Changes in expression of arachidonic acid (AA) metabolizing enzymes are implicated in the development and progression of human prostate carcinoma (Pca). Transgenic mouse models of Pca that progress from high-grade prostatic intraepithelial neoplasia (HGPIN) to invasive and metastatic carcinoma could facilitate study of the regulation and function of these genes in Pca progression. Herein we characterize the AA-metabolizing enzymes in transgenic mice established with a prostate epithelial-specific long probasin promoter and the SV40 large T antigen (LPB-Tag mice) that develop extensive HGPIN and invasive and metastatic carcinoma with neuroendocrine (NE) differentiation. Murine 8-lipoxygenase (8-LOX), homologue of the 15-LOX-2 enzyme that is expressed in benign human prostatic epithelium and reduced in Pca, was not detected in wild-type or LPB-Tag prostates as determined by enzyme assay, reverse transcription-PCR, and immunohistochemistry. The most prominent AA metabolite in mouse prostate was 12-HETE. Wild-type prostate (dorsolateral lobe) converted 1.6 +/- 0.5% [(14)C]AA to 12-HETE (n = 7), and this increased to 8.0 +/- 4.4% conversion in LPB-Tag mice with HGPIN (n = 13). Quantitative real-time reverse transcription-PCR and immunostaining correlated the increased 12-HETE synthesis with increased neoplastic epithelial expression of 12/15-LOX, the leukocyte-type (L) of 12-LOX and the murine homologue of human 15-LOX-1. Immunostaining showed increased L12-LOX in invasive carcinoma and approximately one-half of metastatic foci. COX-2 mRNA was detectable in neoplastic prostates with HGPIN but not in wild-type prostate. By immunostaining, COX-2 was increased in the neoplastic epithelium of HGPIN but was absent in foci of invasion and metastases. We conclude that (a) AA metabolism in wild-type mouse prostate differs from humans in the basal expression of LOXs (15-LOX-2 in human, absence of its 8-LOX homologue in mouse prostate); (b) increased expression of 12/15-LOX in HGPIN and invasive carcinoma of the LPB-Tag model is similar to the increased 15-LOX-1 in high-grade human Pca; and (c) the LPB-Tag model shows increased COX-2 in HGPIN, and therefore, it may allow additional definition of the role of this enzyme in the subset of human HGPINs or other precursor lesions that are COX-2 positive, as well as investigation of its contribution to neoplastic cell proliferation and tumor angiogenesis in Pca.