Comparative study of gene expression by cDNA microarray in human colorectal cancer tissues and normal mucosa

Abstract

The causative molecular pathways underlying the pathogenesis of colorectal cancer (CRC) need to be better characterized. The purpose of our study was to better understand the genetic mechanism of oncogenesis for human colorectal cancer and to identify new potential tumor markers of use in clinical practice. We used cDNA microarrays to compare gene expression profiles of colorectal biopsies from 25 CRC patients and 13 normal mucosa from adjacent non-cancerous tissues. Findings were validated by real-time PCR; in addition, Western blotting and immunochemistry analysis were carried out as further confirmation of differential expression at a protein level. Comparing cancerous tissues with normal colonic mucosa we identified 584 known genes differentially expressed to a significant degree (p<0.001). Many of the transcripts that were more abundant in tumors than in non-neoplastic tissues appear to reflect important events for colon carcinogenesis. For example, a significant number of these genes serve as apoptotic inhibitors (e.g. BFAR, BIRC1, BIRC6). Furthermore, we observed the simultaneous up-regulation of HLA-E and the down-regulation of ß2-microglobulin; these genes strongly support a potential tumor escape strategy from immune surveillance in colon cancer tissues. Our study provides new gene candidates in the pathogenesis of human CRC disease. From our results we hypothesize that CRC cells escape immune surveillance through a specific gene expression alteration; moreover, over-expression of several survival genes seems to confer a more anti-apoptotic phenotype. These genes are involved in pathways not previously implicated in CRC pathogenesis and they may provide new targets for therapy.

β2microglobulin mRNA expression levels are prognostic for lymph node metastasis in colorectal cancer patients

“…accuracy of B2M for prognosis of lymph node metastases was 0.83±0.04, a value that is sufficiently high to warrant further investigation into this biomarker. Although a previous study has shown that B2M was the most highly downregulated gene in CRC compared to adjacent normal tissue (Bianchini et al, 2006), this is the first study to show a relationship between B2M mRNA levels and a clinical parameter related to outcome of CRC patients.…”

“…Our rationale for the Revised 14 February 2008; accepted 7 April 2008; published online 27 May 2008 inclusion of B2M was based on the following observations: (1) 32% of B2M null  IL-2 null mice develop adenocarcinoma in the proximal half of the colon between 6 and 12 months (Shah et al, 1998), (2) out of 19K genes screened from 25 matched CRC tissue and normal mucosa, B2M was the most highly downregulated gene in CRC (Bianchini et al, 2006), (3) oncogenic K-ras mutations (which are present in the majority of CRC) inhibit the expression of B2M and other interferon (IFN)-responsive genes (Klampfer et al, 2003), (4) downregulation of B2M in CRC has been confirmed by real-time RT -PCR (Bianchini et al, 2006), and (5) the level of expression of B2M is very high and can be reliably measured in formalin-fixed paraffin-embedded (FFPE) tissues (Chen et al, 2007).…”

HLA-E contributes to an immune-inhibitory phenotype of glioblastoma stem-like cells

“…Under physiological conditions, HLA-E is mainly involved in maternal immune tolerance. HLA-E is abberantly expressed in several tumors like lymphoma (Marin et al, 2003), melanoma (Derre et al, 2006), colon carcinoma (Bianchini et al, 2006), ovarian cancer (Malmberg et al, 2002) and may contribute to immunosuppression in glioblastoma (Mittelbronn et al, 2007;Wischhusen et al, 2005).…”

Up-Regulation of microrna-125b Induced By 5-Fluorouracil (5-FU) Treatment Inhibits Cell Growth and Proliferation in Pancreatic Cancer Cells

“…It has been reported NAIP is overexpressed in breast cancer patients with unfavorable clinical features such as stage and tumor size, suggesting that NAIP would play a role in the disease manifestation [28]. In colorectal cancer BIRC1 transcript that was more abundant in tumors than in non-neoplastic tissues appeared to reflect important events for colon carcinogenesis [29]. Our results showed that BIRC1 was down-regulated in 5-FU treated cells and miR-125b stable transfected clones 5 and 14, indicating reduction of BIRC1 might contribute to the inhibition of apoptosis of pancreatic cancer cells.…”