Abstract 913: Differences in basal isoform phosphorylation of signaling proteins between normal and tumor tissue in different cancer types detected by the NanoPro™1000 technology
Authors: Unger Florian T. , Krueger Jana , Schaller Janina , Giese Rebecca , Dede Cordula , Samsen Alexandra , Juhl Hartmut , David Kerstin A. 
Published: May 2015

In the era of targeted anticancer therapy, the proteomic analysis of cellular signaling networks has strongly gained in importance in the field of cancer research and treatment. There is scientific evidence that individual phosphorylation profiles of signaling proteins, besides the mutation status of patients` tumors, contain useful therapeutic information and their measurement has to be established in the clinical setting. Although, predictive genetic markers of response to targeted therapy such as KRAS testing are already in use, heterogeneity in responses to such treatment has been clinically observed. In order to understand this heterogeneity on the proteome level, the activation status of cell signaling proteins has to be analyzed. In addition, the comparison of basal phosphorylation levels of normal tissues and corresponding tumor tissues might promote a deeper understanding of cell signaling in complex clinical biospecimen. In this study, we differentially analyzed basal isoform phosphorylation in normal and tumor tissue of colorectal cancer (n= 30) and corresponding liver metastases (n= 30), as well as in breast cancer (n=26), and non-small cell lung cancer (n=29). Isoform and corresponding phosphorylation of selected key proteins from two EGF-receptor downstream pathways, i.e. Erk1/2, Mek1/2 and Akt were detected using the NanoPro™1000 technology. It has been postulated that oncogene addiction, i.e. hyper activation of oncogenic signaling pathways is a hallmark of cancer, therefore potentially restricted to tumor tissue. Today, little is known about the basal phosphorylation status of normal tissue and therapeutic consequences. In this study, we have shown that there are significant differences in the overall degree of phosphorylation between normal and tumor tissues. For example, normal liver tissue shows significant higher phosphorylation of Erk1/2 compared to liver metastases of colorectal cancer. Statistical analysis of data also revealed that the overall phosphorylation of Erk1/2, Mek1/2 and Akt significantly differed among individual patients, but not between tumor entities. Therefore, the in-depth analysis of specific isoform phosphorylation can reveal significant biological differences. Furthermore, the analysis might result in therapy relevant, predictive signatures independent of the mutation status. In summary, we found that high phosphorylation of signaling molecules is not restricted to tumor tissue and has to be taken in account when analyzing clinical biospecimen. The NanoPro TM1000 technology can be used to robustly screen a large cohort of patients, i.e. biopsies, to gain insights in phosphorylation patterns of normal and cancer tissue. Therein, the analysis of isoform phosphorylation potentially enables the selection of patients, who will most likely benefit from targeted treatment.

Citation Format: Florian T. Unger, Jana Krueger, Janina Schaller, Rebecca Giese, Cordula Dede, Alexandra Samsen, Hartmut Juhl, Kerstin A. David. Differences in basal isoform phosphorylation of signaling proteins between normal and tumor tissue in different cancer types detected by the NanoPro™1000 technology. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 913. doi:10.1158/1538-7445.AM2014-913