Sporadic and familial pheochromocytomas are associated with loss of at least two discrete intervals on chromosome 1p

Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial forms of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma, In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of similar to 70 cM (Ipter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%)sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients, Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PCI (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome Ip may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is Likely to have a broader role in the development of endocrine malignancies.

Loss of heterozygosity of the APC gene in oral squamous cell carcinoma

The aim of this study was to investigate loss of heterozygosity (LOH) of the APC tumor suppressor gene loci, using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) in 40 cases of oral squamous cell carcinoma (OSCC). Observed informativity was 72.5% for APC exon 11 and 82.5% for APC exon 15. LOH at APC exon 11 was observed in 2 (6.9%) of 29 informative cases, and no LOH was observed for APC exon 15. Our results suggest that inactivation of the APC gene plays a minor role in the carcinogenesis of OSCC. (C) 2008 Elsevier GmbH. All rights reserved.

Germline mutations in TMEM127 confer susceptibility to pheochromocytoma

Pheochromocytomas, which are catecholamine-secreting tumors of neural crest origin, are frequently hereditary(1). However, the molecular basis of the majority of these tumors is unknown(2). We identified the transmembrane-encoding gene TMEM127 on chromosome 2q11 as a new pheochromocytoma susceptibility gene. In a cohort of 103 samples, we detected truncating germline TMEM127 mutations in approximately 30% of familial tumors and about 3% of sporadic-appearing pheochromocytomas without a known genetic cause. The wild-type allele was consistently deleted in tumor DNA, suggesting a classic mechanism of tumor suppressor gene inactivation. Pheochromocytomas with mutations in TMEM127 are transcriptionally related to tumors bearing NF1 mutations and, similarly, show hyperphosphorylation of mammalian target of rapamycin (mTOR) effector proteins. Accordingly, in vitro gain-of-function and loss-of-function analyses indicate that TMEM127 is a negative regulator of mTOR. TMEM127 dynamically associates with the endomembrane system and colocalizes with perinuclear (activated) mTOR, suggesting a subcompartmental-specific effect. Our studies identify TMEM127 as a tumor suppressor gene and validate the power of hereditary tumors to elucidate cancer pathogenesis.

3q27 Aberrations in a Childhood Ovary Teratoma With Associated Malignant Germ Cell Component

Cytogenetic Studies of childhood ovary tumors have been poorly described. in the present article, the cytogenetic findings of an ovarian teratoma with malignant germ cell (yolk-sac) component occurring in an 8-year-old female are detailed. GTG-banding showed a karyotype of 46,XX, t(3;20)(q27;q13.3) [4]/46,XX, del3q27 [3]/46,XX [30]. Previous Studies have demonstrated common sites of loss of heterozygosity at 3q27-q28 region in different types of cancer, suggesting the presence of tumor Suppressor genes within this region. Pediatr Blood Cancer 2009;52:398-401. (C) 2008 Wiley-Liss, Inc.

Genomic deletions at 1p and 14q are associated with an abnormal cDNA microarray gene expression pattern in meningiomas but not in schwannomas

The molecular pathology of meningiomas and shwannomas involve the inactivation of the NF2 gene to generate grade I tumors. Genomic losses at 1p and 14q are observed in both neoplasms, although more frequently in meningiomas. The inactivation of unidentified genes located in these regions appears associated with tumor progression in meningiomas, but no clues to its molecular/clinical meaning are available in schwannomas. Recent microarray gene expression studies have demonstrated the existence of molecular subgroups in both entities. In the present study, we correlated the presence of genomic deletions at 1p, 14q, and 22q with the expression patterns of 96 tumor-related genes obtained by cDNA low-density microarrays in a series of 65 tumors including 42 meningiomas and 23 schwannomas. Two expression pattern groups were identified by cDNA mycroarray analysis when compared to the expression pattern in normal control RNA in both meningiomas and schwannomas, each one with patterns similar and different from the normal control. Meningioma and schwannoma subgroups differed in the expression of 38 and 16 genes, respectively. Using MLPA and microsatellites, we identified genomic losses at 1p, 14q, and 22q at nonrandom frequencies (12.5-69%) in meningiomas and schwannomas. Losses at 22q were almost equally frequent in both molecular expression subgroups in both neoplasms. However, deletions at 1p and 14q accumulated in meningiomas with a gene expression pattern different from the normal pattern, whereas the inverse situation occurred in schwannomas. Those anomalies characterized the schwannomas with expression pattern similar to the normal control. These findings suggest that deletions at 1p and 14q enhance the development of an abnormal tumor-related gene expression pattern in meningiomas, but this fact is not corroborated in schwannomas. (C) 2010 Elsevier Inc. All rights reserved.

Clinical and molecular characterization of Brazilian families with von Hippel-Lindau disease: a need for delineating genotype-phenotype correlation

von Hippel-Lindau (VHL) disease is an autosomal dominant hereditary cancer syndrome that predisposes to the development of a variety of benign and malignant tumours, especially cerebellar haemangioblastomas, retinal angiomas and clear-cell renal cell carcinomas (RCC). The etiology and manifestations are due to germline and somatic mutations in the VHL tumour suppressor gene. VHL disease is classified into type 1 and type 2, showing a clear genotype-phenotype correlation, as type 2 is associated with phaeochromocytoma and essentially caused by missense mutations. The aim of this study is to characterize the phenotype and genotype of families with VHL disease. Eighteen of twenty patients from ten unrelated families underwent genetic testing, nine of them fulfilled VHL disease criteria and one had an apparently sporadic cerebellar haemangioblastoma. Four different germline mutations in the VHL gene were identified: c.226_228delTTC (p.Phe76del); c.217C > T (p.Gln73X); IVS1-1 G > A and IVS2-1 G > C. The first three mutations were associated with type 1 disease and the last one with type 2B, which had never been identified in the germline. The transcriptional processing of a novel splice-site mutation was characterised. Three type 1 VHL families showed large deletions of the VHL gene, two of them encompassed the FANCD2/C3orf10 genes and were not associated with renal lesions. We also suggest that such families should be subclassified according to the risk of RCC and the extent of the VHL gene deletions. This study highlights the need for a through clinical and molecular characterisation of families with VHL disease to better delineate its genotype-phenotype correlation.

New recurrent deletions in the PPAR gamma and TP53 genes are associated with childhood myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a rare hematological malignancy in children. It was performed FISH analysis in 19 pediatric MDS patients to investigate deletions involving the PPAR gamma and TP53 genes. Significant losses in the PPAR gamma gene and deletions in the tumor suppressor gene TP53 were observed in 17 and 18 cases, respectively. Using quantitative RT-PCR, it was detected PPAR gamma transcript downexpression in a subset of these cases. G-banding analysis revealed 17p deletions in a small number of these cases. One MDS therapy-related patient had neither a loss of PPAR gamma nor TP53. These data suggest that the PPAR gamma and TP53 genes may be candidates for molecular markers in pediatric MDS, and that these potentially recurrent deletions could contribute to the identification of therapeutic approaches in primary pediatric MDS. (C) 2008 Elsevier Ltd. All fights reserved.

A study of adrenocortical tumors in children and adolescents by a comparative genomic hybridization technique

Adrenocortical tumors (ACT) are rare neoplasms of the adrenal glands accounting for 0.2% of all pediatric cancers. However, the incidence of ACT in South Brazilian children is 10 to 15 times greater than the worldwide incidence. Comparative genomic hybridization studies have revealed the presence of a high degree of chromosomal instability in ACT. We evaluated 16 ACT, 8 of them carcinomas and 8 adenomas. The presence of changes in DNA copy numbers was determined by comparative genomic hybridization, and the findings were validated by real-time polymerase chain reaction on the basis of IGF-II gene expression. The adenomas showed a mean of 19.7 imbalances per case, with the most frequent gain and loss being 4p15.1-p15.3 and 20p11.2-p13.2, respectively. The carcinomas presented with a mean of 35.5 imbalances per case, with the more frequent gain being 2q14.1-q24.3 and the more frequent losses being 3q21-q26.2, 20q12-qter, and 22q11.2-q13.3. The most frequent imbalances in both adenomas and carcinomas were gains of 1p21-p31.2, 2p12-p21 and loss of 20p11.2-p12. The expression of IGF-II mRNA (11p15.5) was higher in samples that presented with a gain of this region. It has been established that great genomic instability exists in pediatric ACT.

Human salivary gland morphogenesis: myoepithelial cell maturation assessed by immunohistochemical markers

Aims: Myoepithelial cells are important components of salivary gland structure, aiding the expulsion of saliva from acinar lobules. The aim was to evaluate the expression of smooth muscle actin (SMA), calponin, caldesmon, CD10, CD29, S100 protein, glial fibrillary acidic protein (GFAP) and p63 in myoepithelial cells during salivary gland morphogenesis to understand the maturation process of these cells and their possible use in the diagnosis of salivary gland lesions. Methods and results: Major and minor human salivary glands at various stages of development, derived from fetuses at 8-26 weeks of gestation, were studied immunohistochemically. Fully developed salivary glands were used as controls. The protein p63 was present in all stages of salivary gland morphogenesis from initial bud to terminal bud stage. CD29, S100 and calponin were detected increasingly as salivary gland structure matured and in fully developed salivary gland. Proteins GFAP, CD10 and caldesmon were not observed in myoepithelial cells of salivary glands. Conclusions: The proteins SMA, calponin, CD29, S100 and p63, which are present from the earliest stages of salivary gland maturation, are valuable myoepithelial markers but, although very specific, are not exclusive markers for this cell type.

Peroxiredoxin I is differentially expressed in multiple myelomas and in plasmablastic lymphomas

BACKGROUND: Plasmablastic lymphoma (PBL) and multiple myeloma (MM) are B cell-derived malignancies that share many morphologic and immunophenotypic traits, making the differential diagnosis particularly complicated. We have recently demonstrated that peroxiredoxin I (PrdxI) is expressed in plasma cells but not in B lymphocytes, suggesting that its expression is development-associated. AIM: To analyze PrdxI expression in PBL and in MM in order to study its utilization as an additional diagnostic molecular tool. METHODS AND RESULTS: Eight cases of PBL and nine of MM were studied by immunohistochemistry. We have demonstrated that PrdxI expression is closely connected with the immunoglobulin production capacity of the cells, which means high in MM, but absent in PBL cases, except one, wherein few cells were stained. CONCLUSIONS: We hypothesize PrdxI as a component of the unfolded protein response (UPR), an adaptive pathway essential for plasma cell differentiation. As we have not detected immunoglobulin in our PBL cases, we suggest that UPR was not activated in the cells, accounting for the impediment of the developmental process, and for the inhibition of PrdxI expression observed. PrdxI could be considered an additional plasma cell functional marker and could also be speculated as a therapeutic target in the treatment of MM. Oral Diseases (2008) 14, 741-746

gamma-Radiation induces apoptosis via sarcoplasmatic reticulum in guinea pig ileum smooth muscle cells

We investigated the effects of gamma-radiation on cells isolated from the longitudinal smooth muscle layer of the guinea pig ileum, a relatively radioresistant tissue. Single doses (up to 50 Gy) reduced the amount of sarcoplasmatic reticulum and condensed the myofibrils, as shown by electron microscopy 3 days post-irradiation. After that, contractility of smooth muscle strips was reduced. Ca(2+) handling was altered after irradiation, as shown in fura-2 loaded cells, with elevated basal intracellular Ca(2+), reduced amount of intrareticular Ca(2+), and reduced capacitive Ca(2+) entry. Radiation also induced apoptosis, judged from flow cytometry of cells loaded with proprium iodide. Electron microscopy showed that radiation caused condensation of chromatin in dense masses around the nuclear envelope, the presence of apoptotic bodies, fragmentation of the nucleus, detachment of cells from their neighbors, and reductions in cell volume. Radiation also caused activation of caspase 12. Apoptosis was reduced by the administration of the caspase inhibitor Z-Val-Ala-Asp-fluoromethyl-ketone methyl ester (Z-VAD-FIVIK) during the 3 day period after irradiation, and by the chelator of intracellular Ca(2+), 1,2-bis(o-aminophenoxy)ethane-N,N,N`,N`-tetraacetic acid (BAPTA), from 1 h before until 2 h after irradiation. BAPTA also reduced the effects of radiation on contractility, basal intracellular Ca(2+), amount of intrareticular Ca(2+), capacitative Ca(2+) entry, and apoptosis. In conclusion, the effects of gamma radiation on contractility, Ca(2+) handling, and apoptosis appear due to a toxic action of intracellular Ca(2+). Ca(2+)-induced damage to the sarcoplasmatic reticulum seems a key event in impaired Ca(2+) handling and apoptosis induced by gamma-radiation. (c) 2008 Elsevier B.V. All rights reserved.

MC1R genotype modifies risk of melanoma in families segregating CDKN2A mutations

Mutations in the exons of the cyclin-dependent kinase inhibitor gene CDKN2A are melanoma-predisposition alleles which have high penetrance, although they have low population frequencies. In contrast, variants of the melanocortin-1 receptor gene, MC1R, confer much lower melanoma risk but are common in European populations. Fifteen Australian CDKN2A mutation-carrying melanoma pedigrees were assessed for MC1R genotype, to test for possible modifier effects on melanoma risk. A CDKN2A mutation in the presence of a homozygous consensus MC1R genotype had a raw penetrance of 50%, with a mean age at onset of 58.1 years. When an MC1R variant allele was also present, the raw penetrance of the CDKN2A mutation increased to 84%, with a mean age at onset of 37.8 years (P=0.1). The presence of a CDKN2A mutation gave a hazard ratio of 13.35, and the hazard ratio of 3.72 for MC1R variant alleles was also significant. The impact of MC1R variants on risk of melanoma was mediated largely through the action of three common alleles, Arg151Cys, Arg160Trp, and Asp294His, that have previously been associated with red hair, fair skin, and skin sensitivity to ultraviolet light.

Ataxia telangiectasia mutated (ATM) kinase and ATM and Rad3 related kinase mediate phosphorylation of Brca1 at distinct and overlapping sites - In vivo assessment using phospho-specific antibodies

Recent studies have provided evidence that breast cancer susceptibility gene products (Brca1 and Brca2) suppress cancer, at least in part, by participating in DNA damage signaling and DNA repair. Brca1 is hyperphosphorylated in response to DNA damage and co-localizes with Rad51, a protein involved in homologous-recombination, and Nbs1.Mre11.Rad50, a complex required for both homologous-recombination and nonhomologous end joining repair of damaged DNA. Here, we report that there is a qualitative difference in the phosphorylation states of Brca1 between ionizing radiation (IR) and UV radiation. Brca1 is phosphorylated at Ser-1423 and Ser-1524 after IR and W; however, Ser-1387 is specifically phosphorylated after IR, and Ser-1457 is predominantly phosphorylated after W. These results suggest that different types of DNA-damaging agents might signal to Brca1 in different ways. We also provide evidence that the rapid phosphorylation of Brca1 at Ser-1423 and Ser-1524 after IR (but not after W) is largely ataxia telangiectasia mutated (ATM) kinase-dependent. The overexpression of catalytically inactive ATM and Rad3 related (ATR) kinase inhibited the UV-induced phosphorylation of Brca1 at these sites, indicating that ATR controls Brca1 phosphorylation in vivo after the exposure of cells to UV light. Moreover, ATR associates with Brca1; ATR and Brca1 foci co-localize both in cells synchronized in S phase and after exposure of cells to DNA-damaging agents. ATR can itself phosphorylate the region of Brca1 phosphorylated by ATM (Ser-Gln cluster in the C terminus of Brca1, amino acids 1241-1530), However, there are additional uncharacterized ATR phosphorylation site(s) between residues 521 and 757 of Brca1, Taken together, our results support a model in which ATM and ATR act in parallel but somewhat overlapping pathways of DNA damage signaling but respond primarily to different types of DNA lesion.

Evolution of colorectal cancer: Change of pace and change of direction

This review compiles evidence for an alternative to the classical adenoma-carcinoma sequence in the evolution of colorectal cancer. It is suggested that between 30 and 50% of colorectal cancers are not initiated by mutation of the tumor suppressor gene APC, but through the epigenetic silencing of genes implicated in the control of differentiation, cell cycle control and DNA repair proficiency. The precursor polyps are often characterized by a serrated architecture, and include hyperplastic polyps, admixed polyps and serrated adenomas. The alternative pathway is heterogeneous and may culminate in cancers showing low or high level DNA microsatellite instability (MSI-L and MSI-H, respectively), and in cancers that are microsatellite stable (MSS). Cancers showing DNA MSI may be characterized by an accelerated evolution. Cancers in hereditary non-polyposis colorectal cancer show features of both classical (adenoma and APC mutation) and alternative pathways (rapid evolution, MSI-H and lack of chromosomal instability). (C) 2001 Blackwell Science Asia Pty Ltd.