title: Differential susceptibility to hydrogen sulfide-induced apoptosis between PHLDA1-overexpressing oral cancer cell lines and oral keratinocytes: role of PHLDA1 as an apoptosis suppressor.
abstract: Hydrogen sulfide (H2S) is a novel gasotransmitter that plays multiple biological roles in various body systems. In addition to its endogenous production, H2S is produced by bacteria colonizing digestive organs, including the oral cavity. H2S was previously shown to enhance pro-apoptotic effects in cancer cell lines, although the mechanisms involved remain unclear. To properly assess the anti-cancer effects of H2S, however, investigations of apoptotic effects in normal cells are also necessary. The aims of this study were (1) to compare the susceptibility to H2S-induced apoptosis between the oral cancer cell line Ca9-22 and oral keratinocytes that were derived from healthy gingiva, and (2) to identify candidate genes involved in the induction of apoptosis by H2S. The susceptibility to H2S-induced apoptosis in Ca9-22 cells was significantly higher than that in keratinocytes. H2S exposure in Ca9-22 cells, but not keratinocytes, enhanced the expression of pleckstrin homology-like domain, family A, member 1 (PHLDA1), which was identified through a differential display method. In addition, PHLDA1 expression increased during actinomycin D-induced apoptosis in Ca9-22 cells. Knockdown of PHLDA1 expression by small interfering RNA in Ca9-22 cells led to expression of active caspase 3, thus indicating apoptosis induction. The tongue cancer cell line SCC-25, which expresses PHLDA1 at a high level, showed similar effects. Our data indicate that H2S is an anti-cancer compound that may contribute to the low incidence of oral cancer. Furthermore, we demonstrated the role of PHLDA1 as an apoptosis suppressor.
authors.affiliation: Department of Translational Research, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan; Department of Oral Health, School of Life Dentistry, Nippon Dental University, Tokyo 102-0071, Japan. Electronic address: murata-ta@tsurumi-u.ac.jp.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Murata
authors.affiliation: Department of Dental Hygiene, Nippon Dental University College at Tokyo, Tokyo 102-0071, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Oral Health, School of Life Dentistry, Nippon Dental University, Tokyo 102-0071, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kamoda
authors.affiliation: Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Moriyama
authors.affiliation: Department of Oral Maxillofacial Surgery, Nippon Dental University Hospital, Tokyo 102-8158, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kumazawa
authors.affiliation: Department of Translational Research, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hanada
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D009061:Mouth Mucosa / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009062:Mouth Neoplasms / Q000235:genetics* / Q000473:pathology; D034741:RNA, Small Interfering / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C491923:PHLDA1 protein, human; D034741:RNA, Small Interfering; D014157:Transcription Factors; D006862:Hydrogen Sulfide
keywords: 7-AAD; 7-amino-actinomycin D; ACP; ANOVA; Annexin V-PE; Apoptosis susceptibility; H(2)S; Hydrogen sulfide; Oral cancer; PHLDA1; SEM; analysis of variance; annealing control primers; hydrogen sulfide; phycoerythrin-conjugated annexin V; pleckstrin homology-like domain, family A, member 1; siRNA; small interfering RNA; standard error of the mean