The majority of cancers employ an elevated level of glycolysis, even under mildly aerobic conditions. This bias towards aerobic glycolysis, known as the Warburg effect, is a hallmark of cancer that regulates various cellular attributes including drug sensitivity. Many studies show that the major pathway regulating glycolysis is PI3K/Akt/mTOR pathway. We hypothesize that cancer cell lines established in physiological hypoxia can more accurately mimic leukemia in vivo, and that in vitro studies in physiological O2 of agents targeting the PI3K/Akt/mTOR Pathway in ALL will more closely resemble in vivo results. Our goals are 1) to show that the glycolytic pathway genes are affected by oxygen conditions in acute lymphoblastic leukemia (ALL) established in different oxygen conditions and therefore, the more glucose consumption and more lactate production are seen in cell lines established in hypoxia;and 2) using the cell lines established in hypoxia and direct xenografts we will evaluate drugs targeting the glycolytic pathway. By comparing new childhood acute lymphoblastic leukemia cell lines in atmospheric (20% O2) and physiologic bone marrow (5% O2) oxygen concentrations, we will demonstrate that atmospheric oxygen tension inhibits glycolysis-related gene expression, glucose consumption, lactate production, cell proliferation, and alters dug sensitivities. The effects of physiological and non-physiological (i.e. """"""""standard"""""""" culture conditions) oxygen concentrations on glycolysis are not readily reversible by switching cell cultures from one oxygen condition to another, indicating the need to establish cell lines in physiological oxygen conditions in order to provide accurate in vitro models for studying cancer cell metabolism. Our preliminary observations suggest that preservation of the Warburg effect in leukemia requires culturing cells at physiologic oxygen concentrations from the time of their initial establishment. By establishing and evaluating a large panel of leukemia cell lines in two different oxygen conditions, and also for comparison as direct xenografts in immunocompromised mice, we will provide an understanding on the importance of culture conditions on metabolic networks in cancer in vitro models. In addition, we will evaluate whether glycolytic pathway could provide feasible targets for ALL treatment by evaluating new PI3K inhibitor with less immunosuppression in combination with current therapy of ALL (e.g. dexamethasone and L-asparaginase, another metabolism inhibitor). This project will also make available for other investigators via the COG repository (www.COGcell.org) a unique set of well characterized and validated laboratory models for studying cancer biology and preclinical therapeutics.
Lymphoid malignancies are the most common cancer in children and adolescents in the United States, and the most prevalent of these is acute lymphoblastic leukemia (ALL) with the incidence being gradually increasing over the last 25 years. Significant improvements in primary therapy for childhood ALL have led to an overall cure rate of approximately 80 %. However, of the 20% of patients who relapse, the majority die. The ultimate goals of our proposal are to identify how leukemia cells make energy to grow and proliferate, and to find drugs that can attack the energy generating mechanisms of leukemia cells.
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