Read the following passage.
BRCA1 and BRCA2 are human genes that code for tumour suppressor proteins involved in DNA repair. Mutations in BRCA1 and BRCA2 significantly increase the risk of developing breast and ovarian cancers. Specific inherited and somatic mutations in these genes can be identified using genetic screening. DNA extracted from a patient's saliva or blood sample can be screened for all known pathogenic variants of these two genes.
Estrogen-receptor (ER)-positive breast cancers possess receptors for the hormone estradiol (estrogen). These breast cancers grow and proliferate in response to elevated estradiol concentrations in the breast tissue. Hormonal therapy for ER-positive breast cancers often utilises drugs, such as tamoxifen, which have a molecular structure similar to estradiol.
Blood tests are widely used to detect specific cancer biomarkers. Women with ovarian cancer often exhibit elevated levels of Cancer Antigen 125 (CA-125) in their blood. However, non-malignant conditions, including uterine fibroids, pelvic inflammatory disease (PID), endometriosis, and even normal menstruation, can also cause significant elevations in CA-125 levels.
Recent clinical advances in epigenetic therapies target the aberrant epigenetic modifications often observed in breast cancer cells, such as hypermethylation of promoter regions of tumour suppressor genes. Novel drugs known as epidrugs are designed to reverse these epigenetic modifications and restore normal gene expression patterns.
Use the information in the passage and your own knowledge to answer the following questions.
BRCA1 and BRCA2 are human genes that code for tumour suppressor proteins. Mutations in BRCA1 and BRCA2 can cause cancer. Explain how.
DNA extracted from a patient's saliva or blood sample can be screened for all known pathogenic variants of these two genes. Describe how this DNA could be screened for all known pathogenic variants of BRCA1 and BRCA2.
Hormonal therapy for ER-positive breast cancers often utilises drugs, such as tamoxifen, which have a molecular structure similar to estradiol. Suggest and explain how these drugs act as an effective treatment for ER-positive breast cancers.
Blood tests are widely used to detect specific cancer biomarkers. However, the results of blood tests may not be conclusive when testing for ovarian cancer using CA-125. Explain why.
Novel drugs known as epidrugs are designed to reverse these epigenetic modifications and restore normal gene expression patterns in cancer cells. Suggest and explain how epidrugs could be used to treat these cancers by reversing epigenetic changes.
