Differential usage of the transport systems for folic acid and methotrexate in normal human T-lymphocytes and leukemic cells

Curcumin ameliorates the targeted delivery of methotrexate intercalated montmorillonite clay to cancer cells

Montmorillonite Clay (MMT) is aimed to develop as an orally administrable drug delivery vehicle with enhanced efficacy. Aiming to enhance the therapeutic index of methotrexate, curcumin is concomitantly used with methotrexate in the present study. Being folate antagonist in nature, methotrexate is internalized into cells by folate receptor (FR); which is over-expressed in certain human cancer cells such as cervical carcinoma cells (HeLa). Firstly, montmorillonite Clay (MMT) is organically modified (OMMT) with cetyl trimethyl ammonium bromide (CTAB) and used to intercalate curcumin and methotrexate separately, designated as OMMT-Cur and OMMT-MTX, respectively. XRD pattern demonstrated successful intercalation of therapeutics and an increase in clay interlayer distance facilitated by CTAB. The dissolution kinetics of methotrexate follows Higuchi model for both Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), while the release kinetics for curcumin fitted into Higuchi model for SGF and Hixson-Crowell model for SIF, respectively. OMMT-MTX are able to discriminate FR-positive HeLa cells from FR-negative breast cancer cells (MCF7); irrespective of alike cellular phenotypes. Further, the pre-treatment of HeLa cells with curcumin improves its sensitivity towards methotrexate causing a greater killing of the Hela cells. Together, the results propose the concomitant use of curcumin and methotrexate for successfully targeting highly invasive FR-positive carcinomas by means of folate receptor using MMTs.

Polymeric advanced delivery systems for antineoplasic drugs: doxorubicin and 5-fluorouracil

Conventional pharmaceuticals generally display the inability to transport active ingredients directly to specific regions of the body, amongst some of their main limitations. The distribution of the drugs in the circulatory system may lead to undesired toxicity, and therefore, adverse reactions. To address this situation, a selective transport of drugs is required, that is, releasing drugs specifically to the site of action in appropriate concentrations and in the right time. To achieve this goal, it is necessary to develop delivery systems that respond to several features, such as low toxicity, optimum properties for the transport and release of the drug, as well as a long half-life in the body. This feature paper critically provides an overview of different strategies of controlled drug release for two model antineoplasic drugs, i.e. doxorubicin (DOX) and 5-fluorouracil (5-FU). Any of the presented strategies for drug release possess advantages and disadvantages, and the selection of the strategy used will depend on the targeted tissue and nature of the drug.

A pivotal role of vitamin B9 in the maintenance of regulatory T cells in vitro and in vivo

Dietary factors regulate immunological function, but the underlying mechanisms remain elusive. Here we show that vitamin B9 is a survival factor for regulatory T (Treg) cells expressing high levels of vitamin B9 receptor (folate receptor 4). In vitamin B9-reduced condition in vitro, Treg cells could be differentiated from naïve T cells but failed to survive. The impaired survival of Treg cells was associated with decreased expression of anti-apoptotic Bcl2 and independent of IL-2. In vivo depletion of dietary vitamin B9 resulted in the reduction of Treg cells in the small intestine, a site for the absorption of dietary vitamin B9. These findings provide a new link between diet and the immune system, which could maintain the immunological homeostasis in the intestine.

The antiepileptic drugs phenobarbital and carbamazepine reduce transport of methotrexate in rat choroid plexus by down-regulation of the reduced folate carrier

Intrathecal methotrexate (MTX) has been associated with severe neurotoxicity. Because carrier-associated removal of MTX from the cerebrospinal fluid (CSF) into blood remains undefined, we determined the expression and function of MTX transporters in rat choroid plexus (CP). MTX neurotoxicity usually manifests as seizures requiring therapy with antiepileptic drugs (AEDs) such as phenobarbital (PB). Because we have demonstrated that PB reduces activity of MTX influx carrier reduced folate carrier (Rfc1) in liver, we investigated the influence of the AEDs PB, carbamazepine (CBZ), or gabapentin on Rfc1-mediated MTX transport in CP. Reverse transcriptase-polymerase chain reaction and Western blot analysis showed similar expression of the MTX influx carrier Rfc1 and organic anion transporter 3 or efflux transporter multidrug resistance-associated protein 1 (Mrp1) and breast cancer resistance protein (Bcrp) in rat CP tissue and choroidal epithelial Z310 cells. Confocal microscopy revealed subcellular localization of Rfc1 and Bcrp at the apical and of Mrp1 at the basolateral CP membrane. Uptake, efflux, and inhibition studies indicated MTX transport activity of Rfc1, Mrp1, and Bcrp. PB and CBZ but not gabapentin significantly inhibited Rfc1-mediated uptake of MTX in CP cells. Studies on the regulatory mechanism showed that PB significantly inhibited Rfc1 translation but did not alter carrier gene expression. Altogether, removal of intrathecal MTX across the blood-CSF barrier may be achieved through Rfc1-mediated uptake from the CSF followed by MTX extrusion into blood, particularly via Mrp1. Antiepileptic treatment with PB or CBZ causes post-transcriptional down-regulation of Rfc1 activity in CP. This mechanism may result in enhanced MTX toxicity in patients with cancer who are receiving intrathecal MTX chemotherapy by reduced CSF clearance of the drug.

Two pediatric osteosarcoma cases with delayed methotrexate excretion: its clinical course and management

High-dose methotrexate (MTX) chemotherapy extends the duration of hospitalization and introduces the risks of serious complications related to delayed MTX excretion. The treatment of delayed MTX excretion is largely dependent on invasive measures such as hemodialysis because the clinical data regarding the efficacy or safety of carboxypetidase G(2) is limited. We report here on the cases of two pediatric osteosarcoma patients with delayed MTX excretion and who were successfully managed using supportive measures. Potential life-threatening complications were prevented by administering high doses of leucovorin.