DNA repair .. continued Flashcards

1
Q

The use of cultured cells to study secondary events in tumour formation. Explain Crisis ?

A

Most cells die after culture within

a few weeks (crisis)

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2
Q

What happens to the cells which survive crisis? and how ?

A

They are an established cell line and grow indefinitely, with the following characteristics:

  1. Anchorage dependence
  2. Growth factor dependence
  3. Show density-dependent inhibition
  4. Morphology
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3
Q

Explain Anchorage dependence ?

A

Cells need a surface to attach to

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4
Q

Explain Growth factor dependence ?

A

Require essential growth factors and hormones to survive

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5
Q

Explain Show density-dependent inhibition ?

A

Cells only grow to a limited density due to cell-cell contacts

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6
Q

Explain the morphology?

A

Cells are flat and extended on the growing surface, typical with an elongated network of stress fibres

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7
Q

What do the cells which become transformed show many characteristics of ?

A

Tumour cells, with the following:

  1. Anchorage independence
  2. Less growth factor dependence
  3. Lack density-dependent inhibition
  4. Increased metabolic rates
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8
Q

Now explain the growth characteristics of tumour cells in culture ?

A
  1. Anchorage independence; cells do not always need a solid surface to attach to and are more resistant to apoptosis
  2. Less growth factor dependence; some cells even make their own growth factors for autocrine stimulation and survival
  3. Lack density-dependent inhibition; show decreased levels of contact inhibition and grow on top of each other
  4. Increased metabolic rates; increased expression of glucose transporters or ones with increased activity; secrete lactic acid (WARBURG effect) which changes the colour of the growth medium; increased rates of protein synthesis
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9
Q

What does altered morphology show in cells?

A

Decreased expression of surface fibronectin and exhibit increased motility; cells round up and lose attachment with the surface

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10
Q

What else does the altered morphology in a cell show ?

A

Decreased cytoskeletal arrangement due to disarray, decreased expression or aberrant expression of essential structural proteins (e.g. tropomysin, actin, vinculin)

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11
Q

Malignant tumours cells are invasive and can spread. This process requires a number of events, including:

A
  1. A number of changes in gene expression

2. The ability to move brought about decreased fibronectin/E-cadherin expression to reduce cell:cell contacts

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12
Q

What does decreased E-cadherin and increased N-cadherin expression reduce ? and alter ?

A

It reduces cell to cell contact. This alters cell signalling

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