Abstract 546: Characterization of tumor-stromal interactions in microenvironment of prostate cancer bone metastasis

Abstract

Abstract Prostate cancer is the most common cancer in men around the world, with a high incidence of bone metastasis, which is the major determinant of mortality in prostate cancer. The survival and proliferation of prostate cancer cells metastatic to bone result from the cross-talk between carcinoma cells and the stromal cells. In contrast to skeletal metastases resulting from breast or lung cancer that are most often osteolytic, metastases from prostate carcinoma are nearly always osteoblastic, suggesting that interactions between prostate cancer cells and stroma in bone might be different from those of lung or breast cancer cells and bone stroma. Therefore, gene expression patterns that are unique to osteoblastic prostate cancer will help to identify genes involved in the bidirectional cross-talk between prostate cancer cells and bone cells in microenvironment niche. However, because gene expression signatures from human cancer tissues are a mixture of those from carcinoma and stromal cells, it has been impossible to delineate stromal cell specific gene expression signatures from carcinoma cell signatures. Thus, we have devised a novel experimental strategy: “competitive cross-species hybridization of microarray”, which can simultaneously extract gene expression patterns of carcinoma cells and stromal cells from a single xenograft sample. In the current study, we xenografted human prostate cancer cells (PC3, PCA118b, 10A) into mouse bone and prostate and used these tissues for microarray experiments. Total RNAs were purified from three different tissue groups: normal bones (mouse RNA only), tumor-bearing bones (mixture of mouse and human RNA), and tumor-bearing prostates (mixture of mouse and human RNA). Labeled cRNA from normal bones and tumor-bearing bones were hybridized to mouse microarray slide to measure gene expression of mouse bone cells. Likewise, labeled cRNA from tumor-bearing prostate and tumor-bearing bone were hybridized to human microarray slide to measure gene expression of human prostate cancer cells. Gene expression data from mouse microarrays identified gene expression patterns unique to bone cells that interact with prostate cancer cells in bone. When same analysis applied to human data, it also uncovered prostate cancer cell gene expression signatures associated with different microenvironment (prostate vs. bone). In order to uncover gene networks involved in cross-talk between prostate cancer cells and bone cells in metastatic bone microenvironment, gene network analysis using Ingenuity Pathway Analysis (IPA) was applied to combined gene lists from human and mouse data. In conclusion, by applying novel experimental strategy, “competitive cross-species hybridization of microarray”, we uncovered critical gene network involved in bidirectional cellular communication that drives the survival of prostate cancer cells in metastatic bone microenvironment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 546.