Expression of p53-induced apoptosis effector PERP in primary uveal melanomas: Downregulation is associated with aggressive type Luminita Paraoan a, * , Donna Gray a , Paul Hiscott a,b , Bahram Ebrahimi c , Bertil Damato a,d , Ian Grierson a a Unit of Ophthalmology, School of Clinical Sciences, University of Liverpool, UCD Building, Daulby Street, Liverpool L69 3GA, UK b Division of Pathology, School of Clinical Laboratory Sciences, University of Liverpool, UCD Building, Daulby Street, Liverpool L69 3GA, UK c Division of Medical Microbiology, School of Infection and Host Defence, University of Liverpool, UCD Building, Daulby Street, Liverpool L69 3GA, UK d Ocular Oncology Centre, St. Paul’s Eye Unit, Royal Liverpool University Hospital, Liverpool, UK Received 20 January 2006; accepted in revised form 27 April 2006 Available online 19 June 2006 Abstract Expression of PERP ( p53 apoptosis effector related to PMP-22) was investigated in primary uveal melanomas and its variation was analyzed in relation to clinico-pathological and cytogenetical characteristics of these tumors. The transcriptional level of PERP gene was measured by quan- titative real-time RT-PCR in 26 uveal melanomas with known chromosomes 3 and 8 status. PERP protein levels were assessed by Western blot analysis of 22 fresh-frozen tumors and by immunohistochemical analysis of 16 paraffin-embedded tumor specimens. Differential expression of PERP was identified in primary choroidal melanoma specimens, both at transcriptional and protein level. Reduced PERP mRNA level was sig- nificantly associated with monosomy 3 (two-way ANOVA and t-test, p ¼ 0.004) but not with gains in chromosome 8. Transcriptional downre- gulation of PERP did not present a statistically significant association with ciliary body involvement, size, PAS-positive loops or cell type. Immunoblotting and immunohistochemistry further demonstrated significantly reduced PERP protein level in monosomy 3 melanomas, as com- pared with disomy 3 tumors. The altered expression of PERP highlighted this apoptosis-specific target of p53 as a possible contributor to apoptosis in uveal melanoma with PERP downregulation being particularly relevant to the aggressive (monosomy 3) type of uveal melanoma. As PERP is a novel type of p53 effector that is likely to stimulate apoptosis through a mechanism distinct from that of Bcl-2-related mitochondrial effectors, further elucidation of its role in uveal melanoma pathogenesis will assist in the design of novel therapeutic approaches aimed at increasing the rate of apoptosis in this tumor. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: apoptosis; effector; p53; uveal melanoma; monosomy 3 1. Introduction Molecular mechanisms underlying aggressiveness of uveal melanoma in some patients and relative quiescence in others are poorly understood. Uveal melanomas tend to metastasize via the blood stream to the liver and other parts of the body (Albert, 1997; Damato, 2000). Features associated with an increased probability of metastatic disease include large basal tumor diameter, ciliary body involvement, epithelioid cell type, closed PAS-positive loops, partial or complete loss of chromosome 3 (i.e. monosomy 3) and partial gains in chromo- some 8 (Damato et al., 1996; Sisley et al., 1997; White et al., 1998; Damato, 2000; Aalto et al., 2001; Folberg et al., 2001; Scholes et al., 2003). Metastatic disease is usually fatal within a year of detection and only rarely does it respond to chemo- therapy. Consequently, despite advances in both diagnosis and treatment of the primary tumor, the uveal melanoma-related mortality has not changed significantly over the last few * Corresponding author. Tel.: þ44 151 706 4101; fax: þ44 151 706 5934. E-mail address: luminita.paraoan@liverpool.ac.uk (L. Paraoan). 0014-4835/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.exer.2006.04.016 Experimental Eye Research 83 (2006) 911e919 www.elsevier.com/locate/yexer