Thiosemicarbazones Can Act Synergistically with Anthracyclines to Downregulate CHEK1 Expression and Induce DNA Damage...

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Anthracyclines are common anticancer drugs but often induce multidrug resistance (MDR).
• Thiosemicarbazones have shown potential in overcoming drug resistance.
• Pediatric solid tumors frequently develop resistance to standard therapies.

Purpose of the Study:

• To investigate the synergistic effects of combining anthracyclines with thiosemicarbazones in pediatric solid tumor cells.
• To elucidate the underlying mechanism of this synergistic interaction.
• To evaluate the potential of this combination therapy for overcoming MDR.

Main Methods:

• Treatment of pediatric solid tumor cell lines with combinations of anthracyclines (doxorubicin, daunorubicin, mitoxantrone) and thiosemicarbazones (DpC, Dp44mT).
• Assessment of synergistic effects and Pgp expression levels.
• Analysis of DNA repair mechanisms, checkpoint kinase 1 (CHEK1) expression, and DNA double-strand breaks.
• Evaluation of cell death pathways, including mitotic catastrophe.

Main Results:

• All tested combinations demonstrated synergistic effects in pediatric solid tumor cell lines.
• Synergism was independent of Pgp expression, indicating a novel mechanism.
• The combination therapy led to impaired DNA repair control and cell death via mitotic catastrophe.
• Thiosemicarbazones downregulated CHEK1 expression, and both agents induced DNA double-strand breaks.
• Concomitant application achieved the strongest synergistic effect at lower drug concentrations.

Conclusions:

• A novel Pgp-independent synergistic mechanism exists between anthracyclines and thiosemicarbazones.
• This combination therapy effectively targets pediatric solid tumors by inducing mitotic catastrophe through impaired DNA repair.
• The findings offer a promising strategy for treating tumors irrespective of their Pgp status, potentially overcoming MDR.