CD44v6 Expression In Osteosarcoma,Giant Cell Tumor Of Bone And Osteochondroma

IntroductionThere are many mechanism involved in the growth and metastasis of neoplasm. Generally speaking, the cell - cell and cell - matrix interaction which transferred by cell surface adhesion molecules is the biological basis. As the research of molecular biology and tumor genesis develops, it has been known that Cluster of Differentiation (CD44) , as an adhesion molecule, plays an important role in these processes.CD44 is a transmembrane glycoprotein. The gene contains at least 20 exons and introns which is scattered in exons. According to the types of exon, one molecules known as CD44s and another containing the variable exons or their peptide products are designated CD44v. CD44s is ubiquitously expressed in normal tissues, but CD44v expression is restricted. The functions of CD44 include: cell adhesion, lymphocyte homing and activation, myelopolisis and angio-genesis. Tumor cells express different CD44 isoforms, and its expression is tissue specific. The main reason of CD44 involving in tumor growth and metastasis is that it can change cell adhesion and to signal to both the locomotory and mitogenic machinery of the cell. CD44 can also induce the tumor cells to produce autocrine growth factors. CD44 has the ability to take up and degrade hyaluronate and this property could allow tumor cells to detachment. CD44 might also assist in thefunction of tumorgenesis of other oncogenes such as Ras. The interrelation between CD44 and tumor has been confirmed in many tumors and cell lines. There is little research on the relation of CD44 and normal bone and bone tumor. What is less is the study on the expression of CD44v6 in bone tumors with different biological behavior.MaterialsAll samples were taken from the Department of Pathology of Chinese Medical University from 1992 to 2001. The samples are well preserved in paraffin blocks. Cutting in 5um sections. In each the tumor diagnosis was based on histopathological examination. The samples include 23 cases osteosarcoma, 34 cases giant cell tumor of bone (GCTB) (Jaffe I 15 cases, II 15 cases and III 4 cases) and 23 cases osteochondroma as control. Monoclonal antibody rat against human CD44v6 was produced by Maxim. Co. Fujian.MethodIn this study, we use a standard S - P immunohistochemical staining procedure to detect the expression of CD44v6 in 23 cases osteosarcoma, 34 cases giant cell tumor of bone and compare to 23 cases osteochondroma. CD44v6 staining is yellow - brown on membrane. We scored 10 high visual random in double - blind way. The antibody staining intensity was scored on a visual scale as - meaning no staining; + for weak staining, positive cells <25% ; ++corresponding moderate staining, positive cells 25% to 50% and +++ for strong antibody binding, positive cells > 50%. x2 test was used to analyzed thedata.Results53. 85% of osteosarcoma expressed CD44v6 and 26. 47% of GCTB expressed CD44v6. None of the samples of osteochondroma was stained. The expression of CD44v6 in osteochondroma is negative. Significant statistical correlation of CD44v6 expression was found in either osteosarcoma or GCTB compared with osteochondroma. Significant statistical correlation of CD44v6 expression was also found in grade II - Iff of GCTB compared with grade I . The difference of CD44v6 expression between osteosarcoma and GCTB is significant. The difference of CD44v6 expression is not significant between osteosarcoma and GCTB grade II -III.DiscussionCD44 is a transmembrane glycoprotein, encoded on the short arm of chromosome 11. Gene length is 50 Kb. The genetic sequence contains at least 20 exons and introns, which inserted in exons. The genetic sequence contains constant and variable exons. According to the type of exon, CD44 molecules can be divided into two groups: the u-biquitously expressed standard isoform ( abbreviated to CD44s ) and CD44v which molecules containing the variable exons or their peptide products. Variation occurs at the transcription stage and the splicing together of exons to form mRNA is called alterna...