Contributions
Abstract: PB1670
Type: Publication Only
Background
Cytarabine is a chemotherapeutic drug used alone or in combination with other anticancer drugs to treat acute myeloid leukemia (AML). New treatment strategies are emerging to enhance the anti-cancer effect and decrease the toxiciteis. Nucleophosmin (NPM1 or B23) is a ribosomal protein located mainly in nucleolus, and multifunctional enzyme in cancer cell growth and protein synthesis. AMP-activated protein kinase (AMPK) is a critical energy sensor to regulate homeostasis and plays a potential role for anti-cell proliferating activity.
Aims
We investigated the effects of AMPK activation on the cell death (apoptosis) and NPM1 expression in AML cells treated with low or high dose of cytarabine, an anti-leukemic drug, to predict the mechanisms responsible for AML cells chemoresistance.
Methods
The HL-60 (FAB M2) cells were exposed to the different drug combinations including cytarabine and AMPK activators. The molecular mechanisms of drug synergism detected by western blot assay and RT-qPCR. Cell viability and apoptosis were assessed using cell counting kit - 8 assay and flow cytometry.
Results
We found that cell apoptosis (36.27 ~ 42.11 %) showed little dependence on cytarabine concentrations (10, 100, and 1000 mM), while the overexpression of NPM1 increased proportionally with drug dependence, indicating the drug-induced cell resistance. In the same point, cytarabine also inhibited the phosphor-activity (Thr172) and expression level of AMPK, which has mTOR-p70S6K pathway-repressor activity. As expected, single cytarabine treatment increased the ratio of p-mTOR/mTOR and p-p70S6K/p70S6K. Co-treatment of AMPK activator (phenformin or AICAR) in cytarabine-treated HL-60 AML cells inhibited significantly the induction of NPM1 overexpression level with the decrease of phosphor-activities of mTOR and its substrate p70S6K, resulted in the accelerated cell apoptosis.
Conclusion
Our results suggest that the higher concentration of cytarabine induces NPM1 overexpression, and that AMPK activation might be used to sensitize AML cells to cytarabine with the control of NPM1 expression levels. These modulatoins to standard therapeutic strategies could actually enable the reduction of the chemotherapeutic dose, therefore reducing their toxicity and adverse effects.
Session topic: 3. Acute myeloid leukemia - Biology
Keyword(s): Cytarabine, chemotherapy, Apoptosis, Acute Myeloid Leukemia
Abstract: PB1670
Type: Publication Only
Background
Cytarabine is a chemotherapeutic drug used alone or in combination with other anticancer drugs to treat acute myeloid leukemia (AML). New treatment strategies are emerging to enhance the anti-cancer effect and decrease the toxiciteis. Nucleophosmin (NPM1 or B23) is a ribosomal protein located mainly in nucleolus, and multifunctional enzyme in cancer cell growth and protein synthesis. AMP-activated protein kinase (AMPK) is a critical energy sensor to regulate homeostasis and plays a potential role for anti-cell proliferating activity.
Aims
We investigated the effects of AMPK activation on the cell death (apoptosis) and NPM1 expression in AML cells treated with low or high dose of cytarabine, an anti-leukemic drug, to predict the mechanisms responsible for AML cells chemoresistance.
Methods
The HL-60 (FAB M2) cells were exposed to the different drug combinations including cytarabine and AMPK activators. The molecular mechanisms of drug synergism detected by western blot assay and RT-qPCR. Cell viability and apoptosis were assessed using cell counting kit - 8 assay and flow cytometry.
Results
We found that cell apoptosis (36.27 ~ 42.11 %) showed little dependence on cytarabine concentrations (10, 100, and 1000 mM), while the overexpression of NPM1 increased proportionally with drug dependence, indicating the drug-induced cell resistance. In the same point, cytarabine also inhibited the phosphor-activity (Thr172) and expression level of AMPK, which has mTOR-p70S6K pathway-repressor activity. As expected, single cytarabine treatment increased the ratio of p-mTOR/mTOR and p-p70S6K/p70S6K. Co-treatment of AMPK activator (phenformin or AICAR) in cytarabine-treated HL-60 AML cells inhibited significantly the induction of NPM1 overexpression level with the decrease of phosphor-activities of mTOR and its substrate p70S6K, resulted in the accelerated cell apoptosis.
Conclusion
Our results suggest that the higher concentration of cytarabine induces NPM1 overexpression, and that AMPK activation might be used to sensitize AML cells to cytarabine with the control of NPM1 expression levels. These modulatoins to standard therapeutic strategies could actually enable the reduction of the chemotherapeutic dose, therefore reducing their toxicity and adverse effects.
Session topic: 3. Acute myeloid leukemia - Biology
Keyword(s): Cytarabine, chemotherapy, Apoptosis, Acute Myeloid Leukemia