Invasion and metastasis of triple-negative breast cancer mediated by the PSME3-NF-kappaB pathway

Abstract:

Objective：To investigate the effect of proteasome activator complex subunit 3（PSME3） on the invasion and metastasis of triple-negative breast cancer（TNBC） and its mechanism. Methods：The samples collected from TNBC patients were used to detect the expression of PSME3 by immunohistochemistry. The TNBC cell line MDA-MB-231 was used to construct PSME3 overexpression and interference stable strains using the lentiviral packaging system. The mRNA expression of PSME3 was determined by real-time PCR and the protein expression of PSME3 was measured by Western blot. The cell lines were divided into PSME3 overexpression（exPSME3） group，short hairpin RNA targeting PSME3（shPSME3） group，and wild-type control group. When Western blot was used to identify stable strains，PSME3 expression negative control（exNC） group and short hairpin RNA targeting negative control（shNC） group were included in order to exclude the effect of the vector itself on PSME3 expression. The cell migration ability and in－vasion ability were evaluated by wound healing assay and Tran－swell assay，respectively. The expression of vascular endothelial growth factor-A（VEGF-A） and matrix metalloproteinase-9（MMP-9）（migration-related proteins） in each group was mea－sured by Western blot. The protein expression of nuclear factor-kappaB（NF-kappaB） and its active group — phosphorylated-P65（P-P65） was determined by cell slide immunofluorescence and Western blot，respectively. Results：Immunohistochemical results showed that PSME3 expression was significantly higher in the tumor tissues of TNBC patients than in the adjacent tissues（t=36.700，P=0.000）. The wound healing assay indicated that compared with the control group，the migration ability was significantly higher in the exPSME3 group（P=0.000） and significantly lower in the shPSME3 group（P=0.009）. Western blot results showed that compared with the control group，the expression of VEGF-A and MMP-9 was signif－icantly higher in the exPSME3 group and significantly lower in the shPSME3 group. Transwell assay revealed that compared with the control group，the invasion ability was significantly higher in the exPSME3 group（P=0.000） and significantly lower in the shPSME3 group（P=0.000）. Cell slide immunofluorescence results showed that there was no significant difference in the expression of NF-kappaB between the three groups；compared with the control group，the expression of P-P65 was significantly higher in the exPSME3 group（P=0.001） and significantly lower in the shPSME3 group（P=0.001），which was in accordance with Western blot results. Conclusion：The PSME3-NF-kappaB pathway can mediate the invasion and metastasis of TNBC.