| Description |
140 p. : ill. |
| Note |
Advisors: Saroj Mathupala, Andrew E. Sloan. |
| Thesis |
Thesis (Ph.D.)--Wayne State University, 2005. |
| Summary |
Glioblastoma multiforme are highly malignant tumors that produce large amounts of lactate as a by-product of glucose consumption. We investigated inhibition of lactate efflux as a novel method to destructively alter the metabolite profile in these tumors to induce tumor-specific apoptosis and radiosensitization, thus adding a wing to our current growing armament of gene therapies against cancer. Thus, our main objective was to test the in-vitro and in-vivo therapeutic potential of lactate transporter (monocarboxylate transporters; MCTs) inhibition or knockout; alone or combined with irradiation. We used -cyano-4-hydroxycinnamic acid (ACCA), an inhibitor of lactate and pyruvate transport, and small interference RNA (siRNA) against glioma specific MCTs, to test the specificity and efficacy of our technique. The method was tested first in vitro , and then in vivo in a nude rat model. |
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Flow cytometry was used to assess the apoptosic/necrotic state of ACCA treated U-87MG glioma cells and used to calculate the lethal dose at LD 30 . 1 H Magnetic Resonance Spectroscopy (HR-MAS 1 H MRS) was used to assess metabolite profiles of cells 6, 12, and 24 hrs post ACCA treatment. For combined therapy, the cells were exposed to irradiation, post-ACCA therapy. For targeted therapy, the experiments were repeated with siRNA against glioma specific MCT isoforms. Survival fractions were determined by clonogenic assay, and the data fitted to the linear-quadratic (LQ) model. |
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In vivo efficacy of the therapy was tested on stereotaxically implanted U87-MG tumors in nude rat brains. ACCA or MCT-specific adenovirons were applied in situ via osmotic pumps. The tumor response monitored by MRI and postmortem histopathology, in the presence or absence of combined radiotherapy via "gamma knife" based irradiation. |
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We found that targeted MCT-specific gene therapy, both in-vitro and in-vivo , was cytotoxic to tumors and sensitized them to irradiation damage. Inhibition of lactate/pyruvate transport in glioma, induced apoptosis and reduced antioxidant protection, debilitating the tumor's ability to defend against free radical damage. Irradiating these antioxidant-depleted cells made them more vulnerable to free radical provoked damage. We conclude that the localized use of a lactate transport inhibitor such as ACCA or MCT-specific-siRNA will be a novel adjunctive therapeutic strategy against glial tumors, which can be combined with radiotherapy for increased efficacy. |
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| Added Title |
Wayne State University thesis (Ph.D.) : Physiology.
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| OCLC # |
81148129 |
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