Project description:Tumor initiation and progression are critically dependent on interaction of cancer cells with their cellular and extracellular microenvironment. Alterations in the composition, integrity, and mechanical properties of the extracellular matrix (ECM) dictate tumor processes including proliferation, migration, and invasion. Also in primary liver cancers, consisting of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), the dysregulation of the extracellular environment by liver fibrosis and tumor desmoplasia is pertinent. Yet, in-depth characterization of liver cancer ECM and underlying tumor-promoting mechanisms remain largely unknown. Herein, we used an integrative molecular and mechanical approach to extensively characterize the ECM of HCC and CCA tumors by utilizing decellularization techniques. We identified a myriad of ECM-related proteins in both tumor and adjacent liver tissue, highlighting the complexity of the primary liver cancer matrisome. The differences in ECM protein abundance result in divergent mechanical properties on a macro- and micro-scale that is tumor-type specific. Furthermore, we employed the decellularized tumor ECM to create a tumor-specific hydrogel that support patient-derived tumor organoids. This provides a new avenue for personalized medicine by combining patient-derived tumor ECM and cancer cells. Taken together, this study provides better understanding of alterations to key aspects of the ECM that occur during primary liver cancer development.
Project description:The mechanical microenvironment of primary breast tumors plays a substantial role in promoting tumor progression. While the transitory response of cancer cells to pathological stiffness in their native microenvironment has been well described, it is unclear whether mechanical stimuli in the primary tumor influence distant, late-stage metastatic phenotypes in absentia. Here, we show that primary tumor stiffness promotes stable yet non-genetically heritable phenotypes in breast cancer cells. This “mechanical memory” instructs cancer cells to adopt and maintain increased cytoskeletal dynamics, traction force, and 3D invasion in vitro, in addition to promoting osteolytic bone metastasis in vivo. We established a “mechanical conditioning score” comprised of mechanically-regulated genes as a proxy measurement of tumor stiffness response, and we show that it is associated with bone metastasis in patients. Using a discovery approach, we mechanistically traced mechanical memory in part to ERK-mediated mechanotransductive activation of RUNX2, an osteogenic gene bookmarker and bone metastasis driver. This combination of traits allows for the stable transactivation of osteolytic target genes which persists after cancer cells disseminate from their activating microenvironment. Using genetic, epigenetic, and functional approaches, RUNX2-mediated mechanical memory can be stimulated, repressed, selected, or extended. In concert with previous studies detailing how biochemical properties of the primary tumor stroma influence distinct metastatic phenotypes, the impact of local biomechanical properties we present here support a generalized model of cancer progression in which the integrated properties of the primary tumor microenvironment govern cell behavior in the metastatic microenvironment.
Project description:Cancer originates as the progressive accumulation of genetic mutations in proto-oncogenes and tumor suppressors. However, the early events underlying tumor initiation remain largely elusive, mostly due to the general lack of information regarding the cells-of-origin responsible for tumor formation as well as the precise impacts of genetic insults on tumor initiation in vivo. Here, we demonstrate that Sox2-positive (Sox2+) adult stem cells are responsible for epithelial squamous tumor formation. Conditional expression of oncogenic Kras (KrasG12D) and knockout of p53 (also known as Trp53) in Sox2+ cells quickly and specifically resulted in the formation of squamous tumors in the forestomach and esophagus. GFP-based lineage tracing experiments demonstrated that Sox2+ cells are the cells-of-origin of squamous tumors in the esophagus and forestomach. Of note, our data showed that p53 deletion alone did not suffice for tumor initiation. On the contrary, tumor initiation was observed upon KrasG12D activation whereas p53 deletion further contributed to the malignancy of the generated tumors, pointing out distinct roles for Kras activation and p53 deletion in squamous tumor formation and progression, to which a multihit carcinogenesis model can be applied. Global gene expression analysis revealed secreting factors upregulated in the generated tumors induced by oncogenic Kras, which contribute to tumor progression. Taken together, these results demonstrate that epithelial squamous tumors can specifically originate as a consequence of defined genetic mutations in a Sox2+ cell population and highlight the connections between proliferative stem cells and tumor development in vivo.
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. ChIP-Seq for chromatin regulators and RNA Polymerase II in multiple myeloma, glioblastoma multiforme, and small cell lung cancer
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. Gene expression profiling in multiple myeloma cells after BET-Bromodomain inhibition with JQ1
Project description:Oncogenes can only initiate tumors in certain cellular contexts, which is referred to as oncogenic competence. In melanoma, whether cells in the microenvironment can endow such competence remains unclear. Using a combination of zebrafish transgenesis coupled with human tissues, we demonstrate that GABAergic signaling between keratinocytes and melanocytes promotes melanoma initiation by BRAFV600E. GABA is synthesized in melanoma cells, which then acts on GABA-A receptors on keratinocytes. Electron microscopy demonstrates specialized cell-cell junctions between keratinocytes and melanoma cells, and multi-electrode array analysis shows that GABA acts to inhibit electrical activity in melanoma/keratinocyte co-cultures. Genetic and pharmacologic perturbation of GABA synthesis abrogates melanoma initiation in vivo. These data suggest that GABAergic signaling across the skin microenvironment regulates the ability of oncogenes to initiate melanoma.
Project description:Most of the gas exchange in the human body is carried out by the lungs, and the physiological activities of the lungs are uninterrupted. Due to the deterioration of the external environment, pulmonary cell lesions are common clinical lung diseases. Mechanical cyclic stretching is one kind of bionic technology to observe lung cancer cells. The A549 cell line is the human lung adenocarcinoma cell line derived from a primary lung tumor. This study investigated the effects of mechanical cyclic stretching on A549 cell activity and gene expression profile. Whereas mechanical cyclic stretching had no significant difference in colony formation and cell migration of A549 cells, the cell invasion increased significantly in A549 cells after stretching. In addition, the microarray data showed that mechanical cyclic stretching altered gene expression, induced inflammation of cells, and activation of Wnt/β-catenin and tumor necrosis factor pathways. More importantly, mechanical cyclic stretching activated the expression of tumor necrosis factor-alpha (TNF-α) protein. Therefore, the increase of cell invasion induced by mechanical cyclic stretching might be associated with the activation of TNF-α in human lung adenocarcinoma cells.