Transmembrane protein 88 exerts a tumor-inhibitory role in thyroid cancer through restriction of Wnt/β-catenin signaling

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.

Illustrating the biological functions and diagnostic value of transmembrane protein family members in glioma

Background

It is well-established that patients with glioma have a poor prognosis. Although the past few decades have witnessed unprecedented medical advances, the 5-year survival remains dismally low.

Objective

This study aims to investigate the role of transmembrane protein-related genes in the development and prognosis of glioma and provide new insights into the pathogenesis of the disease

Methods

The datasets of glioma patients, including RNA sequencing data and relative clinical information, were obtained from The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA) and Gene Expression Omnibus (GEO) databases. Prognostic transmembrane protein-related genes were identified by univariate Cox analysis. New disease subtypes were recognized based on the consensus clustering method, and their biological uniqueness was verified via various algorithms. The prognosis signature was constructed using the LASSO-Cox regression model, and its predictive power was validated in external datasets by receiver operating characteristic (ROC) curve analysis. An independent prognostic analysis was conducted to evaluate whether the signature could be considered a prognostic factor independent of other variables. A nomogram was constructed in conjunction with traditional clinical variables. The concordance index (C-index) and Decision Curve Analysis (DCA) were used to assess the net clinical benefit of the signature over traditional clinical variables. Seven different softwares were used to compare the differences in immune infiltration between the high- and low-risk groups to explore potential mechanisms of glioma development and prognosis. Hub genes were found using the random forest method, and their expression was based on multiple single-cell datasets.

Results

Four molecular subtypes were identified, among which the C1 group had the worst prognosis. Principal Component Analysis (PCA) results and heatmaps indicated that prognosis-related transmembrane protein genes exhibited differential expression in all four groups. Besides, the microenvironment of the four groups exhibited significant heterogeneity. The 6 gene-based signatures could predict the 1-, 2-, and 3-year overall survival (OS) of glioma patients. The signature could be used as an independent prognosis factor of glioma OS and was superior to traditional clinical variables. More immune cells were infiltrated in the high-risk group, suggesting immune escape. According to our signature, many genes were associated with the content of immune cells, which revealed that transmembrane protein-related genes might influence the development and prognosis of glioma by regulating the immune microenvironment. TMEM158 was identified as the most important gene using the random forest method. The single-cell datasets consistently showed that TMEM158 was expressed in multiple malignant cells.

Conclusion

The expression of transmembrane protein-related genes is closely related to the immune status and prognosis of glioma patients by regulating tumor progression in various ways. The interaction between transmembrane protein-related genes and immunity during glioma development lays the groundwork for future studies on the molecular mechanism and targeted therapy 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.

Downregulation of TMEM220 promotes tumor progression in Hepatocellular Carcinoma

During the process of long-term carcinogenesis, cells accumulate many mutations. Deregulated genes expression causes profound changes in cell proliferation, which is one of the hallmarks of HCC. A comprehensive understanding of these changes will contribute to the molecular mechanism of HCC progression. Through clinical sample analysis, we found that TMEM220 is downregulated in tumor and lower levels of TMEM220 is associated with poor prognosis in HCC patients. Through overexpressing TMEM220 in HCC cell lines, we found that the proliferation of cancer cells was significantly slowed down and metastasis was significantly reduced. For further study of its molecular mechanism, we performed a reverse-phase protein array (RPPA). The results suggest that phenotypic changes caused by TMEM220 in HCC cells might be associated with FOXO and PI3K-Akt pathways. Mechanism studies showed that overexpression of TMEM220 could regulate β-catenin and FOXO3 transcriptional activity by altering their subcellular localization, affecting the expression of downstream gene p21 and SNAIL, and ultimately reducing the progression of HCC. Altogether, our study proposes a working model in which upregulation of TMEM220 expression alters the genes expression involved in cell proliferation, thereby inhibiting HCC progression, which suggests that TMEM220 might serve as a clinical biomarker.

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.