Breast Cancer Flashcards
Nuclear receptors
= steroid receptors or lipid receptors
Cortisol production and binding
A glucocorticoid
Ligand for glucocorticoid receptor
Produced by adrenal cortex
Cortisol’s effects on the immune system
An important negative regulator of the immune system. Suppresses the expression of pro-inflammatory genes in immunce cells, and activate the expression of anti- inflammatory genes. Potent agonists of GR (such as prednisone) are therefore used to treat many different conditions when it is important to suppress the inflammatory response, such as allergy or autoimmune disease.
Cortisol effects on metabolism
Cortisol in an important stress response hormone and is produced at higher levels in the fasting state. It reinforces the activty of glucagon and epinephrine to promote fuel mobilization. However, its effects are primarly a result of causing changes in gene expression.
For example, cortisol stimulates the expression of genes required for gluconeogenesis in the liver, increases the expression of hormone sensitive lipase in adipose tissue, and promotes muscle protein breakdown, to stimulate the release of amino acids to support gluconeogenesis.
Side effects of glucocorticoids given as anti-inflammatories
The use of potent agonists of GR to treat autoimmune disease is a double edged sword, as it can lead to side effects such as hyperglycemia, fat redistribution, and muscle atrophy, among other symptoms
Aldosterone
A mineralocorticoid
Ligand for the mineralocorticoid receptor
Produced by the adrenal cortex, acts almost exclusively on the kidneys
Progesterone
A progestin
Ligand for the progesterone receptor
Produced in ovaries, acts in female reproductive tract, breast, and brain
Functions of progesterone
Progesterone levels vary during the menstrual cycle, and it has important effects in regualting the lining of the uterus (endometrium). Its levels are also elevated during pregnancy. Progesterone plays important roles in breast development during puberty and pregnacy, and also regulates lactation. Many of the actions of progesterone require the action of estrogen, because estrogen regulates the expression of the progesterone receptor.
Testosterone
An androgen
Ligand of the androgen receptor
Produced by the adrenal gland in both men and women, and also the testis in men
Functions of testosterone
Testosterone is critical for development of the male reproductive organs as well as further development of male characteristics in puberty. Testosterone is also important for function of the prostate in adults and therefore the androgen receptor is an important drug target for treatment of prostate cancer. Androgens can also promote the growth of muscle and for this reason can be considered a type of anabolic hormone.
Synthesis of steroid hormones from cholesterol
Estradiol
An estrogen
Ligand of the estrogen receptor
Produced by ovaries and peripheral tissues, acts on female reproductive tract, breasts, brain
Functions of estrogens
Estrogen is important during puberty for development of the reproductive system and secondary sexual characteristics in females, and also regulates the biology of the endometrium and and breast during the reproductive cycle. Estrogen is important for expression of the progresterone receptor. Estrogen and progresterone work together to regulate proliferation and differentiation of the ducts and lobules of the breast during puberty, pregnancy and lactation.
Because many breast cancers are dependent on estrogen for proliferation, the estrogen receptor is an important drug target for breast cancer
Three major sources of estrogen
(1) by direct secretion from the ovary in reproductive-age women
(2) by conversion of circulating androstenedione (A), originating from the adrenal or ovary or both, to estrone (E 1 ) in peripheral tissues
(3) by conversion of A to E 1 in estrogen target tissues.
Relative strength of estrogens
E2 >> E1
The expression of genes that encode the enzymes ____ and reductive ____ is critical for E2 formation from E1.
The expression of genes that encode the enzymes aromatase and reductive 17β-hydroxysteroid dehydrogenases (17β-HSD) is critical for E2 formation from E1.
Production of Estrogen figure
The classic hormones that use nuclear receptors for signaling are ___ and ___.
The classic hormones that use nuclear receptors for signaling are thyroid hormone and steroid hormones
In addition to hormones, nuclear receptors also mediate the biologic effects of some ___.
In addition to hormones, nuclear receptors also mediate the biologic effects of some vitamins.
Specifically, vitamins D and A.
Nuclear receptor signaling
Much of the regulation of nuclear receptor signaling is mediated by interactions of nuclear receptors with ____.
Much of the regulation of nuclear receptor signaling is mediated by interactions of nuclear receptors with coregulators (costimulators and corepressors).
Major domains of nuclear receptors
DNA-binding domain: Controls gene-specificity of the receptor
Ligand-binding domain: Activates the transcriptional effects. Operates by recruitment of coactivators or corepressors. May operate geneteically or epigenetically.
Dynamic range of transcriptional effects of nuclear receptors
SERM
Selective estrogen receptor modulator
such as tamoxifen
Receptor antagonists in some tissues like breast tissue and breast cancer cells, but act as agonists in other tissues such as endometrium and bone.
Breast anatomy
The most common type of breast cancer
ductal carcinoma
Breast cancer risk factors
- Personal history of breast cancer
- Family history of breast cancer
- Inherited mutations in BRCA1 or 2
- Personal history of non-canceorus breast disease
- Dense tissue finding on mammogram
- Several symtpoms which expose the breast to more estrogen:
- Early menstruation age
- Older age at first birth or never given birth
- Starting menopause later
- Taking hormones
- Radiation exposure
- Alcoholism
- Obesity
- Being white
Protective factors for breast cancer
- Estrogen-only hormone therapy after hysterectomy
- SERMs
- Aromatase inhibitors
- Exercise
Signs of breast cancer (or other conditions, not exclusive)
- A lump or thickening in or near the breast or in the underarm area.
- A change in the size or shape of the breast.
- A dimple or puckering in the skin of the breast
- A nipple turned inward into the breast.
- Fluid, other than breast milk, from the nipple, especially if it’s bloody.
- Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin around the nipple).
- Dimples in the breast that look like the skin of an orange, called peau d’orange.
Mammogram
Breast x-ray