The Effect Of Epithelial Growth Factor On The Migration And Adhesion Of Human Lens Epithelial Cells In Vitro

IntroductionPosterior capsule opacification (PCO) is the mainly reason induced to low vision after extracapsular cataract extraction. Even though tremendous advances have been made especially during the last 10-15 years in terms of surgical techniques and improvement of implant technology, posterior capsule opacification (PCO) still remains a serious long - term complication, which is now the commonest complication of cataract surgery occurring in up to 50% of patients by 2 to 3 years after the operation. PCO is caused by lens epithelial cells retained in the capsular bag following surgery which then proliferate, migrate and transform to myofibroblasts. PCO results from the growth and transdifferentiation of lens epithelial cells left on the anterior capsule at the time of cataract surgery. These cells proliferate to form monolayers on the capsular surfaces, and such monolayers continue to line the anterior capsule leaflet many years after surgery. Some cells, however, differentiate or undergo a transition to another cell type, and these processes greatly contribute to PCO.The operation of ECCE induces the release of many kinds of cytokine. The cytokine connect with their receptors and take some role alone or co - effect with others, which contribute to the formation of PCO. At the same time, ECM releases to the humor from the injured blood - humor barrier and deposits on the surface of posterior membrane of capsule;which supplies a good condition for the lens epithelial cells adhesion. Alive cells have the characters of transferring and adhesion. According to the stimulation of chemotactic factors, cells make migration and adhesion to the substance (such as ECM). After ECCE, formation of PCO is induced by the left lens epithelial cells migration to the lens posteriorcapsule, the adhesion to ECM there and growth. The proliferation of these LEC, regeneration of lens fiber and formation of collagen result in PCO.Although there was no EGF found in the humor in congenital and senile cataracts , some researchers have found EGF in the humor of PCO, ECCE with or without IOL patients. Majima at al. found that EGF can promote the growth of lens epithelial cells and also fibrosis of anterior lens capsule. EGF acts as a stimulation factor to not only endothelial cells growing, but also to the migration and proliferation of endothelial cells and epithelial cells. So it can be said that EGF is an important factor to lens epithelial cells proliferation and contribute to the formation of PCO.The adhesion of cells to their neighbors determines cellular and tissue morphogenesis and regulates major cellular processes including motility, growth, differentiation, and survival. Cell - cell adherens junctions (AJs ) , the most common (indeed, essentially ubiquitous) type of intercellular adhesions, are important for maintaining tissue architecture and cell polarity and can limit cell movement and proliferation. Growth factors such as EGF, HGF/scatter factor (SF) , and FGF can induce the dismantling of AJs and can cause a dramatic change in cell morphology and gene expression in which cells shift from an epithelial to a fibroblastic phenotype. Whereas tyrosine kinase receptor signaling regulates cell adhesion, it is also possible that AJs, in turn, influence tyrosine kinase signaling. The reduction in cell proliferation characteristic of dense cell cultures is mediated, in part, by cadherin -containingAJs that render the cells insensitive to growth factor stimulation. The loss of AJs in cooperation with deregulation of other pathways leads to enhanced cell proliferation, motility, and, eventually, metastasis.PurposeTo study the effect of EGF on migration and adhesion of human lens epithelial cells.MethodsHuman lens epithelial cells were cultured in DMEM + 20% FBS medium. The scratch assay was used for examining the effect of EGF on human lens epithelial cells in their migration. Western blot method was performed to determine the expression of (3 - catenin protein and other proteins.ResultsAt the concentration of 20ng/ml EGF treatment, the migration distance of human lens epithelial cells increased with the treatment time lasting, with the peak after the 48 - hour treatment. And after the 48 - hour EGF treatment, the migration distance of human lens epithelial cells increased with treatment concentration increasing, with the peak at the concentration of 20ng/ml. Further more, at the concentration of lOng/ml EGF treatment, the expression of (3 -catenin protein of human lens epithelial cells increased with the treatment time lasting, with the peak after 2 - hour treatment. After the 2 - hour EGF treatment, the expression of p - catenin protein of human lens epithelial cells increased with the treatment concentration increasing, with the peak at the concentration of lOng/ml. After EGF treatment with the concentration of 20ng/ml, the expression of E - cadherin and vinculin of human lens epithelial cells increased with the treatment time lasting. These effects were partly reduced after wortmannin adding.Conclusions1. EGF promoted the migration of human lens epithelial cells.2. EGF promoted the adhesion of human lens epithelial cells. And it could increase the expressions of |3 - catenin ^E - cadherin and vinculin protein.3. These promotion effects seemed through PI3K/AKT signal pathway. And from the results of wortmannin adding, we may say that the inhibitor of PI3Kcould inhibit the promotion of EGF to cells migration and adhesion partly.