Introduction.Pax-5 gene codifies for a transcription factor central to B-cell differentiation and function, expressed during the early stage of differentiation and alternatively spliced during B-cell ...development. In addition to the full-length isoform (Pax-5a), isoforms arising from the inclusion or exclusion of exons 2, 7, 8, and/or 9, and lacking the DNA-binding and the transactivating domains, have been described. These isoforms and their levels of expression increase during B-cell maturation. In particular, Pax-5b isoform (deleted of exon 2), resulting in protein with partial DNA-binding domain, is related with the differentiation stage. Recently, mutations of Pax-5 gene were reported in 31.7% of 242 children (Mullighan, Nature 2007) and 30% of 119 adults (Familiades, ASH 2007 abs. 2806) with B-cell precursor acute lymphoblastic leukemia (ALL). We investigated Pax-5 gene mutations and isoforms expression in patients with ALL at the diagnosis and in selected cell populations from control subjects.
Methods.Pax-5 mutations and mRNA isoforms were investigated by sequence analysis. Pax-5a and Pax-5b expression levels were evaluated by quantitative PCR in leukemic cells. Total RNA was obtained from leukemic blasts of 95 patients with B-cell precursor ALL at diagnosis, 45 adults and 50 children. These last had been selected according to the presence of adverse translocations: BCR/ABL p190 (n=10), E2A-PBX1 (n=10), TEL/AML (n=10), MLL/AF4 (n=10), or none (n=10). mRNA was obtained from purified peripheral blood CD19+ lymphocytes (6 samples), from bone marrow CD34+ hematopoietic progenitor cells (6 samples), and pro-B CD34+CD19+ cells (3 samples) from a total of 8 healthy bone marrow donors.
Results. Pax-5 gene point mutations were found in 8/45 adults (18%) and 14/50 children (28%) (p=n.s.), resulting in a total of 20 different mutations. Mutations were located as follows: exon 2 (53G>C, 76delG, 101C>G, 113G>A, 197G>A), exon 3 (223A>G, 247delA, 296T>C), exon 4 (446A>T, 526G>A), exon 5 (580A>C, 601G>A), exon 6 (625C>T, 716G>A), exon 7 (836C>A), exon 8 (955G>A, 964insC, 971A>G), exon 9 (1058C>T), exon 10 (1133G>A). There was no correlation between the presence of mutations and the listed genetic subtypes. Pax-5 alternative splicing was observed in 47/95 cases (49%): 29/45 adults (64%) and 18/50 children (36%) (p=n.s.). Alternative splicing resulted in increased frequencies of the Pax-5b isoform and the deletion of exons 8 and/or 9; furthermore, a novel isoform resulting from the skipping of exon 5 was documented. On the contrary, only the fulllenght isoform was present in CD34+ progenitors and CD34+CD19+ cells from healthy donors, in which deleted isoforms were detected only at the stage of mature B-lymphocytes.
Conclusion: Pax-5 mutations are frequent in childhood and adult ALL and are scattered all over the gene. We extend the current knowledge on their pathogenic role by demonstrating that alternative splicing is a common event in these patients. Imbalance between the fulllength and the Pax-5b isoforms is expected to affect the maturation of the B-cell and its propensity to apoptosis (Robichaud Nucleic Acids Res 2008), thus contributing to the process of leukemogenesis. Based on our findings, this mechanism acts broadly and is independent of the most common ALL genetic translocations.
After 12 months of treatment, most patients with chronic myeloid leukemia (CML) who receive imatinib as first-line therapy will have complete cytogenetic and molecular response. However, several ...patients will not exhibit molecular response, but their innate mechanism(s) of resistance remain poorly understood. We explored the molecular events involved in innate resistance in CML.
Five patients who were molecular nonresponders and 7 major responders were investigated by using the expression profile of a set of 380 genes. Multiple testing procedure, Significance Analysis of Microarrays, Empirical Bayes Analysis of Microarrays, False Discovery Rate, and support vector machine with linear kernel were used for comparative analysis.
Three hundred twenty-three of 380 genes (85%) were overexpressed in the nonresponder group compared with the responders. After a very stringent statistical analysis, a list of 26 genes was identified, in which overexpression in nonresponders was highly statistically significant. These genes are involved in signal transduction and transcription factors, apoptosis, cell cycle, and adhesion. Discriminative power of the proposed gene set was estimated by 2 different statistical methods, which yielded a correct prediction of the drug response for each patient used as a test sample.
Our study identified a set of 26 genes involved in resistance to imatinib, which can be used as clinical predictors or therapeutic targets. We consider some of them of particular interest: IGFBP2, CDC37, MAPK3, ETS1, and PEA15. Epigenetic mechanisms, such as genome-wide promoter hypomethylation, might be involved as the basic mechanism for innate resistance in CML.
We investigated the metabolomic profile associated with exposure to trihalomethanes (THMs) and nitrate in drinking water and with colorectal cancer risk in 296 cases and 295 controls from the Multi ...Case-Control Spain project. Untargeted metabolomic analysis was conducted in blood samples using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. A variety of univariate and multivariate association analyses were conducted after data quality control, normalization, and imputation. Linear regression and partial least-squares analyses were conducted for chloroform, brominated THMs, total THMs, and nitrate among controls and for case-control status, together with a N-integration model discriminating colorectal cancer cases from controls through interrogation of correlations between the exposure variables and the metabolomic features. Results revealed a total of 568 metabolomic features associated with at least one water contaminant or colorectal cancer. Annotated metabolites and pathway analysis suggest a number of pathways as potentially involved in the link between exposure to these water contaminants and colorectal cancer, including nicotinamide, cytochrome P-450, and tyrosine metabolism. These findings provide insights into the underlying biological mechanisms and potential biomarkers associated with water contaminant exposure and colorectal cancer risk. Further research in this area is needed to better understand the causal relationship and the public health implications.
The article describes the research policy of the mentioned university within the framework of the national higher education and research policy. The Campinas model is characterized by a research ...policy oriented "to hard sciences and engineering and guided by the demands of the productive sector", especially "to meet the demands of the local industry." This, at least, was the concept of the initial phase in Campinas; the article also shows why this aim had to be abandoned later on. (DIPF/ Bi.).
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