p53-Mediated Down-Regulation of DNA Repair Gene MGMT via Interaction with Sp1 Transcription Factor

Strategic Insights -

Recent research published in Anticancer Research has identified a mechanism by which the p53 protein regulates the expression of the DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT). The study found that p53 sequesters the Sp1 transcription factor, preventing it from binding to the MGMT promoter and thus inhibiting MGMT expression. This interaction was observed in human tumor cells and was dose-dependent, with Sp1 overexpression abrogating the inhibitory effect of p53 on the MGMT promoter activity. The researchers concluded that sequestration of Sp1 could be one of the mechanisms by which p53 negatively regulates MGMT expression, enhancing sensitivity of tumor cells to O(6)-alkylguanine generating drugs.

Key Takeaways:

  • The p53 protein regulates the expression of the DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT) via interaction with the Sp1 transcription factor.
  • p53 sequesters Sp1, preventing it from binding to the MGMT promoter and inhibiting MGMT expression.
  • The interaction between p53 and Sp1 is dose-dependent, with Sp1 overexpression abrogating the inhibitory effect of p53 on the MGMT promoter activity.
  • The researchers observed stable interaction of Sp1 with wild-type p53 in HCT116 cells.
  • Recombinant p53 alone did not bind to the Sp1 consensus sequence, but overexpression of wild-type p53 reduced the binding of nuclear extract to the Sp1 consensus sequence.
  • The study suggests that sequestration of Sp1 could be one of the mechanisms by which p53 negatively regulates MGMT expression, enhancing sensitivity of tumor cells to O(6)-alkylguanine generating drugs.

Statistics:

  • The study found that HCT116 cells showed a stable interaction of Sp1 with wild-type p53.
  • The researchers observed a dose-dependent effect of Sp1 overexpression on the inhibitory effect of p53 on the MGMT promoter activity.
  • The study suggests that the sensitivity of tumor cells to O(6)-alkylguanine generating drugs could be enhanced by p53-mediated down-regulation of MGMT expression.

Sources:

  • Bocangel, D., et al. "p53-Mediated down-regulation of the human DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT) via interaction with Sp1 transcription factor." Anticancer Research 29.10 (2009): 3741-3750.
  • Bocangel, D. Department of Biochemistry, University of Texas Medical Branch, Galveston, TX 77555 USA.