Profiling Cytochrome P450 Expression in Ovarian Cancer: Identification of Prognostic Markers

Abstract

Purpose: The cytochromes P450 are a multigene family of enzymes with a central role in the oxidative metabolism of a wide range of xenobiotics, including anticancer drugs and biologically active endogenous compounds. The purpose of this study was to define the cytochrome P450 profile of ovarian cancer and identify novel therapeutic targets and establish the prognostic significance of expression of individual cytochrome P450s in this type of cancer. Experimental Design: Immunohistochemistry for a panel of 23 cytochrome P450s and cytochrome P450 reductase was done on an ovarian cancer tissue microarray consisting of 99 primary epithelial ovarian cancers, 22 peritoneal metastasis, and 13 normal ovarian samples. The intensity of immunoreactivity in each sample was established by light microscopy. Results: In primary ovarian cancer, several P450s (CYP1B1, CYP2A/2B, CYP2F1, CYP2R1, CYP2U1, CYP3A5, CYP3A7, CYP3A43, CYP4Z1, CYP26A1, and CYP51) were present at a significantly higher level of intensity compared with normal ovary. P450 expression was also detected in ovarian cancer metastasis and CYP2S1 and P450 reductase both showed significantly increased expression in metastasis compared with primary ovarian cancer. The presence of low/ negative CYP2A/2B (log rank = 7.06, P = 0.008) or positive CYP4Z1 (log rank = 6.19, P = 0.01) immunoreactivity in primary ovarian cancer were each associated with poor prognosis. Both CYP2A/2B and CYP4Z1were also independent markers of prognosis. Conclusions: The expression profile of individual P450s has been established in ovarian cancer. Several P450s show increased expression in ovarian cancer and this provides the basis for developing P450-based therapeutics in ovarian cancer. Expression of CYP2A/2B or CYP4Z1in primary ovarian cancer were independent markers of prognosis.Ovarian cancer is the most common gynecological malignancy worldwide; yet, the 5-year survival rate for this disease has remained low at f30% for the last 20 years and with relatively little recent improvement (1, 2). Poor prognosis is generally considered to be the result of late presentation when ovarian cancer is of advanced stage and the unpredictable and generally very limited response of this type of cancer to current cancer therapies (3, 4). Improved survival in ovarian cancer is, therefore, dependent on the development of new paradigms in treatment.The cytochrome P450 (P450) enzymes are a large family of constitutive and inducible mono-oxygenase enzymes that metabolize many lipophilic, biologically active endogenous and xenobiotic substrates, including a large number of therapeutic drugs and toxic environmental chemicals (5 -8). Currently, the human P450 superfamily is classified into 18 distinct families based on nucleic acid homology (5). Some P450s, especially the major xenobiotic metabolizing forms of P450, have been very well characterized, whereas very little is known about the biology of some of the more recently identified P450s. Individual P450s show characteristic cell type -and tissue-spe...

Nedd9/Hef1/Cas-L mediates the effects of environmental pollutants on cell migration and plasticity

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A novel role for the retinoic acid-catabolizing enzyme CYP26A1 in Barrett's associated adenocarcinoma

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