Recent clinical studies have indicated that intra-tumoral gene expression levels of
5-fluorouracil (5-FU) metabolism-related
enzymes may predict the clinical response of several
cancers to 5-FU-based
chemotherapy. However, few studies examining
oral squamous cell carcinomas (OSCCs) have been reported. In this study, we determined the expression levels of
5-FU metabolism-related
enzymes like
thymidylate synthase (TS),
dihydropyrimidine dehydrogenase (DPD),
thymidine phosphorylate (TP) and orotate phosphoribosyl
transferase (OPRT) using reverse transcription-polymerase chain reaction (RT-PCR) combined with
laser capture microdissection (LCM). We also evaluated the correlation between the
mRNA expressions of these genes and clinico-pathological factors or the treatment effects of 5-FU-based
chemotherapy combined with
radiotherapy in 27 patients with OSCC. No significant correlation was observed between the
mRNA expression levels of any of the examined genes and the T-stage, N-stage, differentiation grade or mode of
tumor invasion. Although TS and OPRT
mRNA were not correlated with the histopathological effects and the development of
tumor recurrence, DPD and TP
mRNA were significantly correlated with the histopathological effects and
tumor recurrence. A significant positive correlation was also observed between the expression of TS and DPD
mRNA, but no other correlations were observed among the other genes. Our results suggest that the combined evaluation of TP and DPD
mRNA expression in
tumor cells using LCM and RT-PCR may be a useful predictor of the efficacy of 5-FU-based
chemotherapy combined with
radiotherapy in patients with OSCC.