Microarray profiling analysis of lncRNAs expression in renal cell carcinoma cells
Ontology highlight
ABSTRACT: Despite sunitinib contributes to prolong the progression-free survival of metastatic renal cell carcinoma significantly, the universal presence of resistance limits the initial response rate and restricts durable responses. The mechanisms involved in sunitinib resistance vary and need further investigation. We found lncRNA CCAT1 overexpressed in sunitinib resistant cells while declined in the parental cells. Moreover, lncRNA CCAT1 increased significantly in samples with resistance to sunitinib compared to those with responses to sunitinib. Impoverishment of CCAT1 suppressed cell growth and colony formation while triggered apoptosis. Inversely, the ectopic expression of c-Myc reversed the inhibition of cell growth and enhancement of apoptosis by sh-CCAT1. We also verified that anti-apoptosis protein Bcl-2 and Mcl-1 decreased along with the deregulation of CCAT1, whereas the expression of Bcl-2 and Mcl-1 restored in cells those were transfected sh-CCAT1 and c-Myc simultaneously. Apart from the in vitro experiments, we demonstrated that knockdown of CCAT1 boosted response to sunitinib by performing sunitinib-resistant ACHN mouse models. Briefly, lncRNA CCAT1 conferred renal cell carcinoma resistance to sunitinib in a c-Myc-dependent manner, providing novel target for improvement of sunitinib therapy.
Project description:Many traditional cytotoxic agents used in the treatment of cancer function by eliciting an apoptotic response in tumor cells. However, evasion of apoptosis by BCL-2 family members is often deregulated prior to therapeutic intervention leading to treatment failure. To address this, ABT-737 was rationally designed to target BCL-2-like family members and has shown promising results against tumor cells dependent on BCL-2 for their survival. One shortcoming is that MCL-1, a member of the BCL-2 family is poorly inhibited by ABT-737 and is a major cause of resistance. To gain insight into biological pathways that could circumvent this resistance, we designed an shRNA screen to identify novel sensitizers to ABT-737 by engineering MYC driven lymphomas that were resistant to ABT-737 due to endogenous MCL-1 expression. Utilizing this model, we performed a shRNA drop-out screen and identified Dhx9 as a target whose suppression sensitizes cells to ABT-737. DHX9 loss lead to replicative stress signaling, which in turn potently induced the BH3-only proteins, NOXA and PUMA, in a p53-dependent manner to curtail MCL-1 activity. Induction of NOXA is essential for ABT-737 sensitization. Our results ascribe a novel role for DHX9 in the replicative stress pathway and link DHX9 activity to p53 function in vivo. Comparison of Arf-/-Eu-myc/Bcl-2 lymphomas expressing either control Rluc.713 or Dhx9 shRNA, Dhx9.1241
Project description:Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. This data is from the lysate fraction of the secretomes described in PXD001476.
Project description:To determine the global transcriptome changes in mantle cell lymphoma cells following treatment with the BET bromodomain antagonist, JQ1 Mantle Cell Lymphoma (MCL) cells exhibit increased B cell receptor and NFkB activities. The BET protein BRD4 is essential for the transcriptional activity of NFkB. Here, we demonstrate that treatment with the BET protein bromodomain antagonist (BA) JQ1 attenuates MYC and CDK4/6, inhibits the nuclear RelA levels and the expression of NFκB target genes including Brutonâs Tyrosine Kinase (BTK) in MCL cells. While lowering the levels of the anti-apoptotic BCL2 family proteins, BA treatment induces the pro-apoptotic protein BIM and exerts dose-dependent lethality against cultured and primary MCL cells. Co-treatment with BA and the BTK inhibitor ibrutinib synergistically induces apoptosis of MCL cells. Compared to each agent alone, co-treatment with BA and ibrutinib markedly improved the median survival of mice engrafted with the MCL cells. BA treatment also induced apoptosis of the in vitro isolated, ibrutinib-resistant MCL cells which overexpress CDK6, BCL2, Bcl-xL, XIAP and AKT, but lack ibrutinib resistance-conferring BTK mutation. Co-treatment with BA and panobinostat (pan-histone deacetylase inhibitor) or palbociclib (CDK4/6 inhibitor) or ABT-199 (BCL2 antagonist) synergistically induced apoptosis of the ibrutinib-resistant MCL cells. These findings highlight and support further in vivo evaluation of the efficacy of the BA-based combinations with these agents against MCL, including ibrutinib-resistant MCL. MO2058 cells treated with vehicle, 250 nM or 1000 nM JQ1 for 8 hours. Samples were acquired and analyzed in duplicate.
Project description:CCAT1-L is a highly expressed long noncoding RNA located in the colorectal cancer specific super enhance region about 500 kb upstream of MYC gene. Knockdown of CCAT1-L significantly down-regulated interaction frequency between CCAT1 and MYC locus and repress MYC expression, suggesting a long-range chromatin interaction between CCAT1-L and MYC locus maintained by CCAT1-L underlie the MYC regulation. To further validate this hypothesis, multiplexed 3C sequencing (3C-seq) was employed to evaluate chromatin interaction strength between CCAT1-L and MYC locus in CCAT1-L knockdown and scramble knockdown (Scr) HT29 cells. The 3C-Seq design and data analysis were performed according to Stadhouders et al, Nat Protoc. 2013, 8:509-524. A series of bait sequences accommodating different locus around CCAT1-L and MYC were selected. Through integrating with specific sample barcodes, bait-specific primer sets were designed to construct relevant 3C-seq libraries in CCAT1-L knockdown and scramble knockdown (Scr) HT29 samples. All of the 3C sample libraries from different treatment, including CCAT1-L knockdown and scramble knockdown (Scr), were then pooled together for high-throughput sequencing. Two technical 3C-seq were performed (CCAT1_myc_3C_1.txt.gz and CCAT1_myc_3C_2.txt.gz) and then combined together to get enough reads for further analysis. 3C-seq reads from different samples were divided according to sample barcodes (CCAT1-L knockdown: ATGTCA; Scr: GCCAAT) and different bait sequences, and then mapped to human reference genome to assess chromatin interaction strength between CCAT1-L and MYC locus in different treatments. In our study, one representative bait-specific sequencing data (CTTCTACTGATTGGCCCTAAACACTTTTCCAAAGCTT) was select to generate bedgraph files and upload to UCSC for visualization to show the chromatin interaction between CCAT1-L and Myc locus in CCAT1-L knockdown (CCAT1-L_knockdown_out.bedgraph) and scramble knockdown (Scr_out.bedgraph) samples.
Project description:Many traditional cytotoxic agents used in the treatment of cancer function by eliciting an apoptotic response in tumor cells. However, evasion of apoptosis by BCL-2 family members is often deregulated prior to therapeutic intervention leading to treatment failure. To address this, ABT-737 was rationally designed to target BCL-2-like family members and has shown promising results against tumor cells dependent on BCL-2 for their survival. One shortcoming is that MCL-1, a member of the BCL-2 family is poorly inhibited by ABT-737 and is a major cause of resistance. To gain insight into biological pathways that could circumvent this resistance, we designed an shRNA screen to identify novel sensitizers to ABT-737 by engineering MYC driven lymphomas that were resistant to ABT-737 due to endogenous MCL-1 expression. Utilizing this model, we performed a shRNA drop-out screen and identified Dhx9 as a target whose suppression sensitizes cells to ABT-737. DHX9 loss lead to replicative stress signaling, which in turn potently induced the BH3-only proteins, NOXA and PUMA, in a p53-dependent manner to curtail MCL-1 activity. Induction of NOXA is essential for ABT-737 sensitization. Our results ascribe a novel role for DHX9 in the replicative stress pathway and link DHX9 activity to p53 function in vivo.
Project description:We showed that genetically double-knockdown of c-Myc/Bcl-2 synergistically killed AML cells and inhibited the growth of AML cells in vivo. Mechanically, co-targeting c-Myc/Bcl-2 reciprocally abrogated over-proliferation and apoptosis resistance via synergistically impairing mitochondrial biogenesis.
Project description:To determine the global transcriptome changes in mantle cell lymphoma cells following treatment with the BET bromodomain antagonist, JQ1 Mantle Cell Lymphoma (MCL) cells exhibit increased B cell receptor and NFkB activities. The BET protein BRD4 is essential for the transcriptional activity of NFkB. Here, we demonstrate that treatment with the BET protein bromodomain antagonist (BA) JQ1 attenuates MYC and CDK4/6, inhibits the nuclear RelA levels and the expression of NFκB target genes including Bruton’s Tyrosine Kinase (BTK) in MCL cells. While lowering the levels of the anti-apoptotic BCL2 family proteins, BA treatment induces the pro-apoptotic protein BIM and exerts dose-dependent lethality against cultured and primary MCL cells. Co-treatment with BA and the BTK inhibitor ibrutinib synergistically induces apoptosis of MCL cells. Compared to each agent alone, co-treatment with BA and ibrutinib markedly improved the median survival of mice engrafted with the MCL cells. BA treatment also induced apoptosis of the in vitro isolated, ibrutinib-resistant MCL cells which overexpress CDK6, BCL2, Bcl-xL, XIAP and AKT, but lack ibrutinib resistance-conferring BTK mutation. Co-treatment with BA and panobinostat (pan-histone deacetylase inhibitor) or palbociclib (CDK4/6 inhibitor) or ABT-199 (BCL2 antagonist) synergistically induced apoptosis of the ibrutinib-resistant MCL cells. These findings highlight and support further in vivo evaluation of the efficacy of the BA-based combinations with these agents against MCL, including ibrutinib-resistant MCL.
Project description:Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. We hypothesized that expression of apoptosis-related proteins in AML blasts, and possibly also in bystander cells in the bone marrow, is regulated by extracellular factors present in the AML microenvironment. Tumor cell communication with its microenvironment is emerging as an important determinant playing multiple roles in cancer. Both soluble factors and extracellular vesicles (EVs), most notably exosomes, have been shown to influence cellular processes of malignant and normal cells in the tumor microenvironment. We performed a proteomics analysis of the whole secretome as well as of EVs secreted by AML blasts to pinpoint released protein factors that might mediate apoptosis-resistance.
Project description:Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. Herein, we further explored this aspect of apoptosis in AML. Firstly, the intra-individual ex vivo apoptosis-related profiles of normal lymphocytes and AML blasts showed a strong correlation, with expression values far beyond control lymphocytes. Secondly, we demonstrated that apoptosis-resistant primary AML blasts, as opposed to apoptosis-sensitive cells, were able to up-regulate BCL-2 expression in sensitive AML blasts in contact cultures (p=0.0067 and p=1.0 respectively). Using proteomics we further set out to identify novel proteins possibly engaged in apoptosis regulation. Proteomics analysis revealed that major functional protein clusters upregulated in secretomes of apoptosis-resistant AML, were presumably engaged in global gene regulation including mRNA splicing, protein translation and chromatin remodeling.
Project description:Targeting BET bromodomain proteins utilizing small molecules in an emerging anti-cancer strategy with clinical evaluation of at least six inhibitors now underway. While MYC downregulation was initially proposed as a key mechanistic property of BET inhibitors, recent evidence suggests that additional anti-tumor activities are important. Using the Eμ-Myc model of B-cell lymphoma we demonstrate that BET inhibition with JQ1 is a potent inducer of p53-independent apoptosis that occurs in the absence of effects on Myc gene expression. JQ1 skews the expression of pro-apoptotic (Bim) and anti-apoptotic (BCL-2/BCL-xL) BCL-2 family members to directly engage the mitochondrial apoptotic pathway. Consistent with this, Bim knockout or Bcl-2 overexpression inhibited apoptosis induction by JQ1. We identified lymphomas that were either intrinsically resistant to JQ1-mediated death or acquired resistance following in vivo exposure. Strikingly, in both instances BCL-2 was strongly upregulated and was concomitant with activation of RAS pathways. Eμ-Myc lymphomas engineered to express activated Nras upregulated BCL-2 and acquired a JQ1-resistance phenotype. These studies provide important information on mechanisms apoptosis induction and resistance to BET-inhibition, while providing further rationale for the translation of BET inhibitors in aggressive B-cell lymphomas.