Regulation of circulating chromogranin B levels in heart failure.

BACKGROUND: Chromogranin B (CGB) regulates B-type natriuretic peptide (BNP) production. Circulating CGB levels are elevated in heart failure (HF) animal models and HF patients, but also increase in healthy individuals in response to physical activity. Therefore, CGB seems to integrate information from myocardial stress and systemic neuro-endocrine activation. Substantial gaps remain in our understanding of CGB regulation in HF. METHODS AND RESULTS: We conducted a retrospective registry study including 372 patients. CGB and N-terminal pro-BNP (NT-proBNP) plasma levels were assessed in acute HF and chronic valvular HF patients and controls. CGB levels were significantly increased in acute HF and chronic valvular HF, but significantly higher in the latter. Patients in chronic valvular HF with severe mitral regurgitation (cHF-MR) showed significantly higher CGB levels than patients in chronic valvular HF with severe aortic stenosis. CGB levels progressively increased with worsening NYHA functional status and were moderately correlated to NT-proBNP, but independent of left ventricular (LV) ejection fraction (LVEF), LV mass, age and body weight. Finally, cHF-MR patients showed significant reductions of CGB levels after interventional mitral valve repair. CONCLUSION: CGB is a promising emerging biomarker in HF patients with unique potential to integrate information from myocardial stress and neuro-endocrine activation.

Clinicopathological hallmarks and biomarkers of colorectal neuroendocrine neoplasms.

Chromogranin A (CgA) is a well-established marker for diagnosis and follow up of patients with gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). Recently, it has been shown that plasma levels of CgA correlate with tumor load and predict survival of patients with NEN of the small bowel. It is assumed that this is as well valid for NEN of the colon and rectum, however, this is not supported by data. To evaluate this assumption, we analyzed 62 patients with NEN of the colon and rectum listed in the Marburg GEP-NEN registry for clinicopathological characteristics, expression and plasma levels of CgA. The present study demonstrates that immunohistochemical CgA and synaptophysin are good markers for histological diagnosis in patients with NEN of the colon and rectum. However, plasma CgA is a poor marker to follow-up these patients because only a minority exhibited increased levels which did not increase significantly during tumor progression. In contrast to NEN of the small bowel, there is no correlation of CgA plasma levels with tumor burden or survival. Patients with NEN of the colon and rectum displayed a relatively good prognosis resulting in a median survival of 8.5 years. However, a subset of patients affected by G3 neoplasms, exhibited a poorer prognosis with a median survival of 2.5 years. Taken together, CgA is a valuable marker for immunohistochemical diagnosis, but CgA plasma concentration is not suitable to mirror tumor burden or prognosis in patients with NEN of the colon and rectum.

[Advances of circulating biomarkers in gastroenteropancreatic neuroendocrine neoplasms].

Gastroenteropancreatic neuroendocrine neoplam (GEP-NEN) is a rare group of tumors with its incidence rising significantly in recent decades. Because of the late presentation of the disease and limitations in conventional biomarkers, about 50% of GEP-NEN patients manifests advanced disease when diagnosed. Therefore, it is vital to identify circulating biomarkers which can not only be used for early diagnosis but also accurately evaluating the biological behavior of GEP-NEN. This review summarizes the advances of circulating biomarkers in diagnosing and evaluating efficacy of treatment in GEP-NEN. Well-known circulating biomarkers include chromogranin A (CgA), pancreastatin (PST), chromogranin B (CgB), neuron-specific enolase (NSE) and pancreatic peptide(PP). Novel biomarkers including circulating tumor cell(CTC), microRNA and NETest are promising biomarkers with potential clinical benefit, but further researches are needed before their clinical applications.

Utility of chromogranin B compared with chromogranin A as a biomarker in Japanese patients with pancreatic neuroendocrine tumors.

OBJECTIVE: Currently, serum chromogranin A is a well-established biomarker for pancreatic neuroendocrine tumors; however, other pancreatic diseases, oral use of a proton pump inhibitor and renal impairment can affect chromogranin A. Meanwhile, chromogranin B, belonging to the same granin family as chromogranin A, is not fully examined in these conditions. The present study aimed to evaluate the utility of chromogranin B as a pancreatic neuroendocrine tumor biomarker. METHODS: Serum chromogranin B levels were determined by radioimmunoassay and serum chromogranin A levels by enzyme-linked immunosorbent assay in pancreatic neuroendocrine tumor (n = 91) and other pancreatic conditions, and in healthy people (n = 104), to assess the relationships with clinical features. RESULTS: The diagnostic ability of chromogranin B was as good as chromogranin A. The area under the curve was 0.79 for chromogranin B (sensitivity/specificity: 72%/77%), and 0.78 for chromogranin A (sensitivity/specificity: 79%/64%). Chromogranin B was not affected by proton pump inhibitor use and age, which affected chromogranin A. The number of cases without liver metastases was larger in pancreatic neuroendocrine tumor patients with positive chromogranin B and negative chromogranin A. Though chromogranin A significantly elevated cases with proton pump inhibitor treatment and had positive correlation with age, chromogranin B did not have the tendencies. However, both chromogranin B and chromogranin A elevated in the case with renal impairment. In addition, the logistic regression analysis showed that chromogranin B was superior to chromogranin A in differentiation of pancreatic neuroendocrine tumor from other pancreatic diseases. CONCLUSIONS: Compared with chromogranin A, chromogranin B may be more useful during proton pump inhibitor treatment and can detect tumors without liver metastases. In addition, chromogranin B may be an excellent biomarker when differentiation of pancreatic neuroendocrine tumor from other pancreatic diseases is required.

Circulating chromogranin B levels in patients with acute respiratory failure: data from the FINNALI Study.

PURPOSE: Circulating chromogranin B (CgB) levels are increased in situations characterized by systemic and myocardial stress, but whether CgB provides prognostic information in patients with acute respiratory failure (ARF) is unknown. METHODS: We included 584 patients with ARF, defined as ventilatory support >6 h, and with blood samples available on Intensive Care Unit (ICU) admission and day 3 (n = 479). CgB levels were measured by radioimmunoassay and follow-up was 90 days. RESULTS: One-hundred-sixty-nine patients (29%) died during follow-up. Admission CgB levels separated non-survivors from survivors: median 1234 (Q1-3 989-1742) vs. 917 (753-1224) pmol/L, respectively, p < 0.001. CgB levels on ICU admission (logarithmically transformed) were associated with time to death after adjustment for established risk indices available on ICU admission, including N-terminal pro-B-type natriuretic levels: HR 2.62 (95%C.I. 1.82-3.77), p < 0.001. Admission CgB levels also improved prognostication on top of SOFA and SAPS II scores as assessed by Cox regression analyses and the category-free net reclassification index. The area under the curve (AUC) for admission CgB levels to separate survivors and non-survivors was 0.72 (95%CI 0.67-0.76), while the AUC on day 3 was 0.60 (0.54-0.66). CONCLUSIONS: CgB levels measured on ICU admission provided additional prognostic information to established risk indices in ARF patients.

Routine measurement of plasma chromogranin B has limited clinical utility in the management of patients with neuroendocrine tumours.

OBJECTIVE: Chromogranin A (CgA) and B (CgB) are markers for monitoring disease status in patients with gastroenteropancreatic neuroendocrine tumours (NETs). These are specialized diagnostic tests often necessitating referral of specimens to a supraregional assay service (SAS) laboratory for analysis. The aim of this audit was to assess whether measurement of either plasma CgA or CgB alone provides sufficient clinical information in comparison with the current practice of measuring both markers together. DESIGN: A retrospective analysis was undertaken for all chromogranin tests requested for patients with a known NET diagnosis. Results were categorized based on whether plasma concentrations were elevated for one or both CgA and CgB. RESULTS: A total of 325 sequential patients with a NET diagnosis had plasma chromogranin levels measured during the period of review. Baseline CgA was elevated in 60·9% of patients. Isolated elevations in CgA (with normal CgB) were found in 44·9% of patients, whilst combined elevations in both CgA and CgB were found in 16% of patients. Combined CgA and CgB concentrations within the normal range were observed for 38·5% of patients. Only two patients (0·6%) had an isolated elevation in CgB at baseline. Both patients had a diagnosis of pancreatic NET and were radiologically stable. Plasma CgA and CgB corresponded with disease stage (localized vs metastatic). CgB in addition to CgA did not provide any significant improvement in diagnostic performance for identification of metastatic disease compared to CgA alone. CONCLUSIONS: Based on this NET population and specific assay performance characteristics, CgA alone provides sufficient information for the management of NET patients; the routine estimation of CgB in all patients is not informative in clinical practice.

Comparison of the utility of Cocaine- and Amphetamine-Regulated Transcript (CART), chromogranin A, and chromogranin B in neuroendocrine tumor diagnosis and assessment of disease progression.

CONTEXT: Prognosis in patients with neuroendocrine tumors (NETs) is often poor, frequently reflecting delayed diagnosis. Hence, accurate and practical NET markers are needed. Cocaine- and amphetamine-regulated transcript (CART) peptide is a potential novel NET marker. DESIGN AND PARTICIPANTS: Circulating levels of CART peptide and the established NET markers chromogranin A (CgA) and chromogranin B (CgB) were measured using RIA in 353 patients with NET (normal renal function) and in controls. Clinical data were collected retrospectively. MAIN OUTCOME MEASURE(S): The comparative and combined utility of CART, CgA, and CgB for diagnosis and assessment of disease progression was measured in different NET subtypes. RESULTS: CgA and CgB in combination improved diagnostic accuracy in patients with gut NETs, nongastroenteropancreatic NETs, and NETs with an unknown primary origin compared with each biomarker alone. Measuring CART did not further improve diagnosis in these NET subtypes. For pancreatic NETs, CgB was superior to CgA and CART in detecting stable disease (P < .007), whereas CgA and CART in combination were most effective in identifying progressive disease. In phaeochromocytomas/paragangliomas (PCC/PGL), CART was the most useful biomarker for identifying stable (P < .001) and progressive (P = .001) disease. Consistent with this, plasma CART decreased following PCC/PGL tumor resection, remaining low in all patients in remission, but increasing in those with progressive disease. CONCLUSIONS: CART is a useful marker for identifying progressive pancreatic NETs. CART is superior to CgA and CgB in detecting stable and progressive PCC/PGLs, and may have a role as a surveillance marker for PCC/PGL patients.

Effect of short- and long-term physical activities on circulating granin protein levels.

BACKGROUND: The classic chromogranin-secretogranin (granin) proteins are produced in the myocardium and throughout the neuroendocrine system, but while chromogranin (Cg) A and B levels are high in the adrenal medulla, secretogranin (Sg) II production is higher in the pituitary gland. Whether these differences may influence the response to physical activity is not known. METHODS: We measured circulating granin proteins during (1) a short-term maximal bicycle exercise stress test and (2) a 7 day military ranger course of continuous physical activity and sleep and energy deprivation. RESULTS: In 9 healthy subjects performing the exercise stress test (7 male, age 45±5 y [mean±SEM], duration 10.13±1.14 min), CgB levels increased from before to immediately after the test: 1.20±0.12 vs. 1.45±0.09 nmol/L, p=0.013. Metabolic equivalents, representing an index of performed work, were closely associated with the change (∆) in CgB levels during stress testing and explained 74% of the variability in ∆CgB levels (p=0.004). CgA and SgII levels were not increased after exercise stress testing. In the second cohort of 8 male subjects (age 25±1 y) participating in the ranger course, CgB levels increased from day 1 and were significantly elevated on days 5 and 7. CgA also increased gradually with levels significantly elevated on day 7, while SgII was markedly increased on day 5 whereas levels on days 3 and 7 were unchanged compared to baseline levels. CONCLUSION: We demonstrate a heterogeneous response to short- and long-term physical activities among circulating granin proteins with the most potent effect on CgB levels.

Management of pancreatic neuroendocrine tumors.

Neuroendocrine tumors are a heterogeneous group of rare tumors originating from neuroendocrine cells with secretory characteristics, and are primarily located in gastric, duodenal, pancreatic, and small and large bowel mucosa. Due to their extremely variable biologic and clinical behaviour, diagnosis is often delayed after a prolonged workup. Many advances have been made in recent years in the diagnosis, characterization, and treatment of neuroendocrine tumors. This review focuses on pancreatic neuroendocrine tumors, discussing the relatively new, multidisciplinary approach to their management. A Pubmed search was performed, limited to papers published within the last five years, using the key words NETs, pancreatic NETs, pancreatic tumors, diagnosis, imaging, nuclear imaging, endoscopy, endoscopic ultrasound, and biochemical markers.

Chromogranin/secretogranin proteins in murine heart: myocardial production of chromogranin A fragment catestatin (Chga(364-384)).

In the heart, the secretory granules containing the atrial natriuretic peptides (ANP) and B-type myocardial natriuretic peptide (BNP) provide the basis for the endocrine function of this organ. We sought to determine whether atrial and myocardial secretory granules contain chromogranin/secretogranin proteins including chromogranin A (CHGA/Chga), chromogranin B (CHGB/Chgb) and secretogranin II (SCG2/Scg2). Deconvolution microscopy on immunolabeled proteins revealed the presence of Chga, Chgb, and Scg2 in murine cardiac secretory granules. The presence of low plasma catestatin (CST: mChga(364-384)) in older mice indicates diminished processing of Chga to CST with advancement of age, which is comparable to that found in humans. We have previously shown that CST (hCHGA(352-372)) exerts potent cardio-suppressive effects on frog and rat heart, but the source of CST for such action has remained elusive. In the present study, we found CST-related peptides in cardiomyocytes and in heart, which establishes an autocrine/paracrine function of CST in cardiac tissue. We conclude that cardiac secretory granules contain Chga, Chgb and Scg2 and that Chga is processed to CST in murine heart.

Chromogranin B in heart failure: a putative cardiac biomarker expressed in the failing myocardium.

BACKGROUND: Chromogranin B (CgB) is a member of the granin protein family. Because CgB is often colocalized with chromogranin A (CgA), a recently discovered cardiac biomarker, we hypothesized that CgB is regulated during heart failure (HF) development. METHODS AND RESULTS: CgB regulation was investigated in patients with chronic HF and in a post-myocardial infarction HF mouse model. Animals were phenotypically characterized by echocardiography and euthanized 1 week after myocardial infarction. CgB mRNA levels were 5.2-fold increased in the noninfarcted part of the left ventricle of HF animals compared with sham-operated animals (P<0.001). CgB mRNA level in HF animals correlated closely with animal lung weight (r=0.74, P=0.04) but not with CgA mRNA levels (r=0.20, P=0.61). CgB protein levels were markedly increased in both the noninfarcted (110%) and the infarcted part of the left ventricle (70%) but unaltered in other tissues investigated. Myocardial CgB immunoreactivity was confined to cardiomyocytes. Norepinephrine, angiotensin II, and transforming growth factor-beta increased CgB gene expression in cardiomyocytes. Circulating CgB levels were increased in HF animals (median levels in HF animals versus sham, 1.23 [interquartile range, 1.03 to 1.93] versus 0.98 [0.90 to 1.04] nmol/L; P=0.003) and in HF patients (HF patients versus control, 1.66 [1.48 to 1.85] versus 1.47 [1.39 to 1.58] nmol/L; P=0.007), with levels increasing in proportion to New York Heart Association functional class (P=0.03 for trend). Circulating CgB levels were only modestly correlated with CgA (r=0.31, P=0.009) and B-type natriuretic peptide levels (r=0.27, P=0.014). CONCLUSIONS: CgB production is increased and regulated in proportion to disease severity in the left ventricle and circulation during HF development.

Neuroendocrine inhibition of glucose production and resistance to cancer in dwarf mice.

Pit1 null (Snell dwarf) and Proph1 null (Ames dwarf) mutant mice lack GH, PRL and TSH. Snell and Ames dwarf mice also exhibit reduced IGF-I, resistance to cancer and a longer lifespan than control mice. Endogenous glucose production during fasting is reduced in Snell dwarf mice compared to fasting control mice. In view of cancer cell dependence on glucose for energy, low endogenous glucose production may provide Snell dwarf mice with resistance to cancer. We investigated whether endogenous glucose production is lower in Snell dwarf mice during feeding. Inhibition of endogenous glucose production by glucose injection was enhanced in 12 to 14 month-old female Snell dwarf mice. Thus, we hypothesize that lower endogenous glucose production during feeding and fasting reduces cancer cell glucose utilization providing Snell dwarf mice with resistance to cancer. The elevation of circulating adiponectin, a hormone produced by adipose tissue, may contribute to the suppression of endogenous glucose production in 12 to 14 month-old Snell dwarf mice. We compared the incidence of cancer at time of death between old Snell dwarf and control mice. Only 18% of old Snell dwarf mice had malignant lesions at the time of death compared to 82% of control mice. The median ages at death for old Snell dwarf and control mice were 33 and 26 months, respectively. By contrast, previous studies showed a high incidence of cancer in old Ames dwarf mice at the time of death. Hence, resistance to cancer in old Snell dwarf mice may be mediated by neuroendocrine factors that reduce glucose utilization besides elevated adiponectin, reduced IGF-I and a lack of GH, PRL and TSH, seen in both Snell and Ames dwarf mice. Proteomics analysis of pituitary secretions from Snell dwarf mice confirmed the absence of GH and PRL, the secretion of ACTH and elevated secretion of Chromogranin B and Secretogranin II. Radioimmune assays confirmed that circulating Chromogranin B and Secretogranin II were elevated in 12 to 14 month-old Snell dwarf mice. In summary, our results in Snell dwarf mice suggest that the pituitary gland and adipose tissue are part of a neuroendocrine loop that lowers the risk of cancer during aging by reducing the availability of glucose.

Measurements of secretogranins II, III, V and proconvertases 1/3 and 2 in plasma from patients with neuroendocrine tumours.

INTRODUCTION: Chromogranin (Cg) and secretogranin (Sg) are members of the granin family of proteins, which are expressed in neuroendocrine and nervous tissue. In recent publications we have presented generation of region-specific antibodies against CgA and CgB and also development of several region-specific radioimmunoassays for measurements of specific parts of the Cgs. In this study we describe generation of antibodies against SgII, SgIII, SgV and the proconvertases PC1/3 and PC2 and development of radioimmunoassays for measurements of these proteins. MATERIALS AND METHODS: Peptides homologous to defined parts of the secretogranin and proconvertase molecules were selected and synthesised. Antibodies were raised, radioimmunoassays were developed and circulating levels of the proteins in plasma samples from 22 patients with neuroendocrine tumours were measured in the assays. RESULTS: Increased plasma concentrations were recorded in 11, 4 and 3 of the patients with the SgII 154-165 (N-terminal secretoneurin), the SgII 172-186 (C-terminal Secretoneurin) and the SgII 225-242 assays respectively. The SgIII, SgV, PC1/3 and PC2 assays failed to detect increased concentrations in any of the patients. CONCLUSION: Increased concentrations of SgII, especially the N-terminal part of secretoneurin could be measured in plasma from patients with endocrine pancreatic tumours and in this case this assay was quite comparable to measurements of CgA and CgB. Even though secretoneurin was not as frequently increased as CgA and CgB in patients with carcinoid tumours or pheochromocytoma it may be a useful marker for endocrine pancreatic tumours.

Elevated cocaine- and amphetamine-regulated transcript immunoreactivity in the circulation of patients with neuroendocrine malignancy.

CONTEXT: Cocaine- and amphetamine-regulated transcript (CART) codes for a peptide widely distributed in nervous and endocrine tissues. CART immunoreactivity (CART-LI) has been detected in human insulinomas. OBJECTIVE: The objective of the study was to investigate the measurement of plasma CART-LI as a tumor marker of neuroendocrine malignancy. DESIGN AND SUBJECTS: Plasma CART-LI levels were measured in 401 patients with a range of diagnoses: neuroendocrine malignancy (n = 131), after removal of neuroendocrine malignancy (n = 27), without any form of tumor or renal impairment (n = 192), with renal impairment (n = 17) and with nonneuroendocrine tumors (n = 34). Chromatography methods were used to investigate CART-LI circulating in human plasma. RESULTS: The upper limit of normal calculated for CART-LI was 150 pmol/liter. Mean circulating plasma CART-LI among neuroendocrine tumor patients was 440 pmol/liter, 56% of subjects having levels greater than 150 pmol/liter. Measuring CART-LI in addition to chromogranin (Cg)-A improved the sensitivity for neuroendocrine malignancy from 85 to 91%, whereas combined use of CgA and CgB had a joint sensitivity of 89%. Of 38 patients with pancreatic neuroendocrine tumors, 71% had plasma CART-LI levels greater than 150 pmol/liter, increasing to 95% in those classified with progressive disease (n = 20, mean CART-LI 625 pmol/liter), compared with 80% for CgA. Chromatographic analysis suggests that circulating CART-LI is present as one major form, which may correspond to CART (62-102) or another unknown form. CONCLUSIONS: We demonstrate CART-LI as a specific tumor marker in patients with a range of neuroendocrine tumors. Used in combination with CgA, CART-LI measurement has the potential to improve sensitivity in diagnosis and follow-up of neuroendocrine tumors, in particular progressive pancreatic neuroendocrine tumors.

Measurements of chromogranin B can serve as a complement to chromogranin A.

OBJECTIVE: CgA has been shown to be an excellent marker for neuroendocrine tumours. However, there are two major drawbacks with CgA measurements; elevated levels are common in patients with decreased renal function and in patients on treatment with proton pump inhibitors. These problems are not seen with CgB measurements. We have recently presented the development of 13 region-specific radioimmunoassays for measurements of CgB. A region-specific assay was identified, which measured higher concentrations of CgB than the other assays and seemed to be very useful as a marker for neuroendocrine tumours. The aim of the present study was therefore to further explore the diagnostic potential of this assay in the clinical management of patients with neuroendocrine tumours. METHODS: Measurements of CgB with two methods were compared with CgA in plasma samples from patients investigated for neuroendocrine tumours (N=86), patients with decreased renal function (N=35) and patients on treatment with proton pump inhibitors (N=29). RESULTS: The diagnostic sensitivity for the new CgB assay was almost as good as that for CgA. Furthermore, with CgB measurements we could avoid the falsely elevated levels of CgA found in patients with decreased renal function and treatment with proton pump inhibitors. CONCLUSIONS: We conclude that the new CgB assay can serve as a complement to CgA measurements as an important tumour marker for neuroendocrine tumours.