Mutita Junking

Decreased expression of galectin-3 is associated with metastatic potential of liver fluke-associated cholangiocarcinoma.

Galectin-3, a beta-galactoside-binding lectin, is a multifunctional protein implicated in a variety of biological functions, including tumour cell adhesion, proliferation, differentiation, cancer progression and metastasis. The present study was performed to clarify the impact of galectin-3 expression on patients with liver fluke-associated cholangiocarcinoma. Galectin-3 expression was examined immunohistochemically in 53 patients with intrahepatic cholangiocarcinoma, who had undergone surgery without pre-operative therapy. All bile duct epithelium expressed galectin-3 with different intensities, according to the different histological subtypes. The poorly-differentiated type expressed galectin-3 less intensely than the papillary, well- to moderately-differentiated types (P=0.012). We observed the association of low galectin-3 expression with lymphatic invasion (P=0.002). Suppression of galectin-3 expression in two human cholangiocarcinoma cell lines using siRNA targeted to galectin-3 significantly increased cell migration and invasion without alterations in cell proliferation. Regulation of galectin-3 expression may therefore be an alternative therapeutic approach to control metastasis of cholangiocarcinoma.

Suppression of galectin‐3 expression enhances apoptosis and chemosensitivity in liver fluke‐associated cholangiocarcinoma

Cholangiocarcinoma (CCA) is a fatal disease with high resistance to anticancer drugs. This is probably in part due to enhanced resistance to apoptosis. We have previously shown that galectin‐3 (Gal‐3), a β‐galactoside‐binding lectin, is highly expressed in CCA tissues. In this study, we demonstrated further that Gal‐3 plays a direct role in anti‐apoptosis regardless of the apoptotic insults. The anti‐apoptotic activity and chemoresistance of CCA cells were related to Gal‐3 expression level. Suppression of Gal‐3 expression with siRNA stimulated apoptosis. siGal‐3‐K626 transiently depleted Gal‐3 expression to the baseline and dramatically induced apoptosis, while siGal‐3‐K402 suppressed Gal‐3 expression by 50% and provoked cell apoptosis, but only under apoptotic insults (hypoxic conditions or short UV radiation). These actions were reversed in Gal‐3 overexpressing CCA cells. The correlation between the degree of anti‐apoptotic activity and the level of endogenous Gal‐3 was demonstrated. Suppression of Gal‐3 expression in CCA cells with siGal‐3‐K402 significantly enhanced apoptosis induced by cisplatin or 5‐fluorouracil by approximately 10 times, whereas overexpression of Gal‐3 led to an increased resistance to drugs. In summary, the present study showed that the cellular level of Gal‐3 might contribute to the anti‐apoptotic activity and chemoresistance of CCA cells. Hence, Gal‐3 expression level in cancer cells or tissues may be a marker for predicting chemotherapeutic response, and Gal‐3 may be a specific gene‐targeting therapy option for treating CCA. (Cancer Sci 2009; 00: 000–000)

Human kidney anion exchanger 1 interacts with adaptor-related protein complex 1 μ1A (AP-1 mu1A)

Kidney anion exchanger 1 (kAE1) mediates chloride (Cl⁻) and bicarbonate (HCO₃⁻) exchange at the basolateral membrane of kidney α-intercalated cells. Impaired trafficking of kAE1 leads to defect of the Cl⁻/HCO₃⁻ exchange at the basolateral membrane and failure of proton (H+) secretion at the apical membrane, causing a kidney disease--distal renal tubular acidosis (dRTA). To gain a better insight into kAE1 trafficking, we searched for proteins physically interacting with the C-terminal region of kAE1 (Ct-kAE1), which contains motifs crucial for intracellular trafficking, by a yeast two-hybrid (Y2H) system. An adaptor-related protein complex 1 μ1A (AP-1 mu1A) subunit was found to interact with Ct-kAE1. The interaction between either Ct-kAE1 or full-length kAE1 and AP-1 mu1A were confirmed in human embryonic kidney (HEK) 293T by co-immunoprecipitation, affinity co-purification, co-localization, yellow fluorescent protein (YFP)-based protein fragment complementation assay (PCA) and GST pull-down assay. The interacting site for AP-1 mu1A on Ct-kAE1 was found to be Y904DEV907, a subset of YXXØ motif. Interestingly, suppression of endogenous AP-1 mu1A in HEK 293T by small interfering RNA (siRNA) decreased membrane localization of kAE1 and increased its intracellular accumulation, suggesting for the first time that AP-1 mu1A is involved in the kAE1 trafficking of kidney α-intercalated cells.

NF-κB is required for dengue virus NS5-induced RANTES expression

Dengue virus (DENV) infection associates with renal disorders. Patients with dengue hemorrhagic fever and acute kidney injury have a high mortality rate. Increased levels of cytokines may contribute to the pathogenesis of DENV-induced kidney injury. Currently, molecular mechanisms how DENV induces kidney cell injury has not been thoroughly investigated. Excessive cytokine production may be involved in this process. Using human cytokine RT(2) Profiler PCR array, 14 genes including IP-10, RANTES, IL-8, CXCL-9 and MIP-1β were up-regulated more than 2 folds in DENV-infected HEK 293 cells compared to that of mock-infected HEK 293 cells. In the present study, RANTES was suppressed by the NF-κB inhibitor, compound A (CpdA), in DENV-infected HEK 293 cells implying the role of NF-κB in RANTES expression. Chromatin immunoprecipitation (ChIP) assay showed that NF-κB binds more efficiently to its binding sites on the RANTES promoter in NS5-transfected HEK 293 cells than in HEK 293 cells expressing the vector lacking NS5 gene. To further examine whether the NS5-activated RANTES promoter is mediated through NF-κB, the two NF-κB binding sites on the RANTES promoter were mutated and this promoter was coupled to the luciferase cDNA. The result showed that when both binding sites of NF-κB in the RANTES promoter were mutated, the ability of NS5 to induce the luciferase activity was significantly decreased. Therefore, DENV NS5 activates RANTES production by increasing NF-κB binding to its binding sites on the RANTES promoter.

Role of Adaptor Proteins and Clathrin in the Trafficking of Human Kidney Anion Exchanger 1 (kAE1) to the Cell Surface

Kidney anion exchanger 1 (kAE1) plays an important role in acid–base homeostasis by mediating chloride/bicarbornate (Cl−/HCO3−) exchange at the basolateral membrane of α‐intercalated cells in the distal nephron. Impaired intracellular trafficking of kAE1 caused by mutations of SLC4A1 encoding kAE1 results in kidney disease – distal renal tubular acidosis (dRTA). However, it is not known how the intracellular sorting and trafficking of kAE1 from trans‐Golgi network (TGN) to the basolateral membrane occurs. Here, we studied the role of basolateral‐related sorting proteins, including the mu1 subunit of adaptor protein (AP) complexes, clathrin and protein kinase D, on kAE1 trafficking in polarized and non‐polarized kidney cells. By using RNA interference, co‐immunoprecipitation, yellow fluorescent protein‐based protein fragment complementation assays and immunofluorescence staining, we demonstrated that AP‐1 mu1A, AP‐3 mu1, AP‐4 mu1 and clathrin (but not AP‐1 mu1B, PKD1 or PKD2) play crucial roles in intracellular sorting and trafficking of kAE1. We also demonstrated colocalization of kAE1 and basolateral‐related sorting proteins in human kidney tissues by double immunofluorescence staining. These findings indicate that AP‐1 mu1A, AP‐3 mu1, AP‐4 mu1 and clathrin are required for kAE1 sorting and trafficking from TGN to the basolateral membrane of acid‐secreting α‐intercalated cells.

A Peptide Inhibitor Derived from the Conserved Ectodomain Region of DENV Membrane (M) Protein with Activity Against Dengue Virus Infection

Dengue virus (DENV) infection is a public health problem worldwide; thus, the development of a vaccine and anti‐DENV drugs is urgently needed. It has been observed that low levels of viremia in DENV‐infected individuals are associated with mild disease outcomes; therefore, reduction of DENV load should offer therapeutic benefits. Disruption of protein–protein interactions on the surface of DENV by a peptide that mimics part of its structural protein may affect stability of the virion structure and inhibit viral entry into host cells. To test this hypothesis, we generated a novel peptide inhibitor that mimics the conserved ectodomain region of DENV membrane (M) protein, MLH40 peptide, for DENV inhibition assays. MLH40 inhibited all four serotypes of the virus (DENV1–4) at half maximal inhibition concentration of 24–31 μm. MLH40 at 100 μm blocked DENV2 attachment to cells by 80%. The inhibitory activity of MLH40 against DENV was consistently observed with different cell types, including Vero, A549, and Huh7 cells. Prediction of MLH40 binding by a molecular docking program indicated that its N‐terminal loop may interact with DENV envelope (E) proteins and alter their dimer conformation. Thus, MLH40 may serve as a lead‐peptide inhibitor for the development of an anti‐DENV drug.

Human kidney anion exchanger 1 interacts with kinesin family member 3B (KIF3B)

Impaired trafficking of human kidney anion exchanger 1 (kAE1) to the basolateral membrane of α-intercalated cells of the kidney collecting duct leads to the defect of the Cl(-)/HCO(3)(-) exchange and the failure of proton (H(+)) secretion at the apical membrane of these cells, causing distal renal tubular acidosis (dRTA). In the sorting process, kAE1 interacts with AP-1 mu1A, a subunit of AP-1A adaptor complex. However, it is not known whether kAE1 interacts with motor proteins in its trafficking process to the plasma membrane or not. We report here that kAE1 interacts with kinesin family member 3B (KIF3B) in kidney cells and a dileucine motif at the carboxyl terminus of kAE1 contributes to this interaction. We have also demonstrated that kAE1 co-localizes with KIF3B in human kidney tissues and the suppression of endogenous KIF3B in HEK293T cells by small interfering RNA (siRNA) decreases membrane localization of kAE1 but increases its intracellular accumulation. All results suggest that KIF3B is involved in the trafficking of kAE1 to the plasma membrane of human kidney α-intercalated cells.

Testosterone reduces AGTR1 expression to prevent β-cell and islet apoptosis from glucotoxicity

Hypogonadism in men is associated with an increased incidence of type 2 diabetes. Supplementation with testosterone has been shown to protect pancreatic β-cell against apoptosis due to toxic substances including streptozotocin and high glucose. One of the pathological mechanisms of glucose-induced pancreatic β-cell apoptosis is the induction of the local rennin-angiotensin-aldosterone system (RAAS). The role of testosterone in regulation of the pancreatic RAAS is still unknown. This study aims to investigate the protective action of testosterone against glucotoxicity-induced pancreatic β-cell apoptosis via alteration of the pancreatic RAAS pathway. Rat insulinoma cell line (INS-1) cells or isolated male mouse islets were cultured in basal and high-glucose media in the presence or absence of testosterone, losartan, and angiotensin II (Ang II), then cell apoptosis, cleaved caspase 3 expression, oxidative stress, and expression of angiotensin II type 1 receptor (AGTR1) and p47(phox) mRNA and protein were measured. Testosterone and losartan showed similar effects in reducing pancreatic β-cell apoptosis. Testosterone significantly reduced expression of AGTR1 protein in INS-1 cells cultured in high-glucose medium or high-glucose medium with Ang II. Testosterone decreased the expression of AGTR1 and p47(phox) mRNA and protein in comparison with levels in cells cultured in high-glucose medium alone. Furthermore, testosterone attenuated superoxide production when co-cultured with high-glucose medium. In contrast, when cultured in basal glucose, supplementation of testosterone did not have any effect on cell apoptosis, oxidative stress, and expression of AGT1R and p47(phox). In addition, high-glucose medium did not increase cleaved caspase 3 in AGTR1 knockdown experiments. Thus, our results indicated that testosterone prevents pancreatic β-cell apoptosis due to glucotoxicity through reduction of the expression of ATGR1 and its signaling pathway.

Vivo-morpholino oligomers strongly inhibit dengue virus replication and production

Dengue virus (DENV) infection is a worldwide public health problem, which can cause severe dengue hemorrhagic fever (DHF) and life-threatening dengue shock syndrome (DSS). There are currently no anti-DENV drugs available, and there has been an intensive search for effective anti-DENV agents that can inhibit all four DENV serotypes. In this study, we tested whether vivo-morpholino oligomers (vivo-MOs), whose effect on DENV infection has not previously been studied, can inhibit DENV infection. Vivo-MOs were designed to target the top of 3’ stem-loop (3’ SL) in the 3’ UTR of the DENV genome and tested for inhibition of DENV infection in monkey kidney epithelial (Vero) cells and human lung epithelial carcinoma (A549) cells. The results showed that vivo-MOs could bind to a DENV RNA sequence and markedly reduce DENV-RNA, protein, and virus production in infected Vero and A549 cells. Vivo-MOs at a concentration of 4 µM could inhibit DENV production by more than 104-fold when compared to that of an untreated control. In addition, vivo-MOs also inhibited DENV production in U937 cells and primary human monocytes. Therefore, vivo-MOs targeting to the 3’ SL in the 3’ UTR of DENV genomes are effective and have the potential to be developed as anti-DENV agents.

Enhanced cytotoxic activity of effector T-cells against cholangiocarcinoma by dendritic cells pulsed with pooled mRNA

Cholangiocarcinoma is a malignancy of bile duct epithelia with an increasing in incidence rate worldwide. Surgery is the only curative treatment, while adjuvant chemotherapy and radiotherapy render poor responses. Cell-based immunotherapy is a potential strategy for cholangiocarcinoma treatment. However, variation of tumor antigens in cholangiocarcinoma leads to the ineffectiveness of cell-based immunotherapy. In this study, we examined the activation of effector T-cells by dendritic cells pulsed with protein lysate or total RNA from cholangiocarcinoma cell lines for their cytolytic activity against cholangiocarcinoma. Broad-spectrum antigen types with respect to RNA antigen sources were obtained from combination of three cholangiocarcinoma cell lines (KKU-213, KKU-100, and KKU-055). Compared with protein lysate–pulsed dendritic cells, total RNA–pulsed dendritic cells induced anti-tumor effector T-cell response with higher killing ability to KKU-100 and KKU-213 cells compared with protein lysate–pulsed dendritic cells. Moreover, pooled messenger RNA from three cholangiocarcinoma cell lines significantly increased the specific killing capacity of activated lymphocytes against KKU-213 cells. These results suggest that activation of anti-tumor effector T-cells against cholangiocarcinoma by RNA-pulsed dendritic cells is more effective than that by protein lysate–pulsed dendritic cells. In addition, pulsing dendritic cells with pooled messenger RNA from multiple cell lines enhanced the efficacy of a cellular immune response against cholangiocarcinoma.