What is the mode of action of tamoxifen?
Tamoxifen (TAM) is known to have a dual mechanism of action: (1) to compete with 17β-estradiol (E2) at the receptor site and to block the promotional role of E2 in breast cancer; and (2) to bind DNA after metabolic activation and to initiate carcinogenesis.
What is the primary target of tamoxifen?
Tamoxifen competitively inhibits estrogen binding to its receptor, which is critical for it’s activity in breast cancer cells.
What is the drug tamoxifen used for?
Tamoxifen is a hormone therapy for breast cancer in both women and men. It lowers the risk of early breast cancer coming back (recurring) after surgery or developing in the other breast. It can also control advanced breast cancer for some time.
What class of drug is tamoxifen?
Tamoxifen is in a class of medications known as antiestrogens. It blocks the activity of estrogen (a female hormone) in the breast. This may stop the growth of some breast tumors that need estrogen to grow.
Is tamoxifen an agonist or antagonist?
Tamoxifen is both an antagonist and an agonist of the estrogen receptor. However, a molecular explanation exists for this apparent paradox. The dual action is a function of the estrogen receptor complex present in a particular cell or tissue.
What receptors does tamoxifen block?
The drug tamoxifen blocks estrogen receptors, stopping cells from responding to the hormone. As such, it is often used to reduce the likelihood that estrogen-dependent breast cancer will come back after treatment.
What is tamoxifen side effects?
Side effects of tamoxifen may include: Menopause-like symptoms, including hot flashes, night sweats and vaginal dryness. Weight gain (more common) or fluid retention (edema). Irregular or loss of menstrual periods.
How is tamoxifen used for fertility?
Fertility specialists sometimes prescribe Tamoxifen for the treatment of female infertility. When administered for this purpose, it works by blocking estrogen receptors in the hypothalamus, the area of the brain responsible for initiating the signal that ultimately leads to ovarian stimulation.
What type of antagonist is tamoxifen?
Tamoxifen is a nonsteroidal estrogen receptor antagonist that is mainly used for the treatment of estrogen receptor-positive breast cancer. It also inhibits protein kinase C, an important component of several signal transduction pathways.
How is tamoxifen an agonist?
In breast tissue, tamoxifen acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. A beneficial side effect of tamoxifen is that it prevents bone loss by acting as an ER agonist (i.e., mimicking the effects of estrogen) in this cell type.
Where is tamoxifen an agonist?
Tamoxifen is both an antagonist and an agonist of the estrogen receptor.
Is tamoxifen a safe drug?
Tamoxifen may cause cancer of the uterus (womb), strokes, and blood clots in the lungs. These conditions may be serious or fatal. Tell your doctor if you have ever had a blood clot in the lungs or legs, a stroke, or a heart attack.
Who should take tamoxifen?
Tamoxifen is used to reduce the risk of invasive breast cancer if you’re at high risk and you’re 35 and older, whether or not you’ve gone through menopause. You and your health care provider might consider whether chemoprevention with tamoxifen is right for you if: Your Gail model risk score is greater than 1.7%.
Can tamoxifen prevent pregnancy?
Tamoxifen and Herceptin Impact on Fertility Tamoxifen is not known to cause infertility, but it may interfere with childbearing because of the duration of the treatment—usually five to 10 years—during which time women should not get pregnant.
What does tamoxifen do to the uterus?
Tamoxifen results in a spectrum of uterine abnormalities including benign alterations such as endometrial polyps, endometrial hyperplasia, endometrial cystic atrophy, adenomyosis, and uterine fibroid growth as well as malignant transformation into endometrial carcinoma and uterine sarcoma[4–8].
Why is tamoxifen an agonist?
If a cell type requires activating factors 1 and 2 of the estrogen receptor to be functioning concurrently, tamoxifen is antagonistic. However, if a cell or tissue requires only activating factor 1 to interact with transcription factors at the promoter, tamoxifen is agonistic.
How is tamoxifen an agonist and antagonist?
Is tamoxifen an antagonist or agonist?
What are side effects of tamoxifen?
Tamoxifen may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- increased bone or tumor pain.
- pain or reddening around the tumor site.
- hot flashes.
- excessive tiredness.