Epidermal growth factor down-regulates the expression of neutrophil gelatinase-associated lipocalin (NGAL) through E-cadherin in pancreatic cancer cells.
BACKGROUND
The authors previously reported that neutrophil gelatinase-associated lipocalin (NGAL) overexpression significantly blocked invasion and angiogenesis of pancreatic ductal adenocarcinoma (PDAC). They also demonstrated a loss of NGAL expression in the advanced stages of PDAC. However, little is known regarding the mechanisms of NGAL regulation in PDAC. Because the epidermal growth factor (EGF)-EGF receptor (EGFR) axis is up-regulated significantly in PDAC, they examined EGF-mediated NGAL regulation in these cells.


METHODS
The NGAL-positive cell lines AsPC-1 and BxPC-3 were used as a model system. Quantitative real-time polymerase chain reaction (RT-PCR), Western blot analysis, and immunofluorescence studies were used to investigate EGF-mediated effects on NGAL expression. E-cadherin expression was manipulated using lentiviral overexpression or small hairpin RNA constructs. NGAL promoter activity was assessed by luciferase-reporter assay and electrophoretic mobility shift assay.


RESULTS
NGAL expression was positively associated with tumor differentiation and was down-regulated significantly after EGF treatment along with a concomitant reduction of E-cadherin expression in PDAC cells. E-cadherin down-regulation was partly through the EGFR-dependent mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) (MEK-ERK) signaling pathway. In addition, E-cadherin down-regulation reduced NGAL expression in PDAC cells, whereas overexpression of E-cadherin led to increased NGAL expression and partly rescued the inhibition of NGAL expression by EGF. Furthermore, EGF, in part through E-cadherin, reduced NGAL promoter activity by blocking nuclear factor κB (NF-κB) activation.


CONCLUSIONS
The current study demonstrated for the first time that EGF potently blocked NGAL expression in PDAC cells. This effect was mediated in part through activation of the EGFR-MEK-ERK signaling pathway, which, in turn, down-regulated E-cadherin with a subsequent reduction in NF-κB activation. These findings illustrate a novel mechanism by which EGF regulates NGAL expression in PDAC.
Department of Gastroenterology, Hepatology, and Nutrition, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
Zhimin
Z
Tong
Subhankar
S
Chakraborty
Bokyung
B
Sung
Pooja
P
Koolwal
Sukhwinder
S
Kaur
Bharat B
BB
Aggarwal
Sendurai A
SA
Mani
Robert S
RS
Bresalier
Surinder K
SK
Batra
Sushovan
S
Guha
D000209:Acute-Phase Proteins / Q000235:genetics* / Q000378:metabolism; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D000071068:Lipocalin-2; D054834:Lipocalins / Q000235:genetics* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
D000209:Acute-Phase Proteins; D015820:Cadherins; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D004815:Epidermal Growth Factor; D048049:Extracellular Signal-Regulated MAP Kinases
E-cadherin; epidermal growth factor; neutrophil gelatinase associated lipocalin; nuclear factor κB; pancreatic cancer