Cancer often results from a multistage process involving an initiating event (mediated by a viral infection or a carcinogenic chemical), followed by exposure to tumor promoters. Tumor promoters, a group of molecules that stimulate cell proliferation, cannot induce tumor formation by themselves. The phorbol esters, found in croton oil (obtained from the seeds of the croton plant, Croton tiglium), are potent tumor promoters. (Other examples of tumor promoters include asbestos and several components of tobacco smoke.) In one of the tumor-promoting actions of the phorbol esters, these molecules mimic the actions of DAG. In contrast to DAG, the phorbol esters are not easily disposed of. Explain the possible biochemical consequences of phorbol esters in an “initiated” cell. What enzyme is activated by both DAG and phorbol esters?
Cancer often results from a multistage process involving an initiating event (mediated by a viral
infection or a carcinogenic chemical), followed by exposure to tumor promoters. Tumor
promoters, a group of molecules that stimulate cell proliferation, cannot induce tumor formation
by themselves. The phorbol esters, found in croton oil (obtained from the seeds of the croton
plant, Croton tiglium), are potent tumor promoters. (Other examples of tumor promoters include
asbestos and several components of tobacco smoke.) In one of the tumor-promoting actions of
the phorbol esters, these molecules mimic the actions of DAG. In contrast to DAG, the phorbol
esters are not easily disposed of. Explain the possible biochemical consequences of phorbol
esters in an “initiated” cell. What enzyme is activated by both DAG and phorbol esters?
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