Effects of smoking and alcohol consumption on 5-fluorouracil-related metabolic enzymes in oral squamous cell carcinoma.

Lifestyle, particularly smoking and alcohol consumption, may induce and/or inhibit drug metabolism. In order to reveal the effects of smoking and alcohol consumption on the 5-fluorouracil (5-FU)-related metabolic enzymes, namely thymidylate synthase, dihydropyrimidine dehydrogenase (DPD; a sole catabolic enzyme of 5-FU), orotate phosphoribosyl transferase (OPRT) and thymidine phosphorylase, in oral squamous cell carcinomas, the mRNA expression of these enzymes was investigated in 29 surgical specimens and compared by the Brinkman index and drinking years. The surgical specimens were divided into normal and tumor regions and were independently analyzed using quantitative reverse transcription-polymerase chain reaction. There was a significantly positive correlation between DPD mRNA expression in these tissues and Brinkman index/drinking years, with OPRT mRNA expression being significantly correlated to the Brinkman index in tumor tissues. These results revealed that lifestyle habits, including smoking and alcohol consumption, may vary the activity of the 5-FU-related metabolic enzymes. DPD is the initial and rate-limiting enzyme in the catabolic pathway of 5-FU. Therefore, smoking and alcohol consumption may reduce the anticancer activity of 5-FU, possibly through the induction of DPD activity.

The effect of neoadjuvant therapy on the 5-fluorouracil metabolic and relative enzymes of oral squamous cell carcinoma.

To assess the effect of neoadjuvant therapy using tegafur/uracil (UFT) and radiation therapy on the 5-fluorouracil (5-FU) metabolic and relative enzymes, thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyl transferase (OPRT) and thymidine phosphorylase (TP) in oral squamous cell carcinoma (OSCC), we examined the mRNA expression and immunohistochemical staining status of these enzymes using 17 surgical specimens. Seven patients did not receive any neoadjuvant therapy and 10 were treated with UFT and local irradiation therapy. Our result showed that the mRNA expression of these enzymes in neoadjuvant group was not significantly different from that of non-treated group using real-time quantitative PCR. To confirm the protein expression, we also carried out immunohistological staining of TS and DPD two key enzymes in the 5-FU metabolism, using the same specimens. Immunohistological staining status did not correspond to the results of mRNA analysis completely, though no significant difference between the groups was observed. Furthermore, no significant relationship between the UFT administration period and mRNA expression of the 5-FU metabolic enzymes was observed in neoadjuvant therapy group and also the distribution of the enzyme mRNA expression levels was similar to that of non-treated group. The results suggested that the neoadjuvant therapy of OSCC might not affect the expression status of 5-FU metabolic and relative enzymes in surgical tumor samples and the tumor tissues might serve as a useful specimen source to analyze the expression status of the 5-FU metabolic and relative enzymes and to determine the prospective efficiency of 5-FU-based adjuvant chemotherapy.

A prostaglandin E2 receptor subtype EP1-selective antagonist, ONO-8711, suppresses 4-nitroquinoline 1-oxide-induced rat tongue carcinogenesis.

We previously reported that certain cyclooxygenase (COX) inhibitors could inhibit chemically induced tongue carcinogenesis. In the present study, we investigated the effects of prostaglandin E(2) (PGE(2)) receptor EP(1)-selective antagonist ONO-8711 on 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis to know whether an EP(1) receptor involves in oral carcinogenesis. Male Fischer 344 rats were given drinking water containing 4-NQO for 8 weeks (20 p.p.m. for the initial 2 weeks, 25 p.p.m. for 2 weeks, and then 30 p.p.m. for 4 weeks). After 4-NQO treatment, animals were given 400 or 800 p.p.m. ONO-8711 containing diets for 23 weeks. The incidence of tongue squamous cell carcinomas (SCC) in the 4-NQO-treated rats was 64%, while that in the rats given ONO-8711 after 4-NQO exposure was 29 (P<0.05) and 29% (P<0.05) in the 400 and 800 p.p.m. of ONO-8711, respectively. The multiplicity of tongue cancer was also smaller in the 4-NQO + ONO-8711 (400 p.p.m. ONO-8711, 0.35 +/- 0.61; and 800 p.p.m. ONO-8711, 0.29 +/- 0.47; P<0.05), when compared with the 4-NQO alone group (0.88 +/- 0.88). Feeding with ONO-8711 significantly reduced PGE(2) level and cell proliferation activity in the non-tumorous epithelium of the tongue. Also, treatment with ONO-8711 resulted in the decrease in EP(1) immunohistochemical expression in the tongue lesions induced by 4-NQO. The results suggest that EP(1) receptor involves in oral carcinogenesis, and that an EP1-selective antagonist ONO-8711 exerts the cancer chemopreventive effects through the suppression of EP(1) expression, PGE(2) biosynthesis and cell proliferation.