1
|
Carter Y, Jaskula-Sztul R, Chen H, Mazeh H. Signaling pathways as specific pharmacologic targets for neuroendocrine tumor therapy: RET, PI3K, MEK, growth factors, and Notch. Neuroendocrinology 2013; 97:57-66. [PMID: 22343668 PMCID: PMC3360110 DOI: 10.1159/000335136] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Accepted: 11/11/2011] [Indexed: 12/21/2022]
Abstract
Neuroendocrine tumors are rare tumors with a common progenitor - the neural crest cell. Included in this category are pulmonary and gastrointestinal tract carcinoid tumors and medullary thyroid cancer. The majority of these tumors are sporadic in nature, however they can be hereditary. Medullary thyroid cancers can present sporadically, with other endocrine tumors, as in the complex of multiple endocrine neoplasias 1, 2A, or 2B, or as familial medullary thyroid cancer. These tumors can become evident at later stages, with metastases already present at the time of diagnosis. Despite the small size and rare incidence of gastrointestinal neuroendocrine (carcinoid) tumors, they can be debilitating when present. Their natural history presents as early lymph node and distant metastases, as well as symptoms of the carcinoid syndrome, which result from the overproduction and secretion of serotonin and somatostatin. As a consequence of their metastases, surgical resection is non-curative and hence there is a need for novel treatment strategies to address tumor burden and symptom control. There are multiple intracellular pathways which can be targeted, either individually or in combination, to address these tumors. Here, we review some of the intracellular pathways, and identify some specific targets, which are vital to the generation and propagation of neuroendocrine tumorigenesis, and thus, can be the foci of novel drug therapies. We also elaborate on present pharmacological strategies and clinical trials involving these intracellular pathways.
Collapse
Affiliation(s)
- Yvette Carter
- Section of Endocrine Surgery, Department of Surgery, University of Wisconsin, Madison, WI 53792, USA
| | | | | | | |
Collapse
|
2
|
Nölting S, Garcia E, Alusi G, Giubellino A, Pacak K, Korbonits M, Grossman AB. Combined blockade of signalling pathways shows marked anti-tumour potential in phaeochromocytoma cell lines. J Mol Endocrinol 2012; 49:79-96. [PMID: 22715163 PMCID: PMC4714579 DOI: 10.1530/jme-12-0028] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Currently, there is no completely effective therapy available for metastatic phaeochromocytomas (PCCs) and paragangliomas. In this study, we explore new molecular targeted therapies for these tumours, using one more benign (mouse phaeochromocytoma cell (MPC)) and one more malignant (mouse tumour tissue (MTT)) mouse PCC cell line - both generated from heterozygous neurofibromin 1 knockout mice. Several PCC-promoting gene mutations have been associated with aberrant activation of PI3K/AKT, mTORC1 and RAS/RAF/ERK signalling. We therefore investigated different agents that interfere specifically with these pathways, including antagonism of the IGF1 receptor by NVP-AEW541. We found that NVP-AEW541 significantly reduced MPC and MTT cell viability at relatively high doses but led to a compensatory up-regulation of ERK and mTORC1 signalling at suboptimal doses while PI3K/AKT inhibition remained stable. We subsequently investigated the effect of the dual PI3K/mTORC1/2 inhibitor NVP-BEZ235, which led to a significant decrease of MPC and MTT cell viability at doses below 50 nM but again increased ERK signalling. Accordingly, we next examined the combination of NVP-BEZ235 with the established agent lovastatin, as this has been described to inhibit ERK signalling. Lovastatin alone significantly reduced MPC and MTT cell viability at therapeutically relevant doses and inhibited both ERK and AKT signalling, but increased mTORC1/p70S6K signalling. Combination treatment with NVP-BEZ235 and lovastatin showed a significant additive effect in MPC and MTT cells and resulted in inhibition of both AKT and mTORC1/p70S6K signalling without ERK up-regulation. Simultaneous inhibition of PI3K/AKT, mTORC1/2 and ERK signalling suggests a novel therapeutic approach for malignant PCCs.
Collapse
Affiliation(s)
- Svenja Nölting
- Department of Endocrinology, William Harvey Research Institute and Barts Cancer Institute, Barts and the London School of Medicine, Queen Mary University of London, London, UK
| | | | | | | | | | | | | |
Collapse
|
3
|
Gupta S, Engstrom PF, Cohen SJ. Emerging therapies for advanced gastroenteropancreatic neuroendocrine tumors. Clin Colorectal Cancer 2011; 10:298-309. [PMID: 21813338 DOI: 10.1016/j.clcc.2011.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 12/21/2010] [Accepted: 01/24/2011] [Indexed: 01/17/2023]
Abstract
Neuroendocrine tumors comprise a heterogeneous group of neoplasms derived from peptide- and amine-producing cells of the neuroendocrine system. Gastroenteropancreatic NET are differentiated into tumors and carcinomas based on their malignant potential and subdivided into those arising from the pancreas (islet cell tumors or pancreatic NET) and the more classical gut "carcinoids". Moderate to well differentiated NET have historically been considered rare tumors but recent epidemiological statistics suggest that their frequency has increased substantially over the past three decades. While the incidence of NET is increasing, data from both the US and UK demonstrate no improvement in outcomes over a similar time period. Due to the generally indolent biology of NET, most patients present with advanced disease before symptoms become apparent. In patients with localized NET, the 5-year survival rates after resection range from 60 to 90%, while regional lymph node involvement decreases the 5-year survival rates after surgery to 50-75%. Patients with distant metastases have a 5 year survival rate of approximately 25-40%. Conventional cytotoxic chemotherapy is of unclear benefit in patients with these generally slow growing tumors. Multiple agents have been tested in Phase 2 and Phase 3 trials. In general, the lack of major objective responses with significant toxicities has limited routine use of traditional chemotherapy agents and has emphasized the need to develop new agents in these diseases. This review will focus on emerging molecularly-targeted treatments with an emphasis on their underlying biologic and preclinical rationale.
Collapse
Affiliation(s)
- Sameer Gupta
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | | |
Collapse
|
4
|
Chen L, Shi Y, Jiang CY, Wei LX, Wang YL, Dai GH. Expression and prognostic role of pan-Ras, Raf-1, pMEK1 and pERK1/2 in patients with hepatocellular carcinoma. EUROPEAN JOURNAL OF SURGICAL ONCOLOGY 2011; 37:513-20. [PMID: 21324414 DOI: 10.1016/j.ejso.2011.01.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 12/28/2010] [Accepted: 01/24/2011] [Indexed: 11/18/2022]
Abstract
AIMS Ras/Raf/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling cascades play important roles in the transmission of signals involved in apoptosis. Importantly, components of these pathways are aberrantly expressed in human cancer. However, there is limited data linking clinical outcomes with the aberrant expression of this pathway. The present study analyzed the prognostic values of pan-Ras, Raf-1, phosphorylated MEK1 (pMEK1) and phosphorylated ERK1/2 (pERK1/2) in hepatocellular carcinoma (HCC). METHODS Expression of pan-Ras, Raf-1, pMEK1 and pERK1/2 in 81 HCC patients who underwent curative resection was examined by immunohistochemical staining. Long-term survival after resection of patients according to the expression of pan-Ras, Raf-1, pMEK1 and pERK1/2 was assessed using univariate analysis and multiple Cox proportional hazards model. RESULTS In univariate analysis, patients with Raf-1 or pMEK1 overexpression had shorter disease-free survival (DFS) (P<0.05) and poorer overall survival (OS) (P<0.05) than groups with weak-expression of Raf-1 or pMEK1, respectively. Patients with pan-Ras overexpression had poorer overall survival (OS) (P<0.05) than the group with weak-expression of pan-Ras. Importantly, Raf-1 overexpression was a promising prognostic marker for poor survival according to multivariate Cox regression analysis (DFS, Hazard Ratio 1.807, P = 0.035; OS, Hazard Ratio 1.959, P = 0.044). CONCLUSIONS Raf-1 overexpression could be considered as an independent prognostic biomarker in HCC and may predict early tumor recurrence and death for HCC patients. It can be used to stratify patients at higher risk for poor prognosis and help to select the appropriate therapeutic regime of HCC.
Collapse
Affiliation(s)
- L Chen
- Department of Medical Oncology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, China
| | | | | | | | | | | |
Collapse
|
5
|
Abstract
Although neuroendocrine tumors are rare, the more common types such as gastrointestinal and pancreatic carcinoids, medullary thyroid cancers, and small cell lung cancers have been studied in detail during the last few years. Data published thus far indicate that multiple signaling pathways are involved in these cancers. Recent focus has been on developing novel therapeutics by targeting specific signaling pathways. This article details several of the signaling mechanisms that have been discovered to play a role in the development and progression of neuroendocrine tumors. The therapeutic options developed to address the various pathways, including their specific mechanisms of actions, are also discussed.
Collapse
Affiliation(s)
- Barbara Zarebczan
- Endocrine Surgery Research Laboratories, Department of Surgery, University of Wisconsin Carbone Cancer Center, Madison, WI 53705, USA
| | | |
Collapse
|
6
|
Ning L, Chen H, Kunnimalaiyaan M. Focal adhesion kinase, a downstream mediator of Raf-1 signaling, suppresses cellular adhesion, migration, and neuroendocrine markers in BON carcinoid cells. Mol Cancer Res 2010; 8:775-82. [PMID: 20407018 DOI: 10.1158/1541-7786.mcr-09-0525] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have recently reported that activation of the Raf-1/mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase 1/2 (MEK1/2)/ERK1/2 signaling cascade in gastrointestinal carcinoid cell line (BON) alters cellular morphology and neuroendocrine phenotype. The mechanisms by which Raf-1 mediates these changes in carcinoid cells are unclear. Here, we report that activation of the Raf-1 signaling cascade in BON cells induced the expression of focal adhesion kinase (FAK) protein, suppressed the production of neuroendocrine markers, and resulted in significant decreases in cellular adhesion and migration. Importantly, inactivation of MEK1/2 by 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene or abolition of FAK induction in Raf-1-activated BON cells by targeted siRNA led to reversal of the Raf-1-mediated reduction in neuroendocrine markers and cellular adhesion and migration. Phosphorylation site-specific antibodies detected the phosphorylated FAK(Tyr407), but not FAK(Tyr397), in these Raf-1-activated cells, indicating that FAK(Tyr407) may be associated with changes in the neuroendocrine phenotype. Overexpression of constitutively active FAK plasmids (wild-type FAK or FAK(Tyr397) mutant) into BON cells reduced neuroendocrine markers, whereas the FAK(Tyr407) mutant plasmid did not show any decrease in the levels of neuroendocrine markers, indicating that phosphorylation of FAK at the Tyr(407) residue may be important for these effects. Our results showed for the first time that FAK is an essential downstream effector of the Raf-1/MEK1/2/ERK1/2 signaling cascade and negatively regulated the neuroendocrine and metastatic phenotype in BON cells.
Collapse
Affiliation(s)
- Li Ning
- Endocrine Surgery Research Laboratories, Department of Surgery, University of Wisconsin School of Medicine and Public Health and University of Wisconsin Carbone Cancer Center, Madison, Wisconsin, USA
| | | | | |
Collapse
|
7
|
Abstract
Medullary thyroid cancer accounts for 5%-10% of all thyroid cancers. The majority of medullary thyroid cancers are sporadic, but 20% of cases are a result of a germline mutation in the ret proto-oncogene. Hereditary medullary thyroid cancer can be seen as part of the multiple endocrine neoplasia syndrome type 2A or 2B or as part of familial medullary thyroid cancer. This article discusses the current methods available for the diagnosis and evaluation of a patient with suspected medullary thyroid cancer. The management of medullary thyroid cancer is predominantly surgical excision, consisting of a total thyroidectomy and lymph node dissection. The extent and timing of surgical excision are discussed. Systemic therapeutic options are limited for medullary thyroid cancer, but several therapeutic targets show promise for the development of new therapies in the future.
Collapse
Affiliation(s)
- Rebecca S Sippel
- Department of Surgery, University of Wisconsin, Wisconsin 53792-7375, USA.
| | | | | |
Collapse
|
8
|
Deming D, Geiger P, Chen H, Vaccaro A, Kunnimalaiyaan M, Holen K. ZM336372, a Raf-1 activator, causes suppression of proliferation in a human hepatocellular carcinoma cell line. J Gastrointest Surg 2008; 12:852-7. [PMID: 18299943 DOI: 10.1007/s11605-008-0495-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepatocellular carcinoma has been described to exhibit characteristics similar to that of neuroendocrine tumors (NETs). This includes similar anti-neoplastic responses to extracellular signal-regulated kinase (ERK) activation. NET cells and HepG2 cells have both shown growth inhibition with ERK activation. ZM336372, a Raf-1 activating agent, has been shown to cause growth inhibition and suppression of hormone secretion in a neuroendocrine cell line. Here we examine treatment of the HepG2 cell line with ZM336732 to determine if a similar anti-proliferative response will be obtained. HepG2 cells were treated with ZM336372 or solvent (dimethyl sulfoxide). The resulting effect on the proliferation was measured using the 3,4-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Western blot analysis was performed to examine the activation of the Raf-1/mitogen-activated protein kinase kinase/ERK pathway, chromogranin A production, and p21CIP1 level. Growth inhibition was observed with ZM336372 in a dose-dependent fashion. Minimal baseline phosphorylation of ERK 1/2 was observed; however, activation was observed after treatment with ZM336372. Chromogranin A secretion was suppressed due to treatment with ZM336372. A dose-dependent up-regulation of p21CIP1 was observed in response to ZM336372 treatment. ZM336372 causes growth inhibition, suppression of hormone secretion, and up-regulation of cell cycle inhibitors in a human hepatocellular carcinoma cell line, similar to that previously seen in NETs.
Collapse
Affiliation(s)
- Dustin Deming
- Department of Medicine, University of Wisconsin, K4/528, Madison, WI 53792, USA
| | | | | | | | | | | |
Collapse
|
9
|
Greenblatt DY, Kunnimalaiyaan M, Chen H. Raf-1 activation in gastrointestinal carcinoid cells decreases tumor cell adhesion. Am J Surg 2007; 193:331-5; discussion 335. [PMID: 17320529 PMCID: PMC1838566 DOI: 10.1016/j.amjsurg.2006.09.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Revised: 09/20/2006] [Accepted: 09/20/2006] [Indexed: 11/18/2022]
Abstract
BACKGROUND Gastrointestinal carcinoid tumors are highly metastatic. Activation of the Raf-1 signaling pathway in carcinoid cells results in morphologic changes. These Raf-1-induced structural changes may affect cellular adhesion, thereby altering metastatic potential. METHODS An estrogen-inducible Raf-1 cell line (BON-raf) was used to study the effects of Raf-1 on cellular adhesion. Cell adhesion was measured before and after Raf-1 induction. Western blot analysis was used to confirm Raf-1 activation and measure levels of an essential adhesion regulator, beta-catenin. RESULTS Estrogen treatment of BON-raf cells resulted in Raf-1 activation and a marked decrease (68%) in cell adhesion. In the absence of Raf-1 induction, carcinoid cells expressed high levels of beta-catenin. Raf-1 activation led to decreased expression of beta-catenin. CONCLUSIONS Raf-1 induction in carcinoid cells results in a significant decrease in adhesion. Furthermore, the important adhesion regulator, beta-catenin, is decreased in activated BON-raf cells. These Raf-1-related changes in adhesion may alter the metastatic phenotype of carcinoid cells.
Collapse
Affiliation(s)
- David Yü Greenblatt
- Endocrine Surgery Research Laboratories, Section of Endocrine Surgery, Department of Surgery, University of Wisconsin, H4/750 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA
| | | | | |
Collapse
|
10
|
Kappes A, Vaccaro A, Kunnimalaiyaan M, Chen H. ZM336372, a Raf-1 activator, inhibits growth of pheochromocytoma cells. J Surg Res 2006; 133:42-5. [PMID: 16603190 DOI: 10.1016/j.jss.2006.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 02/01/2006] [Accepted: 02/02/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND Surgical resection is the only curative treatment for patients with pheochromocytomas, paragangliomas, and other catecholamine-producing tumors. Patients with metastatic disease can often have significant symptoms associated with catecholamine excess. Activation of the Raf-1/MEK/ERK1/2 pathway has been shown to inhibit growth and hormone production for neuroendocrine tumors (NE) such as carcinoid and medullary thyroid cancer. However, the role of the Raf-1/MEK/ERK1/2 signaling pathway in pheochromocytomas is unknown. MATERIALS AND METHODS Pheochromocytoma PC-12 cells were treated with varying concentrations of ZM336372, a pharmacologic Raf-1 activating drug. Levels of phosphorylated ERK1/2 and the NE marker Chromogranin A (CgA) were determined by Western blot. Cellular growth was measured by MTT cell-proliferation assay. RESULTS At baseline, PC-12 cells had very little phosphorylated ERK1/2, similar to other NE tumors. Treatment of PC-12 cells with increasing dosages of ZM336372 resulted in increased phosphorylated ERK1/2. Importantly, ZM336372 inhibited pheochromocytoma cellular proliferation. Furthermore, Raf-1 pathway activation by ZM336372 was associated with suppression of NE marker, CgA, by the tumor cells. CONCLUSIONS These data suggest that Raf-1/MEK/ERK1/2 pathway activation may be a novel strategy to treat pheochromocytoma and other catecholamine-producing tumors. In pheochromocytoma cells, ZM336372 blocks cellular proliferation and suppresses NE vasoactive peptide production. Thus, ZM336372 may be used for both therapeutic and palliative treatment for patients with pheochromocytomas.
Collapse
Affiliation(s)
- Ashley Kappes
- Endocrine Surgery Research Laboratories, Section of Endocrine Surgery, Department of Surgery, University of Wisconsin, Madison, WI 53792, USA
| | | | | | | |
Collapse
|
11
|
Abstract
PURPOSE OF REVIEW Carcinoid tumors often present with metastatic disease. Generally, these tumors can be treated conservatively. New evidence exists, however, that stage IV disease may be better managed with more aggressive medical and surgical treatment. Headway is also being made into understanding the associated fibrosis seen with advanced disease and in better understanding signaling pathways with the hope of offering future treatment options. RECENT FINDINGS Recent literature has advocated for more aggressive surgical treatment of carcinoid tumors, especially in the setting of hepatic metastases and peritoneal carcinomatosis. Octreotide and lanreotide are further being described for treating metastatic carcinoids. Radiolabeled somatostatin analogues may prove to be as effective for treating carcinoids as for visualizing them. Other potential treatment modalities include pharmacologic activation of signaling pathways to control excess hormone production. Research into fibrosis - a cause of pain, bowel obstruction, retroperitoneal vascular constriction and right heart failure - has shown that serotonin and tachykinins may be the key mediators. SUMMARY Patients with stage IV carcinoid tumors may benefit from more aggressive surgical management and new treatment modalities. The growing body of knowledge regarding important molecular signaling pathway may lead to new medical therapies and further understanding of the sequelae of excess hormone production.
Collapse
Affiliation(s)
- Alysandra Lal
- Section of Endocrine Surgery, Department of Surgery, University of Wisconsin, Madison, Wisconsin 53792, USA
| | | |
Collapse
|
12
|
Affiliation(s)
- Kyle Holen
- University of Wisconsin Comprehensive Cancer Center, Madison, WI 53792, USA
| |
Collapse
|
13
|
Van Gompel JJ, Kunnimalaiyaan M, Holen K, Chen H. ZM336372, a Raf-1 activator, suppresses growth and neuroendocrine hormone levels in carcinoid tumor cells. Mol Cancer Ther 2005; 4:910-7. [PMID: 15956248 DOI: 10.1158/1535-7163.mct-04-0334] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuroendocrine tumors, such as carcinoids, are highly metastatic neoplasms that secrete bioactive hormones resulting in carcinoid syndrome. Few curative treatments exist outside of surgical resection. We have previously shown that activation of the Raf-1 signaling pathway can suppress hormone production in carcinoid tumor cells. In this study, we investigated a novel treatment for carcinoid tumor cell growth based on pharmacologic Raf-1 activation using the compound ZM336372. Treatment of carcinoid tumor cells with ZM336372 resulted in progressive phosphorylation of Raf-1, mitogen-activated protein kinase 1/2, and extracellular signal-regulated kinase 1/2. Importantly, exposure to ZM336372 resulted in a significant reduction of bioactive hormone levels as well as the transcription factor, human achaete-scute homologue-1 in carcinoid tumor cells. Furthermore, treatment with ZM336372 led to a marked suppression of cellular proliferation and induction of the cell cycle inhibitors p21 and p18. In summary, ZM336372 targets both proliferation and palliative issues associated with carcinoid tumor cells, and therefore, warrants further investigation as a possible therapeutic strategy for patients with carcinoid tumors.
Collapse
Affiliation(s)
- Jamie J Van Gompel
- Department of Surgery, University of Wisconsin Medical School, Madison, 53792, USA
| | | | | | | |
Collapse
|
14
|
Musunuru S, Carpenter JE, Sippel RS, Kunnimalaiyaan M, Chen H. A mouse model of carcinoid syndrome and heart disease. J Surg Res 2005; 126:102-5. [PMID: 15916982 DOI: 10.1016/j.jss.2005.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 12/31/2004] [Accepted: 01/03/2005] [Indexed: 11/17/2022]
Abstract
BACKGROUND Carcinoid heart disease occurs in over 65% of patients with the carcinoid syndrome and is characterized by fibrous thickening of cardiac valves, leading to heart failure. Whether serotonin is directly responsible for these cardiac abnormalities is unknown. Therefore, to further understand the etiology and pathophysiology of carcinoid heart disease, we developed an animal model of the carcinoid syndrome. MATERIALS AND METHODS Seventeen nude mice underwent intrasplenic injection of human pancreatic carcinoid BON cells (10(7)) and then were euthanized 9 weeks later. Murine livers were analyzed by immunohistochemistry. Murine hearts were sectioned and the surface area of the right heart valves determined. Blood was also collected and analyzed for platelet serotonin by ELISA. RESULTS Sixty-five percent of the mice developed gross carcinoid liver metastases demonstrated by chromogranin-A-staining lesions within the liver. Mice with carcinoid liver metastases had elevated platelet serotonin levels (1058 +/- 529 ng/ml versus 123 +/- 52 ng/ml, P = 0.002) when compared to the controls. Animals with carcinoid liver metastases also had a trend toward greater tricuspid valvular surface areas (242 +/- 24 versus 174 +/- 25 microm, P = 0.08). On histological examination, this increase in tricuspid surface area in mice with liver metastases appeared to be due to fibrosis of the valvular tissues, consistent with the pathologic findings of carcinoid heart disease. CONCLUSIONS Using this novel animal model of carcinoid syndrome, the tricuspid valve thickening resembling carcinoid heart disease could be due to exposure to factors such as serotonin secreted by carcinoid tumor cells.
Collapse
Affiliation(s)
- Sandeepa Musunuru
- Department of Surgery, University of Wisconsin Medical School, Madison, Wisconsin 53792, USA
| | | | | | | | | |
Collapse
|
15
|
Liman J, Ganesan S, Dohm CP, Krajewski S, Reed JC, Bähr M, Wouters FS, Kermer P. Interaction of BAG1 and Hsp70 mediates neuroprotectivity and increases chaperone activity. Mol Cell Biol 2005; 25:3715-25. [PMID: 15831476 PMCID: PMC1084317 DOI: 10.1128/mcb.25.9.3715-3725.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It was recently shown that Bcl-2-associated athanogene 1 (BAG1) is a potent neuroprotectant as well as a marker of neuronal differentiation. Since there appears to exist an equilibrium within the cell between BAG1 binding to heat shock protein 70 (Hsp70) and BAG1 binding to Raf-1 kinase, we hypothesized that changing BAG1 binding characteristics might significantly alter BAG1 function. To this end, we compared rat CSM14.1 cells and human SHSY-5Y cells stably overexpressing full-length BAG1 or a deletion mutant (BAGDeltaC) no longer capable of binding to Hsp70. Using a novel yellow fluorescent protein-based foldase biosensor, we demonstrated an upregulation of chaperone in situ activity in cells overexpressing full-length BAG1 but not in cells overexpressing BAGDeltaC compared to wild-type cells. Interestingly, in contrast to the nuclear and cytosolic localizations of full-length BAG1, BAGDeltaC was expressed exclusively in the cytosol. Furthermore, cells expressing BAGDeltaC were no longer protected against cell death. However, they still showed accelerated neuronal differentiation. Together, these results suggest that BAG1-induced activation of Hsp70 is important for neuroprotectivity, while BAG1-dependent modulation of neuronal differentiation in vitro is not.
Collapse
Affiliation(s)
- Jan Liman
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - Sundar Ganesan
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - Christoph P. Dohm
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - Stan Krajewski
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - John C. Reed
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - Mathias Bähr
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
| | - Fred S. Wouters
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
- Corresponding author. Mailing address for Fred S. Wouters: Cell Biophysics Group, European Neuroscience Institute Göttingen, Waldweg 33, 37075 Göttingen, Germany. Phone: 0049-551-3912368. Fax: 0049-551-3912346. E-mail:
| | - Pawel Kermer
- Neurologische Klinik, Universität Göttingen, Cell Biophysics Group, European Neuroscience Institute Göttingen, Göttingen, Germany, The Burnham Institute, La Jolla, California
- Corresponding author. Mailing address for Pawel Kermer: Neurologische Klinik, Universität Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. Phone: 49-551-394927. Fax: 49-551-3914302. E-mail:
| |
Collapse
|
16
|
Chen H, Kunnimalaiyaan M, Van Gompel JJ. Medullary thyroid cancer: the functions of raf-1 and human achaete-scute homologue-1. Thyroid 2005; 15:511-21. [PMID: 16029117 DOI: 10.1089/thy.2005.15.511] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Medullary thyroid cancer (MTC) is a prototypic neuroendocrine tumor of the thyroid C cells. Other than surgery, there are no curative therapies for MTC. In this review, we detail recent studies that suggest that targeting specific signaling pathways may be a viable strategy to control MTC tumor progression. Specifically, we discuss the role of the raf-1 and achaete-scute homologue-1 pathways in the MTC tumor growth and differentiation.
Collapse
Affiliation(s)
- Herbert Chen
- Department of Surgery, University of Wisconsin Medical School, the University of Wisconsin Comprehensive Cancer Center, Madison, Wisconsin, USA.
| | | | | |
Collapse
|
17
|
Van Gompel JJ, Chen H. Insulin-like growth factor 1 signaling in human gastrointestinal carcinoid tumor cells. Surgery 2005; 136:1297-302. [PMID: 15657590 DOI: 10.1016/j.surg.2004.06.061] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Background Insulin-like growth factor 1 (IGF-1) is an autocrine regulator of carcinoid tumors. Blockade of IGF-1 signaling has been proposed as a therapeutic target in the treatment of patients with carcinoid syndrome. We hypothesized that the induction of parallel raf-1/MEK1 pathways will block IGF-1-mediated chromogranin A (CgA) maintenance. Methods Human gastrointestinal carcinoid tumor cells (BON) were treated with IGF-1 (0-500 ng/mL). Raf-1/MEK1 activation was achieved with an estrogen-inducible raf-1 vector that was transduced into BON cells. Activation of IGF-1/raf-1 pathways was determined by phosphorylation of downstream targets p70s6 and ERK1/2. The secreted and intercellular levels of CgA were measured in conditioned media and whole cell extracts by Western and enzyme-linked immunosorbent assay analysis. Results IGF-1 and raf-1 pathways were activated successfully in BON cells, as shown by high levels of phosphorylated p70s6 and phosphorylated ERK1/2, respectively. Treatment of BON cells with IGF-1 stimulated the release of CgA, while high intracellular CgA levels were maintained. The activation of raf-1/MEK1 reversed the effect of IGF-1 treatment by the depletion of intracellular CgA. Conclusions The induction of the raf-1/MEK1 pathway blocks IGF-1-mediated intracellular neuroendocrine hormone regulation. Therefore, raf-1/MEK1 activation may be a viable method to block IGF-1-mediated cellular effects and serve as a therapeutic target in gastrointestinal carcinoid tumors.
Collapse
Affiliation(s)
- Jamie Joseph Van Gompel
- Department of Surgery, University of Wisconsin Comprehensive Cancer Center, 600 Highland Avenue, Madison, WI 53792, USA
| | | |
Collapse
|
18
|
Steelman LS, Pohnert SC, Shelton JG, Franklin RA, Bertrand FE, McCubrey JA. JAK/STAT, Raf/MEK/ERK, PI3K/Akt and BCR-ABL in cell cycle progression and leukemogenesis. Leukemia 2004; 18:189-218. [PMID: 14737178 DOI: 10.1038/sj.leu.2403241] [Citation(s) in RCA: 499] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The roles of the JAK/STAT, Raf/MEK/ERK and PI3K/Akt signal transduction pathways and the BCR-ABL oncoprotein in leukemogenesis and their importance in the regulation of cell cycle progression and apoptosis are discussed in this review. These pathways have evolved regulatory proteins, which serve to limit their proliferative and antiapoptotic effects. Small molecular weight cell membrane-permeable drugs that target these pathways have been developed for leukemia therapy. One such example is imatinib mesylate, which targets the BCR-ABL kinase as well as a few structurally related kinases. This drug has proven to be effective in the treatment of CML patients. However, leukemic cells have evolved mechanisms to become resistant to this drug. A means to combat drug resistance is to target other prominent signaling components involved in the pathway or to inhibit BCR-ABL by other mechanisms. Treatment of imatinib-resistant leukemia cells with drugs that target Ras (farnysyl transferase inhibitors) or with the protein destabilizer geldanamycin has proven to be a means to inhibit the growth of resistant cells. This review will tie together three important signal transduction pathways involved in the regulation of hematopoietic cell growth and indicate how their expression is dysregulated by the BCR-ABL oncoprotein.
Collapse
Affiliation(s)
- L S Steelman
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA
| | | | | | | | | | | |
Collapse
|
19
|
Sippel RS, Carpenter JE, Kunnimalaiyaan M, Chen H. The role of human achaete-scute homolog-1 in medullary thyroid cancer cells. Surgery 2004; 134:866-71; discussion 871-3. [PMID: 14668716 DOI: 10.1016/s0039-6060(03)00418-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Human achaete-scute homolog-1 (hASH1) is a transcription factor that is expressed highly in neuroendocrine tumors such as medullary thyroid cancer (MTC). Thyroid C-cells do not develop in hASH1 knockout mice, which suggests that hASH1 is essential for normal C-cell development. METHODS To determine the effect of raf-1 induction on hASH1 and hormone production, we used an estrogen inducible raf-1 construct in MTC cell line (TT) cells (TT-raf cells). TT or TT-raf cells were treated with control or 1 microM estradiol. After 48 hours, the cells were analyzed for levels of hASH1 and chromogranin A by Western blotting and for calcitonin production by enzyme-linked immunosorbent assay. RESULTS Activation of raf-1 in the TT-raf cells resulted in high levels of phosphorylated MEK and ERK1/2, a morphologic transdifferentiation, and a decrease in chromogranin A and calcitonin levels that are associated with a reduction in hASH1 production. Furthermore, using MEK inhibitors, we demonstrated that these raf-1-mediated changes are dependent on MEK but not ERK1/2 activation. CONCLUSION hASH1 down-regulation by raf-1 in MTC cells is associated with a significant decrease in hormone production. Thus, hASH1 appears to be important in the endocrine phenotype of MTC tumors and may serve as a molecular target for the treatment of patients with MTC.
Collapse
Affiliation(s)
- Rebecca S Sippel
- Department of Surgery, The University of Wisconsin Medical School and the University of Wisconsin Comprehensive Cancer Center, 600 Highland Avenue, Madison, WI 53792, USA
| | | | | | | |
Collapse
|
20
|
Sippel RS, Carpenter JE, Kunnimalaiyaan M, Lagerholm S, Chen H. Raf-1 activation suppresses neuroendocrine marker and hormone levels in human gastrointestinal carcinoid cells. Am J Physiol Gastrointest Liver Physiol 2003; 285:G245-54. [PMID: 12851216 DOI: 10.1152/ajpgi.00420.2002] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastrointestinal carcinoid cells secrete multiple neuroendocrine markers and hormones including 5-HT and chromogranin A. The intracellular signaling pathways that regulate production of bioactive molecules are not completely understood. Our aim was to determine whether activation of the raf-1/MEK/MAPK signal transduction pathway in carcinoid cells could modulate production of neuroendocrine markers and hormones. Human pancreatic carcinoid cells (BON) were stably transduced with an estrogen-inducible raf-1 construct creating BON-raf cells. Activation of raf-1 in BON-raf cells led to a marked induction of phosphorylated MEK and ERK1/2 within 48 h. Importantly, raf-1 activation resulted in morphological changes accompanied by a marked decrease in neuroendocrine secretory granules by electronmicroscopy. Moreover, induction of raf-1 in BON-raf cells led to significant reductions in 5-HT, chromogranin A, and synaptophysin levels. Furthermore, treatment of BON-raf cells with MEK inhibitors PD-98059 and U-0126 blocked raf-1-mediated morphological changes and hormone suppression but not ERK1/2 phosphorylation. These results show that raf-1 induction suppresses neuroendocrine marker and hormone production in human gastrointestinal carcinoid cells via a pathway dependent on MEK activation.
Collapse
Affiliation(s)
- Rebecca S Sippel
- Dept. of Surgery, Univ. of Wisconsin Medical School, University of Wisconsin Comprehensive Cancer Center, Madison 53792, USA
| | | | | | | | | |
Collapse
|