is apoptosis always parp cleavage dependent? - cancer-parp-zvad-flow cyto (Jan/23/2007 )

Thanks everbody.
I am working on a natural product that apparently decreases sw480 and ht29 cells' viability,detected by wst8 and tryphan blue methods by dose and time dependent manner. Flow cytometry analysis with PI yileds 20-30 percent increase in sub-g1 population and same amount of increase in g2m cells (dose dependent) when the product is applied. Not all but 20 percent blockage is obtained with zvad-fmk. But caspase 3 and parp seems uncleaved in western blotting results. Is it possibble? Is it normal? What should I do to prove that there is apoptosis and g2m arrest (or disprove)?
mogcev

Thanks everbody.
I am working on a natural product that apparently decreases sw480 and ht29 cells' viability,detected by wst8 and tryphan blue methods by dose and time dependent manner. Flow cytometry analysis with PI yileds 20-30 percent increase in sub-g1 population and same amount of increase in g2m cells (dose dependent) when the product is applied. Not all but 20 percent blockage is obtained with zvad-fmk. But caspase 3 and parp seems uncleaved in western blotting results. Is it possibble? Is it normal? What should I do to prove that there is apoptosis and g2m arrest (or disprove)?
mogcev

caspase-3-independent apoptosis is possible as shown f.i. at caspase 3-deficient cells;

try FEBS Lett. 2002 Sep 25;528(1-3):63-9: "Identification of a caspase 3-independent role of pro-apoptotic factor Bak in TNF-alpha-induced apoptosis."
by Suyama E, Kawasaki H, Taira K.

Thank you very much for your share of thought, the Bearer. I will work on the paper carefully
mogcev