The Research And Significance Of Genome Chromosomal Change And Protein Expression In Gastrointestinal Stromal Tumor

Objective: Gastrointestinal stromal tumors(GISTs) with uncertain malignant potential is one of the most common mesenchymal tumors of the gastrointestinal tract. Applying advanced molecular biological technique to search gene alteration and protein expression is important to our understanding on tumors. It is significant to reveal formation, development mechanism, direct treatment and predict prognosis. In this study, we apply the technique of comparative genomic hybridization to detect GISTs samples, and select worthy molecular biological parameters, such as p16,nm23 et al by immunohistochemistry which were filtered by CGH according to gene loss or gain and to provide significant evidence for diagnosis and therapy of genetics alteration and prognosis of GISTs.Subjects and methods: 25 cases of novel samples were collected from 2006-2007 and store in -80℃, after operation, all GISTs to confirm by histology and immunohistochemistry and then applying comparative genomic hybridization (CGH) technique to study tumor cytogenetic changes; according to gene loss or gain to select worthy molecular biological parameters (p16,PTEN,p53,Cmyc,MDM2,nm23,E2F1,Ki-67) to detect 62 GISTs of visit documents by immunohistochemistry in later years. Statistical analysis was performed using the SPSS 11.5 software.Results: 1. Death from tumor or the presence of liver and abdominal metastases was considered to represent evidence for progressive disease (PD). 2. We anslyzed 25 GISTs with CGH. Results show that each one has different degree of variances, included gains and losses of partial and whole chromosome. Each case has abnormal average region, losses are more than gains, equal to 3.12 and 2.2 per case respectively. Main regions are lost at chromosomes 14q(60%), 1p(40%), et al, and gains at 17q(40%), 5p(32%), et al.3.(1)In 62 cases of GISTs, p16 expression had significant difference in grade of GISTs(P<0.001). The PD in cases of cells expression was less than 50% with p16 immunostaining and higher than cases which cells of 50%-75% and more than 75% with p16 immunostaining(P<0.001).There was significant difference of PD in p16 expression(P<0.001).(2) The negative expression rate of PTEN protein was 19.4% in 62 cases GISTs, and negative expression cases increased along with the risk grading raised.The expression of PTEN protein was significantly related to risk grading of GISTs (P<0.05),but no difference with PD(P>0.05).(3)The positive expression of p53 protein was 26 cases among 62 GISTs, the higher tumor grading,the more positive cases, The expression of p53 protein was positive related to risk grading of the tumor (P<0.05). PD incidence rate in p53 (++) cases was higher than that in p53 (-) cases (P<0.05).(4)The positive expression rate of Cmyc protein was 80.6%, the higher malignant degree,the more positive cases of Cmyc,and The expression of Cmyc protein was related to risk grading of the tumor.Rate of PD was difference between in Cmyc(+++)cases and in Cmyc (+) and Cmyc (-) cases respectively (P<0.01).Rate of PD was difference between in Cmyc(++)cases and in Cmyc(+) and Cmyc (-)cases respectively (P<0.05).(5) Rate of MDM2 positive expression was 0.0%,0.0%,15.8%,61.1% in different grading. The expression rate in theⅣgrading was significantly higher than the others. The expression of MDM2 protein was related to the tumor malignant degree(P<0.05). PD incidence rate in MDM2 (++)cases was higher than that in MDM2(+)and (-) (P<0.05).(6)There was positive expression of different degree of nm23 protein among 62 GISTs, but the intensity was different. The expression intensity of low risk group was higher than that of high. The expression of nm23 protein was significantly related to risk grading of the tumor(P<0.01). PD incidence rate in nm23 cases was higher than that in other grade (P<0.01).(7)The positive expression rate of E2F1 protein was 71.0%, the expression of E2F1 was significantly related to risk grading of the tumor(P<0.05). There was difference in PD incidence rate between E2F1(+++)and other groups (P<0.01). PD incidence rate in E2F1 cases was differenc in others (P<0.01).(8)The Ki-67 labeling index inⅠ,Ⅱ,Ⅲ,Ⅳgrading GISTs was 0.0%,16.7%,36.8%,94.4% respectively.The positive cell populations of Ki-67 was significantly related to malignant degree(P<0.05).Conclusion: 1. There are unrandom DNA copy number gains and losses sites in chromosome, show these sites may include candidate oncogene and tumor suppressor gene. Losses of chromosomes arm 14q and 22q represent early changes related to the pathogenesis of GISTs. DNA losses of 1p might tend poor biologic behavior. Deletion of 9p and gains of 17q and 20q might represent a significant predictive marker in the malignant progression of GISTs. whether gains of 8q and9p were prognostic marker for GISTs were further confirmed .2. p16 protein expression and Ki-67 labeling index can be as valuable reference markers to judge malignant degree of GISTs. Cmyc, nm23 can be as prognostic marker too. E2F1 may be a prognostic factor, but to judge GISTs prognosis need to combine with another molecular biology marker. MDM2 was unsuitable as prognostic markers. Other studies are necessary to confirm whether PTEN and p53 are prognostic markers for GISTs.Research innovation: 1. In this study that covered two different fields which genetics alteration and prognosis factor of GISTs, refer to the whole genome chromosomal related gene alteration. 2. Based on specific gene alteration, with research status exterior and interior in GISTs to select directly molecular biological parameter and study relationship between protein expression and prognosis of GISTs and consummate prognostic evaluation criterion.