Renata Canalle

Polymorphisms of xenobiotic metabolizing enzymes and DNA repair genes and outcome in childhood acute lymphoblastic leukemia

The interindividual variation in the activity of xenobiotic metabolizing enzymes and DNA repair genes could modify an individuals risk of recurrent malignancy and response to therapy. We investigated whether ALL outcome was related to polymorphisms in genes CYP2D6, MPO, EPHX1, NQO1, TS, XPD and XRCC1 in 95 consecutive ALL children by PCR or PCR-FRLP techniques. Polymorphisms in genes NQO1 and TS were associated with a significantly slow response to induction chemotherapy and NQO1 was also associated with a lower five-year event-free survival. This study suggests that polymorphisms of NQO1 and TS could be important for patient response to induction therapy and for treatment outcome.

Impact of thymidylate synthase promoter and DNA repair gene polymorphisms on susceptibility to childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the frequency of polymorphisms in the TYMS, XRCC1, and ERCC2 DNA repair genes in pediatric patients with acute lymphoblastic leukemia using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) approaches. The study was conducted in 206 patients and 364 controls from a Brazilian population. No significant differences were observed among the analyzed groups regarding XRCC1 codon 399 and codon 194 and ERCC2 codon 751 and codon 312 polymorphisms. The TYMS 3R variant allele was significantly associated with a reduced risk of childhood ALL, represented by the sum of heterozygous and polymorphic homozygous genotypes (odds ratio 0.60; 95% confidence interval 0.37–0.99). The results suggest that polymorphism in TYMS may play a protective role against the development of childhood ALL.

Role of the CYP2D6, EPHX1, MPO, and NQO1 Genes in the Susceptibility to Acute Lymphoblastic Leukemia in Brazilian Children

Polymorphic variations of several genes associated with dietary effects and exposure to environmental carcinogens may influence susceptibility to leukemia development. The objective of the present study was to evaluate the effect of the polymorphisms of debrisoquine hydroxylase (CYP2D6), epoxide hydrolase (EPHX1), myeloperoxidase (MPO), and quinone‐oxoreductase (NQO1), which have been implicated in xenobiotic metabolism, on the risk of childhood acute lymphoblastic leukemia (ALL). We evaluated the frequency of polymorphisms in the CYP2D6 (*3 and *4), EPHX1 (*2 and *3), MPO (*2), and NQO1 (*2) genes in 206 patients with childhood ALL and in 364 healthy individuals matched for age and gender from a Brazilian population separated by ethnicity (European ancestry and African ancestry), using the PCR‐RFLP method. The CYP2D6 polymorphism variants were associated with an increased risk of ALL. The EPHX1, NQO1, and MPO variant genotypes were significantly associated with a reduced risk of childhood ALL. A significantly stronger protective effect is observed when the EPHX1, NQO1, and MPO variant genotypes are combined suggesting that, CYP2D6 polymorphisms may play a role in the susceptibility to pediatric ALL, whereas the EPHX1, NQO1, and MPO polymorphisms might have a protective function against leukemogenesis. Environ. Mol. Mutagen., 2010.

Genotoxic action of the sesquiterpene lactone glaucolide B on mammalian cells in vitro and in vivo

Glaucolide B is a sesquiterpene lactone isolated from Vernonia eremophila Mart. (Vernonieae, Asteraceae) and has schistosomicidal, antimicrobial and analgesic activities. This study examined the cytotoxic and clastogenic activities of glaucolide B in human cultured lymphocytes and in bone marrow cells from BALB/c mice. The mitotic index (MI) and chromosomal aberrations were analyzed in both of the above systems, whereas sister chromatid exchanges (SCE) and the proliferation index (PI) were determined only in vitro. In human cultured lymphocytes, glaucolide B concentrations greater than 15 µg/ml of culture medium completely inhibited cell growth. At 4 µg/ml and 8 µg/ml of culture medium, glaucolide B significantly increased the frequency of chromosomal aberrations in lymphocytes and was also cytotoxic at concentrations ³8 µg/ml; there was no increase in the frequency of SCE. Glaucolide B (160-640 mg/kg) did not significantly increase the frequency of chromosomal aberrations in mouse bone marrow cells nor did it affect cell division. Since glaucolide B showed no clastogenic action on mammalian cells in vivo but was cytotoxic and clastogenic in vitro, caution is needed in its medicinal use.

Vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (NOS3) polymorphisms are associated with high relapse risk in childhood acute lymphoblastic leukemia (ALL).

BACKGROUND Angiogenesis has been shown as an important process in hematological malignancies. It consists in endothelial proliferation, migration, and tube formation following pro-angiogenic factors releasing, specially the vascular endothelial growth factor (VEGF), which angiogenic effect seems to be dependent on nitric oxide (NO). We examined the association among functional polymorphisms in these two angiogenesis related genes: VEGF (-2578C>A, -1154G>A, and -634G>C) and NOS3 (-786T>C, intron 4 b>a, and Glu298Asp) with prognosis of childhood acute lymphoblastic leukemia (ALL). METHODS The genotypes were determined and haplotypes estimated in 105 ALL patients that were divided in 2 groups: high risk (HR) and low risk of relapse (LR) patients. In addition, event-free survival curves according to genotypes were assessed. RESULTS The group HR compared to the LR showed a higher frequency of the alleles -2578C and -634C and the haplotype CGC for VEGF (0.72 vs. 0.51, p<0.008; 0.47 vs. 0.26, p<0.008; and 42.1 vs. 14.5, p<0.006; respectively) and a lower frequency of the haplotype CbGlu (0.4 vs. 8.8,p<0.006), for NOS3. CONCLUSION Polymorphisms of VEGF and NOS3 genes are associated with high risk of relapse, therefore may have a prognostic impact in childhood ALL.

Polymorphisms in genes encoding drugs and xenobiotic metabolizing enzymes in a Brazilian population.

Polymorphic variations of several genes associated with drugs and xenobiotic metabolism have been linked to the factors that predispose to the carcinogenesis process. As considerable interindividual and interethnic variation in metabolizing enzyme activity has been associated with polymorphic alleles, we evaluated the frequency of the polymorphisms of CYP2D6, EPHX1 and NQO1 genes in 361 Brazilian individuals separated by ethnicity (European and African ancestry), using the polymerase chain reaction-restriction fragment length (PCR-RFLP) method. The allele frequencies of the variants *3 and *4 for the gene CYP2D6 were 0.04 and 0.14 for white subjects and 0.03 and 0.10 for black individuals, respectively. For the both variants of the gene EPHX1, we found higher allele frequencies among white individuals compared with mulatto subjects (0.62 vs 0.54 and 0.18 vs 0.14, respectively); however, these differences were not statistically significant (p = 0.39 and 0.56, respectively). For the NQO1 gene we observed a higher frequency of the homozygous genotype among black individuals (7.9%) compared with white subjects (6.3%) (p = 0.003). The genotype frequencies were within the Hardy–Weinberg equilibrium. We concluded that the allele frequencies of CYP2D6, EPHX1 and NQO1 gene polymorphisms in this Brazilian population showed ethnic variability when compared with those observed in other populations.

Identificação dos polimorfismos do gene XRCC1 em pacientes com anemia falciforme

Abstract Sickle cell disease (SCD) is an inherent disorder caused by asingle nucleotide substitution. The great variability in clinical andhematological features of SCD provides a challenge in theunderstanding of the pathophysiological mechanisms leading tothe disease. The identification of DNA polymorphisms cancontribute to understand the role of the different biomarkers andtheir relationships with the extremely variable clinical manifestationof SCD. In order to contribute to the identification of polymorphismsin SCD, we proposed to study the distribution of the DNA repairgene XRCC1 in SCD patients and healthy control individuals. Ourresults indicate that the polymorphisms of the XRCC1 variantalleles 399Gln and 194Trp were not statistically different betweenthe groups studied. We observed a tendency for the prevalence ofthe Gln/Gln genotype in SCD patients. The results from ongoinginvestigations with other polymorphisms have been elucidatingthe role of such biomarkers and their relationships with the clinicalmanifestation of SCD. Rev. bras. hematol. hemoter. 2006;

The Role of Matrix Metalloproteinases a nd Tissue Inhibitors of Metalloproteinases in the Progression of Astrocytomas

Neoplasms of the central nervous system (CNS) constitute a group of tumors that are heterogeneous in epidemiology, biological behavior, genetic alterations, histological type, tumor location, pattern of spread, clinical presentation, natural history, age of occurrence, and prognosis (Behin et al., 2003; Louis, 2006; Stroher et al., 2000). According to the 2010 Surveillance Epidemiology and End Results [SEER] data, there were approximately 22,020 deaths from cancers of the brain and nervous system in the U.S. As reported by Binder et al., (2003) and Wrensch et al., (2002), some 7 to 16 cases of primary CNS tumors per 100,000 person-years are diagnosed in adults; approximately 50% of these cases are metastatic tumors, according to Hill et al. 1999. CNS tumors are the third leading cause of cancer deaths in middle-aged adults, the second most common cause of death in children, and the most common solid tumor in children (Giles, 1995; Heuer et al., 2007). The incidence of CNS tumors in children and adolescents is approximately 2.7 cases per 100,000 patients per year. This figure accounts for 16% of the neoplasms within this group, making CNS tumors the second most frequent type of cancer (after leukemia) in young patients (20 years old and younger). The mortality rate observed with CNS tumors is one of the highest among childhood cancers. Diagnosis and treatment improvements, however, has contributed to the survival of these patients (Potter et al., 1998). Epidemiological studies have shown a slight increase in the incidence of CNS tumors during the 1980s and 1990s in children and the elderly (Fisher et al. 2007; Swensen & Bushouse 1998). The apparent increase in the number of cases of CNS cancers is directly linked to the implementation of high-resolution neuroimaging tools, such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT), which have impacted the clinical diagnosis of neurological diseases (Cristensen et al., 2003; Fisher et al., 2007). Another