Chemokines as Prognostic Factor in Colorectal Cancer Patients: A Systematic Review and Meta-Analysis.

Chemokines orchestrate many aspects of tumorigenic processes such as angiogenesis, apoptosis and metastatic spread, and related receptors are expressed on tumor cells as well as on inflammatory cells (e.g., tumor-infiltrating T cells, TILs) in the tumor microenvironment. Expressional changes of chemokines and their receptors in solid cancers are common and well known, especially in affecting colorectal cancer patient outcomes. Therefore, the aim of this current systematic review and meta-analysis was to classify chemokines as a prognostic biomarker in colorectal cancer patients. A systematic literature search was conducted in PubMed, CENTRAL and Web of Science. Information on the chemokine expression of 25 chemokines in colorectal cancer tissue and survival data of the patients were investigated. The hazard ratio of overall survival and disease-free survival with chemokine expression was examined. The risk of bias was analyzed using Quality in Prognosis Studies. Random effects meta-analysis was performed to determine the impact on overall respectively disease survival. For this purpose, the pooled hazard ratios (HR) and their 95% confidence intervals (CI) were used for calculation. Twenty-five chemokines were included, and the search revealed 5556 publications. A total of thirty-one publications were included in this systematic review and meta-analysis. Overexpression of chemokine receptor CXCR4 was associated with both a significantly reduced overall survival (HR = 2.70, 95%-CI: 1.57 to 4.66, p = 0.0003) as well as disease-free survival (HR = 2.68, 95%-CI: 1.41 to 5.08, p = 0.0026). All other chemokines showed either heterogeneous results or few studies were available. The overall risk of bias for CXCR4 was rated low. At the current level of evidence, this study demonstrates that CXCR4 overexpression in patients with colorectal cancer is associated with a significantly diminished overall as well as disease-free survival. Summed up, this systematic review and meta-analysis reveals CXCR4 as a promising prognostic biomarker. Nevertheless, more evidence is needed to evaluate CXCR4 and its antagonists serving as new therapeutic targets.

Protective effect of miR-18a in resected liver metastases of colorectal cancer and FOLFOX treatment.

BACKGROUND: Colorectal cancer ranks second in terms of cancer associated deaths worldwide, whereas miRNA play a pivotal role in the etiology of cancer and its metastases. AIMS: Studying the expression and cellular function of miR-18a in metastatic colorectal cancer and association to progression-free survival. METHODS AND RESULTS: Colorectal liver metastases (N = 123) and primary colorectal cancer (N = 27) where analyzed by RT-PCR and correlated with clinical follow up data. Invasion and migration assays were performed with the liver metastatic cell line LIM2099 after miR-18a knockdown. Cell viability under FOLFOX treatment and knockdown was measured. We found that the expression of miR-18a was increased 4.38-fold in liver metastases and 3.86-fold in colorectal tumor tissue compared to healthy liver tissue and colorectal mucosa, respectively (p ≤ .001). Patients with a high miR-18a expression in liver metastases had a progression-free survival (PFS) of 13.6 months versus 8.9 months in patients with low expression (N = 123; p = .024). In vitro migration of LIM2099 cells was reduced after miR-18a knockdown and cell viability was significantly increased after miR-18a knockdown and treatment with folinic acid or oxaliplatin. Subgroup analysis of PFS revealed significant benefits for patients with high miR-18a expression receiving 5-FU, folinic acid or oxaliplatin. CONCLUSIONS: High expression of miR-18a in colorectal liver metastases might have a protective effect after resection of metastases and FOLFOX treatment regarding PFS.

Long non-coding RNAs CCAT1 and CCAT2 in colorectal liver metastases are tumor-suppressive via MYC interaction and might predict patient outcomes.

BACKGROUND: Liver metastases severely reduce the long term survival of colorectal cancer patients. Long non-coding RNAs (lncRNAs) CCAT1 and CCAT2 have previously been found to be associated with impaired patient outcomes in primary colorectal cancer. We aimed to elucidate the role of CCAT1 and CCAT2 in colorectal liver metastases. METHODS: Total RNA was isolated from 97 human tissue samples of colorectal liver metastases and adjacent normal liver tissue. Gene expression analysis was performed by RT-qPCR and Multiplex ELISA and correlated with patient characteristics and survival. Gene expression, cancer cell migration, invasion, and proliferation were studied after siRNA-mediated knockdown of CCAT1, CCAT2, and MYC in metastatic colorectal cancer cell lines Colo205 and HROC277Met2. RESULTS: Elevated expression levels of lncRNAs CCAT1 and CCAT2, and their common target MYC in colorectal liver metastases were associated with prolonged progression-free survival after liver resection. High expression of CCAT1 was likewise associated with prolonged overall survival. Knockdown of CCAT1, CCAT2, and MYC resulted in increased migratory and invasive potential in metastatic colorectal cancer cell lines. Gene expression analysis revealed alterations in constituents of Wnt signaling following knockdown. CONCLUSION: Our findings demonstrate tumor-suppressive functions of lncRNAs CCAT1 and CCAT2 in colorectal liver metastases. They suppress Wnt signaling directly and indirectly through target gene MYC and might prevent further metastatic spread from colorectal liver metastases.

Granulin: An Invasive and Survival-Determining Marker in Colorectal Cancer Patients.

BACKGROUND: Granulin is a secreted, glycosylated peptide-originated by cleavage from a precursor protein-which is involved in cell growth, tumor invasion and angiogenesis. However, the specific prognostic impact of granulin in human colorectal cancer has only been studied to a limited extent. Thus, we wanted to assess the expression of granulin in colorectal cancer patients to evaluate its potential as a prognostic biomarker. METHODS: Expressional differences of granulin in colorectal carcinoma tissue (n = 94) and corresponding healthy colon mucosa were assessed using qRT-PCR. Immunohistochemistry was performed in colorectal cancer specimens (n = 97), corresponding healthy mucosa (n = 47) and colorectal adenomas (n = 19). Subsequently, the results were correlated with histopathological and clinical patients' data. HCT-116 cells were transfected with siRNA for invasion and migration assays. RESULTS: Immunohistochemistry and qRT-PCR revealed tumoral over expression of granulin in colorectal cancer specimens compared to corresponding healthy colon mucosa and adenomas. Tumoral overexpression of granulin was associated with a significantly impaired overall survival. Moreover, downregulation of granulin by siRNA significantly diminished the invasive capacities of HCT-116 cells in vitro. CONCLUSION: Expression of granulin differs in colorectal cancer tissue, adenomas and healthy colon mucosa. Furthermore, granulin features invasive and migrative capabilities and overexpression of granulin correlates with a dismal prognosis. This reveals its potential as a prognostic biomarker and granulin could be a worthwhile molecular target for individualized anticancer therapy.

Impact of EGFR and EGFR ligand expression on treatment response in patients with metastatic colorectal cancer.

Up to 50% of patients with colorectal cancer (CRC) have either synchronous or metachronous hepatic metastases in the course of their disease. Patients with metastatic CRC (mCRC) whose tumors express wild-type KRAS benefit from treatment with monoclonal antibodies (such as cetuximab or panitumumab) that target the epidermal growth factor receptor (EGFR). However, the therapeutic response to these antibodies is variable, and further predictive models are required. The present study examined whether expression of different EGFRs or their ligands in tumors was associated with the response to cetuximab treatment. Tumor tissues, collected during liver resection in 28 patients with mCRC, were analyzed. The protein expression levels of EGFR/ErbB1, ErbB2, ErbB3 and the EGFR ligands heregulin and amphiregulin were determined using Luminex 200® and enzyme-linked immunosorbent assays. Computed tomography or magnetic resonance imaging was performed 4 weeks before and 6-8 weeks after treatment with cetuximab. Response to treatment was assessed using the response evaluation criteria for solid tumors (RECIST). The association between the protein expression levels of different EGFRs and their ligands with RECIST criteria was then analyzed to determine whether these protein levels could predict the treatment response to cetuximab. A total of 12 patients exhibited a partial response, 9 exhibited stable disease and 7 exhibited progressive disease after cetuximab therapy according to RECIST. The expression levels of EGFRs (EGFR/ErbB1, ErbB2 and ErbB3) and their ligands (heregulin and amphiregulin) were not significantly associated with the response to cetuximab therapy. Therefore, the present study indicated that EGFR or EGFR ligand expression did not predict treatment response in patients with CRC with liver metastases following cetuximab therapy.

Volume changes of the pancreatic head remnant after distal pancreatectomy.

BACKGROUND: Little is known about pancreatic regeneration in humans after surgical resection. We examined pancreatic head volume changes after distal pancreatectomy. METHODS: Using computed tomography or magnetic resonance imaging volumetry, we assessed volume changes of the pancreatic head remnant in 67 patients at defined time points (3, 6, 9, and 12 months) after distal pancreatectomy. A volume increase of >1 cm³ was defined as hypertrophy, a decrease of >1 cm³ as atrophy, and alterations of ±1 cm³ were considered as unchanged. Volumetry results were correlated with clinical patient data, histology, and immunohistochemistry for the pancreatic regeneration markers Pax4, Ghrelin, cholecystokinin receptor A, and cholecystokinin receptor B of the resection margin. RESULTS: Of 67 patients, 33 patients (49%) exhibited a hypertrophy of the pancreatic head remnant with a median increase of 5.08 cm³, 26 patients (39%) showed an atrophy, and in 8 patients (12%) pancreatic volume remained unchanged. No correlation of preoperative, postoperative, and new-onset diabetes with hypertrophy or atrophy was found. In patients with ductal adenocarcinoma, hypertrophy occurred less frequently compared to patients with other pathologies (38% vs 63%; P = .04). In patients with ductal adenocarcinoma, hypertrophy was associated with significantly shorter survival. Patients with a postoperative hypertrophy that did not suffer from ductal adenocarcinoma displayed significantly less fibrosis at the resection margin compared to patients with a postoperative atrophy and pancreatic ductal adenocarcinoma patients. Immunohistochemical staining revealed no differential expression of the tested regeneration markers in hypertrophy versus atrophy. CONCLUSION: This study demonstrates volume changes of the pancreatic head remnant after distal pancreatectomy. Clinical and functional significance and underlying molecular mechanisms in humans remain unclear.

CCR5 status and metastatic progression in colorectal cancer.

Multiple reports have highlighted the importance of the local immunological cellular composition (i.e. the density of effector T cells and macrophage polarization state) in predicting clinical outcome in advanced metastatic stage of colorectal cancer. However, in spite of the general association between a high effector T cell density and improved outcome, our recent work has revealed a specific lymphocyte-driven cancer cell-supporting signal. Indeed, lymphocyte-derived CCL5 supports CCR5-positive tumor cell proliferation and thereby fosters tumor growth in metastatic liver lesions. Upon systematic analysis of CCR5 expression by tumor cells using immunohistochemistry, we observed that the intensity of CCR5 increases with primary tumor size and peaks in T4 tumors. In liver metastases however, though CCR5 expression intensity is globally heightened compared to primary tumors, alterations in the expression patterns appear, leading to "patchiness" of the stain. CCR5 patchiness is, therefore, a signature of liver metastases in our cohort (n = 97 specimens) and relates to globally decreased expression intensity, but does not influence the extent of the response to CCR5 inhibitor Maraviroc in patients. Moreover, CCR5 patchiness relates to a poor immune landscape characterized by a low cytotoxic-to-regulatory T cell ratio at the invasive margin and enriched cellular and molecular markers of macrophage M2 polarization. Finally, because higher numbers of PD-1- and CTLA-4-positive cells surround tumors with patchy CCR5 expression, one can speculate that these tumors potentially respond to immune checkpoint blockade. This hypothesis is corroborated by the prolonged disease-free survival and disease-specific survival observed in patients with low gene expression of CCR5 in metastases from two publically available cohorts. These observations highlight the complex role of the CCL5-CCR5 axis in CRC metastatic progression and warrant further investigations.

E3 ubiquitin ligase Smurf2: a prognostic factor in microsatellite stable colorectal cancer.

PURPOSE: Smurf2 is a member of the homologous to E6-AP carboxyl terminus family of E3 ubiquitin ligases. Changes in their expression pattern are known to contribute to tumorigenesis. Smurf2 plays a decisive role in cell differentiation, proliferation, and migration and exhibits a dual role in cancer - functioning as both oncogene and tumor suppressor. Dysregulation of Smurf2 in different cancer types has been described, besides colorectal cancer (CRC). We therefore examined the expression and oncogenic potential of Smurf2 in human CRC patients. MATERIALS AND METHODS: Expression levels of Smurf2 were analyzed via qRT-PCR in CRC specimens and healthy mucosa from 98 patients who had undergone surgery due to CRC. Spatial expression of Smurf2 was additionally studied by immunohistochemistry. siRNA-mediated knockdown of Smurf2 was applied for migration and invasion assays in DLD-1 and SW-480 cells. RESULTS: Smurf2 was significantly overexpressed in CRC tissue compared to corresponding healthy colon mucosa. Smurf2 expression levels differed significantly between microsatellite instable (MSI) and microsatellite stable (MSS) CRC. In patients suffering from MSS CRC, high tumoral expression of Smurf2 was significantly associated with impaired overall survival. Consistently, in vitro analysis revealed that knockdown of Smurf2 reduced the invasive and migratory potential of MSS CRC cells. CONCLUSION: Smurf2 expression is upregulated in CRC specimens and affects survival dependent on patients' MSI status. Moreover, Smurf2 supports cancer cell migration and invasion, collectively suggesting an oncogenic function in CRC.

High-Throughput Screening of Combinatorial Immunotherapies with Patient-Specific In Silico Models of Metastatic Colorectal Cancer.

Solid tumors are rich ecosystems of numerous different cell types whose interactions lead to immune escape and resistance to immunotherapy in virtually all patients with metastatic cancer. Here, we have developed a 3D model of human solid tumor tissue that includes tumor cells, fibroblasts, and myeloid and lymphoid immune cells and can represent over a million cells over clinically relevant timeframes. This model accurately reproduced key features of the tissue architecture of human colorectal cancer and could be informed by individual patient data, yielding in silico tumor explants. Stratification of growth kinetics of these explants corresponded to significantly different overall survival in a cohort of patients with metastatic colorectal cancer. We used the model to simulate the effect of chemotherapy, immunotherapies, and cell migration inhibitors alone and in combination. We classified tumors according to tumor and host characteristics, showing that optimal treatment strategies markedly differed between these classes. This platform can complement other patient-specific ex vivo models and can be used for high-throughput screening of combinatorial immunotherapies.Significance: This patient-informed in silico tumor growth model allows testing of different cancer treatment strategies and immunotherapies on a cell/tissue level in a clinically relevant scenario. Cancer Res; 78(17); 5155-63. ©2018 AACR.

In Silico Modeling of Immunotherapy and Stroma-Targeting Therapies in Human Colorectal Cancer.

Despite the fact that the local immunological microenvironment shapes the prognosis of colorectal cancer, immunotherapy has shown no benefit for the vast majority of colorectal cancer patients. A better understanding of the complex immunological interplay within the microenvironment is required. In this study, we utilized wet lab migration experiments and quantitative histological data of human colorectal cancer tissue samples (n = 20) including tumor cells, lymphocytes, stroma, and necrosis to generate a multiagent spatial model. The resulting data accurately reflected a wide range of situations of successful and failed immune surveillance. Validation of simulated tissue outcomes on an independent set of human colorectal cancer specimens (n = 37) revealed the model recapitulated the spatial layout typically found in human tumors. Stroma slowed down tumor growth in a lymphocyte-deprived environment but promoted immune escape in a lymphocyte-enriched environment. A subgroup of tumors with less stroma and high numbers of immune cells showed high rates of tumor control. These findings were validated using data from colorectal cancer patients (n = 261). Low-density stroma and high lymphocyte levels showed increased overall survival (hazard ratio 0.322, P = 0.0219) as compared with high stroma and high lymphocyte levels. To guide immunotherapy in colorectal cancer, simulation of immunotherapy in preestablished tumors showed that a complex landscape with optimal stroma permeabilization and immune cell activation is able to markedly increase therapy response in silico These results can help guide the rational design of complex therapeutic interventions, which target the colorectal cancer microenvironment. Cancer Res; 77(22); 6442-52. ©2017 AACR.

Detailed resolution analysis reveals spatial T cell heterogeneity in the invasive margin of colorectal cancer liver metastases associated with improved survival.

On a broader scale, T cell density and localization in colorectal cancer liver metastases have prognostic and predictive implications. As T cell distribution at higher resolutions has not been fully investigated, a detailed resolution analysis of T cell distribution was performed. Patient tissues were divided into 10 µm distance classes between the tumor border and adjacent normal liver. Thereby, distinct density patterns of T cell localization in relation to the malignant tissue could be detected. At a distance of 20 to 30 µm to the tumor, a decrease of CD3 T cells is common. Within this area, cytotoxic Granzyme B and CD8+ T cells were found to be significantly reduced as well as CD163 macrophages were increased and identified to be in close contact with T cells. Our data suggests a physical or functional border within this region. Survival analysis revealed improved overall survival in patients with high T cells numbers at the direct tumor border. Interestingly, the decreased T cells in the 20 to 30 µm region were also found to be significantly associated with improved survival. Consequently, the detailed localization of T cells, despite blockade, could be associated with improved clinical outcome. The high-resolution analysis represents new insights into relevant heterogenous T cell distributions especially related to clinical responses. As the paradoxical observation of localization-dependent prognostic relevance of T cell densities is only detectable by detailed spatial analyses, this investigation of spatial profiles at higher resolutions is suggested as a new biomarker for survival and response to therapies.

Serum MMP7, MMP10 and MMP12 level as negative prognostic markers in colon cancer patients.

BACKGROUND: Matrixmetalloproteinases (MMPs) comprise a family of zinc-dependent endopeptidases which are involved in angiogenesis, tumor invasion and metastatic formation. Up to date, the prognostic relevance of MMPs in serum of patients with colon cancer remains unknown. Thus, we wanted to assess an expression pattern of MMPs in a homogenous cohort of colon cancer patients to assess their potential as prognostic biomarkers. METHODS: Differences in the expression pattern of MMP7, MMP10 and MMP12 in 78 serum specimens of patients with an adenocarcinoma of the colon and serum specimens of a healthy control group were assessed using Luminex-100 technologies. Subsequently, we correlated these results with histopathological and clinical data of the patients. RESULTS: Luminex based expression analysis revealed a significant overexpression of MMP7 and an overexpression of MMP10 and MMP12 in the sera of colon cancer patients compared to the healthy control group. Patients with vascular invasion showed a significantly higher MMP12 expression than V0-staged patients. Moreover overexpression of MMP7, MMP10 and MMP12 in colon cancer patients´ sera displayed a significantly impaired overall survival. Multivariate analysis revealed high MMP10 serum levels to be an independent adverse prognostic marker in colon cancer patients. CONCLUSIONS: Expression patterns of MMP7, MMP10 and MMP12 in colon cancer patients´ sera are different compared to serum specimens of healthy individuals. Furthermore, overexpression of MMP7, MMP10 and MMP12 in colon cancer patients´ sera correlates with a dismal prognosis and may help to stratify patients into different risk groups.

Tumoral Immune Cell Exploitation in Colorectal Cancer Metastases Can Be Targeted Effectively by Anti-CCR5 Therapy in Cancer Patients.

The immune response influences the clinical course of colorectal cancer (CRC). Analyzing the invasive margin of human CRC liver metastases, we identified a mechanism of immune cell exploitation by tumor cells. While two distinct subsets of myeloid cells induce an influx of T cells into the invasive margin via CXCL9/CXCL10, CCL5 is produced by these T cells and stimulates pro-tumoral effects via CCR5. CCR5 blockade in patient-derived functional in vitro organotypic culture models showed a macrophage repolarization with anti-tumoral effects. These anti-tumoral effects were then confirmed in a phase I trial with a CCR5 antagonist in patients with liver metastases of advanced refractory CRC. Mitigation of tumor-promoting inflammation within the tumor tissue and objective tumor responses in CRC were observed.

Expressional STAT3/STAT5 Ratio is an Independent Prognostic Marker in Colon Carcinoma.

BACKGROUND: Signal transducer and activator of transcription proteins (STATs) are crucial regulators of cell growth and differentiation; however, their specific prognostic impact in human colon cancer has only been studied to limited extent. We aimed to assess the prognostic significance of specific STAT expression patterns in colon carcinoma. METHODS: Protein expression patterns of activated STAT1, STAT3, STAT4, and STAT5 in human colon carcinoma tissue and corresponding healthy mucosa (n = 104) were assessed using multiplex bead-based immunoassay technologies. Expression patterns were correlated with clinical and survival data. Immunohistochemistry was performed to assess spatial expression of STAT3 and STAT5. RESULTS: STAT3 was underexpressed whereas STAT4 and STAT5 were overexpressed in colon carcinoma tissue. Primary tumors from patients with distant metastases (M1) displayed significantly increased expression of STAT1 and STAT3 but decreased expression of STAT4 and STAT5. Increased tumor expression of STAT1 or STAT3 was associated with impaired patient survival, whereas increased expression of STAT4 or STAT5 correlated with improved survival. Multivariate analysis identified an increased STAT3/STAT5 expressional ratio as an adverse prognostic marker in colon cancer patients. CONCLUSIONS: The tumor progression-associated transcription factors STAT3, STAT4, and STAT5 are differently expressed in colon carcinoma tissue and colon mucosa. Moreover, the STAT3/STAT5 expression ratio is an independent prognostic marker in colon cancer patients.

Prognostic impact of a compartment-specific angiogenic marker profile in patients with pancreatic cancer.

Pancreatic cancer consists of a heterogenous bulk of tumor cells and stroma cells which contribute to tumor progression by releasing angiogenic factors. Those factors can be detected as circulating serum factors. We performed a compartment-specific analysis of tumor-derived and stroma-derived angiogenic factors to identify biomarkers and molecular targets for the treatment of pancreatic cancer. Kryo-frozen tissue from primary ductal adenocarcinomas (n = 51) was laser-microdissected to isolate tumor and stroma tissue. Expression of 17 angiogenic factors (angiopoietin-2, follistatin, GCSF, HGF, interleukin-8, leptin, PDGF-BB, PECAM-1, VEGF, matrix metalloproteinase -1, -2, -3, -7, -9, -10, -12, and -13) was analyzed using a multiplex elisa assay for tissue-derived proteins and corresponding serum. Our study reveals a compartment-specific expression profile for several angiogenic factors and matrix metalloproteinases. ROC analysis of corresponding serum samples reveals MMP-7 and MMP-12 as strong classifiers for the diagnosis of patients with pancreatic cancer vs. healthy control donors. High expression of tumor-derived PDGF-BB and MMP-1 correlates with prolonged survival in univariate and multivariate analysis. In conclusion, a distinct expression patterns for angiogenic cytokines and MMPs in pancreatic cancer and surrounding stroma may implicate them as novel targets for cancer treatment. Tumor-derived PDGF-BB and MMP-1 are significant and independent prognostic markers for poor survival.

Hepatic metastases of colorectal cancer are rather homogeneous but differ from primary lesions in terms of immune cell infiltration.

The immune system plays an important role in shaping the clinical course of colorectal cancer (CRC). However, it is still unclear how the immune infiltrates of primary CRC lesions and distant metastases by immune effector cells are related to each other. To address this issue, we quantified CD3+, CD8+ and granzyme B+ lymphocytes in primary CRC samples and corresponding liver metastases. This analysis showed that the prognostic predictions that can be drawn from the infiltration of immune cells in primary CRCs and their metastases are heterogeneous. To investigate whether such heterogeneity would also be observed within CRC hepatic metastases, the density of the immune infiltrate and cytokine production were assessed in opposite sides of the same metastatic lesion. In addition, tumor-infiltrating lymphocytes were assessed in sequential sections of the same metastatic lesion, with a spacing of 30 µm. In summary, consistent cell counts and cytokine levels were detected within the same lesion. The study of a case of synchronous metastases, however, suggested that different metastatic lesions within the same patient may be heterogeneous, perhaps indicating a major impact for local causes on tumor infiltration by immune cells. In summary, our study demonstrates a consistent degree of heterogeneity between primary tumors and hepatic metastases but an excellent intra-lesional homogeneity. These findings may be of key importance for patient stratification and the development of personalized strategies against CRC.

Expression analysis of aldehyde dehydrogenase 1A1 (ALDH1A1) in colon and rectal cancer in association with prognosis and response to chemotherapy.

BACKGROUND: Aldehyde dehydrogenase 1A1 (ALDH1A1) has been described as a cancer stem cell marker and as a regulator of cellular chemoresistance. Therefore, ALDH1A1 has been suggested as potential biomarker to stratify patients into different risk categories for a "personalized" therapy approach. We have investigated the prognostic role of ALDH1A1 in primary colorectal cancer and its value in predicting response to chemotherapy in metastatic colorectal cancer. METHODS: Immunostaining against ALDH1A1 was performed on a paraffin-embedded tissue microarray including 659 primary colon cancer samples and 338 rectal cancer samples. Likewise, tissue of 44 palliatively resected colorectal liver metastases on whole-mount tissue slides was immunostained against ALDH1A1. Cytoplasmic, nuclear, and stromal expression of ALDH1A1 was assessed and merged with histopathological and clinical data. RESULTS: Univariate and multivariate analysis revealed that cytoplasmic and stromal expression of ALDH1A1 is not significantly associated with prognosis either in colon or in rectal cancer. Furthermore, cytoplasmic expression of ALDH1A1 does not predict response to palliative chemotherapy in patients with metastatic diseases. Intriguingly, as a novel finding, nuclear expression of ALDH1A1 was observed in a small subgroup of patients with colon cancer and rectal cancer. In colon cancer, nuclear expression was significantly associated with shortened overall survival by univariate and multivariate analysis. CONCLUSIONS: Immunohistochemical expression analysis of ALDH1A1 in colon cancer is useful for the detection of nuclear expression in a small subpopulation of patients and is associated with shorter survival. Cytoplasmic expression fails to be of clinical relevance as prognostic or predictive marker in colorectal cancer.

Overexpression of ZEB2 at the invasion front of colorectal cancer is an independent prognostic marker and regulates tumor invasion in vitro.

PURPOSE: Epithelial-to-mesenchymal transition (EMT) plays a pivotal role in tumor invasion and dissemination. EMT occurs predominantly at the tumor edge where it is induced by cytokines, the extracellular matrix environment, or hypoxia. In the tumor cell, it is further mediated by several transcription factors and microRNAs. The aim of this study was to explore the expression of EMT-associated genes at the invasive front in colorectal cancer and to evaluate their prognostic significance. EXPERIMENTAL DESIGN: We evaluated the expression of 13 EMT-associated genes at the invasion front of 30 colorectal liver metastases by quantitative real-time PCR. Immunostaining against zinc finger E-box-binding homeobox 2 (ZEB2) was carried out on 175 primary colorectal cancer specimens and 30 colorectal liver metastases and correlated to clinical and histopathologic data. DLD-1 cells were transfected with siRNA and subjected to migration and invasion assays. RESULTS: Gene expression analysis and immunohistochemistry showed an upregulation of ZEB2 at the invasion front in primary colorectal cancer and liver metastases. Overexpression of ZEB2 at the invasion front correlated significantly with tumor stage in primary colorectal cancer. Moreover, univariate and multivariate analysis revealed overexpression of ZEB2 at the invasion front as an independent prognostic marker for cancer-specific survival. Downregulation of ZEB2 by siRNA decreased the migration and invasion capacity of DLD-1 cells in vitro. CONCLUSIONS: Overexpression of ZEB2 at the invasion front correlates with tumor progression and predicts cancer-specific survival in primary colorectal cancer. Therefore, ZEB2 may be interesting as biomarker and potential target for treatment of colorectal cancer.

Invasion front-specific expression and prognostic significance of microRNA in colorectal liver metastases.

The tumor edge of colorectal cancer and its adjacent peritumoral tissue is characterized by an invasion front-specific expression of genes that contribute to angiogenesis or epithelial-to-mesenchymal transition. Dysregulation of these genes has a strong impact on the invasion behavior of tumor cells. However, the invasion front-specific expression of microRNA (miRNA) still remains unclear. Therefore, the aim of the present study was to investigate miRNA expression patterns at the invasion front of colorectal liver metastases. Laser microdissection of colorectal liver metastases was performed to obtain separate tissue compartments from the tumor center, tumor invasion front, liver invasion front and pure liver parenchyma. Microarray expression analysis revealed 23 miRNA downregulated in samples from the tumor invasion front with respect to the same miRNA in the liver, the liver invasion front or the tumor center. By comparing samples from the liver invasion front with samples from pure liver parenchyma, the tumor invasion front and the tumor center, 13 miRNA were downregulated. By quantitative RT-PCR, we validated the liver invasion front-specific downregulation of miR-19b, miR-194, let-7b and miR-1275 and the tumor invasion front-specific downregulation of miR-143, miR- 145, let-7b and miR-638. Univariate analysis demonstrated that enhanced expression of miR-19b and miR-194 at the liver invasion front, and decreased expression of let-7 at the tumor invasion front, is an adverse prognostic marker of tumor recurrence and overall survival. In conclusion, the present study suggests that invasion front-specific downregulation of miRNA in colorectal liver metastases plays a pivotal role in tumor progression.