Chemokine-like factor-like MARVEL transmembrane domain-containing family in autoimmune diseases

CMTM5 influences Hippo/YAP axis to promote ferroptosis in glioma through regulating WWP2-mediated LATS2 ubiquitination

Glioma, a common malignancy, is characterized by high morbidity and mortality. Promoting ferroptosis can delay tumor progression. Here, we aimed to explore the underlying mechanism of ferroptosis in glioma. In vitro and in vivo experiments were conducted using glioma cells and nude mice. The expression of genes and proteins was evaluated by RT-qPCR, Western blot assay, and immunohistochemical staining. Malignant activities of glioma cells were evaluated using MTT, EdU, and Transwell assays. The levels of Fe2+, lipid reactive oxygen species, and malondialdehyde were determined using commercial kits. The interplays among CMTM5, WWP2, and LATS2 were validated using Co-immunoprecipitation assay. The UALCAN database predicted downregulation of CMTM5 expression in glioma, and low expression of CMTM5 was associated with poor survival outcomes. CMTM5 overexpression inhibited cell growth and invasion and promoted ferroptosis of glioma cells. Besides, CMTM5 protein interacted with WWP2 protein and decreased WWP2 expression. WWP2 silencing attenuated LATS2 ubiquitination to enhance LATS2 expression and phosphorylation of YAP1. CMTM5 exerted a suppressive effect on cell growth and invasion and promoted ferroptosis of glioma cells by regulating the WWP2/LATS2 pathway. In the in vivo experiments, CMTM5 overexpression suppressed tumor growth and enhanced ferroptosis. CMTM5 regulated Hippo/YAP signaling to inhibit cell growth and invasion and to promote ferroptosis in glioma by regulating WWP2-mediated LATS2 ubiquitination, thereby attenuating glioma progression.

Cmtm4 deficiency exacerbates colitis by inducing gut dysbiosis and S100a8/9 expression

The dysfunction of innate immunity components is one of the major drivers for ulcerative colitis (UC), and increasing reports indicate that the gut microbiome serves as an intermediate between genetic mutations and UC development. Here, we find that the IL-17 receptor subunit, CMTM4, is reduced in UC patients and dextran sulfate sodium (DSS)-induced colitis. The deletion of CMTM4 (Cmtm4-/-) in mice leads to a higher susceptibility to DSS-induced colitis than in wild-type, and the gut microbiome significantly changes in composition. The causal role of the gut microbiome is confirmed with a cohousing experiment. We further identify that S100a8/9 is significantly up-regulated in Cmtm4-/- colitis, with the block of its receptor RAGE that reverses the phenotype associated with the CMTM4 deficiency. CMTM4 deficiency rather suppresses S100a8/9 expression in vitro via the IL17 pathway, further supporting that the elevation of S100a8/9 in vivo is most likely a result of microbial dysbiosis. Taken together, the results suggest that CMTM4 is involved in the maintenance of intestinal homeostasis, suppression of S100a8/9, and prevention of colitis development. Our study further shows CMTM4 as a crucial innate immunity component, confirming its important role in UC development and providing insights into potential targets for the development of future therapies.

Research advances of MAL family members in tumorigenesis and tumor progression (Review)

The myelin and lymphocyte protein (MAL) family is a novel gene family first identified and characterized in 2002. This family is comprised of seven members, including MAL, MAL2, plasmolipin, MALL, myeloid differentiation‑associated marker (MYADM), MYADML2 and CMTM8, which are located on different chromosomes. In addition to exhibiting extensive activity during transcytosis, the MAL family plays a vital role in the neurological, digestive, respiratory, genitourinary and other physiological systems. Furthermore, the intimate association between MAL and the pathogenesis, progression and metastasis of malignancies, attributable to several mechanisms such as DNA methylation has also been elucidated. In the present review, an overview of the structural and functional properties of the MAL family and the latest research findings regarding the relationship between several MAL members and various cancers is provided. Furthermore, the potential clinical and scientific significance of MAL is discussed and directions for future research are summarized.

The origin, evolution, and molecular diversity of the chemokine system

Chemokine signalling performs key functions in cell migration via chemoattraction, such as attracting leukocytes to the site of infection during host defence. The system consists of a ligand, the chemokine, usually secreted outside the cell, and a chemokine receptor on the surface of a target cell that recognises the ligand. Several noncanonical components interact with the system. These include a variety of molecules that usually share some degree of sequence similarity with canonical components and, in some cases, are known to bind to canonical components and/or to modulate cell migration. Whereas canonical components have been described in vertebrate lineages, the distribution of the noncanonical components is less clear. Uncertainty over the relationships between canonical and noncanonical components hampers our understanding of the evolution of the system. We used phylogenetic methods, including gene-tree to species-tree reconciliation, to untangle the relationships between canonical and noncanonical components, identify gene duplication events, and clarify the origin of the system. We found that unrelated ligand groups independently evolved chemokine-like functions. We found noncanonical ligands outside vertebrates, such as TAFA "chemokines" found in urochordates. In contrast, all receptor groups are vertebrate-specific and all-except ACKR1-originated from a common ancestor in early vertebrates. Both ligand and receptor copy numbers expanded through gene duplication events at the base of jawed vertebrates, with subsequent waves of innovation occurring in bony fish and mammals.

Research insights into the chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTM): their roles in various tumors

The chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing (CMTM) family includes CMTM1-8 and CKLF, and they play key roles in the hematopoietic, immune, cardiovascular, and male reproductive systems, participating in the physiological functions, cancer, and other diseases associated with these systems. CMTM family members activate and chemoattract immune cells to affect the proliferation and invasion of tumor cells through a similar mechanism, the structural characteristics typical of chemokines and transmembrane 4 superfamily (TM4SF). In this review, we discuss each CMTM family member's chromosomal location, involved signaling pathways, expression patterns, and potential roles, and mechanisms of action in pancreatic, breast, gastric and liver cancers. Furthermore, we discuss several clinically applied tumor therapies targeted at the CMTM family, indicating that CMTM family members could be novel immune checkpoints and potential targets effective in tumor treatment.

microRNA-378a-3p plays a regulatory role in trophoblast cell function in preeclampsia by targeting CMTM3

BACKGROUND

Preeclampsia (PE) is a potential multisystemic disease in the middle and late pregnancy. Although its precise etiology and pathogenesis remain unknown, it is a significant cause of morbidity and mortality in both pregnant women and newborns. This study explored the effects of the miR-378a-3p/CKLF-like MARVEL transmembrane domain containing 3 (CMTM3) upon the trophoblast biological functions in PE.

METHODS

The placental pathology of PE were identified by hematoxylin-eosin (HE) staining, and miR-378a-3p expression in placental tissues of PE was verified by RT-qPCR. Trophoblast cells (HTR-8/SVneo and JEG-3) were treated with lipopolysaccharide (LPS), and cell counting kit-8 (CCK-8) assay, flow cytometry, scratch assay, and Transwell assay were carried out to measure cell viability, apoptosis, migratory and invasive capacities, respectively. Western blot was performed to determine the expression levels of the cell migration-related proteins. The binding of miR-378a-3p to CMTM3 was verified through a dual-luciferase reporter gene assay.

RESULTS

miR-378a-3p expression levels were down-regulated in placental tissues and primary trophoblast cells from women with PE compared to the control group. The overexpression of miR-378a-3p promoted the capabilities of LPS-treated trophoblast cells to proliferate, migrate and invade. In contrast, it impeded cell apoptosis, promoted matrix metallopeptidase (MMP)-2 and MMP-9 expression and inhibiting TIMP metallopeptidase inhibitor (TIMP)-1 and TIMP-2 expression. Regarding the molecular mechanism, miR-378a-3p was chosen as the target to modulate the expression level of CMTM3. CMTM3 expression was increased in placental tissues and primary trophoblast cells from women with PE compared to the control group. CMTM3 overexpression could partially neutralize the effects of the overexpressed miR-378a-3p on trophoblast cell function and the expression levels of migration-associated proteins.

CONCLUSION

Our study provides a foundation for miRNA-targeted therapy for preeclampsia by establishing for the first time a potential role for the miR-378a-3p/CMTM3 axis in regulating trophoblast cell activities by altering the expression of migration-related proteins.

Identification of immunodiagnostic blood biomarkers associated with spinal cord injury severity

Blood always shows some immune changes after spinal cord injury (SCI), and detection of such changes in blood may be helpful for diagnosis and treatment of SCI. However, studies to date on blood immune changes after SCI in humans are not comprehensive. Therefore, to obtain the characteristics of blood immune changes and immunodiagnostic blood biomarkers of SCI and its different grades, a human blood transcriptome sequencing dataset was downloaded and analyzed to obtain differentially expressed immune-related genes (DEIGs), related functions and signaling pathways related to SCI and its various grades. Characteristic biomarkers of SCI and its different grades were identified by using weighted gene coexpression network analysis (WGCNA) and least absolute shrinkage and selection operator (LASSO) logistic regression. Expression of biomarkers was verified through experiments. The area under the curve (AUC) of biomarkers was calculated to evaluate their diagnostic value, and differences in immune cell content were examined. In this study, 17 kinds of immune cells with different contents between the SCI group and healthy control (HC) group were identified, with 7 immune cell types being significantly increased. Differences in the content of immune cells between different grades of SCI and the HC group were also discovered. DEIGs were identified, with alteration in some immune-related signaling pathways, vascular endothelial growth factor signaling pathways, and axon guidance signaling pathways. The SCI biomarkers identified and those of American Spinal Injury Society Impairment Scale (AIS) A and AIS D of SCI have certain diagnostic sensitivity. Analysis of the correlation of immune cells and biomarkers showed that biomarkers of SCI, AIS A grade and AIS D grade correlated positively or negatively with some immune cells. CKLF, EDNRB, FCER1G, SORT1, and TNFSF13B can be used as immune biomarkers for SCI. Additionally, GDF11and HSPA1L can be used as biomarkers of SCI AIS A grade; PRKCA and CMTM2 can be used as biomarkers of the SCI AIS D grade. Detecting expression of these putative biomarkers and changes in related immune cells may be helpful for predicting the severity of SCI.

CKLF as a Prognostic Biomarker and Its Association with Immune Infiltration in Hepatocellular Carcinoma

The Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing (CMTM) family, comprising nine members, is involved in the tumorigenesis and progression of various cancers. However, the expression profiles and clinical significance of CMTM family members in hepatocellular carcinoma (HCC) are not fully clarified. In this study, the RNA-sequencing and clinical data were downloaded from The Cancer Genome Atlas (TCGA) databases. The Kaplan–Meier method and the Cox proportional hazards regression analysis were used to evaluate the prognostic significance of CMTM family members. Single-sample gene set enrichment analysis (ssGSEA) and ESTIMATE algorithms were employed to explore the relationship between CMTM family genes and the tumor microenvironment in HCC. Finally, the prognostic CMTM family gene expression was further validated by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical (IHC) staining in clinical HCC tissue specimens. The results indicated that, compared with normal tissues, the expression of CKLF, CMTM1, CMTM3, CMTM4, CMTM7, and CMTM8 were significantly upregulated in HCC, while the expression of CMTM2, CMTM5, and CMTM6 were significantly downregulated in HCC. Univariate and multivariate Cox regression analysis demonstrated that CKLF was an independent prognostic biomarker for the overall survival (OS) of HCC patients. In HCC, the expression of CKLF was found to be correlated with immune cell infiltration, immune-related functions, and immune checkpoint genes. The qRT-PCR and IHC confirmed that CKLF was highly expressed in HCC. Overall, this research suggested that CKLF is involved in immune cell infiltration and may serve as a critical prognostic biomarker, which provides new light on the therapeutics for HCC.

[Advances in the Study of Chemokine-like Factor Superfamily Members in Tumors]

Chemokine-like factor-like MARVEL transmembrane domain containing member/chemokine-like factor superfamily member (CMTM/CKLFSF) including CKLF and CMTM1-CMTM8 are a new family of proteins linking chemokines and transmembrane superfamilies. CMTM not only have broad chemotactic activities, but also associate with hematopoietic system, immune system, and tumor development and metastasis closely. CMTM proteins are involved in key biological processes of cancer development, which include activation and recycling of growth factor receptors, cell proliferation and metastasis, and regulation of the tumor immune microenvironment. This is a new focus of research on the relationship between CMTM and tumors, because CMTM4/CMTM6 can be considered as a regulator for programmed cell death ligand 1 (PD-L1). This paper reviews the role of CMTM family members on cancer, especially in tumor growth, metastasis and immune escape, summarize the latest findings on the relationship between CMTM and non-small cell lung cancer, and explores the potential clinical value of CMTM as a novel drug target or biomarker.
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Identification of prognostic biomarkers in the CMTM family genes of human ovarian cancer through bioinformatics analysis and experimental verification

Background: Ovarian cancer (OV) is one of the most common gynecological malignancies worldwide, and its immunotherapy has considerable prospects. Multiple members of the CMTM family were aberrantly expressed in human cancers and controlled key malignant biological processes and immune regulation in cancer development. However, little is known about the function of this gene family in ovarian cancer, especially in terms of immunity.

Methods: GEPIA, Oncomine, HPA, Kaplan–Meier plotter, cBioPortal, GeneMANIA, and TIMER were used to analyze the differential gene expression, prognostic value, genetic alterations, and alterations in the immune microenvironment of the CMTM family in patients with ovarian cancer. Importantly, RT-qPCR was used to verify the gene expression of the CMTM family.

Results: CMTM1/3/4/6/7/8 showed abnormally high expression at the mRNA and protein levels in OV tissues based on the GEPIA and HPA databases. RT-qPCR showed that CMTM1/6/8 was highly expressed in ovarian cancer cell lines. IHC verified that CMTM8 is highly expressed in ovarian cancer tissues and is closely related to Ki-67. Survival analysis showed that high expression of CMTM1/2/3/5/8 can lead to a significant reduction in overall survival and progression-free survival. There were many types of genetic alterations in the CMTM family. Also, CMTM1/2/3/6 had a certain correlation with the changes in the immune microenvironment such as immune cell infiltration and immune checkpoint expression, which may be the potential mechanism of the CMTM family in ovarian cancer. IHC verified that CMTM6 is highly expressed in ovarian cancer tissues and is closely related to PD-L1.

Conclusion: This study confirmed that the CMTM family has abnormal expression in ovarian cancer and CMTM8 can be used as a biomarker for prognostic evaluation. Also, the CMTM family may be used as a potential target for immunotherapy based on the suppression of immune checkpoints.

Prognostic significance and immune characteristics of CMTM4 in hepatocellular carcinoma

Background

Previous study has shown that chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family member 4 (CMTM4) can bind and maintain programmed cell death ligand 1 (PD-L1) expression to promote tumor progression by alleviating the suppression of tumor-specific T cell activity, suggesting its potential role in tumor immunotherapy. However, the role of CMTM4 in tumor immunity has not been well clarified, especially in hepatocellular carcinoma (HCC).

Methods

The protein expression of CMTM4/PD-L1/CD4/CD8 was detected by immunohistochemistry (IHC) detection in 90 cases of HCC tissues. The mRNA expression profiles and related prognosis data were obtained from The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC). Two immune therapy cohorts were from Imvigor210 and GSE176307.

Results

Though the single protein expression of CMTM4, PD-L1, CD4 or CD8 in HCC tissues by IHC detection didn’t show a significant relationship with the prognosis of HCC patients, we found that high co-expression of CMTM4/PD-L1/CD4 showed a good prognosis of HCC patients. Further Timer 2.0 analysis identified that HCC patients with high expression of CMTM4/PD-L1 and high infiltration of CD4⁺ T cells had a better overall survival than those with low infiltration of CD4⁺ T cells. Moreover, a series of bioinformatics analyses revealed that CMTM4-related genes posed important effects on prognosis and immunity in HCC patients, and CMTM4 had a positive correlation with infiltration of CD4⁺ and CD8⁺ T cells in HCC. At last, we used two immunotherapy cohorts to verify that the combination of CMTM4 with PD-L1 could improve the prognosis of tumor patients underwent immunotherapy.

Conclusions

CMTM4 and PD-L1 co-expression with T cell infiltration shows prognostic significance in HCC, suggesting combined effect from multiple proteins should be considered in HCC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09999-y.

Identification of biomarkers related to neutrophils and two molecular subtypes of systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE), an autoimmune disease with complex pathogenesis, poses a considerable threat to women’s health. Increasing evidence indicates that neutrophils play an important role in the development and progression of lupus.

Methods

Weighted correlation network analysis and single-sample gene set enrichment analysis (GSEA) were used to analyse SLE expression data from a comprehensive gene expression database and identify modules associated with neutrophils. Thereafter, the biomarkers most closely related to neutrophils were identified. We reclassified SLE into two molecular subtypes based on the aforementioned biomarkers and evaluated cell infiltration, molecular mechanisms, and signature pathways in each subtype.

Results

The results showed significant differences in immunological characteristics between the two molecular subtypes of SLE. Hub genes were significantly upregulated in the NEUT-H subtype, and they may be associated with lupus activity. The GSEA revealed associations between our biomarkers and key metabolic pathways.

Conclusions

Our study provides not only a classification for patients with SLE but also new cell and gene targets for immunotherapy, as well as a new experimental paradigm to explore immunotherapy for other autoimmune diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01306-9.

CMTM Family and Gastrointestinal Tract Cancers: A Comprehensive Review

Gastrointestinal tract cancers are a highly heterogeneous group of malignant diseases, contributing significantly to the burden of death worldwide. Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTMs) plays important roles in cancer development and progression. Since the first member was cloned, there have been abundant studies on the relationships between the CMTM family and human cancers. It has been reported that the CMTM family has a large potential prognostic value for multiple cancers. Meanwhile, upregulated or downregulated expression of the family members was related to advanced tumor stage, metastasis, and overall survival. Studies have also reported that these proteins play critical roles in antitumor immunity. We performed a systematic review to sum up the latest advances of CMTM family’ roles in gastrointestinal tract cancers, with a primary focus on hepatocellular carcinoma and gastric carcinoma.

CMTM6 as a master regulator of PD-L1

Immune checkpoint proteins, such as programmed cell death receptor 1 (PD-1) and its ligand (PD-L1), play critical roles in the pathology of chronic inflammatory pathological conditions, particularly cancer. In addition, the activation of PD-1/PD-L1 pathway is involved in mediating resistance to certain anti-cancer chemo- and immuno-therapeutics. Unfortunately, targeting the PD-1/PD-L1 pathway by the available anti-PD-1/PD-L1 drugs can benefit only a small proportion of cancer patients. Thus, studying the factors that regulate the expression of these immune checkpoint proteins is of central importance in this context. Recent investigations have identified CMTM6 and, to a lesser extent, CMTM4, as master regulators of PD-L1 expression in various cancer cells. Understanding the mechanisms by which such proteins upregulate the expression of PD-L1 in tumor cells, and determining the potential regulators of CMTM6 expression in different types of cancers will accelerate the development of new therapeutic targets and/or lead to the enhancement of the currently available PD-1/PD-L1 blockade therapies.

CMTM6 knockdown prevents glioma progression by inactivating the mTOR pathway

Background

Gliomas in the adult brain are complicated and aggressive with a poor prognosis. Gene therapy is a recent alternative glioma treatment. We sought to explore the mechanism of chemokine-like factor (CKLF) MARVEL transmembrane domain-containing 6 (CMTM6) in glioma.

Methods

The Cancer Genome Atlas database reports that CMTM6 is expressed in tumors and glioma tissue. CMTM6 expression in glioma tissues and cells was detected and its relationship with clinical pathology was analyzed. Short hairpin ribonucleic acid-CMTM6 lentivirus was transfected into U87 and U251 cells to evaluate malignant glioma cells. Using the biological website (https://string-db.org/cgi/input.pl?Sessionid) and reference retrieval, the pathway that interacted with CMTM6 and related to glioma was identified. The level of the mammalian target of rapamycin pathway-related proteins was detected. Functional rescue experiments were performed using the combination of mTOR activator MHY1485 and the knockdown CMTM6. The growth of xenograft tumors was observed and Ki67-positive expression was determined.

Results

CMTM6 upregulation in gliomas was associated with a poor prognosis. CMTM6 expression was notably higher in gliomas. After the knockdown of CMTM6, the proliferation, invasion, and migration of U87 and U251 cells were inhibited, and the apoptosis rate was increased. Knocking down CMTM6 inactivated the mTOR pathway. The activation of mTOR pathway reversed the inhibitory effects of CMTM6 knockdown on glioma cell behaviors. CMTM6 knockdown reduced tumor volume, body mass, and Ki67-positive expression.

Conclusions

The knockdown of CMTM6 inhibited the activation of mTOR pathway and prevented the malignant episodes of glioma cells.

CMTM6, a potential immunotherapy target

The CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6), which binds to the programmed death ligand 1 (PD-L1) and stabilizes the expression of PD-L1 on the cell surface, has been recently discovered as a novel regulator of PD-L1 expression in cancer. PD-L1 is an immune checkpoint inhibitory molecule that can mediate the immune escape of tumor cells in various tumors and has been studied intensively in recent years. In 2017, two articles simultaneously reported that CMTM6 can stabilize the expression of PD-L1 on the plasma membrane and prevent PD-L1 from being degraded by lysosomes; therefore, CMTM6 may play an important role in tumor cell immune escape and immunosuppression. At present, there are few studies on the relationship between the expression of CMTM6 and PD-L1 in different tumors and diseases. These studies together suggested that CMTM6 may be a potential novel immunotherapy target. In this review, we briefly describe the latest research progresses of CMTM6 in various cancers and other diseases.

Differential expression of Triggering Receptor Expressed on Myeloid cells 2 (Trem2) in tissue eosinophils

No longer regarded simply as end-stage cytotoxic effectors, eosinophils are now recognized as complex cells with unique phenotypes that develop in response stimuli in the local microenvironment. In our previous study, we documented eosinophil infiltration in damaged muscle characteristic of dystrophin-deficient (mdx) mice that model Duchenne muscular dystrophy. Specifically, we found that eosinophils did not promote the generation of muscle lesions, as these persisted in eosinophil-deficient mdx.PHIL mice. To obtain additional insight into these findings, we performed RNA sequencing of eosinophils isolated from muscle tissue of mdx, IL5tg, and mdx.IL5tg mice. We observed profound up-regulation of classical effector proteins (major basic protein-1, eosinophil peroxidase, and eosinophil-associated ribonucleases) in eosinophils isolated from lesion-free muscle from IL5tg mice. By contrast, we observed significant up-regulation of tissue remodeling genes, including proteases, extracellular matrix components, collagen, and skeletal muscle precursors, as well as the immunomodulatory receptor, Trem2, in eosinophils isolated from skeletal muscle tissue from the dystrophin-deficient mdx mice. Although the anti-inflammatory properties of Trem2 have been described in the monocyte/macrophage lineage, no previous studies have documented its expression in eosinophils. We found that Trem2 was critical for full growth and differentiation of bone marrow-derived eosinophil cultures and full expression of TLR4. Immunoreactive Trem2 was also detected on human peripheral blood eosinophils at levels that correlated with donor body mass index and total leukocyte count. Taken together, our findings provide important insight into the immunomodulatory and remodeling capacity of mouse eosinophils and the flexibility of their gene expression profiles in vivo.

Downregulated CMTM8 Correlates with Poor Prognosis in Gastric Cancer Patients

This study aimed to examine the expression and clinical significance of chemokine-like factor-like MARVEL transmembrane domain-containing family member 8 (CMTM8) in gastric cancer (GC). The mRNA and protein expression of CMTM8 were detected by bioinformatics analysis and immunohistochemistry (IHC), respectively. Bioinformatics analysis found that there was a high mRNA expression of CMTM8 in GC tissues, but failed to identify a significant relationship with the clinicopathological features or prognosis of GC patients. However, IHC results showed that the positive expression of CMTM8 protein in GC tissues was significantly lower than that of adjacent nontumor tissues and correlated with differentiation, tumor node metastasis stage, and distal metastasis of GC patients (p < 0.05). Moreover, the survival time of GC patients with negative CMTM8 protein expression group was shorter than that of positive CMTM8 protein expression group by Kaplan-Meier survival analysis (p < 0.05). Cox proportional hazards model (COX) regression analysis indicated that CMTM8 protein was an independent protective factor for the overall survival of GC patients. Further Gene Set Enrichment Analysis suggested that CMTM8 may be involved in regulating the calcium signaling pathway, cell adhesion molecules, and cytokine-cytokine receptor interaction in GC. Our study shows that CMTM8 protein is downregulated in GC tissues, and CMTM8 protein expression is related to GC metastasis and the prognosis of GC patients.

The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer

The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.

Comprehensive analysis of the prognostic value of the chemokine-like factor-like MARVEL transmembrane domain-containing family in gastric cancer

Background

The chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing (CMTM) family refers to a family of transcriptional repressor genes. CMTMs are closely associated with the epigenetic regulatory mechanisms and development of multiple malignancies, including gastric cancer. However, their specific biological functions and prognostic values in gastric cancer have yet to be elucidated.

Methods

Tumor sample datasets were retrieved and analyzed using databases including Oncomine, STRING, GEPIA2, cBioportal, and Kaplan-Meier plotter. To investigate the prognostic role of CMTMs in gastric cancer, we applied unsupervised hierarchical clustering analysis of CMTM gene expression patterns.

Results

While the mRNA levels of CMTM1/3/6/7/8 were upregulated in gastric cancer, CMTM2/4/5 showed no statistically significant difference at the mRNA level in patients with gastric cancer. Moreover, the mRNA expressions of different CMTMs exhibited strong correlations with various clinical parameters of patients with gastric cancer, including tumor stage, metastatic lymph node status, H. pylori status, and tumor grade. Also, the results suggested that elevated levels of CMTM3/5 mRNA had a significant association (P<0.05) with poor overall survival, progression-free survival, and post-progression survival. Conversely, elevated expression of CMTM2/4/6 mRNA had a significant association with better overall survival, progression-free survival, and post-progression survival. Unsupervised hierarchical clustering analysis successfully identified 2 major clusters of patients as follows: signature #1: CMTM4/6/8 and signature #2: CMTM1/2/3/5/7. Signature #2 was closely correlated with poorer overall survival, which indicated that the expression pattern of the CMTM family could be a novel prognostic factor for patients with gastric cancer.

Conclusions

These results suggest that the expression levels of CMTM genes possibly have prognostic value as a biomarker of gastric cancer.

Possible effects of chemokine-like factor-like MARVEL transmembrane domain-containing family on antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disease defined by thrombotic or obstetrical events and persistent antiphospholipid antibodies (aPLs). Chemokine-like factor-like MARVEL transmembrane domain-containing family (CMTM) is widely expressed in the immune system and may closely related to APS. This review aimed to systematically summarize the possible effects of CMTM on APS. Publications were collected from PubMed and Web of Science databases up to August 2020. CKLF, CKLFSF, CMTM, antiphospholipid syndrome, immune cells, and immune molecules were used as search criteria. Immune cells, including neutrophil, dendritic cells (DCs), T-cells, B-cells, and inflammatory cytokines, play an important role in the development of APS. Chemokine-like factor 1 (CKLF1) has a chemotactic effect on many cells and can affect the expression of inflammatory cytokines and adhesion molecules through the nuclear factor-kB (NF-kB) pathway or mitogen-activated protein kinase (MARK) pathway. CKLF1 can participate in the maturation of DCs, T lymphocyte activation, and the activation of neutrophils through the MAPK pathway. CMTM1 may act on Annexin A2 by regulating Ca²⁺ signaling. CMTM2 and CMTM6 are up-regulated in neutrophils of APS patients. Some CMTM family members influence the activation and accumulation of platelets. CMTM3 and CMTM7 are binding partners of B-cell linker protein (BLNK), thereby linking B cell receptor (BCR) and activating BLNK-mediated signal transduction in B cells. Moreover, CMTM3 and CMTM7 can act on DCs and B-1a cell development, respectively. CMTM may have potential effects on the development of APS by acting on immune cells and immune molecules. Thus, CMTM may act as a novel prognostic factor or immunomodulatory treatment option of APS.

CMTM3 overexpression promotes cell apoptosis while DHT promotes cell proliferation in hair follicle stem cells (HFSCs)

In Yangtze River Delta white goat, hypermethylation of CMTM3 leads to a decreased expression level in high quality brush hair. However, the regulation of CMTM3 expression and its function in hair follicle stem cells (HFSCs) remains largely unknown. In this study, we investigated the regulation of CMTM3 expression, function, and molecular mechanism in HFSCs. The re-expression of CMTM3 significantly suppressed the proliferation of HFSCs by inducing G1 cell cycle arrest and promoting apoptosis. Moreover, the downregulation of CMTM3 promoted HFSC proliferation. Treatment with sh_CMTM3 and incubation in a DHT culture medium had the most significant growth-promoting effect. It was hypothesized that transcriptome analysis using RNA sequencing (RNA-seq) in samples would enable the identification of unique protein-coding and non-coding genes that may help uncover the role of CMTM3. Multiple genes and pathways were involved in this process, including 168 common DEGs, such as CXCL8 and E-selectin, which is reportedly involved in multiple regulatory pathways. These results indicated that CMTM3 can function as HFSCs through the induction of a G1 cell cycle arrest and promoted apoptosis by mediating crosstalk between several pathways and transcription factors. Our data is available in the National Center for Biotechnology Information (NCBI) database with the accession number PRJNA657430.

Chemokine-Like Factor-Like MARVEL Transmembrane Domain-Containing Family in Hepatocellular Carcinoma: Latest Advances

Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTMs) is a new gene family, consisting of CKLF and CMTM1 to CMTM8, which plays an important role in hematopoiesis system, autoimmune diseases, male reproduction etc. Abnormal expression of CMTMs is also associated with tumor genesis, development and metastasis. In this review, we briefly describe the characteristics of CMTM family, outline its functions in multiple kinds of carcinomas, and summarize the latest research on their roles in hepatocellular carcinoma which are mainly related to the expression, prognostic effect, potential functions, and mechanism of action. The CMTM family is expected to provide new ideas and targets for HCC diagnosis and treatment.

CMTM family proteins 1-8: roles in cancer biological processes and potential clinical value

The CKLF-like MARVEL transmembrane domain containing (CMTM) family of genes comprises CKLF and CMTM1–8 (previously called chemokine-like factor superfamily 1–8, CKLFSF1–8). The CMTM family proteins contain a structurally conserved MAL and related proteins for vesicle trafficking and membrane linking (MARVEL) domain. Dysregulated expression of multiple CMTM family members is a common feature in many human cancer types. CMTM proteins control critical biological processes in cancer development, including growth factor receptor activation and recycling, cell proliferation, apoptosis, metastasis, and immune evasion. Emerging in vivo and in vitro evidence indicates that the mechanisms of action of most CMTM proteins are complex and multifactorial. This review highlights new findings regarding the roles of CMTM1–8 in cancer, particularly in tumor growth, metastasis, and immune evasion. Additionally, the potential clinical value of CMTMs as novel drug targets or biomarkers is discussed.