Hydrogen Peroxide Stimulates Proliferation and Migration of Human Prostate Cancer Cells through Activation of Activator Protein-1 and Up-regulation of the Heparin Affin Regulatory Peptide Gene

Abstract

It is becoming increasingly recognized that hydrogen peroxide (HP) plays a role in cell proliferation and migration. In the present study we found that exogenous HP significantly induced human prostate cancer LNCaP cell proliferation and migration. Heparin affin regulatory peptide (HARP) seems to be involved in the stimulatory effect of HP, because the latter had no effect on stably transfected LNCaP cells that did not express HARP. Moreover, HP significantly increased HARP mRNA and protein amounts in a concentration-and time-dependent manner. Curcumin and activator protein-1 (AP-1) decoy oligonucleotides abrogated both HPinduced HARP expression and LNCaP cell proliferation and migration. HP increased luciferase activity of the 5-flanking region of the HARP gene introduced in a reporter gene vector, an effect that was abolished when even one of the two putative AP-1 binding sites of the HARP promoter was mutated. The effect of HP seems to be due to the binding of Fra-1, JunD, and phospho-c-Jun to the HARP promoter. These results support the notion that HARP is important for human prostate cancer cell proliferation and migration, establish the role of AP-1 in the up-regulation of HARP expression by low concentrations of HP, and characterize the AP-1 dimers involved.A growing body of evidence correlates the production of reactive oxygen species with many aspects of cellular functions (1). Reactive oxygen species include the superoxide, hydrogen peroxide (HP), 2 and the hydroxyl radical. Of these, HP has the chemical stability required to establish significant steady-state concentrations in vivo (2, 3) and is small and uncharged, properties that allow it to freely diffuse across plasma membranes and make it an ideal candidate for a signaling molecule (4). Small quantities of HP are produced by all types of cells, and several signal transduction pathways in mammalian cells have been reported to be activated by HP, such as tyrosine kinases, mitogen-activated protein kinases, protein kinase C, the epidermal growth factor receptor, protein phosphatases, potassium channels, and the transcription factors activator protein-1 (AP-1), and nuclear factor B (reviewed in ref. 1).Heparin affin regulatory peptide (HARP), also called pleiotrophin or heparin-binding growth-associated molecule, is an 18-kDa secreted growth factor that displays high affinity for heparin. A growing body of evidence indicates that HARP is involved in cell proliferation, migration, and differentiation and plays a significant role in several cellular processes (5, 6). HARP seems to play a major role in physiological as well as tumor angiogenesis and is detected in various carcinomas, such as human breast and prostate cancer, neuroblastomas, gliomas, benign meningiomas, and small cell lung cancer and mammary tumors, exhibiting a proto-oncogene function (5-8).HARP is highly conserved among human, rat, bovine, and mouse species, and its gene is expressed in a highly restricted temporal and spatial pattern during development, suggesting that HARP may be an ...

JunD Is Required for Proliferation of Prostate Cancer Cells and Plays a Role in Transforming Growth Factor-β (TGF-β)-induced Inhibition of Cell Proliferation

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