CMTM5 is downregulated and suppresses tumour growth in hepatocellular carcinoma through regulating PI3K-AKT signalling

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.

Current Opinions on the Relationship Between CMTM Family and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a typically malignant tumor in the digestive system. The mortality of HCC ranks third place in the world, second only to lung cancer and colorectal cancer. For the characteristics of high invasiveness, high metastasis, high recurrence rate as well as short survival time, HCC treatment has always been difficult in clinical practice. Many causes have contributed to the appearance of these features, including insidious onset, high degree of malignancy, lack of effective early molecular diagnostic markers, and disease prediction models. The human chemokine-like factor superfamily (CMTMs) is a new gene family consisting of CKLF and CMTM1-CMTM8. CMTMs have a marvel domain which can activate and chemotaxis immune cells. Many studies have reported that CMTMs are involved in the regulation of cell growth and development, and play an important role in the malignant progression of the immune system and reproductive system, especially in the development of tumors. In this review, we summarized the structure and function of the human CMTMs, the relationship between its family members and HCC, the prognostic value, potential functions, and mechanisms in HCC. CMTMs could provide a new diagnostic and therapeutic target in clinical practice for patients with HCC.

A Systems Biology and LASSO-Based Approach to Decipher the Transcriptome-Interactome Signature for Predicting Non-Small Cell Lung Cancer

The lack of precise molecular signatures limits the early diagnosis of non-small cell lung cancer (NSCLC). The present study used gene expression data and interaction networks to develop a highly accurate model with the least absolute shrinkage and selection operator (LASSO) for predicting NSCLC. The differentially expressed genes (DEGs) were identified in NSCLC compared with normal tissues using TCGA and GTEx data. A biological network was constructed using DEGs, and the top 20 upregulated and 20 downregulated hub genes were identified. These hub genes were used to identify signature genes with penalized logistic regression using the LASSO to predict NSCLC. Our model’s development involved the following steps: (i) the dataset was divided into 80% for training (TR) and 20% for testing (TD1); (ii) a LASSO logistic regression analysis was performed on the TR with 10-fold cross-validation and identified a combination of 17 genes as NSCLC predictors, which were used further for development of the LASSO model. The model’s performance was assessed on the TD1 dataset and achieved an accuracy and an area under the curve of the receiver operating characteristics (AUC-ROC) of 0.986 and 0.998, respectively. Furthermore, the performance of the LASSO model was evaluated using three independent NSCLC test datasets (GSE18842, GSE27262, GSE19804) and achieved high accuracy, with an AUC-ROC of >0.99, >0.99, and 0.95, respectively. Based on this study, a web application called NSCLCpred was developed to predict NSCLC.

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.

CMTM Family Genes Affect Prognosis and Modulate Immunocytes Infiltration in Grade II/III Glioma Patients by Influencing the Tumor Immune Landscape and Activating Associated Immunosuppressing Pathways

Lower-grade glioma (LGG) is one of the most common primary tumor types in adults. The chemokine-like factor (CKLF)-like Marvel transmembrane domain-containing (CMTM) family is widely expressed in the immune system and can modulate tumor progression. However, the role of the CMTM family in LGG remains unknown. A total of 508 LGG patients from The Cancer Genome Atlas (TCGA) database were used as a training cohort, and 155 LGG patients from the Chinese Glioma Genome Atlas (CGGA) array database, 142 LGG patients from the CGGA RNA-sequencing database, and 168 LGG patients from the GSE108474 database were used as the validation cohorts. Patients were subdivided into two groups using consensus clustering. The ENET algorithm was applied to build a scoring model based on the cluster model. Finally, ESTIMATE, CIBERSORT, and xCell algorithms were performed to define the tumor immune landscape. The expression levels of the CMTM family genes were associated with glioma grades and isocitrate dehydrogenase (IDH) status. Patients in cluster 2 and the high-risk score group exhibited a poor prognosis and were enriched with higher grade, wild-type IDH (IDH-WT), 1p19q non-codeletion, MGMT promoter unmethylation, and IDH-WT subtype. Patients in cluster 1 and low-risk score group were associated with high tumor purity and reduced immune cell infiltration. Enrichment pathways analysis indicated that several essential pathways involved in tumor progression were associated with the expression of CMTM family genes. Importantly, PD-1, PD-L1, and PD-L2 expression levels were increased in cluster 2 and high-risk groups. Therefore, the CMTM family contributes to LGG progression through modulating tumor immune landscape.

Oncogenic and tumor suppressor genes expression in myeloproliferative neoplasms: The hidden side of a complex pathology

Background

The present study aimed to explore the changes in the expressions of six tumor‐related genes in myeloproliferative neoplasms (MPNs). The study population included 130 patients with MPNs (52 with chronic myeloid leukemia (CML), 49 with essential thrombocythemia (ET), 20 with polycythemia vera (PV), and 9 with primary myelofibrosis (PMF)) and 51 healthy individuals.

Methods

The expression profiling of six genes (ADAMTS18, CMTM5, CDKN2B, DCC, FHIT, and WNT5B) in the peripheral blood granulocyte cells was explored by real‐time quantitative reverse transcription polymerase chain reaction.

Results

The patients with MPNs showed significant downregulation of CMTM5 (EFC = 0.66) and DCC (EFC = 0.65) genes in contrast to a non‐significant upregulation of ADAMTS18, CDKN2B, FHIT, and WNT5B genes. Downregulation of DCC was consistent in all subtypes of MPN (EFC range: 0.591–0.860). However, CMTM5 had a 1.22‐fold upregulation in PMF in contrast to downregulation in other MPN subtypes (EFC range: 0.599–0.775). The results revealed a significant downregulation in CMTM5 and DCC at below 60‐years of age. Furthermore, female patients showed a clear‐cut downregulation in both CMTM5 and DCC (EFC DCC: 0.436 and CMTM5: 0.570), while male patients presented a less prominent downregulation with a borderline p‐value only in DCC (EFC: 0.69; p = 0.05).

Conclusions

Chronic myeloid leukemia cases showed a significant upregulation of WNT5B, as a known oncogenesis gene. Two tumor suppressor genes, namely DCC and CMTM5, were downregulated in the patients with MPNs, especially in females and patients below 60 years of age.

Muscone suppresses gastric cancer via regulation of miRNA-145

This study aims to determine the effects and mechanism of action of muscone on the biological activity of the gastric cancer cell lines SGC-7901 and MGC-803 (proliferation, apoptosis, invasion, and migration) in vitro. An optimal muscone concentration was determined using MTT and cell apoptosis tests. The SGC-7901 and MGC-803 cells were divided into five groups: normal control, muscone, miRNA, muscone + miRNA, and muscone + miRNA inhibitor. Cell proliferation rate, apoptosis rate, cell cycle phase distribution, number of invading cells, and wound healing rate were compared among the five groups using MTT, flow cytometry, transwell, and wound healing assays. Relative expression levels of the proteins PI3K, AKT, P21, c-Myc, MMP-2, and MMP-9 were measured by Western blot. Compared with the control group, the groups treated with muscone and miRNA showed significantly lower cell proliferation rate, number of invading cells, and wound healing rate (p < .05 for all), but significantly higher rates of cell apoptosis rate and numbers of cells in the G1 phase (p < .05 for all). These groups also showed significantly lower expression of the proteins PI3K, AKT, c-Myc, MMP-2, and MMP-9 but significantly increased expression of the protein P21 (p < .05). Transfecting muscone-treated SGC-7901 and MGC-803 cells with miRNA-145 inhibitor resulted in a significant recovery of biological activity (p < .05). Muscone suppresses the biological activity of SGC-7901 and MGC-803 gastric cancer cells in vitro via regulation of miRNA-145.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

These data provided CMTM5/7 as new biomarker and prognostic factors in BC.

Expression and clinical significance of CMTM1 in hepatocellular carcinoma

Background

CKLF Like Marvel Transmembrane Domain Containing 1 (CMTM1) plays a role in breast cancer and lung cancer, but studies on the occurrence and development of CMTM1 in hepatocellular carcinoma (HCC) have not been reported.

Methods

The Cancer Genome Atlas (TCGA) database and immunohistochemistry (IHC) were used to detect CMTM1 expression in HCC tissues. The relationship between CMTM1 expression and the clinicopathological characteristics of HCC patients was analyzed by chi-square test, and the relationship between CMTM1 expression and the prognosis of HCC patients was tested by the Kaplan–Meier model.

Results

Bioinformatics analysis showed that the mRNA expression of CMTM1 was upregulated in HCC tissues, and low expression of CMTM1 is associated with longer disease-free survival in patients with HCC. Similarly, the survival time of HCC patients in CMTM1 high expression group was significantly shorter than that in CMTM1 low expression group. IHC detection indicated that CMTM1 protein was highly expressed in both HCC and adjacent non-tumor tissues, with a positive expression in 84% (63/75) of HCC tissues and 89.3% (67/75) of adjacent non-tumor tissues. Moreover, CMTM1 expression was related to family history and TNM stage of HCC patients (P < 0.05), but had no relationship with other clinicopathological characteristics. The survival analysis based on IHC results showed that the prognosis of HCC patients in CMTM1 negative group was significantly poorer than that in CMTM1 positive group (P < 0.05).

Conclusion

CMTM1 has a high expression in HCC tissues and is related to the prognosis of HCC patients.

Expressions of ZNF436, β-catenin, EGFR, and CMTM5 in breast cancer and their clinical significances

As the leading malignancy among women, breast cancer is a serious threat to the life and health of women. In this context, it is of particular importance that a proper therapeutic target be identified for breast cancer treatment. We collected the pathological tissues of 80 patients, with the view to discovering appropriate molecular targets for the treatment of breast cancer, this paper analyzes the expressions of ZNF436, β-catenin, EGFR and CMTM5 in breast cancer tissues, as well as their correlations with breast cancer in combination with the clinicopathologic characteristics of studied patients. Immunohistochemistry (IHC) was utilized to detect the expression levels of ZNF436, β-catenin, EGFR and CMTM5 in cancerous and paracancerous tissues of breast cancer patients. The expression levels of ZNF436, β-Catenin and EGFR in breast cancer tissues were significantly greater than those in paracancerous tissues in this study (p<0.05), while CMTM5 was highly expressed in paracancerous tissues (p<0.05). Additionally, the correlation of the expressions of such indicators with the staging, differentiation and lymphatic metastasis of breast cancer, were also found to be statistically significant at the level p<0.05. The different expression levels of ZNF436, β-catenin, EGFR and CMTM5 in breast cancer and paracancerous tissues open up the possibility of utilizing them as molecular markers for breast cancer. These findings provide a theoretical basis for targeted molecular therapies for breast cancer, and hence carry a significant practical significance.

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.

Overexpression of Rab40b Promotes Hepatocellular Carcinoma Cell Proliferation and Metastasis via PI3K/AKT Signaling Pathway

Background

Rab40b is an evolutionarily conserved Rab GTPase that plays an important role in intracellular trafficking and is closely related to cancer progression. However, the role and potential molecular mechanism of Rab40b in hepatocellular carcinoma (HCC) have not yet been elucidated.

Materials and Methods

The expression of Rab40b in HCC tissues and peritumour tissues was tested by qRT-PCR, Western blotting and histological analysis. A Kaplan-Meier survival curve was generated based on the expression of Rab40b in the HCC samples. Cell proliferation assays, wound healing assays, and transwell assays are used to examine the effect of Rab40b on HCC cell growth in vitro. The effect of Rab40b on cell cycle was examined by flow cytometry. A xenograft implantation model was used to assess the effect of Rab40b on the development of HCC cells in vivo.

Results

Rab40b protein expression is upregulated in HCC tissues, and this upregulation is associated with high pathological stage and poor prognosis in HCC patients. Rab40b overexpression promotes the proliferation and metastasis of HCC cells by upregulating cyclin D1, cyclin E1 and matrix metalloproteinase 2 (MMP2) through the PI3K/AKT signalling pathway. Conversely, Rab40b inhibitors can significantly inhibit the proliferation and metastasis of HCC cell lines and induce G0/G1 cell cycle arrest and apoptosis. Studies of a nude mouse xenograft model demonstrated that Rab40b knockdown can significantly inhibit the proliferation and progression of HCC tumours in vivo.

Conclusion

Overall, this study demonstrates that Rab40b is an important oncoprotein that promotes HCC progression by regulating the expression of cyclin D1, cyclin E1, p21 and MMP2 through the PI3K/AKT signalling pathway.

Identification of Serum CMTM2 as a Potential Biomarker for HBV-Related Disorders

Substantial advance supports that CMTM2 serve as an important performer in physiological and pathological processes. However, very little is clear about the relationship between CMTM2 and HBV-related disorders. Here, for the first time, we explore that whether or not serum CMTM2 is involved in HBV-related diseases. We found that CMTM2 values were significantly lower in patients compared to healthy control (p <0.001), using ELISA assay. Furthermore, serum CMTM2 levels were negatively correlated with HBV DNA levels in CHB patients but not correlated with the serum levels of ALT and AST. Serum CMTM2 concentrations were not correlated with the serum levels of ALT, AST and HBV DNA load in HBLC and HCC patients. In addition, analysis of the ROC curve indicated that CMTM2 levels were significantly associated with the diagnostic value of HBV-related disorders. Finally, downregulation of CMTM2 was observed in HBV-infected cell model. CMTM2 degradation could be attributed to HBx-activated Lys48 (K48)-linked polyubiquitination, which was abolished by treatment with the proteasome inhibitor MG132. HBV infection suppresses CMTM2 expression by activating ubiquitin-proteasome system. Serum CMTM2 levels can be adopted as an effective indicator of the pathogenesis of HBV-related disorders.

CMTM5-v1 inhibits cell proliferation and migration by downregulating oncogenic EGFR signaling in prostate cancer cells

Anomalous epidermal growth factor receptor (EGFR) signaling plays an important role in the progression of prostate cancer (PCa) and the transformation to castration-resistant PCa (CRPC). A novel tumor suppressor CKLF-like MARVEL transmembrane domain-containing member 5(CMTM5) has a MARVEL domain and may regulate transmembrane signaling. Thus, we postulated that CMTM5 could regulate EGFR and its downstream molecules to affect the biological behaviors of PCa cells. In this study, we found that CMTM5 was expressed in benign prostatic hyperplasia (BPH) tissues but was undetectable in PCa cells. However, the EGFR was upregulated in PCa cells, especially in two metastatic CRPC cell lines, PC3 and DU145. Furthermore, ectopic expression of CMTM5-v1 suppressed cell proliferation and migration and p-EGFR levels. Further investigation revealed that restoration of CMTM5-v1 inhibited not only EGF-mediated proliferation but also chemotactic migration by EGF in PC3 and DU145 cells. Moreover, mechanistic studies showed that CMTM5-v1 attenuated EGF-induced receptor signaling by repressing EGFR and Akt phosphorylation in PCa cells, which were essential for malignant features. Finally, CMTM5-v1can promote the sensitivity of PC3 cells to Gefetinib, a tyrosine kinase inhibitor (TKI) targeting the EGFR. These observations indicate that CMTM5-v1 suppressed PCa cells through EGFR signaling. The loss of CMTM5 may participate in the progression of PCa resulting from deregulated EGFR, and CMTM5 might be associated with the efficacy of TKIs in terms of their potent inhibition of EGFR and human epidermal growth factor-2 (HER2) activation.

RNA-seq analysis identified hormone-related genes associated with prognosis of triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer that currently lacks effective biomarkers and therapeutic targets required to investigate the diagnosis and treatment of TNBC. Here we performed a comprehensive differential analysis of 165 TNBC samples by integrating RNA-seq data of breast tumor tissues and adjacent normal tissues from both our cohort and The Cancer Genome Atlas (TCGA). Pathway enrichment analysis was conducted to evaluate the biological function of TNBC-specific expressed genes. Further multivariate Cox proportional hazard regression was performed to evaluate the effect of these genes on TNBC prognosis. In this report, we identified a total of 148 TNBC-specific expressed genes that were primarily enriched in mammary gland morphogenesis and hormone levels related pathways, suggesting that mammary gland morphogenesis might play a unique role in TNBC patients differing from other breast cancer types. Further survival analysis revealed that nine genes ( FSIP1, ADCY5, FSD1, HMSD, CMTM5, AFF3, CYP2A7, ATP1A2, and C11orf86) were significantly associated with the prognosis of TNBC patients, while three of them ( ADCY5, CYP2A7, and ATP1A2) were involved in the hormone-related pathways. These findings indicated the vital role of the hormone-related genes in TNBC tumorigenesis and may provide some independent prognostic markers as well as novel therapeutic targets for TNBC.

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.

p21 in Cancer Research

p21 functions as a cell cycle inhibitor and anti-proliferative effector in normal cells, and is dysregulated in some cancers. Earlier observations on p21 knockout models emphasized the role of this protein in cell cycle arrest under the p53 transcription factor activity. Although tumor-suppressor function of p21 is the most studied aspect of this protein in cancer, the role of p21 in phenotypic plasticity and its oncogenic/anti-apoptotic function, depending on p21 subcellular localization and p53 status, have been under scrutiny recently. Basic science and translational studies use precision gene editing to manipulate p21 itself, and proteins that interact with it; these studies have led to regulatory/functional/drug sensitivity discoveries as well as therapeutic approaches in cancer field. In this review, we will focus on targeting p21 in cancer research and its potential in providing novel therapies.

Increased CMTM6 can predict the clinical response to PD-1 inhibitors in non-small cell lung cancer patients

CKLF-like MARVEL transmembrane domain containing 6 (CMTM6) plays a crucial role in the stability of the programmed death-ligand 1 (PD-L1). However, there has been no previous study of CMTM6 in non-small cell lung cancer (NSCLC) and its association with PD-L1 has not been confirmed. The aim of this study was to investigate the expression of CMTM6 and PD-L1 and to confirm their predictive roles for anti-PD-1 therapy in non-small cell lung cancer. CMTM6 and PD-L1 immunohistochemical expressions were evaluated in 35 advanced, treatment-refractory NSCLC patients who received PD-1 inhibitor therapy. The correlation between CMTM6 and PD-L1 expression was also determined based on immunohistochemistry and RNA-sequencing data obtained from The Cancer Genome Atlas (TCGA) database. CMTM6 expression was positively correlated with PD-L1 expression in immunohistochemical data (Pearson's r = 0.342 and p = .044). A positive correlation was also identified in the mRNA expression data. Using receiver operating characteristic curves, the levels of CMTM6 and PD-L1 expression which provided the best distinguishing point between responder versus non-responder to PD-1 inhibitors were 70 and 75 H-scores, respectively. The patients in the PD-1 inhibitor responder group had higher CMTM6 expressions in univariate logistic regression analysis (odds ratio (OR) = 5.333, p = .037). However, PD-L1 expression was not associated with response to PD-1 inhibitor (p = .288). In multivariate analysis, CMTM6 was also found to be an independent predictor of the response to PD-1 inhibitors (OR = 6.226, p = .032). CMTM6 expression can be a promising predictor useful for therapeutic decision-making regarding PD-1 inhibitors.

Overexpression of CMTM7 inhibits cell growth and migration in liver cancer

Chemokine-like factor (CKLF)-like, MAL and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain-containing family proteins (CMTMs) have significant roles in the immune system, in male reproduction, as well as in tumorigenesis. Previous studies have shown that CMTM family member 7 (CMTM7) was broadly expressed in various normal tissues, but not in lung, gastric, esophageal, pancreas, and cervix cancers. To explore its relationship with liver cancer, we examined the expression of CMTM7 in liver cancers and its correlation with clinical and pathological conditions. We found that CMTM7 expression was markedly reduced in liver cancer tissues, and negatively correlated with TNM staging and tumor metastasis. In vitro studies showed that enforced expression of CMTM7 inhibited the cell growth and migration of liver cancer cells. Further analysis revealed that CMTM7 suppressed AKT signaling and induced cell cycle arrest at the G0/G1 phase in the liver cancer cells, likely as the consequent of decreased levels of cyclin D1, cyclin-dependent kinase 4 (CDK4), and CDK6, and increased p27 expression. Thus, CMTM7 functions as a tumor suppressor in liver cancer through suppressing cell cycle progression.

Characterization of the epithelial membrane protein 3 interaction network reveals a potential functional link to mitogenic signal transduction regulation

Epithelial Membrane Protein 3 (EMP3), a 4-transmembrane glycoprotein, first gained attention as a putative tumor suppressor. Accumulating evidence, however, points to a more tumor promotive function of EMP3. The biological function of EMP3 remains largely unclear. To elucidate more of EMP3's interaction network, we performed a Yeast-Two-Hybrid (Y2H) screening, followed by validation of candidate interactors by Biomolecular Fluorescence Complementation (BiFC) and Proximity Ligation Assay (PLA). Furthermore, we generated stable EMP3 knockdown cell lines and measured cell proliferation, migration and sensitivity to apoptosis induction as well as the expression and activation levels of important signal pathway components. The Y2H screening yielded 10 novel interactions of EMP3, eight of which could also be detected by BiFC and PLA interaction assays. All newly discovered interaction partners are involved in signaling or trafficking regulation. Most notably, FLOT1 and HTATIP2 have well described roles in the regulation of EGFR signaling. In addition, knockdown of EMP3 resulted in reduced levels of p-AKT, p-ERK and p-EGFR, attenuated cell proliferation and migration and sensitized cells to apoptosis induction by TRAIL and Staurosporine. Based on these observations we hypothesize that EMP3 might be involved in the regulation of receptor-tyrosine-kinase mediated mitogenic signaling.

Identification of prognostic biomarkers for patients with hepatocellular carcinoma after hepatectomy

Hepatocellular carcinoma (HCC) is a lethal malignancy with high morbidity and mortality rates worldwide. The identification of prognosis-associated biomarkers is crucial to improve HCC patient survival. The present study aimed to explore potential predictive biomarkers for HCC. Differentially expressed genes (DEGs) were analyzed in the GSE36376 dataset using GEO2R. Hub genes were identified and further investigated for prognostic value in HCC patients. A risk score model and nomogram were constructed to predict HCC prognosis using the prognosis-associated genes and clinical factors. Pearson's correlation was employed to show interactions among hub genes. Gene enrichment analysis was performed to identify detailed biological processes and pathways. A total of 71 DEGs were obtained and seven (ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13, all adjusted P≤0.05) of the 10 hub genes were identified as prognosis-related genes for survival analysis in HCC patients, including alcohol dehydrogenase 4 (class II), pi polypeptide (ADH4), cytochrome p450 family 2 subfamily C member 8 (CYP2C8), cytochrome P450 family 2 subfamily C member 9 (CYP2C9), cytochrome P450 family 8 subfamily B member 1 (CYP8B1), solute carrier family 22 member 1 (SLC22A1), tyrosine aminotransferase (TAT) and hydroxysteroid 17-β dehydrogenase 13 (HSD17B13). The risk score model could predict HCC prognosis and the nomogram visualized gene expression and clinical factors of probability for HCC prognosis. The majority of genes showed significant Pearson's correlations with others (41 Pearson correlations P≤0.01, four Pearson correlations P>0.05). GO analysis revealed that terms such as ‘chemical carcinogenesis’ and ‘drug metabolism-cytochrome P450’ were enriched and may prove helpful to elucidate the mechanisms of hepatocarcinogenesis. Hub genes ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13 may be useful as predictive biomarkers for HCC prognosis.

Association Between Polymorphisms in CMTM Family Genes and Hepatocellular Carcinoma in Guangxi of China

Polymorphisms in genes may affect its expression and alter individual susceptibility to cancer. In this study, we investigate associations between CMTM family gene polymorphisms and hepatocellular carcinoma (HCC) in a southern Chinese population. Ten selected single-nucleotide polymorphisms (SNPs) in CMTM family genes were genotyped in 315 HCC patients and 315 cancer-free controls using Sequenom MassARRAY platform and the associations of the selected SNPs with HCC risk were evaluated. We found individuals with the rs164207 AA genotypes had a significantly increased risk of HCC than those with CC genotypes (adjusted OR = 2.794, 95% CI = 1.143-6.828). Also, individuals with the rs3811178 GG genotypes showed a significant association with increased risk of HCC when compared with the AA genotypes (adjusted OR = 2.578, 95% CI = 1.114-5.969). Furthermore, there was also a significantly increased risk of HCC when combined risk genotypes of these loci, i.e., rs164207 AA, CA and rs3811178 GG, GA. Compared with the low-risk group (0 risk genotypes), the high-risk group (2 risk genotypes) was at significantly increased risk of HCC (adjusted OR = 3.339, 95% CI = 1.119-9.964, p = 0.031). Our results suggest that polymorphisms of rs3811178 in CMTM5 and rs164207 in CMTM6 might contribute to the genetic susceptibility of HCC in the southern Chinese population. Further well-designed studies with larger sample sizes are needed to confirm our findings.

Long Noncoding RNA FGFR3-AS1 Promotes Hepatocellular Carcinoma Carcinogenesis via Modulating the PI3K/AKT Pathway

Hepatocellular carcinoma (HCC) as one of the most refractory cancers leads to high mortality worldwide. Long noncoding RNAs have been widely acknowledged as important biomarkers and therapeutic targets in HCC. In this study, we investigated the effects of long noncoding RNA FGFR3-AS1 on tumor growth and metastasis in HCC. First, we found that the expression of FGFR3-AS1 was upregulated about threefold in HCC samples and cell lines. We knocked down FGFR3-AS1 in Huh7 and Hep3B cells and found that FGFR3-AS1 knockdown significantly inhibited cell proliferation but induced apoptosis. Moreover, FGFR3-AS1 knockdown led to more HCC cells arrested in the G₀ stage. FGFR3-AS1 knockdown significantly inhibited cell migration and invasion. Additionally, we found that FGFR3-AS1 silencing dramatically delayed tumor growth in vivo. We found that, mechanistically, FGFR3-AS1 silencing decreased the activation of the PI3K/AKT signaling pathway. Taken together, our data demonstrated the pro-oncogenic role of FGFR3-AS1 in HCC and suggested that FGFR3-AS1 may serve as a novel biomarker for the diagnosis and therapeutic target for HCC treatment.