Growth inhibition and induction of apoptosis by flavopiridol in rat lung adenocarcinoma, osteosarcoma and malignant fibrous histiocytoma cell lines.
Flavopiridol is the potent inhibitor of cdks sharing its function with endogenous cdk inhibitors, and causes arrest at both the G1 and G2 phases of the cell cycle resulting in apoptosis in various tumor cell lines. Cyclin-dependent kinase inhibitor p16INK4a induces cell cycle arrest in G1 or G2 or both, and is inactivated in many malignant tumors. In this study, we focused on the effects of flavopiridol on chemically-induced rat lung adenocarcinoma, osteosarcoma and malignant fibrous histiocytoma (MFH) cell lines showing different pattern of p16INK4a status. The data demonstrated that flavopiridol inhibited cellular growth in a dose- and time-dependent manner, inducing apoptosis within 24 h in all cell lines at a concentration of 300 nM. The growth inhibition rate was the greatest for lung adenocarcinoma cells, lacking p16INK4a expression associated with methylation-mediated gene silencing; 83% at a concentration of 300 nM for 72-h treatment; while the growth of osteosarcoma and MFH cells, both expressing p16INK4a, were inhibited at similar levels; 54-61% for osteosarcoma and 61-64% for MFH cell lines. Then, we further investigated the influence of p16INK4a induction upon the effect of flavopiridol in p16INK4a-deficient lung adenocarcinoma cells. 5-aza 2'-deoxycytidine (5-Aza-CdR) induced p16INK4a expression and inhibited cellular growth in lung adenocarcinoma at a similar level to that with flavopiridol treatment. After the induction of p16INK4a expression by 5-Aza-CdR, the growth inhibition rates of flavopiridol in the p16INK4a-induced lung adenocarcinoma cells could not achieve comparable inhibition to that in the p16INK4a-deficient cells; the efficacy was reduced compared to original p16INK4a-deficient cells at each concentration of 50, 100 and 500 nM for 72-h treatment. These data indicate that flavopiridol shows cell type specific inhibition and possibly acts in a more compensatory manner for endogenous p16INK4a function in tumor cells having the aberrations of p16INK4a gene.
Honoki
Kanya
K
Department of Orthopedic Surgery, Nara Medical University, Kashihara, Nara 634-8522, Japan. kahonoki@naramed-u.ac.jp
Yoshitani
Kazuhiro
K
Tsujiuchi
Toshifumi
T
Mori
Toshio
T
Tsutsumi
Masahiro
M
Morishita
Toru
T
Takakura
Yoshinori
Y
Mii
Yoshio
Y
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000235:genetics; D051358:Cyclin-Dependent Kinase 4; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D018844:Cyclin-Dependent Kinases / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology* / Q000627:therapeutic use; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018219:Histiocytoma, Benign Fibrous / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D012516:Osteosarcoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D010880:Piperidines / Q000494:pharmacology* / Q000627:therapeutic use; D011401:Promoter Regions, Genetic / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats
D019941:Cyclin-Dependent Kinase Inhibitor p16; D005419:Flavonoids; D010880:Piperidines; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D019938:Cyclin D1; C077990:alvocidib; C495903:Cdk4 protein, rat; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases