Expression Signatures Identify Origin of Primary and Therapeutic Strategies for Patients with Advanced Solid Tumors

ABSTRACT: Background: Fatal cancer is often the result of spread, or metastasis, of a cancer cell from the site of its origin to a distant anatomic site. While the metastatic process and the foreign environment of the metastatic site impact a tumor’s biology, we continue to determine therapy for patients based upon their cancer’s site of origin. We have performed an unbiased analysis across metastatic solid tumors from common primary sites to determine the molecular impact of the metastatic process on site-specific biology and to identify novel therapeutic strategies. Methods: Global gene expression was used as a biological phenotype to perform a top-down analysis of 96 metastatic human tumors. Laser capture microdissection, RNA amplification, and microarray analysis were used to measure the transcription patterns of malignant epithelial cells. Genes, multi-gene expression “signatures”, and pathways associated with site of origin (SOO) and site of metastases (SOM) were identified using established computational approaches. SOO and SOM expression signatures were validated on multiple, independent datasets comprising 1217 samples (1104 samples from GSE2109 (Expression Project for Oncology) and 113 samples from GSE12630 (Monzon FA, Lyons-Weiler M, Buturovic LJ, Rigl CT et al. Multicenter validation of a 1,550-gene expression profile for identification of tumor tissue of origin. J Clin Oncol 2009 May 20;27(15):2503-8. PMID: 19332734). Reverse phase proteomics and in vitro tissue culture were used to validate associations between biological pathways, site of primary, and implicated therapeutic combinations. Findings: SOO has the dominant influence on solid tumor biology as samples segregate based upon their primary site during unsupervised hierarchical clustering. In addition, statistically significant associations are identified between single genes and pathways and each primary site investigated and SOO signatures for colon, breast, ovary, lung, and prostate cancers accurately identify primary site for independent samples of both local and metastatic tumors independent of degree of histological differentiation. The impact of SOM on tumor biology is evident as genes and pathways are significantly associated with metastatic site and SOM signatures can be generated but they are not strongly predictive when applied to localized tumors. Pathway analysis identified relatively increased expression of MYC, beta-catenin, and SRC gene sets in metastatic colorectal cancers which was confirmed with proteomic analysis of a sub-set of the original tumors. Within colorectal cancers, high SRC expression also correlates with predicted oxaliplatin sensitivity and the combination of an SRC inhibitor with oxaliplatin demonstrated synergy in three independent colorectal cancer cell lines. Interpretation: Our findings suggest that the complex alterations required for metastasis do not obscure the impact of a cancer cell’s origin. SOO signatures have the potential to be highly accurate diagnostic tools and the underlying site-specific biology can be used to identify novel therapeutic targets for advanced cancers. Keywords: Gene expression analysis

ORGANISM(S): Homo sapiens

PROVIDER: GSE18549 | GEO | 2016/02/13

SECONDARY ACCESSION(S): PRJNA121359

REPOSITORIES: GEO