搜索结果: 'methocult media formulations for human hematopoietic cells serum containing'

BACKGROUND: The mitomycins are natural products that contain a variety of functional groups,including aminobenzoquinone- and aziridine-ring systems. Mitomycin C (MC) was the first recognized bioreductive alkylating agent,and has been widely used clinically for antitumor therapy. Precursor-feeding studies showed that MC is derived from 3-amino-5-hydroxybenzoic acid (AHBA),D-glucosamine,L-methionine and carbamoyl phosphate. A genetically linked AHBA biosynthetic gene and MC resistance genes were identified previously in the MC producer Streptomyces lavendulae NRRL 2564. We set out to identify other genes involved in MC biosynthesis. RESULTS: A cluster of 47 genes spanning 55 kilobases of S. lavendulae DNA governs MC biosynthesis. Fourteen of 22 disruption mutants did not express or overexpressed MC. Seven gene products probably assemble the AHBA intermediate through a variant of the shikimate pathway. The gene encoding the first presumed enzyme in AHBA biosynthesis is not,however,linked within the MC cluster. Candidate genes for mitosane nucleus formation and functionalization were identified. A putative MC translocase was identified that comprises a novel drug-binding and export system,which confers cellular self-protection on S. lavendulae. Two regulatory genes were also identified. CONCLUSIONS: The overall architecture of the MC biosynthetic gene cluster in S. lavendulae has been determined. Targeted manipulation of a putative MC pathway regulator led to a substantial increase in drug production. The cloned genes should help elucidate the molecular basis for creation of the mitosane ring system,as well efforts to engineer the biosynthesis of novel natural products. View Publication

PURPOSE: Despite their preclinical promise,previous MEK inhibitors have shown little benefit for patients. This likely reflects the narrow therapeutic window for MEK inhibitors due to the essential role of the P42/44 MAPK pathway in many nontumor tissues. GSK1120212 is a potent and selective allosteric inhibitor of the MEK1 and MEK2 (MEK1/2) enzymes with promising antitumor activity in a phase I clinical trial (ASCO 2010). Our studies characterize GSK1120212' enzymatic,cellular,and in vivo activities,describing its unusually long circulating half-life. EXPERIMENTAL DESIGN: Enzymatic studies were conducted to determine GSK1120212 inhibition of recombinant MEK,following or preceding RAF kinase activation. Cellular studies examined GSK1120212 inhibition of ERK1 and 2 phosphorylation (p-ERK1/2) as well as MEK1/2 phosphorylation and activation. Further studies explored the sensitivity of cancer cell lines,and drug pharmacokinetics and efficacy in multiple tumor xenograft models. RESULTS: In enzymatic and cellular studies,GSK1120212 inhibits MEK1/2 kinase activity and prevents Raf-dependent MEK phosphorylation (S217 for MEK1),producing prolonged p-ERK1/2 inhibition. Potent cell growth inhibition was evident in most tumor lines with mutant BRAF or Ras. In xenografted tumor models,GSK1120212 orally dosed once daily had a long circulating half-life and sustained suppression of p-ERK1/2 for more than 24 hours; GSK1120212 also reduced tumor Ki67,increased p27(Kip1/CDKN1B),and caused tumor growth inhibition in multiple tumor models. The largest antitumor effect was among tumors harboring mutant BRAF or Ras. CONCLUSIONS: GSK1120212 combines high potency,selectivity,and long circulating half-life,offering promise for successfully targeting the narrow therapeutic window anticipated for clinical MEK inhibitors. View Publication

Molluscum contagiosum poxvirus (MCV) type 1 and type 2 encode two chemokine-like proteins MC148R1 and MC148R2. It is believed that MC148R proteins function by blocking the inflammatory response. However,the mechanism of the proposed biological activities of MC148R proteins and the role of the additional C-terminal cysteines that do not exist in other chemokines are not understood. Here,we demonstrated in two different assay systems that His-tagged MC148R1 displaces the interaction between CXCL12α and CXCR4. The N-terminal cysteines but not the additional C-terminal cysteines modulate this displacement. His-tagged MC148R1 blocked both CXCL12α-mediated and MIP-1α-mediated chemotaxis. In contrast,MC148R2 blocked MIP-1α-mediated but not CXCL12α-mediated chemotaxis. Immunoprecipitation by antibodies to MC148R1 or CXCL12α followed by immunoblotting and detection by antibodies to the other protein demonstrated physical interaction of His-tagged CXCL12α and His-tagged MC148R1. Interaction with chemokines might mask the receptor interaction site resulting in decreased binding and impairment of the biological activities. View Publication

Since the discovery of rapamycin,considerable progress has been made in unraveling the details of the mammalian target of rapamycin (mTOR) signaling network,including the upstream mechanisms that modulate mTOR signaling functions,and the roles of mTOR in the regulation of mRNA translation and other cell growth-related responses. mTOR is found in two different complexes within the cell,mTORC1 and mTORC2,but only mTORC1 is sensitive to inhibition by rapamycin. mTORC1 is a master controller of protein synthesis,integrating signals from growth factors within the context of the energy and nutritional conditions of the cell. Activated mTORC1 regulates protein synthesis by directly phosphorylating 4E-binding protein 1 (4E-BP1) and p70S6K (S6K),translation initiation factors that are important to cap-dependent mRNA translation,which increases the level of many proteins that are needed for cell cycle progression,proliferation,angiogenesis,and survival pathways. In normal physiology,the roles of mTOR in both glucose and lipid catabolism underscore the importance of the mTOR pathway in the production of metabolic energy in quantities sufficient to fuel cell growth and mitotic cell division. Several oncogenes and tumor-suppressor genes that activate mTORC1,often through the phosphatidylinositol 3-kinase (PI3K)/AKT pathway,are frequently dysregulated in cancer. Novel analogs of rapamycin (temsirolimus,everolimus,and deforolimus),which have improved pharmaceutical properties,were designed for oncology indications. Clinical trials of these analogs have already validated the importance of mTOR inhibition as a novel treatment strategy for several malignancies. Inhibition of mTOR now represents an attractive anti-tumor target,either alone or in combination with strategies to target other pathways that may overcome resistance. The far-reaching downstream consequences of mTOR inhibition make defining the critical molecular effector mechanisms that mediate the anti-tumor response and associated biomarkers that predict responsiveness to mTOR inhibitors a challenge and priority for the field. View Publication

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disease,characterized by motor neuron (MN) death,for which there are no truly effective treatments. Here,we describe a new small molecule survival screen carried out using MNs from both wild-type and mutant SOD1 mouse embryonic stem cells. Among the hits we found,kenpaullone had a particularly impressive ability to prolong the healthy survival of both types of MNs that can be attributed to its dual inhibition of GSK-3 and HGK kinases. Furthermore,kenpaullone also strongly improved the survival of human MNs derived from ALS-patient-induced pluripotent stem cells and was more active than either of two compounds,olesoxime and dexpramipexole,that recently failed in ALS clinical trials. Our studies demonstrate the value of a stem cell approach to drug discovery and point to a new paradigm for identification and preclinical testing of future ALS therapeutics. View Publication

SummaryThyroid carcinoma represents the first malignancy among the endocrine organs. Investigating the cellular hierarchy and the mechanisms underlying the initiation of thyroid carcinoma is crucial in thyroid cancer research. Here,we present a protocol for deriving thyroid cell lineage from human embryonic stem cells. We also describe steps for engineering thyroid progenitor cells utilizing CRISPR-Cas9 technology,which can be used to perform in vivo studies,thus facilitating the development of representative thyroid tumorigenesis models.For complete details on the use and execution of this protocol,please refer to Veschi et al.1 Graphical abstract Highlights•Differentiation protocol for thyroid cell lineages from human embryonic stem cells•CRISPR-Cas9-mediated cellular engineering for common thyroid cancer genetic alteration•Orthotopic injection of thyroid progenitors to recapitulate thyroid cancer progression Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics. Thyroid carcinoma represents the first malignancy among the endocrine organs. Investigating the cellular hierarchy and the mechanisms underlying the initiation of thyroid carcinoma is crucial in thyroid cancer research. Here,we present a protocol for deriving thyroid cell lineage from human embryonic stem cells. We also describe steps for engineering thyroid progenitor cells utilizing CRISPR-Cas9 technology,which can be used to perform in vivo studies,thus facilitating the development of representative thyroid tumorigenesis models. View Publication

Despite significant advancements in targeted- and immunotherapies,millions of patients with cancer still succumb to the disease each year. In renal cell carcinoma,up to 25% of metastatic patients do not respond to first-line therapies. This reality underscores the urgent need for innovative or repurposed therapies to effectively treat these patients. Patient-derived organoids represent a promising model for evaluating treatment efficacy and toxicity,offering a potential breakthrough in personalized medicine. However,utilizing organoid models for drug screening presents several challenges. Our protocol aims to address these obstacles by outlining a practical approach to successfully isolate and cultivate patient-derived renal cell carcinoma and kidney organoids for treatment screening purposes. Graphical abstract Patient-derived organoids represent a promising model for evaluating treatment efficacy and toxicity,offering a potential breakthrough in personalized medicine. Nowak-Sliwinska and colleagues present a detailed protocol for obtaining kidney and kidney cancer organoids for drug development and precision oncology. View Publication

Current evidence supports a model in which the low-affinity state of the platelet integrin alphaIIbbeta3 results from alphaIIbbeta3 adopting a bent conformation. To assess alphaIIbbeta3 biogenesis and how alphaIIbbeta3 initially adopts the bent conformation,we mapped the conformational states occupied by alphaIIb and beta3 during biogenesis using conformation-specific monoclonal antibodies (mAbs). We found that alphaIIbbeta3 complex formation was not limited by the availability of either free pro-alphaIIb or free beta3,suggesting that other molecules,perhaps chaperones,control complex formation. Five beta3-specific,ligand-induced binding site (LIBS) mAbs reacted with much or all free beta3 but not with beta3 when in complex with mature alphaIIb,suggesting that beta3 adopts its mature conformation only after complex formation. Conversely,2 alphaIIb-specific LIBS mAbs directed against the alphaIIb Calf-2 region adjacent to the membrane reacted with only minor fractions of free pro-alphaIIb,raising the possibility that pro-alphaIIb adopts a bent conformation early in biogenesis. Our data suggest a working model in which pro-alphaIIb adopts a bent conformation soon after synthesis,and then beta3 assumes its bent conformation by virtue of its interaction with the bent pro-alphaIIb. View Publication

Prostaglandin F2alpha inhibits adipose differentiation of primary culture of adipocyte precursors and of the adipogenic cell line 1246 in defined medium. In the present paper,we investigated the effect of FP receptor agonists cloprostenol and fluprostenol on the differentiation of newborn rat adipocyte precursors in primary culture. The results show that cloprostenol and fluprostenol are very potent inhibitors of adipose differentiation. Dose response studies indicate that both agonists are more potent than PGF2alpha in inhibiting adipocyte precursors differentiation. 50% inhibition of adipose differentiation was observed at a concentration of 3 x 10(-12) M for cloprostenol and 3 to 10 x 10(-11) M for fluprostenol respectively whereas the PGF2alpha concentration required to elicit the same effect was 10(-8) M. In contrast compounds structurally related to PGE2 such as 17-phenyl trinor PGE2 had no effect on adipose differentiation except when added at a 10,000-fold higher concentration. View Publication