Hypermethylation of NDN promotes cell proliferation by activating the Wnt signaling pathway in colorectal cancer

Targeting CD44 and other pleiotropic co-receptors as a means for broad inhibition of tumor growth and metastasis

Although progress has been made in the treatment of cancer, particularly for the four major types of cancers affecting the lungs, colon, breast and prostate, resistance to cancer treatment often emerges upon inhibition of major signaling pathways, which leads to the activation of additional pathways as a last-resort survival mechanism by the cancer cells. This signaling plasticity provides cancer cells with a level of operational freedom, reducing treatment efficacy. Plasticity is a characteristic of cancer cells that are not only able to switch signaling pathways but also from one cellular state (differentiated cells to stem cells or vice versa) to another. It seems implausible that the inhibition of one or a few signaling pathways of heterogeneous and plastic tumors can sustain a durable effect. We propose that inhibiting molecules with pleiotropic functions such as cell surface co-receptors can be a key to preventing therapy escape instead of targeting bona fide receptors. Therefore, we ask the question whether co-receptors often considered as "accessory molecules" are an overlooked key to control cancer cell behavior.

Necdin, one of the important pathway proteins in the regulation of osteosarcoma progression by microRNA-200c

MicroRNA-200c (miR-200c) generally acts as a tumor suppressor in multiple cancer types and a promising therapeutic target in tumorigenesis. However, only a few studies have explained the role of miR-200c in the development of osteosarcoma (OS). In this study, we investigated the role of miR-200c in OS progression and identified the regulatory pathway protein NDN involved in inhibiting the occurrence and development of OS. Firstly, we found that miR-200c is downregulated in OS cells and tissues. As well, in vitro and in vivo experiments showed that upregulating miR-200c inhibits the proliferation, invasion, metastasis of Saos-2 cells, promotes the apoptosis of Saos-2 cells and suppresses tumor growth in mice, indicating miR-200c plays a major role in regulating the OS progression. Furthermore, bioinformatics analysis showed that an anti-tumor protein, necdin (NDN), might be a potential target by miR-200c. To verify this hypothesis, we measured the expression level of NDN in OS cells and tissues and found NDN is downregulated, suggesting NDN is functional in OS progression. Moreover, we found that the expression levels of NDN and miR-200c in in vivo and in vitro experiments were positively correlated. However, the results of dual-luciferase reporter gene experiment showed miR-200c does not directly act on the 3ʹ untranslated region (UTR) of NDN gene, indicating that NDN might be an important pathway protein which regulates OS progression in the presence of miR-200c. Therefore, miR-200c/NDN could be potential targets for developing effective treatment against OS.

Role of DNA Methylation in the Resistance to Therapy in Solid Tumors

Despite the recent advances in chemotherapeutic treatments against cancer, some types of highly aggressive and invasive cancer develop drug resistance against conventional therapies, which continues to be a major problem in the fight against cancer. In recent years, studies of alterations of DNA methylome have given us a better understanding of the role of DNA methylation in the development of tumors. DNA methylation (DNAm) is an epigenetic change that promotes the covalent transfer of methyl groups to DNA. This process suppresses gene expression through the modulation of the transcription machinery access to the chromatin or through the recruitment of methyl binding proteins. DNAm is regulated mainly by DNA methyltransferases. Aberrant DNAm contributes to tumor progression, metastasis, and resistance to current anti-tumoral therapies. Aberrant DNAm may occur through hypermethylation in the promoter regions of tumor suppressor genes, which leads to their silencing, while hypomethylation in the promoter regions of oncogenes can activate them. In this review, we discuss the impact of dysregulated methylation in certain genes, which impact signaling pathways associated with apoptosis avoidance, metastasis, and resistance to therapy. The analysis of methylome has revealed patterns of global methylation, which regulate important signaling pathways involved in therapy resistance in different cancer types, such as breast, colon, and lung cancer, among other solid tumors. This analysis has provided gene-expression signatures of methylated region-specific DNA that can be used to predict the treatment outcome in response to anti-cancer therapy. Additionally, changes in cancer methylome have been associated with the acquisition of drug resistance. We also review treatments with demethylating agents that, in combination with standard therapies, seem to be encouraging, as tumors that are in early stages can be successfully treated. On the other hand, tumors that are in advanced stages can be treated with these combination schemes, which could sensitize tumor cells that are resistant to the therapy. We propose that rational strategies, which combine specific demethylating agents with conventional treatment, may improve overall survival in cancer patients.

Identification of aberrantly methylated differentially expressed genes and associated pathways in endometrial cancer using integrated bioinformatic analysis

Endometrial cancer (EC) is a fatal female reproductive tumor. Bioinformatic tools are increasingly developed to screen out molecular targets related to EC. In this study, http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE17025 and http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE40032 were obtained from Gene Expression Omnibus (GEO). “limma” package and Venn diagram tool were used to identify hub genes. FunRich was used for functional analysis. Retrieval of Interacting Genes Database (STRING) was used to analyze protein‐protein interaction (PPI) complex. Cancer Genome Atlas (TCGA), GEPIA, immunohistochemistry staining, and ROC curve analysis were carried out for validation. Univariate and multivariate regression analyses were performed to predict the risk score. Compound muscle action potential (CMap) was used to find potential drugs. GSEA was also done. We retrieved seven oncogenes which were upregulated and hypomethylated and 12 tumor suppressor genes (TSGs) which were downregulated and hypermethylated. The upregulated and hypomethylated genes were strikingly enriched in term “immune response” while the downregulated and hypermethylated genes were mainly focused on term “aromatic compound catabolic process.” TCGA and GEPIA were used to screen out EDNRB, CDO1, NDN, PLCD1, ROR2, ESPL1, PRAME, and PTTG1. Among them, ESPL1 and ROR2 were identified by Cox regression analysis and were used to construct prognostic risk model. The result showed that ESPL1 was a negative independent prognostic factor. Cmap identified aminoglutethimide, luteolin, sulfadimethoxine, and maprotiline had correlation with EC. GSEA results showed that “hedgehog signaling pathway” was enriched. This research inferred potential aberrantly methylated DEGs and dysregulated pathways may participate in EC development and firstly reported eight hub genes, including EDNRB, CDO1, NDN, PLCD1, ROR2, ESPL1, PRAME, and PTTG1 that could be used to predict EC prognosis. Aminoglutethimide and luteolin may be used to fight against EC.

Hypermethylation Of ADHFE1 Promotes The Proliferation Of Colorectal Cancer Cell Via Modulating Cell Cycle Progression

Background

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Studies have demonstrated that epigenetic modifications play essential roles in the development of CRC. ADHFE1 is a differentially expressed gene that has been reported to be hypermethylated in CRC. However, the role and mechanism of ADHFE1 in the proliferation of CRC remain unclear.

Materials and methods

ADHFE1 expression was analyzed in CRC tissues by IHC and qRT-PCR, and the relationship between ADHFE1 expression and the clinicopathological parameters was analyzed. Cell proliferation were assessed by the in vitro and in vivo experimental models. GSEA assay was performed to explore the mechanism of ADHFE1 in the proliferation of CRC. Flow cytometry and Western blot were used to detect the activation of the cell cycle signaling. Bisulfite genomic sequence (BSP) assay was used to test the methylation degree of ADHFE1 gene promoter in CRC tissues.

Results

Here, we verified that ADHFE1 was down-regulated and hypermethylated in CRC tissues. The down-regulation of ADHFE1 was correlated with poor differentiation and advanced TNM stage of CRC patients. And ADHFE1 expression restored when the CRC cell line SW620 was treated with the demethylating agent 5-Aza-CdR. Overexpression of ADHFE1 inhibited the proliferation of CRC, while ADHFE1 knockdown promoted the proliferation of CRC cells in vitro and in vivo. Moreover, ADHFE1 overexpression could induce a significant G1-S cell cycle arrest in CRC cells and vice versa.

Conclusion

Hypermethylation of ADHFE1 might promote cell proliferation by modulating cell cycle progression in CRC, potentially providing a new therapeutic target for CRC patients.

A Role for the WNT Co-Receptor LRP6 in Pathogenesis and Therapy of Epithelial Cancers

The WNT/β-catenin signaling pathway controls stem and progenitor cell proliferation, survival and differentiation in epithelial tissues. Aberrant stimulation of this pathway is therefore frequently observed in cancers from epithelial origin. For instance, colorectal and hepatic cancers display activating mutations in the CTNNB1 gene encoding β-catenin, or inactivating APC and AXIN gene mutations. However, these mutations are uncommon in breast and pancreatic cancers despite nuclear β-catenin localization, indicative of pathway activation. Notably, the low-density lipoprotein receptor-related protein 6 (LRP6), an indispensable co-receptor for WNT, is frequently overexpressed in colorectal, liver, breast and pancreatic adenocarcinomas in association with increased WNT/β -catenin signaling. Moreover, LRP6 is hyperphosphorylated in KRAS-mutated cells and in patient-derived colorectal tumours. Polymorphisms in the LRP6 gene are also associated with different susceptibility to developing specific types of lung, bladder and colorectal cancers. Additionally, recent observations suggest that LRP6 dysfunction may be involved in carcinogenesis. Indeed, reducing LRP6 expression and/or activity inhibits cancer cell proliferation and delays tumour growth in vivo. This review summarizes current knowledge regarding the biological function and regulation of LRP6 in the development of epithelial cancers—especially colorectal, liver, breast and pancreatic cancers.

Downregulation of DACT-2 by Promoter Methylation and its Clinicopathological Significance in Prostate Cancer

Backgrounds: Dapper homolog (DACT) 2, a member of DACT gene family, is frequently down-regulated in various malignancies and linked to tumor progression. However, the regulatory mechanism of DACT-2 expression and its biological role in human prostate cancer (PCa) remains elusive. Here, we investigated the expression and an epigenetic change of DACT-2 in prostate cancer, and determined if these findings were correlated with clinicopathologic characteristics of PCa.

Methods: The expression profile of DACT-2 of was detected by qRT-PCR, Western blotting, and immunohistochemistry in four prostate cell lines (RWPE-1, LNCaP, PC-3 and DU145), 56 cases of frozen prostate tissues (forty-seven primary prostate carcinomas, nine paired noncancerous and cancerous prostate tissues) and a tissue microarray sets including 100 paraffin-embedded prostate samples (3 normal tissues, 2 cases of adjacent tissues and 95 cases of cancer). Subsequently, the regulatory mechanism of DACT-2 down-regulation was investigated through methylation-specific PCR (MSP) and bisulfite sequencing (BSP). The role of DACT-2 in prostate cancer cell migration and invasion was respectively examined by wound healing and transwell assay. After 5-aza-2'-deoxycytidine treatment of prostate cancer cells, qRT-PCR was used to detect whether the expression of DACT-2 gene mRNA in the cells recovered.

Results: Immunohistochemical results shown that the DACT-2 protein was strongly (3+) expressed in the cytoplasm of all 5 noncancerous tissues and 12.7% (12/95) prostate cancer (PCa) tissues. Whereas 68.4% (65/95) PCa samples and 18.9% (18/95) PCa tissues respectively displayed weakly (1+) expressed and moderately (2+) expressed. In addition, DACT-2 expression was negatively associated with Gleason score in tumor specimens (p=0.029). What's more, down-regulation and promoter methylation of DACT-2 were observed in 68.1% (32/47) frozen PCa tissues and all three prostate cancer cell lines. And, the expression of DACT-2 mRNA was restored by the treatment of demethylated drug 5-aza-2'-deoxycytidine in all prostate cancer lines. Prostate cancer cells invasion and migration were significantly suppressed by ectopic expression of DACT-2 in vitro.

Conclusions: Our study provides evidence that DACT-2 may be a useful biomarker for distinguishing prostate tumor tissues from non-cancerous samples and a potential target for epigenetic silencing in primary prostate Cancer.

Drugs Targeting Epigenetic Modifications and Plausible Therapeutic Strategies Against Colorectal Cancer

Genetic variations along with epigenetic modifications of DNA are involved in colorectal cancer (CRC) development and progression. CRC is the fourth leading cause of cancer-related deaths worldwide. Initiation and progression of CRC is the cumulation of a variety of genetic and epigenetic changes in colonic epithelial cells. Colorectal carcinogenesis is associated with epigenetic aberrations including DNA methylation, histone modifications, chromatin remodeling, and non-coding RNAs. Recently, epigenetic modifications have been identified like association of hypermethylated gene Claudin11 (CLDN11) with metastasis and prognosis of poor survival of CRC. DNA methylation of genes CMTM3, SSTR2, MDF1, NDRG4 and TGFB2 are potential epigenetic biomarkers for the early detection of CRC. Tumor suppressor candidate 3 (TUSC3) mRNA expression is silenced by promoter methylation, which promotes epidermal growth factor receptor (EGFR) signaling and rescues the CRC cells from apoptosis and hence leading to poor survival rate. Previous scientific evidences strongly suggest epigenetic modifications that contribute to anticancer drug resistance. Recent research studies emphasize development of drugs targeting histone deacetylases (HDACs) and DNA methyltransferase inhibitors as an emerging anticancer strategy. This review covers potential epigenetic modification targeting chemotherapeutic drugs and probable implementation for the treatment of CRC, which offers a strong rationale to explore therapeutic strategies and provides a basis to develop potent antitumor drugs.

SSH3 facilitates colorectal cancer cell invasion and metastasis by affecting signaling cascades involving LIMK1/Rac1

Slingshot phosphatase 3 (SSH3) is a member of the SSH phosphatase family that regulates actin filament dynamics. However, its role in cancer metastasis is relatively unclear compared to that of SSH1. Here, we showed that SSH3 was upregulated in colorectal cancer (CRC). Of note, SSH3 was upregulated in the tumor thrombus and lymph node metastasis compared with that in paired primary CRC tissues. High SSH3 expression was associated with the aggressive phenotype of CRC and may be an independent prognostic factor for the poor survival of patients with CRC. SSH3 significantly enhanced the invasion and metastasis of CRC cells in vitro and in vivo. Moreover, SSH3 regulated the remodeling of actin, which is involved in the cytoskeleton signaling pathway, through its interaction with LIMK1/Rac1 and subsequently promoted CRC cell invasion and metastasis. Our data elucidate an important role for SSH3 in the progression of CRC, and SSH3 may be considered a potential therapeutic target for CRC.

Dietary Compounds as Epigenetic Modulating Agents in Cancer

Epigenetic mechanisms control gene expression during normal development and their aberrant regulation may lead to human diseases including cancer. Natural phytochemicals can largely modulate mammalian epigenome through regulation of mechanisms and proteins responsible for chromatin remodeling. Phytochemicals are mainly contained in fruits, seeds, and vegetables as well as in foods supplements. These compounds act as powerful cellular antioxidants and anti-carcinogens agents. Several dietary compounds such as catechins, curcumin, genistein, quercetin and resveratrol, among others, exhibit potent anti-tumor activities through the reversion of epigenetic alterations associated to oncogenes activation and inactivation of tumor suppressor genes. In this review, we summarized the actual knowledge about the role of dietary phytochemicals in the restoration of aberrant epigenetic alterations found in cancer cells with a particular focus on DNA methylation and histone modifications. Furthermore, we discussed the mechanisms by which these natural compounds modulate gene expression at epigenetic level and described their molecular targets in diverse types of cancer. Modulation of epigenetic activities by phytochemicals will allow the discovery of novel biomarkers for cancer prevention, and highlights its potential as an alternative therapeutic approach in cancer.

Development of somatic mutation signatures for risk stratification and prognosis in lung and colorectal adenocarcinomas

Background

Prognostic signatures are vital to precision medicine. However, development of somatic mutation prognostic signatures for cancers remains a challenge. In this study we developed a novel method for discovering somatic mutation based prognostic signatures.

Results

Somatic mutation and clinical data for lung adenocarcinoma (LUAD) and colorectal adenocarcinoma (COAD) from The Cancer Genome Atlas (TCGA) were randomly divided into training (n = 328 for LUAD and 286 for COAD) and validation (n = 167 for LUAD and 141 for COAD) datasets. A novel method of using the log2 ratio of the tumor mutation frequency to the paired normal mutation frequency is computed for each patient and missense mutation. The missense mutation ratios were mean aggregated into gene-level somatic mutation profiles. The somatic mutations were assessed using univariate Cox analysis on the LUAD and COAD training sets separately. Stepwise multivariate Cox analysis resulted in a final gene prognostic signature for LUAD and COAD. Performance was compared to gene prognostic signatures generated using the same pipeline but with different somatic mutation profile representations based on tumor mutation frequency, binary calls, and gene-gene network normalization. Signature high-risk LUAD and COAD cases had worse overall survival compared to the signature low-risk cases in the validation set (log-rank test p-value = 0.0101 for LUAD and 0.0314 for COAD) using mutation tumor frequency ratio (MFR) profiles, while all other methods, including gene-gene network normalization, have statistically insignificant stratification (log-rank test p-value ≥0.05). Most of the genes in the final gene signatures using MFR profiles are cancer-related based on network and literature analysis.

Conclusions

We demonstrated the robustness of MFR profiles and its potential to be a powerful prognostic tool in cancer. The results are robust according to validation testing and the selected genes are biologically relevant.

NIT1 suppresses tumour proliferation by activating the TGFβ1-Smad2/3 signalling pathway in colorectal cancer

NIT1 protein has been reported to be a potential tumour suppressor in tumour progression. However, little is known about the specific role of NIT1 in tumour development and progression. In this study, we confirmed the specific effects of NIT1 in the regulation of colorectal carcinoma cell proliferation. Here, we showed that NIT1 was significantly downregulated in colorectal cancer tissues compared with that in adjacent normal tissues. The decreased expression of NIT1 was significantly correlated with poor differentiation and more serosal invasion. Functional experiments showed that NIT1 inhibited CRC cell growth both in vitro and in vivo. NIT1 induced cell cycle arrest and apoptosis. Furthermore, NIT1 recruited Smad2/3 to the TGFβ receptor and activated the TGFβ–Smad2/3 pathway by interacting with SARA and SMAD2/3 in CRC. Further study has shown that SMAD3 directly binds to the promoter regions of NIT1 and enhances the transcription of NIT1. Together, our findings indicate that NIT1 suppresses CRC proliferation through a positive feedback loop between NIT1 and activation of the TGFβ–Smad signalling pathway. This study might provide a new promising strategy for CRC.