Expression and significance of osteopontin and cluster of differentiation 44v6 in brain metastatic tumors

Objective To detect the expression of osteopontin (OPN) and cluster of differentiation 44v6 (CD44v6) in brain metastatic tumors,and to explore their role in the formation and invasion of metastases.Methods By reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical (SP) techniques,the expression of OPN and CD44v6 mRNA and protein was detected in brain metastatic tumors,primary tumor and normal brain tissue.The correlation of their expression was assayed by using statistical methods.Results The relative expression levels of OPN and CD44v6 mRNA were 0.82 ± 0.05 and 0.77 ± 0.05 respectively in brain metastases,and 0.75 ± 0.07 and 0.69 ± 0.04 in primary tumors,which were obviously higher than those in human normal brain tissue (P ＜ 0.05).The positive expression rate of OPN and CD44v6 protein was 92％ (46/50) and 88％ (44/50) respectively in brain metastases,which was obviously higher than that in human normal brain tissue too (P ＜ 0.05).The expression of OPN mRNA and protein had a positive correlation with that of CD44v6 in metastases (r =0.632,P ＜ 0.01 ; r =0.915,P ＜ 0.05).Conclusion The over-expression of OPN and CD44v6 played an important biological role in the formation of brain metastatic tumors,and they showed a synergistic effect. Key words: Osteopontin;  Cluster of differentiation 44v6 ;  Brain metastatic tumor