Human cancers are complex ecosystems composed of cells with distinct phenotypes, genotypes and epigenetic states, but current models do not adequately reflect tumor composition in patients. We used single cell RNA-seq to profile 430 cells from five primary glioblastomas, which we found to be inherently variable in their expression of diverse transcriptional programs related to oncogenic signaling, proliferation, complement/immune response and hypoxia. We also observed a continuum of stemness-related expression states that enabled us to identify putative regulators of stemness in vivo. Finally, we show that established glioblastoma subtype classifiers are variably expressed across individual cells within a tumor and demonstrate the potential prognostic implications of such intratumoral heterogeneity. Thus, we reveal previously unappreciated heterogeneity in diverse regulatory programs central to glioblastoma biology, prognosis, and therapy.Tumor heterogeneity poses a major challenge to cancer diagnosis and treatment. It can manifest as variability between tumors, wherein different stages, genetic lesions or * Corresponding authors: Bernstein.bradley@mgh.harvard.edu (BEB), aregev@broadinstitute.org (AR), Suva.Mario@mgh.harvard.edu (MLS). † These authors contributed equally to this work. ‡ These authors contributed equally to this work. Glioblastoma is an archetypal example of a heterogeneous cancer and one of the most lethal human malignancies (9, 10). Intratumoral heterogeneity and redundant signaling routes likely underlie the inability of conventional and targeted therapies to achieve long-term remissions (11-13). These tumors contain cellular niches enriched for distinct phenotypic properties, including transient quiescence and self-renewal (14-16), adaptation to hypoxia (17), and resistance to radiation induced DNA damage (18,19). DNA and RNA profiles of bulk tumors have enabled genetic and transcriptional classification of glioblastomas (20,21). However, the relationships between different sources of intratumoral heterogeneitygenetic, transcriptional and functional -remain obscure.Single cell transcriptome analysis by 23) should in principle enable functional characterization from landmark genes and annotated gene sets, relate in vivo states to in vitro models, inform transcriptional classifications based on bulk tumors, and even capture genetic information for expressed transcripts. To interrogate intratumoral heterogeneity systematically, we isolated individual cells from five freshly resected and dissociated human glioblastomas and generated single cell full-length transcriptomes using SMART-seq (96-192 cells/tumor, total 672 cells; Fig. 1A). Prior to sorting, the suspension was depleted for CD45 + cells to remove inflammatory infiltrate. As a control, we also generated population (bulk) RNA-seq profiles from the CD45-depleted tumor samples. All tumors were IDH1/2 wild type primary glioblastomas ( Fig. S1) and three were EGFR amplified as determined by routine clinical tests (Table S1). We exclude...

Cancers arise owing to mutations in a subset of genes that confer growth advantage. The availability of the human genome sequence led us to propose that systematic resequencing of cancer genomes for mutations would lead to the discovery of many additional cancer genes. Here we report more than 1,000 somatic mutations found in 274 megabases (Mb) of DNA ©2007 Nature Publishing Group Correspondence and requests for materials should be addressed to P. A.F. (paf@sanger.ac.uk) or M.R.S. (mrs@sanger.ac.uk).. Supplementary Information is linked to the online version of the paper at www.nature.com/nature.Reprints and permissions information is available at www.nature.com/reprints.The authors declare no competing financial interests. Europe PMC Funders GroupAuthor Manuscript Nature. Author manuscript; available in PMC 2009 July 20. Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts corresponding to the coding exons of 518 protein kinase genes in 210 diverse human cancers. There was substantial variation in the number and pattern of mutations in individual cancers reflecting different exposures, DNA repair defects and cellular origins. Most somatic mutations are likely to be 'passengers' that do not contribute to oncogenesis. However, there was evidence for 'driver' mutations contributing to the development of the cancers studied in approximately 120 genes. Systematic sequencing of cancer genomes therefore reveals the evolutionary diversity of cancers and implicates a larger repertoire of cancer genes than previously anticipated.Cancers are clonal proliferations that arise owing to mutations that confer selective growth advantage on cells. The mutated genes that are causally implicated in cancer development are known as 'cancer genes' and more than 350 have thus far been identified (ref. 1 and http://www.sanger.ac.uk/genetics/CGP/Census/). Cancer genes have been identified by several different physical and genetic mapping strategies, by biological assays and as plausible biological candidates. Each of these approaches has identified a subset of cancer genes, leaving the possibility that others have been overlooked. The provision of the human genome sequence, therefore, led to the proposal that systematic resequencing of cancer genomes could reveal the full compendium of mutations in individual cancers and hence identify many of the remaining cancer genes2.Somatic mutations occur in the genomes of all dividing cells, both normal and neoplastic. They may occur as a result of misincorporation during DNA replication or through exposure to exogenous or endogenous mutagens. Cancer genomes carry two biological classes of somatic mutation arising from these various processes. 'Driver' mutations confer growth advantage on the cell in which they occur, are causally implicated in cancer development and have therefore been positively selected. By definition, these mutations are in 'cancer genes'. Conversely, 'passenger' mutations have not been subject to selection. They were present in the cell that wa...