Expression and Functionality of Anti-Human Immunodeficiency Virus and Anticancer Drug Uptake Transporters in Immune Cells

Abstract

Almost all drugs used in anti-human immunodeficiency virus (HIV)-1 and anticancer therapies require membrane proteins to get into the cell to develop their proper activity. Nevertheless, little is known regarding the expression and activity of specific carriers involved in the uptake of these drugs in immune cells. Here, we assessed the mRNA levels, protein expression profile, and activity of the gene families SLC28 (coding for concentrative nucleoside transporters, hCNT1-3), SLC29 (equilibrative nucleoside transporters, hENT1-2), and SLC22 (organic cation transporters, hOCT1-3 and hOCTN1-2). Both hENTs and hCNT2 were abundant in primary lymphocytes, with a preferential activity of hENT1. A significant up-regulation in hENTs expression (100-fold) and activity (30-fold) was seen under stimulation of primary T lymphocytes. In contrast, monocytes, monocyte-derived macrophages (MDMs), and immature monocyte-derived dendritic cells predominantly expressed hCNT3, a functional transporter in MDMs. Finally, in immune cells, hOCTs showed a more heterogeneous expression profile and a lower activity than human nucleoside transporters (hNTs), although up-regulation of hOCTs also occurred upon lymphocyte activation. Overall, the expression and activity of most of the studied transporters emphasize their relevance in relation to anti-HIV and anticancer therapies. The identification of the transporter involved in each specific drug uptake in immune cells could help to optimize pharmacological therapeutic responses.

Transport of Lamivudine [(-)-β-l-2′,3′-Dideoxy-3′-thiacytidine] and High-Affinity Interaction of Nucleoside Reverse Transcriptase Inhibitors with Human Organic Cation Transporters 1, 2, and 3

“…The SLC22 gene family, which encodes for hOAT and hOCT proteins, has been associated with the uptake of antiviral drugs used in HIV and other viral infections (Chen and Nelson, 2000;Takeda et al, 2002). We previously determined that hOCTs are highly expressed, active, and up-regulated in immune cells (including CD4ϩ T cells, main targets of HIV) (Minuesa et al, 2008). Here, we first studied the interaction of hOCTs with NRTIs, finding a high affinity (IC 50 in the picomolar range) interaction in all cases.…”

“…As for influx transporters, some members of SLC28 and SLC29 have been associated with NRTI uptake and with anticancer nucleoside analogs (Pastor-Anglada et al, 2004;ErrastiMurugarren et al, 2007), although none of the functionally expressed members of SLC28 or SLC29 gene families seem to be involved in the uptake of AZT in immune cells (Purcet et al, 2006;Minuesa et al, 2008). Polyspecific organic anion, cation, and carnitine transporters of the SLC22 family also have been associated with the uptake of some nucleoside and nucleotide analogs and antiviral drugs.…”

“…As for human organic cation transporters (hOCTs), no specific member has been described yet as an NRTI transporter in immune cells, even though it has been suggested an organic cation transport for AZT and 3TC uptake in microglia and the renal brush-border membrane, respectively (Takubo et al, 2000a;Hong et al, 2001). Because we had found previously that hOCTs are well expressed and functionally active in immune cells and highly up-regulated after activation of CD4ϩ T cells (Minuesa et al, 2008), we were interested in studying the role of hOCTs in the uptake of NRTIs, the possible cross-inhibition between them, and whether these drugs interact and, therefore, inhibit the physiological function of hOCTs.…”

Relevance of the Organic Cation Transporters 1 and 2 for Antiretroviral Drug Therapy in Human Immunodeficiency Virus Infection

“…Minuesa et al (2008) could already show that an in vitro T-cell stimulation of peripheral blood mononuclear cells (PBMCs) could lead to an up-regulation of OCT1 but not of OCT2. The divergent results of the OCT2 expression could be because of the differences in the experimental settings as Minuesa et al (2008) used PBMCs instead of lymphoid tissue mononuclear cells, stimulated the cells with unspecific agents for T cell activation compared with the immune activation by HIV, and chose an in vitro setting in contrast to our in vivo studies with HIV-infected patients. The increased expression cannot be a consequence of therapy because all the patients included were therapy-naive.…”

Identification and Characterization of Proximal Promoter Polymorphisms in the Human Concentrative Nucleoside Transporter 2 (SLC28A2)

“…In particular, CNT1 prefers pyrimidine-based analogs (e.g., zidovudine, gemcitabine, cytarabine), CNT2 prefers purine-based analogs (e.g., ribavirin and didanosine), and CNT3 accepts both purine and pyrimidinebased analogs (e.g., cladribine, gemcitabine, and fludarabine) (Gray et al, 2004). Human CNT2 is localized to the apical membranes of absorptive epithelial cells of the intestine, kidney, and liver and is also expressed in lymphocytes (Gray et al, 2004;Ferná ndez-Veledo et al, 2006;Meier et al, 2007;Minuesa et al, 2008). The role of CNT2 in the disposition and response to anticancer and antiviral nucleoside drugs has been characterized in intestinal tissues (Shin et al, 2006), renal epithelium (Damaraju et al, 2007;Elwi et al, 2009), and lymphocytes (Molina-Arcas et al, 2003;Minuesa et al, 2008).…”