ABSTRACT
OBJECTIVES: To investigate the effect of mechanistic target of rapamycin (mTOR)-specific small interfering RNA (siRNA) and rapamycin on tumour size and levels of hypoxia inducible factor 1α(HIF-1α), vascular endothelial growth factor (VEGF) and mTOR proteins, and mTOR mRNA, in a mouse xenograft model of human oesophageal carcinoma. METHODS: Tumours were induced in BALB/c nude mice using the human oesophageal squamous cell carcinoma cell line, EC1, injected subcutaneously. Animals were divided into four treatment groups (n = 5 per group) after 7 days: control (phosphate buffered saline, daily intraperitoneal [i.p.] injection); 50 µg/kg rapamycin, daily i.p. injection; 3 µg/kg mTOR siRNA, daily i.p. injection; combined mTOR siRNA and rapamycin, daily i.p. injections. Tumour volume was measured 21 days after xenograft. Levels of mTOR, VEGF and HIF-1α were assessed via immunohistochemistry and in situ hybridization. RESULTS: mTOR siRNA and/or rapamycin significantly decreased tumour volume and levels of HIF-1α, VEGF and mTOR protein, and mTOR mRNA. Combination treatment was significantly more effective than either treatment alone. CONCLUSIONS: mTOR siRNA and/or rapamycin inhibited the growth of oesophageal carcinoma in vivo. This may represent a novel and effective treatment strategy for oesophageal carcinoma.
Subject(s)
Antibiotics, Antineoplastic/pharmacology , Carcinoma/drug therapy , Esophageal Neoplasms/drug therapy , Sirolimus/pharmacology , TOR Serine-Threonine Kinases/genetics , Animals , Carcinoma/metabolism , Carcinoma/pathology , Cell Line, Tumor , Esophageal Neoplasms/metabolism , Esophageal Neoplasms/pathology , Female , Gene Expression , Gene Knockdown Techniques , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Mice , Mice, Inbred BALB C , Mice, Nude , RNA, Small Interfering/genetics , TOR Serine-Threonine Kinases/antagonists & inhibitors , TOR Serine-Threonine Kinases/metabolism , Tumor Burden/drug effects , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism , Xenograft Model Antitumor AssaysABSTRACT
OBJECTIVE: To investigate the effects of a phosphatase and tensin homologue (PTEN) antisense oligonucleotide on PTEN and mammalian target of rapamycin (mTOR) mRNA and protein, cell proliferation and apoptosis in oesophageal squamous cell carcinoma (OCSS) cell lines. METHODS: EC9706 and EC1 cells were transfected with PTEN antisense oligonucleotide, sense oligonucleotide or nonsense oligonucleotide. Cell proliferation and apoptosis were quantified. Immuno cyto chemistry and in situ hybridization were used to determine PTEN and mTOR protein and mRNA levels, respectively. RESULTS: Transfection with PTEN antisense oligonucleotide dose- and time-dependently enhanced cell proliferation and inhibited apoptosis in both EC9706 and EC1 cells. PTEN mRNA and protein were significantly downregulated, and mTOR protein and mRNA were significantly upregulated. CONCLUSION: These data suggest that PTEN is an important tumour suppressor gene in the development of OSCC.
