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In this study, we found that the phospholipase C delta1 (PLCD1) protein expression is reduced in colorectal tumor tissues compared with paired surgical margin tissues. PLCD1‐promoted CpG methylation was detected in 29/64 (45%) primary colorectal tumors, but not in nontumor tissues. The PLCD1 RNA expression was also reduced in three out of six cell lines, due to PLCD1 methylation. The ectopic expression of PLCD1 resulted in inhibited proliferation and attenuated migration of colorectal tumor cells, yet promoted colorectal tumor cell apoptosis in vitro. We also observed that PLCD1 suppressed proliferation and promoted apoptosis in vivo. In addition, PLCD1 induced G1/S phase cell cycle arrest. Furthermore, we found that PLCD1 led to the downregulation of several factors downstream of β‐catenin, including c‐Myc and cyclin D1, which are generally known to be promoters of tumorigenesis. This downregulation was caused by an upregulation of E‐cadherin in colorectal tumor cells. Our findings provide insights into the role of PLCD1 as a tumor suppressor gene in colorectal cancer (CRC), and demonstrate that it plays significant roles in proliferation, migration, invasion, cell cycle progression, and epithelial‐mesenchymal transition. On the basis of these results, tumor‐specific methylation of PLCD1 could be used as a novel biomarker for early detection and prognostic prediction in CRC. [ABSTRACT FROM AUTHOR]

Background: Recently, emerging evidence has indicated crucial roles for long noncoding RNAs (lncRNAs) in breast cancer (BC) development and progression. Our study aimed to investigate the clinical significance of LINC01089 in patients with BC and to determine its biological functions and underlying molecular mechanisms. Materials and methods: Correlations between LINC01089 expression and the clinicopathological characteristics of BC patients were assessed using chi-square tests. The Kaplan-Meier method was used to produce survival curves. The clinical risk characteristics associated with the overall survival and recurrence-free survival of patients with BC were estimated using univariate and multivariate Cox regression analyses. Several methods were used to determine the expression profile, biological functions and underlying mechanisms of LINC01089 in BC, including cell proliferation assays, colony formation assays, flow cytometry, transwell assays, wound healing assays, quantitative real-time polymerase chain reaction and Western blotting. Results: LINC01089 was downregulated in BC tissues and cell lines. Low LINC01089 expression was significantly correlated with age (P=0.026), lymph node metastasis (P=0.003), and poor prognosis of patients with BC. According to the multivariate Cox regression analysis results, LINC01089 was an independent prognostic indicator of overall survival (P=0.032) and recurrence-free survival (P=0.014). Functional studies revealed significant decreases in the proliferation, migration, and invasion of tumor cells overexpressing LINC01089, and EGF could reverse above effects of LINC01089 on BC cells. Additionally, increased LINC01089 expression promoted apoptosis and cell cycle arrest at G0/G1 phase, accompanied by decreased expression of the key cell cycle regulators CDK4 and CDK6. Loss-of-function assays confirmed partial results. Mechanistically, LINC01089 blocked the Wnt/β-catenin pathway and the expression of downstream target genes by inhibiting β-catenin expression at the transcriptional level. Conclusion: Based on our results, LINC01089 functions as a tumor suppressor and potentially represents a novel prognostic indicator and therapeutic target in BC. [ABSTRACT FROM AUTHOR]

Background/Aims: Interferon consensus sequence-binding protein 8 (IRF8) belongs to a family of interferon (IFN) regulatory factors that modulates various important physiological processes including carcinogenesis. As reported by others and our group, IRF8 expression is silenced by DNA methylation in both human solid tumors and hematological malignancies. However, the role of IRF8 in lung carcinoma remains elusive. In this study, we determined IRF8 epigenetic regulation, biological functions, and the signaling pathway involved in non-small cell lung cancer (NSCLC). Methods: IRF8 expression were determined by Q- PCR. MSP and A+T determined promotor methylation. MTS, clonogenic, Transwell assay, Flow cytometry, three-dimensional culture and AO/EB stain verified cell function. In vivo tumorigenesis examed the in vivo effects. By Chip-QPCR, RT-PCR, Western blot and Immunofluorescence staining, the mechanisms were studied. Results: IRF8 was significantly downregulated in lung tumor tissues compared with adjacent non-cancerous tissues. Furthermore, methylation-specific PCR analyses revealed that IRF8 methylation in NSCLC was a common event, and demethylation reagent treatment proved that downregulation of IRF8 was due to its promoter CpG hypermethylation. Clinical data showed that the IRF8 methylation was associated with tumor stage, lymph node metastasis status, patient outcome, and tumor histology. Exogenous expression of IRF8 in the silenced or downregulated lung cancer cell lines A549 and H1299 at least partially restored the sensitivity of lung cancer cells to apoptosis, and arrested cells at the G0/G1 phase. Cell viability, clonogenicity, and cell migration and invasive abilities were strongly inhibited by restored expression of IRF8. A three-dimensional culture system demonstrated that IRF8 changed the cells to a more spherical phenotype. Moreover, ectopic expression of IRF8 enhanced NSCLC chemosensitivity to cisplatin. Furthermore, as verified by Chip-qPCR, immunofluorescence staining, and western blotting, IRF8 bound to the T-cell factor/lymphoid enhancer factor (TCF /LEF) promoter, thus repressing β-catenin nuclear translocation and its activation. IRF8 significantly disrupted the effects of Wnt agonist, bml284, further suggesting its involvement in the Wnt/β-catenin pathway. Conclusion: IRF8 acted as a tumor suppressor gene through the transcriptional repression of β-catenin-TCF/LEF in NSCLC. IRF8 methylation may serve as a potential biomarker in NSCLC prognosis. [ABSTRACT FROM AUTHOR]

Background/Aims: ADAMTS (disintegrin-like and metalloproteinase with thrombospondin motifs) proteins are extracellular zinc metalloproteinases that play an important role in extracellular matrix assembly and degradation, connective tissue structuring, angiogenesis, and cell migration. Multiple studies suggest that ADAMTS proteins (e.g. ADAMTS9) can act as tumor suppressors. In gastric, esophageal, and nasopharyngeal carcinomas ADAMTS9 is frequently down-regulated by promoter methylation. Whether ADAMTS9 can function as a tumor suppressor gene (TSG) in colorectal cancer is still unclear. Methods: We performed immunohistochemistry, RT-PCR, and qRT-PCR, to examine the expression of ADAMTS9 in colorectal cancer cell lines and primary colorectal cancer tissues. Methylation-specific PCR was also carried out to investigate the promoter methylation status of ADAMTS9. We also explored the functions of ADAMTS9 in colorectal cancer cell lines through in vitro experiments. Results: ADAMTS9 expression was down-regulated or silenced in 83.3% (5/6) of colorectal cancer cell lines, and frequently repressed in 65.6% (21/32) of colorectal cancer tissues. Down-regulation of ADAMTS9 was partially due to promoter methylation. Exogenous expression of ADAMTS9 in colorectal cancer cell lines inhibited cell proliferation and migration through the regulation of cell cycle and apoptosis. In addition, ADAMTS9 prevented the activation of Akt, and its downstream targets in colorectal cancer cell lines. Conclusion: Our findings suggest ADAMTS9 is a TSG in colorectal cancer. [ABSTRACT FROM AUTHOR]

ADAMTS18 dysregulation plays an important role in many disease processes including cancer. We previously found ADAMTS18 as frequently methylated tumor suppressor gene ( TSG) for multiple carcinomas, however, its biological functions and underlying molecular mechanisms in breast carcinogenesis remain unknown. Here, we found that ADAMTS18 was silenced or downregulated in breast cancer cell lines. ADAMTS18 was reduced in primary breast tumor tissues as compared with their adjacent noncancer tissues. ADAMTS18 promoter methylation was detected in 70.8% of tumor tissues by methylation-specific PCR, but none of the normal tissues. Demethylation treatment restored ADAMTS18 expression in silenced breast cell lines. Ectopic expression of ADAMTS18 in breast tumor cells resulted in inhibition of cell migration and invasion. Nude mouse model further confirmed that ADAMTS18 suppressed breast cancer metastasis in vivo. Further mechanistic studies showed that ADAMTS18 suppressed epithelial-mesenchymal transition ( EMT), further inhibited migration and invasion of breast cancer cells. ADAMT18 deregulated AKT and NF- κB signaling, through inhibiting phosphorylation levels of AKT and p65. Thus, ADAMTS18 as an antimetastatic tumor suppressor antagonizes AKT and NF- κB signaling in breast tumorigenesis. Its methylation could be a potential tumor biomarker for breast cancer. [ABSTRACT FROM AUTHOR]

The KRAB–zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect on Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. [ABSTRACT FROM AUTHOR]