Small molecules that induce intrinsic pathway apoptosis
Apoptosis is generally believed to be a process that requires several hours, in contrast to non-programmed forms of cell death that can occur in minutes. Our findings challenge the time-consuming nature of apoptosis. We describe herein the discovery and characterization of a small molecule, named Raptinal, which initiates intrinsic pathway caspase-dependent apoptosis within minutes, in multiple different cell lines. Comparison to a mechanistically diverse panel of apoptotic stimuli reveals Raptinal-induced apoptosis proceeds with unparalleled speed. The rapid phenotype enabled identification of the critical roles of mitochondrial voltage-dependent anion channel function, mitochondrial membrane potential/coupled respiration, and mitochondrial complex I, III and IV function for apoptosis induction. Use of Raptinal in whole organisms demonstrates its utility to study apoptosis in vivo for a variety of applications. Overall, rapid inducers of apoptosis are powerful tools that will be used in a variety of settings to generate further insight into the apoptotic machinery.
1. A method to induce caspase-dependent apoptosis in an animal cell comprising contacting an animal cell with an effective apoptosis-inducing amount of compound 1 or 2:
thereby initiating intrinsic pathway caspase-dependent apoptosis.
2. The method of claim 1 wherein the animal cell is in a live animal.
3. The method of claim 1 wherein the animal cell is in an in vitro cell culture.
4. The method of claim 1 wherein compound 1 or 2 is in a solution or formulation in a concentration of about 0.1 μM to about 20 μM.
5. The method of claim 1 wherein compound 1 or 2 is in a solution or formulation in a concentration of about 1 μM, about 2 μM, about 5 μM, about 10 μM, or about 20 μM.
6. The method of claim 1 wherein the apoptosis occurs within about 6 hours of contacting the cell.
7. The method of claim 1 wherein the apoptosis occurs within about 180 minutes of contacting the cell.
8. A method of inducing initiation of cytochrome c release from the mitochondria of an animal cell comprising contacting an animal cell with an effective cytochrome c releasing amount of compound 1 or compound 2:
thereby initiating release of cytochrome c from the animal cell.
9. The method of claim 8 wherein the release of cytochrome c from the animal cell is initiated within 60 minutes of contacting the cell.
10. The method of claim 8 wherein the release of cytochrome c from the animal cell is initiated within 30 minutes of contacting the cell.
11. The method of claim 8 further comprising pretreating the cell with a cytoprotective agent or an inhibitor of a cellular pathway, and assessing cytochrome c release from the cell.
12. The method of claim 11 wherein the cytoprotective agent or inhibitor is a mitochondrial inhibitor, an inhibitor of respiration or the electron transport chain, a component of the mitochondrial transition pore, or an inhibitor of glycolysis, reactive oxygen species, calcium dependent pathways, granzyme B, transcription, or translation.
13. The method of claim 11 wherein the pretreating is carried out for about 1-3 hours.
14. The method of claim 10 further comprising contacting the cells with compound 1 or 2 in combination with the pan-caspase inhibitor Q-VD-OPh.
15. The method of claim 11 further comprising analyzing components of the cell for additional apoptotic regulators.
16. The method of claim 8 wherein the cell is contacted with compound 1 or compound 2 in combination with a caspase inhibitor, and the consequences of rapid caspase-9 activation without activation of caspase-8 following caspase-3 activation are evaluated.
17. A method of killing or inhibiting the growth of a cancer cell comprising contacting a cancer cell with an effective anticancer amount of compound 1 or 2:
thereby killing or inhibiting the growth of the cancer cell.
18. The method of claim 17 wherein the cancer cell is a breast cancer cell, a cervical cancer cell, a leukemia cell, a lymphoma cell, a lung cancer cell, a melanoma cell, or an osteosarcoma cell.
19. A method of inducing caspase-3/-7 activity and inducing subsequent PARP-1 cleavage in a cell within 2 hours comprising contacting an animal cell with an effective amount of compound 1 or compound 2:
thereby inducing caspase-3/-7 activity and inducing subsequent PARP-1 cleavage in the cell.
20. A composition comprising compound 1:
and water.