Bio-mimetic nanostructure self-assembled from Au@Ag heterogeneous nanorods and phage fusion proteins for targeted tumor optical detection and photothermal therapy.

Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm(2). The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor.

Anti-cancer effect and the underlying mechanisms of gypenosides on human colorectal cancer SW-480 cells.

BACKGROUND: Gypenosides (Gyp), the main components from Gynostemma pentaphyllum Makino, are widely used in traditional Chinese medicine. The present study aimed to investigate the anti-cancer effect and the underlying mechanisms of Gyp on human colorectal cancer cells SW-480. MATERIALS AND METHODS: The inhibitory effect of Gyp on SW-480 cells was evaluated by MTT assay. Apoptotic cell death was detected by nuclear Hoechst 33342 staining and DNA fragmentation analysis. Apoptosis was analyzed using Annexin V-PE/7-amino-actinomycin D staining. Cell membrane integrity was evaluated with flow cytometry following PI staining. Changes of mitochondrial membrane potential (Δψm) were detected through flow cytometry analysis of rhodamine 123 (Rh123). The role of reactive oxygen species (ROS) in Gyp induced cell death was investigated by intracellular ROS generation and general ROS scavenger. Wound-healing assay was carried out to investigate Gyp-inhibited migration of SW-480 cells in vitro. Additionally, the alterations in F-actin microfilaments were analyzed by FITC-labeled phalloidin toxin staining and the morphological changes were evaluated under scanning electron microscope (SEM). RESULTS: After the Gyp treatment, the plasma membrane permeability of SW-480 cell was increased, Δψm was decreased significantly, the level of intracellular ROS level was increased, DNA fragmentation and apoptotic morphology were observed. Cells treated with Gyp exert serious microfilament network collapse as well as the significant decrease in the number of microvilli. Gyp induced the changes of cell viability, cell migration, intracellular ROS generation and nuclear morphology were alleviated obviously by NAC. CONCLUSION: The results in this study implied that ROS play an important role in Gyp induced cell toxicity and apoptosis, and the mitochondria damage may be upstream of ROS generation post Gyp treatment. The findings of the present study provide new evidences for anti-tumor mechanisms by which Gyp induces apoptosis in vitro.

Apoptosis in a tissue-like culture model of human colorectal adenoma cells.

Tissue-like cultures of LT97 human colonic adenoma cells were produced by plating on reconstructed connective tissue supports (CTR) containing colon-associated fibroblasts to form mucosal monolayers and polyp-like structures closely resembling the in vivo situation. Tight cell-cell contacts and a high density of desmosomes were observed in 93.8+/-3.5% of the section area for CTR cultures, but only in 17.8+/-10.0% of the area for cultures on collagen gels (CG) without fibroblasts. While LT97 cultures on plastic shed apoptotic bodies into the medium, they collected at the basal pole of the cell layer in the CTR cultures as is also observed in adenoma tissue. Only a small proportion was released into the medium as shown by the detection of apoptosis specific keratin fragments, which could be increased by 100microM of quercetin and resveratrol. In addition, tissue-like structures altered the relative effectivity of test compounds. As the tissue-like conditions closely resemble the situation in vivo tissue-like cultures are an important step towards the establishment of tissue reconstructs that can replace animal models in the analysis of basic mechanisms of growth control and the testing of tumor promoting and chemopreventive compounds and may even be superior in terms of predictivity as they use human cells.

Effect of interstitial laser hyperthermia in a murine model of colorectal liver metastases: scanning electron microscopic study.

Interstitial laser hyperthermia (ILH) is an in situ ablative technique used to treat colorectal liver metastases. The relatively high recurrence of tumor after treatment by ILH may be related to incomplete destruction. Little is known about the effectiveness of ILH for destroying tumor microvasculature. The aim of this study was to define the changes to the microvascular architecture of tumors after treatment with ILH, specifically focusing on the completeness of tumor vasculature destruction. An intrasplenic induction model of liver metastases in 4- to 6-week-old male inbred CBA mice was used. Laser hyperthermia was applied to liver and tumor tissue using a bare optical quartz fiber from a Medilas Fibertom 4100 Nd:YAG surgical laser generator. The animals underwent microvascular corrosion casting of the livers immediately after application of ILH. Microvascular casts were then prepared and studied by scanning electron microscopy. ILH produced complete, uniform destruction of the tumor microvasculature with compete hemostasis. Blood flow in vessels larger than 100 microm diameter had a relatively protective effect, although ILH was able to overcome this barrier effectively by increasing the energy applied. ILH produces complete destruction of tumor microvasculature with hemostasis. The protective effect of blood flow in larger vessels can be overcome by the appropriate use of higher energy levels.