Expression of epidermal growth factor-receptor related protein (ERRP) in human colorectal carcinogenesis

In vivo molecular imaging of epidermal growth factor receptor in patients with colorectal neoplasia using confocal laser endomicroscopy

Epidermal growth factor receptor (EGFR) plays an important role in tumorigenesis of colorectal cancer (CRC), and its in vivo molecular imaging in rodent models has become the subject of an increased number of studies using novel imaging techniques for gastrointestinal endoscopy. Current study aimed to evaluate the use of confocal endomicroscopy (CLE) for in vivo molecular imaging of EGFR in patients with colorectal neoplasia. Molecular imaging of colorectal neoplasia in patients was performed by CLE after topical application of a fluorescent-labeled molecular probe against EGFR. Representative images of CLE were chosen to calculate EGFR-specific fluorescence intensity. Targeted biopsy specimens were taken from each examined site during in vivo imaging for histology and immunohistochemistry (IHC). During in vivo molecular imaging in 37 patients, an EGFR-specific fluorescence signal was present in 18/19 CRC, and 12/18 colorectal adenomas. No or only weak fluorescence signal was observed in vivo in 10 cases of normal mucosa. CLE is a novel tool that could be used in molecular imaging with specific targeting of EGFR in patients with colorectal neoplasia. This technique demonstrates a promising imaging approach for targeted therapies of colorectal neoplasia.

Epidermal growth factor receptor (EGFR) gene copy number in colorectal adenoma-carcinoma progression

Adenomas are the easily identifiable precursors of the vast majority of colorectal cancers. Some of their morphological features, such as dysplasia, are predictive of their biological evolution toward adenocarcinomas. A large body of evidence has demonstrated that the epidermal growth factor receptor (EGFR) signaling pathway is commonly activated in colorectal cancer and EGFR-target therapies have improved the outcome for colorectal cancer patients. Nevertheless, the mechanisms underlying the role of EGFR in the adenoma-carcinoma sequence are not entirely clear. We retrospectively analyzed EGFR gene copy number by fluorescence in situ hybridization (FISH) in paraffin-embedded tissue from 215 patients recruited through a prospective colorectal cancer screening procedure and undergoing surgical colectomy. We observed that in human colorectal carcinogenesis, EGFR copy number increases progressively, from adenomas with high-grade dysplasia to locally advanced adenocarcinomas, through early invasive adenocarcinomas, suggesting that deregulation of EGFR may correlate with the malignant progression.

Concordant KRAS mutations in primary and metastatic colorectal cancer tissue specimens: a meta-analysis and systematic review

A meta-analysis was performed to compare KRAS gene mutations in colorectal cancer tissue samples with primary and metastatic colorectal cancers. A total of 19 publications with 986 paired primary and distant metastases and 171 paired primary and lymph node metastases showed that KRAS genotype was highly concordant in primary and distant metastatic tumors, indicating that either type of tumor tissue could be useful as a source to detect KRAS mutations for selection of anti-EGFR therapy. However, lymph-node-metastatic tumors might not be suitable for diagnostic analysis of KRAS mutations due to an obvious discordant rate between primary and lymph-node-metastatic tumors.

Differential expression of proteins during the canceration of colorectal adenoma cells

Colorectal carcinoma is one of the most frequently seen malignant tumors of the gastric tract. Colorectal adenomas are considered to be precancerous lesions of colorectal carcinoma. The adenoma-carcinoma sequence has traditionally been characterized as a uniform progression from normal mucosa to adenoma to carcinoma through an underlying homogenous carcinogenic pathway. Current research indicates that some proteins are differentially expressed in colorectal adenomas during their carcinomatous changes. These proteins include cell skeleton-related proteins, intracellular enzymes and proteins involved in cellular signal transduction. The functional roles of these proteins in the carcinomatous changes of colorectal adenomas differ greatly from each other and have not yet been fully clarified. This article reviews these differentially expressed proteins and briefly describes the possible mechanism by which these proteins cause the malignant transition from colorectal adenoma to colorectal carcinoma. Furthermore, proteomic technology has developed rapidly and has been simultaneously applied to the detection and characterization of various kinds of proteins due to its high throughput and convenient nature. This article also introduces the utilization of proteomics to identify and compare proteins that are differentially expressed between colorectal adenoma and colorectal carcinoma. Research on these proteins may lead to the identification of cancer markers that could subsequently facilitate the early diagnosis and further understanding of colorectal carcinoma.

Emerging therapies in gastrointestinal cancers

Members of the receptor tyrosine kinase family, that include EGFR, ErbB-2/HER-2, ErbB-3/HER-3 and ErbB-4/HER-4, are frequently implicated in experimental models of epithelial cell neoplasia as well as in human cancers. Therefore, interference with the activation of these growth factor receptors represents a promising strategy for development of novel and selective anticancer therapies. Indeed, a number of inhibitors that target either EGFR or HER-2, with the exception of a few that target both; have been developed for treatment of epithelial cancers. Since most solid tumors express different ErbB receptors and/or their ligands, identification of inhibitor(s), targeting multiple EGFR family members may provide a therapeutic benefit to a broader patient population. Here we describe the significance of an ErbB family of receptors in epithelial cancers, and summarize different available therapeutics targeting these receptors. It also emphasizes the need to develop pan-ErbB inhibitors and discusses EGF-Receptor Related Protein, a recently isolated negative regulator of EGFR as a potential pan-ErbB therapeutic for a wide variety of epithelial cancers.

Therapeutic potential of EGFR-related protein, a universal EGFR family antagonist

Interference with the activation of growth factor receptors, specifically epidermal growth factor receptor (EGFR) and/or other member(s) of its family (human epidermal growth factor [HER]-2, -3 and -4) represents a promising strategy for development of novel and selective anticancer therapies. Indeed, a number of inhibitors that target either EGFR or HER-2, but not both, have been developed for treatment of epithelial cancers. However, since most solid tumors express different EGFRs, identification of inhibitor(s) targeting multiple EGFR family members may provide a therapeutic benefit to a broader patient population. To this end, the author proposes that EGFR-related protein (ERRP), a recently isolated negative regulator of EGFR that possesses a substantial homology to the extracellular ligand-binding domain of EGFR and its family members, is a pan-ErbB inhibitor that targets multiple members of the EGFR family. This review discusses the significance of EbB [corrected] family of receptors in epithelial cancers, and describes isolation, characterization and the mechanisms of action of ERRP as well as its potential application as a therapeutic agent for a wide variety of epithelial cancers.

Epidermal growth factor receptor (EGFR)-related protein inhibits multiple members of the EGFR family in colon and breast cancer cells

Inactivation of epidermal growth factor receptor (EGFR) family members represents a promising strategy for the development of selective therapies against epithelial cancers. Current anti-EGFR therapies, such as cetuximab (Erbitux), gefitinib (Iressa), or trastuzumab (Herceptin), target EGFR or HER-2 but not both. Because solid tumors express different EGFRs, identification of inhibitor(s), targeting multiple EGFR family members may provide a therapeutic benefit to a broader patient population. We have identified a natural inhibitor of EGFRs called EGFR-related protein (ERRP), a 53 to 55 kDa protein that is present in most, if not all, normal human epithelial cells. The growth of colon (HCT-116, Caco2, and HT-29) and breast (MDA-MB-468 and SKBR-3) cancer cells expressing varying levels of EGFR, HER-2, and/or HER-4 was inhibited by recombinant ERRP in a dose-dependent manner. In contrast, ERRP caused no inhibition of growth of normal mouse fibroblast cell lines (NIH-3T3, NIH-3T3/P67), and the growth of nontransformed rat small intestinal IEC-6 cells expressing relatively low levels of EGFRs was inhibited only at high doses of ERRP. Transforming growth factor-alpha or heparin-binding epidermal growth factor-induced activation of EGFR and HER-2 was inhibited by ERRP in colon and breast cancer cells expressing high levels of EGFR or HER-2. In contrast, cetuximab inhibited the growth- and ligand-induced activation of EGFR in cell lines expressing high levels of EGFR, whereas trastuzumab was effective only in HER-2-overexpressing cells. ERRP and trastuzumab, but not cetuximab, attenuated heregulin-alpha-induced activation of colon and breast cancer cells that expressed high levels of HER-2. Furthermore, ERRP, but not cetuximab or trastuzumab, significantly induced apoptosis of colon and breast cancer cells. None of these agents induced apoptosis of either NIH-3T3 mouse fibroblast or normal rat small intestinal IEC cells. Our results suggest that ERRP is an effective pan-erbB inhibitor and, thus, may be a potential therapeutic agent for a wide variety of epithelial cancers expressing different levels and subclasses of EGFRs.