Circular RNA circPGD contributes to gastric cancer progression via the sponging miR-16-5p/ABL2 axis and encodes a novel PGD-219aa protein

Coding circular RNA in human cancer

circular RNA (circRNA) is a covalently closed single-stranded RNA that lacks 5' and 3' ends and has long been considered a noncoding RNA. With the development of high-throughput sequencing and bioinformatics technology, the understanding of circRNA has become increasingly advanced. Recent studies have shown that some cytoplasmic circRNAs can be effectively translated into detectable proteins, further indicating the importance of circRNA in cellular pathology and physiological functions. Internal ribosome entry site (IRES) and N6-methyladenosine (m6A) mediated cap-independent translation initiation are considered potential mechanisms of circRNA translation. Multiple circRNAs have been shown to play crucial roles in human cancer. This paper provides an overview of the nature and functions of circRNA and describes the possible mechanisms underlying the initiation of circRNA translation. We summarized the emerging functions of circRNA-encoded proteins in human cancer. Finally, we discuss the therapeutic potential of circRNAs and the challenges of research in this field. This review on circRNA translation will reveal a hidden human proteome and enhance our understanding of the importance of circRNAs in human malignant tumors.

CircFLNA facilitates gastric cancer cell proliferation and glycolysis via regulating SOX5 by sponging miR-1200

BACKGROUND AND STUDY AIMS

Circular RNAs (circRNAs) are important regulators for gastric cancer (GC) progression. Our study aims to investigate the role and mechanism of circFLNA in GC progression.

PATIENTS AND METHODS

The levels of circFLNA, microRNA (miR)-1200 and SRY-box transcription factor 5 (SOX5) were examined using qRT-PCR. Flow cytometry, cell counting kit 8 assay and EdU assay were performed to measure cell proliferation and apoptosis. Cell glycolysis ability was assessed by examining glucose uptake and lactate produce. RNA interaction was determined using RNA pull-down assay and dual-luciferase reporter assay. Mice xenograft models were constructed to evaluate the regulation of circFLNA knockdown on GC tumor growth.

RESULTS

CircFLNA was upregulated in GC tissues. Functional experiments showed that circFLNA knockdown suppressed GC cell proliferation, inhibited glycolysis, and promoted apoptosis in vitro, as well as reduced GC tumor growth in vivo. CircFLNA sponged miR-1200, and miR-1200 targeted SOX5. MiR-1200 mimic reversed the promotion effect of circFLNA overexpression on GC cell growth and glycolysis, and SOX5 upregulation also abolished the inhibiting effect of miR-1200 mimic on GC cell growth and glycolysis.

CONCLUSION

Our data suggest that circFLNA might exert oncogenic role in GC development, which promoted GC proliferation and glycolysis through regulating miR-1200/SOX5 axis.

The microprotein HDSP promotes gastric cancer progression through activating the MECOM-SPINK1-EGFR signaling axis

The presence of noncanonical open reading frames within lncRNAs (long non-coding RNAs) suggests their potential for translation, yielding various functional peptides or proteins. However, the existence and specific roles of these products in gastric cancer remain largely unclear. Here we identify the HOXA10-HOXA9-derived small protein (HDSP) in gastric cancer through comprehensive analysis and experimental validation, including mass spectrometry and western blotting. HDSP exhibits high expression and oncogenic roles in gastric cancer. Mechanistically, HDSP blocks TRIM25-mediated ubiquitination and degradation by interacting with MECOM, leading to MECOM accumulation and enhanced SPINK1 transcription-a gene promoting cancer via the EGFR signaling pathway. Furthermore, MECOM fosters HOXA10-HOXA9 transcription, establishing a feedback loop activating SPINK1-EGFR signaling. HDSP knockdown inhibits tumor growth in a PDX (patient-derived xenograft) model, and infusion of an artificially synthesized HDSP peptide as a neoantigen enhances immune cell-mediated anti-tumor efficacy against gastric cancer in vitro and in vivo. These findings propose HDSP as a potential therapeutic target or neoantigen candidate for gastric cancer treatment.

High expression of ABL2 promotes gastric cancer cells migration, invasion and proliferation via the TGF-β and YAP signaling pathways

Background: The Abelson-Related Gene (ABL2) is expressed in various malignancies. However, its role in gastric cancer (GC) regarding tumor proliferation, metastasis, and invasion remains unclear. Methods: ABL2 expression in clinical specimens was assessed using quantitative real-time fluorescence PCR (qRT-PCR). Western blotting and immunofluorescence assay determined protein levels. Additionally, Transwell migration and invasion, cell counting kit-8 (CCK-8) and colony-formation assays analyzed the effect of ABL2 on GC cells. Protein levels related to GC cells were assessed through Western blotting. The effects of si-ABL2 combined with GA-017 that activated YAP on cell migration, invasion and proliferation were investigated. Results: ABL2 expression was upregulated in human GC tissues compared to paracancer tissues, and it was positively related to tumor node metastasis classification (TNM) stage. Furthermore, high ABL2 levels promoted the proliferation, metastasis, and invasion capacity in GC cells. Elevated ABL2 expression enhanced the expression of MMP2, MMP9, and PCNA while decreasing TIMP1 and TIMP2 expression. It also increased the p-SMAD2/3 expression and YAP expression, decreased the expression of p-YAP in GC cells. Furthermore, GA-017 increased ABL2 expression in MGC-803 cells and counteracted the effects of si-ABL2 on cell migration, invasion and proliferation. Conclusion: These findings indicated that heightened ABL2 expression could activate TGF-β/SMAD2/3 and YAP signaling pathway, promoting epithelial mesenchymal transformation (EMT), and enhancing multiplication, metastasis, and invasion in GC cells.

Communication molecules (ncRNAs) mediate tumor-associated macrophage polarization and tumor progression

Non-coding RNAs play important roles in tumor cells and macrophages and participate in their communication as messengers. Non-coding RNAs have an impact in tumor cell proliferation, migration, and apoptosis, and they also regulate the differentiation and regulation of immune cells. In macrophages, they stimulate the polarization of macrophages into M1 or M2 by regulating proteins related to signaling pathways; in tumor cells, non-coding RNAs can enter macrophages through exosomes and affect the latter polarization. The polarization of macrophages further regulates the biological functions of cancer cells. The direction of macrophage polarization determines tumor progression, angiogenesis and drug resistance. This often creates a feedback loop. Non-coding RNAs act as bridges between tumor cells and macrophages to regulate the balance of the tumor microenvironment. We reviewed the signaling pathways related to macrophage polarization and the regulatory mechanisms of non-coding RNA in tumor-associated macrophages M1 and M2, and discussed the potential applications and prospects of exosome engineering.

Helicobacter pylori upregulates circPGD and promotes development of gastric cancer

PURPOSE

Helicobacter pylori (H. pylori) has unique biochemical traits and pathogenic mechanisms, which make it a substantial cause of gastrointestinal cancers. Circular RNAs (circRNAs) have concurrently been identified as an important participating factor in the pathophysiology of several different cancers. However, the underlying processes and putative interactions between H. pylori and circRNAs have received very little attention. To address this issue, we explored the interaction between H. pylori and circRNAs to investigate how they might jointly contribute to the occurrence and development of gastric cancer.

METHODS

Changes in circPGD expression in H. pylori were detected using qRT-PCR. Cell proliferation and migration changes were assayed by colony formation, the CCK-8 assay and the transwell assay. Apoptosis was measured by flow cytometry. Western blot was conducted to detect changes in cell migration, apoptosis, proliferation and inflammation-associated proteins. QRT-PCR was used to measure changes in circPGD and inflammation-associated factors.

RESULTS

We found that H. pylori induced increased circPGD expression in infected human cells and facilitated gastric cancer progression in three ways by promoting cell proliferation and migration, enhancing the inflammatory response, and inhibiting apoptosis.

CONCLUSIONS

CircPGD appears to play a role in H. pylori-related gastric cancer and may thus be a viable, novel target for therapeutic intervention.

CircRNA_15430 reduced by Helicobacter pylori infection and suppressed gastric cancer progression via miR-382-5p/ZCCHC14 axis

BACKGROUND

Helicobacter pylori (H.pylori, HP) is one of the main causes of gastric cancer (GC). CircRNAs have been reported to play a crucial role in developing many types of cancer. However, the role of circRNAs in the development and progression of HP infected-GC has not been studied.

METHODS

The location of circRNA_15430 in GC cells were detected by nuclear and cytoplasmic RNA fractionation and RNA fluorescence in situ hybridization analysis (FISH) assays, and circRNA_15430, miR-382-5p and ZCCHC14 expression in GC cell lines and tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The function of circRNA_15430 in GC cells were examined by using colony formation, cell counting kit-8 (CCK-8) and Transwell assays, flow cytometry and laser scanning confocal microscopy. The protein levels were detected by Western blotting. Whether circRNA_15430 sponges miR-382-5p was monitored with a dual-luciferase reporter assay. Furthermore, circRNA_15430 was analyzed in vivo in tumor growth with nude mice.

RESULTS

CircRNA_15430 is primarily localized in the cytoplasm of GC cells, and downregulated in the GC cell lines and tissues, and is negatively correlated with the tumor size. Downregulation of circRNA_15430 promotes proliferation, migration and suppresses cell apoptosis and autophagy in GC cells. Mechanically, circRNA_15430 acts as a miR-382-5p sponge, alleviating the inhibitory effect of miR-382-5p on its target ZCCHC14. Knockdown circRNA_15430 enhances tumor growth in vivo. In addition, circRNA_15430 was reduced in HP + gastritis tissues and HP-infected MGC-803 cells, reversing the pro-HP effect on autophagy. Additionally, miR-382-5p was increased in HP + gastritis tissue and HP-infected MGC-803 cells while ZCCHC14 decreased in HP-infected MGC-803 cells. MiR-382-5p reverses the effect of si-ZCCHC14 on autophagosome numbers in MGC-803 cells.

CONCLUSIONS

Therefore, circRNA_15430 plays an inhibitory role in GC and regulates the progression of HP infection-related GC, providing a novel molecular marker for GC therapy.

A novel long non-coding RNA XLOC_004787, is associated with migration and promotes cancer cell proliferation by downregulating mir-203a-3p in gastric cancer

BACKGROUND

Long noncoding RNAs (lncRNAs) have been identified as important regulatory factors implicated in a wide array of diseases, including various forms of cancer. However, the roles of most lncRNAs in the progression of gastric cancer (GC) remain largely unexplored. This study investigates the biological function and underlying mechanism of a novel lncRNA, XLOC_004787 in GC.

METHODS

The location of XLOC_004787 in GES-1 cells and HGC-27 cells were detected by fluorescence in situ hybridization (FISH) assay. The expression levels of XLOC_004787 were assessed using quantitative real-time fluorescence PCR (qRT-PCR) in various cell lines, including GES-1, MGC-803, MKN-45, BGC-823, SGC-7901, and HGC-27 cells. Functional assays such as Transwell migration, cell counting kit-8 (CCK-8), and colony formation experiments were employed to analyze the effects of XLOC_004787 and miR-203a-3p on cell migration and proliferation. Protein levels associated with GC in these cell lines were examined by Western blotting. The intracellular localization of β-catenin and P-Smad2/3 was assessed using immunofluorescence (IF) assay. Additionally, the interaction between XLOC_004787 and miR-203a-3p was investigated using a dual luciferase assay.

RESULTS

XLOC_004787 was localized at both the cytoplasm and nucleus of GES-1 cells and HGC-27 cells. Compared to normal tissues and GES-1 cells, XLOC_004787 expression was significantly upregulated in GC tissues and cells, with the highest and lowest expression observed in SGC-7901 and HGC-27 cells, respectively. Furthermore, a reduced expression of XLOC_004787 was seen to inhibit migration and proliferation in SGC-7901 cells. Western blotting analysis revealed that a decrease in XLOC_004787 expression correspondingly decreased the expression of N-cadherin, mmp2, mmp9, Snail, Vimentin, β-catenin, C-myc, Cyclin D1, and TGF-β, while concurrently increasing E-cadherin expression. This was also associated with diminished expression of P-Smad2/3 in relation to Smad2/3, and reduced P-Gsk3β expression in comparison to Gsk3β. Additionally, the nuclear entry of P-Smad2/3 and β-catenin was reduced by lower XLOC_004787 expression. Amplifying XLOC_004787 expression via pcDNA_XLOC_004787 suggested a potential for cancer promotion. Notably, XLOC_004787 was found to negatively regulate mir-203a-3p expression, with potential binding sites identified between the two. Higher mir-203a-3p expression was observed to decrease migration and proliferation, and enhance E-cadherin expression. Conversely, suppression of mir-203a-3p expression suggested a potential promotion of proliferation and migration in GC cells.

CONCLUSIONS

These results suggest that XLOC_004787, found to be upregulated in GC tissues, potentially promotes proliferation and migration in GC cells. This occurs through the activation of TGF-β and Wnt/β-catenin signaling pathways and the expression of EMT-related proteins. Additionally, XLOC_004787 may influence cell migration and proliferation by modulating the signaling pathway via the adsorption and inhibition of mir-203a-3p.

Newly discovered mechanisms that mediate tumorigenesis and tumour progression: circRNA-encoded proteins

Proteins produced by cap-independent translation mediated by an internal ribosome entry site (IRES) in circular RNAs (circRNAs) play important roles in tumour progression. To date, numerous studies have been performed on circRNAs and the proteins they encode. In this review, we summarize the biogenesis of circRNAs and the mechanisms regulating circRNA-encoded proteins expression. We also describe relevant research methods and their applications to biological processes such as tumour cell proliferation, metastasis, epithelial-mesenchymal transition (EMT), apoptosis, autophagy and chemoresistance. This paper offers deeper insights into the roles that circRNA-encoded proteins play in tumours. It also provides a theoretical basis for the use of circRNA-encoded proteins as biomarkers of tumorigenesis and for the development of new targets for tumour therapy.

circRanGAP1/miR-27b-3p/NRAS Axis may promote the progression of hepatocellular Carcinoma

BACKGROUND

Though circular RNAs (circRNAs) are the key regulators in tumor carcinogenesis, they remain largely unexplored in hepatocellular carcinoma (HCC).

METHODS

The expression of RanGAP1-derived circRNAs (circ_0063531, circ_0063534, circ_0063513, circ_0063518, circ_0063507, circ_0063723) were evaluated in eight paired HCC and normal tissues, and the correlation between circRanGAP1 (circ_0063531) expression and clinicopathological characteristics in 40 HCC patients was determined. The association between miR-27b-3p and circRanGAP1 or NRAS was predicted using bioinformatics analysis. The expression of circRanGAP1, miR-27b-3p, and NRAS were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The potential oncogenic role of circ-RanGAP1 was assessed using CCK-8, colony formation, transwell assays in vitro, subcutaneous tumor mouse model, vein tail metastatic model, and orthotopically implanted intrahepatic HCC model in vivo. Luciferase reporter and RNA immunoprecipitation (RIP) assays were used to explore the binding site between miR-27b-3p and circ-RanGAP1 or NRAS. Protein expression was detected using western blotting. The localization of miR-27b-3p and circ-RanGAP1 was investigated using fluorescence in situ hybridization (FISH). The level of immune infiltration was assessed by bioinformatics analysis, flow cytometry, and orthotopically implanted intrahepatic HCC models.

RESULTS

Here, we found elevated circRanGAP1 in the cells and clinical tissues of patients with HCC. Increased circRanGAP1 levels are associated with enlarged tumors and the advanced stage of TNM. CircRanGAP1 promotes the growth, migration, and HCC cell invasion, concurrently with the growth and metastasis of tumors in-vivo. Moreover, circRanGAP1 is mainly located inside the cytoplasm. Mechanistically, circRanGAP1 as an oncogene promotes HCC progression by miR-27b-3p/NRAS/ERK axis, furthermore, affects the infiltration level of tumor-associated macrophages probably by sponging miR-27b-3p. Immune infiltration analysis shows that NRAS is positively correlated with the levels of CD68+ tumor-associated macrophages in HCC samples and that NRAS and CD68 are related to the poor outcome of HCC.

CONCLUSION

These results reveal that circRanGAP1 is a HCC oncogene that function by the miR-27b-3p/NRAS/ERK axis and regulates the infiltration levels of tumor-associated macrophages by sponging miR-27b-3p. Therefore, circRANGAP1/ NRAS axis may be an important potential treatment target against HCC.