•Human indoleamine 2,3-dioxygenase 2 (hIDO2)expression and purification.•hIDO2 bioassay system establishment.•hIDO2 inhibitor screening.As an analogue of IDO1 (indoleamine 2, 3-dioxygenase 1), the well-known new therapeutic target, IDO2 is receiving increased attention. Herein, the expression and purification of recombinant human IDO2 (hIDO2) and the establishment of a hIDO2 bioassay system on both enzymatic and cellular levels are described. Nine tryptanthrin derivatives were screened for potential hIDO2 inhibitory activities, and their Ki values, enzymatic and cellular IC50 values, as well as the types of inhibition were measured. The typtanthrin derivatives 5i, 5c and 5d (especially 5i) were found to be potent hIDO2 inhibitors with superior efficiency far better than that of the most frequently-used inhibitor L-1-MT. Two ultimate purposes of the present study have been achieved: establishing an IDO2 bioassay system and screening novel IDO2 inhibitors that can be used (directly or with some modifications) for potential therapeutic applications.

Sphingomyelin synthase (SMS) has two isoforms of SMS1 and SMS2, the last enzyme involved in the biosynthesis of sphingomyelin (SM), and has impact on the expression of membrane proteins. In the present study, we explored the potential effects of SMS on drug transporters, a special family of membrane proteins in human intestinal epithelial Caco-2 cells. The specific knockdown of SMS1 or SMS2 with siRNA in Caco-2 cells substantially decreased the expression and function of P-glycoprotein (P-gp) and multidrug resistance protein 2 (MRP2) rather than other drug transporters MRP1, MRP3, PEPT1, OATP2B1, and BCRP. In the SMS1 stable overexpressed Caco-2 cell line, the expression levels of P-gp and MRP2 and transcription factor pregnane X receptor (PXR) were upregulated and the phosphorylation levels of signaling pathways janus protein tyrosine kinase 2 (JAK-2) and extracellular signal-regulated kinases (ERK) were also evidently increased; however, the upregulated mRNA expression levels of PXR, P-gp, and MRP2 were diminished by inhibiting the phosphorylation of ERK and JAK-2. Furthermore, the SMS1 overexpression in Caco-2 cells altered the expression levels of ERM proteins ezrin and moesin, which are closely connected to the function of drug transporters. In conclusion, we herein demonstrate for the first time that in Caco-2 cells SMS regulates the expression and function of drug transporters P-gp and MRP2, and their regulator PXR is mediated by phosphorylated ERK and JAK-2 signaling pathways.

Besides the direct stimulation of erythropoiesis, erythropoietin (EPO) therapy in renal anemia may also play a regulatory role in maintaining the homeostasis of hematopoietic nutrients. It has been reported that EPO can stimulate intestinal iron absorption. However, the involvement of EPO in intestinal folate absorption remains elusive. The objective of this study was to investigate the effect of EPO on intestinal transport of folate in vitro and to elucidate the possible mechanism(s) involved in this regulation. Transport assays of folic acid were performed in Caco-2 monolayers treated with EPO. The effect of EPO on the expression of transporters involved in the folate absorption was investigated. The possible involvement of three main EPO signaling pathways, the janus protein tyrosine kinase 2 (JAK-2) pathway, extracellular signal regulated kinases (ERK) pathway, and phosphatidylinositol 3 kinase/Akt (PI3K/Akt) pathway, in the transporter regulation was explored. The absorptive flux (apical to basolateral) of folic acid was enhanced by EPO treatment in a dose-dependent manner, which was companied with the significant up-regulation of reduced folate carrier (RFC) and apical proton coupled folate transporter (PCFT). The efflux (basolaterial to apical) of folic acid was enhanced only by the high dose of EPO treatment, which was associated with the significant up-regulation of apical multidrug resistance-associated protein 2 (MRP2). The expression levels of all of these transporters were up-regulated by EPO treatment in a dose- and time-dependent manner. Transporter expression in response to blocking EPO induced activation of JAK-2, ERK, and PI3K/Akt was changed to a different extent. As a conclusion, intestinal folate absorption was enhanced by EPO treatment in vitro. Our findings provided direct evidence to establish the correlation between EPO and folate homeostasis.Keywords: Caco-2; ERK; erythropoietin; folate; JAK-2; MRP2; PCFT; PI3k/Akt; RFC;

Indoleamine 2,3-dioxygenase (IDO-1) is emerging as an important new therapeutic target for the treatment of cancer, neurological disorders, and other diseases that are characterized by pathological tryptophan metabolism. However, only a few structural classes are known to be IDO-1 inhibitors. In this study, a natural compound tryptanthrin was discovered to be a novel potent IDO-1 inhibitor by screening of indole-based structures. Three series of 13 tryptanthrin derivatives were synthesized, and the structure–activity analysis was undertaken. The optimization led to the identification of 5c, which exhibited the inhibitory activity at a nanomolar level. In vitro 5c dramatically augmented the proliferation of T cells. When administered to Lewis lung cancer (LLC) tumor-bearing mice, 5c significantly inhibited IDO-1 activity and suppressed tumor growth. In addition, 5c reduced the numbers of Foxp3+ regulatory T cells (Tregs), which are known to prevent the development of efficient antitumor immune responses.

We report a new controlled-release targeted drug delivery system based on core–shell structured silica mesoporous microspheres capped with superparamagnetic iron oxide nanoparticles. A ligand exchange strategy was developed to release guest molecules loaded in the mesopores. The system possesses a stimuli-responsive release property for the entrapped guest molecules, which is important for the delivery of toxic anticancer drugs in chemotherapy. A variety of stimulating agents, such as EDTA and sodium citrate, have been used to release the entrapped guest molecules, relying on the new ligand exchange triggered release mechanism. The release rate of guest molecules can be controlled by using different trigger-agents. The drug delivery system possesses high saturation magnetization (∼58 emu g−1) and superparamagnetic character, and thus can be easily enriched by a permanent magnet and re-dispersed in PBS solutions, which greatly facilitates its manipulation in practical applications. Cytotoxicity analyses of the drug delivery system based on human gastric cancer SGC-7901 and rat pheochromocytoma PC12 cells show low cytotoxicity and good biocompatibility. The uptake properties of the system by SGC-7901 and human cervical carcinoma HeLa cells demonstrate their great potential for applications in drug delivery. Furthermore, in vitro experiments show that cancer cells can be effectively killed by anticancer drug (paclitaxel) released from the system, further indicating the promise of the controlled-release drug delivery system in cancer treatment.

Previously, we have reported the design and synthesis of 4-aryl-1H-1,2,3-triazoles as inhibitors of indoleamine 2,3-dioxygenase (IDO), a promising therapeutic target of cancer. Here, we present the structure–activity relationship and enzyme kinetic studies on a series of 4-aryl-1H-1,2,3-triazoles. Three compounds (1, 6, 8) were found to possess more IDO inhibitory potency than the most commonly used 1-methyltryptophan. The results from the structure–activity relationship and molecular docking studies indicated that an electron-withdrawing group with low steric hindrance near the NH group of triazoles was necessary for the IDO inhibition.Three 4-aryl-1H-1,2,3-triazoles (1, 6, 8) possessed more IDO inhibitory potency than 1-methyltryptophan. A small electron-withdrawing group near the triazole NH was important for the IDO inhibition.Highlights► A series of 4-aryl-1H-1,2,3-triazoles were evaluated as IDO inhibitors. ► Three compounds (1, 6, 8) possessed more IDO inhibitory potency than 1-MT. ► A small electron-withdrawing group near the triazole NH was required for inhibition.

An unprecedented route to prepare terminal alkynes from 1,1-dibromo-1-alkenes mediated by Cs2CO3 was proven. 1,1-Dibromo-1-alkenes bearing various functional groups were efficiently converted to corresponding terminal alkynes in moderate to excellent yields.

Multidrug resistance-associated protein 2 (MRP2, ABCC2) is the second member of the MRP transporter family and functions physiologically as an organic anion transporter. Earlier studies have confirmed that radixin, which is a member of the ERM (ezrin/radixin/moesin) family, modulates MRP2 localization at the canalicular membrane in hepatocytes. The relationship between radixin and MRP2 – particularly, the effect of radixin on the expression and function of MRP2 in cells or tissues that co-express all three ERM proteins – has not been well studied. To examine the role of radixin in the expression and function of MRP2 and other MRPs, we chose human gastric carcinoma SGC-7901 cells that express all three ERM proteins rather than hepatocytes, which predominantly express radixin. Radixin stable knockdown SGC-7901 cells, which were constructed by RNAi, exhibited no compensatory up-regulation of ezrin or moesin. The mRNA expression profiles of MRPs in the radixin knockdown cells were primarily evaluated by RT-PCR. Real time quantitative RT-PCR and western blot analysis revealed that the radixin deficiency caused the mRNA and protein expression levels of MRP2 to be reduced by about 50%, respectively. Accordingly, efflux and MTT assays showed that the radixin knockdown cells exhibited lower efflux ability with respect to calcein but no significant change in cell viability. In conclusion, among the MRP1–6 family members, radixin selectively modulates the expression and function of MRP2 in a system co-expressing all three ERM proteins.Download high-res image (99KB)Download full-size image