Designed FHIT alleles establish that Fhit-induced apoptosis in cancer cells is limited by substrate binding.

The FHIT gene is inactivated early in the development of many human tumors, and Fhit-deficient mice have increased cancer incidence. Viral reexpression of Fhit kills Fhit-deficient cells by induction of apoptosis. Fhit, a member of branch 2 of the histidine-triad superfamily of nucleoside monophosphate hydrolases and transferases, is a diadenosine polyphosphate hydrolase, the active-site histidine of which is not required for tumor suppression. To provide a rigorous test of the hypothesis that Fhit function depends on forming a complex with substrates, we designed a series of alleles of Fhit intended to reduce substrate-binding andor hydrolytic rates, characterized these mutants biochemically, and then performed quantitative cell-death assays on cancer cells virally infected with each allele. The allele series covered defects as great as 100,000-fold in k(cat) and increases as large as 30-fold in K(M). Nonetheless, when mutant FHIT genes were expressed in two human cancer cell lines containing FHIT deletions, reductions in apoptotic activity correlated exclusively with K(M). Mutants with 2- and 7-fold increases in K(M) significantly reduced apoptotic indices, whereas the mutant with a 30-fold increase in K(M) retained little cellular function. These data indicate that the proapoptotic function of Fhit is limited by substrate binding and is unrelated to substrate hydrolysis.
AuthorsFrancesco Trapasso, Agnieszka Krakowiak, Rossano Cesari, Jeffrey Arkles, Sai Yendamuri, Hideshi Ishii, Andrea Vecchione, Tamotsu Kuroki, Pawel Bieganowski, Helen C Pace, Kay Huebner, Carlo M Croce, Charles Brenner
JournalProceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 100 Issue 4 Pg. 1592-7 (Feb 18 2003) ISSN: 0027-8424 [Print] United States
PMID12574506 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Neoplasm Proteins
  • fragile histidine triad protein
  • Acid Anhydride Hydrolases
  • Acid Anhydride Hydrolases
  • Alleles
  • Apoptosis (physiology)
  • Cell Line
  • Flow Cytometry
  • Humans
  • Kinetics
  • Mutation
  • Neoplasm Proteins (genetics, isolation & purification, metabolism, physiology)
  • Neoplasms (genetics, pathology)
  • Substrate Specificity
  • Tumor Cells, Cultured

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research network!

Choose Username:
Verify Password: