Inhibition of DMBA/croton oil-induced two-stage mouse skin carcinogenesis by diphenylmethyl selenocyanate

Attenuation of cyclophosphamide-induced pulmonary toxicity in Swiss albino mice by naphthalimide-based organoselenium compound 2-(5-selenocyanatopentyl)-benzo[de]isoquinoline 1,3-dione

CONTEXT

The widely used antineoplastic drug cyclophosphamide causes pulmonary toxicity by inducing oxidative stress. Selenium, a dietary micronutrient, has been found to protect various organs from oxidative injuries.

OBJECTIVE

This study was designed to investigate the protective efficacy of an organoselenium compound 2-(5-selenocyanato-pentyl)-benzo[de]isoquinoline 1,3-dione against cyclophosphamide-induced pulmonary toxicity in Swiss albino mice.

MATERIALS AND METHODS

Cyclophosphamide (25 mg/kg b.w.) was administered intraperitoneally for 10 d and the organoselenium compound (3 mg/kg b.w.) was given by oral gavage in concomitant and pretreatment schedules. Various biochemical parameters related to oxidative stress and antioxidant enzymes along with histology of lungs were evaluated to assess the effect of the test compound.

RESULTS

The oral LD50 of the test compound was more than 1000 mg/kg b.w. in Swiss albino mice. The test compound substantially ameliorated cyclophosphamide-induced pulmonary injury by reducing the levels of reactive oxygen species, reactive nitrogen species, and lipid peroxidation, respectively, by 14.88, 18.54, and 21.10% in concomitant treatment schedule and by 23.89, 35.73, and 30.76% in the pretreatment schedule as well as by restoring the level of reduced glutathione and activities of glutathione-S-transferase, superoxide dismutase, catalase, and glutathione peroxidase, respectively, by 36.88, 42.43, 38.0, 35.0, and 34.06% in the concomitant treatment schedule and by 66.02, 59.29, 57.23, 71.59, and 57.22% in the pretreatment schedule. The test compound also attenuated cyclophosphamide-induced histological alterations of lung tissue.

DISCUSSION AND CONCLUSION

The test compound emerged as an efficient antioxidant protecting lungs tissue from cyclophosphamide-induced injury.

Nanovesicular carrier-based formulation for skin cancer targeting: evaluation of cytotoxicity, intracellular uptake, and preclinical anticancer activity

CONTEXT

Skin cancer has turned into global epidemic leading to higher incidences among cancer stricken population.

OBJECTIVE

The aim of the present investigation is to evaluate the anticancer potential and intracellular uptake of a novel nanovesicular formulation of 5-FU.

MATERIALS AND METHODS

Detailed intracellular uptake study in conjunction with estimation of intracellular reactive oxygen species was done using skin melanoma cell lines (A375) along with cytotoxicity studies. To further obtain the mechanistic insights into inhibition of tumor cell proliferation, cell-cycle arrest studies were conducted. The preclinical anticancer activity was carried out employing in vivo DMBA-croton oil-induced skin cancer model in mice.

RESULTS AND DISCUSSION

Significant reduction in the number of papillomas was observed in skin cancer-bearing mice on treatment with nanovesicular formulation (51.4 ± 3.2%) in comparison with marketed formulation (21.3 ± 2.1%) of 5-FU. Tumor volume was found to be reduced to 46.3 ± 3.5% with prepared formulation, whereas the marketed formulation-treated group showed the reduction of 18.6 ± 1.8% in comparison with the control (untreated) group.

CONCLUSION

The results of present study demonstrated that nanovesicular formulation of 5-FU possessed the enhanced anticancer activity which could be attributed to better intracellular uptake, cellular retention, and sustained release of drug.

Manganese superoxide dismutase in cancer prevention

SIGNIFICANCE

Cancer is the second leading cause of death in the United States. Considering the quality of life and treatment cost, the best way to fight against cancer is to prevent or suppress cancer development. Cancer is preventable as indicated by human papilloma virus (HPV) vaccination and tamoxifen/raloxifen treatment in breast cancer prevention. The activities of superoxide dismutases (SODs) are often lowered during early cancer development, making it a rational candidate for cancer prevention.

RECENT ADVANCES

SOD liposome and mimetics have been shown to be effective in cancer prevention animal models. They've also passed safety tests during early phase clinical trials. Dietary supplement-based SOD cancer prevention provides another opportunity for antioxidant-based cancer prevention. New mechanistic studies have revealed that SOD inhibits not only oncogenic activity, but also subsequent metabolic shifts during early tumorigenesis.

CRITICAL ISSUES

Lack of sufficient animal model studies targeting specific cancers; and lack of clinical trials and support from pharmaceutical industries also hamper efforts in further advancing SOD-based cancer prevention.

FUTURE DIRECTIONS

To educate and obtain support from our society that cancer is preventable. To combine SOD-based therapeutics with other cancer preventive agents to obtain synergistic effects. To formulate a dietary supplementation-based antioxidant approach for cancer prevention. Lastly, targeting specific populations who are prone to carcinogens, which can trigger oxidative stress as the mechanism of carcinogenesis.

Chemopreventive potential of piperine in 7,12-dimethylbenz[a]anthracene-induced skin carcinogenesis in Swiss albino mice

The chemopreventive potential of orally administered piperine was studied in Swiss albino mice against 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin carcinogenesis. The mechanistic pathway for the chemopreventive potential of piperine was evaluated by analysing the status of phase I and phase II detoxification agents, lipid peroxidation by-products and antioxidants during DMBA-induced skin carcinogenesis. Skin squamous cell carcinoma was induced in the shaved back of mice, by painting with DMBA (25μg in 0.1ml acetone/mouse) two times weekly for 8 weeks. We observed severe hyperplasia, dysplasia, and well-differentiated squamous cell carcinoma in the 8th, 10th and 15th week of experimental period respectively in mice treated with DMBA alone. Marked alterations in the status of phase I and phase II detoxification agents, lipid peroxidation by-products and antioxidants were observed in tumor bearing mice. Oral administration of piperine (50mgkg(-1) body weight) by gastric gavage significantly prevented the formation of skin tumors during DMBA-induced mouse skin carcinogenesis. Also, piperine administration brought back the status of phase I and phase II detoxification agents, lipid peroxidation by-products and antioxidants to near normal range in DMBA treated mice. The present study thus demonstrates that piperine has significant suppressing effect on cell proliferation during DMBA-induced mouse skin carcinogenesis. The chemopreventive potential of piperine is probably due to its modulating effect on the status of lipid peroxidation, antioxidants and detoxification agents during DMBA-induced skin carcinogenesis.

Role of synthesized organoselenium compounds on protection of rat erythrocytes from DMBA-induced oxidative stress

Formation of free radicals is not limited to normal cellular process but also occur upon exposure to certain chemicals (polycyclic aromatic hydrocarbon, cadmium, lead, etc.), cigarette smoke, radiation, and high-fat diet. Free-radical damage is an important factor in many pathological and toxicological processes. Selenium, an essential micronutrient, is a associated with antioxidant functions, physiological defense mechanisms against different diseases including several types of cancers. Search for new selenium compounds with more chemopreventive activities and less toxicities are in progress. In addition, there has been a growing interest in the synthesis of organoselenium compounds with respect to their use in enzymology and bioorganic chemistry. In the present study, adult female Wistar rats were treated with 7,12-dimethylbenz[a]anthracene (DMBA) and the organoselenium compounds [1-isopropyl-3-methylbenzimidazole-2-selenone (Se I) and 1, 3-di-p-methoxybenzylpyrimidine-2-selenone (Se II)] in determined doses. The protective effects of synthetic organoselenium compounds (Se I and Se II) against DMBA-induced changes in antioxidant enzyme (superoxide dismutase, glutathione peroxidase (GSH-Px), catalase (CAT), glutathione reductase (GR)) activities, total GSH, and malondialdehyde (MDA) levels of rat erythrocyte were investigated. The DMBA-treated group exhibited significant decreases in the levels of erythrocyte GSH-Px, CAT, and GR activities, an increase in MDA levels, and a decrease in total GSH level compared to the control. Se I and Se II fully or partially restored enzyme activity. Lipid peroxidation was also decreased in Se-I- and Se-II-treated groups.

Antioxidative effects of novel synthetic organoselenium compound in rat lung and kidney

The effects of environmental chemicals, drugs, and physical agents on the developing lung and kidney are influenced by the state of development and maturation. Selenium is an essential element with physiological nonenzymatic antioxidant properties. Therefore, we undertook the present study to evaluate the antioxidant potential of the novel synthetic organoselenium compounds (Se I and Se II). In this study, adult female Wistar rats were treated with DMBA and the novel organoselenium compounds [1-isopropyl-3-methylbenzimidazole-2-selenone (Se I) and 1,3-di-p-methoxybenzylpyrimidine-2-selenone (Se II)] in the determined doses. The protective effects of novel synthetic organoselenium compounds (Se I and Se II) against DMBA-induced changes in levels of some [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities and total glutathione (GSH), malonedialdehyde (MDA)] parameters in rat lung and kidney were investigated. As a result, it was found that both Se I and Se II had provided the antioxidant effects against DMBA-induced oxidative stress in rat lung and kidney and lipid peroxidation had also been decreased by these organoselenium compounds.

Chemoprotection and enhancement of cancer chemotherapeutic efficacy of cyclophosphamide in mice bearing Ehrlich ascites carcinoma by diphenylmethyl selenocyanate

PURPOSE

Chemoprotective effect of diphenylmethyl selenocyanate against cyclophosphamide (CP) induced cellular toxicity and antitumor efficacy was evaluated in mice bearing Ehrlich ascites carcinoma.

METHODS

Diphenylmethyl selenocyanate (3 mg/kg.b.w.) was administered orally and CP was given intraperitoneally (25 mg/kg.b.w). The effects were observed on the level of lipid peroxidation, antioxidant enzymes status, serum transaminase (ALT, AST) activity, hematological profile, transplantable murine tumor growth, apoptosis induction in tumor cells, and life span of tumor bearing hosts.

RESULTS

The selenium compound restored the levels of antioxidant enzymes system, decreased the level of lipid peroxidation and serum transaminase activity. Hematological profile reverted to near normal level after selenium compound treatment. Treatment with the selenium compound also resulted in significant tumor growth regression along with significant upregulation of apoptosis, increased in mean survival time and life span of tumor bearing host.

CONCLUSIONS

Results clearly indicate that diphenylmethyl selenocyanate has the potential to reduce the cellular toxicity of CP at the same time improving its antitumor efficacy.

The effect of green tea on oxidative damage and tumour formation in Lobund-Wistar rats

A number of epidemiological studies suggest that the consumption of green tea reduces the incidence of prostate cancer. As the major catechins present in green tea are potent antioxidants, we hypothesized that genetic and cellular damage induced by oxygen free radicals could be significantly reduced by potent antioxidants in green tea, thus reducing the cumulative genetic and cellular damage with age, and slowing or preventing tumour formation. Long-term administration of a decaffeinated green tea extract to Lobund-Wistar rats for periods up to 26 months almost halved the incidence of primary tumours in the genitourinary tract when compared with an age-matched cohort receiving just water. We observed no inhibition of DNA adduct formation or lipid peroxidation in animals consuming green tea compared with animals consuming deionized water. The decrease in tumour formation was associated with an increase in 8-hydroxy-2'deoxyguanosine and 4-hydroxynonenal content (markers of DNA adduct formation and lipid peroxidation, respectively) in the epithelium of the ventral prostate in aging animals. In addition, there was an increase in 8-hydroxy-2'deoxyguanosine expression, but no change in 4-hydroxynonenal expression in the seminal vesicles of older animals. An age-associated increase in expression of the antioxidant enzymes manganese superoxide dismutase and catalase in the epithelium of the ventral prostate of aging animals was observed. Furthermore, there was also an increase in manganese superoxide dismutase expression, but no change in catalase expression in the seminal vesicles of older animals. These data demonstrate that consumption of green tea decreases the incidence of genitourinary tract tumours in the Lobund-Wistar rat, but has no effect on age-associated DNA adduct formation and lipid peroxidation in the ventral prostate and seminal vesicles of the aging rat.

Mechanism of selenium-induced inhibition of arsenic-enhanced UVR carcinogenesis in mice

BACKGROUND

Hairless mice that ingested arsenite in drinking water exhibited more than a 5-fold enhancement of ultraviolet radiation (UVR) carcinogenesis, whereas arsenite alone was carcinogenically inactive. Dietary organoselenium blocked the cancer enhancement effect of arsenic but not cancer induction by UVR.

OBJECTIVE

In this study we sought to explain selenium blockage of As enhancement by establishing the extent that As and Se tissue distributions are coincident or divergent.

METHODS

We used the X-ray fluorescence microprobe at the Advanced Photon Source (Argonne National Laboratory) to probe sections of skin and liver from hairless mice exposed to a) UVR, b) UVR + As, c) UVR + organoselenium, or d) UVR + As + organoselenium.

RESULTS

We found elevated levels of As in the skin epithelium (hair follicles and epidermis) and diffusely in the liver of mice exposed to UVR + As. Arsenic was entirely absent in skin in mice exposed to UVR + As + organoselenium, but a diffuse low level was seen in the liver. As and Se locations were consistently divergent in skin; As was more diffusely distributed, whereas Se was strongly associated with membranes. X-ray absorption near-edge spectra are consistent with the presence of the seleno-bis(S-glutathionyl) arsinium ion in the liver.

CONCLUSIONS

Supplemental Se was uncommonly effective at preventing even a trace of As in skin at 14 or 196 days of continuous exposure to As in drinking water. Traces of the seleno-bis(S-glutathionyl) arsinium ion in the liver suggested that formation of this compound was more likely to be responsible for the As-blocking effect of Se than was a mechanism based on antioxidation.

The Investigation of the Antioxidative Properties of the Novel Synthetic Organoselenium Compounds in Some Rat Tissues

DMBA (7,12-dimethylbenz[a]anthracene) is a polycyclic aromatic hydrocarbon (PAH) known to cause tumors in rats. Selenium is an essential element with physiological non-enzymatic antioxidant properties. Because of the health problems induced by many environmental pollutants, many efforts have been undertaken in evaluating the relative antioxidant potential of selenium and synthetic organoselenium compounds. In this study, adult female Wistar rats were treated with DMBA and the novel organoselenium compounds (1- isopropyl-3-methylbenzimidazole-2-selenone [SeI] and 1,3-di- p-methoxybenzylpyrimidine-2-selenone [SeII]) in the determined doses. The protective effects of novel synthetic organoselenium compounds (SeI and SeII) against DMBA-induced changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities and total glutathione (GSH) and malone-dialdehyde (MDA) levels of rat heart and brain were investigated. It was determined that SeI and SeII fully or partially restored enzyme activity. It was also found that lipid peroxidation was also decreased in SeI and SeII treated groups. Consequently, it was determined that novel synthetic organoselenium compounds (SeI and SeII) provided protection of antioxidant activity, and protection against lipid peroxidation measured as MDA in SeI and SeII treated groups was provided by novel synthesized organoselenium compounds. The ability of the organoselenium compounds to prevent oxidative damage induced by DMBA in rats was rationalized.

Protective effect of diphenylmethyl selenocyanate against CCl4-induced hepatic injury

Organoselenocyanates represent an important class of chemopreventive agent, which possess antioxidative, antimutagenic as well as cancer chemopreventive properties. The present study is an attempt to evaluate the protective effect of diphenylmethyl selenocyanate -- a synthetic organoselenocyanate against carbon tetrachloride (CCl(4))-induced hepatic damage in Swiss albino mice in vivo. Mice were pretreated with the Se-compound orally in a duration dependent manner (7 and 15 days) to observe its protective action against an acute toxic dose (24 h) of CCl(4) (single injection at a dose of 20 microl and 50 microl kg(-1) b.w.) that induced hepatic necrosis and caused DNA damage (strand breaks) in the hepatocytes. This study revealed that pretreatment with the Se-compound reduced the extent of massive hepatic necrosis in a duration dependent manner, but it had no modulatory effect on hepatocellular apoptosis caused by acute toxic doses of CCl(4). It was also found that the Se-compound could significantly (P < 0.01) prevent the CCl(4)-induced elevation of DNA damage in hepatocytes measured by comet assay in a duration dependent manner. So these findings will further strengthen the view that organoselenocyanate is an effective chemopreventive agent against acute hepatic damage, caused by halogenated alkanes such as CCl(4).

Diphenyl diselenide supplementation delays the development of N-nitroso-N-methylurea-induced mammary tumors

The effect of dietary diphenyl diselenide (1 ppm) on N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis was examined in female Wistar rats. Beginning at 5 weeks of age, the animals were fed with either control or diphenyl-diselenide-supplied diets until the end of the study (210 days). At 50 days of age, mammary tumor was induced by the administration of three doses of NMU (50 mg/kg body wt, intraperitoneally) once a week for 3 weeks. In experimental trials, latency to tumor onset was extended in rats fed with diet supplemented with diphenyl diselenide (P < 0.05). The incidence and frequency of tumors were significantly small in animals supplemented with diphenyl diselenide. However, the multiplicity of tumors was not altered by dietary diphenyl diselenide. Diphenyl diselenide supplementation also restored superoxide dismutase (SOD) activity and vitamin C levels altered in the NMU group (P < 0.05). Our results suggest that diphenyl diselenide can be considered a chemopreventive agent, even when supplemented at a relatively low concentration.

Prevention of cadmium induced lipid peroxidation, depletion of some antioxidative enzymes and glutathione by a series of novel organoselenocyanates

A series of organoselenocyanate compounds 4a-d were synthesized utilizing 1,8-naphthalic anhydride as the building unit. To evaluate the preventive potential of the Se compounds against Cd induced hepatic lipid peroxidation and oxidative stress, female Swiss Albino mice were exposed to Cd (as CdCl(2)) during 20 days at a dose of 1 or 2mg/kg bw given ip and the selenium compounds were given at the dose of 3mg/kg bw orally in a pretreatment and concomitant treatment schedule. Hepatic lipid peroxidation level was increased significantly by Cd, whereas the glutathione-S-transferase (GST), superoxide dismutase(SOD), reduced glutathione(GSH) and catalase(CAT) levels were decreased. The selenium compounds effectively decreased the hepatic lipid peroxidation level of the animals treated with Cd. The compounds were also effective in restoring the GST, SOD, and GSH as well as CAT level towards normal. Cadmium induced enhanced Serum alanine aminotransferase (ALT) and aspertate aminotransferase (AST) level were also decreased by the selenium compounds. The study evidences the preventive effects of organoselenocyanates 4a-d (Scheme 1) against Cd induced lipid peroxidation and oxidative stress, 4d showing the highest activity.

Hepatic chemoprotective enzyme responses to 2-substituted selenazolidine-4(R)-carboxylic acids

In epidemiology and human supplementation studies, as well as many animal models, selenium has shown antitumorigenic activity. The mechanism of action, however, has not been satisfactorily resolved. Selenium supplementation affects many enzymes in addition to those where selenocysteine is an essential component. Such enzymes include cytoprotective detoxifying enzymes, and the regulation of these enzymes by a set of 2-substituted selenazolidine-4(R)-carboxylic acids (SCAs) has been investigated. Following seven consecutive daily doses of these prodrugs of L-selenocysteine, changes in hepatic enzyme activities and/or mRNA levels of glutathione transferase (GST), microsomal epoxide hydrolase (mEH), NAD(P)H-quinone oxidoreductase (NQO), UDP-glucuronosyltransferase (UGT), glutathione peroxidase (GPx), and thioredoxin reductase (TR) have been observed. Among the enzymes examined, UGTs and GPx were found to be the least affected. Among the compounds, 2-oxoSCA produced the most changes and 2-phenylSCA produced the least, none. For no two compounds was the pattern of changes identical, and for a single compound, few changes were reproduced in common by the two routes of administration investigated. In general, more changes were elicited following intraperitoneal (i.p.) administration than with the intragastric (i.g.) route. This dominance was typified by 2-butylSCA and 2-cyclohexylSCA where enzyme activity elevations (TR and mEH with both, NQO with 2-butylSCA) were seen only with the i.p. route. With 2-oxoSCA, however, GST, TR, and NQO activities were found to be elevated independent of route. Only with GST (both routes) and TR (i.p. route), elevations in mRNAs accompanied the 2-oxoSCA elicited elevations of activities at the time of sacrifice. For some enzymes, most notably mEH with compounds administered i.p., elevations in mRNAs were not manifest as increased enzyme activity. Thus, although constituting a closely related series of compounds, each 2-substituted SCA produced its own unique pattern of changes, and for most members, changes were predominant following i.p. administration.

Inhibition of DMBA Induced Rat Mammary Duct Damage by Novel Synthetic Organoselenium Compounds

The balance between prooxidants and antioxidants is crucial to the survival and functioning of aerobic organisms. Partially reduced derivatives of oxygen, which are produced in aerobic organisms as part of normal physiological and metabolic processes, are toxic species, oxidizing numerous biomolecules, which initiate tissue injury and cell death. DMBA (7,12-dimethylbenz[a]anthracene) is a polycyclic aromatic hydrocarbon (PAH) known to cause tumors in rats. DMBA is known to generate DNA-reactive species, which may enhance oxidative stress in cells, during its metabolism. Besides the formation of DNA adducts, oxidative products derived from mutagen metabolism, such as DMBA, might impair vital cellular functions by damaging proteins and lipid membranes. Synthetic organoselenium compounds inhibit the initiation phase of carcinogenesis by inhibiting DMBA-DNA adduct formation in the target organ in vivo. Because of the health problems induced by many environmental pollutants, many efforts have been undertaken to evaluate the relative antioxidant potential of selenium and synthetic organoselenium compounds. We undertook the present study to evaluate the chemopreventive potential of the novel synthetic organoselenium compounds (1-isopropyl-3-methylbenzimidazole-2-selenone (SeI) and 1,3-di-p-methoxybenzylpyrimidine-2-selenone (SeII)) in the well-established DMBA-treated rat model by monitoring the extent of lipid peroxidation and mammary duct damage. In this study, adult female Wistar rats were treated with DMBA and the novel organoselenium compounds (SeI and SeII) in determined doses. In DMBA-treated rats, the effects of the organoselenium compounds on malondialdehyde (MDA) levels and histological changes in the rat mammary lactiferous duct were studied. The ability of the organoselenium compounds to prevent oxidative damage induced by DMBA in rat mammary ducts was demonstrated. Protection against lipid peroxidation measured as MDA in the SeI and SeII treated groups was provided by the novel synthesized organoselenium compounds. SeI and SeII both provided chemoprevention against DMBA-induced oxidative stress in the rat mammary duct.

Synthesis and evaluation of antioxidative properties of a series of organoselenium compounds

A series of organoselenocyanate compounds 4a-d were synthesized utilizing 1,8-naphthalic anhydride as the building unit. These compounds were evaluated for their antioxidative activities against DMBA-PMA-induced oxidative stress in a two-stage mouse skin carcinogenic model. Compound 4d was found to have the maximum antioxidative property in comparison with the other compounds. Also, the pretreatment group showed better results than the concomitant treatment groups.

Diphenylmethyl selenocyanate inhibits DMBA–croton oil induced two-stage mouse skin carcinogenesis by inducing apoptosis and inhibiting cutaneous cell proliferation

Numerous epidemiological and experimental studies have showed the inverse relationship between dietary selenium intake and different types of cancer. Continuous efforts are going on to develop suitable organoselenium compounds, which can be used as cancer chemopreventive agents for human. In the present study, a synthetic organoselenium compound diphenylmethyl selenocyanate was evaluated for its ability to arrest cell proliferation and to induce apoptosis against 7,12-dimethylbenz[a]anthracene-croton oil induced two-stage mouse skin carcinogenesis model. Reduction in the incidence and number of papilloma, the preneoplastic lesion, was considered to be the mean of assessment. Significant decrease in the level of cell proliferation (p<0.01) and significant enhancement in the level of apoptosis (p<0.01) were found. Caspase-3, which contribute a part in the process of cellular apoptosis to prevent further cellular differentiation was also elevated significantly (P<0.01) during the treatment with the Se compound. These observations seem to be correlated with the significant reduction in the corresponding number of skin papilloma formation after 12 weeks of experiment. Thus the compound, diphenylmethyl selenocyanate may be considered for further research to establish it as an effective cancer chemopreventive agent.