Potentially predictive microRNAs of gastric cancer with metastasis to lymph node

AIM:To detect the expression of 60 microRNAs(miRNAs)in gastric cancer tissues and find new predictive biomarkers of gastric cancer with metastasis.METHODS:The expressions of 60 candidate miRNAs in 30 gastric cancer tissues and paired normal tissues were detected by stem-loop real-time reverse transcription-polymerase chain reaction.After primary screening of miRNAs expression,5 selected miRNAs were further testified in another 22 paired gastric tissues.Based on the expression level of miRNAs and the status of metastasis to lymph node(LN),receiver-operating-characteristic(ROC)curve were used to evaluate their ability in predicting the status of metastasis to LN.RESULTS:Thirty-eight miRNAs expressions in gastric cancer tissues were significantly different from those in paired normal tissues(P<0.01).Among them,31miRNAs were found to be up-expressed in cancer tissues and 1 miRNAs were down-expressed≥1.5 fold vs paired normal gastric tissue.Five microRNAs(miR-125a-3p,miR-133b,miR-143,miR-195 and miR-212)were differently expressed between different metastatic groups in 30 gastric cancer biopsies(P<0.05).Partial correlation analysis showed that hsa-mir-212 and hsa-mir-195 were correlated with the status of metastasis to LN in spite of age,gender,tumor location,tumor size,depth of invasion and cell differentiation.ROC analysis indicated that miR-212 and miR-195 have better sensi-tivities(84.6%and 69.2%,respectively)and specifici-ties(both 100%)in distinguishing biopsies with metastasis to LN from biopsies without metastasis to LN.CONCLUSION:miR-212 and miR-195 could be independent biomarkers in predicting the gastric cancer with metastasis to LN.

Depletion of telomerase RNA inhibits growth of gastrointestinal tumors transplanted in mice

AIM: To explore effects of telomerase RNA-targeting phosphorothioate antisense oligodeoxynucleotides (PS-ASODN) on growth of human gastrointestinal stromal tumors transplanted in mice. METHODS: A SCID mouse model for transplantation of human gastrointestinal stromal tumors (GISTs) was established using tumor cells from a patient who was diagnosed with GIST and consequently had been treated with imatinib. GIST cells cultured for 10 passages were used for inoculation into mice. Transfection of PS-ASODN was carried out with Lipotap Liposomal Transfection Reagent. GISTs that subsequently developed in SCID mice were subjected to intratumoral injection once daily from day 7 to day 28 postinoculation, and mice were divided into the following four groups according to treatment: PS-ASODN group (5.00 μmoL/L of oligonucleotide, each mouse received 0.2 mL once daily); imatinib group (0.1 mg/g body weight); liposome negative control group (0.01 mL/g); and saline group (0.01 mL/g). On day 28, the mice were sacrificed, and tumor attributes including weight and longest and shortest diameters were measured. Tumor growth was compared between treatment groups, and telomerase activity was measured by enzyme-linked immunosorbent assay. Apoptosis was examined by flow cytometry. Real-time polymerase chain reaction was used to detect expression of the mRNA encoding the apoptosis inhibition B-cell leukemia/lymphoma 2 (bcl-2 ) gene. RESULTS: In the PS-ASODN group, tumor growth was inhibited by 59.437%, which was markedly higher than in the imatinib group (11.071%) and liposome negative control group (2.759%) [tumor inhibition=(mean tumor weight of control group - mean tumor weight of treatment group)/(mean tumor weight of control group) × 100%]. Telomerase activity was significantly lower (P < 0.01) in the PS-ASODN group (0.689 ± 0.158) compared with the imatinib group (1.838 ± 0.241), liposome negative control group (2.013 ± 0.273), and saline group (2.004 ± 0.163). Flow cytometry revealed that the apoptosis rate of tumor cells treated with PS-ASODN was 20.751% ± 0.789%, which was higher (P < 0.01) than that of the imatinib group (1.163% ± 0.469%), liposome negative control group (1.212% ± 0.310%), and saline group (1.172% ± 0.403%). Expression of bcl-2 mRNA in the transplanted GISTs was markedly downregulated (P < 0.01) in the PS-ASODN group (7.245 ± 0.739) compared with the imatinib group (14.153 ± 1.618) and liposome negative control group (16.396 ± 1.351).CONCLUSION: PS-ASODN can repress GIST growth, mediated perhaps by inhibition of telomerase activity and downregulation of bcl-2 expression.