title: Modulation of circadian rhythm of DNA synthesis in tumor cells by inhibiting platelet-derived growth factor signaling.
abstract: Circadian synchronization of cell proliferation is observed not only in normal healthy tissues but also in malignant solid tumors. However, the proliferation rhythm of tumor cells is often different from that of normal cells. We reported here that the peculiar rhythm of tumor cell proliferation was modulated by inhibition of platelet-derived growth factor (PDGF) signaling. DNA synthesis in tumor cells implanted in mice showed a 24-h oscillation apparently differing from that of normal bone marrow cells. Continuous administration of AG1295 (10 microg/h, s.c.), a PDGF receptor tyrosine kinase inhibitor, substantially suppressed DNA synthesis in the implanted tumor cells but not in the healthy bone marrow cells. During the administration of this drug, the rhythm of DNA synthesis in the tumor cells was synchronized with that in bone marrow cells. The present results suggest that the circadian rhythm of DNA synthesis in tumor cells is modulated by PDGF receptor signaling, which is activated following tumor progression. Because the rhythmic patterns of clock gene expression in tumor cells did not differ significantly from those in other healthy tissues, the enhanced signal transduction of PDGF receptor may cause an alteration in the rhythmicity of tumor cell proliferation without changing in the intracellular molecular clockwork.
authors.affiliation: Pharmaceutics, Division of Clinical Pharmacy, Department of Medico-Pharmaceutical Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Satoru
authors.initials: S
authors.lastname: Koyanagi
authors.forename: Yukako
authors.initials: Y
authors.lastname: Kuramoto
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoshizumi
authors.forename: Naoya
authors.initials: N
authors.lastname: Matsunaga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimeno
authors.forename: Shinji
authors.initials: S
authors.lastname: Soeda
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Ohdo
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects*; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012510:Sarcoma 180 / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects; D020032:Tyrphostins / Q000494:pharmacology*
chemical_list: C407689:6,7-dimethoxy-2-phenylquinoxaline; D010982:Platelet-Derived Growth Factor; D020032:Tyrphostins; D004247:DNA