Fluorouracil uptake in triple-negative breast cancer cells: Negligible contribution of equilibrative nucleoside transporters 1 and 2.

Equilibrative nucleoside transporters (ENTs) 1 and 2 reportedly accept fluorouracil as a substrate. Here, we evaluated ENT1/2 expression at the messenger RNA (mRNA), protein, and functional levels in a panel of four triple-negative breast cancer (TNBC) cell lines, BT-549, Hs578T, MDA-MB-231, and MDA-MB-435, and we examined the relationship of the observed profiles to fluorouracil sensitivity. Nitrobenzylthioinosine (NBMPR) at 0.1 µM inhibits only ENT1, while dipyridamole at 10 µM or NBMPR at 100 µM inhibits both ENT1 and ENT2. We found that the uptake of [3 H]uridine, a typical substrate of ENT1 and ENT2, was decreased to approximately 40% by 0.1 µM NBMPR. At 100 µM, NBMPR almost completely blocked the saturable uptake of [3 H]uridine, but this does not imply a functional role of ENT2, because 10 µM dipyridamole showed similar inhibition to 0.1 µM NBMPR. Expression of ENT1 mRNA was almost 1 order of magnitude higher than that of ENT2 in all TNBC cell lines. Liquid chromatography-tandem mass spectrometry(LC-MS/MS) LC-MS/MS-based targeted protein quantification showed that ENT1 protein levels were in the range of 9.3-30 fmol/µg protein in plasma membrane fraction of TNBC cell lines, whereas ENT2 protein was below the detection limit. [3 H]Fluorouracil uptake was insensitive to 0.1 µM NBMPR and 10 µM dipyridamole, suggesting a negligible contribution of ENT1 and ENT2 to fluorouracil uptake. The levels of ENT1 mRNA, ENT1 protein, ENT2 mRNA, and ENT1-mediated [3 H]uridine uptake in the four TNBC cell lines showed no correlation with fluorouracil sensitivity. These results indicate that neither ENT1 nor ENT2 contributes significantly to the fluorouracil sensitivity of TNBC cell lines.

[Early Prediction of Support Necessity for Pharmacy Clinical Internship Using Deep Learning].

The duration of undergraduate study was extended in 2006 to six years for pharmaceutical education aimed at training highly qualified pharmacists. Clinical internship in current pharmaceutical education is positioned as being important for fostering the qualities required of a pharmacist, and the support of faculty members is essential. Based on the above, we thought that support from faculty members should be provided easily and positively, which would enrich community pharmacy clinical internships. This study aimed to examine the method of predicting the need for support from weekly reports of community pharmacy practice trainees at Showa Pharmaceutical University. It became evident that the level of necessary support could not be predicted by using the support needs listed. However, application of deep learning to the contents of the weekly report for the first to fifth weeks in 2019 enabled the prediction of the level of support needed in 2020 with 97% accuracy. Although this research is currently limited to predicting the level of support required for community pharmacy practical internship at our university, it demonstrates the use of deep learning to predict the level of support needed based on five weeks' worth of weekly reports.

Proton-coupled erythromycin antiport at rat blood-placenta barrier.

The aim of the present study was to characterize the mechanism of erythromycin transport at the blood-placenta barrier, using TR-TBT 18d-1 cells as a model of rat syncytiotrophoblasts. [(14)C]Erythromycin was taken up by TR-TBT 18d-1 cells with a Michaelis constant of 466 microM. Although the uptake was not dependent on extracellular Na(+) or Cl(-), it was increased at weakly alkaline pH. Significant overshoot of [(14)C]erythromycin uptake by placental brush-border membrane vesicles was observed in the presence of an outwardly directed proton gradient. These results indicate that erythromycin is transferred by the H(+)-coupled transport system in syncytiotrophoblasts. To address the physiological transport of erythromycin in rat placenta, fetal-to-maternal transport clearance was estimated by means of the single placental perfusion technique. Clearance of [(14)C]erythromycin was higher than that of [(14)C]inulin, a paracellular pathway marker, and was decreased by the addition of 5 mM erythromycin, indicating that saturable efflux system from fetus to mother is involved. The effect of various transporter inhibitors on [(14)C]erythromycin efflux from TR-TBT 18d-1 cells was evaluated. cyclosporin A, fumitremorgin C, and probenecid had no effect, whereas ethylisopropylamiloride, a specific inhibitor of Na(+)/H(+) exchangers (NHEs), was significantly inhibitory. These results suggest that erythromycin efflux transport at the rat blood-placenta barrier is mediated by an erythromycin/H(+) antiport system, driven by H(+) supplied by NHEs.

Prexasertib increases the sensitivity of pancreatic cancer cells to gemcitabine and S­1.

Our previous study demonstrated that gemcitabine (GEM), S­1, and a combination of GEM and S­1 (GS) induced S­phase arrest and increased the phosphorylation of checkpoint kinase 1 (Chk1), which is a critical mediator of cell survival under impaired DNA replication, in pancreatic cancer cell lines. The aim of the present study was to investigate the combined effect of the Chk1 inhibitor prexasertib and antitumor drugs (GEM and S­1) on pancreatic cancer cell line SUIT­2. Furthermore, we conducted mechanistic analysis of the combined effect. The MTT assay revealed that a combination of prexasertib and GS showed a strong effect. Mechanistic analysis of the combined effect showed effective induction of apoptosis. Furthermore, a combination of prexasertib and GS downregulated the expression of antiapoptotic protein Bcl­2. Chk1 knockdown with small interfering RNA and GS treatment resulted in strong induction of apoptosis. Our results provide evidence to show that the combination of prexasertib and GS has a strong antitumor effect and effectively induces apoptosis in pancreatic cancer cells through downregulation of the antiapoptotic protein Bcl­2. Prexasertib could possibly enhance the effects of standard drugs, including GEM, S­1, and GS, against pancreatic cancer.

Quantification of ENT1 and ENT2 Proteins at the Placental Barrier and Contribution of These Transporters to Ribavirin Uptake.

The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [3H]ribavirin in rats was much higher than that of [14C]sucrose. The uptake of [3H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 µM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 µM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 µM dipyridamole on [3H]ribavirin uptake was not much different from that by 0.1 µM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [3H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [3H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.

Contribution of equilibrative nucleoside transporter (ENT) 2 to fluorouracil transport in rat placental trophoblast cells.

Fluorouracil is used for treatment of breast cancer even in pregnant women, except during fetal organogenesis. The purpose of this study was to clarify the transport mechanism of fluorouracil at the rat placental barrier. Maternal-to-fetal transfer of [3H]fluorouracil in rats at gestational day 19.5 was saturable and much higher than that of [14C]sucrose. The uptake of [3H]fluorouracil was also saturable in rat placental trophoblast TR-TBT 18d-1 cells, which express both equilibrative nucleoside transporter (ENT) 1 and ENT2. Nitrobenzylthioinosine (NBMPR) at 0.1 µM had no effect on [3H]fluorouracil uptake by TR-TBT 18d-1 cells, but 100 µM NBMPR almost completely inhibited the saturable component, suggesting involvement of ENT2, rather than ENT1 in the transport. Rat ENT2 cRNA-injected oocytes showed significantly increased [3H]fluorouracil uptake compared with water-injected oocytes, while rat ENT1 cRNA-injected oocytes did not show an increase of [3H]fluorouracil uptake. The Michaelis-Menten constant for rat ENT2-mediated uptake of [3H]fluorouracil was 4.21 mM. The expression profile of ENT2 mRNA in rat placenta during pregnancy was almost constant from 13.5 to 21.5 days of gestation. In conclusion, ENT2 appears to be the mediator of fluorouracil transport in rat placental trophoblast cells.

[Development of a New Scholastic Program for Medication Counseling Practice in Preclinical Training, Constructed for Junior Students by Senior Students Based on Their Experiences of On-site Practice].

Long-term practical on-site training, based on the Model Core Curriculum for Pharmaceutical Education, is a core program of the 6-year course of pharmaceutical education, introduced in Japan in 2010. In particular, medication counseling in practical training in 5th-year provides valuable opportunities for communication with real patients rather than simulated patients (SPs). However, it can also cause anxiety in 4th-year students before practical training. To address such concerns, upperclassmen (5th- and 6th-year students), who have already completed practical training, constructed and conducted a new educational program for medication counseling practice in preclinical training based on their experiences. They also developed case scenarios and played the role of patients themselves to create more realistic clinical settings. Advice from professional SPs was also provided. The 5-step program is composed of 1st counseling, 1st small group discussion (SGD) for improving counseling, 2nd revised counseling based on the 1st SGD, 2nd SGD, and development of a counseling plan and presentation. Educational effects of the program were evaluated by questionnaire survey after preclinical training in 4th-year students and after their practical training in 5th-year students. This new program, the Advanced Medication Counseling Practice, was found to be useful to reduce anxiety about communication with patients among 4th-year students (about 90%). Even after their practical training in 5th-year, they still appreciated usefulness of this program (about 80%). This program is still valued 4 years after its development. We developed the Advanced Medication Counseling Practice in preclinical training for junior students by senior students.

Hepatocyte growth factor suppresses the anticancer effect of irinotecan by decreasing the level of active metabolite in HepG2 cells.

In the liver, carboxylesterase (CES) converts irinotecan (CPT-11) to its active metabolite SN-38, which exerts anticancer effects. SN-38 is metabolized to an inactive metabolite SN-38 glucuronide by uridine 5'-diphospho-glucuronosyltransferase 1A1 (UGT1A1). Therefore, single nucleotide polymorphisms (SNPs) of the UGT1A1 gene are responsible for the severe adverse effects associated with the disruption of SN-38 metabolism. However, despite having SNPs of the UGT1A1 gene, many patients metabolize SN-38 sufficiently to avoid severe adverse effects. Among these patients, we found individuals with elevated serum concentrations of hepatocyte growth factor (HGF). The aim of this study was to evaluate whether HGF alters the metabolism of CPT-11, resulting in a reduction in the anticancer effect of CPT11. The cytotoxicity of CPT-11 and SN-38 was evaluated in HepG2 cells pretreated with HGF. Furthermore, we explored the level of expression and mechanisms of activity of CES and UGT1A1. HGF suppressed the cytotoxicity of CPT-11 by decreasing intracellular SN-38 levels that resulted from a decrease in CES2 and an increase in UGT1A1. Furthermore, this HGF-induced suppression was improved by pretreatment with an inhibitor of HGF receptor c-Met, and the improvement was synergistically potentiated by epidermal growth factor receptor (EGFR) inhibitors. Moreover, HGF induced phosphorylation of signal transducer and activator of transcription 3 and transactivated EGFR. These results suggest that HGF is a possible causative agent of acquired clinical resistance in chemotherapy with CPT-11 and could be useful as a predictor of clinical resistance. Additional treatment using c-Met and/or EGFR inhibitors could be a novel strategy to overcome resistance.