Cell Transformation Flashcards
Describe Dulbecco’s experiment
You take mammalian cells, add the virus, plate the cells and look for the number of plaques. These plaques correspond to the number of animal viruses present in the system
Howard temin and Harry Rubin were studying the effects of _________. To measure the phenotype, they used _____________’s experiment
RSV ; Dulbecco
They found that transforming virus RSV doesn’t cause plaques but instead ______, which are piles of cells
Floci
Rubin and Temin see that one can meaure an effect on cell growth in culture by the transforming oncogenic virus. They used this approach to determine several features the ___________ __________
Transformed phenotype
Name the 6 features of the transformed phenotype
- Change in cell shape
- Immortality
- Lack of requirement for exogenous growth signals
- Can grow in a semi-solid medium
- Loss of density dependant inhibition on growth
- Loss of contact inhibition of cell movement
Transformed phenotype: Describe change in cell shape
Cell shape is hugely important in terms of how the cell behaves in vivo and in culture
Transformed phenotype: Describe immortality
The transformed cell is immortal - lives for as long as it’s grown in culture. Regular cells have a limited number of divisions before they stop (fibroblasts have around 60). This is called the Hayflick phenomenon
Transformed phenotype: Describe lack of requirement for exogenous growth signals
Regular cells only divide in response to external chemical signals, when cells are transformed they no longer requre growth signals to divide
Additionally, transformed cells lose sensitivity to external growth inhibitiory signals
Transformed phenotype: Describe anchorage independant growth
Normal cells (aside from blood cells) can only grow if they are attached a substratum, they would not grow in a semi-solid medium. Transformed cells lose this property and will grow even in a semi-solid medium
Transformed phenotype: Describe density dependant inhibition of growth
Normal cells in culture will grow until they cover the surface available and then they stop. Transformed cells continue to grow in a disordered and multilayered way
Transformed phenotype: Describe loss of contact inhibition of cell movement
If a few fibroblasts are in culture, they move randomly, they crawl and when they hit each other they stop and move apart. Transformed cells don’t do this but instead they crawl on top of each other - they have lost regulation of cell movement
This is the most essential feature of malignant cells - allowing them to leave the primary tumour and travel across the body to create secondary tumours (metastasis)
