Non-Melanoma Skin Cancer Flashcards
What are the most common type of cells in the epidermis?
Keratinocytes
What specific groups of cancers does non-melanoma skin cancers refer to?
Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)
What are the four subtypes of BCCs?
Nodular (~half are this type), morphoeic, pigmented, superficial
What is the first sign of non-melonama skin cancer?
A lump or patch on the skin that doesn’t heal after a few weeks
What cells do BCCs and SCCs develop from?
BCC - basal cells; SCCs - keratinocytes
What are the risk factors of BCC and SCC?
Mainly UV exposure.
BCC from sunburn/recreational exposure to sunlight
SCC mainly linked to overall sun exposures (eg outdoor workers)
How is UV light thought to induce DNA mutations?
Induces direct DNA mutation via covalent bonding between adjacent pyrimidines (UVB) and formation of ROS (UVA)
What is Patched1?
[the protein product of PTCH] Is a cell surface receptor, inhibits SMO
Where is the PTCH gene found?
Chromosome 9q22
What is SMO?
Smoothened; a G-protein coupled receptor
What happens if Patched1 is mutated?
Cessation of SMO inhibition –> activation of Gli1 –> uncontrolled cell proliferation
What is Gli1?
A transcription factor
What other genes are associated with the pathogenesis of BCC?
CYP, GST (detoxify mutagens) and p53 (tumour suppressor gene)
How does SCC arise?
From precursor lesions of actinic keratosis (AK) and Bowen’s disease
What gene mutations are associated with SCC?
p53, Ras, c-Myc
