A dual-targeting drug delivery and pH-sensitive controlled release system based on multifunctionalized graphene oxide (GO) was established in order to enhance the effect of targeted drug delivery and realize intelligently controlled release. A superparamagnetic GO-Fe 3 O 4 nanohybrid was firstly prepared via a simple and effective chemical precipitation method. Then folic acid, a targeting agent toward some tumor cells, was conjugated onto Fe 3 O 4 nanoparticles via the chemical linkage with amino groups of the 3-aminopropyl triethoxysilane (APS) modified superparamagnetic GO-Fe 3 O 4 nanohybrid, to give the multi-functionalized GO. Doxorubicin hydrochloride (Dox) as an anti-tumor drug model was loaded onto the surface of this multi-functionalized GO via p-p stacking. The drug loading capacity of this multi-functionalized GO is as high as 0.387 mg mg À1 and the drug release depends strongly on pH values. Cell uptake studies were carried out using fluorescein isothiocyanate labeled or Dox loaded multi-functionalized GO to evaluate their targeted delivery property and toxicity to tumor cells. The results show that this multi-functionalized GO has potential applications for targeted delivery and the controlled release of anticancer drugs.

An elevated number of Gr-1 + CD11b + myeloid cells has been described in mice bearing transplantable tumors, and has been associated with immune suppression. We examined the role of such myeloid suppressor cells in mice bearing the spontaneously transformed syngeneic mouse ovarian surface epithelial cell line, 1D8. We observed high levels of CD80 expression by Gr-1 + CD11b + cells from spleen, ascites, and tumor tissue of mice bearing 1D8 ovarian carcinoma, whereas CD40 and CD86 were absent. CD80 expression was not detected on Gr-

Purpose: To determine whether -CONH-(CH 2 ) 6 -NH 3 + Cl À functionalized single-walled carbon nanotubes (SWNT) carrying complexed small interfering RNA (siRNA) can enter into tumor cells, wherein they release the siRNA to silence the targeted gene. Experimental Design: -CONH-(CH 2 ) 6 -NH 3 + Cl À was used to mediate the conjugation of telomerase reverse transcriptase (TERT) siRNA to SWNTs. The ability of TERT siRNA delivered via SWNTcomplexes to silence the expression of TERT was assessed by their effects on the proliferation and growth of tumor cells both in vitro and in mouse models. Results: The functionalized SWNTs -CONH-(CH 2 ) 6 -NH 3 + Cl À could facilitate the coupling of siRNAs that specifically target murine TERT expression to form the mTERT siRNA:SWNT+ complex. These functionalized SWNTs rapidly entered three cultured murine tumor cell lines, suppressed mTERT expression, and produced growth arrest. Injection of mTERT siRNA:SWNT+ complexes into s.c. Lewis lung tumors reduced tumor growth. Furthermore, human TERT siRNA:SWNT+ complexes also suppressed the growth of human HeLa cells both in vitro and when injected into tumors in nude mice. Conclusions: -CONH-(CH 2 ) 6 -NH 3 + Cl À functionalized SWNTs carry complexed siRNA into tumor cells, wherein they release the siRNA from the nanotube sidewalls to silence the targeted gene.The -CONH-(CH 2 ) 6 -NH 3 + Cl À functionalized SWNTs may represent a new class of molecular transporters applicable for siRNA therapeutics.

Myeloid-derived suppressor cells (MDSCs) were one of the major components of the immune suppressive network. STAT3 has an important role in regulating the suppressive potential of MDSCs. In this study, we found that the expression of STAT3 could be modulated by both miR-17-5p and miR-20a. The transfection of miR-17-5p or miR-20a remarkably reduces the expression of reactive oxygen species and the production of H2O2, which are regulated by STAT3. MDSCs transfected with miR-17-5p or miR-20a are less able to suppress Ag-specific CD4 and CD8 T cells. Importantly, both miR-17-5p and miR-20a alleviate the suppressive function of MDSCs in vivo. The expression of miR-17-5p and miR-20a in tumor-associated MDSCs was found to be lower than in Gr1+CD11b+ cells isolated from the spleens of disease-free mice. Tumor-associated factor downregulates the expression of both miR-17-5p and miR-20a. The modulation of miR-17-5p and miR-20a expression may be important for the process by which patients with a tumor can overcome the immune tolerance mediated by MDSCs. Our results suggest that miR-17-5p and miR-20a could potentially be used for immunotherapy against diseases, especially cancer, by blocking STAT3 expression.

Human papillomavirus type 16 (HPV16) is the primary etiologic agent of cervical carcinoma, whereas bovine papillomavirus type 1 (BPV1) causes benign fibropapillomas. However, the capsid proteins, L1 and L2, of these divergent papillomaviruses exhibit functional conservation. A peptide comprising residues 1 to 88 of BPV1 L2 binds to a variety of cell lines, but not to the monocyte-derived cell line D32, and blocks BPV1 infection of mouse C127 cells. Residues 13 to 31 of HPV16 L2 and BPV1 L2 residues 1 to 88 compete for binding to the cell surface, and their binding, unlike that of HPV16 L1/L2 virus-like particles, is unaffected by heparinase or trypsin pretreatment of HeLa cells. A fusion of HPV16 L2 peptide 13-31 and GFP binds (K d , ϳ1 nM) to ϳ45,000 receptors per HeLa cell. Furthermore, mutation of L2 residues 18 and 19 or 21 and 22 significantly reduces both the ability of the HPV16 L2 13-31-GFP fusion protein to bind to SiHa cells and the infectivity of HPV16 pseudovirions. Antibody to BPV1 L2 peptides comprising residues 115 to 135 binds to intact BPV1 virions, but fails to neutralize at a 1:10 dilution. However, deletion of residues 91 to 129 from L2 abolishes the infectivity of BPV1, but not their binding to the cell surface. In summary, L2 residues 91 to 129 contain epitopes displayed on the virion surface and are required for infection, but not virion binding to the cell surface. Upon the binding of papillomavirus to the cell surface, residues 13 to 31 of L2 interact with a widely expressed, trypsin-and heparinase-resistant cell surface molecule and facilitate infection.The infectious process for most viruses, including papillomavirus, is poorly understood. However, in the last decade, a plethora of primary viral receptors have been identified (reviewed in reference 1). Viruses adhere to the target cells via these primary receptors, but their uptake and transport to the site of viral replication often require interaction with other secondary viral receptors (1).The papillomavirus capsid comprises two genetically unrelated viral proteins called L1 and L2 that surround the ϳ8-kb histone-bound, closed circular viral genomic DNA (14). Expression of the major capsid protein L1 results in Tϭ7 viruslike particles (VLPs) formed from 72 petameric L1 capsomers (21, 29). Three-dimensional image reconstructions and the ϳ30:1 ratio of L1 and L2 in native bovine papillomavirus type 1 (BPV1) suggest that the L2 minor capsid protein is located in the center of the pentavalent capsomers at the virion vertices (46). Both L1 and L2 are necessary for efficient production of infectious viruses in vivo, with L2 functioning in both encapsidation and the infectious process (36, 37, 52).Papillomaviruses bind via L1 to cells derived from a wide variety of tissues and species (34, 40). While papillomavirus pseudovirions lacking L2 are infectious (45), recent reports suggest that L2 also can bind to the cell surface, resulting in its internalization (28), and that L2 is critical to the infectious process (36, 47). Furthermore, ant...

Dendritic cells (DCs) link innate and adaptive immunity by sensing pathogens or vaccinogens and signaling a variety of defense responses. Since human papillomavirus type 16 L1 virus-like particles (HPV16 VLPs) induce a potent, protective immune response after vaccination, we examined their recognition by DCs. HPV16 VLPs cause phenotypic maturation of murine bone marrow-derived DCs (BMDCs), and immunization of mice with HPV16 VLP-loaded BMDCs or HPV16 VLPs alone induced T helper 1 (Th1)-biased immune responses. Analysis of transcriptional responses of murine BMDCs by microarray suggested that alpha/beta interferon (IFN-α/β) transcripts and numerous proinflammatory cytokines and chemokines are up regulated in response to HPV16 VLPs. Indeed, the induction of IFN-α, IFN-γ, and interleukin-12 (IL-12) production by BMDCs after stimulation with HPV16 VLPs was demonstrated by quantitative enzyme-linked immunosorbent assay. Many microbial products that induce proinflammatory responses are recognized via Toll-like receptor (TLR) signaling through the key adaptor protein MyD88 and activation of NF-κB, nuclear factor of activated T cells (NF-AT), and activating protein 1 (AP-1). Reporter assays indicated that HPV16 VLPs activated NF-κB-, NF-AT-, and AP-1-dependent transcription in the RAW264.7 macrophage cell line. Knockdown of MyD88 transcripts by small interfering RNA in the RAW264.7 macrophage cell line inhibited the activation of NF-κB-, NF-AT- and AP-1-dependent transcription by HPV16 VLP. Furthermore, MyD88−/− BMDCs failed to up regulate IL-12 and IFN-α and -γ in response to HPV16 VLPs. Finally, Th1-biased immune responses to HPV16 VLPs are dramatically impaired in MyD88 and IFN-α/β receptor-deficient mice. This implicates TLR recognition as central to immune recognition of HPV16 L1 VLPs

The papillomavirus capsid mediates binding to the cell surface and passage of the virion to the perinuclear region during infection. To better understand how the virus traffics across the cell, we sought to identify cellular proteins that bind to the minor capsid protein L2. We have identified syntaxin 18 as a protein that interacts with bovine papillomavirus type 1 (BPV1) L2. Syntaxin 18 is a target membrane-associated soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (tSNARE) that resides in the endoplasmic reticulum (ER). The ectopic expression of FLAG-tagged syntaxin 18, which disrupts ER trafficking, blocked BPV1 pseudovirion infection. Furthermore, the expression of FLAG-syntaxin 18 prevented the passage of BPV1 pseudovirions to the perinuclear region that is consistent with the ER. Genetic studies identified a highly conserved L2 domain, DKILK, comprising residues 40 to 44 that mediated BPV1 trafficking through the ER during infection via an interaction with the tSNARE syntaxin 18. Mutations within the DKILK motif of L2 that did not significantly impact virion morphogenesis or binding at the cell surface prevented the L2 interaction with syntaxin 18 and disrupted BPV1 infection.Papillomaviruses (PVs) have been identified as the causative agents of lesions in squamous epithelial cells of many organisms, primarily higher vertebrates (4). These species-specific viruses infect cutaneous and mucosal surface squamous epithelial cells. Bovine papillomavirus type 1 (BPV1) has been studied extensively since the early 1980s and has served as the prototype for many virus-host cell interaction studies involving the papillomaviruses (5,12,14,39,41,51). Infection begins with binding of the virus to the surface of the cell, and the ␣ 2 ␤4 integrin complex has been suggested as a potential receptor for the virus (27). A recent study demonstrated the colocalization of papillomavirus virus-like particles with the clathrin adaptor molecule AP-2 and with the transferrin receptor, a marker of late endosomes and lysosomes, indicating that papillomaviruses internalize via clathrin-coated vesicles (8). The events that are necessary for uncoating of the virus and for viral DNA entry into the nucleus have not been well defined. The kinetics of infection are such that internalization occurs with a half-life of 4 h, and the transcription of viral packaged DNA occurs after 12 h (8).Two structural viral proteins form the nonenveloped icosahedral capsid at a ratio of approximately 30:1 L1 to L2, and they mediate the delivery of the histone-bound ϳ8-kb doublestranded circular papillomavirus genome to the nucleus during infection (11, 45). The L1/L2 ratio suggests that there is one L2 at each of 12 vertices of the 55-nm-diameter particles (45). The major capsid protein L1 is sufficient to form virus-like particles that morphologically and immunologically resemble the native virion (10,23,24,40). The coassembly of L2 into virus-like particles enhances both the ability to package DNA and the ability to mediate infection...

An elevated number of Gr-1(+)CD11b(+) myeloid-derived suppression cells (MDSCs) has been described in mice and human bearing tumor and associated with immune suppression. Arginase I production by MDSCs in the tumor environment may be a central mechanism for immunosuppression and tumor evasion. In this study and before, we found that Gr-1(+)CD11b(+) MDSCs from ascites and spleen of mice bearing ovarian 18D carcinoma express a high level of PD-1, CTLA-4, B7-H1 and CD80 while other co-stimulatory molecules, namely CD40, B7-DC and CD86 are not detected. Further studies showed that PD-1 and CTLA-4 on the Gr-1(+)CD11b(+) MDSCs regulated the activity and expression of arginase I. The blockage and silencing of PD-1, CTLA-4 or both PD-1 and CTLA4 molecules could significantly reduce arginase I activity and expression induced with tumor-associated factor. Similar results were also observed while their ligands B7-H1 and/or CD80 were blocked or silenced. Furthermore, CD80 deficiency also decreased the arginase I expression and activity. Antibody blockade or silencing of PD-1, CTLA-4 or both reduced the suppressive potential of PD-1+CTLA-4+MDSCs. Blockade of PD-1, CTLA-4 or both also slowed tumor growth and improved the survival rate of tumor-bearing mice. Thus, there may exist a coinhibitory and costimulatory molecules-based immuno-regulating net among MDSCs.