| What is cancer ? | - Uncontrolled Mitosis therefore cell division |
| Cell Division controlled by two genes | - Proto-oncogenes (stimulate cell division) ACCELERATOR
- Tumour Suppressor Genes (suppress cell division) BRAKE |
| Benign Tumour | - Localised slow growing tumour that does not metastasise |
| Malignant tumour | - A fast growing tumour that often metastasises |
| Metastasis | - Where primary cancer cells break off and produce secondary cancers (often in the lymph notes) |
| Benign Tumours | - Slow growing
- Cells adhere to each other
- Do not metastasise
- Treated by surgery
- Cells do show diferentiation |
| Malignant Tumours | - Fast growing
- Cells don't adhere to each other
- Does metastasise
- Treated by radiotherapy, chemo, surgery
- Cells do not show diferentiation |
| Proncogenes | - Genes that stimulate cell division e.g. they may encode growth factors or cell cycle regulators/ cause cancer
- 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 |
| If there is a mutation in genes controlling mitosis cancers can develop: | - Proto-Oncogenes become Oncogenes :
these may lead to the constant production of growth factors
- Or may lead to the receptor being activated so cell division is switched on permanently |
| Hypermethylated | - Not enough methyl groups added
- Turn on genes |
| Hypomethylated | - Too many methyl groups added
- Turn off genes |
| Proto-oncogenes can be hypomethylated | - Oncogenes can be hypomethylated in the promoter regions, turned on, more proteins that control mitosis, more uncontrolled cell divison |
| Tumor suppressor genes | - 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 | - Can be hyper. in promoter region to prevent transcription, turn off tsg, less proteins that control mitosis, more uncontrolled cell divisions with a higher mutation rate = cancerous tumours |
| So.... | - If we could produce a drug that would inhibit the enzyme that leads to methylation we could reduce the risk of some cancers
- Identifying high or low methylation levels would help to identify patients at risk |
| Oestrogen and breast cancer | - 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 |
| How protooncogenes are used to initiate cell division | - Proto-oncogene transcribed + translated to produce a protein (growth factor)
- Growth factor binds to complementary shaped receptor on the cell membrane
- This acts as a switch which activate transcription factors
- The transcription factor binds to DNA + leads to the production of proteins that initiate mitosis
- Therefore leading to cell division |
| BRCA 1 | - A tumour suppressor gene
- Mutation is recessive |
