[The role of CD44 in the proliferation, adhesiveness and invasiveness of osteosarcoma cell lines]

OBJECTIVE To study the influence of CD44 a cell-matrix adhesion molecule on the proliferation, adhesiveness and invasiveness of osteosarcoma cell lines, in order to investigate the growth and invasion mechanism of osteosarcoma. METHODS Three osteosarcoma cell lines MG-63, HOS and U2-OS were routinely cultured. Flow cytometry and Western blot analysis were used for detecting the positive rates and relative amount of CD44 protein in the three cell lines. RT-PCR method was also used to compare the differences in the expression of CD44 mRNA among the 3 cell lines. Then, MTT method, adhesion detection, and Microcon-migration assay were used to detect the changes of the cells' proliferation rate, adhesive and invasive abilities after blocking the role of CD44 by using a special neutralizing antibody. RESULTS The results of flow cytometry showed that the percentage of CD44 positive cells were both over 99% in HOS and U2-OS, while that in MG-63 was only (2.10 +/- 0.46)%. The average fluorescence density of CD44 in HOS was significantly higher than in U2-OS. Western blot also showed that the relative content of CD44 protein in HOS was notably higher than that in U2-OS, while CD44 was negatively expressed in MG-63. The expression of CD44 mRNA was significantly lower in MG-63 than in both HOS and U2-OS, which were consistent with the expression of CD44 protein. The proliferation rates and adhesive abilities of MG-63 and HOS have no significant difference, but both were significantly higher than that of U2-OS. The invasive abilities of HOS was dramatically higher than MG-63 and U2-OS. After the role of CD44 was blocked by anti-CD44 neutralizing antibody, the proliferation rates of the 3 cell lines did not change significantly. While the HOS and MG-63 adhesion indices decreased dramatically (P < 0.05), the invasive abilities of HOS and U2-OS also decreased notably (P < 0.01). CONCLUSIONS CD44 could promote the adhesiveness and invasiveness of osteosarcoma cell line HOS. CD44 may take part in promoting the process of U2-OS invasion and the adhesion of MG-63. On the other hand, CD44 could not affect the osteosarcoma cell proliferation rates.