Abstract 44: Tissue image analysis tool to quantify HER2 RNA and protein expression by colorimetric in situ hybridization and immunohistochemistry for breast cancer diagnosis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Early cancer diagnosis and risk assessment are powerful drivers in discovery of oncology biomarkers for diagnostic tests and simultaneous improvement of already identified biomarkers. Molecular tools such as RNA Colorimetric in situ hybridization (CISH) and immunohistochemistry (IHC) combined with conventional histopathology promise to increase the sensitivity and specificity of cancer staging and overall survival prediction. Changes in oncogene and proto-oncogene expression are a hallmark of cancer. For this reason, simultaneous quantification of mRNA and protein expression using RNA CISH and IHC combined with image-analysis is of interest. One such proto-oncogene is HER2, which is encoded by ERBB2 gene located at the long arm of human chromosome 17 (17q12). Here, we combine RNA CISH and IHC with image-analysis to develop a reliable quantitative HER2 assay that enables quantification of HER2 mRNA and protein expression in the context of human breast cancer. Since HER2 is only over-expressed in a subset of human breast cancers, we initially focused our analysis by screening tissue microarrays (TMAs) using RNA CISH and IHC. TMAs containing 20 normal and 20 breast tumor tissues were tested and whole-slide imaging was used to obtain CISH and IHC signals. HER2 mRNA and protein expression were analyzed, quantified, and compared both at tissue- and individual cell-levels using proprietary image-analysis based tools. Moreover, we compared heterogeneity of RNA and protein expression and further extended our studies to several other cancer-related genes. Finally, since oncogene expression plays a role in cancer pathologies, successful quantification of oncogene in situ expression in human cancer tissues may prove to be beneficial to further understanding of cancer pathology, for drug screening and development of biomarkers and ultimately diagnostic tests. Citation Format: Mirza Peljto, Joseph Krueger, Erik Hagendorn, David Young, Steve Potts, Quan Nguyen, Botoul Maqsodi, Takuro Yaoi, Gary McMaster. Tissue image analysis tool to quantify HER2 RNA and protein expression by colorimetric in situ hybridization and immunohistochemistry for breast cancer diagnosis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 44. doi:10.1158/1538-7445.AM2013-44