The Expression And Significance Of MCM2,Ki67 And PCNA In Esophageal Intraepithelial Neoplasia And Esophageal Carcinoma

Background and objectiveAt present, we always use proliferating cell nuclear antigen (PCNA) and Ki67 as proliferation markers, PCNA is a protein with molecular weight of 36KD, as a auxiliary protein of polymerase 5, it is essential in the process of DNA replication, in the whole cell cycle, the expression of PCNA localize in nucleuso But there are studies report PCNA not only related to DNA replication, but also refer to reparation of DNA. So there are PCNA expression in the cell experience the DNA reparation, this interfere the accuratissime for it as a proliferation maker. Ki67 antigen is a nonhiston enucleo- protein which exists in proliferation cells, it is composed with two peptide chain, its expression changes as the cell cycle. There is no expression in GO phase, and emerged in metaphase of cell division of G1, gradually increase in s phase and G2 phase, and achieve the peak in M1 phase, after M phase, it is degradated or lost the antigenic determinant. Many study confirmed that Ki67 was not the indispensable maker for cell proliferation, there is not the expression of Ki67 in the early phase of G1. its expression is affected by the external factors such as cell nutrition.MCM proteins are essential replication initiation factors that ensure the accurate replication of DNA in the cell cycle. Through accurate binding to chromatin during G1 phase and detaching from chromatin during S phase, MCM proteins restrict DNA synthesis to only once per cell cycle. Only licensed origins containing MCM protein scan initiate a pair of replication forks, and once initiation occurs at an origin, the bound MCM proteins are displaced so that the origin cannot fire again. MCM proteins may also function as the helicase that unwinds DNA ahead of each replication fork. Evidence from different organisms and cells indicates that both permanently arrested cells and those in GO phase have lost expression of MCM proteins and are functionally unlicensed. The replication initiation function of MCM proteins in cell cycle implies that they may be valuable markers for proliferation and prognosis in human cancers.The purpose of this study to detect the difference of the expression between nomal esophagus and every pathological changes of esophagus epithelium and between every differentiated-grade esophagus carcinoma, and compare the labelling index of MCM2 with traditional cell proliferation makers such as Ki67 and PCNA. And also compare the sensitivity and specificity to the dysplasia epithelium, to explore the significance of MCM proteins as a proliferation maker in judgement of malignant degree in esophagus carcinoma and early diagnosis of esophagus epithelium precancerous changeMaterials and MethodsSample sources:1.Samples of operation on esophagus: choose from cancer hospital in Linzhou city Henan province between September to November in 2005. all are confirmed as esophagus squamous cell carcinoma. Including 12 well-differentiated esophagus squamous cell carcinoma, 14 moderately-differentiated esophagus squamous cell carcinoma and 17 poorly-differentiated esophagus squamous cell carcinoma. Taking of samples from the tumor and the both cutting edges. The total tissues included 15 hyperplasia, 15 dysplasia, 10 carcinoma in situ.2.15 samples from autopsies affirmed with no disease of esophagus as control.3. Endoscopic biopsy samples from census group: the samples come from high-risk group from cancer hospital in Linzhou city Henan province, as a total of biopsy samples as 171, including 54 normal esophagus epithelium, 48 hyperplasia, 69 dysphasia. 69 dysphasia4. exfoliative cytology samples: 10 exfoliative cytology samples on the surgically resected specimens of esophageal squamous cell carcinoma from the department of pathology of Shantou university medical college in 2006.11, made the cell paraffin blockMethod:The immunohistochemistry(IHC), Envision two-step method was used for stain PCNA,Ki67and MCM2 Result:1. In different differentiated-grade esophagus squamous cell carcinoma, the LI of MCM2 got bigger with the grade descented, there was significant difference. (P＜0.05) ,the LI of Ki67 had the same trend, but there was not significant difference(P＞0.05). the LI of PCNA had significant difference between moderately-differentiated and poorly-differentiated esophagus squamous cell carcinoma (P＜0.05) . but had no between well-differentiated and moderately-differentiated esophagus squamous cell carcinoma (P＞0. 05).2. The esophagus epithelium from normal to hyperplasia to dysplasia to carcinoma in situ, the LI of Ki67,MCM2 and PCNA got bigger, and there were significant difference .in CIS and dysplasia, the LI of MCM2 was bigger than Ki67 and PCNA ,and expression layer was higher.3. In 171 endoscopic biopsy samples from census group, epidemiology diagnostic test evaluation for Ki67,MCM2 and PCNA displayed that the index of MCM2 in esophagus precancerous change (dysplasia) were: sensitivity is 91.3 %, specificity is 61.8%, accuracy is 73.7%, positive predictive value is 61.8%, negative predictive value is 91.3%, each was much higher than Ki67 and PCNA.4. In 10 exfoliative cytology samples on tumors and paracancerous, the average number of positive cells of MCM2 is more than PCNA and Ki67Conclusion1. The expression of MCM2 was related to differentiate grade, from well-differentiated to moderately-differentiated to poorly-differentiated esophagus squamous cell carcinoma, the LI of MCM2 was more and more bigger, the LI of MCM2 is a significant index for malignant level in esophagus carcinoma. And it is more reliable than Ki67 and PCNA.2. In cancerization of esophagus epithelium, from normal to hyperplasia to dysplasia to carcinoma in situ, the LI of MCM2 increased gradually ,in dysplasia and carcinoma in situ, the LI and expression layer of MCM2 is higher than PCNA and Ki67.and in normal and hyperplasia, the LI of PCNA is slightly higher than MCM2 and Ki673. for the diagnosis of dysplasia, the sensitivity, specificity, accuracy, positive predictive value, negative predictive value is higher than PCNA and Ki67.4.10 exfoliative cytology samples on tumors and paracancerous, the average number of positive cells of MCM2 is more than PCNA and Ki67.