We have isolated a novel liver-specific organic anion transporter, LST-1, that is expressed exclusively in the human, rat, and mouse liver. LST-1 is a new gene family located between the organic anion transporter family and prostaglandin transporter. LST-1 transports taurocholate (K m ‫؍‬ 13.6 M) in a sodium-independent manner. LST-1 also shows broad substrate specificity. It transports conjugated steroids (dehydroepiandrosterone sulfate, estradiol-17␤-glucuronide, and estrone-3-sulfate), eicosanoids (prostaglandin E 2 , thromboxane B 2 , leukotriene C 4 , leukotriene E 4 ), and thyroid hormones (thyroxine, K m ‫؍‬ 3.0 M and triiodothyronine, K m ‫؍‬ 2.7 M), reflecting hepatic multispecificity.LST-1 is probably the most important transporter in human liver for clearance of bile acids and organic anions because hepatic levels of another organic anion transporter, OATP, is very low. This is also the first report of the human molecule that transports thyroid hormones.One of the major function of the liver is the removal of various endogenous and exogenous compounds from the circulation (1, 2). This clearance process involves basolateral membrane transport systems that mediate the hepatocellular uptake of bile acids, organic anions, and organic cations (3, 4). One well studied class of substrates are the bile acids. The uptake of taurocholate is mainly mediated by the Na ϩ /taurocholate cotransporting polypeptide (ntcp) in a Na ϩ -dependent manner (5). The uptake of other bile acids (e.g. cholate) occurs predominantly via a Na ϩ -independent mechanism (2, 4). Some amount of taurocholate is also transported by the Na ϩ -independent mechanism. This Na ϩ -independent carrier system further shows a broad substrate specificity transporting conjugated steroids, cardiac glycosides, and other xenobiotics (4).Initially, the organic anion transporter (oatp) 1 family (oatp1, oatp2, oatp3) was considered to represent the Na ϩ -independent transporting mechanisms in the liver (6 -8). Subsequently, a human cDNA, termed OATP, was isolated (9). However, significant differences were found between human OATP and rat oatp family. First, although the substrate specificities were qualitatively similar, significant differences were found between human OATP-and rat oatp family-mediated initial uptake rates and apparent K m values (10, 11). Second, Northern blot analysis of the human OATP showed considerably high expression in the brain, a pattern that is different from any of the oatp family members. These findings strongly suggest the existence of a different group of organic anion transporters in human liver.Here we report the isolation of a novel human organic anion transporter, termed LST-1, which is expressed exclusively in the liver. When expressed in Xenopus oocytes, many of the functional characteristics of LST-1 were identical to the multispecific transporting mechanisms of human liver. These results suggest that LST-1 is the predominant clearance mechanism of several endogenous and exogenous substrates in human liver. MATERIALS ...

The Kelch-like ECH-associated protein 1 (Keap1)-NF-E2-related factor 2 (Nrf2) system is essential for cytoprotection against oxidative and electrophilic insults. Under unstressed conditions, Keap1 serves as an adaptor for ubiquitin E3 ligase and promotes proteasomal degradation of Nrf2, but Nrf2 is stabilized when Keap1 is inactivated under oxidative/electrophilic stress conditions. Autophagy-deficient mice show aberrant accumulation of p62, a multifunctional scaffold protein, and develop severe liver damage. The p62 accumulation disrupts the Keap1-Nrf2 association and provokes Nrf2 stabilization and accumulation. However, individual contributions of p62 and Nrf2 to the autophagy-deficiency-driven liver pathogenesis have not been clarified. To examine whether Nrf2 caused the liver injury independent of p62, we crossed liver-specific Atg7::Keap1-Alb double-mutant mice into p62-and Nrf2-null backgrounds. Although Atg7::Keap1-Alb:: p62 −/− triple-mutant mice displayed defective autophagy accompanied by the robust accumulation of Nrf2 and severe liver injury, Atg7:: Keap1-Alb::Nrf2 −/− triple-mutant mice did not show any signs of such hepatocellular damage. Importantly, in this study we noticed that Keap1 accumulated in the Atg7-or p62-deficient mouse livers and the Keap1 level did not change by a proteasome inhibitor, indicating that the Keap1 protein is constitutively degraded through the autophagy pathway. This finding is in clear contrast to the Nrf2 degradation through the proteasome pathway. We also found that treatment of cells with tert-butylhydroquinone accelerated the Keap1 degradation. These results thus indicate that Nrf2 accumulation is the dominant cause to provoke the liver damage in the autophagy-deficient mice. The autophagy pathway maintains the integrity of the Keap1-Nrf2 system for the normal liver function by governing the Keap1 turnover.electrophile | polyubiquitination

No abstract

Digoxin, which is one of the most commonly prescribed drugs for the treatment of heart failure, is mainly eliminated from the circulation by the kidney. P-glycoprotein is well characterized as a digoxin pump at the apical membrane of the nephron. However, little is known about the transport mechanism at the basolateral membrane. We have isolated an organic anion transporter (OATP4C1) from human kidney. Human OATP4C1 is the first member of the organic anion transporting polypeptide (OATP) family expressed in human kidney. The isolated cDNA encodes a polypeptide of 724 aa with 12 transmembrane domains. The genomic organization consists of 13 exons located on chromosome 5q21. Its rat counterpart, Oatp4c1, is also isolated from rat kidney. Human OATP4C1 transports cardiac glycosides (digoxin, K m ‫؍‬ 7.8 M and ouabain, K m ‫؍‬ 0.38 M), thyroid hormone (triiodothyronine, Km ‫؍‬ 5.9 M and thyroxine), cAMP, and methotrexate in a sodiumindependent manner. Rat Oatp4c1 also transports digoxin (K m ‫؍‬ 8.0 M) and triiodothyronine (Km ‫؍‬ 1.9 M). Immunohistochemical analysis reveals that rat Oatp4c1 protein is localized at the basolateral membrane of the proximal tubule cell in the kidney. These data suggest that human OATP4C1͞rat Oatp4c1 might be a first step of the transport pathway of digoxin and various compounds into urine in the kidney.

We have encountered cases of unusual intraductal pancreatic neoplasms with predominant tubulopapillary growth. We collected data on 10 similar cases of "intraductal tubulopapillary neoplasms (ITPNs)" and analyzed their clinicopathologic and molecular features. Tumor specimens were obtained from 5 men and 5 women with a mean age of 58 years. ITPNs were solid and nodular tumors obstructing dilated pancreatic ducts and did not contain any visible mucin. The tumor cells formed tubulopapillae and contained little cytoplasmic mucin. The tumors exhibited uniform high-grade atypia. Necrotic foci were frequently observed, and invasion was observed in some cases. The ITPNs were immunohistochemically positive for cytokeratin 7 and/or cytokeratin 19 and negative for trypsin, MUC2, MUC5AC, and fascin. Molecular studies revealed abnormal expressions of TP53 and SMAD4 in 1 case, but aberrant expression of beta-catenin was not observed. No mutations in KRAS and BRAF were observed in the 8 cases that were examined. Eight patients are alive without recurrence, 1 patient died of liver metastases, and 1 patient is alive but had a recurrence and underwent additional pancreatectomy. The mitotic count and Ki-67 labeling index were significantly associated with invasion. All the features of ITPN were distinct from those of other known intraductal pancreatic neoplasms, including pancreatic intraepithelial neoplasia, intraductal papillary mucinous neoplasm, and the intraductal variant of acinar cell carcinoma. Intraductal tubular carcinomas showed several features that were similar to those of ITPN, except for the tubulopapillary growth pattern. In conclusion, ITPNs can be considered to represent a new disease entity encompassing intraductal tubular carcinoma as a morphologic variant.

In this multicentre retrospective analysis, the morphological type of IPMN appears to be an independent predictor of patient prognosis.

189 Background: Despite improvements of postoperative adjuvant therapy for resected pancreatic ductal adenocarcinoma (PDAC), its prognosis remains poor. A randomized controlled trial has begun to compare neoadjuvant chemotherapy using gemcitabine and S1 (NAC-GS) with upfront surgery (Up-S) for patients with PDAC planned resection. Methods: Patients were enrolled after the diagnosis of resectable PDAC with histological confirmation. They were randomly assigned as either NAC-GS or Up-S. In NAC-GS, gemcitabine was provided at a dose of 1 g/m2 on day 1 and 8 and oral S-1 was administered at a dose of 40 mg/m2 twice daily on 1-14 days. Patients received 2 cycles of this regimen. S-1 adjuvant for 6 months was administered for the patients with curative resection and fully recovered within 10 weeks after surgery in both arms. The primary endpoint for the phase III part was overall survival (OS); secondary endpoints included adverse events, resection rate, recurrence-free survival, residual tumor status, nodal metastases, and tumor marker kinetics. The target sample size required 163 patients (α-error 0.05; power 0.8) in each arm. The trial was conducted by the Health Labor Sciences Research Grant (H22-009) of Japan and registered with the UMIN Clinical Trials Registry as UMIN000009634. Results: From January 2013 to January 2016, 364 patients were enrolled in 57 centers (182 to NAC-GS and 182 to Up-S). Of these, two were excluded because of ineligibility, therefore 182 patients in NAC-GS and 180 in Up-S constituted the ITT analysis-set. The median OS was 36.7 months in NAC-GS and 26.6 months in Up-S; HR 0.72 (95% confidential interval 0.55-0.94; p=0.015 [stratified log-rank test]). Grade 3 or 4 adverse events frequently (72.8%) observed in NAC-GS were leukopenia or neutropenia. However, the resection rate, R0 resection rate, and morbidity of the operation were equivalent in the two groups. There was no perioperative mortality in either group. Conclusions: This phase III study demonstrated the significant survival benefits of NAC-GS treatment. Therefore, the results indicated that neoadjuvant chemotherapy could be a new standard for patients with resectable PDAC. Clinical trial information: UMIN000009634.

The survival probability in patients with resected bile duct cancer was not significantly different between the gemcitabine adjuvant chemotherapy group and the observation group. Registration number: UMIN 000000820 (http://www.umin.ac.jp/).