title: [Sensitivity of esophageal squamous cell carcinoma cells to rapamycin can be improved by siRNA-interfered expression of p70S6K].
abstract: OBJECTIVE
  To explore the differences in sensitivity to rapamycin of five esophageal squamous cell carcinoma cell lines with different differentiation and the changes of sensitivity of the cells after siRNA-interfered expression of p70S6K.
  
  
  METHODS
  Effects of rapamycin on proliferation of ESCC cell lines with different differentiation, EC9706, TE-1, Eca109, KYSE790 and KYSE450 cells, were investigated using cell counting kit 8 (CCK-8) assay, and according to the above results, the EC9706 cells non-sensitive to rapamycin were chosen to be transfected with p70S6K-siRNA. The changes in sensitivity of cells to rapamycin were measured in vitro and in vivo using CCK-8 kit, flow cytometry and tumor formation in nude mice.
  
  
  RESULTS
  CCK-8 results showed that all the five cell line cells were sensitive to low concentration of rapamycin (<100 nmol/L), but TE-1 and EC9706 cells, which were with poor differentiation, showed resistance to high concentration of rapamycin. After EC9706 cells were treated with 50, 100, 200, 500 and 1 000 nmol/L rapamycin and p70S6K-siRNA, the proliferation rates of EC9706 cells were (48.67 ± 1.68)%, (15.45 ± 1.54)%, (14.00 ± 0.91)%, (10.97 ± 0.72)% and (2.70 ± 0.32)%, respectively, and were significantly lower than that of cells treated with 50, 100, 200, 500 and 1 000 nmol/L rapamycin and control siRNA [(74.53 ± 1.71)%, (68.27 ± 1.35)%, (71.74 ± 2.44)%, (76.23 ± 1.02)% and (80.21 ± 2.77)%] (P<0.05 for all). The results of flow cytometry showed that the ratios of cells in G1 phase of the p70S6K-siRNA, rapamycin and p70S6K-siRNA+ rapamycin groups were (53.82 ± 1.78)%, (57.87 ± 4.01)% and (73.73 ± 3.68)%, respectively, significantly higher than that in the control group (46.09 ± 2.31)% (P<0.05 for all). The results of tumor formation test in vivo showed that the inhibitory effect of rapamycin on tumor growth was stronger after the cells were transfected with p70S6K-siRNA, and the inhibition rate was 96.5%.
  
  
  CONCLUSIONS
  ESCC cells with different differentiation have different sensitivity to rapamycin, and p70S6K-siRNA can improve the sensitivity of cells to rapamycin in vitro and in vivo.
authors.affiliation: Department of Oncology, People's Hospital of Henan Province, Zhengzhou 450003, China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Liu
authors.forename: Zhaoming
authors.initials: Z
authors.lastname: Lu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Yao
authors.initials: Y
authors.lastname: Cui
authors.forename: Jiazhen
authors.initials: J
authors.lastname: Wang
authors.affiliation: Email: hougq@zzu.edu.cn.
authors.forename: Guiqin
authors.initials: G
authors.lastname: Hou
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004938:Esophageal Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000077277:Esophageal Squamous Cell Carcinoma; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D034741:RNA, Small Interfering; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D014162:Transfection
chemical_list: D000903:Antibiotics, Antineoplastic; D034741:RNA, Small Interfering; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020123:Sirolimus