An outline of cancer process MW % Flashcards Preview

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Why can't chemeotheraphy target cancer cells?

  • Chemeotherapy only targets cells which are in the cell cycle stage, but can't target when cells are in the G0 phase.
  • Cancer cells sometimes hide in here.


What are the differences between normal cells and cancer cells?

In cancer cells: 

  1. There is the loss of contact inhibition in cells.
  2. Increase in growth factor secretion.
  3. Increase in oncogene expression.
  4. loss of tumour suppressor genes. 

The reverse of these are true for normal cells.


what are the causes of cancer?

  1. Chemical 
  2. physical 
  3. viral 

These 3 are in the initiation step.

  1. Growth factors 
  2. oncognes 

These two are in the promotion step.

  1. metastasis

This is in the progression step.


List some examples of chemical carcinogens?

  • Nitrogen mustard = leakumia 
  • Aniline dyes=bladder cancer


List some examples of physical carcinogens?

  1. Ionising radiation:
  • Radon source in mainly builiding,but ventilation reduces the risk. Risk increased by smoking 

     2.Mechanism :

  • Chromosome translocation (rearrangement)
  • gene amplification
  • oncogene activation.


Give an example of viral carcinogenes

Avain leukaemia


What is the function of oncogenes in the promotion step of caner?

  • Transforming genes 
  • Positive regulators for growth 
  • Represent a gain in function to transfomed cell


What is the function of growth factors in the promotion step of cancer?

  • Polypeptide molecules 
  • Regulate cell growth function 
  • Bind to cell membrane receptors
  • Stimulate activation of intracellular signal transduction pathways


What are the two different mechanisms in which the stimulation of intracellular signal transduction pathways occur?

  1. Through autocrine (gland is affected):
  • cells carries receptor and secretes growth factor 
  • cell escapes normal control mechanism

   2.   Through paracrine (cells in vicinity of gland affected):

  • Growth factor acting on a cell are produced locally by the cell or its immediate neighbours 


Give an example of Tumour suppressor genes


 •normal function is as transcriptional regulator; promotes DNA repair, apoptosis, differentiation

•Is induced by DNA damage and hypoxia



Give an example of drug used in therepeutics?

  • Anti-VEGF antibody Avastin binds VEGF(vascular endothelial growth factor)
  • Prevents:

    • interaction with  receptors

    •  activation of downstream signalling pathways



    •vascular regression

    • tumour dormant


Why does our immune system not recognise ‘foreign’ cancer cells?

•Cancer cells can ‘hide’ from T cells

PD1 (programmed death receptor) present on T lymphocytes

•Ligand (PDL-1) on tumour cells

•Interaction of these suppresses T cell action.



Multistage cancer pic►