Generation of a selectively cytotoxic fusion protein against p53 mutated cancers

Abstract

BackgroundA significant number of cancers are caused by defects in p21 causing functional defects in p21 or p53 tumour-suppressor proteins. This has led to many therapeutic approaches including restoration by gene therapy with wild-type p53 or p21 using viral or liposomal vectors, which have toxicity or side-effect limitations. We set out to develop a safer, novel fusion protein which has the ability to reconstitute cancer cell lines with active p21 by protein transduction.MethodsThe fusion protein was produced from the cell-translocating peptide Antennapedia (Antp) and wild-type, full-length p21 (Antp-p21). This was expressed and refolded from E. coli and tested on a variety of cell lines and tumours (in a BALB/c nude xenograft model) with differing p21 or p53 status.ResultsAntp-p21 penetrated and killed cancer cells that do not express wild type p53 or p21. This included cells that were matched to cogenic parental cell lines. Antp-p21 killed cancer cells selectively that were malignant as a result of mutations or nuclear exclusion of the p53 and p21 genes and over-expression of MDM2. Non-specific toxicity was excluded by showing that Antp-p21 penetrated but did not kill p53- or p21- wild-type cells. Antp-p21 was not immunogenic in normal New Zealand White rabbits. Recombinant Antp peptide alone was not cytotoxic, showing that killing was due to the transduction of the p21 component of Antp-p21. Antp-p21 was shown to penetrate cancer cells engrafted in vivo and resulted in tumour eradication when administered with conventionally-used chemotherapeutic agents, which alone were unable to produce such an effect.ConclusionsAntp-p21 may represent a new and promising targeted therapy for patients with p53-associated cancers supporting the concept that rational design of therapies directed against specific cancer mutations will play a part in the future of medical oncology.

Transduction of Recombinant M3-p53-R12 Protein Enhances Human Leukemia Cell Apoptosis

“…Apart from Adp53-based gene therapy, several reports also tried to use recombinant p53 protein for cancer therapy 42 , 43 . Most of those reports only use cell-penetrating peptides (CPP) to assist protein to entry the cells without enhancing its transactivating activity.…”

Endogenous arginase 2 as a potential biomarker for PEGylated arginase 1 treatment in xenograft models of squamous cell lung carcinoma

“…Phosphate-buffered saline (as control) or BCT-100 (20 or 60 mg/kg, twice a week) was administered intraperitoneally. Tumor dimension (using standard calipers) and body weight of mice were measured twice a week and tumor volume calculated [volume = (length × width × height)/2] 24 . No blinding was done.…”

Growth suppressive effect of pegylated arginase in malignant pleural mesothelioma xenografts

“…PBS (served as control), BCT-100 (20 and 60 mg/kg twice a week), pemetrexed (Eli Lilly, Indianapolis, Indiana, USA) (150 mg/kg twice a week) and/or cisplatin (Cayman, Teaduspargi, Tallinn, Estonia) (2.5 mg/kg once/week) were administered intraperitoneally. Tumor dimension (using standard calipers) and body weight of mice were measured twice a week and tumor volume was calculated [volume = length x width x width)/2] [ 13 ]. For humane reasons, mice were sacrificed when tumor volume reached 600 mm 3 .…”