circVAPA-rich small extracellular vesicles derived from gastric cancer promote neural invasion by inhibiting SLIT2 expression in neuronal cells.

Gastric cancer (GC) is one of the most common cancer worldwide. Neural invasion (NI) is considered as the symbiotic interaction between nerves and cancers, which strongly affects the prognosis of GC patients. Small extracellular vesicles (sEVs) play a key role in intercellular communication. However, whether sEVs mediate GC-NI remains unexplored. In this study, sEVs release inhibitor reduces the NI potential of GC cells. Muscarinic receptor M3 on GC-derived sEVs regulates their absorption by neuronal cells. The enrichment of sEV-circVAPA in NI-positive patients' serum is validated by serum high throughput sEV-circRNA sequencing and clinical samples. sEV-circVAPA promotes GC-NI in vitro and in vivo. Mechanistically, sEV-circVAPA decreases SLIT2 transcription by miR-548p/TGIF2 and inhibits SLIT2 translation via binding to eIF4G1, thereby downregulates SLIT2 expression in neuronal cells and finally induces GC-NI. Together, this work identifies the preferential absorption mechanism of GC-derived sEVs by neuronal cells and demonstrates a previously undefined role of GC-derived sEV-circRNA in GC-NI, which provides new insight into sEV-circRNA based diagnostic and therapeutic strategies for NI-positive GC patients.

Associations of dietary factors with gastric cancer risk: insights from NHANES 2003-2016 and mendelian randomization analyses.

Background: Gastric cancer (GC) continues to be one of the leading causes of cancer-related deaths globally. Diet significantly influences the incidence and progression of GC. However, the relationship between dietary intake and GC is inconsistent. Methods: A study was conducted with adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2016 to investigate possible associations between 32 dietary factors and GC. To further detect potential causal relationships between these dietary factors and the risk of GC, a two-sample Mendelian randomization (MR) analysis was conducted. The primary method employed was the inverse variance weighted (IVW) analysis, and its results were further validated by four other methods. Results: Of the 35,098 participants surveyed, 20 had a history of GC. Based on the results of weighted logistic multivariate analysis, it was observed that there was a positive correlation between total fat intake [odds ratio (OR) = 1.09, 95% confidence interval (CI): (1.01-1.17), p = 0.03] and GC as well as negative association of dietary monounsaturated fatty acids (MUFAs) intake [OR = 0.83, 95% CI: (0.76-0.92), p < 0.001]. Further evaluations of the odds of GC across the quartiles of dietary MUFAs showed that the top quartile of total MUFA intake was associated with a lower likelihood of GC in three different models [model1: OR = 0.03, 95% CI: (0.00-0.25), p < 0.01; model2: OR = 0.04, 95% CI: (0.00-0.38), p = 0.01; model3: OR = 0.04, 95% CI: (0.00-0.40), p = 0.01]. For the MR analyses, genetic instruments were selected from the IEU Open GWAS project; IVW analysis showed that GC risk was not associated with MUFAs [OR = 0.82, 95% CI: (0.59-1.14), p = 0.23] or the ratio of MUFAs to total fatty acids [OR = 1.00, 95% CI: (0.75-1.35), p = 0.98]. Similar results were observed when using the other MR methods. Conclusion: The NHANES study revealed that consuming MUFAs was linked to a lower risk of GC, although the results of MR analyses do not provide evidence of a causal relationship. Additional research is therefore necessary to clarify these findings.

Evaluation of mandibular motion in adolescents with skeletal class II division 1 malocclusion during mandibular advancement using clear functional aligners: a prospective study.

BACKGROUND: This study aimed to evaluate the characteristics of mandibular protrusive condylar trajectory in adolescents with skeletal Class II Division 1 malocclusion and the changes of condylar trajectory during mandibular advancement (MA) treatment using clear functional aligners. METHODS: This prospective study consisted of a cross-sectional study and a longitudinal study. In cross-sectional study, sixty-one adolescents were divided into two groups: Class I (n = 30) and Class II Division 1 (n = 31). The condylar trajectory was measured and compared using the Mann-Whitney U test. The longitudinal study was the MA treatment group using clear functional aligner and consisted of 16 participants from Class II Division 1group. The condylar trajectory was collected at three-time points: pre-treatment (T1), during MA treatment at approximately 3 months (T2, 105.6 days average), and at the end of MA treatment (T3, 237.6 days average). The changes at T1, T2, and T3, as well as the symmetry between the left and right condyles across all groups, were examined using the Wilcoxon paired test. RESULTS: A greater increase in the anteroposterior displacement and space displacement during protrusive movements was observed in the Class II Division 1 group compared with that in the Class I group, with a large difference being observed in the left and right condylar movements. The condylar anteroposterior displacement and space displacement decreased significantly at T2 and increased significantly at T3; however, no significant difference was observed between T1 and T3. A significant difference was observed between the condylar movement on the left and right sides at T1; however, no significant difference was observed at T2 and T3. CONCLUSIONS: Adolescents with Class II Division 1 malocclusion had higher protrusive capacity than those with Class I. Moreover, their left and right condylar motion was more asymmetric. The range of condyle motion decreased first and then increased during MA therapy, and the left and right condyle movement became more symmetrical, which may be the adaptive response of neuromuscular function to the changes in jaw position.

Three-dimensional spatial analysis of temporomandibular joint in adolescent Class II division 1 malocclusion patients: comparison of Twin-Block and clear functional aligner.

BACKGROUND: Our study aimed to use three-dimensional (3D) spatial morphological measurement methods to compare the influence of Twin-Block and clear functional aligners on the temporomandibular joint (TMJ) of adolescent Class II division 1 malocclusion mandibular retraction patients. We also aimed to explore the similarities and differences in the effects on the TMJ upon using Twin-Block and clear functional aligner. METHODS: Cone-beam computed tomography (CBCT) data of 49 patients with Class II division 1 malocclusion (Twin-Block group: 24; clear functional aligner group: 25) were collected before and after functional orthodontic treatment, and a 3D model of the TMJ was reconstructed using MIMICS 21.0 software. Eighteen measurement parameters, including the anterior, superior, and posterior joint spaces, were measured and compared using the 3D model. RESULTS: After the two groups underwent functional appliance treatment, the height, volume, and surface area of the condyle, length of the mandibular ramus and mandibular length increased; The retro-displaced condyle moved to the middle position of the articular fossa, while the rest of the condylar position did not change significantly. Remodeling of the articular fossa after treatment was not evident. The superior joint space of the clear functional aligner group increased, but there was no significant change after Twin-Block appliances treatment. CONCLUSIONS: Both appliances promote condylar growth and sagittal and vertical development of the mandible in adolescent Class II division 1 malocclusion mandibular retraction patients. The length of the mandibular ramus showed a more significant increase following treatment with the Twin-Block appliances than with clear function aligners.

Small Extracellular Vesicles Derived from Helicobacter Pylori-Infected Gastric Cancer Cells Induce Lymphangiogenesis and Lymphatic Remodeling via Transfer of miR-1246.

Lymph node metastasis (LNM) is a significant barrier to the prognosis of patients with gastric cancer (GC). Helicobacter pylori (H. pylori)-positive GC patients experience a higher rate of LNM than H. pylori-negative GC patients. However, the underlying mechanism remains unclear. Based on the findings of this study, H. pylori-positive GC patients have greater lymphangiogenesis and lymph node immunosuppression than H. pylori-negative GC patients. In addition, miR-1246 is overexpressed in the plasma small extracellular vesicles (sEVs) of H. pylori-positive GC patients, indicating a poor prognosis. Functionally, sEVs derived from GC cells infected with H. pylori deliver miR-1246 to lymphatic endothelial cells (LECs) and promote lymphangiogenesis and lymphatic remodeling. Mechanistically, miR-1246 suppresses GSK3ß expression and promotes ß-Catenin and downstream MMP7 expression in LECs. miR-1246 also stabilizes programmed death ligand-1 (PD-L1) by suppressing GSK3ß and induces the apoptosis of CD8+ T cells. Overall, miR-1246 in plasma sEVs may be a novel biomarker and therapeutic target in GC-LNM.

TRIM29 promotes antitumor immunity through enhancing IGF2BP1 ubiquitination and subsequent PD-L1 downregulation in gastric cancer.

Tripartite motif-containing protein 29 (TRIM29) is a member of TRIM family protein which has been reported to play a role in the progress of inflammatory and cancer diseases. However, its specific role in gastric cancer (GC) has yet to be fully understood. Here, we investigated the expression of TRIM29 in gastric cancer and its functions in the antitumor immunity. TRIM29 expression was lower in tumor tissues than that in paired normal tissues. Lower expression of TRIM29 was related to aberrant hypermethylation of CpG islands in TRIM29 gene. Comprehensive proteomics and immunoprecipitation analyses identified IGF2BP1 as TRIM29 interactors. TRIM29 interacted with IGF2BP1 and induced its ubiquitination at Lys440 and Lys450 site by K48-mediated linkage for protein degradation. IGF2BP1 promoted PD-L1 mRNA stability and expression in a 3'UTR and m6A-dependent manner. Functionally, TRIM29 enhanced antitumor T-cell immunity in gastric cancer dependent on the IGF2BP1/PD-L1 axis in vivo and in vitro. Clinical correlation analysis revealed that TRIM29 expression in patient samples was associated with CD8+ immune cell infiltration in the GC microenvironment and the overall survival rates of GC patients. Our findings revealed a crucial role of TRIM29 in regulating the antitumor T-cell immunity in GC. We also suggested that the TRIM29/IGF2BP1/PD-L1 axis could be used as a diagnostic and prognostic marker of gastric cancer and a promising target for GC immunotherapy.

Gastric cancer-derived LBP promotes liver metastasis by driving intrahepatic fibrotic pre-metastatic niche formation.

BACKGROUND: Liver metastasis (LM) is one of the most common distant metastases of gastric cancer (GC). However, the mechanisms underlying the LM of GC (GC-LM) remain poorly understood. This study aimed to identify the tumour-secreted protein associated with GC-LM and to investigate the mechanisms by which this secreted protein remodels the liver microenvironment to promote GC-LM. METHODS: Data-independent acquisition mass spectrometry (DIA-MS), mRNA expression microarray, quantitative real-time PCR, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) were performed to identify and validate the GC-secreted proteins associated with GC-LM. A modified intrasplenic injection mouse model of LM was used to evaluate the progression and tumour burden of LM in vivo. Flow cytometry, immunofluorescence (IF), western blots (WB) and IHC were performed to validate the pre-metastatic niche (PMN) formation in the pre-modelling mouse models. mRNA sequencing of PMA-treated THP-1 cells with or without lipopolysaccharide binding protein (LBP) treatment was used to identify the functional target genes of LBP in macrophages. Co-immunoprecipitation (Co-IP), WB, ELISA, IF and Transwell assays were performed to explore the underlying mechanism of LBP in inducing intrahepatic PMN formation. RESULTS: LBP was identified as a critical secreted protein associated with GC-LM and correlated with a worse prognosis in patients with GC. LBP activated the TLR4/NF-κB pathway to promote TGF-ß1 secretion in intrahepatic macrophages, which, in turn, activated hepatic satellite cells (HSCs) to direct intrahepatic fibrotic PMN formation. Additionally, TGF-ß1 enhanced the migration and invasion of incoming metastatic GC cells in the liver. Consequently, selective targeting of the TGF-ß/Smad signaling pathway with galunisertib demonstrated its efficacy in effectively preventing GC-LM in vivo. CONCLUSIONS: The results of this study provide compelling evidence that serological LBP can serve as a valuable diagnostic biomarker for the early detection of GC-LM. Mechanistically, GC-derived LBP mediates the crosstalk between primary GC cells and the intrahepatic microenvironment by promoting TGF-ß1 secretion in intrahepatic macrophages, which induces intrahepatic fibrotic PMN formation to promote GC-LM. Importantly, selectively targeting the TGF-ß/Smad signaling pathway with galunisertib represents a promising preventive and therapeutic strategy for GC-LM.

Neural Invasion is an Independent Prognostic Factor in Young and Lymph Node Negative Gastric Cancer Patients Underwent Curative Gastrectomy.

BACKGROUND: The prognostic significance of neural invasion (NI) in gastric cancer (GC) has not been established. This study is to investigate the characteristic and prognostic value of NI in GC. METHODS: 592 patients who had undergone gastrectomy for GC were retrospectively analyzed. NI was defined when cancer cells infiltrated into the perineurium or neural fascicles by hematoxylin and eosin staining of surgical specimens. NI and the other clinical factors were analyzed. RESULTS: NI was detected in 270 of the 592 patients. NI was associated with tumor size, site, depth of invasion, lymph node metastasis, TNM stage, D dissection, tumor differentiation, Lauren classification, and blood vessel invasion. NI was associated with the overall survival. Multivariate analysis indicated that NI was not an independent prognostic factor for total patients, while NI independently predicted prognosis for age < 60 and lymph node metastasis negative patients by subgroup analysis. Concomitant existence of NI with tumor size ≥3cm, TNM stage III, or diffused Lauren classification independently predicted prognosis. CONCLUSIONS: The frequency of NI is high in GC patients and increases with disease progression. NI is related to poor survival in GC patients who underwent curative gastrectomy and provides independent prognostic value for young and lymph node metastasis negative patients.

m5C-methylated lncRNA NR_033928 promotes gastric cancer proliferation by stabilizing GLS mRNA to promote glutamine metabolism reprogramming.

Abnormal 5-methylcytosine (m5C) methylation has been proved to be closely related to gastric carcinogenesis, progression, and prognosis. Dysregulated long noncoding RNAs (lncRNAs) participate in a variety of biological processes in cancer. However, to date, m5C-methylated lncRNAs are rarely researched in gastric cancer (GC). Here, we found that RNA cytosine-C(5)-methyltransferase (NSUN2) was upregulated in GC and high NSUN2 expression was associated with poor prognosis. NR_033928 was identified as an NSUN2-methylated and upregulated lncRNA in GC. Functionally, NR_033928 upregulated the expression of glutaminase (GLS) by interacting with IGF2BP3/HUR complex to promote GLS mRNA stability. Increased glutamine metabolite, α-KG, upregulated NR_033928 expression by enhancing its promoter 5-hydroxymethylcytosine (hm5C) demethylation. In conclusion, our results revealed that NSUN2-methylated NR_033928 promoted GC progression and might be a potential prognostic and therapeutic target for GC.

Long noncoding RNA DIAPH2-AS1 promotes neural invasion of gastric cancer via stabilizing NSUN2 to enhance the m5C modification of NTN1.

Neural invasion (NI) is a vital pathological characteristic of gastric cancer (GC), which correlates with tumor recurrence and a worse prognosis. Long noncoding RNAs (lncRNAs) play critical roles in various biological processes. However, the involvement of lncRNAs in NI of GC (GC-NI) remains unclear. DIAPH2-AS1 was upregulated in NI-positive GC tissues, which was confirmed by qRT-PCR. The higher expression of DIAPH2-AS1 predicted NI and worse survival for GC patients. Both in vitro and in vivo experiments, including wound-healing assay, Transwell assay, DRG-GC cells co-culture model, the mouse sciatic nerve model, and the lung metastasis model, indicated that DIAPH2-AS1 promoted the migration, invasion, and NI potential of GC cells. Mechanistically, pulldown assay and RNA immunoprecipitation assay revealed that DIAPH2-AS1 interacted with NSUN2. Subsequent experiments indicated that DIAPH2-AS1 stabilized NSUN2 from ubiquitin-proteasomal degradation via masking the K577 and K579 of NSUN2. The protection of DIAPH2-AS1 on NSUN2 improved the stability of NTN1 mRNA via m5C modification, which finally induced GC-NI. Our work uncovered DIAPH2-AS1 as a novel oncogenic lncRNA in GC-NI and validated the DIAPH2-AS1-NSUN2-NTN1 axis as a potential therapeutic target for NI-positive GC.

CircTHBS1 drives gastric cancer progression by increasing INHBA mRNA expression and stability in a ceRNA- and RBP-dependent manner.

Circular RNAs (circRNAs) play vital regulatory roles in the progression of multiple cancers. In our study, transcriptome analysis and self-organizing maps (SOM) were applied to screen backbone circRNAs in gastric cancer (GC). Upon validation of the expression patterns of screened circRNAs, gain- and loss-of-function assays were performed in vitro and in vivo. Underlying mechanisms were investigated using RNA pull-down, luciferase reporter assay and RNA immunoprecipitation. The expression of circTHBS1 was significantly increased in GC and associated with poor prognosis. CircTHBS1 facilitated the malignant behavior and epithelial-to-mesenchymal transition of GC cells. Mechanistically, circTHBS1 sponged miR-204-5p to promote the expression of Inhibin Subunit Beta A (INHBA). Moreover, circTHBS1 could enhance the HuR-mediated mRNA stability of INHBA, which subsequently activated the TGF-ß pathway. Our research identified circTHBS1 as an oncogenic circRNA that enhances GC malignancy by elevating INHBA expression, providing new insight and a feasible target for the diagnosis and treatment of GC.

Circular CPM promotes chemoresistance of gastric cancer via activating PRKAA2-mediated autophagy.

BACKGROUND: Chemotherapy can significantly improve the disease-free survival and overall survival of patients with advanced gastric cancer (GC). 5-fluorouracil (5-FU) is frequently applied in the clinic, acting as a first-line chemotherapy drug of advanced GC, which could be used alone or combining platinum drugs. However, its efficacy is significantly attenuated by chemoresistance, which is associated with patients' poor survival. Recently, there is evidence suggesting that dysregulation of autophagy may contribute to drug resistance in cancer, and circular RNAs (circRNAs) also take part in chemoresistance. However, whether circRNAs participate in 5-FU chemoresistance through autophagy remains largely unknown. METHODS: RNA sequencing technologies and bioinformatics analysis were performed in GC. Sanger sequencing, Actinomycin D assay and RNase R assay confirmed the circular structure of circular CPM (circCPM). Various cell line models and animal models were used to explore related functions in vitro and in vivo. Quantitative Real-time PCR (qRT-PCR), fluorescence in situ hybridization, ribonucleic acid; (RNA) pulldown assays, RNA binding protein immunoprecipitation assays and Luciferase reporter assays were applied to explore involved pathways. RESULTS: circCPM was up-regulated in 5-FU resistant GC cell lines and tissue. Moreover, high circCPM expression is positively associated with poor survival. Silencing circCPM greatly improved chemosensitivity in vitro and in vivo. Mechanistically, it directly binds to miR-21-3p in the cytoplasm and therefore increases the expression of PRKAA2, contributing to the activation of autophagy and chemoresistance. CONCLUSION: Our results reveal that circCPM has a crucial role in regulating GC autophagy and 5-FU resistance by targeting PRKAA2. It may function as a new theory basis for assessing the curative effect of GC and reversing 5-FU chemoresistance.

miR-151a-3p-rich small extracellular vesicles derived from gastric cancer accelerate liver metastasis via initiating a hepatic stemness-enhancing niche.

Liver metastasis (LM) severely affects gastric cancer (GC) patients' prognosis. Small extracellular vesicles (sEVs) play key roles in intercellular communication. Specific sEV-miRNAs from several types of cancer were found to induce a premetastatic niche in target organs before tumor cell arrive. However, whether the primary GC affects hepatic microenvironment or the role of sEV-miRNAs in GC-LM is yet unclear. We report that GC-derived sEVs are primarily absorbed by Kupffer cells (KCs). sEV-miR-151a-3p is highly expressed in GC-LM patients' plasma and presents poor prognosis. Treating mice with sEVs-enriched in miR-151a-3p promotes GC-LM, whereas has no influence on the proliferation of GC cells in situ. Mechanistically, sEV-miR-151a-3p inhibits SP3 in KCs. Simultaneously, sEV-miR-151a-3p targets YTHDF3 to decrease the transcriptional inhibitory activity of SP3 by reducing SUMO1 translation in a N6-methyladenosine-dependent manner. These factors contribute to TGF-ß1 transactivation in KCs, subsequently activating the SMAD2/3 pathway and enhancing the stem cell-like properties of incoming GC cells. Furthermore, sEV-miR-151a-3p induces miR-151a-3p transcription in KCs to form a positive feedback loop. In summary, our results reveal a previously unidentified regulatory axis initiated by sEV-miR-151a-3p that establishes a hepatic stemness-permissive niche to support GC-LM. sEV-miR-151a-3p could be a promising diagnostic biomarker and preventive treatment candidate for GC-LM.

A novel protein encoded by circMAPK1 inhibits progression of gastric cancer by suppressing activation of MAPK signaling.

BACKGROUND: A novel type of noncoding RNA, circRNA has been reported to participate in the occurrence and development of diseases through many mechanisms. The MAPK pathway is a common signal transduction pathway involved in cell proliferation, inflammation and apoptosis and plays a particularly important role in cancers. However, the role of circRNAs related to the MAPK pathway in gastric cancer has not been explored. METHODS: A bioinformatics analysis was performed to profile and identify the circRNAs involved in the MAPK pathway in gastric cancer. The tumor-suppressive role of circMAPK1 was confirmed both in vitro and in vivo. Mass spectrometry, Western blot and immunofluorescence staining assays were used to validate the existence and expression of MAPK1-109aa. The molecular mechanism of circMAPK1 was investigated by mass spectrometry and immunoprecipitation analyses. RESULTS: In this study, we identified that circMAPK1 (hsa_circ_0004872) was downregulated in gastric cancer tissues compared with adjacent normal tissues. Importantly, lower circMAPK1 expression predicted poor survival in GC patients. CircMAPK1 inhibited the proliferation and invasion of gastric cancer cells in vitro and in vivo. Next, we found that circMAPK1 encoded a novel protein with 109 amino acids in length. Through a series of functional experiments, we confirmed that circMAPK1 exerted a tumor-suppressing effect via the encoded protein MAPK1-109aa. Mechanistically, the tumor suppressor MAPK1-109aa inhibited the phosphorylation of MAPK1 by competitively binding to MEK1, thereby suppressing the activation of MAPK1 and its downstream factors in MAPK pathway. CONCLUSIONS: Our study revealed that circMAPK1 inhibits the malignant biological behavior of gastric cancer cells through its encoded protein MAPK1-109aa. More importantly, circMAPK1 is a favorable predictor for gastric cancer patients and may provide a new therapeutic target in the treatment of gastric cancer.

CircFAM73A promotes the cancer stem cell-like properties of gastric cancer through the miR-490-3p/HMGA2 positive feedback loop and HNRNPK-mediated ß-catenin stabilization.

BACKGROUND: Circular RNAs (circRNAs) have emerged as a new subclass of regulatory RNAs that play critical roles in various cancers. Cancer stem cells (CSCs), a small subset of cancer cells, are believed to possess the capacities to initiate tumorigenesis and promote progression. Although accumulating evidence has suggested that cells with CSC-like properties are crucial for the malignancy of gastric cancer (GC), it remains unclear whether circRNAs are related to the acquisition of CSC-like properties in GC. METHODS: CircFAM73A expression was analyzed by GEO datasets and verified in GC samples. The roles of circFAM73A in GC cell proliferation, migration, cisplatin resistance, and CSC-like properties were determined by a series of functional experiments both in vitro and in vivo. RNA pulldown was used to explore the miRNAs and proteins binding to circFAM73A. Bioinformatic analysis and experimental verification confirmed the downstream targets of circFAM73A. The regulation of circFAM73A by HMGA2 was verified by ChIP and RIP assays. RESULTS: Elevated circFAM73A expression was confirmed in GC tissues, and higher circFAM73A predicted poor prognosis in GC patients. The upregulation of circFAM73A enhanced CSC-like properties in GC, thus facilitating cell proliferation, migration, and cisplatin resistance. Mechanistically, circFAM73A promoted GC malignancy by regulating miR-490-3p/HMGA2 in a positive feedback loop and recruiting HNRNPK to facilitate ß-catenin stabilization. Moreover, HMGA2 further enhanced E2F1 and HNRNPL activity, which in turn promoted circFAM73A expression. CONCLUSIONS: Our work demonstrates the crucial role of circFAM73A in the CSC-like properties of GC and uncovers a positive feedback loop in circFAM73A regulation that leads to the progression of gastric cancer, which may provide new insights into circRNA-based diagnostic and therapeutic strategies.

Circular RNA TMEM87A promotes cell proliferation and metastasis of gastric cancer by elevating ULK1 via sponging miR-142-5p.

BACKGROUND: Circular RNAs (circRNAs) act as vital regulators of gene expression in a variety of cancers. However, the role of circRNAs in gastric cancer (GC) remains largely unexplored. Herein, we identified that circTMEM87A sponges miR-142-5p to promote GC progression through up-regulating ULK1 expression. METHODS: The expression of circTMEM87A in GC was determined by RNA sequencing and quantitative real-time PCR (qRT-PCR). The effects of knockdown or exogenous expression of circTMEM87A on GC cell phenotypes were evaluated both in vitro and in vivo. The interacting miRNA of circTMEM87A was predicted by bioinformatics and confirmed by RNA pull-down, dual-luciferase reporter assay and fluorescence in situ hybridization (FISH). The mechanism by which circTMEM87A/miR-142-5p/ULK1 axis promotes GC was determined by western blot, GFP/mRFP-LC3 puncta analysis, transmission electron microscope (TEM). RESULTS: CircTMEM87A was dramatically elevated in GC tissues and cell lines, and high circTMEM87A expression was closely correlated with poor prognosis of GC patients. Knockdown of circTMEM87A suppressed cell growth, migration, invasion and induced apoptosis in vitro, as well as inhibited GC tumorigenicity and lung metastasis potential in vivo. Meanwhile, circTMEM87A overexpression had the opposite effects. Furthermore, we demonstrated that circTMEM87A could act as a sponge of miR-142-5p to regulate ULK1 expression and GC progression. CONCLUSIONS: Our findings suggest that circTMEM87A functions as an oncogene through the miR-142-5p/ULK1 axis in GC. CircTMEM87A might be a prognostic biomarker as well as a promising therapeutic target for GC.

Circular RNA MCTP2 inhibits cisplatin resistance in gastric cancer by miR-99a-5p-mediated induction of MTMR3 expression.

BACKGROUND: Cisplatin (CDDP) is the first-line chemotherapy for gastric cancer (GC). The poor prognosis of GC patients is partially due to the development of CDDP resistance. Circular RNAs (circRNAs) are a subclass of noncoding RNAs that function as microRNA (miRNA) sponges. The role of circRNAs in CDDP resistance in GC has not been evaluated. METHODS: RNA sequencing was used to identify the differentially expressed circRNAs between CDDP-resistant and CDDP-sensitive GC cells. qRT-PCR was used to detect the expression of circMCTP2 in GC tissues. The effects of circMCTP2 on CDDP resistance were investigated in vitro and in vivo. Pull-down assays and luciferase reporter assays were performed to confirm the interactions among circMCTP2, miR-99a-5p, and myotubularin-related protein 3 (MTMR3). The protein expression levels of MTMR3 were detected by western blotting. Autophagy was evaluated by confocal microscopy and transmission electron microscopy (TEM). RESULTS: CircMCTP2 was downregulated in CDDP-resistant GC cells and tissues compared to CDDP-sensitive GC cells and tissues. A high level of circMCTP2 was found to be a favorable factor for the prognosis of patients with GC. CircMCTP2 inhibited proliferation while promoting apoptosis of CDDP-resistant GC cells in response to CDDP treatment. CircMCTP2 was also found to reduce autophagy in CDDP-resistant GC cells. MiR-99a-5p was verified to be sponged by circMCTP2. Inhibition of miR-99a-5p could sensitize GC cells to CDDP. MTMR3 was confirmed to be a direct target of miR-99a-5p. Knockdown of MTMR3 reversed the effects of circMCTP2 on the proliferation, apoptosis and autophagy of CDDP-resistant GC cells. CircMCTP2 was also confirmed to inhibit CDDP resistance in vivo in a nude mouse xenograft model. CONCLUSIONS: CircMCTP2 sensitizes GC to CDDP through the upregulation of MTMR3 by sponging miR-99a-5p. Overexpression of CircMCTP2 could be a new therapeutic strategy for counteracting CDDP resistance in GC.

Short-Term Surgical Outcomes of Laparoscopic Proximal Gastrectomy With Double-Tract Reconstruction Versus Laparoscopic Total Gastrectomy for Adenocarcinoma of Esophagogastric Junction: A Matched-Cohort Study.

BACKGROUND: Laparoscopic proximal gastrectomy (LPG) with double-tract reconstruction (DTR) is performed as a function-preserving surgery for patients with adenocarcinoma of esophagogastric junction. However, whether LPG with DTR has postoperative advantages over laparoscopic total gastrectomy (LTG) is debatable. To evaluate benefits of LPG with DTR, we compared short-term surgical outcomes between LPG with DTR and LTG for adenocarcinoma of esophagogastric junction (AEG). METHODS: Twelve patients who underwent LPG with DTR for AEG between February 2016 and August 2017 were included. Twenty-four patients who underwent LTG in the same period were matched to LPG with DTR cases for demographics, comorbidities, tumor characteristics, and tumor node metastasis stage. Short-term surgical outcomes were compared between the two groups. RESULTS: Demographics of the LPG with DTR group and LTG group were comparable. The number of harvested lymph nodes in the LPG with DTR group was less than that in the LTG group, and the amount of estimated blood loss, the operative time, the days of gas-passing, start of diet, postoperative hospital stay were not significantly different between the groups. Furthermore, the postoperative reflux symptom in the LPG with DTR group was not significantly different with that in the LTG group. However, the increasing percentages of the serum albumin, total protein, and hemoglobin levels in the LPG with DTR group were significantly higher than those in the LTG group. CONCLUSIONS: This study reveals that LPG with DTR may be a valuable procedure for the treatment of AEG because it has the advantages over LTG in terms of postoperative serum albumin, total protein, and hemoglobin.