To analyze the genetic alterations of pheochromocytomas and evaluate the difference among malignant, extra-adrenal, and benign pheochromocytomas. Forty-three tumor samples were tested for genetic changes using multiplex ligation-dependent probe amplification. Among them, 39 samples were available for protein expression analysis by immunohistochemistry (IHC). All 43 patients (24 women and 19 men; mean age 44.6±13.6 years; range 18–75 years; 9 with malignant, 7 extra-adrenal, and 27 benign) showed multiple copy number losses or gains. The average copy number change was 13.10 in malignant, 13.93 in benign, and 13.47 in paraganglioma patients. There is no significant difference among the three groups of pheochromocytomas. However, we discovered that in the malignant pheochromocytomas, 6 of the 9 patients (67%) showed erythroblastic leukemia viral oncogene homolog 2 (ERBB-2) oncogene gain, whereas only 12 of the 34 (35%) identified change in the benign and extra-adrenal pheochromocytomas. Further, IHC confirmed that ERBB-2-positive staining was more frequent and stronger in malignant pheochromocytomas than in benign and extra-adrenal pheochromocytomas. Our study illustrates the chromosomal changes of the whole genome of Chinese pheochromocytoma patients. The results suggest that there may be certain progression of genetic events that involves chromosomes 1p, 3p, 6p, 11q, 12q, 17q, and 19q in the development of pheochromocytomas, and the activation of ERBB-2 located on chromosome 17q is an important and early event in the malignancy development of these tumor types. The overexpression of ERBB-2 identified by IHC suggested that this oncogene could be associated with the malignancy of pheochromocytomas and paragangliomas.
WenQi Yuan, WeiQinq Wang, Bin Cui, TingWei Su, Yan Ge, Lei Jiang, WeiWei Zhou and Guang Ning
Jie Cai, Lin Li, Lei Ye, Xiaohua Jiang, Liyun Shen, Zhibo Gao, Weiyuan Fang, Fengjiao Huang, Tingwei Su, Yulin Zhou, Weiqing Wang and Guang Ning
Activating rearranged during transfection (RET) mutations function as the initiating causative mutation for multiple endocrine neoplasia type 2A (MEN2A). However, no conclusive findings regarding the non-RET genetic events have been reported. This is the first study, to our knowledge, examining genomic alterations in matched MEN2A-associated tumors. We performed exome sequencing and SNP array analysis of matched MEN2A tumors and germline DNA. Somatic alterations were validated in an independent set of patients using Sanger sequencing. Genes of functional interest were further evaluated. The germline RET mutation was found in all MEN2A-component tumors. Thirty-two somatic mutations were identified in the nine MEN2A-associated tumors, of which 28 (87.5%) were point mutations and 4 (12.5%) were small insertions, duplications, or deletions. We sequenced all the mutations as well as coding sequence regions of the 12 genes in an independent sample set including 35 medullary thyroid cancers (20 MEN2A) and 34 PCCs (22 MEN2A), but found no recurrent mutations. Recurrent alterations were found in 13 genes with either mutations or alterations in copy number, including an EIF4G1 mutation (p. E1147V). Mutation of EIF4G1 led to increased cell proliferation and RET/MAPK phosphorylation, while knockdown of EIF4G1 led to reduced cell proliferation and RET/MAPK phosphorylation in TT, MZ-CRC1, and PC-12 cells. We found fewer somatic mutations in endocrine tumors compared with non-endocrine tumors. RET was the primary driver in MEN2A-associated tumors. However, low-frequency alterations such as EIF4G1 might participate in MEN2A-associated tumorigenesis, possibly by regulating the activity of the RET pathway.
Xiao-Hua Jiang, Jie-Li Lu, Bin Cui, Yong-Ju Zhao, Wei-qing Wang, Jian-Min Liu, Wen-Qiang Fang, Ya-Nan Cao, Yan Ge, Chang-xian Zhang, Huguette Casse, Xiao-Ying Li and Guang Ning
Multiple endocrine neoplasia type 1 (MEN1) is an inherited tumour syndrome characterized by the development of tumours of the parathyroid, anterior pituitary and pancreatic islets, etc. Heterozygous germ line mutations of MEN1 gene are responsible for the onset of MEN1. We investigated the probands and 31 family members from eight unrelated Chinese families associated with MEN1 and identified four novel mutations, namely 373_374ins18, 822delT, 259delT and 1092delC, as well as three previously reported mutations, such as 357_360delCTGT, 427_428delTA and R108X (CGA>TGA) of MEN1 gene. Furthermore, we detected a loss of heterozygosity (LOH) at chromosome 11q in the removed tumours, including gastrinoma, insulinoma and parathyroid adenoma from two probands of MEN1 families. RT-PCR and direct sequencing showed that mutant MEN1 transcripts remained in the MEN1-associated endocrine tumours, whereas normal menin proteins could not be detected in those tumours by either immunohistochemistry or immunoblotting. In conclusion, MEN1 heterozygous mutations are associated with LOH and menin absence, which are present in MEN1-associated endocrine tumours.
Yu-fang Bi, Rui-xin Liu, Lei Ye, Hai Fang, Xiao-ying Li, Wei-qing Wang, Ji Zhang, Kan-Kan Wang, Lei Jiang, Ting-wei Su, Zhong-yuan Chen and Guang Ning
Although there has been increased knowledge about the molecular biology of neuroendocrine tumors (NETs), little is known about thymic carcinoids and even less about those with excessive hormone disorders, such as ectopic ACTH syndrome. This study was designed to gain insights into the molecular networks underlying the tumorigenesis of thymic carcinoids with ACTH secretion. By an approach integrating cDNA microarray and methods of computational biology, we compare gene expression profile between ACTH-producing thymic carcinoids and the normal thymus. In total, there are 63 biological categories increased and 108 decreased in thymic carcinoids. Cell proliferation was stimulated, which may explain the relatively uncontrolled cell growth of the tumor. Dysregulation of the Notch-signaling pathway was likely to be underlying the neuroendocrine features of this type of tumors. Moreover, inhibition of immunity and increased neuropeptide signaling molecules (POMC and its sorting molecule CPE) made the clinical manifestation reasonable and thus validated the array data. In conclusion, thymic carcinoids have a distinct gene expression pattern from the normal thymus, and they are characterized by deregulations of a series of biofunctions, which may be involved in the development of NETs. Hence, this study has provided not only a detailed comprehension of the molecular pathogenesis of thymic carcinoids with ectopic ACTH syndrome, but also a road map to approach thymic NETs at the system level.