Investigating the Potential of Conjugated Selenium Redox Folic Acid as a Treatment for Triple Negative Breast Cancer

Soni Khandelwal,Julian E Spallholz,Gilbert Kirsch,Mallory Boylan,Lauren S Gollahon

doi:10.3390/antiox9020138

Soni Khandelwal, Julian E Spallholz + Show 3 more

Open Access

https://doi.org/10.3390/antiox9020138

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Journal: Antioxidants	Publication Date: Feb 5, 2020
Citations: 11	License type: CC BY 4.0

Affiliation: Texas Tech University, Université de Lorraine

Abstract

Previous studies have demonstrated that redox selenium compounds arrest cancer cell viability in vitro through their pro-oxidative activity by generating superoxide (O2•−). Currently, there are no efficacious treatment options for women with Triple Negative Breast Cancer (TNBC). However, the association between the over-expression of the Folate Receptor Alpha (FRA) in TNBC and other cancer cells, has led to the possibility that TNBCs might be treated by targeting the FRA with redox selenium covalent Folic Acid conjugates. The present study reports the synthesis of the redox active vitamer, Selenofolate, generating superoxide. Superoxide (O2•−) catalytic generation by Selenofolate was assessed by an in vitro chemiluminescence (CL) assay and by a Dihydroethidium (DHE) in vivo assay. Cytotoxicity of Selenofolate was assessed against the TNBC cell line MDA-MB-468 and an immortalized, mammary epithelial cell line, HME50-5E. Cytotoxicity of Selenofolate was compared to Folic Acid and sodium selenite, in a time and dose dependent manner. Selenofolate and selenite treatments resulted in greater inhibition of MDA-MB-468 cell proliferation than HME50-5E as evaluated by Trypan Blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) metabolic assay and Annexin V apoptosis assays. Folate receptor alpha (FRA) protein expression was assessed by Western blotting, with the experimental results showing that redox active Selenofolate and selenite, but not Folic Acid, was cytotoxic to MDA-MB-468 cells in vitro, suggesting a possible clinical option for treating TNBC and other cancers over-expressing FRA.

Highlights

Reduced Folic Acid plays a coenzyme role in the synthesis of purines and pyrimidines for DNA, and other cellular methylation reactions [1]
Dietary Folic Acid is absorbed by intestinal cells and released in its coenzyme form, 5-methyl-tetrahydrofolate (5-MTHF) into the bloodstream, the form which it is taken up by all cells [2] through one or more of four 5-MTHF Folic Acid receptor isoforms; (Folate Receptor alpha, Folate Receptor Alpha (FRA); beta, FRB; gamma, FRG; or delta, FRD)
The present study demonstrated the synthesis of Selenofolate from Folic Acid, and that Selenofolate as with selenite, both generated superoxide, which reduced MDA-MB-468 cell viability and proliferation in vitro as a function of dose and time over Folic Acid alone

Summary

Introduction

Reduced Folic Acid plays a coenzyme role in the synthesis of purines and pyrimidines for DNA, and other cellular methylation reactions [1]. Dietary Folic Acid is absorbed by intestinal cells and released in its coenzyme form, 5-methyl-tetrahydrofolate (5-MTHF) into the bloodstream, the form which it is taken up by all cells [2] through one or more of four 5-MTHF Folic Acid receptor isoforms;. (Folate Receptor alpha, FRA; beta, FRB; gamma, FRG; or delta, FRD). Uptake of Folic Acid into cells through these receptors maintains Folic Acid homeostasis, which is essential for cellular division and proliferation [3,4]. The FRA facilitates vitamin entry into the cell [7]. Its protein synthesis is through expression of the FOLR1 gene [8].

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