Nicotine-induced human breast cancer cell proliferation attenuated by garcinol through down-regulation of the nicotinic receptor and cyclin D3 proteins.
Previous studies have demonstrated that the persistent exposure of human bronchial epithelial cells to nicotine (Nic) through nicotinic acetylcholine receptors increases cyclin D1 promoter activity and protein expression. The main purpose of this study is to elucidate the carcinogenic role of cyclin D3, which is involved in breast tumorigenesis when induced by Nic. Real-time PCR analysis revealed that cyclin D3 is highly expressed at the mRNA level in surgically dissected breast tumor tissue, compared to the surrounding normal tissue (tumor/normal fold ratio = 17.93, n = 74). To test whether Nic/nicotinic acetylcholine receptor (nAChR) binding could affect cyclin D3 expression in human breast cancer cells, the transformed cell line MCF-10A-Nic (DOX) was generated from normal breast epithelial cells (MCF-10A) with inducible α9-nAChR gene expression, using the adenovirus tetracycline-regulated Tet-off system. Tet-regulated overexpression of α9-nAChR in MCF-10A-Nic (DOX) xenografted BALB/c-nu/nu mice resulted in a significant induction of cyclin D3. In contrast, cyclin D3 expression was down-regulated in α9-nAChR knock-down (siRNA) MDA-MB-231-xenografted tumors in NOD.CB17-PRKDC(SCID)/J(NOD-SCID) mice. Furthermore, we found that Nic-induced human breast cancer (MDA-MB-231) cell proliferation was inhibited by 1 μM of garcinol (Gar), isolated from the edible fruit Garcinia indica, through down-regulation of α9-nAChR and cyclin D3 expression. These results suggest that α9-nAChR-mediated cyclin D3 overexpression is important for nicotine-induced transformation of normal human breast epithelial cells. The homeostatic regulation of cyclin D3 has the potential to be a molecular target for antitumor chemotherapeutic or chemopreventive purposes in clinical breast cancer patients.
Chen
Ching-Shyang
CS
Department of Surgery and Center of Quality Management and Breast Health Center, Taipei Medical University, Taipei, Taiwan.
Lee
Chia-Hwa
CH
Hsieh
Chang-Da
CD
Ho
Chi-Tang
CT
Pan
Min-Hsiung
MH
Huang
Ching-Shui
CS
Tu
Shih-Hsin
SH
Wang
Ying-Jan
YJ
Chen
Li-Ching
LC
Chang
Yu-Jia
YJ
Wei
Po-Li
PL
Yang
Yi-Yuan
YY
Wu
Chih-Hsiung
CH
Ho
Yuan-Soon
YS
D000328:Adult; D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D056743:Cyclin D3 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D008819:Mice, Nude; D016513:Mice, SCID; D008875:Middle Aged; D009367:Neoplasm Staging; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects; D013729:Terpenes / Q000494:pharmacology*; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; C534696:CCND3 protein, human; D056743:Cyclin D3; D018722:Nicotinic Agonists; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; D013729:Terpenes; D018808:Transcription Factor AP-1; C443079:nAChR alpha9; D009538:Nicotine; C054597:garcinol