Silencing RAB27a inhibits proliferation, invasion and adhesion of triple-negative breast cancer cells / 南方医科大学学报

OBJECTIVE@#To investigate the effect of inhibition of RAB27 protein family, which plays a pivotal role in exosome secretion, on biological behaviors of triple-negative breast cancer cells.@*METHODS@#Quantitative real-time PCR and Western blotting were used to examine the expressions of RAB27 family and exosome secretion in 3 triple-negative breast cancer cell lines (MDA-MB-231, MDA-MB-468, and Hs578T) and a normal breast epithelial cell line (MCF10A). The effect of small interfering RNA (siRNA)-mediated silencing of RAB27a and RAB27b on exosome secretion in the 3 breast cancer cell lines was detected using Western blotting, and the changes in cell proliferation, invasion and adhesion were evaluated.@*RESULTS@#Compared with normal breast epithelial cells, the 3 triple-negative breast cancer cell lines exhibited more active exosome secretion (P < 0.001) and showed significantly higher expressions of RAB27a and RAB27b at both the mRNA and protein levels (P < 0.01). Silencing of RAB27a in the breast cancer cells significantly down-regulated exosome secretion (P < 0.001), while silencing of RAB27b did not significantly affect exosome secretion. The 3 breast cancer cell lines with RAB27a silencing-induced down-regulation of exosome secretion showed obvious inhibition of proliferation, invasion and adhesion (P < 0.01) as compared with the cell lines with RAB27b silencing.@*CONCLUSION@#RAB27a plays central role in the exosome secretion in triple-negative breast cancer cells, and inhibiting RAB27a can inhibit the proliferation, invasion and adhesion of the cells.

Differentially quantitative proteome of MHCC97H after Rab27B knock-down:a preliminary study / 军事医学

Objective To discover the vital role of Rab27B in tumor cells and its potential molecular mechanism by means of quantitative proteomics analysis of Rab27B knockdown in MHCC97H.Methods The expression of Rab27B in MHCC97H cells was knocked down by the combination of Tet-on advanced inducible expression system and RNA interference technology.Then, proteins extracted from the cells were identified by LC-MS/MS system after FASP digestion and iTRAQ 4-plex labeling. Finally, the properties of differentially expressed proteins, including the subcellular localizations, biological processes and molecular functions, were analyzed by the bioinformatics method.Results There were 448 differentially expressed proteins (|Ratio|>1.21, P<0.05) identified in MHCC97H cells after Rab27B knock-down.The expression levels of 229 or 219 proteins were positively or negatively correlated with Rab27B, respectively. These differentially expressed proteins were mainly involved in vesicle transport, macromolecule localization, cellular response to stimulus.Furthermore, there were 26 differentially expressed proteins participating in 8 tumor-related signal pathways, eleven of which were in the focal adhesion signal pathway.Conclusion The analysis of quantitative proteomics in Rab27B-knockdown MHCC97H cell line by iTRAQ suggests that Rab27B not only has an impact on the exosomal secretion of tumor cells, but also regulates master proteins in signal pathways involved in cell proliferation and migration.