Research Of Diagnosis For Early Esophageal Carcinoma By Surface Enhanced Laser Desorption/Ionization-Time Of Flight-Mass Spectrometry

ObjectiveThe esophageal carcinoma is one of the most common malignant tumors in our country. The average age of patients is over 40. It is one of the main malignant tumors in digestive system in our country, and has high mortality. The effect of esophageal carcinoma's therapy is not optimistic now. The 5-year survival rate after operation is lower than 30%. However, the earlier period esophageal carcinoma will almost be cured completely. The 5-year survival rate is no less than 90%. So, early diagnosis to esophageal carcinoma is most important to improve patients' prognosis. Nevertheless, present diagnostic techniques are not competent enough for this job. The early symptoms such as light catch, tightly closed after breast bone are not typical. Net-balloon examination is a valid method for mass screening in high-morbidity area. But many patients feel painful and are hard to accept it. There are other techniques such as endoscope, barium swallow, radio isotope, CT, MRI, PET, EUS and tumor marker. They all have their shortcomings and not satisfactory on the whole. The diagnosis of esophageal carcinoma is not difficult to make to the patients who have typical clinical symptoms. However, these patients are often in the medium-advanced stage at that time and the prognosis is not satisfactory. Therefore, to find a highly sensitive and specific diagnostic method for early esophageal carcinoma have always been the focal points of scientific research and clinical practice. The development of proteomics opened a new window for tumor research. Tumor cell will certainly produce proteome which is different to health adults when it grows. If this proteome is found and analyzed correctly, a new method for carcinoma diagnosis will come into being. Surface enhanced laser desorption/ionization- time of flight- mass spectrometry (SELDI-TOF-MS), which emerged in the beginning of 1990, is a new kind of proteomic technology. The proteinchip has been exploited based on this technique, and the chip can bind all kinds of proteins in the sample. When the chip is bombarded by laser in the mass spectrometer, all the binded proteins will be stimulated and gasified into ions. Because ions have variant mass charge ratio(M/Z), they have variant time of flight. So the reception equipment can distinguish variant proteins by their mass charge ratio. It allows for protein profiling from a variety of complex biological materials such as serum, urine and cell lysates with limited sample preparation. This technology, combined with bioinformatics, has been successfully used to analyze the complex serum proteins to explore the cancer-specific 'fingerprints' or 'patterns'. In our present study, we used IMAC (Immobilized Metal Affinity Capture) chips of Ciphergen Corporation to detect and analyze proteomes in serum of patients of early esophageal carcinomas and health adults, expecting to set up a classification tree mode which can discriminate the early esophageal carcinomas correctly.MethodsProteomic spectra of 51 serum samples from early esophageal carcinoma and 56 from health adults were generated by IMAC-Cu proteinchip array and SELDI-TOF-MS. The discriminatory profiling was analyzed by Biomarker Wizard software and Biomarker Pattern software. The classification tree mode was set up by cross-verification. And the results were verified in double-blind by a group of 43 early esophageal carcinomas, 56 health adults, 22 esophagopolypus, 23 pre-cancer diseases and 54 advanced-stage esophageal carcinomas.Results25 distinct proteins which were detected between the two teams were all low-expressed in early esophageal carcinomas. Five proteins (M/Z 4616.05, M/Z 6336.80, M/Z 7769.85, M/Z 6113.94, M/Z 15121.1) were choosed to set up a classification tree mode which can discriminate the two teams correctly. The correct ratio was 98.04% and the specificity was 100%. The mode was double-blind verificated by a group of 43 early esophageal carcinomas, 22 esophagopolypus, 23 pre-cancer diseases, 54 advanced-stage esophageal carcinomas and 56 health adults. In double-blind verification the sensitivity and specificity to early esophageal carcinomas were 83.72% and 96.04% respectively. The specificity to esophagopolypus, pre-cancer diseases, advanced-stage esophageal carcinomas, health adults were 86.36%, 95.65%, 88.89% and 100% respectively.Conclusions25 distinct proteins which were detected between the two teams were all low-expressed in early esophageal carcinomas. Perhaps they were inhibited in the development of carcinoma.Via comparative proteomics research in the serum of early esophageal carcinomas and health adults by SELDI-TOF-MS, early esophageal carcinomas can be quickly and accurately diagnosed with high sensitivity and specificity. The novel technology makes it possible for early diagnosis of esophageal carcinomas.