Working Paper Article Version 1 This version is not peer-reviewed

Inhibition of DNA Repair Pathways and Induction of ROS are Potential Mechanisms of Action of the Small Molecule Inhibitor BOLD-100 in Breast Cancer

Version 1 : Received: 21 July 2020 / Approved: 22 July 2020 / Online: 22 July 2020 (10:00:52 CEST)

A peer-reviewed article of this Preprint also exists.

Bakewell, S.; Conde, I.; Fallah, Y.; McCoy, M.; Jin, L.; Shajahan-Haq, A.N. Inhibition of DNA Repair Pathways and Induction of ROS Are Potential Mechanisms of Action of the Small Molecule Inhibitor BOLD-100 in Breast Cancer. Cancers 2020, 12, 2647. Bakewell, S.; Conde, I.; Fallah, Y.; McCoy, M.; Jin, L.; Shajahan-Haq, A.N. Inhibition of DNA Repair Pathways and Induction of ROS Are Potential Mechanisms of Action of the Small Molecule Inhibitor BOLD-100 in Breast Cancer. Cancers 2020, 12, 2647.

Abstract

BOLD-100, a ruthenium-based complex, sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (also known as IT-139, NKP1339 or KP1339), is a novel small molecule drug that demonstrated a manageable safety profile at the maximum tolerated dose and modest antitumor activity in a phase I clinical trial. BOLD-100 has been reported to inhibit the upregulation of the endoplasmic reticulum stress sensing protein GRP78. However, response to BOLD-100 varies in different cancer models and the precise mechanism of action in high-response versus low-response cancer cells remains unclear. In vitro studies have indicated that BOLD-100 induces cytostatic rather than cytotoxic effects as a monotherapy. To understand BOLD-100 mediated signaling mechanism in breast cancer cells, we used estrogen receptor positive (ER+) MCF7 breast cancer cells to obtain gene-metabolite integrated models. Particularly, BOLD-100 significantly reduced expression of genes involved in the DNA repair pathway. BOLD-100 also induced reactive oxygen species (ROS) and phosphorylation of histone H2AX, gH2AX (Ser139), suggesting disruption of proper DNA surveillance. In estrogen receptor negative (ER-) breast cancer cells, combination of BOLD-100 with a PARP inhibitor, olaparib, induced significant inhibition of cell growth and xenografts and increased gH2AX. Thus, BOLD-100 is a novel DNA repair pathway targeting agent and can be used with other chemotherapies in ER- breast cancer.

Keywords

breast cancer; BOLD-100; olaparib; triple negative breast cancer

Subject

Biology and Life Sciences, Aging

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