OBJECTIVESTo evaluate the expression of synuclein-γ (SNCG) and metalloproteinase 9 (MMP-9) both in the invasive ductal breast cancer samples and T47D and T47D(SNCG)- cell lines, to investigate the correlation between SNCG and MMP-9.

METHODSTotally 96 invasive ductal breast cancer samples (female, mean age of (56 ± 8) years) were collected between June 2009 and June 2012. The expressions of SNCG and MMP-9 were investigated by immunohistochemistry. T47D and SNCG knock down T47D(SNCG)- cell lines were established and SNCG and MMP-9 protein expression were investigated by Western blot and gene expression by real-time PCR.

RESULTSAmong 96 samples, 26 (27.1%) of them co-expressed SNCG and MMP-9, 30(31.2%) of them expressed neither SNCG nor MMP-9. The expression of SNCG was correlated with the expression of MMP-9 (r = 0.655, P = 0.000).SNCG mRNA level of T47D cell line was 13.5 fold of T47D(SNCG)- cell line and SNCG protein expression was 2.1 fold. While MMP-9 mRNA level of T47D cell line was 7.3 fold of T47D(SNCG)- cell line and MMP-9 protien expression was 1.6 fold.When SNCG was knocked down, the expression of MMP-9 decreased.

CONCLUSIONSSNCG and MMP-9 are significantly correlated with each other in breast cancer. SNCG may promote the invasion and metastasis of breast cancer mediated by up-regulating the expression of MMP-9.