INVOLVEMENT OF ARACHIDONIC ACID METABOLITES IN PHEOCHROMOCYTOMA BIOLOGY

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 303-321-Cancer in Endocrine Tissues
Bench to Bedside
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-315
Cecilia Edith Colombero*, María Celia Fernandez, Gabriela Sansó, Ana Vieites, Marta Beatriz Barontini, Patricia Pennisi and Susana Nowicki
Centro de Investigaciones Endocrinológicas (CEDIE-CONICET), Buenos Aires, Argentina
Arachidonic acid can be metabolized into 20-hydroxy and epoxide compounds by Cytochrome P450 complex (CYP), CYP4A11 and 4F2 (20-hydroxylases) and CYP 2J2 (epoxygenase). These metabolites have proliferative promoting actions in some normal and cancer cells, among other biological effects. Previous studies have shown an increase in the expression of these isoforms in several types of tumors. Also, a diminished tumoral progression has been observed after their inhibition. Pheochromocytoma and paragangliomas are rare neuroendocrine, catecholamine secreting tumors, associated with a genetic syndrome in about 25% of patients. No data on the role of these CYP- generated metabolites in this kind of tumor is available so far.

The aim of this study was to assess the effect of 20-hydroxylated (20-HETE) and epoxygenated (11,12-EET and 14,15-EET) metabolites in the proliferation rate of Mouse Pheochromocytoma Cells 3 (MPC3) and to analyze the expression 20-hydroxylases and epoxygenases in murine and human pheochromocytoma.

CYP expression was analyzed by Western Blot and/or PCR in MPC3 cell culture, murine tumors generated by s.c. injection of MPC3 cells, and frozen human tumor samples of sporadic (n=6) or familial [von Hippel Lindau disease (VHL) (n=5), Multiple Endocrine Neoplasia (MEN 2A) (n=3) or Paraganglioma type 4 (PGL4) (n=2)] pheochromocytomas and paragangliomas.

MPC3 cells were incubated with 20-HETE (20uM) or 11,12-EET or 14,15-EET (10nM for both) in low serum medium. 48h incubation resulted in an increase in cell number (increase over control: 20-HETE 64%, n.s.; 11,12-EET 99%, p<0.05; 14,15-EET 141%, p<0.01).  

CYP4A12 (murine 20-hydroxylase), CYP2C29, 2C38 y 2C44 (murine epoxygenases) were detected in murine tumors; yet none of them was found in MPC3 cell culture.

In human samples, isoform expression was related to the genetic background of the tumor: CYP2J2 was low in all samples except in MEN2A. CYP4A11 and 4F2 were present in all samples, being the CYP/tubulin ratio significantly different in PGL4 vs. sporadic for CYP4A11 (0.94±0.06 vs. 0.25±0.14; p<0.05) and in MEN2A vs. VHL for CYP4F2 (1.99±0.28 vs. 1.19±0.18; p<0.05).

Our results demonstrate that these CYP- derived arachidonic acid metabolites have an impact on proliferation in MPC3 cell culture. In addition these CYPs are expressed both in human and murine tumors. Altogether, these results point to a contribution of these metabolites to pheochromocytoma biology.

Nothing to Disclose: CEC, MCF, GS, AV, MBB, PP, SN

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: PIP 112-2008 1-01905, CONICET