Preclinical evaluation of a CXCR4-specific 68Ga-labelled TN14003 derivative for cancer PET imaging

Molecular imaging is an ideal platform for non-invasive detection and assessment of cancer. In recent years, the targeted imaging of CXCR4, a chemokine receptor that has been associated with tumour metastasis, has become an area of intensive research. In our pursuit of a CXCR4-specific radiotracer, we designed and synthesised a novel derivative of the CXCR4 peptidic antagonist TN14003, CCIC16, which is amenable to radiolabelling by chelation with a range of PET and SPECT radiometals, such as ⁶⁸Ga, ⁶⁴Cu and ¹¹¹In as well as ¹⁸F (Al¹⁸F). Potent in vitro binding affinity and inhibition of signalling-dependent cell migration by unlabelled CCIC16 were confirmed by a threefold uptake in CXCR4-over-expressing cells compared to their isogenic counterparts. Furthermore, in vivo experiments demonstrated the favourable pharmacokinetic properties of the ⁶⁸Ga-labelled tracer ⁶⁸Ga–CCIC16, along with its CXCR4-specific accumulation in tissues with desirable contrast (tumour-to-muscle ratio: 9.5). The specificity of our tracer was confirmed by blocking experiments. Taking into account the attractive intrinsic PET imaging properties of ⁶⁸Ga, the comprehensive preclinical evaluation presented here suggests that ⁶⁸Ga–CCIC16 is a promising PET tracer for the specific imaging of CXCR4-expressing tumours.     

Polypeptide growth factors in gastroenteropancreatic neuroendocrine tumours

Polypeptide growth factors form a potent class of extracellular signal molecules in the regulation of cellular differentiation and proliferation. Disturbances in the expression of growth factors influence the normal pathway of differentiation and lead to cellular transformation and tumour progression. Contemporary medical studies report that various growth factors such as those for platelet-derived growth factor, vascular endothelial growth factor, epidermal growth factor, hepatocyte growth factor and insulin-like growth factor are expressed in gastroenteropancreatic neuroendocrine tumours (GEP/NET). Polypeptide growth factors have great significance in the growth, progression and development of metastases by various tumours. We describe the role of growth factors in GEP/NET on the basis of the available reports of medical research.     

Surgical treatment of neuroendocrine tumours of the pancreas

Gastro-entero-pancreatic (GEP) endocrine tumours can originate from various pancreatic islet cells, from endocrine cells of the gastric and duodenal mucosa, or from APUD cells of neuroectodermal origin in the gastrointestinal tract. They are benign when smaller than 2 cm, but larger tumours are generally malignant. Surgery is the only method for the curative treatment of GEP tumours. A diagnosed and localised tumour is an absolute indication for radical surgery. Conservative medical treatment may be indicated only in an inoperable condition, but in this case tumour reduction surgery is suggested. In the last 15 years 22 patients with pancreatic neuroendocrine tumours were treated without any mortality. Except for two of them, the surgical therapy was curative.     

Proliferative activity of well differentiated neuroendocrine tumours of the gut

Neuroendocrine tumours of the gastrointestinal tract are relatively uncommon neoplasms with, in spite of their characteristic morphology, relatively unpredictable biological behaviour. In some sites, notably the appendix, these tumours are largely benign whereas at other localisations, such as the small bowel, metastases occur and the outcome is less favourable. Given the lack of discriminative power of histological parameters, immunohistochemical parameters have been proposed. Of these the Ki-67 index, as an indicator of proliferative activity, has shown some promise. In order to assess their proliferative activity and the potential contribution of this parameter to defining biological behaviour, we performed Ki-67 immunostaining of a series of 64 well differentiated neuroendocrine tumours of the gut (stomach, small bowel, appendix, colon and rectum). Ki-67 labeling index, based upon counting of up to 5000 cells, ranged between 0 and 6.1%. No difference was found according to age, gender, size, location or TNM classification. Ki-67 labeling index of midgut endocrine tumours of long term surviving patients did not differ from patients that died. We conclude that Ki-67 labeling index as an indicator of proliferative activity of well differentiated neuroendocrine tumours of the digestive tract does not correlate with size nor site nor stage. Even though only small numbers of tumours could be analysed, which hampered appropriate statistical analysis, it seems unlikely that proliferative activity has potential as an independent prognostic parameter for this type of tumour.     

Electron microscopy for the diagnosis of tumours.

The role of leukocyte transfusions in the prevention and treatment of infections in adults with granulocytopenia was investigated. Leukocytes were obtained from healthy volunteers by continuous-flow centrifugation. Histocompatibility antigen (HLA)-matched leukocytes were used to assess the prophylactic value of leukocyte transfusions. Seven patients with acute myelogenous leukemia received HLA-matched leukocytes during the period of maximal granulocytopenia associated with initial remission induction therapy; 20 concurrently treated patients who did not receive leukocyte transfusions were the control group. The patients receiving HLA-matched leukocytes had significantly fewer (P = 0.043) infectious episodes (not bacteriologically proven) during the study period, and remission occurred in 5 of the 7, compared with 10 of the 20 controls. In addition, 52 series of two or more ABO-compatible transfusions were given to 50 patients with proven infection or elevated temperature presumed due to infection and a granulocyte count of less than 0.5 X 10(9)/L. Response, indicated by a decrease in temperature, occurred in 23 patients. Leukocyte transfusions thus have an important adjuvant role in the management of patients with severe granulocytopenia.     

Expression of class III beta-tubulin in neuroendocrine tumours of gastrointestinal tract

Class III b-tubulin is presented as a specific marker for the cells of neuronal origin as well as for the tumours originating from these cells. Its expression is considered one of the earliest events that appear in the cells revealing neuronal differentiation. Using monoclonal antibody TU-20 in an immunohistochemical analysis, we studied the expression of class III b-tubulin in gastrointestinal carcinoid tumours. Paraffin-embedded, formalin-fixed tissue sections from 49 tumour samples obtained from following locations: stomach (4 cases), small intestine (8 cases), appendix (18 cases), rectum (3 cases), pancreas (5 cases), liver metastases (7 cases) and lymph node metastases (4 cases) were used in the study. In 41 of the 49 tumour samples (83.7%), positive staining for class III b-tubulin was detected, while 8 tumour samples (16.3%) were negative. Expression of class III b-tubulin was prominent in all three rectal carcinoids and in three atypical carcinoids located in small intestine. Pancreatic neuroendocrine tumours revealed either weak immunostaining (2 cases), or were negative for this marker (3 cases). The intensity of class III b-tubulin immunolabelling was not related to the degree of tumour differentiation. The results of this study suggest that class III b-tubulin could be a perspective marker for gastrointestinal neuroendocrine tumours. Moreover, the differences in its expression could also elucidate some aspects of histogenetic relationships of neuroendocrine tumours of gastrointestinal tract.     

Involvement of novel feeding-related peptides in neuroendocrine response to stress

Various stressors are known to cause eating disorders. However, it is not known in detail about the neural network and molecular mechanism that are involved in the stress-induced changes of feeding behavior in the central nervous system. Many novel feeding-regulated peptides such as orexins/hypocretins and ghrelin have been discovered since the discovery of leptin derived from adipocytes as a product of the ob gene. These novel peptides were identified as endogenous ligands of orphan G protein-coupled receptors. The accumulating evidence reveals that these peptides may be involved in stress responses via the central nervous system, as well as feeding behavior. The possible involvement of novel feeding-related peptides in neuroendocrine responses to stress is reviewed here.     

Barium distinguishes separate calcium targets for synthesis and secretion of peptides in neuroendocrine cells

The effect of barium and potassium on the secretion and biosynthesis of enkephalin in bovine chromaffin cells, and prolactin and beta-endorphin in rat anterior pituitary cells, was examined to determine whether calcium-dependent secretion and biosynthesis are mediated by the same or by different calcium targets within the neuroendocrine cell. In the presence of 1.8 mM calcium, barium and potassium stimulated the secretion of all three peptides over 30 min, and increased the levels of proenkephalin and prolactin mRNA in 24 hr. These effects were inhibited by the calcium channel blocker D600. When the extracellular calcium concentration was lowered to 0.1 mM or less, secretion elicited by potassium was blocked, whereas secretion elicited by barium was enhanced, indicating that barium wholly substitutes for extracellular calcium in mediating peptide secretion. On the other hand, stimulation of proenkephalin and prolactin mRNA by both potassium and barium was inhibited when the extracellular calcium concentration was reduced. We conclude that calcium acts at two different intracellular targets to activate secretion versus biosynthesis of both enkephalin and prolactin. This appears to be the first report in which two different calcium-dependent processes in the intact cell are distinguished by a calcium ion agonist. Calcium-dependent processes such as protein phosphorylation, protein translocation, and enzyme activation may thus be related to events in the intact cell such as peptide synthesis and secretion on the basis of selective stimulation by barium.     

Multivisceral resection of pancreatic neuroendocrine tumours: a report of two cases

Background

Compromised physiological reserve, comorbidities, and the natural history of pancreatic cancer may deny pancreatic resection from elderly patients. We evaluated outcomes of elderly patients amenable to pancreatic surgery.

Methods

The medical records of all patients who underwent pancreatic resection at our institution (1995-2007) were retrospectively reviewed. Patient, tumor, and outcomes characteristics in elderly patients aged ≥ 70 years were compared to a younger cohort (<70y).

Results

Of 460 patients who had surgery for pancreatic neoplasm, 166 (36%) aged ≥ 70y. Compared to patients < 70y (n = 294), elderly patients had more associated comorbidities; 72% vs. 43% (p = 0.01) and a higher rate of malignant pathologies; 73% vs. 59% (p = 0.002). Operative time and blood products consumption were comparable; however, elderly patients had more post-operative complications (41% vs. 29%; p = 0.01), longer hospital stay (26.2 vs. 19.7 days; p < 0.0001), and a higher incidence of peri-operative mortality (5.4% vs. 1.4%; p = 0.01). Multivariable analysis identified age ≥ 70y as an independent predictor of shorter disease-specific survival (DSS) among patients who had surgery for pancreatic adenocarcinoma (n = 224). Median DSS for patients aged ≥ 70y vs. < 70y were 15 months (SE: 1.6) vs. 20 months (SE: 3.4), respectively (p = 0.05). One, two, and 5-Y DSS rates for the cohort of elderly patients were 58%, 36% and 23%, respectively.

Conclusions

Properly selected elderly patients can undergo pancreatic resection with acceptable post-operative morbidity and mortality rates. Long term survival is achievable even in the presence of adenocarcinoma and therefore surgery should be seriously considered in these patients.     

Prognostic value of nucleolar organizer regions in neuroendocrine tumours of the lung

The value of the number and size of the nucleolar organizer regions (NORs) as prognostic indicators in human neuroendocrine lung tumours was evaluated in a quantitative study of 57 cases, including 33 small cell carcinomas (SCLCs), 9 well-differentiated neuroendocrine carcinomas (WDNECs) and 15 classic carcinoids. NORs were visualized on paraffin sections by an argyrophilic technique (AgNOR) and measured by automatic image analysis. In each case, the mean number and area of AgNORs were evaluated; the results were compared with clinical follow-up and survival. AgNOR values for both number and area were significantly higher in SCLCs than in WDNECs and carcinoids. WDNECs had insignificantly higher AgNOR values than carcinoids. Among SCLCs, AgNOR values of the oat cell subtype and the intermediate cell subtype did not differ significantly. Regardless of the histological tumour type, AgNOR values strongly correlated with prognosis, with more and larger AgNORs indicating a more progressive clinical course. In the present study we demonstrate for the first time that the biological behaviour of neuroendocrine lung tumours is correlated with the number and size of AgNORs. Thus the measurement of AgNORs may serve as an additional prognostic indicator in these neoplasms, particularly in the separation of SCLCs from WDNECs with a more favourable prognosis.     

Cytological diagnosis of soft tissue tumours

Cytological diagnosis of soft tissue tumours The aims of this study were to determine the patterns of soft tissue tumours and also to try to assess the utility of fine needle aspiration cytology (FNAC) in diagnosing soft tissue tumours. Of 15 361 patients who visited the cytology diagnostic service of the Pathology Department, Medical Faculty, Addis Ababa University, 623 (4.1%) cases with a diagnosis of soft tissue tumours were retrieved from the department's records for the years 1991-96. Fifty-three soft tissue tumours (25 benign and 28 malignant tumours) with combined FNAC and surgical biopsy results were traced for cyto-histological correlations. Twenty-two out of 25 benign soft tissue tumours were correctly diagnosed, with three false cytologic diagnoses where one mesenchmal neoplasm, one haemangioma, and one haemorragic lesion were identified; and out of 28 malignant soft tissue, 23 were correctly diagnosed however, the five false cytological diagnoses were one soft tissue sarcoma, one dermatofibrosarcoma, one malignant mesenchymal neoplasm, one spindle cell neoplasm and one menechymal neoplasm. Thus, in this study a sensitivity and specificity of 88.5% and 81.5% respectively for the diagnosis of soft tissue tumours were reported. In conclusion, FNAC of soft tissue tumours is a fast, effective and reliable diagnostic tool that may help in categorizing soft tissue tumours into benign and malignant groups for clinical management.     

Coexisting peptides in hypothalamic neuroendocrine systems: Some functional implications

1. Coexisting with oxytocin or vasopressin in the cell bodies and nerve terminals of the hypothalamic-neurohypophysial system are smaller amounts of other peptides. For a number of these "copeptides" there is strong evidence of corelease with the major magnocellular hormones. Guided by the location of their specific receptors we have studied the effects of three copeptides, dynorphin, cholecystokinin (CCK), and corticotropin releasing hormone (CRH), on the secretion of oxytocin and vasopressin from isolated rat neural lobe or neurointermediate lobe preparations in vitro. 2. Dynorphin is coreleased with vasopressin from neural lobe nerve terminals and acts on neural lobe kappa-opiate receptors to inhibit the electrically stimulated secretion of oxytocin. Naloxone augments oxytocin release from the neural lobe in a manner directly proportional to the amount of vasopressin (and presumably dynorphin) released. 3. Cholecystokinin, coreleased with oxytocin by neural lobe terminals, has been shown to have high-affinity receptors located in the NL and to stimulate secretion of both oxytocin and vasopressin. CCK's secretagogue effect was independent of electrical stimulation and extracellular Ca2+ and was blocked by an inhibitor of protein kinase C. 4. CRH, coreleased with OT from the neural lobe, has receptors in the intermediate lobe of the pituitary, but not in the neural lobe itself. CRH stimulates the secretion of oxytocin and vasopressin from combined neurointermediate lobes but not from isolated neural lobes. Intermediate lobe peptides, alpha and gamma melanocyte stimulating hormone, induced secretion of oxytocin and vasopressin from isolated neural lobes. Their effect was, like that of CCK, independent of electrical stimulation and extracellular Ca2+ and blocked by an inhibitor of protein kinase C. 5. Among the CRH-producing parvocellular neurons of the paraventricular nucleus, in the normal rat, approximately half also produce and store vasopressin. After removal of glucocorticoid influence by adrenalectomy, virtually all of the CRH neurons contain vasopressin. 6. The two subtypes of CRH neurosecretory cells found in the normal rat possess different topographical distributions in the paraventricular nucleus, suggesting the possibility of differential innervation. Stress selectively activates the vasopressin containing subpopulation of CRH neurons, indicating that there are separate channels of regulatory input controlling the two components of the parvocellular CRH neurosecretory system.