A simple immunohistochemical algorithm predicts the risk of distant metastases in right-sided colon cancer

Olfactomedin 4 associates with expression of differentiation markers but not with properties of cancer stemness, EMT nor metastatic spread in colorectal cancer

Tumor stem cells play a pivotal role in carcinogenesis and metastatic spread in colorectal cancer (CRC). Olfactomedin 4 (OLFM4) is co-expressed with the established stem cell marker leucine-rich repeat-containing G protein-coupled receptor 5 at the bottom of intestinal crypts and has been suggested as a surrogate for cancer stemness and a biomarker in gastrointestinal tumors associated with prognosis. Therefore, it was the aim of the present study to clarify whether OLFM4 is involved in carcinogenesis and metastatic spread in CRC. We used a combined approach of functional assays using forced OLFM4 overexpression in human CRC cell lines, xenograft mice, and an immunohistochemical approach using patient tissues to investigate the impact of OLFM4 on stemness, canonical Wnt signaling, properties of metastasis and differentiation as well as prognosis. OLFM4 expression correlated weakly with tumor grade in one patient cohort (metastasis collection: p = 0.05; pooled analysis of metastasis collection and survival collection: p = 0.19) and paralleled the expression of differentiation markers (FABP2, MUC2, and CK20) (p = 0.002) but did not correlate with stemness-associated markers. Further analyses in CRC cells lines as well as xenograft mice including forced overexpression of OLFM4 revealed that OLFM4 neither altered the expression of markers of stemness nor epithelial-mesenchymal transition, nor did OLFM4 itself drive proliferation, migration, or colony formation, which are all prerequisites of carcinogenesis and tumor progression. In line with this, we found no significant correlation between OLFM4 expression, metastasis, and patient survival. In summary, expression of OLFM4 in human CRC seems to be characteristic of differentiation marker expression in CRC but is not a driver of carcinogenesis nor metastatic spread.

LIN28 promotes tumorigenesis in colorectal cancer but is not associated with metastatic spread

BACKGROUND

Tumor stem cells play a role in metastatic spread in colorectal cancer (CRC). The oncogene LIN28A/B, a prognostic marker in CRC, is involved in tumorigenesis and maintains stem cell function. Therefore, it was the aim of the present study to clarify whether LIN28A/B is involved in metastatic spread in CRC.

METHODS

Expression of LIN28A/B was analyzed in patients with colon adenocarcinoma in a matched case-control study comparing patients with corresponding liver metastases (n = 42) and patients without hepatic spread within five years (n = 42) by applying immunohistochemistry. Further, LIN28A/B expression was correlated with stem cell associated markers (SOX2, CD133).

RESULTS

LIN28A and B expression significantly correlated with SOX2 expression (p = .02, and p = .04 respectively) but not with CD133 expression. This correlation between LIN28 A/B and SOX2 was not reflected in differences in hepatic spread. In this respect, there was no significant association between LIN28A/B expression and liver metastases.

CONCLUSION

LIN28A/B might be involved in tumor initiation and progression in CRC but is not associated with hepatic spread.

The prognostic value of combining CD133 and mismatch repair proteins in patients with colorectal cancer

The prognostic value of cancer stem cells (CSCs) is a hot topic in colorectal carcinoma (CRC) research. CD133 has been identified as an important colorectal CSC marker, but its prognostic significance remains controversial. Recently, studies have reported a possible functional link between CSCs and DNA mismatch repair (MMR) system. However, the relationship between CRC stemness and MMR proteins remains little explored, and whether the predictive role of CD133 is affected by MMR proteins is still unknown. The aim of our study is to investigate the influence of MMR proteins on the predictive significance of CD133 in terms of CRC patient survival and to further analyze the correlation between MMR proteins and cancer stemness. In our study, we didn't observe the prognostic value of CD133 in CRC patients. However, we demonstrated that in patients with low expression of MSH6, MSH2, PMS2 and MLH1, especially MSH6, CD133 was an effective prognostic biomarker. Moreover, correlation analysis revealed a positive correlation between MSH6 and CD133 expression. In vitro studies supported our clinical data and showed that the expression of cancer-associated stemness markers CD133, BMI-1, OCT-4 and SOX-2 was significantly decreased in siRNA-MSH6/MLH1 CRC cells. Thus, our results demonstrated that MMR proteins might play an important role in modulating the stemness of CRC cells. MMR proteins might be a crucial determinant that can help to accurately identify tumour subclones that may benefit from using the CSC marker CD133 as a prognostic marker.

Biomarker alterations associated with distinct patterns of metastatic spread in colorectal cancer

Metastatic spread is the most important life-threatening feature of colorectal cancer and is supposed to be mainly driven by alterations in different carcinogenic pathways. The present study compared mutation and expression profiles of distinctive biomarkers in colorectal cancer patients with different clinical metastatic patterns. As for a case-control study, patients were matched according to T category, grading and primary tumour site. Overall, 246 patients with either exclusive lung metastasis (N = 82), exclusive liver metastasis (N = 82) or non-metastatic colorectal cancer (N = 82) were identified. Paraffin-embedded specimens were examined for mutations in the RAS and RAF genes and for the expression of β-catenin and CD133. Clinical endpoints were presence or absence of distant metastasis, formation of metastasis in lungs versus the liver and survival. MAPK pathway mutations in either the KRAS, NRAS or BRAF gene were associated with the development of lung metastasis (63.4%) compared to the control group (47.6%; p = 0.04). MAPK pathway alterations plus high β-catenin expression were associated with metastasis to the lungs but not to the liver (28.0% vs. 13.4%; p = 0.02). High CD133 expression correlated with the development of liver metastasis compared to the control group (30.5% vs. 14.6%; p = 0.02). This data indicates that different patterns of distant spread are associated with specific biomarker alterations and may represent different molecular subtypes of colorectal cancer. However, underlying mechanisms of metastasis formation in different anatomic sites remains unclear. Since knowledge of the anticipated site of distant spread would substantially impact clinical management, further research is needed to identify solid biomarkers for different metastatic patterns.

DNA mismatch repair and CD133-marked cancer stem cells in colorectal carcinoma

Background

Except for a few studies with contradictory observations, information is lacking on the possibility of association between DNA mismatch repair (MMR) status and the presence of cancer stem cells in colorectal carcinoma (CRC), two important aspects in colorectal carcinogenesis.

Methods

Eighty (40 right-sided and 40 left-sided) formalin-fixed, paraffin-embedded primary CRC were immunohistochemically studied for CD133, a putative CRC stem cell marker, and MMR proteins MLH1, MSH2, MSH6 and PMS2. CD133 expression was semi-quantitated for proportion of tumor immunopositivity on a scale of 0-5 and staining intensity on a scale of 0-3 with a final score (units) being the product of proportion and intensity of tumor staining. The tumor was considered immunopositive only when the tumor demonstrated moderate to strong intensity of CD133 staining (a decision made after analysis of CD133 expression in normal colon). Deficient MMR (dMMR) was interpreted as unequivocal loss of tumor nuclear staining for any MMR protein despite immunoreactivity in the internal positive controls.

Results

CD133 was expressed in 36 (90.0%) left-sided and 28 (70.0%) right-sided tumors (p < 0.05) and CD133 score was significantly higher in left- (mean ± SD = 9.6 ± 5.3 units) compared with right-sided tumors (mean ± SD = 6.8 ± 5.6 units) p < 0.05). dMMR was noted in 14 (35%) right-sided and no (0%) left-sided CRC. When stratified according to MMR status, dMMR cases showed a lower frequency of CD133 expression (42.9%) and CD133 score (mean ± SD = 2.5 ± 3.6 units) compared with pMMR tumors on the right (frequency = 84.6%; mean score ± SD = 9.2 ± 5.0 units) as well as pMMR tumors on the left (frequency = 90.0%; mean score ± SD = 9.6 ± 5.3 units) (p < 0.05). Interestingly, frequencies of CD133 immunoreactivity and CD133 scores did not differ between pMMR CRC on the right versus the left (p > 0.05).

Conclusion

Proficient MMR correlated with high levels of CD133-marked putative cancer stem cells in both right- and left-sided tumors, whereas significantly lower levels of CD133-marked putative cancer stem cells were associated with deficient MMR status in colorectal carcinomas found on the right.

Association of differential miRNA expression with hepatic vs. peritoneal metastatic spread in colorectal cancer

BACKGROUND

Though peritoneal carcinomatosis reflects a late stage of colorectal cancer (CRC), only few patients present with synchronous or metachronous liver metastases alongside their peritoneal carcinomatosis. It is hypothesized that this phenomenon may be causally linked to molecular characteristics of the primary CRC. This study used miRNA profiling of primary CRC tissue either metastasized to the liver, to the peritoneum or not metastasized at all thus to identify miRNAs potentially associated with defining the site of metastatic spread in CRC.

METHODS

Tissue of the primary tumor stemming from CRC patients diagnosed for either liver metastasis (LM; n = 10) or peritoneal carcinomatosis (PER; n = 10) was analyzed in this study. Advanced CRC cases without metastasis (M0; n = 3) were also included thus to select on those miRNAs most potentially associated with determining metastatic spread in general. miRNA profiling of 754 different miRNAs was performed in each group. MiRNAs being either differentially expressed comparing PER and LM or even triple differentially expressed (PER vs. LM vs. M0) were identified. Differentially expressed miRNAs were further validated by in silico and functional analysis.

RESULTS

Comparative analysis identified 41 miRNAs to be differentially expressed comparing primary tumors metastasized to the liver as opposed to those spread to the peritoneum. A set of 31 miRNAs was significantly induced in primary tumors that spread to the peritoneum (PER), while the remaining 10 miRNAs were found to be repressed. Out of these 41 miRNAs a number of 25 miRNAs was triple-differentially expressed (i.e. differentially expressed comparing LM vs. PER vs. M0). The latter underwent in silico analysis. Finally, we demonstrated that miR-31 down-regulated c-MET in DLD-1 colon cancer cells.

CONCLUSIONS

This study demonstrates that CRC primary tumors spread to the peritoneum vs. metastasized to the liver display significantly different miRNA profiles. Larger patient cohorts will be needed to validate whether determination of e.g. miR-31 may aid to predict the course of disease and whether this may help to create individualized follow up or treatment protocols. To determine whether certain miRNAs may be involved in regulating the metastatic potential of CRC, functional studies will be essential.

Use of Multicenter Data in a Large Cancer Registry for Evaluation of Outcome and Implementation of Novel Concepts

Large clinical cancer registries (CCRs) in Germany shall be strengthened by the German Social Code Book V (SGB V) and implemented until the end of 2017. There are currently several large cancer registries that support clinical data for outcome analysis and knowledge acquisition. The various examples of the Munich Cancer Registry outlined in this paper present many-sided possibilities using and analyzing registry data. The main objective of population-based cancer registration within a defined area and the performance of outcomes research is to provide feedback regarding the results to the broad public, the reporting doctors, and the scientific community. These tasks determine principles of operation and data usage by CCRs. Each clinical department delivers its own findings and applied therapy. The compilation of these data in CCRs provides information on patient progress through the regional network of medical care and delivers meaningful information on the course of oncological diseases. Successful implementation of CCRs allows for presenting the statistical outcomes of health-care delivery, improving the quality of care within the region, accelerating the process of implementing innovative therapies, and generating new hypotheses as a stimulus for research activities.

Cancer Stem Cell Markers Are Associated With Distant Hematogenous Liver Metastases But Not With Peritoneal Carcinomatosis in Colorectal Cancer

Although peritoneal carcinomatosis (PC) displays advanced stage in colorectal cancer (CRC), most patients present without distant metastases. To analyze the expression of cancer stem cell markers immunohistochemistry for CD133, CD44 and β-catenin was applied to CRC with exclusive PC, exclusive hepatic metastasis and CRC with combined spread. Expression of cancer stem cell markers correlated with hematogeneous metastases to the liver and was absent in patients with exclusive PC. Thus, expression of cancer stem cell markers correlates with different patterns of metastatic spread in CRC. These data indicate that CRC with exclusive PC lack stem cell features needed for distant dissemination.

Expression of cancer stem cell markers in metastatic colorectal cancer correlates with liver metastasis, but not with metastasis to the central nervous system

INTRODUCTION

In colorectal cancer (CRC), metastatic spread is supposed to be mainly driven by tumor cells with stem cell features. Only about 1% of all CRC patients develop metastasis to the central nervous system (CNS). The present study intended to analyze the correlation between the expression of cancer stem cell markers and patterns of liver or CNS metastases.

MATERIAL AND METHODS

Immunohistochemistry for β-catenin, CD133, CD44 and the mismatch-repair markers hMLH1 and hMSH2 was applied to primary specimen of two CRC cohorts with CNS (n=29) and exclusive liver metastasis (n=36). Furthermore, mutation analysis for KRAS exon 2 and BRAF exon 15 was performed.

RESULTS

The expression of nuclear β-catenin, CD44 and CD133 was associated with the development of liver metastasis, but not of CNS metastasis. CD133 expression was absent in CRC with solitary CNS metastasis. Combination of cancer stem cell markers revealed high discriminatory power for the prediction of different patterns of distant spread. KRAS mutation was more frequently detected in patients with CNS metastasis, but the mutational status of KRAS and BRAF failed to show correlation with clinico-pathological data or the results of immunohistochemistry.

CONCLUSIONS

This study demonstrates that deregulation of Wnt/β-catenin-signaling and high-grade expression of cancer stem cell markers correlate with metastasis to the liver, but not to the CNS. These data implicate that in CRC other mechanisms than deregulation of Wnt/β-catenin-signaling and acquisition of cancer stemness are required for formation of CNS metastasis.

WNT signaling and distant metastasis in colon cancer through transcriptional activity of nuclear β-Catenin depend on active PI3K signaling

We determined whether active PI3K signaling together with nuclear accumulation of β-Catenin is necessary to fully activate canonical WNT signaling and examined the association of both signaling pathways with colon cancer progression. Using reporter gene assays we examined the activation of β-Catenin mediated transcription upon PI3K inhibition with or without β-Catenin nuclear accumulation. Ectopically induced as well as constitutively active WNT signaling strictly required PI3K activity whereas PI3K inhibition had no effect on β-Catenin subcellular localization but impaired β-Catenin binding to WNT target gene promoters and decreased WNT target gene expression. Transcriptional activity of nuclear β-Catenin depended on active PI3K signaling as nuclear accumulation of β-Catenin failed to induce WNT reporter gene transcription upon PI3K inhibition. PI3K dependend transcriptional transactivation of β-Catenin relies on events beyond phosphorylation at the AKT target site serine 552, as S552D-phosphomimetic β-Catenin mutants were unable to restore WNT signaling when inhibiting PI3K. To study the prognostic value of PI3K pathway activation (activating PIK3CA mutations or loss of PTEN expression) and nuclear β-Catenin expression, both variables were determined in 55 matched pairs of primary right sided colon cancer cases with or without distant metastasis. Activating mutations in the PIK3CA gene or loss of PTEN expression did not correlate with distant metastasis while high nuclear β-Catenin expression combined with activation of the PI3K pathway identified cases in which distant metastasis had occurred. Activation of the PI3K pathway was not associated with nuclear β-Catenin expression. We conclude that the transcriptional activity of nuclear β-Catenin depends on PI3K activity. However, PI3K on its own does not affect β-Catenin subcellular localization. Both factors synergize for full WNT signaling activity and are associated with distant metastasis in colon cancer. Thus, the detection of high nuclear β-Catenin expression and simultaneous PI3K pathway activation identifies colon cancer patients with a high risk for distant metastasis.

Targeting cancer stem cells with an 131I-labeled anti-AC133 monoclonal antibody in human colorectal cancer xenografts

INTRODUCTION

Cancer stem cells (CSCs) are a subpopulation within a tumor, which possesses the characteristics of self-renewal, differentiation, tumorigenicity, and drug resistance. The aim of this study was to target the colorectal CSC marker CD133 with an(131)I-labeled specific monoclonal antibody (AC133 mAb) in a nude mouse xenograft model.

METHODS

Colorectal adenocarcinoma cells (LoVo cell line) were separated into CD133(+) and CD133(-) cells by magnetic activated cell sorting. CD133(+), CD133(-), and unsorted LoVo cells were cultured and then implanted subcutaneously into the lower limbs of nude mice (n = 5). AC133 mAb was labeled with (131)I by the iodogen method.

RESULTS

The radiolabeled compound, (131)I-AC133 mAb, showed high stability, specificity, and immunoactivity in vitro. Obvious accumulation of (131)I-AC133 mAb was seen in nude mice bearing xenografts of CD133(+) and unsorted LoVo cells, but no uptake was found in mice bearing CD133(-) xenografts or specifically blocked xenografts. Biodistribution analysis showed that the tumor uptake of (131)I-AC133 mAb was 6.97 ± 1.40, 1.35 ± 0.48, 6.12 ± 1.91, and 1.61 ± 0.44% ID/g (n = 4) at day 7 after injection of (131)I-AC133 mAb in CD133(+), CD133(-), unsorted LoVo cell and specifically blocked xenografts, respectively. The results of immunofluorescence, autoradiography, and western blotting further verified the specific binding of (131)I-AC133 mAb to CD133(+) tumors.

CONCLUSIONS

This study demonstrates the possibility of targeting CSCs with a radiolabeled AC133 mAb in colorectal cancer xenografts based on in vitro, ex vivo, and in vivo experiments. Our findings suggest a new method for imaging CSCs non-invasively.

Loss of vinculin and membrane-bound β-catenin promotes metastasis and predicts poor prognosis in colorectal cancer

Background

Loss of cell-cell adhesion is important for the development of cancer invasion and metastasis. Vinculin, a key adhesion-related protein, can affect metastasis and prognosis in several tumours. Here, we determined the biological roles of vinculin in the metastasis of colorectal cancer (CRC) and evaluated its clinical significance as a potential disease biomarker.

Methods

The expression level of vinculin in CRC cell lines and tissues was measured using Real-Time PCR and western blotting. Moreover, vinculin function was analysed using Transwell assays and in vivo metastasis assays in gain- and loss-of-function experiments. Furthermore, the impact of vinculin together with membrane-bound β-catenin on the prognosis of 228 CRC patients was investigated by immunohistochemistry. Additionally, the expression of epithelial-mesenchymal transition (EMT) indicators was verified by immunohistochemistry in CRC tissues obtained from these patients.

Result

Vinculin expression was found to be significantly downregulated in highly metastatic CRC cell lines and metastatic tissues. Both in vitro and in vivo experiments showed that vinculin suppressed invasion, migration and metastasis in CRC cells and that this suppression could be attenuated by silencing β-catenin. Moreover, the expression of vinculin and membrane-bound β-catenin were positively correlated in CRC tissues, and lack of vinculin expression emerged as an independent prognostic factor in patients with CRC. Finally, the loss of vinculin and membrane-bound β-catenin was associated with node metastasis, organ metastasis and expression of EMT indicators.

Conclusion

Our results suggest that vinculin may play specific roles in the EMT and metastasis of CRC and that loss of vinculin could be used as a prognostic factor for CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-263) contains supplementary material, which is available to authorized users.

Molecular markers in colorectal cancer: clinical relevance in stage II colon cancer

SUMMARY Colorectal cancer is the second most common cause of cancer death in developed countries. Adjuvant chemotherapy is standard for stage III colorectal cancer but its use in stage II is controversial. Several clinicopathological factors have been described to define a high-risk group among stage II colon cancers, which can aid the selection of patients who may benefit from chemotherapy. Local tumor invasion (T4), high histological grade, obstruction and perforation at diagnosis, and number of lymph nodes removed are the most widely accepted factors. Several molecular factors have been also investigated as prognostic candidate biomarkers. DNA ploidy, KRAS and TP53 mutations, thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, loss of heterozygosity on chromosome 18q and microsatellite instability have been widely investigated. The aim of this review is to analyze the current evidence and clinical applications of the classical molecular biomarkers as well as new ones such as BRAF, circulating tumor cells, genome expression signatures and DNA methylation.

CD133: A cancer stem cells marker, is used in colorectal cancers

Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Cancer stem cells are characterized by their proliferation, tumorigenesis, differentiation, and self-renewal capacities, and chemoradiotherapy resistance. Due to the role of cancer stem cells in tumor initiation and treatment failure, studies of cancer stem cell markers, such as CD133, have been of great interest. CD133, a five-transmembrane glycoprotein, is widely used as a marker to identify and isolate colorectal cancer stem cells. This marker has been investigated to better understand the characteristics and functions of cancer stem cells. Moreover, it can also be used to predict tumor progression, patient survival, chemoradiotherapy resistance and other clinical parameters. In this review, we discuss the use of CD133 in the identification of colorectal cancer stem cell, which is currently controversial. Although the function of CD133 is as yet unclear, we have discussed several possible functions and associated mechanisms that may partially explain the role of CD133 in colorectal cancers. In addition, we focus on the prognostic value of CD133 in colorectal cancers. Finally, we predict that CD133 may be used as a possible target for colorectal cancer treatment.

Detection of miR-34a promoter methylation in combination with elevated expression of c-Met and β-catenin predicts distant metastasis of colon cancer

PURPOSE

Here, we determined whether epigenetic inactivation of miR-34a and miR-34b/c genes may serve as a prognostic marker for distant metastases in colon cancer.

EXPERIMENTAL DESIGN

Using a case-control study design of 94 primary colon cancer samples with and without liver metastases, we determined CpG methylation frequencies of miR-34a and miR-34b/c promoters, expression of miR-34a, and its targets c-Met, Snail, and β-catenin and their prognostic value.

RESULTS

miR-34a methylation was detected in 45.1% (n = 42 of 93) of the samples and strongly associated with metastases to the liver (P = 0.003) and lymph nodes (P = 0.006). miR-34b/c methylation was detected in 91.9% of the samples (n = 79/86). A significant inverse correlation between miR-34a methylation and expression of mature miR-34a (P = 0.018) was detected. Decreased miR-34a expression was associated with upregulation of c-Met, Snail, and β-catenin protein levels (P = 0.031, 0.132, and 0.004), which were associated with distant metastases (P = 0.001, 0.017, and 0.005). In a confounder-adjusted multivariate regression model miR-34a methylation, high c-Met and β-catenin levels provided the most significant prognostic information about metastases to the liver (P = 0.014, 0.031, and 0.058) and matched pairs showed a higher prevalence of these risk factors in the samples with distant spread (P = 0.029). Finally, we obtained statistical evidence indicating that the simultaneous detection of these three markers has the highest prognostic value.

CONCLUSIONS

Silencing of miR-34a and upregulation of c-Met, Snail, and β-catenin expression is associated with liver metastases of colon cancer. Detection of miR-34a silencing in resected primary colon cancer may be of prognostic value, especially in combination with detection of c-Met and β-catenin expression.

Novel biomarkers for the prediction of metastasis in colorectal cancer

INTRODUCTION

In patients with metastatic colorectal cancers, multimodal management and the use of biological agents such as monoclonal antibodies have had major positive effects on survival. The ability to predict which patients may be at 'high risk' of distant metastasis could have major implications on patient management. Histomorphological, immunohistochemical or molecular biomarkers are currently being investigated in order to test their potential value as predictors of metastasis.

AREAS COVERED

Here, the author reviews the clinical and functional data supporting the investigation of three novel promising biomarkers for the prediction of metastasis in patients with colorectal cancer: tumor budding, Raf1 kinase inhibitor protein (RKIP) and metastasis-associated in colon cancer-1 (MACC1).

EXPERT OPINION

The lifespan of most potential biomarkers is short as evidenced by the rare cases that have successfully made their way into daily practice such as KRAS or microsatellite instability (MSI) status. Although the three biomarkers reviewed herein have the potential to become important predictive biomarkers of metastasis, they have similar hurdles to overcome before they can be implemented into clinical management: standardization and validation in prospective patient cohorts.

Differential expression of CD133 based on microsatellite instability status in human colorectal cancer

The association between the types of genomic instability and cancer stem cell (CSC) has not been elucidated. We aimed to investigate the expressions of CSC markers with respect to microsatellite instability (MSI) status in human colorectal cancer (CRC). Immunostainings for CD133, CD44, and CD166, and K-ras mutation analysis were performed on 50 MSI-high (MSI-H), and 50 microsatellite stable (MSS) CRC tissues. In 11 MSS and MSI-H CRC cell lines, CD133 expression and DNA methylation statuses of the CD133 promoter were determined. The proportion of CD133 positive cells and the ability of colosphere formation were compared between HCT116 cells and HCT116 + Chr3 cells (hMLH1-restored HCT116 cells). Immunohistochemistry for CSC markers revealed that high CD133 expression was more frequent in MSS cancers than in MSI-H (P < 0.001, 74.0% vs. 28.0%, respectively), and related with short disease-free survival. Neither CD44 nor CD166 expression differed significantly with respect to MSI status. K-ras mutation showed no association with expressions of CD133, CD44, or CD166. CD133 expression was relatively high in the MSS cell lines compared to those in MSI-H, and showed a reverse correlation with DNA methylation of the CD133 promoter. hMLH1-restored HCT116 cells increased proportions of CD133 positive cells and colosphere forming ability, compared to those in HCT116 cells. In conclusion, high levels of CD133 expression were observed more frequently in MSS CRC than in MSI-H, suggesting that differential expression of colon CSC markers may be linked to tumor characteristics dependent on MSI status.

[Prognostic marker profiles for risk of distant metastases in colorectal cancer]

In colorectal cancer (CRC) prognostic markers correlating with distant metastasis are of high clinical value. In recent years it could be demonstrated that sporadic CRC with microsatellite instability (MSI) exhibits a very low risk for distant spread. Within this group the medullary subtype represents a morphological prototype. In the new WHO classification other morphological variants, such as mucinous, signet ring cell, serrated, cribriform comedo type and solid-undifferentiated forms are graded according to their microsatellite status. The clinical value of BRAF mutations is also dependent on the microsatellite status. Recent data have shown an ambivalent prognostic impact of BRAF mutations. A BRAF mutation in combination with MSI is associated with a good prognosis, whereas a BRAF mutation in the background of microsatellite stability (MSS) indicates a very poor outcome. Based on the concept of migrating stem cells, combined high scores of CD133 and nuclear β-catenin expression can be additionally used as markers for a high risk of distant metastasis. Hence, an immunohistochemical algorithm can be defined by the combination of three markers (hMLH1, CD133 and β-catenin) which allows CRC with either a very high or a very low risk of distant spread to be identified.