Browsing by Subject "Biomedical Sciences"

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    Manipulating Tfam expression and mitochondrial capacity to overcome drug resistance in breast cancer cells.
    (2012-04-18) Zehowski, Cheryl
    For a patient diagnosed with breast cancer, the determination of a treatment is based on a biopsy and the markers that are present in the tumor at the time of diagnosis. There are tumors that are difficult to determine whether or not it will respond to chemotherapy treatment at the time of diagnosis. The research that I have been working on supports the main goal of the Skildum lab that discovering predictive biomarkers in tumor samples will help to determine a personalized and more effective treatment path. To model drug resistant breast cancer in vitro, I work with MCF-7 (sensitive to chemotherapy treatment) and LCC9 (less sensitive to chemotherapy treatment) breast cancer cells. Tfam is the major regulator of mitochondrial DNA replication and transcription. I discovered that the Tfam gene had an increased expression in the LCC9 cells than in the MCF-7 cells. We then decided to look at the contribution of Tfam expression to drug sensitivity in LCC9 cells. Through siRNA transfection, which interferes with the translation of proteins by binding and promoting degradation of the messenger RNA at specific sequences, we successfully knocked down Tfam mRNA expression. Here we show the consequences of Tfam knockdown are decreased mitochondrial DNA copy number and decreased labeling with a mitochondria specific fluorescent dye. From this finding I have begun to test whether Tfam knockdown in LCC9 cells increases their sensitivity to the chemotherapy drug doxorubicin. If LCC9 cells do have increased drug sensitivity after Tfam knockdown, then the Tfam gene could potentially be used as a biomarker of drug resistance in breast cancer patients.
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    Mitochondrial capacity of chemotherapy resistant and sensitive lung cancer cells
    (2012-04-18) Zehowski, Cheryl
    Lung cancer is a significant cause of mortality in the U.S., the leading among cancer deaths, and more research is needed to improve the clinical picture for patients. Drug resistance remains a barrier to successful treatment of cancer even with the ongoing development of new molecularly targeted therapies. In the diagnosis of cancer, the treatment is determined based on the parameters of the tumor. Non-invasive cancers are often cured by surgery alone, while cancers that have progressed past the lymph node stage are commonly treated with chemotherapy. Chemotherapy drugs are administered systemically and used to kill cancer cells and prevent cancerous cells from producing. There is not a definitive way to distinguish between a chemotherapy resistant or sensitive cancer tumor at the time of diagnosis which is wasting precious time for the patient if the treatment does not work. The main goal of the Skildum lab is to identify biomarkers specific for drug resistant cancer that will allow for earlier and more effective treatment decisions. We have established a model of cancer resistance, using MCF-7 (sensitive to chemotherapy) and LCC9 (less sensitive to chemotherapy treatment) breast cancer cells. We have shown that LCC9 cells have increased mitochondrial capacity and increased expression of the Tfam gene in comparison to the MCF-7 counterpart. Tfam is a major regulator of mitochondrial DNA replication and transcription. From here curiosity struck to discover if other forms of cancer have increased expression of the Tfam gene in the resistant form of cancer. If we are able to discover a gene that is uniquely expressed in a number of cancers, we may be able to target that gene as a biomarker in the diagnosis of cancer patients. The goal of the current work was to test whether mitochondrial capacity was elevated in a model of doxorubicin resistant human lung cancer. The techniques used were cell culture, sulforhodamine B assay and hemocytometer to verify doxorubicin treatment in the cells, DNA isolation for mtDNA expression and RNA isolation to express Tfam through qPCR. Preliminary results show that chemotherapy resistant lung cancer cells have increased mitochondrial DNA and Tfam expression in comparison with their sensitive lung cancer counterpart.