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Differential expression of microRNAs in melanoma

Fairchild, Ene Therese Raig
http://rave.ohiolink.edu/etdc/view?acc_num=osu1267469135

Abstract Details

2010, Doctor of Philosophy, Ohio State University, Integrated Biomedical Sciences.
Expression of microRNAs (miRs) has been shown to be altered in lung, breast, stomach, prostate, colon, and pancreatic tumors but has not been fully explored in melanoma. The malignant potential of some melanocytic lesions is difficult to predict. We hypothesized that characterization of miR expression in indeterminate/borderline melanoma tumors would lead to the identification of a unique molecular profile for lesions with high malignant potential and that expression of these miRs would contribute to the malignant phenotype of melanoma cells. In Chapter 2, we evaluated the miR expression profile of melanocytic lesions including dermal nevi (n=7), malignant melanoma (n=28), and indeterminate melanocytic tissues (n=49) by Real-Time PCR and in situ hybridization. MicroRNAs differentially expressed in melanoma compared to cultured melanocytes were identified by microarray analysis. PCR analysis revealed that primary cutaneous melanomas had a 7.6-fold over-expression of miR-21, a 13.3 fold over-expression of miR-155, and a 0.35-fold reduction in miR-211 expression as compared to benign dermal nevi (p<0.0001), whereas there was no significant difference in levels of miR 17 5p, miR-34b, miR-107, miR-130a, miR 145, miR-181b, miR-221, and miR-373. These results were confirmed by in situ hybridization. miR 21 and miR-155 were variably expressed within indeterminate lesions; however, when these lesions were categorized by mitotic activity and Breslow thickness, miR-155 levels correlated with respect to both variables while miR-21 correlated with mitotic activity only (p<0.05). Indeterminate/borderline lesions from fourteen patients with a positive sentinel lymph node biopsy also had higher miR 21 and miR 155 expression as compared to lesions from node negative patients. We concluded that levels of miR-21 and miR-155 are elevated in melanoma lesions and in high risk indeterminate/borderline lesions, indicating that these miRs may be involved in the malignant progression of melanoma and with further study may represent a novel molecular marker of lesions likely to progress to metastasis. In Chapter 3, we employed synthetic pre-miRs to increase the expression of miR 21 in melanoma cell lines derived from melanomas at differing stages of melanoma. Increased miR-21 did not change proliferation as measured by MTT assay and doubling time or the rate of wound closure in melanoma cell lines. However, in Boyden chamber assays, increased miR-21 expression was associated with a significant increase in invasive capacity. Upon examination of protein expression of several confirmed and putative targets of miR-21 by immunoblot, TIMP3 protein was decreased in cell lysates derived from miR-21 transfected cells. Luciferase activity confirmed that the TIMP3 3’UTR is a direct target of miR-21 in melanoma cells lines. This decrease was Depletion of TIMP3 protein with TIMP3-specific siRNA also resulted in an increase in invasion, indicating this may be one of the mechanisms by which miR-21 may be mediating its invasive effects.
William Carson, III/MD (Advisor)
Robert Baiocchi, MD, PhD (Committee Member)
Tatiana Oberyszyn, PhD (Committee Member)
Tushar Patel, MD (Committee Member)
138 p.
Biomedical Research
melanoma; melanocytic lesions; microRNAs; miR-21

Recommended Citations

Citations

  • Fairchild, E. T. R. (2010). Differential expression of microRNAs in melanoma [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267469135

    APA Style (7th edition)

  • Fairchild, Ene. Differential expression of microRNAs in melanoma. 2010. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1267469135.

    MLA Style (8th edition)

  • Fairchild, Ene. "Differential expression of microRNAs in melanoma." Doctoral dissertation, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267469135

    Chicago Manual of Style (17th edition)

osu1267469135
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© 2010, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.
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