Project Identifier: LLNL-94-111
Project Title:
Do Food Mutagens Cause Damage in Human Colon?
Principle Investigator:
Dr. Kenneth W. Turteltaub
Project started in: 1994
Project Funding Information:
Project received funding in Fiscal Year 1995.
Project used human subjects in Fiscal Year 1995.
Funding Sources:
Some of this funding supported collaborators in the United Kingdom for handling samples and patient interactions.
Project does not involve use of multiple protocols/subprojects.
IRB Review:
Type of Review: Full Board
Most Recent Approval: September 20, 1995
IRB Approval Number: 94-111
Number of Human Subjects in the Last Reporting Period for this Project: 3
(Reporting periods vary.)
Type of Human Subjects Involvement:
The aim of this study is to determine if two well-characterized mutagens that are present in the human diet are metabolized similarly in humans and rodents. This comparison is very important for determining if these compounds contribute to the incidence of colon cancer in the western world since rodents have been used to assess the potential carcinogenicity of these compounds. This comparison will help establish how the rodents used in cancer studies compare to the human response and will thus increase the confidence in the human risk assessments made using animals models. This study is a collaboration between LLNL, Dr. S Leveson (York District Hospital, UK) and Dr. C. Garner (University of York, UK).
Human subjects will be given low amounts of 14C-MeIQx and PhIP ((2-amino-3,4-dimethylimidazo[4,5-f]quinoxaline) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, respectively; 0.592 MBq/person) that are naturally present in food. The human subjects (a total of 10 individuals ages 40 - 70) will be patients at the York District Hospital (Wigginton Road, York UK) with previously established colorectal cancer and who are to undergo surgery to remove the tumors. The samples we will use are colon tissue samples removed during surgery and blood drawn prior to surgery. Administration of the compounds, blood collection and surgery will be supervised and carried out at the York District Hospital by Dr. S Leveson. DNA will be isolated in the laboratory of Dr. C Garner University of York (Heslington, York). Only the purified DNA will be handled and analyzed at LLNL.
Briefly, human subjects who are colon cancer patients at the York District Hospital, after being fully informed as to the nature of the study and after giving consent to participate, will be administered either [14C]-PhIP or [14C]-MeIQx in a gelatin capsule, per os, (2 - 6 µg/kg; maximum activity 0.592 MBq/person) 6 hours prior to surgery. One hour prior to surgery, blood will be drawn (50 mls by vein puncture) to determine the circulating levels of PhIP or MeIQx. Colon tissue removed during surgery will be placed on dry ice and immediately frozen. The location and amount of tissue removed will be determined by the surgeon but will principally be tumor tissue. The frozen tissue will be homogenized and the DNA will be extracted using phenol:chloform followed by anion exchange chromatography at the University of York. The purified DNA will be sent to LLNL and analyzed for 14C-content by accelerator mass spectrometry(AMS). Likewise, blood removed 1 hour prior to surgery will be dried and sent to LLNL for analysis of 14C content by AMS. The levels of 14C will then be used to calculate the amount of PhIP or MeIQx covalently bound to the DNA of the colon or present in the blood. The activity of 14C given to the participants will be 3 x 10-3 mSv, approximately 20-times lower than a chest x-ray . Further, the chemical dose will be approximately equivalent to what a human receives from consumption of 1 - 10 hamburgers (2 - 6 µg/kg body weight). The human subjects will undergo the surgery whether or not they participate in this study.