ABSTRACT
Objective To investigate the activation and clinical significance of the mammalian target of rapamycin (mTOR) pathway related protein and eukaryotic translation factor 4E-binding protein 1 (4E-BP1) in gastric cancer.Methods The activation of mTOR and 4E-BP1 in gastric cancer tissues of 38 surgical patients were detected by immunohistochemical method.The differences of phosphorylated mTOR and 4E-BP1 expression among cancerous tissues,para-cancerous tissues and normal gastric mucosa tissues and dinicopathological variables were analyzed by Chi square test and Kruskal-Wallis test.Results The positive expression rate of phosphorylated mTOR in the gastric cancerous tissues was significantly higher than that of para-cancerous tissues and normal tissues [71.1％ (27/38),50.0 ％ (19/38) and 44.7 ％ (17/38),x2 =11.031,P =0.026].The positive expression rate of downstream protein 4E-BP1 in the gastric cancer tissues was also significantly higher than that of paracancerous tissues and normal tissues [68.4％(26/38),57.9％(22/38) and 28.9％ (11/38),x2 =13.943,P=0.007].There was no correlation between phosphorylated mTOR and 4E-BP1 expression and tumor Lauren's sub-type,infiltration,differentiation degree,lymph node metastasis and patient's age.There was statistical significant difference between activated 4E-BP1 expression and tumor size in gastric cancer (H=3.86,P＜0.05).Conclsions mTOR pathway was over activated in gastric cancer.There was difference between phosphorylation degree of its downstream protein 4E-BP1 and the tumor size.
ABSTRACT
Objective To investigate the combined inhibition effect and the potential mechanism of rapamycin (mammalian target of rapamycin inhibitor) and PD98059 (mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor) on mouse colorectal cancer (CRC). Methods S-ICR mice were subcutaneously injected with 20 mg/kg of 1,2-dimethylhydrazine dihydrochloride in the nape for 20 weeks to induce CRC. From the 16th week, the mice were treated with alone or combined injection with 0.25 mg/kg rapamycin and 2.5 mg/kg PD98059. The drugs were administered for 8 weeks. Subsequently, the animals were sacrificed and dissected, the tumor sizes were measured, and the tumors were harvested for pathological assay. Furthermore, the phosphorylation of mTOR, p70S6K, and 4E-BPl proteins was detected by using immunohistoehemistry. Results The mice treated with rapamycin (44. 44 %) or PD 98059 (either alone (38.89%) or combination treatment (6.67%) were significantly less likely to develop cancer compared with mice receiving none of them (77.78%, P<0. 05). The average size of tumors was (6.15±2. 192), (8.85±3. 983), (2.917±0. 191), (16.36±6.855) mm3 respectively (P<0.05).The anti-cancer effect of the combination treatment was substantially significant. The proteins of phospho-mTOR, phospho-p70s6K and phospho-4E-BPl were significantly down-regulated after treatments (all P values < ,0.05). Conclusions Combined treatment was more effective than single-drug treatments of rapamycin or PD98059 alone for the prevention and treatment of mouse CRC. The mTOR signal pathway might be involved in the inhibitory mechanism.
ABSTRACT
Histone methylation is one of the epigenetic modifications. Histone methylation influences constitutive heterochromatin, genomic imprinting, inactivation of X-chromosome and gene transcription regulation. Abnormality of histone methylation is associated with several carcinomas. The discovery of enzymes that reverse histone methylation challenges the current understanding that histone methylation is a stable epigenetic marker and provides a novel way to study histone modifications.