膜則尚未被確定。本研究中第壹單元之研究目的，在於評估南臺灣地區各種可能的口腔癌前期病灶，其惡性轉變為口腔癌與時間的關係。
惡性轉變時間定義為，初次組織病理診斷為口腔癌前期病變，至確定診斷為口腔癌的時間差距。自1991年至2001年，總共1458個診斷為口腔癌前期病灶之病患，其平均年齡為47.45±13.55歲。依據組織病理診斷將病患分類為以下六種：epithelial dysplasia with hyperkeratosis/epithelial hyperplasia (8.85%)，epithelial dysplasia with oral submucous fibrosis (2.54%)，oral submucous fibrosis (27.57%)， hyperkeratosis/epithelial hyperplasia (29.01%)，lichen planus (9.80%)與verrucous hyperplasia ( 22.22%)。
1458位病患其中有44位在這段期間內惡性轉變為口腔癌，其惡性轉變率為5.61%，平均惡性轉變時間為42.64±31.58月。其中166位epithelial dysplasia病患有8位；而423位hyperkeratosis/epithelial hyperplasia病患有15位分別轉變為口腔癌。其他癌前期病灶惡性轉變為口腔癌分別：402位oral submucous fibrosis中有8位；143位lichen planus中有3位；324位verrucous hyperplasia中有10位。
細胞自戕(apoptosis)，是安排細胞在既定的計畫中死亡，係由一系列抑制性與促進性因子所控制。其中有一群抗細胞自戕的蛋白質稱為抑制細胞自戕蛋白質家族。目前所知該家族共有8名成員，分別為cIAP1 (HIAP2, MIHB)，cIAP2 (HIAP1, MIHC)，XIAP (MIHA, hILP)，survivin，NAIP，LIVIN (ML-IAP, KIAP)，ILP2與BRUCE (apollon)。其中以survivin，XIAP，cIAP1，cIAP2 and NAIP最為普遍熟悉。本研究的第貳單元之研究目的在於探討以DMBA誘發倉鼠頰囊袋鱗狀上皮細胞癌化過程，與上述第壹單元中，44 (3.02%) 位患者口腔癌前期病灶，以及其惡性轉變為口腔癌病灶組織中，這五名IAP家族成員的表現以及IAP家族和p53之間的關聯，以及與epigenetic mechanism調控機轉是否有關。
本研究結果顯示survivin和cIAP2的蛋白質與mRNA並不表現在正常倉鼠頰黏膜與塗抹mineral oil的頰黏膜組織中，但是在塗抹DMBA3週，7週以及14週的頰黏膜組織則有表現。XIAP，cIAP2與NAIP的蛋白質與mRNA不只表現在塗抹DMBA3週，7週以及14週的頰黏膜組織中，同時也表現在正常倉鼠頰黏膜與塗抹mineral oil的頰黏膜組織中。p53的蛋白質與mRNA並不表現在正常倉鼠頰黏膜與塗抹mineral oil的頰黏膜組織中，但是在塗抹DMBA3週，7週以及14週的頰黏膜組織則有表現。44位口腔癌前期轉變為口腔癌的組織，其癌前期組織與口腔癌組織都同時有這五名IAP家族與p53蛋白質的表現。雖然還不清楚其中的交互作用為何，不過，這顯示IAP家族成員在動物口腔癌化過程中，與人類口腔癌化的表現有相關性。
另外，由甲基化實驗分析結果顯示這五名IAP家族成員的調控機制與epigenetic mechanism有關。
本研究建立南臺灣地區各種口腔癌前期病變惡性轉變為口腔癌與時間的關係，對於各種口腔癌前期病變長期而仔細的觀察追蹤是必須的。而對IAP家族在口腔癌化過程中表現的瞭解，將有助於日後對於口腔癌治療計畫與策略的擬定。

關鍵字

口腔癌前期病灶 ； 惡性轉變 ； 抑制細胞自戕家族 ； p53 ； 外基因

並列摘要

It is generally accepted that the development of cancer in the oral mucosa is preceded by an identifiable non-invasive precursor lesion. The aim of the present thesis in part I was to estimate the rate and the time to transformation in a group of patients from southern Taiwan with potentially malignant oral epithelial lesions.
The follow-up time is defined as the duration between the onset of the initial diagnosis and the occurrence of confirmed oral cancer. A total of 1458 patients with histological diagnoses of various premalignant oral lesions were followed up between 1991 and 2001. The average age at initial diagnosis was 47.45±13.55 years. The histological diagnoses were divided into six catergories: epithelial dysplasia with hyperkeratosis/epithelial hyperplasia (8.85%); epithelial dysplasia with oral submucous fibrosis (2.54%); oral submucous fibrosis (27.57%); hyperkeratosis/epithelial hyperplasia (29.01%); lichen planus (9.80%) and verrucous hyperplasia ( 22.22%).
Within the cohort of 1458 patients, 44 (3.02%) patients progressed to oral cancer in the same site as the initial lesions with an overall transformation rate of 5.61% and a mean follow-up time of 42.64±31.58 months. Eight of the 166 patients with dysplastic lesions and 15 of 423 patients with hyperkeratosis/epithelial hyperplasia progressed to malignancy. The other patients with malignant transformation originated from various pre-cancerous oral lesions and conditions (oral submucous fibrosis, 8 of 402; lichen planus, 3 of 143; verrucous hyperplasia, 10 of 324).
Apoptosis (programmed cell death) is regulated by a number of inhibitory or stimulatory factor. One such family of antiapoptotic proteins is the inhibitors of apoptosis proteins (IAPs). To date, eight members of the IAP family have been described: cIAP1 (HIAP2, MIHB), cIAP2 (HIAP1, MIHC), XIAP (MIHA, hILP), survivin, NAIP, LIVIN (ML-IAP, KIAP), ILP2, and BRUCE (apollon). The best characterized IAP members are survivin, XIAP, cIAP1, cIAP2 and NAIP. The objective of the present thesis in part II was to investigate the expression of the inhibitiors of apoptosis (IAP) family during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch squamous-cell carcinogenesis and in human oral pre-malignant and malignant epithelial lesions and its implication with p53 and epigenetics.
Survivin and cIAP2 ptoteins and mRNA were not detected in any untreated and mineral oil treated pouch-tissue, but they were detected in all specimens of 3-, 7- and 14 weeks DMBA treated pouch-tissue. XIAP, cIAP1 and NAIP were were detected in all specimens of untreated, mineral oil treated, 3-, 7- and 14 weeks DMBA treated pouch-tissue. p53 was not detected in any untreated and mineral oil treated pouch-tissue, but it was detected in all specimens of 3-, 7- and 14 weeks DMBA treated pouch-tissue. These five members of IAP family and p53 proteins were detected in all different human premalignant lesions and their malignant transformation cancerous lesions. The results of this study demonstrate the association between IAPs and p53 expression in this experimental model system for oral carcinogenesis and in human oral carcinogenesis, although their exact interactions remain to be clarified.
Based on the methylation assay of these five members of IAP family, it reveals these IAPs control by epigenetic mechanism.
In conclusion, the rate and the time to malignant transformation across a spectrum of potentially malignant oral epithelial lesions have been established in a Chinese population in Taiwan. This long-term study of 1458 pre-cancerous patients indicates that the management of oral premalignancy includes careful follow up. To understand the IAP family expression in oral carcinogenesis indicate that the potential of targeting strategies as novel therapeutic tools for oral squamous-cell carcinomas.

並列關鍵字

pre-malignant lesions malignant transformation ； inhibitors of apoptosis (IAP) family ； p53 ； epigenetics

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