adrenomedullin and Pancreatic-Neoplasms

Adrenomedullin (ADM) is a 52-amino acid peptide with structural homology to calcitonin gene-related peptide (CGRP) initially isolated from human pheochromocytoma. ADM is synthesized and is secreted from many mammalian tissues, including the adrenal medulla, endothelial and vascular smooth muscle cells, as well as the myocardium and central nervous system. ADM has been implicated as a mediator of several diseases such as cardiovascular and renal disorders, sepsis, inflammation, diabetes and cancer. ADM is also expressed in a variety of tumors, including breast, endometrial and prostate cancer. ADM has been shown to be a mitogenic factor capable of stimulating growth of several cancer cell types. In addition, ADM is a survival factor for certain cancer cells and an indirect suppressor of the immune response. ADM plays an important role in environments subjected to low oxygen tension, which is a typical feature of solid tumors. Under these conditions, ADM is up regulated and acts as a potent angiogenic factor promoting neovascularization. The major focus of this review will be on the role of ADM in cancer, with emphasis on its utility in diagnostic and prognostic terms, along with its relevance as a therapeutic target.

Topics: Adrenomedullin; Animals; Disease Progression; Endometrial Neoplasms; Female; Humans; Male; Neoplasms; Neovascularization, Physiologic; Ovarian Neoplasms; Pancreatic Neoplasms; Prognosis; Prostatic Neoplasms; Protein Biosynthesis; Receptors, Adrenomedullin; Receptors, Peptide; Signal Transduction

Pancreatic cancer is a leading cause of cancer-related death. Its diagnosis is often delayed and patients are frequently found to have unresectable disease. Patients diagnosed with new-onset diabetes have an 8-fold risk of harboring pancreatic cancer. Adrenomedullin has been claimed to mediate diabetes in pancreatic cancer. New screening tools are needed to develop an early diagnosis protocol.. Patients aged 45-75 years within 2 years of first fulfilling the ADA criteria for diabetes will be prospectively enrolled in this study. Sepsis, renal failure, microangiopathy, pregnancy, acute heart failure and previous malignancies will be considered as exclusion criteria.. 440 patients diagnosed with new-onset diabetes will be enrolled and divided into 2 groups: one with high adrenomedullin levels and one with low adrenomedullin levels. Patients will undergo 3 years' follow-up to detect pancreatic cancer development.. Identifying a marker for pancreatic cancer among high-risk patients such as new-onset diabetics might lead to the identification of a subpopulation needing to be screened in order to enable early diagnosis and treatment of a highly lethal tumor.. This trial was registered at ClinicalTrials.gov on May 25, 2015 under registration number NCT02456051.

Topics: Adrenomedullin; Age of Onset; Aged; Diabetes Mellitus, Type 2; Early Diagnosis; Female; Humans; Male; Middle Aged; Pancreatic Neoplasms

It has been demonstrated that adrenomedullin, a newly discovered peptide, affects the release of insulin from pancreatic islets cells, suggesting a role in the insulin-regulating system.. To investigate whether adrenomedullin secretion is modified in patients with insulin-secreting islet cell tumours.. The study was performed in nine patients with surgically treated insulinoma. Circulating adrenomedullin was assayed using a specific radioimmunoassay and its localization and distribution in the tumour were determined by means of immunohistochemistry.. Adrenomedullin concentrations were significantly greater in patients with insulinoma (6.6 +/- 3.2 fmol/ml) than in controls (2.1 +/- 1.1 fmol/ml). In six patients monitored before and after surgery, plasma adrenomedullin decreased from 6.3 +/- 2.9 fmol/ml to 3.0 +/- 1.6 fmol/ml. Immunoreactive adrenomedullin was localized exclusively in the tumours cells, whereas stroma, surrounding pancreas parenchyma and major ducts were negative for the peptide.. Our findings indicate that circulating adrenomedullin is increased in insulinoma and that this increase is related to the neoplastic phenotype.

Topics: Adenoma, Islet Cell; Adrenomedullin; Adult; Blood Glucose; Female; Humans; Immunohistochemistry; Insulin; Insulinoma; Male; Middle Aged; Pancreatic Neoplasms; Peptides

Tumor metastasis is a primary source of morbidity and mortality in cancer. Adrenomedullin (AM) is a multifunctional peptide regulated by receptor activity-modifying proteins (RAMPs). We previously reported that the AM-RAMP2 system is involved in tumor angiogenesis, but the function of the AM-RAMP3 system remains largely unknown. Here, we investigated the actions of the AM-RAMP2 and 3 systems in the tumor microenvironment and their impact on metastasis. PAN02 pancreatic cancer cells were injected into the spleens of mice, leading to spontaneous liver metastasis. Tumor metastasis was enhanced in vascular endothelial cell-specific RAMP2 knockout mice (DI-E-RAMP2-/-). By contrast, metastasis was suppressed in RAMP3-/- mice, where the number of podoplanin (PDPN)-positive cancer-associated fibroblasts (CAFs) was reduced in the periphery of tumors at metastatic sites. Because PDPN-positive CAFs are a hallmark of tumor malignancy, we assessed the regulation of PDPN and found that Src/Cas/PDPN signaling is mediated by RAMP3. In fact, RAMP3 deficiency CAFs suppressed migration, proliferation, and metastasis in co-cultures with tumor cells in vitro and in vivo. Moreover, the activation of RAMP2 in RAMP3-/- mice suppressed both tumor growth and metastasis. Based on these results, we suggest that the upregulation of PDPN in DI-E-RAMP2-/- mice increases malignancy, while the downregulation of PDPN in RAMP3-/- mice reduces it. Selective activation of RAMP2 and inhibition of RAMP3 would therefore be expected to suppress tumor metastasis. This study provides the first evidence that understanding and targeting to AM-RAMP systems could contribute to the development of novel therapeutics against metastasis.

Topics: Adrenomedullin; Animals; Cancer-Associated Fibroblasts; Cells, Cultured; Liver Neoplasms, Experimental; Male; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Neoplasm Metastasis; Pancreatic Neoplasms; Receptor Activity-Modifying Protein 3

New-onset diabetes and concomitant weight loss occurring several months before the clinical presentation of pancreatic cancer (PC) appear to be paraneoplastic phenomena caused by tumour-secreted products. Our recent findings have shown exosomal adrenomedullin (AM) is important in development of diabetes in PC. Adipose tissue lipolysis might explain early onset weight loss in PC. We hypothesise that lipolysis-inducing cargo is carried in exosomes shed by PC and is responsible for the paraneoplastic effects. Therefore, in this study we investigate if exosomes secreted by PC induce lipolysis in adipocytes and explore the role of AM in PC-exosomes as the mediator of this lipolysis.. Exosomes from patient-derived cell lines and from plasma of patients with PC and non-PC controls were isolated and characterised. Differentiated murine (3T3-L1) and human adipocytes were exposed to these exosomes to study lipolysis. Glycerol assay and western blotting were used to study lipolysis. Duolink Assay was used to study AM and adrenomedullin receptor (ADMR) interaction in adipocytes treated with exosomes.. In murine and human adipocytes, we found that both AM and PC-exosomes promoted lipolysis, which was abrogated by ADMR blockade. AM interacted with its receptor on the adipocytes, activated p38 and extracellular signal-regulated (ERK1/2) mitogen-activated protein kinases and promoted lipolysis by phosphorylating hormone-sensitive lipase. PKH67-labelled PC-exosomes were readily internalised into adipocytes and involved both caveolin and macropinocytosis as possible mechanisms for endocytosis.. PC-secreted exosomes induce lipolysis in subcutaneous adipose tissue; exosomal AM is a candidate mediator of this effect.

Topics: Adipocytes; Adrenomedullin; Animals; Cell Line, Tumor; Cells, Cultured; Endocytosis; Exosomes; Glycerol; Humans; Lipolysis; MAP Kinase Signaling System; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; p38 Mitogen-Activated Protein Kinases; Pancreatic Neoplasms; Receptors, Adrenomedullin; Subcutaneous Fat

Topics: Adrenomedullin; Diabetes Mellitus; Exosomes; Humans; Pancreatic Neoplasms

Extensive desmoplasia is a prominent pathological characteristic of pancreatic cancer (PC) that not only impacts tumor development, but therapeutic outcome as well. Recently, we demonstrated a novel role of MYB, an oncogenic transcription factor, in PC growth and metastasis. Here we studied its effect on pancreatic tumor histopathology and associated molecular and biological mechanisms. Tumor-xenografts derived from orthotopic-inoculation of MYB-overexpressing PC cells exhibited far-greater desmoplasia in histological analyses compared with those derived from MYB-silenced PC cells. These findings were further confirmed by immunostaining of tumor-xenograft sections with collagen-I, fibronectin (major extracellular-matrix proteins), and α-SMA (well-characterized marker of myofibroblasts or activated pancreatic stellate cells (PSCs)). Likewise, MYB-overexpressing PC cells provided significantly greater growth benefit to PSCs in a co-culture system as compared with the MYB-silenced cells. Interrogation of deep-sequencing data from MYB-overexpressing versus -silenced PC cells identified Sonic-hedgehog (SHH) and Adrenomedullin (ADM) as two differentially-expressed genes among others, which encode for secretory ligands involved in tumor-stromal cross-talk. In-silico analyses predicted putative MYB-binding sites in SHH and ADM promoters, which was later confirmed by chromatin-immunoprecipitation. A cooperative role of SHH and ADM in growth promotion of PSCs was confirmed in co-culture by using their specific-inhibitors and exogenous recombinant-proteins. Importantly, while SHH acted exclusively in a paracrine fashion on PSCs and influenced the growth of PC cells only indirectly, ADM could directly impact the growth of both PC cells and PSCs. In summary, we identified MYB as novel regulator of pancreatic tumor desmoplasia, which is suggestive of its diverse roles in PC pathobiology.

Topics: Adrenomedullin; Animals; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; Heterografts; Humans; Mice; Neoplasm Transplantation; Oncogene Proteins v-myb; Pancreatic Neoplasms; Pancreatic Stellate Cells; Paracrine Communication; Response Elements; Transcription, Genetic; Up-Regulation

Stromal infiltration of myelomonocytic cells is a hallmark of pancreatic ductal adenocarcinoma (PDAC) and is related to a poor prognosis. However, the detailed mechanism for the recruitment of myelomonocytic cells to pancreatic cancer tissue remains unclear. In the present study, pancreatic cancer cells secreted high levels of adrenomedullin (ADM), and CD11b+ myelomonocytic cells expressed all components of ADM receptors, including GPR182, CRLR, RAMP2 and RAMP3. ADM enhanced the migration and invasion of myelomonocytic cells through activation of the MAPK, PI3K/Akt and eNOS signaling pathways, as well as the expression and activity of MMP-2. ADM also promoted the adhesion and trans-endothelial migration of myelomonocytic cells by increasing expression of VCAM-1 and ICAM-1 in endothelial cells. In addition, ADM induced macrophages and myeloid-derived suppressor cells (MDSCs) to express pro-tumor phenotypes. ADM knockdown in tumor-bearing mice or administration of AMA, an ADM antagonist, significantly inhibited the recruitment of myelomonocytic cells and tumor angiogenesis. Moreover, in vivo depletion of myelomonocytic cells using clodronate liposomes suppressed the progression of PDAC. These results reveal a novel function of ADM in PDAC, and suggest ADM is a promising target in the treatment of PDAC.

Topics: Adrenomedullin; Adult; Aged; Aged, 80 and over; Animals; Carcinoma, Pancreatic Ductal; Cell Line; Cell Line, Tumor; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Nude; Middle Aged; Monocytes; Myeloid-Derived Suppressor Cells; Pancreatic Neoplasms; RNA Interference; Transplantation, Heterologous

Pancreatic cancer frequently causes diabetes. We recently proposed adrenomedullin as a candidate mediator of pancreatic β-cell dysfunction in pancreatic cancer. How pancreatic cancer-derived adrenomedullin reaches β cells remote from the cancer to induce β-cell dysfunction is unknown. We tested a novel hypothesis that pancreatic cancer sheds adrenomedullin-containing exosomes into circulation, which are transported to β cells and impair insulin secretion.. We characterized exosomes from conditioned media of pancreatic cancer cell lines (n = 5) and portal/peripheral venous blood of patients with pancreatic cancer (n = 20). Western blot analysis showed the presence of adrenomedullin in pancreatic cancer-exosomes. We determined the effect of adrenomedullin-containing pancreatic cancer exosomes on insulin secretion from INS-1 β cells and human islets, and demonstrated the mechanism of exosome internalization into β cells. We studied the interaction between β-cell adrenomedullin receptors and adrenomedullin present in pancreatic cancer-exosomes. In addition, the effect of adrenomedullin on endoplasmic reticulum (ER) stress response genes and reactive oxygen/nitrogen species generation in β cells was shown.. Exosomes were found to be the predominant extracellular vesicles secreted by pancreatic cancer into culture media and patient plasma. Pancreatic cancer-exosomes contained adrenomedullin and CA19-9, readily entered β cells through caveolin-mediated endocytosis or macropinocytosis, and inhibited insulin secretion. Adrenomedullin in pancreatic cancer exosomes interacted with its receptor on β cells. Adrenomedullin receptor blockade abrogated the inhibitory effect of exosomes on insulin secretion. β cells exposed to adrenomedullin or pancreatic cancer exosomes showed upregulation of ER stress genes and increased reactive oxygen/nitrogen species.. Pancreatic cancer causes paraneoplastic β-cell dysfunction by shedding adrenomedullin(+)/CA19-9(+) exosomes into circulation that inhibit insulin secretion, likely through adrenomedullin-induced ER stress and failure of the unfolded protein response.

Topics: Adrenomedullin; Blotting, Western; CA-19-9 Antigen; Diabetes Mellitus; Exosomes; Humans; Insulin-Secreting Cells; Microscopy, Confocal; Pancreatic Neoplasms; Paraneoplastic Syndromes; Real-Time Polymerase Chain Reaction

Diabetes may be a consequence of pancreatic cancer, preceding cancer diagnosis. The underlying mechanism is the release of exosomes delivering adrenomedullin to β cells, inducing endoplasmic reticulum stress and perturbations in the unfolded protein response, leading to β-cell dysfunction and death. This knowledge could lead to improved diagnostic strategies for pancreatic cancer.

Topics: Adrenomedullin; Diabetes Mellitus; Exosomes; Humans; Insulin-Secreting Cells; Pancreatic Neoplasms

New-onset diabetes in patients with pancreatic cancer is likely to be a paraneoplastic phenomenon caused by tumor-secreted products. We aimed to identify the diabetogenic secretory product(s) of pancreatic cancer.. Using microarray analysis, we identified adrenomedullin as a potential mediator of diabetes in patients with pancreatic cancer. Adrenomedullin was up-regulated in pancreatic cancer cell lines, in which supernatants reduced insulin signaling in beta cell lines. We performed quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry on human pancreatic cancer and healthy pancreatic tissues (controls) to determine expression of adrenomedullin messenger RNA and protein, respectively. We studied the effects of adrenomedullin on insulin secretion by beta cell lines and whole islets from mice and on glucose tolerance in pancreatic xenografts in mice. We measured plasma levels of adrenomedullin in patients with pancreatic cancer, patients with type 2 diabetes mellitus, and individuals with normal fasting glucose levels (controls).. Levels of adrenomedullin messenger RNA and protein were increased in human pancreatic cancer samples compared with controls. Adrenomedullin and conditioned media from pancreatic cell lines inhibited glucose-stimulated insulin secretion from beta cell lines and islets isolated from mice; the effects of conditioned media from pancreatic cancer cells were reduced by small hairpin RNA-mediated knockdown of adrenomedullin. Conversely, overexpression of adrenomedullin in mice with pancreatic cancer led to glucose intolerance. Mean plasma levels of adrenomedullin (femtomoles per liter) were higher in patients with pancreatic cancer compared with patients with diabetes or controls. Levels of adrenomedullin were higher in patients with pancreatic cancer who developed diabetes compared those who did not.. Adrenomedullin is up-regulated in patients with pancreatic cancer and causes insulin resistance in β cells and mice.

Topics: Adenocarcinoma; Adrenomedullin; Aged; Animals; Cell Line, Tumor; Cells, Cultured; Diabetes Mellitus, Type 2; Female; Glucose; Humans; In Vitro Techniques; Insulin; Insulin Resistance; Insulin-Secreting Cells; Male; Mice; Mice, Nude; Middle Aged; Models, Animal; Pancreas; Pancreatic Neoplasms; Rats; RNA, Small Interfering; Transplantation, Heterologous; Up-Regulation

Adrenomedullin (AM) is highly expressed in pancreatic cancer and stimulates pancreatic cancer cells leading to increased tumor growth and metastasis. The current study examines the role of specific AM receptors on tumor and cells resembling the tumor microenvironment (human pancreatic stellate--HPSC, human umbilical vein-- HUVEC and mouse lung endothelial cells--MLEC).. AM receptors ADMR and CRLR were present in HPSC, HUVEC and MLECs while PDAC cells possessed only ADMR receptors as assessed by RT-PCR and western blotting. All cell lines expressed and secreted AM as indicated by ELISA. The growth of each of the cell lines was stimulated by exogenous AM and inhibited by the antagonist AMA. AM also stimulated in vitro angiogenesis assessed by polygon formation of endothelial cell lines. SiRNA-mediated silencing of ADMR, but not CRLR, reduced basal growth of all cells examined and reduced polygon formation of endothelial cells in vitro. Orthotopic tumors developed with shADMR bearing cancer cells had dramatically reduced primary tumor volume (>90%) and lung and liver metastasis compared to shControl bearing cells. To validate ADMR as a potential therapeutic target, in vivo studies were conducted using neutral nanoliposomes to systemically deliver human siRNA to ADMR to silence human cancer cells and mouse siRNA to ADMR to silence mouse tumor stromal cells. Systemic silencing of both human and mouse ADMR had no obvious adverse effects but strongly reduced tumor development.. ADMR mediates the stimulatory effects of AM on cancer cells and on endothelial and stellate cells within the tumor microenvironment. These data support the further development of ADMR as a useful target treatment of pancreatic cancer.

Topics: Adrenomedullin; Animals; Cell Line, Tumor; Endothelial Cells; Endothelium, Vascular; Gene Expression Regulation, Neoplastic; Humans; Ligands; Lung; Mice; Neoplasm Metastasis; Neovascularization, Pathologic; Pancreatic Neoplasms; Receptors, Adrenomedullin; Receptors, Peptide; Stromal Cells

Adrenomedullin (ADM) is synthesized by different types of cells and acts by binding calcitonin receptor-like receptor (CRLR) and members of the receptor activity-modifying protein (RAMP) family. In this study, the expression and functional role of ADM and its signaling components were investigated in pancreatic adenocarcinoma (PDAC). By QRT-PCR, median mRNA levels of ADM and CRLR were 1.5- and 2.4-fold higher, respectively, in PDAC tissues compared to normal pancreatic tissues. By immunohistochemistry, ADM, CRLR, RAMP1 and RAMP2, but not RAMP3, were expressed in pancreatic cancer cells. ADM serum levels were significantly increased in PDAC patients compared to healthy controls and chronic pancreatitis (CP) patients, with an area under the ROC curve of 0.83 and 0.98, respectively. At a cut-off level of 30.6 ng/ml, the specificity of ADM to differentiate PDAC from controls and CP patients was 85.5 and 83.6%, with a sensitivity of 80 and 100%. All 5 evaluated pancreatic cancer cells lines expressed ADM, CRLR, RAMP1 and RAMP2, whereas RAMP3 was expressed in only 1/5 pancreatic cancer cell lines. ADM was strongly induced by hypoxia and significantly increased invasiveness in 3/5 human pancreatic cancer cells. Blocking of CRLR decreased invasiveness in 4/5 human pancreatic cancer cells. In addition, rADM slightly up-regulated vascular endothelial growth factor secretion in 3/5 cell lines. In conclusion, ADM is induced by hypoxia and over-expressed in PDAC and might therefore serve as a potential tumor marker. Furthermore, ADM increases invasiveness of some pancreatic cancer cells and might influence angiogenesis, suggesting that blocking this pathway might have a therapeutic potential.

Topics: Adolescent; Adrenomedullin; Adult; Aged; Aged, 80 and over; Calcitonin Receptor-Like Protein; Cell Hypoxia; Cell Line; Cell Movement; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Membrane Proteins; Middle Aged; Neoplasm Invasiveness; Pancreas; Pancreatic Neoplasms; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Receptor Activity-Modifying Proteins; Receptors, Calcitonin; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta1; Vascular Endothelial Growth Factor A

The current study investigated adrenomedullin as a potential autocrine regulator of pancreatic cancer cell function. Adrenomedullin was localized in the neoplastic epithelium of 90% (43 of 48) of human pancreatic adenocarcinomas analyzed by immunohistochemistry and was expressed by 100% (8 of 8) of pancreatic cancer cell lines analyzed by reverse transcription-PCR. Pancreatic cancer cell lines also secreted adrenomedullin into the culture medium as determined by ELISA (5 of 5). Exogenous adrenomedullin treatment of Panc-1, BxPC3, and MPanc96 cells in vitro stimulated cell proliferation, invasion, and nuclear factor kappaB activity, indicating the ability of the cells to respond to adrenomedullin. Treatment of the cell cultures with an adrenomedullin antagonist inhibited basal levels of proliferation and nuclear factor kappaB activity, supporting the autocrine function of this molecule. Furthermore, increasing adrenomedullin levels by gene transfer to Panc-1 cells increased, whereas adrenomedullin small hairpin RNA silencing in MPanc96 cells inhibited tumor growth and metastasis in vivo. Adrenomedullin is able to act through at least two different receptors, adrenomedullin receptor (ADMR) and calcitonin receptor-like receptor (CRLR). Reverse transcription-PCR and Western blotting indicated that pancreatic cancer cells expressed only ADMR but not CRLR. In contrast, cells found in the tumor microenvironment, primary human pancreatic stellate and endothelial (HUVEC) cells, expressed both ADMR and CRLR. Small hairpin RNA silencing of ADMR in pancreatic cancer cells blocked adrenomedullin-induced growth and invasion, indicating that this receptor is involved in the autocrine actions of adrenomedullin. These data indicate that adrenomedullin acting via ADMR increases the aggressiveness of pancreatic cancer cells and suggests that these molecules may be useful therapeutic targets.

Topics: Adenocarcinoma; Adrenomedullin; Animals; Cell Growth Processes; Cell Line, Tumor; Humans; Male; Mice; Mice, SCID; Neoplasm Invasiveness; NF-kappa B; Pancreatic Neoplasms; Receptors, Adrenomedullin; Receptors, Peptide; RNA, Small Interfering

Adrenomedullin is a multi-functional polypeptide hormone. Its involvement in angiogenesis and vasodilator action support the hypothesis that adrenomedullin may be a secretory product of neuroendocrine tumors and contribute to tumor progression. Plasma levels of adrenomedullin were measured by radioimmunoassay in 46 patients with neuroendocrine carcinomas of the gastroenteropancreatic and bronchial system. Tissue expression of adrenomedullin was studied using monoclonal antibodies on pretreated paraffin embedded tissues in a group of 31 patients. Adrenomedullin plasma levels were significantly elevated in patients compared to healthy age-matched controls (p < 0.001). The highest plasma levels were found in patients with neuroendocrine carcinomas of bronchial, midgut and unknown origin. Patients with progressive disease had higher plasma levels than patients with stable disease (p < 0.001). Of the examined tumor samples, 55 % showed cytoplasmic staining for adrenomedullin > 5 % of the total tumor area. Plasma levels and tissue expression of adrenomedullin did not correlate with functional activity of the tumors or presence of the carcinoid syndrome, but did with tumor progression (p < 0.001 and p < 0.014). In conclusion, plasma and tissue expression of the angiogenic peptide adrenomedullin are predictive of tumor progression in patients with neuroendocrine carcinomas. Adrenomedullin might represent a useful prognostic marker in patients with neuroendocrine carcinomas.

Topics: Adrenomedullin; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Bronchial Neoplasms; Carcinoma, Neuroendocrine; Disease Progression; Female; Gastrointestinal Neoplasms; Gene Expression Regulation, Neoplastic; Humans; Male; Middle Aged; Pancreatic Neoplasms; Peptides; Prognosis

Since it is reported that adrenomedullin (AM) upregulated by hypoxia inhibits hypoxic cell death, we examined the effects of AM antagonist (AM C-terminal fragment; AM(22-52)) on the growth of pancreatic cancer cells. We, for the first time, demonstrated that AM antagonist significantly reduced the in vivo growth of the pancreatic cancer cell line. Immunohistochemical analysis demonstrated that the mean diameter of blood vessels was significantly smaller in the tumor tissues treated with AM antagonist than in those treated with AM N-terminal fragment (AM(1-25)), and that the PCNA-labeling index was lower in the former than in the latter. Then we demonstrated that AM antagonist showed no effect on the in vitro growth of the pancreatic cancer cell line. These results showed that AM played an important role in the growth of pancreatic cancer cells in vivo, suggesting that AM antagonist might be a useful tool for treating pancreatic cancers.

Topics: Adrenomedullin; Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Cell Hypoxia; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Mice; Mice, SCID; Neoplasm Proteins; Neovascularization, Pathologic; Pancreatic Neoplasms; Peptide Fragments; Peptides; Transcription Factors; Tumor Cells, Cultured; Xenograft Model Antitumor Assays