Frecuencia de transcritos BCR/ABL p210 en 272 pacientes con leucemia mieloide crónica (LMC) en Bolivia / Frequency of p210 BCR-ABL transcripts in 272 Bolivian patients with chronic myeloid leukemia (CML)

INTRODUCCIÓN: existen dos formas principales del gen de fusión BCR/ABL, que involucra al exón 2 del gen ABL y a diferentes exones del gen BCR; los transcritos b2a2 o b3a2 codifican a la proteína p210, mientras que, el transcrito e1a2 codifica a la proteína p190. En Bolivia, no existe información sobre la frecuencia de estas isoformas (BCR/ABL quimérico) en pacientes con leucemia mieloide crónica (LMC). Objetivo.- Determinar la frecuencia de co-expresión de los transcritos p210 en pacientes con LMC de Bolivia. MATERIAL Y MÉTODO: se estudió 272 pacientes diagnosticados con LMC, entre julio del 1999 a agosto del 2015. Se realizó pruebas de RT-PCR (reverse transcriptase polymerase chain reaction) en muestras de médula ósea y sangre periférica de pacientes adultos y pediátricos con diagnóstico de LMC, positivos para algún tipo de reordenamiento BCR/ABL. RESULTADOS: la expresión del transcrito b2a2 se encontró en 96 pacientes (35,3%), el trascrito b3a2 en 154 casos (56,6%) y ambos transcritos en 22 pacientes (8,1%). Se realizó análisis de supervivencia, donde se observó que a los 5 años la tasa de sobrevida fue 64%; y la sobrevida libre de progresión 42%. También se observó que el tipo de transcrito no influye en la sobrevida total ni en la sobrevida libre de enfermedad. CONCLUSIÓN: se evidenció que no existen diferencias significativas de la expresión de los diferentes transcritos BCR/ABL de los pacientes estudiados en relación a otros estudios reportados.

There are two main forms of BCR/ABL fusion gene, involving exon 2 of ABL gene and different exons of the BCR gene, the transcripts b2a2 or b3a2 code for a p210 protein, and the transcript e1a2 code a p190 protein. In Bolivia, there is no information about the frequency of these isoforms of chimeric gene BCR/ABL in chronic myeloid leukemia (CML). The present study was designed to determine the frequency of co-expression of p210 transcripts in 272 patients with CML. It was conducted reverse transcriptase polymerase chain reaction (RT-PCR) tests in samples of bone marrow and peripheral blood of adult and pediatric patients with CML diagnosis, positive for some kind of BCR/ABL rearrangement. The transcript b2a2 was found in 96 (35,3%) patients; and b3a2 transcript in 154 (56.6%) cases; whereas, in 22 (8.1%) patients both transcripts were detected. Survival analysis was performed, it was observed that to 5 years the overall survival (OS) was 64%, and the progression free survival (PFS) was 42%. It was also observed that the type of transcript does not affect OS and PFS. Statistical analysis of our study, displayed no significant differences in the expression of different transcripts BCR/ABL of the Bolivian population, in relation to studies reported in other populations.

Construction of bcr-abl gene eukaryotic expressing vector and its expression in COS-7 cells / 白血病·淋巴瘤

Objective To clone and construct eukaryotic expressing vector of bcr-abl fusion gene and to express the gene in the mammal COS-7 cell lines. Methods bcr-abl fusion gene was amplified from human chronic myeloid leukemia (CML) K562 cell lines by RT-PCR and the fragment of cDNA was retrieved,purified and cloned into the pEGFP-N3 eukaryotic expressing vector. After the selection of the positive clone and by restriction enzyme analysis and DNA sequencing, the correct plasmid was transfected into COS-7 cell lines and observed the transient expression. Results A 874 bp DNA fragment was amplified by RT-PCR. The sequence analysis showed it was consistent with bcr-abl gene of GeneBank. RT-PCR, Western blotting analysis provided strong evidences that bcr-abl gene was expressed successfully in transfected COS-7 cells.Conclusion The eukaryotic expressing vector of bcr-abl fusion gene was constructed, it will lay the foundation for further study of bcr-abl gene in the diagnosis and treatment of CML.