A perillyl alcohol-conjugated analog of 3-bromopyruvate without cellular uptake dependency on monocarboxylate transporter 1 and with activity in 3-BP-resistant tumor cells. (1st August 2017)

• Record Type: Journal Article
• Authors: Chen, Thomas C.; Yu, Jiali; Nouri Nigjeh, Eslam; Wang, Weijun; Myint, Phyo Thazin; Zandi, Ebrahim; Hofman, Florence M.; Schönthal, Axel H.
• Is Part Of: Cancer letters. Volume 400(2017)
• Page Start: 161
• Page End: 174
• Publication Date: 2017-08-01
• Subjects: Bromopyruvate -- Monocarboxylate transporter -- Perillyl alcohol -- Protein alkylation; 3-BP 3-bromopyruvate -- CFA colony formation assay -- GAPDH glyceraldehyde 3-phosphate dehydrogenase -- GSH glutathione -- MCT-1 monocarboxylate transporter 1 -- NAC N-acetylcysteine -- NEO218 perillyl alcohol conjugated to 3-bromopyruvate -- POH perillyl alcohol -- ROS reactive oxygen species -- SDH succinate dehydrogenase complex; Cancer -- Periodicals; Neoplasms -- Periodicals; Cancer -- Périodiques; Electronic journals; 616.994
• DOI: 10.1016/j.canlet.2017.04.015
• Languages: English
• ISSNs: 0304-3835

Abstract

Abstract: The anticancer agent 3-bromopyruvate (3-BP) is viewed as a glycolytic inhibitor that preferentially kills glycolytic cancer cells through energy depletion. However, its cytotoxic activity is dependent on cellular drug import through transmembrane monocarboxylate transporter 1 (MCT-1), which restricts its anticancer potential to MCT-1-positive tumor cells. We created and characterized an MCT-1-independent analog of 3-BP, called NEO218. NEO218 was synthesized by covalently conjugating 3-BP to perillyl alcohol (POH), a natural monoterpene. The responses of various tumor cell lines to treatment with either compound were characterized in the presence or absence of supplemental pyruvate or antioxidants N-acetyl-cysteine (NAC) and glutathione (GSH). Drug effects on glyceraldehyde 3-phosphate dehydrogenase (GAPDH) enzyme activity were investigated by mass spectrometric analysis. The development of 3-BP resistance was investigated in MCT-1-positive HCT116 colon carcinoma cells in vitro. Our results show that NEO218: (i) pyruvylated GAPDH on all 4 of its cysteine residues and shut down enzymatic activity; (ii) severely lowered cellular ATP content below life-sustaining levels, and (iii) triggered rapid necrosis. Intriguingly, supplemental antioxidants effectively prevented cytotoxic activity of NEO218 as well as 3-BP, but supplemental pyruvate powerfully protected cells only from 3-BP, not from NEO218. Unlike 3-BP, NEO218 exerted its potent cytotoxic activity irrespective of cellular MCT-1 status. Treatment of HCT116 cells with 3-BP resulted in prompt development of resistance, based on the emergence of MCT-1-negative cells. This was not the case with NEO218, and highly 3-BP-resistant cells remained exquisitely sensitive to NEO218. Thus, our study identifies a mechanism by which tumor cells develop rapid resistance to 3-BP, and presents NEO218 as a superior agent not subject to this cellular defense. Furthermore, our results offer alternative interpretations of previously published models on the role of supplemental antioxidants: Rather than quenching reactive oxygen species (ROS), supplemental NAC or GSH directly interact with 3-BP, thereby neutralizing the drug's cytotoxic potential before it can trigger ROS production. Altogether, our study introduces new aspects of the cytotoxic mechanism of 3-BP, and characterizes NEO218 as an analog able to overcome a key cellular defense mechanism towards this drug. Highlights: 3-Bromopyruvate (3BP) conjugated to perillyl alcohol (POH) created novel NEO218. NEO218 alkylates GAPDH and depletes cellular ATP, leading to necrosis. Loss of MCT1 transmembrane protein is a mechanism of 3BP resistance. Unlike 3BP, NEO218 also kills tumor cells lacking MCT1. NEO218 should be explored further as a potential cancer therapy.