Human serum albumin and p53-activating peptide fusion protein is able to promote apoptosis and deliver fatty acid-modified molecules

• Published in: PloS one 2013-11, Vol.8 (11), p.e80926
• Main Authors: Joshi, Michelle R, Yao, Nianhuan, Myers, Kenneth A, Li, Zhiyu
• Format: Article
• Language: English
• Subjects: Albumin; Apoptosis; Apoptosis - drug effects; Binding; Biological Transport - drug effects; Breast cancer; Cancer; Cancer therapies; Cancer treatment; Caspase; Caspases - metabolism; Cell cycle; Cell Line, Tumor; Cytotoxicity; Deoxyribonucleic acid; DNA; Drugs; Endocytosis - drug effects; Enzyme Activation - drug effects; Fatty acids; Fatty Acids - metabolism; Feasibility studies; Fluorescein-5-isothiocyanate - metabolism; Fusion protein; Health aspects; Human serum albumin; Humans; Intracellular; MDM2 protein; Models, Biological; Nuclear Proteins - metabolism; p53 Protein; Peptides; Peptides - pharmacology; Pharmaceutical sciences; Pharmacy; Proteins; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-mdm2 - metabolism; Receptors; Recombinant Fusion Proteins - isolation & purification; Recombinant Fusion Proteins - pharmacology; Serum albumin; Serum Albumin - metabolism; Stability; Toxicity; Tumor proteins; Tumor Suppressor Protein p53 - metabolism; Tumors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0080926

Therapeutic peptides offer a high degree of specificity, potency, and low toxicity; making them promising candidates for cancer therapy. Despite these advantages, a number of hurdles, such as poor serum stability and inefficient cellular penetration, must be overcome. Fusing a therapeutic peptide to human serum albumin (HSA) is a common approach to extend the serum stability of a peptide that binds to extracellular receptors. However, no study has shown that this approach can be applied to target intracellular proteins. Here we demonstrate the feasibility of using a recombinant human serum albumin (rHSA) fusion protein to simultaneously deliver two types of molecules: a peptide capable of binding an intracellular target, as well as fatty acid (FA)-modified FITC (FA-FITC). Two peptides reported to disrupt the intracellular p53 and MDM2/MDMX interaction were fused to the C-terminal of HSA. Cellular and biochemical studies indicate that rHSA fusion proteins were efficiently taken up by SJSA-1 cells and retained MDM2- and MDMX-binding activity. By inducing the accumulation of p53, both fusion proteins promoted efficient cytotoxicity in SJSA-1 cells via caspase activation. Long chain fatty acid (LCFA) transportation is an essential endogenous function of HSA. This study also demonstrates that rHSA fusion proteins formed highly stable complexes with FA-FITC via non-covalent interactions. FA-FITC complexed with HSA could be internalized efficiently and rHSA-P53i and rHSA-PMI retained apoptotic activity as complex components. It is expected that such an approach can ultimately be used to facilitate intracellular delivery of two anticancer therapeutics, each with distinct but complimentary mechanisms, to achieve synergistic efficacy.