title: Expression of the proto-oncogene Pokemon in colorectal cancer--inhibitory effects of an siRNA.
abstract: OBJECTIVE
  This study aimed to investigate expression of the proto-oncogene POK erythroid myeloid ontogenic factor (Pokemon) in colorectal cancer (CRC), and assess inhibitory effects of a small interference RNA (siRNA) expression vector in SW480 and SW620 cells.
  
  
  METHODS
  Semi-quantitative reverse transcription-polymerase chain reaction (PCR) and immunohistochemistry were performed to determine mRNA and protein expression levels of Pokemon in CRC tissues. Indirect immunofluorescence staining was applied to investigate the location of Pokemon in SW480 and SW620 cells. The siRNA expression vectors that were constructed to express a short hairpin RNA against Pokemon were transfected to the SW480 and SW620 cells with a liposome. Expression levels of Pokemon mRNA and protein were examined by real-time quantitative-fluorescent PCR and western blot analysis. The effects of Pokemon silencing on proliferation of SW480 and SW620 cells were evaluated with reference to growth curves with MTT assays.
  
  
  RESULTS
  The mRNA expression level of Pokemon in tumor tissues (0.845 ± 0.344) was significantly higher than that in adjacent tumor specimens (0.321 ± 0.197). The positive expression ratio of Pokemon protein in CRC (87.0%) was significantly higher than that in the adjacent tissues (19.6%). Strong fluorescence staining of Pokemon protein was observed in the cytoplasm of the SW480 and SW620 cells. The inhibition ratios of Pokemon mRNA and protein in the SW480 cells were 83.1% and 73.5% at 48 and 72 h, respectively, compared with those of the negative control cells with the siRNA. In the SW620 cells, the inhibition ratios of Pokemon mRNA and protein were 76.3% and 68.7% at 48 and 72 h, respectively. MTT showed that Pokemon gene silencing inhibited the proliferation of SW480 and SW620 cells.
  
  
  CONCLUSIONS
  Overexpression of Pokemon in CRC may have a function in carcinogenesis and progression. siRNA expression vectors could effectively inhibit mRNA and protein expression of Pokemon in SW480 and SW620 cells, thereby reducing malignant cell proliferation.
authors.affiliation: Department of Gastroenterology, Heping Hospital of Changzhi Medical College, Changzhi, China E-mail : guoruicn@163.com.
authors.forename: Gan-Ting
authors.initials: GT
authors.lastname: Zhao
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Yang
authors.forename: Xi-Xia
authors.initials: XX
authors.lastname: Li
authors.forename: Hui-Lin
authors.initials: HL
authors.lastname: Cui
authors.forename: Rui
authors.initials: R
authors.lastname: Guo
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; C485514:ZBTB7A protein, human