1
|
The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management. Int J Mol Sci 2020. [DOI: 10.3390/ijms21103494
expr 969553959 + 931886332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.
Collapse
|
2
|
The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management. Int J Mol Sci 2020; 21:ijms21103494. [PMID: 32429087 PMCID: PMC7279011 DOI: 10.3390/ijms21103494] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 12/24/2022] Open
Abstract
Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.
Collapse
|
3
|
Symvoulakis EK, Zaravinos A, Panutsopulos D, Zoras O, Papalambros E, Sigala F, Spandidos DA. Highly Conserved Sequence of Exon 15 BRAF Gene and KRAS Codon 12 Mutation among Greek Patients with Colorectal Cancer. Int J Biol Markers 2018; 22:12-8. [PMID: 17393356 DOI: 10.1177/172460080702200102] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background The RAS/RAF/MEK/MAP kinase pathway is essential to intracellular signaling transduction regulating cell proliferation, differentiation and death. We investigated the occurrence of exon 15 BRAF and KRAS codon 12 mutations among Greek patients with colorectal cancer. Methods Sixty-one samples from patients with sporadic colorectal adenocarcinomas were studied for exon 15 BRAF mutations. DNA from surgically resected specimens was analyzed by a combination of polymerase chain reaction and direct sequencing. KRAS codon 12 mutational analysis was technically possible in 58 samples (58/61) by a combination of polymerase chain reaction and restriction fragment length polymorphism. Results No exon 15 BRAF mutations were detected in any of the colon cancer specimens. The frequency of KRAS codon 12 mutations was 29.3% (17/58). Patients aged <70 years more frequently presented carcinomas harboring KRAS codon 12 mutations than patients aged >70 years (p=0.028). Patients between 61 and 70 years of age were more likely to be carriers of this mutation (p=0.040). Conclusions Despite the limited study sample, our data suggest that BRAF mutations might be present less frequently than KRAS mutations in Greek patients with colorectal carcinomas. Further research involving larger patient series will be necessary to confirm these findings and to assess possible ethnic, environmental and lifestyle influences on BRAF and KRAS mutagenesis.
Collapse
Affiliation(s)
- E K Symvoulakis
- Laboratory of Virology, Medical School, University of Crete, Heraklion, Crete, Greece
| | | | | | | | | | | | | |
Collapse
|
4
|
Blocking endothelin-1-receptor/β-catenin circuit sensitizes to chemotherapy in colorectal cancer. Cell Death Differ 2017; 24:1811-1820. [PMID: 28708138 PMCID: PMC5596423 DOI: 10.1038/cdd.2017.121] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/09/2017] [Accepted: 06/23/2017] [Indexed: 12/16/2022] Open
Abstract
The limited clinical response to conventional chemotherapeutics observed in colorectal cancer (CRC) may be related to the connections between the hyperactivated β-catenin signaling and other pathways in CRC stem-like cells (CRC-SC). Here, we show the mechanistic link between the endothelin-1 (ET-1)/ET-1 receptor (ET-1R) signaling and β-catenin pathway through the specific interaction with the signal transducer β-arrestin1 (β-arr1), which initiates signaling cascades as part of the signaling complex. Using a panel of patient-derived CRC-SC, we show that these cells secrete ET-1 and express ETAR and β-arr1, and that the activation of ETAR/β-arr1 axis promotes the cross-talk with β-catenin signaling to sustain stemness, epithelial-to-mesenchymal transition (EMT) phenotype and response to chemotherapy. Upon ETAR activation, β-arr1 acts as a transcription co-activator that binds β-catenin, thereby promoting nuclear complex with β-catenin/TFC4 and p300 and histone acetylation, inducing chromatin reorganization on target genes, such as ET-1. The enhanced transcription of ET-1 increases the self-sustained ET-1/β-catenin network. All these findings provide a strong rationale for targeting ET-1R to hamper downstream β-catenin/ET-1 autocrine circuit. Interestingly, treatment with macitentan, a dual ETAR and ETBR antagonist, able to interfere with tumor and microenvironment, disrupts the ET-1R/β-arr1-β-catenin interaction impairing pathways involved in cell survival, EMT, invasion, and enhancing sensitivity to oxaliplatin (OX) and 5-fluorouracil (5-FU). In CRC-SC xenografts, the combination of macitentan and OX or 5-FU enhances the therapeutic effects of cytotoxic drugs. Together, these results provide mechanistic insight into how ET-1R coopts β-catenin signaling and offer a novel therapeutic strategy to manage CRC based on the combination of macitentan and chemotherapy that might benefit patients whose tumors show high ETAR and β-catenin expression.
Collapse
|
5
|
Lynch JR, Wang JY. G Protein-Coupled Receptor Signaling in Stem Cells and Cancer. Int J Mol Sci 2016; 17:ijms17050707. [PMID: 27187360 PMCID: PMC4881529 DOI: 10.3390/ijms17050707] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 12/28/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are a large superfamily of cell-surface signaling proteins that bind extracellular ligands and transduce signals into cells via heterotrimeric G proteins. GPCRs are highly tractable drug targets. Aberrant expression of GPCRs and G proteins has been observed in various cancers and their importance in cancer stem cells has begun to be appreciated. We have recently reported essential roles for G protein-coupled receptor 84 (GPR84) and G protein subunit Gαq in the maintenance of cancer stem cells in acute myeloid leukemia. This review will discuss how GPCRs and G proteins regulate stem cells with a focus on cancer stem cells, as well as their implications for the development of novel targeted cancer therapies.
Collapse
Affiliation(s)
- Jennifer R Lynch
- Cancer and Stem Cell Biology Group, Children's Cancer Institute, Lowy Cancer Research Centre, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Jenny Yingzi Wang
- Cancer and Stem Cell Biology Group, Children's Cancer Institute, Lowy Cancer Research Centre, University of New South Wales, Sydney, NSW 2052, Australia.
- Centre for Childhood Cancer Research, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia.
| |
Collapse
|
6
|
The influence of folate supplementation on global gene expression in normal colonic mucosa of subjects with colorectal adenoma. Mol Nutr Food Res 2013; 57:709-20. [DOI: 10.1002/mnfr.201200617] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/12/2012] [Accepted: 11/18/2012] [Indexed: 12/31/2022]
|
7
|
Abstract
G-protein-coupled receptors (GPCRs), which represent the largest gene family in the human genome, play a crucial role in multiple physiological functions as well as in tumor growth and metastasis. For instance, various molecules like hormones, lipids, peptides and neurotransmitters exert their biological effects by binding to these seven-transmembrane receptors coupled to heterotrimeric G-proteins, which are highly specialized transducers able to modulate diverse signaling pathways. Furthermore, numerous responses mediated by GPCRs are not dependent on a single biochemical route, but result from the integration of an intricate network of transduction cascades involved in many physiological activities and tumor development. This review highlights the emerging information on the various responses mediated by a selected choice of GPCRs and the molecular mechanisms by which these receptors exert a primary action in cancer progression. These findings provide a broad overview on the biological activity elicited by GPCRs in tumor cells and contribute to the identification of novel pharmacological approaches for cancer patients.
Collapse
|
8
|
Liakou P, Tepetes K, Germenis A, Leventaki V, Atsaves V, Patsouris E, Roidis N, Hatzitheophilou K, Rassidakis GZ. Expression patterns of endothelin-1 and its receptors in colorectal cancer. J Surg Oncol 2011; 105:643-9. [PMID: 22213082 DOI: 10.1002/jso.23017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 12/01/2011] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVES Endothelin-1 (ET-1), a potent vasoconstricting peptide, plays an important role in carcinogenesis. Previous in vitro studies have shown that colorectal cancer cells produce ET-1. METHODS ET-1 and its receptors ET-A (ET(A) R) and ET-B (ET(B) R) were analyzed in colorectal cancer cell lines and tumors by Western blot and immunohistochemistry. Also, ET-1 levels were measured by ELISA in blood samples collected before and after tumor resection. RESULTS ET-1 was immunohistochemically expressed by tumor cells at a variable level in 39 cases tested. The adjacent normal mucosa was negative for ET-1 expression. Strong ET(A) R expression observed in the deeper infiltrating areas at the periphery of neoplastic tissue correlated significantly with tumor stage. ET(B) R levels were very low or undetectable. Western blot analysis in paired (normal, tumor) fresh-frozen samples of colorectal cancers and in four colon carcinoma cell lines confirmed these findings. In addition, lower levels of ET-1 in the peripheral circulation after the tumor resection were found by ELISA as compared to those observed before surgery. CONCLUSIONS ET-1 and ET(A) R, but not ET(B) R, are expressed at a higher level in primary and cultured colon carcinoma cells as compared to normal colon mucosa cells. Further functional studies are needed to explore the role of ET-1/ET(A) R axis in colon carcinogenesis.
Collapse
|
9
|
Rahbari NN, Reissfelder C, Mühlbayer M, Weidmann K, Kahlert C, Büchler MW, Weitz J, Koch M. Correlation of circulating angiogenic factors with circulating tumor cells and disease recurrence in patients undergoing curative resection for colorectal liver metastases. Ann Surg Oncol 2011; 18:2182-91. [PMID: 21598056 DOI: 10.1245/s10434-011-1761-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Indexed: 11/18/2022]
Abstract
BACKGROUND Circulating angiogenic factors (CAF) have been shown as therapeutic targets and prognostic biomarkers in metastatic colorectal cancer. However, their correlation with circulating tumor cells (CTC) is unknown, as is their role as prognostic biomarkers in patients amenable for curative resection. METHODS Preoperative blood samples were collected in patients undergoing potentially curative resection of colorectal liver metastases. Serum levels of eight CAF and CTC were analyzed by using ELISA and CK20 RT-PCR, respectively. Prognostic factors were identified by a Cox proportional hazards model. RESULTS A total of 107 patients were eligible for final analyses. Circulating levels of PlGF, EGF, and bFGF were increased, whereas PDGF-A and Ang-1 levels were decreased in patients compared with healthy control subjects. CTC were detected in 36 of 63 patients (57%) and were associated with significantly lower levels of EGF and bFGF. On univariate analyses, multiple metastases (p = 0.04), a MSKCC risk score >2 (p = 0.004), and detection of CTC (p = 0.05) were associated with disease recurrence. Multivariate analysis, including the panel of eight CAF, revealed a MSKCC score >2 [hazard ratio (HR), 2.01; 95% confidence interval (CI), 1.11-3.82; p = 0.02] and low levels of circulating PlGF (HR, 0.26; 95% CI, 0.08-0.81; p = 0.02) as independent predictors of poor recurrence-free survival. CONCLUSIONS CAF may indicate patients who are at high risk for disease recurrence. The notion that CAF may identify patients who benefit from adjuvant therapy or antiangiogenic agents warrants further investigation.
Collapse
Affiliation(s)
- Nuh N Rahbari
- Department of General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Lloyd GM, Neal CP, Arun C, London NJM, Hemingway DM. The prognostic value of circulating big endothelin-1 in patients undergoing potentially curative resection for colorectal cancer. Colorectal Dis 2011; 13:290-5. [PMID: 19906052 DOI: 10.1111/j.1463-1318.2009.02129.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Elevated circulating endothelin-1 (ET-1) has been demonstrated in patients with colorectal cancer (CRC). The aim of this study was to examine the prognostic value of plasma big ET-1, the stable precursor of ET-1, in cancer-specific survival in patients having curative surgery for CRC. METHOD Seventy-seven patients undergoing potentially curative surgery for CRC between January 2000 and January 2001 were studied. Clinicopathological data were obtained from a prospectively maintained database including long-term follow-up information (median follow up 84 months). The influence of plasma big ET-1 and clinicopathological variables upon over cancer-specific survival was determined by univariate and multivariable analysis. RESULTS On univariate analysis, advanced Dukes' stage, tumour size and patient age were associated with shortened overall survival. Advanced Dukes' stage was the only factor associated with shortened survival on multivariable analysis. Plasma big ET-1 showed no association with either overall or cancer-specific survival following CRC resection. CONCLUSION Plasma big ET-1 appears to have no prognostic value in primary CRC.
Collapse
Affiliation(s)
- G M Lloyd
- Department of Colorectal Surgery, Leicester Royal Infirmary, Leicester, UK.
| | | | | | | | | |
Collapse
|
11
|
Uemura M, Yamamoto H, Takemasa I, Mimori K, Hemmi H, Mizushima T, Ikeda M, Sekimoto M, Matsuura N, Doki Y, Mori M. Jumonji domain containing 1A is a novel prognostic marker for colorectal cancer: in vivo identification from hypoxic tumor cells. Clin Cancer Res 2010; 16:4636-46. [PMID: 20823141 DOI: 10.1158/1078-0432.ccr-10-0407] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE This study aimed to identify novel hypoxia-inducible and prognostic markers in vivo from hypoxic tumor cells. EXPERIMENTAL DESIGN Using carbonic anhydrase 9 and CD34 as a guide for hypoxic tumor cells, laser capture microdissection was used to isolate colorectal cancer (CRC) liver metastases. The samples were analyzed by microarray analysis, in parallel with five CRC cell lines cultured under hypoxic conditions. To evaluate the prognostic impact of the expression of certain genes, samples from a total of 356 CRC patients were analyzed by microarray or quantitative reverse transcription-PCR. In vitro mechanistic studies and in vivo therapeutic experiments were also done about a histone H3 Lys(9) demethylase, Jumonji domain containing 1A (JMJD1A). RESULTS Several candidate genes were identified by microarray analysis of liver metastases and culturing of CRC cells under hypoxic conditions. Among them, we found that JMJD1A was a novel independent prognostic factor for CRC (P = 0.013). In vitro assays revealed that loss of JMJD1A by small interfering RNA treatment was associated with a reduction of proliferative activity and decrease in invasion of CRC cell lines. Furthermore, treatment with an adenovirus system for antisense JMJD1A construct displayed prominent therapeutic effects when injected into established tumor xenografts of the CRC cell lines HCT116 and DLD1. CONCLUSIONS JMJD1A is a useful biomarker for hypoxic tumor cells and a prognostic marker that could be a promising therapeutic target against CRC.
Collapse
Affiliation(s)
- Mamoru Uemura
- Department of Surgery, Gastroenterological Surgery, Graduate School of Medicine, Faculty of Medicine, Osaka University, Osaka, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Endothelins are important mediators of physiological and pathophysiologic processes including cardiovascular disorders, pulmonary disease, renal diseases and many others. Additionally, endothelins are involved in many other important processes such as development, cancer biology, wound healing, and even neurotransmission. Here, we review the cell and molecular biology as well as the prominent pathophysiological aspects of the endothelin system.
Collapse
|
13
|
Kandalaft LE, Facciabene A, Buckanovich RJ, Coukos G. Endothelin B receptor, a new target in cancer immune therapy. Clin Cancer Res 2009; 15:4521-8. [PMID: 19567593 DOI: 10.1158/1078-0432.ccr-08-0543] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The endothelins and their G protein-coupled receptors A and B have been implicated in numerous diseases and have recently emerged as pivotal players in a variety of malignancies. Tumors overexpress the endothelin 1 (ET-1) ligand and the endothelin-A-receptor (ET(A)R). Their interaction induces tumor growth and metastasis by promoting tumor cell survival and proliferation, angiogenesis, and tissue remodeling. On the basis of results from xenograft models, drug development efforts have focused on antagonizing the autocrine-paracrine effects mediated by ET-1/ET(A)R. In this review, we discuss a novel role of the endothelin-B-receptor (ET(B)R) in tumorigenesis and the effect of its blockade during cancer immune therapy. We highlight key characteristics of the B receptor such as its specific overexpression in the tumor compartment; and specifically, in the tumor endothelium, where its activation by ET-1 suppresses T-cell adhesion and homing to tumors. We also review our recent findings on the effects of ET(B)R-specific blockade in increasing T-cell homing to tumors and enhancing the efficacy of otherwise ineffective immunotherapy.
Collapse
Affiliation(s)
- Lana E Kandalaft
- Ovarian Cancer Research Center University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | |
Collapse
|
14
|
Grant K, Knowles J, Dawas K, Burnstock G, Taylor I, Loizidou M. Mechanisms of endothelin 1-stimulated proliferation in colorectal cancer cell lines. Br J Surg 2006; 94:106-12. [PMID: 17078114 DOI: 10.1002/bjs.5536] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Abstract
Background
The peptide endothelin (ET) 1 promotes proliferation in a number of epithelial cancers. The aim of this study was to identify the mechanism of ET-1-stimulated proliferation in colorectal cancer cells in vitro.
Methods
The effects of ET-1 on colorectal cancer cell lines HT29, LIM1215 and SW620 were studied. Cells were cultured with ET-1 plus antagonists/inhibitors to ETA or ETB receptors, G protein subtypes, phosphoinositide 3-kinase (PI3K) or protein kinase C (PKC). DNA replication and apoptosis were investigated by 5-bromo-2′-deoxyuridine incorporation and Annexin V staining. Transactivation of the epidermal growth factor (EGF) receptor was investigated by blockade of the receptor in the presence of ET-1, measurement of levels of phosphorylated EGF receptor in the presence of ET-1, and comparing the effects of ET-1 and EGF on cell proliferation.
Results
ET-1 significantly stimulated growth of all cell lines via ETA receptors. ET-1 stimulated DNA replication, not apoptosis. ET-1-stimulated growth was inhibited by antagonism of pertussis toxin-sensitive G proteins, PI3K and PKC. Inhibition of the EGF receptor reduced the effect of ET-1. ET-1 increased levels of phosphorylated EGF receptor via the ETA receptor.
Conclusion
ET-1 increased DNA replication in colorectal cancer cells via the ETA receptor. This mitogenic action was mediated via pertussis toxin-sensitive G proteins, PI3K, PKC and transactivation of the EGF receptor.
Collapse
Affiliation(s)
- K Grant
- Department of Surgery, Royal Free and University College Medical School, University College London, London, UK
| | | | | | | | | | | |
Collapse
|