Distinct Transcriptional Profiles of Adrenocortical Tumors Uncovered by DNA Microarray Analysis

Abstract

Comprehensive expression profiling of tumors using DNA microarrays has been used recently for molecular classification and biomarker discovery, as well as a tool to identify and investigate genes involved in tumorigenesis. Application of this approach to a cohort of benign and malignant adrenocortical tissues would be potentially informative in all of these aspects. In this study, we generated transcriptional profiles of 11 adrenocortical carcinomas (ACCs), 4 adrenocortical adenomas (ACAs), 3 normal adrenal cortices (NCs), and 1 macronodular hyperplasia (MNH) using Affymetrix HG_U95Av2 oligonucleotide arrays representing approximately 10,500 unique genes. The expression data set was used for unsupervised hierarchical cluster analysis as well as principal component analysis to visually represent the expression data. An analysis of variance on the three classes (NC, ACA plus MNH, and ACC) revealed 91 genes that displayed at least threefold differential expression between the ACC cohort and both the NC and ACA cohorts at a significance level of P < 0.01. Included in these 91 genes were those known to be up-regulated in adrenocortical tumors, such as insulin-like growth factor (IGF2), as well as novel differentially expressed genes such as osteopontin (SPP) and serine threonine kinase 15 (STK15). Increased expression of IGF2 was identified in 10 of 11 ACCs (90.9%) and was verified by quantitative reverse transcriptase-polymerase chain reaction. Select proliferation-related genes (TOP2A and Ki-67) were validated at the protein level using immunohistochemistry and adrenocortical tissue microarrays. Our results demonstrated significant and consistent gene expression changes in ACCs compared to benign adrenocortical lesions. Moreover, we identified several genes that represent potential diagnostic markers and may play a role in the pathogenesis of ACC.

Meta-analysis of adrenocortical tumour genomics data: novel pathogenic pathways revealed

“…We found decreased ALDH1A1 and ALDH1A3 mRNA expression in ACC relative to ACA in several microarray studies (Giordano et al, 2003(Giordano et al, , 2009Vela´zquez-Ferna´ndez et al, 2005;Laurell et al, 2009;Soon et al, 2009;de Reynie`s et al, 2009). Decreased ALDH1A1 has been validated by QRT-PCR in two studies (Fernandez-Ranvier et al, 2008b;Laurell et al, 2009).…”

“…Overexpression of several genes involved in the regulation of G2/M phase transition was noted in ACCs and correlated with chromosome gains: CCNB1 and cell division protein kinase 7 (CDK7) on chr5q13, ubiquitin C (UBC) on chr12q24, and Mdm2 p53-binding protein homologue (MDM2) on chr12q15 (Giordano et al, 2003(Giordano et al, , 2009To¨mbo¨l et al, 2009;de Reynie`s et al, 2009). Overexpression of CCNB1 in ACCs was validated in the recent study by Soon et al (2009) as well.…”

“…Several other members of G2/M transition were significantly overexpressed in ACCs without corresponding chromosomal alterations in at least three microarray studies, including CCNB2, CDC2, CDC25B and topoisomerase II alpha (TOP2A) (Giordano et al, 2003(Giordano et al, , 2009To¨mbo¨l et al, 2009;Soon et al, 2009;de Reynie`s et al, 2009). Overexpression of TOP2A has already been reported and considered as a diagnostic marker for ACCs (Giordano et al, 2003).…”

“…Overexpression G1 cyclins (cyclin E), and G1 cell division protein kinases (CDK2, CDK4) was reported in sporadic ACCs (Bourcigaux et al, 2000). Overexpression of CCNE1 and CCNE2 was found in four of the investigated microarray studies (Giordano et al, 2003(Giordano et al, , 2009To¨mbo¨l et al, 2009;de Reynie`s et al, 2009). GSEA of microarray studies revealed significant enrichment of overexpressed genes on chr19q12, where CCNE1 is mapped (Giordano et al, 2009;To¨mbo¨l et al, 2009;de Reynie`s et al, 2009).…”

“…Overexpression of TOP2A has already been reported and considered as a diagnostic marker for ACCs (Giordano et al, 2003). TOP2A is a major target for a variety of antineoplastic agents, including etoposide and doxorubicin used in ACC chemotherapy (Patalano et al, 2009).…”