The Search For The Causes Of Cancer Flashcards
Name the 3 pillars whose contributions led to understanding the origin of cancer
Boveri - German geneticist (abnormal chromosomes)
Peyton Rous - (tumour causing viruses)
Yamagiwa - (Carcinogens)
What did Boveri propose as the cause of cancer
He proposed that cancer occurs because of an abnormal set of chromosomes in the cancer cells
Describe what defines a ‘normal’ vs an ‘abnormal’ set of chromosomes
Normal - Euploidy
Abnormal - Aneuploidy (the absence of euploidy meaning that the number and/or the composition of certain chromosomes is abnormal)
Boveri believed aneupoidy caused cancer
Were Boveri’s experiments successful?
No,but he was still fundamentally convinced of the genetic origin of cancer
Is Boveri right? Why?
Yes, since abnormalities of the genetic material of the celll are the fundamental causes of cancer
What was Yamagiwa’s contribution to understanding the origin of cancer?
He developed the hypothesis that certain chemicals (he names carcinogens) have the ability to cause any type of cancer
140 years before Yamagiwa, describe the observation made by Percival Pott
He observed the high incidence of scrotal cancer in chimney sweepers and proposed that it was soot which caused the cancer.
Describe Yamagiwa’s experiment
- He repeatedly treats rabbit’s ears with coal tar (extracted from coke)
- Repeats for 660 days
- End result is a rabbit ear with a carcinoma
What does the IARC stand for? What does this agency do?
International Agency for Research on Cancer
It does extensive research on chemicals and cancer (and has a large database with which chemicals cause cancer)
Explain the link between Boveri’s and Yamagiwa’s hypothesis
Carcinogens are potent mutagens - they are able to cause mutations which damage the genetic material.
You can establish carcinognicity first and then prove mutagenicity, or the other way around
What was Peyton Rous’s contribution to understanding the cause of cancer
He identified viral agents as the cause of some tumours
Describe Peyton Rous’s experiment
- Takes tumour cells
- breaks them apart and takes tissue extract
- Filters it to remove all cells and tissue debris (any bacteria is also removed)
- Filtrate is injected into an animal
- Animal developes tumour
How did Peyton Rous know that a virus was causing the tumours?
The tumour causing agent must be filterable (and the filter was good enough to exclude all bacteria therefore it could only be a virus)
