User:Sarah Weiss/Notebook/W/F Red 2012 20.109 Project

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Project Description

  • Description: from 20.109(S12)
    • Writing a research proposal requires that you identify an interesting topic, spend lots of time learning about it, and then design some clever experiments to advance the field. It also requires that you articulate your ideas so any reader is convinced of your expertise, your creativity, and the significance of your findings, should you have the opportunity to carry out the experiments you’ve proposed. To begin you must identify your research question.
    • A general outline for your research proposal presentation is:
      • a brief project overview (scientific and social context)
      • sufficient background information for everyone to understand your proposal
      • a statement of the research problem and goals (specific research aims)
      • project details and methods
      • predicted outcomes if everything goes according to plan and if nothing does
      • needed resources to complete the work
      • societal impact if all goes well
  • Abstract: Something to do with lipid rafts and cancer

Potential topics

  • Is there a way to improve the apoptotic effect of edelfosine on MM cells? This could be based on increasing cholesterol levels in those cells-- is this possible?
  • How does the clustering of the lipid rafts actually lead to apoptosis? What are the mechanisms of the Fas/CD96 receptors?
  • How does increase of cholesterol levels (without addition of edelfosine) increase the viability of these cells? What sort of cell functions does it effect?
  • How do MM cells differ from non-MM cells? In terms of plasma membrane characteristics? How does the edelfosine select the MM cells?
    • Is there a way to use this targeting as an assay for cancer cells in the blood? Similar to the microfluidics devices earlier discussed?
  • How do cholesterol and ceramide interact differently with the death receptors?
    • In Paper 1, assumed that because ceramide addition (and supposed sterol displacement) decreased sensitivity to edelfosine, ceramide was not involved-- perhaps edelfosine needs to target cholesterol first, "then" ceramide comes in to replace and-- still necessary component.

Research to do

  • Plasma membrane and lipid rafts in general
    • Cholesterol
    • Ceramide
  • Chemicals similar to edelfosine, and their effects
  • Different types of cancer with similar membranes?
    • Distinguishing between MM cells and non-MM cells?


Paper 1: "Lipid raft-targeted therapy in multiple myeloma," Mollinedo et al

  • Phospholipid ether edelfosine selectively accumulates in lipids rafts in the cell membrane of multiple myeloma cells, triggering apoptosis
  • Behavior is a function of cholesterol content of rafts
  • Uptake by cells leads to intracellular activation of Fas/CD95 death receptor by capping mechanism (Gajate and Mollinedo 2001, 2007)
  • Multiple myeloma: second most prevalent blood cancer, deadly B-cell malignancy-- poor apoptotic rate (Dimberg et al 2005), thus transforming event is most likely failure in death regulation
  • MM cells: express Fas/CD95, but are resistant to stimulation with agonistic antibodies (Dimberg et al 2005)-- edelfosine induces aggregation independently of the ligand (Gajate et al 2004)
  • Selective for malignant cells-- not incorporated into normal cells from the same patients
  • With addition of cholesterol depleting agent MCD (Christian et al 1997), rafts were disrupted and clustering/apoptosis did not occur; similar effect with ceramide (displace sterols from rafts-- rafts become ceramide-rich)
  • In vivo study:
    • Severe combined immune deficiency mouse model, inoculated with MM1S cells, tumor developed, edelfosine orally administered-- reduction of 88% in tumor weight and volume, poorly vascularized when compared with control, 4 of 12 mice without tumors, edelfosine more concentrated in tumor than in liver or kidney
    • pravastatin administered (reduce cholesterol levels) -- inhibited antitumor action of edelfosine
  • Possibility: cholesterol rich lipid raft domains must turn into ceramide-rich domains for cell-death signalling (Grassme et al 2003)
  • Explanation:
    • 1) edelfosine recruits downstream signalling molecules
    • 2) edelfosine sensitizes cancer cells to death receptors
  • Own notes:
    • Edelfosine could help recruit the ceramide-- turn the cholesterol rich domain into ceramide-rich domain, allowing cell-death signalling
    • What differentiates MM lipid rafts from those of normal cells?

Paper 2: "Low-density lipoprotein cholesterol suppresses apoptosis in human multiple myeloma cells," Tirado-Velez et al

  • LDL transports cholesterol to peripheral tissues from liver
  • Patients with MM have lower plasma levels of LDL cholesterol
  • Exogenous LDL cholesterol improves MM cell viability, blocks the apoptotic effect of lipoprotein depletion
  • Inhibition of endogenous cholesterol production by statins induces myeloma cell death (Janosi et al 2004), however works much better in vitro than in vivo
  • It has been proposed that changes in cholesterol content of lipid rafts, due to aberrant cholesterol metabolism, alter signal transduction events that promote tumor growth and reduce apoptosis
  • Human prostate cancer cells containing cholesterol-rich lipid rafts mediate the pro-survival effect of epidermal growth factor (Zhuang et al 2002)
    • Depletion of cholesterol from lipid rafts disrupt rafts and reduce cell survival
    • Reconstitution of rafts with cholesterol restores EGF effect
  • LDL receptor may be therapeutic target for MM

Paper 3: "Lipid Rafts and Keratinocyte Apoptosis: Regulation via Death REeceptors and Akt" Gniadecki and Poumay

  • Rafts generally as regulators of signal transduction; only form spontaneously in a narrow range of cholesterol concentration
  • Cancer tissues contain more cholesterol than healthy tissue-- may have significance for tumor growth (Chen et al 1978)
  • Cholesterol depletion from membranes of leukemic cells-- apoptosis and increased sensitivity to chemotherapeutic drugs (Kornblau et al 2007) !! OPPOSITE OF FIRST PAPER
    • Elevated initial levels correlated with sensitivity to depletion (Li "Elevated levels..." 2006)
  • Depletion of cholesterol related apoptosis seen in keratinocytes (sin cells) here-- swelling of mitochondria, loss of mitochondrial potential associated
  • Membrane death receptor Fas: binding of ligand FasL
    • hypothesis: Fas is recruited to rafts, forms complexes, colocalizes with capsae 8 (Bionda 2008)
    • in keratinocytes, squamous cell carcinoma: Fas collects with caspase and FADD upon cholesterol depletion
    • Cholesterol-depletion apoptosis even when Fas is blocked (caspase-8 inhibitors)

Paper 4: "Cytoskeleton-mediated Death Receptor and Ligand Concentration in Lipid Rafts forms Apoptosis-promoting Clusters in Cancer Chemotherapy" Gajate and Mollinedo

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