Tumor endothelial marker 8 expression levels in dendritic cell-based cancer vaccines are related to clinical outcome.

Previous studies have shown that tumor endothelial markers (TEMs 1-9) are up modulated in immunosuppressive, pro-angiogenic dendritic cells (DCs) found in tumor microenvironments. We recently reported that monocyte-derived DCs used for vaccination trials may accumulate high levels of TEM8 gene transcripts. Here, we investigate whether TEM8 expression in DC preparations represents a specific tumor-associated change of potential clinical relevance. TEM8 expression at the mRNA and protein level was evaluated by quantitative real-time RT-PCR and cytofluorimetric analysis in human clinical grade DCs utilized for the therapeutic vaccination of 17 advanced cancer patients (13 melanoma and 4 renal cell carcinoma). The analyses revealed that DCs from patients markedly differ in their ability to up-modulate TEM8. Indeed, mDCs from eight non-progressing patients [median overall survival (OS) = 32 months, all positive to the delayed-type hypersensitivity test (DTH)], had similar TEM8 mRNA expression levels [mDCs vs. immature iDCs; mean fold increase (mfi) = 1.97] to those found in healthy donors (mfi = 2.7). Conversely, mDCs from nine progressing patients (OS < 5 months, all but one with negative DTH) showed an increase in TEM8 mRNA levels (mfi = 12.88, p = 0.0018). The present observations suggest that TEM8 expression levels in DC-based therapeutic vaccines would allow the selection of a subgroup of patients who are most likely to benefit from therapeutic vaccination.

Antibody and CD8+ T cell responses against HER2/neu required for tumor eradication after DNA immunization with a Flt-3 ligand fusion vaccine.

PURPOSE: HER2/neu is frequently overexpressed in breast cancer. In a mouse model, vaccination with HER2/neu DNA elicits antibodies that confer partial protection against tumor challenge. EXPERIMENTAL DESIGN: To enhance antitumor immunity, we fused cDNA encoding Flt-3 ligand (FL) to the rat HER2/neu extracellular domain (neu), generating a chimeric FLneu molecule. FLneu and neu DNA vaccines were compared for immunogenicity and their ability to protect mice from tumor challenge. RESULTS: The neu vaccine generated a HER2/neu-specific antibody response. In contrast, vaccination with FLneu induced CD8+ T cells specific for HER2/neu but a negligible anti-HER2/neu antibody response. The switch from an antibody-mediated to T cell-mediated response was due to different intracellular localization of neu and FLneu. Although the neu protein was secreted, the FLneu protein was retained inside the cell, co-localizing with the endoplasmic reticulum, facilitating processing and presentation to T cells. The neu and FLneu vaccines individually conferred only weak tumor immunity. However, efficient tumor rejection was seen when neu and FLneu were combined, inducing both strong anti-HER2/neu-specific antibody and T cell responses. Adoptive transfer of both immune CD8+ T cells and immune sera from immunized mice was required to confer tumor immunity in naïve hosts. CONCLUSIONS: These results show that active induction of both humoral and cellular immunity to HER2/neu is required for efficient tumor protection, and that neither response alone is sufficient.

INF-γ encoding plasmid administration triggers bone loss and disrupts bone marrow microenvironment.

IFN-γ is a pleotropic cytokine produced in the bone microenvironment. Although IFN-γ is known to play a critical role on bone remodeling, its function is not fully elucidated. Consistently, outcomes on the effects of IFN-γ recombinant protein on bone loss are contradictory among reports. In our work we explored, for the first time, the role of IFN-γ encoding plasmid (pIFN-γ) in a mouse model of osteopenia induced by ovariectomy and in the sham-operated counterpart to estimate its effects in skeletal homeostasis. Ovariectomy produced a dramatic decrease of bone mineral density (BMD). pINF-γ injected mice showed a pathologic bone and bone marrow phenotype; the disrupted cortical and trabecular bone microarchitecture was accompanied by an increased release of pro-inflammatory cytokine by bone marrow cells. Moreover, mesenchymal stem cells' (MSCs) commitment to osteoblast was found impaired, as evidenced by the decline of osterix-positive (Osx+) cells within the mid-diaphyseal area of femurs. For instance, a reduction and redistribution of CXCL12 cells have been found, in accordance with bone marrow morphological alterations. As similar effects were observed both in sham-operated and in ovariectomized mice, our studies proved that an increased IFN-γ synthesis in bone marrow might be sufficient to induce inflammatory and catabolic responses even in the absence of pathologic predisposing substrates. In addition, the obtained data might raise questions about pIFN-γ's safety when it is used as vaccine adjuvant.

Administration of DNA Plasmid Coding Protein Aggregating Domain Induces Inflammatory Bone Loss.

BACKGROUND: Plasmids coding protein aggregation polypeptides from different sources have been proposed as genetic adjuvants for DNA vaccines. We reported that a plasmid (pATRex), encompassing the DNA sequence for the von Willebrand A (vWA/A) domain of the Anthrax Toxin Receptor-1 (ANTXR-1, alias TEM8, Tumor Endothelial Marker 8), acts as strong immune adjuvant by inducing formation of insoluble intracellular aggregates and subsequent cell death. OBJECTIVE: In the present study we addressed the question of whether there is any substantial immunotoxicity associated with the use of self-aggregating proteins as genetic adjuvants. METHODS & RESULTS: Here we report, by mean of histology, X-ray and molecular examinations of bone specimens, the unexpected finding that intramuscular injection of pATRex in mice triggers, per se, severe bone loss (osteoporosis) independently from the sex and genotype of the treated animals. CONCLUSION: Even though the study suggests that proteinaceous "sticky " adjuvants are unlikely to find their way into practical vaccination, the information gained is of value as ATRex injections could provide an additional, simplified, mouse model of osteoporosis. Moreover, our results provide experimental support to the hypothesis that proteotoxic aggregates chronically activate the innate immune system in amyloid and aggregosome associated disorders.

Plasmid DNA-coding p62 as a bone effective anti-inflammatory/anabolic agent.

We recently reported that a DNA plasmid coding p62-SQSTM1 acts as an effective anti tumor vaccine against both transplantable mouse tumors and canine spontaneous mammary neoplasms. Here we report the unexpected finding that intramuscular delivery of p62 DNA exerts a powerful anti-osteoporotic activity in a mouse model of inflammatory bone loss (i.e, ovariectomy) by combining bone-sparing and osteo-synthetic effects. Notably, the suppression of osteoporosis by p62DNA was associated with a sharp down-regulation of master inflammatory cytokines, and up-regulation of endogenous p62 protein by bone-marrow stromal cells. The present data provide a solid rational to apply p62 DNA vaccine as a safe, new therapeutic for treatment of inflammatory related bone loss diseases.

Molecular stability of DNA typing short tandem repeats in the mammary tree of patients with breast cancer.

Archival pathologic specimens are a rich source for the studies of hereditary diseases, cancer genetics, and identification cases in forensic science. In this study, the intraindividual consistency of eight identifying microsatellite polymorphisms (i.e., HMTH01, vWFA31, F13A, MITMH26, FES-FPS, CD4, TPOX, CSF1PO)in a cohort of 40 patients with invasive breast carcinoma were analyzed. Nests of cancer and adjacent morphologically normal ductal-lobular structures (TDLUs) were microdissected as discrete regions from hematoxylin-eosin-stained slides. As controls for each case, DNA templates were prepared from TDLUs located in nontumor quadrants and from unaffected breast skin. Over 1,400 carefully controlled PCR reactions were reviewed, and no evidence was found for microsatellite mismatches among intraindividual cancer and control DNAs. The negative results, supported by validation experiments, strongly argue that alterations of simple repeats are rare somatic events during the onset and progression of breast cancer. This study suggests that PCR artifacts may be a relevant cause of misdiagnosis of microsatellite instability in human sporadic cancer.

Plasmids encoding protein aggregation domains act as molecular adjuvants for DNA vaccines.

BACKGROUND: DNA vaccines provide high tolerability and safety but commonly suffer from suboptimal immunogenicity. We previously reported that a plasmid vector (pATRex), encoding the DNA sequence for the von Willebrand I/A domain of the tumor endothelial marker-8 (TEM8) when given in combination with plasmid-encoded tumor antigens acted as a powerful molecular adjuvant enhancing immunity against breast and melanoma tumors. AIMS: In the present study we addressed two unsolved issues; would the adjuvant action of pATRex extend to a DNA vaccine against infectious disease and, if so, what is the mechanistic basis for pATRex adjuvant action? RESULTS: Here we show in a murine malaria vaccine model that co-administration of pATRex potentiates antibody production elicited by an intramuscular injection of plasmid encoding Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5). pATRex enhanced the B-cell response and induced increased IgG1 production consistent with TH2 polarization of the DNA vaccine response. To explore the mechanism of adjuvant action, cells were transfected in vitro with pATRex and this resulted in formation of insoluble intracellular aggregates and apoptotic cell death. Using a structural modeling approach we identified a short peptide sequence (α3-ß4) within ATRex responsible for protein aggregation and confirmed that transfection of cells with plasmid encoding this self-assembling peptide similarly triggered intracellular aggregates, caspase activation and cell death. CONCLUSION: Plasmids encoding aggregation-promoting domains induce formation of insoluble intracellular aggregates that trigger caspase activation and apoptotic cell death leading to activation of the innate immune system thereby acting as genetic adjuvants.

Pilot study of p62 DNA vaccine in dogs with mammary tumors.

Our previous data demonstrated profound anti-tumor and anti-metastatic effects of p62 (sqstm1) DNA vaccine in rodents with various types of transplantable tumors. Testing anti-cancer medicine in dogs as an intermediary step of translational research program provides two major benefits. First, clinical data collected in target animals is required for FDA/USDA approval as a veterinary anti-cancer drug or vaccine. It is noteworthy that the veterinary community is in need of novel medicine for the prevention and treatment of canine and feline cancers. The second more important benefit of testing anti-cancer vaccines in dogs is that spontaneous tumors in dogs may provide invaluable information for human trials. Here, we evaluated the effect(s) of p62 DNA vaccine on mammary tumors of dogs. We found that p62 DNA vaccine administered i.m. decreased or stabilized growth of locally advanced lesions in absence of its overall toxic effects. The observed antitumor activity was associated with lymphocyte infiltration and tumor encapsulation via fibrotic reaction. This data justifies both human clinical trials and veterinary application of p62 DNA vaccine.

Broad-spectrum anti-tumor and anti-metastatic DNA vaccine based on p62-encoding vector.

Autophagy plays an important role in neoplastic transformation of cells and in resistance of cancer cells to radio- and chemotherapy. p62 (SQSTM1) is a key component of autophagic machinery which is also involved in signal transduction. Although recent empirical observations demonstrated that p62 is overexpressed in variety of human tumors, a mechanism of p62 overexpression is not known. Here we report that the transformation of normal human mammary epithelial cells with diverse oncogenes (RAS, PIK3CA and Her2) causes marked accumulation of p62. Based on this result, we hypothesized that p62 may be a feasible candidate to be an anti-cancer DNA vaccine. Here we performed a preclinical study of a novel DNA vaccine encoding p62. Intramuscularly administered p62-encoding plasmid induced anti-p62 antibodies and exhibited strong antitumor activity in four models of allogeneic mouse tumors - B16 melanoma, Lewis lung carcinoma (LLC), S37 sarcoma, and Ca755 breast carcinoma. In mice challenged with Ca755 cells, p62 treatment had dual effect: inhibited tumor growth in some mice and prolonged life in those mice which developed tumor size similar to control. P62-encoding plasmid has demonstrated its potency both as a preventive and therapeutic vaccine. Importantly, p62 vaccination drastically suppressed metastasis formation: in B16 melanoma where tumor cells where injected intravenously, and in LLC and S37 sarcoma with spontaneous metastasis. Overall, we conclude that a p62-encoding vector(s) constitute(s) a novel, effective broad-spectrum antitumor and anti-metastatic vaccine feasible for further development and clinical trials.

Unfaithful association of FCGR2B genetic polymorphisms with susceptibility to SLE.

Correcting errors and proofreading are crucial in a post-genomic era, when DNA sequences are already part of an effective medical screening and treatments. SNPs genotyping of complex human genes can lead to questionable associations if not properly handled. Here, we report about a spurious (reitered) association between FCGR2B genetic polymorphisms and systemic lupus erythematosus.