title: Adenosine A2b receptor promotes progression of human oral cancer.
abstract: BACKGROUND
  Adenosine A2b receptor (ADORA2B) encodes an adenosine receptor that is a member of the G protein-coupled receptor superfamily. This integral membrane protein stimulates adenylate cyclase activity in the presence of adenosine. Little is known about the relevance of ADORA2B to human malignancy including oral squamous cell carcinoma (OSCC). We aimed to characterize the expression state and function of ADORA2B in OSCC.
  
  
  METHODS
  The ADORA2B expression levels in nine OSCC-derived cells were analyzed by quantitative reverse transcriptase-polymerase chain reaction and immunoblotting analyses. Using an ADORA2B knockdown model, we assessed cellular proliferation and expression of hypoxia-inducible factor1α (HIF-1α). We examined the adenosine receptor expression profile under both normoxic and hypoxic conditions in the OSCC-derived cells. In addition to in vitro data, the clinical correlation between the ADORA2B expression levels in primary OSCCs (n = 100 patients) and the clinicopathological status by immunohistochemistry (IHC) also was evaluated.
  
  
  RESULTS
  ADORA2B mRNA and protein were up-regulated significantly (p < 0.05) in seven OSCC-derived cells compared with human normal oral keratinocytes. Suppression of ADORA2B expression with shRNA significantly (p < 0.05) inhibited cellular proliferation compared with the control cells. HIF-1α also was down-regulated in ADORA2B knockdown OSCC cells. During hypoxia, ADORA2B expression was induced significantly (p < 0.05) in the mRNA and protein after 24 hours of incubation in OSCC-derived cells. IHC showed that ADORA2B expression in primary OSCCs was significantly (p < 0.05) greater than in the normal oral counterparts and that ADORA2B-positive OSCCs were correlated closely (p < 0.05) with tumoral size.
  
  
  CONCLUSIONS
  Our results suggested that ADORA2B controls cellular proliferation via HIF-1α activation, indicating that ADORA2B may be a key regulator of tumoral progression in OSCCs.
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. porsche_0108@yahoo.co.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kasama
authors.affiliation: Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. end@faculty.chiba-u.jp.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Sakamoto
authors.affiliation: Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. kasamatsua@faculty.chiba-u.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasamatsu
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. onefoot_mactwist@yahoo.co.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okamoto
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. koyamatomoyo4@gmail.com.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Koyama
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. d02a032d@yahoo.co.jp.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Minakawa
authors.affiliation: Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. katsunori.ogawara@faculty.chiba-u.jp.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Ogawara
authors.affiliation: Department of Oral and Maxillofacial Surgery Research Institute, National Defense Medical College Hospital, 3-2, Namiki, Tokorozawa-shi, Saitama, 359-8513, Japan. yokoe@ndmc.ac.jp.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yokoe
authors.affiliation: Department of Medical Oncology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. m.shiiba@faculty.chiba-u.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Shiiba
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. tanzawap@faculty.chiba-u.jp.|Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. tanzawap@faculty.chiba-u.jp.
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanzawa
authors.affiliation: Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. uzawak@faculty.chiba-u.jp.|Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. uzawak@faculty.chiba-u.jp.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Uzawa
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D043704:Receptor, Adenosine A2B / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D043704:Receptor, Adenosine A2B