Cytosolic TMEM88 promotes triple-negative breast cancer by interacting with Dvl

TMEM205 induces TAM/M2 polarization to promote cisplatin resistance in gastric cancer

Cisplatin (DDP) is a basic chemotherapy drug for gastric cancer (GC). With the increase of DDP drug concentration in clinical treatment, cancer cells gradually became resistant. Therefore, it is necessary to find effective therapeutic targets to enhance the sensitivity of GC to DDP. Studies have shown that Transmembrane protein 205 (TMEM205) is overexpressed in DDP-resistant human epidermoid carcinoma cells and correlates with drug resistance, and database analyses show that TMEM 205 is also overexpressed in GC, but its role in cisplatin-resistant gastric cancer remains unclear. In this study, we chose a variety of experiments in vivo and vitro, aiming to investigate the role of TMEM 205 in cisplatin resistance in gastric cancer. The results showed that TMEM 205 promoted proliferation, stemness, epithelial-mesenchymal transition (EMT), migration and angiogenesis of gastric cancer cells through activation of the Wnt/β-catenin signaling pathway. In addition, TMEM205 promotes GC progression by inducing M2 polarization of tumor-associated macrophages (TAMs). These results suggest that TMEM205 may be an effective target to regulate the sensitivity of GC to DDP, providing a new therapeutic direction for clinical treatment.

The transmembrane proteins (TMEM) and their role in cell proliferation, migration, invasion, and epithelial-mesenchymal transition in cancer

Transmembrane proteins (TMEM) are located in the different biological membranes of the cell and have at least one passage through these cellular compartments. TMEM proteins carry out a wide variety of functions necessary to maintain cell homeostasis TMEM165 participates in glycosylation protein, TMEM88 in the development of cardiomyocytes, TMEM45A in epidermal keratinization, and TMEM74 regulating autophagy. However, for many TMEM proteins, their physiological function remains unknown. The role of these proteins is being recently investigated in cancer since transcriptomic and proteomic studies have revealed that exits differential expression of TMEM proteins in different neoplasms concerning cancer-free tissues. Among the cellular processes in which TMEM proteins have been involved in cancer are the promotion or suppression of cell proliferation, epithelial-mesenchymal transition, invasion, migration, intravasation/extravasation, metastasis, modulation of the immune response, and response to antineoplastic drugs. Inclusive data suggests that the participation of TMEM proteins in these cellular events could be carried out through involvement in different cell signaling pathways. However, the exact mechanisms not clear. This review shows a description of the involvement of TMEM proteins that promote or decrease cell proliferation, migration, and invasion in cancer cells, describes those TMEM proteins for which both a tumor suppressor and a tumor promoter role have been identified, depending on the type of cancer in which the protein is expressed. As well as some TMEM proteins involved in chemoresistance. A better characterization of these proteins is required to improve the understanding of the tumors in which their expression and function are altered; in addition to improving the understanding of the role of these proteins in cancer will show those TMEM proteins be potential candidates as biomarkers of response to chemotherapy or prognostic biomarkers or as potential therapeutic targets in cancer.

TMEM196 inhibits lung cancer metastasis by regulating the Wnt/β-catenin signaling pathway

PURPOSE

The TMEM196 protein, which comprises four membrane-spanning domains, belongs to the TMEM protein family. TMEM196 was identified as a candidate tumor suppressor gene in lung cancer. However, its role and mechanism in lung cancer metastasis remain unclear. Here, we study the role of TMEM196 in tumor metastasis to further verify the function in lung cancer.

METHODS

In this study, we used qRT-PCR, western blot analysis and immunohistochemistry to examine the expression levels of TMEM196 and related proteins in lung cancer tissues and tumor cells. We utilized Transwell assays, xenograft nude mouse models, and TMEM196^-/- mouse models to evaluate the effects of TMEM196 on tumor invasion and metastasis. Finally, we used bioinformatics analysis and dual-luciferase reporter gene assays to explore the molecular mechanism of TMEM196 as a tumor suppressor.

RESULTS

We found that TMEM196 mRNA and protein expression levels were significantly decreased in lung cancer tissues and cells. Low expression of TMEM196 in clinical patients was associated with poor prognosis. TMEM196 strongly inhibited tumor metastasis and progression in vitro and in vivo. The primary lung tumors induced by tail vein-inoculated B16 cells in TMEM196^-/- mice were significantly larger than those in TMEM196^+/+ mice. Mechanistically, TMEM196 inhibited the Wnt signaling pathway and repressed β-catenin promoter transcription. TMEM196 silencing in lung cancer cells and mice resulted in significant upregulation of the expression of β-catenin and Wnt signaling pathway downstream target genes (MMP2 and MMP7). Decreasing β-catenin expression in TMEM196-silenced cancer cells attenuated the antimetastatic effect of TMEM196.

CONCLUSIONS

Our results revealed that TMEM196 acts as a novel lung cancer metastasis suppressor via the Wnt/β-catenin signaling pathway.

The new oncogene transmembrane protein 60 is a potential therapeutic target in glioma

Glioma is a malignant tumor with a high fatality rate, originating in the central nervous system. Even after standard treatment, the prognosis remains unsatisfactory, probably due to the lack of effective therapeutic targets. The family of transmembrane proteins (TMEM) is a large family of genes that encode proteins closely related to the malicious behavior of tumors. Thus, it is necessary to explore the molecular and clinical characteristics of newly identified oncogenes, such as transmembrane protein 60 (TMEM60), to develop effective treating options for glioma. We used bioinformatic methods and basic experiments to verify the expression of transmembrane protein 60 in gliomas and its relationship with 1p and 19q (1p19q) status, isocitrate dehydrogenase (IDH) status, patient prognosis, and immune cell infiltration using public databases and clinical samples. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to detect co-expressed genes. Thus, we inhibited the expression of transmembrane protein 60 to observe the proliferation and activity of glioma LN229 cells. We found transmembrane protein 60 was significantly upregulated in glioma compared with that in normal brain tissue at the mRNA. In the subgroups of World Health Organization high grade, isocitrate dehydrogenase wildtype, 1p and 19q non-codeletion, or isocitrate dehydrogenase wild combined with 1p and 19q non-codeletion, the expression of transmembrane protein 60 increased, and the prognosis of glioma patients worsened. In the transmembrane protein 60 high expression group, infiltration of immune cells and stromal cells in the tumor microenvironment increased, tumor purity decreased, and immune cells and pathways were activated. The immune cells mainly included regulatory T-cell, gamma delta T-cell, macrophages M0, neutrophils, and CD8⁺ T-cells. Overexpression of co-inhibitory receptors (CTLA4, PDL1 and CD96) may promote the increase of depletion of T-cell, thus losing the anti-tumor function in the transmembrane protein 60 high expression group. Finally, we found that transmembrane protein 60 silencing weakened the viability, proliferation, and colony formation of glioma LN229 cells. This is the 0 report on the abnormally high expression of transmembrane protein 60 in glioma and its related clinical features, such as tumor microenvironment, immune response, tumor heterogeneity, and patient prognosis. We also found that transmembrane protein 60 silencing weakened the proliferation and colony formation of glioma LN229 cells. Thus, the new oncogene transmembrane protein 60 might be an effective therapeutic target for the clinical treatment of glioma.

Transmembrane protein 88 suppresses hepatocellular carcinoma progression and serves as a novel prognostic factor

Background

Transmembrane protein 88 (TMEM88) is known to be involved in the canonical Wnt signaling pathway and is implicated in several malignancies. However, the expression, function, and prognostic significance of TMEM88 in hepatocellular carcinoma (HCC) remain unclear.

Methods

In this study, we analyzed mRNA levels of TMEM88 in HCC specimens from the TCGA dataset (n=374) to explore the correlation between TMEM88 and HCC. We also overexpressed TMEM88 in the Huh7 human HCC cell line to investigate its tumor-related role in HCC. Additionally, we conducted in vivo experiments using a mouse model to further validate the critical function of TMEM88 in modulating HCC growth.

Results

Our results showed that TMEM88 is negatively correlated with the T stage, TNM stage, and pathological grade of HCC. Higher levels of TMEM88 can help predict better overall survival of HCC in both univariate and multivariate analyses. Similarly, higher TMEM88 is a novel prognostic factor for better disease-specific survival of HCC. Overexpression of TMEM88 in Huh7 cells led to a decreased cell proliferation capacity. Xenograft experiments in a mouse model showed that TMEM88 overexpression can remarkably suppress HCC progression.

Conclusions

Transmembrane protein 88 suppresses HCC growth both in vitro and in vivo, which can act as a potential prognostic factor with clinical application potential.

Targeting TMEM88 as an Attractive Therapeutic Strategy in Malignant Tumors

According to authoritative surveys, the overall morbidity and mortality of malignant tumors show an upward trend, and it is predicted that this trend will not be well contained in the upcoming new period. Since the influencing factors, pathogenesis, and progression characteristics of malignant tumors have not been fully elucidated, the existing treatment strategies, mainly including surgical resection, ablation therapy and chemotherapy, cannot achieve satisfactory results. Therefore, exploring potential therapeutic targets and clarifying their functions and mechanisms in continuous research and practice will provide new ideas and possibilities for the treatment of malignant tumors. Recently, a double-transmembrane protein named transmembrane protein 88 (TMEM88) was reported to regulate changes in downstream effectors by mediating different signaling pathways and was confirmed to be widely involved in cell proliferation, differentiation, apoptosis and tumor progression. At present, abnormal changes in TMEM88 have been found in breast cancer, ovarian cancer, lung cancer, thyroid cancer and other malignant tumors, which has also attracted the attention of tumor research and attempted to clarify its function and mechanism. However, due to the lack of systematic generalization, comprehensive and detailed research results have not been comprehensively summarized. In view of this, this article will describe in detail the changes in TMEM88 in the occurrence and development of malignant tumors, comprehensively summarize the corresponding molecular mechanisms, and explore the potential of targeting TMEM88 in the treatment of malignant tumors to provide valuable candidate targets and promising intervention strategies for the diagnosis and cure of malignant tumors.

TMEM100 negatively regulated by microRNA‑106b facilitates cellular apoptosis by suppressing survivin expression in NSCLC

Non‑small cell lung cancer (NSCLC) is a common malignant tumour. Nevertheless, the 5‑year survival rate of NSCLC patients remains poor. Thus, identifying critical factors involved in regulating the progression of NSCLC is important for providing potential treatment targets. In the present study, it was observed that transmembrane protein 100 (TMEM100) was significantly downregulated in NSCLC tissues compared with paired peritumoral tissues. Decreased TMEM100 expression was associated with poor clinical outcomes in NSCLC patients. Moreover, TMEM100 overexpression inhibited colony formation and facilitated apoptosis by suppressing survivin expression in NSCLC cells, whereas TMEM100 knockdown had the opposite effect. In addition, microRNA (miR)‑106b, a miR with controversial roles in different human cancers, was upregulated in NSCLC and directly downregulated TMEM100 expression. The roles of miR‑106b in cell survival were mitigated by the restoration of TMEM100. The aforementioned results indicated that TMEM100 induced cell apoptosis and inhibited cell survival by serving as a tumour suppressor and that miR‑106b‑mitigatedTMEM100 expression defined a potentially oncogenic pathway in NSCLC.

TMEM88 exhibits an antiproliferative and anti-invasive effect in bladder cancer by downregulating Wnt/β-catenin signaling

Transmembrane protein 88 (TMEM88) acts as a novel tumor-associated protein. The dysregulation of TMEM88 has been observed in several tumor types. However, the relevance of TMEM88 in tumorigenesis is still contradictory. This study assessed the relevance of TMEM88 in bladder cancer. TMEM88 levels were found to be significantly lower in bladder cancer tissue. Upregulation of TMEM88 resulted in a dramatic decrease in the cellular proliferative and invasive abilities of bladder cancer. Upregulation of TMEM88 decreased the level of active β-catenin and prohibited the activation of the Wnt/β-catenin pathway, an effect that was associated with downregulation of glycogen synthase kinase-3β (GSK-3β) phosphorylation. Suppression of GSK-3β or overexpression of β-catenin reversed the TMEM88-induced tumor-inhibiting effects in bladder cancer. Overexpression of TMEM88 prohibited the tumor formation and growth of bladder cancer cells in nude mice. In conclusion, this study demonstrates that TMEM88 exerts an antitumor function in bladder cancer through downregulation of Wnt/β-catenin signaling.

TMEM106C contributes to the malignant characteristics and poor prognosis of hepatocellular carcinoma

Transmembrane protein (TMEM) is a kind of integral membrane protein that spans biological membranes. The functions of most members of the TMEM family are unknown. Here, we conducted bioinformatic analysis and biological validation to investigate the role of TMEM106C in HCC. First, GEPIA and Oncomine^TM were used to analyze TMEM106C expression, which was verified by real-time PCR and western blot analyses. Then, the biological functions of TMEM106C were explored by CCK8 and transwell assays. The prognostic value of TMEM106C was analyzed by UALCAN. LinkedOmics was used to analyze TMEM106C pathways generated by Gene Ontology. A protein-protein interaction network (PPI) was constructed by GeneMANIA. We demonstrated that TMEM106C was overexpressed in HCC and that inhibition of TMEM106C significantly suppressed the proliferation and metastasis of HCC through targeting CENPM and DLC-1. Upregulation of TMEM106C was closely correlated with sex, tumor stage, tumor grade and prognosis. Overexpression of TMEM106C was linked to functional networks involving organelle fission and cell cycle signaling pathways through the regulation of CDK kinases, E2F1 transcription factors and miRNAs. Our data demonstrated that TMEM106C contributes to malignant characteristics and poor prognosis in HCC, which may serve as a prognostic biomarker and potential therapeutic target.

miR-518a-3p Suppresses Triple-Negative Breast Cancer Invasion and Migration Through Regulation of TMEM2

MicroRNAs (miRNAs) are emerging as critical mediators in tumors, including triple-negative breast cancer (TNBC). The role of miR-518a-3p in TNBC was investigated to identify potential therapeutic target. Data from KM Plotter database (www.kmplot.com) showed that high miR-518a-3p expression was significantly associated with overall survival of patients with TNBC (p = 0.04). The expression of miR-518a-3p was dysregulated in TNBC cells. Functional assays revealed that over-expression of miR-518a-3p inhibited cell invasion and migration of TNBC. Additionally, miR-518a-3p could target TMEM2 (transmembrane protein 2), and decreased protein and mRNA expression of TMEM2 in TNBC cells. Knockdown of TMEM2 suppressed cell invasion and migration through inhibiting phospho (p)-JAK1 (Janus kinase 1) and p-STAT (signal transducer and activator of transcription protein) 1/2. Moreover, over-expression of TMEM2 counteracted the suppressive effect of miR-518a-3p on TNBC invasion and migration through promoting the levels of p-JAK1 and p-STAT1/2. In conclusion, miR-518a-3p negatively regulates the JAK/STAT pathway via targeting TMEM2 and suppresses invasion and migration in TNBC, suggesting that miR-518a-3p may be a potential therapeutic target in TNBC.

MicroRNA-708 modulates Hepatic Stellate Cells activation and enhances extracellular matrix accumulation via direct targeting TMEM88

Transmembrane protein 88 (TMEM88) is a potential 2-transmembrane-type protein that interacts with the PDZ domain of Dishevelled-1 (DVL-1), a crucial component of Wnt signalling pathway through its C-terminal Val-Trp-Val (VWV) motif in Xenopus embryo cells. Since the significant function of β-catenin in liver fibrosis, it is urgent to study the TMEM88 mechanism in liver fibrosis. The current research was for evaluating the function of TMEM88 in the process of the liver fibrosis and clarifying the inherent mechanism. The study found that TMEM88 is decreased in human fibrotic liver tissues. Functionally, TMEM88 significantly reduced the expression levels of α-smooth muscle actin (α-SMA) and collagen type I (Col.I) and repressed extracellular matrix (ECM) accumulation by restoring the balance between matrix metalloproteinases (MMPs) and TIMPs (tissue inhibitor of metalloproteinases). TMEM88 inhibited HSCs proliferation and evaluated the apoptosis of activated LX-2 cells by regulating Wnt3a, Wnt2b and β-catenin of Wnt/β-catenin signalling pathway. Moreover, we demonstrated that miR-708 particularly targeted TMEM88 3'-UTR regions and down-regulated the expression level of TMEM88 in TGF-β1-stimulated LX-2 cells. MiR-708 promoted the generation of ECM and cell activation in activated LX-2 cells. These results determined that miR-708 could promote HSCs activation and enhance ECM accumulation via direct targeting TMEM88 by Wnt/β-catenin signalling pathway. This will provide a potential target for future research in the process of liver fibrosis.

Transmembrane (TMEM) protein family members: Poorly characterized even if essential for the metastatic process

The majority of cancer-associated deaths are related to secondary tumor formation. This multistep process involves the migration of cancer cells to anatomically distant organs. Metastasis formation relies on cancer cell dissemination and survival in the circulatory system, as well as adaptation to the new tissue notably through genetic and/or epigenetic alterations. A large number of proteins are clearly identified to play a role in the metastatic process but the structures and modes of action of these proteins are essentially unknown or poorly described. In this review, we detail the involvement of members of the transmembrane (TMEM) protein family in the formation of metastases or in the mechanisms leading to cancer cell dissemination such as migration and extra-cellular matrix remodelling. While the phenotype associated with TMEM over or down-expression is clear, the mechanisms by which these proteins allow cancer cell spreading remain, for most of them, unclear. In parallel, the 3D structures of these proteins are presented. Moreover, we proposed that TMEM proteins could be used as prognostic markers in different types of cancers and could represent potential targets for cancer treatment. A better understanding of this heterogeneous family of poorly characterized proteins thus opens perspectives for better cancer patient care.

TMEM88 Inhibits Wnt Signaling by Promoting Wnt Signalosome Localization to Multivesicular Bodies

Wnt/β-catenin signaling is regulated in a bimodal fashion during cardiogenesis. Signaling is initially required to promote generation of precardiac mesoderm, but subsequently must be repressed for cardiac progenitor specification. TMEM88 was discovered recently as a negative regulator during the later phase of cardiac progenitor specification, but how TMEM88 functions was unknown. Based on a C-terminal PDZ-binding motif, TMEM88 was proposed to act by targeting the PDZ domain of Dishevelled, the positive Wnt signaling mediator. However, we discovered that TMEM88 acts downstream of the β-catenin destruction complex and can inhibit Wnt signaling independent of Dishevelled. TMEM88 requires the PDZ-binding motif for trafficking from Golgi to the plasma membrane and is also found in the multivesicular body (MVB) associated with the endocytosed Wnt signalosome. Expression of Tmem88 promotes association of the Wnt signalosome including β-catenin to the MVB, leading to reduced accumulation of nuclear β-catenin and repression of Wnt signaling.

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Human ESCs with a targeted TMEM88 knockout are impaired for cardiac specification

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TMEM88 does not require Dishevelled to inhibit Wnt signaling

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TMEM88 is trafficked from Golgi to plasma membrane and then to the MVB

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Expression of TMEM88 promotes association of the signalosome to the MVB

Molecular and clinical characterization of TMEM71 expression at the transcriptional level in glioma

Background

Glioma is the most common and aggressive type of primary brain tumor in adults. Although radiotherapy and chemotherapy are used in the treatment of glioma, survival remains unsatisfactory. Chemoresistance is one of the primary reasons for the poor prognosis of glioma. Several studies have demonstrated that glioma stem cells (GSC) may be one of the reasons for chemoresistance. In this article, we attempt to search for a new biomarker related to GSC and chemoresistance in glioma.

Methods

We used three datasets (GSE23806, COSMIC, and CGGA) to search for the genes related to GSC, temozolomide (TMZ) resistance, and overall survival. The selected gene was investigated with respect to the relationship between mRNA levels and clinical characteristics in the CGGA and TCGA dataset. Gene ontology (GO) analysis was used for bioinformatics analysis. Kaplan‐Meier survival analysis and Cox regression analysis were used for survival analysis.

Results

The transmembrane protein 71 (TMEM71) gene was selected for further research. TMEM71 was highly expressed in GSCs and TMZ‐resistant cells. The TMEM71 mRNA levels increased with increasing grades of glioma. In IDH‐wild‐type and MGMT‐unmethylated samples, TMEM71 was overexpressed. The TMEM71 transcript levels were also increased significantly in mesenchymal subtype gliomas. GO analysis demonstrated that TMEM71 was related to the immune and inflammatory responses, cell proliferation, cell migration, chemotaxis, and the response to drugs. Specifically, PD‐1, PD‐L1, TIM‐3, and B7‐H3 were tightly associated with TMEM71 expression. This result indicates that TMEM71 may play an important role in the immune response. More importantly, high expression of TMEM71 was correlated with short survival time in both glioma and glioblastoma patients.

Conclusion

In summary, TMEM71 expression was increased in GBM and associated with immune response. Our study suggests that TMEM71 may function as an oncogene and serve as a new effective therapeutic target for the treatment of glioma.

Retracted Article: TMEM88 inhibits fibrosis in renal proximal tubular epithelial cells by suppressing the transforming growth factor-β1/Smad signaling pathway

Transmembrane protein 88 (TMEM88) belongs to a member of the TMEM family, and was reported to be involved in fibrogenesis.

TMEM196 hypermethylation as a novel diagnostic and prognostic biomarker for lung cancer

Emerging evidences have revealed tumor-specific gene methylation is considered to be a promising non-invasive biomarker for many different types of cancers. This study was determined whether TMEM196 gene hypermethylation and downregulation are considered to be promising biomarkers for early diagnosis and prognosis in lung cancer. Methylation status was detected with methylation-specific PCR. Kaplan-Meier survival curves and Cox regression analysis were used to determine the significance of prognosis. TMEM196 gene was hypermethylated in 68.1% (64/94) of lung cancer tissues, 52.8% (67/127) of plasma and 55.2% (79/143) of sputum samples, but unmethylated (0/50) in normal tissues. TMEM196 methylation in plasma and sputum samples was significantly correlated with that in the corresponding paired tumor tissues (r = 0.750, r = 0.880, P < 0.001). TMEM196 aberrant methylation in cancer tissues, plasma and sputum DNA was significantly associated with age and pathological type (P < 0.05). TMEM196 high methylation could robustly distinguish lung cancer patients (AUC = 0.905) from normal subjects and patients with TMEM196 high methylation have a significantly poorer survival than those with low level from The Cancer Genome Atlas (Wilcoxon P < 0.001). Multivariate models showed TMEM196 methylation is an independent prognostic marker in lung cancer. Furthermore, the overall survival of patients with low TMEM196 expression was significantly poorer than that of TMEM196-high patients (P < 0.001, log-rank test). Low TMEM196 expression in tumor tissues was found to predict poorer survival (HR = 3.007; 95%CI, 1.918-4.714). Our study provided new insights into the clinical importance and potential use of TMEM196 methylation and expression as novel early diagnostic and prognostic biomarkers for human lung cancers.

TMEM Proteins in Cancer: A Review

A transmembrane protein (TMEM) is a type of protein that spans biological membranes. Many of them extend through the lipid bilayer of the plasma membrane but others are located to the membrane of organelles. The TMEM family gathers proteins of mostly unknown functions. Many studies showed that TMEM expression can be down- or up-regulated in tumor tissues compared to adjacent healthy tissues. Indeed, some TMEMs such as TMEM48 or TMEM97 are defined as potential prognostic biomarkers for lung cancer. Furthermore, experimental evidence suggests that TMEM proteins can be described as tumor suppressors or oncogenes. TMEMs, such as TMEM45A and TMEM205, have also been implicated in tumor progression and invasion but also in chemoresistance. Thus, a better characterization of these proteins could help to better understand their implication in cancer and to allow the development of improved therapy strategies in the future. This review gives an overview of the implication of TMEM proteins in cancer.

TMEM17 promotes malignant progression of breast cancer via AKT/GSK3β signaling

Purpose

Current knowledge of TMEM17, a recently identified protein of the transmembrane (TMEM) family, is limited, especially with respect to its expression and biological functions in malignant tumors. This study analyzed TMEM17 expression in invasive breast cancer tissue and breast cell lines and its relevance to clinicopathological factors, and investigated the mechanisms underlying the biological effects of TMEM17 on breast cancer cells.

Patients and methods

TMEM17 protein expression was determined in 20 freshly harvested specimens (tumor and paired normal tissues) by Western blotting. Immunohistochemical analysis was performed to determine the expression and subcellular localization of TMEM17 in samples from 167 patients (mean age, 49 years) diagnosed with invasive ductal carcinoma (38 with triple-negative breast cancer; 129 with non-triple-negative breast cancer) who underwent complete resection in the First Affiliated Hospital of China Medical University between 2011 and 2013. Furthermore, TMEM17 was knocked down by small interfering RNAs in breast cancer cell lines.

Results

TMEM17 was found to be significantly upregulated in breast cancer tissues compared to the corresponding normal breast tissues by Western blotting (p=0.015). Immunohistochemical analysis revealed that TMEM was significantly upregulated in invasive breast cancer cells compared to adjacent normal breast duct glandular epithelial cells (10.78% vs 76.05%, p<0.001), and its expression was closely related to the patient’s T-stage (p=0.022), advanced TNM stages (p=0.007), and lymph node metastasis (p=0.012). After TMEM17 knockdown or overexpression in breast cancer cell lines, TMEM17 upregulated p-AKT, p-GSK3β, active β-catenin, and Snail, and downstream target proteins c-myc and cyclin D1, and downregulated E-cadherin, resulting in increased cancer cell proliferation, invasion, and migration. These effects were reversed by the AKT inhibitor LY294002.

Conclusion

Our results indicate that TMEM17 is upregulated in breast cancer tissues and can promote malignant progression of breast cancer cells by activating the AKT/GSK3β signaling pathway.

Cytosolic THUMPD1 promotes breast cancer cells invasion and metastasis via the AKT-GSK3-Snail pathway

Human THUMP domain-containing protein 1 (THUMPD1) is a specific adaptor protein that modulates tRNA acetylation through interaction with NAT10. Immunohistochemical analysis of 146 breast cancer specimens (82 triple-negative and 64 non-triple-negative cases) indicated THUMPD1 expression is higher in breast cancer tissues (60.9%, 89/146) than normal breast tissues (28.3%, 15/53; p < 0.001). Overall and cytosolic, but not nuclear, THUMPD1 expression in breast cancer correlated with advanced TNM stage (p = 0.003 and p < 0.001, respectively), lymph node metastasis (p = 0.001 and p < 0.001, respectively), and poor patient prognosis (p = 0.001 and p < 0.001, respectively). THUMPD1 interacted and co-localized with YAP, but did not affect Hippo pathway activity. THUMPD1 overexpression enhanced breast cancer cells invasion and migration in vivo and in vitro, possibly through activation of AKT, GSK3β and Snail, and inhibition of E-cadherin. Treatment with the AKT inhibitor, LY294002, reduced the effects of THUMPD1 overexpression in breast cancer cells. These results indicate that THUMPD1 promotes breast cancer cells invasion and migration via the AKT-GSK3β-Snail pathway.

TMEM88, CCL14 and CLEC3B as prognostic biomarkers for prognosis and palindromia of human hepatocellular carcinoma

Hepatocellular carcinoma is one of the most mortal and prevalent cancers with increasing incidence worldwide. Elucidating genetic driver genes for prognosis and palindromia of hepatocellular carcinoma helps managing clinical decisions for patients. In this study, the high-throughput RNA sequencing data on platform IlluminaHiSeq of hepatocellular carcinoma were downloaded from The Cancer Genome Atlas with 330 primary hepatocellular carcinoma patient samples. Stable key genes with differential expressions were identified with which Kaplan-Meier survival analysis was performed using Cox proportional hazards test in R language. Driver genes influencing the prognosis of this disease were determined using clustering analysis. Functional analysis of driver genes was performed by literature search and Gene Set Enrichment Analysis. Finally, the selected driver genes were verified using external dataset GSE40873. A total of 5781 stable key genes were identified, including 156 genes definitely related to prognoses of hepatocellular carcinoma. Based on the significant key genes, samples were grouped into five clusters which were further integrated into high- and low-risk classes based on clinical features. TMEM88, CCL14, and CLEC3B were selected as driver genes which clustered high-/low-risk patients successfully (generally, p = 0.0005124445). Finally, survival analysis of the high-/low-risk samples from external database illustrated significant difference with p value 0.0198. In conclusion, TMEM88, CCL14, and CLEC3B genes were stable and available in predicting the survival and palindromia time of hepatocellular carcinoma. These genes could function as potential prognostic genes contributing to improve patients' outcomes and survival.

Potential role and prognostic importance of dishevelled-2 in epithelial ovarian cancer

OBJECTIVE

To investigate the role and prognostic importance of Dvl2 in human epithelial ovarian cancer (EOC).

METHODS

A multimethod study was undertaken including patients with pathologically confirmed non-metastatic EOC who underwent surgery for maximum tumor resection at a center in China. Dvl2 expression was assessed by western blot using fresh EOC tissues and normal ovarian tissues obtained between June 2014 and January 2015. Additionally, retrospective data were obtained for patients treated between April 2004 and September 2009. Their tumor specimens were used in immunohistochemistry analysis. Kaplan-Meier survival plots were constructed to estimate the overall survival by Dvl2 expression, and a Cox proportional hazards model was used to analyze prognostic factors. Alterations in Dvl2 expression during the cell cycle were assessed by a starvation and refeeding assay.

RESULTS

Dvl2 expression was higher in EOC samples than in normal tissues on western blot. Overall, 124 patients were included in immunohistochemistry analysis, and Dvl2 expression level was significantly associated with the tumor grade and Ki-67 expression. Overexpression of Dvl2 was correlated with poor prognosis. The pattern of Dvl2 expression throughout the cell cycle matched that of the cell proliferation marker cyclin D1.

CONCLUSION

Dvl2 could play a part in EOC progression and might be an independent prognostic factor. Additionally, it might be a prospective therapeutic target in the treatment of EOC.

Transmembrane protein 88 (TMEM88) promoter hypomethylation is associated with platinum resistance in ovarian cancer

OBJECTIVES

Epigenetic alterations have been implicated in the development of platinum resistance in ovarian cancer (OC). In this study, we aimed to identify DNA methylation changes in platinum resistant tumors and their functional implications.

METHODS

To identify DNA methylation alterations we used the Illumina 450k DNA methylation array and profiled platinum sensitive and resistant OC xenografts. Validation analyses employed RT-PCR and immunohistochemistry (IHC).

RESULTS

Genome-wide DNA methylation analysis of OC xenografts identified 6 genes (SSH3, SLC12A4, TMEM88, PCDHGC3, DAXX, MEST) whose promoters were significantly hypomethylated in resistant compared to sensitive (control) xenografts (p<0.001). We confirmed that TMEM88 and DAXX mRNA expression levels were increased in platinum resistant compared to control xenografts, inversely correlated with promoter methylation levels. Furthermore treatment of OC cells with SGI-110 (guadecitabine), a DNA methyl transferase (DNMT) inhibitor, increased TMEM88 mRNA expression levels, supporting that TMEM88 is transcriptionally regulated by promoter methylation. TMEM88 was detectable by IHC in all histological types of ovarian tumors and its knock-down by using siRNA promoted OC cell proliferation and colony formation and re-sensitized cells to platinum. Furthermore, TMEM88 knock down induced upregulation of cyclin D1 and c-Myc, known Wnt target genes, supporting that TMEM88 inhibits Wnt signaling.

CONCLUSIONS

Overall, our results support that OC platinum resistance was correlated with TMEM88 overexpression regulated through decreased promoter methylation. Our data suggest that TMEM88 functions as an inhibitor of Wnt signaling, contributing to the development of platinum resistance.