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Degree

Doctor of Philosophy in Medical Sciences (Ph.D.), University of Toledo Health Science Campus, Graduate School, 2005.

Abstract

Arachidonic acid metabolism leads to the production of biolipid mediatiors with important roles in multiple pathological processes including prostate cancer. Expression of platelet-type 12-lipoxygenase (P12-LOX) correlates with clinical stage and grade of prostate adenocarcinoma and overexpression in prostate cancer cells leads to large, highly vascularized tumors in a mouse model. The product of arachidonic acid metabolism via P12-LOX is 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), a lipid previously linked to angiogenesis. Although P12-LOX and its product, 12(S)-HETE, have been shown to play a role in prostate cancer biology, an underlying mechanism has yet to be characterized. Thus, PC-3 prostate cancer cells overexpressing P12-LOX were employed to define the function of 12(S)-HETE as an angiogenic factor. Overexpression of P12-LOX in prostate cancer cells resulted in increased 12(S)-HETE production and enhanced accumulation of the potent angiogenic protein vascular endothelial growth factor (VEGF). Elevated basal phosphorylation of the extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen activated protein kinase (MAPK) was found in cells overexpressing P12-LOX. Incubation of PC-3 and DU145 prostate cancer cells with 12(S)-HETE resulted in a significant increase in phosphorylated ERK1/2, whereas preincubation with pharmacological inhibitor/s of MEK and pertussis toxin (PTx) sensitive G-protein coupled receptors (GPCR) blocked 12(S)-HETE induced ERK1/2 phosphorylation. Additionally, inhibition of both MEK and PTx sensitive GPCRs reduced VEGF accumulation in culture media of cells overexpressing P12-LOX. These results indicate that P12-LOX overexpression by prostate cancer cells, a condition mirrored in prostate cancer patients, may have the untoward effect of increasing VEGF production and that this effect is due to the stimulation of ERK1/2 by 12(S)-HETE in a PTx sensitive GPCR mediated manner. Inhibition of P12-LOX in the treatment of prostate cancer is currently not a viable therapeutic strategy due to a lack of lipoxygenase inhibitor specificity. Using X-ray crystallographic analysis, the 3D interaction of curcumin with soybean lipoxygenase-3 was examined. These pilot studies may help in the development of novel, highly specific inhibitors of P12-LOX. Taken together, these data show that P12-LOX plays a significant role in prostate cancer induced angiogenesis by promoting VEGF production and that X-ray crystallography may prove beneficial in the development of specific inhibitors of P12-LOX.

Subject Headings

Biology, Molecular

Keywords

Lipoxygenase; VEGF; Angiogenesis; Prostate cancer

Advisor

Jerzy Jankun, Ph.D

Pages

209p.

Document number: mco1106061925
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=mco1106061925

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