CKLF-like MARVEL Transmembrane Domain-containing Research Articles

Current advancements in PD-L1 modulation by CMTM6 in malignant tumors

Abstract The CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6), a member of the chemokine-like factor superfamily, binds to programmed death-ligand 1 (PD-L1) on the cell membrane, thereby impeding PD-L1’s lysosomal degradation and sustaining its expression. In recent years, extensive studies on PD-L1 have provided insights into its function as an immunepoint inhibitor involved in tumor cell immune evasion. The specific interaction between CMTM6 and PD-L1 suggests a potential role in tumor cell immune evasion and suppression, potentially offering a novel therapeutic target for cancer immunotherapy. Currently, the research on CMTM6 and PD-L1 in diverse tumors and diseases is limited, but their significant roles are indicated. This article provides an overview of the impact of CMTM6 on the immune microenvironment in different types of cancer (such as lung cancer, breast cancer, and liver cancer), and summarizes the effects of CMTM6 on the occurrence and development of various tumors.

CMTM6 mediates the Warburg effect and promotes the liver metastasis of colorectal cancer

Liver metastasis of colorectal cancer (CRC) is a leading cause of death among cancer patients. The overexpression of glucose transporter 1 (Glut1) and enhanced glucose uptake that are associated with the Warburg effect are frequently observed in CRC liver metastases, but the underlying mechanisms remain poorly understood. CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6) regulates the intracellular trafficking of programmed death-ligand-1 (PD-L1); therefore, we investigated whether CMTM6 regulates Glut1 trafficking and the Warburg effect in CRC cells. We found that knocking down of CMTM6 by shRNA induced the lysosomal degradation of Glut1, decreased glucose uptake and glycolysis in CRC cells, and suppressed subcutaneous CRC growth in nude mice and liver metastasis in C57BL/6 mice. Mechanistically, CMTM6 forms a complex with Glut1 and Rab11 in the endosomes of CRC cells, and this complex is required for the Rab11-dependent transport of Glut1 to the plasma membrane and for the protection of Glut1 from lysosomal degradation. Multiomics revealed global transcriptomic changes in CMTM6-knockdown CRC cells that affected the transcriptomes of adjacent cancer-associated fibroblasts from CRC liver metastases. As a result of these transcriptomic changes, CMTM6-knockdown CRC cells exhibited a defect in the G2-to-M phase transition, reduced secretion of 60 cytokines/chemokines, and inability to recruit cancer-associated fibroblasts to support an immunosuppressive CRC liver metastasis microenvironment. Analysis of TCGA data confirmed that CMTM6 expression was increased in CRC patients and that elevated CMTM6 expression was associated with worse patient survival. Together, our data suggest that CMTM6 plays multiple roles in regulating the Warburg effect, transcriptome, and liver metastasis of CRC.

CMTM4 inhibits gastric tumorigenesis and metastasis.

CKLF-like MARVEL transmembrane domain-containing 4 (CMTM4) is involved in immune regulation and tumor progression; however, its role in gastric cancer (GC) remains unclear. This study explored the role and mechanism of CMTM4 in GC. Immunohistochemistry was used to analyze CMTM4 expression in human gastric biopsied cells from patients with GC (N=23) or chronic superficial gastritis (N=23). To investigate the function of CMTM4 in GC cells, the gene CMTM4 was knocked down and overexpressed in human gastric adenocarcinoma cell line AGS. The gene CMTM4 was overexpressed in AGS cells and human gastric cell line SGC7901. Cell Counting Kit 8 (CCK-8) and cell clonogenic assays were used to analyze the proliferation of the GC cells. Flow cytometry was used to analyze the effects of CMTM4 on apoptosis and the cell cycle. Wound healing and transwell assays were used to analyze the migration and invasion of the gastric cells, respectively. The mechanism of CMTM4 in GC cells was explored using the tandem mass tags (TMTs) proteome and verified by western blot analysis. CMTM4 expression was more downregulated in the human GC tissues than the gastritis tissues. CMTM4 overexpression significantly inhibited the proliferation, migration, and invasion of the GC cells, whereas CMTM4 knockdown enhanced gastric cell proliferation (P>0.05), migration (P>0.05), and invasion (P>0.05). Flow cytometry showed that CMTM4 promoted apoptosis and resulted in G1/S arrest in the GC cells. In addition, the proteome and western blot results showed that STAT1 was significantly upregulated, and the STAT1 signaling pathways were enriched in the GC cells overexpressing CMTM4. Our results suggest that CMTM4 plays a tumor-suppressive role in GC and may affect the growth, migration, and invasion of GC cells through the STAT1 signaling pathway. CMTM4 might have potential value as a prognosis marker and potential therapeutic target for GC therapy.

CMTM3 Suppresses Proliferation and Osteogenic Transdifferentiation of C2C12 Myoblasts through p53 Upregulation.

CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3), a member of the CMTM family that is closely related to tumor occurrence and progression, plays crucial roles in the immune system, cardiovascular system, and male reproductive system. Recently, CMTM3 has emerged as a potential target for treating diseases related to bone formation. However, additional studies are needed to understand the mechanisms by which CMTM3 regulates the process of osteogenic differentiation. In this study, we observed a significant downregulation of Cmtm3 expression during the transdifferentiation of C2C12 myoblasts into osteoblasts induced by BMP4. Cmtm3 overexpression suppressed proliferation and osteogenic differentiation in BMP4-induced C2C12 cells, whereas its knockdown conversely facilitated the process. Mechanistically, Cmtm3 overexpression upregulated both the protein and mRNA levels of p53 and p21. Conversely, Cmtm3 knockdown exerted the opposite effects. Additionally, we found that Cmtm3 interacts with p53 and increases protein stability by inhibiting proteasome-mediated ubiquitination and degradation. Notably, Trp53 downregulation abrogated the inhibitory effect of Cmtm3 on BMP4-induced proliferation and osteogenic differentiation of C2C12 myoblasts. Collectively, our findings provide key insights into the role of CMTM3 in regulating myoblast proliferation and transdifferentiation into osteoblasts, highlighting its significance in osteogenesis research.

Molecular and immunological characteristics of patients with CMTM6 low expression colorectal cancer.

CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6), a regulator of programmed cell death ligand 1 (PD-L1), has attracted extensive attention due to its role in tumors. However, research on the expression of CMTM6 in colorectal cancer (CRC) and its relationship with PD-L1 expression and immune cell infiltration is limited. We used The Cancer Genome Atlas database to mine and analyze data from patients with CRC using bioinformatics methods. We investigated the expression of CMTM6 in CRC and its relationship with PD-L1 expression and immune cell infiltration. Immunohistochemistry and PCR were performed to detect CMTM6 and PD-L1 expression in CRC tissues. Differential gene expression analysis was performed using the edgeR package in R and immune cell infiltration analysis was performed using the ssGSEA algorithm. Additionally, GO and KEGG enrichment analyses were conducted to identify the biological processes and pathways associated with low CMTM6 expression. Our study found that CMTM6 expression was significantly upregulated in CRC tissues compared to that in adjacent normal tissues. Patients with high CMTM6 expression exhibited significantly increased levels of PD-L1 expression and higher levels of tumor-infiltrating immune cells compared to patients with low CMTM6 expression. GO and KEGG analyses suggested that CMTM6 may be involved in multiple immune regulatory pathways in CRC.

Loss of the Novel Myelin Protein CMTM5 in Multiple Sclerosis Lesions and Its Involvement in Oligodendroglial Stress Responses.

This study comprehensively addresses the involvement of the protein CKLF-like Marvel transmembrane domain-containing family member 5 (CMTM5) in the context of demyelination and cytodegenerative autoimmune diseases, particularly multiple Sclerosis (MS). An observed reduction in CMTM5 expression in post-mortem MS lesions prompted further investigations in both in vitro and in vivo animal models. In the cuprizone animal model, we detected a decrease in CMTM5 expression in oligodendrocytes that is absent in other members of the CMTM protein family. Our findings also confirm these results in the experimental autoimmune encephalomyelitis (EAE) model with decreased CMTM5 expression in both cerebellum and spinal cord white matter. We also examined the effects of a Cmtm5 knockdown in vitro in the oligodendroglial Oli-neu mouse cell line using the CRISPR interference technique. Interestingly, we found no effects on cell response to thapsigargin-induced endoplasmic reticulum (ER) stress as determined by Atf4 activity, an indicator of cellular stress responses. Overall, these results substantiate previous findings suggesting that CMTM5, rather than contributing to myelin biogenesis, is involved in maintaining axonal integrity. Our study further demonstrates that the knockdown of Cmtm5 in vitro does not modulate oligodendroglial responses to ER stress. These results warrant further investigation into the functional role of CMTM5 during axonal degeneration in the context of demyelinating conditions.

CMTM6 overexpression confers trastuzumab resistance in HER2-positive breast cancer

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer is characterized by invasive growth, rapid metastasis and chemoresistance. Trastuzumab is an effective treatment for HER2+ breast cancer; however, trastuzumab resistance leads to cancer relapse and metastasis. CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6) has been considered as a new immune checkpoint for tumor-induced immunosuppression. The role of CMTM6 in trastuzumab resistance remains unknown. Here, we uncover a role of CMTM6 in trastuzumab-resistant HER2+ breast cancer. CMTM6 expression was upregulated in trastuzumab-resistant HER2+ breast cancer cell. Patients with high CMTM6 expressing HER2+ breast cancer had worse overall and progression-free survival than those with low CMTM6 expression. In vitro, CMTM6 knockdown inhibited the proliferation and migration of HER2+ breast cancer cells, and promoted their apoptosis, while CMTM6 overexpression reversed these effects. CMTM6 and HER2 proteins were co-localized on the surface of breast cancer cells, and CMTM6 silencing reduced HER2 protein levels in breast cancer cells. Co-immunoprecipitation revealed that CMTM6 directly interacted with HER2 in HER2+ breast cancer cells, and CMTM6 overexpression inhibited HER2 ubiquitination. Collectively, these findings highlight that CMTM6 stabilizes HER2 protein, contributing to trastuzumab resistance and implicate CMTM6 as a potential prognostic marker and therapeutic target for overcoming trastuzumab resistance in HER2+ breast cancer.

CMTM7 recognizes an immune-hot tumor microenvironment and predicts therapeutic response of immunotherapy in breast cancer well.

Breast cancer (BRCA) is a complex disease that leads to major mortalities and unsatisfactory clinical outcomes among women worldwide. CKLF-like MARVEL transmembrane domain-containing 7 (CMTM7) is a potential tumor suppressor and regulator of PD-L1, which has been found as a functional signature in considerable oncogenesis, progression, and therapeutic resistance via deletion and downregulation. In this research, triple-negative breast cancer (BRCA), a molecular subtype having a lower response to endocrinotherapy but a higher response to chemotherapy and immunotherapy, showed higher transcriptional levels of CMTM7. Moreover, CMTM7 positively correlated with immunomodulators, tumor-infiltrating immune cells (TIICs), and immune checkpoints in many independent datasets. Furthermore, in an immunotherapy cohort of BRCA, patients with high CMTM7 expression were more sensitive to immunotherapy, and the therapeutic predictive value of CMTM7 is higher than that of PD-1 and PD-L1. To sum up, CMTM7 correlated with an inflamed tumor microenvironment and identified immune-hot tumors, which can be a novel biomarker for the recognition of immunological characteristics and an immunotherapeutic response in BRCA.

New prognostic biomarker CMTM3 in low grade glioma and its immune infiltration.

BackgroundThe CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3) is differentially expressed in a variety of tumors and closely related to tumor occurrence and progression. The expression of CMTM3 was significantly elevated in glioma compared with normal brain tissue, to explore the potential function of CMTM3 in the prognosis and immune infiltration of glioma has certain clinical significance.MethodsThe tumor data in this study were derived from the sequencing data of various tumors in The Cancer Genome Atlas (TCGA) database. Low-grade glioma (LGG) data in the TCGA database include sequencing and clinical data. Clinical data mainly include survival time, survival outcome, age, WHO classification and other information. Sequencing data for normal tissues were obtained from the Genotype Tissue Expression (GTEx) database. Statistical analyses were mainly performed using bioinformatics tools and the corresponding R software (version 3.6.3). The Mann-Whitney U test (Wilcoxon rank sum test) was used to compare the expression differences between the tumor group and the normal group. Survival analysis was conducted using log-rank test to compare whether the overall survival (OS) time was statistically different between the CMTM3 high and low expression groups. The Tumor Immunity Estimation Resource (TIMER) database was used for immune infiltration analysis.ResultsThe results showed that the expression of CMTM3 in World Health Organization (WHO) II and WHO III gliomas was significantly higher than that of normal tissues (P<0.05). Glioma with high CMTM3 expression showed a lower overall survival (OS) (P<0.05). Gene enrichment analysis showed that CMTM3 was significantly enriched in 4 pathways (FDR <0.25, P<0.05). A high correlation was detected between CMTM3 and a variety of immune cells. CMTM3 is highly correlated with macrophages (r=0.536, P=1.31e-36), dendritic cells (r=0.546, P=2.85e-38), CD4+ T cells (r=0.517, P=6.17e-34).ConclusionsThe CMTM3 gene can be used as a potential prognostic marker for WHO grade II and WHO grade III glioma, is related to the immune infiltration in glioma microenvironment, and may became a new immunotherapy target.

PD-L1 promotes myofibroblastic activation of hepatic stellate cells by distinct mechanisms selective for TGF-β receptor I versus II.

SUMMARYIntrahepatic cholangiocarcinoma (ICC) contains abundant myofibroblasts derived from hepatic stellate cells (HSCs) through an activation process mediated by TGF-β. To determine the role of programmed death-ligand 1 (PD-L1) in myofibroblastic activation of HSCs, we disrupted PD-L1 of HSCs by shRNA or anti-PD-L1 antibody. We find that PD-L1, produced by HSCs, is required for HSC activation by stabilizing TGF-β receptors I (TβRI) and II (TβRII). While the extracellular domain of PD-L1 (amino acids 19–238) targets TβRII protein to the plasma membrane and protects it from lysosomal degradation, a C-terminal 260-RLRKGR-265 motif on PD-L1 protects TβRI mRNA from degradation by the RNA exosome complex. PD-L1 is required for HSC expression of tumor-promoting factors, and targeting HSC PD-L1 by shRNA or Cre/loxP recombination suppresses HSC activation and ICC growth in mice. Thus, myofibroblast PD-L1 can modulate the tumor microenvironment and tumor growth by a mechanism independent of immune suppression.

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.

Breast cancer cell-derived extracellular vesicles transfer miR-182-5p and promote breast carcinogenesis via the CMTM7/EGFR/AKT axis

BackgroundExtracellular vesicles (EVs) derived from tumor cells are implicated in the progression of malignancies through the transfer of molecular cargo microRNAs (miRNAs or miRs). We aimed to explore the role of EVs derived from breast cancer cells carrying miR-182-5p in the occurrence and development of breast cancer.MethodsDifferentially expressed miRNAs and their downstream target genes related to breast cancer were screened through GEO and TCGA databases. miR-182-5p expression was examined in cancer tissues and adjacent normal tissues from patients with breast cancer. EVs were isolated from breast cancer cell line MDA-MB-231 cells and identified. The gain- and loss-of function approaches of miR-182-5p and CKLF-like MARVEL transmembrane domain-containing 7 (CMTM7) were performed in MDA-MB-231 cells and the isolated EVs. Human umbilical vein endothelial cells (HUVECs) were subjected to co-culture with MDA-MB-231 cell-derived EVs and biological behaviors were detected by CCK-8 assay, flow cytometry, immunohistochemical staining, Transwell assay and vessel-like tube formation in vitro. A xenograft mouse model in nude mice was established to observe the tumorigenesis and metastasis of breast cancer cells in vivo.ResultsmiR-182-5p was highly expressed in breast cancer tissues and cells, and this high expression was associated with poor prognosis of breast cancer patients. miR-182-5p overexpression was shown to promote tumor angiogenesis in breast cancer. Moreover, our data indicated that miR-182-5p was highly enriched in EVs from MDA-MD-231 cells and then ultimately enhanced the proliferation, migration, and angiogenesis of HUVECs in vitro and in vivo. Moreover, we found that CMTM7 is a target of miR-182-5p. EVs-miR-182-5p promotes tumorigenesis and metastasis of breast cancer cells by regulating the CMTM7/EGFR/AKT signaling axis.ConclusionsTaken altogether, our findings demonstrates that EVs secreted by breast cancer cells could carry miR-182-5p to aggravate breast cancer through downregulating CMTM7 expression and activating the EGFR/AKT signaling pathway.

Prognostic Implications of Pan-Cancer CMTM6 Expression and Its Relationship with the Immune Microenvironment.

CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6) reportedly stabilizes programmed death-ligand 1 (PD-L1) and enhances the efficacy of immunotherapy. However, correlations between CMTM6 expression and the immune microenvironment and its prognostic value remain unknown in a variety of tumors. CMTM6 expression data were obtained from The Cancer Genome Atlas (TCGA) for 33 cancer types classified into high and low expression subgroups according to the median CMTM6 expression value. Pan-cancer analysis of CMTM6 protein expression in 20 tumor types was performed using a cohort from the Human Protein Atlas (HPA). PD-L1 protein expression data were obtained from The Cancer Proteome Atlas (TCPA) for 32 cancer types. Frequencies of CMTM6 copy number alterations and mutations were analyzed using cBioPortal. MANTIS was employed to estimate microsatellite instability in the TCGA cohort. CIBERSORT and the ESTIMATE algorithm were applied to estimate the relative fractions of infiltrating immune cell types and immune scores, respectively. Kaplan–Meier survival curve analysis was performed to assess the pan-cancer prognostic value of CMTM6.CMTM6 is heterogeneously expressed in diverse cancers. Further, the results revealed low CMTM6 mutation frequencies in multiple cancers. Among them, CMTM6 mutation frequency was the highest in uterine cancer. Additionally, CMTM6 expression was related to PD-L1 protein expression in breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, glioblastoma multiforme (GBM), head and neck squamous cell carcinoma, kidney renal papillary cell carcinoma, sarcoma (SARC), stomach adenocarcinoma, and uterine carcinosarcoma. Increased CMTM6 expression may be associated with increased infiltration of neutrophils in some types of cancer. Finally, pan-cancer analysis indicated that CMTM6 expression was closely related to overall survival in adrenocortical carcinoma, GBM, acute myeloid leukemia, liver hepatocellular carcinoma, mesothelioma, SARC, thymoma, and uveal melanoma. Taken together, these findings highlight that CMTM6 plays an important role in the tumor immune microenvironment, and CMTM6 has been identified to have prognostic value in some types of cancers. Thus, CMTM6 is a potential target for cancer immunotherapy and effective prognostic biomarker.

Overexpression of CD168 is related to poor prognosis in oral squamous cell carcinoma.

Receptor for hyaluronic acid (HA)-mediated motility (RHAMM) is also known as CD168. This study proposed to elucidate the prognostic and clinicopathological significance of CD168 expression in oral squamous cell carcinoma (OSCC). Immune staining of a human tissue microarray and Western blot were used to reveal the expression level of CD168 in OSCC. Correlations between clinicopathological indexes and CD168 expression in OSCC patients were assessed. Increased expression of CD168 was detected in OSCC tissues. High expression of CD168 indicated worse survival of patients (p<.05). Furthermore, high expression of CD168 was related to pathological grade in OSCC (p<.05). CD168 expression was positively related to programmed death ligand 1 (PD-L1), CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6), B7 homology 4 protein (B7-H4), CD44, CD133, and Slug expression in OSCC. This study revealed the overexpression of CD168 in OSCC and shed light on the prognostic significance of CD168 expression in OSCC patients.

CMTM8 as an LPA1-associated partner mediates lysophosphatidic acid-induced pancreatic cancer metastasis.

BackgroundLysophosphatidic acid (LPA) is known to promote cancer cell invasiveness through LPA1, but the downstream signaling cascades are still not fully clarified. The CKLF-like MARVEL transmembrane domain-containing (CMTM) family regulates aggressive phenotype in many cancers.MethodsWe performed LPA1 co-immunoprecipitation combined with mass spectrometry to search for LPA1-associated proteins. The role of CMTM8 in mediating the pro-invasive activity of LPA was investigated in pancreatic cancer.ResultsWe identified CMTM8 as an LPA1-interacting protein. LPA1 and CMTM8 were co-localized in pancreatic cancer cells. LPA treatment led to stabilization of CMTM8 protein, which was impaired by knockdown of LPA1. Depletion of CMTM8 significantly suppressed the migration and invasion of pancreatic cancer cells. Conversely, ectopic expression of CMTM8 enhanced the migratory and invasive capacity of pancreatic cancer cells. CMTM8 depletion blocked the formation of metastatic lesions in the lung. Knockdown of CMTM8 attenuated LPA-induced migration and invasion in pancreatic cancer cells. CMTM8 overexpression stimulated β-catenin activation through reduction of GSK3β. In addition, knockdown of β-catenin dramatically antagonized CMTM8-mediated migration and invasion in pancreatic cancer cells.ConclusionsCMTM8 serves as a key mediator of LPA-induced invasiveness in pancreatic cancer. The interaction between CMTM8 and LPA1 leads to activation of oncogenic β-catenin signaling. CMTM8 represents a potential therapeutic target for pancreatic cancer.

Comprehensive analysis of N6-methyladenosine -related long non-coding RNAs and immune cell infiltration in hepatocellular carcinoma

ABSTRACT We aimed to illustrate the influence of N6-methyladenosine (m6A) long non-coding RNAs (lncRNAs) and immune cell infiltration in hepatocellular carcinoma (HCC). The relationship of lncRNAs and m6A was identified through gene expression analysis using PERL and R packages. The Kyoto Encyclopedia of Genes and Genomes gene expression enrichment analysis was performed via gene set enrichment analysis. Lasso regression was utilized to construct prognostic model. Differences in the tumor microenvironment and the immune correlation were analyzed to clarify immune cell infiltration in different clusters and their correlation with the clinical prognosis. Co-expression analysis showed that lncRNA expression was associated closely with m6A. Many lncRNAs were predictive risk factors of prognosis in HCC. m6A-lncRNAs were partially highly expressed in tumor tissue and could be used in a prognostic model to predict HCC prognosis, independent of other clinical characteristics. ‘NOTCH SIGNALING PATHWAY’ was most significantly enriched according to GSEA. CKLF-like MARVEL transmembrane domain-containing member 3 (CMTM3) was overexpressed in tumor tissue. Immune cells, such as activated CD4 memory T cells, CD8 T cells, and follicular helper T cells, highly infiltrated tissues in cluster 2. All related scores were higher in cluster 2, indicating a lower purity of tumor cells and higher density of immune-related cells in the tumor microenvironment. m6A-lncRNAs are closely related to HCC occurrence and progression. Corresponding prognostic models can help predict HCC prognosis. m6A-lncRNAs and the related immune cell infiltration in the tumor microenvironment can provide novel therapeutic targets in HCC that need to be further studied.

MiR-149-5p Regulates Goat Hair Follicle Stem Cell Proliferation and Apoptosis by Targeting the CMTM3/AR Axis During Superior-Quality Brush Hair Formation.

The Yangtze River Delta white goat is a unique goat species that can produce superior quality brush hair. CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3), which influences the transcriptional activity of androgen receptor (AR), was identified as a candidate gene related to superior-quality brush hair formation. CMTM3 is generally expressed at low levels, but miR-149-5p is highly expressed in the skin tissues of these goats. The mechanism by which CMTM3 regulates the proliferation and apoptosis of goat hair follicle stem cells has not been elucidated. Here, RT-qPCR, western blotting, 5-ethynyl-2′-deoxyuridine (EdU), cell cycle, apoptosis, and dual-luciferase assays were used to investigate the role and regulatory mechanism of CMTM3 and miR-149-5p. Functional studies showed that CMTM3 overexpression inhibited proliferation and induced apoptosis in cultured hair follicle stem cells, whereas silencing CMTM3 markedly facilitated cell proliferation and deterred apoptosis in cultured hair follicle stem cells. Then, using bioinformatic predictions and the aforementioned assays, including dual-luciferase assays, RT-qPCR, and western blotting, we confirmed that miR-149-5p targets CMTM3 and preliminarily investigated the interaction between CMTM3 and AR in goat hair follicle stem cells. Furthermore, miR-149-5p overexpression significantly accelerated the proliferation and attenuated the apoptosis of hair follicle stem cells. Conversely, miR-149-5p inhibition suppressed the proliferation and induced the apoptosis of hair follicle stem cells. These results reveal a miR-149-5p-related regulatory framework for the miR-149-5p/CMTM3/AR axis during superior quality brush hair formation, in which CMTM3 plays a negative role.

OSCC cell-secreted exosomal CMTM6 induced M2-like macrophages polarization via ERK1/2 signaling pathway.

CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6) is a critical regulator of tumor immunology among various cancers. However, the role and underlying molecular mechanism of CMTM6 in oral squamous cell carcinoma (OSCC) progression remains unclear. The expression of CMTM6, PD-L1 and CD163 in OSCC tissues were detected by immunohistochemistry on tissue microarray. The effect of CMTM6 knockdown on OSCC cells and macrophage polarization were analyzed by CCK-8 assay, apoptotic assay, would-healing assay, transwell assay and qPCR. OSCC cell derived exosomes were obtained by ultracentrifugation and the mechanistic studies were conducted by qPCR and Western Blot. 4-Nitroquinoline N-oxide (4NQO) induced OSCC mice were used for verifying the effect of CMTM6 downregulation on M2 macrophage infiltration and tumor growth. In OSCC samples, higher CMTM6 expression has been obviously associated with higher pathological stage of OSCC patients, CD163 + macrophages infiltration and PD-L1 expression. CMTM6 knockdown of OSCC cells inhibited proliferative, migrative and invasive abilities of OSCC cells, as well as inhibited M2 macrophage polarization in vitro with downregulating PD-L1 expression. Importantly, exosomes from OSCC cells shuttled CMTM6 to macrophages and promoted M2-like macrophage polarization through activating ERK1/2 signaling. In addition, in 4NQO-induced OSCC mice, CMTM6 level was positively associated with CD163, CD206 and PD-L1 as well as M2-like macrophage infiltration. OSCC cell-secreted exosomal CMTM6 induces M2-like macrophages polarization to promote malignant progression via ERK1/2 signaling pathway, revealing a novel crosstalk between cancer cells and immune cells in OSCC microenvironment.

CMTM5/7 are biomarkers and prognostic factors in human breast carcinoma

The CKLF-like MARVEL transmembrane domain-containing family (CMTM) is the protein product of at least one splice variant of each gene contained a Marvel (MAL and related proteins for vesicle trafficking and membrane link) domain, involved in a variety of cellular processes and the pathogenesis of diseases, including tumorigenesis. However, the diverse expression patterns and prognostic values of eight CMTMs have yet to be elucidated. We analyzed the expressions and impacts on survival of different CMTM factors in BC patients to determine their potential diagnosis and prognosis values in BC. In the current study, we examined the transcriptional and survival data of CMTMs in patients with breast carcinoma (BC) from ONCOMINE, GEPIA, Kaplan-Meier Plotter, and cBioPortal databases. It was found that CMTM5/7 were down-regulated, whereas CMTM1/6 were up-regulated in BC patients compared with the normal tissues. In survival analyses through the Kaplan-Meier plotter database, increased mRNA expressions of CMTM5/6/7 and decreased mRNA expression of CMTM4 were associated with better relapse-free survival (RFS) of BC patients. These data provided CMTM5/7 as new biomarker and prognostic factors in BC.

PD-L1 is induced on the hepatocyte surface via CKLF-like MARVEL transmembrane domain-containing protein 6 up-regulation by the anti-HBV drug Entecavir.

Chronic hepatitis B is now controllable when treated with nucleoside reverse transcriptase inhibitors (NRTIs), which inhibit hepatitis B virus (HBV) replication. However, once the NRTIs are discontinued, most patients relapse, necessitating lifelong NRTIs treatment. HBV infection relapse is assumed to be caused by the persistent existence of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. The mechanism by which cccDNA-positive hepatocytes escape immune surveillance during NRTIs treatment remains elusive. Entecavir (ETV), a commonly used NRTI, post-transcriptionally up-regulates programmed cell death-ligand 1 (PD-L1), an immune checkpoint molecule, on the cell surface of hepatocytes regardless of HBV infection. Up-regulation by ETV depends on up-regulation of CKLF-like MARVEL transmembrane domain-containing 6, a newly identified potent regulator of PD-L1 expression on the cell surface. ETV-treated hepatic cells suppressed the activity of primary CD3 T cells and programmed cell death protein-1 (PD-1)-over-expressed Jurkat cells. Finally, ETV induces PD-L1 in primary hepatocytes infected by HBV. These results provide evidence that ETV considerably up-regulates PD-L1 on the cell surface of infected hepatocytes, which may be one of the mechanisms by which infected hepatocytes subvert immune surveillance.