Secondary bile acids effects in colon pathology. Experimental mice study.

PURPOSE: To assess whether deoxycholic acid (DOC) and lithocholic acid (LCA) administered in a period of six months in a concentration of 0.25% may have a carcinogenic role in mice colon. METHODS: The study used C57BL6 female mice divided into four groups. The control group received a balanced diet and the others received diets supplemented with 0.25% DOC, 0.25% LCA and 0.125% DOC+0.125% LCA, respectively. After euthanasia, the lesions found in the resected gastrointestinal tracts were stained with hematoxylin-eosin and examined microscopically. RESULTS: No gastrointestinal tract changes were observed in the control group, while hyperplastic Peyer's patches in the small intestine, flat adenomas with mild dysplasia and chronic colitis at the level of the colon were found in all three test groups. The colonic lesions prevailed in the proximal colon. The highest number of flat adenoma lesions (8), hyperplasia of Peyer's patches (25) and chronic colitis (2) were found in mice fed with diet and LCA. CONCLUSION: Precancerous or cancerous pathological lesions could not be identified. Instead, adenomatous colonic injuries occurred in a shorter period of time (six months), compared to the reported data.

Secondary bile acids effects in colon pathology. Experimental mice study

ABSTRACTPURPOSE:To assess whether deoxycholic acid (DOC) and lithocholic acid (LCA) administered in a period of six months in a concentration of 0.25% may have a carcinogenic role in mice colon.METHODS:The study used C57BL6 female mice divided into four groups. The control group received a balanced diet and the others received diets supplemented with 0.25% DOC, 0.25% LCA and 0.125% DOC+0.125% LCA, respectively. After euthanasia, the lesions found in the resected gastrointestinal tracts were stained with hematoxylin-eosin and examined microscopically.RESULTS:No gastrointestinal tract changes were observed in the control group, while hyperplastic Peyer's patches in the small intestine, flat adenomas with mild dysplasia and chronic colitis at the level of the colon were found in all three test groups. The colonic lesions prevailed in the proximal colon. The highest number of flat adenoma lesions (8), hyperplasia of Peyer's patches (25) and chronic colitis (2) were found in mice fed with diet and LCA.CONCLUSION: Precancerous or cancerous pathological lesions could not be identified. Instead, adenomatous colonic injuries occurred in a shorter period of time (six months), compared to the reported data.

Secondary bile acids effects in colon pathology. Experimental mice study

To assess whether deoxycholic acid (DOC) and lithocholic acid (LCA) administered in a period of six months in a concentration of 0.25% may have a carcinogenic role in mice colon. The study used C57BL6 female mice divided into four groups. The control group received a balanced diet and the others received diets supplemented with 0.25% DOC, 0.25% LCA and 0.125% DOC+0.125% LCA, respectively. After euthanasia, the lesions found in the resected gastrointestinal tracts were stained with hematoxylin-eosin and examined microscopically. No gastrointestinal tract changes were observed in the control group, while hyperplastic Peyer's patches in the small intestine, flat adenomas with mild dysplasia and chronic colitis at the level of the colon were found in all three test groups. The colonic lesions prevailed in the proximal colon. The highest number of flat adenoma lesions (8), hyperplasia of Peyer's patches (25) and chronic colitis (2) were found in mice fed with diet and LCA. Precancerous or cancerous pathological lesions could not be identified. Instead, adenomatous colonic injuries occurred in a shorter period of time (six months), compared to the reported data.(AU)

Effects of selenium on Pteridium aquilinum and urethane-induced lung carcinogenesis.

The results of our previous study demonstrated that ptaquiloside, the main toxic agent found in Pteridium aquilinum, suppresses natural killer (NK) cell-mediated cytotoxicity. However, the ability of ptaquiloside to suppress the cytotoxicity of NK cells was prevented by selenium supplementation. NK cells play an important role in the innate immune response and have the ability to kill tumor cells. Therefore, we hypothesized that selenium may prevent the higher susceptibility to urethane-induced lung carcinogenesis that has been observed in mice treated with P. aquilinum. The immunosuppressive effects of ptaquiloside have been associated with a higher number of urethane-induced lung nodules in mice. Hence, we assessed the effects of P. aquilinum-induced immunosuppression on urethane-induced lung carcinogenesis in C57BL/6 mice that had been supplemented with selenium. For these experiments, mice were treated with both an aqueous extract of P. aquilinum (20 g/kg/day) and selenium (1.3 mg/kg) by gavage once daily for 14 days followed by a once-weekly intraperitoneal injection of urethane (1 g/kg) for 10 weeks that was accompanied by gavage 5 days a week. Lung adenomas in mice that had been treated with P. aquilinum plus urethane occurred with a frequency that was 44% higher than that in mice that had been treated with only urethane. In mice that had been supplemented with selenium and treated with P. aquilinum plus urethane, the occurrence of lung adenomas was reduced to 26%. These results suggest that selenium prevents the immunosuppressive effects of P. aquilinum on urethane-induced lung carcinogenesis.

Lung tumor development in the presence of sphingosine 1-phosphate agonist FTY720.

Urethane is a chemical carcinogen which causes lung tumorigenesis in mice with similarities to human adenocarcinoma (AC). The sphingosine 1-phosphate agonist FTY720 administered to mice in doses above 5 mg/kg/day has been able to prevent hepatocellular carcinoma and bladder cancer. We used BALB/c mice in urethane-induced lung cancer model to investigate the effects of a lower dose of FTY720 (1 mg/kg/day). The benefits of FTY720 were associated with the time point of the compound administration. FTY720 30 Group presented lower incidence and smaller area of lung nodules, decreased PCNA and increased Caspase-3 expressions. The findings in FTY720 0 Group (nodule multiplicity and area, PCNA expression) were similar to Urethane Group suggesting that the administration of the compound at early time point did not affect lung tumor development. FTY720 90 Group presented the biggest nodule area which was associated with increased PCNA and decreased Caspase-3 expressions. FTY720 (30 days and 90 days) administration decreased CD4 + splenocytes and blood lymphocytes which caused opposite effects in lung tumor development - impairment and improvement respectively.In conclusion, FTY720 in low dose did not provide lung tumor inhibition in mice but its administration 30 days after the chemical carcinogen (Urethane) injection was associated with impaired tumor development.

FTY720 and lung tumor development.

FTY720 has been shown to prevent cancer development in experimental models but there is no report whether this beneficial effect is associated with the time point of the drug administration. Lung adenoma was induced in mice by urethane injection followed by different periods of FTY720 administration in order to evaluate lung tumor development. BALB/c mice received urethane intraperitoneally in two doses of 1.5 g/kg and were submitted to five daily doses of FTY720 (1 mg/kg/day) starting just after urethane injection (G2 n=5), 4 weeks after urethane injection (G3 n=10), 8 weeks after urethane injection (G4 n=10) and no FTY720 administration (G1 n=5). Twenty-four weeks after urethane administration mice were evaluated for the number of leukocyte in blood, lymphocytes in spleen, and lungs were evaluated for changes in histology, PCNA and VEGF expression. Lung nodules were present in higher numbers both in non treated (G1; 0.0-7.0) and FTY720 treated 8 weeks after urethane injection (G4; 0.0-6.0). G4 Group also presented the highest number of papillary nodules. G1 and G4 groups presented the lower number of splenocytes and neutrophils. In early time FTY720 treated mice (G2) we observed a slight decrease in PCNA staining and also the lower percentage of VEGF intense staining. Therefore, our data suggest that the benefits of FTY720 treatment are time-dependent and when administered in early periods after lung tumor induction this drug could impair cancer development.

Altered expression of connexins in urethane-induced mouse lung adenomas.

Lung carcinogenesis is a multistep process whose molecular alterations can be studied in mouse models. Urethane, a specific lung tumor carcinogen, can induce adenomas in mice. Mouse lung alveolar cells reportedly generate lung neoplasms, and express connexins 26, 32, 43 and 46. The aim of the present study was to evaluate the expression of connexins in urethane-induced lung adenomas. Fifteen-day-old CD1 male mice received 2 i.p. injections of urethane (1.5 g/kg bw). The mice were euthanized 25 weeks after urethane injection, and lung adenomas were quantified. Lung tissue and lung adenomas were harvested and the RNA was extracted. The expression of connexins 26, 32, 43 and 46 was evaluated by Real-Time PCR, and these proteins were identified by Western blot. Immunohistochemistry revealed the distribution pattern of these connexins in lung tissue and adenomas. The treatment with urethane was associated with the downregulation of Cx26, 32 and 46 expressions, and with the upregulation of Cx43 expression in lung tissue. Surprisingly, in lung adenomas Cx32 and Cx43 expressions were not detected, although the expression of connexins 26 and 46 was present. Western blot and immunohistochemistry corroborated the RT-PCR data. These results may indicate a role of Cx32 and Cx43 in urethane-induced lung carcinogenesis, since their absence may contribute to the development of urethane induced lung tumors. The role of Cx26 and Cx46 is yet to be determined.

Inverse genetic predisposition to colon versus lung carcinogenesis in mouse lines selected based on acute inflammatory responsiveness.

Mouse lines produced by bidirectional selection on the basis of maximum (AIRmax) or minimum (AIRmin) acute inflammatory reactions were examined for the development of chemically induced acute colitis and colon tumors and the development of lung tumors. AIRmax mice were more susceptible than AIRmin to acute colitis induced by ingestion of dextran sodium sulfate showing a 3-fold higher disease activity index and presenting an intense inflammatory infiltrate in the base of colon crypts as well as elevated expression of IL-1beta, TNFalpha, IFNgamma and IL-6 mRNA in colon tissue. AIRmax were also more susceptible than AIRmin to colon cancer induced by 2 or 7 weekly doses of 1,2-dimethylhydrazine (DMH), showing significantly higher numbers of colonic aberrant crypt foci (ACF) at 150 days after DMH treatment (P = 0.01) and significantly higher numbers of tumors affecting larger intestinal areas at 300-475 days. At the latter time point, however, multiple lung adenomas and large adenocarcinomas were found in AIRmin but not in AIRmax mice. Treatment of mice with nimesulide for 60 days beginning 24 h before the first of two DMH doses almost completely inhibited the appearance of ACF in both lines. Furthermore, ACF numbers and the degree of acute inflammation directly co-segregated in an F2 (AIRmax x AIRmin) intercross population. The results demonstrate that genetic determinants of the inflammatory response differentially influence susceptibility to colon and lung carcinogenesis in the AIRmax and AIRmin mouse model.

Inhibitory effects of Pfaffia paniculata (Brazilian ginseng) on preneoplastic and neoplastic lesions in a mouse hepatocarcinogenesis model.

Studies have been demonstrating Pfaffia paniculata root (Brazilian ginseng) anticarcinogenic activities. We evaluated its chemopreventive effects on preneoplastic hepatic lesions. BALB/c aged-15 days received 10mug/g of diethylnitrosamine carcinogen, i.p. They were fed with the powdered root added to the diet: 0.5, 2 or 10% during 27 weeks. After being sacrificed, the macroscopic lesions in the livers were examined. Preneoplastic or neoplastic lesions were measured, quantified and classified morphologically. The treatment reduced the incidence, mean area and number of lesions, indicating an inhibitory effect of these roots on hepatocarcinogenesis promotion or progression steps.

Immunohistochemical analysis of heme oxygenase-1 in preneoplastic and neoplastic lesions during chemical hepatocarcinogenesis.

Heme oxygenase (HO) breaks down the pro-oxidant heme into carbon monoxide, iron and the antioxidant biliverdin. The isoform HO-1 plays an effective role to counteract oxidative damage and to control inflammation. Prolonged cellular damage due to chronic inflammation is one of the reasons leading to the development of tumours. The aim of this work was to investigate HO-1 expression and localization along the different stages of chemically induced hepatocarcinogenesis (HCC) and the occurring morphological changes. To provoke sustained oxidative stress and chronic inflammation, CF1 mice received dietary p-dimethylaminoazobenzene (DAB, 0.5%, w/w) during a whole period of 14 months. HO-1 expression increased along the experimental trial in morphologically normal hepatocytes in DAB-treated animals. HO-1 expression diminished in altered hepatic foci (AHF) and oval cells and early preneoplastic lesions. Otherwise, marked HO-1 overexpression was detected in Kupffer cells and macrophages surrounding necrotic and nodular areas. Adenomas showed decreased HO-1 immunostaining. In hepatocellular carcinomas, an inverse relationship was found between the immunohistochemical expression of HO-1 and the degree of tumour differentiation, being negative in poorly differentiated tumours. In our experimental model, down modulation of HO-1 expression correlated with malignancy progression. Thus, our data point to activation of HO-1 as a potential therapeutic tool.

Increased susceptibility to urethane-induced lung tumors in mice with decreased expression of connexin43.

Gap junction intercellular communication capacity and connexin expression are reportedly decreased in human lung cancer. The mechanisms by which connexins, the gap junction proteins, act as tumor suppressors are unclear. In order to understand the involvement of connexins in tumorigenesis, we analyzed the effect of the heterologous deletion of Gja1 [the connexin43 (Cx43) gene] on the development of lung adenomas in mice. Heterozygous (Cx43(+/-)) and wild-type mice (Cx43(+/+)) were treated or not with single doses of urethane at 15 and 17 days after birth. Twenty-five weeks later, both the number and size of nodules were increased in Cx43(+/-) mice as compared with Cx43(+/+) mice. Moreover, the lesions were histologically more aggressive in the heterozygous mice. However, no increase in spontaneous lesions was observed in the lungs of untreated Cx43(+/-) mice. Heterozygous mice effectively presented lower expression of Cx43 genes and decreased amounts of Cx43. In conclusion, our results indicate that deletion of one allele of the Cx43 gene clearly favors the carcinogenic effect of urethane administration and results in a higher susceptibility to lung adenoma formation in mice.

Urban levels of air pollution modifies the progression of urethane-induced lung tumours in mice.

This paper investigates the effects of air pollution in urethane-induced lung tumours in mice by means of histological, morphometrical, and DNA ploidy. The experimental exposure was done in locations with different air pollution profiles: a polluted area (downtown São Paulo) and a "clean" environment. Swiss mice were employed and urethane (3 g/kg) was used as a carcinogenic substance. All the animals, whether exposed or not to air pollution, were sacrificed after 6 months, and the lung lesions were analysed. The results showed a significant effect of air pollution on tumour progression, observed by changes in the phenotype of the tumour cells as demonstrated by morphometry and DNA ploidy. We observed more atypical adenomas in the air pollution-exposed group (p = 0.02). Coherently, morphometric differences were also detected between the two groups. Neoplasms of exposed mice exhibited an increase in the nuclear fraction (p = 0.002) and in the nucleus/cytoplasm ratio (p = 0.011), as a decrease in the stromal fraction (p < 0.001). There was a higher risk of aneuploidy in the 6-months-of-air-pollution-exposure group (relative risk: 1.58; 95% of confidence interval: 1.007 to 2.403). These results indicate that urban air pollution accelerates the process of progression towards malignancy.

Biochemical parameters in the anterior pituitary during the course of tumorigenesis induced by diethylstilbestrol treatment.

Treatment of F344 rats with diethylstilbestrol (DES) for 1-2 months induces a prolactin (PRL)-secreting pituitary adenoma. After 8 weeks of DES treatment, we have shown that the ratio of regulatory subunits of the cAMP-dependent protein kinase (RI/RII) increased in the tumors. Presently we report the variations in RI/RII ratio, pituitary weight, DNA content, serum PRL, nuclear estrogen receptor (E2R) and of ornithine decarboxylase (ODC) activity from the time of DES pellet implantation until 8 weeks. Pituitary weight, DNA content and serum PRL rose significantly at 4 weeks with a maximum at 6-8 weeks, and significantly correlated with each other. E2R and ODC activity increased from week 1 onwards, with a maximum at 2 weeks and decreased at 8 weeks. Both variables showed a positive correlation but neither E2R nor ODC activity correlated with pituitary weight, DNA or serum PRL. Values for RI remained stable with time, but RII decreased progressively. The RI/RII ratio was maintained around unity between 1-4 weeks, increasing to 1.6-2 thereafter. This ratio positively correlated with pituitary weight and DNA. It is suggested that during tumor induction by estrogen in a sensitive strain of rats, growth signals with different time-courses become activated. Increases in pituitary weight and DNA content, indicators of mammotroph hypertrophy and hyperplasia, were preceded by early rises in E2R and ODC activity. Increases in the RI/RII ratio accompanied the adenomatous change, suggesting their role in cell transformation after 6 weeks of estrogen exposure.

[Bleeding hepatic adenoma and its relation to oral contraceptives]. / Adenoma hepático sangrante y su relación con los anovulatorios.

PIP: The article discusses the case of a young patient with ruptured benign adenoma of the liver, possibly related to previous treatment with oral contraceptives. The patient, whose adenoma was bleeding into the peritoneal cavity, underwent right hepatectomy by the Lin technique. There were no complications. Complete resection is the only known adequate treatment for these benign tumors, and Lin's technique and surgical instruments have proven to be very helpful.^ieng

[Rupture of hepatic adenoma and oral contraceptives]. / Adenoma hepático roto y anticonceptivos por via bucal.

We present one case of hepatic adenoma in a patient with a long history of oral contraceptive administration. Review of the literature in similar cases points to the possibility of a cause effect relationship between this type of drugs and liver adenomas.

PIP: A patient with a 10-year history of oral contraception was surgically treated for a ruptured hepatic adenoma. The recent literature on the subject gives numerous instances of similar cases for which lobectomy seems to be the only definitive treatment.