Experimental esophageal carcinogenesis: technical standardization and results

Drinking for protection? Epidemiological and experimental evidence on the beneficial effects of coffee or major coffee compounds against gastrointestinal and liver carcinogenesis

Recent meta-analyses indicate that coffee consumption reduces the risk for digestive tract (oral, esophageal, gastric and colorectal) and, especially, liver cancer. Coffee bean-derived beverages, as the widely-consumed espresso and "common" filtered brews, present remarkable historical, cultural and economic importance globally. These drinks have rich and variable chemical composition, depending on factors that vary from "seeding to serving". The alkaloids caffeine and trigonelline, as well as the polyphenol chlorogenic acid, are some of the most important bioactive organic compounds of these beverages, displaying high levels in both espresso and common brews and/or increased bioavailability after consumption. Thus, we performed a comprehensive literature overview of current knowledge on the effects of coffee beverages and their highly bioavailable compounds, describing: 1) recent epidemiological and experimental findings highlighting the beneficial effects against gastrointestinal/liver carcinogenesis, and 2) the main molecular mechanisms in these in vitro and in vivo bioassays. Findings predominantly address the protective effects of coffee beverages and their most common/bioavailable compounds individually on gastrointestinal and liver cancer development. Caffeine, trigonelline and chlorogenic acid modulate common molecular targets directly implicated in key cancer hallmarks, what could stimulate novel translational or population-based mechanistic investigations.

Helicobacter pylori infection combined with DENA revealed altered expression of p53 and 14-3-3 isoforms in Gulo-/- mice

Unlike most other mammals, human bodies do not have the ability to synthesize vitamin C inside of their own bodies. Therefore, humans must obtain vitamin C through daily diet. Gulo(-/-) mice strain is known with deficiency, in which vitamin C intake can be controlled by diet like human, and would be valuable for investigating the molecular mechanism of various diseases. In the present study, we established Gulo(-/-) mice model and investigated the differentially expressed proteins in stomach tissue of Gulo(-)(/-) mice after Helicobacter pylori-infected, and followed by DENA, using immunohistochemistry and proteomic approach. The results of immunohistochemistry analysis of stomach tissue showed that the tumor suppressor, p53 protein, expression was significantly decreased (p<0.05) but not messenger RNA (mRNA) transcriptional level, and 14-3-3 ε, 14-3-3 δ, Ki-67 and cleaved caspase 3 expressions were significantly increased (p<0.05) by H. Pylori infection, and followed by DENA treatment in Gulo(-/-) mice. Moreover, knockdown of 14-3-3 isoforms (14-3-3 ε, 14-3-3 σ, 14-3-3 ζ and 14-3-3 η) were significantly increased sub-G1 phase (characteristics of apoptosis) in AGS cells and, phenotypic changes like cell shrinkage, density and cleaved nuclei were also observed. Proteome analyses showed that 14-3-3 σ, 14-3-3 η, and tropomyosin alpha-1 chain were down-regulated, and Hspd1 protein and HSC70 were up-regulated after H. Pylori-infection, and followed by DENA. The combined results of immunohistochemistry and proteomic analysis suggest that H. pylori altered the p53 and 14-3-3 isoforms expression and DENA further enhanced the H. pylori effect, which might be involved in carcinogenesis and metastasis of gastric cancer on Gulo(-/-) mice.

Role of the vitamin C in diethylnitrosamine-induced esophageal cancer in Wistar rats

PURPOSE: To evaluate the inhibitory effect of vitamin C on the experimental esophageal carcinogenesis induced by diethylnitrosamine (NDEA). METHODS: Sixty Wistar male rats aged three months, with mean weight of 210 g were employed in the study and were divided into four different groups according to the drinking drugs: group I - controls: only water, seven days a week; group II - only vitamin C, seven days a week; group III - NDEA, three days a week and water during the other four days; group IV - NDEA, three days a week and vitamin C during the other four days; group V - NDEA together with vitamin C three days a week, and only water during the other four days and group VI - NDEA together with vitamin C three days a week and vitamin C during the other four days. The dosages of NDEA were: - 10 mg. / Kg / day and vitamin C - 200 mg / animal / day, dissolved in drinking water. The animals were observed during 180 days and after that each one was sacrificed and its esophagus and the stomach were removed together and macro and microscopically analyzed to identify any tumors. RESULTS: The largest number of tumors was observed in the group III: 48 macroscopic lesions (4.8 lesions per animal) and 23 microscopic lesions (2.3 lesions per animal). The groups that received vitamin C (groups IV, V and VI) showed smaller number of tumors: group V - 0.5 macroscopic lesions and 0.3 microscopic lesions per animal and group VI - 0.1 macroscopic lesions and 0.1 microscopic lesions per animal. The incidence of tumors in the groups V and VI showed statistical significance (p<0.05), when compared to the other groups. CONCLUSION: The vitamin C administered together with diethylnitrosamine showed an inhibitory effect on the experimental esophageal carcinogenesis in Wistar rats.

Modelo experimental de carcinogênese esofágica

OBJETIVO: O carcinoma epidermóide do esôfago é neoplasia com alta taxa de mortalidade. A necessidade do entendimento do processo de carcinogênse na melhora de resultados desta doença, conduz aos estudos experimentais. MÉTODO: Induzida a carcinogênese esofágica quimicamente por meio da dietilnitrosamina(DEN), em um grupo de 100 camundongos fêmeas. Utilizados quatro grupos, onde os Grupos 1 e 2 foram considerados controles, sendo diferenciados por gavagem esofágica, uma vez semana, com água em temperatura ambiente (20-25ºC) ou quente (60º-70ºC). E os Grupos 3 e 4, considerados estudos, receberam DEN por três dias consecutivos semanalmente, também sendo diferenciados por gavagem quente ou fria. Progressivas eutanásias com coletas de peças esofágicas, com início no 30º dia do experimento e terminando no 150º dia. RESULTADOS: Demonstrou-se que não houve diferença na incidência tumoral quando foi acrescida a variável temperatura da água (p=0,6854). Observou-se, que a carcinogênese durante o experimento, considerados os grupos que receberam DEN como sendo um único grupo, demonstrou clara e evidente progressão de lesões neoplásicas. CONCLUSÃO: Houve progressão neoplásica esofágica com a utilização de DEN, bem como o método pode ser utilizado em estudos para investigação do processo mutagênico.

Carcinogens and endemic squamous cancer of the oesophagus in Transkei, South Africa. Environmental initiation is the dominant factor; tobacco or other carcinogens of low potency or concentration are sufficient for carcinogenesis in the predisposed mucosa

Oesophageal cancer is common in Africa, and is a major cause of death in Transkei, South Africa. The cause of this endemic disease has been debated for many decades. A continuing focus of research has been identification of a single potent carcinogen. I argue that endemic incidence of oesophageal cancer is associated with potent initiation, not with potent carcinogenesis. Tobacco is a known oesophageal carcinogen, and there is very strong evidence that it is causally involved in a significant proportion of victims. Other potential carcinogens present in the environment include fungal mycotoxins, human papillomavirus, Solanum nigrum and nitrosamines. These are all of lower carcinogenic potential for the oesophagus, and do not have strong evidence associating them with the disease. In the presence of potent environmental initiation, any oesophageal carcinogen even if of low potency or of low concentration may cause the disease. Any or all of the substances named above may be involved, any one of them the cause of the final carcinogenic change in the individual. Tobacco exemplifies this point. It is of relatively low concentration/usage in Transkei, yet has an undeniable association with oesophageal cancer. Carcinogenesis for the oesophagus in Transkei is solely or predominantly due to agents which are already known, including tobacco, acting on a predisposed mucosa. The search for further carcinogens is of low importance, and the search for a single potent carcinogen is misguided. What is of importance is the development of methods to reduce the risks associated with predisposing factors and with known carcinogens.