Patients with malignant hematologic diseases often have associated chromosomal abnormalities, but the factors which initiate or foster these alterations are poorly understood. The goal is to investigate the possibility that folate deficiency, which is relatively common in this patient population, may play an important role in the progression of these diseases by promoting chromosomal instability. Decreased intracellular folate activity is associated with numerous chromosomal aberrations including breaks, gaps, despiralization and increased sister chromatid exchanges (SCE). The first specific aim of this proposal is to measure the effects of folate deficiency on the mutagenicity of chemotherapeutic agents. Nutrient lack and drug effects might combine synergistically to account, at least in part, for the high incidence of leukemia in patients with Hodgkin's disease and other hematologic malignancies. Chinese hamster ovary cells will be grown in folate deficient and standard media. The extent of folate deficiency will be evaluated by bioassay, the deoxyuridine (du) suppression test, morphology and flow cytometry. The effect of folate deficiency alone, chemotherapeutic agents alone, and the combination of drug and folate deficiency on chromosome stability will be measured with four assays: SCE, mutant induction at a specific locus (HGPRT), flow cytometry for gain, loss or unequal exchange of DNA, and detection of double strand breaks by alkaline filter elution. Our second specific aim is to measure the effect of folate status on the frequency of chemotherapy-induced chromosomal alterations in patients with hematologic malignancies. The incidence of chromosomal changes before and after chemotherapy will be determined and correlated with patient folate status as evaluated by morphology, blood folate levels, the du suppression test, and assays of membrane transport and cellular uptake of folate. The frequency of chromosomal alterations will be assessed by measuring SCE and somatic mutants at the HGPRT locus in peripheral lymphocytes. These studies will provide information about the incidence of folate deficiency, the degree of chromosomal instability, and the extent of synergy between folate deficiency and chemotherapeutic agents in causing chromosomal damage. The corollary, if our hypothesis is confirmed, is that dietary supplementation with a non-toxic nutrient might reduce the frequency of chemotherapy-induced chromosomal changes in patients with hematologic malignancies.
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