Unexpected heat shock element binding ability and tumor-killing activity of the combinatorial function domain of apoptin

Apoptin and apoptotic protease-activating factor 1 plasmid-assisted multi-functional nanoparticles in hepatocellular carcinoma therapy

Cancer drugs usually have side effects in chemotherapy. Apoptin, a protein recognized by its good therapeutical effect on tumors and innocuous to body, is employed to treat hepatocellular carcinoma (HCC). As our previous data shown, the efficiency of apoptin protein might be limited by the protein of apaf-1. Therefore, we designed the multi-functional nanoparticles (MFNPs) encapsulating apoptin and apaf-1 plasmids by layer-by layer assembly. The NPs could release drugs into tumor site specifically and had good compatibility to normal cells and tissues. The groups of biotin, ε-polylysine, and nuclear localization signal in MFNPs conferred NPs the capabilities to enter cancer cells specifically, escape lysosome and enter the nucleus, respectively. In vitro inhibition experiment and in vivo anti-tumor therapy confirmed MFNPs as an excellent carrier to treat HCC. In addition, the dual-drug system was superior to any of the single-drug system. The mechanism analysis proved that supplement of the protein of apaf-1 might enhance apoptosome formation, causing the increase of therapeutical efficacy.

Multifunctional nanoparticles for targeted delivery of apoptin plasmid in cancer treatment

The systemic toxicity and low efficacy of traditional chemotherapy for hepatocellular carcinoma (HCC) result in poor clinical outcomes. This study was designed to achieve targeted delivery of apoptin plasmid (AP) to liver tumors and killing of cancer cells using multifunctional nanoparticles (MFNPs) having sustained-release properties. The MFNPs featuring a distinct core-shell structure were prepared using poly(lactic-glycolic acid)-ε-polylysine copolymer and loaded with AP by adsorption. Specific targeting of liver tumor cells was achieved by biotinylation of the nanoparticles (NPs), while an improvement in lysosomal escape and nuclear localization enhanced the tumor cell killing capability of AP. Blank MFNPs exhibited good biocompatibility while AP-loaded NPs were found to exert strong inhibitory effects on both tumor cells in vitro and solid tumors in vivo. Taken together, these findings demonstrate a promising route for the development of tumor-targeted NPs which may lead to improved therapeutic strategies for treating HCC.

Apoptin as a Tumor-Specific Therapeutic Agent: Current Perspective on Mechanism of Action and Delivery Systems

Cancer remains one of the leading causes of death worldwide in humans and animals. Conventional treatment regimens often fail to produce the desired outcome due to disturbances in cell physiology that arise during the process of transformation. Additionally, development of treatment regimens with no or minimum side-effects is one of the thrust areas of modern cancer research. Oncolytic viral gene therapy employs certain viral genes which on ectopic expression find and selectively destroy malignant cells, thereby achieving tumor cell death without harming the normal cells in the neighborhood. Apoptin, encoded by Chicken Infectious Anemia Virus' VP3 gene, is a proline-rich protein capable of inducing apoptosis in cancer cells in a selective manner. In normal cells, the filamentous Apoptin becomes aggregated toward the cell margins, but is eventually degraded by proteasomes without harming the cells. In malignant cells, after activation by phosphorylation by a cancer cell-specific kinase whose identity is disputed, Apoptin accumulates in the nucleus, undergoes aggregation to form multimers, and prevents the dividing cancer cells from repairing their DNA lesions, thereby forcing them to undergo apoptosis. In this review, we discuss the present knowledge about the structure of Apoptin protein, elaborate on its mechanism of action, and summarize various strategies that have been used to deliver it as an anticancer drug in various cancer models.

Apoptin-derived peptide reverses cisplatin resistance in gastric cancer through the PI3K-AKT signaling pathway

The prognosis of gastric cancer (GC) remains poor due to clinical drug resistance, and novel drugs are urgently needed. Apoptin-derived peptide (AdP) is an antitumor polypeptide constructed in our laboratory that has been used to combat cisplatin (CDDP) resistance in GC cells. MTT and colony-formation assays and Hoechst 33342 staining were used to measure the cytotoxicity of CDDP and AdP in GC cells. Cell apoptosis was measured using an Annexin-V-FITC/PI dual staining assay. Western blot analysis was conducted to detect the expression of proteins in the PI3K/AKT signaling pathway and resistance-related markers. AdP exerted a specific cytotoxic effect on GC cells and CDDP-resistant GC cells in a concentration- and time-dependent manner. AdP also suppressed cell invasion and migration. Additionally, AdP inhibited the expression of p85, AKT, p-p85, p-AKT, multidrug resistance 1 (MDR1), and aryl hydrocarbon nuclear translocator (ARNT) in the PI3K/AKT/ARNT signaling pathway, which promoted apoptosis and necrosis in GC cells. AdP promoted apoptosis in CDDP-resistant GC cells by suppressing the PI3K/AKT/ARNT signaling pathway and might be considered a candidate agent for the clinical treatment of cisplatin-resistant GC.

rApoptin induces apoptosis in human breast cancer cells via phosphorylation of Nur77 and Akt

Breast cancer is the leading cause of cancer incidence and cancer-related mortality among women and is becoming a major public health problem around the world. The current study aims to investigate the possible role and mechanism of recombinant Apoptin (rApoptin), a potential anticancer candidate that minimally impacts normal cells, in the breast cancer cell proliferation and apoptosis in vitro and in vivo. We found that rApoptin could effectively inhibit the proliferation and apoptosis in MCF-7 and MDA-MB-231 cells in vitro, which was further confirmed by flow cytometry analysis. Apoptin partially inhibited MCF-7 cell xenograft tumor development in vivo. Furthermore, we found via western blot that rApoptin-induced apoptosis in MCF-7 and MDA-MB-231 cells was associated with the phosphorylation of Nur77 (p-Nur77) and Akt (p-Akt). In addition, compared with the control groups, rApoptin-treated tissues showed significantly higher expression of Bax and Cyt c while Bcl-2 expression was decreased by rApoptin treatment. Together, our results are the first to demonstrate that rApoptin was able to effectively induce breast cancer cell apoptosis both in vitro and in vivo and that this activity could be regulated by the phosphorylation of Nur77 and Akt and the mitochondrial pathway. Our findings highlight the potential application of rApoptin as a breast cancer treatment.