Islet cell tumors of the pancreas: the medical oncologist's perspective

Mechanistic Insights into the N-Hydroxylations Catalyzed by the Binuclear Iron Domain of SznF Enzyme: Key Piece in the Synthesis of Streptozotocin

SznF, a member of the emerging family of heme-oxygenase-like (HO-like) di-iron oxidases and oxygenases, employs two distinct domains to catalyze the conversion of Nω-methyl-L-arginine (L-NMA) into N-nitroso-containing product, which can subsequently be transformed into streptozotocin. Using unrestricted density functional theory (UDFT) with the hybrid functional B3LYP, we have mechanistically investigated the two sequential hydroxylations of L-NMA catalyzed by SznF's binuclear iron central domain. Mechanism B primarily involves the O-O bond dissociation, forming Fe(IV)=O, induced by the H+/e- introduction to the FeA side of μ-1,2-peroxo-Fe2(III/III), the substrate hydrogen abstraction by Fe(IV)=O, and the hydroxyl rebound to the substrate N radical. The stochastic addition of H+/e- to the FeB side (mechanism C) can transition to mechanism B, thereby preventing enzyme deactivation. Two other competing mechanisms, involving the direct O-O bond dissociation (mechanism A) and the addition of H2O as a co-substrate (mechanism D), have been ruled out.

A Case of Pancreatic Neuroendocrine Tumor With Extensive Skeletal Metastases Detected on 68Ga-DOTANOC PET-CT

Neuroendocrine tumors (NETs) are a rather uncommon cause of chronic non-bloody diarrhea and are therefore often left undiagnosed for prolonged periods of time. In this case, a 46-year-old man was inappropriately treated with antibiotics for months by various doctors, and by the time the diagnosis of NET was made, the tumor had already metastasized to the entire skeleton. The patient refused surgery and was started on octreotide, which resolved his diarrhea.

Urea-based anticancer agents. Exploring 100-years of research with an eye to the future

Suramin was the first urea-based drug to be approved in clinic, and in the following century a number of milestone drugs based on this scaffold were developed. Indeed, urea soon became a privileged scaffold in medicinal chemistry for its capability to establish a peculiar network of drug−target interactions, for its physicochemical properties that are useful for tuning the druggability of the new chemical entities, and for its structural and synthetic versatility that opened the door to numerous drug design possibilities. In this review, we highlight the relevance of the urea moiety in the medicinal chemistry scenario of anticancer drugs with a special focus on the kinase inhibitors for which this scaffold represented and still represents a pivotal pharmacophoric feature. A general outlook on the approved drugs, recent patents, and current research in this field is herein provided, and the role of the urea moiety in the drug discovery process is discussed form a medicinal chemistry standpoint. We believe that the present review can benefit both academia and pharmaceutical companies’ medicinal chemists to prompt research towards new urea derivatives as anticancer agents.

Vasoactive intestinal peptide secreting tumour: An overview

Vasoactive intestinal peptide (VIP) secreting tumour (VIPoma) is a rare functional neuroendocrine tumour that typically arises from pancreatic islet cells. These present as sporadic, solitary pancreatic neoplasias with an estimated incidence of one in ten million individuals per year. Only around 5% of VIPomas are associated with multiple endocrine neoplasia type I syndrome. Excessive VIP secretion produces a clinical syndrome characterized by refractory watery diarrhoea, hypokalemia and metabolic acidosis. These coupled with elevated plasma levels of VIP are diagnostic. The majority of VIPomas are malignant and have already metastasized at the time of diagnosis (60%). Metastases occur most frequently in the liver, or regional lymph nodes, lungs, kidneys and bones. Some reports of skin metastases have been documented. Complete surgical resection continues to be the only potentially curative treatment. However, when the neoplasia cannot be excised completely, surgical debulking may provide palliative benefit. Other palliative options have included recently the peptide receptor radionuclide therapy which has shown to be effective and well-tolerated. This article will review all aspects of pancreatic VIPomas highlighting aspects such as clinical presentation, diagnosis and management.

Synthetic and biosynthetic routes to nitrogen-nitrogen bonds

The nitrogen-nitrogen bond is a core feature of diverse functional groups like hydrazines, nitrosamines, diazos, and pyrazoles. Such functional groups are found in >300 known natural products. Such N-N bond-containing functional groups are also found in significant percentage of clinical drugs. Therefore, there is wide interest in synthetic and enzymatic methods to form nitrogen-nitrogen bonds. In this review, we summarize synthetic and biosynthetic approaches to diverse nitrogen-nitrogen-bond-containing functional groups, with a focus on biosynthetic pathways and enzymes.

Pathogenic Mechanism of Autoimmune Diabetes Mellitus in Humans: Potential Role of Streptozotocin-Induced Selective Autoimmunity against Human Islet β-Cells

Human type 1 diabetes mellitus is a chronic autoimmune disease characterized by the selective loss of insulin-producing β-cells in pancreatic islets of genetically susceptible individuals. In this communication, a new hypothesis is postulated which is based on the observations that streptozotocin (STZ), a chemically reactive and cytotoxic compound produced by certain gram-positive bacteria, can be preferentially taken up into islet β-cells and induce cytotoxicity and autoimmunity. It is hypothesized that humans might be occasionally exposed to STZ through opportunistic infections with the STZ-producing bacteria and/or through ingestion of certain food products that contain STZ. In addition, the potential presence of the STZ-producing bacteria in the gut microbiota of some individuals might be another source of long-term STZ exposure. Because of the high chemical reactivity of STZ and its breakdown products, these chemicals can covalently modify certain cellular macromolecules (e.g., DNA and proteins), and the covalently modified cellular components would serve as new antigens, potentially capable of inducing both humoral and cellular autoimmune responses in the islets of certain individuals. In addition to STZ exposure, the eventual development of autoimmunity against STZ-exposed islet β-cells also depends critically on the genetic predisposition of the susceptible individuals plus the opportunistic presence of a conducive, strong environmental trigger, which often is presented as severe febrile viral infections subsequently inducing strong aberrant reactions of the body’s immune system. The proposed pathogenic hypothesis is supported by a considerable body of direct and indirect evidence from laboratory animal studies and clinical observations. Certainly, more experimental and clinical studies are needed to carefully further examine each of the key components of the proposed pathogenic hypothesis.

N-Nitrosation Mechanism Catalyzed by Non-heme Iron-Containing Enzyme SznF Involving Intramolecular Oxidative Rearrangement

The non-heme iron-dependent enzyme SznF catalyzes a critical N-nitrosation step during the N-nitrosourea pharmacophore biosynthesis in streptozotocin. The intramolecular oxidative rearrangement process is known to proceed at the Fe^II-containing active site in the cupin domain of SznF, but its mechanism has not been elucidated to date. In this study, based on the density functional theory calculations, a unique mechanism was proposed for the N-nitrosation reaction catalyzed by SznF in which a four-electron oxidation process is accomplished through a series of complicated electron transferring between the iron center and substrate to bypass the high-valent Fe^IV═O species. In the catalytic reaction pathway, the O₂ binds to the iron center and attacks on the substrate to form the peroxo bridge intermediate by obtaining two electrons from the substrate exclusively. Then, instead of cleaving the peroxo bridge, the C^ε-N^ω bond of the substrate is homolytically cleaved first to form a carbocation intermediate, which polarizes the peroxo bridge and promotes its heterolysis. After O-O bond cleavage, the following reaction steps proceed effortlessly so that the N-nitrosation is accomplished without NO exchange among reaction species.

Somatostatinoma and Neurofibromatosis Type 1-A Case Report and Review of the Literature

Somatostatinomas are rare neuroendocrine tumors (NET) that arise in the gastrointestinal (GI) tract. Because of their insidious growth, they are usually asymptomatic until late stages, presenting as malignant disease. We report the case of a 50-year-old woman who presented with epigastric abdominal pain, diarrhea and significant weight loss in the last two years. On clinical examination the patient met the criteria for neurofibromatosis type 1 (NF1). Abdominal CT and MRI revealed an infiltrative duodenal mass, with pancreatic invasion, locoregional enlarged lymph nodes and disseminated hepatic nodules. Microscopy and immunohistochemistry uncovered a neuroendocrine tumor, staining positive for chromogranin A (CgA), synaptophysin and somatostatin, with a Ki67 = 1%. Somatostatin receptors (SSTRs) type 2 were negative and SSTRs type 5 were positive in less than 50% of tumoral cells. Our patient was classified as a T3N1M1 stage IV metastatic duodenal grade 1 somatostatinoma and treatment with somatostatin analogues and chemotherapy with capecitabine and temozolomide was started, with so far abdominal imaging follow-up showing stable disease. When a patient is diagnosed with a rare NET, such as a somatostatinoma, it is of utmost importance to determine if it is a sporadic tumor or just a feature of a genetic disorder.

Synthesis of 18F-labeled streptozotocin derivatives and an in-vivo kinetics study using positron emission tomography

Glucose transporter 2 (GLUT2) is involved in glucose uptake by hepatocytes, pancreatic beta cells, and absorptive cells in the intestine and proximal tubules in the kidney. Pancreatic GLUT2 also plays an important role in the mechanism of glucose-stimulated insulin secretion. In this study, novel Fluorine-18-labeled streptozotocin (STZ) derivatives were synthesized to serve as glycoside analogs for in-vivo GLUT2 imaging. Fluorine was introduced to hexyl groups at the 3'-positions of the compounds, and we aimed to synthesize compounds that were more stable than STZ. The nitroso derivatives exhibited relatively good stability during purification and purity analysis after radiosynthesis. We then evaluated the compounds in PET imaging and ex-vivo biodistribution studies. We observed high levels of radioactivity in the liver and kidney, which indicated accumulation in these organs within 5 min of administration. In contrast, the denitroso derivatives accumulated only in the kidney and bladder shortly after administration. Compounds with nitroso groups are thus expected to accumulate in GLUT2-expressing organs, and the presence of a nitroso group is essential for in-vivo GLUT2 imaging.

Pancreatic neuroendocrine tumor: review of heterogeneous spectrum of CT appearance

OBJECTIVE

Pancreatic neuroendocrine tumors (PanNETs) are uncommon pancreatic neoplasms and can be a diagnostic challenge with heterogeneous spectrum of CT appearance. We review CT findings of PanNETs and other mimics.

CONCLUSION

PanNETs are typically hypervascular and have avid enhancement on arterial and venous phase images. However, dedicated pancreas protocol may be needed due to their sometimes atypical appearance including transient enhancement. Careful evaluation of CT findings will help differentiate PanNETs from their mimics, and can be used to establish the diagnosis of a PanNETs. Although an accurate diagnosis can be based on serological, urine, and CT scan findings, confirmation is made via pathological examination.

A Model for Human Islet Transplantation to Immunodeficient Streptozotocin-Induced Diabetic Mice

Streptozotocin (STZ) is a cytotoxic glucose analogue that causes beta cell death and is widely used to induce experimental diabetes in rodents. The sensitivity of beta cells to STZ is species-specific and human beta cells are resistant to STZ. In experimental islet transplantation to rodents, STZ-diabetes must be induced before transplantation to avoid destruction of grafted islets by STZ. In human islet transplantation, injection of STZ before transplantation is inconvenient and costly, since human islet availability depends on organ donation and frail STZ-diabetic mice must be kept for unpredictable lapses of time until a human islet preparation is available. Based on the high resistance of human beta cells to STZ, we have tested a new model for STZ-diabetes induction in which STZ is injected after human islet transplantation. Human and mouse islets were transplanted under the kidney capsule of athymic nude mice, and 10–14 days after transplantation mice were intraperitoneally injected with five consecutive daily doses of STZ or vehicle. Beta-cell death increased and beta-cell mass was reduced in mouse islet grafts after STZ injection. In contrast, in human islet grafts beta cell death and mass did not change after STZ injection. Mice transplanted with rodent islets developed hyperglycemia after STZ-injection. Mice transplanted with human islets remained normoglycemic and developed hyperglycemia when the graft was harvested. STZ had no detectable toxic effects on beta cell death, mass and function of human transplanted islets. We provide a new, more convenient and cost-saving model for human islet transplantation to STZ-diabetic recipients in which STZ is injected after islet transplantation.

Streptozotocin Impairs Proliferation and Differentiation of Adult Hippocampal Neural Stem Cells in Vitro-Correlation With Alterations in the Expression of Proteins Associated With the Insulin System

Rats intracerebroventricularily (icv) treated with streptozotocin (STZ), shown to generate an insulin resistant brain state, were used as an animal model for the sporadic form of Alzheimer’s disease (sAD). Previously, we showed in an in vivo study that 3 months after STZ icv treatment hippocampal adult neurogenesis (AN) is impaired. In the present study, we examined the effects of STZ on isolated adult hippocampal neural stem cells (NSCs) using an in vitro approach. We revealed that 2.5 mM STZ inhibits the proliferation of NSCs as indicated by reduced number and size of neurospheres as well as by less BrdU-immunoreactive NSCs. Double immunofluorescence stainings of NSCs already being triggered to start with their differentiation showed that STZ primarily impairs the generation of new neurons, but not of astrocytes. For revealing mechanisms possibly involved in mediating STZ effects we analyzed expression levels of insulin/glucose system-related molecules such as the glucose transporter (GLUT) 1 and 3, the insulin receptor (IR) and the insulin-like growth factor (IGF) 1 receptor. Applying quantitative Real time-PCR (qRT-PCR) and immunofluorescence stainings we showed that STZ exerts its strongest effects on GLUT3 expression, as GLUT3 mRNA levels were found to be reduced in NSCs, and less GLUT3-immunoreactive NSCs as well as differentiating cells were detected after STZ treatment. These findings suggest that cultured NSCs are a good model for developing new strategies to treat nerve cell loss in AD and other degenerative disorders.

Uptake of glucose-conjugated MGMT inhibitors in cancer cells: role of flippases and type IV P-type ATPases

The DNA repair protein O⁶-methylguanine-DNA-methyltransferase (MGMT) is a key determinant of cancer resistance. The MGMT inhibitors O⁶-benzylguanine (O⁶BG) and O⁶-(4-bromothenyl)guanine (O⁶BTG) failed to enhance the therapeutic response due to toxic side effects when applied in combination with alkylating chemotherapeutics, indicating a need of inhibitor targeting. We assessed MGMT targeting that relies on conjugating the inhibitors O⁶BG and O⁶BTG to ß-D-glucose, resulting in O⁶BG-Glu and O⁶BTG-Glu, respectively. This targeting strategy was selected by taking advantage of high demand of glucose in cancers. Contrary to our expectation, the uptake of O⁶BG-Glu and O⁶BTG-Glu was not dependent on glucose transporters. Instead, it seems that after membrane binding the conjugates are taken up via flippases, which normally transport phospholipids. This membrane binding is the consequence of the amphiphilic character of the conjugates, which at higher concentrations lead to the formation of micelle-like particles in aqueous solution. The unusual uptake mechanism of the conjugates highlights the importance of proper linker selection for a successful ligand-based drug delivery strategy. We also demonstrate that proteins of the P4-Type ATPase family are involved in the transport of the glucose conjugates. The findings are not only important for MGMT inhibitor targeting, but also for other amphiphilic drugs.

Comparison of the response using ICR mice derived from three different sources to multiple low-dose streptozotocin-induced diabetes mellitus

This study was conducted to compare the multiple low-dose streptozotocin (MLDS)-induced diabetic patterns of Korl:ICR, A:ICR, and B:ICR mice obtained from three different sources. Six-week-old male ICR mice were obtained from three difference sources. Korl:ICR mice were kindly provided by the National Institute of Food and Drug Safety Evaluation (NIFDS). The other two groups of ICR mice were purchased from different vendors located in the United States (A:ICR) and Japan (B:ICR). All ICR mice that received MLDS exhibited overt diabetic symptoms throughout the study, and the incidence and development of diabetes mellitus were similar among the three ICR groups. The diabetic mice exhibited hyperglycemia, loss of body weight gain, decreased plasma insulin levels, impaired glucose tolerance, decreased number of insulin-positive cells, and decreased size of β-cells in the pancreas. The diabetes symptoms increased as the blood glucose level increased in the three ICR groups. In particular, the level of blood glucose in the STZ-treated group was higher in Korl:ICR and A:ICR mice than in B:ICR mice. The plasma insulin levels, glucose tolerance, blood chemistry, and morphological appearance of the pancreas were very similar in the ICR groups obtained from the three different sources. In conclusion, our results suggest that Korl:ICR, A:ICR, and B:ICR mice from different sources had similar overall responses to multiple low-dose STZ to induce diabetes mellitus.

N-acetylcysteine treatment attenuates the cognitive impairment and synaptic plasticity loss induced by streptozotocin

Alzheimer's disease (AD) is a neurodegenerative disorder pathologically characterized by severe neuronal and glial structural changes and progressive cognitive decline. N-acetylcysteine (NAC) is a well-known pharmacological agent with pro-neurogenic properties and neuroprotective effects. In this study, we evaluated NAC protective effects on cognitive impairment and associated pathological markers in a streptozotocin (STZ)-induced sporadic dementia of AD type mice model. Animals were divided into six groups: I) Sham, II) NAC, III) physostigmine (PHY), IV) STZ, V) NAC + STZ and VI) PHY + NAC. NAC (5 mg/kg) and PHY (0.25 mg/kg) were administrated orally for 30 consecutive days and STZ (2.5 mg/kg) intracerebroventricularly at the first and third days. Novel object recognition (NOR, days 26-27) and Morris water maze (MWM, days 26-30) tasks were assessed to evaluate learning and memory. On the thirty-first day animals were euthanized and brains collected for biochemical analysis. Interestingly, our results showed that STZ treatment induced cognitive impairment in mice in the NOR and MWM tasks. Both NAC and PHY treatments prevented from this impairment. The increase in AChE activity and decrease in pTrkB and MnSOD levels caused by STZ in the cerebral cortex and hippocampus, were prevented by the NAC and PHY treatments. The decrease in SYN, MAP2 and GFAP expressions were also prevented by NAC and PHY treatments. In conclusion, NAC treatment prevented the cognitive impairment induced by STZ, normalizing the AChE activity and rescuing the synaptic plasticity loss. Our results suggest that NAC is a promising therapeutic strategy for the treatment of AD.

Cross sectional and nuclear medicine imaging of pancreatic insulinomas

Insulinomas are rare neuroendocrine tumors which occur predominantly in the pancreas. Although majority of the insulinomas are benign, over-secretion of insulin by the tumor leads to debilitating hypoglycemic symptoms. The diagnosis is based on clinical and biochemical findings. After the diagnosis is made, the principal challenge lies in locating the tumor because most tumors are solitary and small in size. Locating the tumor is of paramount importance as complete surgical excision is the only curative treatment, and incomplete resection leads to persistence of symptoms. Different preoperative and intraoperative imaging techniques have been used with varying success rates for the insulinoma imaging. Besides localizing the tumor, imaging also helps to guide biopsy, detect metastatic lesions, and perform image-guided therapeutic procedures. This review will discuss the role of different Cross sectional and nuclear medicine imaging modalities in insulinomas.

Design, Synthesis and in Vivo Evaluation of Novel Glycosylated Sulfonylureas as Antihyperglycemic Agents

Sulphonylurea compounds have versatile activities such as antidiabetic, diuretic, herbicide, oncolytic, antimalarial, antifungal and anticancer. The present study describes the design, synthesis and in vivo testing of novel glycosylated aryl sulfonylurea compounds as antihyperglycaemic agents in streptozocine-induced diabetic mice. The rational for the introduction of the glucosamine moiety is to enhance selective drug uptake by pancreatic β-cells in order to decrease the cardiotoxic side effect commonly associated with sulfonylurea agents. 2-Deoxy-2-(4-chlorophenylsulfonylurea)-d-glucopyranose was found to be the most potent antihyperglycaemic agents among the synthesized compounds in diabetic mice. This investigation indicates the importance of this novel class as potential antihyperglycaemic agents.

Successful pharmaceutical-grade streptozotocin (STZ)-induced hyperglycemia in a conscious tethered baboon (Papio hamadryas) model

BACKGROUND

Non-human primate (NHP) diabetic models using chemical ablation of β-cells with STZ have been achieved by several research groups. Chemotherapeutic STZ could lead to serious adverse events including nephrotoxicity, hepatotoxicity, and mortality.

METHODS

We implemented a comprehensive therapeutic strategy that included the tether system, permanent indwelling catheter implants, an aggressive hydration protocol, management for pain with IV nubain and anxiety with IV midazolam, moment-by-moment monitoring of glucose levels post-STZ administration, and continuous intravenous insulin therapy.

RESULTS

A triphasic response in blood glucose after STZ administration was fully characterized. A dangerous hypoglycemic phase was also detected in all baboons. Other significant findings were hyperglycemia associated with low levels of plasma leptin, insulin and C-peptide concentrations, hyperglucagonemia, and elevated non-esterified fatty acids (NEFA) concentrations.

CONCLUSIONS

We successfully induced frank diabetes by IV administering a single dose of pharmaceutical-grade STZ safely and without adverse events in conscious tethered baboons.

Insulinoma: a comprehensive summary of two cases

Pancreatic endocrine tumours are rare in occurrence. They may present with a baffling range of symptoms which pose a diagnostic dilemma. Two cases of pancreatic insulinoma are presented herewith. Both presented with neuro-psychiatric complaints and were treated symptomatically for depression, anxiety, seizures etc. The diagnosis in these patients was missed for years. Insulinoma being a great diagnostic challenge, requires reasonably high clinical suspicion, accurate biochemical diagnosis and radiological localization to avoid extensive surgery. The aim is to highlight the occurrence of this rare tumour at a tertiary care hospital.

Sporadic pancreatic vasoactive intestinal peptide-producing tumor (VIPoma) in a 47-year-old male

VIPoma is an exceedingly unusual neuroendocrine neoplasm that autonomously secretes vasoactive intestinal polypeptide (VIP). Its reported incidence is approximately 1 per 10 million individuals per year. Herein, we report the case of sporadic pancreatic VIPoma in a 47-year-old male who presented with a six-month history of chronic, plentiful, watery diarrhea. On physical examination, the patient looked sick, lethargic and had signs of dehydration. Laboratory investigations revealed high VIP hormone level (989pg/mL), hypokalemia, hypercalcemia, hyperglycemia, high blood urea nitrogen, high creatinine, and metabolic acidosis on arterial blood gas. Contrast-enhanced computed tomography (CT) scan showed a 3.1×3.3×4.7cm, well-defined, enhancing lesion involving the pancreatic tail with a cystic component. Moreover, a 5.7×6.1×6.8cm metastatic hepatic lesion was identified. The patient underwent distal pancreatectomy with splenectomy, hepatic lesion resection, and lymph node dissection. Histopathological and immunohistochemical examination of the pancreatic and hepatic lesions revealed neuroendocrine tumor (VIPoma). Postoperatively, the patient received radiofrequency ablation for the hepatic lesion. A post-operative six-month follow-up showed significant symptomatic relief, reduced VIP hormone level (71pg/mL) and normalized electrolyte and acid-base profiles. However, a magnetic resonance imaging (MRI) scan showed a small residual metastatic liver lesion which was considered for hepatic artery embolization (HAE). The patient is still alive with a residual hepatic disease at 18months. We also present a brief literature review on VIPoma.

Insulinoma: rare yet important

We report our experience with six cases of insulinoma that were managed at our hospital between 2009 and 2013. Four patients were women and two men, with mean age of 43 years and mean duration of symptoms before diagnosis of 5.7 years. Biochemical confirmation was made in all cases and preoperative localisation was successful in two cases only. In the other four, intraoperative localisation was made. Enucleation was performed in four patients and distal pancreatectomy in the other two. The tumour was proved benign in all patients by histopathology. Postoperatively, all patients were asymptomatic during a follow-up period ranging from 9 months to 4 years and both serum glucose and insulin were normal during that period. We think that careful preoperative workup and skilful surgical techniques can end the prolonged suffering of patients with insulinomas with excellent results.

Streptozotocin is equally diabetogenic whether administered to fed or fasted mice

Streptozotocin (STZ) is a selective pancreatic β cell toxin used to generate experimental hyperglycemia in rodent models. Several laboratory animal protocols suggest that STZ be administered to fasted rodents to minimize competition between STZ and glucose for low affinity GLUT2 transporters on β cells. However, whether the diabetogenic effects of multiple low dose (MLD)-STZ administration are enhanced by fasting has not been addressed. Given that repeated bouts of fasting can cause undue metabolic stress in mice, we compared the efficacy of MLD-STZ injections (50 mg/kg body weight daily for 5 days) to induce experimental hyperglycemia in both NOD/SCID/γchain(null) and C57BL/6J mice that were either ad libitum fed (STZ-Fed) or that had been fasted for 6 h (STZ-Fasted) prior to the time of STZ administration. Both STZ-Fed and STZ-Fasted mice had significantly worse glucose tolerance than vehicle-treated control mice 10 days after initiation of the MLD-STZ regimen. In C57BL/6J mice, fasting glucose levels, serum insulin levels, β cell mass, and glucose disposal during intraperitoneal glucose tolerance tests (IPGTTs) were indistinguishable between STZ-Fed and STZ-Fasted mice 20 days after MLD-STZ. The glucose intolerant phenotypes persisted for 20 weeks thereafter, irrespective of whether C57BL/6J mice were fed or fasted at the time of STZ injections. However, STZ-Fasted C57BL/6J mice experienced significant weight loss during the repeated bouts of fasting/re-feeding that were required to complete the MLD-STZ protocol. In summary, induction of experimental hyperglycemia can be achieved using the MLD-STZ protocol without repeated bouts of fasting, which have the potential to cause metabolic stress in laboratory mice.

Cost-effectiveness of gene-expression profiling for tumor-site origin

OBJECTIVES

Gene-expression profiling (GEP) reliably supplements traditional clinicopathological information on the tissue of origin (TOO) in metastatic or poorly differentiated cancer. A cost-effectiveness analysis of GEP TOO testing versus usual care was conducted from a US third-party payer perspective.

METHODS

Data on recommendation changes for chemotherapy, surgery, radiation therapy, blood tests, imaging investigations, and hospice care were obtained from a retrospective, observational study of patients whose physicians received GEP TOO test results. The effects of chemotherapy recommendation changes on survival were based on the results of trials cited in National Comprehensive Cancer Network and UpToDate guidelines. Drug and administration costs were based on average doses reported in National Comprehensive Cancer Network guidelines. Other unit costs came from Centers for Medicare & Medicaid Services fee schedules. Quality-of-life weights were obtained from literature. Bootstrap analysis estimated sample variability; probabilistic sensitivity analysis addressed parameter uncertainty.

RESULTS

Chemotherapy regimen recommendations consistent with guidelines for final tumor-site diagnoses increased significantly from 42% to 65% (net difference 23%; P<0.001). Projected overall survival increased from 15.9 to 19.5 months (mean difference 3.6 months; two-sided 95% confidence interval [CI] 3.2-3.9). The average increase in quality-adjusted life-months was 2.7 months (95% CI 1.5-4.3), and average third-party payer costs per patient increased by $10,360 (95% CI $2,982-$19,192). The cost per quality-adjusted life-year gained was $46,858 (95% CI $13,351-$104,269).

CONCLUSIONS

GEP TOO testing significantly altered clinical practice patterns and is projected to increase overall survival, quality-adjusted life-years, and costs, resulting in an expected cost per quality-adjusted life-year of less than $50,000.

Electrochemical analysis of antichemotherapeutic drug zanosar in pharmaceutical and biological samples by differential pulse polarography

The electrochemical reduction of zanosar was investigated systematically by direct current polarography, cyclic voltammetry, and differential pulse polarography (DPP). A simple DPP technique was proposed for the direct quantitative determination of anticancer drug zanosar in pharmaceutical formulation and spiked human urine samples for the first time. The reduction potential was -0.28 V versus Ag/AgCl with a hanging mercury drop electrode in Britton-Robinson buffer as supporting electrolyte. The dependence of the intensities of currents and potentials on pH, concentration, scan rate, deposition time, and nature of the supporting electrolyte was investigated. The calibration curve was found to be linear with the following equation: y = 0.4041x + 0.012, with a correlation coefficient of 0.992 (R (2)) over a concentration range from 1.0 × 10(-7) M to 1.0 × 10(-3) M. In the present investigation, the achieved limit of detection (LOD) and limit of quantization (LQD) were 7.42 × 10(-8) M and 2.47 × 10(-8) M; respectively. Excipients did not interfere with the determination of zanosar in pharmaceutical formulation and spiked urine samples. Precision and accuracy of the developed method were checked by recovery studies in pharmaceutical formulation and spiked human urine samples.

White rice vinegar improves pancreatic beta-cell function and fatty liver in streptozotocin-induced diabetic rats

Vinegar is a traditional remedy for ailments including diabetes. This study was conducted to investigate the beneficial effects of vinegar in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were orally administered with white rice vinegar (WRV, 2 ml/kg body weight per day, n = 6) or with an equal volume of drinking water (n = 6) for 1 month. Fasting and random blood glucose was measured from tail vein samples. Body weight, 24-h food and water intake were monitored 1 week and 1 month after STZ injection. Fasting serum insulin concentrations were assayed using ELISA. Pancreatic beta- and alpha-cell proportions were measured using immunofluorescence microscopy. Periodic acid Schiff staining was performed to access glycogen contents and histological changes in liver tissues. Compared with control animals, the WRV-treated rats had less weight loss, lower fasting and random blood glucose, higher fasting serum insulin and higher beta-cell proportion. The WRV treatment also improved fatty changes and glycogen storages in the liver of STZ rats. Oral intake of WRV improved fasting hyperglycemia and body weight loss through attenuating insulin deficiency, pancreatic beta-cell deficit, and hepatic glycogen depletion and fatty changes in STZ-induced diabetic rats.

Identification of links between small molecules and miRNAs in human cancers based on transcriptional responses

The use of small molecules to target miRNAs is a new type of therapy for human diseases, particularly cancers. We proposed a novel high-throughput approach to identify the biological links between small molecules and miRNAs in 23 different cancers and constructed the Small Molecule-MiRNA Network (SMirN) for each cancer to systematically analyze the properties of their associations. In each SMirN, we partitioned small molecules (miRNAs) into modules, in which small molecules (miRNAs) were connected with one miRNA (small molecule). Almost all of the miRNA modules comprised miRNAs that had similar target genes and functions or were members of the same miRNA family. Most of the small molecule modules involved compounds with similar chemical structures, modes of action, or drug interactions. These modules can be used to identify drug candidates and new indications for existing drugs. Therefore, our approach is valuable to drug discovery and cancer therapy.

A pilot phase II study of valproic acid for treatment of low-grade neuroendocrine carcinoma

INTRODUCTION

Notch1 has been shown to be a tumor suppressor in neuroendocrine tumors (NETs). Previous in vitro studies in NET cell lines have also suggested that valproic acid (VPA), a histone deacetylase inhibitor, can induce Notch1 and that Notch1 activation correlates with a decrease in tumor markers for NETs. Thus, this study aimed to evaluate the role of VPA in treating NETs and to determine whether VPA induced the Notch signaling pathway signaling in vivo.

PATIENTS AND METHODS

Eight patients with low-grade NETs (carcinoid and pancreatic) were treated with 500 mg of oral VPA twice a day with dosing adjusted to maintain a goal VPA level between 50 and 100 μg/mL. All patients were followed for 12 months or until disease progression.

RESULTS

Notch1 signaling was absent in all tumors prior to treatment and was upregulated with VPA. One patient had an unconfirmed partial response and was noted to have a 40-fold increase in Notch1 mRNA levels. Four patients had stable disease as best response. Tumor markers improved in 5 out of 7 patients. Overall, treatment with VPA was well tolerated.

CONCLUSION

. VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.

Metastatic insulinoma in a patient with type 2 diabetes mellitus: case report and review of the literature

Pancreatic neuroendocrine tumors (NETs) are extremely rare, and although insulinomas are the commonest, less than 10% of insulinomas are malignant. Most patients with insulinomas present with neuroglycopenic symptoms and weight gain attributable to insulin excess. Here, we report a case where a 67-year-old lady with a background history of type 2 diabetes mellitus and breakthrough hyperinsulinism who presented with coma. The biochemical profile revealed features typical of insulinoma, and CT and endosonography confirmed a pancreatic tumor with large volume right-sided liver metastases (biopsy confirming a neuroendocrine tumor). The patient underwent successful one-step RO surgical resection, distal pancreatectomy, splenectomy, and right hepatectomy, and 9 months postoperatively, she remains free of recurrent disease. She remains a diabetic.

Therapies for the medical management of persistent hypoglycaemia in two cases of inoperable malignant insulinoma

OBJECTIVE

Hypoglycaemia poses a significant management challenge in patients with unresectable functional malignant insulinoma. Novel agents such as mammalian target of rapamycin (mTOR) inhibitors and radiolabelled peptides may be effective where there is failure of conventional therapy.

DESIGN

We present the cases of two men diagnosed with inoperable malignant insulinoma and hepatic metastases who developed severe symptomatic hypoglycaemia, and review potential therapies for glycaemic support.

METHOD

Despite treatment with diazoxide, frequent oral carbohydrate, prednisolone and somatostatin analogue therapy, both men required hospital admission for treatment with continuous i.v. dextrose. Both were treated with Lutetium-177 octreotate. One man was also treated with everolimus, a mTOR inhibitor.

RESULT

Use of Lutetium-177 octreotate, and in one case everolimus, successfully achieved normoglycaemia, facilitating safe discharge from hospital. Both men also had regression in the size and number of hepatic metastases.

CONCLUSION

Lutetium-177 octreotate and everolimus are options for managing hypoglycaemia due to unresectable malignant insulinoma when refractory to conventional supportive therapies.

Identification of a novel Raf-1 pathway activator that inhibits gastrointestinal carcinoid cell growth

Carcinoids are neuroendocrine tumors (NET) that secrete hormones, including serotonin, resulting in the malignant carcinoid syndrome. In addition to the significant morbidity associated with the syndrome, carcinoids are frequently metastatic at diagnosis, and untreated mortality at 5 years exceeds 70%. Surgery is the only curative option, and the need for other therapies is clear. We have previously shown that activation of Raf-1 inhibits carcinoid cell proliferation. We investigated the ability of leflunomide (LFN), a Food and Drug Administration-approved medication for the treatment of rheumatoid arthritis, and its active metabolite teriflunomide (TFN) as a potential anti-NET treatment. LFN and TFN inhibit the in vitro proliferation of gastrointestinal carcinoid cells and induce G(2)-M phase arrest. Daily oral gavage of nude mice with subcutaneous xenografted carcinoid tumors confirms that LFN can inhibit NET growth in vivo. Treatment with TFN suppresses the cellular levels of serotonin and chromogranin A, a glycopeptide co-secreted with bioactive hormones. Additionally, TFN reduces the level of achaete-scute complex-like 1 (ASCL1), a NET marker correlated with survival. These effects are associated with the activation of the Raf-1/mitiogen-activated protein kinase kinase/extracellular signal-regulated kinase-1/2 pathway, and blockade of mitiogen-activated protein kinase kinase signaling reversed the effects of TFN on markers of the cell cycle and ASCL1 expression. In summary, LFN and TFN inhibit carcinoid cell proliferation in vitro and in vivo and alter the expression of NET markers. This compound thus represents an attractive target for further clinical investigation.

Radiofrequency ablation of solitary pancreatic insulinoma in a patient with episodes of severe hypoglycemia

Insulinomas are rare neuroendocrine tumors of the pancreas. Therapy of first choice is the surgical resection or enucleation. In cases of metastases or in patients with high surgical risk, medical therapy with diazoxide or octreotide is an alternative. In this case, we describe the successful use of computed tomography (CT)-guided radiofrequency ablation (RFA) of an insulinoma in an 80-year-old female patient. The patient suffered from episodes of severe nightly hypoglycemia with a minimal glucose concentration of 1.95 mmol/l (36 mg/dl). An insulinoma measuring 1.5 cm in diameter was localized by endoscopic ultrasound and CT scan in the tail of the pancreas. Owing to a high surgical risk caused by the patient's comorbidities and poor physical condition, the resection of the tumor was not considered. The medical treatment with diazoxide failed to control the symptoms of hypoglycemia sufficiently. Using CT-guided percutaneous RFA, the insulinoma was successfully ablated. No postinterventional complications occurred. During a 5-week follow-up, episodes of hypoglycemia were absent. A control-CT, 5 weeks after RFA, revealed no residual tumor. In conclusion, we found RFA suitable for the treatment of pancreatic insulinomas. Until more data concerning efficacy and complication rates have been collected; the procedure should be reserved for the treatment of patients who are no candidates for surgical therapy and in whom symptoms cannot be controlled by the medical therapy.

5-Fluorouracil treatment of problematic scars

BACKGROUND

Keloids and hypertrophic scars can be uncomfortable, disfiguring, and aesthetically undesirable. Anecdotal reports suggest that low-dose intralesional fluorouracil can be used to treat these undesirable scars.

METHODS

Using a prospective case series protocol, both keloid and hypertrophic scar patients were included. Keloid patients underwent excision followed by a series of treatments with intralesional 5-fluorouracil into the healing scar to prevent recurrence (n = 32). The hypertrophic scar patients were treated with the same series of injections without scar excision to both control symptoms and improve scar appearance (n = 21). The primary outcome measures were scar volume and a symptom questionnaire. Patients were followed for 1 year after completing the injection treatments.

RESULTS

In the keloid group, the recurrence rate was 19 percent at 1-year follow-up for this group of patients who had failed previous corticosteroid injection therapy. In the hypertrophic scar group, 14 percent did not respond to the series of injections. In this group, there was a median volume decrease of 50 percent maintained for 1 year after injection therapy was terminated.

CONCLUSIONS

Intralesional fluorouracil is a safe and effective means of controlling problem scars in terms of both recurrence and symptom control. Benefits were maintained for at least 1 year after completion of therapy. Intralesional 5-fluorouracil should be considered another option for patients suffering from problematic scars.

Preoperative detection of insulinomas: two case reports

Background

Insulinoma is the most common endocrine tumor of the pancreas. Accurate preoperative detection and localization of insulinomas is essential for the appropriate selection of candidates for surgery. We present two cases with benign pancreatic insulinoma.

Case presentation

Preoperative evaluation for patients with suspected insulinomas has been controversial. Endoscopic ultrasonography (EUS) has a sensitivity of 95% in well skilled operators and well tolerated preoperative imaging method.

Conclusion

We have detected the insulinomas with EUS before surgery in our patients but other imaging modalities did not help us for localization of them. Patients have been asymptomatic postoperatively with no hypoglycemia on repeat fasting. We reviewed here the different modalities for preoperative localization of insulinoma.

Chemical dissection of the link between streptozotocin, O-GlcNAc, and pancreatic cell death

Streptozotocin is a natural product that selectively kills insulin-secreting β cells, and is widely used to generate mouse models of diabetes or treat pancreatic tumors. Several studies suggest that streptozotocin toxicity stems from its N-nitrosourea moiety releasing nitric oxide and possessing DNA alkylating activity. However, it has also been proposed that streptozotocin induces apoptosis by inhibiting O-GlcNAcase, an enzyme that, together with O-GlcNAc transferase, is important for dynamic intracellular protein O-glycosylation. We have used galacto-streptozotocin to chemically dissect the link between O-GlcNAcase inhibition and apoptosis. Using X-ray crystallography, enzymology, and cell biological studies on an insulinoma cell line, we show that, whereas streptozotocin competitively inhibits O-GlcNAcase and induces apoptosis, its galacto-configured derivative no longer inhibits O-GlcNAcase, yet still induces apoptosis. This supports a general chemical poison mode of action for streptozotocin, suggesting the need for using more specific inhibitors to study protein O-GlcNAcylation.

Design of anticancer agents utilizing streptozocin for in silico optimization of properties and pattern recognition identification of group features

Streptozocin has been shown to be useful in the clinical treatment of malignant neuroendocrine tumors of the pancreas. The poor prognosis for patients having malignant tumors of pancreas suggests the investigation and development of new therapeutics. Nine analogs to streptozocin are determined by in silico physicochemical analysis and generation of structures by modeling from functional group isosteres. In these analogs is preserved the alkylating nitrosourea moiety, however, the covalently bonded substituent has significant hydrogen bonding sites and may include a ring structure. Analogs retain a broad range in lipophilicity, having a range of Log P from -2.798 (hydrophilic) to 3.001 (lipophilic). Standard deviation of molecular masses is only 12.6% of the group mean, so a small alteration in size occurs which is also reflected by only a 15.5% deviation in molecular volumes. Streptozocin and seven analogs show zero violations of the Rule of 5 which suggests favorable bioavailability. All compounds showed at least seven hydrogen bond acceptors with a strong positive correlation between hydrophilicity to the total number of hydrogen bond acceptors and donors. Analysis of similarity (ANOSIM) and discriminant analysis determined that streptozocin is highly similar to all nine analogs. However hierarchical cluster analysis and K-means cluster analysis were able to elucidate patterns of associations and differentiation among the ten compounds. This study demonstrates the efficacy of utilizing in silico optimization and pattern recognition to elucidate potential anticancer drugs.