Apoptosis in Cancer Cells

Triggers of Apoptosis

infection by a virus or absence of growth signals

Bax and Bak

proapoptotic proteins, Bak is bound to mitochondrial outer membrane but Bax is in cytosol, associated with viral triggers.

Bad and BH3

Proapoptotic proteins, associated with the absence of survival factors, bind to anti-apoptotic proteins.

Bcl2 and BcXL

antiapoptotic proteins that inhibit cytochrome c release. These bind to Bax and Bak.

C-FLIP

inhibits apoptosis by not cleaving caspase 8 into its active form, regulates extrinsic pathway

Fas Ligand

Binds to FAS receptor, activates the FADD, which forms the DISC to initiate apoptosis.

The extrinsic pathway

cell receives apoptotic signal via an external ligand that binds to membrane bound receptor

Intrinsic pathway

apoptotic signal is in cytosol of cell and causes mitochondria to release proteins which induce cytochrome c release.

Cytochrome C

induced apoptosis, binds to apas-1 to form an apoptosome which activates an initiator caspase.