Meat intake and risk of non-Hodgkin lymphoma.

We conducted a population-based, case-control study to test the hypothesis that consumption of meat and meat-related mutagens increases the risk of non-Hodgkin lymphoma (NHL), and whether the associations are modified by N-acetyltransferase (NAT) 1 and 2. Participants (336 cases and 460 controls) completed a 117-item food frequency questionnaire. The risk of NHL was associated with a higher intake of red meat (OR = 1.5; CI, 1.1-2.2), total fat (OR = 1.4; CI, 1.0-2.1), and oleic acid (OR = 1.5; CI, 1.0-2.2). NHL risk was also associated with a higher intake of very well-done pork (OR = 2.5; 95 % CI, 1.4-4.3) and the meat-related mutagen MeIQx (OR = 1.6; 95 % CI, 1.1-2.3). Analyses of the major NHL histologic subtypes showed a positive association between diffuse large B cell lymphoma (DLBCL) and higher intake of red meat (OR = 2.1; 95 % CI, 1.1-3.9) and the association was largely due to meat-related mutagens as a positive association was observed for higher intakes of both MeIQx (OR = 2.4; 95 % CI, 1.2-4.6) and DiMeIQx (OR = 1.9; 95 % CI, 1.0-3.5). Although the OR for follicular lymphoma (FL) was also increased with a higher red meat intake (OR = 1.9; 95 % CI, 1.1-3.3), the association appeared to be due to increased oleic acid (OR = 1.7; 95 % CI: 0.9-3.1). We found no evidence that polymorphisms in NAT1 or NAT2 modify the association between NHL and meat-related mutagens. Our results provide further evidence that red meat consumption is associated with an increase in NHL risk, and new evidence that the specific components of meat, namely fat and meat-related mutagens, may be impacting NHL subtype risk differently.

Nitrosation of glycine ethyl ester and ethyl diazoacetate to give the alkylating agent and mutagen ethyl chloro(hydroximino)acetate.

Whereas nitrosation of secondary amines produces nitrosamines, amino acids with primary amino groups and glycine ethyl ester were reported to react with nitrite to give unidentified agents that alkylated 4-(p-nitrobenzyl)pyridine to produce purple dyes and be direct mutagens in the Ames test. We report here that treatment of glycine ethyl ester at 37 degrees C with excess nitrite acidified with HCl, followed by ether extraction, gave 30-40% yields of a product identified as ethyl chloro(hydroximino)acetate [ClC(=NOH)COOEt, ECHA] and a 9% yield of ethyl chloroacetate. The ECHA was identical to that synthesized by a known method from ethyl acetoacetate, strongly alkylated nitrobenzylpyridine, and may have arisen by N-nitrosation of glycine ethyl ester to give ethyl diazoacetate, which was C-nitrosated and reacted with chloride to give ECHA. Nitrosation of ethyl diazoacetate also yielded ECHA. Ethyl nitroacetate was not an intermediate as its nitrosation did not produce ECHA. ECHA reacted with aniline to give ethyl (hydroxamino)(phenylimino)acetate [PhN=C(NHOH)CO2Et]. This product was different from ethyl [(phenylamino)carbonyl]carbamate [PhNHC(=O)NHCO2Et], which was synthesized by reacting ethyl isocyanatoformate (OCN.CO2Et) with aniline. ECHA reacted with guanosine to give a derivative, which may have been a guanine-C(=NOH)CO2Et derivative. ECHA showed moderate toxicity and weak but significant mutagenicity without activation in Salmonella typhimurium TA-100 (mean, 1.31 x control value for 12-18 microg/plats) and for V79 mammalian cells (1.5-1.7 x control value for 60-100 microM). In conclusion, gastric nitrosation of glycine derivatives such as peptides with a N-terminal glycine might produce ECHA analogues that alkylate bases of gastric mucosal DNA and thereby initiate gastric cancer.

Expression of drug-metabolizing enzymes in the pancreas of hamster, mouse, and rat, responding differently to the pancreatic carcinogenicity of BOP.

BACKGROUND/METHODS: N-nitroso-bis(2-oxopropyl)amine (BOP) induces pancreatic ductal adenocarcinoma in Syrian golden hamsters, but not in rats or mice. To examine whether this difference is due to the diversity in the presence and distribution of enzymes involved in the metabolism of BOP, the cellular expression of nine cytochrome P-450 isozymes (CYP1A1, CYP1A2, CYP2B6, CYP2C8,9,19, CYP2D1, CYP2E1, CYP3A1, CYP3A2, and CYP3A4) and of three glutathione S-transferase isozymes (GST-pi, GST-alpha, and GST-mu) was investigated in the pancreas of hamsters, rats, and mice by immunohistochemistry. RESULTS: We found a wide species variation in the presence and cellular localization of the enzymes and a lack of several enzymes, including GST-alpha in islets, CYP2B6, CYP2C8,9,19, CYP3A1 in acinar cells, and CYP3A4 in ductal cells, in the rat as compared with hamster and mouse. CONCLUSION: Although the results could not clarify the reasons for the species differences in the pancreatic carcinogenicity of BOP, the presence of most of the cytochrome P-450 isozymes in pancreatic islets of all three species highlights the important role of the islets in drug metabolism.

In vitro pharmacokinetics and pharmacodynamics of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU).

The relationship between treatment efficacy and the pharmacokinetics (PK) and pharmacodynamics (PD) of anticancer drugs is poorly defined. 1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) is an alkylating agent used in the treatment of brain and other forms of cancer. It is postulated that BCNU kills cells by forming DNA interstrand cross-links. The present study was undertaken to characterize the PK and PD of BCNU in mouse L1210 cells. L1210 cells were exposed to BCNU (0-160 microM) and analyzed for intracellular BCNU concentrations, DNA interstrand cross-links, cell cycle phase, and cytotoxicity. The half-life of BCNU in cells was approximately 40 min. The maximum reduction of mitochondrial enzyme activity (maximum cell death) achieved within 24 hr after exposure to BCNU was concentration-dependent and could be described by a Hill equation. At lower concentrations, the area under the DNA interstrand cross-link-time curve linearly correlated with the maximum cell death and the area under the BCNU concentration-time curve. BCNU induced cell accumulation in the G(2)/M phase of the cell cycle, which continued even after apparent completion of cross-link repair. Loss of membrane permeability was minimal (approximately 2%) during the first 24 hr. Thereafter, cells died exponentially over the next 9 days, primarily by necrosis. In conclusion, while cytotoxicity was concentration-dependent, an indirect relationship was found among the time-course of BCNU concentrations, DNA interstrand cross-links, and cell death. Because of the disparity between the time-scale of PK and PD, focusing only on the early events may provide limited information about the process of anticancer drug-induced cell death.

Species differences in the distribution of drug-metabolizing enzymes in the pancreas.

We investigated the cellular expression of 9 cytochrome P450-isozymes (CYP1A1, CYPIA2, CYP2B6, CYP2C8,9,19, CYP2D1, CYP2E1, CYP3A1, CYP3A2, CYP3A4) and 3 glutathione S-transferase-isozymes (GST-pi, GST-alpha. GST-mu) in the pancreas of hamsters, mice, rats, rabbits, pigs, dogs and monkeys, and in comparison with the human pancreas. A wide variation was found in the cellular localization of these enzymes between the 8 species. Most enzymes were expressed in the pancreas of the hamster, mouse, monkey and human, whereas rats, pigs, rabbits and dogs were lacking several isozymes. However, in all of the species the islet cells expressed more enzymes than ductal and acinar cells. An exclusive expression of enzymes in the islet cells was found in the hamster (CYP2E1). mouse (CYP1A1 , CYP1A2, GST-alpha, GST-mu), rat (CYP2C8,9, 19). rabbit (CYP1A2, CYP2B6, GST-pi), and pig (CYP1AI). Although no polymorphism was found in the pancreas of animals, in human tissue four enzymes were missing in about 50% of the cases. The results imply a greater importance of the islet cells in the metabolism of xenobiotics within the pancreas. The differences in the distribution of these drug-metabolizing enzymes in the pancreas between the species call for caution when extrapolating experimental results to humans.

Differences in the expression of glutathione S-transferases in normal pancreas, chronic pancreatitis, secondary chronic pancreatitis, and pancreatic cancer.

INTRODUCTION: In our previous study, glutathione S-transferase-pi (GST-pi), a phase II drug metabolizing enzyme, was found to be expressed in pancreatic ductal and ductular cells but not acinar cells of the normal pancreas, chronic pancreatitis, and secondary pancreatitis caused by pancreatic cancer. A greater percentage of the cells expressing GST-pi was shown in the islets of chronic pancreatitis specimens compared with the normal pancreas and secondary pancreatitis. AIMS AND METHODOLOGY: To examine whether the increased number of islet cells expressing GST-pi and the absence in the acinar cells are compensated for by other GST isozymes, we investigated the expression of GST-alpha and GST-mu in the same specimens. RESULTS: Unlike the distribution of GST-pi, the distribution of GST-alpha and GST-mu in islets did not show marked differences between the three groups. However, in four of 18 primary chronic pancreatitis specimens, more islet cells (approximately 25%) expressed GST-alpha than in the normal pancreas and secondary chronic pancreatitis (both approximately 10%). The reactivity of cancer cells to GST-alpha, GST-mu, and GST-pi was similar to the ductal cells in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis. Contrary to the expression of GST-pi, no statistically significant differences were found in the distribution of GST-alpha and GST-mu in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis. CONCLUSION: The expression of the other GSTs does not compensate for the variation of expression of GST-pi. There was no specimen in each group that did not express at least one GST isozyme in islet, acinar, and ductal cells.