The Expression Profile of Glycolysis Associated Molecules and Chemoresistance in Acute Myeloid Leukemia

The drug resistance of leukemic cells remains a major obstacle to chemotherapy in patients with AML, which always leads to treatment failure consequently. However, the complex mechanism in chemoresistance causes a growing concern to looking for some new therapeutic targets and improving the sensitivity of chemotherapy. Recently, researchers have used metabolomics technology to explore the differences of metabolomics between imatinib (IM)-resistant and sensitive chronic myeloid leukemia (CML) cells, and thus to clarify the mechanism of IM resistance, provide new targets to the treatment of IM resistance. The data showed that increased glycolytic activity related with IM drug resistance. As glycolytic rate directlly correlates with tumorigenesis and chemoresistance, it provides a new idea for cancer treatment. Some studies confirmed that there was also abnormal glycolysis in hematopoietic tumor cells. Thus, the study was expected to investigate the relations between the altered energy metabolism and chemoreisitance in AML. Furthermore, the effect of inhibition of glycolysis on chemoresistance in myeloid leukemia cells was evaluated.

The bone marrow samples obtained from with newly diagnosed (n=45) and relapsed (n=9) patients with AML (M3 excluded) in our hospitals from October 2010 to November 2011. The AML blasts in every sample was exceed to 80 percent. The total 54 AML cases with average age of 41.6±17.8 years were included in 31 male and 23 female patients. The expression differences of glycolysis associated molecules (e.g. HIF-1α, HK-II, GLUT1, CD147 and LDH) and β subunit of human F1-F0 ATP synthase (ATP5B) in different drug-sensitive AML cells were analyzed. Adriamycin (ADM)-sensitive AML cell line HL-60 and resistant cell line HL-60/ADM were used to evaluate the glycolytic activities and the effect of glycolysis inhibition on cellular proliferation.

The drug-resistant HL-60/ADM cells exhibited a significantly higher glycolysis rates than the drug-sensitive AML cell line HL-60 (97.4%±0.70% vs. 55.0%±3.16%, P<0.01). The levels of HIF-1α and GLUT1 mRNA expression of the drug-resistant HL-60/ADM cells was higher than that of drug-sensitive HL-60 cells (HIF-1α: 3.70±0.084 vs. 1.0±0.075, P<0.01, GLUT1: 3.36±0.149 vs. 1.0±0.080, P<0.01). Likewise, the levels of HIF-1α, HK-IIand GLUT1 mRNA expression in AML patients with NR were higher than those in groups of health control, CR and PR (P<0.01). Also, the serum level of LDH in AML patients with NR was higher than that in groups of health control, CR and PR (1211.57±456.99 vs. 490.75±278.35 vs. 490.63±213.94 vs. 149.90±31.66, P<0.01). Furthermore, the expression of CD147 on bone marrow blasts from NR group was higher than that in groups of CR and PR (97.75%±4.17% vs. 89.41%±14.22%, P<0.01). Additionally, the expression of ATP5B protein were decreased in the drug-resistant HL-60/ADM cells (0.1388 vs 0.1192), and the level of ATP5B protein in patients with NR was lower than that in CR group (0.0092±0.0042 vs. 0.0540±0.0482, P<0.01). 2-DG or 3BrPA, the glycolysis inhibitors, acts in synergy with ADM in ADM-resistant HL-60/ADM leukemic cells, whereas it didn't increase ADM-induced toxicity in HL-60 cells. Treatment of the cell lines HL-60/ADM and HL-60 with sublethal concentrations of 2-DG or 3 BrPA, either alone or in combination with ADM, resulted in a considerable reduction of glucose uptake compared with non-treated cells. With these treatments for 24h, the cellular apoptosis rate in these two cell lines showed no significant difference (P>0.05). However, the glycolysis inhibitors in combination with ADM increased markedly the necrosis in these cell lines.

The chemoresistance was associated with increased glycolytic activity and low efficiency of oxidation phosphorylation in AML cells, regarding as the elevated expression of glycolysis associated molecules, i.e. HIF-1α□AHK-II□AGLUT1□ALDH and CD147. Inhibition of glycolysis can reverse the chemoresistance of drug-resistant AML cell line HL-60/ADM. The enhancements of ADM-induced cytotoxicity by 2-DG or 3BrPA may be due to the activation of nonapoptotic, programmed cell death.

No relevant conflicts of interest to declare.