[Analysis of differentiation characters in osteosarcoma Mdr sublines].

OBJECTIVE: To explore the relationship between multidrug resistance (Mdr) and malignancy. To observe whether P-glycoprotein (P-gp) overexpression had the same bioactivity as osteogenic stem cell turning into more mature cell or more complex phenotype when parent cell line turned to Mdr phenotype. METHODS: Six cell sublines of Mdr phenotype with different expression degree were analyzed. Stathmin generally identified in malignancy cell and stem cell, was a microtubule associated protein and the signal of differentiation in osteogenic stem cell. RT-PCR and hybridization in situ were used to analyze the relationship between Mdr1 mRNA and expression of Stathmin mRNA and VEGF mRNA. RESULTS: Morphological and functional analysis of Mdr phenotype showed the P-gp-positive cell lines were more differentiated than the parent cells in terms of enhanced activity of cellular alkaline phosphatase. These subclones all displayed a decrease in potential malignancy such as tumor growth rate and metastatic ability. A significant negative correlation could be identified between Mdr1 mRNA and expression of VEGF and Stathmin mRNA. CONCLUSION: Expression of Mdr1/P170 indicated osteosarcoma cells differentiated towards more mature state, which will develop the new research field of Mdr and supply the new research method of the function of P- gp.