There is no need to use any "promoting" agent to produce HCC in rodents. It has been shown long ago that HCC develop without additional exposure to "promoters" by nitrosamines such as N-nitrosomorpholine.(NNM) This does not only hold for the continuous exposure of rodents to NNM but also for limited exposure in so-called "stop experiments", which from my point of view are in any case pereferable since they permit to analyse the development of HCC after withdrawl of the carcinogen without any interference with effects of ongoing toxicity by the carcinigen apllied or with the variouss consequences of the administrationof of "promoters". It has been well documented that the promoter used most frequently in rodents, namely phenobarbital, produces liver neoplasms including HCC after long-term teratment without any preceding application of nitrosamines as "initiators". The question whether liver cirrhosis is a prerequisite of HCC development induced by chemicals in rodents has also been stidied in some detail. At least in the case of NNM and thioacetamide it has been shown that the combination of HCC and cirrhois is a matter of the dose applied: whereas high doses of NNM result in pronounced hepatocwellular (usually perivenular) necrosis (apoptpsis) eliciting reactive oval cell proliferation, fibrosis and cirhhosis and at the same time specific preneoplastic foci of altered hepatocytes (FAH), hepatocaellular adenomas (HCA) and HCC, low doses of the same compound largely avoid necrosis (apoptois), oval cell proliferation, and chirrhosis but, nevvertheless induce FAH, HCA, and HCC. The concept of "initiaition" and "promotion" dominating the literature for a long time may not be very helpful in the long run to understand neoplastic development. For more details on this problem I refer to chapters by Bannasch and Schröder in Pathology of the Liver (eds. McSween et al., Churchill Livingstone 2002) and bay Bannasch and Zerban in Liver Cancer (eds. Okuda and Tabor, Churchill Livingstone. New York 1997).

Hi Aastha,

phenobarbital is used to induce strong cytochrome P450 activity, leading to oxidative stress and tumor promotion. CCL4 also causes oxidative stress, but the main rationale for its use is the induction of liver fibrosis. Nitrosamine alone induce liver cancer without any fibrosis in mice, while most HCC in humans arise on a fibrotic/cirrhotic background.

The net outcome of using PB or CCL4 is accelerated tumor formation and increased tumor number/size respect to nitrosamine alone. Note that other factors promoting liver inflammation, such as obesity and high fat diet, also greatly enhance the nitrosamine carcinogenic effect.

Cheers,

Tommaso

Thank you Tommaso Mello for answering my question.

There is no need to use any "promoting" agent to produce HCC in rodents. It has been shown long ago that HCC develop without additional exposure to "promoters" by nitrosamines such as N-nitrosomorpholine.(NNM) This does not only hold for the continuous exposure of rodents to NNM but also for limited exposure in so-called "stop experiments", which from my point of view are in any case pereferable since they permit to analyse the development of HCC after withdrawl of the carcinogen without any interference with effects of ongoing toxicity by the carcinigen apllied or with the variouss consequences of the administrationof of "promoters". It has been well documented that the promoter used most frequently in rodents, namely phenobarbital, produces liver neoplasms including HCC after long-term teratment without any preceding application of nitrosamines as "initiators". The question whether liver cirrhosis is a prerequisite of HCC development induced by chemicals in rodents has also been stidied in some detail. At least in the case of NNM and thioacetamide it has been shown that the combination of HCC and cirrhois is a matter of the dose applied: whereas high doses of NNM result in pronounced hepatocwellular (usually perivenular) necrosis (apoptpsis) eliciting reactive oval cell proliferation, fibrosis and cirhhosis and at the same time specific preneoplastic foci of altered hepatocytes (FAH), hepatocaellular adenomas (HCA) and HCC, low doses of the same compound largely avoid necrosis (apoptois), oval cell proliferation, and chirrhosis but, nevvertheless induce FAH, HCA, and HCC. The concept of "initiaition" and "promotion" dominating the literature for a long time may not be very helpful in the long run to understand neoplastic development. For more details on this problem I refer to chapters by Bannasch and Schröder in Pathology of the Liver (eds. McSween et al., Churchill Livingstone 2002) and bay Bannasch and Zerban in Liver Cancer (eds. Okuda and Tabor, Churchill Livingstone. New York 1997).

Peter Sir, thank you so much for making such a wonderful effort to reply to my question.

Hi,

I hope this late answer will still help you.

Like Dr Bannasch i think promotor are not a necessary condition. I used a widely known protocol of intraperitoneal injection of DEN (ref: Schiffer E, Housset C, Cacheux W, Wendum D, Desbois-Mouthon C, Rey C, Clergue F, Poupon R, Barbu V, Rosmorduc O. Gefitinib, an EGFR inhibitor, prevents hepatocellular carcinoma development in the rat liver with cirrhosis. Hepatology. 2005 Feb;41(2):307-14.) in wistar rats to study expression of TSAP-6.

Liver changes were progressive from fibrosis to cirrhosis and finally HCC such as in human model.

Hope it will be helpfull.