Comparative Studies On Screening Serum Biomarkers Of Colorectal Cancer With AU And NP20 Chips And Set Up The Model Of Combined Diagnosis

Colorectal cancer （CRC）, the third most frequent cancer in the whole world, including colon cancer and rectal cancel, is often diagnosed at an intermediate or late stage with poor prognosis. Hence, there is a great need for new biomarkers for early detection of CRC. There are some current biomarkers such as CEA which is the only clinical skill to inspect expression products of colorectal cancer. The CEA, however, still has some problems. On the one hand, a great quantity of serum needed will lead to expensive testing price; On the other hand, it exists in the problem of poor sensitivity and specificity.Recently, proteomics has been rapidly developed and been applied to tumor research. It gives us the possibility to discover novel biomarkers for cancer diagnosis and the researchers want to make a breakthrough in the area of oncotherapy by the method.In this research, we conducted the technique and the theory of molecular epidemiology and performed a case-control study researching on serum proteomics studies of colorectal cancer in Chinese population for the first time by magnetic beads associated with surface enhanced laser desorption/ionization time-of-flight mass spectrometry（SELDI-TOF-MS） respectively with the two chips（gold chip and normal phase 20 chip）. These researches included the screening of novel serum protein biomarkers of colorectal cancer, the discovery of different expression protein of different clinical stage of colorectal carcinoma etc. The initial study, which looked for the difference between expression protein of colon cancer and rectal cancer, was also provided. At last, the model of combined diagnosis was established by decision tree model analysis. Furthermore, our study also compared the experimental results of the two chips, and associated with the result of experimental analysis of magnetic beads in order to set up an optimized experimental technique route.The results show that it is a distinguished difference existed in case and control. From the experimental results between NP20 and AU chips, we found two protein peaks---M13732₄ and M13912₃ which could better discriminate the two groups. The position of the two peaks is near, it is supposed that the two peaks may be two similar chemical compositions, and they could be the novel biomarkers. The differences of early-stage and late-stage colorectal cancer are also distinguished. However, the differences of the colon cancer and rectal cancer aren’t obvious. Besides, the combined model improves the rate of accuracy of prediction, optimizing the experimental results. The results also show that the method of magnetic beads associated SELDI protein chip has many advantages of cheap, speedy, easy handle etc. Hence, it is worthwhile to optimize the technique route.To sum up, these optimized experimental conditions established could be a reference for the future studies. The combined diagnosis model and the possible new biomarkers can also provide a theoretical basis if they are applied to clinical examination in the future.