Gene expression profiles of different clinical stages of colorectal carcinoma: toward a molecular genetic understanding of tumor progression

Primary Colorectal Tumor Displays Differential Genomic Expression Profiles Associated with Hepatic and Peritoneal Metastases

BACKGROUND

Despite improvements in characterization of CRC heterogeneity, appropriate risk stratification tools are still lacking in clinical practice. This study aimed to elucidate the primary tumor transcriptomic signatures associated with distinct metastatic routes.

METHODS

Primary tumor specimens obtained from CRC patients with either isolated LM (CRC-Liver) or PM (CRC-Peritoneum) were analyzed by transcriptomic mRNA sequencing, gene set enrichment analyses (GSEA) and immunohistochemistry. We further assessed the clinico-pathological associations and prognostic value of our signature in the COAD-TCGA independent cohort.

RESULTS

We identified a significantly different distribution of Consensus Molecular Subtypes between CRC-Liver and CRC-peritoneum groups. A transcriptomic signature based on 61 genes discriminated between liver and peritoneal metastatic routes. GSEA showed a higher expression of immune response and epithelial invasion pathways in CRC-Peritoneum samples and activation of proliferation and metabolic pathways in CRC-Liver samples. The biological relevance of RNA-Seq results was validated by the immunohistochemical expression of three significantly differentially expressed genes (ACE2, CLDN18 and DUSP4) in our signature. In silico analysis of the COAD-TCGA showed that the CRC-Peritoneum signature was associated with negative prognostic factors and poor overall and disease-free survivals.

CONCLUSIONS

CRC primary tumors spreading to the liver and peritoneum display significantly different transcriptomic profiles. The implementation of this signature in clinical practice could contribute to identify new therapeutic targets for stage IV CRC and to define individualized follow-up programs in stage II-III CRC.

New insights into KLFs and SOXs in cancer pathogenesis, stemness, and therapy

Despite the development of cancer therapies, the success of most treatments has been impeded by drug resistance. The crucial role of tumor cell plasticity has emerged recently in cancer progression, cancer stemness and eventually drug resistance. Cell plasticity drives tumor cells to reversibly convert their cell identity, analogous to differentiation and dedifferentiation, to adapt to drug treatment. This phenotypical switch is driven by alteration of the transcriptome. Several pluripotent factors from the KLF and SOX families are closely associated with cancer pathogenesis and have been revealed to regulate tumor cell plasticity. In this review, we particularly summarize recent studies about KLF4, KLF5 and SOX factors in cancer development and evolution, focusing on their roles in cancer initiation, invasion, tumor hierarchy and heterogeneity, and lineage plasticity. In addition, we discuss the various regulation of these transcription factors and related cutting-edge drug development approaches that could be used to drug "undruggable" transcription factors, such as PROTAC and PPI targeting, for targeted cancer therapy. Advanced knowledge could pave the way for the development of novel drugs that target transcriptional regulation and could improve the outcome of cancer therapy.

Investigation of the expression levels of CPEB4, APC, TRIP13, EIF2S3, EIF4A1, IFNg, PIK3CA and CTNNB1 genes in different stage colorectal tumors

Background/aim

The aim of the study is to assess expression levels of CPEB4, APC, TRIP13, EIF2S3, EIF4A1, IFNg, PIK3CA and CTNNB1 genes in tumors and peripheral bloods of colorectal cancer patients in stages I–IV.

Materials and methods

The mRNA levels of the genes were determined in tumor tissues and peripheral blood samples of 45 colorectal cancer patients and colon tissues and peripheral blood samples of 5 healthy individuals. Real-time polymerase chain reaction method was used for the analysis.

Results

The mRNA level of the CPEB4 gene was significantly downregulated in colorectal tumor tissues and was upregulated in the peripheral blood of colorectal cancer patients relative to the controls (P < 0.05). APC mRNA level was significantly downregulated in tissues and upregulated in the peripheral blood (P < 0.05). TRIP13 mRNA level was upregulated in peripheral blood and also significantly upregulated in colorectal tumor tissues (P < 0.05). EIF2S3 mRNA level was upregulated in tissues and also significantly upregulated in peripheral blood (P < 0.05). PIK3CA mRNA level was downregulated in tissues and upregulated in peripheral blood. EIF4A1 mRNA level was downregulated in tissues and significantly upregulated in peripheral blood (P < 0.05). CTNNB1 mRNA level was downregulated in tissues and upregulated in peripheral blood. IFNg mRNA level was upregulated in both colorectal cancer tumor tissues and peripheral blood.

Conclusion:

TRIP13 and CPEB4 mRNA up regulation in the peripheral blood of patients with colorectal cancer may be a potential target for early stage diagnosis. In addition to this evaluation, although there is not much study on EIF2S3 and EIF4A1 mRNA changes in cases with colorectal cancer, upregulation in peripheral blood draws attention in our study. These data will shed light on the new comprehensive studies.

Phosphoserine aminotransferase has conserved active site from microbes to higher eukaryotes with minor deviations

Serine is ubiquitously synthesized in all living organisms from the glycolysis intermediate 3-phosphoglycerate (PGA) by phosphoserine biosynthetic pathway, consisting of three different enzymes, namely: 3-phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Any functional defect or mutation in these enzymes may cause deliberating conditions, such as colon cancer progression and chemoresistance in humans. Phosphoserine aminotransferase (PSAT) is the second enzyme in this pathway that converts phosphohydroxypyruvate (PHP) to O-phospho-L-serine (OPLS). Humans encode two isoforms of this enzyme: PSAT1 and PSAT2. PSAT1 exists as a functional dimer, where each protomer has a large and a small domain; each large domain contains a Lys residue that covalently binds PLP. The PLP-binding site of human PSAT1 and most of its active site residues are highly conserved in all known PSAT structures except for Cys-80. Interestingly, Two PSAT structures from different organisms show halide binding near their active site. While the human PSAT1 shows a water molecule at this site with different interacting residues, suggesting the inability of halide binding in the human enzyme. Analysis of the human PSAT1 structure showed a big patch of positive charge around the active site, in contrast to the bacterial PSATs. Compared to human PSAT1, the PSAT2 isoform lacks 46 residues at its C-terminal tail. This tail region is present at the opening of the active site as observed in the other PSAT structures. Further structural work on human PSAT2 may reveal the functional importance of these 46 residues.

L-serine synthesis via the phosphorylated pathway in humans

L-serine is a nonessential amino acid in eukaryotic cells, used for protein synthesis and in producing phosphoglycerides, glycerides, sphingolipids, phosphatidylserine, and methylenetetrahydrofolate. Moreover, L-serine is the precursor of two relevant coagonists of NMDA receptors: glycine (through the enzyme serine hydroxymethyltransferase), which preferentially acts on extrasynaptic receptors and D-serine (through the enzyme serine racemase), dominant at synaptic receptors. The cytosolic "phosphorylated pathway" regulates de novo biosynthesis of L-serine, employing 3-phosphoglycerate generated by glycolysis and the enzymes 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase, and phosphoserine phosphatase (the latter representing the irreversible step). In the human brain, L-serine is primarily found in glial cells and is supplied to neurons for D-serine synthesis. Serine-deficient patients show severe neurological symptoms, including congenital microcephaly, psychomotor retardation, and intractable seizures, thus highlighting the relevance of de novo production of this amino acid in brain development and morphogenesis. Indeed, the phosphorylated pathway is strictly linked to cancer. Moreover, L-serine has been suggested as a ready-to-use treatment, as also recently proposed for Alzheimer's disease. Here, we present our current state of knowledge concerning the three mammalian enzymes of the phosphorylated pathway and known mutations related to pathological conditions: although the structure of these enzymes has been solved, how enzyme activity is regulated remains largely unknown. We believe that an in-depth investigation of these enzymes is crucial to identify the molecular mechanisms involved in modulating concentrations of the serine enantiomers and for studying the interplay between glial and neuronal cells and also to determine the most suitable therapeutic approach for various diseases.

The transition from primary colorectal cancer to isolated peritoneal malignancy is associated with an increased tumour mutational burden

Colorectal Peritoneal metastases (CPM) develop in 15% of colorectal cancers. Cytoreductive surgery and heated intraperitoneal chemotherapy (CRS & HIPEC) is the current standard of care in selected patients with limited resectable CPM. Despite selection using known prognostic factors survival is varied and morbidity and mortality are relatively high. There is a need to improve patient selection and a paucity of research concerning the biology of isolated CPM. We aimed to determine the biology associated with transition from primary CRC to CPM and of patients with CPM not responding to treatment with CRS & HIPEC, to identify those suitable for treatment with CRS & HIPEC and to identify targets for existing repurposed or novel treatment strategies. A cohort of patients with CPM treated with CRS & HIPEC was recruited and divided according to prognosis. Molecular profiling of the transcriptome (n = 25), epigenome (n = 24) and genome (n = 21) of CPM and matched primary CRC was performed. CPM were characterised by frequent Wnt/ β catenin negative regulator mutations, TET2 mutations, mismatch repair mutations and high tumour mutational burden. Here we show the molecular features associated with CPM development and associated with not responding to CRS & HIPEC. Potential applications include improving patient selection for treatment with CRS & HIPEC and in future research into novel and personalised treatments targeting the molecular features identified here.

Positive expression of basic transcription factor 3 predicts poor survival of colorectal cancer patients: possible mechanisms involved

Basic transcription factor 3 (BTF3) is associated with the development of several cancers. The aim of our study was to elucidate the role of BTF3 in colorectal cancer (CRC) tissues. CRC tissues or their paired adjacent noncancerous (ANCT) tissues were obtained from 90 patients who underwent operations in our hospital from November 2011 to December 2016, and then we implemented a gene microarray assay for detecting significant changes in gene expression and confirmed expression in tissues using immunohistochemistry and real-time PCR. We transfected or injected the silencing BTF3 (BTF3-siRNA) plasmid into cells and nude mice, and measured the tumorigenicity of CRC cells with flow cytometry and studied the expression level of BTF3 downstream genes (MAD2L2, MCM3 and PLK1) in CRC cells. BTF3 expression level was not only significantly higher in CRC tissue than in ANCT tissue (2.61 ± 0.07 vs 1.90 ± 0.03, P < 0.001) but BTF3-siRNA decreased tumor formation in a nude mice model. Furthermore, based on the data of gene microarray analysis, MAD2L2, MCM3 and PLK1 were detected as the downstream target genes of BTF3 and their expressions were positive related with BTF3 expression. Also, through transfecting BTF3-siRNA into HCT116 cells, we found that BTF3-siRNA could decrease cell viability and induced cell apoptosis and blocking the cell cycle. In conclusion, BTF3 is positively related to CRC and BTF3-siRNA attenuated the tumorigenicity of colorectal cancer cells via MAD2L2, MCM3 and PLK1 activity reduction.

Identification of genes and pathways, including the CXCL2 axis, altered by DNA methylation in hepatocellular carcinoma

PURPOSE

Recent genetic studies have suggested that tumor suppressor genes are often silenced during carcinogenesis via epigenetic modification caused by methylation of promoter CpG islands. Here, we characterized genes inactivated by DNA methylation in human hepatocellular carcinoma (HCC) to identify the genes and pathways involved in DNA methylation in hepatocellular carcinoma.

METHODS

Eight HCC-derived cell lines were treated with a DNA demethylating agent, 5-aza-2'-deoxycytidine. Additionally, 100 pairs of primary HCC and adjacent non-cancerous tissues as well as 15 normal liver tissues were analyzed by comprehensive gene expression analysis using microarrays. Moreover, gene set enrichment analysis identified the major molecular pathways associated with DNA methylation. Validation of gene expression and DNA methylation status was performed by real-time PCR after bisulfite modification.

RESULTS

We showed that CXCL2, an immune-related chemokine, expression was significantly downregulated in tumor tissues and also significantly upregulated by DAC treatment in cell lines. Furthermore, we observed a statistically significant difference in methylation status between normal liver tissues and tumor tissues (P < 0.05). In addition, tumors with higher CXCL2 expression included significantly more numbers of multiple tumors than the lower expression group.

CONCLUSIONS

We identified CXCL2, an immune-related chemokine, decreased in hepatocellular carcinoma and the regulation mechanism may be controlled by methylation. Further studies should be warranted to examine if and to what extent the gene is actually suppressed by methylation and if there is a possibility that the CXCL2 axis plays a role for diagnosis and treatment of hepatocellular carcinoma.

Genetic and immunological biomarkers predict metastatic disease recurrence in stage III colon cancer

Background

Even though the post-operative outcome varies greatly among patients with nodal positive colon cancer (UICC stage III), personalized prediction of systemic disease recurrence is currently insufficient. We investigated in a retrospective setting whether genetic and immunological biomarkers can be applied for stratification of distant metastasis occurrence risk.

Methods

Eighty four patients with complete resection (R0) of stage III colon cancer from two clinical centres were analysed for genetic biomarkers: microsatellite instability, oncogenic mutations in KRAS exon2 and BRAF exon15, expression of osteopontin and the metastasis-associated genes SASH1 and MACC1. Tumor-infiltrating CD3 and CD8 positive T-cells were quantified by immunocytochemistry. Results were correlated with outcome and response to 5-FU based adjuvant chemotherapy, using Cox’s proportional hazard models and integrative two-step cluster analysis.

Results

Distant metastasis risk was significantly correlated with oncogenic KRAS mutations (p = 0.015), expression of SASH1 (p = 0.016), and the density of CD8-positive T-cells (p = 0.007) in Kaplan-Meier analysis. Upon multivariate Cox-regression analysis, KRAS mutation (p = 0.008) and density of CD8-positive TILs (p = 0.009) were retained as prognostic parameters for metachronous distant metastasis. Integrative two-step cluster analysis was used to combine all genetic markers, allowing stratification of patient subgroups. Post-operative distant metastasis risk ranged from 31% (low-risk) to 41% (intermediate), and 57% (high-risk) (p = 0.032). Increased expression of osteopontin (p = 0.019) and low density of CD8-positive T-cells (p = 0.043) were significantly associated with unfavourable response to 5-FU.

Conclusions

Integrative biomarker analysis allows stratification of stage III colon cancer patients for the risk of metastatic disease recurrence and may indicate response to 5-FU. Thus, biomarker analysis might facilitate the use of adjuvant therapy for high risk patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4940-2) contains supplementary material, which is available to authorized users.

Associations between novel genetic variants in the promoter region of MALAT1 and risk of colorectal cancer

The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a well-known long non-coding RNA, is involved in pathogenesis and progress of multiple tumors. However, no study has been performed to investigate the relationship between the genetic variants in promoter region of MALAT1 and colorectal cancer risk. In this study, we conducted a two-stage case-control study to evaluate whether MALAT1 genetic variants were associated with colorectal cancer risk. We identified that a single nucleotide polymorphism (SNP) rs1194338 was significantly associated with the decreased colorectal cancer risk with an odds ratio (OR) of 0.70 [95% confidence interval (CI) = 0.49-0.99] in the combined stage. The subsequently stratified analyses showed that the protective effect of rs1194338 was more pronounced in several subgroups. Furthermore, gene expression profiling analysis revealed overexpression of MALAT1 mRNA in colorectal cancer tissue compared with normal controls. Confirmation studies with large sample size and further mechanistic investigations into the function of MALAT1 and its genetic variants are warranted to advance our understanding of their roles in colorectal carcinogenesis, and to aid in the development of novel and targeted therapeutic strategies.

Interferon-inducible CXC-chemokines are crucial immune modulators and survival predictors in colorectal cancer

Tumor-infiltrating T-cells are strongly associated with prognosis in colorectal cancer, but the mechanisms governing intratumoral lymphocyte recruitment are unclear. We investigated the clinical relevance and functional contribution of interferon-regulated CXC-chemokines CXCL9, CXCL10, and CXCL11, described as T-cells attractants. Their expression was significantly elevated in tumors as compared to normal colon in 163 patients with colon cancer, represented an independent positive predictor of post-operative survival, and was highly significantly correlated with the presence of tumor-infiltrating cytotoxic CD8⁺ T-cells and CD4⁺ T_H1-effector cells. The regulation of chemokine expression was investigated in established cell lines and in tissue explants from resected tumor specimen (n=22). All colorectal cancer cell lines tested, as well as stroma or endothelial cells, produced CXC-chemokines in response to cytokine stimulation. Moreover, resected tumor explants could be stimulated to produce CXC-chemokines, even in cases with initially low CXC-levels. Lastly, a causative role of chemokine expression was evaluated with an orthotopic mouse model, based on isogenic rectal CT26 cancer cells, engineered to express CXCL10. The orthotopic model demonstrated a protective and anti-metastatic role of intratumoral CXCL10 expression, mediated mainly by adaptive immunity.

Association between genetic variants in the promoter region of a novel antisense long noncoding RNA RP11-392P7.6 and colorectal cancer risk

There is a widespread occurrence of antisense transcripts' regulation on cancer-related genes in cancer biology. RP11-392P7.6 is antisense to the coding region of cancer-related gene GPRC5D, which has been found recently. The aim of this study was to investigate the associations of tagSNPs in the promoter region of RP11-392P7.6 with the risk of colorectal cancer. We conducted a two-stage case-control study, with a discovery set (320 cases and 319 controls) and a validation set (501 cases and 538 controls). Four tagSNPs (rs1531970, rs1642199, rs4763903, and rs10845671) were selected based on 1000 Genomes Project data and genotyped by using the Sequenom MassARRAY genotyping platform. In the discovery set, three tagSNPs (rs1642199, rs4763903, and rs10845671) were revealed promising associations with the risk of colorectal cancer, among which the rs10845671 variants were further replicated in the validation set (OR = 1.47, 95% CI = 1.10-1.20 in heterozygote codominant model; OR = 1.38, 95% CI = 1.04-1.83 in dominant model). When combined the two sets, the above positive associations remained unchanged. Rs10845671 was found to be associated with an increased risk of colorectal cancer (OR = 1.43, 95% CI = 1.14-1.81 in heterozygote codominant model; OR = 1.35, 95% CI = 1.08-1.69 in dominant model). These findings indicate that rs10845671 may contribute to the susceptibility to colorectal cancer and be a candidate biomarker for colorectal cancer risk prediction. Environ. Mol. Mutagen. 58:434-442, 2017. © 2017 Wiley Periodicals, Inc.

Spindle Assembly Checkpoint as a Potential Target in Colorectal Cancer: Current Status and Future Perspectives

Colorectal cancer (CRC), one of the most common malignancies worldwide, is often diagnosed at an advanced stage, and resistance to chemotherapeutic and existing targeted therapy is a major obstacle to its successful treatment. New targets that offer alternative clinical options are therefore urgently needed. Recently, perturbation of the spindle assembly checkpoint (SAC), the surveillance mechanism that maintains anaphase inhibition until all chromosomes reach the metaphase plate, has been regarded as a promising target to fight cancer cells, either alone or in combination regimens. Consistent with this strategy, many cancers, including CRC, exhibit altered expression of SAC genes. In this article, we review our current knowledge on SAC activity status in CRC, and on current anti-CRC strategies and future therapeutic perspectives on the basis of SAC targeting experiments in vitro and in animal models.

Gene-expression analysis of a colorectal cancer-specific discriminatory transcript set on formalin-fixed, paraffin-embedded (FFPE) tissue samples

BACKGROUND

A recently published transcript set is suitable for gene expression-based discrimination of normal colonic and colorectal cancer (CRC) biopsy samples. Our aim was to test the discriminatory power of the CRC-specific transcript set on independent biopsies and on formalin-fixed, paraffin-embedded (FFPE) tissue samples.

METHODS

Total RNA isolations were performed with the automated MagNA Pure 96 Cellular RNA Large Volume Kit (Roche) from fresh frozen biopsies stored in RNALater (CRC (n = 15) and healthy colonic (n = 15)), furthermore from FFPE specimens including CRC (n = 15) and normal adjacent tissue (NAT) (n = 15) specimens next to the tumor. After quality and quantity measurements, gene expression analysis of a colorectal cancer-specific marker set with 11 genes (CA7, COL12A1, CXCL1, CXCL2, CHI3L1, GREM1, IL1B, IL1RN, IL8, MMP3, SLC5A7) was performed with array real-time PCR using Transcriptor First Strand cDNA Synthesis Kit (Roche) and RealTime ready assays on LightCycler480 System (Roche). In situ hybridization for two selected transcripts (CA7, CXCL1) was performed on NAT (n = 3), adenoma (n = 3) and CRC (n = 3) FFPE samples.

RESULTS

Although analytical parameters of automatically isolated RNA samples showed differences between fresh frozen biopsy and FFPE samples, both quantity and the quality enabled their application in gene expression analyses. CRC and normal fresh frozen biopsy samples could be distinguished with 93.3% sensitivity and 86.7% specificity and FFPE samples with 96.7 and 70.0%, respectively. In situ hybridization could confirm the upregulation of CXCL1 and downregulation of CA7 in colorectal adenomas and tumors compared to healthy controls.

CONCLUSION

According to our results, gene expression analysis of the analyzed colorectal cancer-specific marker set can also be performed from FFPE tissue material. With the addition of an automated workflow, this marker set may enhance the objective classification of colorectal neoplasias in the routine procedure in the future.

Identification of differential proteins in colorectal cancer cells treated with caffeic acid phenethyl ester

AIM: To investigate the molecular mechanisms of the anti-cancer activity of caffeic acid phenethyl ester (CAPE).

METHODS: Protein profiles of human colorectal cancer SW480 cells treated with or without CAPE were analysed using a two-dimensional (2D) electrophoresis gel-based proteomics approach. After electrophoresis, the gels were stained with Coomassie brilliant blue R-250. Digital images were taken with a GS-800 Calibrated Densitometer, and image analysis was performed using PDQuest 2-D Analysis software. The altered proteins following CAPE treatment were further identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry following a database search. The identified proteins were validated by Western blot and immunofluorescence assay.

RESULTS: CAPE induced human colorectal cancer cell apoptosis. Four up-regulated proteins and seven down-regulated proteins in colorectal cancer cells treated with CAPE were found. The identified down-regulated proteins in CAPE-treated colorectal cancer cells were Triosephosphate Isomerase (Tim), Proteasome subunit alpha 4 (PSMA4) protein, Guanine nucleotide binding protein beta, Phosphoserine aminotransferase 1 (PSAT1), PSMA1, Myosin XVIIIB and Tryptophanyl-tRNA synthetase. Notably, CAPE treatment led to the down-regulation of PSAT1 and PSMA1, two proteins that have been implicated in tumorigenesis. The identified up-regulated proteins were Annexin A4, glyceraldehyde-3-phosphate dehydrogenase, Glucosamine-6-phosphate deaminase 1 (GNPDA1), and Glutathione peroxidase (GPX-1). Based on high match scores and potential role in cell growth control, PSMA1, PSAT1, GNPDA1 and GPX-1 were further validated by Western blotting and immunofluorescence assay. PSMA1 and PSAT1 were down-regulated, while GNPDA1 and GPX-1 were up-regulated in CAPE-treated colorectal cancer cells.

CONCLUSION: These differentiated proteins in colorectal cancer cells following CAPE treatment, may be potential molecular targets of CAPE and involved in the anti-cancer effect of CAPE.

PSAT1 regulates cyclin D1 degradation and sustains proliferation of non-small cell lung cancer cells

Multiple nodes in the one-carbon metabolism pathway play important regulatory roles in cancer cell growth and tumorigenesis. The specific biological functions of metabolic enzymes in regulating the signaling pathways that are associated with tumor cell growth and survival, however, remain unclear. Our current study found that phosphoserine aminotransferase 1 (PSAT1), an enzyme catalyzing serine biosynthesis, was significantly up-regulated in non-small cell lung cancer (NSCLC) and was involved in the regulation of E2F activity. Loss- and gain-of-function experiments demonstrated that PSAT1 promoted cell cycle progression, cell proliferation and tumorigenesis. Mechanistic study suggested that elevated PSAT1 led to inhibition of cyclin D1 degradation and subsequently an alteration in Rb-E2F pathway activity, which in turn enhanced G1 progression and proliferation of NSCLC cells. Moreover, phosphorylation of cyclin D1 at threonine 286 by GSK-3β was required for PSAT1-induced blockage of cyclin D1 degradation. We also found that the activity of p70S6K mediated the effects of PSAT1 on GSK-3β phosphorylation and cyclin D1 degradation. We further identified that PSAT1 was over-expressed in NSCLC and predicted poor clinical outcome of patients with the disease. Correlation analysis showed that PSAT1 expression positively correlated with the levels of phosphorylated GSK-3β, cyclin D1 and phosphorylated Rb in NSCLC primary tumors. These findings uncover a mechanism for constitutive activation of E2F via which unrestrained cell cycle progression occurs in NSCLC and may represent a prognostic biomarker and therapeutic target.

Bifidobacterium bifidum PRL2010 modulates the host innate immune response

Here, we describe data obtained from transcriptome profiling of human cell lines and intestinal cells of a murine model upon exposure and colonization, respectively, with Bifidobacterium bifidum PRL2010. Significant changes were detected in the transcription of genes that are known to be involved in innate immunity. Furthermore, results from enzyme-linked immunosorbent assays (ELISAs) showed that exposure to B. bifidum PRL2010 causes enhanced production of interleukin 6 (IL-6) and IL-8 cytokines, presumably through NF-κB activation. The obtained global transcription profiles strongly suggest that Bifidobacterium bifidum PRL2010 modulates the innate immune response of the host.

Clinical applications of gene expression in colorectal cancer

BACKGROUND

Despite developments in diagnosis and treatment, 20% of colorectal cancer (CRC) patients present with metastatic disease and 30% of cases recur after curative surgery. Furthermore, the molecular factors involved in prognosis and response to therapy in CRC is poorly understood. The aims of this study were to quantitatively examine the expression of target genes in colorectal cancer and to correlate their expression levels with clinico-pathological variables.

METHODS

A detailed analysis of published CRC microarray data was performed to identify the most prominent genes. The selected genes were validated in fifty-two pairs of fresh colorectal tumour and associated normal tissue specimens by RQ-PCR using TaqMan(®) assays. Statistical analysis and correlation with clinicopathological data was performed using SPSS software.

RESULTS

Expression levels of CXCL12 (P=0.000), CDH17 (P=0.026), MUC2 (P=0.000), L-FABP (P=0.000) and PDCD4 (P=0.000) were down regulated and IL8 (P=0.000) was upregulated in tumours compared to normal colorectal tissues. No significant differences were noted in expression of CEACAM5, CXCR4, CXCR7, TGFB1, TGFBR1 and TGFBR2. Furthermore, we found significant associations of gene expression levels and clinicopathological variables such as tumour size, grade, invasion and lymph node status.

CONCLUSIONS

We identified a comprehensive list of genes with highly differential expression patterns in colorectal cancer that could serve as molecular markers to complement existing histopathological factors in diagnosis, follow up and therapeutic strategies for individualised care of patients.

Prediction in rectal cancer

The treatment of rectal cancer largely depends on disease stage at diagnosis, based on which patients can be classified as low, intermediate, or high risk. Prognostic and predictive markers, specific to each risk category, can be applied for optimal risk classification and subsequent treatment allocation. These markers are either histopathological, determined with imaging, or have a biomolecular background. This review provides an overview of the current status of treatment options and the use of prognostic and predictive markers in each risk category. An effort was made to identify those markers that are currently lacking in, but have the potential to improve, the clinical decision process by discussing the data from recent studies aimed at the development of new prognostic and predictive markers. At this moment, none of the markers studied has been proven to be of significant, independent value, justifying implementation in daily clinical practice. However, recent developments in imaging techniques and biomolecular research do show great potential.

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

AIMS

A test predicting distant metastases would be valuable for prognostication in colon cancer (CC). In previous studies, CC with microsatellite instability (MSI) showed a reduced risk of distant metastases. High expression of CD133 and β-catenin, both related to cancer stem cell phenotypes, might be predictive markers for metastasis. The aim of this study was to develop a simple and robust test for risk assessment of distant metastases in CC.

METHODS AND RESULTS

In a case-control study, 57 cases of right-sided CC specimens with synchronous distant metastases were matched with 57 CC without distant metastases. Immunohistochemistry for MLH1, CD133 and nuclear β-catenin was carried out. To define the diagnostic algorithm the tumours were first stratified according to their MLH1 expression. Loss of MLH1 expression was correlated significantly with a very low risk of distant metastases (5.3%; P = 0.00003). In MLH1-positive cases, combined high scores of CD133 and β-catenin were associated with a very high rate of distant metastases (94.4%), whereas the risk was intermediate for carcinomas with either low CD133 and/or low β-catenin expression (P = 0.0007). A validation study using an independent set of 68 right-sided CC specimens showed a clear trend towards risk stratification according to the algorithm; however, sample sizes were small, and associations were not statistically significant.

CONCLUSIONS

By the use of three markers, this algorithm allowed identification of subgroups of right-sided CC patients with extremely high and extremely low risk of distant metastases.

The causes and consequences of polyploidy in normal development and cancer

Although nearly all mammalian species are diploid, whole-genome duplications occur in select mammalian tissues as part of normal development. Such programmed polyploidization involves changes in the regulatory pathways that normally maintain the diploid state of the mammalian genome. Unscheduled whole-genome duplications, which lead primarily to tetraploid cells, also take place in a substantial fraction of human tumors and have been proposed to constitute an important step in the development of cancer aneuploidy. The origins of these polyploidization events and their consequences for tumor progression are explored in this review.

Prediction of metastasis and recurrence in colorectal cancer based on gene expression analysis: ready for the clinic?

Cancers of the colon and rectum, which rank among the most frequent human tumors, are currently treated by surgical resection in locally restricted tumor stages. However, disease recurrence and formation of local and distant metastasis frequently occur even in cases with successful curative resection of the primary tumor (R0). Recent technological advances in molecular diagnostic analysis have led to a wealth of knowledge about the changes in gene transcription in all stages of colorectal tumors. Differential gene expression, or transcriptome analysis, has been proposed by many groups to predict disease recurrence, clinical outcome, and also response to therapy, in addition to the well-established clinico-pathological factors. However, the clinical usability of gene expression profiling as a reliable and robust prognostic tool that allows evidence-based clinical decisions is currently under debate. In this review, we will discuss the most recent data on the prognostic significance and potential clinical application of genome wide expression analysis in colorectal cancer.

Comparative profiling of primary colorectal carcinomas and liver metastases identifies LEF1 as a prognostic biomarker

Purpose

We sought to identify genes of clinical significance to predict survival and the risk for colorectal liver metastasis (CLM), the most common site of metastasis from colorectal cancer (CRC).

Patients and Methods

We profiled gene expression in 31 specimens from primary CRC and 32 unmatched specimens of CLM, and performed Significance Analysis of Microarrays (SAM) to identify genes differentially expressed between these two groups. To characterize the clinical relevance of two highly-ranked differentially-expressed genes, we analyzed the expression of secreted phosphoprotein 1 (SPP1 or osteopontin) and lymphoid enhancer factor-1 (LEF1) by immunohistochemistry using a tissue microarray (TMA) representing an independent set of 154 patients with primary CRC.

Results

Supervised analysis using SAM identified 963 genes with significantly higher expression in CLM compared to primary CRC, with a false discovery rate of <0.5%. TMA analysis showed SPP1 and LEF1 protein overexpression in 60% and 44% of CRC cases, respectively. Subsequent occurrence of CLM was significantly correlated with the overexpression of LEF1 (chi-square p = 0.042), but not SPP1 (p = 0.14). Kaplan Meier analysis revealed significantly worse survival in patients with overexpression of LEF1 (p<0.01), but not SPP1 (p = 0.11). Both univariate and multivariate analyses identified stage (p<0.0001) and LEF1 overexpression (p<0.05) as important prognostic markers, but not tumor grade or SPP1.

Conclusion

Among genes differentially expressed between CLM and primary CRC, we demonstrate overexpression of LEF1 in primary CRC to be a prognostic factor for poor survival and increased risk for liver metastasis.

Mutated KRAS results in overexpression of DUSP4, a MAP-kinase phosphatase, and SMYD3, a histone methyltransferase, in rectal carcinomas

Mutations of the KRAS oncogene are predictive for resistance to treatment with antibodies against the epithelial growth factor receptor in patients with colorectal cancer. Overcoming this therapeutic dilemma could potentially be achieved by the introduction of drugs that inhibit signaling pathways that are activated by KRAS mutations. To identify comprehensively such signaling pathways, we profiled pretreatment biopsies and normal mucosa from 65 patients with locally advanced rectal cancer-30 of which carried mutated KRAS-using global gene expression microarrays. By comparing all tumor tissues exclusively to matched normal mucosa, we could improve assay sensitivity, and identified a total of 22,297 features that were differentially expressed (adjusted P-value <0.05) between normal mucosa and cancer, including several novel potential rectal cancer genes. We then used this comprehensive description of the rectal cancer transcriptome as the baseline for identifying KRAS-dependent alterations. The presence of activating KRAS mutations is significantly correlated to an upregulation of 13 genes (adjusted P-value <0.05), among them DUSP4, a MAP-kinase phosphatase, and SMYD3, a histone methyltransferase. Inhibition of the expression of both genes has previously been shown using the MEK1-inhibitor PD98059 and the antibacterial compound Novobiocin, respectively. These findings suggest a potential approach to overcome resistance to treatment with antibodies against the epithelial growth factor receptor in patients with KRAS-mutant rectal carcinomas.

Modeling oncogenic signaling in colon tumors by multidirectional analyses of microarray data directed for maximization of analytical reliability

Background

Clinical progression of colorectal cancers (CRC) may occur in parallel with distinctive signaling alterations. We designed multidirectional analyses integrating microarray-based data with biostatistics and bioinformatics to elucidate the signaling and metabolic alterations underlying CRC development in the adenoma-carcinoma sequence.

Methodology/Principal Findings

Studies were performed on normal mucosa, adenoma, and carcinoma samples obtained during surgery or colonoscopy. Collections of cryostat sections prepared from the tissue samples were evaluated by a pathologist to control the relative cell type content. The measurements were done using Affymetrix GeneChip HG-U133plus2, and probe set data was generated using two normalization algorithms: MAS5.0 and GCRMA with least-variant set (LVS). The data was evaluated using pair-wise comparisons and data decomposition into singular value decomposition (SVD) modes. The method selected for the functional analysis used the Kolmogorov-Smirnov test. Expressional profiles obtained in 105 samples of whole tissue sections were used to establish oncogenic signaling alterations in progression of CRC, while those representing 40 microdissected specimens were used to select differences in KEGG pathways between epithelium and mucosa. Based on a consensus of the results obtained by two normalization algorithms, and two probe set sorting criteria, we identified 14 and 17 KEGG signaling and metabolic pathways that are significantly altered between normal and tumor samples and between benign and malignant tumors, respectively. Several of them were also selected from the raw microarray data of 2 recently published studies (GSE4183 and GSE8671).

Conclusion/Significance

Although the proposed strategy is computationally complex and labor–intensive, it may reduce the number of false results.

Differential expression of the chemokines GRO-2, GRO-3, and interleukin-8 in colon cancer and their impact on metastatic disease and survival

BACKGROUND AND AIM

Chemotactic cytokines play a role in angiogenesis and attraction of immune cells. However, their contribution to tumor formation remains incompletely understood. In a previous transcriptome study, we identified a family of structurally related chemokines of the CXC-family to be specifically up-regulated in colorectal cancer. The aim of the present study was to investigate the regulation of their expression in colon cancer cells and to test the hypothesis that altered CXC-chemokine expression is related to critical clinical parameters, such as survival or metastasis formation.

MATERIALS AND METHODS

Expression levels of interleukin-8 (CXCL-8) and growth-related oncogenes 2 and 3 (GRO-2/CXCL-2 and GRO-3/CXCL-3) were quantified using qRT-PCR in 97 patients with completely resected colon carcinoma and correlated with clinical parameters. Moreover, 16 samples of normal mucosa, nine samples of benign adenoma, and 11 samples of liver metastasis were analyzed. Next, the regulation of chemokine expression in response to various stimuli was tested in colon cancer cell lines (HT29, HCT116, CaCO2).

RESULTS

Expression of GRO-2, GRO-3, and IL-8 was significantly increased in colon cancer as compared to normal colon tissue. Expression of GRO-2 and GRO-3 was already enhanced in premalignant adenomas, and GRO-3 was significantly down-regulated in liver metastasis as compared to the primary tumor. Importantly, expression of GRO-3 was significantly higher in patients with local versus systemic disease. Moreover, IL-8 expression was significantly associated to overall post-operative survival. Finally, all chemokines were strongly induced by IL-1alpha in the colon cancer cell lines tested, indicating a potential link to inflammatory processes.

CONCLUSION

In accordance with earlier findings, we report here a significantly increased expression of GRO-2, GRO-3, and IL-8 in colon carcinoma as compared to normal tissue. Furthermore, GRO-3 was related to metastasis formation, and IL-8 was associated with survival, suggesting a potential predictive power of these markers.

An expression module of WIPF1-coexpressed genes identifies patients with favorable prognosis in three tumor types

Wiskott–Aldrich syndrome (WAS) predisposes patients to leukemia and lymphoma. WAS is caused by mutations in the protein WASP which impair its interaction with the WIPF1 protein. Here, we aim to identify a module of WIPF1-coexpressed genes and to assess its use as a prognostic signature for colorectal cancer, glioma, and breast cancer patients. Two public colorectal cancer microarray data sets were used for discovery and validation of the WIPF1 co-expression module. Based on expression of the WIPF1 signature, we classified more than 400 additional tumors with microarray data from our own experiments or from publicly available data sets according to their WIPF1 signature expression. This allowed us to separate patient populations for colorectal cancers, breast cancers, and gliomas for which clinical characteristics like survival times and times to relapse were analyzed. Groups of colorectal cancer, breast cancer, and glioma patients with low expression of the WIPF1 co-expression module generally had a favorable prognosis. In addition, the majority of WIPF1 signature genes are individually correlated with disease outcome in different studies. Literature gene network analysis revealed that among WIPF1 co-expressed genes known direct transcriptional targets of c-myc, ESR1 and p53 are enriched. The mean expression profile of WIPF1 signature genes is correlated with the profile of a proliferation signature. The WIPF1 signature is the first microarray-based prognostic expression signature primarily developed for colorectal cancer that is instrumental in other tumor types: low expression of the WIPF1 module is associated with better prognosis.

Reduced lymph node yield in rectal carcinoma specimen after neoadjuvant radiochemotherapy has no prognostic relevance

BACKGROUND

In colorectal surgery UICC/AJCC criteria require a yield of 12 or more locoregional lymph nodes for adequate staging. Neoadjuvant radiochemotherapy for rectal carcinoma reduces the number of lymph nodes in the resection specimen; the prognostic impact of this reduced lymph node yield has not been determined.

METHODS

One hundred two patients with uT3 rectal carcinoma who were receiving neoadjuvant radiochemotherapy were compared with 114 patients with uT3 rectal carcinoma who were receiving primary surgery followed by adjuvant radiochemotherapy. Total lymph node yield and number of tumor-positive lymph nodes were determined and correlated with survival.

RESULTS

After neoadjuvant radiochemotherapy both total lymph node yield (12.9 vs. 21.4, p < 0.0001) and number of tumor-positive lymph nodes (1.0 vs. 2.3, p = 0.014) were significantly lower than after primary surgery plus adjuvant radiochemotherapy. Reduced total lymph node yield in neoadjuvantly treated patients had no prognostic impact, with overall survival of patients with 12 or more lymph nodes the same as that of patients with less than 12 lymph nodes. Overall survival of neoadjuvantly treated patients was significantly influenced by the number of tumor-positive lymph nodes with 5-year-survival rates of 88, 63, and 39% for 0, 1-3, and more than 3 positive lymph nodes (p < 0.0001).

CONCLUSION

The UICC/AJCC criterion of a total lymph node yield of 12 or more should be revised for rectal carcinoma patients.

The prometastatic microenvironment of the liver

The liver is a major metastasis-susceptible site and majority of patients with hepatic metastasis die from the disease in the absence of efficient treatments. The intrahepatic circulation and microvascular arrest of cancer cells trigger a local inflammatory reaction leading to cancer cell apoptosis and cytotoxicity via oxidative stress mediators (mainly nitric oxide and hydrogen peroxide) and hepatic natural killer cells. However, certain cancer cells that resist or even deactivate these anti-tumoral defense mechanisms still can adhere to endothelial cells of the hepatic microvasculature through proinflammatory cytokine-mediated mechanisms. During their temporary residence, some of these cancer cells ignore growth-inhibitory factors while respond to proliferation-stimulating factors released from tumor-activated hepatocytes and sinusoidal cells. This leads to avascular micrometastasis generation in periportal areas of hepatic lobules. Hepatocytes and myofibroblasts derived from portal tracts and activated hepatic stellate cells are next recruited into some of these avascular micrometastases. These create a private microenvironment that supports their development through the specific release of both proangiogenic factors and cancer cell invasion- and proliferation-stimulating factors. Moreover, both soluble factors from tumor-activated hepatocytes and myofibroblasts also contribute to the regulation of metastatic cancer cell genes. Therefore, the liver offers a prometastatic microenvironment to circulating cancer cells that supports metastasis development. The ability to resist anti-tumor hepatic defense and to take advantage of hepatic cell-derived factors are key phenotypic properties of liver-metastasizing cancer cells. Knowledge on hepatic metastasis regulation by microenvironment opens multiple opportunities for metastasis inhibition at both subclinical and advanced stages. In addition, together with metastasis-related gene profiles revealing the existence of liver metastasis potential in primary tumors, new biomarkers on the prometastatic microenvironment of the liver may be helpful for the individual assessment of hepatic metastasis risk in cancer patients.

Histopathological response after preoperative radiochemotherapy in rectal carcinoma is associated with improved overall survival

BACKGROUND

Recent studies showed improved local control after preoperative radiochemotherapy (RCTX) in patients with locally advanced rectal carcinoma, but failed to demonstrate a survival benefit. Our aims were to determine outcome and impact of histopathological response after preoperative RCTX.

METHODS

One hundred four patients with uT3 rectal carcinoma were treated with preoperative RCTX of 45 Gy and continuous 5-FU infusion between 1997 and 2001 (group I). Histopathological response was evaluated in all specimens after tumor resection. Group II consisted of 114 patients with uT3 rectal carcinoma treated with postoperative RCTX between 1988 and 1997.

RESULTS

Group I showed a 6.1% 5-year local recurrence rate compared to 15.3% in group II (P = 0.023). Overall survival rates did not differ significantly between both groups (P = 0.225). Histopathological responders had a significantly improved 5-year overall survival with 89.1 (7.8)% compared to 68.7 (6.7)% of the non-responders (P = 0.008) and were identified as an independent prognostic factor.

CONCLUSIONS

Significant improvement of overall survival was observed for histopathological tumor responders after neoadjuvant radiochemotherapy. Our protocol of preoperative radiochemotherapy confirms the results of the multi-center studies in regard to local control and overall survival.

Identification of gene signatures for invasive colorectal tumor cells

BACKGROUND

Gene signatures of sporadic colorectal carcinoma tissues and microdissected colorectal tumor cells were analyzed to identify stromal and tumor cell-specific markers, respectively.

METHODS

Serial sections of frozen colorectal tumors (n=29) were subjected to RNA isolation of (1) entire tissue sections with a various tumor cell content and of (2) microdissected invasive tumor cells. Three matching samples of microdissected normal colorectal epithelial and invasive tumor cells were similarly obtained. RNA samples were analyzed using the HG95A and HG95Av2 GeneChip microarrays (Affymetrix). The microarray data was evaluated by established methods and validated by Q-RT-PCR.

RESULTS

Unsupervised hierarchical cluster analysis of 18 sample pairs (training set) clearly distinguished tumors from microdissected tumor cells. A 149-gene signature was identified using statistical methods, which was then validated by a hierarchical clustering analysis of 11 independent sample pairs (test set). Genes specifically associated with microdissected invasive tumor cells were for example CKS2 and NME1. In contrast, genes associated with stromal cells were for example MMP2, SDF1 and FBLN2. Finally, a 65-gene signature distinguished normal colorectal epithelial cells and invasive tumor cells, including down-regulation of BMP2 and ANPEP mRNA expression as well as up-regulation of TKT, SPARC, MCM5 mRNA expression.

CONCLUSIONS

Our approach allowed precise evaluation of molecular signatures in morphologically defined cell populations and identified novel target genes related to stroma-tumor interactions in colorectal cancer. The approach enables further analysis of gene signatures in different tumor areas and cell types, such as within invasive margins to decipher molecular mechanisms of colorectal cancer invasion and metastasis.

Overexpression of phosphoserine aminotransferase PSAT1 stimulates cell growth and increases chemoresistance of colon cancer cells

BACKGROUND

Colorectal cancer (CRC) is one of the most common causes of cancer death throughout the world. In this work our aim was to study the role of the phosphoserine aminotransferase PSAT1 in colorectal cancer development.

RESULTS

We first observed that PSAT1 is overexpressed in colon tumors. In addition, we showed that after drug treatment, PSAT1 expression level in hepatic metastases increased in non responder and decreased in responder patients. In experiments using human cell lines, we showed that ectopic PSAT1 overexpression in colon carcinoma SW480 cell line resulted in an increase in its growth rate and survival. In addition, SW480-PSAT1 cells presented a higher tumorigenic potential than SW480 control cells in xenografted mice. Moreover, the SW480-PSAT1 cell line was more resistant to oxaliplatin treatment than the non-transfected SW480 cell line. This resistance resulted from a decrease in the apoptotic response and in the mitotic catastrophes induced by the drug treatment.

CONCLUSION

These results show that an enzyme playing a role in the L-serine biosynthesis could be implicated in colon cancer progression and chemoresistance and indicate that PSAT1 represents a new interesting target for CRC therapy.

Microarray-based prediction of tumor response to neoadjuvant radiochemotherapy of patients with locally advanced rectal cancer

BACKGROUND & AIMS

Neoadjuvant chemoradiotherapy has become a standard treatment of locally advanced rectal carcinomas, even though the responsiveness varies from complete response to resistance. The aim of the study was to evaluate the capacity of gene expression signatures to identify responders and nonresponders pretherapeutically.

METHODS

By using microarray technology we generated gene expression profiles of 43 biopsy specimens of locally advanced rectal carcinomas. The transcription profile then was compared with histopathologic response and used to identify a set of genes discriminating responders from nonresponders.

RESULTS

We identified a gene expression signature of 42 genes, mostly encoding proteins that either play a role in the nucleus, such as the transcription factor ETS2, or are associated with transport function, such as the solute carrier SLC35E1, or the regulation of apoptosis, such as caspase-1. In leave-one-out cross-validation the correct classification of a responder was 71%, the specificity of the analysis for a correct classification of a nonresponder was 86%. By applying an additional statistical method of 200 successive splittings into training and test data sets we generated an individual prediction accuracy measure for each predicted response.

CONCLUSIONS

Our study shows that pretherapeutic prediction of response of rectal carcinomas to neoadjuvant chemoradiotherapy is feasible, and may represent a new valuable and practical tool of therapeutic stratification.

Expression of osteopontin, a target gene of de-regulated Wnt signaling, predicts survival in colon cancer

Osteopontin (OPN) is a secreted phosphoprotein, which has been reported to be associated with tumor progression in numerous solid tumors. In a previous transcriptome study on colorectal cancer, we identified the gene OPN among the most strongly up-regulated transcripts. OPN has been suggested as a putative target of Wnt signaling, but the molecular mechanism responsible for its aberrant transcription is not fully understood. We analyzed 13 normal colon tissues, 9 adenomas, 120 primary colon tumors, and 10 liver metastases by quantitative reverse-transcription PCR. OPN expression was strongly elevated in primary colon cancer and liver metastasis, but not in pre-cancerous lesions and UICC stage I tumors. Multivariate analysis established OPN expression as an independent prognostic parameter for overall survival. Moreover, high OPN expression identified a subgroup of patients with bad prognosis. Next, we determined immunohistochemically a correlation of OPN expression with aberrant beta-catenin staining, which is indicative of Wnt activation. Elevated expression of OPN was significantly correlated with increased cytoplasmic and nuclear beta-catenin staining. The in vivo role of Wnt signaling for the expression of OPN was tested in genetically defined mouse models with (Apc(1638N)) or without (pvillin-KRAS(V12G)) Wnt activating mutations. Mutation of the tumor suppressor APC was necessary for upregulation of OPN expression in the murine tumors on transcript and on protein levels. Thus, OPN is a transcriptional target of aberrant Wnt signaling, and OPN expression alone predicts survival in human colon cancer.

Expression of ontogene C-erbB-2 and its correlations with invasion and metastasis in colorectal carcinoma

AIM: To investigate the expression of oncogene C-erbB-2 and its significance in colorectal carcinoma.

METHODS: Immunohistochemical technique (SP) was performed to detect the expression of oncogene C-erbB-2 in 69 cases of colorectal carcinoma and its corresponding tissues from patients received curative resection.

RESULTS: The expression of C-erbB-2 was mainly found in cell membrane and cytoplasm of colorectal carcinoma tissues with a positive rate of 65.2% (45/69), which was significantly higher than that in the tissues of benign tumor (2/20, P < 0.05). The positive rate of C-erbB-2 expression had significant difference between colorectal cancer (65.2%) and its surrounding tissues (mesenteric: 47.8%, normal cancer-adjacent: 30.4%, distant resection margin: 13.0%; all P < 0.05). The expression of C-erbB-2 was significantly correlated with the gross morphology, differentiation of the tumor cells, clinical staging (Dukes staging) and lymph node metastasis (P < 0.05), but not with the age, sex of patients, tumor location and size, as well as distant metastasis (P > 0.05). The expression of oncogene C-erbB-2 in the mesenteric margin and cancer-adjacent tissues was markedly different between routine histology and immunohistochemistry (P < 0.05).

CONCLUSION: The expression of C-erbB-2 gene is positively correlated with tumor invasion and metastasis in colorectal carcinoma, and it is a marker in evaluating the prognosis of colorectal carcinoma.

Expression of the mitotic checkpoint geneMAD2L2 has prognostic significance in colon cancer

Aneuploidy and genetic instability are a hallmark of colorectal cancer and other solid tumors, and they are thought to enhance tumor progression. The gene MAD2L2 (mitotic arrest deficient 2-like 2) encodes the spindle checkpoint protein MAD2L2 (or MAD2B), a key component of a surveillance system that delays anaphase until all chromosomes are correctly oriented. Defects in this mitotic checkpoint are known to contribute to genetic instability, i.e., numerical and structural aberrations of chromosomes. We have previously identified MAD2L2 as significantly upregulated in locally restricted colorectal tumors by gene expression profiling. So far, MAD2L2 has not been reported to play a major role in human cancer in contrast to its homologue MAD2. To address this question, 118 histologically confirmed colorectal lesions were analyzed by quantitative real-time PCR for expression of MAD2L2, and compared to normal colon tissue from 11 patients. Twenty-five out of 118 tumor samples (21%) showed MAD2L2 overexpression of 3-fold or more compared to normal colon, and the fraction of overexpressing tumors increased with tumor stage. Correspondingly, protein levels of MAD2L2 were found to be significantly upregulated in tumors as compared to matched normal tissue. Tumors with upregulated MAD2L2 expression had significantly higher numbers of aberrant mitotic figures (anaphase bridges), an indication of chromosomal instability. Elevated expression of MAD2L2 was significantly correlated with reduced patient survival. By multivariate analysis, MAD2L2 expression was retained as an independent prognostic parameter for patient survival. Thus, our results demonstrate that overexpression of MAD2L2 correlates with bad prognosis in colorectal cancer.