| Summary: | 碩士 === 國防醫學院 === 牙醫科學研究所 === 93 === Most of oral cancers are initially asymptomatic lesion and are not diagnosed or treated until they reach an advanced stage. Early detection of cancer is the most effective way to reduce the harm from the disease. If we could find out some biomakers for prognostic improvement and serve it as an intervention for public health, the cancer can be early detected and early treated and eventually be prevented.
The first part of this study is to validate the finding of previous DNA microarray study conducted by Dr. Kuo Chin-shan that cell oxidative damage process may contribute the major mechanism for oral carcinogenesis. He found that hOGG1, a base excision repair enzyme for DNA lesion, gene was highly expressed in cancer cells in comparison with that of normal cells. Because the DNA microarray study was focused on RNA level, we than investigate the expression of hOGG1 in the protein level to find if it could be used as the biomarker candidate for detecting oral mucosal diseases related to betel-nut chewing.
The noninvasive sampling method was used by saliva collection followed by certification to obtain the oral exofoliated cells. Three groups including normal control, persons with betel-nut chewing habit, and patients with oral cancer were designed to investigate the protein expression of hOGG1 using Western blot analysis. The results showed no significant difference among groups, indicating that hOGG1 is not a suitable biomarker for detecting oral cavity disorder.
Because of the finding hOGG1and the fact that RNA expression level is not correlated with the level of proteins expression, we then further search the biomarker in oral cavity by using proteomics approach. The saliva samples from each group were collected and separated by two-dimensional gel electrophrosis. Isolated spots revealing differences figure between groups were selected for further identification, using the MALDI-TOF mass spectrometry and LC/MS/MS. The results showed that Annexin-1 was overexpressed in the betel nut chewing group and PLUNC protein and Cytokeratin1 were overexpressed in the cancer group. The results found in this study: Annexin-1 and PLUNC proteins are related to inflammation and stimulation from environment and changes of cytokeratin expression have been reported in oral mucosal disease including carcinomas, suggesting that they are the good targets for biomarker validation.
Taken together, we have setup the well-developed protocols for oral exfoliated cell collection applied for proteomic study. More potential biomarkers may be identified by using this high throughput method.
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