Panx1 knockout promotes preneoplastic aberrant crypt foci development in a chemically induced model of mouse colon carcinogenesis

Colorectal cancer, which is the third leading cause of cancer-related deaths worldwide, is a multistep disease, featuring preneoplastic aberrant crypt foci (ACF) as the early morphological manifestation. The roles of hemichannel-forming transmembrane Pannexin 1 (Panx1) protein have not been investigated in the context of colon carcinogenesis yet, although it has contrasting roles in other cancer types. Thus, this study was conducted to examine the effects of Panx1 knockout (Panx1-/- ) on the early events of chemically induced colon carcinogenesis in mouse. Wild type (WT) and Panx1-/- female C57BL6J mice were submitted to a chemically induced model of colon carcinogenesis by receiving six intraperitoneal administrations of 1,2-dimethylhydrazine (DMH) carcinogen. Animals were euthanized 8 h (week 7) or 30 weeks (week 37) after the last DMH administration in order to evaluate sub-acute colon toxicity outcomes or the burden of ACF, respectively. At week 7, Panx1 genetic ablation increased DMH-induced genotoxicity in peripheral blood cells, malondialdehyde levels in the colon, and apoptosis (cleaved caspase-3) in colonic crypts. Of note, at week 37, Panx1-/- animals showed an increase in aberrant crypts (AC), ACF mean number, and ACF multiplicity (AC per ACF) by 56%, 57% and 20%, respectively. In essence, our findings indicate that Panx1 genetic ablation promotes preneoplastic ACF development during chemically induced mouse colon carcinogenesis, and a protective role of Panx1 is postulated.

Bavachinin mitigates DMH induced colon cancer in rats by altering p53/Bcl2/BAX signaling associated with apoptosis

Bavachinin is a flavanone obtained from the Chinese herb, Fructus Psoraleae. Flavonoids and flavanones are recognized as cancer preventive agents. We investigated the anticancer properties of bavachinin using a model of dimethylhydrazine (DMH and dextran sodium sulfate (DSS) induced rat colon cancer. We investigated aberrant crypt foci (ACF), hyperplastic lesions, catalase (CAT), superoxide dismutase (SOD) and glutathione (GST) levels in Wistar rats. Expression of cancer biomarkers including IL-6, p53, Bcl2 and BAX was investigated. We found that bavachinin administered to rats re-established the colonic crypts that were damaged by DMH and prevented progression of the cancer.

Effects of karanjin on dimethylhydrazine induced colon carcinoma and aberrant crypt foci are facilitated by alteration of the p53/Bcl2/BAX pathway for apoptosis

We investigated the effects of karanjin on dimethylhydrazine (DMH) induced colon cancer in rats. Male Wistar rats were injected with DMH followed by dextran sodium sulfate in drinking water for 7 days. Karanjin at doses of 50,100 and 200 mg/kg was administered orally for 18 weeks. Colon tissues were investigated using TUNEL analysis of apoptosis; histopathological assessment including number of aberrant crypt foci (ACF); immunohistochemical staining for Bcl-2-associated X protein (BAX), B-cell lymphoma 2 (Bcl2), p53 and proliferating cell nuclear antigen (PCNA); and antioxidant assay in vivo. We found that treatment with karanjin inhibited formation of ACF in the colon mucosa and reduced colon lesions. Karanjin treatment also increased the antioxidants, catalase, glutathione and superoxide dismutase. Immunostaining showed that karanjin treatment reduced BAX, p53 and PCNA levels and increased Bcl2 expression. The TUNEL assay revealed that karanjin induced apoptosis in the colon mucosa. Our findings suggest that karanjin can ameliorate colon carcinogenesis in rats by regulating BAX, Bcl2 and p53 pathways.

Pharmabiotic beads with improved encapsulation and gut survival for management of colonic inflammation associated gut derangements

Encapsulation techniques and materials, explored for addressing compromised probiotic gut survival, report significant production losses resulting in <10% entrapment. Presently, we report three-time enhanced entrapment (30 ± 1.2%) of Lactobacillus acidophilus (LAB) in calcium-alginate beads, by modifying process parameters and employing polyethylene glycol (PEG). Water-loving, viscolysing and osmotic-building effects of PEG create numerous, fine voids in the alginate gel allowing efficient diffusion of crosslinking calcium ions, resulting in less leaky beads. Eudragit S100 overcoat improved LAB survival by 690 times in simulated GIT stresses.In DMH-DSS induced colitis and precancerous lesions in rats, while free LAB failed to show any protection, pharmabiotic beads significantly (p < .05) reduced lipid peroxidation, increased antioxidant levels; decreased serum inflammatory burden; downregulated COX-2, iNOS, and c-Myc expression; elevated levels of the selected gut bacteria and SCFAs especially butyrate, all of which add up to antioxidant, anti-inflammatory, balanced gut biota, and ultimately anticancer effects.

The modulatory effects of exercise on the inflammatory and apoptotic markers in rats with 1,2-dimethylhydrazine-induced colorectal cancer

This study aimed to investigate the underlying mechanisms in anti-tumorigenesis effects of exercise through evaluation of inflammation and apoptosis. Twenty-four Wistar rats were divided into control, exercise, 1,2-dimethylhydrazine (DMH), and DMH + exercise. After a week, rats in the DMH group were given DMH twice a week for 2 weeks. Animals in the exercise groups performed exercise on a treadmill 5 days/week for 8 weeks. After 8 weeks of training, levels of COX-2, PCNA, Bax, Bcl-2, and procaspase-3/cleaved caspase-3 were assessed. Histological changes, number of aberrant crypt foci (ACF), and serum levels of TNF-α and IL-6 were also analyzed. ACF number was significantly decreased following the exercise program. Protein levels of COX-2 and PCNA and serum levels of IL-6 and TNF-α were significantly elevated in the rats receiving DMH and downregulated after performing the exercise program (P < 0.05). Exercise upregulated apoptosis, which was evident from the increased Bax/Bcl2 ratio, and enhanced the expression levels of activated caspase-3 as compared to the DMH group. The colonic architecture was improved in DMH + exercise. Exercise can effectively attenuate DMH-induced increase of inflammatory markers. Exercise induces apoptosis at the downstream of the inflammatory response. Therefore, exercise may play a role as a moderator of inflammation to exert protective effects against colon cancer.

Artesunate suppresses inflammation and oxidative stress in a rat model of colorectal cancer

Anti-inflammatory drugs are well known to reduce the risk of colon cancer and prophylactic use of such agents is gaining acceptance as a cancer prevention therapy. As artesunate, an antimalarial drug, has been shown to exhibit chemopreventive properties, the present study was carried out to evaluate its inhibitory effect on oxidative stress and inflammation in a rat model of colon carcinogenesis. A chemical carcinogen, 1,2-dimethylhydrazine was injected twice at an interval of 1 week to induce preneoplastic lesions in the colon and the parameters indicating oxidative stress and inflammation were evaluated after 8 weeks. Artesunate (50 and 150 mg/kg) and aspirin (60 mg/kg) were administered orally throughout the study. Analysis of colon tissue revealed that both the drugs preserved histoarchitecture, inhibited cellular influx, decreased the levels of oxidative stress and inflammatory markers, downregulated cyclooxygenase-2, inducible nitric oxide synthase, nuclear factor κB, and interleukin 1β in comparison to the experimental control. Suppression of oxidative stress and pro-inflammatory signaling by both the drugs were found to contribute to inhibition of colon carcinogenesis. The protection afforded by these drugs was found to be comparable. Our study shows that like aspirin, use of artesunate could also reduce the risk of colon cancer and it has a potential for further evaluation for the treatment purpose.

Reduction of Preneoplastic Lesions Induced by 1,2-Dimethylhydrazine in Rat Colon by Maslinic Acid, a Pentacyclic Triterpene from Olea europaea L

Maslinic acid triggers compelling antiproliferative and pro-apoptotic effects in different human cancer cell lines. Hence, the chemopreventive activity was investigated on early stages of carcinogenesis induced by 1,2-dimethylhydrazine (DMH) which is a model that mimics human sporadic colorectal cancer. Male Sprague-Dawley rats were orally administered either maslinic acid at 5, 10 or 25 mg/kg dissolved in (2-hydroxypropyl)-β-cyclodextrin 20% (w/v) or the solvent for 49 days. After one week of treatment, animals received three weekly intraperitoneal injections of DMH at the dose of 20 mg/kg. Maslinic acid reduced the preneoplastic biomarkers, aberrant crypt foci (ACF) and mucin-depleted foci (MDF), already at 5 mg/kg in a 15% and 27%, respectively. The decline was significant at 25 mg/kg with decreases of 33% and 51%, respectively. Correlation analysis showed a significant association between the concentrations of maslinic acid found in the colon and the reduction of ACF (r = 0.999, p = 0.019) and MDF (r = 0.997, p = 0.049). The present findings demonstrate that maslinic acid induced an inhibition of the initiation stages of carcinogenesis. The assessment of this pentacyclic triterpene at the colon sheds light for designing diets with foods rich in maslinic acid to exert a chemopreventive activity in colorectal cancer.

Transplantation of placenta-derived multipotent cells in rats with dimethylhydrazine-induced colon cancer decreases survival rate

Transplantation of placenta-derived multipotent cells (PDMCs) is a promising treatment method for many diseases. However, the impact of PDMCs on colon cancer has not yet been studied. PDMCs were obtained from rat placentas by culturing tissue explants. Colon cancer was experimentally induced in male albino Wistar rats by administering 20 mg/kg dimethylhydrazine (DMH) once a week for 20 consecutive weeks. The administration of the PDMCs was performed at the 20th week after the first DMH injection. The number and size of each tumour lesion were calculated in the 5th week after transplantation. The tumour type was determined by standard histological methods. To study the engraftment of PDMCs in the body of rats, the cells were transduced with enhanced green fluorescent protein. Cell engraftment was determined by assessing the presence of EGFP by PCR and immunohistochemistry. Survival of all rats was monitored daily. Allogeneic transplantation of PDMCs to rats at middle phase of DMH-induced colon carcinogenesis did not significantly influence the number of neoplasms and the parameters of mean and total tumour area, but led to an increase in size of the most invasiveness tumours. Intravenous allogeneic transplantation of PDMCs reduced the survival rate of rats with colon cancer by 17 days. PDMCs from rats engrafted into tissues of the normal intestine, tumours, lungs, liver, and spleen of rats for five weeks after intravenous transplantation. These results suggest that intravenous allogeneic transplantation of PDMCs promotes colon cancer progression and has a negative impact on survival of rats.

Chemopreventive Action by Ethanol-extracted Brazilian Green Propolis on Post-initiation Phase of Inflammation-associated Rat Colon Tumorigenesis

BACKGROUND/AIM

Propolis has since long been utilized in numerous folk medicines with a variety of medicinal properties. In this study, the effects of ethanol-extracted (EEP) and water-extracted (WEP) Brazilian green propolis on the post-initiation phase of inflammation-associated rat colon tumorigenesis were directly compared.

MATERIALS AND METHODS

Male F344 rats at 6 weeks of age were subcutaneously injected with 1,2-dimethylhydrazine (DMH) at 40 mg/kg body weight twice during the first week, followed by 1% dextran sodium sulfate (DSS) in drinking water for one week. After a 1-week no-treatment period, animals were administered either basal Oriental MF powdered diet, or 1% EEP or 1% WEP in the basal diet until week 32.

RESULTS

Post-initiation treatment with EEP significantly reduced the multiplicity of colorectal carcinomas compared to the control (0.40±0.13/rat vs. 2.29±0.84/rat, respectively, p<0.05), and EEP also reduced the tumor volume. Immunohistochemically, expression of inflammation-associated proteins inducible nitric oxide synthase, tumor necrotic factor alpha, nuclear factor kappa B and glutathione peroxidase-2 were significantly diminished in colorectal tumors from EEP-treated rats.

CONCLUSION

Suppression of inflammation and oxidative stress, which had been triggered by DMH and promoted by DSS, was a primary mechanism by which EEP suppressed carcinogenesis.

Genistein regulates tumor microenvironment and exhibits anticancer effect in dimethyl hydrazine-induced experimental colon carcinogenesis

Colon cancer is one of the leading causes of cancer mortality, worldwide. Cancer stem cells are attractive targets for therapeutic interventions since their abnormal growth may trigger tumor initiation, progression, and recurrence. Colon cancer in rats were induced with 1, 2-dimethyl hydrazine (DMH) and treated with genistein, an isoflavone rich in the soy food products, which also possesses various biological activities. Genistein treatment regulates enzymatic and non-enzymatic anti-oxidants in the DMH-induced colonic tissue microenvironment. Alcian blue staining in colonic tissue reveals that mucin secretion was found to be depleted in DMH-induced group of animals. The alterations were normalized in the genistein-treated groups. Also, the mast cell population and collagen deposition were reduced as compared to induced group. Genistein treatment reduces the prognostic marker Argyrophilic nuclear organizer region (AgNOR) and proliferating cell nucleolar antigen (PCNA) in DMH-induced group of rats. DMH administration induces oxidative stress, whereas genistein activates nuclear factor-erythroid 2 related factor 2 (Nrf-2) and its downstream target hemoxygenase-1 (HO-1). Colonic stem cell marker protein CD133, CD44, and β-catenin expressions were found to be increased in DMH-induced group of animals as compared to control group of rats. Genistein treatment suppressed the expression of these stem cell markers suggesting rapid dysfunctional activation and proliferation of colonic stem cell-induced by DMH. The results of this study indicate that genistein administration in rats restored the colonic niche that was damaged by DMH and inhibits colon cancer progression. © 2016 BioFactors, 42(6):623-637, 2016.

Chemoprevention of tea on colorectal cancer induced by dimethylhydrazine in Wistar rats

AIM:To investigate the chemopreventive effects of green tea and tea pigment on 1,2-dimethylhydrazine (DMH)-induced rat colorectal carcinogenesis.METHODS:Male weaning Wistar rats were randomly allocated into four groups.Rats in the positive control group were given a(c)s.c. injection of DMH, once a week for ten weeks;rats in tea treated groups, with the same DMH treatment as in the positive group, received 2% green tea and 0.1% tea pigments; rats in the negative control group were given s.c.injection of the same volume of saline as well as DMH in the positive group. Animals were sacrified and necropsied at the end of week 16 and week 32.RESULTS:Aberrant cryptic foci (ACF) were formed in animals in DMH-treated groups at the end of week 16. Compared to the DMH group, green tea and tea pigments groups had less ACF (148.25 and 204.25, respectively, P<0.01). At the end of week 32, all rats in DMH group developed large intestinal tumors. The results also showed that DMH increased labeling index (LI) of proliferating cell nuclear antigen (PCNA) of intestinal mucosa and the expression of ras-p21. However, in the tea-treated groups, PCNA-LI was significantly reduced as compared with the positive control group (36.63 and 40.36 in the green tea group and tea pigment group, respectively, at the end of the experiment,P<0.01).ras-p21 expression was also significantly reduced (2.07 and 2.36 in the colon tumors of rats in the green tea group and tea pigments group, respectively at the end of the experiment, P<0.01). Furthermore, green tea and tea pigment inhibited the expression of Bcl-2 protein (2, 5, 1, 0 and 2, 4, 1, 0,respectively, at the end of the experiment P<0.01), and induced expression of Bax protein (0,1,3,4 and 0,1,4,3, respectively, P <0.01).CONCLUSION:Chinese green tea drinking inhibited ACF and colonic tumors formation in rats, which showed that tea had a significant chemopreventive effect on DMH-induced colorectal carcinogenesis. Such effects may be due to suppression of cell proliferation and induction of apoptosis in the intestinal crypts.

Activated K-ras in tumorigenic and non-tumorigenic cell variants from a rat colon adenocarcinoma, induced by dimethylhydrazine

Using NIH3T3 cell transfection assay, activated c-K-ras was detected in two cell lines, TRb and TSb, obtained from a single colon adenocarcinoma induced in a rat by 1,2-dimethylhydrazine. TRb cells give rise to progressive and metastatic tumors in the syngeneic rats, whereas TSb cells only induce regressive tumors. Levels of K-ras transcripts in TRb and TSb cells were higher than that of NIH3T3 cells, but no difference was found between TRb and TSb cells. No significant difference was observed in expression levels of c-myc in these two cell lines. c-fos expression was, however, significantly lower in TRb than TSb cells.