Effect of the Adition of Metformin on the expressión of Multidrug-Resistance Genes (ABCB1, ABCG2) in Acute Lymphoblastic Leukemia: In Vitro and In Vivo Study

INTRODUCTION. The over expresión of the multidrug resistance genes (MDR) specifficaly ABCB1 and ABCG2 correlate with a poor prognosis in patients with ALL. Different drugs specially the chomotherapeutic agents are they substrates. This genes encode a family of different membrane transports that Works with energy specifically the ATP. Metformin is a biguanide whose mechanism of action is the activiation of AMPK and depletes the levels of ATP.

PRIMARY OBJECTIVE: Evaluate the efficacy of the use of Metformin on the levels of expression of the MDR genes (ABCB1 y ABCG2) by RQ-PCR in ALL cell lines and patients with ALL during a preinduction treatment with prednisone.

RESULTS.

In vitro study. The ALL cell lines RS4, ReH, MOLT4 and SUB15 were elavluated. After the addition of Metformin (10uM) the expression level of ABCB1, ABCG2 started to decrease after the 24hrs of culture (mean expression level of 0.3823 ABCB1 and 0.4265 of ABCB2) with a máximum effect at 48 hours (0.2415 ABCB1 and 0.3452 ABCB2) The difference of levels were statystically significant (p= 0.0045).

In vivo study. About 108 patients were evaluated, 44 (40.7%) in the arm of prednisone and 64 (59.3%) in the arm of prednisone plus metformin. Fort eh subanalysis of the MDR genes by RQ-PCR we select 25 patients (14 in the prednisone arm and 11 in the metformin arm). The mean levels of the genes was 0.1906 for the ABCB1 gene and 0.3371 of the ABDG2. At the moment of diagnosis about 32% were considerer with high level of expression (n=8), 28% (n=7) of low expression and 40% (n=10) do not express any of the both genes. After the treatment with Metformin 4 patients with high expression at diagnosis change the patter for low expression. Although there is no difference in means of the expression of genes in both arms (p = 0.391 , p = 0. 828) in the group of metformin the prognosis in the high expression group was better than in the prednisone arm (p=0.043). Fort he entire cohort the complete remission rate was higher in the Metformin cohort comparing with prednisone (86.4% versus 67.2%) and the refractoriness was higher in the group of prednisone (n=16, 25%) p=0.002. About the relapse, the addition of Metformin reduce the relapse rate ( 6 vs 21 patients, p = 0.027).

Conclusion. The addition of metformin in a controlled enviroment reduce the expression of the MDR genes, but in vivo the impact is primarily on the refractory leukemias and the relapse rate