CMYC-initiated HNF1A-AS1 overexpression maintains the stemness of gastric cancer cells.

Cancer stem cells (CSCs) are believed to be responsible for cancer metastasis and recurrence due to their self-renewal ability and resistance to treatment. However, the mechanisms that regulate the stemness of CSCs remain poorly understood. Recently, evidence has emerged suggesting that long non-coding RNAs (lncRNAs) play a crucial role in regulating cancer cell function in different types of malignancies, including gastric cancer (GC). However, the specific means by which lncRNAs regulate the function of gastric cancer stem cells (GCSCs) are yet to be fully understood. In this study, we investigated a lncRNA known as HNF1A-AS1, which is highly expressed in GCSC s and serves as a critical regulator of GCSC stemness and tumorigenesis. Our experiments, both in vitro and in vivo, demonstrated that HNF1A-AS1 maintained the stemness of GC cells. Further analysis revealed that HNF1A-AS1, transcriptionally activated by CMYC, functioned as a competing endogenous RNA by binding to miR-150-5p to upregulate ß-catenin expression. This in turn facilitated the entry of ß-catenin into the nucleus to activate the Wnt/ß-catenin pathway and promote CMYC expression, thereby forming a positive feedback loop that sustained the stemness of GCSCs. We also found that blocking the Wnt/ß-catenin pathway effectively inhibited the function of HNF1A-AS1, ultimately resulting in the inhibition of GCSC stemness. Taken together, our results demonstrated that HNF1A-AS1 is a regulator of the stemness of GCSCs and could serve as a potential marker for targeted GC therapy.

PIN1P1 is activated by CREB1 and promotes gastric cancer progression via interacting with YBX1 and upregulating PIN1.

Long noncoding RNAs (lncRNAs) play critical roles in the carcinogenesis and progression of cancers. However, the role and mechanism of the pseudogene lncRNA PIN1P1 in gastric carcinoma remain unclear. The expression and effects of lncRNA PIN1P1 in gastric cancer were investigated. The transcriptional regulation of CREB1 on PIN1P1 was determined by ChIP and luciferase assays. The mechanistic model of PIN1P1 in gastric cancer was further explored by RNA pull-down, RIP and western blot analysis. PIN1P1 was overexpressed in gastric cancer tissues, and upregulated PIN1P1 predicted poor prognosis in patients. CREB1 was directly combined with the promoter region of PIN1P1 to promote the transcription of PIN1P1. CREB1-mediated enhanced proliferation, migration and invasion could be partially reversed by downregulation of PIN1P1. Overexpressed PIN1P1 promoted the proliferation, migration and invasion of gastric cancer cells, whereas decreased PIN1P1 showed the opposite effects. PIN1P1 directly interacted with YBX1 and promoted YBX1 protein expression, leading to upregulation of PIN1, in which E2F1 may be involved. Silencing of YBX1 during PIN1P1 overexpression could partially rescue PIN1 upregulation. PIN1, the parental gene of PIN1P1, was elevated in gastric cancer tissues, and its upregulation was correlated with poor patient outcomes. PIN1 facilitated gastric cancer cell proliferation, migration and invasion. To sum up, CREB1-activated PIN1P1 could promote gastric cancer progression through YBX1 and upregulating PIN1, suggesting that it is a potential target for gastric cancer.

CAP2 promotes gastric cancer metastasis by mediating the interaction between tumor cells and tumor-associated macrophages.

The metastasis of cancer cells is the main cause of death in patients with gastric cancer (GC). Mounting evidence has demonstrated the vital importance of tumor-associated macrophages in promoting tumor invasion and metastasis; however, the interaction between tumor cells and macrophages in GC is largely unknown. In this study, we demonstrated that cyclase-associated protein 2 (CAP2) was upregulated in GC, especially in cases with lymph node metastasis, and was correlated with a poorer prognosis. The transcription factor JUN directly bound to the promoter region of CAP2 and activated CAP2 transcription. The N-terminal domain of CAP2 bound to the WD5 to WD7 domains of receptor for activated C kinase 1 (RACK1) and induced M2 macrophage polarization by activating the SRC/focal adhesion kinase (FAK)/ERK signaling pathway, which resulted in IL-4 and IL-10 secretion. Polarized M2 macrophages induced premetastatic niche formation and promoted GC metastasis by secreting TGFB1, which created a TGFB1/JUN/CAP2 positive-feedback loop to activate CAP2 expression continuously. Furthermore, we identified salvianolic acid B as an inhibitor of CAP2, which effectively inhibited GC cell invasion capabilities by suppressing the SRC/FAK/ERK signaling pathway. Our data suggest that CAP2, a key molecule mediating the interaction between GC cells and tumor-associated macrophages, may be a promising therapeutic target for suppressing tumor metastasis in GC.

ETS-1-activated LINC01016 over-expression promotes tumor progression via suppression of RFFL-mediated DHX9 ubiquitination degradation in breast cancers.

Long non-coding RNAs (lncRNAs) are key regulators during the development of breast cancer (BC) and thus may be viable treatment targets. In this study, we found that the expression of the long intergenic non-coding RNA 01016 (LINC01016) was significantly higher in BC tissue samples with positive lymph node metastasis. LINC01016, which is activated by the transcription factor ETS-1, contributes to the overt promotion of cell proliferation activity, enhanced cell migratory ability, S phase cell cycle arrest, and decreased apoptosis rate. By RNA pull-down assays and mass spectrometry analyses, we determined that LINC01016 competitively bound and stabilized DHX9 protein by preventing the E3 ubiquitin ligase RFFL from binding to DHX9, thereby inhibiting DHX9 proteasomal degradation. This ultimately led to an increase in intracellular DHX9 expression and activated PI3K/AKT signaling, with p-AKT, Bcl-2, and MMP-9 involvement. This is the first study to reveal that the LINC01016/DHX9/PI3K/AKT axis plays a critical role in the progression of BC, and thus, LINC01016 may serve as a potential therapeutic target for patients with BC.

Construction of coaxial liquid centrifugal platform for the extraction of active ingredients from natural products.

In the classical natural product extraction and separation process, it is tedious and requires large amounts of reagents and time. In this study, an efficient coaxial liquid centrifugal oil-water-oil triple-liquid-phase system with a simple structure and convenient operation was successfully constructed and used to extract flavonoids from Platycladi Cacumen. The results showed that the coaxial liquid centrifugal platform constructed in this study had good stability and 6 ml was the minimum volume of the middle phase for 1000 rpm to stabilize the system. Besides, it was easy to repeat the operation: the relative standard deviations of the extraction yields of flavonoids and sugar in six parallel operations were all less than 10%. Moreover, it was only one-tenth of the time required for this method as traditional liquid-liquid extraction while reducing the use of volatile organic reagents. Finally, the new method was more selective than the traditional method for the extraction of flavonoids. Therefore, this study provides a possibility for the coaxial liquid centrifugal platform to be used in multi-liquid phase systems to achieve the simultaneous extraction of different parts of natural products by different liquid phases. It is expected to provide a reliable reference for further expansion of small-scale experimental operations to industrial production.

HRCT1, negatively regulated by miR-124-3p, promotes tumor metastasis and the growth of gastric cancer by activating the ERBB2-MAPK pathway.

BACKGROUND: Gastric cancer is the fourth leading cause of cancer-related deaths worldwide. And patient outcomes are poor due to tumor relapse and metastasis. To develop new therapeutic strategies, it is of great importance to explore the mechanism underlying the progression of gastric cancer. METHODS: Primary gastric cancer samples with lymph node metastases (LNM) and without LNM were subjected to mRNA microarray assay. The differentially expressed genes were confirmed by RT-qPCR. HRCT1 protein expression was further detected using an immunohistochemistry (IHC) assay. In vitro and in vivo assays were performed to investigate the role of HRCT1 in tumor invasion, metastasis, and proliferation. The expressions of the downstream target genes of HRCT1 were detected by microarray, RT-qPCR and Western blot assays. Dual-luciferase reporter and Western blot assays were carried out to identify miRNAs target to HRCT1. RESULTS: HRCT1 was upregulated in gastric cancer, and high expression of HRCT1 was associated with poor overall survival (OS) and disease-free survival (DFS). Moreover, HRCT1protein expression was an independent predictor for poor OS and DFS. HRCT1 could promote gastric cancer cells' migration, invasion, and proliferation in vitro as well as tumor metastasis and growth in vivo. Notably, our data showed that HRCT1 promoted gastric cancer progression by activating the ERBB2-MAPK signaling pathway. At least partially, the expression of HRCT1 could be negatively regulated by miR-124-3p. CONCLUSIONS: The upregulated expression of HRCT1 predicts poor survival for patients with gastric cancer. HRCT1 promotes tumor progression by activating the ERBB2-MAPK pathway. HRCT1, negatively regulated by miR-124-3p, may be a potential therapeutic target for patients with gastric cancer.

E2F1-initiated transcription of PRSS22 promotes breast cancer metastasis by cleaving ANXA1 and activating FPR2/ERK signaling pathway.

Breast cancer (BC) is the most common malignant tumor in women worldwide. Metastasis is the main cause of BC-related death. The specific mechanism underlying BC metastasis remains obscure. Recently, PRSS22 was discovered to be involved in tumor development, however, its detailed biological function and regulatory mechanism in BC are unclear. Here, we characterized that PRSS22 expression is upregulated in BC tissues compared with non-tumorous breast tissues. Dual luciferase assays, bioinformatics analyses and chromatin immunoprecipitation (ChIP) assays indicated that transcription factor E2F1 directly binds to the PRSS22 promoter region and activates its transcription. Functionally, upregulation of PRSS22 promoted invasion and metastasis of BC cells in vitro and in vivo, whereas knockdown of PRSS22 inhibited its function. Mechanistically, the combination of PRSS22 and ANXA1 protein in BC cells was first screened by protein mass spectrometry analysis, and then confirmed by co-immunoprecipitation (Co-IP) and western blot assays. Co-overexpression of PRSS22 and ANXA1 could promote BC cell migration and invasion. We further demonstrated that PRSS22 promotes the cleavage of ANXA1 and in turn generates an N-terminal peptide, which initiates the FPR2/ERK signaling axis to increase BC aggressiveness.

A signal on-off fluorescence sensor based on the self-assembly DNA tetrahedron for simultaneous detection of ochratoxin A and aflatoxin B1.

Highly rigid and versatile functionality of DNA tetrahedron nanostructures is often used in biosensing systems as a potential detection technique. In this work, a signal on-off fluorescence sensor based on the self-assembly DNA tetrahedron was developed for the rapid simultaneous detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1). The fluorophore labeled DNA tetrahedron as probe was successfully synthesized via a simple denaturing annealing, the distance between fluorophore and quencher was regulated according to the change of hairpin structure on the tetrahedron. The fluorescence intensity of Cy3 decreased significantly in the presence of OTA, while the fluorescence intensity of Cy5 kept almost unchanged. And the fluorescence intensity of Cy5 decreased significantly in the presence of AFB1, while the fluorescence intensity of Cy3 kept almost unchanged. In the present of OTA and AFB1, the fluorescence intensity of Cy3 and Cy5 showed decreased significantly simultaneously, indicating the fluorescence sensor can be applied to simultaneous detect OTA and AFB1. Hence, the quantitative analysis of OTA and AFB1 was performed indirectly by the fluorescence intensity changes. The limits of detection (LOD) are as low as 0.005 ng/mL for OTA and 0.01 ng/mL for AFB1. In addition, the novel DNA tetrahedron-based fluorescence sensor possessed a universal applicability, which could be well applied in corn and wine.

Low Glucose-Induced Overexpression of HOXC-AS3 Promotes Metabolic Reprogramming of Breast Cancer.

Breast cancer is the most common malignancy in women worldwide. However, the mechanisms underlying breast cancer energy metabolism and progression remain obscure. Cancer cells rapidly adapt to microenvironments with fluctuating nutrient levels. Here, we characterized a long noncoding RNA (lncRNA), HOXC-AS3, which is activated upon glucose deprivation to trigger a nutrient-stress response and a switch in glucose metabolism. Upregulation of HOXC-AS3 in breast cancer was identified by in published microarray and RNA-sequencing datasets, and then confirmed by qRT-PCR in fresh breast cancer tissues. Glucose deprivation induced HOXC-AS3 overexpression in a dose- and time-dependent manner in breast cancer cells. Gain- and loss-of-function experiments in vitro and in vivo showed that HOXC-AS3 triggers energy metabolism reprogramming. ChIRP-mass spectrometry and unique molecular identifier RNA immunoprecipitation and high-throughput sequencing (UMI RIP-seq) identified binding motifs of HOXC-AS3 with SIRT6. HOXC-AS3 selectively antagonized SIRT6-mediated H3K9ac deacetylation of glycolysis-related genes. Moreover, HOXC-AS3 binding to SIRT6 prevented contact inhibition of HIF1α, leading to reprogramming of metabolic pathways. In addition, HOXC-AS3, SP1, and miR-1224-5p formed a positive feedback loop to maintain cancer-promoting signals. Furthermore, administration of anti-HOXC-AS3-motif-RNAs effectively blocked the function of HOXC-AS3, ultimately suppressing breast cancer progression. These results reveal a critical role for HOXC-AS3 in regulating the metabolic reprogramming of breast cancer cells under metabolic stress. Use of an anti-HOXC-AS3-motif RNA mixture may be a promising strategy to suppress breast cancer progression. SIGNIFICANCE: HOXC-AS3 is a low glucose-activated long noncoding RNA that triggers metabolic reprogramming in breast cancer cells to adapt to nutrient stress, identifying HOXC-AS3 as a potential therapeutic target for breast cancer treatment.

Long noncoding RNA lnc-LEMGC combines with DNA-PKcs to suppress gastric cancer metastasis.

Long non-coding RNAs (lncRNAs) play important roles in cancer development and progression; however, their contributions to gastric cancer metastasis remain largely unknown. By lncRNA microarray screening, our study showed that 453 lncRNAs are dysregulated in gastric cancer tissues with or without lymph node metastasis, of which lnc-LEMGC ranks as one of the most significantly downregulated lncRNAs. Lnc-LEMGC inhibited cell migration and invasion both in vitro and in vivo, by combining with protein DNA-PKcs. Importantly, nucleotides 1300-1800 of lnc-LEMGC prevented DNA-PKcs phosphorylation of serine 2056 and partially abrogated the effects of downstream effectors, ErbB1, SRC and protein tyrosine kinase 2 (FAK), in the epidermal growth factor receptor (EGFR) pathway. The results of this study extend our knowledge of lncRNA's molecular mechanisms, in which lnc-LEMGC functions by directly suppressing the phosphorylation of its combined protein DNA-PKcs and inactivating the DNA-PKcs downstream EGFR signaling.

lncRNA THAP7-AS1, transcriptionally activated by SP1 and post-transcriptionally stabilized by METTL3-mediated m6A modification, exerts oncogenic properties by improving CUL4B entry into the nucleus.

Long noncoding RNAs (lncRNAs) are dysregulated in different cancer types, and thus have emerged as important regulators of the initiation and progression of human cancers. However, the biological functions and the underlying mechanisms responsible for their functions in gastric cancer (GC) remain poorly understood. Here, by lncRNA microarray, we identified 1414 differentially expressed lncRNAs, among which THAP7-AS1 was significantly upregulated in GC tissues compared with non-tumorous gastric tissues. High expression of THAP7-AS1 was correlated with positive lymph node metastasis and poorer prognosis. SP1, a transcription factor, could bind directly to the THAP7-AS1 promoter region and activate its transcription. Moreover, the m6A modification of THAP7-AS1 by METTL3 enhanced its expression depending on the "reader" protein IGF2BP1-dependent pathway. THAP7-AS1 promoted GC cell progression. Mechanistically, THAP7-AS1 interacted with the 1-50 Amino Acid Region (nuclear localization signal) of CUL4B through its 1-442 nt Sequence, and it promoted interaction between nuclear localization signal (NLS) and importin α1, and improved the CUL4B protein entry into the nucleus, repressing miR-22-3p and miR-320a expression by CUL4B-catalyzed H2AK119ub1 and the EZH2-mediated H3K27me3, subsequently activating PI3K/AKT signaling pathway to promote GC progression. Moreover, LV-sh-THAP7-AS1 treatment could suppress GC growth, invasion and metastasis, indicating that THAP7-AS1 may act as a promising molecular target for GC therapies. Taken together, our results show that THAP7-AS1, transcriptionally activated by SP1 and then modified by METTL3-mediated m6A, exerts oncogenic functions, by promoting interaction between NLS and importin α1 and then improving the CUL4B protein entry into the nucleus to repress the transcription of miR-22-3p and miR-320a.

Aberrant promoter hypermethylation inhibits RGMA expression and contributes to tumor progression in breast cancer.

Breast cancer (BC) is the most common cancer in women worldwide, and the exploration of aberrantly expressed genes might clarify tumorigenesis and help uncover new therapeutic strategies for BC. Although RGMA was recently recognized as a tumor suppressor gene, its detailed biological function and regulation in BC remain unclear. Herein, we found that RGMA was downregulated in BC tissues compared with non-tumorous breast tissues, particularly in metastatic BC samples, and that patients with low RGMA expression manifested a poorer prognosis. Furthermore, DNMT1 and DNMT3A were found to be recruited to the RGMA promoter and induced aberrant hypermethylation, resulting in downregulation of RGMA expression in BC. In contrast, RGMA overexpression suppressed BC cell proliferation and colony-formation capabilities and increased BC cell apoptosis. Furthermore, RGMA knockdown accelerated BC cell proliferation and suppressed cellular apoptosis in vitro and in vivo. Reversal of RGMA promoter methylation with 5-Aza-CdR restored RGMA expression and blocked tumor growth. Overall, DNMT1- and DNMT3A-mediated RGMA promoter hypermethylation led to downregulation of RGMA expression, and low RGMA expression contributed to BC growth via activation of the FAK/Src/PI3K/AKT-signaling pathway. Our data thus suggested that RGMA might be a promising therapeutic target in BC.

ELK1-induced up-regulation of KIF26B promotes cell cycle progression in breast cancer.

KIF26B is a member of the kinesin superfamily that is up-regulated in various tumors, including breast cancer (BC), which can promote tumor progression. This study aimed to investigate the potential function of KIF26B in BC, and the underlying mechanisms, focusing mainly on cell proliferation. KIF26B expression was examined in BC tissue samples obtained from 99 patients. Then, we performed MTS, EdU and flow cytometry assays to detect cell proliferation, and western blotting to measure the expression of cell cycle-related proteins in MDA-MB-231 and MDA-MB-468 cells following KIF26B knockdown. Promoter analysis was used to study the upstream regulatory mechanism of KIF26B. KIF26B was upregulated in BC tissues. High expression of KIF26B was associated with clinicopathological parameters, such as positive lymph node metastasis, higher tumor grade, and higher proliferative index in BC. Furthermore, knockdown of KIF26B expression inhibited MDA-MB-231 and MDA-MB-468 cell proliferation, arresting cells in the G1 phase of the cell cycle in vitro. Similarly, KIF26B silencing decreased the expression levels of Wnt, ß-catenin, and cell cycle-related proteins such as c-Myc, cyclin D1, and cyclin-dependent kinase 4, while increasing the expression of p27. Moreover, ELK1 could bind to the core promoter region of KIF26B and activate its transcription. KIF26B acts as an oncogene in BC by regulating multiple proteins involved in the cell cycle. ELK1 activates KIF26B transcription.

MiR-19a/miR-96-mediated low expression of KIF26A suppresses metastasis by regulating FAK pathway in gastric cancer.

Gastric cancer (GC) is one of the most common malignant neoplasms. Invasion and metastasis are the main causes of GC-related deaths. Recently, kinesins were discovered to be involved in tumor development. The aim of this study was to elucidate the roles of kinesin superfamily protein 26A (KIF26A) in GC and its underlying molecular mechanism in regulating tumor invasion and metastasis. Using real-time quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC), we showed that KIF26A expression was lower in GC tissues without lymph node metastasis (LNM) than in nontumorous gastric mucosa, and even lower in GC tissues with LNM than in GC tissues without LNM. Functional experiments showed that KIF26A inhibited migration and invasion of GC cells. We further identified focal-adhesion kinase (FAK), phosphatidylinositol 3-kinase regulatory subunit alpha (PI3KR1), VAV3, Rac1 and p21-activated kinase 2, and ß-PAK (PAK3) as downstream effectors of KIF26A in the focal-adhesion pathway, and we found that KIF26A could regulate FAK mRNA expression through inhibiting c-MYC by MAPK pathway. c-MYC could bind to the promoter of FAK and activate FAK transcription. Moreover, we found that KIF26A-mediated inactivation of the focal-adhesion pathway could reduce the occurrence of the epithelial-to-mesenchymal transition (EMT) by increasing expression of E-cadherin and reducing that of Snail. Luciferase assays and Western blotting revealed that miR-19a and miR-96 negatively regulate KIF26A. Finally, we found that decreased expression of KIF26A has been positively correlated with histological differentiation, Lauren classification, LNM, distal metastasis, and clinical stage, as well as poor survival in patients with GC. These data indicate that KIF26A could inhibit GC migration and invasion by regulating the focal-adhesion pathway and repressing the occurrence of EMT.

Correction: SP1-activated long noncoding RNA lncRNA GCMA functions as a competing endogenous RNA to promote tumor metastasis by sponging miR-124 and miR-34a in gastric cancer.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

E2F1-activated SPIN1 promotes tumor growth via a MDM2-p21-E2F1 feedback loop in gastric cancer.

Gastric cancer (GC) is one of the most common cancers around the world. Searching for specific gene expression changes during the development of GC could help identify potential therapy targets. We previously showed that the histone code reader SPIN1 may act as an oncogene in breast cancer. At present, the biological function and regulation of SPIN1 in GC remain unclear. Here, we demonstrate that SPIN1 is upregulated in GC tissues, compared with nontumorous gastric tissues. Increased expression of SPIN1 is closely associated with poor prognosis for patients with GC. Increased SPIN1 expression enhances GC cell proliferation, migration, and invasion and promotes cell cycle progression. Mechanically, SPIN1 sustains GC cell proliferation via activation of the MDM2-p21-E2F1 signaling pathway by binding to H3K4me3 of the MDM2 promoter region. Interestingly, E2F1 could directly bind to the SPIN1 promoter and activate its transcription, thus forming a positive feedback loop. Our data suggest that SPIN1 plays an important role in the development of GC and could be used as a promising prognostic biomarker and therapeutic target for GC.

TIPRL, a Novel Tumor Suppressor, Suppresses Cell Migration, and Invasion Through Regulating AMPK/mTOR Signaling Pathway in Gastric Cancer.

Invasion and metastasis of gastric cancer after curative resection remain the most common lethal outcomes. However, our current understanding of the molecular mechanism underlying gastric cancer metastasis is far from complete. Herein, we identified TOR signaling pathway regulator (TIPRL) as a novel metastasis suppressor in gastric cancer through genome-wide gene expression profiling analysis using mRNA microarray. Decreased TIPRL expression was detected in clinical gastric cancer specimens, and low TIPRL expression was correlated with more-advanced TNM stage, distant metastasis, and poor clinical outcome. Moreover, TIPRL was identified as a direct target of miR-216a-5p and miR-383-5p. Functional study revealed that re-expression of TIPRL in gastric cancer cell lines suppressed their migratory and invasive capacities, whereas inverse effects were observed in TIPRL-deficient models. Mechanistically, TIPRL downstream effectors and signaling pathways were investigated using mRNA microarray. Gene expression profiling revealed that TIPRL could not modulate the downstream genes at transcriptional levels, thereby implying that the regulation might occur at the post-transcriptional levels. We further demonstrated that TIPRL induced phosphorylation/activation of AMPK, which in turn attenuated phosphorylation of mTOR, p70S6K, and 4E-BP1, thereby leading to inactivation of mTOR signaling and subsequent suppression of cell migration/invasion in gastric cancer. Taken together, TIPRL acts as a novel metastasis suppressor in gastric cancer, at least in part, through regulating AMPK/mTOR signaling, likely representing a promising target for new therapies in gastric cancer.

Long Non-coding RNA AK025387 Promotes Cell Migration and Invasion of Gastric Cancer.

Gastric cancer is one of the most common cancers in the world, and long non-coding RNAs (lncRNAs) play a crucial role in proliferation, metastasis, and invasion of gastric cancer. However, there are very few researches focusing on the effects of lncRNAs on metastatic gastric cancer. In this research, we identify one kind of lncRNA, called AK025387, which is highly expressed in metastatic gastric cancer samples compared with non-metastatic gastric cancer samples. The expression of AK025387 is significantly positively correlated with lymph node metastasis. The in situ hybridization demonstrates that AK025387 is located in both nucleus and cytoplasm, but mostly in cytoplasm. AK025387 promotes gastric cancer cells migratory and invasive ability, but it inhibits apoptosis in vitro. Furthermore, AK025387 regulates Raf-1, mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK), and extracellular signal-regulated kinase (ERK) and is involved in mitogen-activated protein kinase (MAPK) signaling pathway to perform its biological functions. We conclude that AK025387 is highly expressed in metastatic gastric cancer, and its biological functions suggest the potential of AK025387 to be a biomarker of metastatic gastric cancer.

SP1-activated long noncoding RNA lncRNA GCMA functions as a competing endogenous RNA to promote tumor metastasis by sponging miR-124 and miR-34a in gastric cancer.

Long noncoding RNAs (lncRNAs) were demonstrated to play important roles in gene regulation and cancer progression. However, the functional roles of lncRNAs and the detailed mechanisms underlying gastric cancer (GC) progression remain largely unclear. Here, we identified a novel cancer-related lncRNA, termed lncRNA GCMA (Gastric Cancer metastasis-associated lncRNA), which was upregulated in GC tissues with lymph node metastasis (LNM) compared with tissues without LNM. High expression of GCMA was significantly associated with poor prognosis of patients with GC. Luciferase assays, bioinformatics analyses and chromatin immunoprecipitation (ChIP) assays indicated that SP1 transcription factor directly bound to the GCMA promoter region and activated its transcription. Functionally, upregulation of GCMA dramatically promoted GC cells proliferation, migration and invasion in vitro, whereas knockdown of GCMA elicited the opposite function. Consistently, stable knockdown of GCMA inhibited tumor proliferation, invasion and metastasis in vivo. Mechanistically, by using bioinformatics analyses, RNA binding protein immunoprecipitation (RIP) assays, luciferase assays and western-blot assays, GCMA was demonstrated to function as a competing endogenous RNA (ceRNA) via competitively absorbing miR-124 and miR-34a to upregulate slug and snail, thereby induced epithelial-mesenchymal transition (EMT) and GC cell metastasis in vitro and in vivo. Collectively, these results demonstrate that GCMA functions as an oncogenic lncRNA that may serve as a potential prognostic biomarker for GC and shed new lights on targeted therapy of GC in the future.