Signal transduction of phorbol 12-myristate 13-acetate (PMA)-induced growth inhibition of human monocytic leukemia THP-1 cells is reactive oxygen dependent

Traore, Kassim; Trush, Michael A.; George, Matthew; Spannhake, Ernst Wm.; Anderson, Winston; Asseffa, Amha

doi:10.1016/j.leukres.2004.12.011

« Previous Next »Leukemia Research
Volume 29, Issue 8 , Pages 863-879, August 2005

Signal transduction of phorbol 12-myristate 13-acetate (PMA)-induced growth inhibition of human monocytic leukemia THP-1 cells is reactive oxygen dependent

Kassim Traore
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, Washington, DC, USA
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, USA
- Corresponding author. Tel.: +1 410 955 9645; fax: +1 410 955 0116.
Michael A. Trush
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, USA
Matthew George Jr.
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, Washington, DC, USA
Ernst Wm. Spannhake
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, USA
Winston Anderson
- Department of Biology, College of Arts and Sciences, Howard University, Washington, DC, USA
Amha Asseffa
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, Washington, DC, USA

Received 19 July 2004; accepted 19 December 2004. published online 07 March 2011.

Abstract

Human monocytic THP-1 cells can be induced to differentiate to macrophages when treated with phorbol 12-myristate 13-acetate (PMA). It is understood that before initiating cell differentiation, PMA treatment must first induce an inhibition of cell growth. Since the initial biochemical and molecular events that are associated with this growth inhibition have not been characterized, the present study was carried out to elucidate the molecular mechanisms associated with the PMA-induced growth arrest of THP-1 cells. Our results indicate that PMA inhibits THP-1 cells at G₁-phase of the cell cycle, via a complex mechanism associated with the modulation of the expression of several cell cycle regulators, initiated by the cellular generation of reactive oxygen species (ROS). Both p21^WAF1/CIP1 mRNA and protein were upregulated 24h post PMA treatment as demonstrated by ribonuclease protection assay and Western blotting, respectively. Because these cells lack functional p53, this effect was independent of p53 activity. Electrophoretic mobility shift assay showed that the PMA-induced activation of the p21^WAF1/CIP1 promoter was driven by the specific protein 1 (Sp1) transcription factor through Sp1-binding sites. Additionally, our study demonstrates that PMA-induces the upregulation of p21 through a protein kinase C (PKC)-mediated ROS-dependent signaling mechanism involving MAP kinase activation.