By Vanessa Wasta
Johns Hopkins Medicine

The compound formed by cooking meats at very high temperatures acts as both an initiator and promoter of prostate cancer in rats, according to a Johns Hopkins Kimmel Cancer Center study.

Previous research in rats has shown that the compound, PhIP (2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine), causes early prostate cancer lesions only in the front of the organ called the ventral lobe and not in other lobes.

To begin to unravel why these pre-cancers congregate in this area, Yatsutomo Nakai, lead author on the study, mixed PhIP into food given to a group of rats for up to eight weeks, then studied the animals' prostates, intestines and spleens to look for genetic mutations. After four weeks, all lobes had significantly elevated mutations compared to rats that did not ingest PhIP. After eight weeks, researchers observed a significant increase in proliferation only in the ventral lobe, indicating that PhIP caused additional "promotional" events only in that lobe.

Researchers also observed in that lobe alone an increase in inflammatory mast cells and macrophages, suggesting that these cells may contribute to the development of prostate cancer.

"We stumbled across a new potential interaction between ingestion of cooked meat in the diet and cancer in the rat," said co-author Angelo De Marzo, senior author of the study and an associate professor of pathology, urology and oncology in the School of Medicine. "For humans, the biggest problem is that it's extremely difficult to tell how much PhIP you've ingested, since different amounts are formed depending on cooking conditions."

Co-authors were Jessica L. Hicks and William G. Nelson.

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