Transfer RNA-derived fragments as novel biomarkers of the onset and progression of gastric cancer.

Gastric cancer (GC) is a particularly malignant disease; thus, early diagnosis and treatment are especially important. Transfer RNA-derived small RNAs (tsRNAs) have been implicated in the onset and progression of various cancers. Therefore, the aim of this study was to explore the role of tRF-18-79MP9P04 (previously named tRF-5026a) in the onset and progression of GC. Expression levels of tRF-18-79MP9P04 were quantified in gastric mucosa specimens of healthy controls and plasma samples of patients with different stages of GC. The results showed that plasma levels of tRF-18-79MP9P04 were significantly decreased in the early and advanced stages of GC. The results of the nucleocytoplasmic separation assay found that tRF-18-79MP9P04 was localized in the nuclei of GC cells. High-throughput transcriptome sequencing identified genes regulated by tRF-18-79MP9P04 in GC cells, and the function of tRF-18-79MP9P04 was predicted by bioinformatics. Collectively, the findings of this study suggest that tRF-18-79MP9P04 would be useful as non-invasive biomarker for early diagnosis of GC and is related to cornification, the type I interferon signaling pathway, RNA polymerase II activities, and DNA binding.

Linc-ROR Regulates POU5F1 and SOX2 by Competitively Binding miR-145-5p to Affect the Proliferation and Migration of Gastric Cancer Cells.

Gastric cancer is the third leading cause of cancer-related deaths worldwide, and research on gastric cancer pathogenesis is fundamental. Long intergenic non-coding RNAs (lincRNAs) control cancer initiation and progression through several mechanisms, with the competitive endogenous RNA (ceRNA) regulatory network being the most common. In this study, in situ hybridization revealed that long intergenic non-protein coding RNA-regulator of reprogramming (linc-ROR) was highly expressed in gastric cancer cells and was mainly cytoplasmic-positive. Cell counting kit-8 (CCK-8), plate colony formation, wound healing, and Transwell assay revealed that linc-ROR knockdown impedes the growth, proliferation, and migration of gastric cancer cells, while linc-ROR overexpression promoted gastric cancer cell growth, migration, and colony formation ability. Combined with previous studies, the molecular mechanism axis of linc-ROR/miR-145-5-5p/POU5F1/SOX2 was verified. The expression of linc-ROR knockdown significantly suppressed the protein expression of POU5F1 and SOX2. Co-transfection with linc-ROR siRNA reverses the carcinogenic effect of the miR-145-5p inhibitor on gastric cancer cell proliferation, cloning, and migration. These findings lay a foundation for developing novel targets for gastric cancer treatment.

Absolute quantification of a plasma tRNA-derived fragment for the diagnosis and prognosis of gastric cancer.

Background: The transition from a healthy gastric mucosa to gastric cancer is a multi-step process. Early screening can significantly improve the survival rate of gastric cancer patients. A reliable liquid biopsy for gastric cancer prediction is urgently needed and since tRNA-derived fragments (tRFs) are abundant in various body fluids, tRFs are possible new biomarkers for gastric cancer. Methods: A total of 438 plasma samples from patients with different gastric mucosal lesions as well as healthy individuals were collected. A specific reverse transcription primer, a forward primer, a reverse primer, and a TaqMan probe were designed. A standard curve was constructed and an absolute quantitation method was devised for detection of tRF-33-P4R8YP9LON4VDP in plasma samples of individuals with differing gastric mucosa lesions. Receiver operating characteristic curves were constructed to evaluate the diagnostic values of tRF-33-P4R8YP9LON4VDP for individual with differing gastric mucosa. A Kaplan-Meier curve was established to calculate the prognostic value of tRF-33-P4R8YP9LON4VDP for advanced gastric cancer patients. Finally, a multivariate Cox regression analysis was performed to assess the independent prognostic value of tRF-33-P4R8YP9LON4VDP for advanced gastric cancer patients. Results: A detection method for plasma tRF-33-P4R8YP9LON4VDP was successfully established. Levels of plasma tRF-33-P4R8YP9LON4VDP were shown to reflect a gradient change from healthy individuals to gastritis patients to early and advanced gastric cancer patients. Significant differences were found among individuals with differing gastric mucosa, with reduced levels of tRF-33-P4R8YP9LON4VDP significantly related to a poor prognosis. tRF-33-P4R8YP9LON4VDP was found to be an independent predictor of an unfavorable survival outcome. Conclusions: In this study, we developed a quantitative detection method for plasma tRF-33-P4R8YP9LON4VDP that exhibited hypersensitivity, convenience, and specificity. Detection of tRF-33-P4R8YP9LON4VDP was found to be a valuable means by which to monitor different gastric mucosa and to predict patient prognosis.

tRNA derived fragments:A novel player in gene regulation and applications in cancer.

The heterogeneous species of tRNA-derived fragments (tRFs) with specific biological functions was recently identified. Distinct roles of tRFs in tumor development and viral infection, mediated through transcriptional and post-transcriptional regulation, has been demonstrated. In this review, we briefly summarize the current literatures on the classification of tRFs and the effects of tRNA modification on tRF biogenesis. Moreover, we highlight the tRF repertoire of biological roles such as gene silencing, and regulation of translation, cell apoptosis, and epigenetics. We also summarize the biological roles of various tRFs in cancer development and viral infection, their potential value as diagnostic and prognostic biomarkers for different types of cancers, and their potential use in cancer therapy.

Extracellular vesicles-associated tRNA-derived fragments (tRFs): biogenesis, biological functions, and their role as potential biomarkers in human diseases.

Traditionally, transfer RNAs (tRNAs) specifically decoded messenger RNA (mRNA) and participated in protein translation. tRNA-derived fragments (tRFs), also known as tRNA-derived small RNAs (tsRNAs), are generated by the specific cleavage of pre- and mature tRNAs and are a class of newly defined functional small non-coding RNAs (sncRNAs). Following the different cleavage positions of precursor or mature tRNA, tRFs are classified into seven types, 5'-tRNA half, 3'-tRNA half, tRF-1, 5'U-tRF, 3'-tRF, 5'-tRF, and i-tRF. It has been demonstrated that tRFs have a diverse range of biological functions in cellular processes, which include inhibiting protein translation, modulating stress response, regulating gene expression, and involvement in cell cycles and epigenetic inheritance. Emerging evidences have indicated that tRFs in extracellular vesicles (EVs) seem to act as regulatory molecules in various cellular processes and play essential roles in cell-to-cell communication. Furthermore, the dysregulation of EV-associated tRFs has been associated with the occurrence and progression of a variety of cancers and they can serve as novel potential biomarkers for cancer diagnosis. In this review, the biogenesis and classification of tRFs are summarized, and the biological functions of EV-associated tRFs and their roles as potential biomarkers in human diseases are discussed.

Establishment of an Absolute Quantitative Method to Detect a Plasma tRNA-Derived Fragment and Its Application in the Non-Invasive Diagnosis of Gastric Cancer.

(1) Transfer RNA (tRNA)-derived fragments (tRFs) are a new category of regulatory non-coding RNAs with distinct biological functions in cancer. They are produced from pre-tRNAs or mature tRNAs and their sequences are relatively short; thus, the amplification of tRFs, especially those in body fluids, is faced with certain technical difficulties. In this study, we established a quantitative method to detect plasma tRF-27-87R8WP9N1E5 (tRF-27) and used it to screen gastric cancer patients. (2) A specific stem-loop-structure reverse transcription primer, a TaqMan probe, and amplification primers for tRF-27 were prepared, and the absolute quantitative method was used to measure plasma tRF-27 levels. To determine the noninvasive diagnostic value of tRF-27 in gastric cancer, plasma tRF-27 levels in patients with benign and malignant lesions (120 healthy individuals, 48 patients with benign lesions, 48 patients with precancerous lesions, and 72 patients with early gastric cancer) were analyzed. Plasma tRF-27 levels were also analyzed in 106 preoperative gastric cancer patients, 106 postoperative gastric cancer patients, and 120 healthy individuals. Survival curves and Cox regression models were established and analyzed. (3) A new absolute quantitative method to determine the plasma tRF-27 copy number was established. Plasma tRF-27 levels were significantly increased in gastric cancer patients compared to healthy individuals, and the area under the receiver operating characteristic curve was 0.7767, when the cutoff value was 724,807 copies/mL, with sensitivity and specificity values of 0.6226 and 0.8917, respectively. The positive predictive and negative predictive values were 83.50% and 72.80%, respectively. Plasma tRF-27 levels in postoperative gastric cancer patients were significantly decreased compared to preoperative gastric cancer patients and tended to the levels of healthy individuals. Moreover, tRF-27 levels were closely related to tumor size and Ki67 expression in gastric cancer patients. Prognostic analysis showed that tRF-27 may be an independent predictor of overall survival. (4) This novel and non-invasive method of measuring plasma tRF-27 levels was valuable in the early diagnosis of gastric cancer.

Ailanthone suppresses the activity of human colorectal cancer cells through the STAT3 signaling pathway.

Ailanthone (AIL) is a major quassinoid extracted from the Chinese medicinal herb, Ailanthus altissima, which has been reported to exert anti­proliferative effects on various cancer cells. The present study aimed to investigate the antitumor effects of AIL on HCT116 and SW620 colon cancer cells, and to analyze the underlying molecular mechanisms. CCK­8 assay was used to detect cell viability. Furthermore, colony formation and Transwell assays, and flow cytometry were used to examine the effects of AIL on cell proliferation, apoptosis and migration. Finally, the expression levels of cell cycle control proteins, and caspase and Bcl­2 family­related proteins involved in the regulation of apoptosis, as well as those of cell migration­ and pathway­related proteins were examined using western blot analysis. Reverse transcription­quantitative PCR was used to quantitatively analyze the changes in the JAK and STAT3 gene levels in each group. The in vitro cell function tests revealed that AIL inhibited the proliferation and migration, and induced the apoptosis and cell cycle arrest of HCT116 and SW620 cells. It was further found exerted these effects via the JAK/STAT3 signaling pathway, as well as through caspase and Bcl­2 family proteins. On the whole, the present study demonstrates that AIL suppresses the activity of colon cancer cells via the STAT3 pathway.

The tRNA-derived fragment 5026a inhibits the proliferation of gastric cancer cells by regulating the PTEN/PI3K/AKT signaling pathway.

BACKGROUND: Recently, tRNA-derived fragments (tRFs) have been shown to serve important biological functions. However, the role of tRFs in gastric cancer has not been fully elucidated. This study aimed to identify the tumor suppressor role of tRF-5026a (tRF-18-79MP9P04) in gastric cancer. METHODS: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was first used to detect tRF-5026a expression levels in gastric cancer tissues and patient plasma. Next, the relationship between tRF-5026a levels and clinicopathological features in gastric cancer patients was assessed. Cell lines with varying tRF-5026a levels were assessed by measuring tRF-5026a using qRT-PCR. After transfecting cell lines with a tRF-5026a mimic or inhibitor, cell proliferation, colony formation, migration, apoptosis, and cell cycle were evaluated. The expression levels of related proteins in the PTEN/PI3K/AKT pathway were also analyzed by Western blotting. Finally, the effect of tRF-5026a on tumor growth was tested using subcutaneous tumor models in nude mice. RESULTS: tRF-5026a was downregulated in gastric cancer patient tissues and plasma samples. tRF-5026a levels were closely related to tumor size, had a certain diagnostic value, and could be used to predict overall survival. tRF-5026a was also downregulated in gastric cancer cell lines. tRF-5026a inhibited the proliferation, migration, and cell cycle progression of gastric cancer cells by regulating the PTEN/PI3K/AKT signaling pathway. Animal experiments showed that upregulation of tRF-5026a effectively inhibited tumor growth. CONCLUSIONS: tRF-5026a (tRF-18-79MP9P04) is a promising biomarker for gastric cancer diagnostics and has tumor suppressor effects mediated through the PTEN/PI3K/AKT signaling pathway.

Clinical diagnostic values of transfer RNA-derived fragment tRF-19-3L7L73JD and its effects on the growth of gastric cancer cells.

Background and aim: Medicine has made great progress, but gastric cancer is still one of the most common malignant tumors worldwide. tRNA-derived fragments (tRFs), a type of small non-coding RNA, have been found to play important roles in cancers. Due to an abundance of modifications, tRFs have the potential to serve as cancer biomarkers. However, the relationship between tRFs and gastric cancer is still largely unclear. We have identified a new tRF, tRF-19-3L7L73JD, found to be expressed at a lower level in gastric cancer patients than healthy controls. Our study aims to explore the diagnostic value of tRF-19-3L7L73JD screening in gastric cancer and to investigate its effects on the growth of gastric cancer cells. Methods: Using quantitative reverse transcription-polymerase chain reaction, we identified tRF-3L7L73JD as differentially expressed in plasma from gastric cancer patients compared to healthy controls. We measured tRF-3L7L73JD levels in plasma from 40 gastric cancer patients and healthy controls. Furthermore, we tested another cohort containing 89 gastric cancer patients and 98 healthy controls to validate our findings. Next, we analyzed the relationship between levels of tRF-19-3L7L73JD in plasma and clinicopathological data of gastric cancer patients, and then evaluated the effects of tRF-19-3L7L73JD on gastric cancer cell growth. Cell proliferation was measured by the Cell Counting Kit-8 and clone formation experiments after transfer with tRF-19-3L7L73JD mimics. The changes in cell migration ability were explored through the scratch and Transwell experiments. Finally, we explored changes in apoptosis and cell cycle by flow cytometry. Results: tRF-19-3L7L73JD showed lower expression in the tested gastric cancer patients. In the validation cohort tRF-19-3L7L73JD was also expressed at low levels in the pre-operative plasma group compared with healthy plasma and post-operative plasma groups. Additionally, a comparison of gastric cancer cell lines with normal gastric epithelial cell lines produced the same result. We found that tRF-19-3L7L73JD expression in patients was related to tumor size. The area under the curve (AUC) was 0.6230, with sensitivity and specificity of 0.4045 and 0.7959, respectively. Cellular function studies revealed that tRF-19-3L7L73JD inhibited cell proliferation and migration, induced apoptosis, and arrested cells at G0/G1 phases, suggesting it may suppress the development of gastric cancer. Conclusion: The results suggest that tRF-19-3L7L73JD may be useful as a biomarker of gastric cancer.

Global profile of tRNA-derived small RNAs in gastric cancer patient plasma and identification of tRF-33-P4R8YP9LON4VDP as a new tumor suppressor.

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) have been found to play important roles in the occurrence and development of cancers. However, the tsRNA profile in gastric cancer is unknown. In this study, we aimed to identify the global tsRNA profile in plasma from gastric cancer patients and elucidate the role of tRF-33-P4R8YP9LON4VDP in gastric cancer. Differentially expressed tsRNAs in the plasma of gastric cancer patients and healthy controls were investigated using RNA sequencing. The expression levels of tRF-33-P4R8YP9LON4VDP in the plasma of gastric cancer patients, healthy controls and gastric cancer cell lines were first detected by quantitative reverse transcription-polymerase chain reaction. The effects of tRF-33-P4R8YP9LON4VDP overexpression or downregulation in gastric cancer cells on proliferation, migration, apoptosis, and cell cycle were analyzed using the Cell Counting Kit-8, scratch assay, Transwell assay, and flow cytometry, respectively. There were 21 upregulated and 46 downregulated tsRNAs found in plasma from gastric cancer patients. The significantly upregulated tsRNAs included tRF-18-S3M83004, tRF-31-PNR8YP9LON4VD, tRF-19-3L7L73JD, tRF-33-P4R8YP9LON4VDP, tRF-31-PER8YP9LON4VD, tRF-18-MBQ4NKDJ, and tRF-31-PIR8YP9LON4VD. The significantly downregulated tsRNAs included tRF-41-YDLBRY73W0K5KKOVD, tRF-18-07QSNHD2, tRF-28-86J8WPMN1E0J, tRF-29-86V8WPMN1EJ3, tRF-31-6978WPRLXN4VE, tRF-30-MIF91SS2P46I, tRF-26-MI7O3B1NR8E, tRF-30-RRJ89O9NF5W8, tRF-26-XIP2801MK8E, and tRF-35-V0J8O9YEKPRS93, In vitro studies showed that tRF-33-P4R8YP9LON4VDP inhibited proliferation of gastric cancer cells. In conclusion, tsRNAs such as tRF-33-P4R8YP9LON4VDP could serve as a novel diagnostic biomarker and target for gastric cancer therapeutics.

tRNA-derived fragments: Mechanisms underlying their regulation of gene expression and potential applications as therapeutic targets in cancers and virus infections.

tRNA-derived fragments (tRFs) are a new category of regulatory noncoding RNAs with distinct biological functions in cancers and stress-induced diseases. Herein, we first summarize the classification and biogenesis of tRFs. tRFs are produced from pre-tRNAs or mature tRNAs. Based on the incision loci, tRFs are classified into several types: tRF-1, tRF-2, tRF-3, tRF-5, and i-tRF. Some tRFs participate in posttranscriptional regulation through microRNA-like actions or by displacing RNA binding proteins and regulating protein translation by promoting ribosome biogenesis or interfering with translation initiation. Other tRFs prevent cell apoptosis by binding to cytochrome c or promoting virus replication. More importantly, the dysregulation of tRFs has important clinical implications. They are potential diagnostic and prognostic biomarkers of gastric cancer, liver cancer, breast cancer, prostate cancer, and chronic lymphocytic leukemia. tRFs may become new therapeutic targets for the treatment of diseases such as hepatocellular carcinoma and respiratory syncytial virus infection. Finally, we point out the existing problems and future research directions associated with tRFs. In conclusion, the current progress in the research of tRFs reveals that they have important clinical implications and may constitute novel molecular therapeutic targets for modulating pathological processes.

Downregulated Expression of linc-ROR in Gastric Cancer and Its Potential Diagnostic and Prognosis Value.

BACKGROUND: Gastric cancer (GC) is one of the global mortality diseases and has a poor prognosis due to the lack of ideal tumor biomarkers. Numerous studies have shown that long noncoding RNAs (lncRNAs) can affect the occurrence and development of cancer through a variety of signaling pathways. The abnormal expression and specificity of lncRNAs in tumors make them potential biomarkers of cancers. Nevertheless, the diagnostic roles of lncRNAs in GC have been poorly understood. So this study focuses on the clinical diagnostic value of lncRNAs in GC. MATERIALS AND METHODS: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to investigate the expression of the linc-ROR (long intergenic noncoding RNA, regulator of reprogramming) in 105 paired GC tissues and adjacent normal tissues. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were established to assess the diagnostic value of linc-ROR. The relationship between expression of linc-ROR and clinicopathological factors of patients with GC was further explored. Kaplan-Meier analysis was performed to evaluate the prognostic value of linc-ROR expression. RESULTS: The linc-ROR expression level was significantly decreased in GC tissues compared with its adjacent nontumor tissues (n = 105, P < 0.001). We also discovered that linc-ROR was evidently downregulated in 68.6% (72/105) of GC tissues. The AUC's value of linc-ROR was up to 0.6495, with sensitivity and specificity of 0.7524 and 0.5143, respectively. Intriguingly, the linc-ROR expression levels were obviously associated with tumor differentiation (P = 0.004). Notably, the overall survival rate of GC patients with high expression of linc-ROR was significantly higher than those with low expression. CONCLUSION: Our data revealed that linc-ROR has clinical potential as a biomarker for the diagnosis of GC and assessment of its prognosis.

Isolated metachronous splenic multiple metastases after colon cancer surgery: A case report and literature review.

BACKGROUND: Isolated splenic metastasis is a rare clinical entity. Multiple metastases in the spleen after radical colon resection in a patient who subsequently underwent a second local resection for isolated metachronous splenic metastasis are exceedingly rare. CASE SUMMARY: We report a colon cancer patient who underwent laparoscopic radical colon resection 14 mo previously, and subsequently underwent a second local resection due to local recurrence detected by elevated serum carcinoembryonic antigen (CEA) and positron emission tomography (PET). However, multiple metastases in the spleen were found 7 mo later by elevated serum CEA and PET-magnetic resonance imaging. Then the patient underwent total laparoscopic splenectomy. Local tumor recurrence and splenic metastasis from colorectal cancer (CRC) were found by postoperative pathology. Genetic analysis of these recurrent and metastatic tissues showed KRAS exon2, APC exon16 and TP53 exon6 missense mutations, but no mutations of NRAS, KRAF, EGFR, ERBB2, MET, MLH1, MSH2 and MSH6 were detected. Chemotherapy and target therapy were administered after multiple disciplinary team (MDT) consultation, and no tumor recurrence has been observed to date. We also reviewed the literature by conducting a search of the PubMed database using the following key words: CRC, splenic metastasis, isolated, and review. We identified 34 relevant papers, which included 28 cases of metachronous metastasis and 6 cases of simultaneous metastasis. CONCLUSION: Close monitoring of serum CEA levels is crucial for the detection of isolated splenic metastases after colon surgery. In terms of overall survival and progression-free survival, MDT plays an important role in the entire process of disease management.

Ailanthone: A novel potential drug for treating human cancer.

Cancer is the second leading cause of death after cardiovascular disease. In 2015, >8.7 million people died worldwide due to cancer, and by 2030 this figure is expected to increase to ~13.1 million. Tumor chemotherapy drugs have specific toxicity and side effects, and patients can also develop secondary drug resistance. To prevent and treat cancer, scientists have developed novel drugs with improved antitumor effects and decreased toxicity. Ailanthone (AIL) is a quassinoid extract from the traditional Chinese medicine plant Ailanthus altissima, which is known to have anti-inflammatory and antimalarial effects. An increasing number of studies have focused on AIL due to its antitumor activity. AIL can inhibit cell proliferation and induce apoptosis by up- or downregulating cancer-associated molecules, which ultimately leads to cancer cell death. Antitumor effects of AIL have been observed in melanoma, acute myeloid leukemia, bladder, lung, breast, gastric and prostate cancer and vestibular neurilemmoma. To the best of our knowledge, the present study is the first review to describe the antitumor mechanisms of AIL.

Action mechanisms and research methods of tRNA-derived small RNAs.

tRNA-derived small RNAs (tsRNAs), including tRNA-derived fragments (tRFs) and tRNA halves (tiRNAs), are small regulatory RNAs processed from mature tRNAs or precursor tRNAs. tRFs and tiRNAs play biological roles through a variety of mechanisms by interacting with proteins or mRNA, inhibiting translation, and regulating gene expression, the cell cycle, and chromatin and epigenetic modifications. The establishment and application of research technologies are important in understanding the biological roles of tRFs and tiRNAs. To study the molecular mechanisms of tRFs and tiRNAs, researchers have used a variety of bioinformatics and molecular biology methods, such as microarray analysis, real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR); Northern blotting; RNA sequencing (RNA-seq); cross-linking, ligation and sequencing of hybrids (CLASH); and photoactivatable-ribonucleoside-enhanced cross-linking and immunoprecipitation (PAR-CLIP). This paper summarizes the classification, action mechanisms, and roles of tRFs and tiRNAs in human diseases and the related signal transduction pathways, targeted therapies, databases, and research methods associated with them.

Clinical significance of the molecular heterogeneity of gastrointestinal stromal tumors and related research: A systematic review.

Gastrointestinal stromal tumors (GISTs) are the most commonly observed mesenchymal tumors of the digestive tract, and they originate from the interstitial cells of Cajal. GISTs can be divided into KIT/PDGFRA­mutant GISTs and wild­type GISTs based on the presence or absence of KIT/PDGFRA mutations. Wild­type GISTs can be divided into succinate dehydrogenase complex (SDH)­deficient GISTs and non­SDH­deficient GISTs. Downstream signaling pathways activated by these mutations serve a pivotal role in the development of GISTs and are associated with the biological behavior, including risk stratification, clinical prognosis and drug resistance. Accurate medical care requires accurate molecular diagnosis, which in turn prolongs the survival of patients with GISTs and makes GIST a chronic disease. At present, there is a lack of effective treatment for imatinib/sunitinib/regorafenib resistant patients and KIT/PDGFRA­WT GISTs, which is undoubtedly a major challenge for future research. The present review summarizes the molecular pathogenesis of GISTs and the progress of related research.

Reduced expression of circRNA hsa_circ_0067582 in human gastric cancer and its potential diagnostic values.

BACKGROUND: Gastric cancer (GC) is one of the global mortality diseases and has a poor prognosis due to the lack of ideal tumor biomarkers. Circular RNAs (circRNAs) are an abundant kind of endogenous RNAs that recently are found play a crucial role in the cancer occurrence and development. Nevertheless, little is known with regard to the diagnostic values of these circRNAs for GC. In this article of research, we investigated the role of hsa_circ_0067582 in clinical diagnosis of GC. MATERIALS AND METHODS: We used divergent primers, and the expression levels of hsa_circ_0067582 in 93 fresh GC tissues and paired adjacent normal tissues from surgical patients were detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Then, a receiver operating characteristic (ROC) curve was established to assess the diagnostic significance of hsa_circ_0067582. The relationship between expression of hsa_circ_0067582 and clinicopathological factors of patients was made further explored. RESULTS: Hsa_circ_0067582 levels were significantly decreased in GC tissues contrasted with adjacent normal tissues (n = 93, P < .001). After that, we discovered that it was evidently downregulated in 81.7% (76/93) GC tissues. The area under the ROC curve (AUC) of hsa_circ_0067582 was up to 0.6937, the sensitivity was 66.67%, and the specificity was 61.29%. Moreover, the hsa_circ_0067582 levels were obviously associated with tumor diameter (P = .002) and carbohydrate antigen 19-9 (CA19-9, P = .01). Meanwhile, after operation, low-level group of hsa_circ_0067582 of GC patients was associated with better prognosis. CONCLUSION: Our data imply that hsa_circ_000067582 may be a potential biomarker for GC diagnosis and prognosis evaluation.

Downregulated Expression of hsa_circ_0005556 in Gastric Cancer and Its Clinical Significance.

BACKGROUND: Gastric cancer (GC) has a poor prognosis due to the lack of ideal tumor markers. Circular RNAs (circRNAs) are a novel type of noncoding RNA related to the occurrence of GC. Among our research, we investigated the role of hsa_circ_0005556 in GC. MATERIALS AND METHODS: The expression of hsa_circ_0005556 of 100 paired GC tissues and adjacent normal tissues was detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). A receiver operating characteristic (ROC) curve was established to evaluate the diagnostic value of hsa_circ_0005556. The correlation between the expression of hsa_circ_0005556 and corresponding clinicopathological characteristic was explored. RESULTS: hsa_circ_0005556 was significantly downregulated in GC tissues contrasted with adjacent normal tissues (n = 100, p < 0.001). The areas under the ROC curve (AUC) of hsa_circ_0005556 were up to 0.773, while 64% sensitivity and 82% specificity, respectively. Moreover, its expression levels were significantly associated with differentiation (p = 0.001), TNM stage (p = 0.013), and lymphatic metastasis (p = 0.039). GC patients of high hsa_circ_0005556 levels had a longer overall survival (OS) than those of the low group (p = 0.047). CONCLUSION: hsa_circ_0005556 is a potential biomarker for GC, which may guide judgment of the indication of endoscopic treatment for early gastric cancer (EGC).

Using tRNA halves as novel biomarkers for the diagnosis of gastric cancer.

BACKGROUND: tRNA halves (tiRNAs) are produced from mature tRNAs. They have important roles both with in normal cells and cancer cells. However, the diagnostic value of tiRNAs in cancers have not yet been elucidated. OBJECTIVE: To explore the diagnostic value of tiRNA-5034-GluTTC-2 in gastric cancer. PATIENTS AND METHODS: Quantitative reverse transcription-polymerase chain reaction was used to detect the expression levels of tiRNA-5034-GluTTC-2 in paired gastric cancer tissues and adjacent normal tissues, plasmas from patients with gastric cancer and healthy people, and gastric cancer cell lines. Then, the relationship between its levels and clinicopathological factors of patients with gastric cancer was analyzed. A receiver operating characteristic (ROC) curve was established to predict the diagnostic value. RESULTS: tiRNA-5034-GluTTC-2 was first found to be down-regulated in gastric cancer tissues and plasmas. Its levels were significantly associated with tumor size. The area under the ROC curve (AUC) was 0.779 and 0.835 in tissue and plasma, respectively. The sensitivity, specificity and AUC were 84.7%, 92.8%, and 0.915 when tissues and plasmas were used in combination, respectively. The overall survival rate of patients with a lower expression of tiRNA-5034-GluTTC-2 was significantly lower than those with a higher expression. CONCLUSIONS: These results indicated that tiRNA-5034-GluTTC-2 may be a novel biomarker for the diagnosis of gastric cancer.

Transfer RNA-derived fragments and tRNA halves: biogenesis, biological functions and their roles in diseases.

The number of studies on non-coding RNAs has increased substantially in recent years owing to their importance in gene regulation. However, the biological functions of small RNAs from abundant species of housekeeping non-coding RNAs (rRNA, tRNA, etc.) remain a highly studied topic. tRNA-derived small RNAs (tsRNAs) refer to the specific cleavage of tRNAs by specific nucleases [e.g., Dicer and angiogenin (ANG)] in particular cells or tissues or under certain conditions such as stress and hypoxia. tsRNAs are a type of non-coding small RNA that are widely found in the prokaryotic and eukaryotic transcriptomes and are generated from mature tRNAs or precursor tRNAs at different sites. There are two main types of tsRNAs, tRNA-derived fragments (tRFs) and tRNA halves. tRFs are 14-30 nucleotides (nt) long and mainly consist of three subclasses: tRF-5, tRF-3, and tRF-1. tRNA halves, which are 31-40 nt long, are generated by specific cleavage in the anticodon loops of mature tRNAs. There are two types of tRNA halves, 5'-tRNA halves and 3'-tRNA halves. tsRNAs have multiple biological functions including acting as signaling molecules in stress responses and as regulators of gene expression. Additionally, they have been considered to be involved in RNA processing, cell proliferation, translation suppression, the modulation of DNA damage response, and neurodegeneration. More importantly, they are closely related to the occurrence of many human diseases such as tumors, infectious diseases, metabolic diseases, and neurological diseases. Moreover, tsRNAs have the potential to become new biomarkers for disease diagnosis. Continuous investigations will help us to understand their generation and regulatory mechanisms as well as the possible roles of tRFs and tRNA halves.