Metastasis suppressor 1 (MTSS1) demonstrates prognostic value and anti-metastatic properties in breast cancer

MicroRNA as Key Players in Hepatocellular Carcinoma: Insights into Their Role in Metastasis

Liver cancer or hepatocellular carcinoma (HCC) remains the most common cancer in global epidemiology. Both the frequency and fatality of this malignancy have shown an upward trend over recent decades. Liver cancer is a significant concern due to its propensity for both intrahepatic and extrahepatic metastasis. Liver cancer metastasis is a multifaceted process characterized by cell detachment from the bulk tumor, modulation of cellular motility and invasiveness, enhanced proliferation, avoidance of the immune system, and spread either via lymphatic or blood vessels. MicroRNAs (miRNAs) are small non-coding ribonucleic acids (RNAs) playing a crucial function in the intricate mechanisms of tumor metastasis. A number of miRNAs can either increase or reduce metastasis via several mechanisms, such as control of motility, proliferation, attack by the immune system, cancer stem cell properties, altering the microenvironment, and the epithelial-mesenchymal transition (EMT). Besides, two other types of non-coding RNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can competitively bind to endogenous miRNAs. This competition results in the impaired ability of the miRNAs to inhibit the expression of the specific messenger RNAs (mRNAs) that are targeted. Increasing evidence has shown that the regulatory axis comprising circRNA/lncRNA-miRNA-mRNA is correlated with the regulation of HCC metastasis. This review seeks to present a thorough summary of recent research on miRNAs in HCC, and their roles in the cellular processes of EMT, invasion and migration, as well as the metastasis of malignant cells. Finally, we discuss the function of the lncRNA/circRNA-miRNA-mRNA network as a crucial modulator of carcinogenesis and the regulation of signaling pathways or genes that are relevant to the metastasis of HCC. These findings have the potential to offer valuable insight into the discovery of novel therapeutic approaches for management of liver cancer metastasis.

MTSS1: beyond the integration of actin and membrane dynamics

MTSS1 is a ubiquitously expressed intracellular protein known mainly for its involvement in basic cellular processes, such as the regulation of actin organization and membrane architecture. MTSS1 has attracted much attention for its role as a tumor suppressor, being absent or expressed at reduced levels in advanced and metastasizing cancers. Occasionally, MTSS1 is, instead, upregulated in metastasis and, in some cases, even in primary tumors. In addition to these well-established functions of MTSS1 linked to its I-BAR- and WH2-domains, the protein is involved in modulating cell-cell contacts, cell differentiation, lipid metabolism, and vesicle formation and acts as a scaffolding protein for several E3 ubiquitin ligases. MTSS1 is classified as a housekeeping protein and is never mutated despite the several pathologic phenotypes linked to its dysregulation. Despite MTSS1's involvement in fundamental signaling pathways, MTSS1 gene ablation is not ubiquitously lethal, although it affects embryonic development. Due to MTSS1´s involvement in many seemingly disparate processes, with many cases lacking mechanistic explanations, we found it timely to review the recent data on MTSS1's role at the cellular level, as well as in health and disease, to direct further studies on this interesting multifunctional protein.

Study of prognostic splicing factors in cancer using machine learning approaches

Splicing factors (SFs) are the major RNA-binding proteins (RBPs) and key molecules that regulate the splicing of mRNA molecules through binding to mRNAs. The expression of splicing factors is frequently deregulated in different cancer types, causing the generation of oncogenic proteins involved in cancer hallmarks. In this study, we investigated the genes that encode RNA-binding proteins and identified potential splicing factors that contribute to the aberrant splicing applying a random forest classification model. The result suggested 56 splicing factors were related to the prognosis of 13 cancers, two SF complexes in liver hepatocellular carcinoma, and one SF complex in esophageal carcinoma. Further systematic bioinformatics studies on these cancer prognostic splicing factors and their related alternative splicing events revealed the potential regulations in a cancer-specific manner. Our analysis found high ILF2-ILF3 expression correlates with poor prognosis in LIHC through alternative splicing. These findings emphasize the importance of SFs as potential indicators for prognosis or targets for therapeutic interventions. Their roles in cancer exhibit complexity and are contingent upon the specific context in which they operate. This recognition further underscores the need for a comprehensive understanding and exploration of the role of SFs in different types of cancer, paving the way for their potential utilization in prognostic assessments and the development of targeted therapies.

A potential new biomarker in HNSCC: metastasis suppressor protein 1 (MTSS1)

OBJECTIVE

Metastasis suppressor protein 1 (MTSS1) is a prognostic tumour marker in different malignant epithelial tumour entities and previously mainly the MTSS1 expression was analysed. This study evaluated the best analysis method as a prognosis and aggressiveness tumour marker in head and neck squamous cell carcinoma (HNSCC).

STUDY DESIGN

MTSS1 expression, MTSS1 intensity, interpretation MTSS1 score and MTSS1 edging score were analysed in formalin-fixed paraffin-embedded tissue slices of 60 patients with proven HNSCC and correlated with clinical and pathological outcome parameters.

RESULTS

A lack of MTSS1 expression showed tumour aggressiveness, but surprisingly, mainly MTSS1 intensity was correlated with a worse patient outcome. There was a significant correlation between higher MTSS1 intensity and an increased risk for lymph node metastasis (P = .027) and a significant increased risk for extracapsular growth (P = .016). Furthermore, disease-specific survival was worse in cases with higher MTSS1 intensity (P = .001).

CONCLUSION

MTSS1 intensity has a high scientific potential for further studies and could potentially be used as a prognostic marker in diagnostic and therapeutic decision-making.

Metastasis suppressor genes in clinical practice: are they druggable?

Since the identification of NM23 (now called NME1) as the first metastasis suppressor gene (MSG), a small number of other gene products and non-coding RNAs have been identified that suppress specific parameters of the metastatic cascade, yet which have little or no ability to regulate primary tumor initiation or maintenance. MSG can regulate various pathways or cell biological functions such as those controlling mitogen-activated protein kinase pathway mediators, cell-cell and cell-extracellular matrix protein adhesion, cytoskeletal architecture, G-protein-coupled receptors, apoptosis, and transcriptional complexes. One defining facet of this gene class is that their expression is typically downregulated, not mutated, in metastasis, such that any effective therapeutic intervention would involve their re-expression. This review will address the therapeutic targeting of MSG, once thought to be a daunting task only facilitated by ectopically re-expressing MSG in metastatic cells in vivo. Examples will be cited of attempts to identify actionable oncogenic pathways that might suppress the formation or progression of metastases through the re-expression of specific metastasis suppressors.

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

circFBXO7/miR-96-5p/MTSS1 axis is an important regulator in the Wnt signaling pathway in ovarian cancer

BACKGROUND

CircRNAs are a novel class of evolutionarily conserved noncoding RNA molecules that form covalently closed continuous loop structures without 5' caps and 3' poly(A) tails. Accumulating evidence suggests that circRNAs play important regulatory roles in cancer and are promising biomarkers for cancer diagnosis and prognosis, as well as targets for cancer therapy. In this study, we identify and explore the role of a novel circRNA, circFBXO7, in ovarian cancer.

METHODS

rRNA-depleted RNA-sequencing was performed to identify differentially expressed circRNAs between ovarian cancerous and normal tissues. qRT-PCR and single-molecule RNA in-situ hybridization was used to quantify circFBXO7 expression in tumor tissues. The association of circFBXO7 expression with patient prognosis was evaluated by Kaplan-Meier survival analysis. The biological function of circFBXO7 was also investigated using loss-of-function and gain-of-function assays in vivo and in vitro. Luciferase reporter and TOP/FOP-Flash reporter assays were then conducted together with RNA immunoprecipitation and western blot to assess the circFBXO7/miR-96-5p/MTSS1/Wnt/β-catenin axis.

RESULTS

circFBXO7 was downregulated in ovarian cancer which was associated with poor prognosis. Biologically, circFBXO7 overexpression significantly suppressed ovarian cancer cell proliferation, migration, and invasion in vitro, and inhibited tumor growth and metastasis in vivo, whereas its knockdown exerted an opposite role. Mechanistically, circFBXO7 functioned as a competing endogenous RNA for miR-96-5p to regulate the expression of MTSS1. Consequently, downregulation of MTSS1 led to excessive accumulation of β-catenin and increased phosphorylation of GSK3β, leading to the translocation of β-catenin to the nucleus, thereby activating the Wnt/β-catenin signaling pathway and ultimately promoting ovarian cancer progression.

CONCLUSIONS

Our findings indicate that circFBXO7 acts as a bone fide tumor suppressor in ovarian cancer and that the circFBXO7/miR-96-5p/MTSS1 axis is an important regulator in the Wnt/β-catenin signaling pathway which may provide a promising target for ovarian cancer therapy.

Chicory: Understanding the Effects and Effectors of This Functional Food

Industrial chicory has been the subject of numerous studies, most of which provide clinical observations on its health effects. Whether it is the roasted root, the flour obtained from the roots or the different classes of molecules that enter into the composition of this plant, understanding the molecular mechanisms of action on the human organism remains incomplete. In this study, we were interested in three molecules or classes of molecules present in chicory root: fructose, chlorogenic acids, and sesquiterpene lactones. We conducted experiments on the murine model and performed a nutrigenomic analysis, a metabolic hormone assay and a gut microbiota analysis, associated with in vitro observations for different responses. We have highlighted a large number of effects of all these classes of molecules that suggest a pro-apoptotic activity, an anti-inflammatory, antimicrobial, antioxidant, hypolipidemic and hypoglycemic effect and also an important role in appetite regulation. A significant prebiotic activity was also identified. Fructose seems to be the most involved in these activities, contributing to approximately 83% of recorded responses, but the other classes of tested molecules have shown a specific role for these different effects, with an estimated contribution of 23-24%.

Knockdown of lncRNA ZEB2NAT suppresses epithelial mesenchymal transition, metastasis and proliferation in breast cancer cells

Breast cancer is the second most common cause of cancer-related mortality in women. Breast cancer metastasis which usually is observed at the last stage is the major cause of breast cancer-related death. Long non-coding RNAs (lncRNAs) are member of the non-coding RNA family. It is known that lncRNAs have important functions in the genes regulation of different processes and pathways such as EMT (Epithelial mesenchymal transition), metastasis and apoptosis. Therefore, it is inevitable that lncRNAs have potential contribution for the understanding of cancer pathogenesis. lncRNA-ZEB2NAT is the natural antisense transcript of ZEB2. Herein, we investigated the effects of lncRNA-ZEB2NAT on process of EMT, metastasis and apoptosis in MCF7 and MDA-MB-231 breast cancer cells. The effect of ZEB2NAT on the expression of important genes in EMT, metastasis and apoptosis, and some protein levels was determined by qRT-PCR and western blot analysis, respectively. The effects of ZEB2NAT on cell proliferation, apoptosis, invasion and colony formation were evaluated using XTT, annexin V, invasion and colony assays, respectively. The ZEB2NAT knockdown caused anti-metastatic and apoptotic effects. The ZEB2NAT knockdown resulted in a decrease in ZEB2 and N-cadherin but an increase in E-cadherin protein levels. In addition, it was determined that ZEB2NAT knockdown significantly decreased cell proliferation and stimulated apoptosis in both cells. It was found that ZEB2NAT knockdown significantly decreased invasion and colony formation in both cells. ZEB2NAT knockdown showed anti-metastatic and apoptotic effect by affecting the important genes in both cells. These results have suggested that ZEB2NAT has an important role in EMT, metastasis and apoptosis in breast cancer and ZEB2NAT knockdown caused significant anti-cancer activities.

MicroRNAs as Biomarkers for Early Diagnosis, Prognosis, and Therapeutic Targeting of Ovarian Cancer

Ovarian cancer is the major cause of gynecologic cancer-related mortality. Regardless of outstanding advances, which have been made for improving the prognosis, diagnosis, and treatment of ovarian cancer, the majority of the patients will die of the disease. Late-stage diagnosis and the occurrence of recurrent cancer after treatment are the most important causes of the high mortality rate observed in ovarian cancer patients. Unraveling the molecular mechanisms involved in the pathogenesis of ovarian cancer may help find new biomarkers and therapeutic targets for ovarian cancer. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression, mostly at the posttranscriptional stage, through binding to mRNA targets and inducing translational repression or degradation of target via the RNA-induced silencing complex. Over the last two decades, the role of miRNAs in the pathogenesis of various human cancers, including ovarian cancer, has been documented in multiple studies. Consequently, these small RNAs could be considered as reliable markers for prognosis and early diagnosis. Furthermore, given the function of miRNAs in various cellular pathways, including cell survival and differentiation, targeting miRNAs could be an interesting approach for the treatment of human cancers. Here, we review our current understanding of the most updated role of the important dysregulation of miRNAs and their roles in the progression and metastasis of ovarian cancer. Furthermore, we meticulously discuss the significance of miRNAs as prognostic and diagnostic markers. Lastly, we mention the opportunities and the efforts made for targeting ovarian cancer through inhibition and/or stimulation of the miRNAs.

Metastasis suppressor 1 interacts with α-actinin 4 to affect its localization and regulate formation of membrane ruffling

Membrane ruffling plays an important role in the directed cell migration and escape of tumor cells from the monolayer. Metastasis suppressor 1 (MTSS1), also known as missing in metastasis, has been implicated in cell morphology, motility, metastasis, and development. Here, the dynamic interaction proteins associated with MTSS1 and involved in membrane ruffling were determined by cross-linking and mass spectrometry analysis. We identified α-actinin 4 (ACTN4) as an interacting protein and confirmed a direct interaction between MTSS1 and ACTN4. Moreover, co-expression of MTSS1 in fibroblasts recruited cytoplasmic ACTN4 to the cell periphery, at which point ruffling became thick and rigid. In MCF-7 cells, MTSS1 knockdown did not show an obvious effect on the cell shape or the distribution of endogenous ACTN4; however, ACTN4 overexpression transformed cell morphology from an epidermal- to a fibroblast-like shape, and further MTSS1 depletion significantly increased the ratio of fibroblast cells exhibiting prominent ruffling. Furthermore, biochemical data suggested that MTSS1 cross-linking with ACTN4 induced the formation of actin fiber bundles into more organized structures in vitro. These data indicated that MTSS1 might recruit cytoplasmic ACTN4 to the cell periphery and regulate cytoskeleton dynamics to restrict its performance in membrane ruffling.

Analysis of RPL37A, MTSS1, and HTRA1 expression as potential markers for pathologic complete response and survival

BACKGROUND

Non-metastatic locally advanced breast carcinoma (LABC) treatment involves neoadjuvant chemotherapy (NCT). We evaluated the association of clinical-pathological data and immunoexpression of hormone receptors, HER2 and Ki67, and new biomarkers, RPL37A, MTSS1 and HTRA1, with pathological complete response (PCR) or tumour resistance (stable disease or disease progression), disease-free survival (DFS) and cancer-specific survival (CSS).

METHODS

This is a retrospective study of 333 patients with LABC who underwent NCT. Expression of MTSS1, RPL37A and HTRA1/PRSS11 was evaluated by immunohistochemistry in TMA slides. Cutoff values were established for low and high tumour expression. ROC plotter evaluated response to NCT. Chi-square test for factors related to PCR, and Kaplan-Meier test and Cox model for factors related to DFS and CSS were prformed.

RESULTS

The mean follow-up was 70.0 months and PCR rate was 15.6%. At 120 months, DFS rate was 32.5% and CSS rate was 67.1%. In multivariate analysis, there was an association between: (1) necrosis presence, intense inflammatory infiltrate, ER absence, HER2 molecular subtype and high RPL3A expression with increased odds of PCR; (2) lymph node involvement (LNI), high Ki67, low RPL37A and high HTRA1 expression with increased risk for NCT non-response; (3) LNI, high proliferation, necrosis absence, low RPL37A and high HTRA1 expression with increased recurrence risk; (4) advanced LNI, ER negative tumours, high HTRA1, low RPL37A expression and desmoplasia presence with higher risk of cancer death.

CONCLUSION

RPL37A is a potential biomarker for response to NCT and for prognosis. Additional studies evaluating HTRA1 and MTSS1 prognostic value are needed.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

A reciprocal feedback of Myc and lncRNA MTSS1-AS contributes to extracellular acidity-promoted metastasis of pancreatic cancer

Rationale: Previous studies have reported on the role of extracellular acidity in the metastasis of numerous cancers. However, the involvement of long noncoding RNA (lncRNA) in the extracellular acidity-induced cancer metastasis of pancreatic cancer (PC) remains unclear. Methods: Different expression levels of lncRNAs in PC cells under normal and acidic conditions were compared by RNA sequencing (RNA-seq). The effects of antisense lncRNA of metastasis suppressor 1 (MTSS1-AS) on acidic PC cells were assessed by gain- and loss-of-function experiments. Fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down, Western blot, luciferase reporter, and Chromatin immunoprecipitation assays were employed to determine the regulatory mechanisms of MTSS1-AS in the acidity-induced metastasis of PC cells. The expression of MTSS1-AS and associated pathways were compared in PC samples and peritumoral normal tissues. Results: RNA-seq demonstrated that MTSS1-AS was significantly downregulated in pancreatic cells cultured with the acidic medium. The overexpression of MTSS1-AS remarkably inhibited the acidity-promoted metastasis of PC cells by upregulating the expression of its sense gene metastasis suppressor 1 (MTSS1). Mechanistically, MTSS1-AS scaffolded the interaction between E3 ubiquitin-protein ligase STIP1 homology and U-box containing protein 1 (STUB1) and transcription regulator myeloid zinc finger 1 (MZF1), leading to ubiquitination-mediated degradation of MZF1. Further, MZF1 inhibited the expression of MTSS1 by binding to the MTSS1 promoter. Thus, the acidity-reduced MTSS1-AS facilitated the stability of MZF1 and its inhibitory effect on MTSS1 transcription, thereby promoting the metastasis of PC cells under acidic conditions. Moreover, MTSS1-AS was transcriptionally repressed by the binding of MYC proto-oncogene (Myc) with initiator (Inr) elements of the MTSS1-AS promoter. Meanwhile, MTSS1-AS mutually repressed the expression of Myc by impairing the MZF1-mediated transcription activation of Myc, thereby forming a negative feedback loop between MTSS1-AS and Myc in acidic PC cells. In accordance with the experimental results, MTSS1-AS and MTSS1 were downregulated in PC and correlated with poor overall survival. Conclusions: The results implicated that a reciprocal feedback loop between Myc and MTSS1-AS contributed to the extracellular acidity-promoted metastasis of PC, and indicated that MTSS1-AS was a valuable biomarker and therapeutic target for PC.

Metastasis suppressor 1 acts as a tumor suppressor by inhibiting epithelial-to-mesenchymal transition in triple-negative breast cancer

OBJECTIVE

This study aimed to analyze the function of metastasis suppressor 1 (MTSS1) in triple negative breast cancer (TNBC).

METHODS

MTSS1 expression in 30 TNBC and paracancerous tissues was measured by quantitative reverse transcriptase polymerase chain reaction. The prognostic value of MTSS1 was assessed by Kaplan-Meier analysis followed by the log-rank test. MCF7 cells were transfected with si-MTSS1, while MDA-MB-231 cells were transfected with pcDNA3.1-MTSS1. Cell proliferation assay and transwell assay were performed to investigate the effects of MTSS1 on the biological behavior of breast cancer cells. Immunofluorescence and western blot were used to detect the influence of MTSS1 on epithelial-mesenchymal transition (EMT) markers.

RESULTS

MTSS1 expression was significantly lower in TNBC tissues compared with that in paracancerous tissues (0.012 vs. 0.370; P = 0.006). A lower MTSS1 expression level was also found in tumor tissues of patients with lymph node metastasis (P = 0.002) or tumor node metastasis stage (P = 0.010). Patients with low expression of MTSS1 (⩽ 0.009) had shorter disease-free survival (47.4 vs. 56.0 months; P = 0.012). The knockdown of MTSS1 in MCF7 cells inhibited cell proliferation, enhanced cell migration and invasion capacities, decreased the E-cadherin level, and increased the vimentin level, whereas overexpression of MTSS1 in MDA-MB-231 cells had the opposite effects (P < 0.05).

CONCLUSIONS

Our findings demonstrated that MTSS1 regulates proliferation, invasion, migration, and EMT in TNBC, and that decreased MTSS1 is associated with shorter disease-free survival.

Circular RNA SFMBT2 Inhibits the Proliferation and Metastasis of Glioma Cells Through Mir-182-5p/Mtss1 Pathway

Glioma is a common type of tumor in human central nervous system, and it is characterized with high mobility and mortality. The prognosis of patients with advanced glioma remains poor. Thus, it is necessary to develop novel therapeutic approaches for the treatment of this disease. Circular RNAs are a group of noncoding RNAs which have been detected in eukaryotic cells. They are tissue-specific and characterized with a more stable structure compared with linear RNAs. Recently, studies have revealed that certain circular RNAs are involved in biological processes such as gene regulation; however, the functions of most circular RNAs remain unknown and require further investigation. Furthermore, circular RNAs can act as "sponges" of its target microRNA, consequently suppressing their activity. Additionally, impaired expression of circular RNAs is reported in different diseases including cancer. In our study, low expression of circular RNA Scm like with 4 Mbt domains 2 was detected in glioma samples. Furthermore, reduced circRNA Scm like with 4 Mbt domains 2 expression was observed in human glioma cell lines compared to normal astrocyte cells. Additionally, overexpression of circRNA Scm like with 4 Mbt domains 2 suppressed the growth and metastasis of glioma cells in vitro. Moreover, microRNA-182-5p could be a downstream molecule of circRNA Scm like with 4 Mbt domains 2. The influenced of microRNA-182-5p-induced proliferation, migration, and invasion of glioma cells could be abrogated by overexpressed circRNA Scm like with 4 Mbt domains 2. In addition, metastasis suppressor 1 was predicted as a novel target of microRNA-182-5p, and its expression was restored by circRNA Scm like with 4 Mbt domains 2. In summary, our findings provided novel insight into the roles of circRNA Scm like with 4 Mbt domains 2 in glioma. More importantly, circRNA Scm like with 4 Mbt domains 2/microRNA-182-5p/metastasis suppressor 1 axis could be a putative therapeutic target for the treatment of patients with glioma.

MTSS1 hypermethylation is associated with prostate cancer progression

This study was conducted to evaluate the influence of DNA methylation of metastasis suppressor 1 (MTSS1) on prostate cancer (PCa) progression. Forty-nine paired PCa tissue samples and normal tissue samples from The Cancer Genome Atlas were analyzed. Methylome analysis, CpG island arrays and Hierarchical clustering were used to analyze methylation profiles of PCa tissues. MTSS1 methylation level was detected by methylation-specific PCR. Relative messenger RNA and the expression level of MTSS1 protein were identified by quantitative real-time PCR (qRT-PCR) and western blot analysis. The migration, invasion, proliferation, and cell cycle were detected separately by wound-healing assay, transwell chamber assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and flow cytometry. The roles of MTSS1 in PCa progression were demonstrated in vivo by tumor formation assays in nude mice. MTSS1 expression was decreased in PCa tissues in comparison with paired adjacent normal prostate tissues. Compared to the methylation of MTSS1 in normal prostate tissues based on the MethHC website, the MTSS1 in PCa tissues was hypermethylated. The expression of MTSS1 detected by qRT-PCR and western blot analysis was found to be downregulated in PCa cells and tissues. The reduced expression of MTSS1 by small interfering RNA-MTSS1 was recovered by 5-aza-2'-deoxycytidine treatment. Besides, MTSS1 demethylation inhibited migration, invasion, and proliferation of PCa cells, and induced cell cycle to be arrested at G0/G1 phase. Furthermore, it was shown by tumor xenograft assay that MTSS1 inhibited the growth of tumor in vivo. Hypermethylated MTSS1 promoted PCa cells migration, invasion, and proliferation, and suppressed cell cycle arrest at the G0/G1 phase.

Long non‑coding RNA MEG3 suppresses the growth of glioma cells by regulating the miR‑96‑5p/MTSS1 signaling pathway

Glioma is one of the most common types of tumor of the central nervous system with high mobility and mortality. The prognosis of patients with high-grade glioma is poor. Therefore, it is urgent to develop the therapeutic strategies for the treatment of glioma. Long non-coding RNAs (lncRNAs) have been reported as potential inducers or suppressors of numerous types of tumors including glioma. Previous studies have revealed that lncRNA maternally expressed gene 3 (MEG3) is involved in the initiation and progression of cancer; however, the underlying mechanisms remain unclear. In the present study, MEG3 was downregulated in glioma tissue. In addition, downregulation of MEG3 was observed in human glioma cell lines compared with normal astrocyte cells. Furthermore, overexpressed MEG3 inhibited the proliferation, migration and invasion of glioma cells. Additionally, microRNA-96-5p (miR-96-5p) was a promising target of MEG3, and the promoting effects of miR-96-5p on cell growth and metastasis could be reversed by upregulated MEG3. Metastasis suppressor 1 (MTSS1) was predicted as the putative target of miR-96-5p, and its expression was restored by MEG3. In summary, the present data provided novel insight into the roles of MEG3 in glioma, and MEG3/miR-96-5p/MTSS1 signaling could be a promising therapeutic target for the treatment of patients with glioma.

MTSS1 inhibits metastatic potential and induces G2/M phase cell cycle arrest in gastric cancer

Background: Metastasis suppressor 1 (MTSS1), a potential metastasis suppressor gene associated with tumor progression, may play an important role in cancer development. Our previous study demonstrated that MTSS1 was downregulated significantly when gastric cancer (GC) progressed and metastasized, suggesting that MTSS1 may be involved in the physiopathologic mechanism of GC.

Purpose: The objective of this study was to evaluate the effect of MTSS1 expression on the biological behavior of gastric cancer cell both in vitro and in vivo.

Materials and methods: The gain-and-loss function of MTSS1 in GC cells were analyzed after transfection with pEGFP-N1-MTSS1 and ShRNA431. Proliferation and invasion abilities were measured by means of plate clone formation assay and transwell assay. To further explore the underlying mechanism of MTSS1-induced tumor restrain, cell cycle distribution was analyzed using flow cytometry.

Results: The results revealed that overexpression of MTSS1 significantly reduced proliferation, migration and invasion of GC cells in vivo and in vitro, while downregulation of MTSS1 had the opposite biological manifestations. Moreover, overexpression of MTSS1 induced accumulation of GC cells in G2/M phase, increased phosphorylated Cdc2 expression and decreased Cdc25C and cyclinB1 levels, suggesting MTSS1 could cause G2/M cell cycle arrest.

Conclusion: Our data provided insight into an important role for MTSS1 in suppressing tumor cell proliferation, invasion and migration, indicating that MTSS, as a functional tumor suppressor in GC, could be a potential therapeutic target to prevent GC metastasis.

Advances in Targeting the Epidermal Growth Factor Receptor Pathway by Synthetic Products and Its Regulation by Epigenetic Modulators As a Therapy for Glioblastoma

Glioma is the most common primary tumor of the nervous system, and approximately 50% of patients exhibit the most aggressive form of the cancer, glioblastoma. The biological function of epidermal growth factor receptor (EGFR) in tumorigenesis and progression has been established in various types of cancers, since it is overexpressed, mutated, or dysregulated. Its overexpression has been shown to be associated with enhanced metastatic potential in glioblastoma, with EGFR at the top of a downstream signaling cascade that controls basic functional properties of glioblastoma cells such as survival, cell proliferation, and migration. Thus, EGFR is considered as an important therapeutic target in glioblastoma. Many anti-EGFR therapies have been investigated both in vivo and in vitro, making their way to clinical studies. However, in clinical trials, the potential efficacy of anti-EGFR therapies is low, primarily because of chemoresistance. Currently, a range of epigenetic drugs including histone deacetylase (HDAC) inhibitors, DNA methylation and histone inhibitors, microRNA, and different types of EGFR inhibitor molecules are being actively investigated in glioblastoma patients as therapeutic strategies. Here, we describe recent knowledge on the signaling pathways mediated by EGFR/EGFR variant III (EGFRvIII) with regard to current therapeutic strategies to target EGFR/EGFRvIII amplified glioblastoma.

Computational analysis of the evolutionarily conserved Missing In Metastasis/Metastasis Suppressor 1 gene predicts novel interactions, regulatory regions and transcriptional control

Missing in Metastasis (MIM), or Metastasis Suppressor 1 (MTSS1), is a highly conserved protein, which links the plasma membrane to the actin cytoskeleton. MIM has been implicated in various cancers, however, its modes of action remain largely enigmatic. Here, we performed an extensive in silico characterisation of MIM to gain better understanding of its function. We detected previously unappreciated functional motifs including adaptor protein (AP) complex interaction site and a C-helix, pointing to a role in endocytosis and regulation of actin dynamics, respectively. We also identified new functional regions, characterised with phosphorylation sites or distinct hydrophilic properties. Strong negative selection during evolution, yielding high conservation of MIM, has been combined with positive selection at key sites. Interestingly, our analysis of intra-molecular co-evolution revealed potential regulatory hotspots that coincided with reduced potentially pathogenic polymorphisms. We explored databases for the mutations and expression levels of MIM in cancer. Experimentally, we focused on chronic lymphocytic leukaemia (CLL), where MIM showed high overall expression, however, downregulation on poor prognosis samples. Finally, we propose strong conservation of MTSS1 also on the transcriptional level and predict novel transcriptional regulators. Our data highlight important targets for future studies on the role of MIM in different tissues and cancers.

MicroRNA-146b-3p Promotes Cell Metastasis by Directly Targeting NF2 in Human Papillary Thyroid Cancer

Background: MiR-146b has been reported to be overexpressed in papillary thyroid cancer (PTC) tissues and associated with aggressive PTC. MiR-146b is regarded as a relevant diagnostic marker for this type of cancer. MiR-146b-5p has been confirmed to increase cell proliferation by repressing SMAD4. However, detailed functional analysis of another mature form of miR-146b, miR-146b-3p, has not been carried out. This study aimed to identify the differential expression of miR-146b-5p and miR-146b-3p in more aggressive PTC associated with lymph node metastasis, and further elucidate the contribution and mechanism of miR-146b-3p in the process of PTC metastasis. Methods: Expression of miR-146b-5p and miR-146b-3p was assessed in formalin-fixed paraffin-embedded tissue samples from PTC patients, and the relationship with lymph node metastasis was analyzed. A variety of PTC cells, including BHP10-3, BHP10-3SC_mice, and K1 cells, were cultured and treated with miR-146b-5p or miR-146b-3p mimics/inhibitors. The cell migration and invasion abilities were characterized by the real-time cell analyzer assay and Transwell™ assay. PTC xenograft models were used to examine the effect of miR-146b-3p on PTC metastatic ability in vivo. Direct downstream targets of miR-146b-3p were analyzed by luciferase reporter assay and Western blotting. The mechanism by which miR-146b-3p affects cell metastasis was further characterized by co-transfection with merlin, the protein product of the NF2 gene. Results: MiR-146b-5p and miR-146b-3p expression was significantly higher in thyroid cancer tissues and cell lines than in normal thyroid tissue and cells. Moreover, expression of miR-146b-5p and miR-146b-3p was further increased in thyroid metastatic nodes than in thyroid cancer. After overexpression of miR-146b-5p or miR-146b-3p in BHP10-3 or K1 cells, PTC migration and invasion were increased. Notably, miR-146b-3p increased cell migration and invasion more obviously than did miR-146b-5p. Overexpression of miR-146b-3p also significantly promoted PTC tumor metastasis in vivo. Luciferase reporter assay results revealed that NF2 is a downstream target of miR-146b-3p in PTC cells, as miR-146b-3p bound directly to the 3' untranslated region of NF2, thus reducing protein levels of NF2. Overexpression of merlin reversed the enhanced aggressive effects of miR-146b-3p. Conclusions: Overexpression of miR-146b-5p and miR-146b-3p is associated with PTC metastasis. MiR-146b-3p enhances cell invasion and metastasis more obviously than miR-146b-5p through the suppression of the NF2 gene. These findings suggest a potential diagnostic and therapeutic value of these miRNAs in PTC metastasis.

Metastasis suppressor protein 1 regulated by PTEN suppresses invasion, migration, and EMT of gastric carcinoma by inactivating PI3K/AKT signaling

Epithelial-mesenchymal transition (EMT) is a crucial event for cancer progression and metastasis. Metastasis suppressor protein 1 (MTSS1) is a metastasis suppressor in several cancers. In this study, we elucidated the potential physiological function of MTSS1 in the invasion and migration of gastric cancer (GC), and its distinct role in EMT and subsequently determined the potential molecular mechanism. We observed that MTSS1 expression was downregulated in GC tissues and several GC cell lines (SGC-7901, MGC-803, MKN-28, MKN-45, and BGC-823). Importantly, forced expression of MTSS1 drastically diminished the cell viability in both SGC-7901 and MKN-45 cells. Moreover, overexpression of MTSS1 attenuated the invasion ability of these two cell lines. In addition to the invasive capability, introduction of MTSS1 led to a loss of migratory potential. Furthermore, augmentation of MTSS1 exhibited the typical EMT phenotype switch, accompanied by enhanced the expression of vimentin and N-cadherin and reduced E-cadherin expression. Interestingly, MTSS1 also repressed transforming growth factor beta 1 (TGF-β1)-induced EMT. Our mechanistic investigations revealed that MTSS1 was positively regulated by the phosphatase and tensin homolog (PTEN), and it functioned as a tumor suppressor, possibly by inactivating the phosphoinositide 3-kinase (PI3K)/v-akt murine thymoma viral oncogene (AKT) pathway in GC cells. Collectively, our data provide insight into an important role for MTSS1 in suppressing tumor cell invasion, migration and EMT, which indicates that MTSS1 may act as a prospective prognostic biological marker and a promising therapeutic target for GC.

MicroRNA-324-5p suppresses the migration and invasion of MM cells by inhibiting the SCFβ-TrCP E3 ligase

Multiple myeloma (MM) is a cytogenetically heterogeneous malignancy of plasma cells in bone marrow. Among the cytogenetic abnormalities of MM, del(17p) is a well-recognized high-risk genetic lesion associated with the late stage and progression of the disease. MicroRNA (miR)-324-5p, located at 17p13.1, was identified to be involved in the dysregulation of a number of types of malignant disease. However, whether miR-324-5p is associated with the development and progression of MM remains unknown. In the present study, the expression status of miR-324-5p in MM, and its effect on the migratory and invasive ability of MM cells were investigated. Using ubiquitination pathway polymerase chain reaction array, the inhibitory effect of miR-324-5p on the ubiquitinated proteins was investigated. It was identified that miR-324-5p levels were decreased in samples from patients with MM and MM cell lines. Increased expression of miR-324-5p by transfection of miR-324-5p mimic suppressed the proliferative, migratory and invasive abilities of MM.1R cells. Furthermore, increased expression of miR-324-5p in MM.1R cells inhibited the ubiquitination pathway and decreased the levels of ubiquitination-associated proteins, particularly the Skp1-Cullin1-F-box β-transducin repeat-containing protein (SCF^β-TrCP) E3 ligase. In addition, the results of the present study demonstrated that the SCF^β-TrCP E3 ligase may contribute to the suppression of MM cell motility by inhibiting the expression of metastasis-associated genes, including metastasis suppressor 1. In conclusion, the results of the present study suggested that miR-324-5p may act as a tumor suppressor by impairing the motility of MM cells by suppressing the ubiquitination pathway.

Expression and clinical significance of miR-23a and MTSS1 in diffuse large B-cell lymphoma

The present study investigated the expression and clinical significance of micro-ribonucleic acid-23a (miR-23a) and metastasis suppressor 1 (MTSS1) in diffuse large B-cell lymphoma (DLBCL). A total of 70 cases of tumor tissues of patients with DLBCL and 30 cases of reactive lymphoid hyperplasia tissues were collected. OCI-LY10 cell was transfected with miR-23a antisense oligonucleotide (miR-23a ASO). The expression of miR-23a and MTSS1 in tumor tissues of patients with DLBCL and reactive lymphoid hyperplasia tissues were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Spearmans test was used for correlation analysis was also performed for their expression. The relationship of the expressions of miR-23a and MTSS1 with the pathological parameters of patients with DLBCL was further analyzed. The DLBCL OCI-LY10 cells were cultured in vitro, and gene silencing downregulated the expression of miR-23a in OCI-LY10 cells. The expression of miR-23a was studied via RT-qPCR, and the effect of downregulation of miR-23a on MTSS1 protein expression was determined by western blot analysis. Moreover, the effects of miR-23a on the proliferation, metastasis and invasion capacities of OCI-LY10 cells were observed by both methyl thiazolyl tetrazolium (MTT) assay and Transwell chamber assay. The results of RT-qPCR showed that the mRNA expression of miR-23a in DLBCL tissues was significantly higher than that of reactive hyperplasia tissues. Immunohistochemical results revealed that the positive expression rate of MTSS1 in DLBCL tissues (30.00%) was significantly lower in comparison to reactive hyperplasia tissues (90.00%). Correlation analysis revealed that the miR-23a expression had a significant negative correlation with MTSS1 expression (r=-0.538, p=0.01). The expression of miR-23a and MTSS1 were correlated with the Ann Arbor staging, extranodal invasion and International Prognostic Index (IPI) scores of patients (p<0.05). However, they had no significant correlation with the sex and age of patients (p>0.05). After the downregulation of miR-23a expression, the MTSS1 protein expression in OCI-LY10 cells showed a significant increase. However, the proliferation, metastasis and invasion capacities of OCI-LY10 cells were obviously decreased. In conclusion, miR-23a promoted the proliferation, invasion and metastasis of DLBCL OCI-LY10 cells through the targeted inhibition of MTSS1. The high expression of miR-23a and the low expression of MTSS1 protein could be used as reference indexes for the prognosis of DLBCL.

MTSS1 and SCAMP1 cooperate to prevent invasion in breast cancer

Cell-cell adhesions constitute the structural "glue" that retains cells together and contributes to tissue organisation and physiological function. The integrity of these structures is regulated by extracellular and intracellular signals and pathways that act on the functional units of cell adhesion such as the cell adhesion molecules/adhesion receptors, the extracellular matrix (ECM) proteins and the cytoplasmic plaque/peripheral membrane proteins. In advanced cancer, these regulatory pathways are dysregulated and lead to cell-cell adhesion disassembly, increased invasion and metastasis. The Metastasis suppressor protein 1 (MTSS1) plays a key role in the maintenance of cell-cell adhesions and its loss correlates with tumour progression in a variety of cancers. However, the mechanisms that regulate its function are not well-known. Using a system biology approach, we unravelled potential interacting partners of MTSS1. We found that the secretory carrier-associated membrane protein 1 (SCAMP1), a molecule involved in post-Golgi recycling pathways and in endosome cell membrane recycling, enhances Mtss1 anti-invasive function in HER2+/ER-/PR- breast cancer, by promoting its protein trafficking leading to elevated levels of RAC1-GTP and increased cell-cell adhesions. This was clinically tested in HER2 breast cancer tissue and shown that loss of MTSS1 and SCAMP1 correlates with reduced disease-specific survival. In summary, we provide evidence of the cooperative roles of MTSS1 and SCAMP1 in preventing HER2+/ER-/PR- breast cancer invasion and we show that the loss of Mtss1 and Scamp1 results in a more aggressive cancer cell phenotype.

Reprogramming human A375 amelanotic melanoma cells by catalase overexpression: Upregulation of antioxidant genes correlates with regression of melanoma malignancy and with malignant progression when downregulated

Reactive oxygen species (ROS) are implicated in tumor transformation. The antioxidant system (AOS) protects cells from ROS damage. However, it is also hijacked by cancers cells to proliferate within the tumor. Thus, identifying proteins altered by redox imbalance in cancer cells is an attractive prognostic and therapeutic tool. Gene expression microarrays in A375 melanoma cells with different ROS levels after overexpressing catalase were performed. Dissimilar phenotypes by differential compensation to hydrogen peroxide scavenging were generated. The melanotic A375-A7 (A7) upregulated TYRP1, CNTN1 and UCHL1 promoting melanogenesis. The metastatic A375-G10 (G10) downregulated MTSS1 and TIAM1, proteins absent in metastasis. Moreover, differential coexpression of AOS genes (EPHX2, GSTM3, MGST1, MSRA, TXNRD3, MGST3 and GSR) was found in A7 and G10. Their increase in A7 improved its AOS ability and therefore, oxidative stress response, resembling less aggressive tumor cells. Meanwhile, their decrease in G10 revealed a disruption in the AOS and therefore, enhanced its metastatic capacity.

These gene signatures, not only bring new insights into the physiopathology of melanoma, but also could be relevant in clinical prognostic to classify between non aggressive and metastatic melanomas.

miR-96 promotes breast cancer metastasis by suppressing MTSS1

Novel, non-invasive biomarkers with high sensitivity and specificity are critical for breast cancer treatment, and prognosis. MicroRNA (miR)-96 has been demonstrated to be highly expressed in several solid malignancies, including breast cancer. However, its expression and function in the metastasis and prognosis of breast cancer have not been fully explored, and its regulation mechanisms remain unclear. In the present study, the serum miR-96 expression in healthy controls, benign and malignant breast cancer types was compared by using reverse transcription-quantitative polymerase chain reaction. The effect of chemotherapy on miR-96 expression in breast cancer was also investigated. Result revealed that miR-96 expression was increased in malignant breast cancer types and reduced in patients following chemotherapy treatment. The effect of miR-96 manipulation on the migration of breast cancer cells was also investigated by using wound healing, and Transwell migration assays. These results revealed that the induced expression of miR96 led to enhanced wound closing and trans-membrane cell numbers. By using bioinformatics analysis, western blotting and immunohistochemical staining, the metastasis suppressor-1 (MTSS1) gene was identified to be the functional target of miR-96 in the promotion of cell migration. In conclusion, it was identified that miR-96 exhibited an increased level in serum samples of patients with malignant breast cancer in comparison with benign breast tumor types and health controls and may be substantially reduced by chemotherapy treatment, implying that it may be used as a prognostic marker in breast cancer. miR-96 overexpression may inhibit migration of breast cancer cells by downregulating MTSS1 expression.

PTEN-Dependent Stabilization of MTSS1 Inhibits Metastatic Phenotype in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) presents at metastatic stage in over 50% of patients. With a survival rate of just 2.7% for patients presenting with distant disease, it is imperative to uncover novel mechanisms capable of suppressing metastasis in PDAC. Previously, we reported that the loss of metastasis suppressor protein 1 (MTSS1) in PDAC cells results in significant increase in cellular migration and invasion. Conversely, we also found that overexpressing MTSS1 in metastatic PDAC cell lines corresponds with not only decreased metastatic phenotype, but also greater overall survival. While it is known that MTSS1 is downregulated in late-stage PDAC, the mechanism behind that loss has not yet been elucidated. Here, we build off our previous findings to present a novel regulatory mechanism for the stabilization of MTSS1 via the tumor suppressor protein phosphatase and tensin homolog (PTEN). We show that PTEN loss in PDAC cells results in a decrease in MTSS1 expression and increased metastatic potential. Additionally, we demonstrate that PTEN forms a complex with MTSS1 in order to stabilize and protect it from proteasomal degradation. Finally, we show that the inflammatory tumor microenvironment, which makes up over 90% of PDAC tumor bulk, is capable of downregulating PTEN expression through secretion of miRNA-23b, potentially uncovering a novel extrinsic mechanism of MTSS1 regulation. Collectively, these data offer new insight into the role and regulation of MTSS1in suppressing tumor cell invasion and migration and help shed light as to what molecular mechanisms could be leading to early cell dissemination in PDAC.

Missing-in-metastasis B (MIM-B) combined with caveolin-1 promotes metastasis of hepatocellular carcinoma

BACKGROUND

Increasing amounts of evidence indicate that Missing in metastasis B (MIM-B) promotes cancer metastasis. Here, we sought to better understand the mechanism through which MIM-B promotes tumor metastasis in hepatocellular carcinoma (HCC).

METHODS

We performed confocal microscopy analysis to determine the distributions of MIM-B and caveolin-1 and conducted co-immunoprecipitation assays to detect the interactions between MIM-B and caveolin-1 in vitro. We performed transwell assays to analyze the invasive ability of HCC cells. Changes in the expression levels of key genes and some molecular makers were detected by immunohistochemistry and western blotting in HCC tissue samples.

RESULTS

We found that MIM-B co-localizes with caveolin-1 and demonstrated that MIM-B and caveolin-1 interact in vitro. Repressing MIM-B and caveolin-1 expression inhibited the epidermal growth factor receptor signaling pathway. We overexpressed MIM-B and caveolin-1 in Hep3B cells, which enhanced Hep3B cell invasiveness. Furthermore, MHCC97H cell invasiveness was significantly decreased in cells in which MIM-B and caveolin-1 expression was inhibited. Additionally, we found that MIM-B and caveolin-1 were expressed at higher levels in HCC tissues than in paired normal tissues. Moreover, HCC patients with MIM-B and caveolin-1 up-regulation experienced significantly worse outcomes than controls (P < 0.001), and HCC patients with high MIM-B and caveolin-1 expression levels often developed pulmonary metastasis (P < 0.001).

CONCLUSIONS

MIM-B combined with caveolin-1 promotes metastasis of HCC, and elevated MIM-B and caveolin-1 expression levels are associated with a poor prognosis in HCC patients; therefore, MIM-B and caveolin-1 may represent novel targets for the diagnosis and treatment of HCC.

Loss of MTSS1 results in increased metastatic potential in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of 7%. This dismal prognosis is largely due to the inability to diagnose the disease before metastasis occurs. Tumor cell dissemination occurs early in PDAC. While it is known that inflammation facilitates this process, the underlying mechanisms responsible for this progression have not been fully characterized. Here, we functionally test the role of metastasis suppressor 1 (MTSS1) in PDAC. Despite evidence showing that MTSS1 could be important for regulating metastasis in many different cancers, its function in PDAC has not been studied. Here, we show that loss of MTSS1 leads to increased invasion and migration in PDAC cell lines. Moreover, PDAC cells treated with cancer-associated fibroblast-conditioned media also have increased metastatic potential, which is augmented by loss of MTSS1. Finally, overexpression of MTSS1 in PDAC cell lines leads to a loss of migratory potential in vitro and an increase in overall survival in vivo. Collectively, our data provide insight into an important role for MTSS1 in suppressing tumor cell invasion and migration driven by the tumor microenvironment and suggest that therapeutic strategies aimed at increasing MTSS1 levels may effectively slow the development of metastatic lesions, increasing survival of patients with PDAC.

Comprehensive circular RNA profiling reveals the regulatory role of the circRNA-100338/miR-141-3p pathway in hepatitis B-related hepatocellular carcinoma

Circular RNAs (circRNAs) represent a class of endogenous noncoding RNAs that have recently been recognized as important regulators of gene expression and pathological networks. However, their transcriptional activities and functional mechanisms in cancer remain largely unknown. Here, we present results from a global circRNA expression and functional analysis of patients with hepatocellular carcinoma (HCC). Using a circRNA microarray, we identified 226 differentially expressed circRNAs, of which 189 were significantly upregulated and 37 were downregulated. High expression of circRNA_100338, one of the upregulated circRNAs in HCC, is closely correlated with a low cumulative survival rate and metastatic progression in HCC patients with hepatitis B. Furthermore, our in silico and experimental analyses identified miR-141-3p as a direct target of circRNA_100338. Thus, circRNA_100338 functions as an endogenous sponge for miR-141-3p in HCC. In addition, we identified the crucial antagonistic roles of circRNA_100338 and miR-141-3p in the regulation of invasive potential in liver cancer cells. Overall, the differential expression of multiple circRNAs in HCC tissues and their clinical significance in hepatitis B-related HCC patients as revealed by our study suggests that circRNA_100338 is a potentially valuable biomarker for HCC diagnosis and target for HCC therapeutics.

Missing-in-metastasis protein downregulates CXCR4 by promoting ubiquitylation and interaction with small Rab GTPases

Surface expression of chemokine receptor CXCR4 is downregulated by missing-in-metastasis protein (MIM; also known as MTSS1), a member of the inverse BAR (I-BAR)-domain protein family that recognizes and generates membranes with negative curvature. Yet, the mechanism for the regulation is unknown. Here, we show that MIM forms a complex with CXCR4 by binding to E3 ubiquitin ligase AIP4 (also known as ITCH) in response to stromal cell-derived factor 1 (SDF-1; also known as CXCL12). Overexpression of MIM promoted CXCR4 ubiquitylation, inhibited cellular response to SDF-1, caused accumulation and aggregation of multivesicular bodies (MVBs) in the cytoplasm, and promoted CXCR4 sorting into MVBs in a manner depending on binding to AIP4. In response to SDF-1, MIM also bound transiently to the small GTPase Rab5 at 5 min and to Rab7 at 30 min. Binding to Rab7 requires an N-terminal coiled-coil motif, deletion of which abolished MIM-mediated MVB formation and CXCR4 internalization. Our results unveil a previously unknown property of MIM that establishes the linkage of protein ubiquitylation with Rab-guided trafficking of CXCR4 in endocytic vesicles.

Human cytomegalovirus interleukin-10 enhances matrigel invasion of MDA-MB-231 breast cancer cells

BACKGROUND

While some risk factors for breast cancer are well-known, the influence of other factors, particularly virus infection, remains unclear. Human cytomegalovirus (HCMV) is widespread in the general population, and both molecular and epidemiological evidence has indicated links between HCMV and breast cancer. The HCMV protein cmvIL-10 is a potent suppressor of immune function that has also been shown to promote proliferation and migration of breast cancer cells. In this study, the impact of cmvIL-10 on tumor cell invasion through a simulated basement membrane was investigated.

RESULTS

MDA-MB-231 breast cancer cells exhibited invasion through a matrigel layer that was significantly enhanced in the presence of either purified cmvIL-10 or supernatants from HCMV-infected cells containing secreted cmvIL-10. Transcriptional profiling revealed that cmvIL-10 altered expression of several genes implicated in metastasis. Exposure to cmvIL-10 resulted in higher MMP-3 mRNA levels, greater protein expression, and increased enzymatic activity. Treatment with cmvIL-10 also increased expression of both urokinase plasminogen receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1), which can stimulate MMP-3 activity and have previously been identified as poor prognostic markers in breast cancer patients. Finally, MDA-MB-231 cells treated with cmvIL-10 showed significant downregulation of metastasis suppressor 1 (MTSS1), a scaffolding protein that regulates cytoskeletal rearrangements and is frequently lost in metastatic tumors.

CONCLUSIONS

HCMV, and in particular the secreted viral cytokine, cmvIL-10, can induce cellular changes that facilitate cell migration and invasion. These findings indicate that HCMV may be associated with promoting the malignant spread of breast cancer cells and suggest that antiviral treatment may be a useful complement to chemotherapy in some patients.

MTSS1 is epigenetically regulated in glioma cells and inhibits glioma cell motility

Epigenetic silencing by DNA methylation in brain tumors has been reported for many genes, however, their function on pathogenesis needs to be evaluated. We investigated the MTSS1 gene, identified as hypermethylated by differential methylation hybridization (DMH). Fifty-nine glioma tissue samples and seven glioma cell lines were examined for hypermethylation of the MTSS1 promotor, MTSS1 expression levels and gene dosage. GBM cell lines were treated with demethylating agents and interrogated for functional consequences of MTSS1 expression after transient transfection. Hypermethylation was significantly associated with IDH1/2 mutation. Comparative SNP analysis indicates higher incidence of loss of heterozygosity of MTSS1 in anaplastic astrocytomas and secondary glioblastomas as well as hypermethylation of the remaining allele. Reversal of promoter hypermethylation results in an increased MTSS1 expression. Cell motility was significantly inhibited by MTSS1 overexpression without influencing cell growth or apoptosis. Immunofluorescence analysis of MTSS1 in human astrocytes indicates co-localization with actin filaments. MTSS1 is down-regulated by DNA methylation in glioblastoma cell lines and is part of the G-CIMP phenotype in primary glioma tissues. Our data on normal astrocytes suggest a function of MTSS1 at focal contact structures with an impact on migratory capacity but no influence on apoptosis or cellular proliferation.

Role of Akt2 in regulation of metastasis suppressor 1 expression and colorectal cancer metastasis

Survival signaling is critical for the metastatic program of cancer cells. The current study investigated the role of Akt survival proteins in colorectal cancer (CRC) metastasis and explored potential mechanisms of Akt-mediated metastasis regulation. Using an orthotopic implantation model in mice, which uniquely recapitulates the entire multistep process of CRC metastasis, combined with an inducible system of short hairpin RNA-mediated Akt isoform knockdown in human CRC cells, our studies confirm a role of Akt2 in CRC cell dissemination to distant organs in vivo. Akt2 deficiency profoundly inhibited the development of liver lesions in mice, whereas Akt1 had no effect under the experimental conditions used in the study. Array analysis of human metastatic genes identified the scaffolding protein metastasis suppressor 1 (MTSS1) as a novel Akt2-regulated gene. Inducible loss of Akt2 in CRC cells robustly upregulated MTSS1 at the messenger RNA and protein level, and the accumulated protein was functionally active as shown by its ability to engage an MTSS1-Src-cortactin inhibitory axis. MTSS1 expression led to a marked reduction in levels of functional cortacin (pcortactin Y421), an actin nucleation-promoting factor that has a crucial role in cancer cell invasion and metastasis. MTSS1 was also shown to mediate suppressive effects of Akt2 deficiency on CRC cell viability, survival, migration and actin polymerization in vitro. The relevance of these findings to human CRC is supported by analysis of The Cancer Genome Atlas (TCGA) and NCBI GEO data sets, which demonstrated inverse changes in expression of Akt2 and MTSS1 during CRC progression. Taken together, the data identify MTSS1 as a new Akt2-regulated gene, and point to suppression of MTSS1 as a key step in the metastasis-promoting effects of Akt2 in CRC cells.

Distinct Epigenetic Effects of Tobacco Smoking in Whole Blood and among Leukocyte Subtypes

Tobacco smoke exposure dramatically alters DNA methylation in blood cells and may mediate smoking-associated complex diseases through effects on immune cell function. However, knowledge of smoking effects in specific leukocyte subtypes is limited. To better characterize smoking-associated methylation changes in whole blood and leukocyte subtypes, we used Illumina 450K arrays and Reduced Representation Bisulfite Sequencing (RRBS) to assess genome-wide DNA methylation. Differential methylation analysis in whole blood DNA from 172 smokers and 81 nonsmokers revealed 738 CpGs, including 616 previously unreported CpGs, genome-wide significantly associated with current smoking (p <1.2x10-7, Bonferroni correction). Several CpGs (MTSS1, NKX6-2, BTG2) were associated with smoking duration among heavy smokers (>22 cigarettes/day, n = 86) which might relate to long-term heavy-smoking pathology. In purified leukocyte subtypes from an independent group of 20 smokers and 14 nonsmokers we further examined methylation and gene expression for selected genes among CD14+ monocytes, CD15+ granulocytes, CD19+ B cells, and CD2+ T cells. In 10 smokers and 10 nonsmokers we used RRBS to fine map differential methylation in CD4+ T cells, CD8+ T cells, CD14+, CD15+, CD19+, and CD56+ natural killer cells. Distinct cell-type differences in smoking-associated methylation and gene expression were identified. AHRR (cg05575921), ALPPL2 (cg21566642), GFI1 (cg09935388), IER3 (cg06126421) and F2RL3 (cg03636183) showed a distinct pattern of significant smoking-associated methylation differences across cell types: granulocytes> monocytes>> B cells. In contrast GPR15 (cg19859270) was highly significant in T and B cells and ITGAL (cg09099830) significant only in T cells. Numerous other CpGs displayed distinctive cell-type responses to tobacco smoke exposure that were not apparent in whole blood DNA. Assessing the overlap between these CpG sites and differential methylated regions (DMRs) with RRBS in 6 cell types, we confirmed cell-type specificity in the context of DMRs. We identified new CpGs associated with current smoking, pack-years, duration, and revealed unique profiles of smoking-associated DNA methylation and gene expression among immune cell types, providing potential clues to hematopoietic lineage-specific effects in disease etiology.

Effect of metastasis suppressor 1 on H1299 cells and its clinical significance in non-small cell lung cancer

The present study aimed to investigate the effect of metastasis suppressor 1 (MTSS1) on the proliferation, migration and invasion of human H1299 non-small cell lung cancer cells and its clinical significance in non‑small cell lung cancer. The target gene MTSS1-overexpressing lentivirus (LV-MTSS1) was transfected into H1299 cells and expression of MTSS1 was detected at the mRNA and protein levels. Cell Counting Kit-8, wound healing and Transwell assays revealed that the migration and invasion activities were significantly suppressed by MTSS1, but that it had no effect on cell proliferation. In addition, MTSS1 expression in tissue microarrays including samples from 223 cases of non-small cell lung cancer was tested by immunohistochemistry to explore the correlation between MTSS1 and clinicopathological characteristics and prognosis. MTSS1 suppressed H1299 cell migration and invasion, and its expression level can be used as a new independent factor for determining the prognosis of non-small cell lung cancer.

Increased expression of Solute carrier family 12 member 5 via gene amplification contributes to tumour progression and metastasis and associates with poor survival in colorectal cancer

OBJECTIVE

Using whole genome sequencing, we identified gene amplification of solute carrier family 12 member 5 (SLC12A5) located at 20q13.12 in colorectal cancer (CRC). We analysed its amplification, overexpression, biological effects and prognostic significance in CRC.

DESIGN

SLC12A5 amplification status was evaluated by fluorescence in situ hybridisation (FISH). The effects of SLC12A5 re-expression or knockdown were determined in proliferation, apoptosis, invasion and metastasis assays. SLC12A5 target genes and related pathways were identified by reporter activity and cDNA microarray analyses. Clinical impact of SLC12A5 overexpression was assessed in 195 patients with CRC.

RESULTS

Amplification of SLC12A5 was verified in 78 out of 191 (40.8%) patients with primary CRC by FISH, which was positively correlated with its protein overexpression (p<0.001). Biofunctional investigation of SLC12A5 revealed that SLC12A5 significantly increased cell proliferation, G1-S cell cycle transition, invasion/migration abilities, but suppressed apoptosis in vitro and promoted xenograft tumour growth as well as lung metastasis in vivo. The antiapoptosis effect by SLC12A5 was mediated through inhibiting apoptosis-inducing factor and endonuclease G-dependent apoptotic signalling pathway; and the pro-metastasis role was by regulating key elements of the matrix architecture, including matrix metallopeptidase and fibronectin. After a median follow-up of 50.16 months, multivariate analysis revealed that patients with SLC12A5 protein overexpression had a significant decrease in overall survival. Kaplan-Meier survival curves showed that SLC12A5 overexpression was significantly associated with shortened survival in patients with CRC.

CONCLUSIONS

SLC12A5 plays a pivotal oncogenic role in colorectal carcinogenesis; its overexpression is an independent prognostic factor of patients with CRC.

Expression and Significances of MTSS1 in Pancreatic Cancer

Thus far, expression of metastasis suppressor 1 (MTSS1), its clinicopathologic and prognostic significances in pancreatic cancer (PC) remain unknown. Expression of MTSS1 was detected by Western blotting in PC cell lines, and by tissue microarray-based immunohistochemical staining in paired tumor and non-tumor samples from 242 patients with PC. Furthermore, the correlations between MTSS1 expression and clinicopathologic variables as well as overall survival were evaluated. In PC cell lines, MTSS1 was differentially expressed. In addition, MTSS1 expression was significantly lower in tumor than in non-tumor tissues (P < 0.001 in both McNemar and Mann-Whitney U tests). High tumoral expression of MTSS1 was closely associated with absence of lymph node metastasis (P = 0.023). Univariate analysis found that high MTSS1 expression in tumor tissues was a strong predictor of favorable overall survival in the whole cohort (P < 0.001). Besides, its impacts on prognosis were also observed in nine out of fourteen subgroups. Finally, MTSS1 expression was identified as an independent prognostic marker in the whole cohort (P = 0.031) as well as in six subgroups (P < 0.05), as shown by multivariate Cox regression test. Down-regulation of MTSS1 expression is evident in PC, and is associated with lymph node metastasis and poor prognosis.

p63 controls cell migration and invasion by transcriptional regulation of MTSS1

Metastasis is a multistep cell-biological process, which is orchestrated by many factors, including metastasis activators and suppressors. Metastasis Suppressor 1 (MTSS1) was originally identified as a metastasis suppressor protein whose expression is lost in metastatic bladder and prostate carcinomas. However, recent findings indicate that MTSS1 acts as oncogene and pro-migratory factor in melanoma tumors. Here, we identify and characterized a molecular mechanism controlling MTSS1 expression, which impinges on a pro-tumorigenic role of MTSS1 in breast tumors. We found that in normal and in cancer cell lines ΔNp63 is able to drive the expression of MTSS1 by binding to a p63-binding responsive element localized in the MTSS1 locus. We reported that ΔNp63 is able to drive the migration of breast tumor cells by inducing the expression of MTSS1. Notably, in three human breast tumors data sets the MTSS1/p63 co-expression is a negative prognostic factor on patient survival, suggesting that the MTSS1/p63 axis might be functionally important to regulate breast tumor progression.

Identification of the Adapter Molecule MTSS1 as a Potential Oncogene-Specific Tumor Suppressor in Acute Myeloid Leukemia

The adapter protein metastasis suppressor 1 (MTSS1) is implicated as a tumor suppressor or tumor promoter, depending on the type of solid cancer. Here, we identified Mtss1 expression to be increased in AML subsets with favorable outcome, while suppressed in high risk AML patients. High expression of MTSS1 predicted better clinical outcome of patients with normal-karyotype AML. Mechanistically, MTSS1 expression was negatively regulated by FLT3-ITD signaling but enhanced by the AML1-ETO fusion protein. DNMT3B, a negative regulator of MTSS1, showed strong binding to the MTSS1 promoter in PML-RARA positive but not AML1-ETO positive cells, suggesting that AML1-ETO leads to derepression of MTSS1. Pharmacological treatment of AML cell lines carrying the FLT3-ITD mutation with the specific FLT3 inhibitor PKC-412 caused upregulation of MTSS1. Moreover, treatment of acute promyelocytic cells (APL) with all-trans retinoic acid (ATRA) increased MTSS1 mRNA levels. Taken together, our findings suggest that MTSS1 might have a context-dependent function and could act as a tumor suppressor, which is pharmacologically targetable in AML patients.

Missing-in-Metastasis regulates cell motility and invasion via PTPδ-mediated changes in SRC activity

MIM (Missing-in-Metastasis), also known as MTSS1 (metastasis suppressor 1), is a scaffold protein that is down-regulated in multiple metastatic cancer cell lines compared with non-metastatic counterparts. MIM regulates cytoskeletal dynamics and actin polymerization, and has been implicated in the control of cell motility and invasion. MIM has also been shown to bind to a receptor PTP (protein tyrosine phosphatase), PTPδ, an interaction that may provide a link between tyrosine-phosphorylation-dependent signalling and metastasis. We used shRNA-mediated gene silencing to investigate the consequences of loss of MIM on the migration and invasion of the MCF10A mammary epithelial cell model of breast cancer. We observed that suppression of MIM by RNAi enhanced migration and invasion of MCF10A cells, effects that were associated with increased levels of PTPδ. Furthermore, analysis of human clinical data indicated that PTPδ was elevated in breast cancer samples when compared with normal tissue. We demonstrated that the SRC protein tyrosine kinase is a direct substrate of PTPδ and, upon suppression of MIM, we observed changes in the phosphorylation status of SRC; in particular, the inhibitory site (Tyr527) was hypophosphorylated, whereas the activating autophosphorylation site (Tyr416) was hyperphosphorylated. Thus the absence of MIM led to PTPδ-mediated activation of SRC. Finally, the SRC inhibitor SU6656 counteracted the effects of MIM suppression on cell motility and invasion. The present study illustrates that both SRC and PTPδ have the potential to be therapeutic targets for metastatic tumours associated with loss of MIM.

EGF induces microRNAs that target suppressors of cell migration: miR-15b targets MTSS1 in breast cancer

Growth factors promote tumor growth and metastasis. We found that epidermal growth factor (EGF) induced a set of 22 microRNAs (miRNAs) before promoting the migration of mammary cells. These miRNAs were more abundant in human breast tumors relative to the surrounding tissue, and their abundance varied among breast cancer subtypes. One of these miRNAs, miR-15b, targeted the 3' untranslated region of MTSS1 (metastasis suppressor protein 1). Although xenografts in which MTSS1 was knocked down grew more slowly in mice initially, longer-term growth was unaffected. Knocking down MTSS1 increased migration and Matrigel invasion of nontransformed mammary epithelial cells. Overexpressing MTSS1 in an invasive cell line decreased cell migration and invasiveness, decreased the formation of invadopodia and actin stress fibers, and increased the formation of cellular junctions. In tissues from breast cancer patients with the aggressive basal subtype, an inverse correlation occurred with the high expression of miRNA-15b and the low expression of MTSS1. Furthermore, low abundance of MTSS1 correlated with poor patient prognosis. Thus, growth factor-inducible miRNAs mediate mechanisms underlying the progression of cancer.

Downregulation of MTSS1 expression is an independent prognosticator in squamous cell carcinoma of the lung

Background:

The metastasis suppressor 1 (MTSS1) is a newly discovered protein putatively involved in tumour progression and metastasis.

Material and Methods:

Immunohistochemical expression of MTSS1 was analysed in 264 non-small-cell lung carcinomas (NSCLCs).

Results:

The metastasis suppressor 1 was significantly overexpressed in NSCLC compared with normal lung (P=0.01). Within NSCLC, MTSS1 expression was inversely correlated with pT-stage (P=0.019) and histological grading (P<0.001). NSCLC with MTSS1 downregulation (<20%) showed a significantly worse outcome (P=0.007). This proved to be an independent prognostic factor in squamous cell carcinomas (SCCs; P=0.041), especially in early cancer stages (P=0.006).

Conclusion:

The metastasis suppressor 1 downregulation could thus serve as a stratifying marker for adjuvant therapy in early-stage SCC of the lung.