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Comparative profiling of primary colorectal carcinomas and liver metastases

ABSTRACT: 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) of the expressed genes between these two groups. To characterize the clinical relevance of two highly-ranked differentially expressed signature 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. 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 = 0.035), 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 signature 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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE22834 | GEO | 2011/03/22

SECONDARY ACCESSION(S): PRJNA127889

REPOSITORIES: GEO

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Project description:Purpose: This study aimed to identify a novel biomarker or a target of treatment for colorectal cancer (CRC). Experimental Design: The expression profiles of cancer cells in 104 patients with CRC were examined using laser microdissection and oligonucleotide microarray analysis. Overexpression in CRC cells especially in patients with distant metastasis was a prerequisite to select candidate genes. The mRNA expression of candidate gene was investigated by quantitative reversetranscription polymerase chain reaction (RT-PCR) in 77 patients as a validation study. We analyzed the protein expression and localization of the candidate gene by immunohistochemical study, and investigated the relationship between the expression and the clinicopathological feature in 274 CRC patients. Results: We identified 6 genes as candidates related to distant metastasis in CRC patients by microarray analysis. Among these genes, Osteoprotegerin (OPG) is known to have an association with aggressiveness in several cancers through inhibiting apoptosis by neutralizing the function of tumor necrosis factor related apoptosis inducing ligand (TRAIL). The mRNA expression of OPG in cancer tissues was significantly higher in patients with distant metastasis than those without metastasis. The overexpression of OPG protein was significantly associated with worse overall survival and relapse free survival (RFS). Moreover, the overexpression of OPG protein was an independent risk factor for recurrence of CRC. Conclusion: The overexpression of OPG would be a predictive biomarker of recurrence and a target of the treatment for CRC. Total of 148 microarray datasets obtained from LCM and homogenized tissues of colorectal cancer patients were normalized using robust multi-array average (RMA) method under R 2.6.2 statistical software with affy package from BioConductor. Normalization was separately performed for LCM dataset and homogenized tissue dataset. The normalized gene expression levels were presented as log2-transformed values by RMA.

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Comparative profiling of primary colorectal carcinomas and liver metastases

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