The activity of a novel mithramycin analog is related to its binding to DNA, cellular accumulation, and inhibition of Sp1-driven gene transcription

Chem Biol Interact. 2014 Aug 5:219:123-32. doi: 10.1016/j.cbi.2014.05.019. Epub 2014 Jun 4.


DIG-MSK (demycarosyl-3D-β-D-digitoxosyl-mithramycin SK) is a recently isolated compound of the mithramycin family of antitumor antibiotics, which includes mithramycin A (MTA) and mithramycin SK (MSK). Here, we present evidence that the binding of DIG-MSK to DNA shares the general features of other mithramycins such as the preference for C/G-rich tracts, but there are some differences in the strength of binding and the DNA sequence preferentially recognized by DIG-MSK. We aimed at gaining further insights into the DIG-MSK mechanism of action by direct comparison with the effects of the parental MTA. Similar to MTA, MSK and DIG-MSK accumulated rapidly in A2780, IGROV1 and OVCAR3 human ovarian cancer cell lines, and DIG-MSK was a potent inhibitor of both basal and induced expression of an Sp1-driven luciferase vector. This inhibitory activity was confirmed for the endogenous Sp1 gene and a set of Sp-responsive genes, and compared to that of MTA and MSK. Furthermore, DIG-MSK was stronger than MTA as inhibitor of Sp3-driven transcription and endogenous Sp3 gene expression. Differences in the effects of MTA, MSK and DIG-MSK on gene expression may have a large influence on their biological activities.

Keywords: Cell Uptake; DNA-binding; Mithramycin; Ovarian cancer; Transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibiotics, Antineoplastic / pharmacology*
  • Antibiotics, Antineoplastic / therapeutic use
  • Binding Sites / physiology
  • Cell Line, Tumor
  • Female
  • GPI-Linked Proteins / genetics
  • GPI-Linked Proteins / physiology
  • Gene Expression Regulation, Neoplastic / physiology*
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / physiology
  • Kinetics
  • Ovarian Neoplasms / drug therapy*
  • Plicamycin / analogs & derivatives*
  • Plicamycin / pharmacology
  • Plicamycin / therapeutic use
  • RNA / chemistry
  • RNA / genetics
  • Real-Time Polymerase Chain Reaction
  • Sp1 Transcription Factor / genetics
  • Sp1 Transcription Factor / physiology*
  • Spectrometry, Fluorescence
  • Transcription, Genetic / physiology*


  • Antibiotics, Antineoplastic
  • GPI-Linked Proteins
  • Intracellular Signaling Peptides and Proteins
  • Sp1 Transcription Factor
  • ULBP1 protein, human
  • demycarosyl-3D-digitoxosylmithramycin SK
  • RNA
  • Plicamycin