Sonia Carturan

DNA repair gene polymorphisms, bulky DNA adducts in white blood cells and bladder cancer in a case-control study

Individuals differ widely in their ability to repair DNA damage, and DNA‐repair deficiency may be involved in modulating cancer risk. In a case‐control study of 124 bladder‐cancer patients and 85 hospital controls (urological and non‐urological), 3 DNA polymorphisms localized in 3 genes of different repair pathways (XRCC1‐Arg399Gln, exon 10; XRCC3‐Thr241Met, exon 7; XPD‐Lys751Gln, exon 23) have been analyzed. Results were correlated with DNA damage measured as 32P‐post‐labeling bulky DNA adducts in white blood cells from peripheral blood. Genotyping was performed by PCR‐RFLP analysis, and allele frequencies in cases/controls were as follows: XRCC1‐399Gln = 0.34/0.39, XRCC3‐241Met = 0.48/0.35 and XPD‐751Gln = 0.42/0.42. Odds ratios (ORs) were significantly greater than 1 only for the XRCC3 (exon 7) variant, and they were consistent across the 2 control groups. XPD and XRCC1 appear to have no impact on the risk of bladder cancer. Indeed, the effect of XRCC3 was more evident in non‐smokers [OR = 4.8, 95% confidence interval (CI) 1.1–21.2]. XRCC3 apparently interacted with the N‐acetyltransferase type 2 (NAT‐2) genotype. The effect of XRCC3 was limited to the NAT‐2 slow genotype (OR = 3.4, 95% CI 1.5–7.9), suggesting that XRCC3 might be involved in a common repair pathway of bulky DNA adducts. In addition, the risk of having DNA adduct levels above the median was higher in NAT‐2 slow acetylators, homozygotes for the XRCC3‐241Met variant allele (OR = 14.6, 95% CI 1.5–138). However, any discussion of interactions should be considered preliminary because of the small numbers involved. Our results suggest that bladder‐cancer risk can be genetically modulated by XRCC3, which may repair DNA cross‐link lesions produced by aromatic amines and other environmental chemicals.

DNA adduct levels and DNA repair polymorphisms in traffic-exposed workers and a general population sample.

Peripheral blood DNA adducts have been considered an acceptable surrogate for target tissues and possibly predictive of cancer risk. A group of 114 workers exposed to traffic pollution and a random sample of 100 residents were drawn from the EPIC cohort in Florence, a population recently shown to present increased DNA adduct levels (Palli et al., Int J Cancer 2000;87:444–51). DNA bulky adducts and 3 DNA repair gene polymorphisms were analyzed in peripheral leukocytes donated at enrollment, by using 32P‐postlabeling and PCR methods, respectively. Adduct levels were significantly higher for traffic workers among never smokers (p = 0.03) and light current smokers (p = 0.003). In both groups, urban residents tended to show higher levels than those living in suburban areas, and a seasonal trend emerged with adduct levels being highest in summer and lowest in winter. Traffic workers with at least 1 variant allele for XPD‐Lys751Gln polymorphism had significantly higher levels in comparison to workers with 2 common alleles (p = 0.02). A multivariate analysis (after adjustment for age, season, area of residence, smoking, XPD‐Lys751Gln genotype and antioxidant intake) showed a significant 2‐fold association between occupational exposure and higher levels of adducts (odds ratio 2.1; 95% confidence interval 1.1–4.2), in agreement with recent pooled estimates of increased lung cancer risk for similar job titles. Our results suggest that traffic workers and the general population in Florence are exposed to high levels of genotoxic agents related to vehicle emissions. Photochemical pollution in warmer months might be responsible for the seasonal trend of genotoxic damage in this Mediterranean urbanized area.

Early prediction of treatment outcome in acute myeloid leukemia by measurement of WT1 transcript levels in peripheral blood samples collected after chemotherapy.

The Wilms’ tumor gene WT1 is a reliable marker for minimal residual disease assessment in acute leukemia patients. The study was designed to demonstrate the potential use of WT1 to establish quality of remission in acute leukemia patients for early identification of patients at high risk of relapse. A prospective study based on a quantitative Real–Time PCR (TaqMan) assay in 562 peripheral blood samples collected from 82 acute leukemia patients at diagnosis and during follow-up was established. The evaluation of WT1 in peripheral blood samples after induction chemotherapy can distinguish the continuous complete remission patients from those who obtain only an “apparent” complete remission and who could relapse within a few months. WT1 helps identify patients at high risk of relapse soon after induction chemotherapy allowing post-induction therapy in high risk patients to be intensified.

Deferasirox is a powerful NF-κB inhibitor in myelodysplastic cells and in leukemia cell lines acting independently from cell iron deprivation by chelation and reactive oxygen species scavenging

Background Usefulness of iron chelation therapy in myelodysplastic patients is still under debate but many authors suggest its possible role in improving survival of low-risk myelodysplastic patients. Several reports have described an unexpected effect of iron chelators, such as an improvement in hemoglobin levels, in patients affected by myelodysplastic syndromes. Furthermore, the novel chelator deferasirox induces a similar improvement more rapidly. Nuclear factor-κB is a key regulator of many cellular processes and its impaired activity has been described in different myeloid malignancies including myelodysplastic syndromes. Design and Methods We evaluated deferasirox activity on nuclear factor-κB in myelodysplastic syndromes as a possible mechanism involved in hemoglobin improvement during in vivo treatment. Forty peripheral blood samples collected from myelodysplastic syndrome patients were incubated with 50 μM deferasirox for 18h. Results Nuclear factor-κB activity dramatically decreased in samples showing high basal activity as well as in cell lines, whereas no similar behavior was observed with other iron chelators despite a similar reduction in reactive oxygen species levels. Additionally, ferric hydroxyquinoline incubation did not decrease deferasirox activity in K562 cells suggesting the mechanism of action of the drug is independent from cell iron deprivation by chelation. Finally, incubation with both etoposide and deferasirox induced an increase in K562 apoptotic rate. Conclusions Nuclear factor-κB inhibition by deferasirox is not seen from other chelators and is iron and reactive oxygen species scavenging independent. This could explain the hemoglobin improvement after in vivo treatment, such that our hypothesis needs to be validated in further prospective studies.

Comparison of three Tfr2 -deficient murine models suggests distinct functions for TFR2 alpha and beta isoforms in different tissues

Transferrin receptor 2 (TFR2) is a transmembrane protein that is mutated in hemochromatosis type 3. The TFR2 gene is transcribed in 2 main isoforms: the full-length (alpha) and a shorter form (beta). alpha-Tfr2 is the sensor of diferric transferrin, implicated in the modulation of hepcidin, the main regulator of iron homeostasis. The function of the putative beta-Tfr2 protein is unknown. We have developed a new mouse model (KI) lacking beta-Tfr2 compared with Tfr2 knockout mice (KO). Adult Tfr2 KO mice show liver iron overload and inadequate hepcidin levels relative to body iron stores, even though they increase Bmp6 production. KI mice have normal transferrin saturation, liver iron concentration, hepcidin and Bmp6 levels but show a transient anemia at young age and severe spleen iron accumulation in adult animals. Fpn1 is strikingly decreased in the spleen of these animals. These findings and the expression of beta-Tfr2 in wild-type mice spleen suggest a role for beta-Tfr2 in Fpn1 transcriptional control. Selective inactivation of liver alpha-Tfr2 in KI mice (LCKO-KI) returned the phenotype to liver iron overload. Our results strengthen the function of hepatic alpha-Tfr2 in hepcidin activation, suggest a role for extrahepatic Tfr2 and indicate that beta-Tfr2 may specifically control spleen iron efflux.

Estrogen Receptor-α Polymorphisms and Angiographic Outcome After Coronary Artery Stenting

Objective—Because of the receptor-mediated antiproliferative effects of estradiol on vascular smooth muscle cells, our study aimed at identifying a role of PvuII and XbaI polymorphisms of the &agr;-estrogen receptor (&agr;ER) gene in the occurrence of restenosis after coronary stent implantation (in-stent restenosis [ISR]). Methods and Results—In 858 patients (148 women), 955 lesions were treated with stent implantation, and the PvuII C/T and XbaI G/A polymorphisms of the &agr;ER gene were determined. Quantitative angiography was performed before and after stenting and at 6-month follow-up. The allelic frequencies were similar between sexes (C/T allele, 0.43/0.57 and 0.44/0.56; P =0.9; G/A allele, 0.35/0.65 and 0.38/0.62; P =0.8; in women and men, respectively). A significantly higher ISR rate in women than in men homozygous for the T-allele of the PvuII polymorphism (42.6% versus 26.9%, P =0.03) or the G-allele of the XbaI polymorphism (41.2% versus 19.4%, P =0.04) was observed. At multivariate analysis, T/T genotype was the only independent predictor of ISR in women but not in men (odds ratio, 1.5; 95% CI, 1.0 to 2.1; P =0.03). XbaI polymorphism was no longer associated with ISR in both sexes. Conclusions—Women homozygous for the T-allele of the PvuII polymorphism of the &agr;ER gene treated with coronary stent implantation have a higher risk of ISR than men.

Sensitivity to imatinib therapy may be predicted by testing Wilms tumor gene expression and colony growth after a short in vitro incubation

The objective of the current study was to verify the ability to predict response to imatinib therapy using in vitro assays to evaluate the inhibition of Wilms tumor gene (WT1) expression and colony growth after samples obtained from patients with chronic myelogenous leukemia (CML) before the start of treatment were subjected to short‐term incubation with imatinib.

Valproate enhances imatinib‐induced growth arrest and apoptosis in chronic myeloid leukemia cells

The objective of this study was to evaluate the ability of the clinically available histone deacetylase (HDAC) inhibitor valproate to enhance the cytotoxicity of the Bcr‐Abl inhibitor imatinib in imatinib‐resistant cell lines.

Role of TGF-β1 haplotypes in the occurrence of myocardial infarction in young Italian patients

BackgroundTransforming growth factor beta 1 (TGF-β1) gene play an important role in the acute myocardial infarction (AMI), however no investigation has been conducted so far in young AMI patients.In this study, we evaluated the influence of TGF-β1 polymorphisms/haplotypes on the onset and progression of AMI in young Italian population.Methods201 cases and 201 controls were genotyped for three TGF-β1 polymorphisms (G-800A, C-509T and Leu10Pro). The main follow-up end-points (mean follow-up, 107 ± 49 months) were death, myocardial infarction or revascularization procedures.ResultsSignificant risk factors were smoking (p < 10-4), family history for coronary artery disease (p < 10-4), hypercholesterolemia (p = 0.001) and hypertension (p = 0.002). The C-509T and Leu10Pro polymorphisms showed significant differences (p = 0.026 and p = 0.004) between cases and controls.The most common haplotypes revealed a possible protective effect (GCT, OR 0.75, 95% CI 0.57–0.99, p = 0.042) and an increased risk of AMI (GTC, OR 1.51, 95% CI 1.13–2.02, p = 0.005), respectively.No statistical differences were observed in genotype distribution in the follow-up study between the two groups: 61 patients with subsequent events (13 deaths) and 108 without events.ConclusionEven though our results need to be further confirmed in larger studies, this is the first study reporting on a possible role of TGFβ1 common haplotypes in the onset of AMI in young patients.

WT1 transcript amount discriminates secondary or reactive eosinophilia from idiopathic hypereosinophilic syndrome or chronic eosinophilic leukemia

Idiopathic hypereosinophilic syndromes (HES) comprise a spectrum of indolent to aggressive diseases characterized by persistent hypereosinophilia. Hypereosinophilia can result from the presence of a defect in the hematopoietic stem cell giving rise to eosinophilia, it can be present in many myeloproliferative disorders or alternatively it may be a reactive form, secondary to many clinical conditions. The hybrid gene FIP1L1-PDGRFα was identified in a subset of patients presenting with HES or chronic eosinophilic leukemia (CEL). In spite of this, the majority of HES patients do not present detectable molecular lesions and for many of them the diagnosis is based on exclusion criteria and sometimes it remains doubt. In this study we explored the possibility to distinguish between HES/CEL and reactive hypereosinophilia based on WT1 transcript amount. For this purpose, 312 patients with hypereosinophilia were characterized at the molecular and cytogenetic level and analyzed for WT1 expression at diagnosis and during follow-up. This study clearly demonstrates that WT1 quantitative assessment allows to discriminate between HES/CEL and reactive eosinophilia and represents a useful tool for disease monitoring especially in the patients lacking a marker of clonality.