Biogenesis of a novel compartment for autophagosome-mediated unconventional protein secretion

A novel membrane structure called CUPS is assembled during the secretion of unconventional cargo such as Acb1.

The endoplasmic reticulum (ER)–Golgi-independent, unconventional secretion of Acb1 requires many different proteins. They include proteins necessary for the formation of autophagosomes, proteins necessary for the fusion of membranes with the endosomes, proteins of the multivesicular body pathway, and the cell surface target membrane SNARE Sso1, thereby raising the question of what achieves the connection between these diverse proteins and Acb1 secretion. In the present study, we now report that, upon starvation in Saccharomyces cerevisiae, Grh1 is collected into unique membrane structures near Sec13-containing ER exit sites. Phosphatidylinositol 3 phosphate, the ESCRT (endosomal sorting complex required for transport) protein Vps23, and the autophagy-related proteins Atg8 and Atg9 are recruited to these Grh1-containing membranes, which lack components of the Golgi apparatus and the endosomes, and which we call a novel compartment for unconventional protein secretion (CUPS). We describe the cellular proteins required for the biogenesis of CUPS, which we believe is the sorting station for Acb1’s release from the cells.

Influence of somatostatin to biochemical parameters in patients with primary hyperparathyroidism

Somatostatin (SRIF) is effective in the nonoperative management of a variety endocrine tumors. A potential role of SRIF for treatment of patients with primary hyperparathyroidism (pHPT) has been suggested. In a controlled, prospective, triple-blinded, randomized clinical trial, the somatostatin analogue octreotide (SMS 201-995, Sandostatin) was evaluated in 40 patients with well documented pHPT. Amongst other biochemical parameters, serum calcium and-phosphate and levels of parathyroid hormone, calcitonin, and osteocalcin as well as octreotide were assessed before and for 4 hours after a single iv. application of 200 micrograms ocreotide or placebo. SRIF-receptor autoradiography was performed in parathyroid tissue samples. Baseline values revealed a constellation of biochemical parameters typically found in pHPT. Following 200 micrograms octreotide, no significant changes in any of the biochemical parameters investigated for were observed. Multivariate analysis was performed to identify patient subpopulations in which any given combination of laboratory parameters changed in response to either drug or placebo. However, no 'responders' to octreotide were identified. 45% of patients receiving octreotide, reported side effects. Parathyroid tissue samples were negative for SRIF-receptor expression. It is concluded that a single dose iv. application of octreotide does not result in appreciable changes of biochemical parameters relevant in pHPT and carries a high rate of side effects. Furthermore, absence of SRIF-receptors in parathyroid tissue from patients with pHPT, together with lack of octreotide effects, suggests that somatostatin-analogues may not be effective in the non-operative therapy of pHPT.

[Solid pseudopapillary pancreas tumors--often neglected]

Solid pseudopapillary tumors of the pancreas (SPTP) are rare tumors of the pancreas with low malignancy potential and a very good prognostic outcome after surgery. They typically occur in young women or adolescents and consist of solid, cystic and cystic-hemorrhagic components.Imaging findings in these tumors are characteristic and include a fibrotic capsule with a clear delineation and exhibit solid and cystic-hemorrhagic signal and density characteristics. Calcifications may be present in the periphery of the tumor. The tumor capsule shows contrast enhancement, the solid components in the periphery enhance in the early phase and gradually and inhomogeneously in late phases. MRI is superior to CT and other imaging modalities for characterization of SPTP. Awareness and knowledge of this tumor entity with an excellent prognosis is crucial to guide the patient towards effective, predominantly organ-sparing surgical treatment.

[Tumor-like lesion of the pancreas in chronic pancreatitis : imaging characteristics of computed tomography]

OBJECTIVE

The aim of this study was to describe the imaging findings for inflammatory pseudotumors in patients with chronic pancreatitis as detected in computed tomography (CT).

MATERIALS AND METHODS

In this retrospective study 20 patients with chronic pancreatitis were included, who underwent an abdominal CT scan. In all patients the diagnosis was confirmed by surgery and histopathology. Imaging findings which have previously been described as typical for chronic pancreatitis and for inflammatory pseudotumors were assessed by two radiologists in consensus. Values of tissue density (HU) at CT were measured within the lesions and in the surrounding pancreatic tissue.

RESULTS

In 90% of patients with histologically proven chronic pancreatitis, CT showed corresponding indicative findings. In 10 patients the resected specimen revealed an inflammatory pseudotumor, which was located in all cases within the pancreatic head. Using CT these 10 patients presented with calcifications within the lesion in 50% of the cases, an irregular dilatation of the main pancreatic duct in 90%, a "double duct sign" in 70%, an interrupted main pancreatic duct in the area of the lesion in 50%, a "duct penetrating sign" in 30%, an infiltration of adjacent structures in 10% and pathologically enlarged lymph nodes in 100% of the cases. In the venous contrasting phase six tumors were hypodense and four isodense compared to the surrounding pancreatic tissue. In six patients biphasic CT was performed and the mean difference in attenuation between inflammatory pseudotumors and surrounding parenchyma was significantly higher in the pancreatic phase than in the venous phase.

DISCUSSION

Differentiation between inflammatory pseudotumors and adenocarcinoma remains difficult or even impossible. Typical signs indicative of an adenocarcinoma of the pancreatic head, such as dilatation of the common bile duct and/or the main pancreatic duct as well as enlarged lymph nodes, were also found in patients with inflammatory pseudotumors. Inflammatory pseudotumors showed low contrast between lesions and parenchyma in the venous phase and calcifications within the solid part of the tumor.

Characterization of somatostatin receptor subtypes

Somatostatin regulates endocrine and exocrine secretion, possesses antiproliferative properties and acts as a neurotransmitter/neuromodulator in the central nervous system. These effects are mediated by G protein-coupled receptors, of which at least five types have been cloned (sstr1-5). In radioligand-binding studies we have compared the binding properties of sstr1-5 with their activities as somatostatin receptors. All receptors identified so far bind somatostatin-14 and somatostatin-28 with high affinity. The similarities in receptor sequence and in the binding profiles of short synthetic somatostastin analogues such as octreotide, MK 678 or RC 160 for sstr1-5 indicate the existence of two classes of receptors sstr1/sstr4 with virtually no or very low affinity and sstr2/sstr3/sstr5 with intermediate to high affinity for the short somatostatin analogues. All five receptors mediate inhibition of adenylyl cyclase; this inhibition is sensitive to pertussis toxin. In vitro and in vivo studies suggest the importance of sstr2 and/or sstr5 in the inhibition of growth hormone release. The sstr2 receptor is apparently the predominant subtype expressed in somatostatin receptor-positive tumours. Evidence exists for the importance of sstr5 receptors in insulin secretion and sstr1 receptors in oncology. Somatostatin receptor-selective agonists and antagonists will help to explore new therapeutic opportunities in oncology as well as in endocrine and gastrointestinal disorders and those of the central nervous system.

Immunological and clinical response after vaccination therapy of pancreatic carcinoma patients with autologous, tumor-lysate pulsed dendritic cells: Results of a phase II-study

4579

Background: Multiple studies in the experimental and in the clinical setting have shown that vaccine therapy using dendritic cells can induce antitumor immunity. Here, we report about the results of a phase II-study using autologous, tumor-lysate pulsed dendritic cells for the treatment of patients with advanced pancreatic carcinoma. Methods: Pancreatic carcinoma patients receiving abdominal surgery were included into to the study protocol. Tumor-lysate was derived by freeze-taw-cycles from surgically derived tissue specimens. Patients were eligible for DC vaccination after recurrence of pancreatic carcinoma or in a primarily palliative situation. DC were derived from PBMC according to a six-day protocol, loaded with tumor lysate and stimulated with TNF-a and PgE2. DC were applicated intracutaneously into the groin region every other week for three cycles, then monthly. All patients received standard chemotherapy with gemcitabine concomitantly. Immune response was controlled by DTH skin testing. Samples of non adherent cells were frozen for MLR and ELISPOT assays to monitor immune response ex vivo. Main study end point was partial or complete remission. Results: Ten patients have received dendritic cell vaccination so far. Of these, one patient developed a partial remission after a four-months course of vaccination therapy. Another patient showed stable disease after having received five vaccinations. Both patients showed immunological response. The patient with stable disease had a mean of 56 IFN-γ positive spots per 50E3 DC-stimulated non adherent cells prior to vaccination. After vaccination, this number increased to 191 spots per 50E3 cells (negative control: 5; positive control: 315). Both patients are alive 13 and 7 months after the start of vaccination therapy, respectively. Conclusions: Vaccination therapy with dendritic cells can be of clinical benefit in the setting of advanced pancreatic carcinoma. Clinical responses were associated with the induction of a stable immunological response.

No significant financial relationships to disclose.

[Use of a chlorhexidine-fuchsin solution for ear, nose and throat diseases]

Castellani's solution can no longer be used for medication due to the critical status of its ingredients. A solution of chlorhexidine and fuchsin is proposed as an alternative. This has good antimicrobial effectiveness and can be used in difficult cases of otitis externa solution for the treatment of cavities after mastoidectomy. The literature indicates that the use of this solution is admissible for selected cases in the field of ear, nose and throat diseases.

Preliminary results of a phase II-study: Vaccination therapy of pancreatic carcinoma patients with autologous, tumor lysate pulsed dendritic cells

14102

Background: Vaccination trials in the experimental and in the clinical setting have shown that it is possible to use dendritic cells (DC) to induce a specific antitumoral immune response. In this study, a protocol for the treatment of patients with metastasised pancreatic carcinoma with autologous, tumor-lysate pulsed dendritic cells was established. Methods: Patients with strong suspicion of pancreatic carcinoma receiving abdominal surgery are recruited to the study. Tumor-lysate is derived by freeze-taw-cycles from surgically derived tissue specimens. After recurrence of histologically verified pancreatic carcinoma or in a primarily palliative situation, patients are eligible for DC vaccination. DC are derived from PBMC according to a six-day protocol, loaded with tumor lysate and stimulated with TNF-alpha and PgE2. DC are applicated intracutaneously into the groin region three times in twice weekly cycles, then in monthly cycles. Immune response is controlled by DTH skin testing. Samples of non adherent cells are frozen for future MLR and ELISPOT assays. Main study end point is partial or complete remission four months after the start of vaccination. Alternative end points are adverse effects, quality of life, one-year survival and immuno-monitoring. Results: Tumor material of 49 patients has been worked up to tumor lysate and stored for future vaccinations. Four patients have received dendritic cell vaccination. Two of these patients have received their four months staging CT. In one case local disease was stable. The other patient showed progressive disease. A more pronounced proliferation of specific T cells compared to the control setting could be demonstrated by MLR assay. Discussion: A protocol for vaccination with tumor lysate pulsed dendritic cells of patients with pancreatic carcinoma has been established. Four patients have been vaccinated with dendritic cells according to a phase II study protocol. Vaccination was tolerated well. Because of a severe adverse reaction after the beginning of gemcitabine therapy, vaccination had to be omitted intercurrently with this patient. Results of most immuno monitoring assays are pending. One patient receiving DC vaccination therapy showed stable local disease.

No significant financial relationships to disclose.

Randomized phase II trial comparing gemcitabine/cisplatin-based chemoradiotherapy (CRT) to 5-FU-based CRT in patients with locally advanced pancreatic cancer

4038

Background: CRT is a relevant treatment option for patients with unresectable pancreatic cancer. Up to now, 5-FU has been the drug of choice for concurrent CRT. Based on evidence that also gemcitabine may improve the antitumor activity of radiation, a randomized phase II trial was undertaken. Methods: Patients with locally advanced, non-metastatic and histologically proven pancreatic cancer were included into a three-arm trial. In arm treatment arm A, radiation (CTV I up to 50.0 Gy, conventional fractionation) was applied concurrently with protracted venous infusion of 5-FU (350 mg/m2/irradiation day). In treatment arm B, patients received radiotherapy together with gemcitabine (300 mg/m2/d 30 minute infusion) and cisplatin (30 mg/m2/d 60 minute infusion) applied on days 1, 8, 22, and 29. In treatment arm C, patients received an identical regimen of CRT as described for arm B which was followed by 4 cycles of chemotherapy with gemcitabine (1000mg/m2, 30 min iv) plus cisplatin (50mg/m2) applied at 2-week intervals. Patients were stratified for Karnofsky performance status (KPS ≥80% vs. <80%). The primary end-point of the trial was the 9-months survival rate. Results: Ninety-six patients with a median age of 63.5 years (range 40–75 years) were included into the trial from 01/02 until 06/05 (arm A: 32 patients, arm B: 33 patients, arm C: 31 patients). Two patients did not complete CRT. At the time of evaluation, 66 patients (70.2%) had died. 9-months survival rate was 60%, 58%, and 46% in treatment arms A, B, and C, respectively. Median overall survival in arm A was 9.6 mo (95% CI, 8.7–10.5 mo), in arm B 9.6 mo (95%CI, 7.4–11.8 mo), and in arm C 6.1 mo (95% CI, 1.6–10 mo). Secondary end-points such as treatment-related toxicity, response rate, secondary resectability, and time to progression are under evaluation. Conclusions: CRT with gemcitabine plus cisplatin is not superior to 5-FU-based CRT with regard to the primary end-point of 9-months survival rate. Updated results will be presented at the meeting.

No significant financial relationships to disclose.

Regulation of CRH-induced secretion of ACTH and corticosterone by SOM230 in rats

OBJECTIVE

Adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome is biochemically characterized by increased plasma concentrations of ACTH inducing hypersecretion of cortisol. Somatostatin is known to inhibit ACTH secretion, and in vitro data have shown the inhibition of ACTH secretion by agonists activating sst2 and sst5 receptors. The present study aimed to determine the inhibitory effect of the multireceptor ligand SOM230, compared with the sst2-preferring agonist octreotide, on corticotropin-releasing hormone (CRH)-stimulated secretion of ACTH and corticosterone in rats.

METHODS

Secretion of ACTH and corticosterone was induced by i.v. application of CRH (0.5 microg/kg) in rats pretreated 1 h before by i.v. application of SOM230 (1, 3, or 10 microg/kg), octreotide (10 microg/kg) or NaCl 0.9%.

RESULTS

SOM230 (3 and 10 microg/kg) inhibited CRH-induced ACTH release by 45+/-3% and 51+/-2%, respectively, and corticosterone release by 43+/-5% and 27+/-16%, respectively. 10 microg/kg of octreotide tended to be less potent at inhibiting ACTH release (34+/-6% inhibition) and did not alter the secretion of corticosterone.

CONCLUSION

SOM230 has a stronger inhibitory effect on ACTH and corticosterone secretion than octreotide in rats. This difference can be explained by its higher affinity to sst1, sst3 and especially sst5 receptors compared with octreotide.

Medicinal chemistry of somatostatin analogs leading to the DTPA and DOTA conjugates of the multi-receptor-ligand SOM230

The somatostatin field has been a success story in terms of medicinal chemistry and drug discovery offering a variety of therapeutic opportunities. A rational medicinal chemistry approach capitalising on structure activity relationships has led to the discovery of SOM230, a novel, stable cyclohexapeptide somatostatin analog which exhibits multi-receptor binding to human somatostatin receptor (SSTR) subtypes (SSTR 1-5). Recently, we extended this research utilising the hydroxproline urethane extension of SOM230 for the attachment of the chelators DTPA and DOTA, which enable early diagnosis of SSTR positive tumors and radiotherapy.