Somatostatin, cortistatin and their receptors in tumours

Engineering peptide drug therapeutics through chemical conjugation and implication in clinics

The development of peptide drugs has made tremendous progress in the past few decades because of the advancements in modification chemistry and analytical technologies. The novel-designed peptide drugs have been modified through various biochemical methods with improved diagnostic, therapeutic, and drug-delivery strategies. Researchers found it a helping hand to overcome the inherent limitations of peptides and bring continued advancements in their applications. Furthermore, the emergence of peptide-drug conjugates (PDCs)-utilizes target-oriented peptide moieties as a vehicle for cytotoxic payloads via conjugation with cleavable chemical agents, resulting in the key foundation of the new era of targeted peptide drugs. This review summarizes the various classifications of peptide drugs, suitable chemical modification strategies to improve the ADME (adsorption, distribution, metabolism, and excretion) features of peptide drugs, and recent (2015-early 2024) progress/achievements in peptide-based drug delivery systems as well as their fruitful implication in preclinical and clinical studies. Furthermore, we also summarized the brief description of other types of PDCs, including peptide-MOF conjugates and peptide-UCNP conjugates. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development and progress toward a bright future of novel peptide drugs.

Transcriptomic analysis identifies the neuropeptide cortistatin (CORT) as an inhibitor of temozolomide (TMZ) resistance by suppressing the NF-κB-MGMT signaling axis in human glioma

Glioma is a common tumor originating in the brain that has a high mortality rate. Temozolomide (TMZ) is the first-line treatment for high-grade gliomas. However, a large proportion of gliomas are resistant to TMZ, posing a great challenge to their treatment. In the study, the specific functions and mechanism(s) by which cortistatin (CORT) regulates TMZ resistance and glioma progression were evaluated. The decreased expression of CORT was detected in glioma tissues, and highly expressed CORT was associated with a better survival rate in patients with glioma. CORT overexpression notably decreased the capacity of glioma cells to proliferate and migrate in vitro and to form tumors in vivo. CORT overexpression also markedly suppressed the viability and enhanced the apoptosis of TMZ-resistant U251 cells by regulating MGMT, p21, and Puma expression. Importantly, CORT overexpression reduced the resistance of gliomas to TMZ in vivo. CORT expression was negatively correlated with MGMT expression in both glioma tissues and cells, and it was found that CORT inhibited NF-κB pathway activation in glioma cells, thereby inhibiting MGMT expression. In conclusion, CORT regulates glioma cell growth, migration, apoptosis, and TMZ resistance by weakening the activity of NF-κB/p65 and thereby regulating MGMT expression. The CORT/NF-κB/MGMT axis might be regarded as a molecular mechanism contributing to the resistance of glioma to TMZ. Our data also suggest that CORT regulates the viability and metastatic potential of glioma cells, independent of its effects on TMZ resistance, providing evidence of novel therapeutic targets for glioma that should be evaluated in further studies.

Peptide-Drug Conjugates: Design, Chemistry, and Drug Delivery System as a Novel Cancer Theranostic

The emergence of peptide-drug conjugates (PDCs) that utilize target-oriented peptide moieties as carriers of cytotoxic payloads, interconnected with various cleavable/noncleavable linkers, resulted in the key-foundation of the new era of targeted therapeutics. They are capable of retaining the integrity of conjugates in the blood circulatory system as well as releasing the drugs at the tumor microenvironment. Other valuable advantages are specificity and selectivity toward targeted-receptors, higher penetration ability, and drug-loading capacity, making them a suitable candidate to play their vital role as promising carrier agents. In this review, we summarized the types of cell-targeting (CTPs) and cell-penetrating peptides (CPPs) that have broad applications in the advancement of targeted drug-delivery systems (DDS). Moreover, the techniques to overcome the limitations of peptide-chemistry for their extensive implementation to construct the PDCs. Besides this, the diversified breakthrough of linker chemistry, and ample knowledge of various cytotoxic payloads used in PDCs in recent years, as well as the mechanism of action of PDCs was critically discussed. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development, also their progression toward a bright future for PDCs as novel theranostics in clinical practice.

Cuprotosis clusters predict prognosis and immunotherapy response in low-grade glioma

Cuprotosis, an emerging mode of cell death, has recently caught the attention of researchers worldwide. However, its impact on low-grade glioma (LGG) patients has not been fully explored. To gain a deeper insight into the relationship between cuprotosis and LGG patients' prognosis, we conducted this study in which LGG patients were divided into two clusters based on the expression of 18 cuprotosis-related genes. We found that LGG patients in cluster A had better prognosis than those in cluster B. The two clusters also differed in terms of immune cell infiltration and biological functions. Moreover, we identified differentially expressed genes (DEGs) between the two clusters and developed a cuprotosis-related prognostic signature through the least absolute shrinkage and selection operator (LASSO) analysis in the TCGA training cohort. This signature divided LGG patients into high- and low-risk groups, with the high-risk group having significantly shorter overall survival (OS) time than the low-risk group. Its predictive reliability for prognosis in LGG patients was confirmed by the TCGA internal validation cohort, CGGA325 cohort and CGGA693 cohort. Additionally, a nomogram was used to predict the 1-, 3-, and 5-year OS rates of each patient. The analysis of immune checkpoints and tumor mutation burden (TMB) has revealed that individuals belonging to high-risk groups have a greater chance of benefiting from immunotherapy. Functional experiments confirmed that interfering with the signature gene TNFRSF11B inhibited LGG cell proliferation and migration. Overall, this study shed light on the importance of cuprotosis in LGG patient prognosis. The cuprotosis-related prognostic signature is a reliable predictor for patient outcomes and immunotherapeutic response and can help to develop new therapies for LGG.

Cortistatin prevents glucocorticoid-associated osteonecrosis of the femoral head via the GHSR1a/Akt pathway

Long-term use of glucocorticoids (GCs) is known to be a predominant cause of osteonecrosis of the femoral head (ONFH). Moreover, GCs can mediate apoptosis of various cell types by exaggerating oxidative stress. We have previously found that Cortistatin (CST) antagonizes oxidative stress and improves cell apoptosis in several conditions. In this study, we detected that the CST expression levels were diminished in patients with ONFH compared with femoral neck fracture (FNF). In addition, a GC-induced rat ONFH model was established, which impaired bone quality in the femoral head. Then, administration of CST attenuated these ONFH phenotypes. Furthermore, osteoblast and endothelial cells were cultured and stimulated with dexamethasone (Dex) in the presence or absence of recombinant CST. As a result, Dex induced impaired anabolic metabolism of osteoblasts and suppressed tube formation in endothelial cells, while additional treatment with CST reversed this damage to the cells. Moreover, blocking GHSR1a, a well-accepted receptor of CST, or blocking the AKT signaling pathway largely abolished the protective function of CST in Dex-induced disorder of the cells. Taken together, we indicate that CST has the capability to prevent GC-induced apoptosis and metabolic disorder of osteoblasts in the pathogenesis of ONFH via the GHSR1a/AKT signaling pathway.

18F-Labeled Somatostatin Analogs as PET Tracers for the Somatostatin Receptor: Ready for Clinical Use

Molecular imaging of the somatostatin receptor plays a key role in the clinical management of neuroendocrine tumors. PET imaging with somatostatin analogs (SSAs) labeled with ⁶⁸Ga or ⁶⁴Cu is currently the gold standard in clinical practice. However, widespread implementation of ⁶⁸Ga imaging is often hampered by practical and economic issues related to ⁶⁸Ge/⁶⁸Ga generators. ¹⁸F offers several advantages to tackle these issues. Recent developments in radiochemistry have allowed a shift from ⁶⁸Ga toward ¹⁸F labeling, leading to promising clinical translations of ¹⁸F-labeled SSAs, such as Gluc-Lys-[¹⁸F]FP-TOCA, [¹⁸F]F-FET-βAG-TOCA, [¹⁸F]AlF-NOTA-octreotide, [¹⁸F]SiTATE, and [¹⁸F]AlF-NOTA-JR11. This review gives an update of currently available clinical data regarding ¹⁸F-labeled SSA tracers and provides justification for the clinical application of this class of tracers.

Prospective Multicentric Assessment of 68Ga-DOTANOC PET/CT in Grade 1-2 GEP-NET

The aim of this multicentric study was to prospectively compare 68Ga-DOTANOC PET/CT versus somatostatin receptor scintigraphy (SRS) with SPECT/CT, combined with multiphasic CT scan and MRI in patients with grade 1 or 2 gastroenteropancreatic neuroendocrine tumors (GEP-NET). Patients with histologically proven grade 1 or 2 GEP-NET with suspicion of recurrence or progression, or with typical aspects of GEP-NET on morphological imaging, were explored with conventional imaging (CI): SRS with SPECT/CT, multiphasic CT scan and/or liver MRI followed by 68Ga-DOTANOC PET/CT. The gold standard was based on histology and imaging follow-up. The data of 105 patients (45 woman and 60 men; median age) were analyzed. 68Ga-DOTANOC PET/CT sensitivity was significantly higher than CI sensitivity in per-patient (98.9% vs. 88.6%, p = 0.016) and per-region (97.6% vs. 75.6%, p < 0.001) analyses, in the detection of the primary (97.9% vs. 78.7%; p = 0.016), peritoneal carcinomatosis (95% vs. 30%, p < 0.001), and bone metastases (100% vs. 33.3%, p = 0.041). 68Ga-DOTANOC PET/CT had an impact on the therapeutic management of 41.9% (44/105) patients compared to decisions based on CI explorations. Our data confirm the superiority of 68Ga-DOTANOC PET/CT over CI in the detection of peritoneal carcinomatosis and bone metastasis, as well as its strong therapeutic impact on the management of patients with grade 1-2 GEP-NETs.

Radiolabeled Somatostatin Analogs-A Continuously Evolving Class of Radiopharmaceuticals

Somatostatin receptors (SSTs) are recognized as favorable molecular targets in neuroendocrine tumors (NETs) and neuroendocrine neoplasms (NENs), with subtype 2 (SST₂) being the predominantly and most frequently expressed. PET/CT imaging with ⁶⁸Ga-labeled SST agonists, e.g., ⁶⁸Ga-DOTA-TOC (SomaKit TOC^®) or ⁶⁸Ga-DOTA-TATE (NETSPOT^®), plays an important role in staging and restaging these tumors and can identify patients who qualify and would potentially benefit from peptide receptor radionuclide therapy (PRRT) with the therapeutic counterparts ¹⁷⁷Lu-DOTA-TOC or ¹⁷⁷Lu-DOTA-TATE (Lutathera^®). This is an important feature of SST targeting, as it allows a personalized treatment approach (theranostic approach). Today, new developments hold promise for enhancing diagnostic accuracy and therapeutic efficacy. Among them, the use of SST₂ antagonists, such as JR11 and LM3, has shown certain advantages in improving image sensitivity and tumor radiation dose, and there is evidence that they may find application in other oncological indications beyond NETs and NENs. In addition, PRRT performed with more cytotoxic α-emitters, such as ²²⁵Ac, or β^- and Auger electrons, such as ¹⁶¹Tb, presents higher efficacy. It remains to be seen if any of these new developments will overpower the established radiolabeled SST analogs and PRRT with β^--emitters.

Structure-based design of a Cortistatin analogue with immunomodulatory activity in models of inflammatory bowel disease

Ulcerative colitis and Crohn’s disease are forms of inflammatory bowel disease whose incidence and prevalence are increasing worldwide. These diseases lead to chronic inflammation of the gastrointestinal tract as a result of an abnormal response of the immune system. Recent studies positioned Cortistatin, which shows low stability in plasma, as a candidate for IBD treatment. Here, using NMR structural information, we design five Cortistatin analogues adopting selected native Cortistatin conformations in solution. One of them, A5, preserves the anti-inflammatory and immunomodulatory activities of Cortistatin in vitro and in mouse models of the disease. Additionally, A5 displays an increased half-life in serum and a unique receptor binding profile, thereby overcoming the limitations of the native Cortistatin as a therapeutic agent. This study provides an efficient approach to the rational design of Cortistatin analogues and opens up new possibilities for the treatment of patients that fail to respond to other therapies.

Inflammatory bowel disease is caused by chronic inflammation of the gastrointestinal tract and disturbed immune responses. Here the authors present examination of Cortistatin analogues that display enhanced half-life stability whilst maintaining immunomodulatory functionality.

Peptide-Drug Conjugates and Their Targets in Advanced Cancer Therapies

Cancer became recently the leading cause of death in industrialized countries. Even though standard treatments achieve significant effects in growth inhibition and tumor elimination, they cause severe side effects as most of the applied drugs exhibit only minor selectivity for the malignant tissue. Hence, specific addressing of tumor cells without affecting healthy tissue is currently a major desire in cancer therapy. Cell surface receptors, which bind peptides are frequently overexpressed on cancer cells and can therefore be considered as promising targets for selective tumor therapy. In this review, the benefits of peptides as tumor homing agents are presented and an overview of the most commonly addressed peptide receptors is given. A special focus was set on the bombesin receptor family and the neuropeptide Y receptor family. In the second part, the specific requirements of peptide-drug conjugates (PDC) and intelligent linker structures as an essential component of PDC are outlined. Furthermore, different drug cargos are presented including classical and recent toxic agents as well as radionuclides for diagnostic and therapeutic approaches. In the last part, boron neutron capture therapy as advanced targeted cancer therapy is introduced and past and recent developments are reviewed.

Recent Advances and Impact of Chemotherapeutic and Antiangiogenic Nanoformulations for Combination Cancer Therapy

Traditional chemotherapy, along with antiangiogenesis drugs (combination cancer therapy), has shown reduced tumor recurrence and improved antitumor effects, as tumor growth and metastasis are often dependent on tumor vascularization. However, the effect of combination chemotherapy, including synergism and additive and even antagonism effects, depends on drug combinations in an optimized ratio. Hence, nanoformulations are ideal, demonstrating a great potential for the combination therapy of chemo-antiangiogenesis for cancer. The rationale for designing various nanocarriers for combination therapy is derived from organic (polymer, lipid), inorganic, or hybrid materials. In particular, hybrid nanocarriers that consist of more than one material construct provide flexibility for different modes of entrapment within the same carrier—e.g., physical adsorption, encapsulation, and chemical conjugation strategies. These multifunctional nanocarriers can thus be used to co-deliver chemo- and antiangiogenesis drugs with tunable drug release at target sites. Hence, this review attempts to survey the most recent advances in nanoformulations and their impact on cancer treatment in a combined regimen—i.e., conventional cytotoxic and antiangiogenesis agents. The mechanisms and site-specific co-delivery strategies are also discussed herein, along with future prospects.

Targeted-nanoliposomal combretastatin A4 (CA-4) as an efficient antivascular candidate in the metastatic cancer treatment

A number of antiangiogenic drugs have been approved by the Food and Drug Administration which are used in cancer therapy, and variety of other agents in several stages of clinical development or in preclinical assessment. Among these, combretastatin A4 (CA-4) is an under-researched inhibitor of angiogenesis that shows potential activity in the treatment of advanced tumors with migration capacity. However, its clinical application has been limited due to poor water solubility, low bioavailability, rapid metabolism, and systemic elimination. During the last decade, numerous investigations have been done to overcome these problems by using different CA-4 delivery systems or developing produgs of CA-4 or its structural analogs. Nevertheless, these strategies could not be efficient out of the undesired side effects on normal tissues. Nanoliposomal CA-4 not only benefits from the advantage of using liposomal drugs as opposed to free drugs but also can accumulate in the tumor site via specific targeting ligands, which leads to efficient targeting and enhancement of bioavailability. To the best of our knowledge, we consider an important attempt to understand different factors that might influence the CA-4 loading and release pattern of liposomes and the consequent results in tumor therapy. In this review, we shed light on various studied liposomal CA-4 formulations showing application thereof in cancer treatment.

Somatostatin receptor expression in parathyroid neoplasms

INTRODUCTION

Parathyroid carcinoma represents a rare cause of primary hyperparathyroidism. Distinguishing carcinoma from the benign tumors underlying primary hyperparathyroidism remains challenging. The diagnostic criteria for parathyroid carcinoma are local and/or metastatic spreading. Atypical parathyroid adenomas share other histological features with carcinomas but lack invasive growth. Somatostatin receptors are commonly expressed in different neuroendocrine tumors, but whether this also holds for parathyroid tumors remains unknown.

AIM

Our aim is to examine the immunohistochemical expression of somatostatin receptor 1-5 in parathyroid typical adenomas, atypical adenomas and carcinomas.

METHODS

We used a tissue microarray construct from a nationwide cohort of parathyroid carcinomas (n = 32), age- and gender-matched typical parathyroid adenomas (n = 72) and atypical parathyroid adenomas (n = 27) for immunohistochemistry of somatostatin receptor subtypes 1-5. We separately assessed cytoplasmic, membrane and nuclear expression and also investigated the associations with histological, biochemical and clinical characteristics.

RESULTS

All parathyroid tumor subgroups expressed somatostatin receptors, although membrane expression appeared negligible. Except for somatostatin receptor 1, expression patterns differed between the three tumor types. Adenomas exhibited the weakest and carcinomas the strongest expression of somatostatin receptor 2, 3, 4 and 5. We observed the largest difference for cytoplasmic somatostatin receptor 5 expression.

CONCLUSIONS

Parathyroid adenomas, atypical adenomas and carcinomas all express somatostatin receptor subtypes 1-5. Somatostatin receptor 5 may serve as a potential tumor marker for malignancy. Studies exploring the role of somatostatin receptor imaging and receptor-specific therapies in patients with parathyroid carcinomas are needed.

Encoding function into polypeptide-oligonucleotide precision biopolymers

We report a novel synthesis strategy to prepare precision polymers providing exact chain lengths, molecular weights and monomer sequences that allow post modifications by convenient DNA hybridization. Two grafted single strand DNA (ssDNA) side chains serve as a versatile platform for sequence-specific attachment of chromophores, proteins, cell-targeting peptide, and a Y-shape DNA linker. This approach resembles a LEGO®-type incorporation of functionalities to create functional biopolymers of high structure definition under mild conditions.

Clinical and functional implication of the components of somatostatin system in gastroenteropancreatic neuroendocrine tumors

PURPOSE

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) comprise a heterogeneous group of malignancies often presenting with metastasis at diagnosis and whose clinical outcome is difficult to predict. Somatostatin (SST) analogs (SSAs) provide a valuable pharmacological tool to palliate hormonal symptoms, and control progression in some NETs. However, many patients do not respond to SSAs or develop resistance, and there are many uncertainties regarding pathophysiology of SST and its receptors (sst1-sst5) in GEP-NETs.

METHODS

The expression of SST system components in GEP-NETs was determined, compared with that of non-tumor adjacent and normal tissues and correlated with clinical and histological characteristics. Specifically, 58 patients with GEP-NETs and 14 normal samples were included. Cell viability in NET cell lines was determined in response to specific SSAs.

RESULTS

Normal samples and non-tumor adjacent tissues presented a similar expression profile, with appreciable expression of sst2 and sst3, and a lower expression of the other receptors. In contrast, cortistatin, sst1, sst4, and sst5 were overexpressed in tumors, while sst3 and sst4 seemed overexpressed in less differentiated tumors. Some SST system components were related to vascular/nerve invasion and metastasis. In vitro, sst1 and sst3 agonists reduced viability in BON-1 cells, while they, similar to octreotide and pasireotide, increased viability in QGP-1 cells.

CONCLUSIONS

These results provide novel information on SST system pathophysiology in GEP-NETs, including relevant associations with clinical-histological parameters, which might help to better understand the intrinsic heterogeneity of NETs and to identify novel biomarkers and/or targets with potential prognostic and/or therapeutic value for GEP-NETs patients.

Circulating levels of cortistatin are correlated with metabolic parameters in patients with newly diagnosed type 2 diabetes mellitus

Cortistatin (CST) is a recently discovered cyclic neuropeptide with multiple bioactive effects. The aim of this study was to investigate the relationship between plasma CST and various metabolic markers in patients with newly diagnosed type 2 diabetes mellitus (T2DM). For this study, 60 patients with newly diagnosed T2DM and 38 age- and gender-matched healthy controls were recruited. Fasting plasma glucose (FPG), serum insulin and hemoglobin A_1c (HbA_1c) levels and a blood lipid profile were obtained with commercially available diagnostic reagents. CST plasma levels were determined using an enzyme immunoassay kit. The results showed that the plasma levels of CST were substantially lower in patients with newly diagnosed T2DM compared with the healthy controls. Plasma CST levels were positively correlated with high-density lipoprotein and negatively related to FPG, serum insulin, the homeostasis model assessment of insulin resistance (HOMA-IR) and HbA_1c in all subjects. Further analysis showed that CST levels were positively correlated with systolic blood pressure and negatively correlated with FPG, serum insulin, HOMA-IR and HbA_1c in patients with newly diagnosed T2DM. Moreover, logistic regression analyses indicated that plasma CST was correlated with newly diagnosed T2DM. In conclusion, patients with newly diagnosed T2DM had significantly lower plasma levels of CST than healthy controls, and plasma CST was associated with glucose metabolism and insulin resistance, indicating a potential role of CST in the development of T2DM.

Berberine ameliorates collagen-induced arthritis in rats by suppressing Th17 cell responses via inducing cortistatin in the gut

Berberine, an isoquinoline alkaloid, has been reported to ameliorate various autoimmune diseases including rheumatoid arthritis by oral administration. However, its mechanism remains mysterious due to an extremely low bioavailability. The fact that berberine readily accumulates in the gut, the largest endocrine organ in the body, attracted us to explore its anti-arthritic mechanism in view of the induction of intestinal immunosuppressive neuropeptides. In this study, berberine (200 mg·kg^-1 , i.g.) was shown to ameliorate collagen-induced arthritis in rats, which was manifested by the reduction of clinical signs and joint destruction, as well as marked down-regulation of Th17 cell frequency and interleukin-17 level in blood. In contrast, an intravenous injection of berberine failed to affect arthritis in rats, implying that its anti-arthritic effect was gut-dependent. Further studies revealed that oral berberine selectively elevated the levels of cortistatin, of five gut-derived neuropeptides tested, in the intestines and sera of arthrititic rats. Antagonists of ghrelin/growth hormone secretagogue receptor 1 (a subtype of cortistatin receptor) almost completely abolished the ameliorative effect of berberine on arthritis and Th17 cell responses in rats. In vitro, berberine showed a moderate ability to promote the expression of cortistatin in nerve cells, which was strengthened when the nerve cells were cocultured with enteroendocrine cells to induce an autocrine/paracrine environment. In summary, oral berberine exerted anti-arthritic effect through inhibiting the Th17 cell response, which was closely associated with the induction of cortistatin generation from gut through augmenting autocrine/paracrine action between enteric nerve cells and endocrine cells.

Obesity- and gender-dependent role of endogenous somatostatin and cortistatin in the regulation of endocrine and metabolic homeostasis in mice

Somatostatin (SST) and cortistatin (CORT) regulate numerous endocrine secretions and their absence [knockout (KO)-models] causes important endocrine-metabolic alterations, including pituitary dysregulations. We have demonstrated that the metabolic phenotype of single or combined SST/CORT KO-models is not drastically altered under normal conditions. However, the biological actions of SST/CORT are conditioned by the metabolic-status (e.g. obesity). Therefore, we used male/female SST- and CORT-KO mice fed low-fat (LF) or high-fat (HF) diet to explore the interplay between SST/CORT and obesity in the control of relevant pituitary-axes and whole-body metabolism. Our results showed that the SST/CORT role in the control of GH/prolactin secretions is maintained under LF- and HF-diet conditions as SST-KOs presented higher GH/prolactin-levels, while CORT-KOs displayed higher GH- and lower prolactin-levels than controls under both diets. Moreover, the impact of lack of SST/CORT on the metabolic-function was gender- and diet-dependent. Particularly, SST-KOs were more sensitive to HF-diet, exhibiting altered growth and body-composition (fat/lean percentage) and impaired glucose/insulin-metabolism, especially in males. Conversely, only males CORT-KO under LF-diet conditions exhibited significant alterations, displaying higher glucose-levels and insulin-resistance. Altogether, these data demonstrate a tight interplay between SST/CORT-axis and the metabolic status in the control of endocrine/metabolic functions and unveil a clear dissociation of SST/CORT roles.

Large Cell Neuroendocrine Carcinoma of the Gallbladder: A Case Report and Literature Review

Large cell neuroendocrine carcinoma (LCNEC) of the gallbladder is exceedingly rare. Only a few studies of pure gallbladder LCNEC without other histologic components have been reported in the literature. Therefore, this condition's biological behavior, appropriate treatment modalities, and overall patient prognosis remain largely unclear. In this report, we present a case involving resected pure gallbladder LCNEC. Additionally, we review relevant literature on LCNEC and discuss the clinical management of LCNEC, including histopathologic features. An 86-year-old woman presented with a gallbladder tumor that measured 25 mm on the body of the gallbladder that was incidentally detected by abdominal ultrasonography. The diagnosis of pure LCNEC without other histologic components was immunohistochemically confirmed after radical cholecystectomy and lymph node dissection in the hepatoduodenal ligament. The postoperative course was uneventful, and no evidence of recurrence or metastasis was observed after 6 months of follow-up. We reviewed 9 case reports describing pure LCNEC of the gallbladder, including the present case. Clinical symptoms and radiologic findings for pure LCNEC were nonspecific. The overall prognosis was poor, but early detection with complete resection might result in a relatively good prognosis.

Medical treatment for gastro-entero-pancreatic neuroendocrine tumours

Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) represents a various family of rare tumours. Surgery is the first choice in GEP-NENs patients with localized disease whilst in the metastatic setting many other treatment options are available. Somatostatin analogues are indicated for symptoms control in functioning tumours. Furthermore they may be effective to inhibit tumour progression. GEP-NENs pathogenesis has been extensively studied in the last years therefore several driver mutations pathway genes have been identified as crucial factors in their tumourigenesis. GEP-NENs can over-express vascular endothelial growth factor (VEGF), basic-fibroblastic growth factor, transforming growth factor (TGF-α and -β), platelet derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1) and their receptors PDGF receptor, IGF-1 receptor, epidermal growth factor receptor, VEGF receptor, and c-kit (stem cell factor receptor) that can be considered as potential targets. The availability of new targeted agents, such as everolimus and sunitinib that are effective in advanced and metastatic pancreatic neuroendocrine tumours, has provided new treatment opportunities. Many trials combing new drugs are ongoing.

Lack of cortistatin or somatostatin differentially influences DMBA-induced mammary gland tumorigenesis in mice in an obesity-dependent mode

Background

Somatostatin (SST) and cortistatin (CORT), two structurally and functionally related peptides, share a family of widespread receptors (sst1-5) to exert apparently similar biological actions, including endocrine/metabolic regulation and suppression of tumor cell proliferation. However, despite their therapeutic potential, attempts to apply SST-analogs to treat breast cancer have yielded unsatisfactory results. Actually, the specific roles of SST and CORT in mammary gland tumorigenesis (MGT), particularly in relation to metabolic dysregulation (i.e. obesity), remain unknown.

Methods

The role of endogenous SST and CORT in carcinogen-induced MGT was investigated under normal (lean) and obesity conditions. To that end, SST- and CORT-knockout (KO) mice and their respective littermate-controls, fed low-fat (LF) or high-fat (HF) diets, were treated with 7,12-dimethyl-benza-anthracene (DMBA) once a week (wk) for 3 wk, and MGT was monitored for 25 wk. Additionally, we examined the effect of SST or CORT removal in the development of the mammary gland.

Results

Lack of SST did not alter DMBA-induced MGT incidence under lean conditions; conversely, lack of endogenous CORT severely aggravated DMBA-induced MGT in LF-fed mice. These differences were not attributable to altered mammary gland development. HF-diet modestly increased the sensitivity to DMBA-induced carcinogenesis in control mice, whereas, as observed in LF-fed CORT-KO, HF-fed CORT-KO mice exhibited aggravated tumor incidence, discarding a major influence of obesity on these CORT actions. In marked contrast, HF-fed SST-KO mice exhibited much higher tumor incidence than LF-fed SST-KO mice, which could be associated with higher mammary complexity.

Conclusions

Endogenous SST and CORT distinctly impact on DMBA-induced MGT, in a manner that is strongly dependent on the metabolic/endocrine milieu (lean vs. obese status). Importantly, CORT, rather than SST, could represent a major inhibitor of MGT under normal/lean-conditions, whereas both neuropeptides would similarly influence MGT under obesity conditions. The mechanisms mediating these different effects likely involve mammary development and hormones, but the precise underlying factors are still to be fully elucidated. However, our findings comprise suggestive evidence that CORT-like molecules, rather than classic SST-analogs, may help to identify novel tools for the medical treatment of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0689-1) contains supplementary material, which is available to authorized users.

Structure-activity relationship for peptídic growth hormone secretagogues

Growth hormone releasing peptides (GHRPs) could be widely used by cheating athletes because they produce growth hormone (GH) secretion, so may generate an ergogenic effect in the body. Knowledge of the essential amino acids needed in GHRP structure for interaction with the target biological receptor GHSR1a, the absorption through different administration routes, and the maintenance of pharmacological activity of potential biotransformation products may help in the fight against their abuse in sport. Several GHRPs and truncated analogues with the common core Ala-Trp-(D-Phe)-Lys have been studied with a radio-competitive assay for the GHSR1a receptor against the radioactive natural ligand ghrelin. Relevant chemical modifications influencing the activity for positions 1, 2, 3, and 7 based on the structure aa-aa-aa-Ala-Trp-(D-Phe)-Lys have been obtained. To test in vivo the applicability of the activities observed, the receptor assay activity in samples from excretion studies performed after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin was confirmed. Overall results obtained allow to infer structure-activity information for those GHRPs and to detect GHSR1a binding (intact GHRPs plus active metabolites) in excreted urines. Copyright © 2016 John Wiley & Sons, Ltd.

Programming Bioactive Architectures with Cyclic Peptide Amphiphiles

We present a versatile approach for the synthesis of cyclic peptide amphiphiles of the hormone somatostatin (SST) with tunable lipophilic tails to program bioactive nanoarchitectures. A novel bis-alkylation reagent is synthesized that facilitates the functionalization of SST with a thiol anchor. Different hydrophobic moieties are introduced inspired by a biomimetic palmitoylation approach which opens access to cyclic peptide amphiphiles that display rich self-organization and cell membrane interactions.

Somatostatin receptor based imaging and radionuclide therapy

Somatostatin (SST) receptors (SSTRs) belong to the typical 7-transmembrane domain family of G-protein-coupled receptors. Five distinct subtypes (termed SSTR1-5) have been identified, with SSTR2 showing the highest affinity for natural SST and synthetic SST analogs. Most neuroendocrine tumors (NETs) have high expression levels of SSTRs, which opens the possibility for tumor imaging and therapy with radiolabeled SST analogs. A number of tracers have been developed for the diagnosis, staging, and treatment of NETs with impressive results, which facilitates the applications of human SSTR subtype 2 (hSSTr2) reporter gene based imaging and therapy in SSTR negative or weakly positive tumors to provide a novel approach for the management of tumors. The hSSTr2 gene can act as not only a reporter gene for in vivo imaging, but also a therapeutic gene for local radionuclide therapy. Even a second therapeutic gene can be transfected into the same tumor cells together with hSSTr2 reporter gene to obtain a synergistic therapeutic effect. However, additional preclinical and especially translational and clinical researches are needed to confirm the value of hSSTr2 reporter gene based imaging and therapy in tumors.

Comparison of immunoreactive score, HER2/neu score and H score for the immunohistochemical evaluation of somatostatin receptors in bronchopulmonary neuroendocrine neoplasms

AIMS

Due to the growing number of somatostatin receptor (SSTR) targeting analogues and radiopeptides used for the diagnosis and therapy of neuroendocrine neoplasms (NEN), the assessment of SSTR subtype status has increasingly gained predictive value. In pathology, the SSTR protein levels are detected routinely by immunohistochemistry (IHC); however, a lack of a standardized evaluation system persists. Thus, in the present investigation, three well-established semi-quantitative scoring systems [immunoreactive score (IRS), human epidermal growth factor receptor 2 (HER2)/neu score, H score] used commonly for SSTR-IHC evaluation in NEN were compared.

METHODS AND RESULTS

A total of 240 formalin-fixed, paraffin-embedded tumour samples from 90 patients with bronchopulmonary NEN were examined by IHC and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for SSTR1, 2A, 3, 4 and 5 expression. Using both methods, SSTR1, 2A and 5 were the most frequently expressed subtypes. For all SSTR subtypes, all three scores correlated well with each other and with qRT-PCR data. However, the IRS was the most meaningful score with the best correlation to mRNA levels.

CONCLUSIONS

Because a unified IHC scoring system for SSTR analysis is needed urgently to optimize the theranostics of NEN, among the scores tested, the IRS seems to be the most suitable according to our results. It provides sufficient accuracy combined with high practicability.

Somatostatin receptors in bronchopulmonary neuroendocrine neoplasms: new diagnostic, prognostic, and therapeutic markers

CONTEXT AND OBJECTIVES

Gastroenteropancreatic neuroendocrine neoplasms are known for their overexpression of somatostatin receptors (SSTRs), which provide the molecular basis for diagnostic and therapeutic interventions. In contrast, few data on the SSTR expression profile exist for bronchopulmonary neuroendocrine neoplasms (BP-NEN).

DESIGN AND SETTINGS

A total of 240 formalin-fixed, paraffin-embedded specimens from 26 typical carcinoid (TC), 30 atypical carcinoid (AC), and 34 small cell lung cancer (SCLC) patients were examined retrospectively by immunohistochemistry (IHC) using specific rabbit monoclonal antibodies and evaluated by the immunoreactive score. Adjacent slides from 20 samples of each tumor type were subjected to additional RT-quantitative PCR mRNA analysis.

RESULTS

With different expression patterns, SSTRs were present in most of the tumor sections, at both the protein and mRNA levels. The RT-quantitative PCR data correlated with the IHC scores. SSTR1 was detected in approximately 65% of the TC and AC, but hardly in the SCLC, whereas both SSTR2A and SSTR5 were present in approximately 45% of each entity. Furthermore, the SSTR1 expression level was positively correlated with patient survival.

CONCLUSIONS

Our results suggest that SSTRs can be used as novel diagnostic, prognostic, and therapeutic markers of BP-NEN. The differences in the SSTR expression profile between the three types of BP-NEN may help to set a diagnostic cutoff and predict patient prognosis. Similar to TC and AC, our results also revealed a previously unappreciated high level of SSTR2A expression in SCLC within a subgroup of patients. However, in most cases, pan-somatostatin analogs may represent an additional therapeutic option.

Drug delivery and release systems for targeted tumor therapy

Most toxic agents currently used for chemotherapy show a narrow therapeutic window, because of their inability to distinguish between healthy and cancer cells. Targeted drug delivery offers the possibility to overcome this issue by selectively addressing structures on the surface of cancer cells, therefore reducing undesired side effects. In this broad field, peptide-drug conjugates linked by intracellular cleavable structures have evolved as highly promising agents. They can specifically deliver toxophores to tumor cells by targeting distinct receptors overexpressed in cancer. In this review, we focus on these compounds and describe important factors to develop a highly efficient peptide-drug conjugate. The necessary properties of tumor-targeting peptides are described, and the different options for cleavable linkers used to connect toxic agents and peptides are discussed, and synthetic considerations for the introduction of these structures are reported. Furthermore, recent examples and current developments of peptide-drug conjugates are critically evaluated with a special focus on the applied linker structures and their future use in cancer therapy.

Lanreotide-conjugated PEG-DSPE micelles: an efficient nanocarrier targeting to somatostatin receptor positive tumors

Lanreotide is an octapeptide analog of endogenous somatostatin, specifically binding with tumors over-express somatostatin receptor 2 (SSTR2). In this study, we conjugated lanreotide to 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (poly-(ethylene glycol))-2000] (PEG-DSPE), constructed active targeted micelles (lanreotide-PM), characterized their in vitro and in vivo targeting effect, and explored the receptor mediated transportion. The uptake of lanreotide-PM was found to be related to the expression level of SSTR2 in different cell lines and the competitive inhibition phenomenon indicated that the cellular uptake of lanreotide-PM was via a receptor meditated mechanism. In vivo, more lanreotide-PM accumulated in SSTR2 high expression tumor xenografts, endocytosed by the tumor cells, induced more apoptosis of tumor cells, and suppressed tumor growth efficiently. In conclusion, lanreotide-modified micelles containing antitumor drugs provide a promising strategy for the treatment of SSTR-expressing tumors.

A disulfide intercalator toolbox for the site-directed modification of polypeptides

A disulfide intercalator toolbox was developed for site-specific attachment of a broad variety of functional groups to proteins or peptides under mild, physiological conditions. The peptide hormone somatostatin (SST) served as model compound for intercalation into the available disulfide functionalization schemes starting from the intercalator or the reactive SST precursor before or after bioconjugation. A tetrazole-SST derivative was obtained that undergoes photoinduced cycloaddition in mammalian cells, which was monitored by live-cell imaging.

Frequency and characterization of gastro-entero-pancreatic neuroendocrine tumor patients with high-grade of uptake at somatostatin receptor scintigraphy

Recent studies suggest that the somatostatin receptor scintigraphy (SRS) grade of uptake is a predictor of response to peptide receptor radionuclide therapy (PRRT). To identify and characterize patients with well-differentiated (WD) neuroendocrine neoplasm (NEN) displaying a high-grade uptake at SRS. Patients with WD-NEN, whose SRS films were available for review, were retrospectively included. SRS was reviewed by three independent readers and classified into four subgroups based on a modified Krenning's scale (mKS): no uptake (group-0), homogeneous grade 1-2 uptake (group-1), homogeneous grade 3-4 (group-2), and heterogeneous grade 1-4 (group-3). A simplified scale (sS) of SRS was also used to look for characteristics of patients with high-grade uptake. One hundred and six WD-NEN patients were enrolled. Group-0, group-1, group-2, and group-3 were found in 17, 8, 33, and 42% of cases respectively. High-grade uptake at sS (75% of cases) was correlated with older age, functioning NEN, high chromogranin-A level, and grade 1 (G1) NEN based on mitotic count. Based on the mKS or sS scales, no difference on survival was found. Thirty-three to seventy-five percent of metastatic NEN patients can be considered candidates for PRRT based on homogeneous or heterogeneous high-grade uptake. Functioning G1 NEN patients could be the best candidates for PRRT. Randomized trials are expected to confirm this result.

Somatostatin derivative (smsDX) targets cellular metabolism in prostate cancer cells after androgen deprivation therapy

Cancer cell metabolism responsive to androgen deprivation therapy (ADT) may be involved in the development and progression of prostate cancer and the ultimate failure of androgen-deprivation therapy. To investigate the metabolism regulation effects on androgen-independent growth of prostate cancer, an established LNCaP-s cell model that resembles the clinical scenario of castration-resistant prostate cancer (CRPC), was used in this current study. This cell line was cultured from androgen-sensitive LNCaP parental cells, in an androgen-reduced condition, resembling clinical androgen deprivation therapy. To assess the effects of smsDX on the invasiveness of prostate cancer cells we used wound healing assay and Matrigel™ invasion assay. We evaluated differentially expressed proteins of the parental LNCaP cells and LNCaP-s cells after ADT by means of two-dimensional gel electrophoresis (2-DE) followed by MALDI-TOF mass spectrometric analysis. The covered area in the wound and the number of cells invading through a Matrigel chamber were significantly smaller for cells treated with smsDX than they were for control cells treated with vehicle. 56 proteins were found differentially expressed in LNCaP-s cells compared to LNCaP cells, majority of them were down-regulated after ADT treatment. 104 proteins of LNCaP cells and 86 in LNCaP-s cells, separately, were found differentially expressed after treatment with smsDX, When we explored these protein functions within the website UniProtKB/Swiss-Prot, surprisingly, most of the proteins were found to be involved in the cellular metabolism and mitochondrial function regulation. LNCaP-s as potential metastatic androgen-independent cancer cells, its metabolism and mitochondrial functions could be altered by a new somatostatin derivative smsDX, the smsDX regulatory effects on metabolism in LNCaP-s deliver more therapeutic information with the treatment of CRPC.

Virotherapy of neuroendocrine tumors

Most patients with small intestinal neuroendocrine tumors (SI-NETs), also referred to as midgut carcinoids, present with systemic disease at the time of diagnosis with metastases primarily found in regional lymph nodes and the liver. Curative treatment is not available for these patients and there is a need for novel and specific therapies. Engineered oncolytic viruses may meet the need and play an important role in the future management of SI-NET liver metastases. This review focuses on adenovirus as the oncolytic anti-cancer agent and its potential curative role for SI-NET liver metastases, but it also summarizes the use of oncolytic viruses for NETs in general. It discusses how specific features of neuroendocrine cell biology can be used to engineer viruses to become selective for infection of NET cells and/or replication within NET cells. In addition, it points out the advantages and shortcomings of using replicating viruses in the treatment of cancer and addresses research fields that can increase the efficacy of virus-based therapy.

Peptide targeted lipid nanoparticles for anticancer drug delivery

Encapsulating anticancer drugs in nanoparticles has proven to be an effective mechanism to alter the pharmacokinetic and pharmacodynamic profiles of the drugs, leading to clinically useful cancer therapeutics like Doxil and DaunoXome. Underdeveloped tumor vasculature and lymphatics allow these first-generation nanoparticles to passively accumulate within the tumor, but work to create the next-generation nanoparticles that actively participate in the tumor targeting process is underway. Lipid nanoparticles functionalized with targeting peptides are among the most often studied. The goal of this article is to review the recently published literature of targeted nanoparticles to highlight successful designs that improved in vivo tumor therapy, and to discuss the current challenges of designing these nanoparticles for effective in vivo performance.

Somatostatin and somatostatin analogues reduce PDGF-induced endometrial cell proliferation and motility

BACKGROUND

Endometriosis is characterized by ectopic implantation of endometrial cells, which show increased proliferation and migration. Somatostatin (SST) and its analogues inhibit normal and cancer cell growth and motility through the SST receptors, sst1-5. Cortistatin (CST), which displays high structural and functional homology with SST, binds all ssts, as well as MrgX2. Our objective was to investigate the gene expression of the SST/CST system and to determine the effect of SST and its analogues on platelet-derived growth factor (PDGF)-induced proliferation and motility in telomerase-immortalized human endometrial stromal cell (T HESC) line and in primary endometrial stromal cell (ESCs) isolated from human endometriotic tissues.

METHODS

Ectopic endometrial tissues were collected from women (n= 23) undergoing laparoscopic surgery for endometriosis (Stage III/IV). Gene expression was evaluated by real-time PCR, cell motility by wound healing assay, protein expression and β-actin rearrangement by immunofluorescence, cell proliferation by the Alamar blue assay and ERK1/2 and Akt phosphorylation by western blot.

RESULTS

Human endometriotic tissues, primary ESCs and T HESCs expressed SST, CST and ssts. SST, its analogues SOM230 and octreotide, as well as CST, counteracted PDGF-induced proliferation and migration in both ESCs and T HESCs. SST also inhibited vascular endothelial growth factor and metalloprotease-2 mRNA expression, and reduced basal and PDGF-induced ERK1/2 phosphorylation.

CONCLUSION

These results indicate that the SST/CST system is expressed in endometriotic tissues and cells. The inhibitory effects of SST and its analogues on PDGF-induced proliferation and motility suggest that these peptides may represent promising tools in the treatment of endometriosis.

The role of somatostatin and dopamine D2 receptors in endocrine tumors

Somatostatin (SS) and dopamine (DA) receptors have been highlighted as two critical regulators in the negative control of hormonal secretion in a wide group of human endocrine tumors. Both families of receptors belong to the superfamily of G protein-coupled receptors and share a number of structural and functional characteristics. Because of the generally reported high expression of somatostatin receptors (SSTRs) in neuroendocrine tumors (NET), somatostatin analogs (SSA) have a pronounced role in the medical therapy for this class of tumors, especially pituitary adenomas and well-differentiated gastroenteropancreatic NET (GEP NET). Moreover, NET express not only SSTR but also frequently dopamine receptors (DRs), and DA agonists targeting the D(2) receptor (D(2)) have been demonstrated to be effective in controlling hormone secretion and cell proliferation in in vivo and in vitro studies. The treatment with SSAs combined with DA agonists has already been demonstrated efficacious in a subgroup of patients with GH-secreting pituitary adenomas and few reported cases of carcinoids. The recent availability of new selective and universal SSA and DA agonists, as well as the chimeric SS/DA compounds, may shed new light on the potential role of SSTR and D(2) as combined targets for biotherapy in NET. This review provides an overview of the latest studies evaluating the expression of SSTR and DR in NET, focusing on their co-expression and the possible clinical implications of such co-expression. Moreover, the most recent insights in SSTR and D(2) pathophysiology and the future perspectives for treatment with SSA, DA agonists, and SS/DA chimeric compounds are discussed.

Long acting somatostatin analogues in combination to antineoplastic agents in the treatment of small cell lung cancer patients

BACKGROUND

Long acting somatostatin analogues combined with platinum analogues have demonstrated an antiproliferative effect on growth of human SCLC xenographs.

METHOD

130 previously untreated SCLC patients--54 with limited disease (LD) and positive somatostatin receptors were included in the study. All patients performed 111In-Octreotide scanning before chemotherapy (CHT), every 3 months and up to 4 times. All patients were treated with paclitaxel 190 mg/m2+carboplatin AUC=5.5 for up to 6 cycles. 47/130 patients (Group A, control group) received only CHT. Forty eight hours after each CHT 43/130 patients (Group B) were also administered 30 mg somatuline® (lanreotide) by a single subcutaneous (s.c.) injection to stimulate somatostatin receptors (SSTRS) for 2 weeks. 40/130 patients (Group C) received 60 mg somatuline® autogel to stimulate SSTRS for 4 weeks. Patients in Groups A and B after the completion of the CHT continued maintenance therapy with somatuline. NSE, IGF1, VEGFA, VEGFC, VEGFR2, HER2 levels were monitored. In histological samples Bcl-2 and VEGF were also explored by immunohistochemistry.

RESULTS

No statistically significant differences were observed between the 3 Groups regarding LD and extensive disease (ED) patient ratios, age and PS. Group B had a survival benefit in comparison to Groups A and C (p=0.029). LD patients of Group B had a significant benefit compared to Groups A and C (p=0.012, Breslow test). In LD Group B had a significant longer TTP (p=0.02) in comparison to Groups A and C. Adverse effects had no statistically significant difference between the Groups and toxicity was well managed.

INTERPRETATION

Long acting somatostatin analogues could be used as an additive therapy in combination to antineoplastic agents in patients positive for somatostatin receptors. A dose of 30 mg improved survival only in LD SCLC patients.

Reflections on the theory of "silver bullet" octreotide tracers: implications for ligand-receptor interactions in the age of peptides, heterodimers, receptor mosaics, truncated receptors, and multifractal analysis

The classical attitude of Nuclear Medicine practitioners on matters of peptide-receptor interactions has maintained an intrinsic monogamic character since many years. New advances in the field of biochemistry and even in clinical Nuclear Medicine have challenged this type of thinking, which prompted me to work on this review. The central issue of this paper will be the use of somatostatin analogs, i.e., octreotide, in clinical imaging procedures as well as in relation to neuroendocirne tumors. Newly described characteristics of G-protein coupled receptors such as the formation of receptor mosaics will be discussed. A small section will enumerate the regulatory processes found in the cell membrane. Possible new interpretations, other than tumor detection, based on imaging procedures with somatostatin analogs will be presented. The readers will be taken to situations such as inflammation, nociception, mechanosensing, chemosensing, fibrosis, taste, and vascularity where somatostatin is involved. Thyroid-associated orbitopathy will be used as a model for the development of multi-agent therapeutics. The final graphical summary depicts the multifactorial properties of ligand binding.

Performance of (18)fluorodeoxyglucose-positron emission tomography and somatostatin receptor scintigraphy for high Ki67 (≥10%) well-differentiated endocrine carcinoma staging

OBJECTIVE

The purpose of this prospective study was to compare the performance of (111)In-octreotide somatostatin receptor scintigraphy (SRS) and (18)fluorodesoxyglucose positron emission tomography (FDG-PET) in aggressive well-differentiated endocrine carcinoma (WDEC) defined by a high Ki67 (≥10%).

METHODS

Eighteen consecutive patients explored in a single hospital between November 2003 and 2008 for high Ki67 (≥10%) WDEC were prospectively included. WDEC were sporadic in 17 cases and secreting in 16 cases. FDG-PET, SRS, and computed tomography (CT) were performed within a maximum of 3 months and reviewed by two independent readers. For each patient, an analysis per organ and lesion was performed. Both the results of conventional imaging and the highest number of metastatic organs and distinct lesions visualized by all imaging methods including SRS, FDG-PET, and thoraco-abdomino-pelvic CT were considered for the determination of the standard. Correlation between tumor slope and maximum standardized uptake value, Ki67 value, and grade of uptake at SRS was evaluated.

RESULTS

FDG-PET, SRS, and CT showed at least one lesion in 18 (100%), 15 (83%), and 17 (94%) patients, respectively. A total of 254 lesions were diagnosed in 59 organs. FDG-PET, SRS, and CT detected 195 (77%), 109 (43%), and 195 (77%) lesions in 53 (90%), 30 (51%), and 39 (66%) organs, respectively. FDG-PET, compared to SRS, detected more, the same as, and less lesions in 14 (78%), one (6%), and three (17%) patients, respectively. A statistical trend was found between Ki67 value and tumor slope (P = 0.07). Median survival after diagnosis was 25 months (range, 6-71 months).

CONCLUSION

These results suggest that FDG-PET is more sensitive than the SRS for high Ki67 WDEC staging.

Androgen-responsive and -unresponsive prostate cancer cell lines respond differently to stimuli inducing neuroendocrine differentiation

The treatment of advanced prostate cancer (CaP) with androgen deprivation therapy inevitably renders the tumours castration resistant and incurable. Under these conditions, neuroendocrine differentiation (NED) of CaP cells occurs and neuropeptides released by neuroendocrine cells facilitate tumour progression. Pharmacological strategies aiming to prevent or delay NED during androgen ablation could, therefore, increase the effectiveness of the therapy. Mechanisms and pathways inducing NED in CaP are poorly understood and data are often discordant. In the present study, we used several CaP cell lines (androgen-responsive: LNCaP, PC3-AR, 22RV1 and -irresponsive: DU145 and PC3) to evaluate NED after androgen deprivation or treatment with epidermal growth factor (EGF). NED was determined by neuron-specific enolase and chromogranin A expression and by the occurrence of morphological changes in the cells. Androgen-deprivation conditions induced NED in LNCaP and PC3-AR, but not in 22Rv1, PC3 and DU145 cells. LNCaP and PC3-AR cells also became resistant to thapsigargin-induced apoptosis. In all the AR-positive cell lines, androgen deprivation caused a decrease in androgen receptor expression indicating that it is downregulated irrespective of NED induction. Treatment with EGF induced NED in DU145 cells and the EGF receptor inhibitor gefinitib prevented the process. On the contrary, no effect of EGF was demonstrated in LNCaP or 22Rv1 cells. CaP cell lines did not respond univocally to treatments inducing NED, suggesting that studies on this topic should be performed in a wide spectrum of cell models which can be more indicative of the tumour variability in vivo.

A novel octreotide modified lipid vesicle improved the anticancer efficacy of doxorubicin in somatostatin receptor 2 positive tumor models

Octreotide (Oct) is a potential ligand due to its high affinity to somatostatin receptors (SSTRs), especially subtype 2 (SSTR2), as many tumor cells specifically overexpress SSTR2. In this study, we conjugated Oct to the PEG end of DSPE-PEG and prepared a novel doxorubicin (DOX)-loaded and Oct-modified sterically stabilized liposomes (Oct-SSL-DOX), in order to facilitate intracellular delivery of chemotherapeutic agent to the related tumor cells through active targeting and finally improve its antitumor activity. Three cells were proved to be different in expression level of SSTR2 and were used as model or control. It was demonstrated by fluorescence spectrophotometry, confocal laser scanning microscopy and flow cytometry that active sterically stabilized liposomes (SSL) increased intracellular delivery of DOX in SSTR2-positive cells, through a mechanism of receptor-mediated endocytosis. Compared to SSL, Oct modification on SSL exhibited little effect on the physicochemical properties of SSL. However, it reduced the circulation time of loaded-DOX to some extent in rats, increased cytotoxicity in SSTR2-positive tumor cells, enhanced drug accumulation in tumor tissue and improved anticancer efficacy in SSTR2-overexpressing tumor model. The correlation was found among intracellular uptake, cytotoxicity, drug distribution in tumor and pharmacodynamics of Oct-SSL-DOX, but not the pharmacokinetics based on plasma drug concentration. In summary, octreotide-modified SSL might be a promising system for the treatment of SSTR2-overexpressing cancers.

Somatostatin receptor 2 expression determined by immunohistochemistry in cold thyroid nodules exceeds that of hot thyroid nodules, papillary thyroid carcinoma, and Graves' disease

BACKGROUND

There is a plethora of partly contradictory reports on somatostatin receptor (SSTR) expression in thyroid tumors. Therefore, our goal was to systematically determine SSTR2 expression in benign cold thyroid nodules (CNs), hot thyroid nodules (HNs), papillary carcinomas (PCs), and Graves' disease (GD) in comparison with intraindividual control tissues by means of immunohistochemistry.

METHODS

Tissue sections from 19 HNs, 10 CNs, 17 PCs and their surrounding tissues, and 8 GD thyroids were immunostained for SSTR2. Membranous SSTR2 staining was quantitated by evaluating 10 high-power fields (HPFs) systematically distributed along the largest diameter of the tissue section.

RESULTS

The area covered by thyroid epithelial cells in 10 HPFs expressed as median (in mm(2)) was 0.53 for CNs, 0.44 for HNs, 1.5 for PCs, 1.3 for GD, and 0.3 for the surrounding tissues. The SSTR2 staining density determined by dividing the area of SSTR2 positively stained thyroid epithelial cells (in mm(2)) by the area of all thyroid epithelial cells (in mm(2)) in 10 HPFs was 0.1662 for CNs, 0.0204 for HNs, 0.0369 for PCs, and 0.0386 for GD.

CONCLUSIONS

SSTR2 expression is inhomogeneous in thyroid disease, with the highest density detected in CNs. It remains to be determined whether this finding could be of pathophysiologic or therapeutic relevance. The high SSTR2 density in CNs should be considered in the interpretation of SSTR scintigraphy-positive findings.

Identification and characterization of two novel truncated but functional isoforms of the somatostatin receptor subtype 5 differentially present in pituitary tumors

CONTEXT

Somatostatin and its related peptide cortistatin exert multiple actions on normal and tumoral tissue targets through a family of receptors termed somatostatin receptor (sst)1-5. Despite the considerable advances in the knowledge on these receptors and their (patho)physiological roles, there is still evidence that additional receptors for these peptides should exist to fully explain their actions.

OBJECTIVE

The growing number of spliced variants found in similar receptor families, often present in tumors, and results from our group obtained on sst5 from other species (pig) led us to explore the existence of new human sst5 isoforms.

DESIGN AND RESULTS

A rapid amplification of cDNA ends PCR approach on samples from a human pituitary tumor and a cell line enabled identification of two novel alternatively spliced sst5 receptor variants. The sequences obtained encode putative proteins that correspond to truncated isoforms of five and four transmembrane domains (TMDs), accordingly named sst5TMD5 and sst5TMD4, respectively. Both novel receptors show a differential expression pattern in normal tissues and are also present in pituitary tumors of diverse etiology including nonfunctioning adenomas, corticotropinomas, somatotropinomas, and a prolactinoma. In contrast to the predominant plasma membrane localization of full-length sst5, both sst5TMD5 and sst5TMD4 show a preferentially intracellular localization. Despite their truncated nature, both receptors are functional, as shown by their ability to mediate selective, ligand-induced rises in free cytosolic calcium concentration. Specifically, whereas sst5TMD5 is selectivity activated by somatostatin compared with cortistatin, cells transfected with sst5TMD4 almost exclusively respond to cortistatin and not to somatostatin.

CONCLUSIONS

Our results demonstrate the existence of two previously unidentified sst5 spliced variants with distinct distribution in normal tissues and pituitary tumors, unique ligand-selective signaling properties, and subcellular distribution, which could contribute to somatostatin and cortistatin signaling in normal and tumoral cells.

Cortistatin vaccination--a solution to growth hormone deficiency

Cortistatin and somatostatin are neuropeptides which have inhibitory effects on growth hormone through common five receptors. Although, both have inhibitory effects but, only cortistatin has direct inhibitory effects on growth hormone secretagogue and is more potent inhibitor of growth hormone than somatostatin. This control of growth hormone can be manipulated through immunoneutralization of cortistatin through cortistatin DNA vaccine rather than antibodies application. A DNA vaccine of cortistatin can be produced using recombinant DNA technology in a eukaryotic expression system and will serve as a tool not to only alleviate the growth hormone deficiency problems in human but, can also be used to improve growth rate in farm animals.