Project description:Crosstalk and complexity within signaling pathways has limited our ability to devise rational strategies for using network biology to treat human disease. This is particularly problematic in cancer where oncogenes that drive or maintain the tumorigenic state alter the normal flow of molecular information within signaling networks that control growth, survival and death. Understanding the architecture of oncogenic signaling pathways, and how these networks are re-wired by ligands or drugs, could provide opportunities for the specific targeting of oncogene-driven tumors. Here we use a systems biology-based approach to explore synergistic therapeutic strategies to optimize the killing of triple negative breast cancer cells, an incompletely understood tumor type with a poor treatment outcome. Using targeted inhibition of oncogenic signaling pathways combined with DNA damaging chemotherapy, we report the surprising finding that time-staggered EGFR inhibition, but not simultaneous co-administration, can dramatically sensitize the apoptotic response of a subset of triple-negative cells to conventional DNA damaging agents. A systematic analysis of the order and timing of inhibitor/genotoxin presentation—using a combination of high-density time-dependent activity measurements of signaling networks, gene expression profiles, cell phenotypic responses, and mathematical modeling—revealed an approach for altering the intrinsic oncogenic state of the cell through dynamic re-wiring of oncogenic signaling pathways. This process converts these cells to a less tumorigenic state that is more susceptible to DNA damage-induced cell death, through re-activation of an extrinsic apoptotic pathway whose function is suppressed in the oncogene-addicted state. Three or 4 replicates of 3 different cell lines at time points 0minutes, 30minutes, 6 hours and 1 day after EGFR inhibition with erlotinib
Project description:Crosstalk and complexity within signaling pathways has limited our ability to devise rational strategies for using network biology to treat human disease. This is particularly problematic in cancer where oncogenes that drive or maintain the tumorigenic state alter the normal flow of molecular information within signaling networks that control growth, survival and death. Understanding the architecture of oncogenic signaling pathways, and how these networks are re-wired by ligands or drugs, could provide opportunities for the specific targeting of oncogene-driven tumors. Here we use a systems biology-based approach to explore synergistic therapeutic strategies to optimize the killing of triple negative breast cancer cells, an incompletely understood tumor type with a poor treatment outcome. Using targeted inhibition of oncogenic signaling pathways combined with DNA damaging chemotherapy, we report the surprising finding that time-staggered EGFR inhibition, but not simultaneous co-administration, can dramatically sensitize the apoptotic response of a subset of triple-negative cells to conventional DNA damaging agents. A systematic analysis of the order and timing of inhibitor/genotoxin presentation—using a combination of high-density time-dependent activity measurements of signaling networks, gene expression profiles, cell phenotypic responses, and mathematical modeling—revealed an approach for altering the intrinsic oncogenic state of the cell through dynamic re-wiring of oncogenic signaling pathways. This process converts these cells to a less tumorigenic state that is more susceptible to DNA damage-induced cell death, through re-activation of an extrinsic apoptotic pathway whose function is suppressed in the oncogene-addicted state.
Project description:We utilized high resolution, high mass accuracy quantitative proteomics to explore stress signaling in yeast. We accessed changes in protein phosphorylation at various time points after exposure to salt stress and used this information to reconstruct stress signaling networks. We performed similar experiments using yeast knockouts to monitor network re-wiring and performed co-IPs to validate protein-protein interactions predicted by the networks.
Project description:Background: Epithelial-stromal crosstalk plays a critical role in invasive breast cancer (IBC) pathogenesis; however, little is known on a systems level about how epithelial-stromal interactions evolve during carcinogenesis. Results: We develop a framework for building genome-wide epithelial-stromal co-expression networks composed of pairwise co-expression relationships between mRNA levels of genes expressed in the epithelium and stroma across a population of patients. We apply this method to laser capture micro-dissection expression profiling datasets in the setting of breast carcinogenesis. Our analysis shows that epithelial-stromal co-expression networks undergo extensive re-wiring during carcinogenesis, with the emergence of distinct network hubs in normal breast, ER-positive IBC, and ER-negative IBC, and the emergence of distinct patterns of functional network enrichment. In contrast to normal breast, the strongest epithelial-stromal co-expression relationships in IBC mostly represent self-loops, in which the same gene is co-expressed in epithelial and stromal regions. We validate this observation using an independent laser capture micro-dissection dataset and confirm that self-loop interactions are significantly increased in cancer by performing computational image analysis of epithelial and stromal protein expression using images from the Human Protein Atlas. Conclusions: Epithelial-stromal co-expression network analysis represents a new approach for systems-level analyses of spatially-localized transcriptomic data. The analysis provides new biological insights into the re-wiring of epithelial-stromal co-expression networks and the emergence of epithelial-stromal co-expression self-loops in breast cancer. The approach may facilitate the development of new diagnostics and therapeutics targeting epithelial-stromal interactions in cancer. 36 flash-frozen human primary breast cancer samples were subjected to laser capture microdissection to separately isolate matched tumor epithelial and tumor-associated stromal components. RNA was isolated, subjected to 2 rounds of amplification, and hybridized on Agilent 4x44K microarrays along with a common reference (single round-amplified commercially obtained Universal Human Reference RNA) in a dyeswap design. For two samples of tumor-associated stroma, a second technical replicate was performed. Samples were labelled as ER-positive based on ESR1 gene expression levels in the tumor epithelium, using univariate Gaussian mixture model-based clustering via the mclust package in R.
Project description:Granzyme B plays a key role in cell-mediated programmed cell death. We previously demonstrated that p53 is a functional determinant in the Granzyme B-induced cytotoxic T lymphocyte response. However, the pathways leading to activation of p53 by Granzyme B remain incompletely understood. We now demonstrate that Granzyme B induced DNA damage signaling as revealed by histone H2AX phosphorylation and subsequent activation of the stress kinase CHK2. Confocal microscopy analysis indicates that Granzyme B treatment of tumor cells induced an early translocation of endonuclease caspase-activated DNase. DNA microarray based global transcriptional profiling and RT-PCR indeed revealed genes related to DNA damage. Among these genes, hSMG-1, a genotoxic stress-activated protein, was constantly upregulated in tumor cells following Granzyme B treatment. Knockdown of the hSMG-1 gene in T1 tumor target cell line resulted in a significant inhibition of Granzyme B- and CTL-induced killing. Our data suggest that Granzyme B may exert cell death through DNA damage signaling and uncover a novel molecular link between the DNA damage pathway and Granzyme B-induced cell death.
Project description:Tumor heterogeneity is a major barrier to cancer therapy, including immunotherapy. Activated T cells can efficiently kill tumor cells following recognition of MHC class I (MHC-I) bound peptides, but this selection pressure favors outgrowth of MHC-I deficient tumor cells. We performed a genome-scale screen to discover alternative pathways for T cell-mediated killing of MHC-I deficient tumor cells. Autophagy and TNF signaling emerged as top pathways, and inactivation of Rnf31 (TNF signaling) and Atg5 (autophagy) sensitized MHC-I deficient tumor cells to apoptosis by T cell-derived cytokines. Mechanistic studies demonstrated that inhibition of autophagy amplified pro-apoptotic effects of cytokines in tumor cells. Antigens from apoptotic MHC-I deficient tumor cells were efficiently cross-presented by dendritic cells, resulting in heightened tumor infiltration by IFNg and TNFa-producing T cells. Tumors with a substantial population of MHC-I deficient cancer cells could be controlled by T cells when both pathways were targeted using genetic or pharmacological approaches.
Project description:Plasmacytoid dendritic cells (pDCs) are a subset of DCs that act as important modulators of anti-tumor immune responses. pDCs have been associated with poor prognosis of tumor patients. Despite this, upon TLR7 activation, pDCs have also been shown to acquire tumor killing capacities, and we previously provided evidence on the role of activated pDCs in eliminating tumor cells in vivo, independently of adaptive immunity. In this study we investigated the mechanism by which pDCs acquire tumor-killing capacities following TLR7/8 triggering by Imiquimod (IMQ). By combining pathway perturbation and analysis of transcriptome, surfaceome, secretome, and killing function, we identified the MAPKs and NF-kB pathways as important downstream mediators of the tumor-killing ability of these cells. JNK inhibition reduces killing by secreted factors whereas p38 or NF-kB inhibition enhances cell mediated killing. Analysis of surface and secreted proteins revealed differential control of expression and secretion by IFN-I/-II, MAPK and NF-kB, while indicating that a complex signaling network is necessary to shape the cytotoxic phenotype of activated pDCs. Our integrated analysis converged on a new pDCs killing gene signature that is predictive of survival in cohorts of melanoma patients. These newly identified markers will be instructive for the rationale design and interpretation of further single-cell and functional approaches aimed at studying the role of pDCs in the tumor microenvironment. These might pinpoint novel strategies to improve cancer management and treatment, by modulating the pDCs pro- vs anti-tumorigenic functions.
Project description:Peroxisome Proliferator-Activated Receptor gamma (PPARG) is a nuclear receptor transcription factor critical for placental development. Using human trophoblast stem cells (TSCs) and their differentiation into extravillous trophoblasts (EVTs) as a model, we show that PPARG is required for both TSC self-renewal and EVT differentiation. ChIP-seq revealed that PPARG occupies distinct sets of regulatory elements in TSCs and EVTs, forming cell-type specific transcriptional networks. Integration with other trophoblast-specific transcription factors suggests that PPARG participates in transcriptional re-wiring during EVT differentiation. Functionally, activation of PPARG promotes EVT invasion, suggesting a potential connection between PPARG signaling and placental pathologies such as placenta accreta. These findings highlight context-specific roles of PPARG in modulating gene expression and cell behavior during human trophoblast development.
Project description:Peroxisome Proliferator-Activated Receptor gamma (PPARG) is a nuclear receptor transcription factor critical for placental development. Using human trophoblast stem cells (TSCs) and their differentiation into extravillous trophoblasts (EVTs) as a model, we show that PPARG is required for both TSC self-renewal and EVT differentiation. ChIP-seq revealed that PPARG occupies distinct sets of regulatory elements in TSCs and EVTs, forming cell-type specific transcriptional networks. Integration with other trophoblast-specific transcription factors suggests that PPARG participates in transcriptional re-wiring during EVT differentiation. Functionally, activation of PPARG promotes EVT invasion, suggesting a potential connection between PPARG signaling and placental pathologies such as placenta accreta. These findings highlight context-specific roles of PPARG in modulating gene expression and cell behavior during human trophoblast development.