An estimated 15% or more of the cancer burden worldwide is attributable to known infectious agents. We screened colorectal carcinoma and matched normal tissue specimens using RNA-seq followed by host sequence subtraction and found marked over-representation of Fusobacterium nucleatum sequences in tumors relative to control specimens. F. nucleatum is an invasive anaerobe that has been linked previously to periodontitis and appendicitis, but not to cancer. Fusobacteria are rare constituents of the fecal microbiota, but have been cultured previously from biopsies of inflamed gut mucosa. We obtained a Fusobacterium isolate from a frozen tumor specimen; this showed highest sequence similarity to a known gut mucosa isolate and was confirmed to be invasive. We verified overabundance of Fusobacterium sequences in tumor versus matched normal control tissue by quantitative PCR analysis from a total of 99 subjects ( p = 2.5 3 10 -6), and we observed a positive association with lymph node metastasis.[Supplemental material is available for this article.] There are variations on the method, but the basic approach involves shotgun sequencing bulk DNA or RNA isolated from disease tissue, computational subtraction of all sequence reads recognized as human, and comparison of the residual reads to databases of known microbial sequences in order to identify microbial species present in the initial specimen. The method is complementary to traditional culture and histolology-based protocols, and new massively parallel sequencing technologies impart high sensitivity. At present the power of the method remains restricted by the content of microbial sequence databases, but with our increasing reach into microbial sequence space, the comprehensiveness of these data resources continues to improve. In oncology, the identification of a novel polyomavirus in Merkel Cell carcinoma (Feng et al. 2008) is a recent demonstration of the utility of a metagenomics approach.Colorectal carcinoma (CRC) is the fourth leading cause of cancer deaths, responsible for approximately 610,000 deaths per year worldwide (World Health Organization 2011). It is also one of the first and best genetically characterized cancers, and specific somatic mutations in oncogenes and tumor suppressor genes have been found that are associated with progression from adenomatous lesions (polyps) to invasive carcinoma (Vogelstein et al. 1988). The root cause of CRC is unclear, but inflammation is a well-recognized risk factor (Wu et al. 2009;McLean et al. 2011). Given the link between H. pylori-mediated inflammation and gastric cancer (Marshall and Warren 1984), we asked if inflammatory microorganisms are associated with other gastrointestinal (GI) cancers. We began to address this question by undertaking a metagenomic survey of colorectal carcinoma. ResultsTotal RNA was isolated from frozen sections of 11 matched pairs of colorectal carcinoma and adjacent normal tissue specimens. RNA was purified by host ribosomal sequence depletion, rather than poly(A) selection, in order to re...

Recent advances in next generation sequencing have made it possible to precisely characterize all somatic coding mutations that occur during the development and progression of individual cancers. Here we used these approaches to sequence the genomes (>43-fold coverage) and transcriptomes of an oestrogen-receptor-alpha-positive metastatic lobular breast cancer at depth. We found 32 somatic non-synonymous coding mutations present in the metastasis, and measured the frequency of these somatic mutations in DNA from the primary tumour of the same patient, which arose 9 years earlier. Five of the 32 mutations (in ABCB11, HAUS3, SLC24A4, SNX4 and PALB2) were prevalent in the DNA of the primary tumour removed at diagnosis 9 years earlier, six (in KIF1C, USP28, MYH8, MORC1, KIAA1468 and RNASEH2A) were present at lower frequencies (1-13%), 19 were not detected in the primary tumour, and two were undetermined. The combined analysis of genome and transcriptome data revealed two new RNA-editing events that recode the amino acid sequence of SRP9 and COG3. Taken together, our data show that single nucleotide mutational heterogeneity can be a property of low or intermediate grade primary breast cancers and that significant evolution can occur with disease progression.

Rhodococcus sp. RHA1 (RHA1) is a potent polychlorinated biphenyl-degrading soil actinomycete that catabolizes a wide range of compounds and represents a genus of considerable industrial interest. RHA1 has one of the largest bacterial genomes sequenced to date, comprising 9,702,737 bp (67% G؉C) arranged in a linear chromosome and three linear plasmids. A targeted insertion methodology was developed to determine the telomeric sequences. RHA1's 9,145 predicted protein-encoding genes are exceptionally rich in oxygenases (203) and ligases (192). Many of the oxygenases occur in the numerous pathways predicted to degrade aromatic compounds (30) or steroids (4). RHA1 also contains 24 nonribosomal peptide synthase genes, six of which exceed 25 kbp, and seven polyketide synthase genes, providing evidence that rhodococci harbor an extensive secondary metabolism. Among sequenced genomes, RHA1 is most similar to those of nocardial and mycobacterial strains. The genome contains few recent gene duplications. Moreover, three different analyses indicate that RHA1 has acquired fewer genes by recent horizontal transfer than most bacteria characterized to date and far fewer than Burkholderia xenovorans LB400, whose genome size and catabolic versatility rival those of RHA1. RHA1 and LB400 thus appear to demonstrate that ecologically similar bacteria can evolve large genomes by different means. Overall, RHA1 appears to have evolved to simultaneously catabolize a diverse range of plantderived compounds in an O2-rich environment. In addition to establishing RHA1 as an important model for studying actinomycete physiology, this study provides critical insights that facilitate the exploitation of these industrially important microorganisms.biodegradation ͉ actinomycete ͉ linear chromosome ͉ aromatic pathways ͉ oxygenase

Somatic missense mutations can initiate tumorogenesis and, conversely, anti-tumor cytotoxic T cell (CTL) responses. Tumor genome analysis has revealed extreme heterogeneity among tumor missense mutation profiles, but their relevance to tumor immunology and patient outcomes has awaited comprehensive evaluation. Here, for 515 patients from six tumor sites, we used RNA-seq data from The Cancer Genome Atlas to identify mutations that are predicted to be immunogenic in that they yielded mutational epitopes presented by the MHC proteins encoded by each patient’s autologous HLA-A alleles. Mutational epitopes were associated with increased patient survival. Moreover, the corresponding tumors had higher CTL content, inferred from CD8A gene expression, and elevated expression of the CTL exhaustion markers PDCD1 and CTLA4. Mutational epitopes were very scarce in tumors without evidence of CTL infiltration. These findings suggest that the abundance of predicted immunogenic mutations may be useful for identifying patients likely to benefit from checkpoint blockade and related immunotherapies.