Association Between the 5,10-MTHFR 677C>T and RFC1 80G>A Polymorphisms and Acute Lymphoblastic Leukemia.

BACKGROUND: Polymorphisms in folate-related genes are closely related to the development of cancer. The 5,10-MTHFR 677C>T and RFC1 80G>A polymorphisms are associated with an increased risk of susceptibility to pediatric ALL. OBJECTIVE: The aim of this study was to illustrate the association between 5,10-MTHFR 677C>T and RFC1 80G>A polymorphisms and ALL in a Mexican population. MATERIALS AND METHODS: This study was conducted in 60 pediatric ALL patients and 60 healthy individuals. The 5,10-MTHFR 677C>T and RFC1 80G>A polymorphisms were detected by the PCR-RFLP method. RESULTS: Our investigation revealed that the 5,10-MTHFR 677 C/T and 5,10-MTHFR 677T/T genotypes are associated with susceptibility to pediatric ALL (OR = 1.9, 95% IC = 1.36-12.09, p = 0.012 and OR = 2.8, 95% CI = 1.49-22.82, p = 0.011, respectively). Likewise, the G/A genotype from the RFC1 80G>A polymorphism showed an increased ALL risk compared to RFC1 G80G genotype (OR = 3. 3, 95% CI = 1.75-8.87, p = 0.002). CONCLUSION: Therefore, our results suggest that the 5,10-MTHFR 677C>T and RFC1 80G>A polymorphisms are factors involved in the susceptibility to ALL in Mexican population.

Deregulation of folate pathway gene expression correlates with poor prognosis in acute leukemia.

The present study analyzed the mRNA expression levels of genes involved in the transport and metabolism of methotrexate (MTX) (RFC1, ABCC1, ABCB1, GGH, FPGS, ATIC, TS, MTHFR, MTRR, MS and MTHFD1) in patients with acute leukemia (AL). The expression levels of the examined genes were analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in patients with AL (ALL:50/AML:19) and 66 healthy individuals. The mRNA expression levels of RFC1, MS, MTRR, MTHFR and ABCB1 were decreased (P<0.05), while those of GGH, FPGS, TS and MTHFD1 (P<0.05) were overexpressed in patients with AL. Patients with high mRNA levels of GGH (OR=4.28, 95% CI=1.29-14.14), TS (OR=7.14, 95% CI 1.84-27.81), MTHFR (OR=4.81, 95% CI=1.31-17.64), ABCB1 (OR=4.61, 95% CI=1.33-15.97) and ABCC1 (OR=5.50, 95% CI=1.12-27.06) had a higher chance of relapse. Interestingly, high mRNA levels of RFC1 are a protective factor in the risk of AL relapse (OR=0.22, 95% 0.06-0.80). The results of the present study indicated that deregulation of folate pathway gene expression is associated with poor prognosis in AL and that the expression levels of these markers could serve as novel molecular targets for the treatment of patients with AL.

Overexpression of dihydrofolate reductase is a factor of poor survival in acute lymphoblastic leukemia.

Dihydrofolate reductase (DHFR) has an important function in DNA synthesis and is a target of methotrexate, which is a crucial treatment option for acute lymphoblastic leukemia (ALL). However, the number of studies conducted to date on DHFR expression in childhood ALL is limited. The aim of the present study was to determine whether the expression of DHFR is associated with survival in childhood ALL. The expression of DHFR in 96 children with ALL and 100 control individuals was determined using reverse transcription-quantitative polymerase chain reaction. The results of the present study demonstrated that the expression of DHFR mRNA in children with ALL was significantly increased (P<0.001), compared with that in the control group. In addition, increased levels of DHFR mRNA were observed in patients with B-cell lineage, compared with patients with T-cell lineage ALL (P<0.05). The Kaplan-Meier estimator analysis revealed that children with ALL who exhibited increased levels of DHFR mRNA had a decreased overall survival time (P<0.05). It was observed that certain patient prognostic features (including age, sex, white blood cell count and high DHFR expression), are associated with poor survival (log-rank test, P<0.05). Therefore, the results of the present study indicated that DHFR upregulation is a factor for poor survival in ALL.

High miR-24 expression is associated with risk of relapse and poor survival in acute leukemia.

MicroRNAs (miRNAs) play an essential role in the development and progression of acute leukemia (AL). miR-24 promotes the survival of hematopoietic cells. However, little is known concerning the function of miR-24 in human AL. The aim of the present study was to investigate the clinical significance of miR-24 expression in AL. miR-24 expression in 147 patients with AL and 100 healthy individuals was measured by quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). The results showed that compared with the healthy individuals, the expression of miR-24 in AL patients was significantly higher (p<0.001). In addition, miR-24 was expressed at significantly higher levels in acute myeloid leukemia (AML) patients and at significantly lower levels in acute lymphoblastic leukemia (ALL) (p<0.001). More importantly, Kaplan-Meier analysis showed that AL patients with high miR-24 expression tended to have shorter overall survival (p<0.05). In the multivariate analysis stratified for known prognostic variables, miR-24 was identified as an independent prognostic marker. Our data indicated that miR-24 upregulation was associated with poor prognosis in AL. miR-24 was identified for the first time as an independent marker for predicting the clinical outcome of AL patients.

Survival and risk of relapse of acute lymphoblastic leukemia in a Mexican population is affected by dihydrofolate reductase gene polymorphisms.

Dihydrofolate reductase (DHFR) is the major target of methotrexate, a key component in childhood acute lymphoblastic leukemia (ALL) treatment. Polymorphisms in the gene coding for DHFR have been associated with adverse event treatment. This study evaluated the effect of the -A317G and C829T polymorphisms in the DHFR gene on survival and risk of relapse of ALL. Seventy patients with ALL and 100 healthy individuals were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. An association between the polymorphisms and the risk of relapse was found (p<0.05); patients with the -317G/G genotype were found to have an 8.55 (95% CI 1.84-39.70) higher chance of relapse and carriers of the 829T/T genotype had a 14.0 (95% CI 1.13-172.63) higher chance of relapse. Other variables, such as age and leukocyte count, were associated (p<0.05) with the risk of relapse of the disease. Individuals with the G/G and T/T genotype of the -A317G and C829T polymorphisms had poorer survival compared to other genotype groups (log-rank test; p<0.05). Although preliminary, these data seem to suggest a role for the DHFR polymorphisms in the risk of relapse of ALL and the mortality risk in these patients.

Polymorphisms of the gamma-glutamyl hydrolase gene and risk of relapse to acute lymphoblastic leukemia in Mexico.

This study evaluated the association of -401C/T and +452C/T polymorphisms of gamma-glutamyl hydrolase and the risk of relapse to acute lymphoblastic leukemia. Genotyping was performed in 70 children with acute lymphoblastic leukemia and 140 healthy children. An association between the -401C/T polymorphism and the risk of relapse was found (p=0.028), patients with the -401T/T genotype have 10.83 (95% CI 1.30-90.14) more chance of a relapse of leukemia. No association was found between the +452C/T polymorphism and the risk of relapse. Therefore, our investigation suggests that the -401C/T polymorphism in the gamma-glutamyl hydrolase may be a factor involved in the generation of relapse to disease in patients with ALL.

Sarcomas de partes blandas en la infancia / Chilhood soft tissue sarcomas

Se revisaron los expedientes de 72 pacientes con diagnóstico de sarcoma de partes blandas, registrados entre 1980 y 1994 en el Instituto Nacional de Pediatría de México. La edad promedio entre los casos con rabdomiosarcoma fue de 5.9 años y de 10.3 años en los que tenían no-rabdomiosarcomas. El 86 por ciento de los casos correspondieron a rabdomiosarcomas y el 14 por ciento restante no-rabdomiosarcomas. El tipo histológico más común en los rabdomiosarcoma fue el embrionario, seguido por la variedad alveolar. El 95 por ciento de los rabdiomiosarcomas se diagnosticaron en estadio III y IV. Se revisaron dos grupos de tratamiento: un grupo de enfermos tratados entre 1980 y 1990 con el esquema VC (vincristina, actinomicina D y ciclofosfamida) y otro de pacientes tratados entre 1990 y 1994 con VACP (esquema VAC más cisplatino); no hubo diferencia entre uno y otro grupos en cuanto a la supervivencia (p = 0.11). Se detectaron 10 casos de sarcomas no-rabdomiosarcomas; el más frecuente (50 por ciento de los casos) fue el Schwanoma maligno; todos los pacientes acudieron en etapas avanzadas; de éstos, sólo cuatro se encuentran con vida

Toxicidad a la L-asparaginasa en pacientes con leucemia aguda linfoblástica / Toxicity to L-asparaginase in patients with acute lymphoblastic leukemia

Antecedentes. La L-asparaginasa es una enzima extraída de Erwinia caratovora y Escherichia coli que ha sido aceptada para el tratamiento de inducción y consolidación en pacientes con leucemia aguda linfoblástica (LAL) y linfoma no Hodgkin; produce una prolongada remisión. Material y métodos. En el Hospital Infantil Privado en un periodo de dos años (1990-1992) se estudiaron 20 pacientes con LAL; recibieron L-asparaginasa; se registraron las complicaciones, la frecuencia y el tiempo de aparición de éstas. Resultados. Un paciente presentó hipersensibilidad tipo l (rash, rubicundez, broncoespasmo, etc.); otro tuvo hiperglicemia, pancreatitis y hemorragia cerebral fatal. En 13 casos hubo plaquetopenia. Hubo tres defunciones por hemorragia cerebral tres semanas después de la aplicación del medicamento; uno de estos pacientes tuvo tiempo parcial de tromboplastina prolongado y otro, alteración del fibrinógeno. Conclusiones. La L-asparaginasa es útil y necesaria para alargar el tiempo de remisión de la LAL. Los pacientes que reciben L-asparaginasa deben ser vigilados estrechamente para detectar hipersensibilidad tipo l, hipofibrinogenemia, hipergilcemia, hiperamonemia, pancreatitis o quiste pseudopancreático