Bingxiu Xiao

Differential expression of microRNA species in human gastric cancer versus non-tumorous tissues

Background and Aim:  MicroRNAs (miRNAs) play important roles in carcinogenesis. The global miRNA expression profile of gastric cancer has not been reported. The purpose of the present study was to determine the miRNA expression profile of gastric cancer.

Using circular RNA as a novel type of biomarker in the screening of gastric cancer.

BACKGROUND Circular RNAs (circRNAs), a class of endogenous RNAs, have emerged as an enigmatic class of RNAs. Little is known about their value in the diagnosis of cancers. METHODS The targeted circRNA of this study was selected using two circRNA databases: CircBase (http://circbase.org/) and circ2Traits (http://gyanxet-beta.com/circdb/). Divergent primers, rather than commonly used convergent primers, for the circRNA were designed. The circRNA levels in 101 paired gastric cancer tissues and adjacent nontumorous tissues from surgical gastric cancer patients and 36 paired plasma samples from preoperative and postoperative gastric cancer patients were analyzed by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The specificity of the amplified products was measured by melting curve analysis and DNA sequencing. To observe the stability of circRNA, three randomly selected samples of gastric cancer tissues were stored at room temperature, 4°C and -20°C, and then, their circRNA levels were analyzed. To verify the reproducibility of qRT-PCR, circRNA levels were detected in a set of specimens (n=15) in two independent experiments with an interval of one day. Then, the correlation of their Ct values was determined. The relationships between circRNA expression levels and clinicopathological factors of patients with gastric cancer were further analyzed by one-way analysis of variance. A receiver operating characteristic (ROC) curve was established to evaluate the diagnostic value. RESULTS Hsa_circ_002059, a typical circular RNA, was first found to be significantly downregulated in gastric cancer tissues compared with paired adjacent nontumorous tissues (p<0.001). Its levels in plasma collected from postoperative gastric cancer patients were found significantly different from those from preoperative gastric cancer patients. The area under the ROC curve was 0.73. Importantly, we further found that lower expression levels were significantly correlated with distal metastasis (P=0.036), TNM stage (P=0.042), gender (P=0.002) and age (P=0.022). The stability of circRNAs and the reproducibility of the qRT-PCR method for detecting circRNA levels were determined. CONCLUSION These results suggested that circRNAs are highly stable in mammalian cells and that one specific circRNA, hsa_circ_002059, may be a potential novel and stable biomarker for the diagnosis of gastric carcinoma.

Detection of circulating tumor cells in peripheral blood from patients with gastric cancer using microRNA as a marker

OBJECTIVE To investigate the feasibility of detecting circulating cancer cells in peripheral blood from gastric cancer patients using Piwi-interacting RNAs (piRNAs) as markers. DESIGN AND METHODS Real-time quantitative reverse transcription-polymerase chain reaction was used to analyze piR-651 and piR-823 levels in the peripheral blood of 93 patients with gastric cancer and 32 healthy volunteers. Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic values. RESULTS The peripheral blood levels of piR-651 and piR-823 in the patients with gastric cancer were significantly lower than those from controls (P<0.001). The piR-651 level in gastric adenocarcinoma was higher than that in gastric signet ring cell carcinoma (P = 0.003). The piR-823 level was positively associated with tumor-node-metastasis stage (P = 0.027) and distant metastasis (P = 0.026). The areas under the ROC curve were 0.841, 0.812 and 0.860 for piR-651, piR-823 and the combination, respectively. CONCLUSIONS piRNAs may be valuable biomarkers for detecting circulating gastric cancer cells.

Long noncoding RNA associated-competing endogenous RNAs in gastric cancer

Some long noncoding RNAs (lncRNAs) play important roles in the regulation of gene expression by acting as competing endogenous RNAs (ceRNAs). However, the roles of lncRNA associated-ceRNAs in oncogenesis are not fully understood. Here, based on lncRNA microarray data of gastric cancer, bioinformatic algorithm miRcode and microRNA (miRNA) targets database TarBase, we first constructed an lncRNA-miRNA-mRNA network. Then, we confirmed it by data of six types of other cancer including head and neck squamous cell carcinoma, prostate cancer, papillary thyroid carcinoma, pituitary gonadotrope tumors, ovarian cancer, and chronic lymphocytic leukemia. The results showed a clear cancer-associated ceRNA network. Eight lncRNAs (AC009499.1, GACAT1, GACAT3, H19, LINC00152, AP000288.2, FER1L4, and RP4-620F22.3) and nine miRNAs (miR-18a-5p, miR-18b-5p, miR-19a-3p, miR-20b-5p, miR-106a-5p, miR-106b-5p, miR-31-5p, miR-139-5p, and miR-195-5p) were involved. For instance, through its miRNA response elements (MREs) to compete for miR-106a-5p, lncRNA-FER1L4 regulates the expression of PTEN, RB1, RUNX1, VEGFA, CDKN1A, E2F1, HIPK3, IL-10, and PAK7. Furthermore, cellular experimental results indicated that FER1L4-small interfering RNA (siRNA) simultaneously suppressed FER1L4 and RB1 mRNA level. These results suggest that lncRNAs harbor MREs and play important roles in post-transcriptional regulation in cancer.

piRNA, the new non-coding RNA, is aberrantly expressed in human cancer cells.

BACKGROUND Piwi-interacting RNAs (piRNAs) are a novel class of non-coding single strand RNAs. They are involved in germline development, in silencing of selfish DNA elements, and in maintaining germline DNA integrity. The relationship between piRNAs and carcinogenesis has not been shown yet. METHODS The relationship between piRNAs and carcinogenesis was identified by microarray screening and real-time quantitative reverse transcription-polymerase chain reaction technology. The piR-651 inhibitor was transfected into gastric cancer cells to assess its influence on cell growth. Cell cycle analysis was used to reveal the cellular mechanisms of piR-651 in the genesis of gastric cancer. RESULTS piR-651 expression was upregulated in gastric cancer tissues compared with paired non-cancerous tissues. The levels of piR-651 were associated with TNM stage (P=0.032). The expression of piR-651 in gastric, colon, lung, and breast cancer tissues was higher than that in paired non-cancerous tissues. The upregulated expression of piR-651 was confirmed in several cancer cell lines including gastric, lung, mesothelium, breast, liver, and cervical cancer cell lines. The growth of gastric cancer cells was inhibited by a piR-651 inhibitor and arrested at the G(2)/M phase. CONCLUSION piR-651 might be involved in the development of gastric cancer and other cancers, and is a potential marker for cancer diagnosis.

Detection of miR-106a in gastric carcinoma and its clinical significance

BACKGROUND MicroRNAs (miRNAs) play important roles in carcinogenesis. miRNA-106a (miR-106a) has oncogenic activity in humans, and often has altered expression. The clinical significance of miR-106a in the diagnosis of gastric carcinoma is poorly understood. METHODS The level of miR-106a in 55 gastric carcinoma and 17 non-tumor tissues was quantified by real-time reverse transcriptase-polymerase chain reaction, and the relationship between miR-106a level and clinical and pathological factors was explored. RESULTS The level of miR-106a in cancer tissues was significantly higher than that in non-tumor tissues, with an average 1.625-fold increase. miR-106a level was significantly associated with tumor stage, size and differentiation; lymphatic and distant metastasis; and invasion (P<0.01). The altered expression of miR-106a was confirmed in gastric cancer cell lines. CONCLUSION miR-106a may be a potential biomarker in the diagnosis of gastric carcinoma.

Long non-coding RNA expression profile in human gastric cancer and its clinical significances.

BackgroundLong non-coding RNAs (lncRNAs) are prevalently transcribed in the genome yet their potential roles in human cancers are not well understood. The aim of the present study was to determine the lncRNA expression profile in gastric cancer and its potential clinical value.MethodsThe global lncRNA expression profile in gastric cancer was measured by lncRNA microarray. Levels of two representative lncRNAs, H19 and uc001lsz, were confirmed by real-time reverse transcriptase-polymerase chain reaction. The relationship between their levels and clinicopathological factors of patients with gastric cancer was explored. A receiver operating characteristic (ROC) curve was constructed for differentiating gastric cancer from benign gastric diseases.ResultsTotal of 135 lncRNAs, which differential expression levels between tumor and non-tumorous tissues were more than twofold, were found (GEO No. GSE47850). The most down-regulated lncRNAs in gastric cancer tissues were FER1L4, uc001lsz, BG491697, AF131784, uc009ycs, BG981369, AF147447, HMlincRNA1600, and AK054588; while the most up-regulated ones were H19, HMlincRNA717, BM709340, BQ213083, AK054978, and DB077273. H19 was found highly expressed in stomach and liver cancer cell lines, while lowly expressed in lung cancer and prostate cancer cell lines. Uc001lsz was lowly expressed in gastric, lung and liver cancer cell lines, while highly expressed in prostate cancer. The areas under ROC curves were up to 0.613, 0.751, and 0.761 for H19, uc001lsz, and the combination, respectively.ConclusionsThe lncRNA expression profile in gastric cancer suggests the potential roles of lncRNAs in gastric cancer occurrence and development. The overexpression of H19 in gastric cancer suggests that H19 may be participated in gastric cancer. The reduced expression of uc001lsz in gastric cancer cell lines and tissues, its associations with TNM stage, and its dysregulation in early cancer and precancerous lesions suggest that uc001lsz may be a potential marker for the diagnosis of early gastric cancer.

piR-823, a novel non-coding small RNA, demonstrates in vitro and in vivo tumor suppressive activity in human gastric cancer cells

Piwi-interacting RNAs (piRNAs), new non-coding small RNAs, are association with chromatin organization, messenger RNA stability and genome structure. However, the roles of piRNA in carcinogenesis are not clearly defined. By using real-time reverse transcription-polymerase chain reaction technology, we found that the expression level of piR-823 in gastric cancer tissues was significant lower than that in non-cancerous tissues. After increase the level of piR-823 in gastric cancer cells, cell growth was inhibited. The results of xenograft nude mice model confirmed its tumor suppressive properties. All of the evidences indicated that piR-823 play a crucial role in the occult of gastric cancer.

MicroRNA-195 and microRNA-378 mediate tumor growth suppression by epigenetical regulation in gastric cancer

The epigenetic regulation of microRNAs is one of several mechanisms underlying carcinogenesis. We found that microRNA-195 (miR-195) and microRNA-378 (miR-378) were significantly down-regulated in gastric cancer tissues and gastric cancer cell lines. The expression of miR-195 and miR-378 in gastric cancer cells was significantly restored by 5-aza-dC, a demethylation reagent. The low expression of miR-195 and miR-378 was closely related to the presence of promoter CpG island methylation. Treatment with miR-195/miR-378 mimics strikingly suppressed the growth of gastric cancer cells whereas promoted the growth of normal gastric epithelial cells. In contrast, administration of miR-195/miR-378 inhibitors significantly prevented the growth of normal gastric epithelial cells. Expression of cyclin-dependent kinase 6 and vascular endothelial growth factor was down-regulated by exogenous miR-195 and miR-378, respectively. In conclusion, miR-195 and miR-378 are abnormally expressed and epigenetically regulated in gastric cancer cell lines and tissues via the suppression of CDK6 and VEGF signaling, suggesting that miR-195 and miR-378 have tumor suppressor properties in gastric cancer.

Down-regulation of miR-31 expression in gastric cancer tissues and its clinical significance

MicroRNAs (miRNAs) are non-coding RNAs that regulate the expression of target mRNAs. Altered expression of specific miRNAs in several tumor types has been reported. However, the expression levels of miR-31 in gastric cancers are unclear. The objective of the present study was to compare the expression profile of miR-31 between gastric cancer tissues and non-tumor tissues. Real-time quantitative reverse transcription-polymerase chain reaction technology was used to detect the levels of miR-31 expression. The expression levels of miR-31 in gastric cancer tissues were significantly lower than those in non-tumor tissues. This new information may help to clarify the molecular mechanisms involved in gastric carcinogenesis and to indicate that miR-31 may be a novel diagnostic biomarker of gastric cancer.