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The Ste20 kinase MST4 plays a role in prostate cancer progression
Victoria Sung1, Wen Luo, Dapeng Qian
1SUGEN, Inc., South San Francisco, California 94080, USA.
Abstract:
MST4, a member of the Sterile 20 serine/threonine kinase family, was found to be expressed in prostate carcinoma tumor samples and cell lines. In addition, expression levels appeared to correlate with tumorigenicity and androgen receptor status of the cells. Ectopic expression of wild-type and kinase-inactive MST4 was used to alter cellular MST4 activity levels in three widely studied human prostate tumor cell lines: LNCaP, DU 145, and PC-3. Overexpression of wild-type MST4 induced anchorage-independent growth of the LNCaP cell line, and increased both in vitro proliferation and in vivo tumorigenesis of the DU 145 cell line. On the other hand, expression of a kinase-inactive form reverted the anchorage-independent growth phenotype and highly tumorigenic behavior of the PC-3 cell line. MST4 kinase activity was stimulated significantly by epidermal growth factor receptor ligands, which are known to promote growth of prostate cancer cells. Together, our studies suggest a potential role for MST4 in the signal transduction pathways involved in prostate cancer progression.
Insights
The serine/threonine kinase MST4 is expressed in prostate cancer and influences tumor growth. Its activity, regulated by growth factors, suggests a role in prostate cancer progression.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Prostate carcinoma exhibits varying expression of MST4, a Sterile 20 kinase family member.
- MST4 expression levels correlate with prostate tumor cell tumorigenicity and androgen receptor status.
Purpose of the Study:
- To investigate the role of MST4 in prostate cancer progression.
- To determine how MST4 activity affects prostate tumor cell behavior and tumorigenesis.
Main Methods:
- Ectopic expression of wild-type and kinase-inactive MST4 in LNCaP, DU 145, and PC-3 human prostate cancer cell lines.
- Assessing anchorage-independent growth, in vitro proliferation, and in vivo tumorigenesis.
- Investigating MST4 kinase activity modulation by epidermal growth factor receptor (EGFR) ligands.
Main Results:
- Overexpression of wild-type MST4 promoted anchorage-independent growth in LNCaP cells and enhanced proliferation and tumorigenesis in DU 145 cells.
- Expression of kinase-inactive MST4 reversed anchorage-independent growth and tumorigenic behavior in PC-3 cells.
- MST4 kinase activity was significantly stimulated by EGFR ligands, known prostate cancer growth promoters.
Conclusions:
- MST4 plays a significant role in prostate cancer progression.
- MST4 kinase activity is implicated in the signal transduction pathways driving prostate cancer growth and tumorigenesis.
- Targeting MST4 may offer a therapeutic strategy for prostate cancer.