title: Betel quid extract promotes oral cancer cell migration by activating a muscarinic M4 receptor-mediated signaling cascade involving SFKs and ERK1/2.
abstract: Betel quid (BQ) is a widely accepted etiological factor for oral squamous cell carcinoma (OSCC) in Southeast Asia, but how BQ chewing leads to oral carcinogenesis remains to be elucidated. We have previously demonstrated that the activation of Src family kinases (SFKs) is critical for BQ-induced oral cancer cell motility. Here we investigate whether this biological effect is mediated by specific membrane receptors in oral cancer cells. We found that BQ-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and cell migration could be inhibited by atropine, suggesting the involvement of the muscarinic receptor family. The enhanced activities of ERK1/2 and cell migration were significantly counteracted by PD102807, the selective antagonist of muscarinic M4 receptor. Moreover, cold BQ extract effectively competed with a known ligand, [(3)H]-N-methyl scopolamine, for binding to muscarinic M4 receptor in vitro, thereby implying that BQ could activate motility-promoting signaling pathways through direct interaction with the receptor. The requirement of muscarinic M4 receptor for BQ-induced oral cancer cell migration was demonstrated by knockdown of the receptor using RNA interference (RNAi). Remarkably, ectopic expression of muscarinic M4 receptor in two oral cancer cell lines, Ca9-22 and SCC-9, further augmented BQ-induced cell migration by 83% and 99%, respectively. Finally, we verified that BQ-induced oral cancer cell migration was mediated through a muscarinic M4 receptor-->SFKs-->ERK1/2 signaling pathway. Thus, our findings have identified a novel signaling cascade mediating BQ-induced oral cancer cell motility, which could be a therapeutic target for BQ-related oral malignancies.
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Taiwan.
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chiu
authors.forename: Bing-Hung
authors.initials: BH
authors.lastname: Chen
authors.forename: Tzyh-Chyuan
authors.initials: TC
authors.lastname: Hour
authors.forename: Wei-Fan
authors.initials: WF
authors.lastname: Chiang
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Wu
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Chen
authors.forename: Hau-Ren
authors.initials: HR
authors.lastname: Chen
authors.forename: Po-Ting
authors.initials: PT
authors.lastname: Chan
authors.forename: Shyun-Yeu
authors.initials: SY
authors.lastname: Liu
authors.forename: Jeff Yi-Fu
authors.initials: JY
authors.lastname: Chen
mesh_terms: D017610:Calcium Compounds / Q000009:adverse effects*; D045744:Cell Line, Tumor; D002465:Cell Movement; D006801:Humans; D008409:Mastication; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009062:Mouth Neoplasms / Q000139:chemically induced* / Q000201:enzymology / Q000473:pathology; D010087:Oxides / Q000009:adverse effects*; D031701:Piper / Q000009:adverse effects*; D010936:Plant Extracts / Q000009:adverse effects*; D043588:Receptor, Muscarinic M4 / Q000819:agonists*; D015398:Signal Transduction
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D010936:Plant Extracts; D043588:Receptor, Muscarinic M4; C495400:lime-piper betel quid; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3