Interleukin-24 (IL-24) is known to selectively induce apoptosis in cancer cells through endoplasmic reticulum (ER) stress when it is expressed inside the cells. However, IL-24 alone is unable to enter the cells and consequently unable to inhibit cell proliferation. In the present study, we developed a novel chimeric protein, P28-IL-24, containing IL-24 which is linked to P-28, a defined cancer specific cell penetrating peptide and a P53 stabilizer, to target IL-24 into breast cancer cells. Afterwards, specific and non-specific cytolethal effect of this fusion protein were evaluated in vitro and in vivo.
MTT assay was performed to evaluate cytotoxicity of the fusion protein on MCF-7 and MDA-MB-231 cancer cells. Next, in order to evaluate the mechanism of the induced cell death, Annexin/PI staining of MCF-7 cells treated with the fusion protein was performed and followed by flowcytometry. Finally, in vivo effect of the fusion protein was evaluated on syngenic breast tumors induced in inbred Balb/C mice.
Our findings showed inhibitory effects on proliferation of MCF-7 and MDA-MB-231 cancer cells by the P28-IL-24 protein. In addition, Annexin/PI staining of the treated MCF-7 cells showed that apoptosis induction is the mechanism of cell death induced by the fusion protein. Treatment of inbred Balb/C mice bearing syngenic 4T1 tumor cells with the p28-IL-24 significantly reduced the tumor sizes up to half of the original size within the study period. Furthermore, Hematoxylin and eosin (H&E) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, revealed that this tumor growth suppression was associated with increase in necrotic and apoptotic cells.
Taken together, the findings of the current study suggest that the recombinant chimeric protein p28-IL-24 can serve as a potent candidate for development of a novel cancer therapeutics. Further in vitro and in vivo preclinical evaluations are undergoing.
Isfahan University of Medical Sciences and Health Services.
Isfahan University of Medical Sciences and Health Services.
All authors have declared no conflicts of interest.