A novel approach in the treatment of neuroendocrine gastrointestinal tumours. Targeting the epidermal growth factor receptor by gefitinib (ZD1839)

A single-center experience on endoscopic ultrasonography-guided ethanol ablation of insulinomas

BACKGROUND/OBJECTIVES

As the most frequent functional pancreatic neuroendocrine tumor, insulinomas may cause a plethora of symptoms and severe impairment in the living of patients by endogenous hyperinsulinemia and subsequent hypoglycemia. Surgery has been regarded as the first choice although a high risk of complications. Ethanol ablation is a promising non-surgical option that could achieve tumor shrinking in a short-term period. But the impact of symptom control and the long-term efficacy lack sufficient and good-quality evidence.

METHODS

A total number of 14 endoscopic ultrasonography-guided ethanol ablations were performed in 9 patients between September 2016 and September 2018 in Peking Union Medical College Hospital. The data were collected and prospectively analyzed.

RESULTS

The follow-up duration ranged from 21 to 1567 days in 9 patients, with a median of 994 days. 4 patients were free from relapse during a median follow-up of 1108 days (range: 994-1567 days). In 5 patients who suffered relapses, the median duration with symptom relief after the first ablation was 128 days (range: 13-393 days). If only repeated ablation was taken into consideration, the median duration with symptom relief was 26 days (range: 1-516 days). No complications happened during the procedures. The severe complication rate after the first ablation was 0.0% (0/9), compared to 7.14% (1/14) if each procedure was counted separately. The only severe complication documented was acute pancreatitis which was completely relieved after symptomatic treatment.

CONCLUSIONS

For patients who are not suitable for surgical resections, endoscopic ultrasonography-guided ethanol ablation of insulinomas could be an effective and safe alternative to relieve symptoms of hypoglycemia.

Efficacy and safety of anti-epidermal growth factor receptor agents for the treatment of oesophageal cancer: a systematic review and meta-analysis

OBJECTIVES

Despite remarkable advances in the treatment of oesophageal cancer (OC), the role of antiepidermal growth factor receptor (anti-EGFR) agents in treating OC remains controversial. Herein, a systematic review and meta-analysis were conducted to elucidate the efficacy and safety of anti-EGFR agents in patients with OC.

DESIGN

Meta-analysis of randomised controlled trials (RCTs) identified by searching the PubMed, Embase, Web of Science, ClinicalTrials.gov, Cochrane Library, Chinese Biology Medicine, China National Knowledge Infrastructure and Wanfang Data Knowledge Service Platform databases from inception to December 2019. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

SETTING

RCTs from any country and healthcare setting.

PARTICIPANTS

Patients with OC.

INTERVENTIONS

Combination therapy with anti-EGFR agents and conventional treatments versus conventional treatments alone in patients with OC.

PRIMARY AND SECONDARY OUTCOME MEASURES

Overall survival (OS) and progression-free survival (PFS) were primary outcome measures, and objective response rate (ORR), disease control rate (DCR) and treatment toxicities were secondary outcome measures.

RESULTS

In total, 25 RCTs comprising 3406 patients with OC were included. Overall, anti-EGFR treatment significantly improved the OS (HR: 0.81, 95% CI 0.74 to 0.89, p<0.00001), ORR (relative risk (RR): 1.33, 95% CI 1.16 to 1.52, p<0.0001) and DCR (RR: 1.22, 95% CI 1.11 to 1.34, p<0.0001) but not PFS (HR: 0.91, 95% CI 0.76 to 1.08, p=0.26). Anti-EGFR treatment was significantly associated with higher incidences of myelosuppression, diarrhoea, acne-like rash and hypomagnesaemia.

CONCLUSIONS

Overall, anti-EGFR agents have positive effects on OS, the ORR and DCR in OC. However, considering the high incidence of adverse effects, such as myelosuppression, diarrhoea, acne-like rashes and hypomagnesaemia, careful monitoring of patients with OC is recommended during anti-EGFR treatment.

TRIAL REGISTRATION NUMBER

CRD42020169230.

TRPC1 Inhibits Cell Proliferation/Invasion and Is Predictive of a Better Prognosis of Esophageal Squamous Cell Carcinoma

BACKGROUND AND OBJECTIVES

In China, over 90% of esophageal cancer (EC) cases are esophageal squamous cell carcinoma (ESCC). ESCC is a frequently malignant tumor with poor prognosis despite the development of comprehensive therapeutic strategies, for which there is still a lack of effective prognostic factors. Previous studies found that the abnormal expression of TRPC1 is closely related to the proliferation, invasion, metastasis, and differentiation of various tumors. However, the relationship between TRPC1 and ESCC is currently unclear. The present study aimed to clarify the clinical significance of TRPC1 and to preliminarily assess the molecular mechanism by which TRPC1 regulates cell proliferation, migration, and invasion in ESCC.

MATERIALS AND METHODS

Immunohistochemistry (IHC) was used to determine the expression of TRPC1 and Ki-67 in 165 cases of ESCC. The correlations between TRPC1 expression and clinicopathological characteristics were determined, and both univariate and multivariate analyses were utilized to quantify the impact of TRPC1 expression on patient survival. Cell Counting Kit-8, scratch wound healing, and transwell assays were used to determine the effects of TRPC1 on proliferation, migration, and invasion in ESCC in vitro, respectively.

RESULTS

The positive expression rate of TRPC1 showed significantly decreased in ESCC (45.50%) compared with the levels in normal esophageal mucosa (NEM; 80.80%) and high-grade intraepithelial neoplasia (HGIEN; 63.20%) (P<0.001). Higher expression rate of TRPC1 was associated with low lymph node metastasis (P<0.001), high differentiation (r_s = 0.232, P=0.003), and low Ki-67 (r_s = -0.492, P<0.001). We further revealed that low expression of TRPC1 was associated with poor prognosis (Disease-free survival, DFS: 95% CI=0.545-0.845, P=0.001; Overall survival, OS: 95% CI=0.553-0.891, P=0.004). Furthermore, we showed that downregulation of TRPC1 promoted the proliferation, migration, and invasion of human esophageal squamous cell carcinoma cell line EC9706 in vitro. In contrast, overexpression of TRPC1 inhibited the proliferation, migration, and invasion of human esophageal squamous cell carcinoma cell line KYSE150 (P<0.01), in a manner at least in part mediated through the AKT/p27 pathway.

CONCLUSION

TRPC1 inhibited the proliferation, migration, and invasion of EC9706 and KYSE150 cells, at least, in part mediated through the AKT/p27 pathway in vitro. The downregulation of TRPC1 may be one of the most important molecular events in the malignant progression of ESCC. TRPC1 could be a new candidate tumor suppressor gene and a new prognostic factor of ESCC.

Neuropilin-2 contributes to tumor progression in preclinical models of small intestinal neuroendocrine tumors

The identification of novel regulators of tumor progression is a key challenge to gain knowledge on the biology of small intestinal neuroendocrine tumors (SI-NETs). We recently identified the loss of the axon guidance protein semaphorin 3F as a protumoral event in SI-NETs. Interestingly the expression of its receptor neuropilin-2 (NRP-2) was still maintained. This study aimed at deciphering the potential role of NRP-2 as a contributor to SI-NET progression. The role of NRP-2 in SI-NET progression was addressed using an approach integrating human tissue and serum samples, cell lines and in vivo models. Data obtained from human SI-NET tissues showed that membranous NRP-2 expression is present in a majority of tumors, and is correlated with invasion, metastatic abilities, and neovascularization. In addition, NRP-2 soluble isoform was found elevated in serum samples from metastatic patients. In preclinical mouse models of NET progression, NRP-2 silencing led to a sustained antitumor effect, partly driven by the downregulation of VEGFR2. In contrast, its ectopic expression conferred a gain of aggressiveness, driven by the activation of various oncogenic signaling pathways. Lastly, NRP-2 inhibition led to a decrease of tumor cell viability, and sensitized to therapeutic agents. Overall, our results point out NRP-2 as a potential therapeutic target for SI-NETs, and will foster the development of innovative strategies targeting this receptor. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Analysis of radiation effects in two irradiated tumor spheroid models

Multicellular spheroids have proven suitable as three-dimensional in vivo-like models of non-vascularized micrometastases. Unlike monolayer-based models, spheroids mirror the cellular milieu and the pathophysiological gradients inside tumor nodules. However, there is limited knowledge of the radiation effects at the molecular level in spheroids of human origin. The present study is a presentation of selected cell biological processes that may easily be analyzed with methods available at routine pathology laboratories. Using gamma irradiated pancreatic neuroendocrine BON1 and colonic adenocarcinoma HCT116 spheroids as model systems, the present study assessed the radiobiological response in these models. Spheroid growth after irradiation was followed over time and molecular responses were subsequently assessed with immunohistochemistry (IHC) staining for descriptive analyses and semi-automatic grading of apoptosis, G₂-phase and senescence in thin sections of the spheroids. Growth studies demonstrated the BON1 spheroids were slower growing and less sensitive to radiation compared with the HCT116 spheroids. IHC staining for G₂-phase was primarily observed in the outer viable P-cell layers of the spheroids, with the 6 Gy irradiated HCT116 spheroids demonstrating a very clear increase in staining intensity compared with unirradiated spheroids. Apoptosis staining results indicated increased apoptosis with increasing radiation doses. No clear association between senescence and radiation exposure in the spheroids were observed. The present results demonstrate the feasibility of the use of multicellular spheroids of human origin in combination with IHC analyses to unravel radiobiological responses at a molecular level. The present findings inspire further investigations, including other relevant IHC-detectable molecular processes in time- and radiation dose-dependent settings.

Sprouting strategies and dead ends in anti-angiogenic targeting of NETs

Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms that arise from cells of the neuroendocrine system. NETs are characterized by being highly vascularized tumors that produce large amounts of proangiogenic factors. Due to their complexity and heterogeneity, progress in the development of successful therapeutic approaches has been limited. For instance, standard chemotherapy-based therapies have proven to be poorly selective for tumor cells and toxic for normal tissues. Considering the urge to develop an efficient therapy to treat NET patients, vascular targeting has been proposed as a new approach to block tumor growth. This review provides an update of the mechanisms regulating different components of vessels and their contribution to tumor progression in order to develop new therapeutic drugs. Following the description of classical anti-angiogenic therapies that target VEGF pathway, new angiogenic targets such as PDGFs, EGFs, FGFs and semaphorins are further explored. Based on recent research in the field, the combination of therapies that target multiple and different components of vessel formation would be the best approach to specifically target NETs and inhibit tumor growth.

Role of Somatostatin Analogues in the Treatment of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are rare epithelial neoplasms with neuroendocrine differentiation originating most commonly in the lungs and gastroenteropancreatic. Treatment includes surgery and other local therapies; treatment of inoperable disease centers around symptom management and control of tumor growth. Somatostatin analogues (SSAs) have been a mainstay of managing hormone-related symptoms. Emerging evidence suggests that they are effective therapies for tumor control also. Peptide receptor radionuclide therapy with radiolabeled SSAs is a new, promising treatment for inoperable or metastatic NETs. This article reviews the role of SSAs in the treatment of NETs.

p38MAPK and Chemotherapy: We Always Need to Hear Both Sides of the Story

The p38MAPK signaling pathway was initially described as a stress response mechanism. In fact, during previous decades, it was considered a pathway with little interest in oncology especially in comparison with other MAPKs such as ERK1/2, known to be target of oncogenes like Ras. However, its involvement in apoptotic cell death phenomena makes this signaling pathway more attractive for many cancer research laboratories. This apoptotic role allows to establish a link between p38MAPK and regular chemotherapeutic agents such as Cisplatin or base analogs (Cytarabine, Gemcitabine or 5-Fluorouracil) which are currently used in hospitals across the world. In fact, and more recently, p38MAPK has also been connected with targeted therapies like tyrosine kinase inhibitors (vg. Imatinib, Sorafenib) and, to a lesser extent, with monoclonal antibodies. In addition, the oncogenic or tumor suppressor potential of this signaling pathway has aroused the interest of the scientific community in evaluating p38MAPK as a novel target for cancer therapy. In this review, we will summarize the role of p38MAPK in chemotherapy as well as the potential that p38MAPK inhibition can bring to cancer therapy. All the evidences suggest that p38MAPK could be a double-edged sword and that the search for the most appropriate candidate patients, depending on their pathology and treatment, will lead to a more rational use of this new therapeutic tool.

Chemotherapy for advanced non-pancreatic well-differentiated neuroendocrine tumours of the gastrointestinal tract, a systematic review and meta-analysis: A lost cause?

BACKGROUND

Chemotherapy is well-established in the treatment of patients with well-differentiated neuroendocrine tumours (NETs) arising from the pancreas (pNETs); however, its role in patients with gastrointestinal non-pancreatic NETs (non-pNETs) is uncertain. This systematic review assesses the evidence for the role of chemotherapy in well-differentiated non-pNET patients.

METHODS

Eligible studies (identified using MEDLINE) were those reporting response and/or survival data for patients with well-differentiated non-pNETs receiving systemic chemotherapy. The primary end-point was overall-response (OR) rate; secondary end-points were progression-free survival (PFS), overall survival (OS), disease-stabilization (DS) and disease-control (DC) rates.

RESULTS

Of 6434 studies screened, 20 were eligible: one randomised phase III trial, 2 randomised phase II studies, 10 single-arm phase II trials and 7 retrospective analyses including a total of 264 patients (median of 11 patients per study, range 6-49); and employing multiple chemotherapy schedules. The mean "median PFS" and "median OS" were 16.9 months (95%-confidence interval (CI) 3.8-30.04) and 32.2 months (95%-CI 10.4-54.2), respectively. The non-weighted mean OR, DS and DC rates were 11.5% (95%-CI 5.8-17.2), 56.5% (95%-CI 38.1-74.9) and 70.7% (95%-CI 54.9-86.5), respectively. In studies including both pNETs and non-pNET patients, meta-analysis showed a lower OR-rate in the non-pNET patients when compared to pNETs [odds ratio (OR) 0.35 (95% CI 0.18-0.66)]; however significance was lost when high-risk bias studies were excluded in a sensitivity analysis [OR 0.45 (95% CI 0.19-1.07); p-value 0.07].

CONCLUSION

Studies were of evidence level-C with heterogeneous populations and treatments; and small patient numbers. Well-designed, prospective studies are needed to adequately evaluate the role of chemotherapy in this setting.

Molecular pathogenesis and targeted therapy of sporadic pancreatic neuroendocrine tumors

Over the past few years, knowledge regarding the molecular pathology of sporadic pancreatic neuroendocrine tumors (PNETs) has increased substantially, and a number of targeted agents have been tested in clinical trials in this tumor type. For some of these agents there is a strong biological rationale. Among them, the mammalian target of rapamycin inhibitor Everolimus and the antiangiogenic agent Sunitinib have both been approved for the treatment of PNETs. However, there is lack of knowledge regarding biomarkers able to predict their efficacy, and mechanisms of resistance. Other angiogenesis inhibitors, such as Pazopanib, inhibitors of Src, Hedgehog or of PI3K might all be useful in association or sequence with approved agents. On the other hand, the clinical significance, and potential for treatment of the most common mutations occurring in sporadic PNETs, in the MEN-1 gene and in ATRX and DAXX, remains uncertain. The present paper reviews the main molecular changes occurring in PNETs and how they might be linked with treatment options.

Gastrointestinal hormones stimulate growth of Foregut Neuroendocrine Tumors by transactivating the EGF receptor

Foregut neuroendocrine tumors [NETs] usually pursuit a benign course, but some show aggressive behavior. The treatment of patients with advanced NETs is marginally effective and new approaches are needed. In other tumors, transactivation of the EGF receptor (EGFR) by growth factors, gastrointestinal (GI) hormones and lipids can stimulate growth, which has led to new treatments. Recent studies show a direct correlation between NET malignancy and EGFR expression, EGFR inhibition decreases basal NET growth and an autocrine growth effect exerted by GI hormones, for some NETs. To determine if GI hormones can stimulate NET growth by inducing transactivation of EGFR, we examined the ability of EGF, TGFα and various GI hormones to stimulate growth of the human foregut carcinoid,BON, the somatostatinoma QGP-1 and the rat islet tumor,Rin-14B-cell lines. The EGFR tyrosine-kinase inhibitor, AG1478 strongly inhibited EGF and the GI hormones stimulated cell growth, both in BON and QGP-1 cells. In all the three neuroendocrine cell lines studied, we found EGF, TGFα and the other growth-stimulating GI hormones increased Tyr(1068) EGFR phosphorylation. In BON cells, both the GI hormones neurotensin and a bombesin analogue caused a time- and dose-dependent increase in EGFR phosphorylation, which was strongly inhibited by AG1478. Moreover, we found this stimulated phosphorylation was dependent on Src kinases, PKCs, matrix metalloproteinase activation and the generation of reactive oxygen species. These results raise the possibility that disruption of this signaling cascade by either EGFR inhibition alone or combined with receptor antagonists may be a novel therapeutic approach for treatment of foregut NETs/PETs.

Translation of molecular pathways into clinical trials of neuroendocrine tumors

Current treatment options for neuroendocrine tumors (NET) include somatostatin analogs, interferon-α, peptide receptor-targeted therapy and cytotoxic chemotherapy. Most patients undergo sequential therapies since these drugs are active only in subpopulations of patients and for a limited period of time. There is a need for novel drugs that are capable of amelioration of symptomatology (syndromic control) and/or tumor growth control. A number of diverse signaling pathways are involved in the pathogenesis of NET and tumor growth, thus many potential targets are available for drug targeting. Targeted therapies therefore represent an appropriate developmental therapeutic strategy given the multiplicity of potential targets in NET. These include but are not limited to: inhibitory or activating G protein-coupled receptors, receptor tyrosine kinases, ligands, and intracellular targets such as the mammalian target of rapamycin (mTOR). Numerous drugs that utilize single or multiple targets are currently in clinical development. Recently, two target-directed agents, the multiple tyrosine kinase inhibitor sunitinib and the mTOR inhibitor everolimus, have been approved for the treatment of progressive pancreatic NET. This review provides a broad overview of established and potential molecular targets in NET, summarizes data from phase II and III clinical trials with targeted drugs and outlines future therapeutic directions.

New drugs in the therapy of neuroendocrine tumors

Neuroendocrine tumors (NET) are a rare and heterogeneous group of neoplasms of a relatively indolent nature whose incidence and prevalence are increasing. Despite the advances made in the field of NET over the past years, these tumors eventually progress to metastatic disease in most of the patients, with a fatal outcome in the majority. Traditional cytotoxic agents remain of limited efficacy; however, recently, a better understanding of molecular pathways has provided clues to potential molecular targets for new therapeutic strategies. Somatostatin analogs are well known to be useful for the control of symptoms in functioning tumors, and it was recently demonstrated that they can inhibit tumor progression in certain disease settings. Moreover, the recently published randomized trials with the multi-TKI sunitinib and with the mTOR-inhibitor everolimus have demonstrated, for the first time, their ability to positively impact the natural history of pancreatic NET (PNET). In this short review, we will discuss available data on newer molecular targeted agents for the treatment of advanced well-differentiated gastro-entero- pancreatic NET (GEP-NET). A possible algorithm for the use of these treatments in the context of the extreme heterogeneity of GEP-NET presentation will be proposed.

Array-based pharmacogenomics of molecular-targeted therapies in oncology

The advent of microarrays over the past decade has transformed the way genome-wide studies are designed and conducted, leading to an unprecedented speed of acquisition and amount of new knowledge. Microarray data have led to the identification of molecular subclasses of solid tumors characterized by distinct oncogenic pathways, as well as the development of multigene prognostic or predictive models equivalent or superior to those of established clinical parameters. In the field of molecular-targeted therapy for cancer, in particular, the application of array-based methodologies has enabled the identification of molecular targets with 'key' roles in neoplastic transformation or tumor progression and the subsequent development of targeted agents, which are most likely to be active in the specific molecular setting. Herein, we present a summary of the main applications of whole-genome expression microarrays in the field of molecular-targeted therapies for solid tumors and we discuss their potential in the clinical setting. An emphasis is given on deciphering the molecular mechanisms of drug action, identifying novel therapeutic targets and suitable agents to target them with, and discovering molecular markers/signatures that predict response to therapy or optimal drug dose for each patient.

The role of cell lines in the study of neuroendocrine tumors

Cell lines originating from neuroendocrine tumors (NETs) represent useful experimental models to assess the control of synthesis and release of different hormones and hormone-like peptides, to evaluate the mechanisms of action of these agents in target tissues at the cellular and subcellular levels, and to study cell proliferation and tumor development, as well as the effect of different drugs on these complex processes. To date, the understanding of NET biology (with regard to their mechanisms of hormone secretion, cell proliferation and metastatic spread) has been hampered by the lack of appropriate animal models or cell lines for their study. In the present review, we aim to summarize the recent in vitro/in vivo data regarding cell lines derived from NETs which are most frequently employed in experimental neuroendocrinology.

Ghrelin in neuroendocrine tumors

Ghrelin is a 28 amino acid peptide, primarily produced by the oxyntic mucosa X/A like neuroendocrine cells in the stomach. It is also found in the small intestine, hypothalamus, pituitary gland, pancreas, heart, adipose tissue, and immune system. In gastrointestinal neuroendocrine tumors (NETs) ghrelin release has been well documented. Ghrelin is a brain-gut circuit peptide with an important role in the physiological regulation of appetite, response to hunger and starvation, metabolic and endocrine functions as energy expenditure, gastric motility and acid secretion, insulin secretion and glucose homeostasis, as well as in the potential connection to the central nervous system. Recently, there has been a significant interest in the biological effects of ghrelin in NETs. In this article, we present a comprehensive review of ghrelin's expression and a brief summary of ghrelin's physiological role in NETs patients with carcinoids, type A chronic atrophic gastritis (CAG), with or without MEN-1, and with and without liver metastases. We hope, with the research reviewed here, to offer compelling evidence of the potential significance of ghrelin in NETs, as well as to provide a useful guide to the future work in this area.

Emerging therapies for advanced gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors comprise a heterogeneous group of neoplasms derived from peptide- and amine-producing cells of the neuroendocrine system. Gastroenteropancreatic NET are differentiated into tumors and carcinomas based on their malignant potential and subdivided into those arising from the pancreas (islet cell tumors or pancreatic NET) and the more classical gut "carcinoids". Moderate to well differentiated NET have historically been considered rare tumors but recent epidemiological statistics suggest that their frequency has increased substantially over the past three decades. While the incidence of NET is increasing, data from both the US and UK demonstrate no improvement in outcomes over a similar time period. Due to the generally indolent biology of NET, most patients present with advanced disease before symptoms become apparent. In patients with localized NET, the 5-year survival rates after resection range from 60 to 90%, while regional lymph node involvement decreases the 5-year survival rates after surgery to 50-75%. Patients with distant metastases have a 5 year survival rate of approximately 25-40%. Conventional cytotoxic chemotherapy is of unclear benefit in patients with these generally slow growing tumors. Multiple agents have been tested in Phase 2 and Phase 3 trials. In general, the lack of major objective responses with significant toxicities has limited routine use of traditional chemotherapy agents and has emphasized the need to develop new agents in these diseases. This review will focus on emerging molecularly-targeted treatments with an emphasis on their underlying biologic and preclinical rationale.

Pancreatic endocrine tumors: a report on a patient treated with sorafenib

A 31-yr-old man with abdominal pain was diagnosed with a pancreatic endocrine tumor and multiple hepatic metastases. Despite optimal treatment with interferon alpha, a somatostatin analog, local therapy with high-intensity focused ultrasound ablation for multiple hepatic metastases, and multiple lines of chemotherapy with etoposide/cisplatin combination chemotherapy and gemcitabine monotherapy, the tumor progressed. As few chemotherapeutic options were available for him, sorafenib (800 mg/day, daily) was administered as a salvage regimen. Sorafenib was continued despite two episodes of grade 3 skin toxicity; it delayed tumor progression compared to the previous immunotherapy and chemotherapy. Serial computed tomography scans showed that the primary and metastatic tumors were stable. Thirteen months after beginning targeted therapy, and up to the time of this report, the patient is well without disease progression. We suggest that sorafenib is effective against pancreatic endocrine tumors.

Current surgical management of pancreatic endocrine tumor liver metastases

BACKGROUND

The management of metastatic disease in pancreatic endocrine tumors (PETs) demands a multidisciplinary approach and the cooperation of several medical specialties. The role of surgery is critical, even when a radical excision cannot always be achieved.

DATA SOURCES

A PubMed search of relevant articles published up to February 2011 was performed to identify current information about PET liver metastases regarding diagnosis and management, with an emphasis on surgery.

RESULTS

The early diagnosis of metastases and their accurate localization, most commonly in the liver, is very important. Surgical options include radical excision, and palliative excision to relieve symptoms in case of failure of medical treatment. The goal of the radical excision is to remove the primary tumor bulk and all liver metastases at the same time, but unfortunately it is not feasible in most cases. Palliative excisions include aggressive tumor debulking surgeries in well-differentiated carcinomas, trying to remove at least 90% of the tumor mass, combined with other additional destructive techniques such as hepatic artery embolization or chemoembolization to treat metastases or chemoembolization to relieve symptoms in cases of rapidly growing tumors. The combination of chemoembolization and systemic chemotherapy results in better response and survival rates. Other local destructive techniques include ethanol injection, cryotherapy and radiofrequency ablation.

CONCLUSION

It seems that the current management of PETs can achieve important improvements, even in advanced cases.

From targets to treatments: a review of molecular targets in pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pancreatic NET) are relatively rare, slowly growing tumors, although their incidence is increasing, and patients may survive for several years with metastatic disease. Apart from symptomatic relief, there have been few treatment options for these tumors in the past. More recently, investigators have explored the potential of molecularly targeted agents in treating pancreatic NET, with some success. In this review, we consider the data supporting exploitation of different targets in pancreatic NET, including peptide receptors, receptor tyrosine kinases (involved in tumor angiogenesis and more directly supporting tumor growth), and intracellular targets, such as the mammalian target of rapamycin (mTOR), which has a central role in regulating cell growth, metabolism, and apoptosis. Probably due to the paucity of pancreatic NET, many clinical trials to date have included heterogeneous NET populations, and there are few randomized studies of this specific patient population. Very recently, promising results have been achieved in placebo-controlled, phase III trials with the multitargeted tyrosine kinase inhibitor, sunitinib, and the mTOR inhibitor, everolimus. These agents have been approved or are currently being reviewed by authorities for use in patients with pancreatic NET. Here we review potential molecular targets in pancreatic NET and summarize the available data for targeted agents from phase II and III trials open to patients with this tumor.

Pancreatic islet cell carcinoma presenting with concurrent Cushing's and Zollinger-Ellison syndromes: case series and literature review

Cushing's syndrome and Zollinger-Ellison syndrome occur occasionally as a result of neuroendocrine cancers. The concurrence of the two syndromes has been considered to confer a poor clinical and therapeutic outcome. In this study, we are reviewing two patients with pancreatic islet cell carcinomas and with both Zollinger-Ellison and Cushing's syndromes, one followed up for more than 5 years, and the other still receiving therapy, 5 years since diagnosis. A literature review showed that surgery has limited utility as the majority of these patients had metastases at the time of diagnosis. Proton-pump inhibitors, ketoconazole, and somatostatin antagonists have a major role in controlling symptoms. Interferon and systemic chemotherapeutic agents play a role in the management of metastatic and fast-growing cases. Chemoembolization and bland embolization show encouraging results in controlling liver metastases. The latter was used effectively and more than once in the two patients presented herein. On the basis of recent molecular genetics studies, target therapy may be helpful, however, ongoing trials will define it's utility. As the data confers a worse prognosis versus other pancreatic neuroendocrine tumors, the relatively favorable outcome of the two patients reported herein may reflect the impact of multiple therapeutic modalities.

PACAP induces signaling and stimulation of 5-hydroxytryptamine release and growth in neuroendocrine tumor cells

Neuroendocrine tumors, although rare, are currently diagnosed with increasing frequency, owing to improved imaging techniques and a greater clinical awareness of this condition. To date, BON is a very well established and characterized human pancreatic neuroendocrine tumor cell line used to study the signal transduction and genetic regulation of neuroendocrine tumors secretion and growth. The secretory activity of BON cells is known to release peptides, such as chromogranin A, neurotensin, and biogenic amines, as 5-HT, permitting an assessment of their biological activity. The neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP), released from the enteric neurons in the gastrointestinal tract by binding to its high affinity receptor PAC1, has been previously shown to regulate the secretory activity and growth of the neuroendocrine-derived enterochromaffin-like cells in the stomach. This led us to speculate that PACAP might also play an important role in regulating the growth of human neuroendocrine tumors. Accordingly, in the current study, we have shown that BON cells express PAC1 receptors, which are rapidly internalized upon PACAP activation. Furthermore, PAC1 receptor activation, in BON cells, couple to intracellular Ca(2+) as well as cAMP responses and induce the release of intracellular 5-HT, activate mitogen activated protein kinases, and stimulate cellular growth. These data indicate that PACAP functionally can stimulate 5-HT release and promote the growth of the BON neuroendocrine tumor cell line. Therefore, PACAP and its receptors regulate neuroendocrine tumor secretory activity and growth in vivo, and this knowledge will permit the development of novel diagnostic and therapeutic targets for managing neuroendocrine tumors in humans.

Treatment of endocrine pancreatic tumors

Endocrine pancreatic tumors are rare with an incidence of 4 per million inhabitants. Most tumors are malignant except for insulinomas that usually are benign. They are slowly growing in the majority of cases but there are exceptions with rapidly progressing malignant carcinomas. Because of the rarity of these tumors large randomized trials are difficult to accomplish. However, most physicians treating these patients agree that surgery should be considered in all cases and that medical treatment with chemotherapy and biotherapy is well established for this group of patients.

Dual knockdown of N-ras and epiregulin synergistically suppressed the growth of human hepatoma cells

Hepatocellular carcinoma (HCC) is a major challenge because of its resistance to conventional cytotoxic chemotherapy and radiotherapy. Multi-targeted therapy might be a new option for HCC treatment. Our previous study showed that N-ras gene was activated in HCC and was inhibited by RNA interference. In the present study, we investigated the alternation of gene expression by microarray in N-Ras-siRNA-treated HepG2 cells. The results revealed that the EREG gene, encoding epiregulin, was dramatically up-regulated in response to silence of N-ras. We speculated that the up-regulation of epiregulin was involved in the compensatory mechanism of N-ras knockdown for cell growth. Therefore, we evaluated whether dual silence of N-ras and epiregulin display a greater suppression of cell growth. The results confirmed that dual knockdown of N-ras and epiregulin synergistically inhibited cell growth. Our results also showed that dual knockdown of N-ras and epiregulin significantly induced cell arrest at G0/G1 phase. Furthermore, Western blot assay showed that dual knockdown of N-ras and epiregulin markedly reduced the phosphorylations of ERK1/2, Akt and Rb, and inhibited the expression of cyclin D1. Our findings imply that multi-targeted silence of oncogenes might be an effective treatment for HCC.

Expression pattern and functional relevance of epidermal growth factor receptor and cyclooxygenase-2: novel chemotherapeutic targets in pancreatic endocrine tumors?

OBJECTIVES

Pancreatic endocrine tumors represent morphologically and biologically heterogeneous neoplasms. Well-differentiated endocrine tumors (benign or of uncertain behavior) can be distinguished from well-differentiated and poorly differentiated endocrine carcinomas. Although many well-differentiated endocrine carcinomas show rather low rates of tumor growth, more than two-thirds of pancreatic endocrine carcinomas display distant metastases at the time of diagnosis. As the currently applied therapies beyond surgery only achieve partial or complete response rates of approximately 15%, additional chemotherapeutic targets are needed, especially in the therapy of inoperable and progressive pancreatic endocrine carcinomas.

METHODS

The expression of epidermal growth factor receptor (EGFR) and cyclooxygenase (COX)-2 were investigated in 110 clinically and pathomorphologically well-characterized pancreatic endocrine tumors, using immunohistochemistry and immunoblot analyses. Functional tests were performed using the human pancreas carcinoid cell line BON and the mouse insulinoma cell line beta-TC-3.

RESULTS

The expression of EGFR correlated significantly with the grade of malignancy, increasing from low rates of expression in benign tumors and tumors of uncertain behavior to high rates of expression in well- and poorly differentiated endocrine carcinomas. The expression of COX-2 was independent of the malignant potential, but was more frequently expressed in primary tumors than in metastases. The treatment of the human pancreas carcinoid cell line BON and the mouse insulinoma cell line beta-TC-3 with EGFR and COX-2 inhibitors (monotherapy and combined therapy) resulted in a significant, dose-dependent reduction of cell viability coupled with increased apoptosis.

CONCLUSIONS

Our results suggest that EGFR and COX-2 may represent useful additional chemotherapeutic targets in pancreatic endocrine tumors.

Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) have long fascinated clinicians and investigators despite their relative rarity. Their clinical presentation varies depending on whether the tumor is functional or not, and also according to the specific hormonal syndrome produced. Tumors may be sporadic or inherited, but little is known about their molecular pathology, especially the sporadic forms. Chromogranin A appears to be the most useful serum marker for diagnosis, staging, and monitoring. Initially, therapy should be directed at the hormonal syndrome because this has the major initial impact on the patient's health. Most PETs are relatively indolent but ultimately malignant, except for insulinomas, which predominantly are benign. Surgery is the only modality that offers the possibility of cure, although it generally is noncurative in patients with Zollinger-Ellison syndrome or nonfunctional PETs with multiple endocrine neoplasia-type 1. Preoperative staging of disease extent is necessary to determine the likelihood of complete resection although debulking surgery often is believed to be useful in patients with unresectable tumors. Once metastatic, biotherapy is usually the first modality used because it generally is well tolerated. Systemic or regional therapies generally are reserved until symptoms occur or tumor growth is rapid. Recently, a number of newer agents, as well as receptor-directed radiotherapy, are being evaluated for patients with advanced disease. This review addresses a number of recent advances regarding the molecular pathology, diagnosis, localization, and management of PETs including discussion of peptide-receptor radionuclide therapy and other novel antitumor approaches. We conclude with a discussion of future directions and unsettled problems in the field.

An epidermal growth factor inhibitor, Gefitinib, induces apoptosis through a p53-dependent upregulation of pro-apoptotic molecules and downregulation of anti-apoptotic molecules in human lung adenocarcinoma A549 cells

A selective epidermal growth factor receptor inhibitor, Gefitinib, has been clinically demonstrated to be effective for certain cancer cell types including lung cancer. Our previous study indicated that Gefitinib induced Fas/caspase-dependent apoptosis in human lung adenocarcinoma A549 cells. However, the pathway relaying the signals of Gefitinib-induced cell death has not been fully elucidated. Loss of normal function of p53 facilitates the development of neoplastic lesions and possibly contributes to the development of resistance to chemotherapy. Thus, the current study was designed to examine the role of p53 in Gefitinib-induced apoptosis. Incubation of human lung adenocarcinoma A549 cells with 25 microM Gefitinib resulted in phosphorylation and activation of p53 such as enhanced DNA binding activity, which was accompanied by the upregulation of PUMA (p53 upregulated modulator of apoptosis) and Fas, and downregulation of survivin and XIAP (X-linked inhibitor of apoptosis protein). The Gefitinib-mediated Fas, PUMA, survivin, XIAP regulation and subsequent apoptosis were significantly inhibited in stable p53-shRNA transfectants. Similarly, H1299/p53 cells were more sensitive to Gefitinib compared to H1299 cells in clonogenic survival assay. This event was accompanied by p53 phosphorylation, as well as Fas, PUMA, survivin, and XIAP modulation. Collectively, the results support an important role of p53 in Gefitinib-induced apoptosis in human lung cancer cells. p53 may induce apoptosis through the regulation of apoptotic (Fas and PUMA) and anti-apoptotic (XIAP and survivin) genes. Our studies not only pave a way to the understanding of pharmacological mechanisms of Gefitinib, but also implicate for the necessity to prescreen p53 expression level before clinical application of Gefitinib in human cancer therapy.

Treatment of gastrointestinal neuroendocrine tumors with inhibitors of growth factor receptors and their signaling pathways: recent advances and future perspectives

The limited efficacy of conventional cytotoxic treatment regimes for advanced gastrointestinal neuroendocrine cancers emphasizes the need for novel and more effective medical treatment options. Recent findings on the specific biological features of this family of neoplasms has led to the development of new targeted therapies, which take into account the high vascularization and abundant expression of specific growth factors and cognate tyrosine kinase receptors. This review will briefly summarize the status and future perspectives of antiangiogenic, mTOR- or growth factor receptor-based pharmacological approaches for the innovative treatment of gastrointestinal neuroendocrine tumors. In view of the multitude of novel targeted approaches, the rationale for innovative combination therapies, i.e. combining growth factor (receptor)-targeting agents with chemo- or biotherapeutics or with other novel anticancer drugs such as HDAC or proteasome inhibitors will be taken into account.

Medical treatment of gastrinomas

Gastrinomas are functional neuroendocrine tumors of the gastroenteropancreatic system. Surgery is first line treatment in gastrinomas, however often fails to be curative. This manuscript reviews current strategies of medical treatment of surgically non-curable gastrinoma. Symptomatic treatment with H(+)-K(+)-ATPase proton-pump inhibitors suppresses hypersecretion of gastric acid and substantially improves quality of life in patients with Zollinger-Ellison syndrome. Further medical therapy is only recommended in cases of progressive metastatic gastrinoma. In well differentiated neuroendocrine carcinoma (G1 and G2) a so-called biotherapy with somatostatin analogues exists as first-line and chemotherapy with streptocotozin plus doxorubicine/5-FU as second-line medical treatment option. In poorly differentiated neuroendocrine carcinoma (G3) chemotherapy with etoposide plus cisplatin is possible. Prospective future therapeutic strategies may include treatment with novel somatostatin analogues as well as angiogenesis inhibitors and kinase inhibitors targeting tumor-specific signaling cascades.

PI(3)K-Akt-mTOR pathway as a potential therapeutic target in neuroendocrine tumors

Constitutive activation of PI(3)K-Akt-mTOR signaling is a frequently occurring event in human cancer and has also been detected in the majority of neuroendocrine tumors (NETs) of the gastroenteropancreatic system. Molecular analysis of NETs suggests, that in addition to mutations in certain tumor-suppressor genes (e.g., PTEN), multiple autocrine growth factor loops contribute to hyperactive PI(3)K-Akt-mTOR signaling, thus promoting unrestricted proliferation and resistance to apoptosis. These insights opened new perspectives for targeted therapy in NETs. In particular, several novel small-molecule inhibitors of tyrosine and serine/threonine kinases have demonstrated potent anti-tumor activity. This review will summarize current knowledge on PI(3)K-Akt-mTOR signaling, its role in proliferation and apoptosis, as well as novel therapeutic approaches targeting PI(3)K-Akt-mTOR pathway components in NET disease.

Relation of neuroendocrine cells to transforming growth factor-alpha and epidermal growth factor receptor expression in gastric adenocarcinomas: prognostic implications

The presence of neuroendocrine (NE) cells in gastric adenocarcinoma (GCa) is well documented, however, their significance is controversial. There is no evidence in the literature concerning the possible effect of these cells on the expression of TGF-alpha and EGFR, which are believed to confer growth advantage to tumor cells. 101 partial or total gastrectomy specimens from patients operated for conventional gastric adenocarcinoma were included in the study. In each case immunohistochemistry was performed on sequential tissue sections for chromogranin A (ChrA), TGF-alpha and EGFR. Samples were graded based on the number of ChrA-positive cells (0-3). TGF-alpha and EGFR expressions were evaluated according to both the intensity (0-2) and quantification of the positively stained areas (0-3). Follow-up data was available in 54 patients. Twenty-seven patients died of disease, while 27 patients were alive with a follow-up of at least 15 months. ChrA expression was detected in 54.4% of the tumor specimens. TGF-alpha was stained positively in 42.6% and EGFR in 49.5% of the cases. NE cells in GCa was related to TGF-alpha (p<0.0001) and EGFR expression (p<0.05), and TGF-alpha/EGFR coexpression (p<0.001). Among histopathologic variables, the presence of NE cells was significantly related to grade, stage and lymph node status. Although the presence of NE cells had no effect on survival, the expression of EGFR (p<0.0001) and TGF-alpha (p=0.002) were related to survival. The results of our study suggest that the presence of NE cells may have an effect on the expression of TGF-alpha and EGFR in GCa, and the autocrine mechanism between TGF-alpha and EGFR plays an important role in the prognosis of gastric carcinoma.

Emerging therapies for the treatment of patients with advanced neuroendocrine tumors

Patients with neuroendocrine tumors may pursue a number of treatment options, but there is little consensus on a single, standard treatment approach. Somatostatin analogs are generally administered to patients with symptoms of hormonal secretion, and are often highly effective in this regard. However, the administration of somatostatin analogs is only rarely associated with tumor regression, and randomized trials demonstrating a survival benefit associated with their use have not been performed. Selected patients with hepatic metastases may undergo surgical debulking, embolization or other ablative therapies. The clinical benefit associated with administration of systemic agents such as IFN-alpha or cytotoxic chemotherapy has been limited. With the possible exception of streptozocin-based therapy in patients with pancreatic neuroendocrine tumors, the widespread use of standard cytotoxic regimens has been limited by their relatively modest antitumor activity, as well as concerns regarding their potential toxicity. The modest efficacy seen with these agents in patients with advanced neuroendocrine tumors has led to great interest in the development of novel treatment approaches. One such approach is the use of radiolabeled somatostatin analogs. Recently, agents targeting the VEGF pathway and mammalian target of rapamycin have also shown promise in patients with advanced neuroendocrine tumors. Ongoing randomized studies should help better define the role these agents will play in the future treatment of patients with this disease.

New drug development in digestive neuroendocrine tumors

The traditional cytotoxic agents are of limited efficacy in the treatment of neuroendocrine tumors of the gastrointestinal tract (NETs). Recent investigations have brought up a number of biological features in this family of neoplasms that could represent targets for anticancer treatment. NETs seem to have an extraordinary tumor vascularization with high expression of proangiogenic molecules such as the vascular endothelial growth factor along with overexpression of certain tyrosine kinase receptors such as the epidermal growth factor receptor (EGFR), the insulin growth factor receptor (IGFR) and their downstream signaling pathway components (PI3K-AKT-mTOR). The rationale of an antiangiogenic approach in the treatment of NETs and the use of other pharmacological strategies such as EGFR, IGFR and mammalian target of rapamycin inhibitors are discussed. Additionally, the emerging results of recent clinical trials with these targeted drugs are presented.

Characterization of the functional and growth properties of cell lines established from ileal and rectal carcinoid tumors

Carcinoids of the intestine are the most common gastrointestinal carcinoid tumors. Therapeutic options to treat patients with these tumors are limited. There are very few ileal carcinoid cell lines available for in vitro studies to analyze new drugs that could be effective in treating patients with metastatic tumors. A replication defective recombinant adenovirus with an SV40 early T-antigen insert was used to infect two intestinal carcinoid tumors to create carcinoid cell lines. The cell lines were studied by cell culture, reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry. Both cell lines expressed SV40 large T antigen and receptors for TGFbeta1, TGFbeta2, EGFR, and somatostatin receptors. Treatment with TGFbeta1 led to growth inhibition and increased apoptosis in the cultured cells. Octreotide inhibited cell growth of both cell lines while stimulating apoptosis. Treatment of the HC45 cells with gefitinib also inhibited cell growth in a concentration-dependent manner. TGFbeta treatment stimulated chromogranin A expression while expression of two other granins, chromogranin B and 7B2, did not change significantly. RNA profiling of cells treated with TGFbeta1 showed increased expression of vitamin D3 receptor. This finding was validated by real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemistry. These results indicate that these carcinoid cell lines can be used to study the proliferative and apoptotic mechanisms involved in intestinal carcinoid tumor growth regulation.

Tyrosine kinase of insulin-like growth factor receptor as target for novel treatment and prevention strategies of colorectal cancer

AIM: To investigate the antineoplastic potency of the novel insulin-like growth factor 1 receptor (IGF-1R) tyrosine kinase inhibitor (TKI) NVP-AEW541 in cell lines and primary cell cultures of human colorectal cancer (CRC).

METHODS: Cells of primary colorectal carcinomas were from 8 patients. Immunostaining and crystal violet staining were used for analysis of growth factor receptor protein expression and detection of cell number changes, respectively. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase (LDH). The proportion of apoptotic cells was determined by quantifying the percentage of sub-G1 (hypodiploid) cells. Cell cycle status reflected by the DNA content of the nuclei was detected by flow cytometry.

RESULTS: NVP-AEW541 dose-dependently inhibited the proliferation of colorectal carcinoma cell lines and primary cell cultures by inducing apoptosis and cell cycle arrest. Apoptosis was characterized by caspase-3 activation and nuclear degradation. Cell cycle was arrested at the G1/S checkpoint. The NVP-AEW541-mediated cell cycle-related signaling involved the inactivation of Akt and extracellular signal-regulated kinase (ERK) 1/2, the upregulation of the cyclin-dependent kinase inhibitors p21^Waf1/CIP1 and p27^Kip1, and the downregulation of the cell cycle promoter cyclin D1. Moreover, BAX was upregulated during NVP-AEW541-induced apoptosis, whereas Bcl-2 was downregulated. Measurement of LDH release showed that the antineoplastic effect of NVP-AEW541 was not due to general cytotoxicity of the compound. However, augmented antineoplastic effects were observed in combination treatments of NVP-AEW541 with either 5-FU, or the EGFR-antibody cetuximab, or the HMG-CoA-reductase inhibitor fluvastatin.

CONCLUSION: IGF-1R-TK inhibition is a promising novel approach for either mono- or combination treatment strategies of colorectal carcinoma and even for CRC chemoprevention.

Epidermal growth factor receptor expression and activation in neuroendocrine tumours

Epidermal growth factor receptor (EGFR) is expressed in many cancers and is associated with poor prognosis. EGFR activation pathways have been well characterised using tumour cell lines and are known to involve EGFR activation through autophosphorylation. Phosphorylation of downstream signalling molecules, such as ERK1/2 (extra-cellular regulated kinase 1 and 2) and PKB/Akt (protein kinase B), leads to enhanced tumour cell survival and proliferation. Although EGFR expression has been determined in neuroendocrine tumour tissue, its activation and subsequent effects on the downstream signalling molecules, ERK1/2 and Akt, have not been studied. We therefore planned to determine the role of EGFR in neuroendocrine tumours (NETs) by determining its pattern of expression and activation, and the subsequent activation of downstream signalling molecules ERK1/2 and Akt. Paraffin-embedded tumour tissue was available from 98 patients with NETs (39 foregut, 42 midgut, four hindgut, five paragangliomas, and four of unknown origin). Immunohistochemical evaluation was performed for the expression of EGFR, p-EGFR, p-Akt, and p-ERK1/2. Ninety-six percent of tumour samples were positive for EGFR expression; 63% were positive for activated EGFR; 76% were positive for activated Akt; and 96% were positive for activated ERK1/2. Importantly, the histological score for the activation of Akt and ERK1/2 correlated with the histological score for activated EGFR. These data provide a rationale for considering EGFR inhibitors in the treatment of NETs. Additionally, direct inhibition of Akt and ERK1/2 may provide further therapeutic options in the treatment of NETs in the future.

The management of insulinoma

BACKGROUND

Insulinomas are rare tumours. Their clinical presentation, localization techniques and operative management were reviewed.

METHODS

An electronic search of the Medline, Embase and Cochrane databases was undertaken for articles published between January 1966 and June 2005 on the history, presentation, clinical evaluation, use of imaging techniques for tumour localization and operative management of insulinoma.

RESULTS AND CONCLUSION

Most insulinomas are intrapancreatic, benign and solitary. Biochemical diagnosis is obtained during a supervised 72-h fast. Non-invasive preoperative imaging techniques to localize lesions continue to evolve. Intraoperative ultrasonography can be combined with other preoperative imaging modalities to improve tumour detection. Surgical resection is the treatment of choice. In the absence of preoperative localization and intraoperative detection of an insulinoma, blind pancreatic resection is not recommended.

Analysis of neuroendocrine differentiation and the p53/BAX pathway in UICC stage III colorectal carcinoma identifies patients with good prognosis

BACKGROUND AND AIMS

Neuroendocrine differentiation is an independent prognostic factor in colorectal cancer. Moreover, an altered p53/BAX pathway is associated with a poor clinical outcome in Union Internationale Contre le Cancer (UICC) stage III disease. Because these markers are involved in different genetic events disrupted in colorectal cancer, we investigated the prognostic power of a multimarker analysis.

PATIENTS AND METHODS

Specimens were analyzed from 59 patients with UICC stage III disease who underwent surgery for colorectal adenocarcinoma at our institution and were followed up for 5 years or until death. Tumors were studied for both p53 mutation and BAX protein expression as well as for the expression of neuroendocrine markers. Statistical analysis of each marker alone or in combination was performed.

RESULTS

p53 status/BAX expression and neuroendocrine differentiation are not correlated in stage III colorectal cancers. However, the combination of both independent events identified a subgroup of patients with an excellent prognosis: Patients whose tumors were neuroendocrine marker-negative and who exhibited an intact p53/BAX pathway lived longer (mean survival, 93 months; range, 82-104 months) than patients whose tumors were either neuroendocrine marker-positive or whose tumors had a completely disrupted apoptotic pathway (41 months; range, 26-57 months; p<0.00001). In multivariate regression analysis, neuroendocrine marker-positive, p53 mutated, low-BAX-expressing tumors revealed an almost fivefold higher risk for earlier death (p<0.0001).

CONCLUSION

Disruption of the p53/BAX pathway is not pathognomonic for colorectal cancers with neuroendocrine differentiation. Both represent independent prognostic markers in UICC stage III disease. Therefore, the combined analysis of p53 status, BAX expression and neuroendocrine differentiation allows one to identify subgroups of patients with either very good or very poor prognosis.

Targeting the epidermal growth factor receptor by erlotinib (Tarceva) for the treatment of esophageal cancer

Esophageal cancer is the sixth most common cause of cancer-related death worldwide. Because of very poor 5-year survival new therapeutic approaches are mandatory. Erlotinib (Tarceva), an inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), potently suppresses the growth of various tumors but its effect on esophageal carcinoma, known to express EGFR, remains unexplored. We therefore studied the antineoplastic potency of erlotinib in human esophageal cancer cells. Erlotinib induced growth inhibition of the human esophageal squamous cell carcinoma (ESCC) cell lines Kyse-30, Kyse-70 and Kyse-140, and the esophageal adenocarcinoma cell line OE-33, as well as of primary cell cultures of human esophageal cancers. Combining erlotinib with the EGFR-receptor antibody cetuximab, the insulin-like growth factor receptor tyrosine kinase inhibitor tyrphostin AG1024, or the 3-hydroxy-3-methylglutaryl coenzyme. A reductase (HMG-CoAR) inhibitor fluvastatin resulted in additive or even synergistic antiproliferative effects. Erlotinib induced cell cycle arrest at the G1/S checkpoint. The erlotinib-mediated signaling involved the inactivation of EGFR-TK and ERK1/2, the upregulation of the cyclin-dependent kinase inhibitors p21(Waf1/CIP1) and p27(Kip1), and the downregulation of the cell cycle promoter cyclin D1. However, erlotinib did not induce immediate cytotoxicity or apoptosis in esophageal cancer cells. The inhibition of EGFR-TK by erlotinib appears to be a promising novel approach for innovative treatment strategies of esophageal cancer, as it powerfully induced growth inhibition and cell cycle arrest in human esophageal cancer cells and enhanced the antineoplastic effects of other targeted agents.

Blockade of IGF-1 receptor tyrosine kinase has antineoplastic effects in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common cancer-related causes of death worldwide. Due to very poor 5-year-survival new therapeutic approaches are mandatory. Most HCCs express insulin-like growth factors and their receptors (IGF-R). As IGF-1R-mediated signaling promotes survival, oncogenic transformation and tumor growth and spread, it represents a potential target for innovative treatment strategies of HCC. Here we studied the antineoplastic effects of inhibiting IGF-1R signaling in HCC cells by the novel IGF-1R tyrosine kinase inhibitor NVP-AEW541.

METHODS AND RESULTS

NVP-AEW541 induced a time- and dose-dependent growth inhibition in the human hepatoblastoma and hepatocellular carcinoma cell lines SK-Hep-1, Hep-3B, Hep-G2 and Huh-7. Measurement of LDH-release showed that the antineoplastic effect of NVP-AEW541 was not due to cytotoxicity. Instead NVP-AEW541 induced apoptosis as evidenced by both caspase-3 and -8 activation as well as by apoptosis-specific morphological and mitochondrial changes. In addition, nuclear degradation was monitored by DNA-laddering. NVP-AEW541-treatment suppressed the expression of the antiapoptotic proteins Bcl-2 and survivin, while the expression of the proapoptotic protein BAX was stimulated in a dose-dependent manner. Moreover, NVP-AEW541 arrested the cell cycle at the G1/S checkpoint. When NVP-AEW541 was combined with cytotoxic chemotherapy or with a specific epidermal growth factor receptor antibody additive antiproliferative effects were observed.

INTERPRETATION

Inhibition of IGF-1R tyrosine kinase (IGF-1R-TK) by NVP-AEW541 induces growth inhibition, apoptosis and cell cycle arrest in human HCC cell lines without accompanying cytotoxicity. Thus, IGF-1R-TK inhibition may be a promising novel treatment approach in HCC.

Expression of tyrosine kinase receptors in malignant midgut carcinoid tumors

BACKGROUND

The expression of certain tyrosine kinase receptors (TKR) has been shown to have a prognostic value in many tumor entities. In recent years, inhibitors and monoclonal antibodies directed towards these receptors have been developed. Several have shown antitumoral effects and have been tested in clinical trials. We wanted to investigate whether midgut carcinoid tumors express TKR and therefore would be suitable for clinical trials with TKR inhibitors (TKRI) or monoclonal antibodies.

MATERIAL AND METHODS

Tumor tissue from 36 patients (24 women and 12 men) with a malignant midgut carcinoid tumor was obtained. The tissues were examined with immunohistochemistry, using polyclonal antibodies against platelet-derived growth factor receptor-alpha (PDGFRalpha), platelet-derived growth factor receptor-beta (PDGFRbeta), epidermal growth factor receptor (EGFR) and c-kit. Human BON1 cells were cultivated and stimulated with PDGF-BB. We also present a case report of a patient with a malignant midgut carcinoid tumor who had stabilization of tumor growth during treatment with imatinib.

RESULTS

Immunohistochemical staining for PDGFRalpha in tumor cells showed immunoreaction for the receptor in 13/34 (38%) for PDGFRbeta in 29/33 (88%), and 24/33 (73%) were immunoreactive for EGFR. No tumor tissue showed immunoreaction for c-kit. In tumor stroma PDGFRalpha was expressed in 35%, PDGFRbeta in 94% and EGFR in 9%. We show that human neuroendocrine tumor cells respond to PDGF, indicating that these tumors express functional PDGF receptors.

CONCLUSION

Malignant midgut carcinoid tumors may express three of the four TKR tested in this investigation. Therefore, these tumors might be susceptible for treatment with TKRI or monoclonal antibodies and this should be further explored in clinical trials.

Genes involved in neuroendocrine tumor biology

The fascinating, but often unpredictable, biology of neuroendocrine tumors (NETs) make the management of these malignancies a real challenge. The more recent development of high-throughput genomic and proteomic techniques, have opened a window to an increased knowledge of the biology of NETs. This review will discuss genes thought to play a role in the context of NE tumor biology, with particularly attention to those that may be potential new diagnostic and prognostic markers, as well as therapeutic targets. NETs constitute a heterogeneous group of neoplasm that may arise in virtually every topographic localization in the body, as a consequence of malignant transformation of various types of NE cells. Since NETs arising in the gastroenteropancreatic (GEP) or bronchopulmonary system are by far the most common, this review focuses on these entities, but lines are drawn to other NETs as well. Although large-scale gene expression analysis undoubtly have raised interesting new hypothesis concerning genes thought to play a role in tumor biology, discrepancies observed between studies and various platforms used, emphasizes the need to not only standardize the way microarray data are reported, but also to introduce standards in sample taking, processing and study design. In addition, the recognition of the complexity of the human proteome, with regard to generation of multiple isoforms from one gene, has created additional challenges. However,some goals have been reached already, as new knowledge has been translated into development of novel promising therapeutics.

Recent advances on the molecular mechanisms involved in pancreatic cancer progression and therapies

This review describes the recent advances in the molecular events involved in pancreatic cancer initiation, progression, and metastasis. Additionally, the importance of deregulated cellular signaling elements as potential targets for developing novel therapeutic strategies against incurable forms of pancreatic cancer is reported. The emphasis is on the critical functions gained by numerous growth factors and their receptors, such as epidermal growth factor receptor, hedgehog signaling, and proangiogenic agents such as vascular endothelial factor and interleukin-8 for the sustained growth, survival, and metastasis of pancreatic cancer cells. The molecular mechanisms associated with antitumoral properties and the clinical benefits of gemcitabine alone or in combination with other cytotoxic agents for the treatment of pancreatic cancer are discussed.

Epidermal growth factor receptor and activated epidermal growth factor receptor expression in gastrointestinal carcinoids and pancreatic endocrine carcinomas

The epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of many tumors. To analyze the expression of EGFR and activated EGFR in well-differentiated neuroendocrine carcinomas including primary and metastatic gastrointestinal carcinoid tumors and pancreatic endocrine tumors (PET), we examined 58 gastrointestinal carcinoid tumors and 48 PET using immunohistochemistry, Western blotting, and RT-PCR. EGFR and activated EGFR (P-EGFR) were expressed by both gastrointestinal carcinoids and PET in primary and metastatic tumors, although a higher percentage of gastrointestinal carcinoid tumors expressed EGFR and activated EGFR. Western blotting detected a 170 kDa band for both EGFR and activated EGFR in three primary carcinoid tumors and two metastatic carcinoid tumors to the liver. RT-PCR analysis confirmed the expression of EGFR mRNA in both primary and metastatic carcinoid tumors. Patients with activated EGFR expression in their primary PET had a significantly worse prognosis compared to those who did not express activated-EGFR (P = 0.043). These results indicate that gastrointestinal carcinoid tumors as well as PET express EGFR and activated EGFR, and that expression is more common in gastrointestinal carcinoid tumors compared to pancreatic endocrine tumors. These findings implicate the EGFR and P-EGFR signal transduction pathway in the pathogenesis of these neuroendocrine tumors and suggest that targeted therapy directed against the EGFR tyrosine kinase domain may be a useful therapeutic approach in patients with unresectable metastatic gastrointestinal carcinoid tumors and pancreatic endocrine tumors.

Identification of novel growth factor-responsive genes in neuroendocrine gastrointestinal tumour cells

Targeting growth-regulatory pathways is a promising approach in cancer treatment. A prerequisite to the development of such therapies is characterisation of tumour growth regulation in the particular tumour cell type of interest. In order to gain insight into molecular mechanisms underlying proliferative responses in neuroendocrine (NE) gastrointestinal (GI) tumours, we investigated gene expression in human carcinoid BON cells after exposure to gastrin, hepatocyte growth factor (HGF), pituitary adenylate cyclase-activating polypeptide or epidermal growth factor. We particularly focused on gastrin- and HGF-induced gene expression, and identified 95 gastrin- and 101 HGF-responsive genes. The majority of these genes are known mediators of processes central in tumour biology, and a number of them have been associated with poor prognosis and metastasis in cancer patients. Furthermore, we identified 12 genes that were regulated by all four factors, indicating that they may be universally regulated during NE GI tumour cell proliferation. Our findings provide useful hypotheses for further studies aimed to search for new therapeutic targets as well as tumour markers in NE GI tumours.