Introduction To Hormone Dependent Cancers: Brest And Prostate Cancer Flashcards
What is a hormone?
Chemical messenger made by specialist cells (endocrine glands) released into bloodstream to have effect on another part of the body
Where are hormones produced?
Endorcrine glands
- ovaries, uterus
- testes
- hypothalamus
- pituitary gland
- thyroid
- thymus
- pancrease
- adrenal cortex
- kidneys
What are the 3 main classes of hormones? and example of each
Steroids - lipid soluble e.g. testosterone
Peptide/protein e.g. insulin
Modified amino acids/amine hormone e.g. adrenaline
What are steroid hormones synthesis from?
Cholesterol
What is the structure of steroid hormones?
4 ring steroid backbone structure + lipophilic so can pass through membranes
Where does cholestrol comes from?
Ingested or synthesised de novo in body
How are steroids synthesised breifly?
Cholestrol converted to corticosteroids/mineralocorticoids in adrenal cortex
Androgenic / estrogenic precursors secreted into blood and reach gonadal tissues
Androgens and estrogens product in gondal target tissues and released into blood stream
name a few steroid hormones
Androgen (testosterone) Estrogen (estrodiol) Progestogen (progesterone) Corticosteroid (cortisol) Minerlocorticoid (aldosterone)
What are the sex steroid hormones?
Hormones made by gonadal tissues
What is the purpose of sex steroid hormones?
sexual dimorphism between males and females
- development of secondary sexual characteristics
What are the effects of estrogen in females?
Control menstural cycles, breast tissue development, fertility, reproductive organ development, secondary sexual characteristics e.g. body hair
What are the effects of testosterone in males?
Reproductuve and supportive organ(prostate) controls
development of sexual characterisitics (e..g deepening of voice and body hair)
What is the link between breats/prostate cancer and sex steroid hormones?
Sex steroid hormones strongly control breast and prostate tissue growth ad development
What do steroids control i breast and prostates?
Cellular prolideration, tissue function, gene expression and morphology of tissues
What do steroids control in cancers of breast and prostate
Steroid hormones still influence cells grwoth and function casuing disease to develop and progress
What is the action of steroid hormones? receptor mechanisms of action
Steroids circulating in blood enter cell due to lipphilic nature across membrane + bind to nuclear receptors found in the cytoplasm or nucleus
Nuclear receptor releases chaperone proteins after confirmational shape change of steroid binding to it and translocates to nucleus
In nucleus, steroid receptor binds to DNA specificic sequences in the promoter regions of steroid response elements
Steroid receptirs recruit transcription factors and coactivators to induce gene expression
What are the key characteristics of the nuclear receptor?
Ligand binding domain (binds to specific steroid hormone)
DNA binding domain - binds to specific dna sequences in the response element
Activation function domain (AF1 and AF2)
- recruits activation machinery for gene expression
Why are nuclear receptors called ligand activated receptors?
Steroid hormone must bind to be activated
What happens to nuclear receptors when ligans (steroid) binds to ligand binding site?
Physical confirmation shape change of polypeptide chains (ALPHA HELIX domains) in receptor to activate the receptor
What happens once steroid binds to nuclear receptor and translocates to nucleus?
Shift in alpha helix due to ligand binding causes receptor to be activated
Activated receptor dimerises and moves to nucleus and binds to specific DNA sequences
Receptor recruits DNA modifiying enzymes and transcription factors to promoter hormone responsive genes activation
What is the structure of the DNA binding domain on the nuclear receptor?
2 zinc finger domains essential for binding to specific DNA sequences
Why are the zinc figer domains important?
To bind to specific DNA sequences in steroid responsive genes
- they
How are genes affected from steroid hormones?
Genes are upregulated and some are downregulated
What types of genes are affected by steroid hormones?
Tissue specific genes, cell cycle and proliferation genes, and genes involved in tissue development and differentiation
What are hormone responsive elements?
Specific DNA sequences found in the promoters of hormone responsive genes
Where do the nuclear recepotrs binds on dna?
Hormone response elements
What is the structure of the hormone response element?
Palindromic
6 bases separated by 3 spacer DNA bases and another 6 dna bases that is a palindromic repeat
What do all nuclear receptors share?
Common domain structure from common evolutionary ancestor
- distant evolutionary ancestors may bind to other things instead of steroids e.g. fatty acids, bioacids, precursors
What are the abbreviattion for main steroid receptors? and their ligands
ER - estrogen receptor - ligand for estrodiol, estriol
AR - androgen receptor - ligand is androgens (testosterone)
PR - progesterone receptor - ligand is progesterone
GR - glucocorticoid receptor - ligand is cortisol
MR - mineralocorticoid receptor - ligand is aldosterone
What are the main sex hormone receptors for each type of cancer?
ER and PR for breast cancer
AR for prostate cancer
What type of gland is the breast?
Apocrine gland
What is the breast made up off? (structur of breast)
Glands(lobules produce breast milk) and ducts(carry the milk)
What is an exocrine gland?
Secrete substances out onto a surface or cavity via ductal surface
What is an endocrine gland?
Secrete substances directly into the bloodstream
What is an apocrine gland?
Specialised exocrine gland in which a part of cell’s cytoplasm breaks off releasing the contents
What is the structure of mammary gland tissue?
2 cel compartments
- Luminal and basal
What is the luminal cell compartment? + its function it mammary gland tissue
Single layer of polarised epithelium around the ductal lumen, luminal cells produce milk during lactation
What is the basal cell compartment and its function if mammary gland tissue?
Cells that don’t touch the lumen
Myoepithelial cells in contact with basement membrane
Function - contractile function during lactation to move milk into the ducts
What are the 2 phases of mammary gland development?
Hormone independent from embryonic development to puberty
Hormone dependent after puberty, menstrual cycle and pregnancy
Which effect does estrogen and other growth hormones have on breasts?
Drive the expression of genes involved in cellular proliferation and differentiation of the breast - MAINLY IN INITIAL GROWTH OF BREAST
Causes ductal elongation and triggers side branching after puberty (hormone dependent stage of mammary gland development)
As adult, maintains mammary gland tissue
What other hormones are involved in breast development?
Cortisol, growth hormones
What effect does progesterone normally have on the mammary glands?
MAIN FUNCTION IS TO INCREASE BRANCHING OF DUCTS
What effect does progesterone have on breats during pregnancy and why?
During pregnancy, progesterone levels increases causing prolonged progesterone receptor activity leading to more side branching and lactogenic differentiation (for milk production) together with PROLACTIN HORMONE
What activates progesterone receptor gene?
Progesterone receptor gene swtiched on by estrogen receptor
Which hormones are involved in lactogenic differenitation during pregnancy?
prolactin and progesterone(more so in side branching)
Where does breast cancer commonly start?
Cells that line milk ducts within breast tissue
How does age affect breast cancer?
Increased risk
Which gene mutations contribute to breast cancer risk?
BRCA1 and BRCA2
- inherited = higher risk of breast and ovarian cancer
What are some risks for breast cancer?
Age
genetic mutations
Reproductive history (early onset of menstrual cycle or late menopause - prolonged hormone exposure)
Overweight/obese
Hormone replacement (birth control pills)
Late pregnancy/not breastfeeding
What is DCIS?
Ductal breast carcinoma in situ
- cancer develops in ducts and havent spread outside of ducts into breast tissue
What is LCIS?
Lobular carcinoma in situ
- abnormal cells found in milk glands (lobules)