Date of Award

2013

Degree Name

Biomedical Sciences

College

Joan C. Edwards School of Medicine

Type of Degree

Ph.D.

Document Type

Dissertation

First Advisor

W. Elaine Hardman

Second Advisor

Monica Valentovic

Third Advisor

Pier Paolo Claudio

Fourth Advisor

Nalini Santanam

Fifth Advisor

John Wilkinson

Abstract

B-cell chronic lymphocytic leukemia (CLL) is the most common form of adult leukemia in the western world. CLL is often diagnosed in the asymptomatic (early-stage) stages. However, approximately 50% of these patients will progress to advanced, symptomatic disease and require therapy. Current treatment options are limited due to progressive drug resistance and severe drug-induced toxicities which are often too toxic for the elderly or those with co-morbidities. Therefore, a non-toxic therapeutic intervention that could slow the progression of asymptomatic CLL to symptomatic CLL or enhance the effects of actively used chemo-therapeutic drugs in patients who require therapy would be clinically beneficial.

In our studies, we evaluated the use of omega-3 (n-3) fatty acids as therapeutic options for CLL utilizing both a clinical supplementation model (FWA #00002704) as well as a cell culture model. The primary objective of the initial study was to determine whether consumption of n-3 could suppress activation of nuclear factor kappa B (NF B) in lymphocytes from patients diagnosed with early stage CLL. The primary objective of the follow-up study was to evaluate whether n-3 eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) could enhance the chemo-sensitivity of CLL-derived cell lines EHEB and MEC-2 and pro-lymphocytic leukemiaderived cell line JVM-2 to anti-cancer drugs doxorubicin, vincristine or fludarabine in vitro.

ur initial study indicated that consumption of an EPA + DHA containing n-3 supplement 1) suppressed activation of NF B in lymphocytes from patients diagnosed with early stage CLL, 2) increased molar concentrations of n-3 in the plasma, 3) increased the chemosensitivity of lymphocytes to doxorubicin in an in vitro assay and 4) decreased the expression of 32 genes in lymphocytes. Targeting the NF B pathway is proposed as a therapy for CLL. Suppression of NF B activation by n-3 may slow the progression of the disease to symptomatic disease where therapy is required. However, a definitive clinical trial will be needed to determine if n-3 can slow the progression of CLL.

The aim of the second study was to expanding upon the chemo-sensitization capabilities of n-3. In these trials, cell-cycle analyses, Annexin-V assays, assays for malondialdehyde (a measure of lipid peroxidation) and DCF fluorescence assays (a measure of reactive oxygen species (ROS) generation) were performed to explore potential mechanism(s) through which enhanced chemo-sensitivity was achieved.

Results indicated that: 1) EPA and DHA differentially sensitized B-leukemic cell lines EHEB, JVM-2 and MEC-2 to doxorubicin, vincristine and fludarabine in vitro; 2) n-3 alone and with drug treatment increased cell death and induced G2/M arrest in a cell-type specific manner; 3) lipid peroxidation increased in the presence of n-3; 4) there was higher lipid peroxidation in MEC-2 cells in presence of DHA and doxorubicin than with either alone; 5) n-3 increased generation of ROS in MEC-2, and 6) the addition of vitamin-E abrogated the increase in ROS generation and chemo-sensitivity of MEC-2 to doxorubicin by DHA.

N-3 are a promising therapeutic intervention for the treatment of CLL with the capacity to potentially slow the progression of the disease and enhance the chemo-sensitivity of malignant cells to chemo-therapeutic drugs and warrants further investigation. Slowing the progression of the disease would be clinically beneficial. Enhanced chemo-sensitivity would be expected to increase drug efficacy and potential reductions in drug dosage and drug-induced toxicities.

Subject(s)

Leukemia - Treatment.

Omega-3 fatty acids - Research.

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