Fused isoselenazolium salts suppress breast cancer cell growth by dramatic increase in pyruvate-dependent mitochondrial ROS production

Marina Makrecka-Kuka,Pavels Dimitrijevs,Ilona Domracheva,Pavel Arsenyan,Kristaps Jaudzems,Maija Dambrova

doi:10.1038/s41598-020-78620-8

Abstract

The development of targeted drugs for the treatment of cancer remains an unmet medical need. This study was designed to investigate the mechanism underlying breast cancer cell growth suppression caused by fused isoselenazolium salts. The ability to suppress the proliferation of malignant and normal cells in vitro as well as the effect on NAD homeostasis (NAD+, NADH, and NMN levels), NAMPT inhibition and mitochondrial functionality were studied. The interactions of positively charged isoselenazolium salts with the negatively charged mitochondrial membrane model were assessed. Depending on the molecular structure, fused isoselenazolium salts display nanomolar to high micromolar cytotoxicities against MCF-7 and 4T1 breast tumor cell lines. The studied compounds altered NMN, NAD+, and NADH levels and the NAD+/NADH ratio. Mitochondrial functionality experiments showed that fused isoselenazolium salts inhibit pyruvate-dependent respiration but do not directly affect complex I of the electron transfer system. Moreover, the tested compounds induce an immediate dramatic increase in the production of reactive oxygen species. In addition, the isoselenazolothiazolium derivative selectively binds to cardiolipin in a liposomal model. Isoselenazolium salts may be a promising platform for the development of potent drug candidates for anticancer therapy that impact mitochondrial pyruvate-dependent metabolism in breast cancer cells.

Highlights

The development of targeted drugs for the treatment of cancer remains an unmet medical need
All the compounds demonstrated higher cytotoxic activities ( IC50 values ranging from 0.044 to 3.23 μM) than the reference compound, N a2SeO3, in breast tumor cell lines. IC50 values of the studied isoselenazolium salts 1–7 were in the same range as for doxorubicin, mammary carcinoma (4T1) cells were more susceptible to derivative 3 than to doxorubicin
Despite difference in compound potency, the most pronounced increase in the H2O2/O ratio in the presence of isoselenazolium salts 3 and 6 was observed when pyruvate and malate were used as substrates (Fig. 3C). These results indicate that isoselenazolium salts most likely affects pyruvate-dependent mitochondrial metabolism

Summary

Introduction

The development of targeted drugs for the treatment of cancer remains an unmet medical need. We elaborated methods for the preparation of novel, stable fused isoselenazolium salts, namely, systems with a Se–N+ bond[22] These compounds, which possess electrophilic selenium in their structure, exhibit glutathione peroxidase-like properties, are toxic to S. feltiae, induce DNA double-strand damage at moderate doses, and display excellent antibacterial activity[23,24,25]. We evaluated the ability of isoselenazolium salts to inhibit human breast adenocarcinoma MCF-7 and mouse carcinoma 4T1 proliferation Their effects on rat cardiomyoblasts (H9C2), mouse fibroblasts (NIH 3T3), primary human epidermal keratinocytes (HEKa), Madin-Darby Canine Kidney (MDCK) cells, and rat vascular smooth muscle cells (A7r5) are included in this study to demonstrate whether these compounds are harmless to normal cells. The ability of isoselenazolium salts to interact with CL-containing mitochondrial model membranes was evaluated by NMR spectroscopy and isothermal titration calorimetry (ITC)

Methods

Results

Discussion

Conclusion