Human serum albumin (HSA) has been extensively explored as a drug delivery platform in cancer research due to its long half-life, exceptional capacity to carry hydrophobic molecules and ability to accumulate in the tumor microenvironment. The goal of this project is to develop a drug carrier system utilizing HSA to deliver multiple anti-cancer therapeutics simultaneously to cancer cells. For this purpose, an HSA fusion protein technology was utilized where a wild-type p53-derived peptide inhibitor (p53i) was fused to HSA, resulting in a new and active protein, termed rHSA-p53i. This protein has physiological properties that are specific to native albumin. Unlike other fusion proteins, rHSA-p53i can be used to target essential apoptotic intracellular pathways. rHSA-p53i preferentially accumulates in the cancer cells, has a long half-life and can bind long chain fatty acids. In addition to the favorable pharmacokinetic properties, rHSA-p53i can induce apoptosis in cancer cells via transcription-dependent (nuclear) or transcription-independent (cytoplasmic) mechanisms, and irrespectively of p53 status. It binds and neutralizes at least four intercellular proteins, MDM2, MDMX, MCL-1, and BCL-xL, frequently upregulated in cancers. rHSA-p53i binding to MDM2 and MDMX causes wild-type p53 to accumulate inside the cell which is followed by the apoptotic gene transcription and caspase activation. Also, rHSA-p53i can liberate pro-apoptotic regulators BAK from the interaction with anti-apoptotic mitochondrial proteins BCL-xL or MCL-1, initiating a cascade of events followed by cytochrome c release. Activation of both pathways triggers apoptotic cells death. Moreover, rHSA-p53i could sensitize cells to the cytotoxicity induced by some commonly used chemotherapeutics. rHSA-p53i administered in combination with 5-fluorouracil (5FU), methotrexate (MTX), doxorubicin, cisplatin or paclitaxel provoked synergistic cell death, perhaps via overlapping mechanisms involving reactivation of both p53 apoptotic pathway. Furthermore, long chain fatty acid (LCFA) transportation properties of native albumin could allow HSA fusion protein technology to be extended beyond delivery of single peptide to a multiple therapeutics delivery platform containing FA-modified small molecule drugs. rHSA-p53i can be formulated with fatty acid conjugated 5-fluorouracil (FA-5FU) via simple non-covalent interactions. rHSA-p53i preferentially accumulate in tumors and have profound anticancer properties. Great specificity for the tumor cells and high loading ratio of fatty acids modified drugs to albumin allows higher chemo-drug concentrations to be used without inducing significant side effects.
Therefore, this fusion protein technology is a feasible and efficient approach to extend the molecular weight of therapeutic protein and thus prolong the plasma half-life. In addition, the synergistic response between therapeutic peptide and chemotherapy could reduce the effective dose of chemotherapeutic required for cell death limiting the resistance common to the single small molecule drugs. Finally, albumin fusion proteins can bind and carry fatty acid-modified chemotherapeutics and function as multi-purpose drug carriers.
|School:||University of the Sciences in Philadelphia|
|School Location:||United States -- Pennsylvania|
|Source:||DAI-B 79/12(E), Dissertation Abstracts International|
|Subjects:||Pharmacology, Pharmaceutical sciences, Oncology|
|Keywords:||Albumin fusion protein, Fatty acid, Mitochondrial apoptosis, Mutant p53, P53 tumor supressor, Recombinant|
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