Alterations in molecular networks of metastatic colorectal carcinoma reveal organ-specific signatures: Implications for targeted therapy of metastatic disease

Abstract

3532 Background: Proteomic analysis of aberrant protein kinase activity is poised to provide crucial knowledge that could drive molecular-targeted therapeutics and personalized medicine. Many cancers are detected at late stages when metastasis has already occurred. Knowledge about the molecular derangements in the metastatic lesion is crucial for the rational selection of therapeutics. Very little is known about the signaling networks in the metastatic microenvironment. We employed reverse phase protein microarrays coupled to laser capture microdissection for a multiplexed phosphoproteomic fingerprint of colorectal metastatic disease to begin to understand the molecular functional changes that occur upon metastasis. Methods: 68 frozen cases of patient-matched colorectal cancer and hepatic metastasis, 15 cases of pulmonary metastasis, and 27 cases of hepatic metastasis of other primary cancers including breast, melanoma, pancreatic, ovarian, and stomach cancers (all taken at the same time at surgery), were subjected to laser capture microdissection. Procured tumor epithelia (20,000 cells per sample), were lysed and subjected to reverse phase protein microarray analysis. Using this technique, we measured the phosphorylation state of 75 kinase substrates. Molecular network analysis was performed using commercially available software. Results: Our results indicate that, unlike analysis of gene microarray data, we observe a significant difference between the molecular networks of activated kinase substrates within the metastatic lesion compared to the patient-matched primary tumor. In fact, despite overall patient-specific heterogeneity of the portraits, organ specific signatures that were independent of the primary origin of the tumor were identified. Conculsions: Effective treatment in the new era of personalized targeted therapeutics will require the ability to understand the functional activation of cellular signaling pathways since these are the drug targets themselves. Our results indicate that treatment of metastatic disease, and patient stratification for matching with the appropriate therapy may be organ-specific and not predicated upon the primary site of the disease. No significant financial relationships to disclose.