ABSTRACT
We recently reported on the use of cDNA subtraction combined with microarray based expression analysis for identifying genes that are differentially over-expressed in small cell lung carcinoma. One of the several hundred genes identified using this approach was termed L985P and its molecular characterization is described in this report. The differential over-expression of L985P mRNA in SCLC, as determined by microarray analysis, was confirmed by real-time RT-PCR and Northern blot analysis. Immunohistochemical analyses show that L985P protein is highly expressed in SCLC with very restricted expression observed in normal lung, which was confined to the apical region of the ciliated bronchiolar epithelium. Flow cytometric and immunohistochemical analysis showed that L985P was localized to the cell surface. Sequence homology comparison indicated that L985P is identical to MS4A8B, a member of the recently described membrane-spanning 4-domain family, subfamily A (MS4A) gene family. The MS4A gene family currently consists of greater than 20 distinct human and mouse proteins that include CD20 and FcepsilonRIbeta. Both CD20 and FcepsilonRIbeta are involved in signaling events that regulate diverse cellular functions including cell growth regulation and differentiation. Collectively, the results presented herein demonstrate that L985P is differentially over-expressed in SCLC and may have potential clinical utility as an immunotherapeutic target for the treatment of SCLC.
Subject(s)
Antigens, CD/biosynthesis , Antigens, CD/genetics , Carcinoma, Small Cell/genetics , Gene Expression Profiling , Lung Neoplasms/genetics , Receptors, IgE/biosynthesis , Receptors, IgE/genetics , Carcinoma, Small Cell/pathology , Cell Differentiation , Cell Proliferation , Humans , Immunotherapy , Lung Neoplasms/pathology , Membrane Proteins , Signal Transduction , Tumor Cells, CulturedABSTRACT
To identify genes that are differentially over-expressed in Small Cell Lung Carcinoma (SCLC) we have used a combination of suppression subtractive hybridization and cDNA microarray to analyse the expression profiles of 2400 cDNAs clones. Genes that are over-expressed in SCLC were identified using 32 pairs of fluorescence-labeled cDNA samples representing various lung tumors and normal tissues. This comprehensive approach has resulted in the identification of 209 genes that are differentially over-expressed in SCLC. Quantitative real-time PCR was used to further validate the expression of 43 genes in SCLC tumors and various normal tissues. Discussed in this report are nine genes, which showed the most promising SCLC tumor to normal tissue differential expression profiles, including seven known and two novel genes. The large number of differentially expressed genes identified from this analysis and the characterization of these genes will provide valuable information in better understanding the biology of SCLC and help us in developing these gene products as potential targets for diagnostic as well as therapeutic usage.
