SEPT2 is a new fusion partner of MLL in acute myeloid leukemia with t(2;11)(q37;q23)

We have identified a new mixed lineage leukemia (MLL) gene fusion partner in a patient with treatment-related acute myeloid leukemia (AML) presenting a t(2;11)(q37;q23) as the only cytogenetic abnormality. Fluorescence in situ hybridization demonstrated a rearrangement of the MLL gene and molecular genetic analyses identified a septin family gene, SEPT2, located on chromosome 2q37, as the fusion partner of MLL. RNA and DNA analyses showed the existence of an in-frame fusion of MLL exon 7 with SEPT2 exon 3, with the genomic breakpoints located in intron 7 and 2 of MLL and SEPT2, respectively. Search for DNA sequence motifs revealed the existence of two sequences with 94.4% homology with the topoisomerase II consensus cleavage site in MLL intron 7 and SEPT2 intron 2. SEPT2 is the fifth septin family gene fused with MLL, making this gene family the most frequently involved in MLL-related AML (about 10% of all known fusion partners). The protein encoded by SEPT2 is highly homologous to septins 1, 4 and 5 and is involved in the coordination of several key steps of mitosis. Further studies are warranted to understand why the septin protein family is particularly involved in the pathogenesis of MLL-associated leukemia.     

Hemophagocytic syndrome complicating T-cell acute lymphoblastic leukemia with a novel t(11;14)(p15;q11) chromosome translocation

A case of hemophagocytic syndrome that developed in a patient with T-cell acute lymphoblastic leukemia (ALL) with a novel chromosome translocation involving 14q11 is reported. A 15-year-old boy with T-cell ALL in relapse showed leukemic cells with an abnormal karyotype of 46,XY,-15,t(11;14)(p15;q11), +der(15)t(15;?)(p11;?). Pancytopenia and extensive hemophagocytosis by macrophages in the bone marrow were observed after reinduction chemotherapy and again at the terminal stage. At autopsy, infiltration of such cells was also found in other organs. The findings suggested occurrence of hemophagocytic syndrome probably associated with cytomegalovirus (CMV) infection. The t(11;14)(p15;q11) may be a novel translocation specific for T-cell ALL, and conceivably, the association of T-cell ALL with the histiocytosis in this patient may not have been coincidental.     

Therapy-related adult acute lymphoblastic leukemia with t(4;11)(q21; q23): MLL rearrangement, p53 mutation and multilineage involvement.

A diagnosis of pro-B acute lymphoblastic leukemia (ALL) with CD15+ was made in a 42-year-old woman, 12 months after the treatment of uterine adenocarcinoma by carboplatinum, anthracyclines, etoposide and radiotherapy. Molecular cytogenetic studies revealed a karyotype with multiple chromosome changes, including the t(4;11)(q21;q23) and a 17p-chromosome, with MLL disruption and 17p13/p53 gene deletion in 86% of the cells. A p53 exon 6 mutation was documented, resulting in p53 protein stabilization, with 20% of the cells reacting with the 1801 anti-p53 monoclonal antibody. Dual-color FISH using MLL and p53 probes was performed on peripheral blood smears, providing direct evidence of the involvement of the blast cells and of the granulocytic lineage. Only a partial, shortlasting response was obtained by induction treatment, confirming that a poor prognosis is associated with therapy-related ALL with the 4;11 translocation.     

t(4;11)(q21;p15), including one complex translocation t(1;4;11)(p32;q21;p15), in adult T-cell acute lymphoblastic leukemia

We report two adults with T-cell acute lymphoblastic leukemia (ALL). Cytogenetic studies at diagnosis with R banding showed a 46,XX,t(4;11)(q21;p15)/46,XX karyotype in one patient and 46,XY,t(1;4;11)(p32;q21;p15)/46,XY in the other. Fluorescence in situ hybridization with whole chromosome paints (WCP1, WCP4, and WCP11) confirmed the complex rearrangement in the latter patient. Only 10 T-cell ALL patients with the t(4;11)(q21;p15) have been described, all, but one of them, being over 15 years old. Although recurrent in T-cell ALL, its frequency appears to be very low; indeed, it has been identified in only 4 of 193 adults and in 1 of 734 children with T-cell ALL thus far reported in the literature.     

伴t(8;21)(q22;q22)易位的急性双表型白血病的临床研究

目的:报道新发现4例伴t(8;21)(q22;q22)易位的急性双表型白血病(biphenotypic acute leukemia,BAL),分析其细胞形态学、免疫表型、染色体核型分型及临床特征。方法:将4例伴t(8;21)(q22;q22)易位的BAL(A组),与随机挑选同期发现的伴其他克隆性染色体改变的BAL(B组)和伴t(8;21)(q22;q22)的M2b(C组)病例对照,对染色体核型分型及临床特点比较分析。结果:伴t(8;21)(q22;q22)易位的BAL特点如下:①无显著男女性别差异;②发病年龄较轻;③外周血白细胞计数不增高;④骨髓细胞形态学显示为粒细胞白血病,且原始细胞显著增多;⑤免疫表型均为B淋巴系和髓系共表达的BAL,CD34表达阳性,且为高表达;⑥染色体改变除t(8;21)(q22;q22)易位外,亦常见性染色体缺失,与(acute myeloid leukemia,AML)AML-M2b的特点相符;亦出现复杂染色体改变,符合BAL的特点。⑦对兼顾髓系和淋巴系的联合治疗方案反应较好,与B组的BAL类似,1例单用AML方案(MA)治疗者NR,后死亡。结论:报道新发现的一组伴t(8;21)(q22;q22)易位的BAL,提示此类患者的白血病细胞克隆起源可能较早。     

伴t(8;21)(q22;q22)易位的急性双表型白血病的临床研究

Objective： To report 4 cases of biphenotypic acute leukemia （BAL） with t（8;21）（q22;q22）, and analyze the characteristics of morphology, immune phenotype, chromosome karyotype （MIC） and clinical manifestations. Methods： The BAL patients with t（8;21）（q22;q22） （group A） were compared with the randomly selected BAL patients with other clonical chromosomal changes （group B） and acute myeloid leukemia M2 cases with t（8;21）（q22;q22） （group C） in MIC and clinical features. Results： BAL with t（8;21）（q22;q22） showed acute myeloid leukemia with high percentages of blast cells morphologically; revealed co-positive to B-lymphoid and myeloid lineages, frequent and high expressions of CD34 and CD33; were responsive to chemotherapy for myeloid and lymphocytic leukemia simultaneously well. Conclusion： A new subset of BAL with t（8;21）（q22;q22） was reported, and this suggests that the leukemia colony with t（8;21）（q22;q22） might originate from early phase of hematopoiesis.     

The human LASP1 gene is fused to MLL in an acute myeloid leukemia with t(11;17)(q23;q21)

The MLL gene at chromosome 11q23 is frequently rearranged in acute leukemia. Here we report the identification of a new MLL fusion partner in the case of an infant with AML-M4 and a t(11;17)(q23;q21) translocation. Fluorescence in situ hybridization (FISH) and RT-PCR analyses indicated a rearrangement of the MLL gene, but no fusion with previously identified MLL fusion partners at 17q, such as AF17 or MSF. Rapid amplification of cDNA ends (RACE) revealed an in-frame fusion of MLL to LASP1, a gene that is amplified and overexpressed in breast cancer. Retroviral transduction of myeloid progenitors demonstrated that MLL/LASP1 is the fourth known fusion of MLL with a cytoplasmic protein that has no in vitro transformation capability, thus establishing a potential subgroup among the MLL fusion proteins.     

A novel translocation t(3;22)(q21;q11) involving 3q21 in myelodysplastic syndrome-derived overt leukemia with thrombocytosis

We report here a novel translocation t(3;22)(q21;q11) in myelodysplastic syndrome (MDS)-derived overt leukemia with thrombocytosis. A 44-year-old female was initially diagnosed as MDS with a low platelet count and normal karyotype. After 4 months, blood leukemic cells and platelets rapidly increased concomitantly and a diagnosis of acute myeloblastic leukemia (AML M1) was made. Chromosome analysis showed 46, XX, t(3;22)(q21;q11) in 14 of 20 metaphases. Fluorescence in situ hybridization analysis confirmed both the der(3)t(3;22) and the der(22)t(3;22). Our results suggest that unidentified gene(s) at 3q21 breakpoint may be implicated in the pathogenesis of abnormal thrombopoiesis as observed in the 3q21q26 syndrome.     

11;14 translocation in childhood T-cell acute lymphoblastic leukemia

No consistent chromosome abnormalities have been reported so far in T-cell lymphoma-leukemia. We report here two children suffering from T-cell acute lymphoblastic leukemia (ALL) with t(11;14)(q13;p11). Even though the breakpoints we claim are different from those in a recent report, we believe that their cases and ours have the same abnormality and that patients with this abnormality constitute a distinct subgroup of T-cell ALL positive for sheep erythrocyte receptor (E+) in children.     

t(11;14)(q23;q24) generates an MLL-human gephyrin fusion gene along with a de facto truncated MLL in acute monoblastic leukemia

More than 20 different partner genes with MLL have been cloned from leukemia cells with translocations involving chromosome 11 band q23 (11q23). All reported partner genes fused in-frame to MLL and the fusion cDNA encode chimeric MLL proteins with a significant portion derived from the partner genes. We analyzed one patient with de novo acute monoblastic leukemia with t(11;14)(q23;q24) and identified that a human homologue of gephyrin (human gephyrin) fused with MLL. Gephyrin is a rat glycine receptor-associated protein, which forms submembranous complexes and anchor glycine or gamma-aminobutyric acidA receptors to microtubules. Alternative splicing of human gephyrin gene created two different forms of fusion cDNA. In one form, human gephyrin gene fused in-frame to MLL exon 9, and the chimeric product had COOH terminus of human gephyrin protein, including the tubulin binding site. In the other, the reading frame terminated shortly after the fusion point. As a result, only seven amino acids with no known function were attached to the NH2 terminus of MLL protein. The functional significance of this de facto truncated MLL gene product is not clear.     

Characterization of the MLL partner gene AF15q14 involved in t(11;15)(q23;q14)

Translocations interrupting the mixed lineage leukemia gene (MLL) occur in 7-10% of acute lymphoblastic leukemia (ALL) and 5-6% of acute myeloid leukemia (AML) cases. One of these translocations, t(11;15)(q23;q14), occurs rarely in both ALL and AML. The gene on chromosome 15, AF15q14, was cloned recently in a patient with AML-M4. We have identified the same gene in a de novo T-ALL patient. However, both the MLL and AF15q14 breakpoints in these patients differed: in the previously reported AML-M4, both gene breaks were within exons, while in our ALL case the MLL break is intronic and the AF15q14 break is exonic. The MLL-AF15q14 fusion described previously shares no AF15q14 residues in common with the chimera reported here. The fusion proteins also differ with respect to MLL--the previously described fusion contains 55 extra amino acids as its MLL break is in exon 11, while the chimera we report breaks in intron 9. Contrary to the originally described normal AF15q14 (5925-bp cDNA encoding a 1833-aa protein), we identify a 7542-bp cDNA and a 2342-aa AF15q14 protein. AF15q14 appears identical to an mRNA previously found to be expressed in melanoma rendered nontumorigenic by microcell-mediated introduction of normal chromosome 6, suggesting the gene may function normally to suppress cell growth and/or enhance maturation.     

Bone marrow ectopic expression of a non-coding RNA in childhood T-cell acute lymphoblastic leukemia with a novel t(2;11)(q11.2;p15.1) translocation

Background

The implementation of gene therapy for the treatment of pituitary tumors emerges as a promising complement to surgery and may have distinct advantages over radiotherapy for this type of tumors. Up to now, suicide gene therapy has been the main experimental approach explored to treat experimental pituitary tumors. In the present study we assessed the effectiveness of insulin-like growth factor I (IGF-I) gene therapy for the treatment of estrogen-induced prolactinomas in rats.

Results

Female Sprague Dawley rats were subcutaneously implanted with silastic capsules filled with 17-β estradiol (E₂) in order to induce pituitary prolactinomas. Blood samples were taken at regular intervals in order to measure serum prolactin (PRL). As expected, serum PRL increased progressively and 23 days after implanting the E₂ capsules (Experimental day 0), circulating PRL had undergone a 3–4 fold increase. On Experimental day 0 part of the E₂-implanted animals received a bilateral intrapituitary injection of either an adenoviral vector expressing the gene for rat IGF-I (RAd-IGFI), or a vector (RAd-GFP) expressing the gene for green fluorescent protein (GFP). Seven days post vector injection all animals were sacrificed and their pituitaries morphometrically analyzed to evaluate changes in the lactotroph population. RAd-IGFI but not RAd-GFP, induced a significant fall in serum PRL. Furthermore, RAd-IGFI but not RAd-GFP significantly reversed the increase in lactotroph size (CS) and volume density (VD) induced by E₂ treatment.

Conclusion

We conclude that IGF-I gene therapy constitutes a potentially useful intervention for the treatment of prolactinomas and that bioactive peptide gene delivery may open novel therapeutic avenues for the treatment of pituitary tumors.