title: Impacts of autophagy-inducing ingredient of areca nut on tumor cells.
abstract: Areca nut (AN) is a popular carcinogen used by about 0.6-1.2 billion people worldwide. Although AN contains apoptosis-inducing ingredients, we previously demonstrated that both AN extract (ANE) and its 30-100 kDa fraction (ANE 30-100K) predominantly induce autophagic cell death in both normal and malignant cells. In this study, we further explored the action mechanism of ANE 30-100K-induced autophagy (AIA) in Jurkat T lymphocytes and carcinoma cell lines including OECM-1 (mouth), CE81T/VGH (esophagus), SCC25 (tongue), and SCC-15 (tongue). The results showed that chemical- and small hairpin RNA (shRNA)-mediated inhibition of AMP-activated protein kinase (AMPK) resulted in the attenuation of AIA in Jurkat T but not in OECM-1 cells. Knockdown of Atg5 and Beclin 1 expressions ameliorated AIA in OECM-1/CE81T/VGH/Jurkat T and OECM-1/SCC25/SCC-15, respectively. Furthermore, ANE 30-100K could activate caspase-3 after inhibition of Beclin 1 expression in OECM-1/SCC25/SCC15 cells. Meanwhile, AMPK was demonstrated to be the upstream activator of the extracellular-regulated kinase (ERK) in Jurkat T cells, and inhibition of MEK attenuated AIA in Jurkat T/OECM-1/CE81T/VGH cells. Finally, we also found that multiple myeloma RPMI8226, lymphoma U937, and SCC15 cells survived from long-term non-cytotoxic ANE 30-100K treatment exhibited stronger resistance against serum deprivation through upregulated autophagy. Collectively, our studies indicate that Beclin-1 and Atg5 but not AMPK are commonly required for AIA, and MEK/ERK pathway is involved in AIA. Meanwhile, it is also suggested that long-term AN usage might increase the resistance of survived tumor cells against serum-limited conditions.
authors.affiliation: Department of Dentistry, Taipei Medical University, Taipei, Taiwan; Department of Dentistry, National Defense Medical Center, Taipei, Taiwan; Oral and Maxillofacial Surgery Section, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Yen
authors.affiliation: Oral and Maxillofacial Surgery Section, Chi Mei Hospital, Liouying, Taiwan; School of Dentistry, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wei-Fan
authors.initials: WF
authors.lastname: Chiang
authors.affiliation: Department of Dentistry, Taipei Medical University, Taipei, Taiwan; Department of Dentistry, National Defense Medical Center, Taipei, Taiwan; Oral and Maxillofacial Surgery Section, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Shyun-Yeu
authors.initials: SY
authors.lastname: Liu
authors.affiliation: Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Oral and Maxillofacial Surgery Section, Chi Mei Hospital, Liouying, Taiwan.
authors.forename: Kuo-An
authors.initials: KA
authors.lastname: Liao
authors.affiliation: Oral and Maxillofacial Surgery Section, Chi Mei Hospital, Liouying, Taiwan.
authors.forename: Che-Yi
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy, Tainan, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Wan-Fang
authors.initials: WF
authors.lastname: Hsieh
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy, Tainan, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Yon-Chi
authors.initials: YC
authors.lastname: Cheng
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy, Tainan, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Kai-Cheng
authors.initials: KC
authors.lastname: Hsu
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy, Tainan, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Pin-Yen
authors.initials: PY
authors.lastname: Lin
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Tai-Chi
authors.initials: TC
authors.lastname: Chen
authors.affiliation: Oral and Maxillofacial Surgery Section, Chi Mei Hospital, Liouying, Taiwan.
authors.forename: I-Ling
authors.initials: IL
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy, Tainan, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Mei-Huei
authors.initials: MH
authors.lastname: Lin
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan; Division of Natural Science, College of Liberal Education, Shu-Te University, Kaohsiung, Taiwan.
authors.forename: Young-Chau
authors.initials: YC
authors.lastname: Liu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001114:Areca / Q000737:chemistry*; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D019169:Jurkat Cells; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009055:Mouth / Q000187:drug effects / Q000378:metabolism; D009062:Mouth Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D009754:Nuts / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology*; D020298:U937 Cells; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C502778:ATG5 protein, human; D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D010936:Plant Extracts; D055372:AMP-Activated Protein Kinases; D053148:Caspase 3