DNA methylation variations are required for epithelial-to-mesenchymal transition induced by cancer-associated fibroblasts in prostate cancer cells.

Widespread genome hypo-methylation and promoter hyper-methylation of epithelium-specific genes are hallmarks of stable epithelial-to-mesenchymal transition (EMT), which in prostate cancer (PCa) correlates with castration resistance, cancer stem cells generation, chemoresistance and worst prognosis. Exploiting our consolidated 'ex-vivo' system, we show that cancer-associated fibroblasts (CAFs) released factors have pivotal roles in inducing genome methylation changes required for EMT and stemness in EMT-prone PCa cells. By global DNA methylation analysis and RNA-Seq, we provide compelling evidence that conditioned media from CAFs explanted from two unrelated patients with advanced PCa, stimulates concurrent DNA hypo- and hyper-methylation required for EMT and stemness in PC3 and DU145, but not in LN-CaP and its derivative C4-2B, PCa cells. CpG island (CGI) hyper-methylation associates with repression of genes required for epithelial maintenance and invasion antagonism, whereas activation of EMT markers and stemness genes correlate with CGI hypo-methylation. Remarkably, methylation variations and EMT-regulated transcripts almost completely reverse qualitatively and quantitatively during MET. Unsupervised clustering analysis of the PRAD TCGA data set with the differentially expressed (DE) and methylated EMT signature, identified a gene cluster of DE genes defined by a CAF+ and AR- phenotype and worst diagnosis. This gene cluster includes the relevant factors for EMT and stemness, which display DNA methylation variations in regulatory regions inversely correlated to their expression changes, thus strongly sustaining the ex-vivo data. DNMT3A-dependent methylation is essential for silencing epithelial maintenance and EMT counteracting genes, such as CDH1 and GRHL2, that is, the direct repressor of ZEB1, the key transcriptional factor for EMT and stemness. Accordingly, DNMT3A knock-down prevents EMT entry. These results shed light on the mechanisms of establishment and maintenance of coexisting DNA hypo- and hyper-methylation patterns during cancer progression, the generation of EMT and cell stemness in advanced PCa, and may pave the way to new therapeutic implications.

The miR-27a-calreticulin axis affects drug-induced immunogenic cell death in human colorectal cancer cells.

Immunogenic cell death (ICD) evoked by chemotherapeutic agents implies emission of selected damage-associated molecular patterns (DAMP) such as cell surface exposure of calreticulin, secretion of ATP and HMGB1. We sought to verify whether miR-27a is implicated in ICD, having demonstrated that it directly targets calreticulin. To this goal, we exposed colorectal cancer cell lines, genetically modified to express high or low miR-27a levels, to two bona fide ICD inducers (mitoxantrone and oxaliplatin). Low miR-27a-expressing cells displayed more ecto-calreticulin on the cell surface and increased ATP and HMGB1 secretion than high miR-27a-expressing ones in time-course experiments upon drug exposure. A calreticulin target protector counteracted the miR-27a effects while specific siRNAs mimicked them, confirming the results reported. In addition, miR-27a negatively influenced the PERK-mediated route and the late PI3K-dependent secretory step of the unfolded protein response to endoplasmic reticulum stress, suggesting that miR-27a modulates the entire ICD program. Interestingly, upon chemotherapeutic exposure, low miR-27a levels associated with an earlier and stronger induction of apoptosis and with morphological and molecular features of autophagy. Remarkably, in ex vivo setting, under the same chemotherapeutic induction, the conditioned media from high miR-27a-expressing cells impeded dendritic cell maturation while increased the secretion of specific cytokines (interleukin (IL)-4, IL-6, IL-8) and negatively influenced CD4(+) T-cell interferon γ production and proliferation, all markers of a tumor immunoevasion strategy. In conclusion, we provide the first evidence that miR-27a impairs the cell response to drug-induced ICD through the regulatory axis with calreticulin.

Proteomic screening identifies calreticulin as a miR-27a direct target repressing MHC class I cell surface exposure in colorectal cancer.

Impairment of the immune response and aberrant expression of microRNAs are emerging hallmarks of tumour initiation/progression, in addition to driver gene mutations and epigenetic modifications. We performed a preliminary survey of independent adenoma and colorectal cancer (CRC) miRnoma data sets and, among the most dysregulated miRNAs, we selected miR-27a and disclosed that it is already upregulated in adenoma and further increases during the evolution to adenocarcinoma. To identify novel genes and pathways regulated by this miRNA, we employed a differential 2DE-DIGE proteome analysis. We showed that miR-27a modulates a group of proteins involved in MHC class I cell surface exposure and, mechanistically, demonstrated that calreticulin is a miR-27a direct target responsible for most downstream effects in epistasis experiments. In vitro miR-27a affected cell proliferation and angiogenesis; mouse xenografts of human CRC cell lines expressing different miR-27a levels confirmed the protein variations and recapitulated the cell growth and apoptosis effects. In vivo miR-27a inversely correlated with MHC class I molecules and calreticulin expression, CD8(+) T cells infiltration and cytotoxic activity (LAMP-1 exposure and perforin release). Tumours with high miR-27a, low calreticulin and CD8(+) T cells' infiltration were associated with distant metastasis and poor prognosis. Our data demonstrate that miR-27a acts as an oncomiRNA, represses MHC class I expression through calreticulin downregulation and affects tumour progression. These results may pave the way for better diagnosis, patient stratification and novel therapeutic approaches.

A specific DNA methylation profile correlates with a high risk of disease progression in stage I classical (Alibert-Bazin type) mycosis fungoides.

BACKGROUND: Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma; in its classical presentation it evolves slowly, but it can have an aggressive course in a subset of patients. OBJECTIVES: To investigate the impact of epigenetic mechanisms on the progression of early stage MF. METHODS: We analysed DNA methylation at 12 different loci and long interspersed nucleotide elements-1 (LINE-1), as a surrogate marker of global methylation, on tissue samples from 41 patients with stage I MF followed up for at least 12 years or until disease progression. The methylation profiles were also analysed in two T-cell lymphoma cell lines and correlated with gene expression. RESULTS: The selected loci were methylated in a tumour-specific manner; concomitant hypermethylation of at least four loci was more frequent in cases progressing within 1-3 and 3-6 years than in late-progressive or non-progressive cases. LINE-1 methylation was significantly lower in rapidly progressive MF at 3 years (61%, P < 0·001) than in those at 12 years (67%). PPARG, SOCS1 and NEUROG1 methylation showed remarkable differences among the prognostic groups, but only PPARG was a significant predictor of disease progression within 6 years, after adjustment for patients' age or gender. Strikingly, a methylation profile similar to progressive cases was found in highly proliferative Sézary-derived HUT78 cells but not in MF-derived HUT102 cells. Exposure to a DNA demethylating agent restored sensitivity to apoptosis and cell cycle arrest. CONCLUSIONS: Epigenetic silencing of specific biomarkers can predict the risk of disease progression in early-stage MF, providing insights into its pathogenesis, prognosis and therapy.

Impact of long-acting octreotide in patients with early-stage MEN1-related duodeno-pancreatic neuroendocrine tumours.

BACKGROUND: Somatostatin analogues (SSA) represent one of the main therapeutic option in patients affected with functioning well-differentiated neuroendocrine tumours (NETs). There are no studies specifically focusing on NETs associated with Multiple Endocrine Neoplasia type 1 (MEN1). AIM: To evaluate the efficacy of the long-acting SSA octreotide in MEN1 patients with early-stage duodeno-pancreatic NETs. PATIENTS AND METHODS: Forty patients with MEN1 were retrospectively evaluated. Twenty patients with evidence of one or more MEN1-related duodeno-pancreatic NETs < 20 mm in size (age range 26-61 years) were treated with octreotide long-acting octreotide (LAR) as first-line therapy. Treatment duration ranged 12-75 months. At the baseline radiological evaluation, multiple duodeno-pancreatic NETs (range 1-8, size 3-18 mm) were detected. RESULTS: An objective tumour response was observed in 10%, stable disease in 80% and progression of disease in 10% of cases. In six patients with abnormally increased CgA, gastrin and/or insulin serum concentrations, a significant clinical and hormonal response occurred in 100% of cases and was stable along the time. CONCLUSIONS: Therapy with SSA is highly safe and effective in patients with early-stage MEN1 duodeno-pancreatic NETs, resulting in long-time suppression of tumour and hormonal activity and 10% objective response. This suggests to early start therapy with SSA in patients with MEN1-related NETs.

Multiple endocrine neoplasia, the old and the new: a mini review.

Multiple endocrine neoplasia syndromes have since been classified as types 1 and 2, each with specific phenotypic patterns. MEN1 is usually associated with pituitary, parathyroid and paraneoplastic neuroendocrine tumours. The hallmark of MEN2 is a very high lifetime risk of developing medullary thyroid carcinoma (MTC) more than 95% in untreated patients. Three clinical subtypesdMEN2A, MEN2B, and familial MTC (FMTC) have been defined based on the risk of pheochromocytoma, hyperparathyroidism, and the presence or absence of characteristic physical features). MEN2 occurs as a result of germline activating missense mutations of the RET (REarranged during Transfection) proto-oncogene. MEN2-associated mutations are almost always located in exons 10, 11, or 13 through 16. Strong genotype-phenotype correlations exist with respect to clinical subtype, age at onset, and aggressiveness of MTC in MEN2. These are used to determine the age at which prophylactic thyroidectomy should occur and whether screening for pheochromocytoma or hyperparathyroidism is necessary. Specific RET mutations can also impact management in patients presenting with apparently sporadic MTC. Therefore, genetic testing should be performed before surgical intervention in all patients diagnosed with MTC. Recently, Pellegata et al. have reported that germline mutations in CDKN1B can predispose to the development of multiple endocrine tumours in both rats and humans and this new MEN syndrome is named MENX and MEN4, respectively. CDKN1B. A recent report showed that in sporadic MTC, CDKN1B V109G polymorphism correlates with a more favorable disease progression than the wild-type allele and might be considered a new promising prognostic marker. New insights on MEN syndrome pathogenesis and related inherited endocrine disorders are of particular interest for an adequate surgical and therapeutic approach.

UHRF1 coordinates peroxisome proliferator activated receptor gamma (PPARG) epigenetic silencing and mediates colorectal cancer progression.

Peroxisome proliferator-activated receptor gamma (PPARG) inactivation has been identified as an important step in colorectal cancer (CRC) progression, although the events involved have been partially clarified. UHRF1 is emerging as a cofactor that coordinates the epigenetic silencing of tumor suppressor genes, but its role in CRC remains elusive. Here, we report that UHRF1 negatively regulates PPARG and is associated with a higher proliferative, clonogenic and migration potential. Consistently, UHRF1 ectopic expression induces PPARG repression through its recruitment on the PPARG promoter fostering DNA methylation and histone repressive modifications. In agreement, UHRF1 knockdown elicits PPARG re-activation, accompanied by positive histone marks and DNA demethylation, corroborating its role in PPARG silencing. UHRF1 overexpression, as well as PPARG-silencing, imparts higher growth rate and phenotypic features resembling those occurring in the epithelial-mesenchymal transition. In our series of 110 sporadic CRCs, high UHRF1-expressing tumors are characterized by an undifferentiated phenotype, higher proliferation rate and poor clinical outcome only in advanced stages III-IV. In addition, the inverse relationship with PPARG found in vitro is detected in vivo and UHRF1 prognostic significance appears closely related to PPARG low expression, as remarkably validated in an independent dataset. The results demonstrate that UHRF1 regulates PPARG silencing and both genes appear to be part of a complex regulatory network. These findings suggest that the relationship between UHRF1 and PPARG may have a relevant role in CRC progression.

A novel germline mutation in peroxisome proliferator-activated receptor gamma gene associated with large intestine polyp formation and dyslipidemia.

We report a novel PPARG germline mutation in a patient affected by colorectal cancer that replaces serine 289 with cysteine in the mature protein (S289C). The mutant has impaired transactivation potential and acts as dominant negative to the wild type receptor. In addition, it no longer restrains cell proliferation both in vitro and in vivo. Interestingly, the S289C mutant poorly activates target genes and interferes with the inflammatory pathway in tumor tissues and proximal normal mucosa. Consistently, only mutation carriers exhibit colonic lesions that can evolve to dysplastic polyps. The proband presented also dyslipidemia, hypertension and overweight, not associated to type 2 diabetes; of note, family members tested positive for the mutation and display only a dyslipidemic profile at variable penetrance with other biochemical parameters in the normal range. Finally, superimposing the mutation to the crystal structure of the ligand binding domain, the new Cys289 becomes so closely positioned to Cys285 to form an S-S bridge. This would reduce the depth of the ligand binding pocket and impede agonist positioning, explaining the biological effects and subcellular distribution of the mutant protein. This is the first PPARG germline mutation associated with dyslipidemia and colonic polyp formation that can progress to full-blown adenocarcinoma.

The high expression of p53 in sporadic colorectal carcinoma is associated with metastasis and decreased survival.

INTRODUCTION: Alteration in the p53 tumour suppressor gene is an event that occurs frequently in human cancer, although its role as predictive and/or prognostic marker is still unclear. The aim of this study was to compare the expression profiles of p53 in colorectal carcinoma with clinicopathological features and survival rate at 5 years from diagnosis. METHODS: One hundred and twenty cases of primary sporadic colorectal cancers (CRCs) and 80 matched normal mucosas were analyzed by immunohistochemistry on paraffin-embedded specimens. The correlation between protein expression profiles, clinicopathological parameters and survival was investigated. RESULTS: In tumour tissues, the expression of p53 was high in 41 cases, low in 38 and negative in 41. A significant correlation was observed between increased p53 expression presence of lymph node (p = 0.002) or liver metastasis (p = 0.008). Moreover, higher levels of p53 were related with advanced tumour stage (III-IV; p = 0.007), poor survival and disease recurrence (p < 0.01). Interestingly, in multivariate analysis p53 expression and distant metastasis were independent prognostic markers. DISCUSSION: Our results suggest that nuclear p53 accumulation in sporadic CRC may have prognostic significance and contribute to identification of patients at high risk of mortality. The current findings may be relevant for management of patients with CRC.

Genetic prenatal RET testing and pregnancy management of multiple endocrine neoplasia Type II A (MEN2A): a case report.

Multiple endocrine neoplasia 2A (MEN 2A) is an inherited dominant syndrome characterised by medullary thyroid carcinoma, adrenal pheochromocytoma and hyperparathyroidism due to specific RET proto-oncogene mutations. Fertile MEN 2A women are at risk of complicated pregnancy because of unrecognised pheochromocytoma and transmission of RET mutation to the progeny. This condition may cause psychological distress in affected pregnant patients and their families. Here we describe the genetic prenatal testing, the pregnancy management and obstetric outcome in a MEN 2A patient with a right side adrenal hyperplasia and elevated calcitonin levels, a condition suspicious for possible recurrence of pheochromocytoma. We confirm that maternal or fetal complications are rare when MEN 2A diagnosis is made before pregnancy and an accurate monitoring is instituted. Furthermore, our results indicate that prenatal testing for RET mutations is highly recommended in making decisions and assuring parents on the lifelong risk of tumors. This will avoid the psychological distress that can further complicate the pregnancy of affected women.

Fasting plasma free fatty acid concentrations and Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR) gamma2 gene in healthy individuals.

BACKGROUND: The Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR) gamma gene has been associated in some, but not all, studies with lower body mass index (BMI) and improved insulin sensitivity; how an altered transcriptional activity of PPARgamma2 could influence insulin sensitivity is currently unclear. The free fatty acids (FFAs) released from adipose tissue triglycerides via lipolysis are key mediators of impaired insulin sensitivity; however, no study has described the relationship of the Pro12Ala mutation with circulating levels of FFAs under physiological conditions. OBJECTIVE: To investigate in a population-based sample of Caucasians the relation of the Pro12Ala polymorphism with plasma concentrations of FFAs and other markers of lipid and glucose metabolism described as components of the insulin resistance syndrome. SUBJECTS: Four hundred and thirty-eight nondiabetic employees of the Italian Telephone Company, aged 35-65 years, randomly selected from a total population of 3900 participants in a company-sponsored health screening. MEASUREMENTS: The Pro12Ala polymorphism of the PPARgamma was studied together with plasma FFAs, insulin, glucose, triglycerides, high density lipoprotein (HDL) cholesterol, blood pressure and anthropometry. The Homeostatic Model Assessment (HOMA) index was calculated as a measure of insulin resistance. RESULTS: Carriers and noncarriers of the Pro12Ala polymorphism showed very similar circulating levels of FFA (0.46 +/- 0.2 vs. 0.47 +/- 0.2, NS); plasma glucose, triglycerides, HDL cholesterol and blood pressure were also similar in the two groups with or without the polymorphism. To allow for the possible confounding effect of obesity, a separate analysis was conducted in overweight (BMI > or = 25 kg/m(2)) and normal-weight people (BMI < 25 kg/m(2)). Circulating plasma FFA concentrations, as well as triglycerides, blood pressure and HOMA, were significantly higher in overweight than normal-weight, as expected, but no significant differences were detected between carriers and noncarriers of the Pro12Ala polymorphism within each BMI group (0.49 +/- 0.2 vs. 0.48 +/- 0.2, NS, and 0.44 +/- 0.2 vs. 0.47 +/- 0.2, NS, in overweight and normal-weight, respectively). The Pro12Ala polymorphism was also analysed across increasing quartiles of FFA concentrations and no relationship was observed between the frequency of the polymorphism and FFA values (overall chi2 = 0.48, NS). CONCLUSION: This study does not show any relationship between the Pro12Ala polymorphism of the PPARgamma gene and fasting FFAs in the general population. The possibility of a different handling of FFAs under different conditions (i.e. postprandial) cannot be excluded and remains to be explored.

Preservation of light signaling to the suprachiasmatic nucleus in vitamin A-deficient mice.

To investigate the role of retinal-based pigments (opsins) in circadian photoreception in mice, animals mutated in plasma retinol binding protein were placed on a vitamin A-free diet and tested for photic induction of gene expression in the suprachiasmatic nucleus. After 10 months on the vitamin A-free diet, the majority of mice contained no detectable retinal in their eyes. These mice demonstrated fully intact photic signaling to the suprachiasmatic nucleus as measured by acute mPer mRNA induction in the suprachiasmatic nucleus in response to bright or dim light. The data suggest that a non-opsin pigment is the primary circadian photoreceptor in the mouse.

In vivo and in vitro studies of cytosolic phospholipase A2 expression in Helicobacter pylori infection.

Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A2 activity (PLA2). The cytosolic form of this enzyme (cPLA2), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA2 expression and PLA2 activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori-positive patients, cPLA2 levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA2 activity were higher than in 10 H. pylori-negative gastritis patients. To clarify whether H. pylori had a direct effect on the cellular expression of cPLA2, we studied cPLA2 expression in vitro with different human epithelial cell lines, one from a patient with larynx carcinoma (i.e., HEp-2 cells) and two from patients with gastric adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA2, mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA2 protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori. In conclusion, our study shows increased cPLA2 expression and PLA2 activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.

Retinol mobilization from cultured rat hepatic stellate cells does not require retinol binding protein synthesis and secretion.

Retinol mobilization from retinyl esters stores of hepatic stellate cells (HSCs) is a key step in the regulation of mammalian retinol homeostasis, but the precise mechanisms of such a mobilization are still poorly understood. Using primary cultures of HSCs, we first demonstrated that HSCs expressed immunoreactivity against retinol-binding-protein (RBP) when cultured in a medium containing RBP but were unable to synthesize RBP transcripts and proteins. Using pulse and chase-type experiments, we demonstrated that radioactive retinol was released in culture medium without binding proteins. Inhibition of protein secretion by brefeldin A did not modify quantitatively retinol release. This data ruled out, for the first time, the direct involvement of RBP in retinol mobilization from HSCs. Moreover, HSCs co-cultured with primary isolated hepatocytes displayed an increase of retinol transfer from HSCs to hepatocytes when they established direct physical contacts, as compared with co-cultures without contact. Based on this latter data, a mechanism of retinol mobilization from HSCs via the hepatocytes using retinol transfer through cellular membranes is proposed.

Loss of heterozygosity at the RET protooncogene locus in a case of multiple endocrine neoplasia type 2A.

We describe a patient affected by multiple endocrine neoplasia type 2A (MEN 2A) bearing a heterozygous germline mutation (Cys(634)Arg) in exon 11 and an additional somatic mutation of the RET protooncogene. A large intragenic deletion, spanning exon 4 to exon 16, affected the normal allele and was detected by quantitative PCR, Southern blot analysis, and screening of several polymorphic markers. This deletion causes RET loss of heterozygosity exclusively in the metastasis, thus suggesting a role for this second mutational event in tumor progression. No additional mutations were found in the other exons analyzed. We provide the first evidence that RET, a dominant oncogene, is affected by a germline mutation and by an additional somatic deletion of the wild-type allele. This unusual genetic profile may be related to the clinical course and very poor outcome.

Fenofibrate prevents and reduces body weight gain and adiposity in diet-induced obese rats.

Fibrates are hypolipidemic drugs that activate the peroxisome proliferator-activated receptors. Since fibrates may also increase energy expenditure, we investigated whether fenofibrate (FF) had this effect in diet-induced obese rats. A 2-month administration of a high-fat palatable diet to adult rats increased body weight by 25% and white adipose mass by 163% compared with a standard diet. These effects were prevented by FF, both when administered for the 2 months of high-fat feeding and when given for only the second month. Consequently, FF-treated rats had a final body weight and white adipose tissue mass similar to untreated animals on the standard diet. FF also increased resting metabolic rate, hepatic peroxisomal and mitochondrial palmitoyl-dependent oxygen uptake and mRNA levels of acyl-CoA oxidase and lipoprotein lipase. Finally, FF lowered mRNA levels of uncoupling protein-2 and did not affect mitochondrial respiration in skeletal muscle. Therefore, FF seems to act as a weight-stabilizer mainly through its effect on liver metabolism.

Medullary thyroid cancer, papillary thyroid microcarcinoma and Graves' disease: an unusual clinical coexistence.

We describe the unusual case of a Caucasian woman who had a diagnosis of medullary thyroid cancer and papillary microcarcinoma 5 years after a diagnosis of Graves' disease. The patient came to our observation for recurrence of hyperthyroidism. An ultrasound scan revealed diffuse thyroid enlargement with a nodule, recently increased in size. The serum CT and carcinoembrional antigen were elevated, and the fine-needle aspiration cytology with immunocytochemical analysis for CT was suggestive for medullary thyroid carcinoma. The nodular lesion showed intense 111In-pentetreotide uptake, whereas total body scintigraphy with the same tracer and with Thallium-201, 99mTc (V) dimercaptosuccinic acid was negative for lymph node and distant metastasis. The histological examination of thyroidectomy specimens confirmed the diagnosis of medullary thyroid cancer, showing a lymphocytic intratumoral infiltration. The histological analysis of the controlateral lobe showed an occult papillary microcarcinoma. Medullary thyroid carcinoma and papillary microcarcinoma showed intense staining with policlonal anti-RET antibodies, although genetic analysis was negative for RET mutations most frequently involved in familial and sporadic medullary thyroid carcinomas. Possible implications about the coexistence of the 3 thyroid diseases are discussed.

Pro12Ala mutation in the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) and severe obesity: a case-control study.

OBJECTIVE: To explore the association of the Pro12Ala mutation in the peroxisome proliferator-activated receptor gamma2 with severe obesity and the features of the metabolic syndrome in a population-based sample of Caucasians. PARTICIPANTS AND METHODS: The study is based on a case-control design: 95 non-diabetic severely obese (body mass index, BMI > 35 kg/m2) cases and 280 normal weight (BMI < 25 kg/m2), age- and sex-matched controls selected from the same population were studied. Height, weight, waist circumference, as well as blood pressure were measured according to a standard protocol. BMI at age 25 y was calculated on the basis of current height and reported weight at age 25 y Biochemical measurements included fasting glucose, triglycerides, high-density lipoprotein cholesterol and insulin. DNA analysis was conducted by PCR and gel electrophoresis. RESULTS: Age and gender distribution were similar in obese and normal weight participants. The percentage of people with the Pro12Ala mutation was not significantly different in obese or normal weight participants (20% and 15%, respectively; P = 0.32). Conversely, in obese participants with obesity starting in early adulthood (ie with BMI at age 25 above 26.9kg/m2 which represents the median of the whole obese group), the Pro12Ala mutation was observed significantly more frequently than in the normal weight controls (29% vs 15%; chi square = 4.5, P < 0.05; odds ratio 2.4; 95% CI 1.03-5.36). No association of the Pro12Ala variant with any of the component of the metabolic syndrome measured in the study was observed in either obese, juvenile obese or normal weight participants. CONCLUSIONS: Results of this study indicate that the Pro12Ala mutation does not play a major role as a determinant of severe obesity and/or features of the metabolic syndrome in the general population. However, this mutation may be of greater importance as a contributor to early onset obesity.

Retinol and retinol-binding protein: gut integrity and circulating immunoglobulins.

Vitamin A (retinol) is required to maintain immunity and epithelial turnover and is a key micronutrient needed for combating infection. Vitamin A actions on the immune system are diverse and cannot be accounted for by a single effect or mechanism. The actions of retinol in maintaining gut integrity in humans and immunoglobulin levels in mice was investigated. For 30 children, performance on the lactulose/mannitol test, a test commonly used to assess intestinal barrier function, was inversely correlated (P=.012) with serum retinol concentrations. Thus, children with lower serum retinol, and presumably poorer vitamin A nutritional status, are more likely to have impaired intestinal integrity. Knockout mice that have impairments in plasma retinol transport have circulating immunoglobulin levels that are half those observed in matched wild type mice. No differences were observed in B and T cell populations present in spleen, thymus, and bone marrow.

3,5-diiodo-L-thyronine regulates glucose-6-phosphate dehydrogenase activity in the rat.

Thyroid hormones influence the activity of lipogenic enzymes such as malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PD). The effect of T3 on ME is exerted at the transcriptional level, but it is unclear if its effect on G6PD is also nuclear mediated. Furthermore, other iodothyronines that have been shown to possess biological activity (such as diiodothyronines) could contribute to this enzyme's regulation. In this study the effects of 3,5-diiodothyronine (T2) on the aforementioned enzymes were examined and compared with those of T3. Rats made hypothyroid by propylthiouracil and iopanoic acid treatment were used throughout. Enzyme activities were determined spectrophotometrically, and G6PD messenger RNA (mRNA) expression was analyzed by Northern blotting using a human G6PD complementary DNA probe. Injections of T2 to hypothyroid animals significantly enhanced the activity of both enzymes. The effect of T2 on ME was nuclear mediated and mimicked the effect of T3. The effects of T2 and T3 on G6PD differed. Injection of T3 into hypothyroid rats induced an increase in both enzyme activity and G6PD mRNA expression, indicating a nuclear-mediated effect. The effect of T2 on G6PD activity, on the other hand, was not nuclear mediated. The injection of T2 into hypothyroid animals did not change G6PD mRNA expression, and the strong increase in the enzyme's activity (from +70% to +300%) was unaffected by simultaneous injection of protein synthesis inhibitors. As the lowest dose of 1 microg T2/100 g BW affects G6PD activity 3-5 times more than the same dose of T3, these data provide the first evidence that T2 is a factor capable of regulating G6PD activity.