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RSK4 knockdown promotes proliferation, migration and metastasis of human breast adenocarcinoma cells
Jia Zhu1, Qiu-Yun Li1, Jian-Lun Liu1
1Department of Breast Surgery, The Affiliated Tumor Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China.
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.
Insights
Downregulating RSK4 (ribosomal S6 kinase 4) expression in breast cancer cells promotes cell proliferation and invasion. Silencing RSK4 may be a therapeutic target for breast cancer treatment.
Area of Science:
- Molecular Biology
- Oncology
- Cancer Research
Background:
- RSK4 (ribosomal S6 kinase 4) is known to inhibit the growth of certain cancer cells.
- Understanding RSK4's role is crucial for developing targeted breast cancer therapies.
Purpose of the Study:
- To construct a lentiviral vector (Lenti-RSK4-shRNA) to specifically inhibit RSK4 expression in MCF-7 breast cancer cells.
- To investigate the impact of RSK4 gene silencing on breast cancer cell proliferation and invasion, both in vitro and in vivo.
Main Methods:
- Stable transfection of MCF-7 cells with Lenti-RSK4-shRNA.
- Quantitative RT-PCR and Western blot to confirm RSK4 knockdown.
- MTT assays, flow cytometry, and Transwell assays for proliferation and invasion analysis.
- Xenograft nude mouse models to assess in vivo tumorigenicity and gene expression changes.
Main Results:
- Successful and significant reduction in RSK4 mRNA and protein expression in transfected MCF-7 cells.
- RSK4-shRNA group exhibited significantly increased cell proliferation, S-phase population, and invasion compared to controls.
- In vivo studies confirmed that RSK4 knockdown promoted tumorigenicity and migration.
- Silencing RSK4 led to decreased expression of E-cadherin and increased expression of Ki-67, cyclin D1, and CXCR4.
Conclusions:
- Downregulation of RSK4 expression is linked to enhanced tumor cell proliferation and invasion in breast cancer.
- RSK4 may function as a tumor suppressor gene in breast cancer.
- Targeting RSK4 through gene silencing presents a potential therapeutic strategy for breast cancer treatment.
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