Identification and characterization of TM4SF1+ tumor self-seeded cells.

Tumor self-seeding is a process whereby circulating tumor cells (CTCs) recolonize the primary tumor, which promotes tumor growth, angiogenesis, and invasion. However, the detailed nature and functions of tumor self-seeded cells (TSCs) have not been well defined due to challenges in tracking and isolating TSCs. Here, we report an accurate animal model using photoconvertible tagging to recapitulate the spontaneous process of tumor self-seeding and identify TSCs as a subpopulation of primary tumor cells with enhanced invasiveness and survival. We demonstrate transmembrane-4-L-six-family-1 (TM4SF1) as a marker of TSCs, which promotes migration, invasion, and anchorage-independent survival in cancer cells. By analyzing single-cell RNA sequencing datasets, we identify a potential TSC population with a metastatic profile in patients with cancer, which is detectable in early-stage disease and expands during cancer progression. In summary, we establish a framework to study TSCs and identify emerging cell targets with diagnostic, prognostic, or therapeutic potential in cancers.

TM4SF1 is a molecular facilitator that distributes cargo proteins intracellularly in endothelial cells in support of blood vessel formation.

Transmembrane-4 L-six family member-1 (TM4SF1) is an atypical tetraspanin that is highly and selectively expressed in proliferating endothelial cells and plays an essential role in blood vessel development. TM4SF1 forms clusters on the cell surface called TMED (TM4SF1-enriched microdomains) and recruits other proteins that internalize along with TM4SF1 via microtubules to intracellular locations including the nucleus. We report here that tumor growth and wound healing are inhibited in Tm4sf1-heterozygous mice. Investigating the mechanisms of TM4SF1 activity, we show that 12 out of 18 signaling molecules examined are recruited to TMED on the surface of cultured human umbilical vein endothelial cells (HUVEC) and internalize along with TMED; notable among them are PLCγ and HDAC6. When TM4SF1 is knocked down in HUVEC, microtubules are heavily acetylated despite normal levels of HDAC6 protein, and, despite normal levels of VEGFR2, are unable to proliferate. Together, our studies indicate that pathological angiogenesis is inhibited when levels of TM4SF1 are reduced as in Tm4sf1-heterozygous mice; a likely mechanism is that TM4SF1 regulates the intracellular distribution of signaling molecules necessary for endothelial cell proliferation and migration.

Integrative Single Cell Atlas Revealed Intratumoral Heterogeneity Generation from an Adaptive Epigenetic Cell State in Human Bladder Urothelial Carcinoma.

Intratumor heterogeneity (ITH) of bladder cancer (BLCA) contributes to therapy resistance and immune evasion affecting clinical prognosis. The molecular and cellular mechanisms contributing to BLCA ITH generation remain elusive. It is found that a TM4SF1-positive cancer subpopulation (TPCS) can generate ITH in BLCA, evidenced by integrative single cell atlas analysis. Extensive profiling of the epigenome and transcriptome of all stages of BLCA revealed their evolutionary trajectories. Distinct ancestor cells gave rise to low-grade noninvasive and high-grade invasive BLCA. Epigenome reprograming led to transcriptional heterogeneity in BLCA. During early oncogenesis, epithelial-to-mesenchymal transition generated TPCS. TPCS has stem-cell-like properties and exhibited transcriptional plasticity, priming the development of transcriptionally heterogeneous descendent cell lineages. Moreover, TPCS prevalence in tumor is associated with advanced stage cancer and poor prognosis. The results of this study suggested that bladder cancer interacts with its environment by acquiring a stem cell-like epigenomic landscape, which might generate ITH without additional genetic diversification.

Breast cancer malignancy is governed by regulation of the macroH2A2/TM4SF1 axis, the AKT/NF-κB pathway, and elevated MMP13 expression.

The histone variant, macroH2A (mH2A) influences gene expression through epigenetic regulation. Tumor suppressive function of mH2A isoforms has been reported in various cancer types, but few studies have investigated the functional role of mH2A2 in breast cancer pathophysiology. This study aimed to determine the significance of mH2A2 in breast cancer development and progression by exploring its downstream regulatory mechanisms. Knockdown of mH2A2 facilitated the migration and invasion of breast cancer cells, whereas its overexpression exhibited the opposite effect. In vivo experiments revealed that augmenting mH2A2 expression reduced tumor growth and lung metastasis. Microarray analysis showed that TM4SF1 emerged as a likely target linked to mH2A2 owing to its significant suppression in breast cancer cell lines where mH2A2 was overexpressed among the genes that exhibited over twofold upregulation upon mH2A2 knockdown. Suppressing TM4SF1 reduced the migration, invasion, tumor growth, and metastasis of breast cancer cells in vitro and in vivo. TM4SF1 depletion reversed the increased aggressiveness triggered by mH2A2 knockdown, suggesting a close interplay between mH2A2 and TM4SF1. Our findings also highlight the role of the mH2A2/TM4SF1 axis in activating the AKT/NF-κB pathway. Consequently, activated NF-κB signaling leads to increased expression and secretion of MMP13, a potent promoter of metastasis. In summary, we propose that the orchestrated regulation of the mH2A2/TM4SF1 axis in conjunction with the AKT/NF-κB pathway and the subsequent elevation in MMP13 expression constitute pivotal factors governing the malignancy of breast cancer.

Single-cell RNA sequencing reveals cancer stem-like cells and dynamics in tumor microenvironment during cholangiocarcinoma progression.

Cholangiocarcinoma is a malignancy of the bile ducts that is driven by activities of cancer stem-like cells and characterized by a heterogeneous tumor microenvironment. To better understand the transcriptional profiles of cancer stem-like cells and dynamics in the tumor microenvironment during the progression of cholangiocarcinoma, we performed single-cell RNA analysis on cells collected from three different timepoints of tumorigenesis in a YAP/AKT mouse model. Bulk RNA sequencing data from TCGA (The Cancer Genome Atlas program) and ICGC cohorts were used to verify and support the finding. In vitro and in vivo experiments were performed to assess the stemness of cancer stem-like cells. We identified Tm4sf1high malignant cells as cancer stem-like cells. Across timepoints of cholangiocarcinoma formation in YAP/AKT mice, we found dynamic change in cancer stem-like cell/stromal/immune cell composition. Nevertheless, the dynamic interaction among cancer stem-like cells, immune cells, and stromal cells at different timepoints was elaborated. Collectively, these data serve as a useful resource for better understanding cancer stem-like cell and malignant cell heterogeneity, stromal cell remodeling, and immune cell reprogramming. It also sheds new light on transcriptomic dynamics during cholangiocarcinoma progression at single-cell resolution.

Prognostic significance of TM4SF1 and DDR1 expression in epithelial ovarian cancer.

Transmembrane 4 L6 family member 1 (TM4SF1) and discoidin domain receptor 1 (DDR1) are expressed in numerous types of cancer, but their expression in epithelial ovarian cancer and the association between their expression and patient prognosis are unclear. The present study aimed to explore the expression of TM4SF1 and DDR1 and their relationship with prognosis in epithelial ovarian cancer. Firstly, the Oncomine and Gene Expression Profiling Interactive Analysis (GEPIA) platforms were used to compare the expression levels of TM4SF1 and DDR1 in ovarian cancer and normal ovarian tissue, and Kaplan-Meier plotter was used to analyze the association between gene expression and patient prognosis. The proteins interacting with TM4SF1 and DDR1 were analyzed using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and enrichment analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways was conducted for the interacting proteins. Furthermore, immunohistochemical staining was performed to detect the expression of TM4SF1 and DDR1 protein in epithelial ovarian cancer tissue and to analyze the association between expression and prognosis. The Oncomine and GEPIA analyses showed that the expression levels of TM4SF1 and DDR1 were significantly higher in epithelial ovarian cancer than in normal ovarian tissue, and the analysis of clinical samples revealed that TM4SF1 and DDR1 were coexpressed in some cases. STRING analysis indicated that the TM4SF1 and DDR1 proteins interact with each other. The overall survival and progression-free survival of patients whose epithelial ovarian cancer coexpressed TM4SF1 and DDR1 were significantly shorter than those of patients lacking TM4SF1 and DDR1 coexpression. Multivariate analysis indicated that TM4SF1 and DDR1 protein coexpression was an independent prognostic factor. In summary, TM4SF1 and DDR1 proteins were coexpressed in some epithelial ovarian cancer tissues and appear to be adverse prognostic factors for epithelial ovarian cancer. In addition, TM4SF1 and DDR1 may have an interactive or mutual regulatory mechanism.

Construction of CAR-T cells targeting TM4SF1 and its anti-tumor capacity in ovarian cancer.

Ovarian cancer (OC) is the most lethal gynecological malignancy with a 5-year survival rate of 49.1% on average. In clinical practice, cytoreduction and chemotherapy remain the conventional treatment for advanced OC. However, the overall prognosis remains poor, which urges oncologists to develop new treatments. Chimeric antigen receptor (CAR)-T therapy as a branch of immunotherapy had gained a success in treating hematological malignancies. TM4SF1, a potential biomarker in many tumors, was validated highly expressed in ovarian cancer. Here we constructed a 3rd generation CAR-T agent targeting TM4SF1 to treat ovarian cancer. CAR-T cells showed a specific cytotoxicity against TM4SF1 positive tumor cell lines in vitro and repressed SKOV3-derived tumor growth in vivo. This is the first time reporting a CAR-T therapy targeting TM4SF1 in ovarian cancer. Our results suggested that TM4SF1 could be a very promising target in curing OC and showed the possibility of TM4SF1-based immunotherapy.

MicroRNA-501-3p targeting TM4SF1 facilitates tumor-related behaviors of gastric cancer cells via EMT signaling pathway.

BACKGROUND: Increasing evidence shows that Transmembrane 4 L6 family member 1(TM4SF1) exerts a critical role in mediating the progression of various tumors. Nevertheless, the exact mechanism of TM4SF1 in gastric cancer (GC) remains unclear. METHODS: Bioinformatics analysis was utilized to analyze TM4SF1 expression in GC tissues. Also, MiRWalk and starBase databases were used to predict the upstream microRNAs which could regulate TM4SF1 expression. Gene set enrichment analysis (GSEA) for TM4SF1 was conducted to screen the potentially involved pathways. Dysregulation of microRNA-501-3p/TM4SF1 was implemented to investigate the regulatory roles of these genes in GC. qRT-PCR and western blot were employed to measure the expression changes of microRNA-501-3p, TM4SF1, and epithelial-mesenchymal transition (EMT) signaling pathway-associated proteins. CCK-8, colony formation, and transwell assays were introduced to examine the biological functions of GC cell lines. RESULTS: TM4SF1 presented a significantly low level in mRNA and protein in GC cells. MicroRNA-501-3p could target TM4SF1 and reduce its expression. Cell function experiments revealed that microRNA-501-3p facilitated cell proliferation, migration, and invasion, while inhibiting cell apoptosis in GC by targeting TM4SF1. EMT-associated proteins were altered by changing microRNA-501-3p/TM4SF1 axis. CONCLUSION: MicroRNA-501-3p regulated EMT signaling pathway by down-regulating TM4SF1 expression and therefore facilitated the malignant progression of GC, which may provide a new potential therapeutic target for the treatment of GC patients.

lncRNA TM4SF1-AS1 predicts dismal outcomes and promotes cholangiocarcinoma progression via modulating miR-744-3p.

BACKGROUND: Cholangiocarcinoma (CCA) is of great malignancy and high mortality. Identification of effective biomarkers could improve the monitoring of CCA development and attenuate patients' outcomes. OBJECTIVE: The potential of lncRNA TM4SF1-AS1 (TM4SF1-AS1) serving biomarker of CCA was estimated and the underlying mechanism was also investigated. METHODS: A total of 107 pairs of tumor and paracancer tissues were collected from CCA patients. The expression levels of TM4SF1-AS1 and miR-744-3p were analyzed in CCA by PCR, and their clinical significance was estimated by a series of statistical analyses. CCK8 and Transwell assays were used to assess the development-related cellular processes of CCA. The interaction between TM4SF1-AS1 and miR-774-3p was evaluated by cell transfection and dual-luciferase reporter assay. RESULTS: The elevated expression of TM4SF1-AS1 and the declined expression of miR-744-3p were observed in CCA. Both TM4SF1-AS1 and miR-744-3p were found to possess a close association with the malignant progression and poor prognosis of CCA patients. TM4SF1-AS1 was suggested to act as a tumor promoter of CCA, where miR-744-3p was found to mediate the function of TM4SF1-AS1. CONCLUSION: Both TM4SF1-AS1 and miR-744-3p were identified as prognostic biomarkers of CCA. TM4SF1-AS1 served as tumor promoter of CCA via modulating miR-744-3p.

Immune Infiltration and Clinical Outcome of Super-Enhancer-Associated lncRNAs in Stomach Adenocarcinoma.

Super-enhancers (SEs) comprise large clusters of enhancers that highly enhance gene expression. Long non-coding RNAs (lncRNAs) tend to be dysregulated in cases of stomach adenocarcinoma (STAD) and are vital for balancing tumor immunity. However, whether SE-associated lncRNAs play a role in the immune infiltration of STAD remains unknown. In the present study, we identified SE-associated lncRNAs in the H3K27ac ChIP-seq datasets from 11 tumor tissues and two cell lines. We found that the significantly dysregulated SE-associated lncRNAs were strongly correlated with immune cell infiltration through the application of six algorithms (ImmuncellAI, CIBERSORT, EPIC, quantiSeq, TIMER, and xCELL), as well as immunomodulators and chemokines. We found that the expression of SE-associated lncRNA TM4SF1-AS1 was negatively correlated with the proportion of CD8+ T cells present in STAD. TM4SF1-AS1 suppresses T cell-mediated immune killing function and predicts immune response to anti-PD1 therapy. ChIP-seq, Hi-C and luciferase assay results verified that TM4SF1-AS1 was regulated by its super-enhancer. RNA-seq data showed that TM4SF1-AS1 is involved in immune and cancer-related processes or pathways. In conclusion, SE-associated lncRNAs are involved in the tumor immune microenvironment and act as indicators of clinical outcomes in STAD. This study highlights the importance of SE-associated lncRNAs in the immune regulation of STAD.

LINC02308 promotes the progression of glioma through activating mTOR/AKT-signaling pathway by targeting miR-30e-3p/TM4SF1 axis.

BACKGROUND: Glioma is a common brain malignancy, and the purpose of this study is to investigate the function of LINC02308 in glioma. METHODS: The differentially expressed lncRNAs were screened by microarray. The expression of LINC02308 in glioma tissues and cells was evaluated. The interaction among LINC02308, miR-30e-3p, and TM4SF1 was determined. Cell proliferation and apoptosis were evaluated. The expression of mTOR/AKT-signaling and apoptosis-related markers was detected by Western blot. A xenograft tumor mouse model was constructed to investigate the roles of LINC02308. RESULTS: LINC02308 was significantly overexpressed in glioma, and a high LINC02308 level was correlated with a poor prognosis. LINC02308 silencing markedly inhibited proliferation and reduced apoptosis of glioma cells and also suppressed tumor growth in the xenograft tumor mouse model. Finally, we demonstrated that LINC02308 played its oncogenic role through binding to miR-30e-3p so as to relieve miR-30e-3p-induced suppression of TM4SF1. CONCLUSIONS: LINC02308 promoted glioma tumorigenesis as a sponge of miR-30e-3p to upregulate TM4SF1 and activate AKT/mTOR pathway. Graphical Abstract Hypothesis diagram illustrates the function and mechanism of LINC02308 in glioma. A schematic representation of the functional mechanism of LINC02308 in glioma.

Effect and mechanism of downregulating the long-chain noncoding RNA TM4SF1-AS1 on the proliferation, apoptosis and invasion of gastric cancer cells.

BACKGROUND: To investigate long-chain noncoding TM4SF1-AS1 in gastric cancer (GC) tissues and cells. METHODS: TM4SF1-AS1 in 40 GC tissues and adjacent tissues was detected and compared using real-time fluorescence quantitative PCR (qRT-PCR). TM4SF1-AS1 in MKN28 and SGC7901 GC cells was downregulated using small interfering RNA (shRNA). The cells were grouped into an interference group (shTM4SF1-AS1 group) and a control group (shControl group). MTT and Transwell tests were applied to determine the proliferation and invasion of the cells in both groups, and flow cytometry was performed to assess the apoptosis rate in the two groups. Western blotting was performed to determine changes in key proteins in cells during the epithelial-to-mesenchymal transition (EMT) and in the TM4SF1 and PI3K-AKT signalling pathways in response to the downregulation of TM4SF1-AS1. RESULTS: The proliferation of MKN28 and SGC7901 in the shTM4SF1-AS1 group was significantly inhibited at 48 h and 72 h compared to that in the shControl group (all P < 0.05). In the shTM4SF1-AS1 group, the number of invaded MKN28 and SGC7901 cells was significantly lower than that in the shControl group (all P < 0.05). Apoptosis in the MKN28 and SGC7901 shTM4SF1-AS1 groups was significantly higher than that in the shControl group (all P < 0.05). Compared to those in the shControl group, levels of E-cadherin in EMT-related proteins were significantly elevated (P < 0.01), while levels of N-cadherin, Snail and Twist1 were significantly decreased (all P < 0.01). After silencing the expression of LncTM4SF1-AS1, the expression levels of TM4SF1 in the shTM4SF1-AS1 group were downregulated compared to those in the shControl group, and the p-PI3K and p-AKT proteins in the PI3K-AKT signalling pathway in the shTM4SF1-AS1 group were downregulated compared to those of the shControl group. CONCLUSIONS: TM4SF1-AS1 is upregulated in gastric cancer tissues and cells. Interfering with and downregulating its expression inhibit cancer cell proliferation, invasion and the EMT and promote apoptosis. The underlying mechanism for these effects is related to silencing the TM4SF1 and PI3K-AKT signalling pathways. TM4SF1-AS1 may be a potential therapeutic target for gastric cancer.

HIF-1α-activated TM4SF1-AS1 promotes the proliferation, migration, and invasion of hepatocellular carcinoma cells by enhancing TM4SF1 expression.

Long non-coding RNAs (lncRNAs) are essential drivers or suppressors in human hepatocellular carcinoma (HCC) by participating in controlling transcription, translation, mRNA stability, and protein degradation protein-protein interaction. TM4SF1-AS1 is recently identified as a tumor-promoting factor in lung cancer. Nevertheless, its function in HCC and related molecular mechanisms remain unknown. Here, our data indicated that either hypoxia or hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor (DMOG) induced the upregulation of TM4SF1-AS1 in HCC cells. HIF-1α knockdown rather than HIF-2α silencing remarkably abrogated hypoxia-upregulated TM4SF1-AS1 expression. Furthermore, we confirmed the elevated expression of TM4SF1-AS1 in HCC tissue samples and cell lines. The silencing of TM4SF1-AS1 prominently inhibited the proliferative, migratory, and invasive abilities of HCC cells. TM4SF1-AS1 depletion significantly blocked hypoxia-enhanced Hep3B cell proliferation and mobility. Interfering TM4SF1-AS1 remarkably reduced TM4SF1 mRNA and protein levels in HCC cells. But TM4SF1-AS1 knockdown did not impact the stability of TM4SF1 mRNA. Hypoxia enhanced the expression of TM4SF1 mRNA, which was subsequently decreased by TM4SF1-AS1 knockdown in HCC cells. We confirmed the positive correlation between TM4SF1 mRNA and TM4SF1-AS1 expression in HCC specimens. Finally, TM4SF1 prominently reversed the inhibitory role of TM4SF1-AS1 depletion in Hep3B cells. In summary, hypoxia-responsive TM4SF1-AS1 was overexpressed in human HCC and contributed to the malignant behaviors of tumor cells by enhancing TM4SF1-AS1 expression.

TM4SF1, a binding protein of DVL2 in hepatocellular carcinoma, positively regulates beta-catenin/TCF signalling.

The interaction between Axin and DVL2 is critical for the breaking down of the beta-catenin destruction complex and the activation of the Wnt/beta-catenin cascade. However, this biological process remains poorly understood. In the present study, TM4SF1 was identified as the interacting partner of DVL2 and positively regulated as Wnt/beta-catenin signalling by strengthening the DVL2-Axin interaction. The expression levels of TM4SF1 were elevated in hepatocellular carcinoma (HCC) and were induced by Kras signalling. The overexpression of TM4SF1 promoted the growth and motility of HCC cells, and up-regulated the target genes (Axin2 and cyclin D1). The down-regulation of TM4SF1 impaired the capability of HCC cells for growth, migration and metastasis. In addition, the down-regulation of TM4SF1 promoted the ubiquitination of beta-catenin. In summary, these results reveal the oncogenic functions of TM4SF1 in HCC progression and suggest that TM4SF1 might be a target for treatment.

TM4SF1 promotes EMT and cancer stemness via the Wnt/ß-catenin/SOX2 pathway in colorectal cancer.

BACKGROUND: Transmembrane 4 L six family member 1 (TM4SF1) is upregulated in several epithelial cancers and is closely associated with poor prognosis. However, the role of TM4SF1 and its potential mechanism in colorectal cancer (CRC) remain elusive. METHODS: We investigated the expression of TM4SF1 in the Oncomine, the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and confirmed the results by immunohistochemistry (IHC), qPCR and Western blotting (WB) of CRC tissues. The effect of TM4SF1 on the epithelial-to-mesenchymal transition (EMT) and cancer stemness of CRC cells was investigated by Transwell, wound healing and sphere formation assays. A series of in vitro and in vivo experiments were conducted to reveal the mechanisms by which TM4SF1 modulates EMT and cancer stemness in CRC. RESULTS: TM4SF1 expression was markedly higher in CRC tissues than in non-tumour tissues and was positively correlated with poor prognosis. Downregulation of TM4SF1 inhibited the migration, invasion and tumour sphere formation of SW480 and LoVo cells. Conversely, TM4SF1 overexpression significantly enhanced the migration, invasion and tumoursphere formation potential of CRC cells, Additionally, TM4SF1 silencing inhibited the EMT mediated by transforming growth factor-ß1 (TGF-ß1). Mechanistically, gene set enrichment analysis (GSEA) predicted that the Wnt signalling pathway was one of the most impaired pathways in TM4SF1-deficient CRC cells compared to controls. The results were further validated by WB, which revealed that TM4SF1 modulated SOX2 expression in a Wnt/ß-catenin activation-dependent manner. Furthermore, we found that knockdown of TM4SF1 suppressed the expression of c-Myc, leading to decreased c-Myc binding to the SOX2 gene promoter. Finally, depletion of TM4SF1 inhibited metastasis and tumour growth in a xenograft mouse model. CONCLUSION: Our study substantiates a novel mechanism by which TM4SF1 maintains cancer cell stemness and EMT via the Wnt/ß-catenin/c-Myc/SOX2 axis during the recurrence and metastasis of CRC.

Role of Transmembrane 4 L Six Family 1 in the Development and Progression of Cancer.

Transmembrane 4 L six family 1 (TM4SF1) is a protein with four transmembrane domains that belongs to the transmembrane 4 L six family members (TM4SFs). Structurally, TM4SF1 consists of four transmembrane domains (TM1-4), N- and C-terminal intracellular domains, two extracellular domains, a smaller domain between TM1 and TM2, and a larger domain between TM3 and TM4. Within the cell, TM4SF1 is located at the cell surface where it transmits extracellular signals into the cytoplasm. TM4SF1 interacts with tetraspanins, integrin, receptor tyrosine kinases, and other proteins to form tetraspanin-enriched microdomains. This interaction affects the pro-migratory activity of the cells, and thus it plays important roles in the development and progression of cancer. TM4SF1 has been shown to be overexpressed in many malignant tumors, including gliomas; malignant melanomas; and liver, prostate, breast, pancreatic, bladder, colon, lung, gastric, ovarian, and thyroid cancers. TM4SF1 promotes the migration and invasion of cancer cells by inducing epithelial-mesenchymal transition, self-renewal ability, tumor angiogenesis, invadopodia formation, and regulating the related signaling pathway. TM4SF1 is an independent prognostic indicator and biomarker in several cancers. It also promotes drug resistance, which is a major cause of therapeutic failure. These characteristics make TM4SF1 an attractive target for antibody-based immunotherapy. Here, we review the many functions of TM4SF1 in malignant tumors, with the aim to understand the interaction between its expression and the biological behaviors of cancer and to supply a basis for exploring new therapeutic targets.

lncRNA TM4SF1-AS1 Activates the PI3K/AKT Signaling Pathway and Promotes the Migration and Invasion of Lung Cancer Cells.

PURPOSE: Metastasis is a crucial cause of the high mortality in patients with lung cancer. Long non-coding RNAs (lncRNAs) are emerging as important players in the development and progression of human cancers. Here, we aimed to identify metastasis-associated lncRNA and to study its roles in the migration and invasion of lung cancer cells. MATERIALS AND METHODS: We screened differentially expressed lncRNAs between high- and low-metastatic lung cancer cell lines by using microarray and identified the target lncRNA TM4SF1-AS1. The effect of the TM4SF1-AS1 on the invasion and migration was evaluated through the wound healing experiment and transwell assay. The expression of related genes was assessed by RNA sequence and Western blotting. RESULTS: TM4SF1-AS1 was highly expressed in high metastatic lung cancer cell line, and it was also significantly up-regulated in lymph node metastatic lung cancer and was associated with lymph node metastasis. Overexpression of TM4SF1-AS1 promoted the migration and invasion of lung cancer cells. Overexpression of TM4SF1-AS1 decreased the expression of E-Cadherin and increased the expression of Vimentin, Snail and Twist, while knockdown of TM4SF1-AS1 exhibited the opposite trend. Furthermore, RNA sequence analysis revealed that some signaling pathways, including PI3K/AKT signaling pathway, were enriched upon TM4SF1-AS1 overexpression. Western blotting further confirmed that the PI3K/AKT signaling pathway was activated by TM4SF1-AS1. CONCLUSION: This study illustrates that TM4SF1-AS1 promotes the migration and invasion of lung cancer cells by activating the PI3K/AKT signaling pathway. TM4SF1-AS1 might be a novel target of molecular treatment for lung cancer.

Lost miR-141 and upregulated TM4SF1 expressions associate with poor prognosis of pancreatic cancer: regulation of EMT and angiogenesis by miR-141 and TM4SF1 via AKT.

Background: Transmembrane-4-L-six-family-1 (TM4SF1) functions to regulate cell growth and mobility and TM4SF1 expression was upregulated in pancreatic cancer. This study further investigated the role of TM4SF1 in regulating pancreatic cancer epithelial-mesenchymal transition (EMT) and angiogenesis and the underlying molecular events.Methods: Tissue specimens were collected from 90 pancreatic cancer patients for immunohistochemical and qRT-PCR analysis of miR-141 and TM4SF1 levels, respectively. Pancreatic cancer cell lines were used for in vitro assays, while nude mice were used for the in vivo assay.Results: TM4SF1 expression was upregulated, whereas miR-141 expression was lost in pancreatic cancer tissues, both of which was associated with advanced clinicopathological features and poor survival of pancreatic cancer patients. Furthermore, miR-141 was able to target and reduce TM4SF1 expression in pancreatic cancer cells and miR-141 expression inhibited pancreatic cancer cell EMT in vitro and Matrigel plug angiogenesis and lung metastasis in nude mice. At the gene level, miR-141 directly targeted and reduced TM4SF1 expression and in turn induced E-cadherin expression and reduced VEGF-A expression by suppressing activation of the AKT signaling pathway.Conclusions: This study demonstrated that upregulated TM4SF1 and lost miR-141 expression were associated with advanced clinicopathological features and poor survival of pancreatic cancer patients. Lost miR-141 expression but induced TM4SF1 expression altered expression of VEGF-A and E-cadherin and promoted pancreatic cancer cell EMT and angiogenesis via the AKT signaling pathway, suggesting that targeting of miR-141 and TM4SF1 may be a potential therapeutic strategy to control pancreatic cancer.

Endoplasmic reticulum-targeting sequence enhanced the cellular immunity of a tumor-associated antigen L6-based DNA vaccine.

Cancer vaccine design to effectively eliminate tumors requires triggering strong immune reactions to elicit long-lasting humoral and cellular immunity and DNA vaccines have been demonstrated to be an attractive immunotherapeutic approach. The tumor-associated antigen L6 (TAL6) is overexpressed on the surface of different cancer cells and promotes cancer progression; therefore, it could be a potential target for cancer treatment. We have revealed that a synthetic peptide containing HLA-A2-restricted cytotoxic T lymphocyte (CTL) and B cell epitope can induce cellular and humoral immunity against TAL6-expressing cancer. To enhance the efficacy of immunotherapy, in this report, we designed an endoplasmic reticulum (ER)-targeting sequence (adenovirus E3/19K protein) at the N-terminus of TAL6 to facilitate MHC class I antigen presentation to CD8+ T cells. Transfection of mammalian cells with the plasmid containing TAL6 fused with the ER-targeting sequence (pEKL6) resulted in higher levels of TAL6 antigens in the ER than transfection with the full-length TAL6 (pL6). The plasmid pEKL6 induced both TAL6-specific CTL responses and antibody titers after intramuscular (IM) immunization with electroporation and it elicited higher levels of antigen-specific CTLs in HLA-A2 transgenic mice. Immunization with pEKL6 induced higher levels of protective antitumor immunity against tumor growth than pL6 immunization in thymoma and melanoma tumor animal models. Notably, pEKL6 elicited long-term anti-tumor immunity against the recurrence of cancers. We found that CD4+ T, CD8+ T, and NK cells are all important for the effector mechanisms of pEKL6 immunization. Thus, cancer therapy using an ER-targeting sequence linked to a tumor antigen holds promise for treating tumors by triggering strong immune reactions.

MicroRNA-206 inhibits metastasis of triple-negative breast cancer by targeting transmembrane 4 L6 family member 1.

Purpose: Breast cancer (BC) is a common malignancy in women, but the survival rate for BC is not very encouraging. Especially for triple-negative breast cancer (TNBC), a kind of breast cancer that does not have any of the receptors that are commonly found in BC. We investigated the impact of microRNA-206 (miR-206) on transmembrane 4 L6 family member 1 (TM4SF1) in TNBC for therapeutic purpose. Patients and methods: Twenty BC tissues from diagnosed BC patients were analyzed via real-time PCR and Western blotting for expression of TM4SF1 and miR-206. The expression of TM4SF1 was studied in relationship with miR-206 in MDA-MB-231 cells. The biological impact of TM4SF1 and miR-206 on MDA-MB-231 cells and BALB/c nude mice model was studied using proliferation, transwell migration, and invasion assays both in vitro and in vivo. Results: The expression of TM4SF1 in BC tissues was significantly higher than that in adjacent normal breast tissues. In contrast, miR-206 showed a decreased expression level in BC tissues, especially for subtype basal like. Overexpression of miR-206 in MDA-MB-231 cells by transfecting miR-206 resulted in downregulation of TM4SF1. In contrast, knockdown miR-206 expression reversed miR-206-mediated phenotype in MDA-MB-231 cells. Expression level of TM4SF1 in MDA-MB-231 cells was associated with cell migration and invasion capabilities in vitro. Breast tumor burden was correlated with the expression level of TM4SF1 in vivo. Conclusion: Taken together, our results showed the involvement of TM4SF1 in TNBC migration and invasion. miR-206 negatively regulated gene expression of TM4SF1. These findings indicate that miR-206 could be used as a potential therapeutic agent for TNBC.