The Expressions And Correlations Of RAR-β Receptor And Galectin-3 In Human Middle Ear Cholesteatoma

The middle ear cholesteatoma is a common disease of Otolarynology andcharacterized by hyperproliferative keratinated squamous epithelium in the middleear cavity. The study also indicated although cholesteatoma take on malignantsymptom similar to carcinoma in clinic, it belonged to benign tumor.Cholesteatoma epithelium cells are not only hyperprolifetative but alsooverapoptosis. But The mechanism of middle ear clesteatoma is not clear yet. Inmolecular biology, the domestic and international researchers have worked hard tostudy the mechanism of cholesteatoma recently. Embryonic tissues and cells areregulated by a number of factors during development and diferentiation,amongthem, retinoic acid plays important roles. The mechanism of retinoic acid inducingcell diferentiation is emphasized in recent decades. Investigations havedemonstrated that the efect of retinoic acid on cells is mediated through twoclasses of nuclear receptors, the retinoic acid receptors(RARs) and the retinoid Xreceptors (RXRs). In order to explore the cell differentiation in the middlecholesteatoma, we explore the expression of RAR-β receptor. The main functionof Galectin-3 in the cell surface is related to tumor cell adhesion among the samekind cells, Galectin-3 is a protein composed of two distinct structural motifs, anamino-terminal half containing Gly-X-Y tandem repeats characteristic ofcollagens and a carboxyl-terminal half containing the carbohydrate-binding site. Itis an important intracellular and extracellular structure that is presumed to interactwith extracellular matrix proteins and cell surface glycoproteins in normal andpathophysiological conditions. We observe the expressions and correlations ofRAR-β receptor and Galectin-3 in human middle ear cholesteatoma.Objective: to explore the expression and correlation of RAR-β receptor andGalectin-3 in acquired middle cholesteatoma, and to evaluate their roles in theformation of the middle ear cholesteatoma.Method: 30 samples of middle ear cholesteatoma we studied came form thepatients who were operated in our hospital during Mach. 2005 to Jun.2006, and allof them had been verified to be cholesteatoma by pathology. 12 samples werenormal skin of the external ear canal acquired from tympanoplasty at the sametime. The wax specimens were sliced into 4μm sections continuously. We used theimmumohistochemical technology with streptavidin-peroxidase TM. The primaryantibodies were rabbit anti-human RAR-β polyclonal antibody and rabbitanti-human Galectin-3 polyclonal antibody separately, and they were both instantantibodies. PBS was used for negative control instead of the primary antibody.The main steps of operation: After deparaffinization and washing, we used salinesodium citrate solution for antigen reparetion. Edogenous peroxidase of thesections were inhibited with a methanolic solution and then blocked with normalbarbary serum to reduce background. Hence we fixed primary antibody (4℃,vernight), postfixed IgG labeled by biotin, and color development was performedwith DAB, The sections afterstained and occluded by neutral balsam. Undermicroscopic observation at magnification×400, we selected five random visualfields and calculated the positive cells, then with the formula LI=∑n/∑N×100%we get labeling index (LI). We dealed with the data with SPSS system software,used x2 test and the paired samples Spearman-test to compare the means of pairedvariables with a level of significance of p<0.05.Results: 24 samples ofcholesteatoma showed a stronger expression of RAR-β receptor than the externalear skin, positive rate was 80%. RAR-β receptor expressed in the cytoplasm andmembrane of the full epithelial tissue, and its LI was 74.2%±5.7%. Comparedwith normal ear canal skin, the expression of RAR-β increased in middle earcholesteatoma epithelium(P<0.05). 26 samples of cholesteatoma were found tocontain Galectin-3 expression. Galectin-3 expressed in the cytoplasm andmembrane of the cell. Furthmore, and its LI was79.2%±6.5%. Compared withnormal ear canal skin, they had obvious difference(P<0.05);The level of RAR-βexpression correlated highly with the level of Galectin-3 expression. Incholesteatoma epithelium samples, RAR-β was 74.2%±5.7%, and Galectin-3 was79.2%±6.5%. They didn't have significant difference by statistics. But incholesteatomatous tissues they were correlated closely by Spermen test.Conclusion: an undiferentiated population of keratinocytes may lead to theformation of cholesteatoma, and a relation may exist between retinoid activity andGalectins.