Date of Award

5-1-2012

Degree Name

Master of Science

Department

Molecular Biology Microbiology and Biochemistry

First Advisor

Mo, Yin-Yuan

Abstract

Serum is an essential component of cell cultural medium. Besides nutrients, it supplies various growth factors which are indispensable for growth, proliferation, and survival. Prolonged serum starvation treatment usually will induce cell to enter a quiescent state (G0) or go to apoptosis. In the present study, we hypothesized that some microRNAs (miRNAs) may promote cancer cell survival under prolonged serum starvation treatment. We used cell culture medium without any serum to culture HCT-116 wild type cells infected with the miRNA library consisting of over 600 miRNA precursors in a lentiviral vector. Finally, we enriched miR944 and miR596 from the screening experiments and identified them capable of conferring serum starvation resistance.. We also found that the expression of c-myc and p53 as well as the phosphorylation of mTOR s2448 are affected by ectopic expression of miR596 and miR944 while cultured in medium with or without serum supplying. These proteins are closely related to the cell survival under stress, which may suggest a possible mechanism for miR596 and miR944. Experiments are underway to identify direct target genes of miR596 and miR944. The other project that I studied is about the function of Leukemia related protein 16 (LRP16) in breast cancer progression. Available evidence suggests that LRP16 is a co-activator of estrogen receptor a (ERa) in promoting ERa-positive breast cancer cell proliferation. Our experiments indicate that LRP16 is upregulated only in primary breast cancer tissues (StageⅡ) and MCF7 cell lines, but not in highly metastasis StageⅢ breast cancer tissues and MDA-MB-231 cell lines. The ectopic expression of LRP16 in MCF7 and 231 cell lines causes an opposite effect on cell proliferation. Although it was originally hypothesized that LRP16 may promote cell proliferation by influencing the production or phosphorylation of p65, or other NF-κB family members, we could not provide direct evidence to support this. Therefore, we did not go further.

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