Association between (GT)n repeats in heme oxygenase-1 gene promoter and 3-year survival of patients with acute leukemia: A controlled, cross-sectional study

Background: Acute leukemia is a common pediatric cancer. Novel strategies for treatment of acute leukemia have been developed, but treatment resistance has remained as the most problematic issue. It is hypothesized that the HO-1 gene up-regulation is responsible for tumor resistance to chemotherapy or radiotherapy-induced apoptosis. HO-1 expression levels have been related to (GT) n microsatellite polymorphisms in the location of its promoter.This study designed to compare allelic frequencies of (GT) n microsatellite polymorphisms in HO-1 gene between acute leukemia patients and healthy controls. Indeed, 3-year disease-free survival was also evaluated. Materials and Methods: The study included 63 acute leukemia patients and 70 healthy infants. We used patient’s medical records to collect data regarding the post-chemotherapy survival. The number of GT repeats in HO-1 promoter was determined by an ABI 3100 sequencer. Results: The HO-1 GT repeats ranged from 14 to 34 with peaks at 27 repeats in both cases and controls. Children with longer alleles ((GT) n ≥ 27) had enhanced 3-year survival rate after treatment with chemotherapy or radiotherapy (P<0.05). Conclusion: Although no significant differences were observed between leukemia patients and controls regarding allelic frequency, we found elevated frequency of “LL” genotype in leukemia patients with good 3-year surveillance. Radiotherapy and chemotherapy might elevate the expression levels of HO-1 with subsequent increased resistance of leukemia patients to therapy.