Effect of 5-fluorouracil and epidermal growth factor on cell growth and dihydropyrimidine dehydrogenase regulation in human uterine cervical carcinoma SKG-IIIb cells.
We previously demonstrated that epidermal growth factor (EGF) induces a decrease in dihydropyrimidine dehydrogenase (DPD), which is the first and rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU), in EGF receptor (EGFR)-positive human SKG-IIIb uterine cervical carcinoma cells, and thereby increased the sensitivity of the cells to 5-FU. In the present study, we examined the individual and combined effects of 5-FU and EGF on growth and DPD activity in SKG-IIIb cells, and also investigated the mode of regulation of DPD activity. The cells showed sensitivity to 5-FU, and growth was stimulated by EGF. When the agents were used in combination, the sensitivity of SKG-IIIb cells to 5-FU was increased roughly sixfold at maximum, as judged in terms of the 50% growth-inhibitory concentration. We then examined the effects of 5-FU and EGF on DPD. Either agent inhibited DPD activity and protein expression in a concentration-dependent manner. Expression of DPD mRNA was concentration-dependently inhibited by treatment with 5-FU and by EGF at a concentration that strongly stimulated cell growth. Further, combination treatment inhibited DPD activity, as well as DPD protein and mRNA expression, more strongly than did treatment with 5-FU or EGF alone. These results suggest that inhibition of DPD activity by EGF or 5-FU is regulated at least at the level of protein expression and that regulation via mRNA is also involved. The above findings indicate that 5-FU and EGF act synergistically in suppressing DPD activity and that the use of 5-FU against tumors in which EGF plays an important role would maximize the potential of 5-FU as an anticancer drug.
Kashima
Naomi
N
Analytical Research Center, Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co., Ltd., Nagaizumi-cho, Sunto-gun, Shizuoka 411-8731, Japan.
Ueda
Masatsugu
M
Kanazawa
Junji
J
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000201:enzymology* / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D017931:DNA Primers / Q000737:chemistry; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005260:Female; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology
D000964:Antimetabolites, Antineoplastic; D017931:DNA Primers; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D004815:Epidermal Growth Factor; D042943:Dihydrouracil Dehydrogenase (NADP); D005472:Fluorouracil