No abstract

Background:The p28 is a small-sized cell-penetrating peptide derived from bacterial protein azurin and can function as a cancerspecific anti-proliferative agent. It can penetrate cancer tissues easily without involving the immune system, and increase the intracellular concentration of p53. Objectives: In this study, we have expressed and purified recombinant p28, then evaluated its anti-proliferative and pro-apoptotic effects on Raji cancer cell line. Methods: The p28 gene was amplified and cloned into pTZ57R cloning vector and was sequenced subsequently. Afterward, it was transformed into E. coli BL21 bacterial host by using pET-28a expression vector. Peptide purification was carried out using Ni-NTA chromatography system. Bradford, SDS-PAGE, and western blotting assays were applied to assess the concentration and expression level of the recombinant peptide. The proficiency of p28 in inhibition of tumor growth and induction of apoptosis in cancerous cells was investigated by evaluating the Raji and HEK-293 cells treated with different concentrations of p28. Results: The overexpression of the p28 peptide in the bacterial host was confirmed by SDS-PAGE and western blotting. Moreover, Bradford assay revealed desirable concentrations of the recombinant p28 before and after dialysis. The MTT and PE-Annexin V apoptosis assays indicated the specific function of p28 in impeding the proliferation of cancerous cells and triggering the apoptosis. Conclusions: The p28 induces apoptosis in cancerous cells but not in normal control cells. In summary, p28 is a non-immunogenic small peptide that can penetrate cancerous cells preferentially, impede the cell proliferation, and induce the apoptosis. Overall, these findings suggest p28 as a promising anticancer drug.

Background As a novel tumor suppressor mediator, activating transcription factor 3 (ATF3) has recently aroused an interest in its possible therapeutic applications in various cancers. In this study, we evaluated the effect of ATF3 overexpression on the cellular level of nuclear factor kappa B (NF-κB) in human papillomavirus (HPV)-infected Ca Ski cells. Further, we examined whether ATF3 could mediate cell cycle arrest and alter the apoptosis level of Ca Ski cells. Methods The biological behavior of Ca Ski cells was evaluated prior and subsequent to the overexpression of ATF3 by MTT assay, fluorescence microscopy, cell cycle and annexin V/PI flow cytometric analysis. The effect of ectopic ATF3 expression on the cellular level of NF-κB in HPV-positive cells was evaluated by western blotting assay. Results The overexpression of ATF3 in Ca Ski cells led to significant apoptosis and cell cycle arrest in the G1 phase. Western blotting assay revealed a discernible reduction of NF-κB p65 level in cervical cancer cells. Conclusion ATF3 acts as a tumor suppressor factor in HPV16-infected Ca Ski cells and exerts anti-cancer effects on HPV16-related cervical cancer cells potentially by hindering cell growth and inducing cell cycle arrest through the down-regulation of NF-κB. Our results suggest that ATF3 induction or NF-κB suppression may be useful targets for HPV16-related cervical cancer prevention and treatment.

Aim: Human respiratory syncytial virus (HRSV) is a common cause of respiratory infections, particularly in infants and the elderly. Ribavirin is the only US FDA-approved antiviral drug for HRSV infection, but it has unwanted side effects. Methods: We engineered an shRNA targeting the HRSV- M gene to antagonize HRSV replication. Results: The results showed that shRNA had a similarly significant reduction in viral load (99.8%) as ribavirin. In addition, combined treatment with ribavirin and M-shRNA resulted in a significant reduction in viral load compared with ribavirin or M-shRNA alone. Conclusion: These results suggest that M-shRNA could be a potential new inhibitor of HRSV replication and could offer a safer and more effective treatment option for HRSV infection in the future.

Purpose: Despite all the efforts for discovery of efficient anti-cancer therapeutics, cancer is still a major health concern worldwide. p28 is a bacterial small peptide which has been widely investigated due to its preferential cell internalization and anti-cancer activities. Intracellularly, p28 offers its anti-cancer traits by impeding the degradation of tumor-suppressor protein "p53". In this study, we investigated the potency of p28 in inducing apoptosis or decreasing cell viability in p53-null "HeLa" cell line. Methods: The coding sequence for p28 peptide was obtained from Pseudomonas aeruginosa by PCR amplification of the p28 gene. The coding gene was cloned in pET-28a vector and transformed into E. coli bacterial host. Subsequently, the expressed peptide was purified using Ni-NTA chromatography system and introduced into the target cells. The anti-proliferative and apoptotic activity of p28 on HeLa and HEK-293 cells were investigated using MTT and PEAnnexin V Flowcytometry assays. Results: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting confirmed the expression of p28 peptide in the bacterial host. Bradford assay revealed a concentration of 0.05 mg/mL for the purified p28. MTT assay of cells treated with p28 at concentrations of 0, 0.5, 1, 2 and 2.5 µM indicated 24h viability values of 97%, 89%, 88%, 87% and 84% for HeLa cells, respectively. Data obtained from flowcytometry analyses revealed 24h apoptosis rate of 7.17%, 8.05%, 8.63% and 8.84% for HeLa cells treated with 0, 0.5, 1, and 2 µM p28, respectively. Conclusion: MTT and flowcytometry apoptosis assays suggest no statistically significant effect of p28 on the viability and apoptosis status of p53-null HeLa cells when results compared to data obtained from HEK-293 cells (P>0.05). These results imply that anti-cancer efficacy of p28 is directly dependent on the presence of p53, suggesting p28 as an inappropriate therapeutic agent for treatment of cancers with negative p53 status.