ABSTRACT
AIM: The objective of this study was to investigate expression of drug resistance associated genes in CD34+ and CD34- leukemic subpopulations in childhood acute lymphoblastic leukemia (ALL). METHODS: ALL samples with heterogeneous CD34 expression were separated into CD34-positive and CD34-negative subpopulations and mRNA levels of MDR1, LRP, BCRP and BCL-2 genes were compared. RESULTS: BCL-2 gene expression levels did not differ significantly between CD34+ vs CD34- subpopulations in most analyzed ALL cases. Oppositely, MDR1 gene had >two-fold differences in expression levels between subpopulations in the majority of ALL cases. In T-lineage ALL CD34- fractions had increased level of BCRP and LRP genes in comparison with CD34+ ones whereas in most of B-lineage ALL expression of these genes did not differ. CONCLUSION: It was not found the unique pattern of resistance related genes expression in CD34+ vs CD34- subpopulations. However, in majority of studied pediatric ALL cases with CD34 heterogeneous expression one of subpopulations (positive or negative) could have an advantage for survival through elevated expression of drug resistance related genes.
Subject(s)
Antigens, CD34/analysis , Drug Resistance, Neoplasm/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP Binding Cassette Transporter, Subfamily G, Member 2 , ATP-Binding Cassette Transporters/genetics , Adolescent , Cell Line, Tumor , Child , Child, Preschool , Female , Humans , Infant , Male , Neoplasm Proteins/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Proto-Oncogene Proteins c-bcl-2/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Vault Ribonucleoprotein Particles/geneticsABSTRACT
AIM: to investigate properties of leukemic cells by sorting out children diagnosed with ALL with different response to chemotherapy based on MRD level. METHODS: We used a minimal residual disease (MRD) data on day 36 obtained with 3-colour flow cytometry as a reference. In view of MRD results, we used real-time PCR to assess expression levels of multidrug resistance associated genes MDR1, LRP and BCRP, antiapoptotic gene Bcl-2 in initial samples from children diagnosed with ALL. P-gp expression and function in initial samples were analyzed by flow cytometry. RESULTS: Briefly, medians of relative expression levels of MDR1 gene were roughly comparable and in MRD(+) group came to 22.8 (0.02-26.6; n = 9) vs 24.8 (3.9-41.4; n = 10) in MRD(-) group. Bcl-2 gene showed tendency to higher expression levels in MRD(+) group with median at 5992.9 (521.0-10362.0; n = 9) compared to 3183.6 (1947.9-6581.0; n = 10) in MRD(-) group. LRP gene relative expression levels were similar in both groups and came to 1934.9 (1500.7-3490.4; n = 9) and 1408.5 (665.5-2917.1; n = 10) in MRD + and MRD(-) groups, respectively. The median of BCRP expression levels in MRD + group was considerably lower than that in MRD - group, namely 76000.0 (48196.2-169230.8; n = 9) and 227967.2 (16683.7-422222.2; n = 10), respectively, but statistical analysis showed no significant difference for this parameter. CONCLUSION: We investigated expression of multidrug resistance genes MDR1, LRP and BCRP and antiapoptotic gene Bcl-2 in leukemic cells at diagnosis, and MRD level at the end of induction therapy, and could not find obvious relations between these parameters.