Molecular and Clinical Insights in the Increasing Detection of BCR::ABL1 p190+ in Adult Acute Myeloid Leukemia Patients.

BACKGROUND/AIM: Acute myeloid leukemia (AML) is a myeloproliferative neoplasm marked by abnormal clonal expansion of hematopoietic progenitor cells, displaying karyotypic aberrations and genetic mutations as prognostic indicators. The World Health Organization (WHO) and the European LeukemiaNet guidelines categorize BCR::ABL1 p190+ AML as high risk. This study explored the identification of the increased incidence of BCR::ABL1 p190+ in our AML population. PATIENTS AND METHODS: This study included 96 AML patients stratified according to WHO guidelines. Subsequently, patients were screened for genetic abnormalities, such as BCR::ABL1 p 190+, PML::RARA, RUNX1::RUNX1T1, and CBFB::MYH11 by quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis. RESULTS: Among 96 AML patients, 36 displayed BCR::ABL1 p190+, overcoming the expected global incidence. Age variations (19 to 78 years) showed no significant laboratory differences between BCR::ABL1 p190+ and non-BCR::ABL p190+ cases. The overall survival analysis revealed no statistically significant differences among the patients (p=0.786). CONCLUSION: The analyzed population presented a higher frequency of BCR::ABL1 p190+ detection in adult AML patients when compared to what is described in the worldwide literature. Therefore, more studies are needed to establish the reason why this incidence is higher and what the best treatment approach should be in these cases.

Unraveling the evolutionary origin of the P5CS gene: a story of gene fusion and horizontal transfer.

The accumulation of proline in response to the most diverse types of stress is a widespread defense mechanism. In prokaryotes, fungi, and certain unicellular eukaryotes (green algae), the first two reactions of proline biosynthesis occur through two distinct enzymes, γ-glutamyl kinase (GK E.C. 2.7.2.11) and γ-glutamyl phosphate reductase (GPR E.C. 1.2.1.41), encoded by two different genes, ProB and ProA, respectively. Plants, animals, and a few unicellular eukaryotes carry out these reactions through a single bifunctional enzyme, the Δ1-pyrroline-5-carboxylate synthase (P5CS), which has the GK and GPR domains fused. To better understand the origin and diversification of the P5CS gene, we use a robust phylogenetic approach with a broad sampling of the P5CS, ProB and ProA genes, including species from all three domains of life. Our results suggest that the collected P5CS genes have arisen from a single fusion event between the ProA and ProB gene paralogs. A peculiar fusion event occurred in an ancestral eukaryotic lineage and was spread to other lineages through horizontal gene transfer. As for the diversification of this gene family, the phylogeny of the P5CS gene in plants shows that there have been multiple independent processes of duplication and loss of this gene, with the duplications being related to old polyploidy events.

A Review on Anaplastic Lymphoma Kinase (ALK) Rearrangements and Mutations: Implications for Gastric Carcinogenesis and Target Therapy.

Gastric adenocarcinoma is a complex disease with diverse genetic modifications, including Anaplastic Lymphoma Kinase (ALK) gene changes. The ALK gene is located on chromosome 2p23 and encodes a receptor tyrosine kinase that plays a crucial role in embryonic development and cellular differentiation. ALK alterations can result from gene fusion, mutation, amplification, or overexpression in gastric adenocarcinoma. Fusion occurs when the ALK gene fuses with another gene, resulting in a chimeric protein with constitutive kinase activity and promoting oncogenesis. ALK mutations are less common but can also result in the activation of ALK signaling pathways. Targeted therapies for ALK variations in gastric adenocarcinoma have been developed, including ALK inhibitors that have shown promising results in pre-clinical studies. Future studies are needed to elucidate the ALK role in gastric cancer and to identify predictive biomarkers to improve patient selection for targeted therapy. Overall, ALK alterations are a relevant biomarker for gastric adenocarcinoma treatment and targeted therapies for ALK may improve patients' overall survival.

Pilocytic astrocytoma in adults: Histopathological, immunohistochemical and molecular study with clinical association.

Pilocytic astrocytoma is the most common primary CNS neoplasm in children and adolescents, rare after the first two decades of life. While some authors report a favorable prognosis in the adult age group with the tumor, others have associated it with higher mortality. The molecular alteration most observed in cases of pilocytic astrocytoma in the pediatric group is the BRAF-KIAA1549 gene fusion, and there are still few studies confirming the presence of this fusion in the adult population. This work investigated genetic alterations involving the 7q34 region in BRAF gene in 21 adult individuals with pilocytic astrocytoma, by FISH. In addition, was identified the immunohistochemical expression of BRAFV600E, correlating these findings with histopathological and clinical ones. BRAF-KIAA1549 fusion appeared in only one case, while in two other cases were found deletions related to the FAM131B-BRAF fusion, suggesting that maybe the latter is more frequently in this population. Through the evaluation of immunoreactivity, 71% of the cases were considered positive and 29% negative. Cases considered positive for BRAFV600E immunoreactivity can potentially be treated through drug therapy with BRAF inhibitors; however, it is always recommended to carry out a molecular study for diagnostic confirmation. This is the first Brazilian study that aimed to investigate possible genetic alterations in the BRAF gene in pilocytic astrocytomas, specifically in adults. Only 1 patient died, but due to operative complications and not the disease itself, suggesting a good evolution of these individuals.

A novel approach for direct detection of the IGH::CRLF2 gene fusion by fluorescent in situ hybridization.

BACKGROUND: High expression of the Cytokine Receptor-Like Factor 2 (CRLF2) gene has been observed in patients with acute lymphoblastic leukemia BCR-ABL1-like subtype. Currently, there is no commercial system available for the direct detection of the IGH::CRLF2 fusion by fluorescent in situ hybridization (FISH), as there are for many other leukemia-related gene fusions. In an effort to verify the IGH::CRLF2 fusion, some researchers prepare home-grown FISH probes from bacterial artificial chromosome clones flanking the IGH and CRLF2 genes, which is the best alternative to confirm the fusion, however difficult to reproduce in most cytogenetic laboratories. RESULTS: For the direct observation of the IGH::CRLF2 gene fusion we designed a methodological approach requiring the two commercially available IGH and CRLF2 break-apart probes. CONCLUSIONS: Our methodological approach allows direct visualization of the IGH::CRLF2 gene fusion and has the potential to be used for identification of other gene fusions.

Tumor condromixoide ectomesenquimal: uma revisão sistemática e análise molecular de um caso extralingual / Ectomesenchymal chondromyxoid tumor: a systematic review and molecular analysis of an extra-lingual case

O tumor condromixoide ectomesenquimal (TCE) é uma neoplasia benigna rara, que afeta principalmente a língua e que exibe alta frequência da fusão RREB1-MRTFB. Microscopicamente, o TCE se assemelha com outras lesões condromixoides, sendo o mioepitelioma um dos principais desafios de diferenciação. Seu diagnóstico requer além da análise microscópica, a imuno-histoquímica. Revisões narrativas sobre o TCE já realizadas não contemplam uma análise sistemática da literatura. A fusão RREB1- MRTFB apesar de frequente em língua, foi positiva em um caso intra-ósseo, não tendo sido ainda descrita nos tecidos moles orais extra lingual. Sendo assim, o objetivo desse estudo foi sistematizar os dados da literatura com ênfase na microscopia do TCE, e relatar um caso extra lingual investigando a fusão RREB1-MRTFB. Uma busca eletrônica em 5 bases foi realizada em dezembro de 2021. Um total de 44 artigos com 101 casos de TCE foram incluídos. Microscopicamente, o TCE mostrou-se não encapsulado (95,5%), porém circunscrito (89,2%), de aspecto lobular (70,6%), entremeado por septos fibrosos (98%), sendo uma proliferação sólida em lençol, ilhas ou cordões (98%), em um padrão reticular (98,3%), cujas células eram fusiformes (77,5%), redondas e ovoides (70,6%) ou poligonais (54,9%), com citoplasma eosinofílico (34,3%), imersas em uma matriz mixoide (97,0%), condroide (88,0%) ou mixocondroide (X%). Na imuno-histoquímica as células mostraram maior positividade para vimentina (100%), GFAP (88,9%), S-100 (85,7%), CD56 (76,9%) e CD57 (75%). A fusão RREB1-MRTFB ocorreu em n=20/23; 87,0%. O presente caso clínico relatado é de um nódulo em face lingual da mandíbula em jovem de 15 anos, cuja morfologia mostrava as características mais frequentemente identificadas na revisão sistemática. A análise molecular confirmou o diagnóstico de TCE. O estudo contribui para um detalhamento das características morfológicas diagnósticas do TCE, bem como expandiu o conhecimento molecular do tumor em um caso extra lingual de um indivíduo brasileiro.

The ectomesenchymal chondromyxoid tumor (ECMT) is a rare benign neoplasm that mainly affects the tongue and exhibits a high frequency of the RREB1-MRTFB fusion. Microscopically, ECMT resembles other chondromyxoid lesions, with myoepithelioma being one of the main differentiation challenges. Its diagnosis requires not only microscopic analysis but also immunohistochemistry. Narrative reviews on ECMT conducted so far do not encompass a systematic analysis of the literature. The RREB1-MRTFB fusion, despite being frequent in the tongue, has been tested positive in an intraosseous case, and it has not yet been described in extra-lingual oral soft tissues.Therefore, the aim of this study was to systematize the literature data with an emphasis on ECMT microscopy and report an extra-lingual case investigating the RREB1-MRTFB fusion. An electronic search across 5 databases was conducted in December 2021. A total of 44 articles comprising 101 cases of ECMT were included. Microscopically, ECMT was found to be non-encapsulated (95.5%), yet circumscribed (89.2%), exhibiting a lobular appearance (70.6%), interspersed with fibrous septa (98%), forming a solid proliferation in sheets, strands and cords (98%) in a reticular pattern (98.3%). The cells were spindle-shaped (77.5%), round and ovoid (70.6%), or polygonal (54.9%), with eosinophilic cytoplasm (34.3%), embedded in a myxoid matrix (97.0%), and chondroid (88.0%). Immunohistochemically, there was higher positivity for vimentin (100%), GFAP (88.9%), S-100 (85.7%), CD56 (76.9%), and CD57 (75%). The RREB1-MRTFB fusion occurred in n=20/23; 87,0%. The present clinical case reportes a nodule on the lingual aspect of the mandible in a 15-year-old individual, whose morphology exhibited the most frequently identified characteristics in the systematic review. The molecular analysis confirmed the diagnosis of ECMT. The present study not only contributes to a detailed understanding of the morphological diagnostic features of ECMT but also expands the molecular knowledge of the tumor based in an extra-lingual case of a Brazilian individual.

XAC4296 Is a Multifunctional and Exclusive Xanthomonadaceae Gene Containing a Fusion of Lytic Transglycosylase and Epimerase Domains.

Microorganisms have a limited and highly adaptable repertoire of genes capable of encoding proteins containing single or variable multidomains. The phytopathogenic bacteria Xanthomonas citri subsp. citri (X. citri) (Xanthomonadaceae family), the etiological agent of Citrus Canker (CC), presents a collection of multidomain and multifunctional enzymes (MFEs) that remains to be explored. Recent studies have shown that multidomain enzymes that act on the metabolism of the peptidoglycan and bacterial cell wall, belonging to the Lytic Transglycosylases (LTs) superfamily, play an essential role in X. citri biology. One of these LTs, named XAC4296, apart from the Transglycosylase SLT_2 and Peptidoglycan binding-like domains, contains an unexpected aldose 1-epimerase domain linked to the central metabolism; therefore, resembling a canonical MFE. In this work, we experimentally characterized XAC4296 revealing its role as an MFE and demonstrating its probable gene fusion origin and evolutionary history. The XAC4296 is expressed during plant-pathogen interaction, and the Δ4296 mutant impacts CC progression. Moreover, Δ4296 exhibited chromosome segregation and cell division errors, and sensitivity to ampicillin, suggesting not only LT activity but also that the XAC4296 may also contribute to resistance to ß-lactams. However, both Δ4296 phenotypes can be restored when the mutant is supplemented with sucrose or glutamic acid as a carbon and nitrogen source, respectively; therefore, supporting the epimerase domain's functional relationship with the central carbon and cell wall metabolism. Taken together, these results elucidate the role of XAC4296 as an MFE in X. citri, also bringing new insights into the evolution of multidomain proteins and antimicrobial resistance in the Xanthomonadaceae family.

Corrigendum: Salivary Gland Carcinoma: Novel Targets to Overcome Treatment Resistance in Advanced Disease.

[This corrects the article DOI: 10.3389/fonc.2020.580141.].

Revealing the BRD4-NOTCH3 fusion: A novel hill in the cancer landscape.

OBJECTIVES: Gene fusions are becoming more evident in cancer scenario for either being the driver alterations, or for the great therapeutic target potential in many cases. Our aim was to characterize the BRD4-NOTCH3 fusion correlating with clinical features, and to determine the frequency of this fusion in the oncological population. MATERIAL AND METHODS: One patient diagnosed with lung adenocarcinoma at Hospital Sírio-Libanês (Brazil) was included. Foundation Medicine database was searched for all BRD4-NOTCH3 fusions among 233,804 specimens. RESULTS: A 76-year-old male patient was diagnosed with lung adenocarcinoma. Molecular assessments demonstrated negative ALK and EGFR, with PD-L1 expression positive by 60 %. He was treated with first line chemotherapy and second line immunotherapy. Subsequent treatments resume re-exposures to chemotherapy with poor responses. A next-generation sequencing (NGS) based assay was performed in the tumor biopsy, revealing mainly mutation in STK11, microsatellite stability, TMB-intermediate, MYC amplification and a BRD4-NOTCH3 fusion. The breakpoint analysis of this fusion indicates that BRD4 active domains are preserved, suggesting that it maintained DNA binding activity, as well as its capacity to be halt by BET inhibitors. Foundation Medicine database was searched for all BRD4-NOTCH3 fusions among more than 230-thousand specimens and it was found in 87 new cases in a rate of 0.04 % occurrence in solid tumors, predominately in gynecological cancers. The same rate was found when we analyzed a different dataset. CONCLUSION: In conclusion, this is the first report of the BRD4-NOTCH3 gene fusion associated with clinical characterization and, although rare, the occurrence of this fusion is constant in different population. Our data suggest that this fusion has great potential to targeted-therapy.

Salivary Gland Carcinoma: Novel Targets to Overcome Treatment Resistance in Advanced Disease.

Salivary gland carcinomas (SGCs) account for <5% of head and neck malignant neoplasms, further subcategorized in over 20 histological subtypes. For the most part, treatment for advanced disease is guided by morphology. SGCs in general respond poorly to a wide array of standard chemotherapy, with short durability, and significant toxicity. More recently, next-generation sequencing provided significant input on the molecular characterization of each SGC subtype, not only improving diagnostic differentiation between morphologically similar tumor types but also identifying novel driver pathways that determine tumor biology and may be amenable to targeted therapy. Among the most common histological subtype is adenoid cystic carcinoma, which often harbors a chromosome translocation resulting in an MYB-NFIB oncogene, with various degrees of Myb surface expression. In a smaller subset, NOTCH1 mutations occur, conferring a more aggressive pattern and potential sensitivity to Notch inhibitors. Salivary duct carcinomas may overexpress Her-2 and androgen receptors, with promising clinical outcomes after exposure to targeted therapies approved for other indications. Secretory carcinoma, previously known as mammary analog secretory carcinoma, is distinguished by an ETV6-NTRK3 fusion that can both help differentiate it from its morphologically similar acinar cell carcinoma and make it susceptible to Trk inhibitors. In the present article, we discuss the molecular abnormalities, their impact on tumor biology, and therapeutic opportunities for the most common SGC subtypes and review published and ongoing clinical trials and future perspectives for this rare disease.

Pilocytic Astrocytoma: A Review of General, Clinical, and Molecular Characteristics.

Pilocytic astrocytomas are the primary tumors most frequently found in children and adolescents, accounting for approximately 15.6% of all brain tumors and 5.4% of all gliomas. They are mostly found in infratentorial structures such as the cerebellum and in midline cerebral structures such as the optic nerve, hypothalamus, and brain stem. The present study aimed to list the main characteristics about this tumor, to better understand the diagnosis and treatment of these patients, and was conducted on search of the published studies available in NCBI, PubMed, MEDLINE, Scielo, and Google Scholar. It was possible to define the main histologic findings observed in these cases, such as mitoses, necrosis, and Rosenthal fibers. We described the locations usually most affected by tumor development, and this was associated with the most frequent clinical features. The comparison between the molecular diagnostic methods showed great use of fluorescent in situ hybridization, polymerase chain reaction (PCR), and reverse transcriptase-PCR, important techniques for the detection of BRAF V600E mutation and BRAF-KIAA1549 fusion, characteristic molecular alterations in pilocytic astrocytomas.

Clear Cell Odontogenic Carcinoma Harboring the EWSR1-ATF1 Fusion Gene: Report of a Rare Case.

Clear cell odontogenic carcinoma (CCOC) is a rare and aggressive malignant epithelial neoplasm, which occurs most frequently in the mandible of elderly patients. Morphologically, CCOC shares similar characteristics with other clear cell tumors, especially hyalinizing clear cell carcinoma of the salivary glands (HCCC). Both CCOC and HCCC are known to harbor EWSR1 rearrangements, especially the EWSR1-ATF1 gene fusion, which indicates a possible link between the two lesions. So far, this fusion has been demonstrated in five cases of CCOC in the literature. Herein, we add another CCOC case to the literature, which arose in the mandible of an 82-year-old female patient and was proven to harbor the EWSR1-ATF1 gene fusion. Immunohistochemically, this case was focally positive for CK7, CK14, CK19 and p63. The patient was referred to surgical treatment; however, she died of disease 2 months after the diagnosis, thereby demonstrating the aggressive nature of this tumor.

A genomic case study of desmoplastic small round cell tumor: comprehensive analysis reveals insights into potential therapeutic targets and development of a monitoring tool for a rare and aggressive disease.

BACKGROUND: Genome-wide profiling of rare tumors is crucial for improvement of diagnosis, treatment, and, consequently, achieving better outcomes. Desmoplastic small round cell tumor (DSRCT) is a rare type of sarcoma arising from mesenchymal cells of abdominal peritoneum that usually develops in male adolescents and young adults. A specific translocation, t(11;22)(p13;q12), resulting in EWS and WT1 gene fusion is the only recurrent molecular hallmark and no other genetic factor has been associated to this aggressive tumor. Here, we present a comprehensive genomic profiling of one DSRCT affecting a 26-year-old male, who achieved an excellent outcome. METHODS: We investigated somatic and germline variants through whole-exome sequencing using a family based approach and, by array CGH, we explored the occurrence of genomic imbalances. Additionally, we performed mate-paired whole-genome sequencing for defining the specific breakpoint of the EWS-WT1 translocation, allowing us to develop a personalized tumor marker for monitoring the patient by liquid biopsy. RESULTS: We identified genetic variants leading to protein alterations including 12 somatic and 14 germline events (11 germline compound heterozygous mutations and 3 rare homozygous polymorphisms) affecting genes predominantly involved in mesenchymal cell differentiation pathways. Regarding copy number alterations (CNA) few events were detected, mainly restricted to gains in chromosomes 5 and 18 and losses at 11p, 13q, and 22q. The deletions at 11p and 22q indicated the presence of the classic translocation, t(11;22)(p13;q12). In addition, the mapping of the specific genomic breakpoint of the EWS-WT1 gene fusion allowed the design of a personalized biomarker for assessing circulating tumor DNA (ctDNA) in plasma during patient follow-up. This biomarker has been used in four post-treatment blood samples, 3 years after surgery, and no trace of EWS-WT1 gene fusion was detected, in accordance with imaging tests showing no evidence of disease and with the good general health status of the patient. CONCLUSIONS: Overall, our findings revealed genes with potential to be associated with risk assessment and tumorigenesis of this rare type of sarcoma. Additionally, we established a liquid biopsy approach for monitoring patient follow-up based on genomic information that can be similarly adopted for patients diagnosed with a rare tumor.

Identificação e caracterização molecular de duas fusões gênicas recorrentes em leucemia mielóide aguda: ETV6-ANLN e NPM1-HAUS1 / Identification and molecular characterization of two recurrente gene fusions in acute myeloid leukemia: ETV6-ANLN and NPM1-HAUS1

Leucemia Mielóide Aguda (LMA) é uma neoplasia hematológica associada a alta morbidade e mortalidade. Os mecanismos genômicos causadores da LMA são diversos e incluem mutações em ponto, inserções, deleções, alterações do número de cópias, na metilação e translocações cromossômicas. Enquanto os genes envolvidos nas translocações cromossômicas mais frequentemente encontradas em LMA já tenham sido identificados, ainda existem dezenas de translocações cromossômicas recorrentes cujos genes envolvidos nos pontos de quebra cromossômicos não são conhecidos. Esta identificação é essencial para a melhor compreensão dos mecanismos da leucemogênese e muitas vezes podem ter um impacto clínico, modificando a estratificação prognóstica ou a conduta terapêutica. No presente trabalho, através da técnica de sequenciamento de DNA de nova geração, identificamos os genes envolvidos em duas translocações cromossômicas recorrentes em LMA: t(7;12)(p15:p13) e t(5;18)(q35;q21) que levam aos genes de fusão ETV6-ANLN e NPM1-HAUS1 respectivamente. A fusão ETV6-ANLN justapõe o exon 1 do gene ETV6 aos exons 2 a 25 do gene ANLN, gerando uma proteína bastante similar ao ANLN selvagem. Esta fusão gênica é expressa em precursores hematopoiéticos CD34+ e nas linhagens granulocítica e linfoide T, tendo provavelmente ocorrido em uma célula tronco hematopoiética ou em um precursor comum linfóide e mielóide. A fusão NPM1-HAUS1 justapõe os exons 1 a 11 do gene NPM1 ao exon 9 do gene HAUS1, gerando uma proteína similar ao NPM1, porém com a presença de um sinal de exportação nuclear na porção C-terminal da proteína. Como consequência, a proteína híbrida NPM1-HAUS1 localiza-se no núcleo e no citoplasma, ao contrário da NPM1 selvagem que tem localização exclusivamente nuclear. Como a localização citoplasmática da proteína NPM1 é leucemogênica em outros contextos, esse é provavelmente o mecanismo leucemogênico inicial associado a esta translocação cromossômica. Em conclusão, nós identificamos e caracterizamos duas novas fusões gênicas recorrentes em LMA. (AU)

Acute Myeloid Leukemia (AML) is a neoplastic myeloid disease characterized by progressive substitution of normal hematopoiesis by leukemic blasts that is associated with high morbidity and mortality. AML is a genomic disease caused by distinct genomic mechanisms such as single nucleotide substitutions, insertions, deletions, copy number variations and chromosomal translocations. While the genes involved in common chromosomal translocations have been well studied, there are several recurrent chromosomal translocations for which the affected genes have not been characterized. The identifications of such genes is essential for better understanding of AML pathophysiology and has the potential to improve diagnostic, prognostic and the therapeutic approach of patients harboring such chromosomal translocations. In the present study we have identified the genes involved in two recurring chromosomal translocations in AML by means of next generation DNA sequencing: t(7;12)(p15:p13) and t(5;18)(q35;q21) that lead to the gene fusions ETV6-ANLN and NPM1-HAUS1 respectively. The gene fusion ETV6-ANLN juxtaposes ETV6 exon 1 to ANLN exons 2 to 25, culminating with a putative protein highly similar to wild type ANLN. This gene fusion is expressed in hematopoietic precursors, granulocytes and T cell lymphocytes, probably occurring in a hematopoietic stem cell or a common myeloid lymphoid precursor. The gene fusion NPM1-HAUS1 leads to the fusion of NPM1 exons 1 to 11 to HAUS1 exon 9, generetaing a putative protein similar to wild type NPM1 with the addition of a novel nuclear export signal (NES) in the C-terminal region of the protein. Regarding subcellular localization, NPM1-HAUS1 localizes in the nucleus and cytoplasm in opposition to wild type NPM1 that localizes exclusively in the nucleus. Since NPM1 cytoplasmic localization has been shown to be associated with leukemogenesis, this is probably the neoplastic mechanism associated with this gene fusion. In conclusion, we have described and characterized two novel gene fusions associated with recurrent chromosomal translocations in AML. (AU)

Identificação e caracterização molecular de duas fusões gênicas recorrentes em leucemia mielóide aguda: ETV6-ANLN e NPM1-HAUS1

Leucemia Mielóide Aguda (LMA) é uma neoplasia hematológica associada a alta morbidade e mortalidade. Os mecanismos genômicos causadores da LMA são diversos e incluem mutações em ponto, inserções, deleções, alterações do número de cópias, na metilação e translocações cromossômicas. Enquanto os genes envolvidos nas translocações cromossômicas mais frequentemente encontradas em LMA já tenham sido identificados, ainda existem dezenas de translocações cromossômicas recorrentes cujos genes envolvidos nos pontos de quebra cromossômicos não são conhecidos. Esta identificação é essencial para a melhor compreensão dos mecanismos da leucemogênese e muitas vezes podem ter um impacto clínico, modificando a estratificação prognóstica ou a conduta terapêutica. No presente trabalho, através da técnica de sequenciamento de DNA de nova geração, identificamos os genes envolvidos em duas translocações cromossômicas recorrentes em LMA: t(7;12)(p15:p13) e t(5;18)(q35;q21) que levam aos genes de fusão ETV6-ANLN e NPM1-HAUS1 respectivamente. A fusão ETV6-ANLN justapõe o exon 1 do gene ETV6 aos exons 2 a 25 do gene ANLN, gerando uma proteína bastante similar ao ANLN selvagem. Esta fusão gênica é expressa em precursores hematopoiéticos CD34+ e nas linhagens granulocítica e linfoide T, tendo provavelmente ocorrido em uma célula tronco hematopoiética ou em um precursor comum linfóide e mielóide. A fusão NPM1-HAUS1 justapõe os exons 1 a 11 do gene NPM1 ao exon 9 do gene HAUS1, gerando uma proteína similar ao NPM1, porém com a presença de um sinal de exportação nuclear na porção C-terminal da proteína...

Acute Myeloid Leukemia (AML) is a neoplastic myeloid disease characterized by progressive substitution of normal hematopoiesis by leukemic blasts that is associated with high morbidity and mortality. AML is a genomic disease caused by distinct genomic mechanisms such as single nucleotide substitutions, insertions, deletions, copy number variations and chromosomal translocations. While the genes involved in common chromosomal translocations have been well studied, there are several recurrent chromosomal translocations for which the affected genes have not been characterized. The identifications of such genes is essential for better understanding of AML pathophysiology and has the potential to improve diagnostic, prognostic and the therapeutic approach of patients harboring such chromosomal translocations. In the present study we have identified the genes involved in two recurring chromosomal translocations in AML by means of next generation DNA sequencing: t(7;12)(p15:p13) and t(5;18)(q35;q21) that lead to the gene fusions ETV6-ANLN and NPM1-HAUS1 respectively. The gene fusion ETV6-ANLN juxtaposes ETV6 exon 1 to ANLN exons 2 to 25, culminating with a putative protein highly similar to wild type ANLN. This gene fusion is expressed in hematopoietic precursors, granulocytes and T cell lymphocytes, probably occurring in a hematopoietic stem cell or a common myeloid lymphoid precursor. The gene fusion NPM1-HAUS1 leads to the fusion of NPM1 exons 1 to 11 to HAUS1 exon 9, generetaing a putative protein similar to wild type NPM1 with the addition of a novel nuclear export signal (NES) in the C-terminal region of the protein...

Conventional and molecular cytogenetic characterization of Burkitt lymphoma with bone marrow involvement in Brazilian children and adolescents.

BACKGROUND: Burkitt lymphoma/leukemia (BL/L) is cytogenetically characterized by the t(8;14)(q24;q32) or its variants, t(2;8)(p11;q21), and t(8;22)(q24;q11.2), which juxtapose the MYC oncogene to one of the three immunoglobulin loci. The overall cure rate of BL/L in children is 70-90%, but patients diagnosed with advanced-stage disease have a less favorable prognosis. It is possible that secondary chromosomal abnormalities contribute to this unfavorable prognosis via chemotherapy resistance, but the results of genetic studies have been inconsistent. This study aimed to identify and characterize secondary chromosomal abnormalities associated with the t(8;14) and its variants in children with French-American-British-L3 leukemia or Burkitt lymphoma with bone marrow involvement at the time of diagnosis. PROCEDURE: Chromosome analysis was based on G-banding. Fluorescence in situ hybridization technique was applied using IGH/MYC/CEP8 dual-fusion and MYC break-apart probes. Multicolor chromosome banding was performed according to standard protocol. RESULTS: We describe a group of BL/L with extreme adverse clinical outcome, in which secondary chromosomal abnormalities, particularly those involving the long arms of chromosomes 1 and 13, were found in 71% of cases. The IGH/MYC fusion showed molecular heterogeneity in 14% of cases and two cases exhibited three IGH/MYC fusion signals. CONCLUSIONS: Secondary chromosomal abnormalities were found in a high proportion of patients. We observed an extent of IGH/MYC heterogeneity not previously reported in Burkitt lymphoma, including the novel finding of three fusion signals in two cases.

Subtipos moleculares de PML/RARα en pacientes con leucemia promielocítica aguda / Molecular subtypes of PML/RARα in patients with acute promyelocytic leukemia

El objetivo fue describir la frecuencia de los subtipos moleculares de PML/RARα en pacientes con leucemia promielocítica aguda (LPA) y su distribución según grupo de riesgo de recaída y citomorfología. Se realizó una serie de casos que incluyó a cincuenta pacientes registrados en el Instituto Nacional de Enfermedades Neoplásicas (INEN), durante el periodo 2010-2012, con diagnóstico molecular de LPA PML/RARα y subtipos bcr1, bcr2 y bcr3 por reacción en cadena de la polimerasa con transcriptasa reversa (RT-PCR). El subtipo bcr1 fue el más frecuente (62%). Los pacientes con riesgo de recaída intermedio y morfología hipergranular fueron, en su mayoría, bcr1 (70%) y todos los que poseían riesgo de recaída alto y morfología hipogranular fueron bcr3. Se concluye que en la población estudiada hay un predomino del subtipo bcr1 y que existen diferencias en la distribución de los subtipos bcr1 y bcr3 según el grupo de riesgo de recaída y citomorfología.

The objective was to describe the frequency of molecular subtypes of PML/RARα in patients with acute promyelocytic leukemia (APL) and their distribution according to risk of recurrence and cytomorphology. A case series was carried out, including fifty patients registered at the National Institute of Neoplastic Diseases (INEN) during 2010-2012, with molecular diagnosis of APL PML/RARα and bcr1, bcr2 and bcr3 subtypes by reverse-transcription polymerase chain reaction (RT-PCR). Bcr1 subtype was the most frequent (62%). Most patients with an intermediate risk of recurrence and hypergranular morphology were bcr1 (70%), while all patients with high risk of recurrence and hypogranular morphology were bcr3. A predominance of bcr1 subtype among the population studied can therefore be concluded, as well as the fact that there are differences in the distribution of bcr1 and bcr3 subtypes according to recurrence risk group and cytomorphology.