Elsevier

Lung Cancer

Volume 48, Issue 1, April 2005, Pages 19-29
Lung Cancer

Identification of intelectin overexpression in malignant pleural mesothelioma by serial analysis of gene expression (SAGE)

https://doi.org/10.1016/j.lungcan.2004.10.011Get rights and content

Summary

Malignant pleural mesothelioma (MPM) is a fatal neoplasm with no acceptable curative approaches. We used serial analysis of gene expression (SAGE) to compare the gene expression pattern of a surgically resected MPM to the autologous normal mesothelium. Intelectin gene overexpression (>139-fold) was found in the tumor. Online SAGE datasets revealed intelectin to be consistently present in mesothelioma(s), ovarian cancer, and colon cancer. Intelectin mRNA expression was found by RT-PCR in 4 of 5 resected MPM tumors, and Intelectin protein expression was confirmed by immunohistochemistry in 28 of 53 MPM tumors, and in 4 of 4 mesothelioma cell lines studied by Western blot. A marked induction in intelectin gene expression was observed among human primary mesothelial cells as a consequence of crocidolite asbestos exposure and simian virus 40 infection. Intelectin overexpression in mesothelioma could have potential screening, and therapeutic implications.

Introduction

Malignant pleural mesothelioma (MPM) is a fatal tumor that continues to be resistant to various treatment options available at present. It is an aggressive malignancy, which, if untreated, has a median survival of less than 8 months [1]. Although recent treatment regimens for selected cases (stage I epithelial) have extended the median survival time from less than a year to almost 2 years, it still remains a difficult clinical problem for which new therapeutic options are being evaluated and tested [2], [3]. Although the association between the asbestos and mesothelioma has been well established, the multitude of events which characterize mesothelial carcinogenesis remains under investigation and include cytogenetic aberrations with alterations of oncogenes, tumor suppressor genes, and genes associated with growth factors or immune modulation [4], [5]. Presently, however, there are no methods to successfully identify patients exposed to asbestos that are at high risk for developing mesothelioma. The aim of this study was to identify differences in the gene expression of MPM tumor compared to normal mesothelium. Serial analysis of gene expression (SAGE) was used to investigate the pattern of differentially expressed gene tags in a human MPM tumor and its matching normal peritoneum. We found elevated expression of intelectin (ITLN1), a novel galactose binding lectin that is usually expressed in heart, colon, small intestine and which has not been previously described in human malignancies. Given the level of intelectin tags expressed in MPM in comparison to mesothelin, we consider it to be a novel finding for mesothelioma and evaluated its expression in a series of MPMs.

Section snippets

Analysis of online SAGE database using the t test

The SAGE results obtained on the MPM tumor (RO96) in comparison to its matching peritoneum are shown in Table 1. Our analysis of SAGE databases revealed 38 tags overexpressed and 17 underexpressed in malignant pleural mesothelioma as compared with normal peritoneum. The results in Table 1 verify previous mesothelioma associated findings including the overexpression of cytokeratins and mesothelin [13]. The tag corresponding to a hypothetical protein (AGATCCCAAG) which was subsequently identified

Discussion

In this communication, we provide the first detailed description of the differential gene expression patterns among the normal pleura and resected malignant pleural mesothelioma tumor with SAGE. We have identified intelectin as a novel finding for mesothelioma using SAGE, confirmed the presence of the intelectin mRNA transcripts by RT-PCR, and verified protein expression by Western blot and immunohistochemical analysis of 53 surgically resected mesotheliomas. These studies were concordant, as

MPM tumor and matching peritoneum

With investigational review board approval, tumor from a 39-year-old male (R096) undergoing extrapleural pneumonectomy for T2NOMO mesothelioma was immediately snap frozen in liquid nitrogen along with uninvolved peritoneum to construct SAGE libraries. Other mesothelioma tumors (R018, R049, R059, R083, R092, R093) as well as normal pleura (R130) from the Karmanos Thoracic Oncology Archives were used for confirmatory analyses.

SAGE

The construction and analysis of the SAGE libraries were performed as

Acknowledgements

This work was supported in part by a grant from the Early Detection Research Network,VA Merit awards to HIP, and an American Lung Association grant and VA Merit award to AW. We thank Julia Sluchak-Carlsen, Apurvi Desai and Valerie Murphy for technical support.

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