Abstract A40: Detection of Erk1/2, Mek1/2, and Akt isoform phosphorylation in tumors of 115 patients with different cancer types using the NanoPro™1000 technology.
Authors: Unger Florian T. , Krüger Jana , Schaller Janina , Rebecca Giese , Dede Cordula , Samsen Alexandra , Juhl Hartmut , David Kerstin A. 
Published: August 2014

Proteomic analysis of cellular signaling networks has strongly gained in importance in the field of cancer research and treatment. In particular, there is a focus on the activation status of growth factor receptor related signaling cascades represented by phosphoproteins as key mediators of cellular signaling. For example, the inhibition of the EGF-receptor pathway has been widely integrated into clinical practice for different tumor entities, e.g. non small lung cancer and colorectal cancer. 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 this study, we differentially analyzed basal isoform phosphorylation of selected key proteins from two EGF-receptor downstream pathways in breast cancer (n=26), non-small cell lung cancer (n=29), colorectal cancer (n= 30) and liver metastases of colorectal cancer (n= 30) using the NanoPro1000™ technology. Patient's samples were collected according to Indivumed's standard operating procedures, ensuring a high quality of tissues characterized by ischemia times below 10 minutes, comprehensive clinical data and corresponding sets of body fluids. The detailed characterization of isoform phosphorylation was conducted using established NanoPro1000™ protocols for Erk1/2, Mek1/2 and Akt.

Statistical analysis of data revealed that isoform phosphorylation of Erk1/2, Mek1/2 and Akt significantly differed among individual patients, but not between tumor entities. Differences in phosphorylation patterns were characterized by the degree of overall phosphorylation, as well as individual patterns of isoform phosphorylation. This indicates that the in-depth analysis of isoform phosphorylation can reveal significant biological differences and might result in therapy relevant, predictive signatures independent of the mutation status. Hence, we established cut-off values for basal signaling molecule phosphorylation, to potentially enable the selection of patients, who will most likely benefit from targeted treatment. Based on the cut-off values we classified patients into statistical significant groups of high, moderate and low signaling molecule phosphorylation. In next steps, this classification will be further validated in terms of clinical relevance to response to targeted therapy.

In summary, the NanoPro1000™ technology can be used to robustly screen a large cohort of patients for signaling molecule phosphorylation. The analysis of patients on the proteome level may be helpful to identify predictive biomarker for the development of resistance to anti-EGF-receptor treatment and thus further improve personalized medicine.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A40.

Citation Format: Florian T. Unger, Jana Krüger, Janina Schaller, Giese Rebecca, Cordula Dede, Alexandra Samsen, Hartmut Juhl, Kerstin A. David. Detection of Erk1/2, Mek1/2, and Akt isoform phosphorylation in tumors of 115 patients with different cancer types using the NanoPro™1000 technology. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A40.