Plasma levels of leptin and soluble leptin receptor and polymorphisms of leptin gene -18G > A and leptin receptor genes K109R and Q223R, in survivors of childhood acute lymphoblastic leukemia

BACKGROUND Approximately 20% of children and adolescents in Europe are overweight. Survivors of pediatric acute lymphoblastic leukemia (ALL) are at increased risk of overweight and obesity. The purpose of this study was to assess leptin and leptin soluble receptor levels, as well as polymorphisms of selected genes in survivors of pediatric ALL, and the influence of chemo- and radiotherapy on development of overweight in the context of leptin regulation. METHODS Eighty two patients (55% males), of median age 13.2 years (m: 4.8 years; M: 26.2 years) were included in the study. The ALL therapy was conducted according to modified Berlin-Frankfurt-Munster (BFM; n = 69) regimen or New York (n = 13) regimen. In 38% of patients cranial radiotherapy (CRT) was used in median dose of 18.2Gy (m: 14Gy; M: 24Gy). Median age at diagnosis was 4.5 (m: 1 year; M: 16.9 years) and median time from completion of ALL treatment was 3.2 years (m: 0.5 year; M: 4.3 years). Patients with BMI ≥85 percentile were classified as overweight. Correlation of plasma levels of leptin and leptin soluble receptor, and polymorphisms of leptin gene -18G > A, leptin receptor genes K109R and Q223R, and the overweight status were analyzed in relation to gender, intensity of chemotherapy (high intensity vs. standard intensity regimens) and to the use of CRT. RESULTS Significant differences of leptin levels in patients treated with and without CRT, both in the entire study group (22.2+/- 3.13 ng/ml vs. 14.9+/-1.6 ng/ml; p < 0.03) and in female patients (29.9+/-4.86 ng/ml vs. 16.9+/-2.44 ng/ml; p = 0.014), were found. Significant increase of leptin levels was also found in overweight patients compared to the non-overweight patients in the entire study group (29.2+/-2.86 ng/ml vs. 12.6+/-1.51 ng/ml; p < 0.0001), female patients (35.4+/-6.48 ng/ml vs. 18.4+/-2.5 ng/ml; p = 0.005), and male patients (25.7+/-2.37 ng/ml vs. 6.9+/-0.95 ng/ml; p < 0.0001). Negative correlation was observed for plasma levels of soluble leptin receptor and overweight status, with significant differences in overweight and non-overweight patients, both in the entire study group (18.2+/-0.75 ng/ml vs. 20.98+/-0.67 ng/ml; p = 0.017) and in male patients (18.2+/-1.03 ng/ml vs. 21.8+/- 1.11 ng/ml; p = 0.038). Significant (p < 0.05) negative correlation was found between leptin and leptin receptor levels in the entire group (correlation coefficient: 0.393) and in both gender subgroups (correlation coefficient in female patients: -0.427; in male patients: -0.396). CONCLUSIONS The prevalence of overweight in our cohort was higher than in general European population (31% vs 20%) and increased regardless of the use of CRT. Leptin and leptin receptor levels may be used as useful markers of high risk of becoming overweight in ALL survivors, particularly in females treated with CRT. Polymorphisms of leptin gene -18G > A and leptin receptor genes K109R and Q223R were not associated with overweight status in ALL survivors.