Cyclooxygenase (COX) is a key enzyme in the synthesis of prostanoids. Two isoforms of this enzyme have been identified: COX-1 and COX-2. Recent studies have suggested that COX-2, but not COX-1, may play a role in colorectal tumorigenesis. In the present study, we investigated the expression of COX-2 as well as COX-1 in human hepatocellular carcinoma (HCC) tissues using immunohistochemistry and immunoblotting. Forty-four surgically resected HCC tissues with adjacent nontumorous livers (NTs), involving 17 cases of chronic viral hepatitis and 27 cases of cirrhosis, and 7 surgically resected, histologically normal liver tissues were used. The well-differentiated HCC expressed COX-2 more frequently and strongly than less-differentiated HCC or hepatocytes of NTs. Lessdifferentiated HCCs expressed less COX-2 than hepatocytes of NTs, which showed scattered, strong COX-2 expression. Histologically normal liver was weakly positive for COX-2. The expression of COX-1 was weaker than that of COX-2 in hepatic neoplastic and non-neoplastic parenchymal cells. An enhanced expression of COX-1 was not observed in well-differentiated HCCs. Immunoblotting also confirmed up-regulation of COX-2, but not COX-1, in well-differentiated HCCs. The present study is the first to demonstrate a high expression of COX-2 in well-differentiated HCC and a low expression in advanced HCC, in contrast to its continuous expression during colorectal carcinogenesis. These findings suggested that COX-2 may play a role in the early stages of hepatocarcinogenesis, but not in the advanced stages, and may consequently be related to HCC dedifferentiation. (HEPATOLOGY 1999;29:688-696.) Cyclooxygenases (COXs) are key enzymes in the conversion of arachidonic acid to prostaglandins and other eicosanoids. Recently, two isoforms of the enzyme have been identified.

Recently, pleiotropic benefits of incretin therapy beyond glycemic control have been reported. Although cancer is one of the main causes of death in diabetic patients, few reports describe the anticancer effects of incretin. Here, we examined the effect of the incretin drug exendin (Ex)-4, a GLP-1 receptor (GLP-1R) agonist, on prostate cancer. In human prostate cancer tissue obtained from patients after they had undergone radical prostatectomy, GLP-1R expression colocalized with P504S, a marker of prostate cancer. In in vitro experiments, Ex-4 significantly decreased the proliferation of the prostate cancer cell lines LNCap, PC3, and DU145, but not that of ALVA-41. This antiproliferative effect depended on GLP-1R expression. In accordance with the abundant expression of GLP-1R in LNCap cells, a GLP-1R antagonist or GLP-1R knockdown with small interfering RNA abolished the inhibitory effect of Ex-4 on cell proliferation. Although Ex-4 had no effect on either androgen receptor activation or apoptosis, it decreased extracellular signal–regulated kinase (ERK)-mitogen-activated protein kinase (MAPK) phosphorylation in LNCap cells. Importantly, Ex-4 attenuated in vivo prostate cancer growth induced by transplantation of LNCap cells into athymic mice and significantly reduced the tumor expression of P504S, Ki67, and phosphorylated ERK-MAPK. These data suggest that Ex-4 attenuates prostate cancer growth through the inhibition of ERK-MAPK activation.

Purpose: The prognosis of platinum-based chemotherapyresistant metastatic urothelial cancer of the bladder remains poor. Personalized selection of the right peptides for each patient could be a novel approach for a cancer vaccine to boost anticancer immunity.Experimental Design: In this randomized, open-label, phase II study, patients ages !18 years with progressive bladder cancer after first-line platinum-based chemotherapy were randomly assigned (1:1) to receive personalized peptide vaccination (PPV) plus best supportive care (BSC) or BSC. PPV treatment used a maximum of four peptides chosen from 31 candidate peptides according to human leukocyte antigen types and peptide-reactive IgG titers, for 12 s.c. injections (8 injections, weekly; 4 injections, bi-weekly). The primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), immune response, and toxicity.Results: Eighty patients were randomly assigned to receive either PPV plus BSC (n ¼ 39) or BSC (n ¼ 41). No significant improvement in PFS was noted [HR, 0.7; 95% confidence interval (CI), 0.4-1.2, P ¼ 0.17]. For the secondary endpoints, PPV plus BSC significantly prolonged OS compared with BSC (HR, 0.58; 95% CI, 0.34-0.99, P ¼ 0.049), with median OS of 7.9 months (95% CI, 3.5-12.0) in the PPV plus BSC and 4.1 months (95% CI, 2.8-6.9) in the BSC. PPV treatment was well tolerated, without serious adverse drug reactions.Conclusions: PPV could not prolong PFS, but OS appeared to be improved with low toxicity and immune responses. Further large-scale, randomized trials are needed to confirm these results.

Dopamine-and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) plays a central role in medium spiny neurons in the neostriatum in the integration of various neurotransmitter signaling pathways. In its Thr-34-phosphorylated form, it acts as a potent protein phosphatase-1 inhibitor, and, in its Thr-75-phosphorylated form, it acts as a cAMP-dependent kinase inhibitor. Here, we investigated glutamate-dependent signaling cascades in mouse neostriatal slices by analyzing the phosphorylation of DARPP-32 at Thr-34 and Thr-75. Treatment with glutamate (5 mM) caused a complex change in DARPP-32 Thr-34 phosphorylation. An initial rapid increase in Thr-34 phosphorylation was NMDA͞␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)͞metabo-tropic glutamate-5 receptor-dependent and was mediated through activation of a neuronal nitric oxide synthase͞nitric oxide͞cGMP͞ cGMP-dependent kinase signaling cascade. A subsequent decrease in phosphorylation was attributable to activation of an NMDA͞ AMPA receptor͞Ca 2؉ ͞protein phosphatase-2B signaling cascade. This decrease was followed by rephosphorylation via a pathway involving metabotropic glutamate-5 receptor͞phospholipase C and extracellular receptor kinase signaling cascade. Treatment with glutamate initially decreased Thr-75 phosphorylation through activation of NMDA͞AMPA receptor͞Ca 2؉ ͞protein phosphatase-2A signaling. Thereafter, glutamate slowly increased Thr-75 phosphorylation through activation of metabotropic glutamate-1 receptor͞phospholipase C signaling. Our analysis of DARPP-32 phosphorylation in the neostriatum revealed that glutamate activates at least five different signaling cascades with different time dependencies, resulting in complex regulation of protein kinase and protein phosphatase activities.dopamine ͉ striatum ͉ nitric oxide ͉ metabotropic glutamate receptor ͉ protein phosphatase D ARPP-32, a dopamine-and cAMP-regulated phosphoprotein of 32 kDa, is a signal transduction molecule that is selectively enriched in medium spiny neurons in the neostriatum (1). Mice lacking DARPP-32 exhibit profound deficits in their molecular, electrophysiological, and behavioral responses to dopamine, drugs of abuse, and antipsychotic medication (2), indicating an essential role for DARPP-32 in dopamine signaling. DARPP-32 is phosphorylated at Thr-34 by cAMP-dependent protein kinase (PKA), resulting in its conversion into a potent inhibitor of protein phosphatase-1 (PP-1). DARPP-32 is phosphorylated at Thr-75 by cyclin-dependent kinase 5 (Cdk5) (3). DARPP-32 phosphorylated at Thr-75 inhibits PKA activity and thereby reduces the efficacy of dopamine signaling. Dopamine, by means of dopamine D1 receptors, activates PKA, which directly stimulates DARPP-32 Thr-34 phosphorylation and indirectly stimulates DARPP-32 Thr-75 dephosphorylation (4, 5). By regulating the activity of PKA and PP-1, dopamine controls the state of phosphorylation of various intracellular targets.Glutamate is the major excitatory neurotransmitter in the brain. The excitation of medium spiny neurons i...

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