Kazutoshi Tobimatsu

Dok1 mediates high-fat diet–induced adipocyte hypertrophy and obesity through modulation of PPAR-γ phosphorylation

Insulin receptor substrate (IRS)-1 and IRS-2 have dominant roles in the action of insulin, but other substrates of the insulin receptor kinase, such as Gab1, c-Cbl, SH2-B and APS, are also of physiological relevance. Although the protein downstream of tyrosine kinases-1 (Dok1) is known to function as a multisite adapter molecule in insulin signaling, its role in energy homeostasis has remained unclear. Here we show that Dok1 regulates adiposity. Expression of Dok1 in white adipose tissue was markedly increased in mice fed a high-fat diet, whereas adipocytes lacking this adapter were smaller and showed a reduced hypertrophic response to this dietary manipulation. Dok1-deficient mice were leaner and showed improved glucose tolerance and insulin sensitivity compared with wild-type mice. Embryonic fibroblasts from Dok1-deficient mice were impaired in adipogenic differentiation, and this defect was accompanied by an increased activity of the protein kinase ERK and a consequent increase in the phosphorylation of peroxisome proliferator–activated receptor (PPAR)-γ on Ser112. Mutation of this negative regulatory site for the transactivation activity of PPAR-γ blocked development of the lean phenotype caused by Dok1 ablation. These results indicate that Dok1 promotes adipocyte hypertrophy by counteracting the inhibitory effect of ERK on PPAR-γ and may thus confer predisposition to diet-induced obesity.

Multicenter retrospective analysis of systemic chemotherapy for advanced neuroendocrine carcinoma of the digestive system

This study analyzed outcomes of systemic chemotherapy for advanced neuroendocrine carcinoma (NEC) of the digestive system. Clinical data from 258 patients with unresectable or recurrent NEC of the gastrointestinal tract (GI) or hepato‐biliary‐pancreatic system (HBP), who received chemotherapy, were collected from 23 Japanese institutions and analyzed retrospectively. Patients had primary sites in the esophagus (n = 85), stomach (n = 70), small bowel (n = 6), colorectum (n = 31), hepato‐biliary system (n = 31) and pancreas (n = 31). Median overall survival (OS) was 13.4 months the esophagus, 13.3 months for the stomach, 29.7 months for the small bowel, 7.6 months for the colorectum, 7.9 months for the hepato‐biliary system and 8.5 months for the pancreas. Irinotecan plus cisplatin (IP) and etoposide plus cisplatin (EP) were most commonly selected for GI‐NEC and HBP‐NEC. For patients treated with IP/EP (n = 160/46), the response rate was 50/28% and median OS was 13.0/7.3 months. Multivariate analysis among patients treated with IP or EP showed that the primary site (GI vs HBP; hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.35–0.97) and baseline serum lactate dehydrogenase levels (not elevated vs elevated; HR 0.65, 95% CI 0.46–0.94) were independent prognostic factors for OS, while the efficacy of IP was slightly better than for EP (HR 0.80, 95% CI 0.48–1.33; P = 0.389). IP and EP are the most common treatment regimens for NEC of the digestive system. HBP primary sites and elevated lactate dehydrogenase levels are unfavorable prognostic factors for survival. A randomized controlled trial is required to establish the appropriate chemotherapy regimen for advanced NEC of the digestive system. This study was registered at UMIN as trial number 000005176.

Overexpression of the transcriptional coregulator Cited2 protects against glucocorticoid-induced atrophy of C2C12 myotubes.

In patients with various catabolic conditions, glucocorticoid excess induces skeletal muscle wasting by accelerating protein degradation via the ubiquitin-proteasome pathway. Although the transcriptional coactivator p300 has been implicated in this pathological process, regulatory mechanisms and molecular targets of its action remain unclear. Here we show that CREB-binding protein (CBP)/p300-interacting transactivator with ED-rich tail 2 (Cited2), which binds to the cysteine-histidine-rich region 1 of p300 and CBP, regulates muscle mass in vitro. Adenovirus-mediated overexpression of wild-type Cited2 significantly blocked morphological alterations of C2C12 myotubes with a concomitant decrease in myosin heavy chain protein in response to synthetic glucocorticoid dexamethasone, which were attributable to the reduced induction of atrophy-related ubiquitin ligases MuRF1 and MAFbx. These myotube-sparing effects were less pronounced, however, with a carboxyl-terminally truncated mutant of Cited2 that lacked the ability to bind p300. These results suggest that the gain of Cited2 function counteracts glucocorticoid-induced muscle atrophy through inhibition of proteolysis mediated by p300-dependent gene transcription.

Multicenter retrospective analysis of systemic chemotherapy in poorly differentiated neuroendocrine carcinoma of the digestive system.

274 Background: Poorly differentiated neuroendocrine carcinoma (PDNEC) is a rare and aggressive disease. No standard regimen has yet been established for advanced PDNEC, although regimens for small-cell lung carcinoma such as irinotecan + cisplatin (IP) or etoposide + cisplatin (EP), are usually adopted. The aim of this study was to investigate the outcomes according to the patients characteristics and treatment regimens for patients with PDNEC of the digestive system. METHODS Data was collected from the medical records of patients at 23 hospitals. The selection criteria were as follows: 1) histologically proven PDNEC, small cell carcinoma, mixed endocrine-exocrine carcinoma with a PDNEC component, or histologically proven neuroendocrine tumor with rapidly progressive clinical course; 2) primary tumor arising from the gastrointestinal tract (GI) or the hepato-biliary-pancreatic system (HBP); and 3) inoperable or recurrent disease treated with systemic chemotherapy between April 2000 and March 2011. RESULTS There were 258 patients (pts). The median age was 62.5 years (range, 26-81); male/female, 182/76 pts; the primary site was the esophagus/stomach/small bowel/colorectum/hepato-biliary system/pancreas in 85/70/6/31/31/35 pts. According to these primary sites, the median overall survival period (mOS) was 13.4/13.3/29.7/7.6/7.9/8.5 months, respectively. The most commonly used regimen was IP (160 pts, 62%), followed by EP (46 pts, 18%). For the patients treated with IP/EP, the response rates (RR) were 50%/27%, the progression free survival periods (mPFS) were 5.2/4.0 months, and mOS were 13.0/7.3 months. The subgroup outcome data for patients with HBP or GI cancers are shown in Table. A multivariate analysis demonstrated that a primary HBP cancer (HR=1.96, p=0.002), and a poor PS (HR=2.33, p=0.01) were independent unfavorable prognostic factors. CONCLUSIONS PDNEC of the HBP has a poorer prognosis than GI. IP was the most commonly selected treatment regimen, and seemed to have a favorable treatment outcome. [Table: see text].

Muscle-Specific Overexpression of Heparin-Binding Epidermal Growth Factor-Like Growth Factor Increases Peripheral Glucose Disposal and Insulin Sensitivity

Physical exercise ameliorates metabolic disorders such as type 2 diabetes mellitus and obesity, but the molecular basis of these effects remains elusive. In the present study, we found that exercise up-regulates heparin-binding epidermal growth factor-like growth factor (HB-EGF) in skeletal muscle. To address the metabolic consequences of such gain of HB-EGF function, we generated mice that overexpress this protein specifically in muscle. The transgenic animals exhibited a higher respiratory quotient than did wild-type mice during indirect calorimetry, indicative of their selective use of carbohydrate rather than fat as an energy substrate. They also showed substantial increases in glucose tolerance, insulin sensitivity, and glucose uptake by skeletal muscle. These changes were accompanied by increased kinase activity of Akt in skeletal muscle and consequent inhibition of Forkhead box O1-dependent expression of the pyruvate dehydrogenase kinase 4 gene. Furthermore, mice with a high level of transgene expression were largely protected from obesity, hepatic steatosis, and insulin resistance, even when maintained on a high-fat diet. Our results suggest that HB-EGF produced by contracting muscle acts as an insulin sensitizer that facilitates peripheral glucose disposal.

Polypoid leiomyosarcoma of the esophagus treated by endoscopic submucosal dissection.

We report a rare case of polypoid leiomyosarcoma of the esophagus that was treated by endoscopic submucosal dissection (ESD). A 63‐year‐old man with complaints of progressive dysphagia was referred to Hyogo Cancer Center for treatment of esophageal tumor. Esophagoscopy revealed a polypoid tumor 25 mm in diameter on the left side of the upper esophagus. Despite several biopsy specimens, the diagnosis could not be confirmed. Computed tomography showed a protruded, homogeneously enhancing mass in the upper esophagus, but no lymph node enlargement or metastasis. After 1.5 months, the esophagogram showed a filling defect 47 mm in diameter in the upper esophagus. Given this rapid tumor growth, en bloc resection was done by ESD for therapeutic diagnosis. After this treatment, the tumor seemed to grow larger, showing a short stalk and occupying the esophageal lumen. Histopathologically, the tumor comprised pleomorphic spindle cells with mitosis. Tumor invasion involved the lumina propria mucosae and contact with the muscularis mucosae, but not involving the submucosa. Immunohistochemical examination showed positive staining for smooth muscle actin and HHF35, but negative for desmin, caldesmon, CD34, c‐kit, DOG1, ALK, S‐100 protein and cytokeratin. These histopathological findings were compatible with a diagnosis of esophageal leiomyosarcoma derived from the muscularis mucosae.

Randomized phase II study of mixing steroid to reduce venous pain in patients with colorectal cancer receiving oxaliplatin through peripheral vein (APOLLO study).

474 Background: Although theCapeOX (capecitabine+oxaliplatin) regimen obviates the need for a central venous port, administration of oxaliplatin through peripheral vein can cause venous pain. One of the reasons is pH. The pH level of oxaliplatin solution is about 4.8 and that of buffered by steroid is approximately 7.0. To test the hypothesis that adjusting the pH of oxaliplatin solution by mixing steroid can reduce venous pain, we have conducted the randomized control study to compare pH-adjusted oxaliplatin solution with unadjusted oxaliplatin solution. Methods: This was a single-blinded multicenter randomized phase II study. Colorectal cancer patients receiving oxaliplatin through peripheral vein were enrolled and randomly assigned to arm A (oxaliplatin 130 mg/m2 with dexamethasone (DEX) 2 mg) or arm B (the same, without DEX) (UMIN000004286. Venous pain was evaluated according to CTCAE criteria (ver. 4.0) and the verbal rating scale (VRS). Assessments were conducted every 3 weeks until cycle 4. Results...