The Relationship Of Osteopontin And The Calcification In Craniopharyngioma

Craniopharyngioma is a histologically benign, extra-axial, slow-growing tumorthat predominately involves the sella and suprasellar space, which is close to thepituitary gland. Craniopharyngioma represents approximately 4.7%～6.5% ofintracranial tumors and 10% of pediatric brain tumors. In pediatric patients,craniopharyngiomas represent the most common intracranial tumor of nonglial originand account for approximately 50% of all sellar and prechiasmatic tumors.Craniopharyngiomas are dysontogenic tumors with benign histology and malignantbehavior, as they have a tendency to affect the surroundings important structuregreatly and recur after a neurosurgery.Gross total surgical removal is the treatment of choice; however, it can beassociated with morbidity and mortality rates as high as 20% (excludingendocrinopathies) and 12%, respectively. Recurrence rates can be as high as31%-81%; and a serious potential for psychosocial deficits exists in patients withhypothalamic injury. The classic and most common appearance of the tumor is that ofa cystic tumor, usually with a solid component. A wide variation in size is observed(which is considerably more severe with recurrent tumors than with others) are alsoobserved. These findings may result in calcification is a very important factor, whichaccounts for the difficulty in resecting craniopharyngiomas. It also explains why, recurrence frequently and complications seriously in these tumors following a radioresection, that are histologically benign.So far, there hasn't been any main hypotheses explain the calcification ofcraniopharyngioma. The purpose of the study is to undertake molecular pathologicaland molecular biological studies on the dose-dependent effect of Osteopontin (OPN)on the calcification of craniopharyngioma as well as its relevant mechanisms.OPN is a 44-kDa, negatively charged, acidic protein that is almost alwayssialated and/or phosphorylated and that is found in large amounts in a variety oftissues and secreted into body fluids, including the stroma. The protein containsseveral conserved motifs, including the integrin binding sequence GRGDS. OPN caninteract with a number of receptors, including RGD-mediated interactions with theintegrinsαvβ3,αvβ5,α9β1 andα4β1. Also reported are non-RGD-mediatedinteractions of OPN with CD44, a family of surface receptors which regulatecelladhesion, movement, and activation. Other non-RGD cell binding interactions thatare dependent only on the beta subunit or sialic acid moieties have also beendemonstrated. Macrophages, T lymphocytes, NK cells, endothelial cells, smoothmuscle cells, fibroblasts, epithelial cells, and osteoclasts all express OPN in responseto activation by various cytokines or inflammatory mediators. OPN has many diverseand incompletely understood functions, including the regulation of cell migration andproliferation, tissue repair and angiogenesis, and cellular chemotaxis and activation ininflammatory conditions.Materials and methods1, Subject: Patients with craniopharyngioma aged 3～67, male (n=31) andfemale (n=23), were studied from June 2004 to March in 2006. Cases acceptancestandard:①Patients with craniopharyngioma who accepted neurosurgery in the period of study;②The craniopharyngioma were confirm by thepostsurgery-pathology..2, Trial management: The study was consisting by two parts, a. To study thedose-dependent effect of OPN on the calcification of craniopharyngioma byimmunohistochemistry and Western Blot; b. To study the bionomics of thecraniopharyngioma with light microscope, electron microscope, and immuno-electronmicroscope.3, The tumor samples harvested from surgical removal were cut into smallpieces of lmm3 with a sharp double knife in time, and the small pieces were put intothe fixation fluid with 0.25％glutaraldehyde for pre-fixation, followed by immersingand embedding them into epoxide-based resin Epon812 for preparation of humansuper-thin sections in 500A, which were then stained with uranyl acetate and citricacid for observation of the tumor ultra structures under an H7500 transmissionelectron microscope. On the other hand, the small pieces were put into fixation fluidcontaining 4％paraformaldehyde and 0.25％glutaraldehyde for 1 hour fixation at thetemperature of 37℃, and then stored in 2.3mol/L sucrose fluid at the temperature of4℃for at least 2 hours for serial sections of 50～70 nm thick with an LeicaUCcryo-ultramicrotome (-90b～110b). Immuno-electron microscopy was then performedfor 10nm colloidal gold particle labelled Osteopontin and the distribution ofOsteopontin in the tumor tissue was observed under a transmission electronmicroscope. Ten arbitrary distribution areas were shot under the electron microscopeof 40000×to calculate the mean of colloidal gold particles.4, Statistics treatment: All data were analyzed by SPSS 10.ResultsSamples were from the 54 patients whose craniopharyngiomas had been surgically removed in our hospital from May 2004 to March 2006, followed bypostoperative pathological diagnosis to find 41 cases of adamantinomatouscraniopharyngiomas and 13 cases of papillary craniopharyngiomas. The 54 patients(31 male and 23 female) in the ages from 3 to 66 years were analyzed. The averageage was 26.5 years.OPN expressed obviously in the admantinomatous craniopharyngioma cell, butabsent or little expressed in the papillary types (Mann-Whitney U test, Z=4.813, P＜0.001). OPN stain grade was significantly in the admantinomatouscraniopharyngioma and related to the grade of calcification, the more calcificationapparent the OPN stain was (Spearman correlation, r_s=0.725, P＜0.001). OPN wasaggregated in the epidermis like cell in the admantinomatous type.CD44V6 stain grade was significantly in the admantinomatouscraniopharyngioma and related to the grade of calcification, the more calcificationapparent the CD44V6 stain was (Spearman correlation, r_s=0.743, P＜0.001).OPN Immuno-electron microscopy show the gold markers in thecraniopharyngioma cell of the ameloblast type be located on the endoplasmicreticulum that the swollen oncocyte afterbirth strach, from endoplasmic reticulumcreation behind secrete the outside of the afterbirth; But didn't see the gold markers inthe craniopharyngioma cell of the squamous type.ConlusionsThe expression degree of the craniopharyngioma OPN of different andpathologic type is different. The craniopharyngioma cell has cytology basal of secretethe OPN; the expression degree of OPN amount and craniopharyngioma calcificationexists just to of Dose-response relation, namely along with the OPN express quantityof increment, the calcification degree of the craniopharyngioma aggravate. OPN may play an important role in the calcification of craniopharyngioma.