CMTM3 is frequently reduced in clear cell renal cell carcinoma and exhibits tumor suppressor activities

CMTM3 Promotes Colitis-associated Carcinogenesis Via CLTC Stabilization and Modulation of VE-cadherin

BACKGROUND & AIMS

Inflammatory bowel disease leads to increased risk of developing colitis-associated colon cancer (CAC). CMTM3 has a higher methylation level in colon cancer, and accumulating evidence suggests that chemokine-like factor-like MARVEL transmembrane domain-containing member 3 (CMTM3) participates in inflammation and cancer development.

METHODS

We explored the signs of azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced CAC in wild-type (WT) and Cmtm3 deficiency (Cmtm3-/-) mice. Experimental colitis was induced in Cmtm3-/- mice as well as mice with endothelial cell-specific deletion of Cmtm3. Disease phenotypes were investigated by body weight, disease activity index (DAI), colon length, histology, immune cell infiltration, and intestinal permeability. The mechanism was analyzed using bone marrow reconstitution, immunofluorescent staining, Western blot, immunoprecipitation, and pull-down experiments.

RESULTS

We found CMTM3 promoted CAC by aggravating colitis. Further, we revealed endothelial cell-specific deletion of Cmtm3 inhibited the colitis development. In vitro and in vivo mechanistic studies revealed that CMTM3 drove colitis by increasing clathrin-dependent downregulation of vascular endothelial-cadherin, thus causing vascular permeability. We further identified that CMTM3 interacted with clathrin heavy chain and inhibited clathrin heavy chain ubiquitination and proteasome-dependent degradation. Interestingly, Cmtm3 knockout and imatinib mesylate both targeted vascular permeability and had comparable efficacy.

CONCLUSIONS

Our study indicates that CMTM3 promotes CAC by aggravating colitis through causing vascular permeability, providing insights into targets for development of future therapies.

CAFuncAPA: a knowledgebase for systematic functional annotations of APA events in human cancers

Alternative polyadenylation (APA) is a widespread posttranscriptional regulation process. APA generates diverse mRNA isoforms with different 3' UTR lengths, affecting mRNA expression, miRNA binding regulation and alternative splicing events. Previous studies have demonstrated the important roles of APA in tumorigenesis and cancer progression through diverse aspects. Thus, a comprehensive functional landscape of diverse APA events would aid in a better understanding of the underlying mechanisms related to APA in human cancers. Here, we built CAFuncAPA (https://relab.xidian.edu.cn/CAFuncAPA/) to systematically annotate the functions of 15478 APA events in human pan-cancers. Specifically, we first identified APA events associated with cancer survival and tumor progression. We annotated the potential downstream effects of APA on genes/isoforms expression, regulation of miRNAs, RNA binding proteins (RBPs) and alternative splicing events. Moreover, we also identified up-regulators of APA events, including the effects of genetic variants on poly(A) sites and RBPs, as well as the effect of methylation phenotypes on APA events. These findings suggested that CAFuncAPA can be a helpful resource for a better understanding of APA regulators and potential functions in cancer biology.

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.

CMTM3 suppresses chordoma progress through EGFR/STAT3 regulated EMT and TP53 signaling pathway

BACKGROUND

Chordomas are rare, slow-growing and locally aggressive bone sarcomas. At present, chordomas are difficult to manage due to their high recurrence rate, metastasis tendency and poor prognosis. The underlying mechanisms of chordoma tumorigenesis and progression urgently need to be explored to find the effective therapeutic targets. Our previous data demonstrates that EGFR plays important roles in chordoma development and CKLF-like MARVEL transmembrane domain containing (CMTM)3 suppresses gastric cancer metastasis by inhibiting the EGFR/STAT3/EMT signaling pathway. However, the roles and mechanism of CMTM3 in chordomas remain unknown.

METHODS

Primary chordoma tissues and the paired adjacent non-tumor tissues were collected to examine the expression of CMTM3 by western blot. The expression of CMTM3 in chordoma cell lines was tested by Real-time PCR and western blot. CCK-8 and colony forming unit assay were performed to delineate the roles of CMTM3 in cell proliferation. Wound healing and Transwell assays were performed to assess cell migration and invasion abilities. A xenograft model in NSG mice was used to elucidate the function of CMTM3 in vivo. Signaling pathways were analyzed by western blot and IHC. RNA-seq was performed to further explore the mechanism regulated by CMTM3 in chordoma cells.

RESULTS

CMTM3 expression was downregulated in chordoma tissues compared with paired normal tissues. CMTM3 suppressed proliferation, migration and invasion of chordoma cells in vitro and inhibited tumor growth in vivo. CMTM3 accelerated EGFR degradation, suppressed EGFR/STAT3/EMT signaling pathway, upregulated TP53 expression and enriched the TP53 signaling pathway in chordoma cells.

CONCLUSIONS

CMTM3 inhibited tumorigenesis and development of chordomas through activating the TP53 signaling pathway and suppressing the EGFR/STAT3 signaling pathway, which suppressed EMT progression. CMTM3 might be a potential therapeutic target for chordomas.

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.

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.

CMTM3 Overexpression Predicts Poor Survival and Promotes Proliferation and Migration in Pancreatic Cancer

Background: Recent evidence has shown that CKLF-like MARVEL transmembrane domain containing 3 (CMTM3) promoted carcinogenesis and tumor progression in a variety of cancer types. The goal of our study is to investigate the association between CMTM3 and pancreatic cancer (PC). Materials and Methods: In current study, data from public databases was used to analyze CMTM3 expression in PC. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were used to investigate CMTM3 expression and determine its clinical significance in PC. Then CMTM3 promoting PC aggressiveness was demonstrated in vitro experiments by cell proliferation and migration assay. Functional and pathway enrichment analyses were performed to evaluate the potential role of CMTM3 in PC. Results: Results of qRT-PCR and IHC revealed that CMTM3 was significantly overexpressed in PC tissues. High CMTM3 expression was an independent risk factor for poor prognosis of PC patients. Overexpression of CMTM3 was associated with poor overall survival (P-value =0.031) and disease-free survival (P-value =0.0047) in the TCGA cohort. Functional and pathway enrichment analyses showed that CMTM3 were enriched in "Regulation of cell proliferation and regulation of cell differentiation, cell morphogenesis, regulation of cell differentiation, Hedgehog signaling pathway, Wnt signaling pathway, ECM-receptor interaction and pathways in cancer". In PC cell lines, CCK8, clone formation and transwell assays showed that CMTM3 knockdown inhibited cells proliferation and migration. Conclusion: CMTM3 was overexpressed and promotes tumor aggressiveness in PC. Our findings provided a novel therapeutic target for PC.

Bioinformatics-Based Discovery of CKLF-Like MARVEL Transmembrane Member 5 as a Novel Biomarker for Breast Cancer

Chemokine-like factor (CKLF)-like MARVEL transmembrane members (CMTMs) represent a novel protein family linking the chemokine and transmembrane-4 superfamily families, which potentially play several roles in diverse physiological and pathological processes. The detailed functions and underlying molecular mechanisms of CMTMs remain elusive in breast cancer. Herein, we performed a comprehensive bioinformatic analysis to investigate the prognostic effect, potential functions, and biomolecular regulatory network of CMTMs in breast cancer. The mRNA expression level of CMTM5, in particular, was significantly downregulated in breast cancer; moreover, high mRNA expression level of CMTM5 was significantly associated with better relapse-free survival. DNA promoter hypermethylation of CMTM5 was negatively correlated with its mRNA expression levels. Furthermore, CMTM5 strongly associated with pathway in MARVEL domains, chemotaxis, cytokines, transmembrane structures, and integral component of membrane. For example, genes related to MARVEL domains, transmembrane structures, and chemokines were significantly enriched. Our findings indicate that CMTM5 can be used as a prognostic biomarker and potential therapeutic target for breast cancer.

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.

Research Advances in CKLF-like MARVEL Transmembrane Domain-containing Family in Non-small Cell Lung Cancer

CKLF-like MARVEL transmembrane domain-containing member (CMTM) is a new gene family first cloned and reported in 2001. The CMTM family consists of nine members including CKLF and CMTM1-CMTM8, which are located on different chromosomes. Besides exhibiting extensive chemotactic activity, the CMTM family plays an important role in the hematopoiesis system, the immune system, the cardiovascular system and the male reproductive system. Recent in-depth research has also revealed that CMTM is closely associated with the genesis, development and metastasis of tumors, displaying opposing activities in diverse human tumors. In this review, we discuss the structural and functional characteristics of the CMTM family and summarize latest research findings of the relationship between several CMTM members and non-small cell lung cancer.

C5aR1 regulates migration of suppressive myeloid cells required for costimulatory blockade-induced murine allograft survival

Costimulatory blockade-induced murine cardiac allograft survival requires intragraft accumulation of CD11b⁺ Ly6C^lo Ly6G^- regulatory myeloid cells (Mregs) that expand regulatory T cells (Tregs) and suppress effector T cells (Teffs). We previously showed that C5a receptor (C5aR1) signaling on T cells activates Teffs and inhibits Tregs, but whether and/or how C5aR1 affects Mregs required for transplant survival is unknown. Although BALB/c hearts survived >60 days in anti-CD154 (MR1)-treated or cytotoxic T-lymphocyte associated protein 4 (CTLA4)-Ig-treated wild-type (WT) recipients, they were rejected at ~30 days in MR1-treated or CTLA4-Ig-treated recipients selectively deficient in C5aR1 restricted to myeloid cells (C5ar1^fl/fl xLysM-Cre). This accelerated rejection was associated with ~2-fold more donor-reactive T cells and ~40% less expansion of donor-reactive Tregs. Analysis of graft-infiltrating mononuclear cells on posttransplant day 6 revealed fewer Ly6C^lo monocytes in C5ar1^fl/fl xLysM-Cre recipients. Expression profiling of intragraft Ly6C^lo monocytes showed that C5aR1 deficiency downregulated genes related to migration/locomotion without changes in genes associated with suppressive function. Cotransfer of C5ar1^fl/fl and C5ar1^fl/fl xLysM-Cre myeloid cells into MR1-treated allograft recipients resulted in less accumulation of C5ar1^-/- cells within the allografts, and in vitro assays confirmed that Ly6C^hi myeloid cells migrate to C5a/C5aR1-initiated signals. Together, our results newly link myeloid cell-expressed C5aR1 to intragraft accumulation of myeloid cells required for prolongation of heart transplant survival induced by costimulatory blockade.

Expression and Clinical Significance of CMTM6 in Hepatocellular Carcinoma

This study aimed to examine the expression level and clinical significance of chemokine-like factor-like MARVEL transmembrane domain-containing family member 6 (CMTM6) in paired hepatocellular carcinoma (HCC) and adjacent nontumor tissues. The expression of CMTM6 was detected in 75 paired HCC and adjacent nontumor tissues by immunohistochemistry. Chi-square test was used to compare the difference of CMTM6 expression between HCC tissues and adjacent nontumor tissues. The clinic-pathological features and prognosis of HCC patients were collected to analyze the relationship with CMTM6 expression. The positive expression of CMTM6 in HCC tissues was significantly lower than that of adjacent nontumor tissues. The difference of CMTM6 expression between HCC tissues and paired adjacent nontumor tissues was statistically significant (p < 0.05). Furthermore, CMTM6 expression was correlated with HCC metastasis and alpha-fetoprotein (AFP) (p < 0.05). Multivariate logistic regression analysis showed tumor staging, metastasis, and AFP had a significant relationship with CMTM6 expression. In addition, the survival time of HCC patients was different between CMTM6 positive group and CMTM6 negative group by Kaplan-Meier survival analysis (p < 0.05). Downregulation of CMTM6 is related to HCC metastasis and the prognosis of HCC patients.

Knockdown of CMTM3 promotes metastasis of gastric cancer via the STAT3/Twist1/EMT signaling pathway

CMTM3 (CKLF-like MARVEL transmembrane domain containing 3) possesses tumor suppressor properties in multiple types of malignancies. Restoration of CMTM3 significantly inhibits the metastasis of gastric cancer, and its expression level is correlated with prognosis. However, the physiological effects and the mechanism of CMTM3 remain unknown. Here, we suppress CMTM3 expression by shRNA to explore its endogenous effects and its mechanism of action in gastric cancer. Stable knockdown of CMTM3 promotes cell migration, invasion and tumor metastasis, increases MMP2 expression and enhances MMP2 activity. CMTM3 inhibits EMT along with the upregulation of E-cadherin and the downregulation of N-cadherin, Vimentin and Twist1. It has no obvious effects on Zeb1 and Snail. CMTM3 suppresses the phosphorylation of STAT3 but not Akt. More importantly, the EMT phenotype and cell migration induced by CMTM3 knockdown can be reversed by the Jak2/STAT3 inhibitor JSI-124 or by siRNA against STAT3 or Twist1. Overall, this study demonstrates that knockdown of CMTM3 promotes the metastasis of gastric cancer through the STAT3/Twist1/EMT pathway.

miR-135b-5p promotes gastric cancer progression by targeting CMTM3

CKLF-like MARVEL transmembrane domain containing 3 (CMTM3) is considered to be a tumor suppressor gene in multiple types of malignancies. Previous studies have indicated that CMTM3 suppresses metastasis and epithelial-mesenchymal transition (EMT) in gastric cancer. However, its role in gastric cancer cell proliferation has rarely been discussed. Moreover, the regulatory mechanisms of CMTM3 in gastric cancer remain unclear. In this study, RT‑qPCR and IHC were used to assess the expression of CMTM3 and miR‑135b‑5p in gastric cancer tissues and cell lines. We found that the expression of miR‑135b‑5p was negatively associated with CMTM3 in gastric cancer tissues, and we verified that miR‑135b‑5p directly targeted CMTM3 in gastric cancer cells by dual-luciferase reporter assay. CCK8 assay, Transwell assay and flow cytometric analysis were conducted to examine the functions of CMTM3 and miR‑135b‑5p in vitro. Our results demonstrated that the overexpression of CMTM3 or the suppression of miR‑135b‑5p using an inhibitor suppressed SGC‑7901 gastric cancer cell proliferation, invasion and cell cycle progression, and promoted SGC‑7901 cell apoptosis. Furthermore, a BALB/c nude mouse subcutaneous xenograft model was used to verify the function of miR‑135b‑5p and CMTM3. Our results revealed that miR‑135b‑5p inhibitor significantly suppressed SGC‑7901 cell tumorigenesis in vivo. In addition, IHC revealed that CMTM3 expression was markedly increased in tumors infected with miR‑135b‑5p inhibitor lentivirus. On the whole, the findings of the present study suggest that the overexpression of miR‑135b‑5p inhibits CMTM3 expression, and promotes gastric cancer progression and metastasis. Our findings provide a novel therapeutic target for gastric cancer.

Differential Gene Expression Analysis of Bovine Macrophages after Exposure to the Penicillium Mycotoxins Citrinin and/or Ochratoxin A

Mycotoxins produced by fungal species commonly contaminate livestock feedstuffs, jeopardizing their health and diminishing production. Citrinin (CIT) and ochratoxin A (OTA) are mycotoxins produced by Penicillium spp. and commonly co-occur. Both CIT and OTA can modulate immune response by inhibiting cell proliferation and differentiation, altering cell metabolism, and triggering programmed cell death. The objective of this study was to determine the effects of sublethal exposure (i.e., the concentration that inhibited cell proliferation by 25% (IC₂₅)) to CIT, OTA or CIT + OTA on the bovine macrophage transcriptome. Gene expression was determined using the Affymetrix Bovine Genome Array. After 6 h of exposure to CIT, OTA or CIT + OTA, the number of differentially expressed genes (DEG), respectively, was as follows: 1471 genes (822 up-regulated, 649 down-regulated), 5094 genes (2611 up-regulated, 2483 down-regulated) and 7624 genes (3984 up-regulated, 3640 down-regulated). Of these, 179 genes (88 up-regulated, 91 down-regulated) were commonly expressed between treatments. After 24 h of exposure to CIT, OTA or CIT + OTA the number of DEG, respectively, was as follows: 3230 genes (1631 up-regulated, 1599 down-regulated), 8558 genes (4167 up-regulated, 4391 down-regulated), and 10,927 genes (6284 up-regulated, 4643 down-regulated). Of these, 770 genes (247 up-regulated, 523 down-regulated) were commonly expressed between treatments. The categorization of common biological functions and pathway analysis suggests that the IC₂₅ of both CIT and OTA, or their combination, induces cellular oxidative stress, a slowing of cell cycle progression, and apoptosis. Collectively, these effects contribute to inhibiting bovine macrophage proliferation.

CMTM5 inhibits renal cancer cell growth through inducing cell-cycle arrest and apoptosis

CKLF-like MARVEL transmembrane domain-containing 5 (CMTM5) has been reported to function as a potential tumor suppressor in several human cancers. However, the involvement of CMTM5 in human renal cell carcinoma (RCC) remains unclear. The current study aimed to detect its expression pattern in RCC tissues and cells, and to determine its anti-proliferative functions in this malignancy. The mRNA and protein expression levels of CMTM5 in RCC tissues and cells were detected by reverse transcription-quantitative polymerase chain reaction, immunohistochemistry and western blotting. Following the transfection with CMTM5 lentivirus or control lenti-EGFP lentivirus into the RCC cell line ACHN, the viability, migration, apoptosis and cell cycle of these cells were detected by Cell Counting kit-8 assay, Transwell assay and flow cytometry, respectively. Compared with the adjacent non-malignant kidney tissue samples, CMTM5 expression was significantly downregulated in RCC tissues (P<0.05). In addition, enforced expression of CMTM5 could efficiently inhibit the cell growth of ACHN cells, which were arrested in G0/G1 phase. Furthermore, the migration and invasion of ACHN cells were also inhibited by restoration of CMTM5 expression. The present data suggest that CMTM5 may function as a tumor suppressor in human RCC by suppressing the viability of RCC cells, implying its potential as a therapeutic target for this malignancy.

Chemokine-like factor-like MARVEL transmembrane domain-containing 3 expression is associated with a favorable prognosis in esophageal squamous cell carcinoma

Decreased expression of human chemokine-like factor-like MARVEL transmembrane domain-containing 3 (CMTM3) has been identified in a number of human tumors and tumor cell lines, including gastric and testicular cancer, and PC3, CAL27 and Tca-83 cell lines. However, the association between CMTM3 expression and the clinicopathological features and prognosis of esophageal squamous cell carcinoma (ESCC) patients remains unclear. The aim of the present study was to investigate the correlation between CMTM3 expression and clinicopathological parameters and prognosis in ESCC. CMTM3 mRNA and protein expression was analyzed in ESCC and paired non-tumor tissues by quantitative real-time polymerase chain reaction, western blotting and immunohistochemical analysis. The Kaplan-Meier method was used to plot survival curves and the Cox proportional hazards regression model was also used for univariate and multivariate survival analysis. The results revealed that CMTM3 mRNA and protein expression levels were lower in 82.5% (30/40) and 75% (30/40) of ESCC tissues, respectively, when compared with matched non-tumor tissues. Statistical analysis demonstrated that CMTM3 expression was significantly correlated with lymph node metastasis (P=0.002) and clinical stage (P<0.001) in ESCC tissues. Furthermore, the survival time of ESCC patients exhibiting low CMTM3 expression was significantly shorter than that of ESCC patients exhibiting high CMTM3 expression (P=0.01). In addition, Kaplan-Meier survival analysis revealed that the overall survival time of patients exhibiting low CMTM3 expression was significantly decreased compared with patients exhibiting high CMTM3 expression (P=0.010). Cox multivariate analysis indicated that CMTM3 protein expression was an independent prognostic predictor for ESCC after resection. This study indicated that CMTM3 expression is significantly decreased in ESCC tissues and CMTM3 protein expression in resected tumors may present an effective prognostic biomarker.

CKLF-Like MARVEL Transmembrane Domain-Containing Member 3 (CMTM3) Inhibits the Proliferation and Tumorigenisis in Hepatocellular Carcinoma Cells

The CKLF-like MARVEL transmembrane domain-containing 3 (CMTM3), a member of the CMTM family, was found in several human tumors and plays an important role in the development and progression of tumors. However, the role of CMTM3 in hepatocellular carcinoma (HCC) remains largely unknown. Thus, in the present study, we explored its expression pattern in human HCC cell lines, as well as its functions in HCC cells. Our results demonstrated that the expression of CMTM3 is lowly expressed in HCC cell lines. In vitro, we found that overexpression of CMTM3 obviously inhibited the proliferation, invasion, and EMT process in HCC cells. Furthermore, overexpression of CMTM3 significantly downregulated the expression levels of phosphorylation of JAK2 and STAT3 in HepG2 cells. In vivo, overexpression of CMTM3 attenuated the tumor growth in Balb/c nude mice. In conclusion, we demonstrated that CMTM3 could play an important role in HCC metastasis by EMT induction via, at least partially, suppressing the JAK2/STAT3 signaling pathway. Therefore, CMTM3 may serve as a potential molecular target in the prevention and/or treatment of HCC invasion and metastasis.

The Role of Chromosomal Instability and Epigenetics in Colorectal Cancers Lacking β-Catenin/TCF Regulated Transcription

All colorectal cancer cell lines except RKO displayed active β-catenin/TCF regulated transcription. This feature of RKO was noted in familial colon cancers; hence our aim was to dissect its carcinogenic mechanism. MFISH and CGH revealed distinct instability of chromosome structure in RKO. Gene expression microarray of RKO versus 7 colon cancer lines (with active Wnt signaling) and 3 normal specimens revealed 611 differentially expressed genes. The majority of the tested gene loci were susceptible to LOH in primary tumors with various β-catenin localizations as a surrogate marker for β-catenin activation. The immunohistochemistry of selected genes (IFI16, RGS4, MCTP1, DGKI, OBCAM/OPCML, and GLIPR1) confirmed that they were differentially expressed in clinical specimens. Since epigenetic mechanisms can contribute to expression changes, selected target genes were evaluated for promoter methylation in patient specimens from sporadic and hereditary colorectal cancers. CMTM3, DGKI, and OPCML were frequently hypermethylated in both groups, whereas KLK10, EPCAM, and DLC1 displayed subgroup specificity. The overall fraction of hypermethylated genes was higher in tumors with membranous β-catenin. We identified novel genes in colorectal carcinogenesis that might be useful in personalized tumor profiling. Tumors with inactive Wnt signaling are a heterogeneous group displaying interaction of chromosomal instability, Wnt signaling, and epigenetics.

CMTM8 inhibits the carcinogenesis and progression of bladder cancer

Bladder cancer is the most common tumor of the urinary tract. The incidence of bladder cancer has increased in the last few decades, thus novel molecular markers for early diagnosis and more efficacious treatment are urgently needed. Chemokine‑like factor (CKLF)‑like MARVEL transmembrane domain containing 8 (CMTM8) is downregulated in several types of cancers and is associated with tumor progression. However, CMTM8 expression has been unexplored in bladder cancer to date. Our results revealed that the expression of CMTM8 was negative in 46 of 74 (62.2%) bladder cancer samples via immunohistochemistry assay. CMTM8 downregulation was associated with advancing tumor stage and tumor grade. CMTM8 was successfully overexpressed by lentivirus in EJ and T24 cells, and the CCK‑8 and Transwell assays showed that CMTM8 overexpression decreased cell proliferation, migration and invasion in vitro. In tumor xenografts upregulation of CMTM8 inhibited tumor growth and lymph node metastasis in vivo. In conclusion, overexpression of CMTM8 in bladder cancer results in reduced malignant cell growth, migration and invasion, which could make it a potential therapeutic target in the treatment of bladder cancer.

Systematic investigation of CMTM family genes suggests relevance to glioblastoma pathogenesis and CMTM1 and CMTM3 as priority targets

The novel CKLF-like Marvel Transmembrane Domain-containing gene family (CMTM) consists of 8 members (CMTM1-8). As little is known about the oncogenic impact of these genes, we aimed to systematically investigate the relevance of CMTMs to glioblastoma pathogenesis. We performed mRNA expression analyses and survival correlations in glioblastoma patients. Moreover, we analyzed the impact of RNAi-based silencing and overexpression of CMTM family genes on tumor cell proliferation and invasion in vitro. CMTMs appeared to be widely regulated in the group of glioblastomas relative to non-neoplastic brain (NB) tissue (significant upregulation for CMTM2, 3, and 6 and significant downregulation for CMTM 4 and 8). For CMTM1, 5 and 7, we found aberrant expression levels in individual tumors. Functionally, CMTM1, 3, and 7 promoted tumor cell invasion, while CMTM1 additionally enhanced cell proliferation. In a large clinically annotated dataset, higher CMTM1 and 3 expression was significantly correlated with shorter overall survival. Our data thus suggest CMTM1 and 3 as priority targets in glioblastomas. Using a human phosphokinase protein expression profiling assay, we can provide first insights into signalling of these two genes that might be conveyed by growth factor receptor, Src family kinase and WNT activation.

CMTM3 inhibits human testicular cancer cell growth through inducing cell-cycle arrest and apoptosis

Human CMTM3 has been proposed as a putative tumor suppressor gene. The loss of CMTM3 has been found in several carcinomas. However, the regulation of CMTM3 expression and its function in tumor progression remain largely unknown. Here, we investigated the regulation of CMTM3 expression, function and molecular mechanism in human testicular cancer cells. CMTM3 was frequently downregulated or silenced in testicular cancer cell lines and tumor tissues but highly expressed in normal testis tissues. The re-expression of CMTM3 significantly suppressed the colony formation, proliferation, and migration capacity of testicular cancer cells by inducing a G2 cell cycle arrest and apoptosis. Moreover, the re-expression of CMTM3 activated the transcription of p53, induced p53 accumulation, up-regulated the expression of p21, and increased the cleavage of caspase 9, 8, 3, and PARP. The downregulation of CMTM3 in clinical tumor tissues was associated with the methylation of a single CpG site located within the Sp1/Sp3-responsive region of the core promoter. These results indicate that CMTM3 can function as tumor suppressor through the induction of a G2 cell cycle arrest and apoptosis. CMTM3 is thus involved in testicular cancer pathogenesis, and it is frequently at least partially silenced by the methylation of a single, specific CpG site in tumor tissues.