Natural Compounds Modulate Drug Transporter Mediated Oral Cancer Treatment.

Oral cancer (OC) is a serious health problem. Surgery is the best method to treat the disease but might reduce the quality of life of patients. Photodynamic therapy (PDT) may enhance quality of life but with some limitations. Therefore, the development of a new strategy to facilitate PDT effectiveness has become crucial. ATP-binding cassette G2 (ABCG2) is a membrane protein-associated drug resistance and stemness in cancers. Here, we examined whether ABCG2 plays an important role in regulating the treatment efficacy of PDT and whether ABCG2 inhibition by natural compounds can promote the effect of PDT in OC cells. Several head and neck cancer cells were utilized in this study. OECM1 and SAS cells were selected to investigate the relationship between ABCG2 expression and protoporphyrin IX (PpIX) accumulation. Western blot analysis, flow cytometry analysis, and survival probability were performed to determine PDT efficacy and cellular stemness upon treatment of different dietary compounds, including epigallocatechin gallate (EGCG) and curcumin. In this study, we found that ABCG2 expression varied in OC cells. Hypoglycemic culture for SAS cells enhanced ABCG2 expression as higher ABCG2 expression was associated with lower PpIX accumulation and cellular stemness in OC cells. In contrast, suppression of ABCG2 expression by curcumin and tea polyphenol EGCG led to greater PpIX accumulation and enhanced PDT treatment efficiency in OC cells. In conclusion, ABCG2 plays an important role in regulating the effect of PDT. Change in glucose concentration and treatment with natural compounds modulated ABCG2 expression, resulting in altered PDT efficacy for OC cells. These modulations raise a potential new treatment strategy for early-stage OCs.

Arecoline activates latent transforming growth factor ß1 via mitochondrial reactive oxygen species in buccal fibroblasts: Suppression by epigallocatechin-3-gallate.

BACKGROUND/PURPOSE: Oral submucous fibrosis (OSF) is a premalignant condition caused by the chewing of areca nut (AN). Transforming growth factor ß (TGFß) plays a central role in the pathogenesis of OSF. Connective tissue growth factor (CTGF or CCN2) and early growth response-1 (Egr-1) are important mediators in the fibrotic response to TGFß in several fibrotic disorders including OSF. Arecoline, a major AN alkaloid, induced the synthesis of CCN2 and Egr-1 in human buccal mucosal fibroblast (BMFs). The aims of this study were to investigate whether arecoline-induced CCN2 and Egr-1 syntheses are mediated through TGFß1 signaling and to inspect the detailed mechanisms involved. METHODS: Western blot and TGFß1 Emax® ImmunoAssay were used to measure the effect of arecoline on the TGFß signaling pathways. 2',7'-dichlorodihydrofluorescein diacetate and MitoSOX™ Red were used to measure the effect of arecoline on the cellular and mitochondrial reactive oxygen species (ROS). RESULTS: Arecoline induced latent TGFß1 activation, Smad2 phosphorylation, and mitochondrial and total cellular ROS in BMFs. TGFß-neutralizing antibody completely inhibited the arecoline-induced synthesis of CCN2 and Egr-1. Mito-TEMPO, a mitochondria-targeted antioxidant, completely suppressed arecoline-induced latent TGFß1 activation and mitochondrial and total cellular ROS. Epigallocatechin-3-gallate (EGCG) dose-dependently inhibited arecoline-induced TGFß1 activation and mitochondrial ROS in BMFs. CONCLUSION: Our results indicated that arecoline-induced mitochondrial ROS plays pivotal roles in the activation of latent TGFß1 leading to the initiation of TGFß1 signaling and subsequent increase in the synthesis of CCN2 and Egr-1. EGCG can be a useful agent in the chemoprevention and treatment of OSF.

Effective vitamin B12 treatment can reduce serum antigastric parietal cell antibody titer in patients with oral mucosal disease.

BACKGROUND/PURPOSE: Patients with serum antigastric parietal cell antibody (GPCA) positivity may have vitamin B12 deficiency and some oral symptoms. This study assessed the changes of serum GPCA titer in GPCA-positive patients after effective vitamin B12 treatment. METHODS: Two hundred and ten GPCA-positive oral mucosal disease patients became oral symptom free (complete response) after 1.0-67.1 months of treatment with regular and continuous intramuscular injection of vitamin B12 once per week. The changes of serum GPCA titers after treatment were evaluated in these 210 patients. RESULTS: We found a significant drop of the GPCA positive rate from 100% to 42.9% in our 210 complete response patients after effective vitamin B12 treatment (p < 0.001). When 210 patients were further divided into seven subgroups according to the low to high serum GPCA titers, we noted that the higher serum GPCA titers decreased to significantly lower levels after treatment in all seven subgroups (all p < 0.001). However, serum GPCA titers increased to significantly higher levels in 46 GPCA-positive control patients receiving only oral administration of two vitamin BC capsules (containing 10 µg of vitamin B12) plus deficient hematinic supplements per day after a follow-up period of 2.7-27 months. A maintenance vitamin B12 treatment once a month could retain the GPCA-negative status in 87% of treated-to GPCA-negative patients compared with those (10%) without further maintenance vitamin B12 treatment. CONCLUSION: Regular and continuous effective vitamin B12 treatment can reduce the relatively higher serum GPCA titers to significantly lower or undetectable levels in GPCA-positive patients.

Cytotoxicity and transformation of C3H10T1/2 cells induced by areca nut components.

BACKGROUND/PURPOSE: Betel quid (BQ) chewing is popular in Taiwan and many other countries. There are about 200-600 million BQ chewers in the world. BQ chewing is one major risk factor of oral cancer and oral submucous fibrosis (OSF). While areca nut (AN), a main component of BQ, exhibits genotoxicity, its transformation capacity and its role in the initiation and promotion stages of carcinogenesis are not fully clear. METHODS: Mouse C3H10T1/2 cells were exposed to AN extract (ANE) for 24 hours. Cytotoxicity was evaluated by colony forming efficiency. For the transformation assay, C3H10T1/2 cells were exposed to ANE for 24 hours and then incubated in medium with/without 12-O-tetradecanolylphorbol-13-acetate (TPA; a tumor promoter) for 42 days. Cells were stained with Giemsa and type II and type III transformed foci were counted for analysis of the transformation capacity of ANE. RESULTS: ANE exhibited cytotoxicity to C3H10T/12 cells at concentrations higher than 320 µg/mL as shown by a decrease in colony numbers. ANE (80-640 µg/mL) alone mildly stimulated the transformed foci formation (p > 0.05). In the presence of TPA, ANE (80-640 µg/mL) markedly stimulated the transformed foci formation. The percentage of dishes with foci increased from 0% in controls to 20% in ANE (80 µg/mL and 320 µg/mL)-treated groups and further increased to 65-94% in ANE plus TPA groups. CONCLUSION: These results indicate that ANE is a weak complete carcinogen. ANE is an effective tumor initiator and can induce malignant transformation of C3H10T1/2 cells in the presence of a tumor promoter. ANE may be involved in multistep chemical carcinogenesis by its malignant transformation capacity.

Sphingosine-1-phosphate stimulated connective tissue growth factor expression in human buccal fibroblasts: Inhibition by epigallocatechin-3-gallate.

BACKGROUND/PURPOSE: Connective tissue growth factor (CCN2) has been associated with the pathogenesis of various fibrotic diseases, including oral submucous fibrosis (OSF). The chemical constituents of areca nut along with the mechanical trauma cause OSF. The coarse fibers of areca nut injure the mucosa and hence sphingosine-1-phosphate (S1P) is released at the wounded sites. Recent studies have shown that S1P is involved in wound healing and the development of fibrosis. The aims of this study were to investigate the effects of S1P on CCN2 expression in human buccal fibroblasts (HBFs) and identify the potential targets for drug intervention or chemoprevention of OSF. METHODS: Western blot analyses were used to study the effects of S1P on CCN2 expression and its signaling pathways in HBFs and whether epigallocatechin-3-gallate (EGCG), the main and most significant polyphenol in green tea, could inhibit this pathway. RESULTS: S1P significantly enhanced CCN2 synthesis in HBFs. This effect can be inhibited by c-Jun NH2-terminal kinase (JNK) inhibitor and extracellular signal-regulated kinase inhibitor but not by P38 mitogen-activated protein kinase inhibitor. Interestingly, EGCG completely blocked S1P-induced CCN2 expression via suppressing S1P-induced JNK phosphorylation. CONCLUSION: S1P released by repetitive mechanical trauma during AN chewing may contribute to the pathogenesis of OSF through upregulating CCN2 expression in HBFs. EGCG could be an adjuvant to the current offered therapy options or the prevention of OSF through suppression of JNK activation.

Significant reduction of serum homocysteine level and oral symptoms after different vitamin-supplement treatments in patients with burning mouth syndrome.

BACKGROUND: Serum homocysteine level is a biomarker of cardiovascular disease. METHODS: In this study, 399 primary and secondary burning mouth syndrome (BMS) patients without or with hematinic deficiencies were treated with vitamin BC capsules plus none, one, or two deficient hematinics depending on the corresponding deficiency statuses of the patients. One hundred and seventy-seven patients showed complete remission of all oral symptoms after treatment. The blood homocysteine, vitamin B12, folic acid, iron, and hemoglobin concentrations at baseline and after treatment till all oral symptoms had disappeared in these 177 complete-response BMS patients were measured and compared by paired t-test. RESULTS: For BMS patients with concomitant deficiencies of vitamin B12 only (n = 48), folic acid only (n = 12), vitamin B12 plus folic acid (n = 9), or vitamin B12 plus iron (n = 15), supplementations with vitamin BC capsules plus corresponding deficient hematinics could significantly reduce the abnormally high serum homocysteine levels to normal levels after a mean treatment period of 5.4-8.2 months (all P-values < 0.01). For BMS patients without definite hematinic deficiencies (n = 62), supplementation with vitamin BC capsules only could also significantly decrease the relatively higher homocysteine levels to significantly lower levels after a mean treatment period of 10.2 months (P < 0.001). CONCLUSION: Specific supplementations with vitamin BC capsules plus none or corresponding deficient vitamin B12 and/or folic acid can reduce the abnormally high serum homocysteine levels to normal levels in BMS patients without or with deficiencies of corresponding hematinics.

5-aminolevulinic acid induce apoptosis via NF-κB/JNK pathway in human oral cancer Ca9-22 cells.

BACKGROUND: 5-aminolevulinic acid-based photodynamic therapy (5-ALA-PDT) is being used to treat oral pre-cancerous and cancerous lesions with some encouraging clinical outcomes. However, the exact mechanisms behind the photodynamic treatment are still not fully elucidated. METHOD: Flow cytometry, TdT-mediated dUTP nick end labeling assay and Western blot analysis were used to investigate the effects of 5-ALA-PDT on human oral cancer Ca9-22 cells. RESULTS: We found that 5-ALA-PDT induces apoptosis in Ca9-22 cells. Western blotting showed that 5-ALA-PDT activates both the caspase-8 and caspase-9 pathways, which differed from previous studies conducted in other cell types. Activation of JNK was evident as early as 30 min. The caspases activation was inhibited by JNK inhibitor SP600125. Treatment with NF-κB inhibitor Bay 11-7082 (Bay) completely abrogated ALA-PDT-induced JNK activation. In addition, Bay and SP600125 almost completely abolished ALA-PDT-induced apoptosis. CONCLUSION: These results demonstrate significant involvement of caspase-8 and -9 and their upstream NF-κB-JNK pathways in ALA-PDT-induced apoptosis. Future studies on how NF-κB and JNK activity regulate ALA-PDT response should provide a better strategy for the treatment of oral cancer.

Topical photodynamic therapy is very effective for oral verrucous hyperplasia and oral erythroleukoplakia.

BACKGROUND: Oral verrucous hyperplasia (OVH) and oral erythroleukoplakia (OEL) are two oral precancerous lesions with relatively high malignant transformation potential. One of the best cancer prevention strategies is to use a conservative and effective treatment modality to eliminate oral precancers to stop their further malignant transformation. Our previous studies have shown that the topical 5-aminolevulinic acid-mediated photodynamic therapy (topical ALA-PDT) using the 635-nm light-emitting diode (LED) light is very effective for OVH and OEL lesions. METHODS: Because the laser machine is a more-popular light source than the LED device in PDT clinics, in this study 40 OVH and 40 OEL lesions were treated once a week with the same PDT protocol but using the 635-nm laser light to evaluate whether this laser light-mediated topical ALA-PDT was also effective for OVH and OEL lesions. RESULTS: We found that all the 40 OVH lesions exhibited complete response (CR) after an average of 3.6 PDT treatments. Of the 40 OEL lesions, 38 showed CR after an average of 3.4 PDT treatments and two showed partial response (PR). Better PDT outcomes were significantly associated with OVH and OEL lesions with the smaller size, pink to red color, epithelial dysplasia, or thinner surface keratin layer. CONCLUSION: This study indicates that the laser light-mediated topical ALA-PDT is also very effective for OVH and OEL lesions. Therefore, we suggest that topical ALA-PDT using either the LED or laser light may serve as the first-line treatment of choice for OVH and OEL lesions.

Comparison of clinical outcomes of oral erythroleukoplakia treated with photodynamic therapy using either light-emitting diode or laser light.

BACKGROUND AND OBJECTIVES: Topical 5-aminolevulinic acid-mediated photodynamic therapy (topical ALA-PDT) using a 635-nm light-emitting diode (LED) light is an effective treatment modality for oral verrucous hyperplasia. This study tested whether topical ALA-PDT using either the LED or laser light was also an effective treatment modality for oral erythroleukoplakia (OEL) lesions. STUDY DESIGN/MATERIALS AND METHODS: In this prospective but non-randomized study, 20 OEL lesions were treated with topical ALA-PDT using the 635-nm LED light and 26 OEL lesions were treated with topical ALA-PDT using the 635-nm laser light. The difference in clinical outcomes was compared between the two groups by Fisher exact test. RESULTS: We found that the 20 LED light-treated OEL lesions showed complete response (CR) in 17 and partial response (PR) in 3. The 17 CR OEL lesions required an average of 3.7 (range, 2-7) treatments of ALA-PDT to achieve CR of the lesions. The 26 laser light-treated OEL lesions showed CR in 25 and PR in 1. The 25 CR OEL lesions needed an average of 3.3 (range, 2-6) treatments of ALA-PDT to achieve CR of the lesions. There was no significant difference in PDT outcomes between the 20 LED light-treated and 26 laser light-treated OEL lesions (P = 0.303). When the 42 CR OEL lesions were pooled together, we found that smaller lesions (greatest diameter <1.5 cm) and lesions with thinner surface keratin (keratin layer < or =30 microm) needed significantly fewer mean treatment number of PDT to achieve a CR than the larger lesions (P = 0.000) and lesions with thicker surface keratin (P = 0.000), respectively. CONCLUSIONS: Topical ALA-PDT using either the LED or laser light is an effective treatment modality for OEL lesions. There is no significant difference in clinical outcomes of OEL lesions treated with PDT using either the LED or laser light.

Photodynamic Therapy of oral dysplasia with topical 5-aminolevulinic acid and light-emitting diode array.

BACKGROUND AND OBJECTIVES: In Taiwan, more than two million people have the betel quid (BQ) chewing habit which is a risk factor related to premalignant lesion and squamous cell carcinoma of oral cavity. We developed a light-emitting diode (LED) array combined with topical 5-aminolevulinic acid (ALA) for photodynamic therapy (PDT) and evaluated its effectiveness for the treatment of oral lesions. STUDY DESIGN/MATERIALS AND METHODS: We compared the ALA-PDT effect of the homemade LED array to that of a commercial light source on cultured Ca9-22 human gingival carcinoma cells and the DMBA-induced hamster buccal pouch carcinoma model. Furthermore, we treated several patients having an oral lesion using a topical ALA delivery system and the LED array. RESULTS: The LED array light source was as effective as the commercial light source for ALA-PDT in cultured Ca9-22 cells with LD(50) of 4.5 and 4.3 J/cm(2), respectively, using an MTT assay. This light source was also effective in the DMBA-induced hamster buccal pouch carcinoma model, and in the patients of oral leukoplakia. CONCLUSIONS: ALA-PDT is effective for premalignant lesions such as mucosal dysplasia and carcinoma in situ of oral cavity. Good results could be obtained by using the homemade LED array as light source. The LED array has the advantages of low cost, high reliability, and portability. It is safe, convenient and easy to use for the treatment of oral dysplasia.

Antioxidative and antiplatelet effects of aqueous inflorescence Piper betle extract.

Piper betle, belonging to the Piperaceae family, is a tropical plant, and its leaf and inflorescence are popularly consumed by betel quid (BQ) chewers in Taiwan and many other South and Southeast Asian countries. However, little is known about the biochemical properties of inflorescence Piper betle (IPB) toward reactive oxygen species (ROS) and platelet functions. In the present work, aqueous IPB extract was shown to be a scavenger of H(2)O(2), superoxide radical, and hydroxyl radical with a 50% inhibitory concentration (IC(50)) of about 80, 28, and 73 microg/mL, respectively. IPB extract also prevented the hydroxyl radical induced PUC18 plasmid DNA breaks at concentrations higher than 40 microg/mL. Since ROS are crucial for platelet aggregation, we further found that IPB extract also inhibited the arachidonic acid (AA) induced and collagen-induced platelet aggregation, with an IC(50) of 207 and 335 microg/mL, respectively. IPB extract also inhibited the AA-, collagen- (>100 microg/mL of IPB), and thrombin (>250 microg/mL of IPB)-induced thromboxane B(2) (TXB(2)) production by more than 90%. However, IPB extract showed little effect on thrombin-induced aggregation. These results indicated that aqueous components of IPB are potential ROS scavengers and may prevent the platelet aggregation possibly via scavenging ROS or inhibition of TXB(2) production.