Presentation is loading. Please wait.

Presentation is loading. Please wait.

04/07/101 Aflatoxin,Tobacco, and the p53 Tumor Suppressor Gene: Cancer's Missing Link? Kerry Scott Lane M.D. Copyright September 21, 2000 North Carolina.

Similar presentations


Presentation on theme: "04/07/101 Aflatoxin,Tobacco, and the p53 Tumor Suppressor Gene: Cancer's Missing Link? Kerry Scott Lane M.D. Copyright September 21, 2000 North Carolina."— Presentation transcript:

1 04/07/101 Aflatoxin,Tobacco, and the p53 Tumor Suppressor Gene: Cancer's Missing Link? Kerry Scott Lane M.D. Copyright September 21, 2000 North Carolina State University

2 04/07/102 Aflatoxin And Tobacco  What is Aflatoxin  Natural Production of Aflatoxin  Evidence for Contamination of Tobacco  p53 Mutation as Biomarker  p53 Tumor Suppressor and All Cancers  Aflatoxin and Immunosuppressive States  Future Regulatory Framework (FDA-WHO-TART)  Future Technology Solutions

3 04/07/103 What is Aflatoxin ? Aflatoxin is a mycotoxin produced by Aspergillus Flavus, Aspergilli and Penicillium fungi. It is an complex aromatic heterocycle. It decomposes at 269 C.(Heat stable). AFB likely survives combustion, especially in ETS. It has profound genetic mutational capabilities due to its sterospecificity.

4 04/07/104 Natural Production of Aflatoxin  Aspergillus is found worldwide, described as a storage fungus.  Aflatoxin production is favored by heat and humidity.  Likely contamination of tobacco is episodic, random, and even microscopic.  Regulated by FDA on corn, grain, peanuts, since late 1960s. Also regulated by EU countries.  Max. permissible level for corn is 20ppb, milk- 0.5

5 04/07/105 Evidence for Contamination of Tobacco  Welty and Lucas, NC State 1968  Pattee, NC State 1969  Egypt 1994-El Magrahby  India 2000-Guhtka  Industry Internal Documents-WARF-1967  Combustion Studies- Kentucky 1970s  Combustion Studies-Cincinnati-Lane 1978  Human experiments and p53 biomarkers and adducts.

6 04/07/106 p53 Mutations as Biomarker  p53 is the “Guardian of the genome” which instructs genetically damaged cells to repair or die.  As a tumor suppressor gene it is a last ditch effort to prevent cancer.  p 53 is the most common mutation in all cancers.  Most typically laboratory cancer experiments use aflatoxin to mutate p53.  Over 10,000 articles on Medline about aflatoxin but none had made the aflatoxin-tobacco connection.

7 04/07/107 p53 and most Cancers  p53 mutations by aflatoxin at codon 249 AGG to AGT thought to cause liver cancer. (G-T transversions).  Guanines preferentially bound by aflatoxin covalently, especially poly GG, GGG and GCs.  Lung cancer “hotspot” is codon 249, AGG to ATG  WHO-IARC database analysis show substantial mutations in human cancers consistent with aflatoxin etiology.  Dennisenko has shown aflatoxin mutates p53 often consistent with WHO data.  Breast cancer shows similar mutational profile.  Most cancers show p53 mutations.

8 04/07/108 Lung Cancer Mutational Spectra

9 04/07/109 p53, Lung Cancer and ETS

10 04/07/1010 Breast Cancer and Aflatoxin

11 04/07/1011 Aflatoxin and Immunosuppression  AFB is a carcinogen, teratogen, mutagen, inhibitor of protein synthesis, and is immunosuppressive.  AFB has been shown to increase HIV levels 500%  Smokers have increased HIV levels.  Increased HIV levels correlate with increased infectivity and poorer prognosis.  Therefore, AFB contaminated tobacco is likely contributing to the AIDS pandemic.

12 04/07/1012 Future Regulatory Framework (FDA-WHO-TART)  WHO FCTC seeks to regulate toxin levels on tobacco products worldwide by 2003.  TART-Tobacco-Aflatoxin Reduction Talks  Aflatoxin and mycotoxin contamination of tobacco are prime candidates for a Harm Reduction Strategy.  FDA will likely adopt similar guidelines soon.  Industry Compliance may provide limited legal immunity.

13 04/07/1013 Future Technology Solutions  Multiple solutions available to limit aflatoxin and mycotoxin production on tobacco products.  Monitoring of AFB and mycotoxin contamination from multiple curing practices will provide valuable data.  Prevention, remediation and terminal testing will result in a less harmful product with less liabilty.  Aflatoxin bioinformatics will yield cancer therapies, vaccines, diagnostic tests, and possibly cures for many human diseases.

14 04/07/1014 Aflatoxin and Tobacco Questions and Answers


Download ppt "04/07/101 Aflatoxin,Tobacco, and the p53 Tumor Suppressor Gene: Cancer's Missing Link? Kerry Scott Lane M.D. Copyright September 21, 2000 North Carolina."

Similar presentations


Ads by Google