Oxidative Stress, Mutations and Chromosomal Aberrations Induced by In Vitro and In Vivo Exposure to Furan.

Furan is a volatile compound that is formed in foods during thermal processing. It is classified as a possible human carcinogen by international authorities based on sufficient evidence of carcinogenicity from studies in experimental animals. Although a vast number of studies both in vitro and in vivo have been performed to investigate furan genotoxicity, the results are inconsistent, and its carcinogenic mode of action remains to be clarified. Here, we address the mutagenic and clastogenic activity of furan and its prime reactive metabolite cis-2 butene-1,4-dial (BDA) in mammalian cells in culture and in mouse animal models in a search for DNA lesions responsible of these effects. To this aim, Fanconi anemia-derived human cell lines defective in the repair of DNA inter-strand crosslinks (ICLs) and Ogg1-/- mice defective in the removal of 8-hydroxyguanine from DNA, were used. We show that both furan and BDA present a weak (if any) mutagenic activity but are clear inducers of clastogenic damage. ICLs are strongly indicated as key lesions for chromosomal damage whereas oxidized base lesions are unlikely to play a critical role.

Multiple roles of perforin in hampering ERBB-2 (Her-2/neu) carcinogenesis in transgenic male mice.

Perforin (pfp)-mediated cytotoxicity is one of the principal immunosurveillance mechanisms involved in the fight against cancer. However, its importance in spontaneous epithelial cancer is still poorly defined. In this study, we use a realistic mouse model that displays many features that are equivalent to human pathology to evaluate the role of pfp-dependent immunosurveillance by comparing tumor progression in rat ERBB-2 (neu) transgenic, pfp-proficient (neu(+)/pfp(+)) or pfp-deficient (neu(+)/pfp(-)) BALB/c male mice. Adult neu(+)/pfp(+) males developed poorly differentiated salivary carcinomas, whereas neu(+)/pfp(-) males displayed their salivary carcinomas noticeably earlier and showed zones of more highly differentiated tumor, indicating that pfp-mediated immunosurveillance is able not only to delay the growth kinetic of an aggressive epithelial tumor, but also to shape its histology. The role of pfp-mediated immunosurveillance appeared to be of even more dramatic importance against the less aggressive male mammary carcinomas. In neu(+)/pfp(+) males, the incidence of mammary carcinomas was a sporadic and late event. In contrast, in neu(+)/pfp(-) males their incidence was four-fold higher. This higher cancer incidence was associated with a 2-fold higher occurrence of persisting mammary remnants, a major risk factor for mammary cancer in male mice, and one that would appear to be due to pfp's previously unidentified involvement in male mammary gland rejection during embryogenesis. This work thus provides further proof of the complex role that the immune system plays in the body and gives new insight into the pathogenesis of epithelial tumors, demonstrating that the penetrance and malignancy of a tumor may be dramatically affected by pfp-dependent mechanisms.

DNA vaccination against membrane-bound Kit ligand: a new approach to inhibiting tumour growth and angiogenesis.

A functional c-Kit/Kit ligand (KitL) signalling network is required for tumour angiogenesis and growth, and therefore the c-Kit/KitL system might well be a suitable target for the cancer immunotherapy approach. We herein describe a strategy that targets membrane-bound KitL (mbKitL) via DNA vaccination. The vaccination procedure generated antibodies which are able to detect mbKitL on human tumour endothelial cells (TECs) and on the breast cancer cell line: TSA. DNA vaccination, interferes with tumour vessel formation and transplanted tumour growth in vivo. Histological analysis demonstrates that, while tumour cell proliferation and vessel stabilisation are impaired, vessel permeability is increased in mice that produce mbKitL-targeting antibodies. We also demonstrate that vessel stabilisation and tumour growth require Akt activation in endothelial cells but not in pericytes. Moreover, we found that regulatory T cells (Treg) and tumour infiltrating inflammatory cells, involved in tumour growth and angiogenesis, were reduced in number in the tumour microenvironment of mice that generate anti-mbKitL antibodies. These data provide evidence that mbKitL targeted vaccination is an effective means of inhibiting tumour angiogenesis and growth.

Early onset and enhanced growth of autochthonous mammary carcinomas in C3-deficient Her2/neu transgenic mice.

Aside from its classical role in fighting infections, complement is an important, although poorly understood, component of the tumor microenvironment. In particular, the tumor growth-regulatory activities of complement remain under debate. To assess the role of the complement system in the progression of autochthonous mammary carcinomas, we have crossed complement component 3 (C3)-deficient (C3-/- ) BALB/c male mice with BALB/c females expressing the activated rat Her2/neu oncogene (neuT). Although neuT transgenic mice develop spontaneous mammary cancers with 100% penetrance, a significantly shorter tumor latency (i.e., earlier onset of the first palpable tumor), a higher frequency of multiple tumors (multiplicity), and a dramatic increase in the tumor growth rate were found in neuT-C3-/- animals. The accelerated tumor onset observed in neuT-C3-/- mice was paralleled by an earlier onset of spontaneous lung metastases and by an increase in Her2 expression levels, primarily on the surface of tumor cells. The percentage of immune cells infiltrating neuT carcinomas was similar in C3-deficient and C3-proficient mice, with the exception of a significant increase in the frequency of regulatory T cells in neuT-C3-/- tumors. Of particular interest, the enhanced immunosuppression imparted by C3 deficiency clearly influenced the immunogenic phenotype of autochthonous mammary tumors as neuT-C3-/- malignant cells transplanted into syngeneic immunocompetent hosts gave rise to lesions with a significantly delayed kinetics and reduced incidence as compared with cells obtained from neuT C3-proficient tumors. Finally, increased blood vessel permeability was evident in neuT-C3-/- tumors, although a similar number of tumor vessels was found in neuT and neuT-C3-/- lesions. Altogether, these data suggest that complement plays a crucial role in the immunosurveillance and, possibly, the immunoediting of Her2-driven autochthonous mammary tumors.

A DNA vaccine against ERBB2 impairs chemical carcinogenesis in random-bred hamsters.

Vaccines against oncoantigens halt early neoplastic lesions in several cancer-prone, genetically engineered mouse models, whereas their ability to prevent chemical carcinogenesis has not been explored. This is a significant issue, as exposure to chemical mutagens is responsible for a substantial percentage of cancers worldwide. Here, we show that the archetypal oncoantigen ERBB2 is transiently overexpressed in Syrian hamsters during the early stages of 7,12-dimethylbenz[α]anthracene (DMBA)-induced oral carcinogenesis. Repeated DNA vaccinations against ERBB2 significantly reduce the number, size, and severity of oral lesions in a manner directly proportional to the anti-ERBB2 antibody response. These results support the prospects of vaccines as a fresh strategy in the management of individuals at risk for exposure to defined carcinogenic agents.

The human splice variant Δ16HER2 induces rapid tumor onset in a reporter transgenic mouse.

Several transgenic mice models solidly support the hypothesis that HER2 (ERBB2) overexpression or mutation promotes tumorigenesis. Recently, a HER2 splice variant lacking exon-16 (Δ16HER2) has been detected in human breast carcinomas. This alternative protein, a normal byproduct of HER2, has an increased transforming potency compared to wild-type (wt) HER2 receptors. To examine the ability of Δ16HER2 to transform mammary epithelium in vivo and to monitor Δ16HER2-driven tumorigenesis in live mice, we generated and characterized a mouse line that transgenically expresses both human Δ16HER2 and firefly luciferase under the transcriptional control of the MMTV promoter. All the transgenic females developed multifocal mammary tumors with a rapid onset and an average latency of 15.11 weeks. Immunohistochemical analysis revealed the concurrent expression of luciferase and the human Δ16HER2 oncogene only in the mammary gland and in strict correlation with tumor development. Transgenic Δ16HER2 expressed on the tumor cell plasma membrane from spontaneous mammary adenocarcinomas formed constitutively active homodimers able to activate the oncogenic signal transduction pathway mediated through Src kinase. These new transgenic animals demonstrate the ability of the human Δ16HER2 isoform to transform "per se" mammary epithelium in vivo. The high tumor incidence as well as the short latency strongly suggests that the Δ16HER2 splice variant represents the transforming form of the HER2 oncoprotein.

Androgen deprivation boosts prostatic infiltration of cytotoxic and regulatory T lymphocytes and has no effect on disease-free survival in prostate cancer patients.

PURPOSE: The value of neoadjuvant hormone therapy (NHT) prior to radical prostatectomy as a means of restraining prostate cancer (PCa) and strengthening its immunotherapy is still uncertain. This article asks whether it subverts immunoregulatory pathways governing tumor microenvironments, and has an impact on patient outcome. EXPERIMENTAL DESIGN: We microdissected epithelium and stroma from cancerous and normal prostate specimens from 126 prostatectomized patients, of whom 76 had received NHT, to detect cytokine/chemokine gene expression levels by real-time reverse transcriptase PCR. Confocal microscopy was used to identify cytokine/chemokine cell sources, and immunostainings to characterize lymphocyte subsets whose prognostic effects were assessed by Kaplan-Meier analyses. RESULTS: NHT boosted the expression of IL-7 in the stroma and that of IFNγ-inducible protein-10/CXCL10 in the glandular epithelium of normal prostate tissue, and restored the CD8(+) lymphocyte depletion occurring in PCa, whereas it significantly increased the CD4(+) lymphocyte infiltrate. Lymphocytes, mostly with CD8(+) phenotype, expressed the T-cell intracellular antigen-1, granzyme-B, and perforin, typical of cytotoxic-effector T cells. NHT also induced thymus and activation-regulated chemokine/CCL17 production by monocytes/macrophages in the prostate and draining lymph nodes, and increased the number of their Forkhead box P3 (Foxp3)(+)CD25(+)CD127(-) T regulatory (Treg) cells. The χ(2) test disclosed the lack of association (P = 0.27) between NHT and the high intratumoral CD8(+)/Treg ratio indicative of a good prognosis. CONCLUSIONS: Androgen withdrawal regulates cytokine/chemokine gene expression in normal prostate and lymphoid tissues, and this probably favors both CD8(+) and Treg infiltrates, leaves their intratumoral balance unchanged, and thus has no impact on disease-free survival.

The Mutyh base excision repair gene influences the inflammatory response in a mouse model of ulcerative colitis.

BACKGROUND: The Mutyh DNA glycosylase is involved in the repair of oxidized DNA bases. Mutations in the human MUTYH gene are responsible for colorectal cancer in familial adenomatous polyposis. Since defective DNA repair genes might contribute to the increased cancer risk associated with inflammatory bowel diseases, we compared the inflammatory response of wild-type and Mutyh(-/-) mice to oxidative stress. METHODOLOGY/PRINCIPAL FINDINGS: The severity of colitis, changes in expression of genes involved in DNA repair and inflammation, DNA 8-oxoguanine levels and microsatellite instability were analysed in colon of mice treated with dextran sulfate sodium (DSS). The Mutyh(-/-) phenotype was associated with a significant accumulation of 8-oxoguanine in colon DNA of treated mice. A single DSS cycle induced severe acute ulcerative colitis in wild-type mice, whereas lesions were modest in Mutyh(-/-) mice, and this was associated with moderate variations in the expression of several cytokines. Eight DSS cycles caused chronic colitis in both wild-type and Mutyh(-/-) mice. Lymphoid hyperplasia and a significant reduction in Foxp3(+) regulatory T cells were observed only in Mutyh(-/-) mice. CONCLUSIONS: The findings indicate that, in this model of ulcerative colitis, Mutyh plays a major role in maintaining intestinal integrity by affecting the inflammatory response.

Sorafenib's inhibition of prostate cancer growth in transgenic adenocarcinoma mouse prostate mice and its differential effects on endothelial and pericyte growth during tumor angiogenesis.

OBJECTIVE: To evaluate Sorafenib's efficacy (60 mg/kg/d per os) in preventing the transformation of high grade prostate intraepithelial neoplasia (HGPIN) into adenocarcinoma (ADC) and in inhibiting the onset and progression of poorly differentiated carcinoma (PDC) in transgenic adenocarcinoma mouse prostate (TRAMP) mice. STUDY DESIGN: Forty-four TRAMP mice were randomly divided into 2 groups of 22 and assigned to daily treatment by gavage with vehicle only or Sorafenib from the 10th to the 26th week of age. At 26 weeks of age the mice were killed, and their genitourinary apparatus was removed and examined by histology, immunohistochemistry and confocal microscopy. RESULTS: Sorafenib reduced HGPIN growth and progression to ADC and was probably also effective in PDC inhibition. The major effect of Sorafenib was on tumor angiogenesis. Interestingly a dissociation between endothelial cells and pericytes was noted in treated PDC since inhibition of pericyte recruitment was less complete than that of endothelial cells. CONCLUSION: Sorafenib's potent antiangiogenic action may be supposed to be exerted primarily by inhibiting endothelial proliferation and sprouting, whereas its inhibition of pericyte recruitment and maturation is less complete. These observations suggest that Sorafenib's effects could be improved by the joint employment of substances capable of interfering with the recruitment and organization of pericytes.

Erbb2 DNA vaccine combined with regulatory T cell deletion enhances antibody response and reveals latent low-avidity T cells: potential and limits of its therapeutic efficacy.

Rat (r)Erbb2 transgenic BALB-neuT mice genetically predestined to develop multiple invasive carcinomas allow an assessment of the potential of a vaccine against the stages of cancer progression. Because of rErbb2 expression in the thymus and its overexpression in the mammary gland, CD8(+) T cell clones reacting at high avidity with dominant rErbb2 epitopes are deleted in these mice. In BALB-neuT mice with diffuse and invasive in situ lesions and almost palpable carcinomas, a temporary regulatory T cells depletion combined with anti-rErbb2 vaccine markedly enhanced the anti-rErbb2 Ab response and allowed the expansion of latent pools of low-avidity CD8(+) T cells bearing TCRs repertoire reacting with the rErbb2 dominant peptide. This combination of a higher Ab response and activation of a low-avidity cytotoxic response persistently blocked tumor progression at stages in which the vaccine alone was ineffective. However, when diffuse and invasive microscopic cancers become almost palpable, this combination was no longer able to secure a significant extension of mice survival.