Piclamilast mitigates 1,2-dimethylhydrazine induced colon cancer in rats through modulation of Ras/PI3K/Akt/mTOR and NF-κß signaling.

Colorectal cancer (CRC) is the third leading type of adult cancer in both genders with high morbidity and mortality worldwide. Even though the discovery of many antineoplastic drugs for CRC, the current therapy is not adequately efficient.This study was designed to investigate the effect and mechanism of Piclamilast (PIC), a selective PDE4 inhibitor, on a DMH-induced colorectal cancer (CRC) rat model. The rats were grouped (n = 10) into group 1 (control), group 2 (PIC 3 mg/kg, p.o.), groups 3-5 received DMH (20 mg/kg/week, S.C.), and groups 4 and 5 received PIC (1 and 3 mg/kg/day, p.o.) for 15 weeks. The DMH treatment increased aberrant crypt foci (ACF), Proliferating cell nuclear antigen (PCNA), and TBARS levels, along with decreased antioxidant defenses (GSH, GSH-Px, and catalase). Increased NF-κß expression and inflammatory cytokines were also evident. PIC dose-dependently reduced ACF and restored oxidative stress and inflammatory markers favorably. Moreover, PIC in its large, tested dose only significantly increased the intracellular level of cAMP and suppressed the activation of Ras and PI3K and its downstream Akt/mTOR signaling. Furthermore, PIC promoted CRC apoptosis, and increased the gene expression of the apoptotic factors, caspase-3 and Bax, and decreased the anti-apoptotic factor Bcl-2. The results of this study show that PIC may be a promising therapeutic agent for the treatment of CRC. PIC might inhibit the proliferation of CRC cells and induce apoptosis via multiple mechanisms that involve its antioxidant effect and inhibition of NF-κß and Ras/PI3K/Akt/mTOR signaling.

Dietary PlsEtn Ameliorates Colon Mucosa Inflammatory Stress and ACF in DMH-Induced Colon Carcinogenesis Mice: Protective Role of Vinyl Ether Linkage.

Ethanolamine plasmalogen (PlsEtn), a sub-class of ethanolamine glycerophospholipids (EtnGpl), is a universal phospholipid in mammalian membranes. Several researchers are interested in the relationship between colon carcinogenesis and colon PlsEtn levels. Here, we evaluated the functional role of dietary purified EtnGpl from the ascidian muscle (87.3 mol% PlsEtn in EtnGpl) and porcine liver (7.2 mol% PlsEtn in EtnGpl) in 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in vivo, and elucidated the possible underlying mechanisms behind it. Dietary EtnGpl-suppressed DMH-induced aberrant crypt with one foci (AC1) and total ACF formation (P < 0.05). ACF suppression by dietary ascidian muscle EtnGpl was higher compared with dietary porcine liver EtnGpl. Additionally, dietary EtnGpl decreased DMH-induced oxidative damage, overproduction of TNF-α, and expression of apoptosis-related proteins in the colon mucosa. The effect of dietary ascidian muscle EtnGpl showed superiority compared with dietary porcine liver EtnGpl. Our results demonstrate the mechanisms by which dietary PlsEtn suppress ACF formation and apoptosis. Dietary PlsEtn attained this suppression by reducing colon inflammation and oxidative stress hence a reduction in DMH-induced intestinal impairment. These findings provide new insights about the functional role of dietary PlsEtn during colon carcinogenesis.

Thymoquinone, the Nigella sativa bioactive compound, prevents circulatory oxidative stress caused by 1,2-dimethylhydrazine in erythrocyte during colon postinitiation carcinogenesis.

We have performed this study to investigate the modulatory effect of thymoquinone (TQ), the Nigella sativa active compound, on erythrocyte lipid peroxidation and antioxidant status during 1,2-dimethylhydrazine- (DMH-) induced colon carcinogenesis after initiation in male Wistar rats. Rats exposed to DMH showed an increase of malondialdehyde and conjugated diene levels, and an augmentation of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also noted. The TQ pretreatment restored the parameters cited above to near-normal values. However, the posttreatment shows an activity similar as that presented by DMH. Therefore, our investigation revealed that TQ was a useful compound preventing DMH-induced erythrocyte damages.

Altered membrane lipid dynamics and chemoprevention by non-steroidal anti inflammatory drugs during colon carcinogenesis.

The present work focuses on the anti-neoplastic role of non steroidal anti-inflammatory drugs (NSAIDs) in modulating the biophysical parameters of the colonic membranes in 1,2-dimethylhydrazine dihydrochloride (DMH) induced carcinogenesis. The steady-state fluorescence polarization technique was applied to assess membrane fluidity, membrane polarity and lipid phase states. The decline in cholesterol content, biosynthesis and cholesterol: phospholipids ratio with DMH treatment indicates more fluidity associated with carcinogenesis. The DMH group had shown lower order parameter indicating more fluidity whereas NSAIDs resulted in increasing the membrane lipid order. The converging effects of these changes were more in membrane phase separations and membrane phase state. In DMH treatment membrane shows lesser phase separation or high polarity, and more liquid crystalline state while for NSAID groups membranes have higher phase separations or low polarity, and more of the gel phase. Further, NSAIDs induced anti-proliferative effects were evidently observed by apoptosis in the colonocytes by using acridine orange-ethidium bromide fluorescent staining and Terminal de-oxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The results suggest that NSAIDs induced alteration in the membrane biophysical parameters may be an important initiating event for the chemopreventive action.

Silibinin modulates biotransforming microbial enzymes and prevents 1,2-dimethylhydrazine-induced preneoplastic changes in experimental colon cancer.

Chemoprevention directed towards the control of colon carcinogenesis in its early stages should ultimately provide a higher quality of life for people than waiting to treat end-stage disease. Silibinin is a major bioactive compound that is present in the widely consumed dietary supplement Silymarin. The current investigation aimed to explore the effect of the phytochemical silibinin on the suppression of 1,2-dimethylhydrazine-induced colonic preneoplastic changes in a long-term preclinical model. Wistar male rats were divided into six groups: group 1 were control rats, group 2 were control rats that received silibinin alone (50 mg/kg body weight orally everyday), rats in group 3 were injected once weekly with 1,2-dimethylhydrazine (20 mg/kg body weight, subcutaneously 15 times), in addition, group 4 (initiation), group 5 (post initiation) and group 6 (entire period) received silibinin as in group 2. At the end of 32 weeks, the activities of the colonic and faecal biotransforming microbial enzymes were analysed. Modulatory effects were also evaluated using aberrant crypt foci (ACF), dysplastic ACF and tumour incidence as endpoint markers. Silibinin markedly reduced tumour incidence, as compared with the rats treated with unsupplemented 1,2-dimethylhydrazine. The most pronounced inhibition of ACF and dysplastic ACF development was observed in the rats fed with silibinin for the entire period and also during the post initiation period. Silibinin administration also significantly (P<0.05) modulated the biotransforming activity of microbial enzymes. The results of our study suggest that silibinin suppresses 1,2-dimethylhydrazine-induced colon carcinogenesis at various stages and exerts a potential chemopreventive action against colon cancer.

Polymeric black tea polyphenols inhibit 1,2-dimethylhydrazine induced colorectal carcinogenesis by inhibiting cell proliferation via Wnt/beta-catenin pathway.

Tea polyphenols like epigallocatechin gallate and theaflavins are established chemopreventive agents for colorectal carcinogenesis. However, studies on evaluating similar chemopreventive properties of thearubigins or polymeric black tea polyphenols (PBPs), the most abundant polyphenols in black tea, are limited. Hence, in the present study we aim to investigate chemopreventive effects along with probable mechanisms of action of PBP extract employing 1,2-dimethylhydrazine (DMH)-induced colorectal carcinogenesis in Sprague-Dawley rats as experimental model. The present study suggests that PBPs, like other tea polyphenols, also inhibit DMH-induced colorectal tumorigenesis by decreasing tumor volume and multiplicity. This study also shows that although the pretreatment with PBP extract could induce detoxifying enzymes in hepatic and colorectal tissue, it did not show any additional chemopreventive effects when compared to treatments with PBP extract after initiation with DMH. Mechanistically, PBP extract may inhibit colorectal carcinogenesis by decreasing DMH-induced cell proliferation via Wnt/beta-catenin pathway. Treatments with PBP extract showed decreased levels of COX-2, c-MYC and cyclin D1 proteins which aid cell proliferation probably by regulating beta-catenin by maintaining expression of APC and decreasing inactivation of GSK3beta. DMH-induced activation of MAP kinases such as ERK and JNK was also found to be inhibited by treatments with PBP extract. In conclusion, the protective effects of PBP extract could be attributed to inhibition of DMH-induced cellular proliferation probably through beta-catenin regulation.

Prevention of 1,2-dimethylhydrazine-induced circulatory oxidative stress by bis-1,7-(2-hydroxyphenyl)-hepta-1,6-diene-3,5-dione during colon carcinogenesis.

We have performed this study to investigate the modulatory effect of bis-1,7-(2-hydroxyphenyl)-hepta-1,6-diene-3,5-dione, a bisdemethoxy curcumin analog (BDMCA) on circulatory lipid peroxidation (LPO) and antioxidant status during 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in male Wistar rats. The effects were compared with that of the reference drug, curcumin. Increased tumor incidence as well as enhanced LPO in the circulation of tumor bearing rats was accompanied by a significant decrease in the level of reduced glutathione and activities of glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). Intragastric administration of BDMCA or curcumin to DMH-treated rats significantly decreased colon tumor incidence and the circulatory LPO, with simultaneous enhancement of GSH content and GPx, GST, SOD and CAT activities. We report that BDMCA exert its chemopreventive effect by decreasing the colon tumor incidence as well as by modulating circulatory oxidative stress in DMH-treated rats through its influence on LPO and antioxidant status. The effects of BDMCA were comparable with that of the reference compound curcumin, a well known anticarcinogen and antioxidant. Thus, it would be suggested that the methoxy group is not responsible for the beneficial effects, however, the terminal phenolic moieties or the central 7-carbon chain may play a role.

PSC 833, an inhibitor of P-glycoprotein inhibits 1,2-dimethylhydrazine-induced colorectal carcinogenesis in male Fischer F344 rats.

BACKGROUND: The expression of P-glycoprotein (Pgp) is intimately associated with cancer development. In order to explore the therapeutic value of Pgp as a target for chemotherapy, we studied the effect of PSC 833 (PSC), a potent inhibitor of Pgp, on 1,2-dimethylhydrazine (1,2-DMH)-initiated colorectal carcinogenesis in rats. MATERIALS AND METHODS: Male Fischer 344 rats, initiated with 1,2-DMH coupled with partial hepatectomy, were exposed to dietary 1% orotic acid for 22 weeks. They were then fed either the AIN93G basal diet (BD) or BD containing PSC (a daily dose of 15 mg/kg body weight) for 35 weeks. RESULTS: PSC significantly inhibited colorectal tumor multiplicity by 53% and tumor burden by 74%. PSC-mediated inhibition was evident in tumors as small as 2 mm in diameter and remained effective throughout the course of tumor growth. Histological assessment showed that PSC significantly inhibited tumor progression to colorectal adenocarcinoma by 63%. CONCLUSION: Collectively, this study indicates that PSC inhibited experimental colorectal carcinogenesis initiated with 1,2-DMH in rats.

Lack of chemopreventive effects of alpha-eleostearic acid on 7,12-dimethylbenz[a]anthracene (DMBA) and 1,2-dimethylhydrazine (DMH)-induced mammary and colon carcinogenesis in female Sprague-Dawley rats.

alpha-Eleostearic acid is one of the conjugated linolenic acids from tung oil, which is obtained from the seeds of Aleurites fordii. The effects of dietary alpha-eleostearic acid (18:3, n-5) on the post-initiation period of 7,12-dimethylbenz[a]anthracene (DMBA) and 1,2-dimethylhydrazine (DMH)-induced mammary and colon carcinogenesis were examined using female Sprague-Dawley (SD) rats. For initiation, rats were given subcutaneous injections of 40mg/kg body weight (5 times) and 20mg/kg body weight (3 times) of DMH during the age of 6-8 weeks and a single intragastric administration of 50mg/kg body weight of DMBA at 9 weeks. Then, the animals were treated with 0%, 0.01%, 0.1% or 1.0% alpha-eleostearic acid for 34 weeks. Control rats received the basal diet alone or 1.0% alpha-eleostearic acid without prior initiation treatment. All surviving animals were killed at week 37 of the experiment. There were no statistically significant alterations in any of the parameters for either mammary or colon tumors. These results thus indicate that alpha-eleostearic acid does not exert clear modification effects on DMBA and DMH-induced mammary and colon carcinogenesis, at least under the present experimental conditions.

Anticarcinogenic effect of bis-1,7-(2-hydroxyphenyl)-hepta-1,6-diene-3,5-dione a curcumin analog on DMH-induced colon cancer model.

1,2-Dimethylhydrazine (DMH) is a toxic environmental pollutant which was reported also to be a colon-specific carcinogen. This study was performed to study the effect of bis-1,7-(2-hydroxyphenyl)-hepta-1,6-diene-3,5-dione, a bisdemethoxycurcumin analog (BDMC-A) on DMH-induced colon carcinogenesis in male Wistar rats and effects were compared with that of the reference drug, curcumin. Rats were given a weekly subcutaneous injection of DMH (20mg/kg body weight) in the groin, for 15 weeks. After a total experimental period of 32 weeks (including 2 weeks of acclimatization) tumor incidence was 100% in DMH-treated rats. Tumor was identified histologically as adenocarcinoma. Dysplasia, papillary pattern, cellular pleomorphism and carcinomatous glands were also noticed in DMH-treated rats. However, there was no colonic tumor in DMH+BDMC-A- and DMH+curcumin-treated rats but, lymphocyte infiltrations were observed. The levels of total bile acids and cholesterol in 24h fecal samples were significantly lower in DMH administered rats when compared to control rats, while, the excretion of bile acids and cholesterol were significantly increased and was near normal levels in DMH+BDMC-A- and DMH+curcumin-treated rats. In DMH-induced tumor bearing rats the levels of colonic and intestinal cholesterol was significantly increased whereas, the levels of phospholipid was decreased with a concomitant increase in the activities of phospholipase A (PLA) and phospholipase C (PLC), compared to untreated control rats. Intragastric administration of BDMC-A and curcumin to DMH administered rats significantly lowered the cholesterol content and raised the phospholipid content and lowered the activities of PLA and PLC towards near normal values. Our study shows that the protective effect of BDMC-A during DMH-induced colon carcinogenesis may be due to its modulatory effects on (i). histological changes, (ii). bile acids, (iii). cholesterol, and (iv). phospholipid metabolism in the target organ. Absence of histological changes in the colon of rats treated with BDMC-A, shows that long term administration of BDMC-A is nontoxic to experimental animals. Our study suggest that BDMC-A may emerge as a potent anticarcinogenic agent against colon cancer. As both BDMC-A and curcumin are equipotent in inhibiting the DMH-induced colon tumor incidence and normalizing histological changes, it could be concluded that the terminal phenolic group and the conjugated double bonds in the central seven carbon change may be responsible for the beneficial effects.

Silk protein, sericin, suppresses colon carcinogenesis induced by 1,2-dimethylhydrazine in mice.

Male 5-week old ICR mice were examined for the effect of feeding silk protein, sericin on colon carcinogenesis. In experiment 1, mice were fed the diets supplemented with 1.5% or 3% sericin for five weeks, and given weekly injections of 1,2-dimethylhydrazine (DMH) for the initial three weeks. Supplemental sericin caused a dose-dependent decrease in the development of colonic aberrant crypt foci. In experiment 2, mice were fed the diet supplemented with 3% sericin for 115 days, and given weekly injections of DMH for the initial ten weeks. The incidence and number of colon tumors were suppressed by consumption of sericin. The results suggest a potential usefulness of sericin as a chemopreventive agent for colon carcinogenesis.

Bacteria used for the production of yogurt inactivate carcinogens and prevent DNA damage in the colon of rats.

Lactic acid-producing bacteria prevent carcinogen-induced preneoplastic lesions and tumors in rat colon. Because the mechanisms responsible for these protective effects are unknown, two strains of lactic acid bacteria, Lactobacillus delbrueckii ssp. bulgaricus 191R and Streptococcus salivarius ssp. thermophilus CH3, that are used to produce yogurt, were investigated in vitro and in vivo to elucidate their potential to deactivate carcinogens. Using the "Comet assay" to detect genetic damage, we found that L. bulgaricus 191R applied orally to rats could prevent 1, 2-dimethylhydrazine-induced DNA breaks in the colon in vivo, whereas St. thermophilus CH3 were not effective. However, in vitro, both strains prevented DNA damage induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in isolated primary rat colon cells. Extracts prepared from milk fermented with St. thermophilus CH3 were as efficient in deactivating MNNG as was L-cysteine. Isolated metabolites arising from bacteria during fermentation in the colon or in milk [L(+) lactate, D(-) lactate, palmitic acid and isopalmitic acid] were not effective. We postulate that thiol-containing breakdown products of proteins, via catalysis by bacterial proteases, could be one mechanism by which MNNG or other carcinogens are deactivated in the gut lumen resulting in reduced damage to colonic mucosal cells.

[The influence of melatonin on mutagenicity and antitumor action of cytostatic drugs in mice]. / Vliianie melatonina na mutagennost' i protivoopukholevyi éffekt tsitostatikov u myshei.

SHR mice received single injections of N-nitrosomethylurea (NMU, 50 mg/kg, i.p.), cyclophosphamide (CP, 200 mg/kg, i.p.) or 1,2-dimethylhydrazine (DMH, 15 mg/kg, s.c.) alone or in combination with melatonin (5 mg/kg, s.c.). For mutagenic study chromosome aberrations tests (ChA) in bone marrow cells and sperm head anomaly test (SHA) were used. Melatonin did not appear mutagenic in either of the tests and significantly reduced the level of ChA (%) from 16.9 +/- 1.6 (NMU), 13.7 +/- 3.5 (CP) and 8.7 +/- 0.3 (DMH) to 4.5 +/- 0.6, 4.3 +/- 0.9 and 5.6 +/- 0.2, respectively, (p < 0.05). Similarly, SHA frequency (%) under the melatonin influence was reduced from 18.6 +/- 0.4 (NMU), 17.7 +/- 0.4 (CP) and 10.0 +/- 0.5 (DVH) to 9.9 +/- 0.5, 6.1 +/- 0.3 and 7.5 +/- 0.2, respectively, (p < 0.05). Unlike in controls, exposure to melatonin in drinking water (20 mg/l, at night) or in injections (5 mg/kg, s.c.) alone or in combination with NMU or CP failed to influence subcutaneously-transplanted Ehrlich carcinoma growth. These findings suggest that melatonin reduced the mutagenicity of the cytostatic drugs without affecting their anti-tumor action.