Tumours
- Abnormal and fast cell division of mutant cells can form a tumour.
Benign Tumours | Malignant Tumours |
Slow growth rate | Faster growth rate |
Cells remain well-differentiated | Cells tend to de-differentiate and become unspecialised |
Tumours are surrounded by a capsule made of dense tissue (compact structure) | Tumours are not surrounded by a capsule |
Cells produce adhesion molecules | Cells stop producing adhesion molecule. Can spread through the body (metastasis) |
Can usually be removed by surgery. | Chemotherapy and radiotherapy are used, which specifically target and kill rapidly dividing cells. |
Oncogenes & Tumour Suppressor Genes
- Oncogenes are genes that stimulate cell division e.g. they may encode growth factors or cell cycle regulators.
- Many cancers are found to have cells with abnormal DNA methylation (epigenetic changes). Detecting these changes can help diagnose, while reversing these changes may help cure these diseases.
- Oncogenes can be hypomethylated in the promoter regions to upregulate transcription and expression to cause excessive proliferation in a tumour.
- Tumour suppressor genes are genes that prevent tumour formation by repairing DNA damage, regulating cell division and promoting apoptosis.
- Tumour suppressor genes can be hypermethylated in the promoter region to prevent transcription, allowing increased cell divisions with a higher mutation rate. resulting in cancerous tumours.
- Oestrogen binds to a transcription factor, which activates genes to promote cell division. Increased oestrogen concentrations in the adipose tissue in the breast of post-menopausal women has been linked to breast cancer development.