20 - Tumour Suppressor Genes

• "Normal" role of TSG products:

  • Negative regulation of proliferative signalling
  • Inhibition of cell division
  • Activating cell death
• Mutations that decrease tumour suppressing protein activity can contribute to cancer
• TSG can be affected by any mutation that decreases expression or inactivates them
• Mutations in classical TSG are genetically recessive (both alleles must be mutated)
• Retinoblastoma is the most common eye tumour in children 0-4 years and arises in immature retinal cells (affects 1/20,000 children)
• Method of screening retinoblastoma:

  • White light shone in eye
  • Reflection from normal retina appears red
  • Reflection appears white could be retinoblastoma
• 87% of children worldwide with retinoblastoma die
• Sporadic (no family history) retinoblastoma causes single tumours in one eye (60% cases)
• Hereditary (inherited) retinoblastoma occurs in both eyes and is dominant (40% cases)