Rab27amrna And Human Breast Cancer Cell Invasion And Metastasis Correlation Between In Vitro And In Vivo Study

Objective To detect expression,localization of Rab27A in human breast cancer cells and furthermore,to investigate the association between Rab27AmRNA and human breast cancer cells metastasis in vivo and vitro.Methods Semi-quantitative realtime RT-PCR and Western blot were used to quantitatively examine the differential expression of Rab27A mRNA and protein in breast cancer cells.To further examine the effects of Rab27A over expression on tumor growth and metastasis,we performed the in vivo assay using an orthotopic xenograft tumor model in the athymic mice.We examined the primary tumor growth in MFP and the pulmonary metastasis by H&E section.Results The expression of Rab27A mRNA increased as invasive and metastatic ability increased.Western blot also showed that breast cancer cell lines differentially expressed Rab27A protein which was 2.83-,4.9-and 9.19-fold in MDA-MB-231,MDA-MB-435 and MDA-MB-435HM respectively compared to that in MCF-7 as determined by densitometric analyses (P＜0.05 or P＜0.01).Rab27A was found to be targeted to diffuse in cytoplasm in three breast cancer cell lines and particularly concentrated in perinuclear in MDA-MB-231 and MDA-MB-435 cells. Rab27A transfectants doubled the volume of primary tumor in comparasion to mock transfected and parental cells at the end of the in vivo assays(P＜0.01) and induced much more haemorrhage and necrosis.The rate of pulmonary metastasis in nude mice was dramatically increased by Rab27A overexpression especially in MDA-MB-231 cells(P＜0.01).We found 2.5 times more metastases per lung from mice bearing Rab27A transfectants than parental and mock transfected cells(P＜0.01). Conclusion The expression of Rab27A increased in human breast cancer cells as invasive and metastatic potential increased,indicating possible involvement of Rab27A in invasive and metastatic phenotypes of breast cancer cells.