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.

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.

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.

Modulating effect of resveratrol and quercetin on oral cancer cell growth and proliferation.

Resveratrol and quercetin are polyphenols which have been detected in significant amounts in green vegetables, citrus fruits and red grape wines. Beneficial effects attributed to these compounds include anti-inflammatory, antiviral and antitumor properties. The effect of resveratrol and quercetin on growth of human oral cancer cells is unknown. Resveratrol and quercetin, in concentrations of 1 to 100 microM, were incubated in triplicates with human oral squamous carcinoma cells SCC-25 in DMEM-HAM's F-12 supplemented with fetal calf serum and antibiotics in an atmosphere of 5% CO2 in air at 37 degrees C for 72 h. Cell growth was determined by counting the number of viable cells with a hemocytometer. Cell proliferation was measured by means of incorporation of [3H]thymidine in nuclear DNA. Resveratrol at 10 and 100 microM induced significant dose-dependent inhibition in cell growth as well as in DNA synthesis. Quercetin exhibited a biphasic effect, stimulation at 1 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 a gradual and significant increase in the inhibitory effect of quercetin on cell growth and DNA synthesis. We conclude that resveratrol or a combination of resveratrol and quercetin, in concentrations equivalent to that present in red wines, are effective inhibitors of oral squamous carcinoma cell (SCC-25) growth and proliferation, and warrant further investigation as cancer chemopreventive agents.

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.

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.

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.

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.

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.

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.

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.

In vitro inhibition of prostaglandin biosynthesis in squamous cell carcinoma by retinoids.

The aim of this study was to evaluate the effect of four natural and synthetic retinoids: Ro 12-7310 (I), Ro 13-7410 (II), 13-cis-retinoic acid (III), and Ro 13-7652 (IV) on the synthesis of PGE2 in human squamous cell carcinoma (SCC) of the tongue (SCC-25). 5 X 10(6) cells were plated and labeled with 0.2 microCi of (14C)-arachidonic acid (AA) in 2 ml of DMEM/F12 containing 0.1% BSA for 4 h. The cells were then washed, and incubated in serum-free medium with the retinoids (10,20,30,40 microM) for 1 h. The cells were further stimulated with melittin an additional hour. Radioactive metabolites released in media were then extracted with diethyl ether. The ether extracts were separated by TLC and radioactive PGE2 zone was quantitated by means of liquid scintillation counting. The rank order of percent inhibition of PGE2 synthesis by retinoids at four concentration levels was (I) greater than (II) greater than (III) greater than (IV). Since inhibition of PG production has been demonstrated to suppress growth of tumors in animal models and humans, further study on the effect of retinoids on growth of SCC in vitro as well as in vivo seems warranted.

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.

Effect of effervescent buffered aspirin on prostaglandin synthesis by human gingival fibroblasts.

Cultured human gingival fibroblasts were incubated with 14C-arachidonic acid (AA) at 37 degrees C for 2 hours. The metabolites formed were extracted from the cell-free medium in methanol, separated and identified by thin layer chromatography, using two solvent systems that allowed resolution of cyclooxygenase and lipoxygenase products. The predominant cyclooxygenase products were PGE2 and 6-keto-PGF1 alpha. PGA2, PGF2 alpha, PGD2, 15-keto-PGE2, TXB2 were also detected in smaller amounts. No detectable radioactivity corresponding to lipoxygenase products 5-HETE, 12-HETE, and 15-HETE was found. Incubation of fibroblasts with effervescent buffered aspirin (EBA) (.02%, .04%, .06%), or sodium bicarbonate, citric acid and aspirin, individually, (in concentrations equivalent to those present in EBA) resulted in stimulation of synthesis of PGs except PGE2 which was inhibited by EBA and aspirin.

Cancer and the prostaglandins: a mini review on cancer research.

This review article has explored the relationship between PGs and cancer. The experimental exploitation of PG compounds and inhibitors has disclosed many possible applications. The potential for pharmacologic manipulation of the "Arachidonic Acid Cascade" system to benefit the cancer patient is promising, and it will require close collaboration of the pathologist, the biochemist, the pharmacologist, and the clinician.

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.

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.

Testosterone inhibits prostaglandin formation by human gingival connective tissue: relationship to 14C-arachidonic acid metabolism.

The relationship between various concentrations of the male sex steroid, testosterone, and the formation of radioactive prostaglandins (PGs) from 14C-arachidonic acid by human gingival homogenate has been investigated. There were statistically significant (combined) linear and quadratic trends between hormone treatment at concentrations of 10(-9), 10(-7), 10(-5) and 10(-3)M and the amounts of PGF2, PGE2, PGD2 and 15-keto-PGE2 formed. The mean amount of each PG formed at the various concentrations of testosterone was statistically significantly less than the corresponding control level. The results indicate that testosterone, at the dose levels tested, is inhibitory to the cyclooxygenase pathway of arachidonic acid metabolism in gingiva.