ShRNA-mediated knock-down of CXCR7 increases TRAIL-sensitivity in MCF-7 breast cancer cells

Abstract

This study aims to investigate the effects of CXCR7-shRNA on TRAIL-mediated apoptosis and suppression of invasive migration and the underlying mechanisms. (1) We constructed CXCR-7-shRNA lentiviral vectors and confirmed their silencing efficiency in MCF-7 cells by RT-PCR analysis. (2) The effects of CXCR7 and/or TRAIL on cell proliferation were examined by MTT assay. (3) Trans well invasion assay was used to examine the effects of CXCR7 silencing and/or TRAIL on MCF-7 cell invasive migration. (4) Expression of Caspase-3, and Caspase-8, and MMP-2 and MMP-9 proteins was examined by Western blot analysis. (1) Viral titers were 2.95 × 10(8) TU/ml, 3.01 × 10(8) TU/ml, 3.26 × 10(8) TU/ml, and 3.08 × 10(8) TU/ml, respectively. (2) CHXR7 shRNAs markedly decreased CXCR7 mRNA expression in MCF-7 cells, among which CXCR7-shRNA-1 showed significantly higher rate of inhibition (P < 0.05). (3) Combination of TRAIL and CXCR7-shRNA-1 resulted in marked suppression of cell proliferation in time-dependent manner (P < 0.05). (4) Cell invasion capacity was inhibited in each experimental group as compared to blank control group at 48 h post treatments (P < 0.05). Among them, combination of TRAIL and CXCR7-shRNA had the highest inhibitory effect (P < 0.05). (5) Western blot analysis indicated that TRAIL alone does not affect CXCR7 expression, but either TRAIL + CXCR7 shRNA or CXCR7 shRNA alone markedly suppressed CXCR7 protein expression. Furthermore, combination of TRAIL and CXCR-7-shRNA significantly increased Caspase-3 and Caspase-8 expression and decreased MMP-2 and MMP-9 expression (P < 0.05). Knock-down of CXCR-7 expression leads to augmented TRAIL-mediated suppression of MCF-7 cell proliferation and invasion.

The Role of the CXCL12/CXCR4/CXCR7 Chemokine Axis in Cancer

“…CXCR7 overexpression reduces the apoptotic fraction in prostate cancer cells and protects these cells from apoptosis (Wang et al, 2008a). Likewise, knockdown of CXCR7 in the MCF7 breast cancer cell line increased the expression of the proapoptotic caspase three and eight proteins (Gao et al, 2015).…”

Atypical chemokine receptors in cancer: friends or foes?

“…ACKR3 promotes cancer cell growth, inducing ERK1/2 phosphorylation and inhibiting apoptosis in breast cancer [72]. In breast and prostate cancer, ACKR3 forms heterodimers with EGFR and stimulates its signaling promoting tumor-cell proliferation in a ligand-independent manner [73][74][75].…”

The Role of ACKR3 in Breast, Lung, and Brain Cancer

“…Decreasing ACKR3 levels alters expression of cell cycle-related proteins and leads to cell cycle arrest, hence reducing cell proliferation (Salazar et al, 2014). Additionally, knock down of the receptor in the MCF7 breast cancer cell line increased the expression of the proapoptotic caspase 3 and 8 proteins (Gao et al, 2015). In addition, ACKR3 expression enhances breast cancer proliferation through signal transducer and activator of transcription 3 activation, which has previously been linked to apoptosis resistance and cell cycle progression in invasive breast cancer (Wani et al, 2014;Li et al, 2015).…”

“…Several in vitro and in vivo studies have found that higher levels of ACKR3 result in increased cell proliferation and invasive migration, promoting tumor growth and metastasis (Miao et al, 2007;Xue et al, 2013;Gao et al, 2015;Li et al, 2015). However, the molecular mechanisms linking enhanced ACKR3 expression to these processes are not fully elucidated.…”

“…Migration and invasion events require degradation of basement membrane extracellular matrix proteins by matrix metalloproteinases (MMPs). ACKR3 expression is associated with the secretion of MMP2, MMP3, and MMP9 (Zabel et al, 2010;Gao et al, 2015). ACKR3 overexpression also accompanies mesenchymal-to-epithelial transition, a pathway leading to metastatic events (Leontovich et al, 2012).…”