I read some papers they observe anticancer dugs effects using through western blot assay. They observe PARP or caspases or BAX or BCL-2 (apoptosis related protein) after long time point 24 or 48 hrs of drug treatment. while other pathways like MAPK or PI3K pathways observe after 2 or 3 hrs of drug treatment. why time difference?
MAPK and PI3K proteins are stimulated due to the activation of tyrosine kinase receptors whereas the other proteins like caspases , BAX and BCL-2 are stimulated by P53 and others. So the appearance of such proteins depends on the pathway being stimulated first.
As Dr. Salwa said, after activation of MAPKs/PI3K proteins, they transduce the signals to more downstream which can activate one after one signaling mechanisms and transcription factors ultimately the expression of harmful proteins. This multi-step process needs more time. So that the upstream proteins are usually detected in early time points and the downstream are in late.
in my point of view each drug can react different in different cancer cell lines and i agree with Dr.Salwa's point. It depends upon ur drug and ur cell line...
First it reallye depends on the cell line and the protein kinases/phosphatases. If you have some oncogenes, that interact with kinases or are dependent on them, they show a higher sensitivity , when you block the activation by PI3K/MAPK inhibitors.
The second point is the pathway of apoptosis induction. Bcl-2, Bax and other mitochondrial associated proteins are much dependent on p53, but also on Akt and other inductors. And they also show a different pattern in cancer cell lines. So the answer to your question lays in the cell type, the dependency on singalling pathways and the induction of apoptosis by mitochondria. Perhaps you can explain your project more in detail.
kind regards
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