Contribution of organic cation transporter 3 to cisplatin cytotoxicity in human cervical cancer cells

Genetic preservation of SLC22A3 in the Admixed and Xhosa populations living in the Western Cape

BACKGROUND

Amphiphilic solute facilitator organic cation transporters mediate the movement of various endogenous and exogenous organic cations, including crucial drugs like metformin, oxaliplatin, and lamivudine. These transporters are now seen as a potential explanation for inter-individual differences in drug effectiveness, contributing to 15-30% of such variability due to genetic factors.The aim of this study was to determine the baseline minor allele frequency distribution of 18 known coding SNPs in the SLC22A3 gene of 278 Cape Admixed (130) and Xhosa (148) individuals residing in Cape Town, South Africa.

METHODS

A convenience sampling method was used for sample collection. DNA extraction and subsequent amplification of target sites was carried out according to standard established methodologies. All genotyping was performed using the SNaPshot™ mini-seuqencing platform.

RESULTS

This study found no genetic polymorphisms in the coding region of the SLC22A3 gene of both the Xhosa and Cape Admixed individuals investigated.

CONCLUSION

This study has shown that SLC22A3 coding SNPs observed in other populations are absent in the sample of both Cape Admixed and Xhosa individuals studied. The lack of protein sequence variation was consistent with other studies and may reflect the significant physiological role of human organic cation transporter 3 in maintaining cellular and organismal homeostasis.

Rescue of Misfolded Organic Cation Transporter 3 Variants

Organic cation transporters (OCTs) are membrane proteins that take up monoamines, cationic drugs and xenobiotics. We previously reported novel missense mutations of organic cation transporter 3 (OCT3, SLC22A3), some with drastically impacted transport capabilities compared to wildtype. For some variants, this was due to ER retention and subsequent degradation of the misfolded transporter. For other transporter families, it was previously shown that treatment of misfolded variants with pharmacological and chemical chaperones could restore transport function to a certain degree. To investigate two potentially ER-bound, misfolded variants (D340G and R348W), we employed confocal and biochemical analyses. In addition, radiotracer uptake assays were conducted to assess whether pre-treatment with chaperones could restore transporter function. We show that pre-treatment of cells with the chemical chaperone 4-PBA (4-phenyl butyric acid) leads to increased membrane expression of misfolded variants and is associated with increased transport capacity of D340G (8-fold) and R348W (1.5 times) compared to untreated variants. We herein present proof of principle that folding-deficient SLC22 transporter variants, in particular those of OCT3, are amenable to rescue by chaperones. These findings need to be extended to other SLC22 members with corroborated disease associations.

Organic Cation Transporter-Mediated Accumulation of Quinolinium Salts in the LV Myocardium of Rodents

Purpose

Quaternary ammonium salts have demonstrated marked accumulation in the left ventricular (LV) myocardium of rodents and swine. To investigate the mechanism underlying this uptake, the present study examined the interaction of [¹⁸F]fluoroethylquinolinium ([¹⁸F]FEtQ) with the family of organic cation transporters (OCTs).

Procedures

The cellular uptake of [¹⁸F]FEtQ into HEK293 cells, expressing human OCT1, -2, or -3 (HEK293-hOCT), and its inhibition by corticosterone was evaluated in vitro. The inhibitory effect of decynium 22 (D 22) in vivo was also studied, using PET/CT of HEK293-hOCT tumor-bearing mice. Furthermore, the distribution kinetics of [¹⁸F]FEtQ were determined in rats, with and without pre-administration of corticosterone, and following administration to a non-human primate (NHP).

Results

The accumulation of [¹⁸F]FEtQ in HEK293-hOCT cells was 15–20-fold higher than in control cells and could be inhibited by corticosterone. in vivo, the uptake of [¹⁸F]FEtQ in the LV myocardium of corticosterone-treated rats was significantly reduced compared to that of untreated animals. Similarly, following administration of D 22 to HEK293-hOCT tumor-bearing mice, the peak tumor uptake of [¹⁸F]FEtQ was reduced by 40–45 % compared to baseline. Contrary to the distinct accumulation of [¹⁸F]FEtQ in the LV myocardium of rats, no cardiac uptake was observed following its administration to a NHP.

Conclusions

The quinolinium salt derivative [¹⁸F]FEtQ interacts with the family of OCTs, and this interaction could account, at least in part, for the increased uptake in the LV myocardium of rodents. Nonetheless, its low affinity for hOCT3 and the results of PET/CT imaging in a NHP indicate a limited clinical applicability as a radiopharmaceutical for cardiac and/or OCT imaging.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11307-022-01728-y.

Effects of cisplatin and acacetin on total antioxidant status, apoptosis and expression of OCTN3 in mouse testis

Cisplatin is a chemotherapeutic medication that also exhibits toxic effects on normal cells. Acacetin (ACA) is an herbal compound that exhibits anticancer properties with few side effects. We investigated the use and side effects of ACA and cisplatin on the male reproductive system. Mature male mice were divided into six groups: control group treated with DMSO, cisplatin group treated with 1 mg/kg cisplatin and three ACA groups treated with 10, 25 or 50 mg/kg ACA. All treatments were applied for three days. A final experimental group was treated with 50 mg/kg ACA for 10 days. At the end of the experiment, animals were sacrificed and reactive oxygen species (ROS), total antioxidant capacity (TAC), OCTN3 gene expression and apoptosis were measured in testis. TAC and OCTN3 gene expression were decreased, while ROS and apoptosis were increased in cisplatin group compared to other groups. All ACA groups exhibited decreased apoptosis and ROS levels, and increased TAC and OCTN3 gene expression compared to the cisplatin treated mice. ACA caused fewer adverse effects in testicular tissue than cisplatin. ACA appears to improve the oxidant-antioxidant system, accelerates cell regeneration and inhibits apoptosis.

The Relationship Between Actin Cytoskeleton and Membrane Transporters in Cisplatin Resistance of Cancer Cells

Cisplatin [cis-diamminedichloroplatinum (II)] is a platinum-based anticancer drug widely used for the treatment of various cancers. It forms interstrand and intrastrand cross-linking with DNA and block DNA replication, resulting in apoptosis. On the other hand, intrinsic and acquired cisplatin resistance restricts its therapeutic effects. Although some studies suggest that dramatic epigenetic alternations are involved in the resistance triggered by cisplatin, the mechanism is complicated and remains poorly understood. Recent studies reported that cytoskeletal structures regulate cisplatin sensitivity and that activities of membrane transporters contribute to the development of resistance to cisplatin. Therefore, we focus on the roles of actin filaments and membrane transporters in cisplatin-induced apoptosis. In this review, we summarize the relationship between actin cytoskeleton and membrane transporters in the cisplatin resistance of cancer cells.

Uptake Transporters of the SLC21, SLC22A, and SLC15A Families in Anticancer Therapy-Modulators of Cellular Entry or Pharmacokinetics?

Solute carrier transporters comprise a large family of uptake transporters involved in the transmembrane transport of a wide array of endogenous substrates such as hormones, nutrients, and metabolites as well as of clinically important drugs. Several cancer therapeutics, ranging from chemotherapeutics such as topoisomerase inhibitors, DNA-intercalating drugs, and microtubule binders to targeted therapeutics such as tyrosine kinase inhibitors are substrates of solute carrier (SLC) transporters. Given that SLC transporters are expressed both in organs pivotal to drug absorption, distribution, metabolism, and elimination and in tumors, these transporters constitute determinants of cellular drug accumulation influencing intracellular drug concentration required for efficacy of the cancer treatment in tumor cells. In this review, we explore the current understanding of members of three SLC families, namely SLC21 (organic anion transporting polypeptides, OATPs), SLC22A (organic cation transporters, OCTs; organic cation/carnitine transporters, OCTNs; and organic anion transporters OATs), and SLC15A (peptide transporters, PEPTs) in the etiology of cancer, in transport of chemotherapeutic drugs, and their influence on efficacy or toxicity of pharmacotherapy. We further explore the idea to exploit the function of SLC transporters to enhance cancer cell accumulation of chemotherapeutics, which would be expected to reduce toxic side effects in healthy tissue and to improve efficacy.

Functional organic cation transporters mediate osteogenic response to metformin in human umbilical cord mesenchymal stromal cells

BACKGROUND

Compelling evidence indicates that metformin, a low-cost and safe orally administered biguanide prescribed to millions of type 2 diabetics worldwide, induces the osteoblastic differentiation of mesenchymal stromal cells (MSCs) through the 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway. As a highly hydrophilic cationic compound, metformin uptake is facilitated by cell membrane organic cation transporters (OCTs) of the solute carrier 22A gene family. We hypothesized that to effectively enhance osteogenic differentiation, and ultimately bone regeneration, metformin must gain access into functional OCT-expressing MSCs.

METHODS

Data was obtained through immunoblotting, cellular uptake, mineralization and gene expression assays.

RESULTS

We demonstrate for the first time that functional OCTs are expressed in human-derived MSCs from umbilical cord Wharton's jelly, an inexhaustible source of nonembryonic MSCs with proven osteogenic potential. A clinically relevant concentration of metformin led to AMPK activation, enhanced mineralized nodule formation and increased expression of the osteogenic transcription factor Runt-related transcription factor 2 (RUNX2). Indeed, targeting OCT function through pharmacological and genetic approaches markedly blunted these responses.

CONCLUSIONS

Our findings indicate that functional OCT expression in UC-MSCs is a biological prerequisite that facilitates the intracellular uptake of metformin to induce an osteogenic effect. Future pre-clinical studies are warranted to investigate whether the expression of functional OCTs may serve as a potential biomarker to predict osteogenic responses to metformin.

Hybrid Gd3+/cisplatin cross-linked polymer nanoparticles enhance platinum accumulation and formation of DNA adducts in glioblastoma cell lines

New hybrid nanoparticles permitted MRI monitoring of a cisplatin infusion while enhancing drug accumulation and DNA adduct formation in glioblastoma cells.

Organic cation transporter 3 mediates cisplatin and copper cross-resistance in hepatoma cells

Platinum-based drugs are first-line compounds in the treatment of many solid cancers. Major obstacles are tumors that become resistant and toxic side effects, both largely due to the expression of transporters that mediate the cellular processing of platinum. In this study, we addressed the establishment of cisplatin resistance in the absence of copper transporter ATP7B that has been previously found to be overexpressed in various resistant cells. Cisplatin sensitivity, induction of apoptosis, drug accumulation, and transporter gene expression were determined in hepatoma cell lines. Knockout or overexpression of copper transporter ATP7B did not affect cisplatin sensitivity. Cisplatin resistant cells showed a stably reduced cisplatin accumulation and a downregulation of organic cation transporter 3 (OCT3). In contrast, OCT3 overexpression could reverse resistance. Reduced MT1 expression was detected in the resistant cell line, however transient and highly dependent on the presence of cisplatin. Cross-resistance to copper was also associated with OCT3 downregulation. Our results suggest that a decreased level of OCT3 expression results in resistance to cisplatin and copper. OCT3 may represent a novel target for improved prognosis and anticancer therapy, including HCC.

Upregulated SLC22A3 has a potential for improving survival of patients with head and neck squamous cell carcinoma receiving cisplatin treatment

Solute carrier family 22 member 3 (SLC22A3), also called organic cation transporter 3 (OCT3), is responsible for organic cation transport, which can eliminate many endogenous small organic cations, drugs, and toxins. This study investigated whether SLC22A3 expression is related to cisplatin uptake and the survival of patients with head and neck squamous cell carcinoma (HNSCC). Using immunohistochemical staining and digital image analysis, SLC22A3 expression was examined in 42 HNSCC patients who were postoperatively treated with or without adjuvant chemotherapy. SLC22A3-overexpressing SCC-4 cells and SLC22A3-knocked down SCC-25 cells were used to investigate the function of SLC22A3 in cisplatin uptake. We found that patients with higher SLC22A3 expression had longer survival times than those with lower SLC22A3 expression (p = 0.051). Moreover, among advanced T-stage patients receiving adjuvant cisplatin therapy, those with higher SLC22A3 expression had longer survival times than those with lower SLC22A3 expression (p = 0.006). An in vitro study demonstrated that SCC-25 cells with upregulated SLC22A3 expression were more sensitive to cisplatin than were SCC-4 cells with downregulated SLC22A3 expression. An increased uptake of cisplatin and an enhanced cytotoxic effect were observed in SLC22A3-overexpressing SCC-4 cells, and decreased uptake was found in SLC22A3-knocked down SCC-25 cells. Our results demonstrated that upregulated SLC22A3 expression can increase the cisplatin uptake and subsequently improve the survival of patients with HNSCC.

Molecular mechanisms of cisplatin resistance in cervical cancer

Patients with advanced or recurrent cervical cancer have poor prognosis, and their 1-year survival is only 10%–20%. Chemotherapy is considered as the standard treatment for patients with advanced or recurrent cervical cancer, and cisplatin appears to treat the disease effectively. However, resistance to cisplatin may develop, thus substantially compromising the efficacy of cisplatin to treat advanced or recurrent cervical cancer. In this article, we systematically review the recent literature and summarize the recent advances in our understanding of the molecular mechanisms underlying cisplatin resistance in cervical cancer.

[Mechanism of Platinum Derivatives Induced Kidney Injury]

Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug's toxicity such as the cisplatin's nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury.

Cellular transport mechanisms of cytotoxic metallodrugs: an overview beyond cisplatin

The field of medicinal inorganic chemistry has grown consistently during the past 50 years; however, metal-containing coordination compounds represent only a minor proportion of drugs currently on the market, indicating that research in this area has not yet been thoroughly realized. Although platinum-based drugs as cancer chemotherapeutic agents have been widely studied, exact knowledge of the mechanisms governing their accumulation in cells is still lacking. However, evidence suggests active uptake and efflux mechanisms are involved; this may be involved also in other experimental metal coordination and organometallic compounds with promising antitumor activities in vitro and in vivo, such as ruthenium and gold compounds. Such knowledge would be necessary to elucidate the balance between activity and toxicity profiles of metal compounds. In this review, we present an overview of the information available on the cellular accumulation of Pt compounds from in vitro, in vivo and clinical studies, as well as a summary of reports on the possible accumulation mechanisms for different families of experimental anticancer metal complexes (e.g., Ru Au and Ir). Finally, we discuss the need for rationalization of the investigational approaches available to study metallodrug cellular transport.

Klotho has dual protective effects on cisplatin-induced acute kidney injury

Klotho protects the kidney from ischemia-reperfusion injury, but its effect on nephrotoxins is unknown. Here we determined whether Klotho protects the kidney from cisplatin toxicity. Cisplatin increased plasma creatinine and induced tubular injury, which were exaggerated in Klotho haplosufficient (Kl/+) and ameliorated in transgenic Klotho overexpressing (Tg-Kl) mice. Neutrophil gelatinase-associated lipocalin and active caspase-3 protein and the number of apoptotic cells in the kidney were higher in Kl/+ and lower in Tg-Kl compared with wild-type mice. Klotho suppressed basolateral uptake of cisplatin by the normal rat kidney cell line (NRK), an effect similar to cimetidine, a known inhibitor of organic cation transport (OCT). A decrease in cell surface and total OCT2 protein and OCT activity by Klotho was mimicked by β-glucuronidase. The Klotho effect was attenuated by β-glucuronidase inhibition. On the other hand, OCT2 mRNA was reduced by Klotho but not by β-glucuronidase. Moreover, cimetidine inhibited OCT activity but not OCT2 expression. Unlike cimetidine, Klotho reduced cisplatin-induced apoptosis from either the basolateral or apical side and even when added after NRK cells were already loaded with cisplatin. Thus, Klotho protects the kidney against cisplatin nephrotoxicity by reduction of basolateral uptake of cisplatin by OCT2 and a direct anti-apoptotic effect independent of cisplatin uptake. Klotho may be a useful agent to prevent and treat cisplatin-induced nephrotoxicity.

Membrane transporters as mediators of Cisplatin effects and side effects

Transporters are important mediators of specific cellular uptake and thus, not only for effects, but also for side effects, metabolism, and excretion of many drugs such as cisplatin. Cisplatin is a potent cytostatic drug, whose use is limited by its severe acute and chronic nephro-, oto-, and peripheral neurotoxicity. For this reason, other platinum derivatives, such as carboplatin and oxaliplatin, with less toxicity but still with antitumoral action have been developed. Several transporters, which are expressed on the cell membranes, have been associated with cisplatin transport across the plasma membrane and across the cell: the copper transporter 1 (Ctr1), the copper transporter 2 (Ctr2), the P-type copper-transporting ATPases ATP7A and ATP7B, the organic cation transporter 2 (OCT2), and the multidrug extrusion transporter 1 (MATE1). Some of these transporters are also able to accept other platinum derivatives as substrate. Since membrane transporters display a specific tissue distribution, they can be important molecules that mediate the entry of platinum derivatives in target and also nontarget cells possibly mediating specific effects and side effects of the chemotherapeutic drug. This paper summarizes the literature on toxicities of cisplatin compared to that of carboplatin and oxaliplatin and the interaction of these platinum derivatives with membrane transporters.

Differential expression of organic cation transporter OCT-3 in oral premalignant and malignant lesions: potential implications in the antineoplastic effects of metformin

BACKGROUND

Recent evidence indicates that metformin, a biguanide used as first-line treatment for type 2 diabetes, prevents the conversion of carcinogen-induced oral dysplasias into head and neck squamous cell carcinomas (HNSCC), most likely by inhibiting mammalian target of rapamycin complex 1 (mTORC1) oncogenic signaling. Whether metformin acts directly at the primary tumor site or indirectly by modulating hormonal secretion from extratumoral organs remains unknown. As organic cation transporters (OCT) belonging to the solute carrier 22A gene family, including OCT-1, OCT-2, and OCT-3, mediate metformin uptake and activity, it is critical to define what role they play in the antineoplastic activity of metformin.

METHODS

Immunohistochemical and immunoblotting techniques were used in normal, dysplastic and HNSCC tissues, and HNSCC cell lines, respectively, to determine OCTs expression levels.

RESULTS

We report that only OCT-3 was highly expressed in a number of HNSCC cell lines, oral epithelial dysplasias, and well to moderately differentiated HNSCC. Indeed, inhibition of OCT-3 expression and activity in HNSCC cells prevented metformin-induced AMP-activated protein kinase activation and mTORC1 pathway inhibition. Moreover, in oral dysplasias, high OCT-3 expression localized to epithelial compartments where mTORC1 signaling was also upregulated suggestive of a potential local effect of metformin.

CONCLUSIONS

The concept of using metformin as a chemopreventive agent to control head and neck carcinogenesis is promising. Further work is warranted to elucidate largely unexplored mechanisms of metformin uptake and pharmacologic action that may ultimately influence the selection of the most suitable patients who can benefit from metformin in head and neck cancer chemoprevention.