title: The inhibitory effects of extracellular ATP on the growth of nasopharyngeal carcinoma cells via P2Y2 receptor and osteopontin.
abstract: BACKGROUND
  Nasopharyngeal carcinoma (NPC) is a common malignant tumor observed in the populations of southern China and Southeast Asia. However, little is known about the effects of purinergic signal on the behavior of NPC cells. This study analyzed the effects of ATP on the growth and migration of NPC cells, and further investigated the potential mechanisms during the effects.
  
  
  METHODS
  Cell viability was estimated by MTT assay. Transwell assay was utilized to assess the motility of NPC cells. Cell cycle and apoptosis were detected by flow cytometry analysis. Changes in OPN, P2Y2 and p65 expression were assessed by western blotting analysis or immunofluorescence. The effects of ATP and P2Y2 on promoter activity of OPN were analyzed by luciferase activity assay. The binding of p65 to the promoter region of OPN was examined by ChIP assay.
  
  
  RESULTS
  An MTT assay indicated that ATP inhibited the proliferation of NPC cells in time- and dose-dependent manners, and a Transwell assay showed that extracellular ATP inhibited the motility of NPC cells. We further investigated the potential mechanisms involved in the inhibitory effect of extracellular ATP on the growth of NPC cells and found that extracellular ATP could reduce Bcl-2 and p-AKT levels while elevating Bax and cleaved caspase-3 levels in NPC cells. Decreased levels of p65 and osteopontin were also detected in the ATP-treated NPC cells. We demonstrated that extracellular ATP inhibited the growth of NPC cells via p65 and osteopontin and verified that P2Y2 overexpression elevated the inhibitory effect of extracellular ATP on the proliferation of NPC cells. Moreover, a dual luciferase reporter assay showed that the level of osteopontin transcription was inhibited by extracellular ATP and P2Y2. ATP decreased the binding of p65 to potential sites in the OPN promoter region in NPC cells.
  
  
  CONCLUSIONS
  This study indicated that extracellular ATP inhibited the growth of NPC cells via P2Y2, p65 and OPN. ATP could be a promising agent serving as an adjuvant in the treatment of NPC.
authors: Guang
authors: G
authors: Yang
authors: Shenghong
authors: S
authors: Zhang
authors: Yanling
authors: Y
authors: Zhang
authors: Qiming
authors: Q
authors: Zhou
authors: Sheng
authors: S
authors: Peng
authors: Tao
authors: T
authors: Zhang
authors: Changfu
authors: C
authors: Yang
authors: Zhenyu
authors: Z
authors: Zhu
authors: State Key Laboratory of Oncology in South China, Department of Imaging and Interventional Radiology, Cancer Center, Sun Yat-sen University, Guangzhou Guangdong 510060, China. zhangfj@sysucc.org.cn.
authors: Fujun
authors: F
authors: Zhang
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D020013:Calcium Signaling; D002277:Carcinoma; D045744:Cell Line, Tumor; D002470:Cell Survival; D004354:Drug Screening Assays, Antitumor; D015870:Gene Expression; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms; D053495:Osteopontin / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2 / Q000235:genetics / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C498143:RELA protein, human; D058473:Receptors, Purinergic P2Y2; D051996:Transcription Factor RelA; D053495:Osteopontin; D000255:Adenosine Triphosphate; D051057:Proto-Oncogene Proteins c-akt