Project description:Fifty percent of cutaneous melanomas are driven by activated BRAFV600E, but tumors treated with RAF inhibitors, even when they respond dramatically, rapidly adapt and develop resistance. Thus, there is a pressing need to identify the major mechanisms of intrinsic and adaptive resistance and develop drug combinations that target these resistance mechanisms. In a combinatorial drug screen on a panel of 12 treatment-naïve BRAFV600E mutant melanoma cell lines of varying levels of resistance to MAPK pathway inhibition we identified the combination PLX4720, a targeted inhibitor of mutated BRaf, and lapatinib, an inhibitor of the ERBB family of receptor tyrosine kinases, as synergistically cytotoxic in the subset of cell lines that displayed the most resistance to PLX4720. To identify potential mechanisms of resistance to PLX4720 treatment and synergy with lapatinib treatment we performed a multi-platform functional genomics analysis to profile the genome as well as the transcriptional and proteomic responses of these cell lines to treatment with PLX4720. We found modest levels of resistance correlated with the zygosity of the BRAF V600E allele and RTK mutational status. Layered over base-line resistance was substantial upregulation of many ERBB pathway genes in response to BRaf inhibition, thus generating the vulnerability to combination with lapatinib. The transcriptional responses of ERBB pathway genes are associated with a number of transcription factors, including ETS2 and its associated cofactors that represent a convergent regulatory mechanism conferring synergistic drug susceptibility in the context of diverse mutational landscapes. 12 BRAF mutant melanomas and 4 melanomas with WT BRAF were exposed plx4720 treatment to evaluate their responses after 8 hours of treatment. 5 of the 12 BRAF mutant melanomas responses were also evaluated in response to the treatment of lapatinib alone, masitinib alone, the combination of lapatinib with plx4720, or the combination of masitinib with plx4720. All samples were run in at least triplicate.
Project description:Colon cancer cell lines with partial sensitivity to the BRAF inhibitor PLX4720 were grown in increasing concentration of the drug to develop acquired resistance. Gene expression was performed for comparison of the resistant clones to the parental lines. Colon cancer cell lines with partial sensitivity to the BRAF inhibitor PLX4720 were grown in increasing concentration of the drug to develop acquired resistance. Gene expression was performed for comparison of the resistant clones to the parental lines.
Project description:A375P melanoma cells were treated with 1uM of the MEK inhibitor PD184352 or 0.4uM of the V600EBRAF inhibitor PLX4720 for 2hr, 6hr and 24hrs. DMSO treatment for 2hr, 6hr and 24hrs serves as the negative control Triplicate experiments were performed for DMSO, PD184352 and PLX4720 treatment at 3 timepoints - 2, 6, 24hrs.
Project description:Mutations in the BRAF proto-oncogene, which encodes the B-Raf kinase, are associated with more aggressive, less-differentiated and therapy-resistant colorectal cancers (CRC). However, the molecular mechanisms responsible for these correlations remain unknown. Here, we report the characterization of human isogenic CRC cell line models (Caco-2, HT29, Colo-205) in which we modulate the expression of the B-RafV600E oncoprotein either by conditional cDNA or shRNA expression. Using these models in conventional and three dimensional tissue culture systems, we demonstrate that genetic depletion of endogenous B-RafV600E decreases cellular motility and invasion, while it induces hallmarks of differentiated epithelia such as the formation of functional adherens and tight junctions. Importantly, these effects are recapitulated by exposing these lines to B-Raf (PLX4720, vemurafenib, dabrafenib) or MEK inhibitors (trametinib). Furthermore, loss of endogenous B-RafV600E in HT29 xenografts does not only stall tumor growth, but also induces epithelial structures with marked expression of Cdx-2, a prognostic marker and master regulator of intestinal morphogenesis. By performing the first transcriptome profiles of B-Raf inhibitor treated 3D cultures of a primary adenocarcinoma and a metastasis derived CRC cell line, we establish functional links between B-RafV600E and proteins of known and potentially new prognostic relevance. We propose that B-Raf/MEK/ERK pathway inhibitors could be used to induce CRC differentiation and thereby to limit metastatic disease. To measure the time resolved gene responses, RNA was isolated from PLX4720 or DMSO treated Colo-205 and HT29 3D culture cell lysates at days 1,3 and 10 and days 1,3, and 8, respectively. The time points for HT29 cells were taken in biological duplicates.
Project description:GATA2 is a pivotal hematopoietic transcription factor required for generation and maintenance of hematopoietic stem cells (HSCs). Due to early embryonic lethality of Gata2 deficiency in mice, its role during adult hematopoiesis is incompletely understood. In zebrafish, mammalian functions of Gata2 are split between two orthologues: Gata2a and Gata2b. Previous studies have shown that Gata2b is prominently expressed in hematopoietic stem and progenitor cells (HSPCs), whereas Gata2a is mainly expressed in the vasculature. We found that Gata2b deficient zebrafish have a reduction in embryonic definitive HSPC numbers and have impaired myeloid lineage differentiation, but are viable. This allowed us to study the role of Gata2b in adult hematopoiesis. To assess the impact of Gata2b deficiency on the transcriptional profile of HSPCs and differentiated cells, we sorted the entire progenitor and HSPC population including the lymphoid population from kidney marrow (KM) of WT and germline Gata2b deficient zebrafish based on scatter profiles and processed for single-cell RNA sequencing. To enrich the scarce HSC population, we used pooled KM from two WT and Gata2b deficient Tg(CD41:GFP) zebrafish per sample and included all CD41:GFPlow expressing cells present in the kidney marrow pool as these cells were shown to contain transplantable HSCs.
Project description:CD4 T cells are essential mediators of the asthmatic process. We used the clinically relevant allergen house dust mites to induce signs of allergy in mice and performed gene expression arrays specifically on CD4 T cells infiltrating the lung Reference: IL-21-producing CD4+ T cells promote type 2 immunity to house dust mites Primary CD4+ T cells were isolated from mice sensitised and challenged to either house dust mites or PBS. Purification of CD4 T cells was performed by flow cytometry. RNA was isolated, converted to cDNA and then hybridised on Affymetrix GeneChip Mouse Gene 2.0 ST Arrays
Project description:Multiciliated cells (MCCs) possess multiple motile cilia on the cell surface and are widely distributed throughout the vertebrate body to perform important physiological functions by regulating fluid movement in the intercellular space. However, neither their function during organ development nor the molecular mechanisms underlying multiciliogenesis are yet well understood. We aim to study the function of miR-34b in multiciliogenesis. We used microarrays to study the global gene expression change in multiciliated cells after miR-34b knockdown. Multiciliated cells were isolated from 3 dpf control embryos (injected with control morpholino) and miR-34b morphants (injected with miR-34b morpholino) for RNA extraction and hybridization on Affymetrix microarrays. Two independent sets of biological replicates were used.
Project description:Background:; Yersinia outer protein (Yop) H is a secreted virulence factor of Yersinia enterocolitica which inhibits phagocytosis of Y. enterocolitica and promotes virulence of Y. enterocolitica (Ye) in mice. The aim of this study was to address whether and how YopH affects the innate immune response against Ye in mice. Results:; For this purpose mice were infected with wild type Ye (pYV+) or a YopH-deficient Ye mutant strain (DyopH). CD11b+ cells were isolated from infected spleen and subjected to gene expression analysis using microarrays. Despite attenuation of DyopH in vivo, by variation of infection doses we were able to achieve conditions that allow comparison of gene expression in pYV+ and DyopH infections at either comparable infection courses or splenic bacterial burden. Gene expression analysis provided evidence that expression levels of several immune response genes including IFN-g and IL-6 are high after pYV+ infection but low after sublethal DyopH infection. In line with these findings, infection of IFN-gR-/- and IL-6-/- mice with pYV+ or DyopH revealed that these cytokines are dispensable for control of DyopH, but not pYV+ infection. Consistently, in bacteria killing assays with BMM in vitro, stimulation of BMM with IFN-g is required for killing of pYV+ but not DyopH. Conclusion:; In conclusion, this data suggest that IFN-g counteracts YopH-mediated virulence mechanisms of Ye which in Ye wild type infection contribute to evasion of the innate immune response including killing by macrophages. Experiment Overall Design: In this study microarray analyses were performed to define differences in gene expression of cells associated with innate immune response (CD11b+ cells) after infection of mice with a sublethal and lethal infection with wildtype Yersinia enterocolitica compared to uninfected mice. In addition, we wanted to investigate whether differences in gene expression can be defined which are due to the virulence factor YopH. Moroeover, we were interested whether gene expression pattern of sublethal and lethal infected mice are different. Allover all five samples were compared. Number of replicates 1.
Project description:Multiciliated cells possess multiple motile cilia on the cell surface and are widely distributed throughout the vertebrate body to perform important physiological functions by regulating fluid movement in the intercellular space. However the molecular mechanisms underlying multiciliogenesis are not well understood. Although dysregulation of members of the miR-34 family plays a critical role in the progression of various cancers, the physiological function of miR-34b, especially in regulating multiciliogenesis, is largely unknown. Here we focus on the multiciliated cells in the zebrafish kidney to study whether and how miR-34b regulate multiciliogenesis. We performed genome-wide gene expression profiling of zebrafish kidney multiciliated cells in the absence (miR-34b morpholino) or presence of miR-34b (control morpholino). RNA samples for microarray gene expression profiling were collected at 3 days post fertilization.
Project description:We generated four drug-resistant melanoma cell lines from paired primary/metastatic cell lines using PLX4720 and used for Affymetrix Human Gene 1.0 ST array