EGFR and HER-2 oncogenes expression in an experimental model of two-stage chemically induced carcinogenesis in mouse skin.

The aim of the study was to investigate the expression of EGFR and HER-2 oncogenes using an experimental two stage chemically induced carcinogenesis protocol on the dorsal skin in FVB/N mice. Forty female FVB/N mice 4 weeks old, were grouped into one control (n = 8) and two experimental groups (Group A: n = 16, Group B: n = 16) following a randomization process. Two-stage carcinogenesis protocol, was implicated, including an initial treatment with 97.4 nmol DMBA on their shaved dorsal skin and subsequent treatments of 32.4 nmol TPA applications after 13 weeks for Group A and after 20 weeks for Group B. The control group C, received no treatment. Skin was examined weekly for tumor development. Post-experiment, animals were euthanized for tissue analysis. The histological status of the skin lesions in the experimental groups corresponded well with tumour advancement (from dysplasia to poorly-differentiated carcinoma). Tumour sections were evaluated histologically and immunohistochemically. EGFR expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 008 respectively), while tended to be higher in benign tumours (p = 079), compared to normal histology. Moreover, mean percentage of EGFR positive expression in malignant tumours was significantly higher than in benign tumours (p < 001). HER-2 expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 015 respectively), while tended to be higher in benign tumours (p = 085), compared to normal histology. Furthermore, mean percentage of HER-2 positive expression in malignant tumours was significantly higher than in benign tumours (p = 005). The study demonstrated that in FVB/N mice subjected to a two-stage chemically induced carcinogenesis protocol, there was a significant increase in the expression of EGFR and HER-2 oncogenes in precancerous and malignant skin lesions compared to normal tissue. This suggests a potentially early role of these oncogenes in the progression of skin tumours in this model.

Serum Raman spectroscopy: Evaluation of tumour load variations in experimental carcinogenesis.

Several serum Raman spectroscopy (RS) studies have demonstrated its potential as an oral cancer screening tool. This study investigates influence of low tumour load (LTL) and high tumour load (HTL) on serum RS using hamster buccal pouch model of experimental oral carcinogenesis. Sera of untreated control, LTL, and HTL groups at week intervals during malignant transformation were employed. Serum Raman spectra were subjected to multivariate analyses-principal component analysis, principal component-based linear discriminant analysis (for stratification of study groups), and multivariate curve resolution-alternating least squares (MCR-ALS) (to comprehend biomolecular differences). Multivariate analysis revealed misclassifications between LTL and HTL at all week intervals. MCR-ALS components showed statistically significant abundances between control versus LTL and control versus HTL, but could not discern LTL and HTL. MCR-ALS components exhibited spectral mixtures of proteins, lipids, heme and nucleic acids. Thus, these findings support use of serum RS as a screening tool as varying tumour load is not a confounding factor influencing the technique.

MicroRNA-191, regulated by HIF-2α, is involved in EMT and acquisition of a stem cell-like phenotype in arsenite-transformed human liver epithelial cells.

Inorganic arsenic is widely distributed in the environment, and epidemiologic data show a strong association between arsenic exposure and risk of liver cancer. An understanding of the mechanisms underlying development of liver cancer and metastasis would be useful in reducing the incidence and mortality of liver cancer. MicroRNAs (miRs) act as regulators in liver cancer. Here, we show that acute or chronic exposure of human liver epithelial L-02 cells to arsenite increased expression of miR-191. There were decreased levels of BASP-1 and E-cadherin and increased levels of WT-1 and N-cadherin, indicating that arsenite induced epithelial-mesenchymal transition (EMT). Moreover, arsenite increased EpCAM and CD90 mRNA levels, showing the acquisition of stem cell-like properties by these cells. Suppression of miR-191 resulted in repression of EMT and reduced expression of stem-cell markers. Further, a miR-191 inhibitor blocked spheroid formation and production of side population cells. Luciferase reporter assays indicated that miR-191 was a target of HIF-2α, and inhibition of miR-191 decreased the neoplastic and metastatic properties of arsenite-transformed L-02 cells. Thus, in arsenite-transformed liver epithelial cells, transcriptional activation of the miR-191 promoter by HIF-2α is involved in EMT and in the acquisition of a stem cell-like phenotype.

Chemopreventive Effects of Azadirachta indica on Cancer Marker Indices and Ultrastructural Changes During 1,2-Dimethylhydrazine-Induced Colon Carcinogenesis in Rats.

The present study elucidated the prospective of Azadirachta indica supplementation, if any, in affording chemoprevention by modulating the altered cancer markers and ultrastructural changes in DMH-induced colorectal carcinogenesis in rats. The rats were segregated into four groups viz., normal control, DMH treated, A. indica treated, and DMH+AI treated. Initiation and induction of colon carcinogenesis were achieved through weekly subcutaneous injections of DMH (30 mg/kg body weight) for both 10 and 20 weeks. A. indica extract was supplemented to rats at a dose rate of 100 mg/kg body weight of animals thrice a week on alternative days, ad libitum for two different time durations of 10 and 20 weeks. The study observed a significant increase in the number of aberrant crypt foci in colons of DMH-treated rats at both the time intervals which were decreased significantly upon AI supplementation. Also, a significant increase was seen in the enzyme activity of alkaline phosphatase, which, however, was moderated upon AI administration to DMH-treated rats. Changes in the ultrastructural architecture of colonic cells were apparent following both the treatment schedules of DMH; however, the changes were prominent following 20 weeks of DMH treatment. The most obvious changes were seen in the form of altered nuclear shape and disruption of cellular integrity, which were appreciably improved upon AI supplementation. In conclusion, the study shows the chemopreventive abilities of AI against DMH-induced colorectal carcinogenesis in rats.

Angiogenesis in potentially malignant lesions and carcinomas during experimental oral carcinogenesis: a preliminary study in the hamster cheek pouch.

AIM: To evaluate vascular morphology and density, angiogenic switch activation, vascular endothelial growth factor (VEGF) expression, and endothelial cell (EC) proliferation in the hamster cheek pouch (HCP) model of oral cancer. MATERIALS AND METHODS: Immunohistochemical detection of factor VIII, 5'-Bromo-2'-Deoxyuridine (BrdU) and VEGF was performed in pre-malignant and tumoral tissues. RESULTS: Activation of angiogenesis was detected adjacent to epithelial dysplasia. Vascularized area and perimeter (p<0.001) increased in dysplasias and tumors. Tumor blood vessels exhibited an enhanced vascular compression (p<0.001) and structural alterations. EC proliferation was similar in dysplasias and carcinomas. An increase in vascular density, EC proliferation and VEGF expression was found in potentially malignant tissues but not in carcinomas. CONCLUSION: The angiogenic switch occurs in the dysplastic stage preceding tumor development in the HCP model of oral cancer. In potentially malignant tissues, increased VEGF expression favors EC proliferation and an increase in vascular density. Conversely, in tumors, VEGF is no longer of pivotal importance.

4NQO carcinogenesis: a model of oral squamous cell carcinoma / Carcinogenesis inducida por 4NQO: un modelo de carcinoma oral de células escamosas

The experimental oral carcinogenesis induced by the chemical 4-nitroquinoline 1-oxide (4NQO) is one of the most frequent in the study of squamous cell carcinoma of the oral cavity (CCEC). The clear advantage is that the model is very similar to the physiological process of malignancy. The model has clear benefits by and is suitable for applications in therapeutic research.

La carcinogénesis oral experimental inducida por el químico 4-nitroquinolina 1-óxido (4NQO) es uno de los métodos más frecuentes en el estudio del carcinoma de células escamosas de la cavidad oral (CCECO). La clara ventaja del modelo radica en el gran parecido al proceso fisiológico de la neoplasia maligna. El modelo tiene beneficios claros y es adecuado para las aplicaciones de la investigación terapéutica.

The effect of different doses of cigarette smoke in a mouse lung tumor model.

Few studies have used Balb/c mice as an animal model for lung carcinogenesis. In this study, we investigated the effect of different doses of cigarette smoking in the urethane-induced Balb/c mouse lung cancer model. After injection of 3mg/kg urethane intraperitoneally, the mice were then exposed to tobacco smoke once or twice a day, five times a week, in a closed chamber. The animals were randomly divided into four groups. The control group (G0) received urethane only. The experimental groups (G1, G2 and G3) received urethane and exposure to the smoke of 3 cigarettes for 10 minutes once a day, 3 cigarettes for 10 minutes twice a day, and 6 cigarettes for 10 minutes twice a day, respectively. The mice were sacrificed after 16 weeks of exposure, and the number of nodules and hyperplasia in the lungs was counted. The results showed no statistically significant difference in the mean number of nodules and hyperplasia among the different groups, suggesting that the Balb/c mice are not suitable to study the pathogenesis of tobacco smoking-induced tumor progression in the lungs.

Neoplastic Paneth cells in the experimental murine carcinoma of the small intestine

The purpose of this study is to elucidate the participation of Paneth cells in experimentally induced adenocarcinoma of the intestine. The rats were fed with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) dissolved in drinking water ad libitum at a concentration of 100 micrograms/ml for 28 weeks. They were sacrificed 12 weeks after the last MNNG administration. A number of tumor cells containing large eosinophilic granules in their supranuclear cytoplasm (Paneth cells) were observed in about 20% of the experimentally induced adenocarcinoma of the small intestine. The granules were stained positively with Lendrum, periodic acid-Schiff, Masson's trichrome, and Mallory's phosphotungstic acid hematoxylin. Ultrastructurally, the granules were round, osmiophilic, and relatively even in size. We compared the morphologic features of the Paneth cell-containing small intestinal adenocarcinomas (Group I) with those without Paneth cells (Group II). Group I was distinguished from Group II by its better differentiation, larger tumor size and lower incidence of calcification. Although Paneth cells are extremely rare in human gastrointestinal carcinomas, twenty percent of MNNG-induced intestinal carcinomas harbor Paneth cells. The neoplastic Paneth cells in experimental carcinomas may differentiate from uncommitted cells in the deeper portion of the crypt.