Mobile DHHC palmitoylating enzyme mediates activity-sensitive synaptic targeting of PSD-95.

Protein palmitoylation is the most common posttranslational lipid modification; its reversibility mediates protein shuttling between intracellular compartments. A large family of DHHC (Asp-His-His-Cys) proteins has emerged as protein palmitoyl acyltransferases (PATs). However, mechanisms that regulate these PATs in a physiological context remain unknown. In this study, we efficiently monitored the dynamic palmitate cycling on synaptic scaffold PSD-95. We found that blocking synaptic activity rapidly induces PSD-95 palmitoylation and mediates synaptic clustering of PSD-95 and associated AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)-type glutamate receptors. A dendritically localized DHHC2 but not the Golgi-resident DHHC3 mediates this activity-sensitive palmitoylation. Upon activity blockade, DHHC2 translocates to the postsynaptic density to transduce this effect. These data demonstrate that individual DHHC members are differentially regulated and that dynamic recruitment of protein palmitoylation machinery enables compartmentalized regulation of protein trafficking in response to extracellular signals.

Identification of Cystatin SN as a novel tumor marker for colorectal cancer.

The goal of this study was to investigate Cystatin SN, a cysteine protease inhibitor, as a novel tumor marker for colorectal cancer (CRC). Gene expression profiles of mRNA from normal tissues and cancer cell lines were performed. Twenty-eight monoclonal antibodies for Cystatin SN were generated and serum Cystatin SN was quantified using ELISA in sera from 159 patients with CRC and 40 healthy controls. Cystatin SN was highly expressed in colon cancer cells. Employing a receiver-operating characteristic curve, we obtained an area under the curve of 0.708 for Cystatin SN, 0.819 for carcinoembryonic antigen (CEA) and 0.703 for carbohydrate antigen 19-9 (CA19-9). The combination assay of Cystatin SN, CEA and CA19-9 showed 62.9% sensitivity and 90.0% specificity. Especially, the sensitivity of the combination assay in stages I and II detection, in which stages curative operation would be possible, was improved over that of the assay testing only for CEA and CA19-9 (from 37.5 to 42.5% in stage I, from 49.0 to 60.8% in stage II). Furthermore, Western blot analysis revealed that Cystatin SN was increased in the urine from patients with CRC. Our results suggest the possibility of utilizing this novel tumor marker that can be tested in urine samples. These observations suggest that Cystatin SN in combination with CEA and CA19-9 is a useful tumor marker for detecting early stage CRC and that it is a unique urinary excretory protein, suggesting that Cystatin SN might be a novel candidate for use in mass screening for CRC.

Efficacy of zinc administration in patients with hepatitis C virus-related chronic liver disease.

OBJECTIVE: Zinc supplementation has been shown to contribute to inhibition of liver fibrosis and improvement in hepatic encephalopathy. However, little is known about the anti-inflammatory effect of zinc on hepatitis C virus (HCV)-related chronic liver disease (CLD). We therefore examined the effects of zinc administration on inflammatory activity and fibrosis in the liver of patients with HCV-related CLD. MATERIAL AND METHODS: Polaprezinc, a complex of zinc and l-carnosine, was administrated at 225 mg/day for 6 months to 14 patients with HCV-related CLD, in addition to their ongoing prescriptions. Peripheral blood cell counts, liver-related biochemical parameters, serological markers for liver fibrosis, HCV-RNA loads, and serum levels of zinc and ferritin were evaluated before and after zinc administration. RESULTS: Serum zinc concentrations were positively correlated with hepatic reserve before zinc supplementation. A significant increase in serum zinc level was observed after zinc supplementation (64+/-15 versus 78+/-26 mg/dl, p=0.0156). Treatment with polaprezinc significantly decreased serum aminotransferase levels (aspartate aminotransferase (AST): 92+/-33 versus 63+/-23 IU/l, p=0.0004; alanine aminotransferase (ALT): 106+/-43 versus 65+/-32 IU/l, p=0.0002), whereas alkaline phosphatase levels were significantly increased (305+/-117 versus 337+/-118 U/l, p=0.0020). Serum ferritin levels were significantly decreased by treatment with polaprezinc (158+/-141 versus 101+/-80 ng/ml, p=0.0117). The reduction rate of ALT levels by polaprezinc was positively correlated with that of ferritin (r(2)=0.536, p=0.0389). There was a tendency toward a decrease in serum type IV collagen 7S levels after treatment with polaprezinc. However, administration of polaprezinc did not affect peripheral blood cell counts, other liver function tests, or HCV-RNA loads. CONCLUSIONS: These findings suggest that polaprezinc exerts an anti-inflammatory effect on the liver in patients with HCV-related CLD by reducing iron overload.

Successful treatment of large-size advanced hepatocellular carcinoma by transarterial chemoembolization followed by the combination therapy of percutaneous ethanol-lipiodol injection and radiofrequency ablation.

We report a case of large-size hepatocellular carcinoma (HCC) successfully treated with transarterial chemoembolization (TACE) followed by the combination therapy of percutaneous ethanol-lipiodol injection and radiofrequency ablation (PELI-RFA) and percutaneous ethanol-lipiodol injection (PELI) therapy. In the present case, the patient had a large-size advanced HCC, 7 cm in diameter, located in the S8 region of the liver. In addition, the hepatic reserve of the patient was severely poor. In order not to impair the poor hepatic reserve, we chose PELI-RFA and PELI, originally developed in our department and reported as milder treatment modalities than others. After TACE , PELI-RFA and PELI were performed several times, the HCC was totally destroyed and early enhancement shown by helical dynamic computed tomography disappeared completely after treatment. The hepatic reserve of the patient was not impaired by the series of treatments. Serum levels of tumor markers, alpha-fetoprotein and Des-gamma-carboxy prothrombin, were rapidly decreased to almost normal levels. PELI-RFA and PELI may be effective for the treatment of large-size HCC of patients with poor hepatic reserve.

Site-directed mutagenesis study of the antibody 2D7 which catalyzes a reaction for insertion of Cu2+ into mesoporphyrin.

Monoclonal antibody 2D7 generated against a transition-state analog N-methyl mesoporphyrin catalyzes a reaction for insertion of a cupric ion into mesoporphyrin. To investigate amino acid residues responsible for the catalytic activity, site-directed mutagenesis of the amino acid residues in the third complementarity determining region of the heavy chain (CDRH3) was performed on the antigen-binding fragment (Fab) of the antibody. Recombinant Fab mutants, in which Arg95 is replaced with Ala (R95A), Asp96 with Asn (D96N) and Met97 with Gly (M97G), were examined in terms of the catalytic efficiency of the reaction (k/K(S)) and the dissociation constant for N-methyl mesoporphyrin binding (K(d)) and these values were compared with those of the wild type. The k/K(S) values of the R95A and D96N mutants were 0.96% and 1.0% of that of the wild type, respectively, whereas the M97G mutant had no detectable catalytic activity. The K(d) values of the R95A and D96N mutants were 165 and 69 times that of the wild type, respectively, while that of the M97G mutant was similar to that of the wild type. The relationship between the k/K(S) and 1/K(d) values in the wild type and the R95A and D96N mutants suggests that Arg95 and Asp96 are responsible for stabilizing the transition-state in the catalytic reaction. The results of the M97G mutant allow us to propose that Met97 plays an important role in the catalytic activity probably due to a subtle and specific conformation of the antibody.

Comparison between combination therapy of percutaneous ethanol injection and radiofrequency ablation and radiofrequency ablation alone for patients with hepatocellular carcinoma.

AIM: In the present study, the characteristics of PEI-RFA treatment were further elucidated by analyzing the relationship between the volume of coagulated necrosis and the energy requirement for ablation or the amount of ethanol injected into HCC. METHODS: The volume of coagulated necrosis, total energy requirement and energy requirement for coagulation of per unit volume were examined in the groups of PEI-RFA and RFA alone using the Cool-tip RF system. RESULTS: The results showed that the volume of coagulated necrosis induced was significantly larger in PEI-RFA group than in routine RFA group, when the total energy administered was comparable in both groups. In PEI-RFA, enlargement of coagulated necrosis was admitted in 3 dimensions and the amount of energy requirement per unit volume of coagulated necrosis was negatively correlated with the amount of ethanol injected into HCC. CONCLUSION: These results suggest that, compared to RFA alone, PEI-RFA enables to induce comparable coagulated necrosis with smaller energy requirement, and that PEI-RFA is likely to be less invasive than RFA alone irrespective of inducing enhanced coagulated necrosis. Thus, simple prior injection of ethanol may make RFA treatment more effective and less invasive for the treatment of patients with HCC.

Efficacy of combination therapies of percutaneous or laparoscopic ethanol-lipiodol injection and radiofrequency ablation.

Percutaneous radiofrequency ablation (RFA) is able to destroy hepatocellular carcinoma (HCC) in a few sessions without major complications. We have previously shown that not only the combined use of percutaneous ethanol injection and RFA (PEI-RFA) but also injection of mixture of ethanol and lipiodol (PELIT) was useful for the treatment of HCC. In the present study, we further developed the combined use of PELIT and RFA through percutaneous or laparoscopic approach (PELI-RFA or LELI-RFA) and evaluated its usefulness. Nineteen nodules in 18 cases were treated with PELI-RFA or LELI-RFA. In the cases treated with LELI-RFA, no bleeding and no spilling milky fluid containing tumor cells were observed from the surface of ablated tumors. In the cases sufficiently treated with PELI-RFA or LELI-RFA, the mixture of ethanol and lipiodol was accumulated in the entire region of the tumor and low-density area was observed around the lipiodol deposit by computed tomography (CT). These delineations of coagulated area were helpful to evaluate the precise area of safety margin around the tumor treated with PELI-RFA or LELI-RFA. Furthermore, the total volume of coagulated necrosis significantly and positively correlated with the product of energy requirement for ablation and the volume of ethanol injected by PELI-RFA or LELI-RFA. Among the cases treated with PELI-RFA or LELI-RFA, local recurrence emerged only in one case in whom enough safety margin could not be achieved by PELI-RFA. Therefore, it is critical to evaluate whether enough safety margin could be obtained with RFA therapy, and PELI-RFA and LELI-RFA are helpful in visualizing the safety margin area.

Combination therapy of percutaneous ethanol injection and radiofrequency ablation against hepatocellular carcinomas difficult to treat.

Radiofrequency ablation (RFA) is an effective modality for the treatment of hepatocellular carcinoma (HCC), because it can induce large coagulated necrosis in a few sessions. We have recently reported that the combination therapy of percutaneous ethanol injection (PEI) with RFA (PEI-RFA) created enhancement of coagulated necrosis compared with RFA alone. In the present study, we adopted PEI-RFA for the treatment of HCCs located in the regions that are difficult to treat with RFA alone. Five patients with biopsy-proven HCC and liver cirrhosis underwent PEI-RFA therapy. In these patients, HCCs were located beside the gallbladder, inferior vena cava or portal vein or kidney, or immediately under the diaphragm. Prior to RFA, 99.5% ethanol was injected into the region of HCC located in the regions where RFA energy appears to be difficult to reach. In all cases, HCC was totally coagulated by PEI-RFA. Injecting ethanol prior to RFA therapy caused no major side effects. These results indicate that PEI-RFA may be effective for the treatment of HCCs located in the regions that are difficult to treat with RFA alone as well as large-sized HCCs.

Clinical significance of lens culinaris agglutinin-reactive fraction of serum alpha-fetoprotein in patients with hepatocellular carcinoma.

alpha-fetoprotein (AFP) is an important marker for the diagnosis of hepatocellular carcinoma (HCC) and has been widely used in clinical settings. Recently, the importance of lens culinaris agglutinin-reactive fraction of AFP (AFP-L3) has been indicated. However, the clinical significance of the level of AFP-L3 protein in relation to the characteristics of HCC has not been fully evaluated. In the present study, both the ratio of AFP-L3 (AFP-L3%) and the absolute value of AFP-L3 (AFP-L3-AV) were examined in 80 patients with HCC, and evaluated with respect to characteristics of HCC such as grade of differentiation, size of tumor and morphological findings. Among HCC-specific tumor markers, AFP, AFP-L3% and protein induced in vitamin K absence (PIVKA-II), AFP showed the highest positive rate in patients with HCC, while AFP-L3% showed the lowest rate. AFP-L3% and AFP-L3-AV were, however, most significantly correlated with the grade of HCC differentiation, while AFP showed the least significant correlation. Furthermore, AFP-L3% was most significantly correlated with the size of HCC in patients with solitary HCC. Conversely, neither AFP-L3-AV nor PIVKA-II showed a significant correlation with the size of HCC. In relation to morphological differences of HCC, although AFP-L3%, AFP-L3-AV and PIVKA-II were significantly higher in the diffuse type of HCC than in the nodular type of HCC, AFP was most significantly correlated with the morphological differences of HCC. These results indicate that tumor markers for HCC, such as AFP, AFP-L3%, AFP-L3-AV and PIVKA-II, may play different roles in predicting the characteristics of HCC.