Transcriptional profiling reveals coordinated up-regulation of oxidative metabolism genes in thyroid oncocytic tumors.
Oncocytomas are large cell tumors characterized by an abnormal proliferation of mitochondria. To investigate this phenomenon in thyroid oncocytomas, we determined gene expression profiles of 87 samples using microarrays of 6720 PCR products from cDNA clones. Samples included 29 thyroid oncocytomas and six papillary carcinomas, the remainder representing other thyroid pathologies or mitochondria-rich tumor samples, normal thyroid samples, and two thyroid cell lines. Hierarchical clustering and supervised analysis identified two specific oncocytic clusters and 163 distinctly regulated genes between oncocytoma and normal thyroid. Differential expression of five selected genes (APOD, BCL-2, COX, CTSB, and MAP2) was confirmed by immunohistochemistry. The two specific oncocytic clusters were rich in mitochondrial genes and revealed coordinated expression of nuclear and mitochondrial respiratory chain genes. We also observed the up-regulation of genes involved in mitochondrial biogenesis, such as nuclear respiratory factor 1 and the endothelial nitric oxide synthase. Several oxidative metabolism genes were overexpressed in oncocytomas, including those from the tricarboxylic acid cycle (MDH1) and cytosolic glycolysis (GAPD, ENO1, and GPI). On the contrary, the lactate dehydrogenase A gene, involved in anaerobic metabolism, was down-regulated. Our results suggest that, unlike a large number of solid tumors, thyroid oncocytomas produce energy through an aerobic pathway.
Baris
Olivier
O
Institut National de la Santé et de la Recherche Médicale, Equipe Mixte INSERM-Universitaire 0018, Laboratoire de Biochimie et Biologie Moléculaire, Centre Hospitalier Universitaire, Angers F-49033, France. olivier.baris@med.univ-angers.fr
Savagner
Frédérique
F
Nasser
Valéry
V
Loriod
Béatrice
B
Granjeaud
Samuel
S
Guyetant
Serge
S
Franc
Brigitte
B
Rodien
Patrice
P
Rohmer
Vincent
V
Bertucci
François
F
Birnbaum
Daniel
D
Malthièry
Yves
Y
Reynier
Pascal
P
Houlgatte
Rémi
R
D018249:Adenoma, Oxyphilic / Q000235:genetics* / Q000378:metabolism*; D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics*