| Summary: | 碩士 === 臺北醫學大學 === 醫學檢驗暨生物技術學系所 === 102 === According to the report of World Health Organization in 2012, colorectal cancer is the third prevalent cancer and gastric cancer is the sixth prevalent cancer. Carcinoembryonic antigen (CEA) is the most use of tumor markers of colorectal cancer. The major biomarkers of gastric cancer are CEA、CA 19-9 and CA 72-4. However, the specificity and sensitivity of those markers are not good . Until now, some researches have explored the protein level of Alpha-1- antichymotrypsin (ACT) in the plasma of gastric and colorectal cancer, but few researches show the post-translational modification (PTM) of ACT in both cancers. In this study, we use proteomic approaches such as western blot, immunoprecipitation, and nano- LC/MS/MS to analyze the plasma samples from normal and cancer groups. Then we identify PTMs between those samples in order to find out the useful PTM sites of ACT to be a diagnostic tool. As our results, there was no significance of protein level between the early stage of gastric cancer group and normal group. However, there
was significance of that in the early stage of colorectal cancer group. The PTM data showed that there were three PTMs in gastric cancer, including Trimethylation (Asp-194), n-Octanoate (Thr-269) and Palmitoylation (Lys-177). There were three PTMs in colorectal cancer, including Hydroxylation (Asn-323), Methylation-2 (Glu-334) and 4-Hydroxy-2-nonenal (Arg-298). There was significance of those PTMs expression between the cancer group and normal group. In conclusion, those PTMs will be good biomarkers for gastric cancer and colorectal cancer by using tandem mass to identify
and quantify them.
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