Date of Award

2007

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Computing, Health and Science

First Advisor

Dr Melanie Ziman

Abstract

Cutaneous Malignant Melanoma is a highly aggressive form of skin cancer that has a tendency to metastasise. In its early stages, the 5-year survival rate of patients is greater than 90% following surgical excision of an in situ tumour. However, following metastasis of the tumour, the 5-year survival rate declines to 5-35%. Due to the correlation between metastasis and declining survival, studies have attempted to identify potential metastasis as early as possible. Molecular markers of melanoma cells in the peripheral blood of CMM patients have been investigated, as the invasion of tumour cells into the blood is one of the first events in melanoma metastasis. Genetic markers PAX3d, MITF, MART1, SFRP5 and TGFβ32 are involved in the development, proliferation and migration of melanocytic cells, and are aberrantly expressed in melanoma. Therefore, the aim of this study was to develop an assay that can be used for CMM diagnosis and prognosis and to assess PAX3d, MITF, SFRP5, MART1 and TGF-{32 expression in peripheral blood of CMM patients relative to healthy volunteers. In this study, lymph node tissue and peripheral blood samples were taken from CMM patients and blood was donated from healthy volunteers. Total RNA was extracted from all samples and following the analysis of RNA quality, samples were Reverse Transcribed. The resulting cDNA was analysed by PCR for the expression of the housekeeping gene GAPDH, following which samples expressing this gene were analysed by PCR for the presence of each of the genetic markers: PAX3d, MITF, MART1, SFRP5 and TGFβ32. Statistical analysis of marker expression showed that CMM patients were significantly more likely than healthy volunteers to express one or more markers, as well as significantly higher expression of MITF, TGFβ32 and MART1 in patients relative to healthy volunteers. The number of markers shown in each sample was statistically analysed and showed that a significantly higher frequency of TGFβ32 expression correlated with primary tumours of >2.00mm in CMM patients, as well as a significantly lower frequency of MART1 expression in patients with a tumour depth of 0.01-2.00mm relative to patients with in situ melanoma or >2.00mm tumour depth. Frequent expression of all markers in CMM patients even after more than one year since diagnosis suggests the longevity of melanoma cells in the blood. The results presented here show that MITF, MART1 and TGFβ32 are sensitive and useful markers of melanoma cells in the peripheral blood of CMM patients even after more than one year since diagnosis.

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