Influence of Cyclooxygenase Inhibitors on the Function of the Prostaglandin Transporter Organic Anion-Transporting Polypeptide 2A1 Expressed in Human Gastroduodenal Mucosa

Abstract

The human organic anion-transporting polypeptide 2A1 (OATP2A1) is a prostaglandin transporter expressed in several tissues and plays an important role for local distribution of prostaglandins, which contribute to the integrity of gastric mucosa. Blockade of prostaglandin pathways by cyclooxygenase (COX) inhibitors has been associated with serious side effects such as gastrointestinal ulceration and bleeding. However, little is known regarding OATP2A1 expression in the upper gastrointestinal tract and the potential impact of cyclooxygenase inhibitors on OATP2A1 function. We first investigated the expression of OATP2A1 mRNA and protein in human gastroduodenal mucosa using human biopsy specimens obtained from antrum, corpus, and duodenum. The results indicate that OATP2A1 is expressed in the neck region and deep pyloric glands of antrum and in parietal cells of gastric corpus. Second, we examined various COX inhibitors for their effects on OATP2A1 transporter activity. Using HEK293 cells expressing OATP2A1, we found that diclofenac and lumiracoxib are potent inhibitors of OATP2A1-mediated transport of prostaglandin (PG) E 2 with IC 50 values of 6.2 Ϯ 1.2 and 3.1 Ϯ 1.2 M. In contrast, indomethacin, ketoprofen, and naproxen led to significant stimulation of OATP2A1-mediated PGE 2 transport by 162.7 Ϯ 13.9, 77.2 Ϯ 3.6, and 32.3 Ϯ 4.9%, respectively. Taken together, our results suggest that various clinically used COX inhibitors have differential impact on the function of the prostaglandin transporter OATP2A1 in human stomach and that these effects may contribute to differences in the gastrointestinal side effects of COX inhibitors.

Influence of the flavonoids apigenin, kaempferol, and quercetin on the function of organic anion transporting polypeptides 1A2 and 2B1

“…The uptake experiments were performed as previously described [19][20]. Briefly, HEK293-OATP1A2, HEK293-OATP2B1, and the respective HEK293-VC cells were seeded in poly-D-lysine coated 12-well plates at an initial density of 7.5x10 5 cells / well.…”

“…Human embryonic kidney cells (HEK293) were transfected with the plasmid pQCXIN-OATP1A2 using a retroviral gene transfer and expression kit (Takara Bio Europe/Clontech, Saint-Germain-en-Laye, France). After geneticin (G-418; 500 µg/ml) treatment, single colonies were selected and characterized for OATP1A2 mRNA and protein expression using real-time PCR, immunofluorescence, and immunoblot analysis as previously described [19][20]. The polyclonal rabbit anti human …”

“…After geneticin (G-418; 500 µg/ml) treatment, single colonies were selected and characterized for OATP1A2 mRNA and protein expression using real-time PCR, immunofluorescence, and immunoblot analysis as previously described [19][20]. The polyclonal rabbit anti human …”

“…The uptake experiments were performed as previously described [19][20]. Briefly, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 12 the inhibitory constants (K i ) of flavonoids for OATP1A2 and OATP2B1 were performed using Dixon-Plot analyses [24].…”

Role of Organic Anion-Transporting Polypeptides for Cellular Mesalazine (5-Aminosalicylic Acid) Uptake

“…HEK293 cells were transfected with the plasmid pQCXIN-OATP1A2 using a retroviral gene transfer and expression kit (Takara Bio Europe/Clontech). After treatment with Geneticin (500 g/ml), single colonies were selected and characterized for SLCO1A2 mRNA expression using real-time PCR as described previously (Mandery et al, 2010). The primers for real-time PCR analysis of SLCO1A2 mRNA were forward 5Ј-AAGACCAACGCAGGATCCAT-3Ј and reverse 5Ј-GAGTTTCACCCATTCCACGTACA-3Ј with a resulting amplicon size of 101 base pairs.…”