Constructed (a) primary prostate cancer-specific and (b) metastatic prostate cancer-specific miRNA-mRNA interaction networks. The primary-specific network includes 67 miRNAs and 233 mRNAs, while the metastatic network involves 65 miRNAs and 180 mRNAs. Both networks include 500 bi-relational edges which are selected based on their summed weight (among all edges converted from 20000 hyperedges of 100 hypergraphs). Up- and down-expressed miRNAs and genes are determined by the mean of each stage class. The red boxed miRNAs and genes have been reported to be associated with the particular stage of prostate cancer. The triangles, rectangles, diamonds and circles denote miRNAs, oncogenes or tumor suppressor genes, transcription factors, and other genes in the network, respectively.