It was recently reported that toombak, a type of snuff used in the Sudan, contained unusually high levels of tobacco-specific nitrosamines. To estimate the internal dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) received by individuals who use this type of tobacco, urine from a group of users was analyzed for 2 metabolites of NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNA...

The contributions of different enzymes to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) biotransformation were assessed in human lung microsomes prepared from peripheral lung specimens obtained from seven subjects. Metabolite formation was expressed as a percentage of total recovered radioactivity from [5-3H]NNK and its metabolites per milligram of protein per minute. 4-(Methylnitrosamin...

Phenethyl isothiocyanate (PEITC), 3-phenylpropyl isothiocyanate (PPITC), 4-phenylbutyl isothiocyanate (PBITC), and the newly synthesized 5-phenylpentyl isothiocyanate (PPeITC), 6-phenylhexyl isothiocyanate (PHITC), and 4-(3-pyridyl)butyl isothiocyanate (PyBITC) were tested for their abilities to inhibit tumorigenicity and DNA methylation induced by the tobacco-specific nitrosamine 4-(methylnitr...

Metabolism and disposition of the tobacco-specific N-nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent rodent lung carcinogen, were studied in rhesus monkeys. In three males receiving a single i.v. dose of [5-3H]NNK (0.72 mCi; 4.6-9.8 microg/kg), urine was collected for 10 days. Within the first 24 h, 86.0 +/- 0.7% of the dose was excreted. NNK-derived radioactivity wa...

A tobacco-specific component, 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK), is a major risk factor for many cancers. Recent reports have demonstrated that NNK exposure may be associated with tumor progression and chemoresistance in certain cancers. However, the underlying NNK-induced mechanism contributing to the aggressiveness of colorectal cancer (CRC) has not been thoroughly studied. In ...

Phenethyl isothiocyanate (PEITC), benzyl isothiocyanate (BITC), and phenyl isothiocyanate (PITC) were tested for their abilities to inhibit lung tumorigenesis and O6-methylguanine formation in lung DNA in duced by the tobacco-specific nitrosamine 4-(methylnitrosamino)-l-(3pyridyl)-l-butanone (NNK) in A/J mice. Pretreatment with PEITC for 4 consecutive days at daily doses of 5 or 25 /¿mol inhib...

Phenethyl isothiocyanate (PEITC), benzyl isothiocyanate (BITC), and phenyl isothiocyanate (PITC) were tested for their abilities to inhibit lung tumorigenesis and O6-methylguanine formation in lung DNA induced by the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice. Pretreatment with PEITC for 4 consecutive days at daily doses of 5 or 25 mumol inhibi...

Epidemiological studies suggest that smoking during pregnancy and passive exposure of children to cigarette smoke may increase the cancer risk in children and young adults. We have previously shown that the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is an active transplacental carcinogen in Syrian golden hamsters when administered by s.c. injections to pre...

Previous studies in our laboratory showed that decaffeinated green tea and black tea extracts inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced tumorigenicity in A/J female mice. In order to understand the mechanism of the inhibitory action, we examined the effects of decaffeinated green tea, black tea, and tea components on the metabolic activation of NNK in vitro and in v...