Overexpression of ribosome binding protein 1 (RRBP1) in breast cancer

Breast cancer is the most prevalent cancer in women and is responsible for ~450,000 deaths worldwide each year. It accounted for 23% of new cancer cases and 14% of total cancer deaths in 2008 [1]. The molecular pathology of breast cancer has been studied extensively over the last two decades and a large number of alterations at the molecular level have been reported by several groups. Gene expression profiling studies are a powerful means of investigating changes in the transcriptome of cancerous cells. They provide a broad view of the numerous candidate genes that are differentially expressed in normal and cancerous lesions [2]. Many of these genes show significant changes in corresponding protein expression. Large scale gene expression profiling studies have been carried out on various subtypes of breast carcinomas by different groups [3-5]. Although these studies have reported many common genes that are significantly upregulated at the mRNA level in breast tumors, such findings are not of much importance if the overexpression is not reflected at the protein level. Moreover, high-throughput techniques like microarrays are associated with limitations such as experimental and biological noise that necessitate further validation of the results obtained using other relatively accurate methods. The current rush of RNA-Seq analyses will also require the same kind of validation that mRNA transcripts are actually translated into proteins.Our approach in this study was to integrate data from public repositories of gene expression information and online resources of protein information coupled to literature mining to generate a list of molecules that have been shown to be overexpressed at the transcript level but not at the protein level. We selected RRBP1 as one such candidate to further validate its protein expression across a panel of breast carcinomas using immunohistochemistry.RRBP1(Q9P2E9, ENSP00000367044.1) is an endoplasmic reticulum membrane protein [6-8] that is e