Effect of flavopiridol on the proliferation, invasiveness and apoptosis of human prostatic cancer cell line LNCaP / 肿瘤研究与临床

Objective To investigate the effect of flavopiridol on the proliferation,invasiveness and apoptosis of human prostate cancer cell line LNCaP,and to explore the possibility of its application in clinical treatment.Methods MTT assay was used to detect cell proliferation,cell invasion in vitro was detected by Transwell assay,and flow cytometer was used to observe apoptosis.Results Flavopiridol inhibited the growth of LNCaP cells in a concentration-dependent and time-dependent way (P ＜ 0.05),and reduced the ability of invasion capacity.After treated by 10 nmol/L flavopiridol for 24 h,the apoptosis rate was increased significantly to (7.5±0.9) ％ compared with the control group [(5.3±0.5) ％] (P ＜ 0.05).Conclusion Flavopiridol can inhibit proliferation of LNCaP cells and induce apoptosis,which may be applicable for the treatment of prostate cancer.

Glucuronidation of flavopiridol by liver microsomes in Vitro: a species and gender comparison / 中国药学杂志

OBJECTIVE: To study the species-dependent and gender-dependent glucuronidation of flavopiridol by human liver microsomes for providing some useful information to clinical application. METHODS: Ten kinds of liver microsomal (male mouse, rat, guinea pig, dog, human and female mouse, rat, guinea pig, dog, human) incubation systems were used to investigate the UGT (UDP-glucuronosyl transferase) metabolism. The amounts of flavopiridol glucuronides in samples were determined by ultra performance liquid chromatography (UPLC). RESULTS: Flavopiridol was metabolized to flavopiridol glucuronide in each selected kind of microsomes. Species-dependent glucuronidation rates of flavopiridol displayed significant differences in the same gender (P<0.05). Significant difference was observed between the glucuronidation rates of dog and guinea pig (P<0.05), while not observed among those of human, rat and mouse. CONCLUSION: Glucuronidation is the dominant pathway in the metabolism of flavopiridol. There was no significant difference between the glucuronidation rate in human male liver microsomes and that in human female liver microsomes, while the species-dependence was markedly observed.

In Vitro Radiosensitization of Flavopiridol Did Not Translated into In Vivo Radiosensitization / 대한방사선종양학회지

PURPOSE: Flavopiridol enhanced radiation-induced apoptosis of cancer cells in our previous in vitro study. The purpose of this study was to assess if flavopiridol could enhance the radioresponse of mouse mammary tumors in vivo. MATERIALS AND METHODS: Balb/c mice bearing EMT-6 murine mammary carcinoma were treated with flavopiridol only, radiation only, or both for 7 days. Flavopiridol was administered 2.5 mg/kg twice a day intraperitoneally (IP). Radiation was delivered at a 4 Gy/fraction at 24-h intervals for a total dose of 28 Gy. Tumor volume was measured and compared among the different treatment groups to evaluate the in vivo radiosensitizing effect of flavopiridol. Tumors were removed from the mice 20 days after treatment, and TUNEL and Immunohistochemical stainings were performed. RESULTS: Significant tumor growth delay was observed in the radiation only and combined treatment groups, when compared with the control group. However, there was no significant difference between the tumor growth curves of the control and flavopiridol only group or between the radiation only and combination treatment group. Apoptotic cells of different treatment groups were detected by terminal deoxynucleotidyl transferase-medicated nick end labeling (TUNEL) staining. The expressions of Ku70 in tumor tissues from the different groups were analyzed by immunohistochemistry. Similarly, no significant difference was found between the apoptotic rate or Ku70 expression among the different treatment groups. CONCLUSION: Flavopiridol did not show evidence of enhancing the radioresponse of mouse mammary tumors in this study.

Induction of apoptosis by the kinase inhibitor flavopiridol in human ovarian cancer cell lines / 부인종양

OBJECTIVE: Flavopiridol that inhibits cyclin-dependent kinase, can cause cell cycle arrest, induce apoptosis in human tumor cell lines. In the present study, we investigated apoptotic effects of flavopiridol and the underlying molecular mechanisms in human ovarian cancer cell lines. METHODS: We used TOV-21G and TOV-112D cell lines. The cell viability was tested by MTT assay and apoptosis was assessed by TUNEL assay and annexin-V binding. Western blot was used to examine apoptosis related protein levels. MAP kinase activity was analyzed by non-radioactive MAP kinase assay kit. RESULTS: Treatment of TOV-21G and TOV-112D cells with flavopiridol (50 nM to 1000 nM) led to a dose- and time-dependent inhibition of cell growth and survival. Dose-related induction of apoptosis was also observed in these cell lines. Flavopiridol (500 nM) induced striking decreases in the levels of the antiapoptic proteins Mcl-1, Bcl-X(L), and XIAP in both cell lines. In contrast, expression of Bax, Bcl-2, and AIF was not significantly influenced by flavopiridol. Although flavopiridol resulted in accumulation of p53 in both cells, flavopiridol mediated apoptosis was p53 independent because it occurred to the same degree in TOV-112D cells in which p53 was inactivated by mutation. Flavopiridol treatment resulted in enhanced cleavage of pro-caspase 9 and activation of caspase 3. Apoptosis was associated with suppression of ERK activity. CONCLUSION: Although the precise mechanisms of flavopiridol mediated cytotoxicity have not been fully defined, these data suggest that flavopiridol has activity against ovarian cancers in vitro and is worthy of continued clinical development in the treatment of ovarian cancer.

Effect of Flavopiridol on Radiation-induced Apoptosis of Human Laryngeal and Lung Cancer Cells / 대한방사선종양학회지

PURPOSE: To investigate the flavopiridol effect on radiation-induced apoptosis and expression of apoptosis- related genes of human laryngeal and lung cancer cells. MATERIALS AND METHODS: A human laryngeal cancer cell line, AMC-HN3 and a human lung cancer cell line, NCI-H460, were used in the study. The cells were divided into four groups according to the type of treatment: 1) control groups; 2) cells that were only irradiated; 3) cells treated only with flavopiridol; 4) cells treated with flavopiridol and radiation simultaneously. The cells were irradiated with 10 Gy of X-rays using a 4 MV linear accelerator. Flavopiridol was administered to the media at a concentration of 100 nM for 24 hours. We compared the fraction of apoptotic cells of each group 24 hours after the initiation of treatment. The fraction of apoptotic cells was detected by measurement of the sub-G1 fractions from a flow cytometric analysis. The expression of apoptosis-regulating genes, including cleaved caspase-3, cleaved PARP (poly (ADP-ribose) polymerase), p53, p21, cyclin D1, and phosphorylated Akt (protein kinase B) were analyzed by Western blotting. RESULTS: The sub-G1 fraction of cells was significantly increased in the combination treatment group, as compared to cells exposed to radiation alone or flavopiridol alone. Western blotting also showed an increased expression of cleaved caspase-3 and cleaved PARP expression in cells of the combination treatment group, as compared with cells exposed to radiation alone or flavopiridol alone. Treatment with flavopiridol down regulated cyclin D1 expression of both cell lines but its effect on p53 and p21 expression was different according to each individual cell line. Flavopiridol did not affect the expression of phophorylated Akt in both cell lines. CONCLUSION: Treatment with flavopiridol increased radiation-induced apoptosis of both the human laryngeal and lung cancer cell lines. Flavopiridol effects on p53 and p21 expression were different according to the individual cell line and it did not affect Akt activation of both cell lines.

Enhancement of Radiation Effects by Flavopiridol in Uterine Cervix Cancer Cells / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: To determine the effects of combinations of radiation and flavopiridol, an inhibitor of cyclin-dependent kinases and global transcription, in a human uterine cervix cancer cell line. MATERIALS AND METHODS: Human uterine cervix cancer cells (HeLa), cultured to the mid-log phase, were exposed to X-rays, flavopiridol, and combinations of X-rays and flavopiridol in various sequences. The end point in this study was the clonogenic survival, which was measured via clonogenic assays. In order to determine the intrinsic cytotoxicity of flavopiridol, 0, 5, 12.5, 25, 37.5, 50 and 100 nM of flavopiridol were added to cell culture media. In the combination treatment, four different schedules of flavopiridol and irradiation combinations were tested: treatment of flavopiridol for 24 hours followed by irradiation, simultaneous administration of flavopiridol and irradiation, and irradiation followed by flavopiridol (for 24 hours) at intervals of 6 and 24 hours. The fraction of cells surviving after the combination treatment with 2 Gy of radiation (SF2) was compared with that of the fraction of cells surviving after treatment with irradiation alone. RESULTS: The cytotoxicity of flavopiridol was found to be dose-dependent, with an IC50 of 80 nM. No cytotoxic enhancements were observed when flavopiridol and radiation were administered simultaneously. Flavopiridol, administered either 24 hours before or 6 hours after irradiation, exerted no sensitizing effects on the cells. Only one protocol resulted in a radiosensitizing effect: the administration of flavopiridol 24 hours after irradiation. CONCLUSION: Flavopiridol enhanced the effects of radiation on a uterine cervix cancer cell line in vitro, and this enhancement was both sequence- and time-dependent.