Treatment of canine haemangiosarcoma with suberoylanilide hydroxamic acid, a histone deacetylase inhibitor.

A case report is presented by describing the treatment of a 12-year-old dog - diagnosed with haemangiosarcoma (HSA) - with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor. The drug was administered orally, on a daily basis, approximately 2 weeks post-splenectomy at a dose of 3 mg kg(-1). HSA is a lethal malignancy of the endothelium, which is usually disseminated by the time it is diagnosed. Median survival time, usually, is no longer than 80 days. Following treatment with SAHA, no sign of malignant growth could be discerned by means of diagnostic abdominal ultrasound, chest X-ray or with the help of clinical symptoms, over a period of >1000 days. The precise mechanism by which HDAC inhibitors exert their anti-cancer effects is uncertain, but evidence suggests that exposure to SAHA generates hyperacetylated chromosomal histones, which, in turn, facilitates the expression of tumour suppressor genes turned off by epigenetic mechanisms during neoplastic transformation of the endothelium.

Effect of soy protein isolate and conjugated linoleic acid on the growth of Dunning R-3327-AT-1 rat prostate tumors.

BACKGROUND: Epidemiologic and animal model studies suggest that consumption of soy isoflavones may be associated with reduced risk of prostate cancer (PC). In addition, animal model studies suggest that conjugated linoleic acid (CLA), a natural positional isomer of linoleic acid, inhibits tumor growth in various models, including models of PC. METHODS: Based on the above-mentioned data, the objective of the present study was to test the hypothesis that supplementation of the diet with combinations of isoflavone-rich soy protein isolate and CLA would act to inhibit the growth of androgen-independent R-3327-AT-1 rat prostate tumor cells inoculated ectopically into male Copenhagen rats. RESULTS: The results of this study indicate that neither an isoflavone-rich soy protein isolate (SPI), nor CLA inhibit the in vivo growth and development of prostate tumor cells when administered in the diet either singly or in combination. Moreover, at the highest concentrations SPI and CLA (i.e., 20% SPI, 1% CLA), there was a statistically significant increase in tumors volume over controls. Administration of SPI at 10% in the diet also enhanced tumor growth, whereas at 5%, SPI exerted no measurable effect. CLA administration alone had no observable effects on AT-1 tumor growth. CONCLUSION: These results, in an established rat model, suggest caution in using isoflavone-rich SPI in human studies involving advanced hormone-refractory prostate cancer until further investigation of these effects are completed.

LAS, a novel selective estrogen receptor modulator with chemopreventive and therapeutic activity in the N-nitroso-N-methylurea-induced rat mammary tumor model.

The N-nitroso-N-methylurea-induced rat mammary tumor model was used to conduct two types of studies: a prevention study designed to test the ability of the novel selective estrogen receptor modulator lasofoxifene (LAS) to inhibit the development of mammary tumors, and a treatment study designed to test the inhibitory effect of LAS on the growth of established tumors. The prevention study indicated that LAS markedly delayed the emergence of N-nitroso-N-methylurea-induced tumors to an extent similar to that obtained by the established antiestrogen tamoxifen (TAM). At the highest dose administered, both TAM and LAS reduced tumor incidence by 75% and total tumor number by 90% relative to the controls. LAS also reduced the multiplicity of tumors, i.e., the mean number of tumors per rat, and resulted in substantially smaller total tumor burden. In the treatment study, LAS significantly inhibited tumor growth compared with the controls. In addition, whereas none of the untreated tumors regressed completely over the experimental period, 40% of LAS-treated tumors regressed by >50% at the highest dose (10 mg/kg daily). The results of this study in a rat mammary tumor model indicate that LAS has both chemopreventive and chemotherapeutic effects quantitatively comparable with those of TAM.

Feeding thiol-containing compounds, derived from vegetables, fails to inhibit N-methylnitrosourea-induced mammary tumorigenesis.

Various thiol-containing compounds have been shown to inhibit chemically-induced tumors in animal models. Two thiol-containing compounds derived from vegetables, namely 1,2 dithiol-3-thione (DTT) and S-methylmethane thiolsulfonate (MMTS), were tested for their chemopreventive activity in the N-methylnitrosourea (NMU)-induced rat mammary tumor model. Each compound was incorporated into the grain-based Teklad 7001 diet and fed to the rats one week prior to initiation with NMU until termination 18 weeks post NMU. DTT was fed at 166 and 500 ppm and MMTS at 200 and 800 ppm. Neither compound exerted a significant inhibitory effect on any index of tumor development including incidence, total tumor, tumor multiplicity, volume or latency. Serum levels of DTT assessed at termination in the 500 ppm DTT group ranged from 10-30 microg/ml. MMTS was undetectable in serum from either MMTS-fed group. The results of this study, using the direct acting carcinogen, NMU, suggest that the chemopreventive effect of thiol-containing compounds may be confined to animal models using carcinogens that require host activation.

Effects of a lycopene-rich diet on spontaneous and benzo[a]pyrene-induced mutagenesis in prostate, colon and lungs of the lacZ mouse.

Consumption of lycopene has been associated with reduced risk of prostate cancer. We have investigated the effects of lycopene, fed as a lycopene-rich tomato oleoresin (LTO) at two doses, on in vivo mutagenesis in prostate, colon, and lungs of lacZ mice. Both short-term benzo[a]pyrene (BaP)- induced and long-term spontaneous mutagenesis were monitored. Non-significant inhibition of spontaneous mutagenesis in prostate and colon was observed at the higher dose of LTO, and the observation of inhibition in colon was facilitated by an unusually high spontaneous mutagenesis rate. BaP-induced mutagenesis was slightly inhibited by LTO in prostate. However, enhancement of BaP-induced-mutagenesis was observed in colon and lung. These results indicate that any antimutagenic effects of LTO may be organospecific.

Preventive potential of wheat bran fractions against experimental colon carcinogenesis: implications for human colon cancer prevention.

Epidemiological studies suggest an inverse relationship between the intake of dietary fiber, particularly fiber from cereal grains, and colon cancer risk. Animal model assays have demonstrated that the protective effects of dietary fiber on colon cancer development depend on the nature and source of the fiber. Wheat bran (WB) appears to inhibit colon tumorigenesis more consistently than do oat bran or corn bran. This study was designed to determine whether specific WB fractions such as WB fiber, WB lipids, or phytic acid differentially affect colon carcinogenesis in a well-established colon cancer model. In addition, the modulating effect of specific fractions of WB on the activities of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-1 and COX-2 enzymes were assessed in colon tumors as those have been shown to play a role in tumor progression. At 5 weeks of age, groups of male F344 rats were assigned to one of six diets: a high-fat diet containing 10% WB (control diet) and experimental high-fat diets containing 10% dephytinized WB (WB-P), 10% defatted WB (WB-F), 10% dephytinized and defatted WB (WB-PF), 10% WB-PF fortified with 2% bran oil and/or with 0.4% phytate. At 7 weeks of age, all eats except those in the vehicle-treated groups were given two weekly s.c. injections of azoxymethane (AOM) at a dose rate of 15 mg/kg body weight/week. They continued to receive their respective diets until 50 weeks after carcinogen treatment and were then killed. Colon tumors were analyzed for iNOS, COX-1, and COX-2 expression and enzymatic activities. Colon tumors were evaluated histopathologically and classified as adenomas and adenocarcinomas. We found that removal of phytic acid (WB-P) or lipids (WB-F) from WB had no significant effect on colon tumor incidence (% animals with tumors) or multiplicity (tumors/ animal), whereas removal of both phytate and lipids from WB (WB-PF) significantly increased colon tumor multiplicity and volume. Interestingly, WB-PF fortified with excess bran oil or with bran oil plus phytate significantly inhibited colon tumor incidence, multiplicity, and volume; but supplementation of WB-PF with phytate alone had no significant effect on colon tumorigenesis in rats suggesting that lipid fraction of WB possesses tumor-inhibitory properties. Moreover, feeding WB-PF diet significantly increased iNOS, total COX and COX-2 enzyme activities, and iNOS protein expression in colon tumors as compared with wheat bran control diet. Feeding the WB-PF that was fortified with excess bran oil alone or with bran oil plus phytate significantly suppressed the activities of iNOS and COX-2 as well as the expression of iNOS and COX-2 in colon tumors compared with that in rats fed the WB diet or WB-PF diet. The study demonstrates for the first time that the lipid fraction of wheat bran has strong colon tumor inhibitor properties. The exact mechanism(s) by which the lipid fraction of WB inhibits colon carcinogenesis in addition to alteration of iNOS and COX activities remains to be elucidated. Additional studies are warranted to identify biologically active constituents of lipid fraction of WB and their relative role in colon tumor inhibition.

The influence of different varieties of olive oil on N-methylnitrosourea(NMU)-induced mammary tumorigenesis.

Several epidemiological and animal model studies suggest that consumption of olive oil, which is rich in the monounsaturated fatty acid, oleic acid (OA, C18:, n-9) may reduce the risk of breast cancer. There are however, a wide variety of olive oils in the marketplace with levels of OA ranging from a low of 50% to a high of 80% OA. The purpose of this rodent model study was to determine whether the level of OA in olive oil is a key determinant of its protective effects. We compared the inhibitory effects among three different types of olive oil containing 54, 70 and 80% OA and 20, 15 and 5% linoleic acid (LA), respectively, corn oil and a store bought olive oil, using the NMU-induced rat mammary tumor model. While little difference was found in total mammary tumor yields, a differential effect was found in the histological type of tumors formed. Olive oil containing 80% OA and 5% LA exhibited the lowest level of adenocarcinomas and the highest level of the more benign adenocarcinoma arising from within a fibroadenoma. While the reasons for this effect remain to be clarified, these results suggest that future studies on the health benefits of olive oil should take into account the type as well as the amount of olive oil.

Effect of intact and isoflavone-depleted soy protein on NMU-induced rat mammary tumorigenesis.

Experiments in animal models of carcinogenesis suggest that soy consumption decreases tumor number and incidence. Genistein, an isoflavone which is present in soy at high concentrations, has been considered to be the primary antitumor constituent in soy. In the present study, the N-nitroso-N-methylurea (NMU)-induced mammary tumor model was used as a means to determine whether the chemopreventive effect of soy was attributable specifically to its high content of isoflavones. Five groups of rats (30/group) were fed the following modified AIN-93G diets: group 1, 20% intact soy protein (SP); group 2, 10% SP; group 3, 20% isoflavone-depleted soy protein (IDSP); group 4, 10% IDSP; group 5, the casein-based AIN-93G diet. The SP contained 1.07 and IDSP 0.073 mg genistein/g isolate, respectively. Experimental diets were initiated 1 week prior to NMU administration (at 50 days of age) and continued for another 18 weeks. No significant differences were found among the five groups when assessed in terms of tumor incidence, latency, multiplicity or volume. A trend towards inhibition was observed in both the 20 and 10% SP and IDSP groups when assessed in terms of total tumors/group, tumor volume and latency, but this trend did not achieve statistical significance. The results of this model study do not support the hypothesis that the isoflavone components of soy protein, or soy protein itself, inhibit chemically induced mammary tumor development.

Effect of dietary lycopene on N-methylnitrosourea-induced mammary tumorigenesis.

Epidemiological studies suggest protective effects of lycopene-rich foods on several types of cancer, including prostate and gastrointestinal tract. Moreover, an inverse association between serum lycopene concentrations and several types of cancer has been reported. However, few studies have focused on breast cancer, and they have shown little association between lycopene consumption and cancer risk. In this report, we used the N-methylnitrosourea (NMU)-induced rat mammary tumor model to compare the effects of pure lycopene with a lycopene-rich tomato carotenoid oleoresin (TCO) on NMU-induced mammary tumorigenesis. Rats were fed diets supplemented with 250 and 500 ppm crystalline lycopene or TCO beginning seven days before initiation with NMU (55 days of age) to termination (18 wk after NMU). Neither pure lycopene nor lycopene in the form of a mixed carotenoid oleoresin exerted an inhibitory effect on tumor incidence, latency, multiplicity, volume, or total tumors per group compared with unsupplemented controls. Weight gains in all groups were similar. Assay of serum lycopene concentrations in lycopene-supplemented groups indicated that median levels of 7,12,60, and 87 ng/ml were attained in blood of groups supplemented with 250 and 500 ppm lycopene and 250 and 500 ppm TCO, respectively. The results of this animal study are consistent with epidemiological reports indicating that lycopene does not protect against breast cancer.

Inhibition by dietary menhaden oil of cyclooxygenase-1 and -2 in N-nitrosomethylurea-induced rat mammary tumors.

Studies in laboratory animals and epidemiological surveys suggest a relationship between the type and amount of dietary fat and mammary cancer. One mechanism proposed to explain this relationship is modulation by dietary fat, of mammary tumor eicosanoid levels through action at the rate limiting enzyme in eicosanoid synthesis, cyclooxygenase (COX). Until recently there have been no studies which have examined COX gene expression in human breast or rodent mammary tissues. In this study we have demonstrated the presence of two immunoreactive isoforms of cyclooxygenase (COX-1 and -2), and the modulating effects of n-3 fatty acids on their expression, in N-nitrosomethylurea (NMU)-induced rat mammary tumors. Three different high fat diets were compared namely, corn oil (CO) 23%; CO 18% menhaden oil (MO) 5%; CO, 5%/MO 18%; low fat corn oil (5%) served as a control. It was found that immunoreactive COX-2 protein levels were approximately 3x higher than COX-1 levels in NMU-induced mammary tumors. Moreover, the high menhaden oil diet (rich in n-3 fatty acids) significantly suppressed both COX-1 (-28%) and COX-2 (-36%) protein levels when compared to the high corn oil diet. No differences were found among the other treatment groups when compared pair-wise or with low-fat control. The mechanism(s) by which n-3 fatty acids suppress COX-1 and COX-2 remain to be determined.

Dietary fiber and breast cancer.

The Fiber Hypothesis which had its origins in the work of Burkitt and others in the early 1970's, focussed largely on fiber's beneficial effects on colon cancer and disorders of the gastric intestinal tract. In the 1980's it was proposed that fiber may also have beneficial effects on breast cancer and a rational for this was proposed involving modulation, by fiber, of the enterohepatic recirculation of estrogens. In the following the evidence from epidemiology, clinical interventions and animal model studies, supporting a role for fiber in breast cancer is critically reviewed. Evidence from animal model studies support the notion that supplementary fiber inhibits chemically-induced mammary tumorigenesis but do not support an estrogen-based mechanism. Some studies in human populations suggest modulation by estrogens and some do not. The aggregate data point to minor constituents present in fiber, such as isoflavones and phytate as the biologically active components of fiber which may be responsible for its anti cancer effects.

Oral enzyme therapy and experimental rat mammary tumor metastasis.

Although there has been much interest over the years in the medical use of orally administered proteolytic enzymes, there is considerable controversy about their efficacy against advanced stages of cancer. In light of this, the goal of the present study was to assess the inhibitory effects of different doses of an orally administered porcine pancreas preparation on the growth and metastasis of the R13762 transplantable rat mammary tumor. Five groups of 12 F-344 female retired breeders were inoculated orthotopically with a 2mm3 tumor implant and placed on the following diets: (1) AIN-76A diet + 20% porcine pancreas preparation (PPP); (2) AIN-76A + 20% PPP + 10 mg Mg citrate/rat/day; (3) AIN-76A + 2% PPP; (4) AIN-76A + 2% PPP + 10 mg Mg citrate and (5) AIN-76A only (control). Primary tumor development was monitored for 40 days and following sacrifice, lungs were excised, stained and metastatic foci quantitated. Metastatic foci were sorted into 3 groups based on their radii: small (<1mm), medium (1-3mm) and large (>3mm), and volumes calculated. The oral enzyme preparation had no effect on primary tumor growth or on body weight change over the duration of the study. The percent (incidence) of rats with pulmonary metastases among the five groups were not significantly different. However, among the three size categories of pulmonary foci, decreased incidence was found only in the large (>3mm) volume subset of the 2% PPP group supplemented with Mg++. When assessed in terms of mean number of pulmonary foci/rat, the 20% PPP group exhibited the highest and controls the lowest frequency with the important exception of the 2% PPP + Mg++ group (large volume) which exhibited the lowest frequency of all treatment groups. In general, the presence of Mg++ resulted in marked decreases in mean number of pulmonary foci/rat compared to groups fed PPP without the Mg++ supplement. Similar results were obtained when foci were quantitated in terms of metastatic volume rather than frequency. The results of this laboratory animal study suggest that to show effective inhibition of metastatic dissemination of the R13762 tumor by PPP, lower doses of PPP and larger numbers of animals, to account for the high variability in the model, will be required.

Oral health knowledge, practices, and status among outpatient veterans at the VA Maryland Health Care System.

Poor oral health can have a significant impact on overall health and quality of life. Yet few studies have established the oral health needs of outpatient veterans. The purpose of this study was to assess the oral health knowledge and practices, the dental status, and the periodontal treatment needs of outpatient veterans seeking primary care services at a statewide healthcare system. Veterans were interviewed and received an oral examination by a trained examiner using NIDCR criteria for dental caries detection and the Community Periodontal Index of Treatment Needs (CPITN). The mean age of the study participants' (n = 135) was 57.7 (SD = 14.1) years. Ninety-five percent of the sample was male and 44% African-American. Untreated coronal and root caries was present in 57% and 36% of veterans, respectively. Sixty-nine participants received the periodontal examination, with 29% of them in Category III. An interpretation of these findings shows a high need for preventive and restorative oral health care among outpatient veterans receiving primary services in an integrated and comprehensive VA health care system.

Chemoprevention of carcinogen-induced mammary tumorigenesis by the hybrid polar cytodifferentiation agent, suberanilohydroxamic acid (SAHA).

Hybrid Polar Cytodifferentiation (HPC) agents represent a novel class of anticancer compounds which act by inducing terminal differentiation and/or apoptosis rather than by cytotoxic action. Among these are HPC agents such as hexamethylenebisacetamide (HMBA) and more potent 2nd generation hybrid/polar compounds such as suberanilohydroxamic acid (SAHA). As of the present, most studies on HPC agents have focused on cancers of the hematopoietic system rather than solid epithelial tumors. The objective of the present study therefore was to assess the chemopreventive action of these two related compounds in the N-methylnitrosourea (NMU)-induced rat mammary tumor model. Female Sprague-Dawley rats were fed diets containing 450 and 900 ppm, SAHA and 1000 and 2000 ppm HMBA, starting one week prior to NMU administration and continued for a period of 18 weeks. Mammary tumor development was monitored by palpation throughout the study, and at termination tumor incidence, number, multiplicity, latency and volume were determined. Weight gain was measured biweekly throughout the study. The salient results were as follows: SAHA at 900 ppm reduced NMU-induced mammary tumor incidence by 40%, total tumors by 66%, mean tumor multiplicity by 43% and mean tumor volume by 78%, with no detectable toxic side effects. HMBA exerted no tumor inhibiting effects at either concentration. This study represents the first demonstration that an HPC agent, namely SAHA, can inhibit the development of a chemically-induced, solid, epithelial tumor, at a relatively low dose (approximately 13 mgs/rat/day) without untoward side effects.

S-allylcysteine, a garlic constituent, fails to inhibit N-methylnitrosourea-induced rat mammary tumorigenesis.

Epidemiological and experimental studies suggest that consumption of garlic may protect against several types of cancer. Moreover, a plausible hypothesis has been proposed that the biological effects of garlic can be attributed to the enhancing action of a variety of organosulfur compounds, present in garlic, on hepatic phase II carcinogen detoxification enzymes. We have used the N-methylnitrosourea (NMU)-induced rat mammary tumor model to test the chemopreventive effects of a water-soluble organosulfur constituent derived from aged garlic, S-allylcysteine (SAC). Rats were fed diets supplemented with 666 and 2,000 ppm SAC beginning seven days before initiation with NMU (55 days of age) to termination (18 wk post-NMU), at which time mammary tumors were enumerated. At neither dose did SAC exert an inhibitory effect on any index of tumor development, including incidence, latency, multiplicity, or volume, compared with untreated controls. Weight gains in all groups were similar. Assay of serum SAC levels in supplemented groups indicated that SAC concentrations were beneath the limits of detection of the high-performance liquid chromatography system used. These results contradict previous animal model studies indicating that SAC acts as an inhibitory agent in experimental mammary tumorigenesis; reasons for this discrepancy include the possibility that SAC may exhibit nonlinear dose effects.