Expression Of EIF4E, VEGF And Their Correlation In Patients With Endometriosis

[Background]Endometriosis, named Ems, means the abnormal presence of endometrium out--side the uterine cavity. It is an ordinary and frequently-occurring gynecological disease affecting the health of women in reproductive age. The incidence is10%-15%,and the literature reported it was increasing year by year. Despite there were many hypotheses about the pathogenesis of endometriosis, it still remains controversial. The most widely accepted three hypotheses are the transplantation of exfoliated endometrium, lymph and vein spreading theory, coelomic epithelial metaplasia theory, but these three theories all exist some defects and cann’t totally explain the pathogenesis of endometriosis. Recently, with the development of molecular biology and immunology, the aetiology of endometriosis had made big progress at genetic susceptibility, immunological mechanism, angiogenesis, cells apoptosis and environmental factors etc. These mechanisms provided a new research field for the pathogenesis, development and therapeutic direction of endometriosis. Especially the angiogenesis has laid a solid theoretical foundation.The concept of angiogenesis was firstly used by Hertig in1935when he observed the formation of new blood vessels. But it was Folkman who made deep research into the angiogenesis. He proposed the idea of angiogenesis in1971, which means the growth and metastasis of tumor all depended on the formation of new blood vessels. Now this idea had been accepted widely. Angiogenesis played a key role in the growth, aggression and metastasis of tumor. The anti-angiogenesis therapy which was the research hotspot, also was proved effective in the comprehensive treatment of tumor. Endometriosis though is benign but had some characteristics that are similar to those of malignancies, such as the abilities to invade and metastasize. Such malignant biological behaviors depended on the angiogenesis of the ectopic endometrium. The famous expert of Department of gynaecology and obstetrics JH Lang academician indicated that ectopic endometrium must firstly break three line of defense, and then undergo attachment-aggression-angiogenesis to successfully plant on the surface of pelvic cavity.Angiogenesis is commonly regulated by the microenvironment, hormones, angiogenesis related factors, oncogenes and tumor suppressor genes. The balance of local angiogenesis factor and inhibiting factor determine whether the ectopic endometrium could plant, aggression and metastasis. There are thirty kinds of angiogenesis factors by cloning and characterizing. VEGF (vascular endothelial growth factor), which is a glucoprotein extracted and purified from bovine pituitary folliculo-stellate cell culture fluid by Ferrarra in1989, is considered the key angiogenic factor and to play a central role in both physiological and pathological angiogenesis. eIF4E (eukaryotic initiation factor4E), as a new tumor maker, is a central regulator in protein translation. Overexpression of eIF4E could selectively increase the levels of some tumor malignant gene production such as VEGF, cyclin D1etc. In conclusion, the overexpression of eIF4E(the key regulatou of protein translation) and VEGF(key factor of angiogenesis) may play an important role in the pathogenesis, development and metastasize of endometriosis.[Purpose]In our study, we aimed to investigate the expression of eIF4E and VEGF in the normal endometrium, eutopic and ectopic endometrium of endometriosis, as well their expression difference in different phase of menstrual cycle and different r-AFS phase. We also studied the correlation between the expression of eIF4E, VEGF so as to explore the pathogenesis of endometriosis and to provide a new path for the diagnose and therapies of endometriosis.[Materials and methods]1. Clinical materialsEctopic endometrium and eutopic endometrium were collected from30patients who underwent the surgical laparoscopy for endometriosis at Nanfang Hospital of Southern Medical University from September2010to May2011. Of the30patients whose average age was31.2±7.8years (range20-46years), and18of them were in the proliferative phase and12patients were in the secretory phase. According to the Revised American Fertility Society Classification of endometriosis (R-AFS) in1985, we found that there were11patients in phase Ⅰ-Ⅱ,13patients in phase III and6in phase IV.Endometrial tissues were as controls from20patients undergoing the laparoscopic hysterectomy for uterine myoma and laparoscopic examination surgery for sterility.2. Experimental methodsThe pathological change and menstrual cycle phase of all the specimen were observed through HE staining. The expressions of eIF4E and VEGF proteins were detected by immunohistochemical method of SP.3. Evaluation of resultsThe positive expression was the occurrence of brown substance in cytoplasm of the glandular epithelium. The expression intensity was estimated with mean optical density (MOD) by image pro-plus6.0semi-quantitative analysis. MOD is equal to the integerated optical density/scanning area and the expression level was stronger with a higher MOD.4. Statistical analysisAll data were analyzed using SPSS13.0software. All different expression levels of eIF4E and VEGF in endometriosis were determined by the ANOVA analysis or the nonparametric test, and the correlation between the two proteins were confirmed by the Pearson test. P<0.05was considered statistically significant. [Result]1. The expression of eIF4E protein in three gourps1.1Location of eIF4E:eIF4E mainly expressed in the cytoplasm, which was detected diffusely in glandular epithelial cells and slightly in stromal cells of ectopic endometrial tissues. The eutopic endometrium and normal endometrium had weak positive expression in the glandular epithelial cells and had no expression in the stromal cells.1.2Difference of expression:The MOD of eIF4E in ectopic endometrium、eutopic endometrium and normal endometrium were0.222±0.039、0.154±0.015and0.109±0.018, respectively. The expression intensity showed such sequence as follows: ectopic endometrium> eutopic endometrium> normal endometrium (χ2=62.91, P=0.000).2. The expression of VEGF protein in three gourps2.1Location of VEGF:VEGF was detected diffusely in the cytoplasm which was detected diffusely in glandular epithelial cells and slightly in stromal cells of ectopic endometrial tissues. The eutopic endometrium and normal endometrium had weak positive expression in the glandular epithelial cells and had no expression in the stromal cells.2.2Difference of expression:The MOD of VEGF in ectopic endometrium、eutopic endometrium and normal endometrium were0.195±0.050、0.131±0.021and0.084±0.019, respectively. The expression intensity of VEGF in three groups showed the same sequence as eIF4E protein (χ2=53.33, P=0.000).3. The expression differences in different menstrual cycle:In the eutopic endome--trium and normal endometrium, the expressions of eIF4E, VEGF in proliferative phase were higher than that in secretory phase (F=10.59, P=0.004; F=6.967, P=0.013).4. The expression differences in different r-AFS stage:There were no differences between the eIF4E and the r-AFS stages of endometriosis. But there were significant higher expressions of VEGF in Ⅰ to Ⅱ stage than in Ⅲ to Ⅳ stage (P=0.02). 5. The correlation of eIF4E and VEGF:The eIF4E and VEGF expression had obvious positive correlation in ectopic and eutopic endometrium (r=0.871, P<0.01; r=0.798, P<0.01), but there was no correlation in the normal endometrium(r=0.296, P=0.205).[Conclusion]1. Expression of eIF4E and VEGF in eutopic endometrium had changed a lot as compared with normal endometrium. This indicated that the eutopic endometrium of Ems had different biological characteristics, which would be an important reason for the occurrence of endometriosis and also supports the hypothesis of "eutopic endometrium determinism" to some extent.2. Expression of eIF4E and VEGF in ectopic endometrium was significant higher than that in the eutopic and normal endometrium, which suggests that eIF4E and VEGF may play an important role in the etiopathogenesis of endometriosis.3. eIF4E expression was positively correlated to VEGF expression in ovarian endometriosis, suggesting eIF4E may have an angiogenic effect through VEGF.4. Expression of eIF4E, VEGF in eutopic and normal endometrium in proliferative phase were higher than that in secretory phase, suggesting secretory endometrium had higher biological behavior and stronger angiogenesis, so as to implant in the pelvic easier.5. Expression of VEGF in ectopic endometrium in I to II stage was higher than that in III to IV stage, but the eIF4E expression in ectopic endometrium showed no differences in different clinical stages. This suggests that eIF4E may relate the occurrence of endometriosis, and VEGF could induce the angiogenesis of ectopic endometrium and promote the development of endometriosis.