Clinical evidence for a protective role of lipocalin-2 against MMP-9 autodegradation and the impact for gastric cancer

Expressions of neutrophil gelatinase-associated lipocalin in gastric cancer: a potential biomarker for prognosis and an ancillary diagnostic test

The aim of this study was to explore the clinical significance of neutrophil gelatinase-associated lipocalin (NGAL) in the development and prognosis of gastric cancer. NGAL tumor levels were determined in 333 GC patients by immunohistochemistry. NGAL in blood samples from 63 healthy donors and 60 gastric cancer patients were also determined by enzyme-linked immunosorbent assay. Rate of NGAL expression was correlated with the size of tumor (69.3% in >4 cm tumors vs. 46.1% in ≤4 cm tumors), Lauren's classification (84.3% in diffuse type vs. 28.2% in intestinal type), lymph node metastasis (75.6% vs. 16.4% with no metastasis), vascular invasion (74.9% vs. 26.8% with no invasion), distant metastasis (94.3% vs. 50.3% with no distant metastasis), and TNM stage (81.8% in TNM III+IV vs. 20.5% in TNM I+II). NGAL expression can be used as an independent prognostic factor in gastric cancer as indicated by multivariate analysis. Positivity for serum NGAL was higher than that for carbohydrate antigen determinant, CA19-9 (38.1% vs. 12.5%) in TNM I, and higher than that for carcinoembryonic antigen, CEA (58.3% vs. 8.3%) and CA19-9 (58.3% vs. 8.3%) in TNM II. In conclusion, serum NGAL has great potential to be used as an ancillary test for diagnosis of gastric cancer. Increased expression of NGAL in tumors suggests gastric cancer is likely to be at an advanced stage with invasion and metastasis, and also poor prognosis.

Lipocalin 2 deficiency inhibits cell proliferation, autophagy, and mitochondrial biogenesis in mouse embryonic cells

Lipocalin 2 (LCN2) has been recently implicated as a critical player in multiple cancer tumorigeneses. However, the molecular mechanisms for its tumorigenic role are poorly understood. Herein, we investigated the effects of LCN2 on cell proliferation, autophagy, and mitochondrial biogenesis in MEF cells. We observed that LCN2 deficiency significantly inhibited cell proliferation and autophagy in MEF cells. Furthermore, mitochondrial DNA content, mRNA expression levels of mitochondrial-encoded gene cytochrome oxidase 2 and PGC-1α were all markedly reduced in LCN2⁻/⁻ MEF cells. Additionally, when compared with wild-type MEF cells, LCN2⁻/⁻ MEF cells expressed significantly higher levels of IRS-1, and displayed more potent TNFα-stimulated NF-κB activation. These findings demonstrate that LCN2 is a critical regulator of cell proliferation, autophagy, and mitochondrial biogenesis.

Relationships of lipocalin 2 with breast tumorigenesis and metastasis

Breast cancer is one of the most common cancers in women worldwide and accounts for one-sixth of cancer deaths in the United States. Breast cancer consists of a heterogeneous group of tumours classified into five types, in which the HER2/neu positive and the basal type (most are ER and HER2 negative) have the worst clinical prognosis. In recent years, prognostic/predictive markers such as ER/PR or HER2/neu have been widely used in the selection of the optimal breast cancer treatments for individual patients, which have been proven to be very effective in disease control. These results suggest that further examination of the molecular mechanisms underlying the breast tumorigenesis and identification of the potential biomarkers in different types of breast cancers will greatly benefit clinical diagnosis and facilitate the design of more effective personalized therapies to increase patient survival. This review aims to summarize recent research findings on lipocalin 2 (LCN2), a newly identified biomarker and a potential therapeutic target for breast cancer, and the possible mechanisms underlying its role in tumorigenesis and metastasis.

Increased serum levels of neutrophil gelatinase-associated lipocalin in patients with essential thrombocythemia and polycythemia vera

Neutrophil gelatinaase-associated lipocalin (NGAL) is a glycoprotein bound with matrix metalloproteinase-9 (MMP-9) in human neutrophils, and elevated tissue NGAL expression has been documented in different infectious and inflammatory conditions. Recent evidence suggests that NGAL expression is induced in many types of human cancer. Moreover, NGAL is required for BCR-ABL-induced tumorigenesis. The aim of the present study was to measure serum levels of NGAL in patients with essential thrombocythemia (ET) and polycythemia vera (PV). We also evaluated NGAL levels in patients with ET and PV with and without thrombotic events, to explore a possible correlation of NGAL with platelet and leukocyte activation, and in patients with sepsis. Serum NGAL levels in the study population were significantly higher than in healthy adults and in subjects with sepsis. A correlation between NGAL and the number of white cells and neutrophils was found in patients with PV and ET. NGAL serum levels were not different depending on the presence or not of the JAK2 mutation, and a mutant allele dosage effect was not observed for NGAL levels. Patients with PV and ET with thrombosis did not have significantly higher levels of NGAL. We were unable to demonstrate a significant association between serum NGAL levels and CD11b or CD62 expression. In conclusion, our study reports evidence demonstrating that increased levels of NGAL appear to be a characteristic of patients with PV and ET.

Up-regulation of the novel proinflammatory adipokines lipocalin-2, chitinase-3 like-1 and osteopontin as well as angiogenic-related factors in visceral adipose tissue of patients with colon cancer

BACKGROUND

Obesity is widely recognised as an important risk factor for colorectal cancer (CC).

AIM

The study aimed to evaluate the effect of CC on circulating concentrations and gene expression levels of inflammatory and angiogenesis-related factors in human visceral adipose tissue (VAT).

METHODS

VAT biopsies were obtained from 18 healthy individuals and 11 patients with CC. Real-time polymerase chain reactions were performed to quantify gene expression levels and zymographic analyses were used to determine the activity of matrix metalloproteinases (MMPs).

RESULTS

Patients with CC exhibited increased mRNA expression levels of lipocalin-2 (P=.014), osteopontin (P=.027), tumor necrosis factor-α (TNF-α) (P=.016) and chitinase-3 like-1 (P=.006) compared to control subjects in VAT. Gene expression levels of hypoxia-inducible factor-1 α, vascular endothelial growth factor and MMP-2 were significantly higher (P<.05) in VAT of patients with CC. The expression of insulin-like growth factor I, insulin growth factor binding protein 3 and MMP-9 followed the same trend, although no significant differences were reached. The enzymatic activity of MMP-9 was increased (P<.001) in patients with CC. Furthermore, individuals with CC showed increased (P<.05) circulating concentrations of the inflammatory markers interleukin-6, tumour necrosis factor α and hepatocyte growth factor, whereas levels of the anti-inflammatory adipokine adiponectin were decreased (P<.01).

CONCLUSION

These findings represent the first observation that mRNA levels of the novel inflammatory factors lipocalin-2, chitinase-3 like-1 and osteopontin are increased in human VAT of subjects with CC. This observation together with the up-regulation of angiogenic factors suggests that adipokines secreted by VAT may be involved in the development of colon cancer.

Neutrophil gelatinase-associated lipocalin immunoexpression in colorectal carcinoma: A stage-specific prognostic factor?

TNM post-surgical staging is considered to be one of the most powerful prognosticators for colorectal carcinoma. Although patient survival mostly decreases concomitantly to stage increase, in a percentage of cases TNM stage appears only to express the anatomic extent of the neoplasia with no correlation with clinical outcome. Thus, the identification of additional prognostic markers for colorectal cancer is required. Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein that appears to play an important role in colorectal cancer progression. In order to evaluate whether NGAL expression may be considered as a predictor of colorectal cancer progression, we analyzed its correlation with clinicopathological characteristics, as well as with patient progression-free survival in a series of surgically resected colorectal carcinomas. A variable NGAL immunoexpression was found in 24 out of the 64 analyzed cases. When only the positive cases were considered, a significant association was found between a high NGAL expression and the presence of distant metastases or high tumor stage. In addition, the presence of NGAL was a significant negative prognostic marker correlated with a shorter progression-free survival in stage I colorectal carcinoma, but not in the remaining TNM stages. If our findings are confirmed in more extensive analyses on stage I colorectal carcinoma, NGAL assessment may be used in order to select those patients with a higher progression risk and to submit them to adjuvant therapies useful to prevent adverse outcome.

Neutrophil gelatinase-associated lipocalin induces the expression of heme oxygenase-1 and superoxide dismutase 1, 2

Lipocalin-2 (Lcn2, NGAL) is a member of the lipocalin super family with diverse function such as the induction of apoptosis, the suppression of bacterial growth, and modulation of inflammatory response. Much interest has recently been focused on the physiological/pathological role of the lipocalin-2 that is considered to be a novel protective factor against oxidative stress. However, its precise biological roles in this protection are not fully understood. In this report we intended to test the effect of lipocalin-2 on the expression of heme oxygenase ((1, 2)) and superoxide dismutase ((1, 2)) which are two strong antioxidants. NGAL was cloned to pcDNA3.1 plasmid by using genetic engineering method. The recombinant vector was transfected to CHO and HEK293T to establish stable cell expressing NGAL and the expression of HO-1, 2 and SOD(1, 2) were compared with appropriate controls by RT-PCR and western blot. On the other hand, expression of NGAL was suppressed by siRNA transfection in order to study the effect of lipocalin-2 on mentioned genes/proteins. The results showed that the expression of HO-1 and SOD(1, 2) enzymes were higher in cells expressing recombinant lipocalin-2 compared with the control cells. Although the expression of HO-1 was lower in NGAL silencing cells, the expression of SOD(1) and SOD(2) were higher. Our data suggest that NGAL is a potent inducer of HO-1 and somewhat SOD(1) and SOD(2) and it appears that part of antioxidant property of NGAL could be attributed to the induction of HO-1 and SOD(1, 2).

Up-regulation of lipocalin 2 is associated with high-risk human papillomavirus and grade of cervical lesion at baseline but does not predict outcomes of infections or incident cervical intraepithelial neoplasia

Our objective was to assess whether neutrophil gelatinase-associated lipocalin (NGAL)/lipocalin 2 (LCN2) expression in cervical human papillomavirus (HPV) lesions has implications on the outcome of HPV infections or disease progression. Cervical biopsy specimens from 225 women in the Latin American Screening study were analyzed for NGAL/LCN2 expression using immunohistochemical analysis, to assess associations with cervical intraepithelial neoplasia (CIN) grade, high-risk HPV, and in predicting outcomes of high-risk (HR)-HPV infections. Expression of NGAL/LCN2 increased with lesion grade (odds ratio [OR], 3.86; 95% confidence interval [CI], 1.53-9.71; P = .001). Up-regulation was also related to HR-HPV detection (OR, 2.21; 95% CI, 1.15-4.24; P = .016) and showed a linear relationship to HR-HPV load (P = .002). NGAL/LCN2 expression was of no value in predicting the outcomes of HR-HPV infections or the surrogate end points (incident CIN 1+ and CIN 2+) of progressive disease. Because the SV40 large T antigen is a powerful up-regulator of this lipocalin, up-regulation of NGAL/LCN2 in CIN is probably induced by HR-HPV E6 oncoprotein, most likely by eliminating its normal transcription repression exerted by wild-type p53.

Expression of matrix metalloproteinases 2 and 9 in human gastric cancer and superficial gastritis

AIM: To assess expression of matrix metalloproteinases 2 (MMP2) and MMP9 in gastric cancer, superficial gastritis and normal mucosa, and to measure metalloproteinase activity.

METHODS: MMP2 and MMP9 mRNA expression was determined by quantitative real-time polymerase chain reaction. Normalization was carried out using three different factors. Proteins were analyzed by quantitative gelatin zymography (qGZ).

RESULTS: 18S ribosomal RNA (18SRNA) was very highly expressed, while hypoxanthine ribosyltransferase-1 (HPRT-1) was moderately expressed. MMP2 was highly expressed, while MMP9 was not detected or lowly expressed in normal tissues, moderately or highly expressed in gastritis and highly expressed in cancer. Relative expression of 18SRNA and HPRT-1 showed no significant differences. Significant differences in MMP2 and MMP9 were found between cancer and normal tissue, but not between gastritis and normal tissue. Absolute quantification of MMP9 echoed this pattern, but differential expression of MMP2 proved conflictive. Analysis by qGZ indicated significant differences between cancer and normal tissue in MMP-2, total MMP-9, 250 and 110 kDa bands.

CONCLUSION: MMP9 expression is enhanced in gastric cancer compared to normal mucosa; interpretation of differential expression of MMP2 is difficult to establish.

Disruption of the Lcn2 gene in mice suppresses primary mammary tumor formation but does not decrease lung metastasis

Based largely on studies in xenograft models, lipocalin-2 (Lcn2) has been implicated in the progression of multiple types of human tumors, including breast cancer. Here we examine the role of Lcn2 in mammary tumorigenesis and lung metastasis using an in vivo molecular genetics approach. We crossed a well-characterized transgenic mouse model of breast cancer, the MMTV-PyMT (mouse mammary tumor virus-polyoma middle T antigen) mouse, with two independent gene-targeted Lcn2(-/-) mouse strains of the 129/Ola or C57BL/6 genetic background. The onset and progression of mammary tumor development and lung metastasis in the female progeny of these crosses were monitored over a 20-week period. Female Lcn2(-/-)MMTV-PyMT mice of the 129/Ola background (Lcn2(-/-)PyMT(129)) showed delayed onset of mammary tumors, and both Lcn2(-/-)PyMT(129) mice and Lcn2(-/-)MMTV-PyMT mice of the C57BL/6 background (Lcn2(-/-)PyMT(B6)) exhibited significant decreases in multiplicity and tumor burden (approximately 2- to 3-fold), as measured by total tumor weight and volume. At the molecular level, mammary tumors derived from Lcn2(-/-)PyMT(B6) females showed reduced matrix metalloproteinase-9 (MMP-9) activity and a lack of high molecular weight MMP activity. However, although increased MMP-9 activity has been linked to tumor progression, neither Lcn2(-/-)PyMT(B6) nor Lcn2(-/-)PyMT(129) female mice showed a reduction in lung metastases compared to Lcn2(+/+)PyMT controls. Our results demonstrate, using an in vivo animal model approach, that Lcn2 is a potent inducer of mammary tumor growth but not a significant promoter of lung metastasis.

Inhibition of lipocalin 2 impairs breast tumorigenesis and metastasis

Lipocalin 2 (LCN2; also known as NGAL) is a secreted glycoprotein and its elevated expression has been observed in breast cancers. However, the importance of LCN2 in breast tumorigenesis is unclear. Here, we employed a spontaneous mammary tumor mouse model showing that MMTV-ErbB2(V664E) mice lacking mouse LCN2 had significantly delayed mammary tumor formation and metastasis with reduced matrix metalloproteinase-9 activity in the blood. LCN2 expression is upregulated by HER2/phosphoinositide 3-kinase/AKT/NF-kappaB pathway. Decreasing LCN2 expression significantly reduced the invasion and migration ability of HER2(+) breast cancer cells. Furthermore, injecting an anti-mouse LCN2 antibody into mice bearing established murine breast tumors resulted in significant blockage of lung metastasis. Our findings indicate that LCN2 is a critical factor in enhancing breast tumor formation and progression possibly in part by stabilizing matrix metalloproteinase-9. Our results suggest that inhibition of LCN2 function by an inhibitory monoclonal antibody has potential for breast cancer therapy, particularly by interfering with metastasis in aggressive types of breast cancer.

Circulating levels of matrix metalloproteinase-9 (MMP-9), neutrophil gelatinase-associated lipocalin (NGAL) and their complex MMP-9/NGAL in breast cancer disease

BACKGROUND

Recent evidence suggests that neutrophil gelatinase-associated lipocalin (NGAL) expression is induced in many types of human cancer, while detection of its complex with matrix metalloproteinase-9 (MMP-9) is correlated with cancer disease status. We aim to evaluate the serum expression of MMP-9, NGAL and their complex (MMP-9/NGAL) during the diagnostic work-up of women with breast abnormalities and investigate their correlation with disease severity.

METHODS

The study included 113 women with non-palpable breast lesions undergoing vacuum-assisted breast biopsy for histological diagnosis, and 30 healthy women, which served as controls. Expression levels of MMP-9, NGAL and their complex MMP-9/NGAL were determined in peripheral blood samples with immunoenzymatic assays.

RESULTS

Women with invasive ductal carcinoma exhibited significantly increased levels of MMP-9, NGAL and MMP-9/NGAL compared to healthy controls (MMP-9: p < 0.003, NGAL: p < 0.008 MMP-9/NGAL: p < 0.01). Significant correlations were observed between MMP-9 and NGAL serum levels and breast disease severity score (r = 0.229, p < 0.006 and r = 0.206, p < 0.01, respectively), whereas a non-significant correlation was found for their complex. MMP-9, NGAL and their complex MMP-9/NGAL levels were not correlated with either Body Mass Index (BMI) or age of patients.

CONCLUSION

These findings suggest that the serum measurement of MMP-9 and NGAL may be useful in non-invasively monitoring breast cancer progression, while supporting their potential role as early biomarkers of breast disease status.

Neutrophil gelatinase-associated lipocalin (NGAL) in human neoplasias: a new protein enters the scene

The small 25 kDa peptide, neutrophil gelatinase-associated lipocalin (NGAL), first known as an antibacterial factor of natural immunity, and an acute phase protein, is currently one of the most interesting and enigmatic proteins involved in the process of tumor development. The aim of the present review is to point out the main contradictory, sometimes even paradoxical, effects attributed to NGAL in human neoplasias. For instance, acting as an intracellular iron carrier and protecting MMP9 from proteolytic degradation, NGAL has a clear pro-tumoral effect, as has already been observed in different tumors (e.g. breast, stomach, oesophagus, brain) in humans. Moreover, in thyroid carcinomas, NGAL is strongly induced by NF-kB, an important factor involved both in tumor growth and in the link between chronic inflammation and neoplastic development. However, on the contrary, some studies have demonstrated that NGAL can inhibit the pro-neoplastic factor HIF-1alpha, FA-Kinase phosphorylation and also VEGF synthesis, thus suggesting that, in alternative conditions, NGAL also, paradoxically, has an anti-tumoral and anti-metastatic effect in neoplasias of, for example, the colon, ovary and pancreas. Finally, in the field of clinical oncology, attention is currently focused on the potential use of NGAL levels in making an early diagnosis, establishing a prognosis and predicting response to different treatments.

Clinical significance of Neutrophil gelatinase-associated lipocalin(NGAL) expression in primary rectal cancer

BACKGROUND

Emerging evidence has demonstrated that Neutrophil gelatinase-associated lipocalin (NGAL) is up-regulated in multiple malignancies, including oesophagus cancer, and plays a critical role in tumorigenesis and progression. However, till now, little is known about the role of NGAL in human rectal cancer. Its association with clinicopathologic characteristics and expression of MMP-9, one of its target genes, has not been reported systematically in rectal cancer. Therefore, to further determine the potential involvement of NGAL in rectal cancer, we have evaluated the expression level of NGAL mRNA by real time RT-PCR, and further elucidated the correlation of NGAL mRNA expression with clinicopathologic features and MMP-9 in rectal cancer.

METHODS

100 paired samples of rectal cancer and adjacent normal tissues obtained from inpatients undergoing surgical operation were allocated into two groups (cancer group and control group). The mRNA expression of NGAL and MMP-9 was determined by real-time RT-PCR. The association between their expression and clinicopathological characteristics of rectal cancer were analysised.

RESULTS

Among the 100 rectal cancers, 69 cases of NGAL mRNA up-regulation were observed. NGAL mRNA up-regulation was positively correlated with MMP-9 (rs = 0.393, p < 0.001). In rectal cancer, NGAL mRNA overexpression was significantly associated with depth of invasion (p = 0.028), lymph node metastasis (p = 0.009), venous involvement (p = 0.023) and advanced pTNM stage (p = 0.011).

CONCLUSION

In human rectal cancer, NGAL mRNA expression was elevated. NGAL mRNA up-regulation was correlated significantly with tumor progression and MMP-9 mRNA overexpression in rectal cancer, suggesting a more aggressive phenotype. NGAL could be used for rectal cancer characterization.

Lipocalin 2 is required for pulmonary host defense against Klebsiella infection

Antimicrobial proteins comprise a significant component of the acute innate immune response to infection. They are induced by pattern recognition receptors as well as by cytokines of the innate and adaptive immune pathways and play important roles in infection control and immunomodulatory homeostasis. Lipocalin 2 (siderocalin, NGAL, 24p3), a siderophore-binding antimicrobial protein, is critical for control of systemic infection with Escherichia coli; however, its role in mucosal immunity in the respiratory tract is unknown. In this study, we found that lipocalin 2 is rapidly and robustly induced by Klebsiella pneumoniae infection and is TLR4 dependent. IL-1beta and IL-17 also individually induce lipocalin 2. Mucosal administration of IL-1beta alone could reconstitute the lipocalin 2 deficiency in TLR4 knockout animals and rescue them from infection. Lipocalin 2-deficient animals have impaired lung bacterial clearance in this model and mucosal reconstitution of lipocalin 2 protein in these animals resulted in rescue of this phenotype. We conclude that lipocalin 2 is a crucial component of mucosal immune defense against pulmonary infection with K. pneumoniae.

Expression analysis of Barrett's esophagus-associated high-grade dysplasia in laser capture microdissected archival tissue

PURPOSE

Identifying genes differentially expressed in nondysplastic BE (NDBE) from those expressed in high-grade dysplasia (HGD) should be of value in improving our understanding of this transition and may yield new diagnostic and/or prognostic markers. The aim of this study was to determine the differential transcriptome of HGD compared with NDBE through gene microarray analysis of epithelial cells microdissected from archival tissue specimens.

EXPERIMENTAL DESIGN

Laser capture microdissection was used to isolate epithelial cells from adjacent inflammatory and stromal cells. Epithelial mRNA was extracted from areas of NDBE and HGD in matched biopsies from 11 patients. mRNA was reverse transcribed and applied on Affymetrix cDNA microarray chips customized for formalin-exposed tissue. For a subset of these genes, differential gene expression was confirmed by real-time PCR and immunohistochemistry.

RESULTS

There were 131 genes overexpressed by at least 2.5-fold in HGD versus NDBE and 16 genes that were underexpressed by at least 2.5-fold. Among the overexpressed genes are several previously shown to be increased in the neoplastic progression of BE, as well as novel genes such as lipocalin-2, S100A9, matrix metallopeptidase 12, secernin 1, and topoisomerase IIalpha. Genes decreased in dysplastic epithelium include MUC5AC, trefoil factor 1 (TFF1), meprin A, and CD13. Real-time PCR validated the changes in expression in 24 of 28 selected genes. Immunohistochemistry confirmed increased protein expression for topoisomerase IIalpha, S100A9, and lipocalin-2 and decreased expression of TFF1 across the spectrum of BE-associated dysplasia from NDBE through adenocarcinoma.

CONCLUSIONS

This is the first study to identify epithelial genes differentially expressed in HGD versus NDBE in matched patient samples. The genes identified include several previously implicated in the pathogenesis of BE-associated dysplasia and new candidates for further investigation.

MMP-2 geno-phenotype is prognostic for colorectal cancer survival, whereas MMP-9 is not

The prognostic significance of single-nucleotide polymorphisms (SNPs) and tumour protein levels of MMP-2 and MMP-9 was evaluated in 215 colorectal cancer patients. Single-nucleotide polymorphism MMP-2(-1306T) and high MMP-2 levels were significantly associated with worse survival. Extreme tumour MMP-9 levels were associated with poor prognosis but SNP MMP-9(-1562C>T) was not. Tumour MMP levels were not determined by their SNP genotypes.