[Show abstract][Hide abstract] ABSTRACT: Background:We investigated the expression of members of the epithelial cell adhesion molecule (EpCAM) signalling pathway in gastric cancer (GC) testing the following hypotheses: are these molecules expressed in GC and are they putatively involved in GC biology.Methods:The study cohort consisted of 482 patients. The following members of the EpCAM signalling pathway were analysed by immunohistochemistry and were correlated with various clinico-pathological patient characteristics: extracellular domain of EpCAM (EpEX), intracellular domain of EpCAM (EpICD), E-cadherin, β-catenin, presenilin-2 (PSEN2), and ADAM17.Results:All members of the EpCAM signalling pathway were differentially expressed in GC. The expression correlated significantly with tumour type (EpEX, EpICD, E-cadherin, β-catenin, and PSEN2), mucin phenotype (EpEX, EpICD, β-catenin, and ADAM17), T-category (EpEX, E-cadherin, and β-catenin), N-category (EpEX and β-catenin), UICC tumour stage (EpEX, EpICD, β-catenin, and PSEN2), tumour grade (EpEX, EpICD, E-cadherin, β-catenin, and PSEN2), and patients' survival (EpEX, EpICD, and PSEN2). A significant coincidental expression in GC was found for EpEX, EpICD, E-cadherin, β-catenin, PSEN2, and ADAM17. Decreased immunodetection of EpEX in locally advanced GC was not associated with decreased EpCAM mRNA levels.Conclusion:All members of the EpCAM signalling pathway are expressed in GC. The expression correlated significantly with each other and with various clinico-pathological patient characteristics, including patients' survival. Thus, the EpCAM signalling pathway is a highly interesting putative therapeutic target in GC.British Journal of Cancer advance online publication, 5 September 2013; doi:10.1038/bjc.2013.536 www.bjcancer.com.
British Journal of Cancer 09/2013; · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated various phenotypic and genotypic biomarkers of gastric cancer (GC) testing the following hypotheses: are these biomarkers suitable for the identification of GC subtypes, are they of prognostic significance, and should any of these biomarkers be considered to tailor patient treatment in the future. The study cohort consisted of 482 patients. pTNM-stage was based on surgical pathologic examination. The Laurén and mucin phenotype was assessed. Helicobacter pylori and Epstein-Barr virus infections were documented. The following biomarkers were determined: BRAF, KRAS, NRAS, and PIK3CA genotype, microsatellite instability, mucin 1, mucin 2, mucin 5, and mucin 6, CD10, E-cadherin, β-catenin, and lysozyme. The histologic phenotype correlated with 10/13 (77%) clinicopathologic patient characteristics and 6/13 (46%) immunohistochemical/molecular biological biomarkers. Inversely, immunohistochemical biomarkers (mucin phenotype, E-cadherin, β-catenin, and lysozyme) were unsuitable for subclassification of GC. It showed too much overlap between the different subtypes. Among the genotypes, only microsatellite instability correlated with tumor type being more prevalent in intestinal and unclassified GCs. Patient survival correlated significantly with 8 (62%) clinicopathologic and 5 (36%) immunohistochemical/molecular biomarkers. Interestingly, in proximal GCs, KRAS mutation was associated with worse prognosis, as was persistent H. pylori infection in unclassified GCs. Mucin 2 (all patients, proximal GCs) and PIK3CA (exon 20; intestinal type GC) prognosticated independently patient survival. The biomarkers examined herein are unsuitable to aid histologic classification of GC. However, several of them show a correlation with either phenotype and/or prognosis and may be considered to tailor patient treatment in the future, such as KRAS, PIK3CA, MSI, and H. pylori status.
Diagnostic molecular pathology: the American journal of surgical pathology, part B 07/2013; · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study evaluates potential markers in blood and stools for their ability to distinguish bacterial from viral gastroenteritis. A total of 108 patients were prospectively recruited, of which 27 showed bacterial, 30 viral, and 51 no detectable pathogen, respectively. Cytokines, C-reactive protein (CRP), and white blood cells as well as the 2 fecal markers lactoferrin and calprotectin were determined. Statistics comprised Kruskal-Wallis test and U test in addition to an assessment of receiver operating characteristic. Interferon γ (IFNγ) levels were significantly increased in the viral group compared to the bacterial and nonspecific group. For the bacterial group, both fecal markers lactoferrin and calprotectin as well as CRP were significantly higher in comparison to the other 2 groups. To differentiate between bacterial and viral gastroenteritis, CRP, serum IFNγ, and the fecal proteins lactoferrin and calprotectin may be useful. A corresponding algorithm should be evaluated prospectively.
Diagnostic microbiology and infectious disease 06/2013; · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Caveolin-1 (Cav1), a scaffold protein of membrane caveolae and coactivator of peroxisome proliferator-activated receptor (PPARγ), inhibits oncogenic signaling through Ras and wingless (WNT). However, the in vivo role of Cav1 in colorectal cancer (CRC) remained unknown. To test whether loss of Cav1 accelerates tumorigenesis, we generated a novel mouse model of CRC by crossing C57BL/6 Apc(min/+) with B6129 Cav1 knockout (Cav1(-/-)) mice. Apc(min/+) Cav1(-/-) mice developed large, microinvasive and vascularized intraepithelial adenocarcinomas in the distal colon and rectum with higher incidence than Apc(min/+) Cav1(+/-) and Apc(min/+) Cav1(+/+) littermates. Intratumoral gene signatures related to Ras and WNT signaling were elevated, nuclear localization of PPARγ protein and expression of PPARγ-target genes were reduced independently of Cav1. The PPARγ-agonist rosiglitazone prevented tumor formation in mice irrespectively of the Cav1 status and up-regulated expression of the Ras-inhibitory protein docking protein-1 (Dok1). Thus, codeficiency of Cav1 and adenomatous polyposis coli (APC) facilitated formation of CRC, and activation of PPARγ may offer novel strategies for treatment of CRC.
[Show abstract][Hide abstract] ABSTRACT: Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25(+) regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies ("humming bird") compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells.
[Show abstract][Hide abstract] ABSTRACT: Background
We evaluated the risk of sampling errors in specimens of biopsy size, which may be caused by heterogeneous overexpression of Her2/neu in gastric cancer (GC).Patients and methodsThe study cohort comprised 454 gastrectomy patients with adenocarcinoma of the stomach or esophago-gastric junction. Tissue micro-arrays (TMAs) served as 'biopsy procedure' and were generated from formalin-fixed and paraffin-embedded tissue: five tissue cylinders were collected randomly from each tumor, rendering 2230 core cylinders. These were compared with 454 whole tissue sections obtained from the same paraffin blocks. Her2/neu expression and gene amplification were analyzed by immunohistochemistry and in situ hybridization. The Her2/neu status was determined according to GC scoring system by two independent observers.ResultsIn whole tissue sections, 37 (8.1%; observer 1) and 38 (8.4%; observer 2) of the GCs, and in the corresponding TMAs, 28 (6.3%; observer 1) and 28 (6.3%; observer 2) of the GCs were classified as Her2/neu-positive (kappa value 98.5% and 96.2%; P < 0001). Comparison of whole tissue sections with corresponding TMAs showed a false-negative rate of 24% and a false-positive rate of 3% for TMAs.Conclusion
Assessment of the Her2/neu status in tissue biopsies carries a significant risk of sampling errors, thereby rendering patients unsuitable for treatment with trastuzumab.
[Show abstract][Hide abstract] ABSTRACT: Bile acids are synthesized from cholesterol and are major risk factors for Barrett adenocarcinoma (BAC) of the esophagus. Caveolin-1 (Cav1), a scaffold protein of membrane caveolae, is transcriptionally regulated by cholesterol via sterol-responsive element-binding protein-1 (SREBP1). Cav1 protects squamous epithelia by controlling cell growth and stabilizing cell junctions and matrix adhesion. Cav1 is frequently down-regulated in human cancers; however, the molecular mechanisms that lead to this event are unknown. We show that the basal layer of the nonneoplastic human esophageal squamous epithelium expressed Cav1 mainly at intercellular junctions. In contrast, Cav1 was lost in 95% of tissue specimens from BAC patients (n = 100). A strong cytoplasmic expression of Cav1 correlated with poor survival in a small subgroup (n = 5) of BAC patients, and stable expression of an oncogenic Cav1 variant (Cav1-P132L) in the human BAC cell line OE19 promoted proliferation. Cav1 was also detectable in immortalized human squamous epithelial, Barrett esophagus (CPC), and squamous cell carcinoma cells (OE21), but was low in BAC cell lines (OE19, OE33). Mechanistically, bile acids down-regulated Cav1 expression by inhibition of the proteolytic cleavage of 125-kDa pre-SREBP1 from the endoplasmic reticulum/Golgi apparatus and nuclear translocation of active 68-kDa SREBP1. This block in SREBP1's posttranslational processing impaired transcriptional activation of SREBP1 response elements in the proximal human Cav1 promoter. Cav1 was also down-regulated in esophagi from C57BL/6 mice on a diet enriched with 1% (wt/wt) chenodeoxycholic acid. Mice deficient for Cav1 or the nuclear bile acid receptor farnesoid X receptor showed hyperplasia and hyperkeratosis of the basal cell layer of esophageal epithelia, respectively. These data indicate that bile acid-mediated down-regulation of Cav1 marks early changes in the squamous epithelium, which may contribute to onset of Barrett esophagus metaplasia and progression to BAC.
[Show abstract][Hide abstract] ABSTRACT: Resistance to chemotherapy is a major obstacle for curative treatment of human gastric cancer (GC). However, the underlying molecular mechanisms are largely unknown. Wingless-type MMTV integration site family members (WNTs) are secreted glycoproteins involved in embryogenesis and, on inappropriate expression in the adult, in cancer. Here, we show expression of WNT6 in GC patient specimens, human GC cell lines and in a mouse model of GC. In human GC cells, WNT6 expression was enhanced by caveolin-1 (Cav1), a scaffold protein of plasma membrane caveolae. WNT6 knock-down and overexpression experiments demonstrated that WNT6 increased the resistance to apoptotic cell death induced by the anthracycline chemotherapeutics epirubicin (Epi) and doxorubicin (Dox). Epi increased the activity of the human WNT6 promoter through Cav1-dependent binding of β-catenin to the proximal WNT6 promoter. Epi increased both WNT6/Wnt6 and Cav1 expression in human GC cells and within the tumor area of a murine model of GC (CEA424-SV40 TAg). In GC patients, WNT6 expression was positively associated with the tumor stage and the nodal status, and inversely correlated with the response to ECF (Epi, cisplatin, 5-fluorouracil) chemotherapy. These results showed that WNT6 and Cav1 are upregulated by chemotherapeutics and enhance the resistance of GC cells to anthracycline drugs. Understanding the molecular mechanisms driving WNT6/Cav1-induced drug resistance will provide benefits in developing new therapies for GC.Oncogene advance online publication, 27 February 2012; doi:10.1038/onc.2012.40.
[Show abstract][Hide abstract] ABSTRACT: Chemotherapy for advanced colorectal cancer leads to improved survival; however, predictors of response to systemic treatment are not available. Genomic and epigenetic alterations of the gene encoding transcription factor AP-2 epsilon (TFAP2E) are common in human cancers. The gene encoding dickkopf homolog 4 protein (DKK4) is a potential downstream target of TFAP2E and has been implicated in chemotherapy resistance. We aimed to further evaluate the role of TFAP2E and DKK4 as predictors of the response of colorectal cancer to chemotherapy.
We analyzed the expression, methylation, and function of TFAP2E in colorectal-cancer cell lines in vitro and in patients with colorectal cancer. We examined an initial cohort of 74 patients, followed by four cohorts of patients (total, 220) undergoing chemotherapy or chemoradiation.
TFAP2E was hypermethylated in 38 of 74 patients (51%) in the initial cohort. Hypermethylation was associated with decreased expression of TFAP2E in primary and metastatic colorectal-cancer specimens and cell lines. Colorectal-cancer cell lines overexpressing DKK4 showed increased chemoresistance to fluorouracil but not irinotecan or oxaliplatin. In the four other patient cohorts, TFAP2E hypermethylation was significantly associated with nonresponse to chemotherapy (P<0.001). Conversely, the probability of response among patients with hypomethylation was approximately six times that in the entire population (overall estimated risk ratio, 5.74; 95% confidence interval, 3.36 to 9.79). Epigenetic alterations of TFAP2E were independent of mutations in key regulatory cancer genes, microsatellite instability, and other genes that affect fluorouracil metabolism.
TFAP2E hypermethylation is associated with clinical nonresponsiveness to chemotherapy in colorectal cancer. Functional assays confirm that TFAP2E-dependent resistance is mediated through DKK4. In patients who have colorectal cancer with TFAP2E hypermethylation, targeting of DKK4 may be an option to overcome TFAP2E-mediated drug resistance. (Funded by Deutsche Forschungsgemeinschaft and others.).
New England Journal of Medicine 01/2012; 366(1):44-53. · 54.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Peroxisome proliferator-activated receptor γ (PPARγ) is a transcription factor that promotes differentiation and cell survival in the stomach. PPARγ upregulates and interacts with caveolin-1 (Cav1), a scaffold protein of Ras/mitogen-activated protein kinases (MAPKs). The cytoplasmic-to-nuclear localization of PPARγ is altered in gastric cancer (GC) patients, suggesting a so-far-unknown role for Cav1 in spatial regulation of PPARγ signaling. We show here that loss of Cav1 accelerated proliferation of normal stomach and GC cells in vitro and in vivo. Downregulation of Cav1 increased Ras/MAPK-dependent phosphorylation of serine 84 in PPARγ and enhanced nuclear translocation and ligand-independent transcription of PPARγ target genes. In contrast, Cav1 overexpression sequestered PPARγ in the cytosol through interaction of the Cav1 scaffolding domain (CSD) with a conserved hydrophobic motif in helix 7 of PPARγ's ligand-binding domain. Cav1 cooperated with the endogenous Ras/MAPK inhibitor docking protein 1 (Dok1) to promote the ligand-dependent transcriptional activity of PPARγ and to inhibit cell proliferation. Ligand-activated PPARγ also reduced tumor growth and upregulated the Ras/MAPK inhibitors Cav1 and Dok1 in a murine model of GC. These results suggest a novel mechanism of PPARγ regulation by which Ras/MAPK inhibitors act as scaffold proteins that sequester and sensitize PPARγ to ligands, limiting proliferation of gastric epithelial cells.
Molecular and Cellular Biology 06/2011; 31(16):3497-510. · 5.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bile acids from duodenogastric reflux promote inflammation and increase the risk for gastro-oesophageal cancers. FXR (farnesoid X receptor/NR1H4) is a transcription factor regulated by bile acids such as CDCA (chenodeoxycholic acid). FXR protects the liver and the intestinal tract against bile acid overload; however, a functional role for FXR in the stomach has not been described. We detected FXR expression in the normal human stomach and in GC (gastric cancer). FXR mRNA and protein were also present in the human GC cell lines MKN45 and SNU5, but not in the AGS cell line. Transfection of FXR into AGS cells protected against TNFα (tumour necrosis factor α)-induced cell damage. We identified K13 (keratin 13), an anti-apoptotic protein of desmosomes, as a novel CDCA-regulated FXR-target gene. FXR bound to a conserved regulatory element in the proximal human K13 promoter. Gastric expression of K13 mRNA was increased in an FXR-dependent manner by a chow diet enriched with 1% (w/w) CDCA and by indomethacin (35 mg/kg of body weight intraperitoneal) in C57BL/6 mice. FXR-deficient mice were more susceptible to indomethacin-induced gastric ulceration than their WT (wild-type) littermates. These results suggest that FXR increases the resistance of human and murine gastric epithelial cells to inflammation-mediated damage and may thus participate in the development of GC.
[Show abstract][Hide abstract] ABSTRACT: Metabolic imaging of gastric cancer is limited due to the 30% of primary tumors that are not (18)F-fluorodeoxyglucose (FDG) avid. In contrast, the proliferation marker (18)F-fluorothymidine (FLT) has been shown to visualize also non-FDG-avid gastric tumors. In this study we tested whether FLT-positron emission tomography (PET) can improve the predictive potential of molecular imaging for assessing response to neoadjuvant therapy in gastric cancer compared with FDG-PET.
45 patients with gastric cancer underwent FDG- and FLT-PET before and 2 weeks after initiation of chemotherapy. FDG/FLT-PET findings and Ki67 immunohistochemistry were correlated with clinical and histopathological response and survival.
14 patients had non-FDG-avid tumors, whereas all tumors could be visualized by FLT-PET. No significant association of clinical or histopathological response with any of the analyzed metabolic parameters [initial standardized uptake value (SUV), SUV after 2 weeks, change of SUV for FDG/FLT] was found. Univariate Cox regression analysis for Ki67 and metabolic parameters revealed significant prognostic impact for survival only for FLT SUV(mean) day 14 (p=0.048) and Ki67 (p=0.006). Multivariate Cox regression analysis (including clinical response, Lauren type, ypN category, and FLT SUV(mean) day 14) revealed Lauren type and FLT SUV(mean) day 14 as the only significant prognostic factors (p=0.006, p=0.002).
FLT uptake 2 weeks after initiation of therapy was shown to be the only imaging parameter with significant prognostic impact. Neither FLT-PET nor FDG-PET were correlated with histopathological or clinical response. However, these data must be interpreted with caution due to the single-center trial study design, relatively short follow-up, poor response rates, and unfavorable prognosis.
Annals of Surgical Oncology 05/2011; 18(12):3316-23. · 3.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated the differential expression of Dicer and Drosha, as well as that of microRNA (miRNA), in adjacent normal and tumour samples of patients with gastric cancer. The expression of Dicer and Drosha was studied by immunohistochemistry in 332 gastric cancers and correlated with clinico-pathological patient characteristics. Differential expression of miRNAs was studied using the Invitrogen NCode(™) Multi-Species miRNA Microarray Probe Set containing 857 mammalian probes in a test set of six primary gastric cancers (three with and three without lymph node metastases). Differential expression was validated by RT-PCR on an independent validation set of 20 patients with gastric cancer. Dicer and Drosha were differentially expressed in non-neoplastic and neoplastic gastric tissue. The expression of Drosha correlated with local tumour growth and was a significant independent prognosticator of patient survival. Twenty miRNAs were up- and two down-regulated in gastric carcinoma compared with non-neoplastic tissue. Six of these miRNAs separated node-positive from node-negative gastric cancers, ie miR-103, miR-21, miR-145, miR-106b, miR-146a, and miR-148a. Five miRNAs expressed differentially in node-positive cancers had conserved binding sites for mRNAs differentially expressed in the same set of tumour samples. Gastric cancer shows a complex derangement of the miRNA-ome, including Dicer and Drosha. These changes correlate independently with patient prognosis and probably influence local tumour growth and nodal spread.
The Journal of Pathology 11/2010; 222(3):310-9. · 7.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: G-protein-coupled receptors (GPCRs) are prime candidates for novel cancer prevention and treatment strategies. We searched for differentially expressed GPCRs in node positive gastric carcinomas.
Differential expression of GPCRs in three node positive vs. three node negative intestinal type gastric carcinomas was analyzed by gene array technology. The candidate genes CXCL12 and its receptor CXCR4 were validated by real-time reverse-transcription polymerase chain reaction in an independent set of 37 gastric carcinomas. Translation was studied by immunohistochemistry in 347 gastric carcinomas using tissue microarrays as well as in 61 matching lymph node metastases. Protein expression was correlated with clinicopathological patient characteristics and survival. 52 GPCRs and GPCR-related genes were up- or down-regulated in node positive gastric cancer, including CXCL12. Differential expression of CXCL12 was confirmed by RT-PCR and correlated with local tumour growth. CXCL12 immunopositivity was negatively associated with distant metastases and tumour grade. Only 17% of gastric carcinomas showed CXCR4 immunopositive tumour cells, which was associated with higher local tumour extent. 29% of gastric carcinomas showed CXCR4 positive tumour microvessels. Vascular CXCR4 expression was significantly associated with higher local tumour extent as well as higher UICC-stages. When expressing both, CXCL12 in tumour cells and CXCR4 in tumour microvessels, these tumours also were highly significantly associated with higher T- and UICC-stages. Three lymph node metastases revealed vascular CXCR4 expression while tumour cells completely lacked CXCR4 in all cases. The expression of CXCL12 and CXCR4 had no impact on patient survival.
Our results substantiate the significance of GPCRs on the biology of gastric carcinomas and provide evidence that the CXCL12-CXCR4 pathway might be a novel promising antiangiogenic target for the treatment of gastric carcinomas.
PLoS ONE 01/2010; 5(4):e10087. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Screening for colorectal cancer (CRC) has shown to reduce cancer-related mortality, however, acceptance and compliance to current programmes are poor. Developing new, more acceptable non-invasive tests for the detection of cancerous and precancerous colorectal lesions would not only allow preselection of individuals for colonoscopy, but may also prevent cancer by removal of precancerous lesions.
Plasma from 128 individuals (cohort I - exploratory study: 73 cases / 55 controls) was used to test the performance of a single marker, SEPT9, using a real-time quantitative PCR assay. To validate performance of SEPT9, plasma of 76 individuals (cohort II - validation study: 54 cases / 22 controls) was assessed. Additionally, improvement of predictive capability considering SEPT9 and additionally ALX4 methylation was investigated within these patients.
In both cohorts combined, methylation of SEPT9 was observed in 9% of controls (3/33), 29% of patients with colorectal precancerous lesions (27/94) and 73% of colorectal cancer patients (24/33). The presence of both SEPT9 and ALX4 markers was analysed in cohort II and was observed in 5% of controls (1/22) and 37% of patients with polyps (18/49). Interestingly, also 3/5 (60%) patients with colorectal cancer were tested positive by the two marker panel in plasma.
While these data confirm the detection rate of SEPT9 as a biomarker for colorectal cancer, they also show that methylated DNA from advanced precancerous colorectal lesions can be detected using a panel of two DNA methylation markers, ALX4 and SEPT9. If confirmed in larger studies these data indicate that screening for colorectal precancerous lesions with a blood-based test may be as feasible as screening for invasive cancer.
PLoS ONE 01/2010; 5(2):e9061. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The chemokine receptor CXCR4 plays a prominent role in the biology of many different tumours, promoting angiogenesis and metastasis. The impact of CXCR4 expression on tumour biology has been described in various gastrointestinal malignancies, but data on its in situ expression and clinicopathological correlations are sparse. Using a novel specific rabbit anti-CXCR4 antibody, the aim was to assess CXCR4 expression immunohistochemically on tissue microarrays generated from 402 colorectal cancers (CRCs) and compare it with CXCL12 expression and various clinicopathological parameters.
CXCR4-expressing tumour cells were observed in 31% of the cases, and expression correlated only with blood vessel invasion (P = 0.049). Furthermore, CXCR4 was found in tumour microvessels in 25% of CRCs. This pattern of CXCR4 expression correlated significantly with T- (P = 0.008), N- (P = 0.009), M- (P = 0.043), L- (P = 0.014) and V-category (P = 0.043) as well as with International Union Against Cancer (UICC) stage (P = 0.001). Furthermore, in node negative CRCs, vascular CXCR4 expression was an independent adverse prognostic factor [hazard ratio 2.87 (1.31-6.29), P = 0.009]. No correlation with CXCL12 expression was found.
Our data provide evidence that CXCR4 plays an important role in tumour angiogenesis of CRC. Therefore, the CXCR4 pathway is a promising therapeutic target for anti-angiogenic therapies in CRC.
[Show abstract][Hide abstract] ABSTRACT: Retinoic acid-regulated nuclear matrix-associated protein (RAMP) is a WD40 repeat-containing protein that is involved in various biological functions, but little is known about its role in human cancer. This study aims to delineate the oncogenic role of RAMP in gastric carcinogenesis.
RAMP expression was examined by real-time quantitative RT-PCR, immunohistochemistry and western blotting. Inhibition of RAMP expression was performed by siRNA-mediated knockdown. The functional effects of RAMP on cell kinetics were measured by cell viability assay, colony formation assay and flow cytometry. Cell lines stably expressing RAMP were established to investigate the oncogenic effects of RAMP in vitro.
Ramp was readily expressed in all seven gastric cancer cell lines and was significantly increased in human gastric cancer tissues when compared with their adjacent non-cancerous tissues (P<0.001). In keeping with this, expression of RAMP protein was higher in gastric cancer tissues compared with their adjacent non-cancerous tissues, whereas moderate protein expression were noted in intestinal metaplasia. Knockdown of RAMP in gastric cancer cells significantly reduced cell proliferation (P<0.01) and soft agar colony formation (P<0.001), but induced apoptosis and G(2)/M arrest. In additional, knockdown RAMP induced cell apoptosis is dependent on functional accumulation of p53 and p21 and induction of cleaved caspases-9, caspases-3 and PARP. Strikingly, overexpression of RAMP promoted anchorage-independent cell growth in soft agar.
Our findings demonstrate that RAMP plays an oncogenic role in gastric carcinogenesis. Inhibition of RAMP may be a promising approach for gastric cancer therapy.
British Journal of Cancer 09/2009; 101(4):691-8. · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Protein extracts from formalin-fixed and paraffin-embedded (FFPE) tissue for proteomic analysis has recently gained attention. In this study, we explored the possibility to standardize tissue sampling from paraffin blocks and compared the protein extracts with those obtained from fresh frozen material.
Fresh frozen and FFPE material was obtained from five patients with pancreatic ductal adenocarcinoma either by cutting sections with a microtome or by stamping a cylinder with tissue micro-array technology. All samples were weighed, forwarded to protein extraction and analyzed by polyacrylamide gel electrophoresis and Western blotting. Immunohistochemistry allocated proteins in tissue sections.
Sampling of tissue was highly reproducible, as assessed by sample weight. While protein concentrations were significantly higher in fresh frozen material compared to FFPE material, equal amounts of protein were extracted from FFPE using either paraffin sections or core cylinders in SDS-PAGE, all three procedures showed comparable protein patterns. In Western blotting, annexin I had the same molecular weight independent of the sample source and sampling procedure.
The sampling of FFPE specimens for protein extraction and analysis can be standardized, uncovering equal amounts of tissue and protein. In addition, the proteins extracted from FFPE tissue seem to be the same compared with those extracted from fresh frozen tissue.
Experimental and Molecular Pathology 09/2009; 88(1):190-6. · 2.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:MicroRNAs (miRNAs) are 19-25-nucleotides regulatory non-protein-coding RNA molecules that regulate the expressions of a wide variety of genes, including some involved in cancer development. In this study, we investigated the possible role of miR-143 in colorectal cancer (CRC).Methods:Expression levels of human mature miRNAs were examined using real-time PCR-based expression arrays on paired colorectal carcinomas and adjacent non-cancerous colonic tissues. The downregulation of miR-143 was further evaluated in colon cancer cell lines and in paired CRC and adjacent non-cancerous colonic tissues by qRT–PCR. Potential targets of miR-143 were defined. The functional effect of miR-143 and its targets was investigated in human colon cancer cell lines to confirm miRNA–target association.Results:Both real-time PCR-based expression arrays and qRT–PCR showed that miR-143 was frequently downregulated in 87.5% (35 of 40) of colorectal carcinoma tissues compared with their adjacent non-cancerous colonic tissues. Using in silico predictions, DNA methyltranferase 3A (DNMT3A) was defined as a potential target of miR-143. Restoration of the miR-143 expression in colon cell lines decreased tumour cell growth and soft-agar colony formation, and downregulated the DNMT3A expression in both mRNA and protein levels. DNMT3A was shown to be a direct target of miR-143 by luciferase reporter assay. Furthermore, the miR-143 expression was observed to be inversely correlated with DNMT3A mRNA and protein expression in CRC tissues.Conclusion:Our findings suggest that miR-143 regulates DNMT3A in CRC. These findings elucidated a tumour-suppressive role of miR-143 in the epigenetic aberration of CRC, providing a potential development of miRNA-based targeted approaches for CRC therapy.
British Journal of Cancer 07/2009; 101(4):699-706. · 5.08 Impact Factor