Early Tumor Shrinkage and Depth of Response as Predictors of Survival for Advanced Biliary Tract Cancer: An Exploratory Analysis of JCOG1113.

BACKGROUND: Recent studies suggest that early tumor shrinkage (ETS) and depth of response (DpR) reflect outcomes of chemotherapy in various cancers. This study evaluated the association of ETS and DpR with clinical outcomes using data from JCOG1113, which demonstrated the non-inferiority of gemcitabine plus S-1 (GS) to gemcitabine plus cisplatin (GC) for chemotherapy-naïve advanced biliary tract cancer. MATERIAL AND METHODS: In total, 354 (289 with measurable target lesions) patients enrolled in JCOG1113 were divided into ETS-unachieved and ETS-achieved groups (≥20% tumor reduction at week 6) and DpR-low and DpR-high groups (≥40% maximum shrinkage) until 12 weeks after enrollment. The impact of ETS and DpR on survival outcome was evaluated using the multivariable Cox proportional hazard model. RESULTS: The proportions of patients in the ETS-achieved and DpR-high groups were similar between the 2 treatment arms. The hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS) for the ETS-achieved group were 0.70 (95% confidence interval (CI), 0.52-0.93) and 0.60 (95%CI, 0.44-0.81), respectively. The HRs of PFS and OS for the DpR-high group were 0.67 (95%CI, 0.48-0.94) and 0.64 (95%CI, 0.46-0.90), respectively. In the subpopulation treatment effect pattern plot analysis, most patients in the ETS-achieved group in the GC arm did not experience disease progression after 12 weeks from the landmark. CONCLUSION: As on-treatment markers, ETS and DpR were effective tools. ETS was clinically useful, because it can be used to evaluate the outcomes of treatment early at a specific time.

Effect of systemic inflammatory response on induction chemotherapy followed by chemoradiotherapy for locally advanced pancreatic cancer: an exploratory subgroup analysis on systemic inflammatory response in JCOG1106.

OBJECTIVE: JCOG1106, a randomized phase II trial conducted to compare chemoradiotherapy (S-1 concurrent radiotherapy) with (Arm B) or without (Arm A) induction chemotherapy using gemcitabine in patients with locally advanced pancreatic cancer, showed a more favorable long-term survival in Arm A. This study was aimed at exploring whether some subgroups classified by the systemic inflammatory response might derive greater benefit from either treatment. METHODS: All subjects eligible for JCOG1106 were included in this analysis (n = 51/49 in Arm A/B). This exploratory subgroup analysis was performed by Cox regression analysis to investigate the impact of the systemic inflammatory response, as assessed based on the serum C-reactive protein, serum albumin (albumin), Glasgow Prognostic Score and derived neutrophil-lymphocyte ratio, at the baseline on overall survival. P values <0.1 for the interaction were regarded as denoting significant association. RESULTS: Glasgow prognostic score showed significant treatment interactions for overall survival. Hazard ratios of Arm B to Arm A were 1.35 (95% confidence interval, 0.82-2.23) in the Glasgow Prognostic Score 0 (C-reactive protein ≤10 mg/L and albumin ≥35 g/L) (n = 44/34 in Arm A/B) and 0.59 (95% confidence interval, 0.24-1.50) in the Glasgow Prognostic Score 1/2 (C-reactive protein >10 mg/L and/or albumin <35 g/L) (n = 7/15) (P-interaction = 0.06). C-reactive protein alone and albumin alone also showed significant treatment interactions for overall survival. CONCLUSIONS: Survival benefits of induction chemotherapy in chemoradiotherapy for locally advanced pancreatic cancer were observed in patients with elevated Glasgow Prognostic Score, high C-reactive protein and low albumin. These results suggest that systemic inflammatory response might be considered to apply induction chemotherapy preceding chemoradiotherapy.

The clinical outcomes of combination chemotherapy in elderly patients with advanced biliary tract cancer: an exploratory analysis of JCOG1113.

In the FUGA-BT trial (JCOG1113), gemcitabine plus S-1 (GS) showed non-inferiority to gemcitabine plus cisplatin (GC) in overall survival (OS) with good tolerance for patients with advanced biliary tract cancer (BTC). We performed a subgroup analysis focused on the elderly cohort of this trial. All 354 enrolled patients in JCOG1113 were classify into two groups; < 75 (non-elderly) and ≥ 75 years (elderly) group. We investigated the influence of age on the safety analysis, including the incidence of chemotherapeutic adverse events and the efficacy analysis, including OS. There were no remarkable differences in OS between the elderly (n = 60) and the non-elderly groups (n = 294). In the elderly group, median OS was 12.7 and 17.7 months for those who received GC (n = 20) and GS (n = 40), respectively. The prevalence of all-grade adverse events was similar between the elderly and the non-elderly groups. However, among the elderly group, Grade ≥ 3 hematological adverse events were more frequently observed in the GC arm than in the GS arm. The clinical outcomes of combination chemotherapy in elderly patients with advanced BTC were comparable to non-elderly patients. GS may be the more favorable treatment for elderly patients with advanced BTC.

Phase II study of S-1 and oxaliplatin as neoadjuvant chemotherapy for locally advanced adenocarcinoma of the gastric or esophagogastric junction: KSCC1601.

BACKGROUND: Perioperative chemotherapy is the standard of care for locally advanced gastric cancer (LAGC). This phase II study investigated the efficacy and safety of S-1 and oxaliplatin (SOX) as neoadjuvant chemotherapy (NAC) for LAGC and esophagogastric junction cancer (EGJC). METHODS: Patients completed up to three cycles of SOX130 (oxaliplatin 130 mg/m2 on day 1, oral S-1 40-60 mg twice daily for 2 weeks every 3 weeks), followed by gastrectomy and D2 lymphadenectomy. The primary endpoint was the pathological response rate (pRR). The anastomosis leakage rate was the secondary endpoint in patients with EGJC, and other secondary endpoints were the R0 resection, overall survival (OS), and relapse-free survival (RFS) rates. RESULTS: Between April 2016 and July 2017, 47 patients (24 EGJC, 23 LAGC) were enrolled in this study. Forty-two patients (89.4%, 95% confidence interval [CI] = 76.9-96.5) underwent surgery, and R0 resection was achieved in 41 patients. The pRR was 59.5% (90% CI = 45.7-72.3). The major grade 3 or 4 toxicities were appetite loss in six patients (12.8%), thrombocytopenia in five patients (10.6%), and neutropenia and diarrhea in three patients (6.4%) each. The rate of severe anastomotic leakage (Clavien-Dindo classification grade III or higher) in 20 EGJC was 25.0% (90% CI = 10.4-45.6). The 3-year OS and RFS rate were 62.9% (95% CI = 47.2-75.1) and 53.2% (95% CI = 38.1-66.2), respectively. CONCLUSION: SOX130 demonstrated substantial benefit for LAGC and EGJC. However, special attention should be paid to anastomotic leakage during surgery for EGJC.

Comparison of gemcitabine-based chemotherapies for advanced biliary tract cancers by renal function: an exploratory analysis of JCOG1113.

JCOG1113 is a randomized phase III trial in patients with advanced biliary tract cancers (BTCs) (UMIN000001685), and gemcitabine plus S-1 (GS) was not inferior to gemcitabine plus cisplatin (GC). However, poor renal function often results in high toxicity of S-1. Therefore, we examined whether GS can be recommended for patients with low creatinine clearance (CCr). Renal function was classified by CCr as calculated by the Cockcroft-Gault formula: high CCr (CCr ≥ 80 ml/min) and low CCr (80 > CCr ≥ 50 ml/min). Of 354 patients, 87 patients on GC and 91 on GS were included in the low CCr group, while there were 88 patients on GC and 88 patients on GS in the high CCr group. The HR of overall survival for GS compared with GC was 0.687 (95% CI 0.504-0.937) in the low CCr group. Although the total number of incidences of all Grade 3-4 non-haematological adverse reactions was higher (36.0% vs. 11.8%, p = 0.0002), the number of patients who discontinued treatment was not different (14.1% vs. 16.9%, p = 0.679) for GS compared with GC in the low CCr group. This study suggests that GS should be selected for the treatment of advanced BTC patients with reduced renal function.

Phase 1 study of Gemcitabine/Nab-paclitaxel/S-1 in patients with unresectable pancreatic cancer (GeNeS1S trial).

PURPOSE: We conducted a phase 1 study to determine the maximum tolerated dose and the recommended dose of gemcitabine/nab-paclitaxel/S-1 combination chemotherapy in patients with unresectable pancreatic cancer. METHODS: We enrolled patients aged 20 years or older with unresectable pancreatic cancer and who had not been treated with chemotherapy or radiation therapy. Gemcitabine and nab-paclitaxel were administered on days 1 and 8, and S-1 was administered orally twice daily for 2 weeks, repeated every 3 weeks. The starting dose was level 0 [gemcitabine 700 mg/m2, nab-paclitaxel 90 mg/m2, S-1 60/80/100 mg/day (< 1.25 m2/1.25-1.50 m2/ > 1.5 m2)]. Dose-limiting toxicities were determined during the first course, and a classical 3 + 3 dose finding design was planned. RESULTS: From March 2018 to October 2019, 20 patients were enrolled. At dose level 0, three of six patients experienced dose-limiting toxicities; one grade 3 skin rash on day 8, and two grade 3 or 4 neutropenia on day 8. At dose level-1 (gemcitabine 600 mg/m2, nab-paclitaxel 90 mg/m2, and S-1 50/70/80 mg/day), two of twelve patients experienced dose-limiting toxicities, all of which were grade 3 neutropenia on day 8. The most frequently observed toxicity during eight courses was neutropenia. Other treatment-related adverse events were mild. Eleven out of 19 (58%) patients achieved partial response. CONCLUSION: We defined the maximum tolerated dose and the recommended dose for combination therapy with gemcitabine/nab-paclitaxel/S-1 as dose level-1. Considering the observed response rate, further studies are warranted in order to determine the efficacy of this regimen (UMIN-CTR 000030007).

Randomized phase II study of chemoradiotherapy with versus without induction chemotherapy for locally advanced pancreatic cancer: Japan Clinical Oncology Group trial, JCOG1106.

BACKGROUND: Chemoradiotherapy is a treatment option for locally advanced pancreatic cancer. However, the efficacy of induction chemotherapy prior to chemoradiotherapy is uncertain. The aim of this randomized, multicentre phase II study is to evaluate the efficacy and safety of chemoradiotherapy with and without induction chemotherapy to determine the significance of induction chemotherapy. METHODS: Patients with locally advanced pancreatic cancer were randomly assigned to the chemoradiotherapy arm (Arm A) or induction chemotherapy followed by the chemoradiotherapy arm (Arm B). Patients in Arm A underwent radiotherapy with concurrent S-1. Patients in Arm B received induction gemcitabine for 12 weeks, and thereafter, only patients with controlled disease underwent the same chemoradiotherapy as Arm A. After chemoradiotherapy, gemcitabine was continued until disease progression or unacceptable toxicity in both arms. The primary endpoint was overall survival. RESULTS: Amongst 102 patients enrolled, 100 were eligible for efficacy assessment. The probability of survival was greater in Arm B in the first 12 months, but the trend was reversed in the following periods (1-year survival 66.7 vs. 69.3%, 2-year survival 36.9 vs. 18.9%). The hazard ratio was 1.255 (95% confidence interval 0.816-1.930) in favour of Arm A. Gastrointestinal toxicity was slightly more frequent and three treatment-related deaths occurred in Arm A. CONCLUSIONS: This study suggested that the chemoradiotherapy using S-1 alone had more promising efficacy with longer-term survival, compared with induction gemcitabine followed by chemoradiotherapy for locally advanced pancreatic cancer. CLINICAL TRIAL REGISTRATION: The study was registered at the UMIN Clinical Trials Registry as UMIN000006811.

Clinical features of immune-mediated hepatotoxicity induced by immune checkpoint inhibitors in patients with cancers.

PURPOSE: The risk factors and clinical characteristics of ICI-induced immune-mediated hepatotoxicity (IMH) are not fully understood. Thus, the present study sought to clarify the clinical features of IMH. METHODS: All patients treated with ICIs between September 2014 and April 2019 at our institution were included. Clinical data were retrospectively collected from medical records. The frequency of grade ≥ 2 liver damage, clinical characteristics, and risk factors for developing IMH were examined. RESULTS: Overall, 250 patients (median age 71 years; range 30-87 years; 202 males and 48 females) were included in the analyses. Forty-five patients had elevated transaminase levels (> threefold the upper limit of normal). Of these, 21 were considered to have IMH. The remaining 24 patients had other causes of elevated transaminase levels. Steroids were administered to 13/21 patients with IMH. Although all patients exhibited improvement, IMH was not associated with the anticancer efficacy of the ICIs or OS. A multivariable analysis revealed that IMH was significantly associated with malignant melanoma (odds ratio [OR] 11.6; 95% confidence interval [CI] 3.5-38.0; P = 0.0002) and ipilimumab-nivolumab combination therapy (OR 61.2; 95% CI 7.9-1275.3; P < 0.0001). CONCLUSION: Immune-mediated hepatotoxicity occurred in 9.5% of patients treated with ICIs. Appropriate therapeutic interventions are important to avoid affecting the patient's prognosis, and accurate diagnosis of IMH is essential for this purpose. The frequency of IMH varied according to the type of cancer and the drug used, and was significantly higher in patients with malignant melanoma and in patients given ipilimumab-nivolumab combination therapy.

Phase II clinical trial of gemcitabine plus oxaliplatin in patients with metastatic pancreatic adenocarcinoma with a family history of pancreatic/breast/ovarian/prostate cancer or personal history of breast/ovarian/prostate cancer (FABRIC study).

BACKGROUND: A family/personal history of breast, ovarian, or pancreatic cancer is a useful predictive marker for response to platinum-based chemotherapy in treating patients with pancreatic cancer. These cancers, and prostate cancer, are known as BRCA-related malignancies. We evaluated the efficacy of gemcitabine plus oxaliplatin (GEMOX) in patients with metastatic pancreatic cancer with a family/personal history of these cancers. METHODS: Chemotherapy-naïve patients with metastatic pancreatic cancer with a family history of pancreatic/breast/ovarian/prostate cancer or a personal history of breast/ovarian/prostate cancer were included. Patients received fixed dose-rate gemcitabine (1000 mg/m2) and oxaliplatin (100 mg/m2) every 2 weeks. The primary endpoint was 1-year survival, and the threshold and expected values were set at 30 and 50%, respectively. The target sample size was determined to be 43, with a one-sided alpha value of 5% and power of 80%. A total of 45 patients were enrolled. RESULTS: Among the first 43 enrolled patients, the 1-year survival rate was 27.9% [90% confidence interval (CI) 17.0-41.3], which did not meet the primary endpoint. Median overall survival, progression-free survival, and response rates were 7.6 months (95% CI 6.0-10.7), 4.0 months (95% CI 2.0-4.6), and 26.7% (95% CI 14.6-41.9), respectively, in all registered patients. The GEMOX regimen was generally tolerated; the most common grade three or higher adverse events were hematological toxicities. CONCLUSION: GEMOX did not show the expected efficacy in patients with metastatic pancreatic cancer with a family or personal history of pancreatic/breast/ovarian/prostate cancer. Selection of GEMOX based on family/personal history is not recommended. TRIAL REGISTRATION NUMBER: UMIN000017894.

Adapalene Gel 0.1% Versus Placebo as Prophylaxis for Anti-Epidermal Growth Factor Receptor-Induced Acne-Like Rash: A Randomized Left-Right Comparative Evaluation (APPEARANCE).

LESSONS LEARNED: The results of the APPEARANCE trial indicate that adapalene does not prevent acne-like rash over placebo when added to topical moisturizer and oral minocycline but instead may have a detrimental effect. Therefore, adapalene is not recommended as prophylaxis against acne-like rash induced by anti-epidermal growth factor receptor therapies.Given that acne-like rash was completely controlled with placebo in approximately half of patients, predictive measures to identify patients needing intensive prophylaxis are required. BACKGROUND: Anti-epidermal growth factor receptor (EGFR) therapies are frequently associated with acne-like rash. To evaluate the prophylactic efficacy of adapalene, a topical retinoid used as first-line therapy for acne vulgaris, we conducted a randomized, placebo-controlled, evaluator-blinded, left-right comparative trial. METHODS: Patients with non-small cell lung, colorectal, or head and neck cancer scheduled to receive anti-EGFR therapies were randomly assigned to once-daily adapalene application on one side of the face, with placebo on the other side. All patients had topical moisturizer coapplied to both sides of the face, and received oral minocycline. The primary endpoint was the difference in total facial lesion count of acne-like rash at 4 weeks. Secondary endpoints included complete control rate (CCR) of acne-like rash (≤5 facial lesions) and global skin assessment (Investigator's Global Assessment [IGA] scale, grade 0-4) at 4 weeks. Two blinded dermatologists independently evaluated the endpoints from photographs. RESULTS: A total of 36 patients were enrolled, of whom 26 were evaluable. Adapalene treatment was associated with a greater lesion count than placebo at 4 weeks, although the difference was not statistically significant (mean, 12.6 vs. 9.8, p = .12). All four patients with a difference >10 in lesion count between face sides had a greater count on the adapalene-treated side. No significant differences were observed in CCR of acne-like rash (54% vs. 50%) or IGA scale (mean grade, 1.9 vs. 1.7) between the adapalene and placebo sides. CONCLUSION: Adapalene is not recommended as prophylaxis against acne-like rash induced by anti-EGFR therapies.

Short-Term and Long-Term Outcomes of Infliximab and Tacrolimus Treatment for Moderate to Severe Ulcerative Colitis: Retrospective Observational Study.

BACKGROUND/AIMS: While some studies have shown that IFX and TAC exhibit similar efficacy against UC in the short-term, it is unclear which drug produces better long-term outcomes. In this study, we compared the long-term efficacy of IFX and TAC in patients with moderate to severe UC. METHODS: This retrospective study was conducted from 2009 to 2017. It included patients with no history of IFX or TAC treatment. We analyzed the clinical response and remission rates at 12 and 52 weeks, and colectomy-free and relapse-free survival were evaluated until the end of the study. RESULTS: At 12 weeks, 94.4% and 77.8% of the patients in the IFX group (n = 18) had demonstrated clinical responses and clinical remission, respectively, whereas 72.7% of the patients in the TAC group (n = 11) exhibited clinical responses and clinical remission. The clinical response, clinical remission, and colectomy-free rates did not differ significantly between the groups. At 52 weeks, clinical responses and clinical remission had been achieved in 76.5% and 70.6% of the patients both in the IFX group, respectively. In the TAC group, clinical responses and clinical remission were achieved in 50.0% of patients. Relapse-free and colectomy-free survival were estimated significantly better in IFX group evaluated by Kaplan-Meier curves. CONCLUSION: This study indicates that IFX and TAC produce similar short-term outcomes in UC patients, but IFX produces better long-term outcomes than TAC especially with avoidance of colectomy. Our data suggest that IFX therapy may be prioritized over TAC for the treatment of moderate to severe UC.

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.

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.

Constrictive pericarditis caused by a pericardial-occupying tumor due to esophageal cancer.

A 61-year-old female was admitted to our hospital for esophageal cancer treatment. Esophagectomy with 2-field lymphadenectomy was performed. Postoperative findings revealed the lesion was a poorly differentiated squamous cell carcinoma invading into the diaphragm and there were no carcinoma cells on the surgical margins. Eight months after surgery, a recurrence was suspected by the presence of tumors at the pericardia, right axillary lymph node and around the descending aorta. The patient was re-admitted for chemotherapy and administrated fluorouracil and cisplatin 4 days after admission. After 7 days, she complained of dysphagia. Esophagogastroduodenoscopy showed no abnormal lesion that could cause the symptom. Computed tomography revealed massive progression of the pericardial tumor, bilateral pleural effusion and congested liver. Echocardiography showed the diffuse pericardial tumor caused restriction of ventricular dilation and hemodynamics of constrictive pericarditis. The patient died 29 days after re-admission. Autopsy revealed squamous cell carcinoma involving the mediatinum and pericardium. The pericardium was completely full of cancer tissue but no fluid. We concluded that the direct cause of death was neoplastic constrictive pericarditis.

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.

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.

Insulin-induced GLUT4 movements in C2C12 myoblasts: evidence against a role of conventional kinesin motor proteins.

Insulin induces translocation of the glucose transporter GLUT4 from intracellular storage compartment to the plasma membrane via complex mechanisms that require intact cytoskeletal networks. In cultured adipocytes, conventional kinesin motor proteins have been proposed to mediate GLUT4 movements on microtubules. It remains, however, unclear whether kinesin motor system plays a similar regulatory role in myocytes. We addressed this issue using C2C12 myoblasts, which have now been shown to express both heavy and light chains of conventional kinesin. In these cells, overexpression of either wild-type kinesin light chain 2 (KLC2) or its phosphorylation-defective mutant did not significantly affect insulin-stimulated translocation of exofacial Myc-tagged GLUT4-green fluorescent protein to the cell surface and its subsequent externalization. Likewise, a dominant-negative mutant of KLC2 had no marked effect on GLUT4 movements in this cell type. These results suggest that conventional kinesin is dispensable for insulin-induced GLUT4 translocation in cultured myoblasts and may thus reveal a cell-type specific role of the microtubules-based cytoskeleton in glucose transport in response to insulin.

Dok1 mediates high-fat diet-induced adipocyte hypertrophy and obesity through modulation of PPAR-gamma 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)-gamma on Ser112. Mutation of this negative regulatory site for the transactivation activity of PPAR-gamma 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-gamma and may thus confer predisposition to diet-induced obesity.