HPV E6 down-regulation and apoptosis induction of human cervical cancer cells by a novel lipid-soluble extract (PE) from Pinellia pedatisecta Schott in vitro.
OBJECTIVE
To evaluate the cytotoxicity and apoptosis induction effects of a novel lipid-soluble extract (PE) from Pinellia pedatisecta Schott on CaSki, HeLa and HBL-100 cells. Particularly, the effect of PE on HPV E6 gene expression was tested, and the mechanism of its apoptosis induction effect was also studied.


METHODS
Cell viability was measured by the MTT assay. DAPI staining and flow cytometric analysis (FCM) were used to identify apoptotic cells in PE-treated CaSki, HeLa, and HBL-100 cells. Expression of the HPV E6 gene in CaSki and HeLa cells was detected by real-time RT-PCR and western blot analysis. Apoptosis-associated genes were examined by RT-PCR and western blot analysis in CaSki cells.


RESULTS
PE inhibited the growth of CaSki and HeLa cells in a time- and dose-dependent manner, but it had no obvious inhibiting effect on HBL-100 cells except at a relatively high dose (500 μg/mL). PE could induce apoptosis in CaSki and HeLa cells in a time-dependent manner but not in HBL-100 cells. HPV E6 mRNA and protein were decreased significantly by PE. Caspase-8, caspase-3, Bax, P53 and P21 mRNAs as well as proteins were increased while Bcl-2 mRNA and protein were decreased significantly by 24 h of PE treatment.


CONCLUSIONS
PE can function as a tumor suppressor by inducing apoptosis in human cervical cancer cells but it has little side effect on normal cells. It probably acts via mitochondria-dependent and death receptor-dependent apoptotic pathways. HPV E6 may be the key target of its action.
Li
Gui-Ling
GL
Obstetrics and Gynecology Hospital, Fudan University, 419 FangXie Road, Shanghai 200011, PR China.
Jiang
Wei
W
Xia
Qing
Q
Chen
Song-Hua
SH
Ge
Xi-Rui
XR
Gui
Sui-Qi
SQ
Xu
Cong-Jian
CJ
D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009856:Oncogene Proteins, Viral / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D030021:Pinellia / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027343:Rhizome / Q000737:chemistry; D012995:Solubility; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000378:metabolism / Q000473:pathology / Q000821:virology
D000972:Antineoplastic Agents, Phytogenic; D004365:Drugs, Chinese Herbal; C118860:E6 protein, Human papillomavirus type 6; D008055:Lipids; D009856:Oncogene Proteins, Viral