Differential contributions of G protein- or arrestin subtype-mediated signalling underlie urocortin 3-induced somatostatin secretion in pancreatic δ cells.

BACKGROUND AND PURPOSE: Pancreatic islets are modulated by cross-talk among different cell types and paracrine signalling plays important roles in maintaining glucose homeostasis. Urocortin 3 (UCN3) secreted by pancreatic ß cells activates the CRF2 receptor (CRF2R) and downstream pathways mediated by different G protein or arrestin subtypes in δ cells to cause somatostatin (SST) secretion, and constitutes an important feedback circuit for glucose homeostasis. EXPERIMENTAL APPROACH: Here, we used Arrb1-/-, Arrb2-/-, Gsfl/fl and Gqfl/fl knockout mice, the G11-shRNA-GFPfl/fl lentivirus, as well as functional assays and pharmacological characterization to study how the coupling of Gs, G11 and ß-arrestin1 to CRF2R contributed to UCN3-induced SST secretion in pancreatic δ cells. KEY RESULTS: Our study showed that CRF2R coupled to a panel of G protein and arrestin subtypes in response to UCN3 engagement. While RyR3 phosphorylation by PKA at the S156, S2706 and S4697 sites may underlie the Gs-mediated UCN3- CRF2R axis for SST secretion, the interaction of SYT1 with ß-arrestin1 is also essential for efficient SST secretion downstream of CRF2R. The specific expression of the transcription factor Stat6 may contribute to G11 expression in pancreatic δ cells. Furthermore, we found that different UCN3 concentrations may have distinct effects on glucose homeostasis, and these effects may depend on different CRF2R downstream effectors. CONCLUSIONS AND IMPLICATIONS: Collectively, our results provide a landscape view of signalling mediated by different G protein or arrestin subtypes downstream of paracrine UCN3- CRF2R signalling in pancreatic ß-δ-cell circuits, which may facilitate the understanding of fine-tuned glucose homeostasis networks.

Laparoscopic Double Hepatic Artery Banding/Ligation for Patients With Hepatic Hereditary Haemorrhagic Telangiectasia (HHHT).

Introduction: Hepatic hereditary haemorrhagic telangiectasia (HHHT) is a rare autosomal dominant genetic disease. Some patients may develop cardiac failure, portal hypertension, and biliary ischaemia. To date, there is no standard surgical treatment for HHHT. The present authors propose a move from open to laparoscopic surgery; however, laparoscopic surgery has not been reported previously as a surgical treatment for HHHT. Report: Two women were admitted with histories of exertional dyspnoea and upper abdominal pain, respectively. Combined with recurrent epistaxis and their positive family history, a diagnosis of clinical HHHT was made based on Curacao criteria after comprehensive evaluation of imaging features. Next generation sequencing (NGS) results also confirmed typical gene mutations responsible for HHT. Both patients underwent laparoscopic double hepatic artery banding and or ligation successfully and were discharged four to six days after operation without severe complications. The symptoms of cardiac insufficiency including exertional dyspnoea and shortness of breath of the first patient improved six months after the operation. The second patient, with epigastric pain, remained pain free without medication three months after the operation. Discussion: Laparoscopic surgery for HHHT is technically challenging. Clinical data and follow up information showed that laparoscopic double hepatic artery banding and or ligation was a technically feasible surgical approach for HHHT patients with simple hepatic artery dilation.

Structure of GPR101-Gs enables identification of ligands with rejuvenating potential.

GPR101 is an orphan G protein-coupled receptor actively participating in energy homeostasis. Here we report the cryo-electron microscopy structure of GPR101 constitutively coupled to Gs heterotrimer, which reveals unique features of GPR101, including the interaction of extracellular loop 2 within the 7TM bundle, a hydrophobic chain packing-mediated activation mechanism and the structural basis of disease-related mutants. Importantly, a side pocket is identified in GPR101 that facilitates in silico screening to identify four small-molecule agonists, including AA-14. The structure of AA-14-GPR101-Gs provides direct evidence of the AA-14 binding at the side pocket. Functionally, AA-14 partially restores the functions of GH/IGF-1 axis and exhibits several rejuvenating effects in wild-type mice, which are abrogated in Gpr101-deficient mice. In summary, we provide a structural basis for the constitutive activity of GPR101. The structure-facilitated identification of GPR101 agonists and functional analysis suggest that targeting this orphan receptor has rejuvenating potential.

NDRG1 facilitates self-renewal of liver cancer stem cells by preventing EpCAM ubiquitination.

BACKGROUND: Portal vein tumour thrombus (PVTT) is the main pathway of HCC intrahepatic metastasis and is responsible for the poor prognosis of patients with HCC. However, the molecular mechanisms underlying PVTT vascular metastases have not been fully elucidated. METHODS: NDRG1 expression was assessed by immunohistochemistry and immunoblotting in clinical specimens obtained from curative surgery. The functional relevance of NDRG1 was evaluated using sphere formation and animal models of tumorigenicity and metastasis. The relationship between NDRG1 and EpCAM was explored using molecular biological techniques. RESULTS: NDRG1 protein was upregulated in HCC samples compared to non-tumorous tissues. Furthermore, NDRG1 expression was enhanced in the PVTT samples. Our functional study showed that NDRG1 was required for the self-renewal of tumour-initiating/cancer stem cells (CSCs). In addition, NDRG1 knockdown inhibited the proliferation and migration of PVTT-1 cells in vitro and in vivo. NDRG1 was found to stabilise the functional tumour-initiating cell marker EpCAM through protein-protein interactions and inhibition of EpCAM ubiquitination. CONCLUSION: Our findings suggest that NDRG1 enhances CSCs expansion, PVTT formation and growth capability through the regulation of EpCAM stability. NDRG1 may be a promising target for the treatment of patients with HCC and PVTT.

In situ subtotal spleen resection combined with selective pericardial devascularization for the treatment of portal hypertension.

BACKGROUND: Hypersplenism and esophageal varices bleeding are the major complications of portal hypertension (PHT). In recent years, increasing attention has been given to spleen preservation operations. The mode and long-term effects of subtotal splenectomy and selective pericardial devascularization for PHT remain controversial. AIM: To investigate the clinical efficacy and safety of subtotal splenectomy combined with selective pericardial devascularization for the treatment of PHT. METHODS: This was a retrospective study of 15 patients with PHT who underwent subtotal splenectomy not preserving the splenic artery or vein combined with selective pericardial devascularization in the Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University from February 2011 to April 2022. Fifteen propensity score-matched patients with PHT who underwent total splenectomy at the same time served as the control group. The patients were followed for up to 11 years after surgery. We compared the postoperative platelet levels, perioperative splenic vein thrombosis, and serum immunoglobulin levels between the two groups. Abdominal enhanced computed tomography was used to evaluate the blood supply and function of the residual spleen. The operation time, intraoperative blood loss, evacuation time, and hospital stay were compared between the two groups. RESULTS: The postoperative platelet level of patients in the subtotal splenectomy group was significantly lower than that in the total splenectomy group (P < 0.05), and the postoperative portal system thrombosis rate in the subtotal splenectomy group was also much lower than that in the total splenectomy group. The levels of serum immunoglobulins (IgG, IgA, and IgM) showed no significant differences after surgery compared with before surgery in the subtotal splenectomy group (P > 0.05), but serum immunoglobulin IgG and IgM levels decreased dramatically after total splenectomy (P < 0.05). The operation time in the subtotal splenectomy group was longer than that in the total splenectomy group (P < 0.05), but there were no significant differences in the amount of intraoperative blood loss, evacuation time, or hospital stay between the two groups. CONCLUSION: Subtotal splenectomy not preserving the splenic artery or vein combined with selective pericardial devascularization is a safe and effective surgical treatment for patients with PHT, not only correcting hypersplenism but also preserving splenic function, especially immunological function.

Autonomous sensing of the insulin peptide by an olfactory G protein-coupled receptor modulates glucose metabolism.

Along with functionally intact insulin, diabetes-associated insulin peptides are secreted by ß cells. By screening the expression and functional characterization of olfactory receptors (ORs) in pancreatic islets, we identified Olfr109 as the receptor that detects insulin peptides. The engagement of one insulin peptide, insB:9-23, with Olfr109 diminished insulin secretion through Gi-cAMP signaling and promoted islet-resident macrophage proliferation through a ß cell-macrophage circuit and a ß-arrestin-1-mediated CCL2 pathway, as evidenced by ß-arrestin-1-/- mouse models. Systemic Olfr109 deficiency or deficiency induced by Pdx1-Cre+/-Olfr109fl/fl specifically alleviated intra-islet inflammatory responses and improved glucose homeostasis in Akita- and high-fat diet (HFD)-fed mice. We further determined the binding mode between insB:9-23 and Olfr109. A pepducin-based Olfr109 antagonist improved glucose homeostasis in diabetic and obese mouse models. Collectively, we found that pancreatic ß cells use Olfr109 to autonomously detect self-secreted insulin peptides, and this detection arrests insulin secretion and crosstalks with macrophages to increase intra-islet inflammation.

Long Noncoding RNA SNHG1 Regulates LMNB2 Expression by Sponging miR-326 and Promotes Cancer Growth in Hepatocellular Carcinoma.

OBJECTIVE: The purpose of the study is to explore the potential competing endogenous RNA (ceRNA) network and investigate the molecular mechanism of long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) in hepatocellular carcinoma (HCC) development. METHODS: By analyzing the data of HCC in The Cancer Genome Atlas (TCGA) database, we included differentially expressed lncRNA and microRNA (miRNA) profiles and constructed ceRNA networks related to the prognosis of HCC patients. qRT-PCR, Western blotting, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), transwell assay, and the nude mouse model were employed to test the effects of SNHG1 and LMNB2 on tumor proliferation and growth in vitro and in vivo. RESULTS: In the study, we identified 115 messenger RNAs (mRNAs), 12 lncRNAs, and 37 miRNAs by intersecting differentially expressed genes (DEGs) in TCGA and StarBase databases. Then, SNHG1-miR-326-LMNB2 pathway came into notice after further survival analysis and hub gene screening. Our results showed that SNHG1 expression was upregulated significantly in HCC tissues and cell lines. Downregulation of both LMNB2, the target of miR-326 in HCC, and SNHG1 inhibited tumor proliferation and growth in vitro and in vivo. Furthermore, SNHG1 could regulate LMNB2 expression through binding to miR-326 in HCC cell lines. CONCLUSION: SNHG1 is a promising prognostic factor in HCC, and the SNHG1-miR-326-LMNB2 axis may be a potential therapeutic target for HCC.

Case Report: Incidentally Discovered a Rare Cystic Lesion of Liver: Multicystic Biliary Hamartoma.

Multicystic biliary hamartoma (MCBH) is an extremely rare cystic lesion of the liver. A 37-year old male patient was admitted to our hospital for incidentally discovered hepatic cystic lesions on abdominal ultrasonography. Abdominal contrast-enhanced computed tomography (CT) showed a multilocular cystic lesion in the segment VI, with mild enhancement in the septae and peripheral wall within the lesion. Only alanine transaminase (ALT) and carbohydrate antigen 19-9 (CA19-9) increased slightly above normal value. Preoperative tests suggested possibility of a benign mucinous cystic neoplasm (MCN) or intraductal papillary neoplasm of the bile duct (IPNB). Laparoscopic complete resection of the lesion was performed. Histopathological examination showed numerous variably sized ductal structures surrounded by periductal glands and fibrous connective tissues containing small blood vessels and smooth muscle bundles. Immunohistochemical staining (IHC) revealed that dilated ducts were positive for cytokeratin CK19, characteristic for biliary tract. Histopathological findings confirmed diagnosis of multicystic biliary hamartoma (MCBH). No recurrence occurred during 6 months follow-up. In conclusion, MCBH should be differentiating from hepatic cystic lesion and could be resected laparoscopically safely.

Long non­coding RNA ZEB1­AS1 predicts a poor prognosis and promotes cancer progression through the miR­200a/ZEB1 signaling pathway in intrahepatic cholangiocarcinoma.

Emerging evidence suggests that long non­coding RNAs (lncRNAs) play pivotal roles in cancer progression, including in intrahepatic cholangiocarcinoma (IHCC). The overexpression of lncRNA ZEB1 antisense 1 (ZEB1­AS1) has been discovered in several types of cancer; however, the clinical significance and functional role of ZEB1­AS1 in IHCC have not yet been determined. In the present study, ZEB1­AS1 was found to be upregulated in IHCC cell lines and tissues. A high ZEB1­AS1 expression was associated with clinical progression and a poor survival of patients with IHCC, and was identified as an independent risk factor for a poor prognosis. In addition, ZEB1­AS1 promoted the proliferation and metastasis of IHCC cells both in vitro and in vivo. ZEB1­AS1 was demonstrated to increase the expression of ZEB1 by sponging miR­200a and to thereby accelerate epithelial­mesenchymal transition (EMT). On the whole, the findings of the present study demonstrate that ZEB1­AS1 promotes proliferation and metastasis in IHCC, and induces EMT through the miR­200a/ZEB1 signaling pathway. ZEB1­AS1 may thus be a promising prognostic biomarker and essential therapeutic target for IHCC.

HMGB1 correlates with angiogenesis and poor prognosis of perihilar cholangiocarcinoma via elevating VEGFR2 of vessel endothelium.

Perihilar cholangiocarcinoma (PHCCA) is the most common type of cholangiocarcinoma with low resection rate and high morbidity. The study of PHCCA biomarkers made progresses slowly compared with intrahepatic cholangiocarcinoma because of surgical complexity and low possibility of radical surgery, which resulted in the difficulty of specimen obtainment. To screen and identify new biomarkers in PHCCA, we constructed a retrospective cohort with 121 PHCCA patients and a prospective cohort consisting of 64 PHCCA patients, and screened the candidate biomarkers by immunohistochemistry and quantified PCR. In our study, expression of high mobility group box 1 (HMGB1) was demonstrated to be significantly associated with microvascular density (MVD) and unfavorable prognosis of PHCCA in both retrospective and prospective study. Moreover, HMGB1 concentrations in bile and serum of PHCCA patients and healthy controls were detected and compared. Postoperative serum HMGB1 and reflux cholangitis indicated recurrence and unfavorable prognosis of PHCCA. With experiments in vitro and in vivo, we demonstrated that intracellular HMGB1 could be released from PHCCA cells and induce invasion and angiogenesis with LPS stimulation. VEGFR2 expression in vessel endothelial cells was upregulated by the released HMGB1 from PHCCA, resulting in the ectopic angiogenesis. In conclusion, intracellular HMGB1 could be released from PHCCA cells and promote angiogenesis via elevating VEGFR2 in vessel endothelial cells. High expression of HMGB1 was associated with MVD and poor prognosis in clinical analyzation. Postoperative serum HMGB1 and cholangitis could predict high recurrence and unfavorable prognosis.

SHMT2 Overexpression Predicts Poor Prognosis in Intrahepatic Cholangiocarcinoma.

BACKGROUND AND OBJECTIVE: Serine hydroxymethyltransferase 2 (SHMT2) functions as a key enzyme in serine/glycine biosynthesis and one-carbon metabolism. Recent studies have shown that SHMT2 participated in tumor growth and progression in a variety of cancer types. The objective of the present study is to explore the expression of SHMT2 and evaluate its prognostic value in patients with intrahepatic cholangiocarcinoma (iCCA). PATIENTS AND METHODS: We retrospectively investigated the expression of SHMT2 in 100 primary iCCA samples through immunohistochemical (IHC) staining on a tissue array. RESULTS: High SHMT2 expression was found in 52 of the 100 specimens. The results indicated that SHMT2 level was upregulated compared to adjacent nontumor intrahepatic bile duct tissue. Furthermore, SHMT2 level was closely associated with tumor T stage (P = 0.017) and tumor TNM stage (P = 0.041) in patients with iCCA, but not with age, gender, tumor size, tumor number, pathological grade, vascular invasion, or N stage. Moreover, Kaplan-Meier analysis suggested that patients with lower SHMT2 level have longer survival rate than those with high expression (45.8 vs 23.1%, P = 0.030). Additionally, the multivariate analysis model indicated SHMT2 is an independent adverse prognosticator in iCCA. CONCLUSION: High SHMT2 level was correlated with poorer overall survival in patients with iCCA. SHMT2 was proved to be a powerful and independent prognostic factor and a potential therapeutic target for patients with iCCA.

Sprouty2 suppresses progression and correlates to favourable prognosis of intrahepatic cholangiocarcinoma via antagonizing FGFR2 signalling.

Fibroblast growth factor receptor 2 (FGFR2) was demonstrated to correlate to the progression and prognosis of intrahepatic cholangiocarcinoma (ICC) by numerous evidences. However, as a well-recognized suppressor of FGFR2 signalling, the clinical significance of Sprouty (SPRY) family of ICC has not been investigated. In our study, the expressions of SPRY1-4 in 20 pairs of fresh tumour tissues were detected with qPCR, and in 108 cases of paraffin-embedded tissues with immunohistochemistry. The prognostic value of SPRY family in ICC was estimated with univariate analysis and multivariate analysis. As a result, SPRY2 was identified as an independent prognostic biomarker predicting favourable prognosis of ICC. High SPRY2 expression was correlated with good differentiation of ICC. With silencing SPRY2 expression, we demonstrated that SPRY2 could suppress FGFR2-induced ERK phosphorylation, migration, invasion and epithelial-mesenchymal transition (EMT) under FGF1 stimulation. By overexpressing SPRY2-wide type or SPRY2-Y55F, the tyrosine-55 of SPRY2 was demonstrated to be essential in suppressing ERK phosphorylation, tumour invasion and EMT of ICC cells. In conclusion, SPRY2 was correlated with favourable prognosis of ICC via suppressing FGFR2-induced ERK phosphorylation, invasion and EMT. The phosphorylation of SPRY2-Y55 was required in this tumour-suppressing function of SPRY2.

Ablation of somatostatin cells leads to impaired pancreatic islet function and neonatal death in rodents.

The somatostatin (SST)-secreting cells were mainly distributed in the pancreatic islets, brain, stomach and intestine in mammals and have many physiological functions. In particular, the SST-secreting δ cell is the third most common cell type in the islets of Langerhans. Recent studies have suggested that dysregulation of paracrine interaction between the pancreatic δ cells and ß cells results in impaired glucose homeostasis and contributes to diabetes development. However, direct evidence of the functional importance of SST cells in glucose homeostasis control is still lacking. In the present study, we specifically ablated SST-secreting cells by crossing Sst-cre transgenic mice with R26 DTA mice (Sst Cre R26 DTA ). The Sst Cre R26 DTA mice exhibited neonatal death. The life spans of these mice with severe hypoglycemia were extended by glucose supplementation. Moreover, we observed that SST cells deficiency led to increased insulin content and excessive insulin release, which might contribute to the observed hypoglycemia. Unexpectedly, although SST is critical for the regulation of insulin content, factors other than SST that are produced by pancreatic δ cells via their endogenous corticotropin-releasing hormone receptor 2 (CRHR2) activity play the main roles in maintaining normal insulin release, as well as neonatal glucose homeostasis in the resting state. Taken together, our results identified that the SST cells in neonatal mouse played critical role in control of insulin release and normal islet function. Moreover, we provided direct in vivo evidence of the functional importance of the SST cells, which are essential for neonatal survival and the maintenance of glucose homeostasis.

Serine/arginine rich splicing factor 2 expression and clinic pathological features indicating a prognostic factor in human hepatocellular carcinoma patients.

BACKGROUND: This research was aimed to study the expression of Serine/arginine rich splicing factor 2 (SRSF2) in tissues of hepatocellular carcinoma, and explore the relationship between the expression and the clinic pathological and prognosis of human hepatocellular carcinoma (HCC). METHODS: One hundred and fifty-three pairs HCC tissues and adjacent normal tissue were collected from January 2010 to March 2013. The expression of SRSF2 gene was detected by immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction (PCR), and the relationship between the expression and the clinic pathological and prognosis of HCC being analyzed. RESULTS: In 153 cases of hepatocellular carcinoma, SRSF2 was highly expressed in 93 cases, low expression of 60 cases, immunohistochemistry score (6.50 ± 2.82), which was significantly higher than that in adjacent normal tissues (2.94 ± 1.23) (P< 0.05). The expression of SRSF2 in HCC was not associated with gender (χ2= 0.014, P= 0.906), age (χ2= 0.007, P= 0.931), tumor size (χ2= 3.566, P= 0.059) and T stage (χ2= 2.708, P= 0.100), and was significantly correlated with tumor differentiation (χ2= 9.687, P= 0.007), lymph node metastasis (χ2= 4.827, P= 0.028), distal metastasis (χ2= 9.235, P= 0.002), tumor, node, metastasis (TNM) stage (χ2= 3.978, P= 0.046), portal vein invasion and serum alpha-fetoprotein (χ2= 14.919, P= 0.000). The expression of SRSF2 protein in hepatocellular carcinoma was positively correlated (r = 0.704, P< 0.05) with serum alpha-fetoprotein through Pearson analysis. The survival rates of SRSF2 overexpressing hepatocellular carcinoma were 74.19%, 44.09%, 26.88%, 24.73% and 21.51% at 1 year, 2 years, 3 years, 4 years and 5 years respectively, which were lower than those of SRSF2 low expression group (93.33%, 71.67%, 56.67%, 51.67% and 50.00%). CONCLUSION: SRSF2 is highly expressed in hepatocellular carcinoma and its expression increases with the degree of tumor differentiation and TNM staging. It is related to lymph node metastasis and metastasis of tumor cells, and is positively related to serum alpha fetoprotein content, and affects the postoperative survival time of HCC patients.

Switching of the substrate specificity of protein tyrosine phosphatase N12 by cyclin-dependent kinase 2 phosphorylation orchestrating 2 oncogenic pathways.

The protein tyrosine phosphatase nonreceptor type 12 (PTPN12) is a multifunctional protein and has elicited much research attention because its decreased protein level has been associated with poor prognosis of several types of cancers. Recently, we have solved the crystal structure of the phosphatase domain of PTPN12, which disclosed a specific PTPN12-insert-loop harboring a cyclin-dependent kinase 2 (CDK2) phosphorylation site. However, the functional significance of this phosphorylation is undefined. In the present study, we found that S19 site phosphorylation of PTPN12 by CDK2 discharged its antitumor activity by down-regulation of its inhibitory role in cell migration, but not affecting its other regulatory functions. Phosphorylation of PTPN12 at the S19 site changed its substrate interface, and by doing so, selectively decreased its activity toward the human epidermal growth factor receptor 2 (HER2)- pY1196 site, but not other HER2 phosphorylation sites or other known PTPN12 substrates. A further in-depth mechanism study revealed that the phosphorylation of PTPN12 by CDK2 impaired recruitment of the serine/threonine-protein kinase 1 (PAK1) to HER2, resulted in the blockade of the HER2-pY1196-PAK1-T423 signaling pathway, thus increased tumor cell motility. Taken together, our results identified a new phosphorylation-based substrate recognition mechanism of PTPN12 by CDK2, which orchestrated signaling crosstalk between the oncogenic CDK2 and HER2 pathways. The newly identified governing mechanism of the substrate selectivity of a particular phosphatase was previously unappreciated and exemplifies how a phospho-network is precisely controlled in different cellular contexts.-Li, H., Yang, D., Ning, S., Xu, Y., Yang, F., Yin, R., Feng, T., Han, S., Guo, L., Zhang, P., Qu, W., Guo, R., Song, C., Xiao, P., Zhou, C., Xu, Z., Sun, J.-P., Yu, X. Switching of the substrate specificity of protein tyrosine phosphatase N12 by cyclin-dependent kinase 2 phosphorylation orchestrating 2 oncogenic pathways.

A cullin 4B-RING E3 ligase complex fine-tunes pancreatic δ cell paracrine interactions.

Somatostatin secreted by pancreatic δ cells mediates important paracrine interactions in Langerhans islets, including maintenance of glucose metabolism through the control of reciprocal insulin and glucagon secretion. Disruption of this circuit contributes to the development of diabetes. However, the precise mechanisms that control somatostatin secretion from islets remain elusive. Here, we found that a super-complex comprising the cullin 4B-RING E3 ligase (CRL4B) and polycomb repressive complex 2 (PRC2) epigenetically regulates somatostatin secretion in islets. Constitutive ablation of CUL4B, the core component of the CRL4B-PRC2 complex, in δ cells impaired glucose tolerance and decreased insulin secretion through enhanced somatostatin release. Moreover, mechanistic studies showed that the CRL4B-PRC2 complex, under the control of the δ cell-specific transcription factor hematopoietically expressed homeobox (HHEX), determines the levels of intracellular calcium and cAMP through histone posttranslational modifications, thereby altering expression of the Cav1.2 calcium channel and adenylyl cyclase 6 (AC6) and modulating somatostatin secretion. In response to high glucose levels or urocortin 3 (UCN3) stimulation, increased expression of cullin 4B (CUL4B) and the PRC2 subunit histone-lysine N-methyltransferase EZH2 and reciprocal decreases in Cav1.2 and AC6 expression were found to regulate somatostatin secretion. Our results reveal an epigenetic regulatory mechanism of δ cell paracrine interactions in which CRL4B-PRC2 complexes, Cav1.2, and AC6 expression fine-tune somatostatin secretion and facilitate glucose homeostasis in pancreatic islets.

Prognostic significance of TBL1XR1 in predicting liver metastasis for early stage colorectal cancer.

BACKGROUND: Liver metastasis is the leading cause of lethal colorectal cancer (CRC). For patients with early stage CRC, metachronous liver metastasis is the primary risk for poor prognosis. Accordingly, identification of prospective biomarkers for metachronous liver metastasis would be invaluable in evaluating patients' clinical outcomes and developing personal treatment therapy. METHODS: Here we investigated the role of transducin (ß)-like 1 X-linked receptor 1 (TBL1XR1) in predicting liver metastasis for early stage CRC. To accomplish this goal, a multi-center retrospective study was performed which included three stages: exploration stage (43 patients), identification stage (162 patients) and validation stage (38 patients). TBL1XR1 expression was evaluated using immunohistochemical staining and RT-qPCR. The prognostic significance of TBL1XR1 in both stage IV CRC patients and early stage CRC patients were evaluated by Kaplan-Meier survival analysis and multivariate analysis, respectively. RESULTS: For stage IV CRC patients, TBL1XR1 expression was correlated with the number of liver metastases (P = 0.036), and high levels of TBL1XR1 in liver metastases indicated poor overall survival (P = 0.028). Moreover, high expressions of TBL1XR1 can serve as a predictor for liver metastasis in early stage CRC patients (P = 0.003). CONCLUSIONS: TBL1XR1 is a promising biomarker for predicting liver metastasis in early stage CRC patients.

Correlations between TBL1XR1 and recurrence of colorectal cancer.

More than 25% localized CRC patients died from post-operative metastasis, and risk of metastasis varies among individuals due to the high heterogeneity of CRC. Therefore, figuring out potential biomarkers for disease recurrence would be invaluable to improve the follow-up efficiency and clinical treatment. Transducin (ß)-like 1 X-linked receptor 1 (TBL1XR1) is a core component of the nuclear receptor corepressor complex, which functions as a repressive coregulatory factor for multiple transcription factors. The clinical significance of TBL1XR1 in CRC hasn't been fully elucidated. In this study, we investigated the expression of TBL1XR1 in primary CRC tissues and liver metastases from TNM stage IV CRC patients, and found that its expression in primary tumor tissues was an independent prognostic factor for tumor recurrence. Thus, we enrolled another cohort including TNM stage I-III patients to further evaluate the relationship between TBL1XR1 expression and disease recurrence. Accordingly, high TBL1XR1 expression indicates poor disease-free survival of stage I-III CRC patients. Furthermore, we confirmed the importance of ß-catenin signaling pathways in TBL1XR1-mediated CRC cell oncogenicity by clinical and cellular results. Our results emphasize the necessity of individual therapy decisions based on clinical biomarkers, especially for localized CRC patients who are not routinely treated with adjunctive chemotherapy.

TBL1XR1 predicts isolated tumor cells and micrometastasis in patients with TNM stage I/II colorectal cancer.

BACKGROUND AND AIM: A considerable number of early-stage colorectal cancer (CRC) patients may develop cancer relapse or metastasis after curative surgery. Isolated tumor cells (ITC) and micrometastasis in lymph nodes (LNMM), which are undetectable by conventional pathological examination, may be one primary reason. Detection of ITC/LNMM is time-consuming and cost-ineffective; we aimed to find biomarkers in primary CRC tissues to help predicting ITC/LNMM status. METHODS: We enrolled 137 node-negative patients with early-stage CRC in this study. Existence of ITC/LNMM was identified by immunohistological staining with cytokeratin 20 in resected lymph nodes. Expression of transducin (ß)-like 1 X-linked receptor 1 (TBL1XR1) in primary CRC tissues was also investigated. Chi-squared test was performed to reveal the correlations between ITC/LNMM and clinicopathological characteristics. Univariate and multivariate analyses were used to determine independent prognostic factors. Knockdown experiment together with proliferation and invasion assays were carried out to explore molecular mechanisms between TBL1XR1 and ITC/LNMM. RESULTS: About 29.2% (40/137) patients were identified as ITC/LNMM positive, and most of them (32/40 cases, 80%) showed high TBL1XR1 expression in primary CRC tissues. Both ITC/LNMM and TBL1XR1 expression were independent prognostic factors for disease relapse or metastasis. In vitro experiments demonstrated that TBL1XR1 can regulate the expression of vascular endothelial growth factor C and epithelial-mesenchymal transition proteins, thus mediate the process of lymph node metastasis. CONCLUSIONS: Identification of ITC/LNMM is significant in evaluating clinical outcome and guiding adjuvant chemotherapy for early-stage CRC patients. TBL1XR1 overexpression in CRC tissues can serve as an efficient biomarker to predict the status of ITC/LNMM.

Adaptive Activation of a Stress Response Pathway Improves Learning and Memory Through Gs and ß-Arrestin-1-Regulated Lactate Metabolism.

BACKGROUND: Stress is a conserved physiological response in mammals. Whereas moderate stress strengthens memory to improve reactions to previously experienced difficult situations, too much stress is harmful. METHODS: We used specific ß-adrenergic agonists, as well as ß2-adrenergic receptor (ß2AR) and arrestin knockout models, to study the effects of adaptive ß2AR activation on cognitive function using Morris water maze and object recognition experiments. We used molecular and cell biological approaches to elucidate the signaling subnetworks. RESULTS: We observed that the duration of the adaptive ß2AR activation determines its consequences on learning and memory. Short-term formoterol treatment, for 3 to 5 days, improved cognitive function; however, prolonged ß2AR activation, for more than 6 days, produced harmful effects. We identified the activation of several signaling networks downstream of ß2AR, as well as an essential role for arrestin and lactate metabolism in promoting cognitive ability. Whereas Gs-protein kinase A-cyclic adenosine monophosphate response element binding protein signaling modulated monocarboxylate transporter 1 expression, ß-arrestin-1 controlled expression levels of monocarboxylate transporter 4 and lactate dehydrogenase A through the formation of a ß-arrestin-1/phospho-mitogen-activated protein kinase/hypoxia-inducible factor-1α ternary complex to upregulate lactate metabolism in astrocyte-derived U251 cells. Conversely, long-term treatment with formoterol led to the desensitization of ß2ARs, which was responsible for its decreased beneficial effects. CONCLUSIONS: Our results not only revealed that ß-arrestin-1 regulated lactate metabolism to contribute to ß2AR functions in improved memory formation, but also indicated that the appropriate management of one specific stress pathway, such as through the clinical drug formoterol, may exert beneficial effects on cognitive abilities.