Background: Ionizing radiation plays a significant role in cancer treatment. Despite recent advances in radiotherapy approaches, the existence of irradiation-resistant cancer cells is still a noteworthy challenge. Therefore, developing novel therapeutic approaches are still warranted in order to increase the sensitivity of tumor cells to radiation. Many types of research rely on the role of mitochondria in radiation protection.Objective: Here, we aimed to target the mitochondria of monocyticleukemia (THP-1) radio-resistant cell line cells by a mitochondrial disrupting peptide, D (KLAKLAK)2, and investigate the synergistic effect of Gamma-irradiation and KLA for tumor cells inhibition in vitro.Material and Methods: KLA was delivered into THP-1 cells using a Cell-Penetrating Peptide (CPP).The cells were then exposed to gamma-ray radiation both in the presence and absence of KLA conjugated with CPP. The impacts of KLA, ionizing radiation or combination of both were then evaluated on the cell proliferation and apoptosis of THP-1 cells using MTT assay and flow cytometry, respectively.Results: The MTT assay indicated the anti-proliferative effects of combined D (KLAKLAK)2 peptide with ionizing radiation on THP-1cells. Moreover, synergetic effects of KLA and ionizing radiation reduced cell viability and consequently enhanced cell apoptosis.Conclusion: Using KLA peptide in combination with ionizing irradiation increases the anticancer effects of radio-resistant THP-1 cells. Therefore, the combinational therapy of (KLAKLAK)2 and radiation is a promising strategy for cancer treatment the in future.

Background: Granzyme B can induce apoptosis in target cells by direct and indirect activation of caspases and cleavage of central caspase substrates. Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein and its expression increases following prostate cancer progression. Objective: In this study, we designed a fusion protein including mutant granzyme B, the influenza virus hemagglutinin HA-2 N-terminal, and PSMA ligand to construct GrB-HA-PSMA ligand fusion protein as a molecular agent for selective targeting of PSMA-positive (LNCaP) cells. Methods: The DNA sequence of our designed structure was synthesized and cloned into a pET28a expression vector. The recombinant protein was expressed in E. coli origami bacteria and then purified. The expression of the recombinant protein was verified by SDS PAGE and ELISA method. Furthermore, ELISA and flow cytometry assays were utilized to investigate the efficiency of binding and permeability of the recombinant protein into the LNCaP cells. Finally, cell proliferation and apoptosis rate were evaluated by MTT assay and flow cytometry assay, respectively. HeLa and PC3 cell lines were used as controls. Results: The results showed that GrB-HA-PSMA ligand fusion protein could specifically bind and internalize into the PSMA-positive cells. Furthermore, treatment of the cells with GrB-HA-PSMA ligand fusion protein resulted in increased apoptotic cell death and decreased proliferation of LNCaP cells. Conclusion: Our findings indicate the specificity of GrB-HA-PSMA ligand fusion protein for PSMA-positive cells and suggest that this fusion protein is a potential candidate for prostate cancer targeted therapy.