| BackgroundGastric cancer is the second leading cause of cancerinduced death, and is the most common gastrointestinal malignancy. Although in recent years diagnosticand treatment measures like endoscopy, surgery, chemotherapy, targeted therapy etc had made certain improvement, the5-year survival rate of gastric cancer is still less than 30%. Previous studies focus on genomics, epigenetics, proteomics, protein regulation network, etc. Some research result has been used in clinical practice, Such as the patients with breast cancer may benefit from the application of HER2-targeted therapy. Valid HER2 testing is essential for optimal therapy of patients with HER2-positive gastric cancer and the correct use of first-line chemotherapy. While testing for HER2 status in breast cancer is routinely performed, this is not the case for HER2 testing in gastric cancer and it is usually only performed on clinician request. The current detection is by fluorescence in situ hybridization (FISH) and by immunohistochemistry (IHC).But these measures have limitations. Firstly, a 13% discordancy rate has been reported between the results of IHC and FISH. Secondly, IHC is semi-quantitative and notoriously subjective, while FISH is timeconsuming and expensive. Thirdly, HER2 status might change during trastuzumab therapy and neither IHC nor FISH are effective assays for reflecting the real-time scenario of HER2 status.These problems lead the study come into being.At the same time, with the development of new generation of gene sequencing technology and high-throughput screening method, the function of non-coding RNA started to become resesrch hotsport. Only 2% of human genes are protein coding gene,Non-coding RNAs which with the higher percentage but has been neglected, especially micrornas (miRNA) and long noncoding RNA (IncRNA). MicroRNAs been widely studied in recent years. However, the studies on lncRNA are less. Now few research on the functions of lncRNAs in gastric cancer were reported.So we conducted the study to discover new IncRNAs associated with gastric cancer, which may have potential roles in the diagnosis and treatmentof gastric cancer?Part1 Correlation of serum HER2 with tissue HER2 status in patients with gastric cancer and clinical significanceObjectiveTo investigate the association between serum HER2 extracellular domain(ECD) and tissue HER2 status, and the prognostic value of serum HER2 ECD in patients with gastric cancer.MethodsA total of 239 patients with gastric cancer were enrolled from December 2012 to June 2013. Serum HER2 ECD was determined by chemiluminescent assay, and tissue HER2 status was evaluated by immunohistochemistry (IHC) and fluorescencein situ hybridization (FISH) assay. A receiver operating characteristic (ROC) curve was plotted to identify the optimal cut-off value for serum HER2 ECD assay for predicting survival in gastric cancer patients.ResultsSerum HER2 ECD was significantly correlated with tissue HER2 status (P<0.001), tumor size (P< 0.001), and intestinal type of gastric cancer (P= 0.021). Serum HER2 ECD levels differed significantlybetween patients with HER2-positive tissue expression and those with HER2-negative tissue expression. ROC analysis yielded an area under the curve value of 0.79 (95% confidence interval [CI]: 0.71-0.87, P< 0.001), with a sensitivity and specificity of 0.54 (95% CI: 0.37-0.70) and 0.93 (95% CI: 0.88-0.96),respectively.With a cut-off value of 24.75 ng/mL, high serum HER2 ECD had a negative impact on overall survival (hazard ratio: 1.93 95% CI: 1.32-4.38, P= 0.006).ConclusionsSerum HER2 ECD could be a highly specific surrogate biomarker for tissue HER2 status in gastric cancer. Suitable cut-off criteria for predicting survival should be established.Part 2 The function of over-expressed lncRNAp2819 on gastric cancer cell lineBGC-823Objective To determine the IncRNA expression profile ingastric cancer and its potential clinical values and the function of over-expressed lncRNAp2819 on GC cell line BGC-823.Methods(1) 5 paired gastric cancerand adjacent normal tissue sampleswere tested by LncRNA+mRNA Human Gene Expression Microarray V4.0, qRT-PCRs(quantitative reverse transcription-polymerase chain reaction, qRT-PCR) were performed to confirm the result. The association between IncRNAs and clinical parameters were analyzed.(2)LncRNA-p2819 were selected for functional study, over-expression of LncRNA-p2819 in gastric cancer cell line BGC-82 3 were performed. MTT assay, flow cytometry,Transwell test were used to identify the proliferation, apoptosis, and invasion patterns of gastric cancer cell line.Results(1) We found that there were totally 5445 differentially expressed lncRNAs. 19 up regulated and 56 down regulated IncRNAs with the fold change over 2 and p<0.05. 4 lncRNAs p2819 (down regulated)?P17382 (upregulated )?P24084 (upregulated )?P27873 (upregulated) were selected for qRT-PCR test in 13 paired gastric cancerand adjacent normal tissue samples, the result consistent with that by Microarray. wefound LncRNA p2819 transcript levels were significantly reduced and the reduction correlated with,tumor size, loction and TNM stage.(2)Expression of p2819 was lower in the GC cell line BGC-823 than that in normal GC cell line. Furthermore, using functional expression cloning, we found that overexpression of p2819 in BGC-823 cells inhibited cell proliferation, induced cell apoptosis and arrested cell cycling. At the same time, the migration and invasion potential of BGC-823 cells were inhibited compared to control groups.ConclusionsOur study provided the first evidence that a lot of lncRNAs differentially expressed in gastric cancer. The decrease in p2819 expression is associated with gastric cancer carcinogenesis and progression and overexpression of p2819 can act as a tumor suppressor for GC, providing a potential attractive therapeutic approach for this malignancy. |
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