Antitumor activity of a small-molecule inhibitor of human silent information regulator 2 enzymes

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• NAD-dependent deacetylases, including SIRT1, regulate cellular stress responses and tumorigenesis via protein deacetylation.
• Key targets include p53 and the BCL6 oncoprotein, crucial in cell cycle control and cancer development.

Purpose of the Study:

• To identify and characterize a novel inhibitor of human SIRT1 and SIRT2 deacetylase activity.
• To evaluate the therapeutic potential of this inhibitor, named cambinol, in preclinical models of cancer.

Main Methods:

• Compound screening to identify SIRT1/SIRT2 inhibitors.
• In vitro studies assessing cambinol's effects on protein acetylation, cell cycle arrest, and apoptosis in cancer cell lines.
• In vivo studies evaluating cambinol's efficacy and tolerability in a Burkitt lymphoma xenograft mouse model.

Main Results:

• Cambinol was identified as an inhibitor of human SIRT1 and SIRT2 deacetylase activity.
• Inhibition of SIRT1 by cambinol during genotoxic stress induced hyperacetylation of stress response proteins and cell cycle arrest.
• Cambinol treatment of Burkitt lymphoma cells induced apoptosis, associated with hyperacetylation of BCL6 and p53, leading to BCL6 inactivation and checkpoint activation.
• Cambinol demonstrated well tolerability in mice and inhibited Burkitt lymphoma xenograft growth.

Conclusions:

• Cambinol effectively inhibits SIRT1 and SIRT2 deacetylase activity.
• Cambinol exhibits potent antitumor activity against Burkitt lymphoma, likely through combined BCL6 inactivation and checkpoint activation.
• Inhibitors of NAD-dependent deacetylases, such as cambinol, represent a promising new class of anticancer agents.