Efecto del aceite de Sacha Inchi (Plukenetia volubilis L.) en la carcinogénesis de colon inducida por 1,2–dimetilhidrazina en ratas Holtzman / Effect of Sacha Inchi oil (Plukenetia volubilis L.) on 1,2–dimethylhydrazine-induced colon carcinogenesis in Holtzman rats

Objetivos: Evaluar el efecto protector del aceite de Sacha Inchi (ASI) sobre el desarrollo de cáncer de colon (CC) inducido con 1,2–dimetilhidrazina (DMH) en ratas Holtzman. Materiales y métodos: Estudio experimental con 28 ratas albinas machos de la cepa Holtzman distribuidas al azar en 4 grupos: un grupo control positivo expuesto a DMH (C1), un grupo control negativo expuesto a ASI a 150 μL/kg/día (C2), y dos grupos experimentales expuestos a DMH con ASI a 150 μL/kg/día (E1) y ASI a 300 μL/kg/día (E2). La DMH se aplicó por 8 semanas y con un tiempo total de inducción de 22 semanas. Luego se realizó el análisis patológico mediante la identificación de lesiones tumorales cancerosas en los intestinos. El efecto protector se evaluó en base a las proporciones de ausencia de lesión en los grupos expuestos a DMH. Resultados: Se identificaron lesiones tumorales cancerosas en: dos especímenes del grupo C1, un espécimen del grupo E1 y dos especímenes del grupo E2. No se identificaron lesiones intestinales en el grupo C2. Las proporciones de ausencia de lesión fueron: en el grupo C1 de 75%, en el grupo E1 de 87,5% y en el grupo E2 de 75%. No se encontraron diferencias significativas (p>0,05). Conclusiones: No se evidenció un efecto protector significativo del ASI sobre el desarrollo de CC inducido con DMH en ratas Holtzman, respecto al grupo control.

Objectives: To evaluate the preventive effect of Sacha Inchi oil (SIO) on 1,2–dimethylhydrazine (DMH)-induced colon carcinogenesis (CC) in Holtzman rats. Materials and methods: Experimental study with 28 Holtzman male albino rats randomly distributed into 4 groups: a positive control group exposed to DMH (C1), a negative control group exposed to SIO at 150 uL/kg/ day (C2), and two experimental groups exposed to DMH with SIO at 150 uL/kg/day (E1) and SIO at 300 uL/kg/day (E2). The DMH was applied for 8 weeks and the total induction time was 22 weeks. Pathological examination was performed by identifying cancerous tumor lesions in the guts. The preventive effect was evaluated based on proportions of lack of lesion in the groups exposed to DMH. Results: Cancerous tumor lesions were identified in: two specimens of group C1, one specimen of group E1 and two specimens of group E2. No intestinal lesions were identified in group C2. The proportions of lack of lesion were: in group C1 of 75%, in group E1 of 87.5% and group E2 of 75%. No significant differences were found (p>0.05). Conclusions: It was not found a significant protective effect of SIO on DMH-induced CC in Holtzman rats, compared to control group.

Efecto quimioprotector del extracto alcaloideo de Melocactus bellavistensis (cactus globoso) sobre el cáncer de colon inducido con 1,2-dimetilhidrazina en ratas / Chemoprotective effect of the alkaloid extract of Melocactus bellavistensis against colon cancer induced in rats using 1,2-dimethylhydrazine

RESUMEN Objetivos Determinar la toxicidad y el efecto quimioprotector del extracto alcaloideo de Melocactus bellavistensis (cactus globoso) sobre el cáncer de colon inducido en ratas con 1,2 dimetilhidrazina (DMH). Materiales y métodos Se obtuvo el extracto alcaloideo de la parte carnosa de Melocactus bellavistensis, posteriormente, se realizó un ensayo de toxicidad aguda en 30 ratones de cepas Balb C57. Para evaluar su efecto quimioprotector se indujo el cáncer de colon en 45 ratas Holtzmann con DMH, según el siguiente diseño experimental: un grupo control con: polisorbato de sodio (PS) a 2 mL/kg y cuatro grupos con DMH 20 mg/kg más 0, 1, 5 y 10 mg/kg de extracto alcaloideo de Melocactus bellavistensis respectivamente. Resultados Con una muestra de 5 g de extracto alcaloideo se determinó una DL50 mayor a 1000 mg/mL en el ensayo de toxicidad aguda del extracto alcaloideo de Melocactus bellavistensis. Los resultados del efecto quimioprotector en los indicadores de estudio histopatológico revelaron que a las dosis de 5 y 10 mg/kg demostraron actividad antitumoral significativa en el cáncer de colon inducido por dimetilhidrazina en ratas con 100% de inhibición de neoplasia. Conclusiones En condiciones experimentales, el extracto de alcaloides de Melocactus bellavistensis demostró tener efecto quimioprotector en cáncer de colon inducido por dimetilhidrazina en ratas.

ABSTRACT Objectives To determine the toxicity and chemoprotective effect of the alkaloid extract of Melocactus bellavistensis against colon cancer induced in rats using 1,2-dimethylhydrazine (DMH). Materials and methods The alkaloid extract was obtained from the fleshy part of M. bellavistensis, and an acute toxicity test was then carried out on 30 mice of the Balb C57 strain. To assess its chemoprotective effect, colon cancer was induced in 45 Holtzman rats using DMH according to the following experimental design: one control group received 2 mL/kg sodium polysorbate, and four groups received 20 mg/kg DMH plus 0, 1, 5, or 10 mg/kg M. bellavistensis alkaloid extract. Results With a sample of 5 g of alkaloid extract, an LD50 greater than 1000 mg/mL was determined in the acute toxicity test. Histological indicators revealed that the 5 and 10 mg/kg doses had significant anti-tumor activity with 100% neoplasia inhibition against DMH- induced colon cancer in rats. Conclusions Under experimental conditions, the alkaloid extract of M. bellavistensis has a chemoprotective effect against DMH-induced colon cancer in rats.

A review of experimental models in colorectal carcinogenesis / Modelos experimentais de carcinogênese colorretal

Colorectal cancer is the leading cause of malignancy of the gastrointestinal tract. A better understanding of the molecular and cellular changes that lead to the disease is necessary to develop early diagnosis and optimal treatment modalities. Rodent models are rapid, reproducible and exhibit an adenoma-carcinoma sequence similar to that found in humans. The objective of this manuscript is to review the most common chemical carcinogens used to induce experimental tumors and the usual methods of evaluation.

O câncer colorretal é a principal neoplasia maligna do trato gastrointestinal. Um melhor entendimento dos processos moleculares e celulares é necessário para o desenvolvimento de estratégias que permitam um diagnóstico precoce e um tratamento mais eficaz. Modelos que utilizam roedores são rápidos, reprodutíveis e permitem o estudo da sequencia adenoma-carcinoma de forma similar a encontrada em humanos. O objetivo desse manuscrito é revisar os principais modelos de carcinogênese química e os métodos mais usuais para avaliação dos resultados.

Comparative study of 1, 2-dimethylhydrazine and azoxymethane on the induction of colorectal cancer in rats / Estudo comparativo das substâncias 1, 2-dimetil-hidrazina e azoximetano na indução de câncer colorretal em ratos

The induced colorectal carcinogenesis in rodents has a long history and currently uses the substances 1,2-dimethylhydrazine and azoxymethane. Objective: The aim of this study was to compare the inductive effect of the substances azoxymethane and 1,2-dimethylhydrazine in colorectal carcinogenesis. Method: 30 randomly chosen male Wistar rats were divided into four groups. G1 group was treated with 1,2-dimethylhydrazine and C1 was its control group; G2 group was treated azoxymethane and C2 was its control group. The animals were weekly weighed until euthanasia, when their intestines were removed, processed and analyzed by an experienced pathologist. Results: Among the control groups (C1 and C2) no histologic changes were observed; moderate dysplasia was detected in G2 group; hyperplasia, mild dysplasia, severe dysplasia and carcinoma were observed in G1 group. When this study compared the cost of the substances, 1,2-dimethylhydrazine was more than 50 times less expensive than azoxymethane. Conclusion: Azoxymethane is able to promote histological changes consistent with colorectal carcinogenesis. 1,2-Dimethylhydrazine produced neoplasia and dysplasia, and, compared to the azoxymethane, was more efficient in the induction of colorectal cancer. (AU)

A carcinogênese colorretal induzida em roedores tem longa história e utiliza, atualmente, as substâncias 1,2 dimetil-hidrazina (DMH) e azoximetano (AOM). Objetivo: Comparar o efeito indutivo das substâncias AOM e DMH para o câncer colorretal (CCR). Método: 30 ratos Wistar machos foram randomizados em quatro grupos. O grupo G1 foi inoculado com DMH, o grupo C1 foi seu controle; G2 recebeu o AOM e C2 foi seu controle. Os animais foram pesados semanalmente até a eutanásia, quando tiveram seus intestinos retirados, processados e analisados por um patologista experiente. Resultados: Os animais dos grupos de controle apresentaram tecido colorretal normal e os animais do grupo G2 apresentaram um padrão de displasia moderada. Nas lâminas do grupo G1, foram encontradas regiões de hiperplasia, displasia leve, displasia grave, e carcinoma. Comparado o custo das substâncias AOM e DMH, este último teve um preço mais de 50 vezes menor ao do AOM. Conclusão: AOM é capaz de promover alterações histológicas compatíveis com a carcinogênese colorretal. DMH produziu neoplasia e displasia grave e, comparada ao AOM, foi mais eficiente na indução do câncer colorretal. (AU)

Sequential Changes in Aberrant Crypt Foci and Lectin Expression in the Early and Late Stages of DMH-Induced Colon Carcinogenesis in Rats

BACKGROUND/AIMS: The purpose of this study was to investigate the malignant potential of aberrant crypt foci (ACF) by measuring the multiplicity of crypts and lectin expression in the early and late stages of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. METHODS: Six-week-old Wistar rats were injected subcutaneously with DMH for 27 weeks. We classified ACF according to the number of crypts per ACF as a few crypts ( or =4 crypts, NC ACF). Immunohistochemistry was used to evaluate lectin expression. RESULTS: In the early stage, FC ACF (590/1,902, 31.0%) occurred more frequently than NC ACF (35/449, 7.8%); whereas in the late stage, NC ACF (176/449, 39.2%) occurred more frequently than FC ACF (324/1,902, 17.0%). The number of ACF peaked at 15 to 20 weeks. The ratio of NC/FC ACF increased gradually during carcinogenesis. The expression of both UEA1 and PNA was higher in NC ACF than FC ACF. Lectin expression increased in the late stage compared with the early stage. CONCLUSIONS: The expression of lectin was higher in NC ACF and ACF in the late stage. Therefore, ACF with higher multiplicities in the late stage may have more malignant potential in DMH-induced colon carcinogenesis.

Pathogenic and tumorigenic effect of 1,2-dimethylhydrazine in mouse colon and ovarian / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the pathogenic and tumorigenic effect of 1,2-dimethylhydrazine (DMH) on the colon and ovaries of mice.</p><p><b>METHODS</b>Sixty ICR female mice were randomly divided into groups A and B for intraperitoneal injection of DMH (20 mg/kg) and saline (control) once a week for 24 weeks, respectively. The mice were sacrificed at 12, 16, 20, 24, 28 and 32 weeks after the first DMH injection for pathological examination of the colon and ovaries.</p><p><b>RESULTS</b>In group A, colorectal adenomas were found in 7, colorectal adenocarcinomas in 5, and hemorrhagic lesions of the ovaries with chronic inflammatory in 21 mice. Choriocarcinoma in the ovaries were detected in one mouse at 28 weeks and in another at 32 weeks. No obvious pathological changes were found in group B following the injections.</p><p><b>CONCLUSION</b>Intraperitoneal injection of DMH may induce colon tumors and ovarian diseases in mice.</p>

Preventive effects of berberine on experimental colon cancer and relationship with cyclooxygenase-2 expression / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the anti-colon cancer effects of berberine and possible relationship with cyclooxygenase-2.</p><p><b>METHOD</b>Wistar rat colon cancer model was induced by 1-2 dimethylhydrazine (DMH) (40 mg x kg(-1), sc) + 1% dextran sodium sulfate solution (DSS) (freely drinking). All rats were randomly divided into 3 groups: Control (DMH + DSS + solvant), meloxicam (Mel) (DMH + DSS + Mel 1.35 mg x kg(-1)), berberine (Ber) (DMH + DSS + Ber 100 mg x kg(-1)). The drugs were given orally once a day for 5 day per week. The body weight, the number of colon ACFs, the incidence and number of colon cancer in rats, as well as the morphological changes of rat colon tissues were evaluated. Human colon cancer lovo cell line was treated by either Ber or Mel in various concentrations (1 10(-6) mol x L(-1), 1 x 10(-5) mol x L(-1), 1 x 10(-4) mol x L(-1), 1 x 10(-3) mol x L(-1)) for 6, 12 and 24 h, respectively, and the cell growth was assayed by MTT method. RT-PCR and western-blot were used to evaluate the mRNA and protein expressions of COX-2 from lovo cells treated with Ber and Mel.</p><p><b>RESULT</b>Ber significantly improved the dyscrasia induced by DMH + DSS, the both of body weight and general condition were better than control group. Ber also significantly inhibited ACF and colon cancer incidence in the rats treated by DMH + DSS for 10 weeks or 20 weeks, which was similar to that of Mel. Ber inhibited the proliferation of lovo cells in concentration- and time-dependent manners, and the IC50 values were significantly smaller than that of Mel at 6, 12 and 24 h after lovo cells were treated by either Ber or Mel. Ber also concentration-dependently decreased expressions of COX-2 mRNA and COX-2 protein from lovo cells.</p><p><b>CONCLUSION</b>Ber can inhibit ACF and tumor formation induced by DMH + DSS, and decrease the lovo cell proliferation index. The anti-tumor effects of Ber may involve in an unknown pathway through which the expressions of COX-2 mRNA and protein were inhibited.</p>

Pituitary toxicity but lack of rat colon carcinogenicity of a DC-magnetic field in a medium-term bioassay.

The present study was designated to evaluate the effect of direct current induced permanent magnetic field (DC-MF) on chemically induced rat colon carcinogenesis. Five experimental groups of male S.D. rats were injected with 1,2-dimethylhydrazine (DMH) subcutaneously, 20 mg/kg b.wt., once a week for four weeks, with exposure to 1 mT DC-MF (12 hours/day) as follows: Before (pre) the carcinogen administration (group 1), simultaneously (group 2), after (post) the carcinogen administration (group 3) and daily from the beginning to the end of the experiment after 12 weeks (group 4). Rats of group 5 served as carcinogen-only treated controls while those of group 6 were non-treated controls. There were no differences in the incidences and multiplicities of colonic aberrant crypt foci (ACF), putative preneoplastic lesions, among all groups except that large foci in group 1 were significantly fewer in numbers than those found in group 5. Proliferating cell nuclear antigen labeling indexes (PCNA-LI) in the colon epithelium were essentially the same in MF-treated and control rats. Histopathological examination showed evident hemorrhage in the pituitary glands of some rats of groups 1-3, and in most rats of group 4. Transmission electron microscopy also revealed ultrastructural changes, but DNA ploidy analysis revealed no carcinogenicity to MF-exposed pituitary glands. Serum levels of AST, ALT, total protein, creatinine, albumin, albumin/globulin ratio and growth hormone levels did not change among the groups. The present study revealed that the action of an artificial MF on rats is not carcinogenic/or cancer-promoting, at least in the present protocol for colon carcinogenesis.

Effect of 2-(carboxyphenyl) retinamide and genistein on the formation of early lesions in 1,2-dimethylhydrazine-induced colon carcinogenesis in rats.

Aberrant crypt foci (ACF) are recognized as preneoplastic lesions for colon cancer, and ACF in rodents are widely used as an intermediate biomarker to predict tumorigenicity in the colon. However, a lack of correlations between the formation of ACF and the development of colonic tumors has been reported in several studies. For example, 2-(carboxyphenyl) retinamide (2-CPR) and genistein were reported to inhibit the carcinogen-induced formation of ACF, whereas both of them were later found to enhance colon tumorigenesis in rats treated with azoxymethane (AOM). Recently, we have identified b-catenin-accumulated crypts (BCAC) in the colon of rats shortly after administration of AOM, and provided evidence that these are independent early lesions of classical ACF, and BCAC might be direct precursors for colon cancers. In the present study, we performed a comparative analysis of the modifying effects of 2-CPR and genistein on 1,2-dimethylhydrazine (DMH)-induced BCAC and ACF in male F344 rats. Dietary administration of 2-CPR (315 ppm) significantly reduced the total number, multiplicity and size of ACF in DMH-exposed colonic mucosa, while genistein (250 ppm) had no significant effects on DMH-induced ACF formation. In contrast, both of 2-CPR and genistein significantly enhanced the multiplicity and size of DMH-induced BCAC when compared with DMH alone group. In addition, both 2-CPR and genistein significantly increased the proliferating cell nuclear antigen (PCNA) index preferentially in BCAC. Together with previous findings that 2-CPR and genistein are tumor promoters in the colon, our results support the concept that BCAC are precursors of colon tumors and suggest that these lesions are more reliable short-term biomarkers for colon carcinogenesis in rodents than ACF.

Role of Protein Kinase C in Abnormal Proliferation of Vascular Endothelial Cell induced by 1,2-Dimethylhydrazine; Analysis of Isoform

PURPOSE: Protein tyrosine kinase(PTK), protein kinase C(PKC), oxidase, as a mediator, have been known to take a role in signal transduction pathway of angiogenesis. The authors confirmed that PKC is the most noticeable mediator for abnormal proliferation of vascular endothelial cells through in vitro study model using the inhibitors, targeting the formation of three co-enzymes. In this study, we would investigate which isoform of PKC play an important role in abnormal angiogenesis of vascular endothelial cell. METHODS: In 96 well plates, 10(4) HUVECs(human umbilical vein endothelial cells) were evenly distributed. Two groups were established; the control group without administration of DMH(1,2-dimethylhydrazine) and the DMH group with administration of 7.5x10(-9)M DMH. RNA was extracted from vascular endothelial cell of each group and expression of the PKC isoform was analyzed by RT-PCR(reverse transcriptase-polymerase chain reaction) method. RESULTS: RT-PCR analysis showed that PKCalpha, -betaI, -betaII, -eta, -micron and -zeta were expressed in vascular endothelial cells of each group. DMH incresed the expression of PKCalpha and PKCmicron, and decreased PKCbetaI, PKCbetaII expression dominantly. CONCLUSION: Based on the result of this study, it was suggested that PKCalpha and PKCmicron may have significant role in abnormal proliferation of vascular endothelial cell.

Inhibitory effects of crude alpha-mangostin, a xanthone derivative, on two different categories of colon preneoplastic lesions induced by 1, 2-dimethylhydrazine in the rat.

The purpose of this study was to examine whether crude alpha-mangostin (a major xanthone derivative in mangosteen pericarp (Garcinia mangostana)) has short-term chemopreventive effects on putative preneoplastic lesions involved in rat colon carcinogenesis. The crude preparation was obtained by simple recrystallization of an ethylacetate extract of mangosteen pericarps. A total of 33 five-week-old male F344 rats were randomly divided into 5 experimental groups. Rats in groups 1-3 were given a subcutaneous injection of 1,2-dimethylhydrazine (DMH)(40 mg/kg body weight) once a week for 2 weeks. Starting one week before the first injection of DMH, rats in groups 2 and 3 were fed a diet containing 0.02% and 0.05% crude alpha-mangostin, respectively, for 5 weeks. Rats in group 4 also received the diet containing 0.05% crude alpha-mangostin, while rats in group 5 served as untreated controls. The experiment was terminated 5 weeks after the start. Dietary administration of crude alpha-mangostin at both doses significantly inhibited the induction and/or development of aberrant crypt foci (ACF) (P<0.05 for 0.02% crude alpha-mangostin, P<0.01 for 0.05% crude alpha-mangostin), when compared to the DMH-treated group (group 1). Moreover, treatment of rats with 0.05% crude alpha-mangostin significantly decreased dysplastic foci (DF) (P<0.05) and beta-catenin accumulated crypts (BCAC) (P<0.05), to below the group 1 values. The proliferating cell nuclear antigen (PCNA) labeling indices of colon epithelium and focal lesions in groups 2 and 3 were also significantly lower than in group 1 and this effect occurred in a dose dependent manner of the crude alpha-mangostin. This finding that crude alpha-mangostin has potent chemopreventive effects in our short-term colon carcinogenesis bioassay system suggests that longer exposure might result in suppression of tumor development.

Effect of Dietary Conjugated Linoleic Acid (CLA) Isomers on Tumor Incidence and the Protein Expression of Cyclooxygenase-2 and Protein Kinase C in Colonic Mucosa of DMH-Treated Rats

This study was designed to compare the anti-carcinogenic effect of conjugated linoleic acid isomers on tumor incidence, cell proliferation and the levels of thromboxane (TX)B2, prostaglandin (PG)E2 and 1,2-diacylglycerol (DAG), and the related enzyme expression of cyclooxygenase (COX)-2 and protein kinase C (PKC) in colonic mucosa of 1,2-dimethylhydrazine (DMH)-treated rats. One hundred eight male Sprague Dawley rats were randomly divided into 3 groups depending on the types of CLA isomers, i.e. control group (no CLA contained), c9t11 group (cis-9, trans-11 CLA contained), and t10c12 group (trans-10, cis-12 CLA contained). The experimental diet was composed of protein at 20%, carbohydrate at 56.2%, and fat at 14.5% including 1.0% CLA isomers by weight. The experimental diet was fed for 30 weeks with the initiation of intramuscular injection of DMH, which was injected twice a week for 6 weeks to give total dose of 180 mg per kg body weight. Two CLA isomers (c9, t11; t10, c12) significantly reduced tumor incidence and cell proliferation by reducing the protein expression of COX-2 and PKC, and the level of TXB2, PGE2, and DAG in colonic mucosa. However, there was no significant difference in anti-carcinogenic effect between c9t11-CLA and t10c12-CLA.

Effect of Dietary CLA Isomers on Apoptosis and Cell Proliferation in Colonic Mucosa of DMH-Treated Rats

The study was designed to compare the anti-carcinogenic effect of conjugated linoleic acid (CLA) isomers on colon carcinogenesis in 1,2-dimethylhydrazine (DMH)-treated rats by determining the levels of apoptosis, cell proliferation, eicosanoids and 1,2-diacylglycerol (DAG) in colonic mucosa. Sixty male Sprague Dawley rats were randomly divided into 3 groups depending on the types of CLA isomers, i.e. BT group (no CLA contained), CLA-C group (cis-9, trans11 isomer contained), and CLA- T group (trans-10, cis-12 isomer contained). The experimental diet was composed of protein at 20%, carbohydrate at 56.2%, and fat at 14.5% including 0.8% CLA isomers by weight. The experimental diet was fed for 14 weeks with the initiation of intramuscular injection of DMH, which was injected twice a week for 6 weeks to give total dose of l80mg per kg body weight. Two CLA isomers (c9t11 and t10c12) significantly increased the relative percentage of apoptosis but reduced cell proliferation in mucosal cell and also the levels of PGE2, TXB2, and DAG in colonic mucosa. However, there was no significant differences in anti-carcinogenic effect between c9t11 isomer and t10c12 isomer. Overall, colon carcinogenesis could be significantly inhibited by CLA isomers by increasing apoptosis and reducing cell proliferation, the levels of eicosanoids and DAG in colonic mucosa.

Inhibition by Ginseng of Colon Carcinogenesis in Rats

The inhibitory effects of ginseng on the development of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in the colon were investigated in rats. Male, 6-week-old rats were injected with DMH once a week for 4 weeks. Rats in Groups 1 and 2 were fed diets containing red and white ginseng, rerspectively, at a dose of 1% for 5 weeks, starting one week before the first treatment of DMH. Animals in Groups 3 and 4 received red or white ginseng for 8 weeks starting after DMH treatment. Group 5 served as a carcinogen control group. Numbers of ACF with at least four crypts were significantly reduced in the colon of Group 2 treated with red ginseng combined with DMH. Moreover, rats were injected with DMH 4 times at one-week intervals. They were also fed diets containing 1% red or white ginseng or the control diet throughout 30 days of the experiment. Treatment with red ginseng resulted in a significant decrease of 5- bromo-2'-deoxyuridine labeling indices in colonic crypts comprising ACF. These findings suggest that dietary administration of red ginseng in combination with DMH suppresses colon carcinogenesis in rats, and the inhibition may be associated, in part, with inhibition of cell proliferation, acting on ACF in the colonic mucosa.

Wound healing and colon carcinogenesis: enhancing effects of skin wounding on development of colon tumors induced by 1, 2 Dimethylhydrazine in the rat

This study demonstrates the tumor promoting effect at a distant site of skin wounding, in a model of colon carcinogenesis induced by 1,2 dimethylhydrazine (DMH) in the rat. Six-week-old male Wistar rats were given subcutaneous injections of DMH, 20mg/kg, or saline, once a week, for eight weeks. One week after the last DMH injection the animals received a full thickness skin wound in their dorsal skin and the wound was left open to heal by second intention. Control and DMH-treated rats, with or without skin wounds were killed at the 12th week, just after healing of the skin wound was complete. The colons were removed and divided into proximal and distal parts. Each segment was rolled as "Swiss roll"and processed for histology. The incidence, distribution and morphology of the colon tumors was recorded. The total number of tumors in the colonic mucosa and the number of tumors per rat was significantly higher in the skin-wounding DMH- treated group than in the unwounded group. In the histopathological analysis of the colon the number of poorly differentiated mucin-secreting carcinomas was 6-fold in the skin-wounding DMH-treated group than in the unwounded group and the majority of tumors were located near to lymphoid aggregates. The present results suggest that wound healing enhances tumor development at a distant site, such as the colon, and this effect seems to be related to tumor histology.

Overexpression of cyclin D1 and cyclin E in 1,2-dimethylhydrazine dihydrochloride-induced rat colon carcinogenesis

Deregulation of G1 cyclins has been reported in several human and rodent tumors including colon cancer. To investigate the expression pattern of G1 cyclins in 1,2- dimethyl-hydrazine dihydrochloride (DMH)-induced rat colon carcinogenesis, we studied the expression of cyclin D1 and cyclin E by quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis and immunohistochemistry (IHC). The mRNA level of cyclin D1 was increased 1.2-fold in adenocarcinomas but not significantly in adenomas, when compared with normal rat colonic mucosa (p<0.05). The cyclin E mRNA level was increased 2.7-fold in adenomas and 3.3-fold in adenocarcinomas (p<0.05). The PCNA mRNA level was also increased 1.9-fold in adenomas and 1.8-fold in adenocarcinomas (p<0.05). Immunohistochemical staining revealed exclusive nuclear staining of the neoplastic cells for cyclin D1, cyclin E and PCNA. Cyclin D1 expression was detected in 56.3% of the adenomas and in 61.5% of the adenocarcinomas examined, whereas cyclin E expression was detected in 87.5% of the adenomas and in 92.3% of the adenocarcinomas. Overall, cyclin D1, cyclin E and PCNA expression was significantly increased at both the mRNA and protein levels in normal colonic mucosa, adenomas and adenocarcinomas, but there was no significant difference in the degree of expression of these genes in adenomas and adenocarcinomas. Our results indicate that the overexpression of cyclin D1 and cyclin E may play an important role during the multistage process of rat colon carcinogenesis, at a relatively early stage, and may disturb cell-cycle control in benign adenomas, and thereafter, participate in tumor progression.

Localizaçäo de lesöes tumorais induzidas pela 1, 2-demetilhidrazina e seu grau de atipia no colon de ratos / Location and malignancy of tumoral lesions induced by 1, 2-dimethylhydrazine in the colon of rats

As diversas técnicas para o tratamento cirúrgico da Síndrome do Intestino Curto apresentam, ainda hoje, problemas de dificil resolução. De todas, as mais promissoras são o transplante de intestino delgado e o transplante de colo. Uma técnica intermediária que mostrou resultados controversos tanto clínicos como experimentais, é a interposição de segmentos de colo no trajeto do intestino delgado após extensas ressecções. Sua aplicação serve, todavia, como um meio de se estudar a adaptação do colo, inclusive visando os transplantes. Neste trabalho foi estudada a indução de tumores pela 1,2-dimetilhidrazina, sua localização e grau de atípia nos diferentes segmentos intestinais após ressecção de 80 por cento do jejuno-íleo. Foram encontradas 24 lesões ao exame macroscópico após a décima sexta se-mana de pós-operatório. O número de lesões por animal variou de 0 a 9. Das 24 lesões en-contradas, 20 estavam no colo (83,33 por cento), sendo que 11 estavam localizadas no cólon proximal, 3 no cólon distal e 6 anorretais. No estudo histológico, a maioria das lesões era de grau III. Este trabalho mostrou que o método de indução de tumores pela 1,2-dimetilhidrazina é apropriado para o estudo de tumores intestinais em ratos.

Estudio histológico e histoquímico de lesiones hiperplásicas y displásicas del intestino grueso en Cebus Apella (primate) tratado con 1, 2-dimetilhidrazida / Histological and histochemical study of hyperplastic and dysplastic lesions of the large intestine in Cebus Apella (primate) treated with 1, 2-dimethylhydrazine

El principal objetivo del presente trabajo consistió en determinar los cambios histológicos en el epitelio del colon en primates de la especie Cebus apella inducidos mediante la administración de la 1,2-dimetilhidrazina (DMH). Fueron utilizados 12 primates, machos de 30 meses de edad y con un peso promedio de 2,800Kg. La DMH fue administrada por vía subcutánea a razón de 25 mg/Kg de peso corporal semanalmente, durante 16 semanas. Durante los 20 meses que duró la experiencia el peso corporal fue evaluado semanalmente en los primeros 4 meses y cada 30 días hasta el final del experimento. Al final de la experiencia, en cortes histológicos de 5 mum, coloreados con Hematoxilina-Eosina, fueron evaluados los cambios histológicos del epitelio intestinal, así como las mucosustancias, utilizándose las técnicas del PAS y Alcian blue e pH 2,5. El estudio histológico e histoquímico permitió caracterizar la morfología normal, así como las características de las mucosustancias en tres regiones: ciego, colon transverso y colon distal. Los cambios histológicos observados en los animales tratados con DMH consistieron en fenómenos de hiperplasia, displasia y disminución de las mucosustancias. Los cambios hiperplásicos comprometieron a las criptas glandulares y al epitelio superficial que reviste a los nódulos linfoides. Focos de displasia fueron observados en el colon transverso y última porción del colon distal y comprometieron a criptas localizadas tanto en profundidad como en criptas de la mucosa superficial. Se observaron criptas con disminución de mucosustancias neutras y ácidas. Nuestros resultados sugieren que la DMH indujo en el colon, focos displásicos y lesiones hiperplásicas en criptas y en el epitelio que reviste a los nódulos linfoides, así como disminución de las mucosustancias neutras y ácidas.

Role of redchilli (Capsaicin) in the formation of colonic carcinoma.

The effect of feeding redchilli (Capsaicin) powder on the histopathological changes occurring in the colonic mucosa was studied in rats. These animals were compared with those treated with a colonic carcinogen 1,2-dimethylhydrazine (DMH). Animals fed with redchilli, dimethylhydrazine, dimethylhydrazine plus redchilli powder showed polyp and dysplasia, malignant tumour and malignant tumour with transitional area of dysplasia.

Elevation in diacylglycerol level and activation of protein kinase C in liver of mice administered with carcinogenic dose of 1,2-dimethylhydrazine.

Five weeks treatment of male mice with 1,2-dimethylhydrazine leads to elevation in the level of diacylglycerol in liver. Increase in diacylglycerol content is accompanied by an increase in particulate activity of protein kinase C with a fall in its activity in cytosolic fraction. Quantitative analysis of neutral lipids of different subcellular fractions from liver reveals that diacylglycerol levels increases highly significantly in liver microsomal membranes of carcinogen treated mice. Separation of neutral lipids by thin layer chromatography indicates that also there is an increase in cholesterol esters in nuclei, mitochondria and microsomes of mice liver whereas monoacylglycerol almost disappeared in mitochondria and microsomes after DMH administration in comparison to their respective controls.