F-box protein FBXL2 inhibits gastric cancer proliferation by ubiquitin-mediated degradation of forkhead box M1

Role of F-box proteins in human upper gastrointestinal tumors

Protein ubiquitination and degradation is an essential physiological process in almost all organisms. As the key participants in this process, the E3 ubiquitin ligases have been widely studied and recognized. F-box proteins, a crucial component of E3 ubiquitin ligases that regulates diverse biological functions, including cell differentiation, proliferation, migration, and apoptosis by facilitating the degradation of substrate proteins. Currently, there is an increasing focus on studying the role of F-box proteins in cancer. In this review, we present a comprehensive overview of the significant contributions of F-box proteins to the development of upper gastrointestinal tumors, highlighting their dual roles as both carcinogens and tumor suppressors. We delve into the molecular mechanisms underlying the involvement of F-box proteins in upper gastrointestinal tumors, exploring their interactions with specific substrates and their cross-talks with other key signaling pathways. Furthermore, we discuss the implications of F-box proteins in radiotherapy resistance in the upper gastrointestinal tract, emphasizing their potential as clinical therapeutic and prognostic targets. Overall, this review provides an up-to-date understanding of the intricate involvement of F-box proteins in human upper gastrointestinal tumors, offering valuable insights for the identification of prognostic markers and the development of targeted therapeutic strategies.

RNF112-mediated FOXM1 ubiquitination suppresses the proliferation and invasion of gastric cancer

Forkhead box M1 (FOXM1) plays a critical role in development physiologically and tumorigenesis pathologically. However, insufficient efforts have been dedicated to exploring the regulation, in particular the degradation of FOXM1. Here, the ON-TARGETplus siRNA library targeting E3 ligases was used to screen potential candidates to repress FOXM1. Of note, mechanism study revealed that RNF112 directly ubiquitinates FOXM1 in gastric cancer, resulting in a decreased FOXM1 transcriptional network and suppressing the proliferation and invasion of gastric cancer. Interestingly, the well-established small-molecule compound RCM-1 significantly enhanced the interaction between RNF112 and FOXM1, which further promoted FOXM1 ubiquitination and subsequently exerted promising anticancer effects in vitro and in vivo. Altogether, we demonstrate that RNF112 suppresses gastric cancer progression by ubiquitinating FOXM1 and highlight the RNF112/FOXM1 axis serves as both prognosis biomarker and therapeutic target in gastric cancer.

HMGA1 and FOXM1 Cooperate to Promote G2/M Cell Cycle Progression in Cancer Cells

HMGA1 is a chromatin-binding protein and performs its biological function by remodeling chromatin structure or recruiting other transcription factors. However, the role of abnormally high level of HMGA1 in cancer cells and its regulatory mechanism still require further investigation. In this study, we performed a prognostic analysis and showed that high level of either HMGA1 or FOXM1 was associated with poor prognosis in various cancers based on the TCGA database. Furthermore, the expression pattern of HMGA1 and FOXM1 showed a significant strong positive correlation in most type of cancers, especially lung adenocarcinoma, pancreatic cancer and liver cancer. Further analysis of the biological effects of their high correlation in cancers suggested that cell cycle was the most significant related pathway commonly regulated by HMGA1 and FOXM1. After knockdown of HMGA1 and FOXM1 by specific siRNAs, an obvious increased G2/M phase was observed in the siHMGA1 and siFOXM1 groups compared to the siNC group. The expression levels of key G2/M phase regulatory genes PLK1 and CCNB1 were significantly downregulated. Importantly, HMGA1 and FOXM1 were identified to form a protein complex and co-located in the nucleus based on co-immunoprecipitation and immunofluorescence staining, respectively. Thus, our results provide the basic evidence that HMGA1 and FOXM1 cooperatively accelerate cell cycle progression by up-regulating PLK1 and CCNB1 to promote cancer cell proliferation.

UPS: Opportunities and challenges for gastric cancer treatment

Gastric cancer remains the fourth most frequently diagnosed malignancy and the fifth leading cause of cancer-related mortality worldwide owning to the lack of efficient drugs and targets for therapy. Accumulating evidence indicates that UPS, which consists of E1, E2, and E3 enzymes and proteasome, plays an important role in the GC tumorigenesis. The imbalance of UPS impairs the protein homeostasis network during development of GC. Therefore, modulating these enzymes and proteasome may be a promising strategy for GC target therapy. Besides, PROTAC, a strategy using UPS to degrade the target protein, is an emerging tool for drug development. Thus far, more and more PROTAC drugs enter clinical trials for cancer therapy. Here, we will analyze the abnormal expression enzymes in UPS and summarize the E3 enzymes which can be developed in PROTAC so that it can contribute to the development of UPS modulator and PROTAC technology for GC therapy.

Targeting CSC-related transcription factors by E3 ubiquitin ligases for cancer therapy

Evidence has revealed that transcription factors play essential roles in regulation of multiple cellular processes, including cell proliferation, metastasis, EMT, cancer stem cells and chemoresistance. Dysregulated expression levels of transcription factors contribute to tumorigenesis and malignant progression. The expression of transcription factors is tightly governed by several signaling pathways, noncoding RNAs and E3 ubiquitin ligases. Cancer stem cells (CSCs) have been validated in regulation of tumor metastasis, reoccurrence and chemoresistance in human cancer. Transcription factors have been verified to participate in regulation of CSC formation, including Oct4, SOX2, KLF4, c-Myc, Nanog, GATA, SALL4, Bmi-1, OLIG2, POU3F2 and FOX proteins. In this review article, we will describe the critical role of CSC-related transcription factors. We will further discuss which E3 ligases regulate the degradation of these CSC-related transcription factors and their underlying mechanisms. We also mentioned the functions and mechanisms of EMT-associated transcription factors such as ZEB1, ZEB2, Snail, Slug, Twist1 and Twist2. Furthermore, we highlight the therapeutic potential via targeting E3 ubiquitin ligases for modulation of these transcription factors.

Identification, Classification and Characterization Analysis of FBXL Gene in Cotton

F-box/LR (FBXL), Leucine-rich repeats in F-box proteins, belongs to the Skp1-Cullin1-F-box protein (SCF) E3 ligase family. FBXL genes play important roles in plant growth, such as plant hormones, responses to environmental stress, and floral organ development. Here, a total of 518 FBXL genes were identified and analyzed in six plant species. Phylogenetic analysis showed that AtFBXLs, VvFBXLs, and GrFBXLs were clustered into three subfamilies (Ⅰ-Ⅲ). Based on the composition of the F-box domain and carboxyl-terminal amino acid sequence, FBXL proteins were classified into three types (Type-A/-B/-C). Whole-genome duplication (WGD) along with tandem duplications and segmental contributed to the expansion of this gene family. The result indicates that four cotton species are also divided into three subfamilies. FBXLs in cotton were classified into three clades by phylogenetic and structural analyses. Furthermore, expression analyses indicated that the expression patterns of GhFBXLs in different cotton tissues were different. The highly expressed of GH_A07G2363 in 5-8 mm anthers, indicates that this gene might play a role in the reproductive process, providing candidate genes for future studies on cotton fertility materials. This study provides an original functional opinion and a useful interpretation of the FBXL protein family in cotton.

c-FLIP promotes drug resistance in non-small-cell lung cancer cells via upregulating FoxM1 expression

The forkhead box M1 (FoxM1) protein, a transcription factor, plays critical roles in regulating tumor growth and drug resistance, while cellular FLICE-inhibitory protein (c-FLIP), an anti-apoptotic regulator, is involved in the ubiquitin-proteasome pathway. In this study, we investigated the effects of c-FLIP on the expression and ubiquitination levels of FoxM1 along with drug susceptibility in non-small-cell lung cancer (NSCLC) cells. We first showed that the expression levels of FoxM1 and c-FLIP were increased and positively correlated (R2 = 0.1106, P < 0.0001) in 90 NSCLC samples. The survival data from prognostic analysis demonstrated that high expression of c-FLIP and/or FoxM1 was related to poor prognosis in NSCLC patients and that the combination of FoxM1 and c-FLIP could be a more precise prognostic biomarker than either alone. Then, we explored the functions of c-FLIP/FoxM1 in drug resistance in NSCLC cell lines and a xenograft mouse model in vivo. We showed that c-FLIP stabilized FoxM1 by inhibiting its ubiquitination, thus upregulated the expression of FoxM1 at post-transcriptional level. In addition, a positive feedback loop composed of FoxM1, β-catenin and p65 also participated in c-FLIP-FoxM1 axis. We revealed that c-FLIP promoted the resistance of NSCLC cells to thiostrepton and osimertinib by upregulating FoxM1. Taken together, these results reveal a new mechanism by which c-FLIP regulates FoxM1 and the function of this interaction in the development of thiostrepton and osimertinib resistance. This study provides experimental evidence for the potential therapeutic benefit of targeting the c-FLIP-FoxM1 axis for lung cancer treatment.

USP28 facilitates pancreatic cancer progression through activation of Wnt/β-catenin pathway via stabilising FOXM1

Ubiquitination is an important post-translational modification that can be reversed by a family of enzymes called deubiquitinating enzymes (DUBs). Ubiquitin-specific protease 28 (USP28), a member of the DUBs family, functions as a potential tumour promoter in various cancers. However, the biological function and clinical significance of USP28 in pancreatic cancer (PC) are still unclear. Here, we showed that PC tumours had higher USP28 expression compared with that of normal pancreatic tissues, and high USP28 level was significantly correlated with malignant phenotype and shorter survival in patients with PC. Overexpression of USP28 accelerated PC cell growth, whereas USP28 knockdown impaired PC cell growth both in vitro and in vivo. Further, we found that USP28 promoted PC cell growth by facilitating cell cycle progression and inhibiting apoptosis. Mechanistically, USP28 deubiquitinated and stabilised FOXM1, a critical mediator of Wnt/β-catenin signalling. USP28-mediated stabilisation of FOXM1 significantly promoted nucleus β-catenin trans-activation, which in turn led to the activation of the Wnt/β-catenin pathway. Finally, restoration of FOXM1 expression abolished the anti-tumour effects of USP28-silencing. Thus, USP28 contributes to PC pathogenesis through enhancing the FOXM1-mediated Wnt/β-catenin signalling, and could be a potential diagnostic and therapeutic target for PC cases.

FOSL1 promotes tumorigenesis in colorectal carcinoma by mediating the FBXL2/Wnt/β-catenin axis via Smurf1

Colorectal carcinoma (CC), one of the most prevalent digestive cancers with high mortality and morbidity globally, still lacks powerful therapies to improve the prognosis. Here, we established that the expression of fos-like antigen-1 (Fosl1) was elevated in CC tissues versus adjacent tissues. Importantly, high Fosl1 expression was related to dismal prognosis among CC patients. Functional assays displayed that Fosl1 increased the viability, epithelial-to-mesenchymal transition (EMT), migration and invasion of CC cells. Additionally, a xenograft assay showed that silencing of Fosl1 in CC cells retarded lung, liver and kidney metastases in vivo. Further investigation demonstrated that Fosl1 was involved in malignant aggressiveness of CC cells by binding to smad ubiquitination regulatory factor 1 (Smurf1). Mechanistically, Smurf1-induced F-Box and leucine rich repeat protein 2 (FBXL2) ubiquitination resulted in its degradation, while FBXL2 disrupted the activation of the Wnt/β-catenin signaling. In summary, Fosl1 plays a pro-metastatic and carcinogenetic role in CC, and we provided forceful evidence that Fosl1 inhibition might act as a prognostic and therapeutic option in CC.

The FBXL family of F-box proteins: variations on a theme

The ubiquitin–proteasome system (UPS) is responsible for the rapid targeting of proteins for degradation at 26S proteasomes and requires the orchestrated action of E1, E2 and E3 enzymes in a well-defined cascade. F-box proteins (FBPs) are substrate-recruiting subunits of Skp1-cullin1-FBP (SCF)-type E3 ubiquitin ligases that determine which proteins are ubiquitinated. To date, around 70 FBPs have been identified in humans and can be subdivided into distinct families, based on the protein-recruiting domains they possess. The FBXL subfamily is defined by the presence of multiple leucine-rich repeat (LRR) protein-binding domains. But how the 22 FBPs of the FBXL family achieve their individual specificities, despite having highly similar structural domains to recruit their substrates, is not clear. Here, we review and explore the FBXL family members in detail highlighting their structural and functional similarities and differences and how they engage their substrates through their LRRs to adopt unique interactomes.

The role of Anaphase Promoting Complex activation, inhibition and substrates in cancer development and progression

The Anaphase Promoting Complex (APC), a multi-subunit ubiquitin ligase, facilitates mitotic and G1 progression, and is now recognized to play a role in maintaining genomic stability. Many APC substrates have been observed overexpressed in multiple cancer types, such as CDC20, the Aurora A and B kinases, and Forkhead box M1 (FOXM1), suggesting APC activity is important for cell health. We performed BioGRID analyses of the APC coactivators CDC20 and CDH1, which revealed that at least 69 proteins serve as APC substrates, with 60 of them identified as playing a role in tumor promotion and 9 involved in tumor suppression. While these substrates and their association with malignancies have been studied in isolation, the possibility exists that generalized APC dysfunction could result in the inappropriate stabilization of multiple APC targets, thereby changing tumor behavior and treatment responsiveness. It is also possible that the APC itself plays a crucial role in tumorigenesis through its regulation of mitotic progression. In this review the connections between APC activity and dysregulation will be discussed with regards to cell cycle dysfunction and chromosome instability in cancer, along with the individual roles that the accumulation of various APC substrates may play in cancer progression.

Functional roles of E3 ubiquitin ligases in gastric cancer

To date, >650 E3 ubiquitin ligases have been described in humans, including >600 really interesting new genes (RINGs), 28 homologous to E6-associated protein C-terminus (HECTs) and several RING-in-between-RINGs. They are considered key regulators and therapeutic targets of many types of human cancers, including gastric cancer (GC). Among them, some RING and HECT E3 ligases are closely related to the proliferation, infiltration and prognosis of GC. During the past few years, abnormal expressions and functions of many E3 ligases have been identified in GC. However, the functional roles of E3 ligases in GC have not been fully elucidated. The present article focuses on the functional roles of E3 ligases related to the proteasome in GC. In this comprehensive review, the latest research progress on E3 ligases involved in GC and elaborate their structure, classification, functional roles and therapeutic value in GC was summarized. Finally, 30 E3 ligases that serve essential roles in regulating the development of GC were described. Some of these ligases may serve as oncogenes or tumor suppressors in GC, whereas the pathological mechanism of others needs further study; for example, constitutive photomorphogenic 1. In conclusion, the present review demonstrated that E3 ligases are crucial tumor regulatory factors and potential therapeutic targets in GC. Therefore, more studies should focus on the therapeutic targeting of E3 ligases in GC.

Molecular characterization and expression analysis of pitaya (Hylocereus polyrhizus) HpLRR genes in response to Neoscytalidium dimidiatum infection

BACKGROUND

Canker disease caused by Neoscytalidium dimidiatum is a devastating disease resulting in a major loss to the pitaya industry. However, resistance proteins in plants play crucial roles to against pathogen infection. Among resistance proteins, the leucine-rich repeat (LRR) protein is a major family that plays crucial roles in plant growth, development, and biotic and abiotic stress responses, especially in disease defense.

RESULTS

In the present study, a transcriptomics analysis identified a total of 272 LRR genes, 233 of which had coding sequences (CDSs), in the plant pitaya (Hylocereus polyrhizus) in response to fungal Neoscytalidium dimidiatum infection. These genes were divided into various subgroups based on specific domains and phylogenetic analysis. Molecular characterization, functional annotation of proteins, and an expression analysis of the LRR genes were conducted. Additionally, four LRR genes (CL445.Contig4_All, Unigene28_All, CL28.Contig2_All, and Unigene2712_All, which were selected because they had the four longest CDSs were further assessed using quantitative reverse transcription PCR (qRT-PCR) at different fungal infection stages in different pitaya species (Hylocereus polyrhizus and Hylocereus undatus), in different pitaya tissues, and after treatment with salicylic acid (SA), methyl jasmonate (MeJA), and abscisic acid (ABA) hormones. The associated protein functions and roles in signaling pathways were identified.

CONCLUSIONS

This study provides a comprehensive overview of the HpLRR family genes at transcriptional level in pitaya in response to N. dimidiatum infection, it will be helpful to understand the molecular mechanism of pitaya canker disease, and lay a strong foundation for further research.

A Cdh1-FoxM1-Apc axis controls muscle development and regeneration

Forkhead box M1 (FoxM1) transcriptional factor has a principal role in regulating cell proliferation, self-renewal, and tumorigenesis. However, whether FoxM1 regulates endogenous muscle development and regeneration remains unclear. Here we found that loss of FoxM1 in muscle satellite cells (SCs) resulted in muscle atrophy and defective muscle regeneration. FoxM1 functioned as a direct transcription activator of adenomatous polyposis coli (Apc), preventing hyperactivation of wnt/β-catenin signaling during muscle regeneration. FoxM1 overexpression in SCs promoted myogenesis but impaired muscle regeneration as a result of spontaneous activation and exhaustion of SCs by transcriptional regulation of Cyclin B1 (Ccnb1). The E3 ubiquitin ligase Cdh1 (also termed Fzr1) was required for FoxM1 ubiquitylation and subsequent degradation. Loss of Cdh1 promoted quiescent SCs to enter into the cell cycle and the SC pool was depleted by serial muscle injuries. Haploinsufficiency of FoxM1 ameliorated muscle regeneration of Cdh1 knock-out mice. These data demonstrate that the Cdh1–FoxM1–Apc axis functions as a key regulator of muscle development and regeneration.

F-box proteins and cancer: an update from functional and regulatory mechanism to therapeutic clinical prospects

E3 ubiquitin ligases play a critical role in cellular mechanisms and cancer progression. F-box protein is the core component of the SKP1-cullin 1-F-box (SCF)-type E3 ubiquitin ligase and directly binds to substrates by various specific domains. According to the specific domains, F-box proteins are further classified into three sub-families: 1) F-box with leucine rich amino acid repeats (FBXL); 2) F-box with WD 40 amino acid repeats (FBXW); 3) F-box only with uncharacterized domains (FBXO). Here, we summarize the substrates of F-box proteins, discuss the important molecular mechanism and emerging role of F-box proteins especially from the perspective of cancer development and progression. These findings will shed new light on malignant tumor progression mechanisms, and suggest the potential role of F-box proteins as cancer biomarkers and therapeutic targets for future cancer treatment.

O-GlcNAcylation-mediated degradation of FBXL2 stabilizes FOXM1 to induce cancer progression

O-GlcNAcylation is a dynamic and reversible post-translational modification of cytonuclear molecules that regulates cellular signaling. Elevated O-GlcNAcylation is a general property of cancer and plays a critical role in cancer progression. We previously showed that the expression of FOXM1, a critical oncogenic transcription factor widely overexpressed in solid tumors, was elevated in MKN45 cells, a human gastric cancer cell line, by the O-GlcNAcase inhibitor Thiamet G (TMG), which induces augmented O-GlcNAcylation. Here, we identified FBXL2 E3 ubiquitin ligase as a new target of O-GlcNAcylation. Consistent with the results in MKN45 cells, FOXM1 expression was increased, accompanied by its decreased ubiquitination and degradation by TMG in the other gastric cancer cell lines, including NUGC-3 cells. We found that FBXL2 ubiquitinated FOXM1, and the interaction with FBXL2 and ubiquitination of FOXM1 were reduced by TMG in NUGC-3 cells. Interestingly, FBXL2 was also ubiquitinated, which was promoted by TMG in the cells. Moreover, FOXM1 expression and cell proliferation were reduced in FBXL2-induced NUGC-3 cells, and the reductions were attenuated by TMG, indicating that FOXM1 was stabilized by O-GlcNAcylation-mediated degradation of FBXL2 to induce cancer progression. These data suggest that elevated O-GlcNAcylation contributes to cancer progression by suppressing FBXL2-mediated degradation of FOXM1.

Circular RNA SMARCA5 inhibits gastric cancer progression through targeting the miR-346/ FBXL2 axis

Circular RNA (circRNA) SMARCA5 (circSMARCA5) is a cancer-related circRNA that has been observed to be involved in the progression of several types of cancer. However, the role of circSMARCA5 in gastric cancer has not been reported. In the present study, we aimed to explore the function and mechanism of circSMARCA5 in gastric cancer. Our results showed that circSMARCA5 expression was significantly decreased in human gastric cancer tissues and cell lines. Further in vitro investigations demonstrated that overexpression of circSMARCA5 in SGC7901 cells inhibited cell proliferation, migration and invasion. Luciferase reporter assays proved that circSMARCA5 acted as a sponge for miroRNA-346 (miR-346) and regulated the expression of F-Box and leucine rich repeat protein 2 (FBXL2). Furthermore, transfection of miR-346 mimics into cells overexpressing circSMARCA5 blocked the function of circSMARCA5. Finally, we found that knockdown FBXL2 significantly reversed the effects of miR-346 inhibitor on gastric cell proliferation, migration and invasion. Collectively, circSMARCA5 exhibited a tumor suppressor-like activity in gastric cancer via regulating the miR-346/FBXL2 axis.

Circular RNA (circRNA) SMARCA5 (circSMARCA5) is a cancer-related circRNA that has been observed to be involved in the progression of several types of cancer.

EZH2 oncogenic mutations drive epigenetic, transcriptional, and structural changes within chromatin domains

Chromatin is organized into topologically associating domains (TADs) enriched in distinct histone marks. In cancer, gain-of-function mutations in the gene encoding the enhancer of zeste homolog 2 protein (EZH2) lead to a genome-wide increase in histone-3 Lys27 trimethylation (H3K27me3) associated with transcriptional repression. However, the effects of these epigenetic changes on the structure and function of chromatin domains have not been explored. Here, we found a functional interplay between TADs and epigenetic and transcriptional changes mediated by mutated EZH2. Altered EZH2 (p.Tyr646* (EZH2^Y646X)) led to silencing of entire domains, synergistically inactivating multiple tumor suppressors. Intra-TAD gene silencing was coupled with changes of interactions between gene promoter regions. Notably, gene expression and chromatin interactions were restored by pharmacological inhibition of EZH2^Y646X. Our results indicate that EZH2^Y646X alters the topology and function of chromatin domains to promote synergistic oncogenic programs.

Regulation of the master regulator FOXM1 in cancer

FOXM1 (forkhead box protein M1) is a critical proliferation-associated transcription factor that is widely spatiotemporally expressed during the cell cycle. It is closely involved with the processes of cell proliferation, self-renewal, and tumorigenesis. In most human cancers, FOXM1 is overexpressed, and this indicates a poor prognosis for cancer patients. FOXM1 maintains cancer hallmarks by regulating the expression of target genes at the transcriptional level. Due to its potential role as molecular target in cancer therapy, FOXM1 was named the Molecule of the Year in 2010. However, the mechanism of FOXM1 dysregulation remains indistinct. A comprehensive understanding of FOXM1 regulation will provide novel insight for cancer and other diseases in which FOXM1 plays a major role. Here, we summarize the transcriptional regulation, post-transcriptional regulation and post-translational modifications of FOXM1, which will provide extremely important implications for novel strategies targeting FOXM1.

Cancer astrocytes have a more conserved molecular status in long recurrence free survival (RFS) IDH1 wild-type glioblastoma patients: new emerging cancer players

Glioblastoma is a devastating disease that despite all the information gathered so far, its optimal management remains elusive due to the absence of validated targets from clinical studies. A better clarification of the molecular mechanisms is needed. In this study, having access to IDH1 wild-type glioblastoma of patients with exceptionally long recurrence free survival (RFS), we decided to compare their mutational and gene expression profile to groups of IDH1 wild-type glioblastoma of patients with shorter RFS, by using NGS technology. The exome analysis revealed that Long-RFS tumors have a lower mutational rate compared to the other groups. A total of 158 genes were found differentially expressed among the groups, 112 of which distinguished the two RFS extreme groups. Overall, the exome data suggests that shorter RFS tumors could be, chronologically, in a more advanced state in the muli-step tumor process of sequential accumulation of mutations. New players in this kind of cancer emerge from the analysis, confirmed at the RNA/DNA level, identifying, therefore, possible oncodrivers or tumor suppressor genes.

Regulator of G-protein signaling 3 targeted by miR-126 correlates with poor prognosis in gastric cancer patients

The Wnt/β-catenin signaling pathway dominates numerous cellular processes including cell proliferation, differentiation, and epithelial-mesenchymal transition, which play a crucial role in human cancer malignancies. Regulator of G-protein signaling 3 (RGS3) is a pivotal molecule involved in the Wnt/β-catenin signaling pathway, which is worthy of intensive research as a potential target in cancer treatment. In this study, we found that RGS3 is significantly upregulated in gastric cancer (GC) tumor samples compared with normal samples from the analysis of two independent GC mRNA microarray datasets in the NCBI public database. Further immunohistochemistry assay and western-blot experiments confirmed this finding on the basis of the results of our own 102 paired GC specimens and three GC cell lines. We found that a high expression of RGS3 is associated with advanced TNM stages and more aggressive malignant behaviors. In addition, the association of overexpression of RGS3 and poor overall survival and progression-free survival outcomes suggests that RGS3 has the potential to serve as a molecular therapy target for GC. Interestingly, our pathways analysis and the follow-up dual-luciferase reporter assay showed that there is a direct 3'-untranslated region binding site between RGS3 mRNA and microRNA-126, a GC inhibitor. On the basis of all the above evidences, our findings suggest that overexpressed RGS3 regulated by microRNA-126 through the post-transcriptional modulation is associated significantly with a poor prognosis of GC patients.

miRNA-346 promotes proliferation, migration and invasion in liver cancer

Liver cancer primarily accounts for the majority of malignancies of the liver. MicroRNAs (miRNAs) are endogenous non-coding RNAs, which are important in tumorigenesis. Abnormal expression of microRNA-346 (miR-346) has been demonstrated in various types of human cancer, however, its expression and potential molecular mechanism in liver cancer remains to be elucidated. Expression levels of miR-346 in liver cancer cell lines were determined by quantitative polymerase chain reaction. The effect of miR-346 on proliferation was evaluated by an MTT assay; cell migration and invasion were evaluated by Transwell migration and invasion assays and target protein expression was determined by western blotting. The present study observed that miR-346 was upregulated in liver cancer cell lines. miR-346 overexpression promoted cell proliferation, migration and invasion in liver cancer cells and conversely, inhibition of miR-346 resulted in the opposite effects. Furthermore, F-Box and leucine rich repeat protein (FBXL)2 was identified as a direct target of miR-346. miR-346 promoted proliferation, migration and invasion of liver cancer via FBXL2. Overall, these findings demonstrated that miR-346 may act as a potential prognostic marker and therapeutic target against liver cancer in the future.