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A short class with Sarah and her students. The other ways are under More.
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Your skin cells divide to replace old ones, then stop. What do you think a cancer cell does differently?
It keeps dividing even when the body doesn't need new cells.
Exactly. Some genes act like an accelerator for division, and others act like brakes. What happens if the accelerator gets stuck?
The cell divides all the time. That's an oncogene, isn't it?
Yes. And when tumour suppressor genes, the brakes, stop working, nothing slows the cell down.
And if the tumour spreads through the blood to other organs, that's metastasis.
Right. That is what makes malignant tumours so dangerous.
Old chemotherapy attacks all fast-dividing cells, which is why hair falls out. How could treatment be more precise?
Target something that only the cancer cells have?
That is a targeted therapy. Imatinib blocks the faulty protein that drives one kind of leukaemia.
Could the immune system be trained to attack cancer instead?
That is immunotherapy. In CAR-T therapy, a patient's own immune cells are modified to recognise their cancer cells.
And how do we know a new treatment is safe?
Through clinical trials: safety first in a small group, then effectiveness, then a large comparison with the best existing treatment.
An axolotl can regrow a whole leg. Why can't we?
Most of our cells are specialised and can't change into other cells.
So regenerative medicine uses stem cells and engineered tissues. Can you give an example?
Growing skin from a patient's own cells to treat burns.
Good. Now, what danger might come from putting pluripotent stem cells into a patient?
If they keep dividing without control, they could form a tumour.
Exactly. That is why the two fields rely on each other: both are about controlling cell division.
Cancer develops when mutations in oncogenes and tumour suppressor genes let cells divide without limit.
Benign tumours stay in place; malignant tumours invade and can spread by metastasis.
Targeted therapies, immunotherapy and prevention by vaccination come from research into cell biology.
Stem cells, tissue engineering and organoids aim to repair or replace damaged tissue.
Both fields depend on controlling cell division and raise questions of safety, consent and cost.
A smoker's lung cells build up mutations from carcinogens in tobacco smoke until a cell escapes the controls on division and forms a tumour.
Imatinib blocks the abnormal protein that drives chronic myeloid leukaemia, so the leukaemia cells stop multiplying while most normal cells are unaffected.
Skin cells taken from a burns patient are multiplied in the laboratory and grafted back, covering wounds with the patient's own tissue.
Accelerator stuck and brakes worn thin, that is how a tumour's growth sets in.
A town's builders, the cells, normally build only when the mayor asks. One builder's walkie-talkie breaks and keeps shouting "Build!", while the inspector who should stop him has fallen asleep. Houses spread over the parks and roads: that is a tumour.
Oncogenes Overdrive, Suppressors Stop: the two kinds of genes that go wrong in cancer.
S.T.O. - Stem cells, Tissue engineering, Organoids: three tools of regenerative medicine.
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What is cancer, in terms of cell division?
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Oncogene and tumour suppressor gene
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Metastasis
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Regenerative medicine
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Why must stem cell therapies be tested carefully for cancer risk?
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A disease in which cells divide uncontrollably and can invade other tissues.
A mutated gene that keeps promoting cell division.
A gene that normally slows or stops cell division, such as the gene for p53.
The spread of cancer cells from the first tumour to other parts of the body.
A drug that blocks a specific protein that drives the growth of particular cancer cells.
Treatment that helps the body's immune system recognise and attack cancer cells.
The branch of medicine that repairs or replaces damaged cells, tissues and organs.
A tiny, simplified organ grown from stem cells in the laboratory.
Cancer research studies why cells escape the controls on cell division and how to stop them, while regenerative medicine uses stem cells and engineered tissues to make the body's own cells divide and specialise to repair damage.
This lesson looks at two research fields built on our understanding of the cell cycle and differentiation. It explains how mutations in genes that control division turn normal cells into cancer cells, and how research has produced targeted drugs, immunotherapies and a vaccine that prevents some cancers. It then explores regenerative medicine, from natural regeneration in animals to stem cell treatments, lab-grown tissues and organoids, and shows why both fields must balance the promise of controlling cells with safety and ethics.
Both fields are about the same question: how does a cell decide when to divide, when to stop, and what to become? Cancer is what happens when that control is lost; regenerative medicine tries to switch division and specialisation on deliberately, in the right place and for the right length of time.
Normal cells divide only when the body needs new cells, and checkpoints in the cell cycle stop division if DNA is damaged. Cancer begins when mutations build up in the genes that control this:
Cells with these mutations divide again and again, forming a tumour. A benign tumour stays in one place. A malignant tumour invades nearby tissue, and its cells can travel in the blood or lymph to form secondary tumours elsewhere, a process called metastasis. Mutations can be caused by carcinogens such as tobacco smoke, ultraviolet light and some viruses, and some people inherit a faulty allele, such as a faulty BRCA1 or BRCA2 gene, that raises their risk.
New treatments are tested in clinical trials: Phase 1 checks safety in a small group, Phase 2 checks whether the treatment works and at what dose, and Phase 3 compares it with the best existing treatment in a large group of patients.
Some animals regenerate remarkably: an axolotl can regrow a lost limb, and a flatworm can regrow a whole body from a fragment. In humans, the liver can regrow after part of it is removed, but most organs cannot. Regenerative medicine aims to repair or replace damaged cells, tissues and organs:
The tools of regenerative medicine are powerful precisely because they make cells divide and specialise. If transplanted pluripotent cells are not fully controlled, they can form tumours, so cancer research and regenerative medicine depend on each other's discoveries. Both fields also raise ethical questions: consent for the use of patients' cells (the famous HeLa cell line was taken from Henrietta Lacks in 1951 without her knowledge), the use of embryos and animals in research, the very high cost of new treatments, and fair access to them.