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Int J Clin Exp Pathol 2013;6(2):199-211

Original Article
Expression of XPG protein in human normal and tumor tissues

Miguel Aracil, Lisa M Dauffenbach, Marta Martínez Diez, Rana Richeh, Victoria Moneo, Juan Fernando
Martínez Leal, Luis Francisco García Fernández, Christopher A Kerfoot, Carlos M Galmarini

Cell Biology and Pharmacogenomics Department, PharmaMar SA, Colmenar Viejo, Spain; 2Mosaic Laboratories
LLC, Lake Forest, CA, U.S.A

Received September 27, 2012; Accepted November 23, 2012; Epub January 15, 2013; Published February 1,
2013

Abstract: XPG (Xeroderma pigmentosum group G complementing factor) is a protein associated with DNA repair
and transcription. Point mutations in ERCC5, the gene coding for XPG, cause the cancer-prone disorder xeroderma
pigmentosum (XP) while truncation mutations give rise to individuals with the combined clinical features of XP
and Cockayne syndrome. Polymorphisms of ERCC5 or alterations in XPG mRNA expression were also associated
to an increase risk of different cancers types and to prognosis of cancer patients. However, the expression of XPG
protein in different normal or tumor human tissues is not well known. In the present work, we have validated an
immunohistochemistry (IHC) assay for detection of expression levels of XPG protein in FFPE human tissue samples.
We have also tested this IHC assay in different normal and tumor human tissues. On a microarray containing 28
normal cores, positive staining was observed in 60% of the samples. The highest staining was detected in adrenal
gland, breast, colon, heart, kidney, thyroid and tongue. In tumors, positive staining was observed in 9 of 10 breast
cancer samples and in all 5 ovarian cancer and 5 sarcomas samples. Subcellular localization was predominantly
nuclear. The use of this validated methodology would help to interpret the role of XPG in tumorogenesis and its use
as a possible prognostic or predictive factor. (IJCP1209028).

Keywords: XPG, immunohistochemistry, tumor tissue

Address all correspondence to:
Dr. Miguel Aracil, Cell
Biology and Pharmacogenomics Department
PharmaMar SA, 28770 Colmenar Viejo, Madrid
Spain. Tel: +34 918466048; Fax: +34 918466001
E-mail: maracil@pharmamar.com