RSK4 knockdown promotes proliferation, migration and metastasis of human breast adenocarcinoma cells

Abstract

Abstract. RSK4 has been shown to inhibit the growth of certain cancer cells. The aim of this study was to construct a lentiviral vector of RSK4-shRNA (Lenti-RSK4-shRNA) to specifically block the expression of RSK4 in the human breast adenocarcinoma cell line MCF-7, and investigate the effect of the RSK4 gene on cell proliferation and invasion in vitro and in vivo. Lenti-RSK4-shRNA was stably transfected into MCF-7 cells. RSK4 mRNA and protein expression were measured by fluorescence quantitative RT-PCR and western blot analysis. Cell proliferation was evaluated by MTT assays and flow cytometric analysis. Invasion was evaluated by Transwell assays and xenograft nude mouse models. The expression of RSK4 mRNA, Ki-67 mRNA, cyclin D1 mRNA, CXCR4 mRNA and E-cadherin mRNA of tumor xenografts were detected by fluorescence quantitative RT-PCR. Significant decreases in RSK4 mRNA and protein expression was detected in MCF-7 cells carrying lentiviral RSK4-shRNA vector. The cell proliferation was significantly promoted in the RSK4-shRNA group as compared to that in the negative and blank control group. In addition, the number of cells in the S phase in the RSK4-shRNA group was significantly greater than the blank and negative control groups (P<0.05). Furthermore, the number of invading cells was increased in the RSK4-shRNA (P<0.05). In vivo, we also found that the knockdown of RSK4 promoted tumorigenicity and migration in the xenograft nude mouse model. In addition, we showed that the RSK4 mRNA and E-cadherin mRNA expression were significantly lower in the RSK4-shRNA group compared to that in negative and blank control group (both P<0.05), while the Ki-67 mRNA, cyclin D1 mRNA and CXCR4 mRNA were higher in the shRNA group compared to that in negative and blank control group (both P<0.05). In conclusion, downregulation of RSK4 expression is indicated to be associated with tumor cell proliferation and invasion, and silencing of the RSK4 may be involved in the development and progression of breast cancer through the changes of Ki-67, cyclin D1, CXCR4 and E-cadherin, and suggesting that RSK4 may act as a potential cancer suppressor gene and therapeutic target for the treatment of breast cancer.

Aberrant expression of RSK4 in breast cancer and its role in the regulation of tumorigenicity

“…Further investigation also showed that the downregulation of RSK4 expression in breast cancer cells is mediated by gene expression inhibition through promoter hypermethylation, which frequently occurs in breast cancer cells (13). Consistently, RSK4 knockdown in human breast adenocarcinoma cells significantly promoted proliferation and migration, which further confirms the role of RSK4 in the development and progression of breast cancer (14).…”

“…cells further confirmed its critical role in regulating breast cancer progression. Combined with other publications about RSK4 and breast cancer (3,13,14), recent evidence provides an important research basis for the future application of RSK4 in breast cancer screening, diagnosis and therapy, although large prospective clinical studies should be performed to establish its predictive value in patients with breast cancer.…”

“…In human breast adenocarcinoma cells with silenced RSK4 gene expression, the mRNA expression levels of RSK4 and E-cadherin were significantly downregulated while the expression of Ki-67, cyclin D1 and CXCR4 was markedly increased. These results suggest that these genes are in the downstream signaling during RSK4-regulated cell fate decision (14). The 90-kDa ribosomal S6 kinases (RSKs) belong to serine kinases that are activated by growth factors through the Ras-dependent mitogen-activated protein (MAP) kinase cascade including MEK and extracellular signal-regulated kinase (ERK) (7).…”

microRNA from brush biopsy to characterize oral squamous cell carcinoma epithelium

“…It can regulate cell survival, angiogenesis, tissue invasion, DNA damage resistance, and EMT . Of the six mRNAS identified in the neurotrophin signaling pathway targeted by the miRNAs (Table ) that showed at least 2× fold change in level, RPS6KA6 and PIK3R1 tumor suppressors that work to inhibit the oncogene PIK3CA were both decreased . SORT1 mRNA was also decreased.…”

<p>Effect of RSK4 on Biological Characteristics of Gastric Cancer</p>

“…[5][6][7][8][9] Several reports have identified RSK4 as a tumor suppressor in the colon, breast, and renal carcinomas. [10][11][12][13] The over-expression of RSK4 could restrict cell growth, demonstrating anti-invasive and anti-metastatic effects. 14,15 In addition, RSK4 is recommended as a useful prognostic marker in patient evaluation.…”