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S K Kang, K-C Choi, H-S Yang, and P C K Leung

Gonadotrophin-releasing hormone (GnRH) functions as a key neuroendocrine regulator of the hypothalamic-pituitary-gonadal axis. In addition to the hypothalamus and pituitary gland, GnRH and its receptor have been detected in other reproductive tissues including the gonads, placenta and tumours arising from these tissues. Recently, a second form of GnRH (GnRH-II) and type II GnRH receptor have been found in normal ovarian surface epithelium and neoplastic counterparts. The two types of GnRH may play an important role as an autocrine/paracrine regulator of reproductive functions and ovarian tumour growth. In this review, the distribution and potential roles of GnRH-I/-II and their GnRH receptors in the ovarian cells and ovarian cancer will be discussed.

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Y-S Yang, H-D Song, Y-D Peng, Q-H Huang, R-Y Li, Z-D Zhu, R-M Hu, Z-G Han, and J-L Chen

Pheochromocytoma is a chromaffin cell neoplasm that typically causes symptoms and signs of episodic catecholamine release. Pheochromocytoma can be divided into two types: familial and sporadic. The molecular mechanisms involved in familial pheochromocytoma have been unraveled, but the detailed molecular mechanism of sporadic pheochromocytoma remains unknown. The present study thus aimed at characterization of gene expression profiling of sporadic pheochromocytoma using expressed sequence tags (ESTs), and established a preliminary catalog of genes expressed in the tumor. In total, 4115 ESTs were generated from the tumor library. The gene expression profilings of the pheochromocytoma and the normal adrenal gland were compared, and 341 genes were identified to be significantly expressed differently between the two libraries. Interestingly, 16 known genes participating in cell division or apoptosis were notably differently expressed between the tumor and the normal adrenal gland. Twenty-four novel full-length cDNAs were cloned from the tumor library and five of them were significantly up-regulated in the tumor. Some of them may be involved in the tumorigenesis of pheochromocytoma. The sequence data of ESTs and novel full-length cDNAs described in this paper have been submitted to the GeneBank library.

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H-C Jennifer Shen, Jennifer E Rosen, Lauren M Yang, Sharon A Savage, A Lee Burns, Carmen M Mateo, Sunita K Agarwal, Settara C Chandrasekharappa, Allen M Spiegel, Francis S Collins, Stephen J Marx, and Steven K Libutti

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome caused by mutations in the MEN1 tumor suppressor gene. Loss of the functional second copy of the MEN1 gene causes individuals to develop multiple endocrine tumors, primarily affecting the parathyroid, pituitary, and pancreas. While it is clear that the protein encoded by MEN1, menin, suppresses endocrine tumors, its biochemical functions and direct downstream targets remain unclear. Recent studies have suggested that menin may act as a scaffold protein to coordinate gene transcription, and that menin is an oncogenic cofactor for homeobox (HOX) gene expression in hematopoietic cancer. The role of HOX genes in adult cell differentiation is still obscure, but growing evidence suggests that they may play important roles in the development of cancer. Therefore, we hypothesized that specific HOX genes were regulated by menin in parathyroid tumor development. Utilizing quantitative TaqMan RT-PCR, we compared expression profiles of the 39 HOX genes in human familial MEN1 (fMEN1) parathyroid tumors and sporadic parathyroid adenomas with normal samples. We identified a large set of 23 HOX genes whose deregulation is specific for fMEN1 parathyroid tumors, and only 5 HOX genes whose misexpression are specific for sporadic parathyroid tumor development. These findings provide the first evidence that loss of the MEN1 tumor suppressor gene is associated with deregulation of specific HOX gene expression in the development of familial human parathyroid tumors. Our results strongly reinforce the idea that abnormal expression of developmental HOX genes can be critical in human cancer progression.