Effective Cellular Transport of Ortho-Halogenated Sulfonamide Derivatives of Metformin Is Related to Improved Antiproliferative Activity and Apoptosis Induction in MCF-7 Cells.

Magdalena Markowicz-Piasecka,Joanna Sikora,Kristiina M Huttunen,Ibrahim Komeil,Johanna Huttunen

doi:10.3390/ijms21072389

Abstract

Metformin is a substrate for plasma membrane monoamine transporters (PMAT) and organic cation transporters (OCTs); therefore, the expression of these transporters and interactions between them may affect the uptake of metformin into tumor cells and its anticancer efficacy. The aim of this study was to evaluate how chemical modification of metformin scaffold into benzene sulfonamides with halogen substituents (compounds 1–9) may affect affinity towards OCTs, cellular uptake in two breast cancer cell lines (MCF-7 and MDA-MB-231) and antiproliferative efficacy of metformin. The uptake of most sulfonamides was more efficient in MCF-7 cells than in MDA-MB-231 cells. The presence of a chlorine atom in the aromatic ring contributed to the highest uptake in MCF-7 cells. For instance, the uptake of compound 1 with o-chloro substituent in MCF-7 cells was 1.79 ± 0.79 nmol/min/mg protein, while in MDA-MB-231 cells, the uptake was considerably lower (0.005 ± 0.0005 nmol/min/mg protein). The elevated uptake of tested compounds in MCF-7 was accompanied by high antiproliferative activity, with compound 1 being the most active (IC50 = 12.6 ± 1.2 µmol/L). Further studies showed that inhibition of MCF-7 growth is associated with the induction of early and late apoptosis and cell cycle arrest at the G0/G1 phase. In summary, the chemical modification of the biguanide backbone into halogenated sulfonamides leads to improved transporter-mediated cellular uptake in MCF-7 and contributes to the greater antiproliferative potency of studied compounds through apoptosis induction and cell cycle arrest.

Highlights

Metformin represents a first-line strategy for the treatment of type 2 diabetes (T2DM), mainly because of high clinical value regarding glycemic control, safety profile and low costs [1]
The uptake of most sulfonamides was more efficient in MCF-7 cells than in MDA-MB-231 cells
Our previous studies [13] revealed that, among organic cation transporters (OCTs) transporters, OCT3 was predominant in MDA-MB-231 cells, while, in the case of MCF-7, we were not able to detect any of the OCT transporters

Summary

Introduction

Metformin represents a first-line strategy for the treatment of type 2 diabetes (T2DM), mainly because of high clinical value regarding glycemic control, safety profile and low costs [1]. Metformin is characterized by multidirectional biological activity, which brings beneficial effects on mortality rates in diabetic patients, improves the serum lipids profile and functions of the endothelium, as well as stimulates gene expression responsible for cellular antioxidant defense mechanisms [2]. A review of an exponentially growing number of publications allows to conclude that anticancer effects of metformin stem from several mechanisms: activation of LKB1/AMPK pathway and subsequent inhibition of the mammalian target of rapamycin (mTOR), induction of cell cycle arrest or apoptosis, inhibition of protein synthesis, activation of the immune system and a possible eradication of cancer stem cells [4]. A large number of publications are those that concern the inhibitory effect of metformin on the growth of breast cancer cells [5,6,7]. Metformin may reduce the mortality from cancers, increase the response to treatment in cancer cells when using radiotherapy and chemotherapy and reduce the malignancy and the likelihood of relapse [8]

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