Remember Me
Or use your Academic/Social account:


Or use your Academic/Social account:


You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.


Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message


Verify Password:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Ferguson, Elaine Lesley
Languages: English
Types: Doctoral thesis
Subjects: RC0254, RM

Classified by OpenAIRE into

mesheuropmc: lipids (amino acids, peptides, and proteins), fungi
Increasingly sophisticated new treatments such as trastuzumab (Herceptin ) and Bevacizumab (Avastin ) have contributed to reduced mortality from breast cancer over recent years, nevertheless 40--60 % of those affected still die from metastatic disease. Thus there remains an urgent need for novel therapies for breast cancer. As PLA2 (crotoxin) has proven anticancer activity but its use is limited by non-specific toxicity, and polymer-drug and polymer-protein conjugates are finding growing use as anticancer agents, the aim of this thesis was to explore the potential of polymer-PLA2 conjugates as a new treatment for breast cancer. Polymer conjugation has previously been shown to reduce systemic toxicity of proteins, prolong their plasma half-life and promote tumour-specific targeting by the enhanced permeability and retention (EPR) effect. First, the synthesis and characterisation methods were optimised using trypsin as a model. After these studies highlighted dextrin as the best polymer for conjugation, dextrin-PLA2 (Apis mellifera venom) conjugates were prepared. Dextrin was chosen for conjugation as it can be used to mask protein activity in the protein masked-unmasked polymer therapy (PUMPT) concept. Such conjugates retained 36 % enzyme activity compared to free PLA2, and moreover, unmasking by a-amylase degradation of dextrin regenerated full enzyme activity. However, while free PLA2 was found to be very haemolytic, dextrin-PLA2 displayed no haemolytic activity, and unmasking by a-amylase degradation of dextrin did not reinstate this activity. The conjugate displayed significant toxicity towards several tumour cell lines, including human breast cancer. Indirect evidence that epidermal growth factor receptor (EGFR) status and tyrosine kinase activity of the receptor influences PLA2-induced anti-proliferative activity were shown. Uptake studies have revealed that conjugation of dextrin to PLA2 reduces non-specific binding to breast cancer cells. In a further study, dextrin-PLA2's ability to burst DaunoXome using the polymer-enzyme liposome therapy (PELT) concept was assessed. Here, it was seen that the conjugate released liposomally encapsulated drug and the combination caused enhanced cytotoxicity in MCF-7 cells. These studies confirm the potential of dextrin-PLA2 as a novel anticancer agent and/or as trigger for liposomal drug release and highlight the feasibility of developing a candidate for further in vivo pharmacokinetic and activity studies.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • Hashizume H, Baluk P, Morikawa S, McLean JW, Thurston G, Roberge S, Jain RK, McDonald DM (2000) Openings between defective endothelial cells explain tumor vessel leakiness. American Journal Pathology 156: 1363-1380
    • Haydon DA, Taylor J (1963) The stability and properties of bimolecular lipid leaflets in aqueous solutions. Journal o f Theoretical Biology 4: 281-296
    • Heimbrook DC, Stirdivant SM, Ahem JD, Balishin NL, Patrick DR, Edwards GM, Defeo-Jones D, FitzGerald DJ, Pastan I, Oliff A (1990) Transforming growth factor alpha-Pseudomonas exotoxin fusion protein prolongs survival of nude mice bearing tumor xenografts. Proceedings o f the National Academy o f Sciences o f the United States o f America 87: 4697-4701
    • Hershfield MS, Buckley RH, Greenberg ML, Melton AL, Schiff R, Hatem C, Kurtzberg J, Markert ML, Kobayashi RH, Kobayashi AL, et al (1987) Treatment of adenosine deaminase deficiency with polyethylene glycol-modified adenosine deaminase. New England Journal o f Medicine 316: 589-596
    • Hewlett LJ, Prescott AR, Watts C (1994) The coated pit and macropinocytic pathways serve distinct endosome populations. Journal o f Cell Biology 124: 689- 703
    • Hortobagyi GN (1997) Anthracyclines in the treatment of cancer. An overview. Drugs 54 Suppl 4: 1-7
    • Hreczuk-Hirst D, Chicco D, German L, Duncan R (2001a) Dextrins as potential carriers for drug targeting: tailored rates of dextrin degradation by introduction of pendant groups. International Journal o f Pharmaceutics 230: 57-66
    • Hreczuk-Hirst D, German L, Duncan R (2001b) Dextrins as Carriers for Drug Targeting: Reproducible Succinoylation as a Means to Introduce Pendant Groups. Journal o f Bioactive and Compatible Polymers 16: 353-365
    • Imai Y, Leung CK, Friesen HG, Shiu RP (1982) Epidermal growth factor receptors and effect of epidermal growth factor on growth of human breast cancer cells in long-term tissue culture. Cancer Research 42: 4394-4398
    • Inaji H, Koyama H, Higashiyama M, Noguchi S, Yamamoto H, Ishikawa O, Omichi K, Iwanaga T, Wada A (1991) Immunohistochemical, ultrastructural and biochemical studies of an amylase-producing breast carcinoma. Virchows Archive A: Pathological Anatomy and Histopathology 419: 29-33
    • Invitrogen Molecular Technologies (2004) Molecular Probes Vol. 2004.
    • Invitrogen Molecular Technologies (2006). A Guide to Fluorescent Probes and Labeling Technologies, http://probes.invitrogen.com/handbook, accessed on Jan 26 2006
    • Jiang J, Neubauer BL, Graff JR, Chedid M, Thomas JE, Roehm NW, Zhang S, Eckert GJ, Koch MO, Eble JN, Cheng L (2002) Expression of group IIA secretory phospholipase A2 is elevated in prostatic intraepithelial neoplasia and adenocarcinoma. American Journal o f Pathology 160: 667-671
    • Johannes L, Lamaze C (2002) Clathrin-dependent or not: is it still the question? Traffic 3: 443-451
    • Johnson KD, Clark A, Marshall S (2002) A functional comparison of ovine and porcine trypsins. Comparative Biochemistry and Physiology Part B 131: 423-431
    • Jones AT (2007) Macropinocytosis: searching for an endocytic identity and role in the uptake of cell penetrating peptides. Journal o f Cell and Molecular Medicine 11: 670-684
    • Jones AT, Gumbleton M, Duncan R (2003) Understanding endocytic pathways and intracellular trafficking: a prerequisite for effective design of advanced drug delivery systems. Advanced Drug Delivery Reviews 55: 1353-1357
    • Jordan VC (2008) Tamoxifen: Catalyst for the change to targeted therapy. European Journal o f Cancer 44: 30-38
    • Jorgensen K, Davidsen J, Mouritsen OG (2002) Biophysical mechanisms of phospholipase A2 activation and their use in liposome-based drug delivery. FEBS Letters 531: 23-27
    • Jorgensen K, Kiebler T, Hylander I, Vermehren C (1999a) Interaction of a lipidmembrane destabilizing enzyme with PEG-liposomes. International Journal o f Pharmaceutics 183: 21-24
    • Jorgensen K, Vermehren C, Mouritsen OG (1999b) Enhancement of phospholipase A2 catalyzed degradation of polymer grafted PEG-liposomes: effects of lipopolymer-concentration and chain-length. Pharmaceutical Research 16: 1491- 1493
    • Journe F, Dumon JC, Kheddoumi N, Fox J, Laios I, Leclercq G, Body JJ (2004) Extracellular calcium downregulates estrogen receptor alpha and increases its transcriptional activity through calcium-sensing receptor in breast cancer cells. Bone 35: 479-488
    • Kano-Sueoka T , King DM, Fisk HA, Klug SJ (1990) Binding of epidermal growth
    • Kato Y , Onishi H, Machida Y (2004) N-succinyl-chitosan as a drug carrier: waterinsoluble and water-soluble conjugates. Biomaterials 25: 907-915
    • Kell B (1971) In The Enzymes, Vol. Ill (3rd edn). Boyer PD (ed), Academic Press (New York, USA), 250-275
    • Kerr DJ, Young AM, Neoptolemos JP, Sherman M, Van-Geene P, Stanley A, Ferry D, Dobbie JW, Vincke B, Gilbert J, el Eini D, Dombros N, Fountzilas G (1996) Prolonged intraperitoneal infusion of 5-fluorouracil using a novel carrier solution. British Journal o f Cancer 74: 2032-2035
    • Khayat Z, Griffiths PC, Grillo I, Heenan RK, King SM, Duncan R (2006) Characterising the size and shape of polyamidoamines in solution as a function of pH using neutron scattering and pulsed-gradient spin-echo NMR. International Journal o f Pharmaceutics 317: 175-186
    • Kingma RL, Snijder HJ, Dijkstra BW, Dekker N, Egmond MR (2002) Functional importance of calcium binding sites in outer membrane phospholipase A. Biochimica et Biophysica Acta 1561: 230-237
    • Kini RM (2003) Excitement ahead: structure, function and mechanism of snake venom phospholipase A2 enzymes. Toxicon 42: 827-840
    • Kirby CJ, Gregoriadis G (1999) Liposomes. In Encyclopedia o f Controlled Drug Delivery, Vol. 1. Mathiowitz E (ed), John Wiley & Sons, Inc. (New York, USA), 461-492
    • Kohn DB, Sadelain M, Glorioso JC (2003) Occurrence of leukaemia following gene therapy of X-linked SCID. Nature Reviews Cancer 3: 477-488
    • Kollmannsberger C, Schittenhelm M, Honecker F, Tillner J, Weber D, Oechsle K, Kanz L, Bokemeyer C (2006) A phase I study of the humanized monoclonal antiepidermal growth factor receptor (EGFR) antibody EMD 72000 (matuzumab) in combination with paclitaxel in patients with EGFR-positive advanced non-smallcell lung cancer (NSCLC). Annals o f Oncology 17: 1007-1013
    • Kopecek J (1984) Controlled biodegradability of polymers- a key to drug delivery systems. Biomaterials 5: 19-25
    • Kopecek J, Rejmanova P, Duncan R, Lloyd JB (1985a) Controlled release of drug model from N-(2-hydroxypropyl)-methacrylamide copolymers. Annals o f the New York Academy o f Sciences 446: 93-104
    • Lehtonen JY, Kinnunen PK (1995) Phospholipase A2 as a mechanosensor. Biophysical Journal 68: 1888-94
    • Moore A (2007) Breast-cancer therapy-looking back to the future. New England Journal o f Medicine 357: 1547-1549
    • Reynolds LJ, Washburn WN, Deems RA, Dennis EA (1991) Assay strategies and methods for phospholipases. Methods in Enzymology 197: 3-23
    • Ringsdorf H (1975) Structure and properties of pharmacologically active polymers. Journal o f Polymer Science- Polymer Symposia 51: 135-153
    • 11. Ferguson, E.L. and Duncan, R. (2008). Investigating a Dextrin-Phospholipase
    • A2 Conjugate as a Trigger for Polymer Enzyme Liposome Therapy (PELT).
    • 13. Hardwicke, J., Ferguson, E.L., Moseley, R., Stephens, P., Thomas, D. and
    • Duncan, R. (2008). Designing Polymer Therapeutics to Promote Tissue Repair.
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article