MAL2 expression predicts distant metastasis and short survival in pancreatic cancer

Activation of MAL2 by RAD21 inhibits the expression of MHC-I in immune evasion of endometrial cancer

CD8+ T cells are the primary mediators of anticancer immunity, and modulation of the CD8+ T cell response has been a central focus of immunotherapy to treat cancer. When CD8+ T cells specifically recognize antigenic peptides presented by the MHC-I on tumor cells, they become activated and kill the tumor cells. However, one pivotal mechanism through which tumor cells evade immune surveillance is to reduce their antigen presentation. To identify novel immunotherapeutic targets, we specifically focused on the role of MAL2 in immune evasion in endometrial cancer (EC) and the underlying mechanism. MAL2 was overexpressed in EC tissues and cells and its transcription was enhanced by RAD21. Knockdown of MAL2 or RAD21 inhibited malignant behavior and immune evasion of EC cells by repressing MHC-I expression and the cytotoxic effects of CD8+ cells. Conversely, MAL2 promoted immune evasion of EC cells and tumor growth in mice in the presence of RAD21 knockdown. These results indicate that RAD21 activation of MAL2 inhibits antigen processing and presentation of MHC-I, thereby inducing immune evasion of EC cells. We further suggest that RAD21 and MAL2 may serve as novel targets for EC immunotherapy.

ATF1 regulates MAL2 expression through inhibition of miR-630 to mediate the EMT process that promotes cervical cancer cell development and metastasis

BACKGROUND

The existence of activating transcription factor 1 (ATF1) could be employed as a clinical marker in the context of cervical cancer development, although its specific mechanism has not been fully clarified.

METHODS

To evaluate the presence of ATF1, miR-630, and myelin and lymphocyte protein 2 (MAL2) in cervical malignancies, we conducted quantitative reverse transcription polymerase chain reaction, immunohistochemistry, and Western blot assays; further studied the expansion, migration, invasion and epithelial-mesenchymal transition (EMT) of cervical carcinoma cells using colony formation assay, transwell, loss cytometry, Western blot. Chromatin immunoprecipitation (ChIP) and RNA immunoprecipitation (RIP) were used to verify that ATF1 could directly transcriptionally repress miR-630; dual luciferase reporter assay and RIP assay were employed to confirm that miR-630 targeted to repress MAL2.

RESULTS

In cervical cancer cases, elevated ATF1 expression and reduced miR-630 expression were detected, displaying a negative relationship between them. Inhibition of ATF1 hindered the growth, migration, infiltration, and EMT in cervical carcinoma cells, while upregulation of miR-630 mitigated the aggressive characteristics of these cells. ATF1 was found to transcriptionally repress miR-630 by TransmiR and ALGGEN prediction and ChIP validation. MicroRNA modulates gene expression and affects cancer progression, and we discovered that miR-630 regulates cancer progression by targeting and inhibiting MAL2.

CONCLUSION

ATF1, which modulates the miR-630/MAL2 pathway, affects the EMT process and cervical carcinoma cell growth and spread. Therefore, ATF1 may serve as a promising marker and treatment target for cervical malignancies intervention.

MAL2 reprograms lipid metabolism in intrahepatic cholangiocarcinoma via EGFR/SREBP-1 pathway based on single-cell RNA sequencing

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive cancer characterized by a poor prognosis and resistance to chemotherapy. In this study, utilizing scRNA-seq, we discovered that the tetra-transmembrane protein mal, T cell differentiation protein 2 (MAL2), exhibited specific enrichment in ICC cancer cells and was strongly associated with a poor prognosis. The inhibition of MAL2 effectively suppressed cell proliferation, invasion, and migration. Transcriptomics and metabolomics analyses suggested that MAL2 promoted lipid accumulation in ICC by stabilizing EGFR membrane localization and activated the PI3K/AKT/SREBP-1 axis. Molecular docking and Co-IP proved that MAL2 interacted directly with EGFR. Based on constructed ICC organoids, the downregulation of MAL2 enhanced apoptosis and sensitized ICC cells to cisplatin. Lastly, we conducted a virtual screen to identify sarizotan, a small molecule inhibitor of MAL2, and successfully validated its ability to inhibit MAL2 function. Our findings highlight the tumorigenic role of MAL2 and its involvement in cisplatin sensitivity, suggesting the potential for novel combination therapeutic strategies in ICC.

Sorafenib Resistance Contributed by IL7 and MAL2 in Hepatocellular Carcinoma Can Be Overcome by Autophagy-Inducing Stapled Peptides

Drug resistance poses a great challenge in systemic therapy for hepatocellular carcinoma (HCC). However, the underlying molecular mechanisms associated with resistance to anti-cancer drugs, such as Sorafenib, remain unclear. In this study, we use transposon insertional mutagenesis to generate Sorafenib-resistant HCC cell lines in order to identify potential drug resistant causative genes. Interleukin 7 (IL7) and mal, T cell differentiation protein 2 (MAL2) were identified as candidate genes that promote survival by activating JAK/STAT and PI3K/AKT signaling pathways. Sorafenib-resistant cells exhibited higher clonogenic survival and lower drug sensitivity due to IL7 and MAL2 upregulation. Higher anti-apoptotic effect, clonogenic survival and increased PI3K/AKT/STAT3 activities were observed in IL7 and MAL2 co-overexpressing cells compared with controls or cells overexpressing IL7 or MAL2 individually. Given the critical role of MAL2 in endocytosis, we propose that MAL2 might facilitate the endocytic trafficking of IL7 and its cognate receptors to the plasma membrane, which leads to upregulated JAK/STAT and PI3K/AKT signaling pathways and Sorafenib resistance. Additionally, our previous studies showed that an autophagy-inducing stapled peptide promoted the endolysosomal degradation of c-MET oncogene and overcame adaptive Sorafenib resistance in c-MET+ HCC cells. In this study, we demonstrate that these stapled peptides readily induced autophagy and inhibited the proliferation of both wild-type and Sorafenib-resistant HCC cells co-overexpressing both IL7 and MAL2. Furthermore, these peptides showed synergistic cytotoxicity with Sorafenib in drug-resistant HCC cells co-overexpressing both IL7 and MAL2. Our studies suggest that targeting autophagy may be a novel strategy to overcome IL7/MAL2-mediated Sorafenib resistance in HCC.

Identification and Interaction Analysis of Molecular Markers in Pancreatic Ductal Adenocarcinoma by Bioinformatics and Next-Generation Sequencing Data Analysis

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common cancers worldwide. Intense efforts have been made to elucidate the molecular pathogenesis, but the molecular mechanisms of PDAC are still not well understood. The purpose of this study is to further explore the molecular mechanism of PDAC through integrated bioinformatics analysis.

Methods

To identify the candidate genes in the carcinogenesis and progression of PDAC, next-generation sequencing (NGS) data set GSE133684 was downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified, and Gene Ontology (GO) and pathway enrichment analyses were performed. The protein-protein interaction network (PPI) was constructed and the module analysis was performed using Integrated Interactions Database (IID) interactome database and Cytoscape. Subsequently, miRNA-DEG regulatory network and TF-DEG regulatory network were constructed using miRNet database, NetworkAnalyst database, and Cytoscape software. The expression levels of hub genes were validated based on Kaplan-Meier analysis, expression analysis, stage analysis, mutation analysis, protein expression analysis, immune infiltration analysis, and receiver operating characteristic (ROC) curve analysis.

Results

A total of 463 DEGs were identified, consisting of 232 upregulated genes and 233 downregulated genes. The enriched GO terms and pathways of the DEGs include vesicle organization, secretory vesicle, protein dimerization activity, lymphocyte activation, cell surface, transferase activity, transferring phosphorus-containing groups, hemostasis, and adaptive immune system. Four hub genes (namely, cathepsin B [CCNB1], four-and-a-half LIM domains 2 (FHL2), major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1) and tubulin beta 1 class VI (TUBB1)) were obtained via taking interaction of different analysis results.

Conclusions

On the whole, the findings of this investigation enhance our understanding of the potential molecular mechanisms of PDAC and provide potential targets for further investigation.

Downregulation of MAL2 inhibits breast cancer progression through regulating β-catenin/c-Myc axis

PURPOSE

Myelin and lymphocyte protein 2 (MAL2) is mainly involved in endocytosis under physiological conditions and mediates the transport of materials across the membranes of cell and organelle. It has been reported that MAL2 is significantly upregulated in diverse cancers. This study aimed to investigate the role of MAL2 in breast cancer (BC).

METHODS

Bioinformatics analysis and Immunohistochemical assay were applied to detect the correlation between MAL2 expression in breast cancer tissues and the prognosis of breast cancer patients. Functional experiments were carried out to investigate the role of MAL2 in vitro and in vivo. The molecular mechanisms involved in MAL2-induced β-catenin and c-Myc expression and β-catenin/c-Myc-mediated enhancement of BC progression were confirmed by western blot, β-catenin inhibitor and agonist, Co-IP and immunofluorescence colocalization assays.

RESULTS

Results from the cancer genome atlas (TCGA) and clinical samples confirmed a significant upregulation of MAL2 in BC tissues than in adjacent non-tumor tissues. High expression of MAL2 was associated with worse prognosis. Functional experiments demonstrated that MAL2 knockdown reduced the migration and invasion associating with EMT, increased the apoptosis of BC cells in vitro and reduced the metastatic capacity in vivo. Mechanistically, MAL2 interacts with β-catenin in BC cells. MAL2 silencing reduced the expression of β-catenin and c-Myc, while the β-catenin agonist SKL2001 partially rescued the downregulation of c-Myc and inhibition of migration and invasion caused by MAL2 knockdown in BC cells.

CONCLUSION

These observations provided evidence that MAL2 acted as a potential tumor promoter by regulating EMT and β-catenin/c-Myc axis, suggesting potential implications for anti-metastatic therapy for BC.

The MAL Family of Proteins: Normal Function, Expression in Cancer, and Potential Use as Cancer Biomarkers

The MAL family of integral membrane proteins consists of MAL, MAL2, MALL, PLLP, CMTM8, MYADM, and MYADML2. The best characterized members are elements of the machinery that controls specialized pathways of membrane traffic and cell signaling. This review aims to help answer the following questions about the MAL-family genes: (i) is their expression regulated in cancer and, if so, how? (ii) What role do they play in cancer? (iii) Might they have biomedical applications? Analysis of large-scale gene expression datasets indicated altered levels of MAL-family transcripts in specific cancer types. A comprehensive literature search provides evidence of MAL-family gene dysregulation and protein function repurposing in cancer. For MAL, and probably for other genes of the family, dysregulation is primarily a consequence of gene methylation, although copy number alterations also contribute to varying degrees. The scrutiny of the two sources of information, datasets and published studies, reveals potential prognostic applications of MAL-family members as cancer biomarkers-for instance, MAL2 in breast cancer, MAL2 and MALL in pancreatic cancer, and MAL and MYADM in lung cancer-and other biomedical uses. The availability of validated antibodies to some MAL-family proteins sanctions their use as cancer biomarkers in routine clinical practice.

Developing and validating a survival prediction model based on blood exosomal ceRNA network in patients with PAAD

BACKGROUND

Among the most lethal cancers, pancreatic adenocarcinoma (PAAD) is an essential component of digestive system malignancies that still lacks effective diagnosis and treatment methods. As exosomes and competing endogenous RNA (ceRNA) regulatory networks in tumors go deeper, we expect to construct a ceRNA regulatory network derived from blood exosomes of PAAD patients by bioinformatics methods and develop a survival prediction model based on it.

METHODS

Blood exosome sequencing data of PAAD patients and normal controls were downloaded from the exoRbase database, and the expression profiles of exosomal mRNA, lncRNA, and circRNA were differentially analyzed by R. The related mRNA, circRNA, lncRNA, and their corresponding miRNA prediction data were imported into Cytoscape software to visualize the ceRNA network. Then, we conducted GO and KEGG enrichment analysis of mRNA in the ceRNA network. Genes that express differently in pancreatic cancer tissues compared with normal tissues and associate with survival (P < 0.05) were determined as Hub genes by GEPIA. We identified optimal prognosis-related differentially expressed mRNAs (DEmRNAs) and generated a risk score model by performing univariate and multivariate Cox regression analyses.

RESULTS

205 DEmRNAs, 118 differentially expressed lncRNAs (DElncRNAs), and 98 differentially expressed circRNAs (DEcircRNAs) were screened out. We constructed the ceRNA network, and a total of 26 mRNA nodes, 7 lncRNA nodes, 6 circRNA nodes, and 16 miRNA nodes were identified. KEGG enrichment analysis showed that the DEmRNAs in the regulatory network were mainly enriched in Human papillomavirus infection, PI3K-Akt signaling pathway, Osteoclast differentiation, and ECM-receptor interaction. Next, six hub genes (S100A14, KRT8, KRT19, MAL2, MYO5B, PSCA) were determined through GEPIA. They all showed significantly increased expression in cancer tissues compared with control groups, and their high expression pointed to adverse survival. Two optimal prognostic-related DEmRNAs, MYO5B (HR = 1.41, P < 0.05) and PSCA (HR = 1.10, P < 0.05) were included to construct the survival prediction model.

CONCLUSION

In this study, we successfully constructed a ceRNA regulatory network in blood exosomes from PAAD patients and developed a two-gene survival prediction model that provided new targets which shall aid in diagnosing and treating PAAD.

Association Mining Identifies MAL2 as a Novel Tumor Suppressor in Colorectal Cancer

Introduction

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. However, the driver genes that promote CRC metastasis remain poorly understood. Association mining mines and extracts the repeated correlations and relevance in a dataset to predict the appearance of other data items according to the appearance of one item.

Methods

Here, the Apriori algorithm was used to find the frequent mutational gene sets (FMGSs) and hidden association rules (ARs) within these FMGSs from 383 CRCs with whole exome sequencing datasets. The weighted correlation network analysis (WGCNA) was used to identify the hub genes in CRC. CCK8, colony formation, cell migration and invasion assays were adopted to detect the roles of hub genes in CRC.

Results

Intriguingly, we found that MAL2 (myelin and lymphocyte protein 2) was associated with TP53 and APC in stage IV of CRC, and further subnetwork exploration based on WGCNA identified MAL2 as a potent hub gene. To validate the metastasis-related role of MAL2 in CRC, a lentivirus-based overexpression system was utilized to construct MAL2-overexpressing human CRC LOVO cells. Overexpression of MAL2 remarkably inhibited CRC cell proliferation and invasion.

Conclusion

Our results highlighted that MAL2 acts as a tumor suppressor in CRC and could serve as a potential therapeutic target.

Transcriptional expressions of hsa-mir-183 predicted target genes as independent indicators for prognosis in bladder urothelial carcinoma

OBJECTIVE

To uncover novel prognostic and therapeutic targets for BLCA, our study is the first to investigate the role of hsa-mir-183 and its up-regulated predicted target genes in bladder urothelial carcinoma.

METHODS

To address this issue, our study explored the roles of hsa-mir-183 predicted target genes in the prognosis of BLCA via UALCAN, Metascape, Kaplan-Meier plotter, Human Protein Atlas, TIMER2.0, cBioPortal and Genomics of Drug Sensitivity in Cancer databases.

RESULTS

High transcriptional expressions of PDCD6, GNG5, PHF6 and MAL2 were markedly relevant to favorable OS in BLCA patients, whereas SLC25A15 and PTDSS1 had opposite expression significance. Additionally, high transcriptional expression of PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 were significantly correlated with BLCA individual cancer stages and molecular subtypes. Furthermore, high mutation rate of PDCD6, MAL2, SLC25A15 and PTDSS1 were observed. Finally, TP53 mutation of PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 has guiding significance for drug selection in BLCA.

CONCLUSIONS

PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 could be the advanced independent indicators for prognosis of BLCA patients, and TP53-mutation might be a biomarker for drug option in BLCA patients.

The novel circ_0084904/miR-802/MAL2 axis promotes the development of cervical cancer

Circular RNAs (circRNAs) have been identified as critical regulators in human cancers, including cervical cancer (CC). However, the precise action of circ_0084904 in cervical carcinogenesis remains to be elucidated. The levels of circ_0084904, microRNA (miR)-802, and Mal, T cell differentiation protein 2 (MAL2) were checked by quantitative real-time PCR (qRT-PCR) or western blot. Ribonuclease R (RNase R) and subcellular localization assays were used to detect the stability and localization of circ_0084904, respectively. Cell colony formation ability was assessed by colony formation assay. Cell cycle and apoptosis were detected by flow cytometry. Cell migration and invasion abilities were gauged by transwell assay. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were applied to determine the direct relationship between miR-802 and circ_0084904 or MAL2. The xenograft experiments were performed to evaluate the role of circ_0084904 in tumor growth in vivo. Circ_0084904 was markedly up-regulated in CC tissues and cell lines. Silencing endogenous circ_0084904 impeded cell colony formation, cell cycle progression, migration, invasion, epithelial-mesenchymal transition (EMT), and promoted apoptosis in vitro, as well as diminished tumor growth in vivo. Mechanistically, circ_0084904 targeted miR-802, and the effects of circ_0084904 silencing were mediated by miR-802. MAL2 was directly targeted and inhibited by miR-802, and MAL2 was a functional target of miR-802. Moreover, circ_0084904 modulated MAL2 expression via miR-802. Our study identified circ_0084904 as a novel oncogenic driver in CC depending on the modulation of the miR-802/MAL2 axis, establishing the notion that silencing of circ_0084904 might represent a promising targeted therapy for CC.

PIK3CB is involved in metastasis through the regulation of cell adhesion to collagen I in pancreatic cancer

Introduction

Pancreatic adenocarcinoma (PAAD) is an aggressive malignancy, with a major mortality resulting from the rapid progression of metastasis. Unfortunately, no effective treatment strategy has been developed for PAAD metastasis to date. Thus, unraveling the mechanisms involved in PAAD metastatic phenotype may facilitate the treatment for PAAD patients.

Objectives

PIK3CB is an oncogene implicated in cancer development and progression but less is known about whether PIK3CB participates in PAAD metastasis. Therefore, the objective of this study is to explore the mechanism(s) of PIK3CB in PAAD metastasis.

Methods

In our study, we examined the PIK3CB expression pattern using bioinformatic analysis and clinical material derived from patients with PAAD. Subsequently, a series of biochemical experiments were conducted to investigate the role of PIK3CB as potential mechanism(s) underlying PAAD metastasis in vivo using nude mice and in vitro using cell lines.

Results

We observed that PIK3CB was involved in PAAD progression. Notably, we identified that PIK3CB was involved in PAAD metastasis. Downregulation of PIK3CB significantly reduced PAAD metastatic potential in vivo. Furthermore, a series of bioinformatic analyses showed that PIK3CB was involved in cell adhesion in PAAD. Notably, PIK3CB depletion inhibited invasion potential specifically via suppressing cell adhesion to collagen I in PAAD cells.

Conclusion

Collectively, our findings indicate that PIK3CB is involved in PAAD metastasis through cell-matrix adhesion. We proposed that PIK3CB is a potential therapeutic target for PAAD therapy.

Overexpression of MAL2 Correlates with Immune Infiltration and Poor Prognosis in Breast Cancer

Background

Myelin and lymphocyte, T cell differentiation protein 2 (MAL2) is highly expressed in various cancers and associated with the development and prognosis of cancer. However, the relationship between MAL2 and breast cancer requires further investigation. This study aimed to explore the prognostic significance of MAL2 in breast cancer.

Methods

MAL2 expression was initially assessed using the Oncomine database and The Cancer Genome Atlas (TCGA) database and verified by quantitative real-time polymerase chain reaction (RT-qPCR). The chi-square test or Fisher's exact test was used to explore the association between clinical characteristics and MAL2 expression. The prognostic value of MAL2 in breast cancer was assessed by the Kaplan–Meier method and Cox regression analysis. Gene set enrichment analysis (GSEA) was performed to identify the biological pathways correlated with MAL2 expression in breast cancer. Besides, a single-sample GSEA (ssGSEA) was used to assess the relationship between the level of immune infiltration and MAL2 in breast cancer.

Results

Both bioinformatics and RT-qPCR results showed that MAL2 was expressed at high levels in breast cancer tissues compared with the adjacent tissues. The chi-square test or Fisher's exact test indicated that MAL2 expression was related to stage, M classification, and vital status. Kaplan–Meier curves implicated that high MAL2 expression was significantly associated with the poor prognosis. Cox regression models showed that high MAL2 expression could be an independent risk factor for breast cancer. GSEA showed that 14 signaling pathways were enriched in the high-MAL2-expression group. Besides, the MAL2 expression level negatively correlated with infiltrating levels of eosinophils and plasmacytoid dendritic cells in breast cancer.

Conclusion

Overexpression of MAL2 correlates with poor prognosis and lower immune infiltrating levels of eosinophils and plasmacytoid dendritic cells in breast cancer and may become a biomarker for breast cancer prognosis.

Efficacy of decitabine in malignant meningioma cells: relation to promoter demethylation of distinct tumor suppressor and oncogenes and independence from TERT

OBJECTIVE

Chemotherapeutic options for meningiomas refractory to surgery or irradiation are largely unknown. Human telomerase reverse transcriptase (hTERT) promoter methylation with subsequent TERT expression and telomerase activity, key features in oncogenesis, are found in most high-grade meningiomas. Therefore, the authors investigated the impact of the demethylating agent decitabine (5-aza-2'-deoxycytidine) on survival and DNA methylation in meningioma cells.

METHODS

hTERT promoter methylation, telomerase activity, TERT expression, and cell viability and proliferation were investigated prior to and after incubation with decitabine in two benign (HBL-52 and Ben-Men 1) and one malignant (IOMM-Lee) meningioma cell line. The global effects of decitabine on DNA methylation were additionally explored with DNA methylation profiling.

RESULTS

High levels of TERT expression, telomerase activity, and hTERT promoter methylation were found in IOMM-Lee and Ben-Men 1 but not in HBL-52 cells. Decitabine induced a dose-dependent significant decrease of proliferation and viability after incubation with doses from 1 to 10 μM in IOMM-Lee but not in HBL-52 or Ben-Men 1 cells. However, effects in IOMM-Lee cells were not related to TERT expression, telomerase activity, or hTERT promoter methylation. Genome-wide methylation analyses revealed distinct demethylation of 14 DNA regions after drug administration in the decitabine-sensitive IOMM-Lee but not in the decitabine-resistant HBL-52 cells. Differentially methylated regions covered promoter regions of 11 genes, including several oncogenes and tumor suppressor genes that to the authors' knowledge have not yet been described in meningiomas.

CONCLUSIONS

Decitabine decreases proliferation and viability in high-grade but not in benign meningioma cell lines. The effects of decitabine are TERT independent but related to DNA methylation changes of promoters of distinct tumor suppressor genes and oncogenes.

Myelin and lymphocyte protein 2 regulates cell proliferation and metastasis through the Notch pathway in prostate adenocarcinoma

Background

Myelin and lymphocyte protein 2 (MAL2) is a proven oncogene in some human tumors. However, currently, little is known about the function of MAL2 in prostate adenocarcinoma (PRAD). This study sought to investigate the role of MAL2 on PRAD progression.

Methods

MAL2 expression in PRAD was first analyzed by the Gene Expression Profiling Interactive Analysis (GEPIA) database. The reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assay and Western blot assay were used to detect the expression of MAL2 in PRAD tissues and cell lines. Additionally, immunohistochemistry (IHC) straining was used to detect the expression of MAL2 in PRAD pathological tissues. The Cell Counting Kit-8 (CCK-8) assay, clone formation assay and Flow cytometry were performed to investigate the effect of MAL2 on PRAD cell proliferation and cell apoptosis. Cell migration and invasion were measured by Transwell assay. The effect of MAL2 on epithelial-mesenchymal transition (EMT) progression and the Notch signaling pathway in PRAD was also investigated.

Results

MAL2 was discovered to be obviously upregulated in PRAD tissues and cell lines. The upregulation of MAL2 was closely associated with tumor, nodes and metastases (TNM) stage, the Gleason score and metastasis of PRAD patients, and affected the prognosis of PRAD patients. Functionally, the depletion of MAL2 suppressed cell proliferation, migration, invasion, and EMT progression, and promoted cell apoptosis of PRAD cells. In an in vivo experiment, MAL2 knockdown significantly suppressed tumor growth in mice. Further, inhibiting the Notch pathway reversed the effect of MAL2 knockdown on PRAD progression.

Conclusions

In sum, MAL2 was found to be upregulated in PRAD, and appears to act as a carcinogen in PRAD. Additionally, MAL2 appears to regulate PRAD progression through the Notch signaling pathway.

MAL2 interacts with IQGAP1 to promote pancreatic cancer progression by increasing ERK1/2 phosphorylation

Pancreatic cancer is a digestive tract malignancy characterized by an occult onset and rapid progression. The genetic heterogeneity of pancreatic cancer is closely related to its highly malignant biological behavior. The myelin and lymphocyte protein 2 (MAL2) is upregulated in multiple cancers at the transcriptional level. However, the exact role of MAL2 in pancreatic cancer remains elusive. In this study, we demonstrated that MAL2 protein and mRNA levels were upregulated in pancreatic cancer. MAL2 overexpression was significantly associated with poor prognosis in patients with pancreatic cancer. We further showed that MAL2 interacted with IQGAP1 to increase ERK1/2 phosphorylation levels, which promoted pancreatic cancer progression. Therefore, these results suggest that MAL2 could be a novel therapeutic target for pancreatic cancer.

FTO modifies the m6A level of MALAT and promotes bladder cancer progression

BACKGROUND

Nearly a half million people around the world are diagnosed with bladder cancer each year, and an incomplete understanding of its pathogenicity and lack of efficient biomarkers having been discovered lead to poor clinical management of bladder cancer. Fat mass and obesity-associated protein (FTO) is a critical player in carcinogenesis. We, here, explored the role of FTO and unraveled the mechanism of its function in bladder cancer.

METHODS

Identification of the correlation of FTO with bladder cancer was based on both bioinformatics and clinical analysis of tissue samples collected from a cohort of patients at a hospital and microarray data. Gain-of-function and loss-of-function assays were conducted in vivo and in vitro to assess the effect of FTO on bladder carcinoma tumor growth and its impact on the bladder carcinoma cell viability. Moreover, the interactions of intermediate products were also investigated to elucidate the mechanisms of FTO function.

RESULTS

Bladder tumor tissues had increased FTO expression which correlated with clinical bladder cancer prognosis and outcomes. Both in vivo and in vitro, it played the function of an oncogene in stimulating the cell viability and tumorigenicity of bladder cancer. Furthermore, FTO catalyzed metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) demethylation, regulated microRNA miR-384 and mal T cell differentiation protein 2 (MAL2) expression, and modulated the interactions among these processes.

CONCLUSIONS

The interplay of these four clinically relevant factors contributes to the oncogenesis of bladder cancer. FTO facilitates the tumorigenesis of bladder cancer through regulating the MALAT/miR-384/MAL2 axis in m6A RNA modification manner, which ensures the potential of FTO for serving as a diagnostic or prognostic biomarker in bladder cancer.

LAMA4 upregulation is associated with high liver metastasis potential and poor survival outcome of Pancreatic Cancer

Rationale: Pancreatic cancer is one of the most difficult cancers to manage and its poor prognosis stems from the lack of a reliable early disease biomarker coupled with its highly metastatic potential. Liver metastasis accounts for the high mortality rate in pancreatic cancer. Therefore, a better understanding of the mechanism(s) underlying the acquisition of the metastatic potential in pancreatic cancer is highly desirable.

Methods: Microarray analysis in wild-type and highly liver metastatic human pancreatic cancer cell lines was performed to identify gene expression signatures that underlie the metastatic process. We validated our findings in patient samples, nude mice, cell lines and database analysis.

Results: We identified a metastasis-related gene, laminin subunit alpha 4 (LAMA4), that was upregulated in highly liver metastatic human pancreatic cancer cell lines. Downregulation of LAMA4 reduced the liver metastatic ability of pancreatic cancer cells in vivo. Furthermore, LAMA4 expression was positively correlated with tumor severity and in silico analyses revealed that LAMA4 was associated with altered tumor microenvironment. In particular, our in vitro and in vivo results showed that LAMA4 expression was highly correlated with cancer-associated fibroblasts (CAFs) level which may contribute to pancreatic cancer metastasis. We further found that LAMA4 had a positive effect on the recruitment and activity of CAFs.

Conclusions: These data provide evidence for LAMA4 as a possible biomarker of disease progression and poor prognosis in pancreatic cancer. Our findings indicate that LAMA4 may contribute to pancreatic cancer metastasis via recruitment or activation of CAFs.

A novel mRNA-miRNA-lncRNA competing endogenous RNA triple sub-network associated with prognosis of pancreatic cancer

Background: Recently, increasing evidence has uncovered the roles of mRNA-miRNA-lncRNA network in multiple human cancers. However, a systematic mRNA-miRNA-lncRNA network linked to pancreatic cancer prognosis is still absent. Methods: Differentially expressed genes (DEGs) were first identified by mining GSE16515 and GSE15471 datasets. DAVID database was utilized to conduct functional enrichment analysis. Protein-protein interaction (PPI) network was built using STRING database, and hub genes were identified by Cytoscape plug-in CytoHubba. Upstream miRNAs and lncRNAs of mRNAs were predicted by miRTarBase and miRNet, respectively. Expression, survival and correlation analysis for genes, miRNAs and lncRNAs were performed via GEPIA, Kaplan-Meier plotter and starBase. Results: 734 and 180 upregulated and downregulated significant DEGs were identified, respectively. Functional enrichment analysis revealed that they were significantly enriched in focal adhesion, pathways in cancer and metabolic pathways. According to node degree, hub genes in the PPI networks were screened, such as TGFB1 and ALB. Among the top 20 hub genes, 7 upregulated genes and 2 downregulated hub genes had significant prognostic values in pancreatic cancer. 33 miRNAs were predicted to target the 9 key genes. But only high expression of 8 miRNAs indicated favorable prognosis in pancreatic cancer. Then, 90 lncRNAs were predicted to potentially bind to the 8 miRNAs. SCAMP1, HCP5, MAL2 and LINC00511 were finally identified as key lncRNAs. By combination of results from expression, survival and correlation analysis demonstrated that MMP9/ITGB1-miR-29b-3p-HCP5 competing endogenous RNA (ceRNA) sub-network was linked to prognosis of pancreatic cancer. Conclusions: In a word, we established a novel mRNA-miRNA-lncRNA sub-network, among which each RNA may be utilized as a prognostic biomarker of pancreatic cancer.

Plasma extracellular vesicle long RNA profiling identifies a diagnostic signature for the detection of pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is difficult to diagnose at resectable stage. Recent studies have suggested that extracellular vesicles (EVs) contain long RNAs. The aim of this study was to develop a diagnostic (d-)signature for the detection of PDAC based on EV long RNA (exLR) profiling.

DESIGN

We conducted a case-control study with 501 participants, including 284 patients with PDAC, 100 patients with chronic pancreatitis (CP) and 117 healthy subjects. The exLR profile of plasma samples was analysed by exLR sequencing. The d-signature was identified using a support vector machine algorithm and a training cohort (n=188) and was validated using an internal validation cohort (n=135) and an external validation cohort (n=178).

RESULTS

We developed a d-signature that comprised eight exLRs, including FGA, KRT19, HIST1H2BK, ITIH2, MARCH2, CLDN1, MAL2 and TIMP1, for PDAC detection. The d-signature showed high accuracy, with an area under the receiver operating characteristic curve (AUC) of 0.960, 0.950 and 0.936 in the training, internal validation and external validation cohort, respectively. The d-signature was able to identify resectable stage I/II cancer with an AUC of 0.949 in the combined three cohorts. In addition, the d-signature showed superior performance to carbohydrate antigen 19-9 in distinguishing PDAC from CP (AUC 0.931 vs 0.873, p=0.028).

CONCLUSION

This study is the first to characterise the plasma exLR profile in PDAC and to report an exLR signature for the detection of pancreatic cancer. This signature may improve the prognosis of patients who would have otherwise missed the curative treatment window.

MAL2-Induced Actin-Based Protrusion Formation is Anti-Oncogenic in Hepatocellular Carcinoma

Recent studies report that the polarity gene myelin and lymphocyte protein 2 (MAL2), is overexpressed in multiple human carcinomas largely at the transcript level. Because chromosome 8q24 amplification (where MAL2 resides) is associated with hepatocellular- and cholangio-carcinomas, we examined MAL2 protein expression in these human carcinoma lesions and adjacent benign tissue using immunohistochemistry. For comparison, we analyzed renal cell carcinomas that are not associated with chromosome 8q24 amplification. Surprisingly, we found that MAL2 protein levels were decreased in the malignant tissues compared to benign in all three carcinomas, suggesting MAL2 expression may be anti-oncogenic. Consistent with this conclusion, we determined that endogenously overexpressed MAL2 in HCC-derived Hep3B cells or exogenously expressed MAL2 in hepatoma-derived Clone 9 cells (that lack endogenous MAL2) promoted actin-based protrusion formation with a reciprocal decrease in invadopodia. MAL2 overexpression also led to decreased cell migration, invasion and proliferation (to a more modest extent) while loss of MAL2 expression reversed the phenotypes. Mutational analysis revealed that a putative Ena/VASP homology 1 recognition site confers the MAL2-phenotype suggesting its role in tumor suppression involves actin remodeling. To reconcile decreased MAL2 protein expression in human carcinomas and its anti-oncogenic phenotypes with increased transcript levels, we propose a transcriptional regulatory model for MAL2 transient overexpression.

Identification of novel mRNA-miRNA-lncRNA competing endogenous RNA network associated with prognosis of breast cancer

Aim: To identify novel competing endogenous RNA (ceRNA) network related to patients prognosis in breast cancer. Materials & methods: Dysregulated mRNA based on intersection of three Gene Expression Omnibus and The Cancer Genome Atlas datasets were analyzed by bioinformatics. Results: In total 72 upregulated and 208 downregulated genes were identified. Functional analysis showed that some pathways related to cancer were significantly enriched. By means of stepwise reverse prediction and validation from mRNA to lncRNA, 19 hub genes, nine key miRNA and four key lncRNAs were identified by expression and survival analysis. Ultimately, the coexpression analysis identified RRM2-let-7a-5p-SNHG16/MAL2 as key ceRNA subnetwork associated with prognosis of breast cancer. Conclusion: We successfully constructed a novel ceRNA network, among which each component was significantly associated with breast cancer prognosis.

Development of prognostic signature and nomogram for patients with breast cancer

To identify prognostic signature that could predict the survival of patients with breast cancer (BC).Breast cancer samples and normal breast tissues in the TCGA-BRCA and GSE7390 were included. Differentially expressed genes (DEGs) were identified using the "limma" method. Overall survival (OS) associated with DEGs were obtained using univariate and multivariable Cox proportional-hazards regression analysis, and the corresponding prognostic signature and nomogram were constructed. Calibration analysis and decision curve analysis (DCA) were performed.In all, 742 DEGs were identified, 19 of which were independently correlated with the OS of BC patients. The OS of patients in the 19-gene signature low-risk group was significantly better than that in high-risk group (hazard ratio [HR] 0.3506, 95% confidence interval [CI] 0.2488-0.4939), and the 19-gene based signature was demonstrated to be an independent prognostic factor in patient with BC in the TCGA-BRCA cohort (HR 1.501, 95% CI 1.374-1.640) and validation cohort GSE7392 ((HR 0.3557, 95% CI 0.2155-0.5871, P < .0001)). The primary and internally validated C-indexes for the 19-gene signature-based nomogram were 0.817 and 8.013, respectively. The results of calibration analysis and DCA analysis confirmed the robustness and the clinical usability of the nomogram.We constructed a prognostic signature and nomogram for patient with BC, which showed good application prospect.

MiR-129 regulates growth and invasion by targeting MAL2 in papillary thyroid carcinoma

MAL2, a member of the MAL proteolipid family, is essential for raft-mediated transport. In this study, we investigated the roles and underlying mechanism of MAL2 in the development of papillary thyroid carcinoma (PTC). Up-regulation of MAL2 was found in human PTC tissues and significantly correlated with poor overall survival (OS). Knockdown of MAL2 dramatically suppressed PTC cell proliferation and invasion in vitro and inhibited tumor growth in vivo. We further found that miR-129 suppressed the expression of MLA through directly binding to the 3' untranslated region (3' UTR). While forced miR-129 expression suppressed growth and invasion of PTC cells, re-expression of MAL2 rescued these effects. Taken together, our data indicated that MAL2 acted as an oncogene and was negatively regulated by miR-129, supporting the potential therapeutic strategy against PTC by targeting miR-129-MAL2 axis.

Pancreatic tumor microenvironment confers highly malignant properties on pancreatic cancer cells

Tumor microenvironment plays a pivotal role in cancer progression; however, little is known regarding how differences in the microenvironment affect characteristics of cancer cells. Here, we investigated the effects of tumor microenvironment on cancer cells by using mouse tumor models. After three cycles of inoculation and extraction of human pancreatic cancer cells, including SUIT-2 and Panc-1 cells, from tumors, distinct cancer cell lines were established: 3P cells from the pancreas obtained using the orthotopic tumor model and 3sc cells from subcutaneous tissue obtained using the subcutaneous tumor model. On re-inoculation of these cells, the 3sc cells and, more prominently, the 3P cells, exhibited higher tumorigenic activity than the parental cells. The 3P cells specifically exhibited low E-cadherin expression and high invasiveness, suggesting that they were endowed with the highest malignant characteristics. RNA-sequence analysis demonstrated that distinct signaling pathways were activated in each cell line and that the 3P cells acquired a cancer stem cell-like phenotype. Among cancer stem cell-related genes, those specifically expressed in the 3P cells, including NES, may be potential new targets for cancer therapy. The mechanisms underlying the development of highly malignant cancer cell lines were investigated. Individual cell clones within the parental cells varied in tumor-forming ability, indicating the presence of cellular heterogeneity. Moreover, the tumor-forming ability and the gene expression profile of each cell clone were altered after serial orthotopic inoculations. The present study thus suggests that both selection and education processes by tumor microenvironment are involved in the development of highly malignant cancer cells.

Effects of cell-cell crosstalk on gene expression patterns in a cell model of renal cell carcinoma lung metastasis

The median survival rate of patients with metastatic renal carcinoma is approximately 10 to 12 months, with up to 50% of patients developing metastases in the lung parenchyma. The molecular basis for metastatic development remains unclear. In the present study, we used renal cell carcinoma (RCC) cells and bronchial epithelial cells, representing metastasis target organ cells, conditioned medium and co-culture models to identify specific gene expression changes responsible for cancer cell viability in a metastatic microenvironment. RCC cell proliferation and migration increased when the culture was supplemented with conditioned medium from lung fibroblasts or pleural epithelial cells. Healthy epithelial cells were, in turn, also stimulated with conditioned medium from RCC cell lines. The mitogen-activated protein kinase (MAPK), interleukin (IL)-6, and phosphatidylinositol 4,5-bisphosphate (PIP2) signaling pathways were identified as deregulated upon cell‑cell interaction. Thus, cell-cell communication may contribute to the development of the metastatic niche. The identified deregulated signaling pathways may be considered as potential therapeutic targets in metastatic renal carcinoma.

The four-transmembrane protein MAL2 and tumor protein D52 (TPD52) are highly expressed in colorectal cancer and correlated with poor prognosis

The four-transmembrane protein MAL2 and tumor protein D52 (TPD52) have been shown to be involved in tumorigenesis of various cancers. However, their roles in colorectal cancer (CRC) remain unclear. In this study, we explored the expressions of MAL2 and TPD52 in tumor specimens resected from 123 CRC patients and the prognostic values of the two proteins in CRC. Immunohistochemical analyses showed that MAL2 (P<0.001) and TPD52 (P<0.001) were significantly highly expressed in primary carcinoma tissues compared with adjacent non-cancerous mucosa tissues. And TPD52 exhibited frequent overexpression in liver metastasis tissues relative to primary carcinoma tissues (P = 0.042), while MAL2 in lymphnode and liver metastasis tissues showed no significant elevation. Real-time quantitative PCR (RT-qPCR) showed the identical results. Correlation analyses by Pearson's chi-square test demonstrated that MAL2 in tumors was positively correlated with tumor status (pathological assessment of regional lymph nodes (pN, P = 0.024)), and clinic stage (P = 0.017). Additionally, the expression of TPD52 was detected under the same condition and was shown to be positively correlated withtumor status (pathological assessment of the primary tumor (pT, P = 0.035), distant metastasis (pM, P = 0.001)) and CRC clinicopathology(P = 0.024). Kaplan-Meier survival curves indicated that positive MAL2 (P<0.001) and TPD52 (P<0.001) expressions were associated with poor overall survival (OS) in CRC patients. Multivariate analysis showed that MAL2 and TPD52 expression was an independent prognostic factor for reduced OS of CRC patients. Moreover, overexpression of TPD52 in CRC SW480 cells showed an increased cell migration (P = 0.023) and invasion (P = 0.012) through inducing occurrence of epithelial-mesenchymal transition (EMT) and activating focal adhesion kinase (FAK)-mediated integrin signalling and PI3K⁄Akt signalling.Whereas TPD52-depleted cells showed the reverse effect. These data suggested that MAL2 and TPD52 might be potential biomarkers for clinical prognosis and might be a promising therapeutic target for CRC.

Exploring the intrinsic differences among breast tumor subtypes defined using immunohistochemistry markers based on the decision tree

Exploring the intrinsic differences among breast cancer subtypes is of crucial importance for precise diagnosis and therapeutic decision-making in diseases of high heterogeneity. The subtypes defined with several layers of information are related but not consistent, especially using immunohistochemistry markers and gene expression profiling. Here, we explored the intrinsic differences among the subtypes defined by the estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 based on the decision tree. We identified 30 mRNAs and 7 miRNAs differentially expressed along the tree's branches. The final signature panel contained 30 mRNAs, whose performance was validated using two public datasets based on 3 well-known classifiers. The network and pathway analysis were explored for feature genes, from which key molecules including FOXQ1 and SFRP1 were revealed to be densely connected with other molecules and participate in the validated metabolic pathways. Our study uncovered the differences among the four IHC-defined breast tumor subtypes at the mRNA and miRNA levels, presented a novel signature for breast tumor subtyping, and identified several key molecules potentially driving the heterogeneity of such tumors. The results help us further understand breast tumor heterogeneity, which could be availed in clinics.

Establishment of novel in vitro mouse chief cell and SPEM cultures identifies MAL2 as a marker of metaplasia in the stomach

Oxyntic atrophy in the stomach leads to chief cell transdifferentiation into spasmolytic polypeptide expressing metaplasia (SPEM). Investigations of preneoplastic metaplasias in the stomach are limited by the sole reliance on in vivo mouse models, owing to the lack of in vitro models for distinct normal mucosal lineages and metaplasias. Utilizing the Immortomouse, in vitro cell models of chief cells and SPEM were developed to study the characteristics of normal chief cells and metaplasia. Chief cells and SPEM cells isolated from Immortomice were cultured and characterized at both the permissive (33°C) and the nonpermissive temperature (39°C). Clones were selected on the basis of their transcriptional expression of specific stomach lineage markers (named ImChief and ImSPEM) and protein expression and growth were analyzed. The transcriptional expression profiles of ImChief and ImSPEM cells were compared further by using gene microarrays. ImChief cells transcriptionally express most chief cell markers and contain pepsinogen C and RAB3D-immunostaining vesicles. ImSPEM cells express the SPEM markers TFF2 and HE4 and constitutively secrete HE4. Whereas ImChief cells cease proliferation at the nonpermissive temperature, ImSPEM cells continue to proliferate at 39°C. Gene expression profiling of ImChief and ImSPEM revealed myelin and lymphocyte protein 2 (MAL2) as a novel marker of SPEM lineages. Our results indicate that the expression and proliferation profiles of the novel ImChief and ImSPEM cell lines resemble in vivo chief and SPEM cell lineages. These cell culture lines provide the first in vitro systems for studying the molecular mechanisms of the metaplastic transition in the stomach.

CD166/ALCAM expression is characteristic of tumorigenicity and invasive and migratory activities of pancreatic cancer cells

BACKGROUND

CD166, also known as activated leukocyte cell adhesion molecule (ALCAM), is expressed by various cells in several tissues including cancer. However, the role of CD166 in malignant tumors is controversial, especially in pancreatic cancer. This study aimed to clarify the role and significance of CD166 expression in pancreatic cancer.

METHODS

We performed immunohistochemistry and flow cytometry to analyze the expression of CD166 in surgical pancreatic tissues and pancreatic cancer cell lines. The differences between isolated CD166+ and CD166- pancreatic cancer cells were analyzed by invasion and migration assays, and in mouse xenograft models. We also performed quantitative RT-PCR and microarray analyses to evaluate the expression levels of CD166 and related genes in cultured cells.

RESULTS

Immunohistochemistry revealed high expression of CD166 in pancreatic cancer tissues (12.2%; 12/98) compared with that in normal pancreas controls (0%; 0/17) (p = 0.0435). Flow cytometry indicated that CD166 was expressed in 33.8-70.2% of cells in surgical pancreatic tissues and 0-99.5% of pancreatic cancer cell lines. Invasion and migration assays demonstrated that CD166- pancreatic cancer cells showed stronger invasive and migratory activities than those of CD166+ cancer cells (p<0.05). On the other hand, CD166+ Panc-1 cells showed a significantly stronger colony formation activity than that of CD166- Panc-1 cells (p<0.05). In vivo analysis revealed that CD166+ cells elicited significantly greater tumor growth than that of CD166- cells (p<0.05) in both subcutaneous and orthotopic mouse tumor models. mRNA expression of the epithelial-mesenchymal transition activator Zeb1 was over-expressed in CD166- cells (p<0.001). Microarray analysis showed that TSPAN8 and BST2 were over-expressed in CD166+ cells, while BMP7 and Col6A1 were over-expressed in CD166- cells.

CONCLUSIONS

CD166+ pancreatic cancer cells are strongly tumorigenic, while CD166- pancreatic cancer cells exhibit comparatively stronger invasive and migratory activities. These findings suggest that CD166 expression is related to different functions in pancreatic cancer cells.