Promoted Gastric Cancer Cell Proliferation Research Articles

CARM1 promotes gastric cancer progression by regulating TFE3 mediated autophagy enhancement through the cytoplasmic AMPK-mTOR and nuclear AMPK-CARM1-TFE3 signaling pathways

BackgroundThe role of CARM1 in tumors is inconsistent. It acts as an oncogene in most cancers but it inhibits the progression of liver and pancreatic cancers. CARM1 has recently been reported to regulate autophagy, but this function is also context-dependent. However, the effect of CARM1 on gastric cancer (GC) has not been studied. We aimed to explore whether CARM1 was involved in the progression of GC by regulating autophagy.MethodsThe clinical values of CARM1 and autophagy in GC were evaluated by immunohistochemistry and qRT–PCR. Transmission electron microscopy, immunofluorescence and western blotting were employed to identify autophagy. The role of CARM1 in GC was investigated by CCK-8, colony formation and flow cytometry assays in vitro and a xenograft model in vivo. Immunoprecipitation assays were performed to determine the interaction of CARM1 and TFE3.ResultsCARM1 was upregulated in clinical GC tissues and cell lines, and higher CARM1 expression predicted worse prognosis. CARM1 enhanced GC cell proliferation, facilitated G1-S transition and inhibited ER stress-induced apoptosis by regulating autophagy. Importantly, treatment with a CARM1 inhibitor rescued the tumor-promoting effects of CARM1 both in vitro and in vivo. Furthermore, we demonstrated that CARM1 promoted TFE3 nuclear translocation to induce autophagy through the cytoplasmic AMPK-mTOR and nuclear AMPK-CARM1-TFE3 signaling pathways.ConclusionCARM1 promoted GC cell proliferation, accelerated G1-S transition and reduced ER stress-induced apoptosis by regulating autophagy. Mechanistically, CARM1 triggered autophagy by facilitating TFE3 nuclear translocation through the AMPK-mTOR and AMPK-CARM1-TFE3 signaling pathways.

RETRACTED: PINK1 deficiency in gastric cancer compromises mitophagy, promotes the Warburg effect, and facilitates M2 polarization of macrophages.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and authors. Following the publication of the above article, the Editor was notified by a concerned reader that the authors supplied duplicated images. Specifically, that in Fig. 5A, both FACS panels are identical and in Fig. 5E, two different proteins (HK2 and PDK1) have the same western blot. After checking the data in relation with Fig. 5A and Fig. 5E, the authors have confirmed that the two pictures indeed have the problems of duplication. The authors reported that this problem came from the authors’ unintentional behavior, which may be due to a copy and paste error in the manner of image processing. The authors sincerely apologize for the inconvenience caused to our Editors and readers. Due to this duplication error, the authors and Editor have made the decision to retract this paper.

CCT5 induces epithelial-mesenchymal transition to promote gastric cancer lymph node metastasis by activating the Wnt/β-catenin signalling pathway.

Lymph node (LN) metastasis confers gastric cancer (GC) progression, poor survival and cancer-related death. Aberrant activation of Wnt/β-catenin promotes epithelial-mesenchymal transition (EMT) and LN metastasis, whereas the constitutive activation mutation of Wnt/β-catenin is rare in GC, suggesting that the underlying mechanisms enhancing Wnt/β-catenin activation need to be further investigated and understood. Bioinformatics analyses and immunohistochemistry (IHC) were used to identify and detect LN metastasis-related genes in GC. Cellular functional assays and footpad inoculation mouse model illustrate the biological function of CCT5. Co-immunoprecipitation assays, western blot and qPCR elucidate the interaction between CCT5 and E-cadherin, and the regulation on β-catenin activity. CCT5 is upregulated in LN metastatic GCs and correlates with poor prognosis. In vitro assays prove that CCT5 markedly promotes GC cell proliferation, anti-anoikis, invasion and lymphatic tube formation. Moreover, CCT5 enhances xenograft GC growth and popliteal lymph node metastasis in vivo. Furthermore, CCT5 binds the cytoplasmic domain of E-cadherin and abrogates the interaction between E-cadherin and β-catenin, thereby releasing β-catenin to the nucleus and enhancing Wnt/β-catenin signalling activity and EMT. CCT5 promotes GC progression and LN metastasis by enhancing wnt/β-catenin activation, suggesting a great potential of CCT5 as a biomarker for GC diagnosis and therapy.

MiR-1298-5p level downregulation induced by Helicobacter pylori infection inhibits autophagy and promotes gastric cancer development by targeting MAP2K6

Helicobacter pylori infection is a leading cause of gastric cancer (GC). However, the underlying mechanisms have not yet been fully elucidated. We aimed to identify microRNAs (miRNAs) regulated by H. pylori infection and their underlying mechanisms in gastric carcinogenesis. Using a mouse model, it was established that H. pylori infection inhibited autophagy in the gastric mucosa. Importantly, H. pylori infection decreased miR-1298-5p levels in human and mouse gastric tissues and human gastric cell lines. Furthermore, the downregulation of miR-1298-5p levels remarkably inhibited autophagy, ultimately increasing the intracellular H. pylori load, which was detected using a gentamicin protection assay. A series of in vitro assays showed that the downregulation of miR-1298-5p expression promoted GC cell proliferation, migration, and invasion. Mechanistically, using bioinformatics prediction, miRNA pull-down assays, and luciferase reporter assays, mitogen-activated protein kinase kinase 6 (MAP2K6) was found to be the direct target of miR-1298-5p, through which miR-1298-5p regulated autophagy and GC cell viability and motility. Moreover, MAP2K6/p38 mitogen-activated protein kinase (MAPK) axis was determined to be the downstream pathway of miR-1298-5p. These findings revealed that H. pylori infection was found to inhibit autophagy and promote tumor growth by regulating miR-1298-5p expression and the miR-1298-5p/MAP2K6/p38 MAPK axis might be a new avenue for the clinical management of H. pylori infection and H. pylori-associated GC.

+HOXA10-AS Promotes Malignant Phenotypes of Gastric Cancer via Upregulating HOXA10.

Objective To study the role of long noncoding RNA HOXA10-AS in gastric cancer (GC) and its underlying mechanism which is one of the most common and fetal malignancies. Long noncoding RNA HOXA10-AS is highly expressed and acts in an oncogenic role in cancers. However, its roles in GC are still unknown. Methods The expression of HOXA10-AS and HOXA10 in GC tissues from the TCGA database was analyzed. Western blot and qRT-PCR assays were applied to examine the expression of HOXA10-AS and HOXA10. Cell proliferation was evaluated with CCK-8 and EdU incorporation assays. Cell apoptosis was analyzed by flow cytometry. Migratory and invasive capacities were evaluated with wound healing and transwell assays. Results HOXA10-AS and HOXA10 were upregulated in GC, and their expressions were positively correlated. Knockdown of HOXA10-AS inhibited HOXA10 expression in GC cells. Furthermore, knockdown of HOXA10-AS restrained GC cell proliferation, migration, and invasion but promoted apoptosis. In addition, overexpression of HOXA10-AS promoted malignant phenotypes of GC cells, but all these effects could be reversed by knockdown of HOXA10. Conclusion HOXA10-AS promoted GC cell proliferation, migration and invasion and enhanced apoptosis via upregulating HOXA10. Our study implies a novel regulatory mechanism of malignant phenotypes and provides potential therapeutic targets for GC.

CircRNA ACVR2A Sponges miR-1290 to Modulate Cell Progression in Gastric Cancer.

Background In recent years, the abnormal expression of circRNAs has been identified to be strongly associated with tumor tissues. In this study, we focused on circACVR2A with a remarkably upregulated expression in gastric tissues and further explored its role in the pathogenic progression of gastric cancer (GC). Methods The differentially expressed circACVR2A in GC tissues and four cell lines (MKN-45, SNU-1, HGC-27, and SGC-7901) was identified by qRT-PCR method. Then, the effect of circACVR2A and miR-1290 on HGC-27 cell proliferation was measured by CCK8 and the colony formation methods. The effect of circACVR2A and miR-1290 on HGC-27 cell metastasis was estimated by transwell assay. The interaction of circACVR2A and miR-1290 was further detected. Results The relative level of circACVR2A in GC tissues and cell lines is remarkably upregulated. The downregulation of circACVR2A promotes GC cell proliferation and metastasis and suppressed the expression level of E-cadherin and Vimentin. The miR-1290 inhibitor reversed the effect of circACVR2A on cell progression in GC cell. Conclusion circACVR2A competitively sponged miR-1290 and was exerted as a tumor suppressor gene oncogene via a circACVR2A/miR-1290 axis, suggesting it as a possible biomarker for GC therapy.

LRG1 mediated by ATF3 promotes growth and angiogenesis of gastric cancer by regulating the SRC/STAT3/VEGFA pathway.

Increasing evidence indicates that leucine-rich-alpha-2-glycoprotein 1 (LRG1) is associated with multiple malignancies, but whether it participates in gastric cancer (GC) angiogenesis remains unclear. The expression levels of LRG1 were assessed in GC samples. Endothelial tube formation analysis, HUVEC migration assay, chorioallantoic membrane assay (CAM), and xenograft tumor model were used to investigate the effect of LRG1 on angiogenesis in gastric cancer. The involvement of activating transcription factor 3 (ATF3) was analyzed by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay. Western blot and enzyme-linked immunosorbent assay were performed to measure the SRC/STAT3/VEGFA pathway. LRG1 was overexpressed in GC tissues and associated with cancer angiogenesis. In addition, LRG1 markedly promoted GC cell proliferation in vitro and in vivo. Moreover, overexpression of LRG1 could stimulate GC angiogenesis in vitro and in vivo. Then, we identified ATF3 promotes the transcription of LRG1 and is a positive regulator of angiogenesis. Additionally, LRG1 could activate VEGFA expression via the SRC/STAT3/ VEGFA pathway in GC cells, thus contributing to the angiogenesis of GC. The present study suggests LRG1 plays a crucial role in the regulation of angiogenesis in GC and could be a potential therapeutic target for GC.

LncRNA OGFRP1 promotes cell proliferation and suppresses cell radiosensitivity in gastric cancer by targeting the miR-149-5p/MAP3K3 axis.

Gastric cancer (GC) is an aggressive malignancy with high incidence and mortality. Radiotherapy is a common treatment for patients with advanced GC. Many long noncoding RNAs (lncRNAs) have been verified to affect the radiosensitivity of multiple cancers in previous studies. Nevertheless, whether lncRNA opioid growth factor receptor pseudogene 1 (OGFRP1) affects the radiosensitivity of GC has not been determined. We hypothesized that OGFRP1 might affect cellular processes in GC development. The present study aims to explore the role of OGFRP1 in GC development. First, high expression of OGFRP1 in GC tissues and cells was determined through RT-qPCR. Subsequently, functional assays including colony formation assays, 5-Ethynyl-2'-deoxyuridine assays and flow cytometry analyses were performed to probe the biological functions of OGFRP1 in GC. Specifically, the effect of OGFRP1 on the radiosensitivity of GC cells was detected. Subsequently, with the help of the starBase tool, we found that miR-149-5p might bind to OGFRP1, which was confirmed through a luciferase reporter assay. Furthermore, we identified that MAP3K3 was targeted by miR-149-5p in GC cells. Finally, the results from rescue experiments validated that enhanced MAP3K3 expression counteracted the effect of OGFRP1 silencing on GC cell proliferation, apoptosis and radiosensitivity. Overall, OGFRP1 was determined to promote GC cell proliferation while suppressing cell apoptosis and radiosensitivity by regulating the miR-149-5p/MAP3K3 axis.

LINC00152 acts as a competing endogenous RNA of HMGA1 to promote the growth of gastric cancer cells

BackgroundLong noncoding RNAs (lncRNAs) play important roles in almost every stage of cancer development. Given the competing endogenous RNA (ceRNA) hypothesis for the regulation of gene expression, we investigated the role of LINC00152 as a ceRNA in gastric cancer (GC) cells.MethodsGastric cancer cell lines were used in this study. Mimics of miRNAs and siRNA were used to evaluate the interaction between LINC00152 and HMGA1. The quantitative real‐time polymerase chain reaction was performed for analyzing gene expression at the transcriptional level. Flow cytometry assay of cell cycle and western blot analysis of related protein expression levels were performed. Online databases such as TCGA and TIMER were used to determine the possibility of HMGA1 and LINC00152 as GC markers and their role in immune infiltration.ResultsTreating GC cell lines with LINC00152 siRNAs downregulated the expression of HMGA1. The cell cycle was arrested in the S phase following a reduction in LINC00152 or HMGA1 expression, whereas the expression of the cell cycle inhibitor P27 increased. In this study, we showed that acting as a ceRNA of HMGA1, LINC00152 has the same function as HMGA1, considering that it could control the cell cycle and promote GC cell proliferation. The TCGA database showed that LINC00152 might be used as a diagnostic marker for GC.ConclusionsThese findings provide mechanistic insights into the role of LINC00152 as a ceRNA to regulate HMGA1 expression in GC cells, where it can promote the proliferation of the GC cells by regulating the expression of the P27.

HOXC10 indicates poor survival outcome in gastric cancer and promotes G1/S cell cycle transition through transcriptional repression of p21.

Homeobox (HOX) genes encode proteins that function as transcription factors during embryogenesis and tumorigenesis. We have previously reported upregulation of HOXC10 in gastric cancer (GC) tissues using cDNA microarray analysis. Though the functional role of HOXC10 in GC has been briefly reported, its specific mechanism is not fully understood. We analyzed the expression of HOXC10 in GC tissues, as well as its correlation with the survival outcome. By in vitro and in vivo assays, we further investigated the role of HOXC10 on cell cycle control and proliferation. Finally, we screened potential downstream targets of HOXC10 by cDNA microarray and explored the role of HOXC10 in p21 transcriptional repression through a dual luciferase reporter and chromatin immunoprecipitation. We illustrated the upregulation of HOXC10 in GC tissues and high HOXC10 expression related to poor survival outcome. Multivariable COX regression analysis showed that HOXC10 was an independent predictor of survival (HR=1.863; 95% CI: 1.076-3.225). Functionally, HOXC10 could promote GC cell proliferation and tumor growth in nude mice. Overexpression of HOXC10 accelerated G1/S cell cycle transition, whereas knocking down HOXC10 induced cell cycle arrest at the G1 phase. Critical factors of G1/S cell cycle transition including p21, CDK2, and c-Myc, were regulated by HOXC10. Importantly, an inverse correlation between p21 and HOXC10 expression in GC cell lines and tissues was observed. HOXC10 could directly bind to the promoter region of p21 and repress its transcriptional activity. Collectively, we identified HOXC10 as a predictor of poor prognosis in GC patients, and a novel transcriptional regulator of p21 in the G1/S cell cycle transition.

LncRNA TNFRSF10A-AS1 promotes gastric cancer by directly binding to oncogenic MPZL1 and is associated with patient outcome.

Background: LncRNA is closely associated with the progression of human tumors. The role of lncRNA TNFRSF10A-AS1 (T-AS1) in gastric cancer (GC) is still unclear. We aim to investigate the functional significance and the underlying mechanisms of T-AS1 in the pathogenesis and progression of GC.Experimental Design: The clinical impact of T-AS1 was assessed in 103 patients with GC. The biological function of T-AS1 was studied in vitro and in vivo. T-AS1 downstream effector were identified by RNA sequencing and RNA pulldown assay.Results: T-AS1 was upregulated in GC cell lines and GC tissues as compared to adjacent non-cancer tissues (n = 47, P < 0.001). Multivariate analysis showed that GC patients with T-AS1 high expression had a significantly shortened survival (n=103, P < 0.05). T-AS1 significantly promoted GC cell proliferation, cell-cycle progression, and cell migration/invasion abilities, but suppressed cell apoptosis. Silencing of T-AS1 in GC cells exerted opposite effects in vitro. Knockout of T-AS1 significantly inhibited xenograft tumor growth in nude mice. Mechanistically, T-AS1 directly bound to Myelin Protein Zero Like 1 (MPZL1). MPZL1 showed an oncogenic function in GC by promoting cell proliferation, migration and invasion but inhibiting cell apoptosis. High expression of MPZL1 was associated with poor survivor of GC patients. Knockdown of MPZL1 could abrogate the effect of T-AS1 in the tumor-promoting function.Conclusions: T-AS1 plays a pivotal oncogenic role in GC and is an independent prognostic factor for GC patients. The oncogenic function of T-AS1 is dependent on its direct downstream effector MPZL1.

TTPAL promotes gastric tumorigenesis by directly targeting NNMT to activate PI3K/AKT signaling

Copy number alterations are crucial for gastric cancer (GC) development. In this study, Tocopherol alpha transfer protein-like (TTPAL) was identified to be highly amplified in our primary GC cohort (30/86). Multivariate analysis showed that high TTPAL expression was correlated with the poor prognosis of GC patients. Ectopic expression of TTPAL promoted GC cell proliferation, migration, and invasion in vitro and promoted murine xenograft tumor growth and lung metastasis in vivo. Conversely, silencing of TTPAL exerted significantly opposite effects in vitro. Moreover, RNA-sequencing and co-immunoprecipitation (Co-IP) followed by liquid chromatograph-mass spectrometry (LC-MS) identified that TTPAL exerted oncogenic functions via the interaction of Nicotinamide-N-methyl transferase (NNMT) and activated PI3K/AKT signaling pathway. Collectively, TTPAL plays a pivotal oncogenic role in gastric carcinogenesis through promoting PI3K/AKT pathway via cooperating with NNMT. TTPAL may serve as a prognostic biomarker of patients with GC.

CircDIDO1 inhibits gastric cancer progression by encoding a novel DIDO1-529aa protein and regulating PRDX2 protein stability

BackgroundCircular RNAs (circRNAs) play important roles in cancer development and progression. The purpose of this study is to identify aberrantly expressed circRNAs in gastric cancer (GC), unravel their roles in GC progression, and provide new targets for GC diagnosis and therapy.MethodsBioinformatic analyses were performed to identify the aberrantly expression of hsa_circ_0061137 (termed as circDIDO1) in GC. Gain- and loss-of-function studies were performed to examine the biological roles of circDIDO1 in GC progression. Tagged RNA affinity purification, mass spectrometry, immunofluorescence, co-immunoprecipitation, and Western blot were used to identify circRNA-interacting and circRNA-encoded proteins. RNA sequencing, qRT-PCR, and Western blot were performed to analyze circRNA-regulated downstream target genes and signaling pathways. Mouse tumor models were used to analyze the effects of circDIDO1 on GC growth and metastasis.ResultsCircDIDO1 was transcribed from human DIDO1 (death-inducer obliterator 1) gene and formed by back-splicing of exons 2–6 of the linear transcript. circDIDO1 was down-regulated in GC tissues and its low levels were associated with larger tumor size, distal metastasis, and poor prognosis. CircDIDO1 overexpression inhibited while knockdown promoted GC cell proliferation, migration and invasion. CircDIDO1 overexpression suppressed GC growth and metastasis in mouse tumor models. Mechanistically, circDIDO1 encoded a novel 529aa protein that directly interacted with poly ADP-ribose polymerase 1 (PARP1) and inhibited its activity. CircDIDO1 also specifically bound to peroxiredoxin 2 (PRDX2) and promoted RBX1-mediated ubiquitination and degradation of PRDX2, which led to the inactivation of its downstream signaling pathways.ConclusionsCircDIDO1 is a new circRNA that has tumor suppressor function in GC and it may serve as a potential prognostic biomarker and therapeutic target for GC.

Oncogenic PAX6 elicits CDK4/6 inhibitor resistance by epigenetically inactivating the LATS2-Hippo signaling pathway.

Intrinsic resistance to CDK4/6 inhibitors hinders their clinical utility in cancer treatment. Furthermore, the predictive markers of CDK4/6 inhibitors in gastric cancer (GC) remain incompletely described. Here, we found that PAX6 expression was negatively correlated with the response to palbociclib in vitro and in vivo in GC. We observed that the PAX6 expression level was negatively correlated with the overall survival of GC patients and further showed that PAX6 can promote GC cell proliferation and the cell cycle. The cell cycle is regulated by the interaction of cyclins with their partner serine/threonine cyclin‐dependent kinases (CDKs), and the G1/S‐phase transition is the main target of CDK4/6 inhibitors. Therefore, we tested whether PAX6 expression was correlated with the GC response to palbociclib. We found that PAX6 hypermethylates the promoter of LATS2 and inactivates the Hippo pathway, which upregulates cyclin D1 (CCND1) expression. This results in a suppressed response to palbociclib in GC. Furthermore, we found that the induction of the Hippo signaling pathway or treatment with a DNA methylation inhibitor could overcome PAX6‐induced palbociclib resistance in GC. These findings uncover a tumor promoter function of PAX6 in GC and establish overexpressed PAX6 as a mechanism of resistance to palbociclib.

CircTMC5 promotes gastric cancer progression and metastasis by targeting miR-361-3p/RABL6.

Gastric cancer (GC) is common in East Asia, yet its molecular and pathogenic mechanisms remain unclear. Circular RNAs (circRNAs) are differentially expressed in GC and may be promising biomarkers. Here, we investigated the role and regulatory mechanism of circTMC5 in GC. CircTMC5 expression was detected in human GC and adjacent tissues using microarray assays and qRT-PCR, while the clinicopathological characteristics of patients with GC were used to assess its diagnostic and prognostic value. The circTMC5/miR-361-3p/RABL6 axis was examined in vitro and vivo, and the immune roles of RABL6 were evaluated using bioinformatics analyses and immunohistochemistry (IHC). CircTMC5 was highly expressed in GC tissues, plasma, and cell lines, and was closely related to histological grade, pathological stage, and T classification in patients with GC. CircTMC5 expression was also an independent prognostic factor for GC and its combined detection with carcinoembryonic antigen may improve GC diagnosis. Low circTMC5 expression correlated with good prognosis, inhibited GC cell proliferation, and promoted apoptosis. Mechanistically, circTMC5 overexpression promoted GC cell proliferation, invasion, and metastasis but inhibited apoptosis by sponging miR-361-3p and up-regulating RABL6 in vitro and vivo, whereas miR-361-3p up-regulation had the opposite effects. RABL6 was highly expressed in GC and was involved in immune regulation and infiltration in GC. CircTMC5 promotes GC and sponges miR-361-3p to up-regulate RABL6 expression, thus may have diagnostic and prognostic value in GC. RABL6 also displays therapeutic promise due to its role in the immune regulation of GC.

CircRNA_100290 promotes GC cell proliferation and invasion via the miR-29b-3p/ITGA11 axis and is regulated by EIF4A3

BackgroundCircular RNAs (circRNAs) have been reported to be important regulators of the development and progression of various carcinomas. However, the role of circRNA_100290 in gastric cancer (GC) is still unclear. This study aimed to investigate the role of circRNA_100290 in GC invasion and metastasis and the possible underlying mechanism.MethodsThe expression of circRNA_100290 in GC cells and tissues was examined using quantitative real-time polymerase chain reaction (qRT-PCR). The role of circRNA_100290 in cell proliferation, migration, and invasion was evaluated in the AGS and HGC-27 cell lines in vitro. Bioinformatics tools, dual-luciferase reporter assays, Western blot assays and qRT-PCR were used to explore the pathways downstream of circRNA_100290. The mechanism underlying the regulation of circRNA_100290 expression was explored using RNA immunoprecipitation, qRT-PCR, and Western blot assays.ResultsThe expression of circRNA_100290 was significantly upregulated in GC cells and 102 GC tissues, and high circRNA_100290 expression in GC was closely related to Borrmann’s type, lymph node metastasis and tumour-node-metastasis stage. In vitro, knockdown of circRNA_100290 in AGS and HGC-27 cells significantly inhibited cell proliferation, migration, and invasion. Mechanistically, a dual-luciferase reporter assay confirmed the direct interaction between circRNA_100290 and miR-29b-3p, which targets ITGA11, an oncogene that is closely related to epithelial–mesenchymal transition (EMT). In addition, EIF4A3, an RNA-binding protein (RBP), could inhibit the formation of circRNA_100290 by binding to the flanking sites of circRNA_100290. Low EIF4A3 expression in GC was related to a poor prognosis.ConclusionsElevated circRNA_100290 expression in GC promotes cell proliferation, invasion and EMT via the miR-29b-3p/ITGA11 axis and might be regulated by EIF4A3. CircRNA_100290 might be a promising biomarker and target for GC therapy.Graphical abstract

H. pylori infection induces CXCL8 expression and promotes gastric cancer progress through downregulating KLF4

Tumour-derived CXCL8 facilitates the movement of myeloid-derived suppressor cells, which are able to restrain antitumour immune responses to the tumour microenvironment. Kruppel-like factor 4 (KLF4) is a potential tumour suppressor in gastric cancer (GC). However, knowledge regarding correlations between KLF4 and CXCL8 in GC is limited. We use cellular and molecular biological methods to assess whether these two factors interact in GC. Expression CXCL8 and KLF4 was altered in human GC tissues compared to normal gastric tissues in opposite ways. Additionally, cytotoxin-associated gene A protein (CagA) gene transduction or Helicobacter pylori(H. pylori) infection upregulated CXCL8 expression. Knockdown of KLF4 expression increased CXCL8 protein and RNA expression, whereas its overexpression had the opposite effect. CXCL8-mediated enhancement of GC cell migration and proliferation was reversed by upregulation of KLF4 expression. Further mechanistic research revealed that KLF4 binds the CXCL8 promoter, suppressing CXCL8 transcription. Moreover, CXCL8 stimulation reduced KLF4 protein expression and promoted GC cell proliferation and migration, eventually promoting neoplasm growth in vivo. Together, our findings demonstrate that CagA promotes CXCL8 and inhibits KLF4. CXCL8 is a decisive downstream target gene of KLF4, and KLF4 negatively regulates CXCL8 in GC. Furthermore, CXCL8's negative regulation of KLF4 in vivo and in vitro, indicates that CagA may downregulate KLF4 by inducing CXCL8 expression, low expression of KLF4 further promotes that of CXCL8, forming a vicious circle in GC. Targeted KLF4 activation might improve the immunosuppressive microenvironment through direct negative regulation of CXCL8, providing a new potential target to strengthen the efficacy of immunotherapy in GC patients.

LINC00665 promotes cell proliferation, invasion, and metastasis by activating the TGF-β pathway in gastric cancer

Background and AimsAccumulating studies have demonstrated that long noncoding RNA plays a vital role in cancer progression. A previous study reported that LINC00665 was overexpressed and acted as a key tumor promoter in lung cancer, but the role of LINC00665 in gastric cancer (GC) remained uncharacterized. Thus, this study aimed to explore the mechanism of LINC00665 in GC. MethodsLINC00665 expression was explored using the Cancer Genome Atlas (TCGA), and a meta-analysis was conducted to assess the expression and prognostic value of LINC00665 in GC from Gene Expression Omnibus databases and the TCGA dataset. Real-time polymerase chain reaction (RT-PCR) was then conducted to verify the LINC00665 expression in GC tissues and cell lines. The effects of LINC00665 on cell proliferation, invasion, metastasis, and cell cycle in GC were evaluated using the CCK-8, wound healing, Transwell, and flow cytometry assays. In vitro validation was also performed. ResultsLINC00665 overexpression was found in GC, and LINC00665 upregulation was significantly related to poor overall survival and disease-free survival. LINC00665 expression was associated with tumor depth, lymph node metastasis, and TNM stage. Univariate and multivariate analyses proved that LINC00665 could be an independent prognostic biomarker in GC. LINC00665 knockdown subsequently inhibited cell proliferation, invasion, and metastasis in GC cell lines; promoted cell apoptosis; and arrested GC cell lines in the G0/G1 phase. Western blot analysis indicated that LINC00665 silencing inhibited epithelial–mesenchymal transition and decreased the expression levels of TGF-β1, Smad2, and α-SMA. ConclusionLINC00665 can be a potential diagnostic and prognostic biomarker for GC patients, and LINC00665 promotes GC cell proliferation, invasion, and metastasis by activating the TGF-β signal pathway.

TASP1 Promotes Proliferation and Migration in Gastric Cancer via EMT and AKT/P-AKT Pathway.

Threonine aspartase 1 (TASP1) was reported to function in the development of cancer. However, the regulatory mechanism of TASP1 in gastric cancer (GC) remains unclear. In this study, we determined the expression of TASP1 in tissues of GC patients, GC cells by qRT-PCR, and western blot and assessed the relationship between TASP1 and GC cell proliferation and migration via CCK-8 and transwell assay. It was found that the expression of TASP1 in GC tissues or GC cell lines was significantly higher than that in normal adjacent tissues or normal cells. The proliferation and migration of GC cells were inhibited upon TASP1 knockdown. Mechanism investigation revealed that TASP1 promoted GC cell proliferation and migration through upregulating the p-AKT/AKT expression. TASP1 induced GC cell migration via the epithelial -mesenchymal transition (EMT) pathway. In conclusion, TASP1 promotes GC progression through the EMT and AKT/p-AKT pathway, and it may serve as a new potential biomarker and therapeutic target for GC.

HOXB13 promotes gastric cancer cell migration and invasion via IGF-1R upregulation and subsequent activation of PI3K/AKT/mTOR signaling pathway

AimsThis study aimed at exploring HOXB13 expression and function in gastric cancer (GC), and the underlying molecular mechanism. Materials and methodsHOXB13 and fat mass and obesity-associated protein (FTO) expression in GC and non-GC tissues of GC patients were analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) and verified by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and western blotting. The regulatory relationship between FTO and HOXB13 was verified via RT-qPCR, methylated RNA immunoprecipitation sequencing (MeRIP-seq), and double luciferase reporter gene assay. The effects of HOXB13 and FTO on proliferation, invasion, and migration of GC cells were studied using EdU and Transwell assays. Key findingsHOXB13 and FTO expression was abnormally high in GC tissues and cell lines, with no significant correlation between HOXB13 and FTO expression and the prognosis of GC patients. Inhibiting FTO expression in GC cells decreased HOXB13 methylation and upregulated HOXB13 expression. Inhibiting HOXB13 and FTO expression suppressed GC cell proliferation, migration, and invasion. Decreased HOXB13 expression suppressed PI3K/AKT/mTOR signaling pathway activity, while atypical HOXB13 expression promoted it. A probable downstream target of HOXB13 was insulin-like growth factor 1 receptor (IGF-1R); a decrease in IGF-1R relieved GC cell migration, invasion, and proliferation and inhibited PI3K/AKT/mTOR signaling pathway activity promoted by atypical HOXB13 expression. SignificanceHOXB13 and FTO expression is elevated in GC. FTO suppresses HOXB13 methylation; FTO and HOXB13 expression promotes GC cell proliferation, migration, and invasion. HOXB13 expression intensifies GC invasion through PI3K/AKT/mTOR signaling via IGF-1R. HOXB13 and associated signaling pathways can be effective targets for GC therapy.