Effect of retinoids and carotenoids on prostaglandin formation by oral squamous carcinoma cells.

Several studies have correlated the excessive production of prostaglandins (PGs) with tumor promotion and the suppression of the immune response. Inhibition of PGs by pharmacological agents has been demonstrated to enhance immunocompetence, and to suppress growth of tumors in animals and humans. In this study we examined the effect of retinol (I), all-trans-retinoic acid (II), N-(4-Hydroxyphenyl) retinamide (N-4-HPR) (III), canthaxanthin (CTX) (IV), and beta-carotene (beta-CT) (V) on the bioconversion of 14C-arachidonic acid (AA) to PGE2 by squamous carcinoma cells of the tongue, SCC-25. Agents (I), (II), (III), (IV) inhibited while (V) stimulated PGE2 formation in a dose related manner. N-4-HPR was the most potent inhibitor of PGE2 synthesis. The data suggest that certain retinoids and carotenoids have the potential of inhibition of PG synthesis by oral squamous carcinoma cells. Inhibitory effects such as those described here and antioxidant properties might in part contribute to the antiinflammatory and anticarcinogenic activity of retinoids in vivo.

Prostaglandin E2 antagonizes gingival fibroblast proliferation stimulated by interleukin-1 beta.

Treatment of human gingival fibroblasts with prostaglandin E2 (PGE2) resulted in significant concentration-dependent inhibition in deoxyribonucleic acid (DNA) synthesis (8.40-37.89%), while indomethacin (INDO) (PG inhibitor), interleukin-1 beta (IL-1 beta) or IL-1 beta+INDO caused a significant and dose-dependent increase in DNA synthesis. Addition of PGE2 to culture media containing IL-1 beta and INDO caused a significant concentration-dependent reduction in IL-1 beta- and INDO-induced stimulation of DNA synthesis. The findings suggest that IL-1 beta and PGE2, which are also produced by fibroblasts, could play an important role in regulation of gingival tissue development and wound healing, and their modulation may have therapeutic potential.

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.

Inhibition of growth in oral squamous carcinoma cells by cyclopentenone prostaglandins: comparison with chemotherapeutic agents.

Four cyclopentenone prostaglandins (CPPGs) and PGE2 caused significant dose-dependent inhibition in growth of human oral squamous carcinoma cells (SCC-15). The rank order of their potency was PGJ2>PGA1>16, 16-dimethyl PGA1>PGA2>PGE2. In a follow-up experiment it was found that the mean per cent inhibition in cell growth by PGJ2 and delta12-PGJ2 at 10(-5) M was 61.22 and 63.81, while that of 5-fluorouracil and methotrexate was 36.67 and 38.86, respectively. delta12-PGJ2 and PGJ2 induced significant dose-dependent inhibition in nuclear DNA synthesis (i.e. cell proliferation). Combining vitamin E succinate with lower concentrations of CPPGs enhanced significantly their inhibitory effect on nuclear DNA synthesis of cancer cells.

Comparison of the inhibitory effect of polyunsaturated fatty acids on prostaglandin synthesis I oral squamous carcinoma cells.

Polyunsaturated fatty acids (PUFAs) have been shown to suppress the growth rate of human osteogenic sarcoma cells and to have selective cytotoxic activity against human cancer cells. The purpose of this study was to investigate the efficacy of various PUFAs on inhibition of prostaglandin (PG) synthesis by oral squamous carcinoma cells (SCC-25). A significant inhibition of PGE2 and PGF2 alpha synthesis in SCC-25 was observed by all PUFAs tested except in the case of linoleic acid (LA) at 10 microM level. At 10 microM level the rank order of inhibition of PG synthesis by PUFAs was docosahexaenoic (DHA) greater than eicosapentaenoic (EPA) + DHA greater than dihomogamma-linolenic (DGLA) greater than EPA greater than alpha-linolenic (ALA) greater than linoleic (LA). At 50, 75, 100 microM the rank order of inhibition was DGLA greater than EPA greater than EPA + DHA greater than DHA greater than ALA greater than LA.

Comparison of the inhibitory effect of polyunsaturated fatty acids on prostaglandin synthesis. II. Fibroblasts.

In a previous publication we reported that PUFAs of the n-6 and n-3 series caused significant inhibition of synthesis of both PGE2 (28.4-92.8%) and PGF2 alpha (24.4-84.0%) in the oral squamous carcinoma cell line SCC-25. In this report we describe the inhibitory effect of the same acids on PG synthesis in normal human gingival fibroblasts under the same experimental conditions. It was found that a combination of EPA + DCHA (6:4), DCHA and ALA caused significant reduction in synthesis of PGE2 (10.1-87.8%) and PGF2 alpha (14.0-54.6%) at the four dose levels studied. The rank order of potency of acids in reduction of PG synthesis was: EPA + DCHA greater than DCHA greater than EPA greater than ALA greater than LA greater than DGLA greater than GLA. The data suggest that although PUFAs are effective inhibitors of PG synthesis by gingival fibroblasts and SCC-25, the fibroblast is less susceptible to the inhibitory effect of fatty acids.

The relationship between inflammation and cAMP level in human gingiva.

The levels of cAMP were measured by means of radioimmunoassay in 20 gingival samples free from inflammatory cells and 43 samples with moderately dense and dense aggregations of inflammatory cells. The average values were found to be 340 +/- 44 and 552 +/- 59 pmol/gm wet tissue, respectively. The increase in cAMP levels in inflammation is suggested to be modulated by an increase in endogenous prostaglandin synthesis and could be one of the natural mechanisms by which the host protects itself from dangerous consequences of unregulated immune response.

Biosynthesis of prostaglandin E2 and F2 alpha in gingiva of patients with chronic periodontitis.

The biosynthesis of radioactive prostaglandin E2 (PGE2) and F2 alpha from (1-14C) arachidonic acid has been demonstrated in the microsomal fraction of gingiva of patients with chronic periodontitis in vitro. 14C corresponding to unmetabolized arachidonic acid in three separate incubations was 83, 66, and 83%, and that corresponding to both PGE2 and PGF2 alpha was 8, 22, and 9% of the total radioactivity recovered after chromatography. The ratios of PGE2 to PGF2 alpha were found to be 6:1, 6:1, and 3:1, respectively.

The effect of non-steroidal anti-inflammatory drugs on the metabolism of 14C-arachidonic acid by human gingival tissue in vitro.

We investigated the effect of non-steroidal anti-inflammatory drugs on prostaglandins (PGs) and 12-hydroxyeicosatetraenoic acid (12-HETE) formation by inflamed human gingival tissues. Gingival tissue homogenates were incubated with 14C-arachidonic acid in the presence of indomethacin, piroxicam, or ibuprofen, and the organic solvent extracts were chromatographed on silica gel plates with standards for radiometric assay. There was a significant negative trend between the doses (10(-7)-10(-3) M) of each of indomethacin, piroxicam, and ibuprofen, and the amounts of PGF2 alpha, PGE2, PGD2, and 15-keto-PGE2 produced. All three drugs have a significant inhibitory effect on PGs and 12-HETE production at 10(-3) M when compared with the control. The rank order effectiveness of the drugs, at 10(-3) M, on PG inhibition was indomethacin greater than piroxicam greater than ibuprofen, and on 12-HETE inhibition was indomethacin greater than ibuprofen greater than piroxicam.

In vitro metabolism studies of (1, 2, 6, 7-3-H)-cortisol in human gingiva in health and disease.

The major conversion products of incubation of 3-H-cortisol with slices of human clinically normal and inflamed gingiva were identified as 11beta-hydroxyandrostenedione and cortisone. Reduction of C-20 of cortisol to 20alpha- and 20beta-dihydro metabolites was found only after incubation of cortisol with normal gingiva and not with inflamed tissue. Thus the two major pathways of metabolism of cortisol in the gingiva appear to be the oxidative cleavage of the side chain and the oxidation of 11beta-ol while the reduction of the 20-one appear limited to the normal tissue. The mean rates of conversion of cortisol to its various metabolites in 12 normal and 12 chronically inflamed gingival tissue samples were 147 and 55.2 pmoles hr-1-mg-1 respectively. The less conversion of cortisol in inflamed tissue might explain its effectiveness as a naturally occuring antiinflammatory hormonal steroid.

The inhibitory effect of curcumin, genistein, quercetin and cisplatin on the growth of oral cancer cells in vitro.

Epidemiological evidence indicates that plant derived flavonoids and other phenolic antioxidants protect against heart disease and cancer. In the current investigation utilizing human oral squamous carcinoma cell line (SCC-25), we have evaluated the potency of three different plant phenolics, viz., curcumin, genistein and quercetin in comparison with that of cisplatin on growth and proliferation of SCC-25. Test agents were dissolved in DMSO and incubated in triplicates in 25 cm2 flasks in DMEM- HAM's F-12 (50:50)supplemented with 10% calf serum and antibiotics in an atmosphere 5% CO2 in air for 72 hours cell growth was determined by counting the number of cells in a hemocytometer. Cell proliferation was determined by measuring DNA synthesis by the incorporation of [3H]-thymidine in nuclear DNA. Cisplatin (0.1, 1.0, 10.0 microM) and curcumin (0.1, 1.0, 10.0 microM) induced significant dose-dependent inhibition in both cell growth as well as cell proliferation. Genistein and quercetin (1.0, 10.0, 100.0 microM) had biphasic effect, depending on their concentrations, on cell growth as well as cell proliferation. Based on these findings, it is concluded that curcumin is considerably more potent than genistein and quercetin, but cisplatin is five fold more potent than curcumin in inhibition of growth and DNA synthesis in SCC-25.

Effect of tea polyphenols on growth of oral squamous carcinoma cells in vitro.

Epidemiologic evidence indicates that both black and green tea is a rich source of flavonoids and other polyphenolic antioxidants which protects against heart disease and cancer. In the current investigation, utilizing human oral squamous carcinoma cell line SCC-25, we have evaluated the effect of three major tea constituents, (-)-epigallocatechin-3-gallate (EGCG), (-)-epicatechin-3-gallate (ECG) and (-)-epigallocatechin (EGC) on cell growth and DNA synthesis. Test agents in concentrations of 50, 80, 100 and 200 microM were incubated in triplicates in DMEM-HAM's F-12 (50: 50) supplemented with 10% calf serum and antibiotics in an atmosphere of 5% CO2 in air for 72 hrs. Cell growth was determined by alamarBlue assay method and DNA synthesis was measured by the incorporation of [3H]-thymidine in nuclear DNA. At the four dose levels used, the three compounds induced significant dose-dependent inhibition in cell growth. In DNA study, the three compounds exhibited stimulatory effect at 50 microM followed by significant dose-dependent inhibitory effect (10 to 100%) at 80, 100 and 200 microM dose levels. Dose-dependent changes in cell morphology were also observed with phase-contrast microscopy after cell treatment with EGCG.

Biphasic action of vitamin E on the growth of human oral squamous carcinoma cells.

Treatment of human tongue squamous carcinoma cell, SCC-25, with physiological concentrations of vitamin E succinate (VES) which varied from 0.001 to 50 mumoles/L resulted in significant dose-dependent stimulation of cell growth. Whereas, pharmacological doses of the vitamin (100-154 microM) induced significant inhibition in cell growth. The possible anticarcinogenic mechanisms of action of vitamin E are discussed.

The effect of red wine and its components on growth and proliferation of human oral squamous carcinoma cells.

Epidemiologic evidence indicates that red wine may contain phenolic compounds which protect against heart disease and cancer. Resveratrol and quercetin are wine phenolics which possess antioxidant and antimutagenic effects. Resveratrol at 10 and 100 microM induced significant dose-dependent inhibition in human oral squamous carcinoma cell (SCC-25) growth and DNA synthesis. Quercetin exhibited a biphasic effect, stimulation at 1.0 and 10 microM and minimal inhibition at 100 microM in cell growth and DNA synthesis. Combining 50 microM of resveratrol with 10, 25 and 50 microM of quercetin resulted in gradual and significant increase in the inhibitory effect of the two compounds. Diluted red wine which contained only 1.6 microM of each of resveratrol and quercetin had significantly more inhibitory effect on cell growth, DNA synthesis and changes in cell morphology than each compound alone or in combination. We conclude that: (i) Resveratrol by itself or a combination of resveratrol and quercetin are effective inhibitors of SCC-25 growth and DNA synthesis. (ii) The presence of other wine phenolic phytochemicals enhance significantly the effect of resveratrol and quercetin on inhibition of cancer cell growth and DNA synthesis.

Prostaglandins in gingiva of patients with periodontal disease.

Prostaglandin E and F were measured simultaneously by radioimmunoassay in extracts of gingiva of patients with chronic periodontal disease. The mean values of PGE and PGF in 27 gingival samples were 42.2 +/- 4.9 and 52.6 +/- 6.8 pmol/gm wet tissue weight, respectively. The correlation coefficient (r) between the two groups of PGs was a positive 0.42, significant at P less than 0.05.

Arachidonic acid metabolism in inflamed gingiva and its inhibition by anti-inflammatory drugs.

Prostaglandin (PG) synthetase inhibitors are tissue-selective. Therefore, the action of four nonsteroidal anti-inflammatory drugs (NSAID) was tested against PG synthesis from 14C-arachidonic acid by gingival homogenate. Suprofen and tolmetin sodium did not significantly inhibit PGs at any of the three concentration levels used (10(-7), 10(-5), 10(-3) M), whereas flurbiprofen and zomepirac sodium did significantly inhibit PG formation at millimolar concentration. The results, coupled with our previous study on indomethacin, piroxicam and ibuprofen open the way for future tests of NSAIDs in treatment of gingival inflammation and periodontal disease.