Functional differences in visceral and subcutaneous fat pads originate from differences in the adipose stem cell.

Metabolic pathologies mainly originate from adipose tissue (AT) dysfunctions. AT differences are associated with fat-depot anatomic distribution in subcutaneous (SAT) and visceral omental (VAT) pads. We address the question whether the functional differences between the two compartments may be present early in the adipose stem cell (ASC) instead of being restricted to the mature adipocytes. Using a specific human ASC model, we evaluated proliferation/differentiation of ASC from abdominal SAT-(S-ASC) and VAT-(V-ASC) paired biopsies in parallel as well as the electrophysiological properties and functional activity of ASC and their in vitro-derived adipocytes. A dramatic difference in proliferation and adipogenic potential was observed between the two ASC populations, S-ASC having a growth rate and adipogenic potential significantly higher than V-ASC and giving rise to more functional and better organized adipocytes. To our knowledge, this is the first comprehensive electrophysiological analysis of ASC and derived-adipocytes, showing electrophysiological properties, such as membrane potential, capacitance and K(+)-current parameters which confirm the better functionality of S-ASC and their derived adipocytes. We document the greater ability of S-ASC-derived adipocytes to secrete adiponectin and their reduced susceptibility to lipolysis. These features may account for the metabolic differences observed between the SAT and VAT. Our findings suggest that VAT and SAT functional differences originate at the level of the adult ASC which maintains a memory of its fat pad of origin. Such stem cell differences may account for differential adipose depot susceptibility to the development of metabolic dysfunction and may represent a suitable target for specific therapeutic approaches.

Characterization of human adult stem-cell populations isolated from visceral and subcutaneous adipose tissue.

Adipose tissue is a dynamic endocrine organ with a central role in metabolism regulation. Functional differences in adipose tissue seem associated with the regional distribution of fat depots, in particular in subcutaneous and visceral omental pads. Here, we report for the first time the isolation of human adipose-derived adult stem cells from visceral omental and subcutaneous fat (V-ASCs and S-ASCs, respectively) from the same subject. Immunophenotyping shows that plastic culturing selects homogeneous cell populations of V-ASCs and S-ASCs from the corresponding stromal vascular fractions (SVFs), sharing typical markers of mesenchymal stem cells. Electron microscopy and electrophysiological and real-time RT-PCR analyses confirm the mesenchymal stem nature of both V-ASCs and S-ASCs, while no significant differences in a limited pattern of cytokine/chemokine expression can be detected. Similar to S-ASCs, V-ASCs can differentiate in vitro toward adipogenic, osteogenic, chondrogenic, muscular, and neuronal lineages, as demonstrated by histochemical, immunofluorescence, real-time RT-PCR, and electrophysiological analyses, suggesting the multipotency of such adult stem cells. Our data demonstrate that both visceral and subcutaneous adipose tissues are a source of pluripotent stem cells with multigermline potential. However, the visceral rather than the subcutaneous ASC could represent a more appropriate in vitro cell model for investigating the molecular mechanisms implicated in the pathophysiology of metabolic disorders such as obesity.

PPARgamma in Neuroblastoma.

Neuroblastoma (NB) is the most common extracranial tumor in children and accounts for around 15% of all paediatric oncology deaths. The treatment of NB includes surgery, chemotherapy, and radiotherapy. Unfortunately, most children with NB present with advanced disease, and more than 60% of patients with high-risk features will have a poor prognosis despite intensive therapy. Agonists of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) have been shown to have pleiotropic effects, including antineoplastic effects. The studies that addressed the role and the possible mechanism(s) of action of PPARgamma in NB cells are reviewed.

Stability of BAT26 in tumours of hereditary nonpolyposis colorectal cancer patients with MSH2 intragenic deletion.

Colon cancers arising in most patients with hereditary nonpolyposis colorectal cancer (HNPCC) show microsatellite instability (MSI). BAT26, a quasimonomorphic polyA stretch located just 3' of MSH2 exon 5, is considered the most sensitive and specific marker of MSI. A total of 10 HNPCC families with large intragenic MSH2 deletions, encompassing exon 5 and intron 5, identified by multiplex ligation-dependent probe amplification (MLPA) were included in this study. The deletions under study were del1-16, del1-8, del1-7, del1-6, and del3-6, detected in 3, 1, 2, 3, and 1 families, respectively. Although all patients examined from these 10 families developed unstable tumours, 13/19 MSI-H tumours (68 %) surprisingly showed stability of BAT26. By MLPA and MSH2 sequence analyses of the BAT26-stable tumours, we demonstrated that the wild-type MSH2 allele was somatically inactivated by an identical large deletion, with complete loss of intron 5/BAT26 sequences at the tumour DNA level. We could infer that the apparent stability of BAT26 was due to the complete absence of target BAT26 sequences in the tumour sample, which results in exclusive amplification of contaminant normal DNA, containing a single copy of a wild-type stable BAT26 sequence. Identification of a subset of MSH2-related unstable tumours that are not recognized by analysis of BAT26 instability indicates that this marker should never be used alone for rapid MSI screening of HNPCC tumours. Moreover, our findings indicate that BAT26 stability in the context of MSI is strongly suggestive of the presence of a large intragenic MSH2 deletion.

Molecular genetic alterations and clinical features in early-onset colorectal carcinomas and their role for the recognition of hereditary cancer syndromes.

OBJECTIVES: Colorectal cancer (CRC) occurs rarely in young individuals (<45 yr) and represents one of the criteria for suspecting hereditary cancer families. In this study we evaluated clinical features and molecular pathways (chromosomal instability [CIN] and microsatellite instability [MSI]) in early-onset CRC of 71 patients. METHODS: Detailed family and personal history were obtained for each patient. Expression of APC, beta-catenin, p53, MLH1, MSH2, and MSH6 genes was evaluated by immunohistochemistry. MSI analysis was performed and constitutional main mutations of the mismatch repair (MMR) genes were searched by gene sequencing. RESULTS: Fourteen (19.7%) out of the 71 cases showed both MSI and altered expression of MMR proteins. In the 57 MSI-negative (MSI-) lesions altered expression of APC, beta-catenin, and p53 genes were found more frequently than in MSI-positive(MSI+) tumors. Seven (50%) out of the 14 patients with MSI+ tumors presented clinical features of Lynch syndrome (hereditary non-polyposis colorectal cancer [HNPCC]) and in all but one, constitutional mutations in MLH1 or MSH2 genes could be detected. The same mutations were also found in other family members. CONCLUSIONS: Our study demonstrates the involvement of CIN in a majority of early-onset colorectal tumors. Furthermore, we identified Lynch syndromes in seven cases (50%) of early-onset colorectal carcinomas with impairment of the MMR system. These results suggest that patients with early-onset CRC should be screened for hereditary cancer syndrome through clinical and molecular characterizations.

Expression of the antiapoptotic gene seladin-1 and octreotide-induced apoptosis in growth hormone-secreting and nonfunctioning pituitary adenomas.

CONTEXT: Seladin-1 (from selective Alzheimer's disease indicator-1) is a recently discovered gene that has been found to be down-regulated in brain regions affected by Alzheimer's disease. Seladin-1 effectively protects neurons against beta-amyloid-mediated toxicity and prevents apoptosis via inhibition of the activation of caspase-3, a key mediator of the apoptotic cascade. Although seladin-1 is expressed in the pituitary gland, no study addressed the expression or the function of this gene in pituitary adenomas. OBJECTIVE: The aim of the present study was to determine the expression level of the seladin-1 gene in pituitary tumors, i.e. GH-secreting and nonfunctioning pituitary adenomas (NFPA), and to determine whether differential expression might be associated with different somatostatin (sst)-induced apoptosis. RESULTS: We found by quantitative real-time RT-PCR that the expression level of seladin-1 was significantly higher in NFPA (n = 21) than in GH-secreting adenomas (n = 30; mean +/- se, 25.69 +/- 6.39 vs. 8.02 +/- 2.68 pg/microg total RNA; P = 0.006). Although the amount of activated caspase-3 did not differ between the two groups of tumors, in primary cell cultures, octreotide was able to increase apoptosis, evaluated by the level of cleaved cytokeratin 18 and the presence of apoptotic nuclei, in GH-secreting adenomas, but not in NFPA. This different response was not attributable to differences in the amount of transcript of sst receptors 2 and 5, which was similar in the two groups of tumors. CONCLUSIONS: Our results suggest that differential seladin-1 expression in pituitary adenomas may be associated with a different apoptotic response to sst analogs.

A kindred with MYH-associated polyposis and pilomatricomas.

MYH-associated polyposis (MAP) is a recently described autosomal recessive form of familial adenomatous polyposis (FAP) associated with susceptibility to colorectal carcinoma (CRC). MAP is caused by biallelic inactivating mutations of the MYH gene, a component of the base excision repair (BER) machinery, whose dysfunction leads to an increase in the rate of G > T transversions following DNA oxidative damage. MAP patients can present with either classic or attenuated polyposis. However, the MAP colonic and extracolonic phenotype has yet to be defined. We report on two siblings, born from consanguineous parents, who were found to be homozygotes for an MYH frameshift mutation. The propositus presented with a low number of colonic lesions and an early-onset CRC. Both siblings had a history of pilomatricomas, benign tumors derived from hair follicles, in childhood. The findings presented provide further evidence of phenotypic variability in MAP, and suggest that multiple pilomatricomas may be a useful cutaneous marker of MAP.

Identification of a novel mutation in the arginine vasopressin-neurophysin II gene affecting the sixth intrachain disulfide bridge of the neurophysin II moiety.

OBJECTIVE: Most mutations of the arginine vasopressin-neurophysin II (AVP-NPII) gene cause autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI). Such mutations are predicted to alter the three-dimensional structure of the prohormone, which accumulates in the cell body, ultimately leading to neuronal degeneration and hormonal deficit. In this study we describe the case of a 26-year-old female reporting a long-lasting history of polyuria/polydipsia. The father of the patient was affected by diabetes insipidus and was under desmopressin treatment until the time of his death. Nevertheless, the patient had never been subjected to endocrine evaluation. DESIGN AND METHODS: Clinical and genetic studies were performed. An 8-h fluid deprivation test plus desmopressin challenge and a 5% saline solution test were performed, in order to confirm the diagnosis. DNA was extracted from peripheral blood lymphocytes and subjected to direct sequencing of the entire coding region of the AVP-NPII gene. RESULTS AND CONCLUSIONS: Clinical assessment of the patient confirmed the diagnosis of neurohypophyseal diabetes insipidus. Desmopressin treatment was started, which effectively reversed the polyuria/ polydipsia syndrome. Genetic analysis revealed a novel mutation (1665T>A) in exon 2 of the AVP-NPII gene, disrupting one of the disulfide bonds present in the NPII moiety which play a fundamental role in determining the proper folding of the molecule. In summary, in the present study we have described a novel mutation of the AVP-NPII gene, which is consistent with the malfolding/toxicity hypothesis underlying the pathogenesis of adFNDI.

Simple and complex genetics of colorectal cancer susceptibility.

There are several hereditary conditions associated with an increased risk of colorectal cancer (CRC). These include well-characterized autosomal dominant syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). A novel autosomal recessive form of FAP, caused by mutations in the base excision repair gene MYH, has recently been recognized. This discovery has provided further evidence for the importance of DNA repair mechanisms in CRC development, already documented by the involvement of the mismatch repair in HNPCC. Additional CRC-predisposing conditions, such as hyperplastic polyposis and hereditary mixed polyposis syndrome, are being outlined. Heterogeneity of genetic mechanisms has important consequences for counseling and surveillance in hereditary CRC. Nevertheless, classical mendelian conditions represent only a minor share of the total CRC population burden. Alleles of the same genes that are involved in hereditary syndromes might also act as low penetrance variants, as shown for APC 1307K in the Ashkenazi. However, the level of complexity of multifactorial CRC is such that current tools appear inadequate to pinpoint all the involved components. A combination of different strategies, including careful clinical observation, analysis of homogeneous patient populations, and critical evaluation of data derived from experimental models, along with methodological improvements in nucleic acid analysis, will probably be necessary to unravel the basis of nonmendelian CRC. Once this is achieved, it will be possible to realize the ultimate goal of targeted CRC prevention, with the adoption of measures tailored according to individual risk levels. .

Susceptibility to refractory ulcerative colitis is associated with polymorphism in the hMLH1 mismatch repair gene.

The hMLH1 gene lies in the linkage susceptibility region to inflammatory bowel disease (IBD) on 3p21. A single nucleotide polymorphism, 655A>G, in exon 8 of the gene causes an I219V change in the MLH1 protein. To test whether hMLH1 may confer susceptibility to ulcerative colitis (UC), we investigated an association between the 655A>G polymorphism and the disease. DNA-based technologies were used to analyze the 655A>G polymorphism in 201 UC patients and 126 healthy ethnically matched controls. The comparison of the allelic frequencies of the 655A>G polymorphism in UC patients and healthy controls did not show significant differences. However, genotype frequencies at the hMLH1 655 position were found to be significantly different when patients with and without refractory UC were compared. This was mainly attributable to a higher level of homozygosity for the G allele in refractory UC patients. Almost 5 times as many (4.9 times) refractory UC patients carried the GG genotype compared with nonrefractory patients (P < 0.0001). The present study provides evidence that the hMLH1 gene is involved in genetic susceptibility to refractory UC. If confirmed by other studies, the GG genotype at position 655 of the hMLH1 gene may represent a useful predictive factor for the clinical management of UC patients.