Chemoprotection against cancer by induction of phase 2 enzymes

Biofactors. 2000;12(1-4):5-11. doi: 10.1002/biof.5520120102.


Induction of Phase 2 enzymes is an effective and sufficient strategy for achieving protection against the toxic and neoplastic effects of many carcinogens. It is proposed that the concept of Phase 2 enzymes as being responsible only for the conjugation of functionalized xenobiotics with endogenous cellular ligands such as glutathione (glutathione S-transferases) and glucuronic acid (UDP-glucuronosyltransferases) be expanded to include proteins with the following common characteristics: (a) coordinate induction by a broad range of chemical agents that all have the capacity to react with sulfhydryl groups; (b) possible regulation by common promoter elements; and (c) catalysis of reactions that lead to comprehensive protection against electrophile and reactive oxygen toxicities, by a wide variety of mechanisms. These mechanisms include: conjugation with endogenous ligands, chemical modification of reactive features of molecules that can damage DNA and other macromolecules, and generation or augementation of cellular antioxidants. In addition to the above conjugating enzymes, a provisional and partial list of Phase 2 proteins might include: NAD(P)H:quinone reductase, epoxide hydrolase, dihydrodiol dehydrogenase, gamma-glutamylcysteine synthetase, heme oxygenase-1, leukotriene B4 dehydrogenase, aflatoxin B1 dehydrogenase, and ferritin.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Anticarcinogenic Agents / pharmacology
  • Anticarcinogenic Agents / therapeutic use*
  • Enzyme Induction / drug effects*
  • Glucuronosyltransferase / metabolism
  • Glutamate-Cysteine Ligase / metabolism
  • Glutathione Transferase / metabolism
  • Heme Oxygenase (Decyclizing) / metabolism
  • Humans
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • Neoplasms / prevention & control*
  • Rats


  • Anticarcinogenic Agents
  • Heme Oxygenase (Decyclizing)
  • NAD(P)H Dehydrogenase (Quinone)
  • Glucuronosyltransferase
  • Glutathione Transferase
  • Glutamate-Cysteine Ligase