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

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.

Incorporation of Sulfonamide Moiety into Biguanide Scaffold Results in Apoptosis Induction and Cell Cycle Arrest in MCF-7 Breast Cancer Cells

“…Among OCT transporters, OCT3 were predominant in MDA-MB-231 cells, while in the case of MCF-7, we were not able to detect any of OCT transporters. In the case of MATE transporters similar significant expression of MATE 1 in both cell lines was reported [ 26 ]. These results are in agreement with outcomes of Cai et al [ 19 ] who also concluded that there is a relationship between the presence of cation-selective transporters, the effectiveness of metformin uptake and its antiproliferative activity.…”

“…The first step of the studies included establishing a relationship between cytotoxic effects of the examined compounds and their cellular uptake in MCF-7 and MDA-MB-231 cells. Both examined cell lines were previously characterized according to the expression of OCT, PMAT and MATE transporters [ 26 ]. Among OCT transporters, OCT3 were predominant in MDA-MB-231 cells, while in the case of MCF-7, we were not able to detect any of OCT transporters.…”

“…Even more considerable differences in the cellular uptake were reported in the case of compound 3 (1.127 ± 0.121 nmol/min/mg of proteins in MCF-7 vs. 0.109 ± 0.041 nmol/min/mg of proteins in MDA-MB-231 cells). The greater uptake of these compounds probably stems from their higher affinity towards PMAT transporters, whose expression is approximately three-fold higher in MCF-7 cells than in MDA-MB-231 cells [ 26 ]. In turn, compound 5 with p -propyl substituent was transported into MCF-7 and MDA-231 cells at a comparable rate (0.582 ± 0.074 nmol/min/mg proteins, and 0.542 ± 0.154 nmol/min/mg protein).…”

“…The compound possessing 10-carbon aliphatic chains (Mito-Met10) was found particularly effective since it triggered G1 cell cycle phase arrest in PDAC cells, enhanced their radiosensitivity and more potently abrogated PDAC growth in preclinical mouse models, compared to metformin. Moreover, our previous studies revealed that chemical modification of the metformin scaffold into sulfenamides [ 25 ] or halogenated sulfonamides [ 26 ] improves OCT-mediated cellular uptake in breast cancer cells, and subsequently leads to greater inhibition of their growth.…”

Pathological and Pharmacological Roles of Mitochondrial Reactive Oxygen Species in Malignant Neoplasms: Therapies Involving Chemical Compounds, Natural Products, and Photosensitizers

“…Metformin has been commonly used for treatment of patients with diabetic mellitus worldwide because of higher values of clinical efficacy, safety, and cost [ 78 ]. In addition to antidiabetic functions, biguanides have been reported to possess antineoplastic effects in various types of malignant tumors, such as cervical cancer, breast cancer, and pancreatic neuroendocrine tumors [ 79 , 80 , 81 ]. The associated anticancer mechanisms involve cell signaling molecules such as FAK, Akt, Rac1, RhoA, cyclin D1, and proliferating cell nuclear antigen [ 79 , 81 ].…”