Both external and internal exposure to ionizing radiation are strong risk factors for the development of thyroid tumors. Until now, the diagnosis of radiation-induced thyroid tumors has been deduced from a network of arguments taken together with the individual history of radiation exposure. Neither the histological features nor the genetic alterations observed in these tumors have been shown to be specific fingerprints of an exposure to radiation. The aim of our work is to define ionizing radiation-related molecular specificities in a series of secondary thyroid tumors developed in the radiation field of patients treated by radiotherapy. To identify molecular markers that could represent a radiation-induction signature, we compared 25K microarray transcriptome profiles of a learning set of 28 thyroid tumors, which comprised 14 follicular thyroid adenomas (FTA) and 14 papillary thyroid carcinomas (PTC), either sporadic or consecutive to external radiotherapy in childhood. We identified a signature composed of 322 genes which discriminates radiation-induced tumors (FTA and PTC) from their sporadic counterparts. The robustness of this signature was further confirmed by blind case-by-case classification of an independent set of 29 tumors (16 FTA and 13 PTC). After the histology code break by the clinicians, 26/29 tumors were well classified regarding tumor etiology, 1 was undetermined, and 2 were misclassified. Our results help shed light on radiation-induced thyroid carcinogenesis, since specific molecular pathways are deregulated in radiation-induced tumors.
Catherine Ory, Nicolas Ugolin, Céline Levalois, Ludovic Lacroix, Bernard Caillou, Jean-Michel Bidart, Martin Schlumberger, Ibrahima Diallo, Florent de Vathaire, Paul Hofman, José Santini, Bernard Malfoy and Sylvie Chevillard
Nabahet Ameur, Ludovic Lacroix, Sophie Roucan, Véronique Roux, Sophie Broutin, Monique Talbot, Corinne Dupuy, Bernard Caillou, Martin Schlumberger and Jean-Michel Bidart
RET oncogene mutations are found in familial medullary thyroid carcinomas (MTC) and in one-third of sporadic cases. Oncogenic mechanisms involved in non-RET mutated sporadic MTC remain unclear. To study alterations associated with the development of both inherited and sporadic MTC, pangenomic DNA microarrays were used to analyze the transcriptome of 13 MTCs (four familial and nine sporadic). By using an ANOVA test, a list of 173 gene sequences with at least a twofold change expression was obtained. A subset of differentially expressed genes was controlled by real-time quantitative PCR and immunohistochemistry on a larger collection of MTCs. The expression pattern of those genes allowed us to distinguish two groups of sporadic tumors. The first group displays an expression profile similar to that expressed by inherited RET634 tumors. The second presents an expression profile close to that displayed by inherited RET918 tumors and includes tumors from patients with distant metastases. It is characterized by the overexpression of genes involved in proliferation and invasion (PTN, ESM1, and CEACAM6) or matrix remodeling (COL1A1, COL1A2, and FAP). Interestingly, RET918 tumors showed overexpression of the PTN gene, encoding pleiotrophin, a protein associated with metastasis. Using a MTC cell line, silencing of RET induced the inhibition of PTN gene expression. Overall, our results suggest that familial MTC and sporadic MTC could activate similar oncogenic pathways.
Pasqualino Malandrino, Abir Al Ghuzlan, Marine Castaing, Jacques Young, Bernard Caillou, Jean-Paul Travagli, Dominique Elias, Thierry de Baere, Clarisse Dromain, Angelo Paci, Philippe Chanson, Martin Schlumberger, Sophie Leboulleux and Eric Baudin
To progress in the stratification of the first-line therapeutic management of metastatic adrenocortical carcinoma (ACC), we searched for prognostic parameters of survival in patients treated with combined mitotane- and cisplatinum-based chemotherapy as first-line. We retrospectively studied prospectively collected parameters from 131 consecutive patients with metastatic ACC (44 with a tissue specimen available) treated at the Gustave Roussy Institute with mitotane- and platinum-based chemotherapy. Fifty-five patients with clinical, pathological, and morphological data available together with treatment characteristics including detailed follow-up were enrolled. Plasma mitotane levels and ERCC1 protein staining were analyzed. Response was analyzed according to RECIST criteria as well as overall survival (OS) from the start of cisplatinum-based chemotherapy. Parameters impacting on OS were evaluated by univariate analysis, and then analyzed by multivariate analysis. Using a landmark method, OS according to response to chemotherapy was analyzed. Objective response to combined mitotane- and cisplatinum-based chemotherapy was 27.3%. Median OS was 1 year. In the univariate analysis, resection of the primary, time since diagnosis, mitotane monotherapy as single first-line treatment, number of affected organs, plasma mitotane above 14 mg/l, and objective response were predictors of survival. In the multivariate analysis, mitotane level ≥14 mg/l and objective response to platinum-based chemotherapy were found to be independent predictors of survival (P=0.03 and <0.001). Our study suggests a prognostic role for mitotane therapy and objective response to platinum-based chemotherapy.
Urbain Weyemi, Bernard Caillou, Monique Talbot, Rabii Ameziane-El-Hassani, Ludovic Lacroix, Odile Lagent-Chevallier, Abir Al Ghuzlan, Dirk Roos, Jean-Michel Bidart, Alain Virion, Martin Schlumberger and Corinne Dupuy
NADPH oxidase 4 (NOX4) belongs to the NOX family that generates reactive oxygen species (ROS). Function and tissue distribution of NOX4 have not yet been entirely clarified. To date, in the thyroid gland, only DUOX1/2 NOX systems have been described. NOX4 mRNA expression, as shown by real-time PCR, was present in normal thyroid tissue, regulated by TSH and significantly increased in differentiated cancer tissues. TSH increased the protein level of NOX4 in human thyroid primary culture and NOX4-dependent ROS generation. NOX4 immunostaining was detected in normal and pathologic thyroid tissues. In normal thyroid tissue, staining was heterogeneous and mostly found in activated columnar thyrocytes but absent in quiescent flat cells. Papillary and follicular thyroid carcinomas displayed more homogeneous staining. The p22phox protein that forms a heterodimeric enzyme complex with NOX4 displayed an identical cellular expression pattern and was also positively regulated by TSH. ROS may have various biological effects, depending on the site of production. Intracellular NOX4–p22phox localization suggests a role in cytoplasmic redox signaling, in contrast to the DUOX localization at the apical membrane that corresponds to an extracellular H2O2 production. Increased NOX4–p22phox in cancer might be related to a higher proliferation rate and tumor progression but a role in the development of tumors has to be further studied and established in the future.