Environment (Light) and Breast Cancer Cont. - Final Exam Flashcards
What neurotransmitter/hormone is part of the pathway for melatonin biosynthesis?
Serotonin
What has vitamin D been found to activate?
The transcription of the initial serotonin – synthesizing gene tryptophan hydroxylase
What 2 factors down-regulate estrogen signalling and what is the result?
- Melatonin
- Vitamin D
- -> Result = decrease in breast cancer
What does low levels of serotonin and vitamin D, coupled with increase in LAN and low melatonin levels lead to?
Increases levels and effects of estrogen, thus increasing the risk of breast cancer
What is serotonin a local regulator of?
Mammary gland epithelium
How many serotonin receptors exhibit different expression patterns in breast caner specimens?
4
What does serotonin regulate and what does it initiate?
- Regulates = lactation
- Initiates = transition into the earliest phases of apoptosis
What does serotonin regulate in the breast for production?
Ca
When does massive cell shedding and cell death occur?>
During early involution
What does serotonin induce?
Cell death of normal mammary epithelial cells in vitro
What seems to be resistance to serotonin (5-HT)-induced cell death?
Breast cancer cells
Mt1
Melatonin receptor 1
What receptor family is Mt1 apart of?
GPCR
What does melatonin-mediated cyclical regulation of GnRH mRNA expression may involve?
PKC and the extracellular signal-regulated kinase 1 & 2 pathways
- but not the PKA pathway
What does melatonin regulate?
GnRH
What does GnRH regulate and how?
Estrogen hypothalamic-pituitary-gonadal axis via LH and FSH
What does LH regulate?
Progesterone
What are 5 approaches to look at LAN effect on the circadian rhythm that accounts for part of the breast cancer burden?
- Other studies looking at shift work
- Epidemiology comparing different areas of the world
- Direct evidence that light inhibits melatonin synthesis
- Animal models
- Melatonin signalling pathways
What do you have an automatic risk for if you dont have children and why?
Breast cancer
- You need to interrupt the menstrual cycles with pregnancy
What is a risk for breast cancer in shift working women?
Urinary melatonin metabolite in night nurses significantly ~40% lower on both work and off days compared to dayshift nurses