Project description:ABT-737 is a highly potent small molecule inhibitor of Bcl-2 which has demonstrated efficacy in preclinical studies. To identify factors which mediate ABT-737 sensitivity we created an ABT-737-resistant cell line derivative. This cell lines maintained its ABT-737 resistance in vitro and in vivo. We isolated RNA from H187-63AR xenografts and compared their global gene expression to H187 xenografts. Keywords: Tumor comparison
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: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:The chromosomal translocation t(11;14)(q13;q32) leading to cyclin-D1 over-expression plays an essential role in the development of mantle cell lymphoma (MCL), an aggressive tumor that remains incurable with current therapies. Cyclin-D1 has been postulated as an effective therapeutic target, but its evaluation has been hampered by our incomplete understanding of its oncogenic functions and by the lack of valid MCL murine models. To address these issues, we generated a cyclin-D1-driven mouse model whereby cyclin-D1 expression can be externally regulated. These mice developed lymphomas capable of recapitulating most features of human MCL. We found that cyclin-D1 inactivation was not sufficient to induce lymphoma regression in vivo. However, using a combination of in vitro and in vivo assays, we identified a novel pro-survival cyclin-D1 function in MCL cells. Specifically, we demonstrate that cyclin-D1 sequestrates the pro-apoptotic protein BAX, thereby favoring BCL2 anti-apoptotic function. Accordingly, cyclin-D1 inhibition sensitized the lymphoma cells to apoptosis through BAX release. Thus, genetic or pharmacologic targeting of cyclin-D1 combined with a pro-apoptotic BH3 mimetic synergistically killed murine lymphomas and human MCL cells. Our study identifies a novel role of cyclin-D1 in deregulating apoptosis and highlights the potential benefit of simultaneously targeting cyclin-D1 and survival pathways in patients with MCL. Dose response involving 20 samples. Two replicates for each cell line, 4 cell lines sensitive to ABT-737 and 6 cell lines resistant to ABT-737. Mantel cell lymphoma cell lines sensitive to ABT-737 vs. Mantel cell lymphoma cell lines resistant to ABT-737
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:RNA expression analysis was performed to compare patterns to sensitivity to BCL2 inhibitors (ABT-263). Overexpression of the prosurvival Bcl-2 family members (Bcl-2, Bcl-xL and Mcl-1) is commonly associated with tumor maintenance, progression and chemoresistance. We previously reported the discovery of ABT-737, a potent, small molecule Bcl-2 family protein inhibitor. A major limitation of ABT-737 is that it is not orally bioavailable. This may limit its use for chronic single agent treatment and the flexibility to dose in combination with parenteral chemotherapy. Here we report the discovery and biological properties of ABT-263, a potent, orally bioavailable Bad-like BH3 mimetic (Kiâ??s of < 1 nM for Bcl-2, Bcl-xL and Bcl-w). The oral bioavailability of ABT-263 in preclinical animal models is 20% - 50%, depending on formulation. ABT-263 disrupts Bcl-2/Bcl-xL interactions with pro-death proteins (e.g., Bim) in cells leading to the initiation of apoptosis within 2 hr post-treatment. In human tumor cells, ABT-263 rapidly induces Bax translocation, cytochrome c release and subsequent programmed cell death. Oral administration of ABT-263 alone induces complete tumor regressions in xenograft models of small cell lung cancer and acute lymphoblastic leukemia. In xenograft models of aggressive B-cell lymphoma and multiple myeloma where ABT-263 exhibits modest or no single agent activity, it significantly enhances the efficacy of clinically relevant therapeutic regimens. These data provide the rationale for clinical trials evaluating ABT-263 in SCLC and B-cell malignancies. The oral efficacy of ABT-263 should provide dosing flexibility to maximize clinical utility as both a single agent and in combination with standard chemotherapeutic regimens. Experiment Overall Design: Naive cell lines were isolated in duplicate or triplicate (only a single for H69AR) to determine RNA expression pattern.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs. One-condition experment, gene expression of 3A6