HE440 Lecture 9: HE440P – Lecture 4
Document Summary
Signalling pathways: understanding these pathways will help to understand the molecular mechanisms behind environmental impact on carcinogenesis. Loss of proliferation inhibition: pten phosphatase, counteracts pi3-kinase by degrading its product, phosphatidylinositol trisphosphate (pip3) Loss of function mutations of pten amplify pi3k signaling and promote tumourigenesis: pten expression in human tumours is often lost by promoter methylation. Apoptosis: does not induce inflammation, phagosomes and adjacent cells engulf debris, millions of cells in our body undergo apoptosis every day, controlled by balance or pro- and anti-apoptotic factors, extrinsic cell surface death receptors, ex. Apoptosis intrinsic: elicited by oncogene activation or other non-sustainable stresses, ex dna damage, telomere shortening, low oxygen, pro-apoptotic bax inserts into outer mitochondrial membrane causing membrane permeabilization. Fas: an adaptor molecule, fas-associated death domain protein (fadd) dimerizes the death receptors. Leads to activation of procaspase 8 to initiator caspase 8: pathway converges with intrinsic. Necroptosis: necrotic cell death that is programmed.
