Background: The high mobility group box 1 (hmgb1) is one of the frequently over-expressed genes
whose aberrant expression is reported in a number of human cancers. Various strategies are underway to inhibit
hmgb1 expression in cancer cells having considerable therapeutic value.
Objective: The present work involves selective transcriptional inhibition of the hmgb1 gene using selective DNA
triplex structure-based gene technology. Here, the promoter region of the hmgb1 gene at position (-183 to -165) from
the transcription start site as a target was selected using bioinformatic tools.
Methods: The DNA triplex formation by the DNA of the target gene and TFO was confirmed using UV absorption
spectroscopy, Circular Dichroism, and Isothermal Calorimetry.
Results: Treatment of HepG2 cell with specific Triplex-forming Oligonucleotide significantly downregulated
HMGB1 expression level at mRNA and protein levels by 50%, while the classical anticancer drugs, actinomycin/
adriamycin as positive controls showed 65% and the combination of TFO and drug decreased by 70%. The
anti-proliferative effects of TFO correlated well with the fact of accumulation of cells in the Go phase and apoptotic
cell death. Further, the binding of anti-cancer drugs to hmgb1 is stronger in DNA triplex state as compared
to hmgb1 alone, suggesting the combination therapy as a better option.
Conclusion: Therefore, the ability of hmgb1 targeted triplex-forming oligonucleotide in combination with triplex
selective anticancer drug holds promise in the treatment of malignancies associated with hmgb1 overexpression.
The result obtained may open up new vistas to provide a basis for the rational drug design and searching
for high-affinity ligands with a high triplex selectivity.