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Krüppel-like factor 4 (gut-enriched Krüppel-like factor) inhibits cell proliferation by blocking G1/S progression of
X Chen1, D C Johns, D E Geiman
1Departments of Medicine and Biological Chemistry, and the Johns Hopkins Oncology Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Abstract:
Krüppel-like factor 4 (KLF4) is an epithelial cell-enriched, zinc finger-containing transcription factor, the expression of which is associated with growth arrest. Previous studies show that constitutive expression of KLF4 inhibits DNA synthesis but the manner by which KLF4 exerts this effect is unclear. In the present study, we developed a system in which expression of KLF4 is controlled by a promoter that is induced upon treatment of cells containing the receptors for the insect hormone, ecdysone, with ponasterone A, an ecdysone analogue. The rate of proliferation of a stably transfected colon cancer cell line, RKO, was significantly decreased following addition of ponasterone A when compared with untreated cells. Flow cytometric analyses indicated that the inducible expression of KLF4 caused a block in the G(1)/S phase of the cell cycle. A similar block was observed when ecdysone receptor-containing RKO cells were infected with a replication-defective recombinant adenovirus containing an inducible KLF4 and treated with ponasterone A. Results of these studies provide evidence that the inhibitory effect of KLF4 on cell proliferation is mainly exerted at the G(1)/S boundary of the cell cycle.
Insights
Krüppel-like factor 4 (KLF4) inhibits cell proliferation by halting the cell cycle at the G(1)/S phase. This study clarifies KLF4
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Krüppel-like factor 4 (KLF4) is a transcription factor linked to growth arrest.
- Previous research indicates KLF4 inhibits DNA synthesis, but the mechanism remains unclear.
Purpose of the Study:
- To elucidate the mechanism by which KLF4 inhibits cell proliferation.
- To investigate the role of KLF4 in cell cycle regulation.
Main Methods:
- Developed an inducible expression system for KLF4 using ponasterone A and ecdysone receptors.
- Utilized stably transfected colon cancer cell line (RKO) and recombinant adenovirus.
- Performed flow cytometric analyses to assess cell cycle progression.
Main Results:
- Inducible KLF4 expression significantly decreased RKO cell proliferation.
- KLF4 induction caused a cell cycle block at the G(1)/S phase.
- Similar G(1)/S phase block observed with adenovirus-mediated KLF4 delivery.
Conclusions:
- KLF4 exerts its inhibitory effect on cell proliferation primarily at the G(1)/S boundary.
- KLF4 plays a critical role in regulating cell cycle progression.
- The inducible system provides a tool for studying KLF4 function.