Retardation of experimental oral cancer by topical vitamin E

The Role of Vitamins in Oral Potentially Malignant Disorders and Oral Cancer: A Systematic Review

BACKGROUND

Micronutrients are vital for general and oral health, and their potential anti-cancer properties are documented. We explore beneficial vitamins for oral potentially malignant disorders (OPMDs) and oral cancer (OC), assessing the therapeutic impacts of essential vitamin supplementation.

METHODS

We systematically review evidence on vitamin supplementation's therapeutic effects for OPMDs and OC. Relevant studies were identified through comprehensive searches of MEDLINE, Evidence-Based Medicine, and Web of Science until 16 May 2023. All studies underwent risk of bias using criteria modified from the Office of Health Assessment and Translation (OHAT) tool.

RESULTS

We analysed 80 papers. Vitamin K, studied in vitro, shows promising therapeutic potential. Vitamin C, investigated in vivo (animals and humans), demonstrated mixed animal results and generally positive human trial effects. Vitamin A's efficacy varied, with positive monotherapy or adjunct effects. Vitamins B and D showed therapeutic benefits. Oral cancer research was extensive, with a focus on oral lichen planus and oral leukoplakia among the 11 OPMDs. All bias levels were reported in 'selective reporting' and 'performance', except for "definitely high" in the 'selection', 'detection', and 'attrition/exclusion' domains.

CONCLUSIONS

Evidence of vitamin interventions for OPMDs and OC ranges from mixed to promising. Standardizing the study design and outcomes would enhance future research.

Development of a Nanoparticle-Embedded Chitosan Sponge for Topical and Local Administration of Chemotherapeutic Agents

The following work describes the development of a novel noninvasive transmucosal drug delivery system, the chitosan sponge matrix (CSM). It is composed of cationic chitosan (CS) nanoparticles (NPs) that encapsulate cisplatin (CDDP) embedded within a polymeric mucoadhesive CS matrix. CSM is designed to swell up when exposed to moisture, facilitating release of the NPs via diffusion across the matrix. CSM is intended to be administered topically and locally to mucosal tissues, with its initial indication being oral cancer (OC). Currently, intravenous (IV) administered CDDP is the gold standard chemotherapeutic agent used in the treatment of OC. However, its clinical use has been limited by its renal and hemotoxicity profile. We aim to locally administer CDDP via encapsulation in CS NPs and deliver them directly to the oral cavity with CSM. It is hypothesized that such a delivery device will greatly reduce any systemic toxicity and increase antitumor efficacy. This paper describes the methods for developing CSM and maintaining the integrity of CDDP NPs embedded in the CSM.

Association between langerhans cells population and histological grade of oral squamous cell carcinoma

Context:

Langerhans cells (LCs) are a unique population of antigen processing cells in the epidermis and mucous membrane, which may play a role in the defence mechanism against epithelial tumors.

Aims:

To compare the distribution of LCs in oral squamous cell carcinomas (OSCC) and normal oral epithelium; and to determine whether the population of LCs in OSCC has any correlation with histological grading of these malignancies.

Settings and Design:

A cross-sectional immunohistochemical analysis of OSCC cases.

Materials and Methods:

Forty-eight randomly selected paraffin tissue blocks of OSCC cases and 30 cases of normal oral epithelium were included. Hematoxylin and eosin-stained sections of the OSCC cases were reviewed and categorized as high-grade malignant tumors or low-grade malignant tumors. Tissue sections were analyzed for density of LCs using CD1a antibody expression.

Statistical Analysis Used:

Data are expressed as percentages compared by Chi-square statistics; mean ± standard deviation, compared by Mann-Whitney-U test and Spearman's correlation tests.

Results:

LCs population was significantly higher in normal oral epithelium when compared with OSCC cases (P = 0.001). There was also a significant difference in the number of LCs per millimetre square area of tissue section between well-differentiated tumors and poorly-differentiated tumours (P = 0.03). There was a negative correlation between the population density of LCs and the grade of OSCC.

Conclusions:

These findings suggest that oral mucosal LCs are involved in immune-surveillance and immunologic impairment may characterize invasive OSCC. In addition, LCs density characterizes histological grades of OSCC, which may be of a prognostic value.

Vitamin or mineral supplement intake and the risk of head and neck cancer: pooled analysis in the INHANCE consortium

To investigate the potential role of vitamin or mineral supplementation on the risk of head and neck cancer (HNC), we analyzed individual-level pooled data from 12 case-control studies (7,002 HNC cases and 8,383 controls) participating in the International Head and Neck Cancer Epidemiology consortium. There were a total of 2,028 oral cavity cancer, 2,465 pharyngeal cancer, 874 unspecified oral/pharynx cancer, 1,329 laryngeal cancer and 306 overlapping HNC cases. Odds ratios (OR) and 95% confidence intervals (CIs) for self reported ever use of any vitamins, multivitamins, vitamin A, vitamin C, vitamin E, and calcium, beta-carotene, iron, selenium and zinc supplements were assessed. We further examined frequency, duration and cumulative exposure of each vitamin or mineral when possible and stratified by smoking and drinking status. All ORs were adjusted for age, sex, race/ethnicity, study center, education level, pack-years of smoking, frequency of alcohol drinking and fruit/vegetable intake. A decreased risk of HNC was observed with ever use of vitamin C (OR = 0.76, 95% CI = 0.59-0.96) and with ever use of calcium supplement (OR = 0.64, 95% CI = 0.42-0.97). The inverse association with HNC risk was also observed for 10 or more years of vitamin C use (OR = 0.72, 95% CI = 0.54-0.97) and more than 365 tablets of cumulative calcium intake (OR = 0.36, 95% CI = 0.16-0.83), but linear trends were not observed for the frequency or duration of any supplement intake. We did not observe any strong associations between vitamin or mineral supplement intake and the risk of HNC.

Tailoring cancer chemoprevention regimens to the individual

The present article, which is a tribute to the memory of Dr. Edward Bresnick, emphasizes the importance of environmental and life-style factors for cancer causation in the human population and points out approaches to cancer prevention. These approaches include vaccinations for the prevention of cancers that are caused by infectious agents as well as the use of cancer chemopreventive agents. The use of tamoxifen and letrozole to prevent breast cancer, finasteride to prevent prostate cancer, sunscreens or topical applications of 5-fluorouracil to prevent sunlight-induced skin cancer, and aspirin or calcium to prevent colon cancer are a few examples of cancer chemoprevention in high risk individuals and in the general population. An underdeveloped area of cancer chemoprevention is the use of combinations of agents that work by different mechanisms. It was pointed out that animal studies indicate that many cancer chemopreventive agents inhibit carcinogenesis under one set of experimental conditions but enhance carcinogenesis under another set of experimental conditions. These observations suggest that tailoring the chemopreventive regimen to the individual or to groups of individuals living under different environmental conditions or with different mechanisms of carcinogenesis may be an important aspect of cancer chemoprevention in human populations. How to tailor cancer chemoprevention regimens to the individual is an important challenge for the future.

Effects of topical and oral vitamin E on pigmentation and skin cancer induced by ultraviolet irradiation in Skh:2 hairless mice

This study investigates whether supplementation with topical RRR-alpha-tocopherol (Eol), topical RRR-alpha-tocopheryl succinate, and oral RRR-alpha-tocopheryl acetate can reduce the incidence of acute and chronic damage to the skin (i.e., sunburn and pigmentation and skin cancer, respectively) induced by ultraviolet (UV) irradiation to mice. Groups of twenty Skh:2 female hairless pigmented mice were treated with 1) lotion vehicle, 2) 5% Eol lotion, 3) 5% topical RRR-alpha-tocopheryl succinate lotion, or 4) lotion vehicle and oral RRR-alpha-tocopheryl acetate. Within each group, 15 mice were exposed to 0.24 J/cm2 of UV-B radiation three times per week. The animals' weights and food intakes were monitored, and the vitamin E concentrations of skin, liver, and adipose tissue were measured to determine whether the topical Eol resulted in significant tissue levels. Skin pigmentation was scored, and the total number of clinically detectable skin tumors per animal was counted weekly. Results showed that the skin concentrations of Eol, as well as levels in the adipose tissue, were increased after topical application. Mice treated with each form of vitamin E showed no signs of toxicity and had significantly less acute and chronic skin damage induced by UV irradiation, as indicated by reduced inflammation and pigmentation and by later onset and lesser incidence of skin cancer.

Response of human oral epithelial cells to oxidative damage and the effect of vitamin E

Smoking and periodontal inflammation are various conditions with the potential to induce oxidative stress and thus DNA damage in the oral cavity. In cellular defense systems, vitamin E is considered the most powerful lipid-soluble antioxidant. To investigate whether oxygen-free radicals alter normal progression of the cell cycle and whether vitamin E prevents this damage, we exposed cultured normal human oral epithelial cells to hydrogen peroxide (H2O2) in the presence or absence of vitamin E. Two primary cell lines were analyzed for the presence of hydroxyl radical, cell cycle distribution and morphology. Each cell line received five treatments: control, ethanol only, vitamin E only, H2O2 only or vitamin E followed by H2O2. Degradation of hydroxyl radicals was detected by electron paramagnetic resonance analysis, cell cycle by flow cytometry and morphology by organotypic technique. Hydroxyl radicals were generated in H2O2-treated cells at an initial concentration, which decreased over a period of time. Cell cycle analysis showed that H2O2-treated cells differed from normal cells in that the percentage of cells in the G1 phase decreased markedly (34.3 vs. 61.2% in control) and the S phase increased (35.5 vs. 15.6% in control). Organotypic cultures treated with H2O2 demonstrated nuclear hyperchromatism, loss of maturation and prominent nucleoli, features consistent with premalignant epithelial transformation. In conclusion, our data suggest that H2O2 produced hydroxyl radicals and altered the cell cycle. Also, vitamin E may have the potential to reduce oxidative damage caused by hydroxyl radicals.

Vitamin E succinate potentiates the inhibitory effect of prostaglandins on oral squamous carcinoma cell proliferation

Previous studies have shown that prostaglandin E2 (PGE2) and vitamin E succinate can act in an additive manner to inhibit the proliferation of human oral squamous carcinoma cells (SCC-25). The initial studies on the additive anticancer activity of PGE2 and vitamin E succinate have been extended to include antineoplastic PGs, delta 12-PGJ2 and PGJ2. Treatment of oral squamous carcinoma cells (SCC-15) with delta 12-PGJ2, PGJ2, and vitamin E succinate, individually, caused significant concentration-dependent inhibition of cell proliferation to various degrees. PGJ2 was most potent and caused an inhibition that corresponded to 85.55% at 10(-5) M. Addition of 1 microM of vitamin E succinate to delta 12-PGJ2 or PGJ2 resulted in a significant increase in the inhibitory potency of the lower concentrations of the two PGs. These results suggest a novel role for a mixture of PGs and vitamin E as potent antitumor proliferative agents.

Biology and chemoprevention of head and neck cancer

Head and neck cancer remains a common cause of mortality and morbidity in the United States and throughout the world. In spite of advances in the management of patients with advanced disease, overall survival in this group remains poor. Furthermore, although cancer mortality is lower in patients with early-stage disease, treatment results in significant morbidity, and these patients also face the risk of developing a second primary tumor. Chemoprevention is an innovative approach to decrease overall cancer morbidity and mortality using substances that are capable of preventing cancer progression. Head and neck cancer is an excellent model for chemoprevention, as its biology is consistent with the two concepts important for the development of chemoprevention strategies: field cancerization and multistep carcinogenesis. Several classes of compounds have been evaluated in chemoprevention trials. The most frequently studied agents, the retinoids, were found frequently to induce remissions in patients with oral leukoplakia. Furthermore, retinoids prevented progression to malignancy in one randomized maintenance study. Other agents, including beta-carotene and vitamin E, have been found also to have activity in the management of oral leukoplakia. However, the clinical role of chemopreventive agents in reducing cancer mortality remains to be defined. Two studies, one in head and neck cancer and one in lung cancer, have shown the ability of retinoids to prevent the development of second primary tumors. Current large randomized trials are defining the effectiveness of these agents in reducing the mortality of aerodigestive tract tumors in individuals at high risk.

Inhibition of human oral squamous carcinoma cell (SCC-25) proliferation by prostaglandin E2 and vitamin E succinate

The primary objective of this investigation was to study the effect of D-alpha-tocopherol acid succinate (vitamin E succinate) and prostaglandin E2 (PGE2), individually and in combination, on the proliferation of human tongue squamous carcinoma cells (SCC-25) in vitro. Test compounds in varying concentrations were incubated with cells in serum-free Dulbecco's Modified Eagle's Medium-Ham's F-12 Medium (50:50), supplemented with 0.1% albumin for sixteen hours. Cell proliferation was measured by the incorporation of [3H] thymidine in acid-insoluble material (i.e. DNA). Prostaglandin E2 and vitamin E succinate, individually at 10(-9)-10(-6) M, caused significant dose-dependent inhibition in DNA synthesis. A combined dose of each compound at 10(-5) M resulted in significant additive inhibition which averaged 43.53% (p < 0.005). Addition of indomethacin (INDO) to cell cultures induced significant dose-dependent stimulation in DNA synthesis. Hence, we might suggest that the overall potential of vitamin E in controlling malignant cell proliferation in vivo could be due to its own effect combined with that of endogenous PGs which are normally produced in excessive amounts by malignant cells.

p53 in the anticancer mechanism of vitamin E

Immunohistochemical techniques were used to study the expression of "wild type" p53 and "mutant" p53 in experimental cancer inhibition by vitamin E. The cancer model used was the squamous cell carcinoma of hamster buccal pouch induced by the carcinogen 7,12 dimethylbenz(a)anthracene (DMBA). Cancer development was studied sequentially for 8-14 weeks and specimens prepared for histological and immunohistochemical interpretation. Primary antibodies used were monoclonal antibodies for "wild type" and "mutant" p53. Specificity of antibodies was confirmed by flow cytometry. Peroxidase-antiperoxidase staining was used on the tissue specimens. In those animals receiving vitamin E the buccal pouch tumour development was significantly inhibited and there was a notable expression of "wild type" p53. There was also a relative absence of "mutant" p53 in the buccal pouch lesions of animals receiving vitamin E. These observations suggest that vitamin E may inhibit cancer formation by stimulating the expression of a cancer suppressor gene.

Prevention of photocarcinogenesis by dietary vitamin E

Ultraviolet B (UV-B) irradiation of C3H/HeN mice induces skin cancer. In this study, the ability of dietary d-alpha-tocopheryl acetate to reduce photocarcinogenesis was tested in this murine model. Skin cancers developed in 67.5% of UV-B-irradiated mice by 31 weeks after the first UV exposure. Supplementation with 100 or 200 IU of d-alpha-tocopheryl acetate per kilogram of diet led to a reduction of the incidence to 46% and 19%, respectively. The latter value was significantly different from that found in mice fed the basal diet (p = 0.039, one-sided P value by log-rank test). Skin levels of alpha-tocopherol varied with the dietary dose of d-alpha-tocopheryl acetate. No toxicity was evident in unirradiated mice fed the vitamin E-supplemented diet, but 40% of the UV-B-irradiated mice fed 200 IU of vitamin E per kilogram of diet died by 31 weeks after the first UV-B treatment. Decreased relative spleen weight was observed in the UV-B-irradiated mice fed the vitamin E-supplemented diet. In summary, oral d-alpha-tocopheryl acetate prevented photocarcinogenesis, but at doses that were toxic to inbred C3H/HeN mice after exposure to 8.6 x 10(5) J/m2 of UV-B irradiation.

Beta-carotene and vitamin E in oral cancer prevention

The ultimate proof that a putative chemopreventive agent does prevent cancer is a demonstration of reduced cancer incidence in a targeted population. However, because of practical and logistical considerations, such trials are virtually impossible to conduct for the majority of cancers. Therefore, a conclusion regarding the efficacy of chemopreventive activity is based on consideration of a variety of indirect lines of evidence, including laboratory studies, animal model systems, epidemiologic surveys, intervention trials involving reversal of premalignant changes, and the prevention of malignancies in particularly high risk subjects. Furthermore, the only agents worth testing are those with limited, or preferably, no toxicity, since the final use will be prevention in a generally healthy population. Beta-carotene and vitamin E both fulfill all the criteria for suitable chemopreventive agents; several lines of evidence point toward preventive roles for them in oral cancer. In numerous epidemiologic studies, low intake of beta-carotene has been associated with higher cancer risk. Both intake and supplemental use of vitamin E have been associated with a lowered risk of cancer. Smokers, whose habit is a major risk factor, have lower beta-carotene levels in oral mucosal cells when compared with non-smokers. In several laboratory and animal model systems, including the very relevant hamster cheek pouch model, these agents strongly inhibit oral cavity carcinogenesis. Beta-carotene and vitamin E produce regression of oral leukoplakia, a premalignant lesion for oral cancer. This has now been shown in seven clinical trials: five with beta-carotene alone, one with vitamin E, and one with a combination of both.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vitamin C and vitamin E on prostaglandin synthesis by fibroblasts and squamous carcinoma cells

Dietary levels of vitamins C and E have been associated with cancer prevention and to a lesser extent with therapeutic enhancement of cancer treatment. Inhibition of prostaglandins (PGs) by pharmacological agents has been demonstrated to enhance immunocompetence, and to suppress growth of tumors in animals and humans. We report here on the effect of vitamins C and E on PGE2 production by human gingival fibroblasts and SCC-25 oral squamous carcinoma cells. The results indicate: 1. vitamins C and E exert a dose-dependent effect on arachidonic acid (AA) release and PGE2 synthesis; 2. vitamin E has a biphasic effect which is stimulatory at 1 and 10 microM and inhibitory at 100 microM; 3. vitamin E is considerably more potent than vitamin C in its inhibitory effect on AA and PGE2 in both cell types; 4. a combination of the two vitamins has a consistent dose-dependent inhibitory effect on AA and PGE2; 5. vitamin C stimulates PGE2 synthesis from exogenous AA in fibroblasts, and inhibits it in SCC-25 cells. The in vivo significance of these findings requires further investigation.

Vitamin E and cancer prevention: recent advances and future potentials

Many animal and in vitro experiments have shown that the supplementation of diet with vitamin E within a certain dose range reduced the risk of chemical- and radiation-induced cancers. In vitro studies revealed that alpha-tocopheryl succinate (TS) induced differentiation and growth-inhibition in certain animal and human tumor cells in culture, whereas alpha-tocopherol (alpha-T), alpha-tocopheryl acetate (alpha-TA) and alpha-tocopheryl nicotinate (alpha-TN) were ineffective, alpha-TS also reduced basal and ligand-stimulated adenylate cyclase activity, and expression of c-myc and H-ras oncogenes in certain tumor cells in culture. The relative efficacy of various forms of vitamin E in cancer prevention in animal or human models has not been evaluated. Human epidemiologic studies utilizing retrospective and prospective case-control experimental designs are not suitable for evaluating the role of vitamin E in cancer prevention due to several inherent problems associated with these methodologies. Intervention trials utilizing vitamin E with appropriate biological and statistical rationales are most suitable for testing the role of vitamin E in cancer prevention in humans. Some human trials utilizing vitamin E alone or in combination with other nutrients are in progress.

Role of vitamin E in the prophylaxis of cancer

Vitamin E may have anticancer properties as a lipid antioxidant and free radical scavenger. Some animal studies support this hypothesis, although findings are contradictory. Most human studies on the role of vitamin E in cancer etiology have been of case-control or cohort design. The results of such studies on whether vitamin E intake reduces the risk of cancer do not generally support the hypothesis of its protective effect, possibly owing to methodological issues. Some of the case-control studies, however, have shown lower concentrations of vitamin E in the serum of patients with cancer than in the controls. Cohort studies also generally show a low level of serum vitamin E associated with a slightly increased risk of cancer, though the strength of this association varies between populations and subgroups, as well as for different cancer sites. No definite conclusions about a causal connection between vitamin E and the occurrence of cancer can be drawn until the final results of current large-scale intervention trials are published.

Topical vitamin E inhibition of immunosuppression and tumorigenesis induced by ultraviolet irradiation

Ultraviolet (UV) irradiation of C3H/HeN mice induces skin cancer and an immunosuppression that prevents the host from rejecting antigenic UV-induced tumors. The capacity of topical vitamin E (dl-alpha-tocopherol) to prevent photocarcinogenesis or the immunosuppression induced by UV irradiation were assessed. Skin cancer incidence in UV-irradiated mice was 81% at 33 weeks after the first UV exposure; application to mice of 25 mg vitamin E three times per week for three weeks before UV irradiation, and throughout the experiment, reduced this incidence to 42% (p = 0.0065, log rank test). Immunoenhancement by vitamin E was assessed by comparing levels of immunosuppression by splenocytes from normal or UV-irradiated mice, with and without topical vitamin E treatment. Transfer of splenocytes from UV-irradiated mice to naive mice prevented the recipients from rejecting a UV-induced tumor challenge, whereas splenocytes from UV-irradiated mice treated with vitamin E did not prevent recipients from rejecting a similar tumor challenge. Phenotypic analysis of splenocytes used in the passive transfer assay, conducted with a biotin-avidin-immunoperoxidase technique, revealed that vitamin E treatment of mice undergoing UV irradiation prevented the UV-induced down regulation of Ia expression in splenocytes and increased the proportion of Lyt-2+ and L3T4+ splenocytes. Therefore, chronically applied vitamin E can effectively reduce cancer formation and immunosuppression induced by UV irradiation. Prevention of UV-induced down regulation of Ia expression may have contributed to this immunomodulation.

Vitamin E in biological systems

The evidence is increasing that free radical reactions are implicated in the development of cell damage and degenerative disease. Results of animal and human studies have demonstrated that vitamin E and the other antioxidants have a significant role in preventing or minimizing peroxidation damage in biological systems. As we await results of additional human studies, there is sufficient evidence to suggest that adequate antioxidant defense by vitamin E and the other antioxidants can provide protection from the increasingly high levels of free radicals present in the environment due to current lifestyles and the rising concentration of environmental pollutants.

The effects on complement component 3 of dietary variation of protein, fat and vitamin E during growth of young mice

Some studies have shown that nutrition lowers overall immunity to disease. To further elucidate the role of nutrition on immunity, we have investigated the effect on serum Complement C3 by three nutrients, protein, lipid and vitamin E, in BALB/c mice for up to 24 weeks. The group with high dietary vitamin E had slightly higher C3 for the first four months but by the 22nd week was lower than control. The groups receiving high or low protein had, respectively, high or low C3. Injection of thymosin fraction 5 increased the C3, suppressed by the low protein diet. The group on the high lipid diet had high C3 until the 14th week whereupon it declined to control level by the 22nd week. The low lipid diet resulted in low C3 during the early weeks but increased to control level by the 22nd week. We conclude that diet is important to complement mediated immunity of young mice.

Regression of experimental cancer by oral administration of combined alpha-tocopherol and beta-carotene

alpha-Tocopherol (vitamin E) and beta-carotene have been shown to be capable of regressing established epidermoid carcinomas of hamster buccal pouch when injected locally into the tumor site. Neither has yet been shown to be effective in regressing cancer when administered by oral route. However, a combination of both alpha-tocopherol and beta-carotene was shown to be effective in regressing epidermoid carcinomas of hamster buccal pouch when the mixture was administered orally in vegetable oil. The epidermoid carcinomas were induced in the right buccal pouch of 100 Syrian hamsters by painting three times weekly for 14 weeks with a 0.5% solution of 7,12-dimethylbenz[a]anthracene in mineral oil. The animals were then divided into five equal groups of 20 animals. Group 1 animals received no further treatment and represented tumor controls. Group 2 animals received 200 micrograms beta-carotene and 200 micrograms dl-alpha-tocopherol acid succinate combined in 0.2 ml vegetable oil. Animals received the mixture daily by mouth using a 1-ml syringe. Groups 3 and 4 received beta-carotene and alpha-tocopherol individually in double amounts (400 micrograms in 0.2 ml vegetable oil). Group 5 animals received only the vegetable oil (0.2 ml daily) and were controls for vehicle. The animals in Groups 1, 3, 4, and 5 were killed after 22 weeks because the tumors were extensive, large, and necrotic and the animals were weak and cachectic. After 22 weeks, the tumors in Group 2 animals were small in 15 out of 20 animals. The tumors were reduced in size compared with tumor burden at 14 weeks, the point at which the beta-carotene/alpha-tocopherol was started.

Inhibition of hamster buccal pouch carcinogenesis by green coffee beans

Forty female Syrian Golden hamsters were divided into two equal groups and placed on one of two diets. The hamsters in Group I received a normal chow, and the animals in Group II were given the same chow supplemented with powdered green coffee beans (20%). After the hamsters adjusted to the diets, 16 animals from each group were selected. The right buccal pouch of each of these hamsters was painted three times weekly with a 0.5% solution of 7, 12-dimethylbenz(a)anthracene (DMBA) in heavy mineral oil. The eight remaining animals, four in each group, served as controls and were treated three times weekly with heavy mineral oil. After a total of 50 treatments (16 1/2 weeks), the hamsters were killed. The animals receiving green coffee beans exhibited a significant delay in the development of DMBA-induced carcinogenesis of the buccal pouch mucosa, as determined by both visual and histologic examination.

Vitamin E stimulates proliferation of experimental oral carcinoma cells in vitro

Vitamin E was found to have a stimulatory effect on the growth in culture of an epidermoid carcinoma cell line derived from chemically induced tumors of hamster buccal pouch. This effect was found to be dose related, with a maximum stimulatory effect at 10 microM. At a concentration of 100 microM, there was an inhibitory effect on both cell turnover and colony formation.