Contributions
Abstract: PB1611
Type: Publication Only
Background
Philadelphia chromosome positive acute lymphoblastic leukemia (Ph + ALL), expressing BCR/ABL oncoprotein, is the most common subtype with high mortality rate and poor prognosis. Overall survival rate can only be extented to a few years after treatment and complete remission can not be achieved. Therefore, it is quite important to investigate new therapeutic agents and define potential novel cellular targets for the treatment. The anticarcinogenic potential of resveratrol has not been investigated in Ph + ALL. Bioactive sphingolipids are a lipid family with important members including ceramide, sphingosine-1-phosphate (S1P) and glucosyl ceramide (GC), which have significant roles in the regulation of cell divison, growth, metastasis and apoptosis. Ceramide produced through de novo synthesis pathway (Serine Palmitoyl Transferase (SPT) is a key enzyme subjected to regulation) is a central molecule in sphingolipid metabolism playing significant roles in the induction of apoptosis. On the other hand, the conversion of ceramide into sphingosine-1-phosphate (S1P) by sphingosine kinase 1 (SK-1) or/and into glucosyl ceramide by glucosyl ceramide synthase (GCS) induces the proliferation of cancer cells. Therefore, ceramide metabolism and the regulation of enzymes such as SPT, SK-1 and GCS have a great therapeutic importance.
Aims
It is aimed to investigate therapeutic potential of resveratrol on Ph + ALL cells and to identifiy potential mechanisms behind resveratol-mediated apoptosis in association with targeting of ceramide metabolism and regulation of BCR-ABL.
Methods
The antiproliferative and apoptotic effects of resveratrol, SPT inhibitor (myriocin), SK-1 inhibitor (SKI II), GCS inhibitor (PDMP), resveratrol:myriocin, resveratrol:SKI-II and resveratrol: PDMP combinations on Ph + ALL cells, SD-1 and SUP-B15, are investigated by cell proliferation assay and flow cytometry (annexin-V/PI), respectively. Caspase-3 and PARP levels and cytochrome c release are checked by western blot to confirm apoptosis induction. The synergistic, antagonistic or additive effects of the mentioned combinations and the combination indexes are calculated using Calcusyn program. The cytostatic effects of each agent alone and combinations are determined by PI staining. BCR-ABL levels are determined by western blot after the cells are exposured to each agent alone and defined combinations.
Results
Proliferation of Ph + ALL cells were reduced dose and time dependently with treatment of either drug except myriocin. Drug interaction relationship were studied using Calcusyn software and effects of synergistic combinations (CI<1) involving lower doses of resveratrol and ceramide metabolism enzymes were selected for further studies.These combinations significantly induced apoptosis via enhanced PARP cleavage, caspase-3 activation and cytrochrome-c release. Combinations also caused ceell cycle arrest at different phases and modulated the expression of BCR-ABL.
Conclusion
The anti-leukemic effect of resveratrol on Ph + ALL cells and mechanisms behind its action are enlightened by targeting critical enzymes involved in ceramide metabolism and regulating BCR-ABL for the first time. Furthermore, resveratrol:SPT inhibitör, resveratrol:SK-1 inhibitor and resveratrol:GCS inhibitor combinations could be considered as a novel approach for the treatment of leukemia.
Session topic: 1. Acute lymphoblastic leukemia – Biology & Translational Research
Keyword(s): Acute lymphoblastic leukemia, BCR-ABL, Ph+ ALL, Synergy
Abstract: PB1611
Type: Publication Only
Background
Philadelphia chromosome positive acute lymphoblastic leukemia (Ph + ALL), expressing BCR/ABL oncoprotein, is the most common subtype with high mortality rate and poor prognosis. Overall survival rate can only be extented to a few years after treatment and complete remission can not be achieved. Therefore, it is quite important to investigate new therapeutic agents and define potential novel cellular targets for the treatment. The anticarcinogenic potential of resveratrol has not been investigated in Ph + ALL. Bioactive sphingolipids are a lipid family with important members including ceramide, sphingosine-1-phosphate (S1P) and glucosyl ceramide (GC), which have significant roles in the regulation of cell divison, growth, metastasis and apoptosis. Ceramide produced through de novo synthesis pathway (Serine Palmitoyl Transferase (SPT) is a key enzyme subjected to regulation) is a central molecule in sphingolipid metabolism playing significant roles in the induction of apoptosis. On the other hand, the conversion of ceramide into sphingosine-1-phosphate (S1P) by sphingosine kinase 1 (SK-1) or/and into glucosyl ceramide by glucosyl ceramide synthase (GCS) induces the proliferation of cancer cells. Therefore, ceramide metabolism and the regulation of enzymes such as SPT, SK-1 and GCS have a great therapeutic importance.
Aims
It is aimed to investigate therapeutic potential of resveratrol on Ph + ALL cells and to identifiy potential mechanisms behind resveratol-mediated apoptosis in association with targeting of ceramide metabolism and regulation of BCR-ABL.
Methods
The antiproliferative and apoptotic effects of resveratrol, SPT inhibitor (myriocin), SK-1 inhibitor (SKI II), GCS inhibitor (PDMP), resveratrol:myriocin, resveratrol:SKI-II and resveratrol: PDMP combinations on Ph + ALL cells, SD-1 and SUP-B15, are investigated by cell proliferation assay and flow cytometry (annexin-V/PI), respectively. Caspase-3 and PARP levels and cytochrome c release are checked by western blot to confirm apoptosis induction. The synergistic, antagonistic or additive effects of the mentioned combinations and the combination indexes are calculated using Calcusyn program. The cytostatic effects of each agent alone and combinations are determined by PI staining. BCR-ABL levels are determined by western blot after the cells are exposured to each agent alone and defined combinations.
Results
Proliferation of Ph + ALL cells were reduced dose and time dependently with treatment of either drug except myriocin. Drug interaction relationship were studied using Calcusyn software and effects of synergistic combinations (CI<1) involving lower doses of resveratrol and ceramide metabolism enzymes were selected for further studies.These combinations significantly induced apoptosis via enhanced PARP cleavage, caspase-3 activation and cytrochrome-c release. Combinations also caused ceell cycle arrest at different phases and modulated the expression of BCR-ABL.
Conclusion
The anti-leukemic effect of resveratrol on Ph + ALL cells and mechanisms behind its action are enlightened by targeting critical enzymes involved in ceramide metabolism and regulating BCR-ABL for the first time. Furthermore, resveratrol:SPT inhibitör, resveratrol:SK-1 inhibitor and resveratrol:GCS inhibitor combinations could be considered as a novel approach for the treatment of leukemia.
Session topic: 1. Acute lymphoblastic leukemia – Biology & Translational Research
Keyword(s): Acute lymphoblastic leukemia, BCR-ABL, Ph+ ALL, Synergy