Lipocalin 2 diminishes invasiveness and metastasis of Ras-transformed cells

Adipokines and epithelial-mesenchymal transition (EMT) in cancer

Obesity is a significant risk factor for cancer development. Within the tumor microenvironment, adipocytes interact with cancer cells, immune cells, fibroblasts and endothelial cells, and orchestrate several signaling pathways by secreting bioactive molecules, including adipokines. Adipokines or adipocytokines are produced predominantly by adipocytes and function as autocrine, paracrine and endocrine mediators. Adipokines can exert pro- and anti-inflammatory functions, and they play a pivotal role in the state of chronic low-grade inflammation that characterizes obesity. Epithelial-mesenchymal transition (EMT), a complex biological process whereby epithelial cells acquire the invasive, migratory mesenchymal phenotype is well-known to be implicated in cancer progression and metastasis. Emerging evidence suggests that there is a link between adipokines and EMT. This may contribute to the correlation that has been documented between obesity and cancer progression. This review summarizes the existing body of evidence supporting an association between the process of EMT in cancer and the adipokines leptin, adiponectin, resistin, visfatin/NAMPT, lipocalin-2/NGAL, as well as other newly discovered adipokines including chemerin, nesfatin-1/nucleobindin-2, AZGP1, SFRP5 and FABP4.

Osteoblast-derived extracellular vesicles exert osteoblastic and tumor-suppressive functions via SERPINA3 and LCN2 in prostate cancer

Clinically, the osteolytic phenotype is rare in prostate cancer (PCa), and the prognosis is generally worse than that of the osteoblastic phenotype. Osteoblastic prostate cancer (BPCa) is a major type of bone metastasis. Several factors responsible for osteogenesis have been identified, but the molecular mechanism of osteoblastic bone metastasis in PCa is not fully understood. Here, we show the osteogenic and tumor-suppressive roles of SERPINA3 and LCN2 in BPCa. In a co-culture of osteoblasts (OBs) and BPCa cells, SERPINA3 and LCN2 were remarkably upregulated in BPCa via OB-derived extracellular vesicles, while they were not in the co-culture of OBs and osteolytic prostate cancer (LPCa) cells. In both the co-culture system and mouse xenograft experiments with intracaudal injection, enhanced expression of SERPINA3 and LCN2 in PCa led to osteogenesis. Additionally, the addition of SERPINA3 and LCN2 to BPCa cells significantly suppressed the proliferative potential. Retrospective analysis also confirmed that high expression levels of SERPINA3 and LCN2 were significantly correlated with a better prognosis. Our results may partially explain how osteoblastic bone metastasis develops and why the prognosis for BPCa is relatively better than that for LPCa.

The Review of Current Knowledge on Neutrophil Gelatinase-Associated Lipocalin (NGAL)

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein that is secreted mostly by immune cells such as neutrophils, macrophages, and dendritic cells. Its production is stimulated in response to inflammation. The concentrations of NGAL can be measured in plasma, urine, and biological fluids such as peritoneal effluent. NGAL is known mainly as a biomarker of acute kidney injury and is released after tubular damage and during renal regeneration processes. NGAL is also elevated in chronic kidney disease and dialysis patients. It may play a role as a predictor of the progression of renal function decreases with complications and mortality due to kidney failure. NGAL is also useful in the diagnostic processes of cardiovascular diseases. It is highly expressed in injured heart tissue and atherosclerostic plaque; its serum concentrations correlate with the severity of heart failure and coronary artery disease. NGAL increases inflammatory states and its levels rise in arterial hypertension, obesity, diabetes, and metabolic complications such as insulin resistance, and is also involved in carcinogenesis. In this review, we present the current knowledge on NGAL and its involvement in different pathologies, especially its role in renal and cardiovascular diseases.

Lipocalin 2 Reduces MET Levels by Inhibiting MEK/ERK Signaling to Inhibit Nasopharyngeal Carcinoma Cell Migration

Nasopharyngeal carcinoma (NPC) is the most common cancer that occurs in the nasopharynx, and it is difficult to detect early. The main cause of death of NPC patients is cancer metastasis. Lipocalin 2 (LCN2) has been shown to be involved in a variety of carcinogenesis processes. Here, we aimed to study the role of LCN2 in NPC cells and determine its underlying mechanism. We found that LCN2 was expressed differently in NPC cell lines, namely HONE-1, NPC-39, and NPC-BM. The down-regulation of LCN2 levels by siRNA targeting LCN2 (siLCN2) increased cell migration and invasion in HONE-1 cells, while the up-regulation of LCN2 levels by transfection with the LCN2 expression plasmid decreased cell migration and invasion in NPC-BM cells. Furthermore, LCN2 levels negatively regulated the phosphorylation of MEK/ERK pathways. The treatment of the specific MEK/ERK inhibitor, U0126, reduced cell migration in HONE-1 cells, whereas the treatment of tBHQ, an ERK activator, enhanced cell migration in NPC-BM cells. Based on the bioinformatics data, there was a moderately negative correlation between LCN2 and MET in metastatic NPC tissues (r = -0.5946, p = 0.0022). Indeed, the manipulation of LCN2 levels negatively regulated MET levels in these NPC cells. The treatment of U0126 reduced siLCN2-increased MET levels, while the treatment of tBHQ enhanced LCN2-enhanced MET levels. Interestingly, the down-regulation of MET levels by siMET further decreased siLCN2-enhanced MET levels and cell migration. Therefore, LCN2 inhibits NPC cell migration by reducing MET levels through MEK/ERK signaling.

Alterations of Ion Homeostasis in Cancer Metastasis: Implications for Treatment

We have previously reported that metastases from all malignancies are characterized by a core program of gene expression that suppresses extracellular matrix interactions, induces vascularization/tissue remodeling, activates the oxidative metabolism, and alters ion homeostasis. Among these features, the least elucidated component is ion homeostasis. Here we review the literature with the goal to infer a better mechanistic understanding of the progression-associated ionic alterations and identify the most promising drugs for treatment. Cancer metastasis is accompanied by skewing in calcium, zinc, copper, potassium, sodium and chloride homeostasis. Membrane potential changes and water uptake through Aquaporins may also play roles. Drug candidates to reverse these alterations are at various stages of testing, with some having entered clinical trials. Challenges to their utilization comprise differences among tumor types and the involvement of multiple ions in each case. Further, adverse effects may become a concern, as channel blockers, chelators, or supplemented ions will affect healthy and transformed cells alike.

The Adipokine Component in the Molecular Regulation of Cancer Cell Survival, Proliferation and Metastasis

A hormonal imbalance may disrupt the rigorously monitored cellular microenvironment by hampering the natural homeostatic mechanisms. The most common example of such hormonal glitch could be seen in obesity where the uprise in adipokine levels is in virtue of the expanding bulk of adipose tissue. Such aberrant endocrine signaling disrupts the regulation of cellular fate, rendering the cells to live in a tumor supportive microenvironment. Previously, it was believed that the adipokines support cancer proliferation and metastasis with no direct involvement in neoplastic transformations and tumorigenesis. However, the recent studies have reported discrete mechanisms that establish the direct involvement of adipokine signaling in tumorigenesis. Moreover, the individual adipokine profile of the patients has never been considered in the prognosis and staging of the disease. Hence, the present manuscript has focused on the reported extensive mechanisms that culminate the basis of poor prognosis and diminished survival rate in obese cancer patients.

ARCHITECT® urine-neutrophil gelatinase-associated lipocalin (u-NGAL) assay as new prognostic marker for clear cell Renal Cell Carcinoma (ccRCC) (preliminary results)

INTRODUCTION

Biomarkers for the diagnosis and monitoring treatment response of kidney cancer are urgently needed. Neutrophil gelatinase-associated lipocalin (NGAL) is a relevant urinary biomarker for the diagnosis of a wide variety of acute and chronic kidney diseases. Its potential utility as a prognostic marker of kidney cancer is largely unknown and, therefore, was the subject of this investigation.

MATERIALS AND METHODS

A retrospective study was done on 50 kidney tumor patients (urine samples prospectively collected before nephrectomy between 2004 and 2012, stored at Biobank Resource Center). The specificity, sensitivity and the predictive value of NGAL were determined for progression-free and disease-specific survival after nephrectomy in renal cell carcinoma (particularly, the clear cell renal cell carcinoma (ccRCC)). Urinary NGAL concentration (u-NGAL) was determined by CMIA technique (ARCHITECT® urine NGAL essay/ABBOTT^®).

RESULTS

Out of the 50 kidney tumor patients, 40 had clear cell carcinoma with a median u-NGAL excretion of 1.4 (IQR: 5.76) ng/mg urinary creatinine (Ucr). u-NGAL was correlated to tumor stage (p = 0.005), and Fuhrman grade (p = 0.0002). Multivariate Cox regression analysis showed a significant association between u-NGAL excretion and clear cell renal cell carcinoma progression free survival and disease specific survival (p = 0.002; p = 0.0001).

CONCLUSIONS

Urinary NGAL was significantly associated with the stage and the grade of kidney cancer. u-NGAL excretion could be considered as a potential biomarker to identify ccRCC patients with the more pejorative outcomes.

Lipocalin-2 expression and function in pancreatic diseases

Lipocalin-2 (LCN2) is a secreted molecule, expressed in various cell types, that is involved in the progression of numerous diseases and disorders. The biological functions and expression levels of LCN2 in diseases including pancreatic cancer, pancreatitis (acute and chronic), and diabetes mellitus, suggest the potential role of LCN2 as a biomarker and/or therapeutic target. However, findings on the role of LCN2 in pancreatic diseases have been contradictory. In pancreatic cancer and pancreatitis, LCN2 has been identified as a potential biomarker; increased expression levels in various biological specimens correlate with the presence of the disease and may be able to differentiate cancer and chronic pancreatitis from healthy subjects. LCN2 is also known to be an adipokine; it is upregulated in obesity and is a common co-factor in the development of pancreatic diseases. Emerging research suggests LCN2 is elevated in type 2 diabetes mellitus, but the exact role of LCN2 in this disease is not clear. In this review, we summarize research on LCN2 as it relates to pancreatic diseases, highlighting the discrepancies in the literature. By explaining and clarifying the role of LCN2 in these disorders, we aim to promote research in developing novel diagnostic and treatment strategies to reduce the burden of pancreatic diseases.

Clinicopathological significance of lipocalin 2 nuclear expression in invasive breast cancer

PURPOSE

The epithelial-mesenchymal transition (EMT) plays a key role in breast cancer progression and metastasis. Lipocalin 2 (LCN2) is involved in the regulation of EMT. The aim of this study was to investigate the clinicopathological significance of LCN2 expression in breast cancer.

METHODS

The expression of LCN2 protein was immunohistochemically assessed in two well-characterised annotated cohorts of breast cancer (discovery cohort, n = 612; validation cohort, n = 1363). The relationship of LCN2 expression and subcellular location with the clinicopathological factors and outcomes of patients was analysed.

RESULTS

Absent or reduced nuclear LCN2 expression was associated with features of aggressive behaviour, including high histological grade, high Nottingham Prognostic Index, high Ki67 labelling index, hormone receptor negativity and human epidermal growth factor receptor 2 positivity. The high cytoplasmic expression of LCN2 was correlated with lymph node positivity. The nuclear downregulation of LCN2 was correlated with the overexpression of EMT associated proteins (N-cadherin and Twist-related protein 2) and basal biomarkers (cytokeratin 5/6 and epidermal growth factor receptor). Unlike the cytoplasmic expression of LCN2, the loss of nuclear expression was a significant predictor of poor outcome. The combinatorial expression tumours with high cytoplasmic and low nuclear expression were associated with the worst prognosis.

CONCLUSIONS

Tumour cell expression of LCN2 plays a role in breast cancer progression with loss of its nuclear expression which is associated with aggressive features and poor outcome. Further functional analysis is warranted to confirm the relationship between the subcellular localisation LCN2 and behaviour of breast cancer.

Expression and the molecular forms of neutrophil gelatinase-associated lipocalin and matrix metalloproteinase 9 in canine mammary tumours

Neutrophil gelatinase-associated lipocalin (NGAL) is a new biomarker for renal injury. It is also involved in tumorigenesis of different human cancer types. The oncogenic role of NGAL is related to its molecular forms, and heterodimer formation with matrix metalloproteinase 9 (MMP9) promotes human breast cancer (HBC) invasion and metastasis. To date, the levels of NGAL and NGAL/MMP9 complex have not yet been explored in canine mammary tumours (CMTs). Hence, this study aimed to investigate whether NGAL and its molecular forms could be the biomarker for CMT diagnosis. To this end, expression profile of NGAL and MMP9 in mammary epithelial cells as well as in urine samples were detected. By immunohistochemistry staining, NGAL was expressed at variable levels. Unlike HBC, a significant reduction in NGAL expression was demonstrated in benign and malignant CMTs as compared with normal controls. Additionally, NGAL expression was significantly reduced in dogs with metastatic CMTs. By contrast, the mean score of MMP9 expression in ascending order was normal groups, benign, and malignant CMTs. Interestingly, analysis of the molecular form revealed the NGAL/MMP9 complex presents in most mammary tissues and urine of dogs with benign or malignant CMTs, whereas the complex was absent in samples from dogs without CMTs. In conclusion, NGAL and MMP9 are ubiquitously expressed in canine mammary epithelial cells in normal and cancerous status. However, the NGAL/MMP9 complex exclusively presents in mammary tissues and urine of dogs with tumours.

CLEC3A, MMP7, and LCN2 as novel markers for predicting recurrence in resected G1 and G2 pancreatic neuroendocrine tumors

Although the postoperative recurrence rate for pancreatic neuroendocrine tumors (PNETs) is reported to be 13.5%-30%, the paucity of valuable biomarkers to predict recurrence poses a problem for the early detection of relapse. Hence, this study aimed to identify new biomarkers to predict the recurrence of PNETs. We performed RNA sequencing (RNA-Seq) on RNA isolated from frozen primary tumors sampled from all localized G1/G2 PNETs resected curatively from 1998 to 2015 in our institution. We calculated differentially expressed genes (DEGs) in tumor with and without recurrence (≥3 years) for the propensity-matched cohort. Gene ontology analysis for the identified DEGs was also performed. Furthermore, we evaluated the expression levels of candidate genes as recurrence predictors via immunostaining. Comparison of transcriptional levels in tumors with and without recurrence identified 166 DEGs. Up- and downregulated genes with high significance in these tumors were mainly related to extracellular organization and cell adhesion, respectively. We observed the top three upregulated genes, C-type lectin domain family 3 member A (CLEC3A), matrix metalloproteinase-7 (MMP7), and lipocalin2 (LCN2) immunohistochemically and compared their levels in recurrent and nonrecurrent tumors. Significantly higher recurrence rate was shown in patients with positive expression of CLEC3A (P = 0.028), MMP7 (P = 0.003), and LCN2 (P = 0.040) than that with negative expression. We identified CLEC3A, MMP7, and LCN2 known to be associated with the phosphatidylinositol-3-kinase/Akt pathway, as potential novel markers to predict the postoperative recurrence of PNETs.

An early-screening biomarker of endometrial carcinoma: NGAL is associated with epithelio-mesenchymal transition

neutrophilgelatinase-associated lipocalin is currently one of the most interesting and enigmatic proteins involved in the development of malignancies. In this study, we found that the expression of neutrophilgelatinase-associated lipocalin was up-regulated in endometrial cancer tissues and cell lines, significantly increased in early-grade ones, suggesting it may serve as a biomarker for early-stage screening for endometrial carcinoma. Moreover, neutrophilgelatinase-associated lipocalin was up-regulated in Ishikawa cells under going epithelio-mesenchymal transition induced by epidermal growth factor (5 ng/ml). Up-regulation of neutrophilgelatinase-associated lipocalin may correlate with the down-regulation of E-cadherin expression, up-regulation of Vimentin expression, enhanced cell migration, invasion and proliferation, which are the typical hallmarks of epithelio-mesenchymal transition processes. neutrophilgelatinase-associated lipocalin may play a dual role during tumorigenetic and developmental processes of endometrial carcinoma. These results suggested neutrophilgelatinase-associated lipocalin to be a potential molecular target in the early diagnosis and treatment of endometrial carcinoma. Further studies are warranted to clarify the molecular mechanisms behind the expression and function of neutrophilgelatinase-associated lipocalin and epithelio-mesenchymal transition.

Overexpression of lipocalin 2 in human cervical cancer enhances tumor invasion

Cervical carcinoma is the third-most common cause of cancer-related deaths in women worldwide. However, the molecular mechanisms underlying the metastasis of cervical cancer are still unclear. Oligonucleotide microarrays coupled with bioinformatics analysis show that cytoskeletal remodeling and epithelial-to- mesenchymal transition (EMT) are significant pathways in clinical specimens of cervical cancer. In accord with clinical observations demonstrating ectopic expression of lipocalin 2 (LCN2), an oncogenic protein associated with EMT, in malignant tumors, was significantly upregulated in cervical cancer and correlated with lymph node metastasis. Overexpression of LCN2 enhanced tumor cell migration and invasion both in vitro and in vivo. Conversely, knockdown or neutralization of LCN2 reduced tumor cell migration and invasion. LCN2-induced migration was stimulated by activation of the EMT-associated proteins, Snail, Twist, N-cadherin, fibronectin, and MMP-9. Our findings collectively support a potential role of LCN2 in cancer cell invasion through the EMT pathway and suggest that LCN2 could be effectively utilized as a lymph node metastasis marker in cervical cancer.

Levels of neutrophil gelatinase-assosciated lipocalin in patients with head and neck squamous cell carcinoma in Indian population from Haryana state

AIM

To study the levels of neutrophil gelatinase associated lipocalin (NGAL) in head and neck squamous cell carcinoma (HNSCC).

METHODS

This was a non randomized case control study conducted at Department of Biochemistry, in collaboration with Regional Cancer Center over a period of one year. The study population included 50 adult newly diagnosed HNSCC patients reporting in outpatient department at Regional Cancer Center and compared with 50 healthy controls. NGAL was estimated by ELISA technique. Student t test and χ² test were applied for comparison of means of study groups. Correlations between groups were analyzed using Pearson correlation coefficient (r) formula.

RESULTS

Patients with HNSCC exhibited significantly increased levels of NGAL (P < 0.05) as compared to healthy controls (978.88 ± 261.39 ng/mL vs 34.83 ± 7.59 ng/mL). Out of 50, 26 patients (52%) were in stage IV, 21 (42%) in stage III, 1 (2%) patient in stage II and 2 (4%) patients were in stage I. Metastasis was absent in 98% patients and mean NGAL levels were highest in these patients but P value was not significant. Mean NGAL levels were highest in stage IV [1041.54 ± 222.15 ng/mL (stage IV) vs 1040 ± 0.00 ng/mL (stage I); 900 ± 0.00 ng/mL (stage II) and 1031.90 ± 202.55 ng/mL (stage III)] and χ² test was highly significant (P < 0.001). Thirty-six patients (72%) were having moderately differentiated HNSCC and mean NGAL levels were maximum in patients with well differentiated HNSCC (1164 ± 315.64 ng/mL vs 1013.33 ± 161.19 ng/mL in moderately differentiated and 890 ± 11.55 ng/mL in poorly differentiated) and the results were also highly significant (P < 0.001, χ² test).

CONCLUSION

The present work demonstrates a potential role of NGAL as cancer biomarker and its use in monitoring the HNSCC progression.

Lipocalin2 suppresses metastasis of colorectal cancer by attenuating NF-κB-dependent activation of snail and epithelial mesenchymal transition

Background

Lipocalin2 (LCN2) is a secretory protein that is aberrantly expressed in several types of cancer and has been involved in metastatic progression. However, neither mechanisms nor the role that LCN2 plays in the metastasis of colorectal cancer are clear.

Methods

LCN2 expression in colorectal cancer was detected by immunohistochemistry in 400 tissue specimens and Kaplan-Meier survival analysis was performed. In vitro, real-time PCR, western blot, colony formation assay, immunofluorescence assay, wound healing assay, migration and invasion experiment were performed to investigate the effects of LCN2 in epithelial mesenchymal transition (EMT), migration and invasion, respectively. In vivo mouse xenograft and metastasis models were utilized to determine tumorigenicity and metastasis ability, and immunohistochemistry, real-time PCR, western blot were used to evaluate the related protein expression. Luciferase reporter assay was used to explore the role of LCN2 on NF-ĸB promoter.

Results

LCN2 was highly expressed in 66.5% of the specimens, and significantly correlated with positive E-cadherin in the membrane and negative nuclear β-catenin. Higher expression of LCN2 together with negative NF-κB expression was negatively related to nuclear accumulation of snail and predicted favorable prognosis. LCN2 blocked cell proliferation, migration and invasion in vitro and in vivo, and inhibited translocation of NF-κB into nucleus. NF-κB could reverse the effect of LCN2 on EMT and promote snail expression. Rescued snail expression had similar effect without influencing NF-κB activity.

Conclusion

LCN2 may be an important negative regulator in EMT, invasion and metastasis of CRC via acting as upstream of NF-κB/snail signaling pathway. Thereby combinative manipulation of LCN2 and NF-κB/snail pathway may represent a novel and promising therapeutic approach for the patients with CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0564-9) contains supplementary material, which is available to authorized users.

Expression and Function of Interleukin-1β-Induced Neutrophil Gelatinase-Associated Lipocalin in Renal Tubular Cells

Acute kidney injury (AKI) is characterized by a sudden loss of renal function. Early recognition of AKI, especially in critically ill patients, is essential for adequate therapy. Currently, neutrophil gelatinase-associated lipocalin (NGAL) is considered to be an effective biomarker of AKI; however, the regulation of its expression and function in renal tubular cells remains unclear. In this study, we investigated the regulation of the expression and function of NGAL in IL-1β-treated Madin–Darby canine kidney (MDCK) cells as a model of renal tubular cells. IL-1β induced a disturbance in the localization of E-cadherin and zonaoccludin-1 (ZO-1). The transepithelial electrical resistance (TER) also decreased 5 days after IL-1β treatment. IL-1β induced NGAL mRNA expression and protein secretion in a time- and dose-dependent manner, which occurred faster than the decrease in TER. In the presence of ERK1/2 and p38 inhibitors, IL-1β-induced NGAL mRNA expression and protein secretion were significantly attenuated. In the presence of recombinant NGAL, IL-1β-induced disturbance in the localization of E-cadherin and ZO-1 was attenuated, and the decrease in TER was partially maintained. These results suggest that NGAL can be used as a biomarker for AKI and that it functions as a protector from AKI.

iTRAQ-Based Proteomics Screen identifies LIPOCALIN-2 (LCN-2) as a potential biomarker for colonic lateral-spreading tumors

The improvement and implementation of a colonoscopy technique has led to increased detection of laterally spreading tumors (LSTs), which are presumed to constitute an aggressive type of colonic neoplasm. Early diagnosis and treatment of LSTs is clinically challenging. To overcome this problem, we employed iTRAQ to identify LST-specific protein biomarkers potentially involved in LST progression. In this study, we identified 2,001 differentially expressed proteins in LSTs using iTRAQ-based proteomics technology. Lipocalin-2 (LCN-2) was the most up-regulated protein. LSTs expression levels of LCN-2 and matrix metallopeptidase-9 (MMP-9) showed positive correlation with worse pathological grading, and up-regulation of these proteins in LSTs was also reflected in serum. Furthermore, LCN-2 protein overexpression was positively correlated with MMP-9 protein up-regulation in the tumor tissue and serum of LST patients (former r_s = 0.631, P = 0.000; latter r_s = 0.815, P = 0.000). Our results suggest that LCN-2 constitutes a potential biomarker for LST disease progression and might be a novel therapeutic target in LSTs.

Lipocalin 2 prevents oral cancer metastasis through carbonic anhydrase IX inhibition and is associated with favourable prognosis

Lipocalin 2 (LCN2), a secreted glycoprotein, is up- or downregulated in different human cancers. At present, the functional role of LCN2 in the progression of oral squamous cell carcinoma (OSCC), which accounts for most head and neck cancers, remains poorly understood, particularly with respect to its involvement in invasion and metastasis. In this study, we observed that LCN2 expression decreased in patients with OSCC and lymph node metastasis compared with that in patients without metastasis. A higher LCN2 expression correlated with the survival of patients with OSCC. Furthermore, LCN2 overexpression in OSCC cells reduced in vitro migration and invasion and in vivo metastasis, whereas its silencing induced an increase in cell motility. Mechanistically, LCN2 inhibited the cell motility of OSCC cells through hypoxia-inducible factor (HIF)-1α-dependent transcriptional inhibition of the carbonic anhydrase IX (CAIX). CAIX overexpression relieved the migration inhibition imposed by LCN2 overexpression in OSCC cells. Moreover, a microRNA (miR) analysis revealed that LCN2 can suppress CAIX expression and cell migration through miR-4505 induction. Examination of tumour tissues from patients with OSCC and OSCC-transplanted mice revealed an inverse correlation between LCN2 and CAIX expression. Furthermore, patients with LCN2(strong)/CAIX(weak) revealed the lowest frequency of lymph node metastasis and the longest survival. Our findings suggest that LCN2 suppresses tumour metastasis by targeting the transcriptional and post-transcriptional regulation of CAIX in OSCC cells. LCN2 overexpression may be a novel OSCC treatment strategy and a useful biomarker for predicting OSCC progression.

Thyroid hormone-mediated regulation of lipocalin 2 through the Met/FAK pathway in liver cancer

The thyroid hormone, 3,3′,5-triiodo-L-thyronine (T₃), regulates cell growth, development and differentiation via interactions with thyroid hormone receptors (TR), but the mechanisms underlying T₃-mediated modulation of cancer progression are currently unclear. Lipocalin 2 (LCN2), a tumor-associated protein, is overexpressed in a variety of cancer types. Oligonucleotide microarray, coupled with proteomic analysis, has revealed that LCN2 is positively regulated by T₃/TR. However, the physiological role and pathway of T₃-mediated regulation of LCN2 in hepatocellular carcinogenesis remain to be characterized. Upregulation of LCN2 after T₃ stimulation was observed in a time- and dose-dependent manner. Additionally, TRE on the LCN2 promoter was identified at positions −1444/−1427. Overexpression of LCN2 enhanced tumor cell migration and invasion, and conversely, its knockdown suppressed migration and invasion, both in vitro and in vivo. LCN2-induced migration occurred through activation of the Met/FAK cascade. LCN2 was overexpressed in clinical hepatocellular carcinoma (HCC) patients, compared with normal subjects, and positively correlated with TRα levels. Both TRα and LCN2 showed similar expression patterns in relation to survival rate, tumor grade, tumor stage and vascular invasion. Our findings collectively support a potential role of T₃/TR in cancer progression through regulation of LCN2 via the Met/FAK cascade. LCN2 may thus be effectively utilized as a novel marker and therapeutic target in HCC.

Lipocalin 2 promotes the migration and invasion of esophageal squamous cell carcinoma cells through a novel positive feedback loop

Lipocalin 2 (LCN2) is a poor prognostic factor in esophageal squamous cell carcinoma (ESCC), however its functional roles and molecular mechanisms of action remain to be clarified. Here, we described the functions and signaling pathways for LCN2 in ESCC. Overexpression of LCN2 in ESCC cells accelerated cell migration and invasion in vitro, and promoted lung metastasis in vivo. Blocking LCN2 expression inhibited its pro-oncogenic effect. Either overexpression of LCN2 or treatment with recombinant human LCN2 protein enhanced the activation of MEK/ERK pathway, which in turn increases endogenous LCN2 to increase MMP-9 activity. The decreased p-cofilin and increased p-ERM induced by pERK1/2 cause the cytoskeleton F-actin rearrangement and alter the behavior of ESCC cells mediated by LCN2. As a consequence, activation of MMP-9 and the rearrangement of F-actin throw light on the mechanisms for LCN2 in ESCC. These results imply that LCN2 promotes the migration and invasion of ESCC cells through a novel positive feedback loop.

HGF mediated upregulation of lipocalin 2 regulates MMP9 through nuclear factor-κB activation

Lipocalin 2 (LCN2) is a member of lipocalin family that binds and transports a small lipophilic ligand, sharing a highly conserved tertiary structure and can be found as a monomer, homodimer, heterodimer with matrix metalloproteinase 9 (MMP9). The high molecule LCN2/MMP9 complex was found in several cancer types. Yet, the mechanisms of regulation between LCN2 with MMP9 in tumorigenesis is unclear. The aims of the present study were to identify the function of LCN2 associated with MMP9 in gastric cancer growth and metastasis. First, we confirmed that the expression level of LCN2 and MMP9 was upregulated by hepatocyte growth factor (HGF). To identify the association pathway of HGF-induced LCN2, the cells were treated with PI3-kinase inhibitor (LY294002), or MEK inhibitor (PD098059), or p38 inhibitor (SB203580) and then analyzed using western blotting. The HGF-mediated LCN2 protein level was decreased with LY294002. Also, the HGF-mediated MMP9 was decreased with LY294002. The role for LCN2 with HGF mediated MMP9 was determined by knockdown of LCN2. LCN2-sh RNA cells showed a decreased level of HGF-mediated MMP9. The HGF-mediated LCN2 protein level was decreased with treatment of the NFκB inhibitor. We confirmed the role of HGF-mediated LCN2. HGF-mediated cell proliferation and in vitro invasion was decreased in LCN2 knockdown cell. In conclusion, the present study showed that LCN2 upregulated MMP9 through PI3K/AKT/NFκB pathway in gastric cancer. LCN2 has a role in cell proliferation and cell invasion in gastric cancer, which may be a possible target for developing gastric cancer therapy.

Low Serum Neutrophil Gelatinase-associated Lipocalin Level as a Marker of Malnutrition in Maintenance Hemodialysis Patients

Background

Neutrophil gelatinase-associated lipocalin (NGAL or LCN2) is an iron-transporting factor which possesses various activities such as amelioration of kidney injury and host defense against pathogens. Its circulating concentrations are elevated in acute and chronic kidney diseases and show a positive correlation with poor renal outcome and mortality, but its clinical significance in maintenance hemodialysis (HD) patients remains elusive.

Methods

Serum NGAL levels were determined by enzyme-linked immunosorbent assay in out-patient, Japanese HD subjects. Their correlation to laboratory findings and morbidity (as development of severe infection or serum albumin reduction) was investigated using linear regression analysis and χ² test.

Results

Pre-dialysis serum NGAL levels in HD patients were elevated by 13-fold compared to healthy subjects (n=8, P<0.001). In a cross-sectional study of 139 cases, serum NGAL concentrations were determined independently by % creatinine generation rate (an indicator of muscle mass, standardized coefficient β=0.40, P<0.001), peripheral blood neutrophil count (β=0.38, P<0.001) and anion gap (which likely reflects dietary protein intake, β=0.16, P<0.05). Iron administration to anemic HD patients caused marked elevation of peripheral blood hemoglobin, serum ferritin and iron-regulatory hormone hepcidin-25 levels, but NGAL levels were not affected. In a prospective study of 87 cases, increase in serum albumin levels a year later was positively associated to baseline NGAL levels by univariate analysis (r=0.36, P<0.01). Furthermore, within a year, patients with the lowest NGAL tertile showed significantly increased risk for marked decline in serum albumin levels (≥0.4 g/dl; odds ratio 5.5, 95% confidence interval 1.5–20.3, P<0.05) and tendency of increased occurrence of severe infection requiring admission (odds ratio 3.1, not significant) compared to the middle and highest tertiles.

Conclusion

Low serum NGAL levels appear to be associated with current malnutrition and also its progressive worsening in maintenance HD patients.

Over-expression of lipocalin 2 promotes cell migration and invasion through activating ERK signaling to increase SLUG expression in prostate cancer

BACKGROUND

Metastasis is the primary cause of prostate cancer (PCa) lethality and poses a huge clinical obstacle. Lipocalin 2 (LCN2), a member of the lipocalin family, is aberrantly expressed in some human cancers and has been implicated in the progression of some tumors. However, the role of LCN2 in the metastatic capacity of prostate cancer (PCa) is poorly understood.

METHODS

LCN2 expression was examined by RT-qPCR and/or immunoblotting in human prostate tissue specimens and prostate cancer cell lines LNCaP, C4-2, 22RV1, PC3, DU-145, and PC3MM2. LCN2 protein level in human serum samples was determined by ELISA. Lentiviruses-mediated over-expression of LCN2 and knockdown of LCN2 was conducted to evaluate the role of LCN2 in cell migratory and invasive capacities of prostate cancer cells. Cell migration and invasion was examined by transwell chamber assay. Knockdown of SLUG by lentivirus was performed to investigate its role in LCN2-promoted cell migration and invasion in vitro (22RV1 cell line) and metastasis in vivo (tail vein metastasis assay in nude mice). Role of ERK signaling in LCN2-mediated up-regulation of SLUG was assayed by using ERK inhibitor U0126.

RESULTS

We confirmed that LCN2 levels were correlated positively with invasive prostate cancer in human tissue and serum samples, and were also consistently associated with the invasive capacity of prostate cancer cell lines. The over-expression of LCN2 in 22RV1 cells (not highly invasive) promoted the epithelial-mesenchymal transition (EMT), increasing cell motility and invasiveness, while the knockdown of LCN2 in PC3 cells (highly invasive) inhibited EMT, decreasing cell motility and invasiveness. Among the multiple EMT transcription factors, LCN2 specifically induces the expression of SLUG, which was shown here to be required for the LCN2-induced increase in the invasive capacity of prostate cancer cells both in vitro and in vivo. Mechanistically, LCN2 promoted SLUG expression via activating ERK signaling pathway.

CONCLUSION

LCN2 plays an important role in promoting cell migration and invasion of prostate cancer by inducing EMT through the ERK/SLUG axis. Therefore, targeted inhibition of LCN2 may represent a therapeutic strategy to prevent the metastasis of prostate cancer.

A possible contribution of lipocalin-2 to the development of dermal fibrosis, pulmonary vascular involvement and renal dysfunction in systemic sclerosis

BACKGROUND

Lipocalin-2 is an adipocytokine implicated in apoptosis, innate immunity, angiogenesis, and the development of chronic kidney disease.

OBJECTIVES

To investigate the role of lipocalin-2 in systemic sclerosis (SSc).

MATERIALS AND METHODS

Serum lipocalin-2 levels were determined by enzyme-linked immunosorbent assay in 50 patients with SSc and 19 healthy subjects. Lipocalin-2 expression was evaluated in the skin of patients with SSc and bleomycin (BLM)-treated mice and in Fli1-deficient endothelial cells by reverse transcriptase-real time polymerase chain reaction, immunoblotting and/or immunohistochemistry.

RESULTS

Although serum lipocalin-2 levels were comparable between patients with SSc and healthy controls, the prevalence of scleroderma renal crisis was significantly higher in patients with SSc with elevated serum lipocalin-2 levels than in those with normal levels. Furthermore, serum lipocalin-2 levels inversely correlated with estimated glomerular filtration rate in patients with SSc with renal dysfunction. Among patients with SSc with normal renal function, serum lipocalin-2 levels positively correlated with skin score in patients with diffuse cutaneous SSc with disease duration of < 3 years and inversely correlated with estimated right ventricular systolic pressure in total patients with SSc. Importantly, in SSc lesional skin, lipocalin-2 expression was increased in dermal fibroblasts and endothelial cells. In BLM-treated mice, lipocalin-2 was highly expressed in dermal fibroblasts, but not in endothelial cells. On the other hand, the deficiency of transcription factor Fli1, which is implicated in SSc vasculopathy, induced lipocalin-2 expression in cultivated endothelial cells.

CONCLUSIONS

Lipocalin-2 may be involved in renal dysfunction and dermal fibrosis of SSc. Dysregulated matrix metalloproteinase-9/lipocalin-2-dependent angiogenesis due to Fli1 deficiency may contribute to the development of pulmonary arterial hypertension associated with SSc.

Expression and localisation of brain-type organic cation transporter (BOCT/24p3R/LCN2R) in the normal rat hippocampus and after kainate-induced excitotoxicity

The iron siderophore binding protein lipocalin 2 (LCN2, also known as 24p3, NGAL and siderocalin) may be involved in iron homeostasis, but to date, little is known about expression of its putative receptor, brain-type organic cation transporter (BOCT, also known as BOCT1, 24p3R, NGALR and LCN2R), in the brain during neurodegeneration. The present study was carried out to elucidate the expression of LCN2 and BOCT in hippocampus after excitotoxicity induced by the glutamate analog, kainate (KA) and a possible role of LCN2 in neuronal injury. As reported previously, a rapid and sustained induction in expression of LCN2 was found in the hippocampus after intracerebroventicular injection of KA. BOCT was expressed in neurons of the saline-injected control hippocampus, and immunolabel for BOCT protein was preserved in pyramidal neurons of CA1 at 1 day post-KA injection, likely due to the delayed onset of neurodegeneration after KA injection. At 3 days and 2 weeks after KA injections, loss of immunolabel was observed due to degenerated neurons, although remaining neurons continued to express BOCT, and induction of BOCT was found in OX-42 positive microglia. This resulted in an overall decrease in BOCT mRNA and protein expression after KA treatment. Increased expression of the pro-apoptotic marker, Bim, was found in both neurons and microglia after KA injection, but TUNEL staining indicating apoptosis was found primarily in Bim-expressing neurons, but not microglia. Interaction between LCN2 and BOCT was found by DuoLink assay in cultured hippocampal neurons. Apo-LCN2 without iron caused no significant differences in neuronal Bim expression or cell survival, whereas holo-LCN2 consisting of LCN2:iron:enterochelin complex increased Bim mRNA expression and decreased neuronal survival. Together, results suggest that LCN2 and BOCT may have a role in neuronal injury.

Regulation of cellular iron metabolism and its implications in lung cancer progression

Iron is essential for life and is involved in numerous metabolic processes including cell growth and proliferation. However, excess iron in the body raises the risk of developing cancer due to its capacity to engage in redox cycling and free radical production. Therefore, iron can contribute to both carcinogenesis and tumor growth. Both epidemiologic and laboratory studies have demonstrated that the effects of iron overload are associated with the tumorigenesis of lung cancer and growth of lung cancer cells. In particular, the discovery of hepcidin and several iron transporters in the past decade may warrant reconsideration of the role of iron in carcinogenesis and tumor cell proliferation in lung cancer. Pathways of iron uptake, storage, efflux, and regulation are all disturbed in cancer, suggesting that reprogramming of iron metabolism is a critical aspect of tumor cell survival. Although these pathways in lung cancer have been identified and extensively studied, many issues on the metabolic processes of iron in lung cancer cells have not been addressed. Targeting metabolic pathways of iron may provide new tools for lung cancer prognosis and therapy.

Lipocalin-2 is associated with a good prognosis and reversing epithelial-to-mesenchymal transition in pancreatic cancer

BACKGROUND

Lipocalin-2 is a multifaceted modulator in cancer progression. Its clinical significance is not clear in pancreatic cancer. The purpose of this study was to investigate whether lipocalin-2 is associated with good prognosis by reversing epithelial-to-mesenchymal transition (EMT) in pancreatic cancer.

METHODS

Lipocalin-2, E-cadherin, or vimentin expression was detected in 60 pancreatic adenocarcinoma specimens. Correlations between lipocalin-2 expression and EMT, the clinicopathologic characteristics, and prognosis were investigated. Whether pancreatic cancer cells' migration and invasion (some characteristics of EMT) were affected by lipocalin-2 was also explored.

RESULTS

High lipocalin-2 expression was significantly associated with a good prognosis in pancreatic cancer (p < 0.05). Overexpression of lipocalin-2 correlated with a lower extent of EMT (p < 0.05), increased E-cadherin expression (p < 0.05), decreased vimentin expression (p < 0.05), and reduced cancer cell migration and invasion in pancreatic cancer.

CONCLUSIONS

Lipocalin-2 may be considered an epithelial inducer, which may reverse EMT and predict a good prognosis in pancreatic cancer.

Novel hepatocellular carcinoma molecules with prognostic and therapeutic potentials

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, is the sixth most common cancer worldwide and the third leading cause of cancer-related death. The difficulty to diagnose early cancer stages, the aggressive behaviors of HCC, and the poor effectiveness of therapeutic treatments, represent the reasons for the quite similar deaths per year and incidence number. Considering the fact that the diagnosis of HCC typically occurs in the advanced stages of the disease when the therapeutic options have only modest efficacy, the possibility to identify early diagnostic markers could be of significant benefit. So far, a large number of biomarkers have been associated to HCC progression and aggressiveness, but many of them turned out not to be of practical utility. This is the reason why active investigations are ongoing in this field. Given the huge amount of published works aimed at the identification of HCC biomarkers, in this review we mainly focused on the data published in the last year, with particular attention to the role of (1) molecular and biochemical cellular markers; (2) micro-interfering RNAs; (3) epigenetic variations; and (4) tumor stroma. It is worth mentioning that a significant number of the HCC markers described in the present review may be utilized also as targets for novel therapeutic approaches, indicating the tight relation between diagnosis and therapy. In conclusion, we believe that integrated researches among the different lines of investigation indicated above should represent the winning strategies to identify effective HCC markers and therapeutic targets.

Lipocalin-2 negatively modulates the epithelial-to-mesenchymal transition in hepatocellular carcinoma through the epidermal growth factor (TGF-beta1)/Lcn2/Twist1 pathway

Lipocalin-2 (Lcn2) is preferentially expressed in hepatocellular carcinoma (HCC). However, the functional role of Lcn2 in HCC progression is still poorly understood, particularly with respect to its involvement in invasion and metastasis. The purpose of this study was to investigate whether Lcn2 is associated with the epithelial-mesenchymal transition (EMT) in HCC and to elucidate the underlying signaling pathway(s). Lcn2 was preferentially expressed in well-differentiated HCC versus liver cirrhosis tissues, and its expression was positively correlated with the stage of HCC. The characteristics of EMT were reversed by adenoviral transduction of Lcn2 into SH-J1 cells, including the down-regulation of N-cadherin, vimentin, alpha-smooth muscle actin, and fibronectin, and the concomitant up-regulation of CK8, CK18, and desmoplakin I/II. Knockdown of Lcn2 by short hairpin RNA (shRNA) in HKK-2 cells expressing high levels of Lcn2 was associated with EMT. Epidermal growth factor (EGF) or transforming growth factor beta1 (TGF-β1) treatment resulted in down-regulation of Lcn2, accompanied by an increase in Twist1 expression and EMT in HCC cells. Stable Lcn2 expression in SH-J1 cells reduced Twist1 expression, inhibited cell proliferation and invasion in vitro, and suppressed tumor growth and metastasis in a mouse model. Furthermore, EGF or TGF-β1 treatment barely changed EMT marker expression in SH-J1 cells ectopically expressing Lcn2. Ectopic expression of Twist1 induced EMT marker expression even in cells expressing Lcn2, indicating that Lcn2 functions downstream of growth factors and upstream of Twist1.

CONCLUSION

Together, our findings indicate that Lcn2 can negatively modulate the EMT in HCC cells through an EGF (or TGF-β1)/Lcn2/Twist1 pathway. Thus, Lcn2 may be a candidate metastasis suppressor and a potential therapeutic target in HCC.

Knockdown of lipocalin-2 suppresses the growth and invasion of prostate cancer cells

BACKGROUND

Lipocalin-2 (LCN2) is a member of the lipocalin superfamily, and it has an important role in the regulation of cellular oncogenesis and apoptosis. However, the role for LCN2 in prostate cancer remains unclear.

METHOD

LCN2 expression has been determined by Western blotting, qRT-PCR, and immunohistochemistry in the human prostate cell lines PC3, DU145, LNCaP, and 22Rv, and in human prostate tissue array. In this study, we identified shRNA-LCN2 to determine the role of LCN2 in prostate-cancer cell proliferation, migration, and invasion. Cell proliferative ability was measured by MTT, colony-formation, and cell-cycle analysis. The role of LCN2 in prostate-cancer cell migration and invasion was analyzed by cell-migration assay and Matrigel invasion assay. The effect of LCN2 knockdown on prostate tumor growth was assessed in a subcutaneous xenograft model.

RESULTS

LCN2 protein and mRNA expression are higher in PC3 and DU145 cells than in LNCaP and 22Rv cells, and prostate cancer tissue correlated significantly with tumor differentiation (P < 0.017) and Gleason's grade (P < 0.02). LCN2 knockdown in PC3 and DU145 cells decreased cell proliferation, colony formation, cell cycle arrest, migration, and invasion. Conversely, LCN2 overexpression in 22Rv cells produced the opposite effect. Subcutaneous xenografts in mice models showed decreased tumor growth in the LCN2-knockdown mice.

CONCLUSIONS

Our results suggest that LCN2 might play an important role in regulation of proliferation and invasion of human prostate cancer, and that it can be a valuable marker of prostate cancer progression.

Bacteroides fragilis enterotoxin upregulates lipocalin-2 expression in intestinal epithelial cells

Enterotoxigenic Bacteroides fragilis (ETBF) produces an ≈ 20 kDa B. fragilis enterotoxin (BFT), which plays an essential role in mucosal inflammation. Lipocalin (Lcn)-2, a siderophore-binding antimicrobial protein, is critical for control of bacterial infection; however, expression of Lcn-2 in BFT-exposed intestinal epithelial cells has not been elucidated. In the present study, stimulation of human intestinal epithelial cells with BFT resulted in the upregulation of Lcn-2 expression that was a relatively late response of intestinal epithelial cells compared with human β-defensin (hBD)-2 expression. The upregulation of Lcn-2 was dependent on AP-1 but not on NF-κB signaling. Lcn-2 induction via AP-1 was regulated by mitogen-activated protein kinases (MAPKs) including ERK and p38. Lcn-2 was secreted from the apical and basolateral surfaces in BFT-treated cells. These results suggest that a signaling pathway involving MAPKs and AP-1 is required for Lcn-2 induction in intestinal epithelial cells exposed to BFT, after which the secreted Lcn-2 may facilitate antimicrobial activity within ETBF-infected mucosa.

One potential oncolytic adenovirus expressing Lipocalin-2 for colorectal cancer therapy

Colorectal cancer is an aggressive malignancy with a high mortality rate; however, effective therapies are currently lacking. Cancer-targeting gene-virotherapy (CTGVT) has been proposed to be a promising strategy for cancer therapy. The purpose of this study was to investigate the antitumor activity of the oncolytic adenovirus harboring Lipocalin-2 (ZD55-Lipocalin-2, an example of CTGVT) in colorectal cancer. ZD55-Lipocalin-2 was generated by deleting E1B55-KD and inserting the Lipocalin-2 gene. Its cytopathic effects and cell growth inhibition were detected in vitro, and antitumor effects were examined in a nude mouse model of human colorectal cancer xenografts. Results showed that ZD55-Lipocalin-2 significantly inhibited the colorectal cancer growth by selective cytolysis, inducing apoptosis and decreasing the microvessel density in tumors. The anticancer potential of ZD55-Lipocalin-2 showed stronger than that of the isolated Lipocalin-2 gene therapy or isolated ZD55 oncolytic adenovirus therapy. ZD55-Lipocalin-2 may serve as a potential anticancer agent for colorectal cancer treatment.

The neglected significance of "antioxidative stress"

Oxidative stress arises when there is a marked imbalance between the production and removal of reactive oxygen species (ROS) in favor of the prooxidant balance, leading to potential oxidative damage. ROSs were considered traditionally to be only a toxic byproduct of aerobic metabolism. However, recently, it has become apparent that ROS might control many different physiological processes such as induction of stress response, pathogen defense, and systemic signaling. Thus, the imbalance of the increased antioxidant potential, the so-called antioxidative stress, should be as dangerous as well. Here, we synthesize increasing evidence on “antioxidative stress-induced” beneficial versus harmful roles on health, disease, and aging processes. Oxidative stress is not necessarily an un-wanted situation, since its consequences may be beneficial for many physiological reactions in cells. On the other hand, there are potentially harmful effects of “antioxidative stress,” especially in the cases of overconsumption of synthetic antioxidants. Antioxidants can neutralize ROS and decrease oxidative stress; however, this is not always beneficial in regard to disease formation or progression (of, e.g., cancer) or for delaying aging.

[NGAL, biomarker of acute kidney injury in 2012]

Neutrophil Gelatinase Associated Lipocalin (NGAL) is one of the most promising biomarkers for acute kidney injury (AKI). Although urinary NGAL is intuitively more appropriate to apprehend renal injury, clinical data have accumulated on the potential interest of NGAL measured indifferently in serum or urine. Diagnostic performance of NGAL greatly varies across studies according to different factors such as the type of patients (pediatric versus adult) and the clinical situations (surgery versus intensive care). Overall, NGAL is presented as a useful tool to diagnose and predict AKI outcome but several issues (the absence of a unique pertinent threshold value, the incomplete analytical validation of its measurement and, its apparent limited clinical added value as compared to traditional AKI markers) remain to be addressed in order to definitely recommend its use in clinical practice.

Treatment of pancreatic cancer using an oncolytic virus harboring the lipocalin-2 gene

BACKGROUND

The 5-year survival rate for patients with pancreatic cancer is <5%, and it is always resistant to the current chemoradiotherapy. Therefore, new, effective agents for the treatment of pancreatic cancer are urgently needed. The promising strategy of cancer-targeting gene virotherapy (CTGVT) has demonstrated great anticancer potential. The objective of the current study was to determine whether 1 CTGVT approach, oncolytic virus (OV)-harboring lipocalin-2, is capable of treating pancreatic cancer.

METHODS

Tissue microarrays were constructed to detect the expression of lipocalin-2 in 60 specimens of pancreatic adenocarcinoma. The clinical significance of lipocalin-2 was investigated in an analysis of correlations between lipocalin-2 expression and matched clinical characteristics. A lipocalin-2-expressing OV, ZD55-lipocalin-2, was constructed by deleting the adenoviral protein E1B55kD. The antitumor efficacy and mechanisms of the OV were investigated in pancreatic cancer cells with v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations in vitro and in vivo.

RESULTS

Lipocalin-2 expression was correlated with a good prognosis in patients with pancreatic adenocarcinoma. ZD55-lipocalin-2 dramatically inhibited the growth of pancreatic cancer in vitro and in vivo by inducing cytolysis and caspase-dependent apoptosis.

CONCLUSIONS

Higher lipocalin-2 expression predicted a better prognosis in patients with pancreatic cancer. The results indicated that ZD55-lipocalin-2, which specifically expressed higher levels of lipocalin-2 in tumor cells, may serve as a potent anticancer drug for pancreatic cancer therapy, especially for patients who have pancreatic adenocarcinoma with KRAS mutations.

Inhibition of lung cancer growth: ATP citrate lyase knockdown and statin treatment leads to dual blockade of mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/AKT pathways

ATP citrate lyase (ACL) catalyzes the conversion of cytosolic citrate to acetyl-CoA and oxaloacetate. A definitive role for ACL in tumorigenesis has emerged from ACL RNAi and chemical inhibitor studies, showing that ACL inhibition limits tumor cell proliferation and survival and induces differentiation in vitro. In vivo, it reduces tumor growth leading to a cytostatic effect and induces differentiation. However, the underlying molecular mechanisms are poorly understood and agents that could enhance the efficacy of ACL inhibition have not been identified. Our studies focus on non-small cell lung cancer (NSCLC) lines, which show phosphatidylinositol 3-kinase (PI3K)/AKT activation secondary to a mutation in the K-Ras gene or the EGFR gene. Here we show that ACL knockdown promotes apoptosis and differentiation, leading to the inhibition of tumor growth in vivo. Moreover, in contrast to most studies, which elucidate how activation/suppression of signaling pathways can modify metabolism, we show that inhibition of a metabolic pathway "reverse signals" and attenuates PI3K/AKT signaling. Additionally, we find that statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, which act downstream of ACL in the cholesterol synthesis pathway, dramatically enhance the anti-tumor effects of ACL inhibition, even regressing established tumors. With statin treatment, both PI3K/AKT and the MAPK pathways are affected. Moreover, this combined treatment is able to reduce the growth of EGF receptor resistant tumor cell types. Given the essential role of lipid synthesis in numerous cancers, this work may impact therapy in a broad range of tumors.

Cell-to-cell signaling influences the fate of prostate cancer stem cells and their potential to generate more aggressive tumors

An increasing number of malignancies has been shown to be initiated and propelled by small subpopulations of cancer stem cells (CSC). However, whether tumor aggressiveness is driven by CSC and by what extent this property may be relevant within the tumor mass is still unsettled. To address this issue, we isolated a rare tumor cell population on the basis of its CD44⁺CD24⁻ phenotype from the human androgen-independent prostate carcinoma cell line DU145 and established its CSC properties. The behavior of selected CSC was investigated with respect to the bulk DU145 cells. The injection of CSC in nude mice generated highly vascularized tumors infiltrating the adjacent tissues, showing high density of neuroendocrine cells and expressing low levels of E-cadherin and β-catenin as well as high levels of vimentin. On the contrary, when a comparable number of unsorted DU145 cells were injected the resulting tumors were less aggressive. To investigate the different features of tumors in vivo, the influence of differentiated tumor cells on CSC was examined in vitro by growing CSC in the absence or presence of conditioned medium from DU145 cells. CSC grown in permissive conditions differentiated into cell populations with features similar to those of cells held in aggressive tumors generated from CSC injection. Differently, conditioned medium induced CSC to differentiate into a cell phenotype comparable to cells of scarcely aggressive tumors originated from bulk DU145 cell injection. These findings show for the first time that CSC are able to generate differentiated cells expressing either highly or scarcely aggressive phenotype, thus influencing prostate cancer progression. The fate of CSC was determined by signals released from tumor environment. Moreover, using microarray analysis we selected some molecules which could be involved in this cell-to-cell signaling, hypothesizing their potential value for prognostic or therapeutic applications.

Endometriosis gene expression heterogeneity and biosignature: a phylogenetic analysis

Endometriosis is a multifactorial disease with poorly understood etiology, and reflecting an evolutionary nature where genetic alterations accumulate throughout pathogenesis. Our objective was to characterize the heterogeneous pathological process using parsimony phylogenetics. Gene expression microarray data of ovarian endometriosis obtained from NCBI database were polarized and coded into derived (abnormal) and ancestral (normal) states. Such alterations are referred to as synapomorphies in a phylogenetic sense (or biomarkers). Subsequent gene linkage was modeled by Genomatix BiblioSphere Pathway software. A list of clonally shared derived (abnormal) expressions revealed the pattern of heterogeneity among specimens. In addition, it has identified disruptions within the major regulatory pathways including those involved in cell proliferation, steroidogenesis, angiogenesis, cytoskeletal organization and integrity, and tumorigenesis, as well as cell adhesion and migration. Furthermore, the analysis supported the potential central involvement of ESR2 in the initiation of endometriosis. The pathogenesis mapping showed that eutopic and ectopic lesions have different molecular biosignatures.

Lipocalin 2 in cancer: when good immunity goes bad

The innate immune molecule Lipocalin 2 (LCN2) was initially shown to combat bacterial infection by binding bacterial siderophores, hence impairing microbial iron sequestration. In recent years, it has become apparent that LCN2 is over-expressed in cancers of diverse histological origin and that it facilitates tumorigenesis by promoting survival, growth, and metastasis. Herein, we discuss emerging evidence that substantiates two functional roles for LCN2 in cancer: promotion of the epithelial-to-mesenchymal transition (EMT) that facilitates an invasive phenotype and metastasis, and sequestration of iron that results in cell survival and tumorigenesis. Further, we present evidence that upregulated LCN2 expression in solid tumors is induced by hypoxia and pro-inflammation, microenvironmental noxae that converge to cause an endoplasmic reticulum (ER) stress response. Taken together, it appears that tumor cells exploit the beneficial innate immune function of LCN2 to support uncontrolled growth. This duplicity in function highlights LCN2 and its upstream driver, the ER stress response, as key targets for cancer therapy.

Lipocalin-2 Is a chemokine inducer in the central nervous system: role of chemokine ligand 10 (CXCL10) in lipocalin-2-induced cell migration

The secreted protein lipocalin-2 (LCN2) has been implicated in diverse cellular processes, including cell morphology and migration. Little is known, however, about the role of LCN2 in the CNS. Here, we show that LCN2 promotes cell migration through up-regulation of chemokines in brain. Studies using cultured glial cells, microvascular endothelial cells, and neuronal cells suggest that LCN2 may act as a chemokine inducer on the multiple cell types in the CNS. In particular, up-regulation of CXCL10 by JAK2/STAT3 and IKK/NF-κB pathways in astrocytes played a pivotal role in LCN2-induced cell migration. The cell migration-promoting activity of LCN2 in the CNS was verified in vivo using mouse models. The expression of LCN2 was notably increased in brain following LPS injection or focal injury. Mice lacking LCN2 showed the impaired migration of astrocytes to injury sites with a reduced CXCL10 expression in the neuroinflammation or injury models. Thus, the LCN2 proteins, secreted under inflammatory conditions, may amplify neuroinflammation by inducing CNS cells to secrete chemokines such as CXCL10, which recruit additional inflammatory cells.

Lipocalin 2 regulation and its complex role in inflammation and cancer

Lipocalin 2 is a protein that has garnered a great deal of interest in multidisciplinary fields over the last two decades since its discovery. However, its exact function in metabolic processes remains to be completely characterized. More recently, it has come to light as a highly upregulated protein in the setting of injury and infection. This review focuses on lipocalin 2 regulation and its relationship to cytokine and endocrine signaling pathways.

TRAIL contributes to the apoptotic effect of 13-cis retinoic acid in human sebaceous gland cells

BACKGROUND

The full mechanism of action of isotretinoin [13-cis retinoic acid (13-cis RA)] in treating acne is unknown. 13-cis RA induces key genes in sebocytes that are involved in apoptosis, including Tumor necrosis factor Related Apoptosis Inducing Ligand (TRAIL).

OBJECTIVES

In this study, we investigated the role of 13-cis RA-induced TRAIL within SEB-1 sebocytes.

METHODS

Using 13-cis RA and recombinant human TRAIL (rhTRAIL) protein, we assessed induction of TRAIL and apoptosis in SEB-1 sebocytes, normal keratinocytes and patient skin biopsies.

RESULTS

Treatment with rhTRAIL protein increased TUNEL-positive staining in SEB-1 sebocytes. TRAIL siRNA significantly decreased the percentage of TUNEL-positive SEB-1 sebocytes in response to 13-cis RA treatment. Furthermore, TRAIL expression increased in the skin of patients with acne after 1 week of isotretinoin therapy compared with baseline. TRAIL expression localized within sebaceous glands. Unlike sebocytes, TRAIL protein expression was not increased in normal human epidermal keratinocytes in response to 13-cis RA, nor did rhTRAIL induce apoptosis in keratinocytes, suggesting that TRAIL is key in the sebocyte-specific apoptotic effects of 13-cis RA.

CONCLUSIONS

Taken together, our data suggest that TRAIL, like the neutrophil gelatinase-associated lipocalin, is involved in mediating 13-cis RA apoptosis of sebocytes.

Murine mammary tumor cells with a claudin-low genotype

Background

Molecular classification of human breast cancers has identified at least 5 distinct tumor subtypes; luminal A, luminal B, Her2-enriched, basal-like and claudin-low. The claudin-low subtype was identified in 2007 and is characterized by low expression of luminal differentiation markers and claudins 3, 4 and 7 and high levels of mesenchymal markers. Claudin-low tumors have a reported prevalence of 7-14% and these tumors have a poor prognosis.

Results

In this study we report the characterization of several cell lines established from mammary tumors that develop in MTB-IGFIR transgenic mice. Two lines, RM11A and RJ348 present with histological features and gene expression patterns that resemble claudin-low breast tumors. Specifically, RM11A and RJ348 cells express high levels of the mesenchymal genes Zeb1, Zeb2, Twist1 and Twist2 and very low levels of E-cadherin and claudins 3, 4 and 7. The RM11A and RJ348 cells are also highly tumorigenic when re-introduced into the mammary fat pad of mice.

Conclusions

Mammary tumor cells established from MTB-IGFIR transgenic mice can be used as in vitro and in vivo model systems to further our understanding of the poorly characterized, claudin-low, breast cancer subtype.

Characterization of the MDSC proteome associated with metastatic murine mammary tumors using label-free mass spectrometry and shotgun proteomics

Expansion of Gr-1+/CD11b+ myeloid derived suppressor cells (MDSCs) is governed by the presence of increasingly metastatic, malignant primary tumors. Metastasis, not the primary tumor, is often the cause of mortality. This study sought to fully characterize the MDSC proteome in response to metastatic and non-metastatic mammary tumors using label-free mass spectrometry shotgun proteomics in a mouse model with tumor cell lines, 67NR and 4T1, derived from the same tumor. 67NR cells form only primary mammary tumors, whereas 4T1 cells readily metastasize to the lungs, lymph nodes, and blood. Overall analysis identified a total of 2825 protein groups with a 0.78% false discovery rate. Of the 2814 true identifications, 43 proteins were exclusive to the 67NR group, 153 were exclusive to the 4T1 group, and 2618 were shared. Among the shared cohort, 26 proteins were increased and 31 were decreased in the metastatic 4T1 cohort compared to non-metastatic 67NR controls after filtering. MDSCs selectively express proteins involved in the γ-glutamyl transferase, glutathione synthase pathways, CREB transcription factor signaling, and other pathways involved in platelet aggregation, as well as lipid and amino acid metabolism, in response to highly metastatic 4T1 tumors. Cell cycle regulation dominated protein pathways and ontological groups of the 67NR non-metastatic group. Not only does this study provide a starting point to identify potential biomarkers of metastasis expressed by MDSCs; it identifies critical pathways that are unique to non-metastatic and metastatic conditions. Therapeutic interventions aimed at these pathways in MDSC may offer a new route to control malignancy and metastasis.