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|Title: ||Effects of andrographolide and taxifolin on cell proliferation, cell cycle progression and apoptosis of prostate carcinoma DU145 cells|
|Other Titles: ||Chuan xin lian nei zhi he hua qi song su dui qian lie xian ai xi bao DU145 zeng zhi, zhou qi he diao wang de ying xiang|
穿心蓮內脂和花旗松素對前列腺癌細胞 DU145 增殖, 週期和凋亡的影響
|Authors: ||Zhang, Zhongrong ( 張鐘融)|
|Department: ||Department of Biology and Chemistry|
|Degree: ||Master of Philosophy|
|Issue Date: ||2011|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Prostate -- Cancer -- Molecular aspects.|
Cancer cells -- Growth -- Regulation.
|Notes: ||CityU Call Number: RC280.P7 Z45 2011|
xviii, 198 leaves : ill. (some col.) 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2011.
Includes bibliographical references (leaves 175-198)
|Abstract: ||Natural products have been playing a domain role in cancer chemotherapy and
prevention in the past 30 years. Traditional Chinese medicine (TCM) with thousands
years of history is a huge source for discovery and investigation of effective natural
herbal products. A lot of compounds isolated or derived from TCM have been
suggested to possess the property of inducing cell cycle arrest, cell differentiation
and apoptosis in various kinds of cancer cells.
Andrographolide (Andro) which is the main bioactive component from
Andrographis paniculata (穿心蓮) has been reported to have many biological
effects including anti-proliferative effect on several tumor cell lines. However, there
is no detailed study about the biological effects of Andro on androgen refractory
prostate cancer cells. Taxifolin (Taxi), a dihydroflavonol belongs to flavonoids
group, together with its glycosides are commonly found in many species of medical
herbs. In recent years, experimental studies have provided growing evidences for the
protective effect of flavonoids against cancer because of their beneficial actions on
multiple cancer-related biological pathways (e.g. carcinogen bioactivation, cellsignaling,
cell cycle regulation, angiogenesis, oxidative stress, inflammation).
Although the reports on flavonoids and cancer are still limited and conflicting, some
protective associations have suggested flavonoid-rich food for cancer protection.
Results in the present study showed that Andro inhibited cell proliferation of
androgen independent prostate cancer cell line DU145 in a time and dosedependent
manner, with the IC50 value (48 h) of 13.70 μM. On the other hand,
Andro exhibited little growth inhibitory effect on noncancerous human fibroblast Hs27 (IC50˃500 μM, 48h). Cell cycle analysis demonstrated that, at low
concentration (˂=40 μM), Andro-treated DU145 cells accumulated at G2/M phase
dose-dependently. Immunoblot of Phospho-Histone H3 (Ser10) antibody (mitotic
marker) further revealed that the G2/M accumulation of DU145 cell was caused by
cell cycle arrest at mitotic phase. Additionally, microtubule network was visualized
by immunostaining of tubulin, which suggested that Andro treatment leaded to the
formation of abnormal spindle-chromosome structure resulting in cell arrest at
prometaphase. However, in vitro microtubule assembly assay indicated that Andro
did not interact directly with microtubule. Double staining of AnnexinV-FITC / PI
showed that Andro also induced apoptosis dose-dependently, with the highest
apoptotic rate after 48-hour treatment. High concentration (80 μM) of Andro
treatment directly induced cell death without a marked alteration of cell cycle
distribution within the first 24 hour. Western blotting analysis revealed that Andro
exposure triggered several cell cycle regulation pathways, including up-regulation
of cyclin B1 and cyclin-dependent kinase (CDK) inhibitor p21(Waf1/Cip1),
dephosphorylation on Tyr15 of Cdc2 and phosphorylation of Wee1, Myt1 and
Cdc25C, which involved in the process of cyclin B/Cdc2 complex activation and
led to cell accumulation in mitosis. Andro-induced apoptosis was associated with
activation and cleavage of poly (ADP-ribose) polymerase (PARP), caspase-7,
caspase-9 and caspase-3 related to mitochondria apoptotic pathway.
Taxi exhibited low anti-proliferative effect on DU145 cell line (IC50˃500 μM, 48 h).
On the other hand, combination of 100 μM Taxi with Andro significantly enhanced
the growth inhibitory effect of the latter on DU145 cells. It was found that
combinated treatments of 100 μM Taxi and Andro (10-40 μM) markedly increased G2/M accumulation in DU145 cells compared to treatments with Andro-alone,
through rising of mitotic index (approximately twice with 20 μM Andro treatment).
Quantification of apoptosis with flow cytometry revealed that Andro-induced
apoptosis and cell death was also promoted potently by synchronous treatment of
Taxi, whereas exposure to Taxi alone did not exhibit marked alteration on cell
morphology, cell cycle distribution or cell viability. Western blotting analysis
revealed that the mitotic rate increased by combination treatment was related to upregulation
of cyclin B/Cdc2 mitotic complex and CDK inhibitor p21; the enhanced
apoptosis was associated with increases of PRAP, caspase-7, and caspase-9
activation. The increase of twisted and elongated mitotic spindle after the combined
treatment suggested that anti-microtubule activity of the two combined compounds
was involved as a remarkable enhanced microtubule polymerization was observed.
This study investigated the biological effect of Andro and Taxi on cell morphology
proliferation, cell cycle, apoptosis in androgen-independent prostate cancer cell
DU145, and the synergetic/additive anticancer effect with combination treatment.
Hence, Andro might be effective on prostate cancer treatment and low cytotoxic
Taxi might be a promising additive in combined drug treatment of prostate cancer.
This study also provided experimental evidences for the potential treatment of
cancer by dietary-flavonoid in combination with anti-cancer compounds.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b4086601|
|Appears in Collections:||BCH - Master of Philosophy |
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