P14.55 FOXP2 as a prognostic biomarker in glioblastoma

Background

FOXP2 is an essential transcription factor for the development of language. It has also a high expression in some neosplasm, with a differential role as a prognostic biomarker. However, the role of FOXP2 in glioblastoma (GBM) has not been studied until now.

AIM

To study the role of FOXP2 as a prognostic biomarker in GBM.

METHODS

This is a retrospective observational case series study in which the expression of FOXP2 has been analyzed at the protein level (immunochemistry, in probes from patients treated in our Center) and at the level of mRNA (RNAseq, in a cohort of GBM patients from The Cancer Genome Atlas [TCGA] database). The expression of some target genes of FOXP2 (RNAseq) has also been studied in the TCGA cohort. Survival analysis using Log-Rank test and COX regression (uni- and multivariate) have been used. The analysis included also other molecular and clinical features of interest in GBM.

RESULTS

At protein level, FOXP2 was expressed in more than 90% of patients, with a mean positivity of 28.33% (SD=32.29). At mRNA level, FOXP2 was expressed in 79% of patients, with a mean expression of 29.72 RPKM (SD=63.77). Patients with a high expression of FOXP2 at protein level showed a worse prognosis than those patients with low expression in both, progression free survival (HR=1.711; p=.034) and overall survival (HR=1.809; p=.014). These associations maintained their significance in multivariate analysis. Nevertheless, no prognostic association was found with mRNA FOXP2 expression. Interestingly, FOXP2 target genes did not show the expected regulation described in previous works. Some of these genes has been involved in oncogenesis.

CONCLUSION

FOXP2 is expressed in many GBM patients. Higher expression of FOXP2 protein may be associated with a worse prognosis, but this has not been confirmed at mRNA. Furthermore, a dysregulation of FOXP2 function may be present in tumoral cells.

Correction: DUB3 and USP7 de-ubiquitinating enzymes control replication inhibitor Geminin: molecular characterization and associations with breast cancer

The final sentence of the Acknowledgements should be as follows: This work was supported by grants from Instituto de Salud Carlos III (BA15/00092), Spanish Ministry of Economy and Competitiveness/EU-ERDF (SAF2016-80626-R, SAF2013-49149-R, BFU2014-51672-REDC), Fundación CajaCanarias (AP2015/008) to RF, and the Australian National Health and Medical Research (NHMRC program grant to SRL and KKK (APP1017028).

Deciphering Tacrolimus-Induced Toxicity in Pancreatic β Cells

β Cell transcription factors such as forkhead box protein O1 (FoxO1), v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), pancreatic and duodenal homeobox 1, and neuronal differentiation 1, are dysfunctional in type 2 diabetes mellitus (T2DM). Posttransplant diabetes mellitus resembles T2DM and reflects interaction between pretransplant insulin resistance and immunosuppressants, mainly calcineurin inhibitors (CNIs). We evaluated the effect of tacrolimus (TAC), cyclosporine A (CsA), and metabolic stressors (glucose plus palmitate) on insulinoma β cells in vitro and in pancreata of obese and lean Zucker rats. Cells were cultured for 5 days with 100 μM palmitate and 22 mM glucose; CsA (250 ng/mL) or TAC (15 ng/mL) were added in the last 48 h. Glucose plus palmitate increased nuclear FoxO1 and decreased nuclear MafA. TAC in addition to glucose plus palmitate magnified these changes in nuclear factors, whereas CsA did not. In addition to glucose plus palmitate, both drugs reduced insulin content, and TAC also affected insulin secretion. TAC withdrawal or conversion to CsA restored these changes. Similar results were observed in pancreata of obese animals on CNIs. TAC and CsA, in addition to glucose plus palmitate, induced comparable inhibition of calcineurin and nuclear factor of activated T cells (NFAT); therefore, TAC potentiates glucolipotoxicity in β cells, possibly by sharing common pathways of β cell dysfunction. TAC-induced β cell dysfunction is potentially reversible. Inhibition of the calcineurin-NFAT pathway may contribute to the diabetogenic effect of CNIs but does not explain the stronger effect of TAC compared with CsA.

DUB3 and USP7 de-ubiquitinating enzymes control replication inhibitor Geminin: molecular characterization and associations with breast cancer

This corrects the article DOI: 10.1038/onc.2017.21.

DUB3 and USP7 de-ubiquitinating enzymes control replication inhibitor Geminin: molecular characterization and associations with breast cancer

Correct control of DNA replication is crucial to maintain genomic stability in dividing cells. Inappropriate re-licensing of replicated origins is associated with chromosomal instability (CIN), a hallmark of cancer progression that at the same time provides potential opportunities for therapeutic intervention. Geminin is a critical inhibitor of the DNA replication licensing factor Cdt1. To properly achieve its functions, Geminin levels are tightly regulated through the cell cycle by ubiquitin-dependent proteasomal degradation, but the de-ubiquitinating enzymes (DUBs) involved had not been identified. Here we report that DUB3 and USP7 control human Geminin. Overexpression of either DUB3 or USP7 increases Geminin levels through reduced ubiquitination. Conversely, depletion of DUB3 or USP7 reduces Geminin levels, and DUB3 knockdown increases re-replication events, analogous to the effect of Geminin depletion. In exploring potential clinical implications, we found that USP7 and Geminin are strongly correlated in a cohort of invasive breast cancers (P<1.01E-08). As expected, Geminin expression is highly prognostic. Interestingly, we found a non-monotonic relationship between USP7 and breast cancer-specific survival, with both very low or high levels of USP7 associated with poor outcome, independent of estrogen receptor status. Altogether, our data identify DUB3 and USP7 as factors that regulate DNA replication by controlling Geminin protein stability, and suggest that USP7 may be involved in Geminin dysregulation during breast cancer progression.

Adrenocortical carcinoma, an unusual extracolonic tumor associated with Lynch II syndrome

Lynch syndrome (LS) is an autosomal dominant condition that predisposes to colorectal cancer and specific other tumors. Extracolonic tumors occur mainly in the endometrium, stomach, ovary, small intestine and urinary tract. The presence of rare tumors in patients belonging to families who have Lynch syndrome is always interesting, because the question arises whether these tumors should be considered as a coincidence or are related with the syndrome. In this last case, they are also the result of the defect in the mismatch repair system, opening the possibility of extending the tumor spectrum associated with the syndrome. Here we describe a patient from a Lynch syndrome family with a germline mutation c.2063T>G (p.M688R) in the MSH2 gene, who developed an adrenal cortical carcinoma, a tumor not usually associated with LS. We analyzed the adrenocortical tumour for microsatellite instability (MSI), LOH and the presence of the germline c.2063T>G (M688R) mutation. The adrenal cortical carcinoma showed the MSH2 mutation, loss of heterozygosity of the normal allele in the MSH2 gene and loss of immunohistochemical expression for MSH2 protein, but no microsatellite instability. Additionally, the adrenal cortical carcinoma did not harbour a TP53 mutation. The molecular study indicates that this adrenal cortical cancer is probably due to the mismatch repair defect.

Localization and gestation-dependent pattern of corticotrophin-releasing factor receptor subtypes in ovine fetal distal colon

Meconium passage is frequently observed in association with feto-maternal stress factors such as hypoxia and infection, but the triggering mechanism is unknown. We hypothesize that differential regulation of corticotrophin-releasing factor (CRF) receptors during gestation play an important role in determining the susceptibilities of the fetus to stress-induced in utero meconium passage at term. We examined the innervation patterns of CRF-receptor type 1 (CRF-R1), a stimulator of gastrointestinal motility and CRF-receptor type II (CRF-R2), an inhibitor of gastrointestinal motility in ovine fetal distal colonic segments from very preterm to term gestation. Both CRF-R1 and CRF-R2 receptors were present in muscularis mucosa as well as in longitudinal and circular smooth muscle layers in fetal distal colonic segments at all gestational ages. Quantitative image analysis indicated a 42% increase in CRF-R1 receptor immunoreactivity in muscularis mucosa and a 30% in longitudinal smooth muscle layers from very preterm to term. In contrast, CRF-R2 receptor immunoreactivity in muscularis mucosa as well as in longitudinal and circular smooth muscle layers decreased by 38%, 55% and 51%, respectively, at term. The percentage of enteric ganglia and the number of enteric neurons expressing CRF-R1 receptors were high at term. Western blot analysis identified 235 and 50 kDa molecular species of CRF-R1 receptors and 37 and 28 kDa molecular species of CRF-R2 receptors. In summary, we speculate that downregulation of CRF-R2 receptor abundance with concurrent increases in CRF-R1 receptor levels in myenteric-smooth muscle unit with advancing gestation sensitizes the colonic motility responses to stressors.

Changes in the epidemiology of meticillin-resistant Staphylococcus aureus associated with the emergence of EMRSA-16 at a university hospital

This study investigated the molecular epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in the University Hospital of the Canary Islands (HUC) in order to evaluate epidemiological changes over a six-year period. Clinical and epidemiological data were collected between May 2000 and December 2003, and isolates were subjected to pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), SCCmec typing and spa typing. Since 2000, the rate of MRSA infections has increased at the HUC, coinciding with the emergence and spread of the EMRSA-16 clone (ST36-MRSA-II) and replacement of the Iberian clone (ST247-MRSA-I). Genotypic changes were associated with changes in the epidemiological profile. The mean age and proportion of patients over 60 years old (P=0.01) and the proportion of respiratory infections (P=0.001) increased significantly. Gentamicin and tetracycline susceptibility of MRSA isolates increased (P<0.001) following the emergence of EMRSA-16. Combining PFGE, SCCmec and MLST has been instrumental in understanding these changes and defining the clones circulating in the HUC patient population.

Presentation and role of transplantation in adult patients with type 1 primary hyperoxaluria and the I244T AGXT mutation: Single-center experience

Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder characterized by allelic and clinical heterogeneity. We aim to describe the presentation and full single-center experience of the management of PH1 patients bearing the mutation described in our community (I244T mutation+polymorphism P11L). Since 1983, 12 patients with recurrent renal lithiasis have been diagnosed with PH1 and renal failure in the Canary Islands, Spain. Diagnostic confirmation was based on the presence of oxalosis in undecalcified bone or kidney allograft biopsy, reduced alanine:glyoxylate aminotransferase activity in liver biopsy, and blood DNA analysis. Patients underwent different treatment modalities depending on individual clinical circumstances and therapeutic possibilities at the time of diagnosis: hemodialysis, isolated kidney, simultaneous liver-kidney, or pre-emptive liver transplantation. In all cases, the presentation of advanced renal disease was relatively late (>13 years) and no cases were reported during lactancy or childhood. The eight patients treated with hemodialysis or isolated kidney transplantation showed unfavorable evolution leading to death over a variable period of time. In contrast, the four patients undergoing liver transplantation (three liver+kidney and one pre-emptive liver alone) showed favorable long-term allograft and patient survival (up to 12 years follow-up). In conclusion, in this PH1 population, all bearing the I244T mutation, the development of end-stage renal disease was distinctive during late adolescence or adulthood. Our long-term results support pre-emptive liver transplantation at early stages of renal failure, and kidney-liver transplantation for those with advanced renal disease.

Role of apolipoprotein E epsilon 4 allele on chronic allograft nephropathy after renal transplantation

Lipid abnormalities may contribute to chronic allograft nephropathy (CAN). Apolipoprotein E (ApoE) gene polymorphism regulates lipoprotein metabolism, but little is known about an association between CAN and this polymorphism. The ApoE gene (E3/E4) polymorphism was typed by PCR assay (99 E3/E3, 28 E3/E4, 1 E4/E4) on 128 consecutive renal transplant patients with functioning grafts for more than 3 years (6.7 +/- 2.8 years). Twenty-eight patients with histological CAN were compared with 100 patients who had no clinical evidence of chronic rejection (no proteinuria and sCr < 2.5 mg%). As expected, univariate analysis revealed that patients with CAN experienced a greater acute rejection rate (78% vs 21%; P=.001), a higher serum creatinine (3.6 +/- 1.7 vs 1.4 +/- 0.5 mg%; P=.0001), and an older organ donor (43 +/- 20 vs 29 +/- 13 years; P=.0001). The lipid profiles (total cholesterol and triglycerides levels) were similar in both groups with 60% in each group receiving anti-lipemic drugs. Interestingly, the ApoE epsilon 4 allele was overrepresented in the group with CAN (39% vs 17%, P=.019). Logistic regression analysis showed that the epsilon 4 allele was an independent predictor of CAN (OR: 3.4; CI 95%: 1.07 to 11; P=.040) as were donor age and acute rejection episodes. In conclusion, an interaction between risk factors and genetic factors may determine CAN in this population. This finding may help to target prophylactic interventions in these recipients.

Tumour spectrum of non-polyposis colorectal cancer (Lynch syndrome) on the island of Tenerife and influence of insularity on the clinical manifestations

Colorectal cancer is a complex disease from a genetic point of view because both genetic and environmental factors interact in its development. Only familial adenomatous polyposis (FAP) follows mendelian genetics, in that mutations of the APC gene lead to development of the tumours. Lynch syndrome is the most frequent form of hereditary colorectal cancer and appears to be associated with other types of extracolonic cancers. The genetic basis has been established as a defect in DNA mismatch repair genes, and there is genetic heterogeneity due to the involvement of several genes in this system. Germinal mutations in these genes predispose to appearance of the syndrome. The aim of this study is to describe the tumoral spectrum of 10 families, comprising a total of 488 individuals, from the island of Tenerife (Canary Islands) and to assess whether the geographical isolation of this population has changed any features of the tumoral spectrum of the syndrome in comparison with studies that cover larger geographical areas with more genetic exchange. From our results we can conclude that the genetic drift and consanguinity in this population with a demographic history of isolation did not significantly alter the tumoral spectrum of the syndrome. Our data confirm that families affected by Lynch syndrome are a high-risk population and should be closely monitored, since their careful supervision has been shown to be useful in preventing cancer. We also emphasize the importance of developing a complete family history that permits these families to be identified together with a mutational screening of DNA mismatch repair genes (mainly MLH1 and MSH2 genes) with the aim of a possible identification of members of a family that should be carefully monitored (the carriers of germline mutations in these genes), whereas the remaining members, originally, are no more at risk than the general population.

Primary hyperoxaluria type 1 in the Canary Islands: a conformational disease due to I244T mutation in the P11L-containing alanine:glyoxylate aminotransferase

Primary hyperoxaluria type 1 (PH1) is an inborn error of metabolism resulting from a deficiency of alanine:glyoxylate aminotransferase (AGXT; EC 2.6.1.44). Most of the PH1 alleles detected in the Canary Islands carry the Ile-244 --> Thr (I244T) mutation in the AGXT gene, with 14 of 16 patients homozygous for this mutation. Four polymorphisms within AGXT and regional microsatellites also were shared in their haplotypes (AGXT*LTM), consistent with a founder effect. The consequences of these amino acid changes were investigated. Although I244T alone did not affect AGXT activity or subcellular localization, when present in the same protein molecule as Leu-11 --> Pro (L11P), it resulted in loss of enzymatic activity in soluble cell extracts. Like its normal counterpart, the AGXT*LTM protein was present in the peroxisomes but it was insoluble in detergent-free buffers. The polymorphism L11P behaved as an intragenic modifier of the I244T mutation, with the resulting protein undergoing stable interaction with molecular chaperones and aggregation. This aggregation was temperature-sensitive. AGXT*LTM expressed in Escherichia coli, as a GST-fusion protein, and in insect cells could be purified and retained enzymatic activity. Among various chemical chaperones tested in cell culture, betaine substantially improved the solubility of the mutant protein and the enzymatic activity in cell lysates. In summary, I244T, the second most common mutation responsible for PH1, is a protein conformational disease that may benefit from new therapies with pharmacological chaperones or small molecules to minimize protein aggregation.

Epidemiologic genotyping of methicillin-resistant Staphylococcus aureus by pulsed-field gel electrophoresis at a university hospital and comparison with antibiotyping and protein A and coagulase gene polymorphisms

A total of 124 methicillin-resistant Staphylococcus aureus (MRSA) isolates were ascertained at the University Hospital of the Canary Islands between January 1997 and April 2000. Genotyping included pulsed-field gel electrophoresis (PFGE) (SmaI digestion) and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis for the coagulase (coa) and protein A (spa) genes. Antibiotic resistance was the main phenotypic marker correlated with genotyping results. Three main PFGE types were detected: A (with 12 subtypes), B (with 2 subtypes), and C. PFGE type A1 was the most commonly found (61% of isolates) and the one responsible for all the epidemic outbreaks. Other genetics markers used (coa and spa RFLPs) were significantly correlated with the PFGE types detected (P < 0.001). These PCR-RFLP assays were useful as molecular markers for a quick, preliminary study of MRSA outbreaks.

Colocalization of tyrosine hydroxylase and GAD65 mRNA in mesostriatal neurons

Although dopamine has been considered as the only neurotransmitter in the nigrostriatal pathway, studies carried out in the last two decades have suggested the existence of a nondopaminergic nigrostriatal projection, and more recently, gamma-aminobutyric acid (GABA) has been identified as its neurotransmitter. In this study, we used the combination of immunocytochemistry for tyrosine hydroxylase (TH; a marker of dopaminergic neurons), in situ hybridization (ISH) for two different isoforms of glutamic acid decarboxylase (GAD65 and GAD67, the rate-limiting enzyme in GABA synthesis) and retrograde tracing techniques to investigate the possible existence of nigrostriatal neurons containing both neurotransmitters (dopamine and GABA) in the rat. Our results revealed that approximately 10% of mesostriatal dopaminergic neurons, most of them lying in the medial region of the substantia nigra pars compacta (SNC) and neighbouring A10 region, contain GAD65 mRNA. These findings reveal a third nigrostriatal pathway formed by dopaminergic/GABAergic neurons. Contrasting with the idea that in the basal ganglia, dopamine and GABA are released from different cell populations, the results suggest a more complex dopamine/GABA interaction than previously assumed, probably including cotransmission.

Regression of left ventricular hypertrophy by lisinopril after renal transplantation: role of ACE gene polymorphism

BACKGROUND

Cardiac complications are the main cause of death in renal transplantation (RT), and left ventricular hypertrophy (LVH) may play an important role in these patients. The unfavorable genotype of the angiotensin-converting enzyme (ACE) gene has been associated with cardiovascular disease, including LVH. ACE inhibitors (ACEIs) reduce LVH, but little is known about the effects of ACEIs on LVH in RT patients with different insertion/deletion (I/D) genotypes of the ACE gene.

METHODS

We prospectively studied 57 stable nondiabetic RT patients with hypertension and echocardiographic LVH as well as a functional graft for 69.5 +/- 5.6 months. Patients randomly received either lisinopril 10 mg/day (group A, N = 29; 5 were excluded due to reversible acute renal failure) or placebo (group B, N = 28) for 12 months. Echocardiography (M-mode, 2-B, and color flow Doppler) was performed at baseline and 6 and 12 months later by the same examiner without previous knowledge of the genetic typing. The ACE genotype (I or D alleles) was ascertained by polymerase chain reaction (PCR; group A, DD = 10 and ID/II = 14; group B, DD = 15 and ID/II = 13).

RESULTS

All patients maintained a good renal function (serum creatinine <2.5 mg/dL) during the follow-up and both groups received a similar proportion of antihypertensive drugs (beta-blockers 83 vs. 79%; Ca antagonists 66 vs. 68%; alpha1-adrenoreceptor antagonists 50 vs. 67%) during the study. As expected, mean arterial blood pressure and hemoglobin levels showed a higher percentage reduction in group A versus group B (-4 +/- 2.8 vs. 2.1 +/- 2.6%, P = 0.07, and -11.5 +/- 1.5 vs. -0.5 +/- 2.3%, P < 0.01, respectively). Group A patients showed a significantly higher decrement in LV mass index (LVMI) than group B at the end of follow-up, after adjusting for age, baseline LVMI, time after grafting and changes in systolic blood pressure, renal function, and hemoglobin levels (group A, -9.5 +/- 3.5% vs. group B, 3 +/- 3.2%, P < 0.05). As a result, 46% of group A and only 7% of group B patients showed a reduction of LVMI >/=15% (P < 0.01). The beneficial effect of lisinopril on LVMI reduction was more evident in DD patients (placebo DD, 8.4 +/- 4.1% vs. lisinopril DD, -7.2 +/- 5.3, P < 0.05), and a trend was observed in patients with other genotypes (placebo ID/II, 2.8 +/- 5.4% vs. lisinopril ID/II, -11.4 +/- 5%, P = 0.33).

CONCLUSIONS

Lisinopril decreases LVM in renal transplant patients with hypertension and LVH, and the ACE gene polymorphism may predict the beneficial effect of this therapy. This finding may be important in targeting prophylactic interventions in this population.

The distribution of two different vitamin D receptor polymorphisms (BsmI and start codon) in primary hyperparathyroidism

INTRODUCTION

The bb genotype of the BsmI polymorphism of the vitamin D receptor (VDR) is more common in primary hyperparathyroidism (HPT) than in the general population in Swedish and German women. However, little is known about the association of HPT with the start codon polymorphism of the VDR (defined by FokI).

OBJECTIVE

To study the distribution of the VDR genotypes in a group of women with HPT compared with a control group. The bone mineral density (BMD) of different genotypes was also investigated.

METHODS

VDR alleles were typed by polymerase chain reaction (PCR) assay around the polymorphic BsmI or FokI restriction sites in 67 control women (48.5 +/- 10 years) and 53 women with HPT (61.4 +/- 11 years). They were all Caucasian and born in the Canary Islands. Lumbar and proximal femur BMDs were measured by dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT).

RESULTS

The 'bb' genotype was equally frequent in controls and HPT subjects (46.3 and 45.3%, respectively). There was a trend towards a lower prevalence of the FF genotype amongst women with HPT as compared with controls (41.5 vs. 57.1%; P = 0.09). BMD was lower in patients with HPT compared with controls in the lumbar spine and the proximal femur.

CONCLUSIONS

The association of the BsmI polymorphism of the VDR gene with HPT is not applicable to all geographical areas. In Canarian postmenopausal women suffering from HPT, VDR genotype distribution is similar to that found in controls. A possible association of HPT with the FokI polymorphism deserves further investigation.

The PlA2 polymorphism of the platelet glycoprotein IIIA gene as a risk factor for acute renal allograft rejection

Glycoprotein IIIa/IIb is a membrane receptor for fibrinogen and von Willebrand factor that plays an important role in platelet aggregation. The beta integrin chain of this receptor, GPIIIa, is polymorphic, and the allele known as PlA2 has been associated with coronary thrombosis. The GPIIIa genotype of a cohort of 119 consecutive renal allograft recipients (46.3 +/- 13 yr; 85 M/34 F; 24.4% diabetic patients) was determined by PCR-restriction fragment length polymorphism, and those patients were followed for at least 12 mo. From 119 patients with at least 1 yr of follow-up, those who suffered an acute rejection (n = 52) showed a lower proportion of HLA-DR beta1 identity with the donor (7.7% versus 23.9%; P = 0.03), a higher proportion of cytomegalovirus-positive (CMV+) donors/CMV- recipients (21% versus 7.5%; P = 0.05), and the PlA2 allele was more frequent (48.1% versus 26.9%; P = 0.02) compared with patients free of acute rejection (n = 67). No other variable was associated with acute rejection in the univariate analysis. The impact of the three above-mentioned significant variables on acute rejection was analyzed by stepwise logistic regression. The presence of the PlA2 allele yielded an odds ratio of 2.75 (95% confidence interval, 1.01 to 7.93) and an HLA-DR beta1 identity of 0.2 (95% confidence interval, 0.06 to 0.99) for suffering an acute rejection episode. In addition, the serum creatinine at discharge was higher in PlA2-positive versus PlA2-negative patients (2.2 +/- 1.6 versus 1.5 +/- 0.6 mg/dl, respectively; P = 0.01), and the prevalence of proteinuria >1.5 g/d 1 yr after transplantation was significantly higher among patients showing the PlA2 allele (16% versus 3%; P = 0.02). Finally, in the entire cohort of patients, the 2-yr graft survival was significantly lower in PlA2-positive (n = 43) compared with PlA2-negative (n = 76) patients (85.7% versus 97.2%; P = 0.015). No differences were found in patient survival (95.2% versus 98.7%, respectively). Proportional hazards regression analysis (Cox regression model) confirmed that serum creatinine level at discharge is the best predictor of allograft survival, followed by CMV status, delayed graft function, and the glycoprotein IIIa/IIb genotype. The PlA2 polymorphism is an independent risk factor for acute renal graft rejection, affecting short-term graft survival. Future studies aimed at preventing the hemostatic imbalance favoring platelet aggregation associated with this polymorphism may be important in preventing acute rejection and its impact on chronic rejection.

Mouse p73 gene maps to the distal part of chromosome 4 and might be involved in the progression of gamma-radiation-induced T-cell lymphomas

We have isolated and sequenced a DNA fragment of about 12 kb that comprises exons 5-14 of the mouse p73 gene. We have identified four polymorphic markers, and one of them has been used to genetically map p73 to the distal part of chromosome 4. Previously, we have reported that gamma-radiation-induced T-cell lymphomas undergo frequent loss of heterozygosity around marker D4Mit205b at the distal part of chromosome 4. Based on this, we have performed loss of heterozygosity analysis in a set of T-cell lymphomas, and we have found allelic losses of p73 in 32.6% (16 of 49) of the tumors analyzed. Interestingly, allelic losses occur concurrently at both p73 and D4Mit205b, thus suggesting that p73 could be specifically inactivated in radiation-induced T-cell lymphomas.

Vitamin D receptor gene polymorphisms, bone mass, bone loss and prevalence of vertebral fracture: differences in postmenopausal women and men

Bone mineral density (BMD), the major determinant of fracture risk, is under strong genetic control. Although polymorphisms of the vitamin D receptor (VDR) gene have been suggested to account for some of the genetic variation in bone mass, the influence of VDR genotypes on osteoporosis remains controversial. Previous published studies have focused mainly on women, but the pattern of response in men has not been determined. Using the BsmI restriction enzyme, we studied the influence of the different VDR genotypes on bone mass, bone loss and the prevalence of vertebral fractures in a population-based sample of both sexes (n = 326). BMD was measured at the lumbar spine and femoral neck, with a 4-year interval, using dual-energy X-ray absorptiometry. Vertebral fractures were assessed by two lateral radiographs at the beginning and end of the study. The prevalence of the three possible VDR genotypes was similar to those in other Caucasian populations and no differences were found between men and women. Women with the favorable bb genotype showed significantly higher BMD values at the lumbar spine and femoral neck, and a positive rate of BMD change at the femoral neck compared with women with the BB and Bb genotypes. Moreover, women with the bb genotype showed a trend toward a lower prevalence and incidence of vertebral fractures (p = 0.07). We have not found any differences between VDR genotypes in men. In conclusion, VDR gene polymorphisms are related to bone mass and bone loss in women; also a trend in the prevalence of vertebral fractures was observed in postmenopausal women but not in men.

[Genetic polymorphism of vitamin D receptor and osteoporosis]

BACKGROUND

Genetic factors condition an important part of bone mass. The role of vitamin D receptor polymorphism (VDR) as genetic marker of osteoporosis is a matter of discussion. We have studied the possible influence of VDR on bone remodelling, calciotropic hormones, on the presence of osteoporosis and osteoporotic bone fractures. PATIENTS, CONTROL POPULATION AND METHODS: A case-control study. We have studied a total of 127 postmenopausal Canarian women from Canary Islands, Spain; 66 healthy controls and 61 with the diagnosis of osteoporosis, which was made by clinical, radiological and densitometric criteria. 17 osteoporotic women have had a fracture: Colles, hip or vertebral (spinal deformity index) fracture. VDR were determined by PCR directed to demonstrate the presence (b) or absence (B) of a restriction target for Bsml in intron 7. We analyzed some biochemical markers of bone remodelling: serum levels of alkaline phosphatase, tartrate resistant acid phosphatase and urine ratios of calcium/creatinine and hydroxyproline/creatinine. We also determined calciotropic hormones: parathyroid hormone and calcitonin. Bone mass was measured by DEXA and TC.

RESULTS

There were no significant differences in either biochemical bone remodelling markers or in bone mass between the three genotypes: bb, Bb and BB, either in controls or in osteoporotic women with the exception of alkaline phosphatase which had a significative increase compared to control in women with unfavorable alleles distribution (bB and BB). Distribution of genotypes was similar between controls and osteoporotic women, with or without fractures.

CONCLUSIONS

In Canarian women, VDR genotype is not associated with changes in biochemical markers of bone remodelling or in bone mass or with the presence of osteoporosis or osteoporotic fractures.

Identification and structural and functional characterization of human enamelysin (MMP-20)

A cDNA encoding a new human matrix metalloproteinase (MMP) has been cloned from RNA prepared from odontoblastic cells. The open reading frame of the cloned cDNA codes for a polypeptide of 483 amino acids and is extensively similar to the sequence of recently described porcine enamelysin, suggesting that the isolated cDNA codes for the human homologue of this enzyme. Human enamelysin (MMP-20) has a domain organization similar to other MMPs, including a signal peptide, a prodomain with the conserved motif PRCGVPD involved in maintaining enzyme latency, a catalytic domain with a Zn-binding site, and a COOH-terminal fragment similar to the sequence of hemopexin. The calculated molecular mass of human enamelysin is about 54 kDa, which is similar to that of collagenases or stromelysins. However, this human MMP lacks a series of structural features distinctive of these subfamilies of MMPs. The full-length human enamelysin cDNA has been expressed in Escherichia coli, and the purified and refolded recombinant protein is able to degrade synthetic peptides used as substrates of MMPs, confirming that human enamelysin belongs to this family of proteases. Furthermore, the recombinant human enamelysin is able to degrade amelogenin, the major protein component of the enamel matrix. On the basis of its degrading activity on amelogenin, and its highly restricted expression to dental tissues, we suggest that human enamelysin plays a central role in the process of tooth enamel formation. Finally, we have found that the human enamelysin gene (MMP-20) maps to chromosome 11q22, clustered to at least seven other members of the MMP gene family.

Expression of steroid sulfatase during embryogenesis

Neurosteroids are steroids that are synthesized de novo in the brain from cholesterol and, in general, mediate their effects through ion-gated channel receptors such as gamma-aminobutyric acidA (GABA[A]) and N-methyl-D-aspartate receptors rather than through classical nuclear steroid hormone receptors. Steroid hormones are known to exist not only as free compounds, but also as sulfated derivatives. Pharmacological studies indicate that unconjugated and sulfated steroids, such as pregnenolone and pregnenolone sulfate, may have opposite effects on GABA(A) receptors. Thus, pregnenolone acts as a potent positive allosteric modulator of gamma-aminobutyric acid action at GABA(A )receptors, whereas pregnenolone sulfate acts as a potent negative modulator. Recent experiments also suggest that dehydroepiandrosterone and dehydroepiandrosterone sulfate may have distinct effects on growth of neurites from embryonic neocortical neurons in vitro. Thus, regulation of steroid sulfation may have profound behavioral and morphological effects on the nervous system. We, therefore, studied the developmental expression of the enzyme steroid sulfatase (STS), which converts sulfated steroids to free steroids. By in situ hybridization, STS messenger RNA was expressed in the embryonic mouse cortex, hindbrain, and thalamus during the last third of gestation. The sites of expression of STS were similar to those of P450c17, suggesting that these two enzymes may have concerted actions in similar functional processes.

Prediction of left ventricular mass changes after renal transplantation by polymorphism of the angiotensin-converting-enzyme gene

Cardiac complications are the main cause of death in renal transplant patients and left ventricular hypertrophy (LVH) may play a determinant role. An association between the insertion-deletion polymorphism of the angiotensin-converting enzyme (ACE) gene and LVH has been reported in adults. However, little is known about the genetic influence on left ventricular mass changes after renal transplantation, where unique environmental factors, such as cyclosporine A (CsA) and prednisone treatment concur. In fact, CsA treatment has recently been associated with the development of LVH. We prospectively determined the changes on cardiac structure and function, assessed by echocardiographic criteria, in 38 consecutive nondiabetic adults who received a cadaveric renal allograft. They were treated with cyclosporine and prednisone and maintained a good renal function during the follow-up. Echocardiographic studies (M-mode, 2-B and color flow Doppler) were performed without previous knowledge of the genetic typing, at the time of transplantation, and 6 and 12 months later. ACE alleles were typed using a PCR-based assay developed to ascertain the presence of an insertion (I)-deletion (D) polymorphism in intron 16 of the ACE gene. Patients with the so-called "unfavorable" DD genotype (N = 16) were compared with the ID or II genotypes (N = 22). The baseline left ventricular mass index was similar in patients with or without the unfavorable DD genotype (X +/- SE; 166.6 +/- 10.4 vs. 181.3 +/- 9 g/m2, respectively) and a similar proportion fulfilled the criteria of LVH (88% vs. 82%, respectively). The mean percent increase of the left ventricular mass index 12 months after renal transplantation was significantly higher in patients with the DD genotype compared to those with other genotypes (21.3 +/- 7.9 vs. -0.08 +/- 4.9%, respectively; P < 0.05). As a result, 94% of DD patients showed LVH at the end of the follow-up, while 68% of the ID or II patients had LVH (P < 0.05). In addition, the left ventricular ejection fraction significantly increased only in ID or II patients 12 months after transplantation with respect to baseline (ID/II patients, 70.4 +/- 1.5 vs. 63.7 +/- 1.8%; P < 0.05; DD patients, 68.3 +/- 2.1 vs. 63.3 +/- 2.9%). The deleterious effect of the DD genotype was independent of blood pressure, biochemical parameters, weight gain, and cumulative steroids dosages or cyclosporine levels. In conclusion, genetic factors determine the changes on cardiac structure and function after renal transplantation. The presence of the DD genotype of the ACE gene is a marker associated with an elevated risk of LVH in this population.

Constitutive NOS isoforms account for gastric mucosal NO overproduction in uremic rats

To study whether renal failure enhances gastric mucosal nitric oxide (NO) formation in the rat, we measured 1) in vivo NO concentration and 2) NO synthase (NOS) activity, content, and mRNA expression in gastric mucosal homogenates of uremic and sham-operated anesthetized rats. Gastric mucosal NO release was measured by an electrochemical technique. NOS content was analyzed by Western immunoblots, using specific monoclonal antibodies. Constitutive (Ca2+ dependent; cNOS) and inducible (Ca2+ independent; iNOS) NOS activities were assayed by following the conversion of L-[U-14C]arginine to [U-14C]citrulline. mRNA expression for the constitutive neuronal (ncNOS), endothelial (ecNOS), and iNOS isoforms was determined by reverse transcription-polymerase chain reaction. Under basal conditions, gastric mucosal NO concentration was significantly greater in uremic compared with control rats. This was accompanied by significantly greater gastric mucosal cNOS activity in uremic rats than in control rats, whereas no differences were observed in iNOS activity between both groups of animals. Moreover, total enzyme content and the levels of gastric mucosal mRNA expression for ncNOS, ecNOS, and iNOS showed no significant differences between uremic and sham-operated rats. These data confirm that, in uremic rats, enhanced Ca2+-dependent NOS activity is responsible for gastric mucosal NO overproduction and suggest that the main regulatory mechanism is not transcriptional but translational and/or posttranslational in nature.

High phosphorus diet increases preproPTH mRNA independent of calcium and calcitriol in normal rats

Phosphorus retention favors secondary hyperparathyroidism by decreasing calcitriol synthesis and serum calcium levels. However, a direct effect of high extracellular phosphorus on parathyroid (PTH) function, gene expression, and cell proliferation is still controversial. Normal rats were fed standard (St; 0.6% calcium, 0.6% phosphorus) or high phosphate (HP) diet (0.6% calcium, 1.2% phosphorus) for 18 days. To rule out transient decreases in serum calcium or calcitriol levels, sets of animals were sacrificed at different time periods after the last feeding (2, 4, 8, 12 or 24 hr). The HP diet led to hyperphosphatemia and secondary hyperparathyroidism and maximum differences in PTH levels were observed eight hours after feeding (St 29.4 +/- 15 vs. HP 87.9 +/- 56 pg/ml, mean +/- SD; P = 0.01). High levels induced by the HP diet prevented both hypocalcemia and low calcitriol levels at each study point. The HP diet also promoted a significant increase of PTH mRNA levels that peaked about eight hours after feeding (100% increase). This was confirmed at the cellular level by in situ hybridization. Parathyroid glands from animals fed the HP diet showed a 25% increase in volume with respect to the St diet (P = 0.01), and a typical pattern of hyperplasia was found. Parathyroid vitamin D receptor (VDR) mRNA levels were not modified by the HP diet. In conclusion, parathyroid gene expression per cell and parathyroid cell hyperplasia are stimulated by high dietary phosphorus independently of calcium and calcitriol. This effect is not mediated by alterations in the gene expression of the parathyroid calcitriol receptor. Our findings emphasize the importance of the control of hyperphosphatemia in chronic renal failure patients.

Influence of vitamin D receptor genotype on bone mass changes after renal transplantation

Renal transplant patients immunosuppressed with cyclosporine A (CsA) exhibit both a significant bone loss and an increased rate of bone fractures. An association between common allelic variants of the the vitamin D receptor (VDR) gene and bone mineral density and turnover has been reported in adults. However, the genetic influence on the rate of bone loss after renal transplantation has not been explored. We prospectively determined the changes in spinal mineral density in 34 consecutive nondiabetic adults who received a cadaveric renal allograft. Serum biochemical markers of bone metabolism and the vertebral mineral density (VMD) assessed by quantitative computed tomography were determined at the time of transplantation and three and twelve months later. In fifteen patients the histomorphometric features of iliac bone were analyzed at baseline and twelve months after transplantation. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. Patients with the so-called "favorable" bb genotype (N = 12) were compared with those with the Bb or BB genotype (N = 22). Baseline VMD was similar in patients with or without the favorable bb genotype. Three months after transplantation the mean (+/- SD) VMD decreased 14 +/- 13.3 percent in all patients (16.5 +/- 13.1% in patients homozygous for the b allele and 13.77 +/- 13.9% in those with Bb or BB genotypes). The rate of VMD loss at this time inversely correlated with pretransplant PTH levels (r = -0.40; P < 0.05). Between 3 and 12 months after transplantation, patients with the favorable bb genotype recovered more VMD than those with Bb or BB types and showed a significantly higher Z score at the end of the follow-up (-0.37 +/- 1.16 vs. -1.10 +/- 1.20, respectively; P < 0.05). The beneficial effect of bb genotype was independent of the prevailing PTH levels and was also observed in those patients with a baseline PTH level < 250 pg/ml (final Z score: bb, -0.42 +/- 1.3, N = 11; Bb/BB, -1.35 +/- 0.8, N = 11, P < 0.05). At the end of follow-up, the histomorphometric studies showed a higher bone formation rate adjusted for PTH levels in patients with the Bb or BB genotype than in those with the favorable bb genotype (0.29 +/- 0.06 vs. 0.21 +/- 0.08 micron3/micron2/day respectively; P < 0.05). In conclusion, high pretransplant PTH levels enhance the early trabecular bone loss after renal transplantation, and functionally different alleles of the vitamin D receptor gene may condition the bone turnover and the degree of recovery of the bone mass.

Characterization of the promoter region of human steroid sulfatase: a gene which escapes X inactivation

The human X-linked steroid sulfatase gene (STS) was among the first genes shown to escape X inactivation. At least fourteen genes regulated in this fashion have now been recognized. They are dispersed into several regions of the X chromosome and may be controlled in a locus specific manner. Studies of the promoters of these genes could provide insights into the mechanism of X inactivation, however little information of this nature is currently available. For this reason we examined 5' flanking sequences of the human STS gene for promoter function. Four transcription start sites scattered over a 50bp region were identified. Functional domains of this TATA-less and GC poor promoter were identified by study of a series of terminal and internal deletions. A putative promoter sequence was identified which by itself exhibits little or no basal activity. However when combined with upstream regulatory elements, this segment showed weak but reproducible activity in a CAT (chloramphenicol acetyltransferase) reporter assay. Several regulatory domains acting as enhancers and repressors were subsequently identified. The relationship of this 5' sequence to the ability of the STS gene to escape X-inactivation is discussed.