- Title
- The role of nucleotide excision repair in melanoma development and platinum chemotherapy resistance
- Creator
- Budden, Timothy
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2017
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Melanoma is a malignant skin cancer caused by exposure to ultraviolet radiation (UV). The melanoma genome shows a significant over-representation of mutations that suggest unpaired UV-induced DNA damage. Melanoma is also intrinsically resistant to platinum based chemotherapy agents that induce similar DNA damage to UV. Both these features of melanoma may be linked to the nucleotide excision repair (NER) pathway, which is responsible for repairing these types of damage. Here we investigated the response of the NER pathway to UVB exposure in melanoma cell lines. The results confirmed that melanoma cells had a defect in the repair of UVB-induced DNA damage, predominantly in the S-phase of the cell cycle. Quantification of NER transcripts also showed that expression of the DNA damage detection branch, global genome repair (GGR) (XPC, DDB1 and DDB2), was not induced in melanoma compared to normal melanocytes. A low mutation frequency in GGR genes suggests that loss of expression is not due to mutations. Investigation into the role methylation plays in silencing XPC showed that demethylation with decitabine allowed for XPC to be induced in response to the platinum agent carboplatin. Decitabine was also able to sensitize melanoma to carboplatin, with increased levels of apoptosis and reduced cell proliferation after combined treatment. Knockdown studies showed that this was not solely due to increased XPC. Whole genome methylation arrays identified many potential demethylated genes that may contribute to the response, with demethylation of CpG island shores and gene bodies the predominant response. Of particular interest were genes from the PTEN/PI3K/AKT pathway and the ability of decitabine and carboplatin to modulate the immunogenicity of melanoma. In conclusion, we identified that GGR is deficient in melanoma and may contribute to the mutation spectrum and platinum resistance. We have also identified a potential therapeutic treatment for melanoma that will be investigated further, particularly in the context of immunotherapy.
- Subject
- melanoma; nucleotide excision repair; NER; ultraviolet; platinum; carboplatin; XPC
- Identifier
- http://hdl.handle.net/1959.13/1337630
- Identifier
- uon:27882
- Rights
- Copyright 2017 Timothy Budden
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 397 KB | Adobe Acrobat PDF | View Details Download |