Hydroxyflutamide enhances cellular sensitivity to 5-fluorouracil by suppressing thymidylate synthase expression in bicalutamide-resistant human prostate cancer cells.
We investigated the antitumor effects of combination therapy with anti-androgens and 5-fluorouracil (5-FU), and examined the underlying mechanism of the treatment. Initially, we established the bicalutamide-resistant subline CDX25R from the androgen receptor (AR)-positive human prostate cancer cell line LNCaP through continuous exposure to bicalutamide. CDX25R cells lost the ability to respond to androgens, but still expressed AR. They showed significant resistance to bicalutamide, but had high sensitivity to hydroxyflutamide (OH-flutamide) compared with LNCaP cells. The CDX25R subline was thus considered to be a suitable model for prostate cancer that has developed resistance to first-line hormonal therapy but shows sensitivity to an alternative approach. Combined treatment with 5-FU and OH-flutamide had a synergistic effect on CDX25R cells. OH-flutamide decreased expression of the transcription factor E2F1, and subsequently of thymidylate synthase (TS), in CDX25R cells but not in AR-negative DU145 cells. This suggested that OH-flutamide enhanced the growth-inhibitory activity of 5-FU in CDX25R cells by reducing TS expression through the AR pathway. Combined therapy with 5-FU and OH-flutamide may, therefore, be appropriate for patients with prostate cancer that has acquired resistance to initial hormone therapy including bicalutamide.
Tokushima Research Center, Taiho Phermaceutical Co., Ltd., Hiraishi, Kawauchi-cho, Tokushima, Japan. rumi-kawabata@taiho.co.jp
Rumi
R
Kawabata
Shinji
S
Oie
Toshinori
T
Oka
Masayuki
M
Takahashi
Hiroomi
H
Kanayama
Kohji
K
Itoh
D000726:Androgen Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000813:Anilides / Q000627:therapeutic use; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology; D002277:Carcinoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D004357:Drug Synergism; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology*; D005485:Flutamide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D008954:Models, Biological; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy / Q000235:genetics; D009570:Nitriles / Q000627:therapeutic use; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D013940:Thymidylate Synthase / Q000235:genetics* / Q000378:metabolism; D014105:Tosyl Compounds / Q000627:therapeutic use
D000726:Androgen Antagonists; D000813:Anilides; D000964:Antimetabolites, Antineoplastic; D009570:Nitriles; D014105:Tosyl Compounds; C014290:hydroxyflutamide; D005485:Flutamide; C053541:bicalutamide; D013940:Thymidylate Synthase; D005472:Fluorouracil