title: Calretinin mediates apoptosis in small cell lung cancer cells expressing tetraspanin CD9.
abstract: A majority of small cell lung cancer (SCLC) cells lack a metastasis suppressor, tetraspanin CD9, and CD9 expression promotes their apoptosis. By a proteomics-based approach, we compared an SCLC cell line with its CD9 transfectant and found that a calcium-binding neuronal protein, calretinin, is upregulated in CD9-positive SCLC cells. Ectopic or anticancer drug-induced CD9 expression upregulated calretinin, whereas CD9 knockdown down-regulated calretinin in SCLC cells. When calretinin was knocked down, CD9-positive SCLC cells revealed increased Akt phosphorylation and decreased apoptosis. These results suggest that CD9 positively regulates the expression of calretinin that mediates proapoptotic effect in SCLC cells.
authors.affiliation: Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan ; Department of Respiratory Medicine, The Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 71004, China.
authors.forename: Ping
authors.initials: P
authors.lastname: He
authors.forename: Hanako
authors.initials: H
authors.lastname: Kuhara
authors.forename: Isao
authors.initials: I
authors.lastname: Tachibana
authors.forename: Yingji
authors.initials: Y
authors.lastname: Jin
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Takeda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tetsumoto
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Minami
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kohmo
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hirata
authors.forename: Ryo
authors.initials: R
authors.lastname: Takahashi
authors.forename: Koji
authors.initials: K
authors.lastname: Inoue
authors.forename: Izumi
authors.initials: I
authors.lastname: Nagatomo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
authors.forename: Takashi
authors.initials: T
authors.lastname: Kijima
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Naka
authors.forename: Eiichi
authors.initials: E
authors.lastname: Morii
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawase
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kumanogoh
keywords: Apoptosis; CD9; Calretinin; KO, knockout; MALDI-TOF, matrix-assisted laser desorption/ionization time-of-flight; NSCLC, nonsmall cell lung cancer; PARP, poly(ADP-ribose)polymerase; PMF, peptide mass fingerprinting; Proteomics; RT-PCR, reverse transcription-PCR; SCLC, small cell lung cancer; Small cell lung cancer; Tetraspanin