FAMLF is a target of miR-181b in Burkitt lymphoma

Burkitt lymphoma (BL) is a highly malignant non-Hodgkin's lymphoma that is closely related to the abnormal expression of genes. Familial acute myelogenous leukemia related factor (FAMLF; GenBank accession No. EF413001.1) is a novel gene that was cloned by our research group, and miR-181b is located in the intron of the FAMLF gene. To verify the role of miR-181b and FAMLF in BL, RNAhybrid software was used to predict target site of miR-181b on FAMLF and real-time quantitative PCR (RQ-PCR) was used to detect expression of miR-181b and FAMLF in BL patients, Raji cells and unaffected individuals. miR-181b was then transfected into Raji and CA46 cell lines and FAMLF expression was examined by RQ-PCR and western blotting. Further, Raji cells viability and proliferation were detected by MTT and clone formation, and Raji cell cycle and apoptosis were detected by flow cytometry. The results showed that miR-181b can bind to bases 21–42 of the FAMLF 5′ untranslated region (UTR), FAMLF was highly expressed and miR-181b was lowly expressed in BL patients compared with unaffected individuals. FAMLF expression was significantly and inversely correlated to miR-181b expression, and miR-181b negatively regulated FAMLF at posttranscriptional and translational levels. A dual-luciferase reporter gene assay identified that the 5′ UTR of FAMLF mRNA contained putative binding sites for miR-181b. Down-regulation of FAMLF by miR-181b arrested cell cycle, inhibited cell viability and proliferation in a BL cell line model. Our findings explain a new mechanism of BL pathogenesis and may also have implications in the therapy of FAMLF-overexpressing BL.

Evaluation of bi/oligoclonal rearrangement of immunoglobulin and T-cell receptor genes in Iranian children suffering B-precursor acute lymphoblastic leukemia

Clonal gene rearrangement of immunoglobulin and T cell receptor may have mono, bi or oligoclonal pattern. Significance of these patterns were studied at diagnosis and follow up of MRD in many countries, however, similar studies have not been conducted among Iranian patients. We investigated the bi/oligoclonal pattern and their association with quantitative and qualitative parameters especially MRD in Iranian children suffering from B-precursor acute lymphoblastic leukemia. In our prospective study, bone marrow aspirates of 140 patients with B-precursor ALLs were selected. Mononuclear cells including leukemic blasts isolated by density gradient. Having DNA extracted, hypervariable regions of IgH, IgK, TCR-delta [D delta 2-D delta 3, V delta 2-D delta 3] and TCR-lambda [V lambda, V lambda I, V lambda II] were amplified by consensus primers using PCR. PCR products were analyzed after heteroduplex analysis and polyacrylamide gel electrophoresis [silver stain]. The DNA sequences were compared and aligned to the sequences homologous for IgH and IgK published by Gene Bank. Bone marrow aspirates of days 14, 28 and 45, as well as months 3 and 6 were treated similarly. IgH gene rearrangements were reported in 114 [90.5%] patients using consensus primers for CDR-III and CDR-I regions [monoclonal: 57.8%, biclonal:34.9% and oligoclonal:5.5%]. Clonal pattern of IgK-Kde were present in 59 cases [67%] [biclonal:10%] Clonal rearrangement of TCR-lambda [V lambda] and V lambda I/II were present in 79.3% and 64.9% of patients, respectively, however, only 5% of cases showed biclonal pattern. The V lambda II rearrangement was the most common [46.8%] type in TCR-lambda. 47 [45.2%] and 11 [16.6%] patients had V delta 2-D delta 3 and D delta 2-D delta 3 partial gene rearrangements, respectively. Biclonal/oligoclonal pattern were present in 13 [27.7%] and 2 [4.3%] cases with V delta 2-D delta 3 rearrangement. Only one patient had biclonal D delta 2-D delta 3 rearrangement. No significant difference regarding the quantitative and qualitative parameters and MRD was observed between the two groups. Bi/oligoclonal rearrangement of IgH, IgK, TCR-delta [D delta 2-D delta 3, V delta 2-Ddelta 3] and TCR-lambda [V lambda, V lambda I, Vlambda II] genes had comparable pattern to other populations. Results of MRD study showed no significant differences between the two groups

Estudios citogenéticos en niños con Leucemia Linfocitica Aguda-B en Costa Rica / Cytogenetic studies in children with Acute Lymphocitic Leukemia-B in Costa Rica

Chromosome analyses were performed on bone marrow of 177 pediatric patients with Acute Lymphocitic Leukemia at the [quot ]Hospital Nacional de Nifios[quot ]. The standard cytogenetic techniques now belongs to the panel of mandatory analyses performed at diagnosis of our acute leukemia patients and represent a major advantage to be effective and independent prognostic factors, essential for therapeutic choices. Cytogenetic results were achieved in 83% of the bone marrow samples: normal karyotypes represented 29% and abnormal karyotypes 71% with the follow distribution: t (9;22) 3%; t (l;19) 5%; t (4;11) 3%, Hyperdiploidy 39%; other chromosomal abnormalities 21%. Systematic cytogenetic analyses are essencial to define morpho-immunologic sub-types of leukemia and to detect new translocations that allows to understand hematopoiesis and leukemogenesis.

Mecanismos de oncogénesis viral / Mechanisms of viral oncogenesis

Actualmente se sabe que el 20 por ciento de los cánceres humanos están asociados con virus oncogénicos. El virus papiloma humano con cáncer anogenital, los virus de la hepatitis B y C con carcinoma hepatocelular, el virus Epstein Barr con carcinomas nasofaríngeos y linfomas, el virus de la leucemia-linfoma T con leucemias en el adulto. Un rasgo común en todos los tumores asociados con infección viral es el largo período de latencia entre la infección y la aparición de la neoplasia y la baja proporción de individuos infectados que desarrollan un tumor maligno. Estas observaciones indican que los virus oncogénicos son necesarios pero no suficientes para inducir cáncer, otros factores podrían estar involucrados. Esta actualización resume informaciones recientes acerca de los mecanismos de carcinogénesis viral, en particular, la interacción de oncoproteínas virales y proteínas supresoras tumorales. La inactivación de estas proteínas supresoras podría representar una estrategia común a través de la cual los virus tumorales pueden contribuir a la transformación maligna de la célula

Cytogenetic studies on patients of acute lymphoblastic leukemia Burkitt's type with (8;14) & (14;18) translocations.

Eight patients with acute lymphoblastic leukemia of Burkitt's type (ALL-L3) and two patients with Burkitt's lymphoma (BL) were subjected for cytogenetic studies. Translocation (8;14)(q24;q32) was present in nine (90%) patients; seven patients of ALL-L3 and two of BL. One ALL-L3 patient revealed t(14;18)(q32;q21) in 100 per cent metaphases. Additional clonal chromosomal anomalies present in these patients were deletion (6q) (40%) and trisomy 21(20%). The occurrence of t(8;14)(q24;q32) in ALL-L3 and BL patients in our series supports the association of t(8;14) with ALL-L3 and Burkitt's lymphoma.