Yan-Qing Guan

Cell cycle arrest and apoptosis of OVCAR-3 and MCF-7 cells induced by co-immobilized TNF-α plus IFN-γ on polystyrene and the role of p53 activation.

The aim of this study is to reveal the biological mechanism for high anti-cancer efficiency of co-immobilized TNF-α plus IFN-γ polymeric drug (co-immobilized drug) in mediating two gynecologic cancer cell lines: MCF-7 and OVCAR-3. The co-immobilized drug is prepared by mixing 10 ng/ml TNF-α plus 10 ng/ml IFN-γ which are then photo-immobilized onto cell culture polystyrene plates. The drug compositions and microstructures are characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The MCF-7 and OVCAR-3 cell cycle arrest and programmed cell death are checked by flow cytometry, and the expression of p53 is probed by immunofluorescence staining. The phosphorylation sites of the p53 regulation and the apoptosis key protein expressions of caspase 3, 8 and 9 are detected by western blot assay. Our data show that, in case of short treatment time (48 h) at low cytokine concentrations (20 ng/ml), the co-immobilized drug demonstrates visible effects in comparison with the treatment using TNF-α plus IFN-γ freely attached on the polymeric plate (free drug). It is revealed that the co-immobilized drug leads to significant cell arrest in the S phase or G(1) and G(2) phase and offer high efficiency in mediating a caspase-dependent apoptosis via p53 transcriptional regulation. Moreover, upon the treatment by the co-immobilized drug, the two gynecologic cancer cell lines show different phosphorylation sites of p53 and then different caspase-dependent apoptosis pathways. The present work sheds deep insights into the p53 regulation mechanism responsible for the high anti-cancer efficiency of the co-immobilized TNF-α plus IFN-γ polymeric drug against MCF-7 and OVCAR-3.

Pathway of programmed cell death in HeLa cells induced by polymeric anti-cancer drugs

Synthesis of anticancer polymeric materials plus their biological applications is one of the most charming and active research areas in biological functional materials. However, the predominant mechanisms for controlling cancer cell viability are not yet clear. In this work, cell culture polymeric materials co-immobilized with death signal proteins interferon-γ (IFN-γ)/tumor necrosis factor-α (TNF-α) on the surface were prepared by photochemical method to develop an anticancer polymeric drug model. Various characterizations on the microstructures and compositions, including the Fourier transform infrared spectroscopy, UV absorption spectroscopy, fluorescence measurement, atomic force microscopy, and electron spectroscopy for chemical analysis, were performed. For addressing the biological applications, we investigated systematically the death pathways of HeLa cells attached onto the drug model by means of a series of cell-biology techniques. It was demonstrated that the IFN-γ plus TNF-α co-immobilized on the polymeric material surface exhibited more notable inhibitive effects than the free IFN-γ plus TNF-α, and the induced HeLa cells were mainly along apoptosis-like PCD with the translocation of EndoG from the cytoplasm to the nucleus. These findings indicate that the polymeric drugs with the co-immobilized IFN-γ plus TNF-α may offer significant potentials for therapeutic manipulation of human cervical cancer.

Powerful inner/outer controlled multi-target magnetic nanoparticle drug carrier prepared by liquid photo-immobilization

Nanomagnetic materials offer exciting avenues for advancing cancer therapies. Most researches have focused on efficient delivery of drugs in the body by incorporating various drug molecules onto the surface of nanomagnetic particles. The challenge is how to synthesize low toxic nanocarriers with multi-target drug loading. The cancer cell death mechanisms associated with those nanocarriers remain unclear either. Following the cell biology mechanisms, we develop a liquid photo-immobilization approach to attach doxorubicin, folic acid, tumor necrosis factor-α, and interferon-γ onto the oleic acid molecules coated Fe3O4 magnetic nanoparticles to prepare a kind of novel inner/outer controlled multi-target magnetic nanoparticle drug carrier. In this work, this approach is demonstrated by a variety of structural and biomedical characterizations, addressing the anti-cancer effects in vivo and in vitro on the HeLa, and it is highly efficient and powerful in treating cancer cells in a valuable programmed cell death mechanism for overcoming drug resistance.

The role of STAT-6 as a key transcription regulator in HeLa cell death induced by IFN-γ/TNF-α co-immobilized on nanoparticles.

Based on the fact that the transcription of STAT-1 plus its Serine 727 and Tyrosine 701 phosphorylation is not the pre-requisite for the cell death signal transduction in the IFN-γ signaling pathway induced by co-immobilized IFN-γ/TNF-α, we investigate both in vitro and in vivo the key transcription regulators to promote the signal transduction of HeLa cells. It is found that IFN-γ R2 is the important death signal receptor in the HeLa cell death by RNA interference. Checking the expression of the whole transcription (STAT) protein family reveals that STAT-6 is highly expressed in comparison with the other STAT proteins. The gene silence of IFN-γ R2 leads to the down-regulation of STAT-6 and phosphorylation-STAT-6 (p-STAT-6) expressions. The successful gene silence of STAT-6 results in the reduction of HeLa cell programmed death and the expression of several important key factors related to programmed cell death (p53, Bcl-2, and Bax). More importantly, our in vivo experiments by injecting nanoparticle drug carriers with the co-immobilized IFN-γ/TNF-α into nude mice model confirm the high expression of STAT-6 and p-STAT-6. It is thus concluded that, in response to IFN-γ, the co-immobilized IFN-γ/TNF-α unusually promotes the activation of STAT-6 rather than STAT-1, resulting in the enhanced cell programmed death in HeLa. The present work reveals the gene-level molecular mechanism of IFN-γ/TNF-α co-immobilized on biomaterials as a potentially effective therapy against cancer cells.

Cell death in HeLa mediated by thermoplastic polyurethane with co-immobilized IFN-γ plus TNF-α.

In order to prohibit the toxicity of free IFN-γ plus TNF-α in treating human cervical cancer HeLa cells, two kinds of thermoplastic polyurethane (polyester/polyether) biomaterials with co-immobilized IFN-γ plus TNF-α on the surfaces are prepared. The programmed cell death of HeLa induced by these biomaterials is investigated. The surface modification of these biomaterials with co-immobilized IFN-γ plus TNF-α is performed by the photo-immobilization method, and the surface structures are characterized by various techniques. The cell morphology, cell mortality, cell cycle arrest, and functional status of caspases, upon the treatment by these biomaterials, are characterized. The results show that the as-prepared biomaterials have high inhibition activity against the growth of HeLa cells. The HeLa cells mediated by the two kinds of biomaterials are mainly arrested in the G(1) phase, while those cells mediated directly by free IFN-γ plus TNF-α are mainly arrested in the S phase. It is suggested that the programmed cell death mechanism induced by these two kinds of biomaterials is both caspase-dependent and caspase-independent. Our data provide the knowledge of microscopic surface structures and cell biology basis for synthesizing the thermoplastic polyurethane biomaterials with co-immobilized IFN-γ plus TNF-α, which are promising for novel therapeutics (e.g. drug cup) design for cervical cancer patients.

Immobilisation of bifenthrin for termite control

BACKGROUND Termites are worldwide pests causing considerable damage to agriculture, forestry and buildings. While various approaches have been tried to eliminate termite populations, the relevant toxicants are associated with certain risks to the environment and human health. RESULTS In this study, to combine the merits of effective chemical control by bifenthrin and a drug photoimmobilisation technique, silk fibroin was used as a carrier to embed bifenthrin, which was then photoactively immobilised by ultraviolet treatment on the surface of wood (cellulose). The immobilised bifenthrin embedded in the photoactive silk fibroin was characterised by Fourier transform infrared spectroscopy (FTIR), ultraviolet absorption spectroscopy (UV), fluorescence measurement and CHN analysis. The surface structures and biological activity were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), electron spectroscopy for chemical analysis (ESCA) and bioassays respectively. CONCLUSIONS The results indicate that the embedded and immobilised bifenthrin has been very well protected from free release and has a long-term stability allowing slow release with a high efficiency against termites at a low dose of 1.25 µg cm(-2). This study provides a novel and environmentally benign technique for termite control by photoimmobilising silk-fibroin-embedded bifenthrin on the surface of materials that are otherwise easily attacked by termites.

Long-term G1 cell cycle arrest in cervical cancer cells induced by co-immobilized TNF-α plus IFN-γ polymeric drugs

A realistic control of cell cycle arrest is an attractive goal for the development of new effective anti-cancer drugs. Any clinical application of an effective anti-cancer drug necessarily relies on the understanding of cellular interaction mechanisms. In the present study, we prepared a co-immobilized TNF-α plus IFN-γ biomaterial, which showed a significant inhibition effect on cervical cancer cell growth, as demonstrated by a series of structural and cellular characterizations. We found that co-immobilized TNF-α plus IFN-α induced a long-term G1 phase cell cycle arrest in HeLa, SiHa, and CaSki cells, respectively. More surprisingly, the expression level of the p27 protein decreased, even when p27 mRNA was highly expressed. In addition, gene-chip results and microarray analysis showed that p57 may be downstream from p27, which acts as a direct regulator of the long-term G1 cell cycle arrest in these cells, leaving no escape for cervical cancer cells. Finally, we also investigated the anti-tumor mechanism of co-immobilized TNF-α plus IFN-γin vivo, using a nude mice animal model. To sum up, our findings suggested that the co-immobilized TNF-α plus IFN-γ can induce a long-term cell cycle arrest in cancer, thus serving as a very efficient tool for treating cervical cancer.