Antigene and Antiproliferative Effects of Triplex-Forming Oligonucleotide (TFO) Targeted on hmgb1 Gene in Human Hepatoma Cells.

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 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 are 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.