Treatment with Angiotensin-(1-7) Prevents Development of Oral Papilloma Induced in K-ras Transgenic Mice.

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant cancer affecting the oral cavity. It is characterized by high morbidity and very few therapeutic options. Angiotensin (Ang)-(1-7) is a biologically active heptapeptide, generated predominantly from AngII (Ang-(1-8)) by the enzymatic activity of angiotensin-converting enzyme 2 (ACE 2). Previous studies have shown that Ang-(1-7) counterbalances AngII pro-tumorigenic actions in different pathophysiological settings, exhibiting antiproliferative and anti-angiogenic properties in cancer cells. However, the prevailing effects of Ang-(1-7) in the oral epithelium have not been established in vivo. Here, we used an inducible oral-specific mouse model, where the expression of a tamoxifen-inducible Cre recombinase (CreERtam), which is under the control of the cytokeratin 14 promoter (K14-CreERtam), induces the expression of the K-ras oncogenic variant KrasG12D (LSLK-rasG12D). These mice develop highly proliferative squamous papilloma in the oral cavity and hyperplasia exclusively in oral mucosa within one month after tamoxifen treatment. Ang-(1-7) treated mice showed a reduced papilloma development accompanied by a significant reduction in cell proliferation and a decrease in pS6 positivity, the most downstream target of the PI3K/Akt/mTOR signaling route in oral papilloma. These results suggest that Ang-(1-7) may be a novel therapeutic target for OSCC.

Curcumin Enriched VCO Protects against 7,12-Dimethyl Benz[a] Anthracene-Induced Skin Papilloma in Mice.

Virgin coconut oil (VCO) and turmeric are traditionally being used in Indian cuisine systems; VCO is a natural combination of medium-chain triglyceride and polyphenols with established pharmacological potential. Curcumin isolated from turmeric is renowned for its anticancer properties, however, with limited clinical success due to poor bioavailability. Considering the lipophilic nature of VCO, curcumin added to VCO is expected to have synergistic/additive actions. In this study, the chemopreventive potential of curcumin enriched VCO (VCr) (4 and 8 mL/Kg orally) was analyzed in 7,12-dimethyl benz[a]anthracene (DMBA;470 nmoles/200 µL/week for two weeks topical)/croton oil (3% v/v in 200 µL acetone twice a week for 6 weeks topical) induced skin papilloma. In DMBA control animals, an average incidence of 13 papilloma/mice (latency period of 11.6 ± 1.5 weeks) was recorded. Pretreatment with VCrH (8 mL/kg) had a 60% inhibition of tumor index, and an increased latency period (12.5 ± 0.9 weeks). Additionally, DMBA/croton oil-induced reduction in glutathione levels and concomitant increase in thiobarbituric acid reactive substance (TBARS) in the skin microenvironment were restored by VCr. The study thus suggests that the VCr promotes antioxidant status in vivo and imparts an improved anticarcinogenic potential. However, further studies are necessary to ascertain the improvement in bioavailability of curcumin .

Prophylactic human papilloma virus vaccination in head and neck: indications and future perspectives.

PURPOSE OF REVIEW: To gain the evidence-based knowledge concerning the efficacy of HPV vaccination for oropharyngeal sites and to highlight the trials and strategies for vaccine administration in HPV-dependent head and neck diseases. RECENT FINDINGS: Vaccination can be provided in two injections. There is increasing anecdotal evidence that therapeutic vaccination is effective in treatment of recurrent respiratory papillomatosis. SUMMARY: The availability and broadening spectrum of HPV vaccines make possible the prevention of cervical and other HPV-dependent diseases. Vaccination is now included in the national immunization programs of most industrial countries and will be used, it is hoped, in developing countries within the next few years. In developing countries, few women are screened for cervical precancerous lesions, making immunization even more important. In affluent countries and matured societies, with high coverage of cervical screening, the focus of interest will shift to other HPV-related diseases. The HPV vaccination is effective in preventing oral infection with types targeted by the vaccines.

Vacuna contra el virus papiloma humano como tratamiento para la papilomatosis respiratoria recurrente / Human papilloma virus vaccination treatment for recurrent respiratory papillomatosis

RESUMEN Una de las manifestaciones clínicas del virus papiloma humano (VPH) es la papilomatosis respiratoria recurrente (PRR), que se caracteriza por la proliferación de lesiones epiteliales verrucosas recurrentes en la mucosa respiratoria, pudiendo progresar a obstrucción de vía aérea o presentar transformación maligna. El tratamiento de primera línea quirúrgico, pero dada su alta recurrencia ha tomado peso el tratamiento adyuvante, como la vacuna tetravalente contra VPH. Sin embargo, existe controversia respecto a su eficacia. El objetivo de esta revisión es analizar la efectividad de la vacuna contra VPH como tratamiento adyuvante de la PRR, para lo cual hicimos una revisión de la literatura sobre la efectividad de la vacuna tetravalente contra VPH para PRR, realizando una búsqueda en diversas fuentes: Pubmed, MEDLINE, EMBASE, Cochrane, Google Scholar y Epistemonikos. Se seleccionaron los estudios que responden a la pregunta y se analizaron los datos de los estudios primarios. Se encontraron cinco estudios primarios no aleatorizados, todos a favor de la vacuna como tratamiento. Concluimos con baja certeza de evidencia, que la vacuna es posiblemente efectiva para pacientes con PRR en disminuir el número de recurrencias, aumentar el intervalo entre cirugías, lograr remisión completa o parcial de la enfermedad y aumentar significativamente los títulos de anticuerpos anti-VPH.

ABSTRACT A clinical manifestation of human papillomavirus (HPV) is recurrent respiratory papillomatosis (RRP), characterized by the proliferation of recurrent verrucous epithelial lesions in the respiratory mucosa, which may progress to airway obstruction or malignant transformation. First-line treatment is surgery, but given its high recurrence the use of adjuvant therapy, such as the quadrivalent vaccine, has gained importance. However, there is controversy regarding its effectiveness. To analyze the effectiveness of the HPV vaccine as an adjuvant treatment for RRP a review of the literature on the effectiveness of HPV tetravalent vaccine for RRP was performed by searching databases such as Pubmed, MEDLINE, EMBASE, Cochrane, Google Scholar and Epistemonikos. We selected the studies that answered the question and analyzed the data from all of which supported the vaccine as treatment. None were randomized controlled trials. We conclude, with low certainty of evidence, that the vaccine is possibly effective for RRP in decreasing the number of recurrences, increasing the intersurgical interval, achieving complete or partial remission of disease and significantly increasing anti-HPV antibodies.

Factores de riesgo asociados a la presencia de virus del papiloma humano (VPH) en mujeres sexualmente activas usuarias de Clínica Estrada, Municipio de El Paraíso, El Paraíso, Honduras, año 2017 / Risk factors associated with the presence of human papillomavirus (HPV) in sexually active women users of Clínica Estrada, Municipality of El Paraíso, El Paraíso, Honduras, 2017

OBJETIVO: Determinar los factores de riesgo asociados a la presencia de virus del papiloma humano (VPH) en mujeres sexualmente activas usuarias de Clínica Estrada, Municipio de El Paraíso, El Paraíso, Honduras, año 2017. DISEÑO: Estudio transversal, analítico, retrospectivo que se realizó en la clínica Estrada en el departamento de El paraíso Honduras, se revisaron 68 historias clínicas de pacientes que se realizaron el examen para detección del Virus de Papiloma Humano y pruebas de inspección acido acética (IVAA); el análisis de datos se realizó en microsoft excel y en el paquete estadístico SPSS versión 23.0; se usó medidas de tendencia central y de dispersión, se calculó el valor de chi cuadrado con un 95% de confianza y la prueba T student. RESULTADOS: La prevalencia de VPH en mujeres sexualmente activas fue de 60.2%positivas y un 39.7% negativas; de procedencia en el área urbana con el 53,7% y 46,3% para la rural; en mujeres casadas un 41,5% positivas; con ITS previa un 84,6%; con citologías previas 80,5%. CONCLUSIONES: La presencia del VPH en mujeres sexualmente activas en Honduras es realmente alarmante, ya que el cáncer cervicouterino es uno de los principales causantes de muerte en el país y este es causado principalmente por dicho virus y se asocia en este estudio con una infección de transmisión sexual previa

In vivo evaluation of antitumoral and antiangiogenic effect of imiquimod-loaded polymeric nanoparticles.

The chemotherapeutic agent imiquimod (Imq) is used to treat skin cancers, the most common type of human cancer. However, the high incidence of local and systemic side effects associated with its use as well as its low skin permeation impair patient compliance and therapeutic effectiveness To overcome these limitations, nanostructured systems such as nanoparticles can be a promising alternative. Nanoparticles are submicron particles (size less than 1000 nm) with high surface area that facilitates the interaction and cellular uptake by biological membranes. Therefore, the aim of the present work is to evaluate antiangiogenic effect and antitumoral activity of imiquimod-loaded nanoparticles compared to market Imq formulation. Polymeric nanoparticles containing Imq were obtained by the technique of precipitation of preformed polymer. Antiangiogenic activity of the formulations was determined in chicken embryo chorioallantoic membrane (CAM) and its chemopreventive potential was evaluate during multistage DMBA and croton oil model of skin carcinogenesis in mice. Nanoparticles containing Imq presented antiangiogenic activity superior than negative control, placebo dispersion and market Imq (p < 0.05) in the CAM model and also significantly reduced the number and size of papillomas compared to all other groups. These results suggest, therefore, that the obtained delivery system can be an alternative to treat diseases related to vessels formation and also potentially increase cutaneous permeation and efficacy of poor soluble drugs normally used to treat cutaneous diseases.

Gardasil Vaccination for Recurrent Laryngeal Papillomatosis in Adult Men Second Report: Negative Conversion of HPV in Laryngeal Secretions.

BACKGROUND: In our first report on antibody levels in middle-aged and older men with recurrent laryngeal papillomatosis (RLP), we reported increases in human papillomavirus (HPV) antibody levels similar to those seen in adult women and young men. We posited that HPV antibodies produced in laryngeal mucus by Gardasil would prevent postoperative reinfection in patients with RLP. STUDY DESIGN: This is a case series study. PURPOSE: The purpose of this study was to examine whether Gardasil injection effectively inhibits recurrence of RLP. Specifically, in this second report, whether HPV antibodies produced in laryngeal secretions by Gardasil are capable of causing negative conversion of HPV-DNA (deoxyribonucleic acid) in laryngeal mucosa was investigated. METHODS: A total of 11 patients for whom antibodies were measured in the first report were studied. Before vaccination and after 1 year Post-vaccination, HPV screening tests were performed on laryngeal secretions, and whether HPV-DNA negative conversion had occurred was evaluated. At the time of collection of laryngeal secretions, the presence or absence of laryngeal papillomas was examined. RESULTS: Before vaccination, all patients were HPV low-risk positive on laryngeal secretion screening tests. After vaccination, three patients were positive. Laryngeal papillomas remained in five patients. CONCLUSIONS: The HPV-DNA test showed negative conversion in eight of 11 (72.7%) patients after vaccination. Residual laryngeal papillomas were found in five of 11 (45.5%) patients. The serum HPV antibody titer did not differ significantly between the group in which laryngeal secretions showed HPV negative conversion and the group in which conversion did not occur. The serum antibody titer did not differ significantly as a function of whether there were residual tumors.

Production of highly immunogenic virus-like particles of bovine papillomavirus type 6 in silkworm pupae.

Bovine papillomaviruses (BPVs) are the causative agent of bovine teat papillomatosis, which can lead to severe economic losses in dairy cattle. Among the 14 identified BPV genotypes, BPV type 6 (BPV6) is the most frequently detected in teat papilloma lesions, and is therefore thought to play a major role in teat papillomatosis. To develop an effective vaccine against BPV6 infection, we produced virus-like particles of BPV6 (BPV6-VLP) in silkworm (Bombyx mori) pupae and purified these by heparin affinity chromatography using a single column. About 0.7mg purified BPV6-VLP was obtained from one pupa. BPV6-VLP-immunized mice produced a specific IgG to BPV6 that recognized BPV6 antigen with high sensitivity in an immunohistochemical analysis. Thus, silkworm pupae are a useful bioreactor for the production of BPV6-VLP, which can potentially be used as a vaccine for bovine teat papillomatosis.

Dendrimer conjugated estramustine nanocrystalline 'Dendot': An effective inhibitor of DMBA-TPA induced papilloma formation in mouse.

Clinically approved anticancer drug estramustine mediates its function by impairing microtubule polymerization. However, the low aqueous solubility and high toxicity limit its anticancer activity via the oral route. Previously, efforts have been made to develop an enhanced water soluble form of estramustine as estramustine phosphate (EM) but acidic gastrointestinal pH breaks the phosphate derivative via oral administration. As an alternative approach, we have made an effort to enhance solubility and minimize toxicity in vivo by conjugating EM to a poly(amidoamine) (PAMAM) dendrimer, which generated the sustained release of dendrimer conjugate (DEM). To the best of our knowledge, for the first time, we report the direct proof of the nano-crystalline 'DenDot' of DEM on TEM image. The toxicity study showed that both EM and DEM were nontoxic up to 20mg/kg. A comparative anti-papilloma study was also performed with EM and dendrimer conjugates (DEM) using a two-stage mouse skin carcinogenesis model. We found that DEM was more effective in inhibiting skin tumor formation than EM. Histopathology and immunohistochemistry studies further indicated that DEM treatment increased cell apoptosis, and reduced epithelial hyperplasia, cell proliferation and inflammation in skin tissues of mice. In addition, the synthetic DEM conjugate inhibited skin tumor progression more effectively than EM.

Diez años de vacunación frente al virus del papiloma: nuevos retos y oportunidades / Ten years of papillomavirus vaccination: new challenges and opportunities

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Vacunación en adultos / Vaccination in adults

ResumenIntroducción:cada año, miles de adultos mueren por causa de enfermedades prevenibles mediante vacunación. Sin embargo, la aplicación de vacunas en adultos es muy baja a nivel mundial por múltiples razones, incluyendo los altos costos de implementación.Objetivos:discutir las recomendaciones nacionales e internacionales de inmunización de personas mayores de 18 años, incluyendo las poblaciones con alto riesgo de adquirir infecciones inmunoprevenibles y resumirlas en un esquema recomendado para vacunación de adultos en general, y personas con elevado nivel de riesgo.Métodos:se efectuó una revisión no sistemática de bibliografía médica y científica publicada entre 2000 y 2017, concerniente a vacunación en adultos. Así mismo, se compararon los esquemas de inmunización vigentes en América y Europa.Conclusiones:las recomendaciones para vacunación en adultos se basan principalmente en edad, condiciones médicas subyacentes, estilo de vida, inmunizaciones previas, características epidemiológicas locales y viajes. La necesidad de aplicar un esquema de vacunación adecuado a la población general y a poblaciones con factores de riesgo, representa una medida de gran importancia en un sistema de salud funcional. En este sentido, la adecuada asesoría e información provenientes del personal de salud constituyen un predictor clave en la inmunización de adultos.

AbstractIntroduction:Every year thousands of adults die from vaccine preventable disease worldwide. Nevertheless, the vaccine application rates maintain in relative low levels for multiple reason, including high costs of the implementation of vaccination programs.Objectives:Discuss national and international existing immunization schemes for adult persons, including high risk populations for the acquisition of immune preventable infections and resume this knowledge in vaccination schemes for adults in general and high risk populationMethods:A nonsystematic revision of medical and scientific literature related to adult vaccination topics from the years 2000 to 2017 was performed. As well, a comparison between actual vaccination schemes from American and European countries has been realized.Conclusion:Vaccination recommendations are based in multiple factors like age, individual medical history, lifestyle, formerly applied vaccinations, local epidemiologic criteria end traveling activity.The application of adequate vaccination scheme for both, adults in general and an adaptation for persons with elevated risk factors, represents a crucial element for effective health system. Therefore, the adequate assessing and information provided by medical personnel represents a key factor in successful vaccination and disease prevention.

Suppression of skin tumorigenesis in CD109-deficient mice.

CD109 is a glycosylphosphatidylinositol-anchored glycoprotein that is highly expressed in several types of human cancers, particularly squamous cell carcinomas. We previously reported that CD109-deficient mice exhibit epidermal hyperplasia and chronic skin inflammation. Although we found that CD109 regulates differentiation of keratinocytes in vivo, the function of CD109 in tumorigenesis remains unknown. In this study, we investigated the role of CD109 in skin tumorigenesis using a two-stage carcinogenesis model in CD109-deficient mice with chronic skin inflammation. Immunohistochemical analysis revealed a higher level of TGF-ß protein expression in the dermis of CD109-deficient mice than in that of wild-type mice. Additionally, immunofluorescence analysis showed that Smad2 phosphorylation and Nrf2 expression were enhanced in primary keratinocytes from CD109-deficient mice compared with in those from wild-type mice. Although no significant difference was found in conversion rates from papilloma to carcinoma between wild-type and CD109-deficient mice in the carcinogenesis model, we observed fewer and smaller papillomas in CD109-deficient mice than in wild-type mice. Apoptosis and DNA damage marker levels were significantly reduced in CD109-deficient skin compared with in wild-type skin at 24 h after 7, 12-dimethylbenz (α) anthracene treatment. Furthermore, mutation-specific PCR revealed that the mutation frequency of the H-ras gene was less in CD109-deficient skin than in wild-type skin in this model. These results suggest that CD109 deficiency suppresses skin tumorigenesis by enhancing TGF-ß/Smad/Nrf2 pathway activity and decreasing the mutation frequency of the H-ras gene.

Attenuation of DMBA/croton oil induced mouse skin papilloma by Apodytes dimidiata mediated by its antioxidant and antimutagenic potential.

Context Considering the role of cellular oxidative stress in mutations and subsequent transformation, phytochemicals with antioxidant potential has become a primary choice as chemopreventives. Apodytes dimidiata E. Mey. Ex. Arn (Icacinaceae), a widely used plant in Zulu traditional medicine, is reported to possess antioxidant activity. Objective To investigate the chemopreventive efficacy of methanol extract of A. dimidiata leaf (AMF). Materials and methods Antimutagenic potential of AMF (25, 50 and 75 µg/plate) was evaluated by the Ames test. The ability of AMF (100 and 250 mg/kg orally) on restoration of depleted antioxidant status by sodium fluoride (NaF) was analysed on BALB/c mice. 7,12-Dimethylbenz[a]anthracene/croton oil induced mouse skin papilloma model was studied up to 20 weeks to analyse the anticarcinogenic effect of AMF (1%, 3% and 5% topically, twice weekly for 6 weeks). Phytochemicals of AMF were characterized by GC-MS. Results AMF (75 µg/plate) reverted 4-nitro-o-phenylenediamine (NPDA) induced mutations in Salmonella typhimurium strains, TA 98, 100 and 102 by 74.8%, 72.5% and 69.3%, respectively. Against sodium azide, the percentage reversion was 80.4, 71.3 and 71.3. In mice, AMF (250 mg/kg for 4 days) increased the serum superoxide dismutase (SOD) and catalase activities by 48.71% and 30.3% against the NaF-induced drop. GSH level was improved by 48.59% with a concomitant decrease in TBARS (57.67%). The skin papilloma reduction was 79.32% for 5% AMF. Squalene, dodecanoic, tetradecanoic and hexadecanoic acids are the known antioxidant and chemopreventive molecules identified by GC-MS. Discussion and conclusion Antioxidant and antimutagenic activities of AMF might have contributed to its anticarcinogenic potential.

UCP2 knockout suppresses mouse skin carcinogenesis.

Mitochondrial uncoupling (uncouples electron transport from ATP production) has recently been proposed as a novel survival mechanism for cancer cells, and reduction in free radical generation is the accepted mechanism of action. However, there is no direct evidence supporting that uncoupling proteins promote carcinogenesis. Herein, we examined whether mitochondrial uncoupling affects mouse skin carcinogenesis using uncoupling protein 2 (UCP2) homozygous knockout and wild-type mice. The results indicate that knockout of Ucp2 significantly reduced the formation of both benign (papilloma) and malignant (squamous cell carcinoma) tumors. UCP2 knockout did not cause increases in apoptosis during skin carcinogenesis. The rates of oxygen consumption were decreased only in the carcinogen-treated UCP2 knockout mice, whereas glycolysis was increased only in the carcinogen-treated wild-type mice. Finally, the levels of metabolites pyruvate, malate, and succinate showed different trends after carcinogen treatments between the wild-type and UCP2 knockout mice. Our study is the first to demonstrate that Ucp2 knockout suppresses carcinogenesis in vivo. Together with early studies showing that UCP2 is overexpressed in a number of human cancers, UCP2 could be a potential target for cancer prevention and/or therapy. Cancer Prev Res; 8(6); 487-91. ©2015 AACR.

Thuya occidentalis CH12 como tratamento alternativo da papilomatose canina / Thuya occidentalis CH12 as an alternative treatment to dog papilomatosis

RESUMO A papilomatose é uma doença de natureza crônica e pode causar tumores epiteliais e na mucosa. Não possui predileção por sexo, raça ou idade, mas comumente aparece em animais jovens. As lesões papilares ocorrem principalmente na mucosa bucal, nos lábios, língua e da faringe, além destes, também são encontradas na forma ocular e cutânea. Este estudo teve como objetivo relatar a eficácia da Thuya occidentalis CH12, uma medicação homeopática de uso comum, no tratamento de cães com papilomatose. Os resultados positivos puderam ser vistos, em alguns casos, já na primeira semana do tratamento, em outros, após vinte dias, e o desaparecimento total das lesões, na maioria dos casos, ocorreu com quinze dias. Alicerçada no princípio da similitude, a homeopatia apóia-se na observação experimental de que toda substância capaz de provocar determinados sintomas em uma pessoa sadia, é capaz de curar estes mesmos sintomas em uma pessoa enferma. A Thuya occidentalis provou ser eficiente contra lesões de papilomavírus canina, e apresentou resultados rápidos e com um valor econômico acessível.

ABSTRACT The papillomatosis is a disease of chronic nature and can cause epithelial and mucosa tumors. . It may affect any gender, race or age but is most common in young animals. The papillary lesions occur mainly on the oral mucosa, in the lips, tongue and pharynx, besides appearing also in the eeyes and skin. This study aimed to report the effectiveness of the Thuya occidentalis CH12 , a homeopathic medication commonly used in the treatment of dogs with papillomatosis . The positive results could be noticed, in some cases, even in the first week of treatment , or after twenty days, with the total remission of the lesions occurring in most of the cases within fifteen days . Founded based on the similarity principle, the homeopathy relies on the experimental observation that any substance capable of causing certain symptoms in a healthy person can cure these same symptoms in a sick person. The Thuya occidentalis proved to be effective against canine papillomavirus lesions, and with fast results at an affordable economic value.

Chemopreventive potential of Apium leptophyllum (Pers.) against DMBA induced skin carcinogenesis model by modulatory influence on biochemical and antioxidant biomarkers in Swiss mice.

AIM: The study was designed to investigate the chemopreventive potential of flavonoidal fractions of Apium leptophyllum fruits (FFALF) on Swiss mice. MATERIALS AND METHODS: Skin tumor or papilloma was developed by topical application of DMBA (25 µg in 0.1 ml acetone) on intrascapular region of mice, twice weekly for 8 weeks. The animals were divided into six groups: Group I (vehicle control); group II (FFALF control, 5 mg/kg); group III (carcinogenic control, DMBA treated initially for 8 weeks); and group IV, V and VI as pre-treated group (FFALF 5, 10 and 20 mg/kg respectively for 16 weeks along with DMBA treatment). After the 16(th) week of treatment; the tumor morphology, skin histopathology, and biochemical and antioxidant biomarkers were measured and compared with carcinogenic control as well as vehicle control. RESULTS: The co-administration of FFALF with DMBA-treated groups showed significant (P ≤ 0.001) prevention against skin papilloma and normalized the status of lipid peroxidation with antioxidant biomarkers in a dose-dependent manner as compared to carcinogenic control. CONCLUSIONS: Thus, the present study suggests that the FFALF is non-carcinogenic and has chemopreventive potential on DMBA-induced carcinogenesis in mouse, which may be due to the modulation of cutaneous lipid peroxidation or enhancement of total antioxidant capacity.

Chemopreventive activity of turmeric essential oil and possible mechanisms of action.

This study aimed to evaluate the antimutagenic and anticarcinogenic activity of turmeric essential oil as well as to establish biochemical mechanisms of action. Antimutagenicity testing was accomplished using strains and known mutagens with and without microsomal activation. Anticarcinogenic activity was assessed by topical application of 7, 12 - dimethylbenz[a]anthracene (DMBA) as initiator and 1% croton oil as promoter for the induction of skin papillomas in mice. Inhibition of p450 enzymes by TEO was studied using various resorufins and aminopyrene as substrate. Turmeric essential oil (TEO) showed significant antimutagenic activity (p<0.001) against direct acting mutagens such as sodium azide (NaN3), 4-nitro-O-phenylenediamine (NPD) and N-methyl- N-nitro N'nitrosoguanine (MNNG). TEO was found to have significant antimutagenic effect (>90%) against mutagen needing metabolic activation such as 2-acetamidoflourene (2-AAF). The study also revealed that TEO significantly inhibited (p<0.001) the mutagenicity induced by tobacco extract to Salmonella TA 102 strain. DMBA and croton oil induced papilloma development in mice was found to be delayed and prevented significantly by TEO application. Moreover TEO significantly (P<0.001) inhibited isoforms of cytochrome p450 (CYP1A1, CYP1A2, CYP2B1/2, CYP2A, CYP2B and CYP3A) enzymes in vitro, which are involved in the activation of carcinogens. Results indicated that TEO is antimutagenic and anticarcinogenic and inhibition of enzymes (p450) involved in the activation of carcinogen is one of its mechanisms of action.

In vivo long-term effects of retinoic acid exposure in utero on induced tumours in adult mouse skin.

BACKGROUND: Retinoic acid (RA) and its analogues (retinoids) are promising agents in skin cancer prevention following either topical application or oral administration. However, long-term in vivo effects of RA on chemically induced hyperplastic epidermal foci in adult mouse skin have also been described, casting some doubt with regard to its chemopreventive activity. HYPOTHESIS/OBJECTIVES: To characterize chemically induced skin tumours and to investigate the in vivo long-term action and preventive effect of RA on adult mouse skin carcinogenesis. ANIMALS: Fifty-six adult Naval Medical Research Institute mice, exposed (n = 28) or not exposed (n = 28) to RA in utero. METHODS: Mice were treated with a standard two-stage skin carcinogenesis protocol, which included an initiating application of 7,12-dimethylbenz(a)anthracene followed by promotion with 12-O-tetradecanoylphorbol 13-acetate. RESULTS: Retinoic acid administered to pregnant mice showed a long-term inhibitory action on cell differentiation and development of chemically induced tumours on the adult skin of their offspring, as well as a stimulatory effect on cell proliferation and expression of an early marker of malignant progression (keratin 13). CONCLUSIONS AND CLINICAL IMPORTANCE: The results suggest that RA exposure in utero confers long-lasting effects on adult mouse skin carcinogenesis. These include chemopreventive activity (reduced number of tumours), as well as enhancement of squamous papilloma progression, which appears to be due to enhanced keratinocyte proliferation and suppression of epidermal maturation. The clinical significance of these findings is not known for other routes of RA administration at this time.