Validating TDP1 as an Inhibition Target for Lipophilic Nucleoside Derivative in Human Cells

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a DNA repair enzyme implicated in tumor resistance to topoisomerase 1 (TOP1) inhibitors like topotecan.
• Inhibiting TDP1 alongside TOP1 poisons may enhance anticancer therapy efficacy.
• Lipophilic molecules with aromatic substituents show potential as TDP1 inhibitors.

Purpose of the Study:

• To investigate the TDP1-dependent mechanism of action for compound 6d, a lipophilic nucleoside derivative.
• To confirm if compound 6d sensitizes cancer cells to topotecan via TDP1 inhibition.
• To analyze the impact of compound 6d and topotecan on TOP1 and TDP1 gene expression.

Main Methods:

• Tested compound 6d's effect on topotecan-induced cytotoxicity in wild-type and TDP1 knockout A549 lung cancer cells.
• Evaluated compound 6d's sensitizing effect in non-cancerous HEK293A cells.
• Assessed the expression levels of TOP1 and TDP1 genes following treatment with compound 6d and topotecan.

Main Results:

• Compound 6d sensitized wild-type A549 lung cancer cells to topotecan but not TDP1 knockout cells.
• No sensitizing effect was observed in non-cancerous HEK293A cells, irrespective of TDP1 status.
• Compound 6d did not alter TDP1 gene expression levels in either cell line.

Conclusions:

• The synergistic effect of compound 6d with topotecan is dependent on TDP1.
• Compound 6d likely acts as a direct TDP1 inhibitor, rather than affecting TDP1 gene regulation.
• This suggests compound 6d holds promise for enhancing topotecan-based anticancer strategies.