The Overexpression of FEN1 and RAD54B May Act as Independent Prognostic Factors of Lung Adenocarcinoma

RNA-sequencing analysis reveals the potential molecular mechanism of RAD54B in the proliferation of inflamed human dental pulp cells

AIM

To investigate the role of RAD54B in the proliferation of inflamed human dental pulp cells (hDPCs) induced by lipopolysaccharide (LPS).

METHODOLOGY

Normal, carious and pulpitic human dental pulp tissues were collected. Total RNA was subjected to RNA-sequencing (seq) and gene expression profiles were studied by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Differentially expressed genes (DEGs) in homologous recombination repair (HRR) were validated with qRT-PCR. The expression of RAD54B and TNF-α in human dental pulp tissues was detected using immunohistochemistry. HDPCs were cultured and RAD54B level in hDPCs was detected after LPS stimulation using western blot. CCK-8 was used to investigate the proliferation of hDPCs transfected with negative control (Nc) small interfering RNA (siRNA), RAD54B siRNA, P53 siRNA or both siRNAs with or without LPS stimulation. Flow cytometry was used to detect the cell cycle distribution, and western blot and immunofluorescence were used to analyse the expression of RAD54B, P53 and P21 under the above treatments. One-way and two-way anova followed by least significant difference posttest were used for statistical analysis.

RESULTS

RNA-seq results identified DEGs amongst the three groups. KEGG pathway analysis revealed enrichment of DEGs in the replication and repair pathway. HRR and non-homologous end joining (NHEJ) components were further verified and qRT-PCR results were basically consistent with the sequencing data. RAD54B, an HRR accessory factor highly expressed in carious and pulpitic tissues as compared to that in normal pulps, was chosen as our gene of interest. High RAD54B expression was confirmed in inflamed human dental pulp tissues and LPS-stimulated hDPCs. Upon RAD54B knockdown, P53 and P21 expressions in hDPCs were upregulated whereas the proliferation was significantly downregulated, accompanied by increased G2/M phase arrest. After inhibiting P53 expression in RAD54B-knockdown hDPCs, P21 expression and cell proliferation were reversed.

CONCLUSIONS

Gene expression profiles of normal, carious and pulpitic human dental pulp tissues were revealed. HRR components were elucidated to function in dental pulp inflammation. Amongst the DEGs in HRR, RAD54B regulated the proliferation of inflamed hDPCs via P53/P21 signalling. This research deepens our understanding of dental pulp inflammation and provides new insight to clarify the underlying mechanisms.

The Clinical Significance of the Expression of FEN1 in Primary Osteosarcoma

PURPOSE

The aim of this research was to investigate the clinical significance of the expression of flap structure-specific endonuclease 1 (FEN1) in primary osteosarcoma.

METHODS

The expression of FEN1 was detected by immunohistochemistry analysis. The association of the expression of FEN1 in osteosarcoma with clinicopathological parameters was analyzed by using χ 2 test or Fisher's exact test. Survival analyses were performed by Kaplan-Meier method and Cox proportional hazards regression model.

RESULTS

Of the 40 osteosarcoma patients, 19 (47.5%) patients presented with FEN1 high expression, while in the non-neoplastic bone specimens, the FEN1 high expression was observed in 10% (3/30), the positive expression rate in osteosarcoma patients was significantly higher than that of non-neoplastic bone specimens (P< 0.01). Univariate analysis indicated that the progression-free survival (PFS) and overall survival (OS) were correlated with the expression level of FEN1 (PFS, P < 0.001; OS, P = 0.002), Enneking staging (PFS, P = 0.026; OS, P = 0.044) and chemotherapy response (PFS, P = 0.019; OS, P = 0.031). Multivariate analysis demonstrated that FEN1 expression was an independent prognostic factor for the PFS (HR = 4.73, P = 0.002) and OS (HR = 4.01, P = 0.038) of osteosarcoma patients.

CONCLUSION

This study showed that FEN1 was overexpressed in osteosarcoma patients and positively associated with poor prognosis of osteosarcoma patients. Further studies should focus on the relative mechanisms and the targeted FEN1 therapies for osteosarcoma.

Integrated bioinformatics analysis reveals CDK1 and PLK1 as potential therapeutic targets of lung adenocarcinoma

ABSTRACT

This study is to identify potential biomarkers and therapeutic targets for lung adenocarcinoma (LUAD).GSE6044 and GSE118370 raw data from the Gene Expression Omnibus database were normalized with Robust Multichip Average. After merging these two datasets, the combat function of sva packages was used to eliminate batch effects. Then, limma packages were used to filtrate differentially expressed genes. We constructed protein-protein interaction relationships using STRING database and hub genes were identified based on connectivity degrees. The cBioportal database was used to explore the alterations of the hub genes. The promoter methylation of cyclin dependent kinase 1 (CDK1) and polo-like Kinase 1 (PLK1) and their association with tumor immune infiltration in patients with LUAD were investigated using DiseaseMeth version 2.0 and TIMER databases. The Cancer Genome Atlas-LUAD dataset was used to perform gene set enrichment analysis.We identified 10 hub genes, which were upregulated in LUAD, among which 8 were successfully verified in the Cancer Genome Atlas and Oncomine databases. Kaplan-Meier analysis indicated that the expressions of CDK1 and PLK1 in LUAD patients were associated with overall survival and disease-free survival. The methylation levels in the promoter regions of these 2 genes in LUAD patients were lower than those in normal lung tissues. Their expressions in LUAD were associated with tumor stages and relative abundance of tumor infiltrating immune cells, such as B cells, CD4+ T cells, and macrophages. Moreover, cell cycle, DNA replication, homologous recombination, mismatch repair, P53 signaling pathway, and small cell lung cancer signaling were significantly enriched in CDK1 and PLK1 high expression phenotype.CDK1 and PLK1 may be used as potential biomarkers and therapeutic targets for LUAD.

High Expression of MTA1 Predicts Unfavorable Survival in Patients With Oral Squamous Cell Carcinoma

BACKGROUND/AIM

Metastasis-associated protein 1 (MTA1) plays a role in ATP-dependent nucleosome disruption activity and histone deacetylase activity and may indicate DNA methylation activity. MTA1 may also be involved in the progression of oral squamous cell carcinoma (OSCC).

PATIENTS AND METHODS

MTA1 immunoreactivity was analyzed using immunohistochemical (IHC) staining analysis in specimens from 281 OSCC patients. Kaplan-Meier analysis was used to determine the prognostic value of MTA1 for overall survival.

RESULTS

High MTA1 expression was significantly associated with female gender and lymph node metastasis. Multivariate analyses showed the independent prognostic role of high MTA1 expression in patients with OSCC of poorer mean survival.

CONCLUSION

MTA1 expression, detected by IHC staining, could be an independent prognostic marker for patients of OSCC.

Amplification of RAD54B promotes progression of hepatocellular carcinoma via activating the Wnt/β-catenin signaling

Liver cancer was reported to be the sixth most frequently diagnosed cancer, and hepatocellular carcinoma (HCC) accounts for 75%-85% of primary liver cancer. Nevertheless, the concrete molecular mechanisms of HCC progression remain obscure, which is essential to elucidate. The expression profile of RAD54B in HCC was measured using qPCR and western blotting. Moreover, the levels of RAD54B in paraffin-embedded samples were evaluated using immunohistochemistry (IHC). The effect of RAD54B on HCC progression was testified by in vitro experiments, and in vivo orthotopic xenograft tumor experiments. The mechanisms of RAD54B promoting HCC progression were investigated through molecular and function experiments. Herein, RAD54B are dramatically upregulated in HCC tissues and cell lines both on mRNA and protein levels, and RAD54B can servers as an independent prognostic parameter of 5-year overall survival and 5-year disease-free survival for patients with HCC. Moreover, up-regulation of RAD54B dramatically increases the capacity for in vitro cell viability and motility, and in vivo intrahepatic metastasis of HCC cells. Mechanistically, RAD54B promotes the HCC progression through modulating the wnt/β-catenin signaling. Notably, blocking the wnt/β-catenin signaling axis can counteract the activating effects of RAD54B on motility of HCC cells. Besides, further analysis illustrates that DNA amplification is one of the mechanisms leading to mRNA overexpression of RAD54B in HCC. Our findings indicate that RAD54B might be a promising potential prognostic marker and a candidate therapeutic target to therapy HCC.

Integrated genomics and comprehensive validation reveal drivers of genomic evolution in esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is associated with a marked genomic instability, which underlies disease progression and development of resistance to treatment. In this study, we used an integrated genomics approach to identify a genomic instability signature. Here we show that elevated expression of this signature correlates with poor survival in EAC as well as three other cancers. Knockout and overexpression screens establish the relevance of these genes to genomic instability. Indepth evaluation of three genes (TTK, TPX2 and RAD54B) confirms their role in genomic instability and tumor growth. Mutational signatures identified by whole genome sequencing and functional studies demonstrate that DNA damage and homologous recombination are common mechanisms of genomic instability induced by these genes. Our data suggest that the inhibitors of TTK and possibly other genes identified in this study have potential to inhibit/reduce growth and spontaneous as well as chemotherapy-induced genomic instability in EAC and possibly other cancers.

Subodh Kumar et al. identify a gene signature correlated with genomic instability and poor survival in esophageal adenocarcinoma (EAC), using a combination of integrative genomic analysis of patient data and laboratory validation in cell line models and mice. They find that inhibitors of some of the identified proteins, including TTK, could be used to reduce genomic evolution as well as inhibit growth of EAC cells.

Flap endonuclease 1 (FEN1) as a novel diagnostic and prognostic biomarker for gastric cancer

OBJECTIVE

Flap endonuclease 1 (FEN1) overexpression has been reported to be closely associated with cancer prognosis. However, its diagnostic and prognostic significance in gastric cancer (GC) has not yet been explored.

METHODS

FEN1 expression, its correlation with clinical parameters, and prognostic significance were investigated by data mining of The Cancer Genome Atlas (TCGA) datasets. Patients were divided into low- and high-expression groups using the median value of FEN1 expression as the cut-off. The diagnostic value of FEN1 expression in GC tissues was determined via receiver operating characteristic (ROC) curve analysis. Univariate and multivariate Cox regression analyses were used to identify the prognostic indicators. Gene set enrichment analysis (GSEA) was used to explore FEN1-related signalling pathways in GC. Furthermore, the Human Protein Atlas (HPA) database and GSE62254 dataset were used for further external validation.

RESULTS

FEN1 was expressed at a higher level in GC tissues than in normal gastric tissues with high diagnostic accuracy (area under the ROC=0.909). Higher FEN1 expression was also validated at the protein level using the HPA database. High FEN1 expression in GC was correlated with older age (P<0.05). Patients with high FEN1 expression had a favourable prognosis compared to patients with low FEN1 expression (P=0.0048). Univariate and multivariate analyses revealed that FEN1 was an independent predictive factor associated with overall survival in both the TCGA cohort and the GSE62254 dataset (P=0.0004 and P=0.011, respectively). GSEA identified that the FEN1 expression was related to DNA replication, cell cycle, cytosolic and sensing pathways, oocyte meiosis, and the P53 signalling pathway.

CONCLUSION

The results revealed high expression of FEN1 in GC; thus, it could be a promising early diagnostic and independent prognostic biomarker for GC.

High Expression of KLF10 Is Associated with Favorable Survival in Patients with Oral Squamous Cell Carcinoma

Background and Objectives: Krüppel-like transcription factor 10 (KLF10) plays a vital role in regulating cell proliferation, including the anti-proliferative process, activation of apoptosis, and differentiation control. KLF10 may also act as a protective factor against oral cancer. We studied the impact of KLF10 expression on the clinical outcomes of oral cancer patients to identify its role as a prognostic factor in oral cancer. Materials and Methods: KLF10 immunoreactivity was analyzed by immunohistochemical (IHC) stain analysis in 286 cancer specimens from primary oral cancer patients. The prognostic value of KLF10 on overall survival was determined by Kaplan–Meier analysis and the Cox proportional hazard model. Results: High KLF10 expression was significantly associated with male gender and betel quid chewing. The 5-year survival rate was greater for patients with high KLF10 expression than for those with low KLF10 expression (62.5% vs. 51.3%, respectively; p = 0.005), and multivariate analyses showed that high KLF10 expression was the only independent factor correlated with greater overall patient survival. The significant correlation between high KLF10 expression and a higher 5-year survival rate was observed in certain subgroups of clinical parameters, including female gender, non-smokers, cancer stage T1, and cancer stage N0. Conclusions: KLF10 expression, detected by IHC staining, could be an independent prognostic marker for oral cancer patients.

Biological and clinical significance of flap endonuclease‑1 in triple‑negative breast cancer: Support of metastasis and a poor prognosis

Flap endonuclease‑1 (FEN1), a structure‑specific nuclease participating in DNA replication and repair processes, has been confirmed to promote the proliferation and drug resistance of tumor cells. However, the biological functions of FEN1 in cancer cell migration and invasion have not been defined. In the present study, using online database analysis and immunohistochemistry of the specimens, it was found that FEN1 expression was associated with a highly invasive triple‑negative breast cancer (TNBC) subtype in both breast cancer samples from the Oncomine database and from patients recruited into the study. Furthermore, FEN1 was an important biomarker of lymph node metastasis and poor prognosis in patients with TNBC. FEN1 promoted migration of TNBC cell lines and FEN1 knockdown reduced the number of spontaneous lung metastasis in vivo. Ingenuity Pathway Analysis of FEN1‑related transcripts in 198 patients with TNBC demonstrated that the polo‑like kinase family may be the downstream target of FEN1. PLK4 was further identified as a critical target of FEN1 mediating TNBC cell migration, by regulating actin cytoskeleton rearrangement. The results of the present study validate FEN1 as a therapeutic target in patients with TNBC and revealed a new role for FEN1 in regulating TNBC invasion and metastasis.

Overexpression of KLF17 Predicts a Favorable Prognosis in Patients with Oral Squamous Cell Carcinoma: A Retrospective Study

Background and Objectives: Patients with oral squamous cell carcinoma (OSCC), a common malignancy in Asian countries, have a poor prognosis. We investigated the role of Krüppel-like factor 17 (KLF17) and its prognostic significance in OSCC. Materials and Methods: KLF17 expression was measured by immunohistochemical staining of specimens from 283 patients with OSCC. We analyzed correlations between KLF17 expression and clinicopathologic features and between KLF17 expression and overall survival. The prognostic value of KLF17 was tested using Kaplan–Meier analysis and Cox proportional hazard models. Results: Among the 283 patients, high KLF17 expression was significantly associated with an early OSCC stage and low T-value (p = 0.033 and p = 0.036, respectively). The five-year survival rates were better in patients with high KLF17 expression than with low expression (66.5% and 49.6%, respectively). The prognostic role of KLF17 was further confirmed through multivariate analysis (hazard ratio 1.506, 95% confidence interval 1.034–2.191, p = 0.033). The prognostic value was more significant in patients with a history of betel quid chewing or with a low T-value. Conclusions: High KLF17 expression can serve as a marker for a favorable prognosis in patients with OSCC. The prognostic role of KLF17 is more significant in patients with a history of betel quid chewing or a low T-value.

Upregulation of FEN1 Is Associated with the Tumor Progression and Prognosis of Hepatocellular Carcinoma

Background

Studies show that patients with hepatocellular carcinoma (HCC) have poor prognosis, particularly when patients are diagnosed at late stages of the disease development. The flap endonuclease 1 (FEN1) gene is overexpressed in multiple malignant tumors and may promote tumor aggressiveness. However, its expression profile and functional roles in HCC are still unclear. Here, we evaluated the molecular mechanisms of FEN1 in HCC.

Methods

The expression of FEN1 in HCC was evaluated using HCC mRNA expression data from TCGA and GEO databases. The expression of FEN1 was also confirmed by immunohistochemistry (IHC) using a tissue microarray (TMA) cohort with a total of 396 HCC patients. Kaplan-Meier analysis and univariate and multivariate Cox regression analyses were used to determine the correlation between FEN1 expression and survival rate of HCC patients. The molecular mechanism and biological functions of FEN1 in HCC were predicted using functional and pathway enrichment analysis in vitro experiments.

Results

FEN1 was overexpressed in multiple HCC cohorts at both mRNA and protein levels. The receiver operating characteristic (ROC) curve showed that FEN1 can serve as a diagnostic predictor of HCC. Meanwhile, patients with high FEN1 expression levels showed lower overall survival (OS) and relapse-free survival (RFS) rates than those with low FEN1 expression. More importantly, we found that FEN1 elevation was an independent prognostic factor for OS and RFS in HCC patients based on univariate and multivariate analyses, indicating that FEN1 might be a potential prognostic marker in HCC. Furthermore, knocking down FEN1 resulted in suppressed cell proliferation and migration in vitro. This could have been due to regulation expressions of c-Myc, survivin, and cyclin D1 genes, indicating that FEN1 may function as an oncogene through its role in the cell cycle and DNA replication pathway.

Conclusion

Our study indicated that high FEN1 expression might function as a biomarker for diagnosis and prognosis. In addition, the study confirms that FEN1 is an oncogene in HCC progression.

Knockdown of RAD54B expression reduces cell proliferation and induces apoptosis in lung cancer cells

Objective

RAD54 homolog B (RAD54B), a member of the SNF2/SWI2 superfamily, is implicated in homologous recombination, and high RAD54B expression predicts the prognostic outcomes of lung adenocarcinoma. However, its role in lung carcinogenesis was unclear so this was determined in the present study.

Methods

We evaluated the gene and protein expression of RAD54B in 15 lung adenocarcinoma tissues and matched adjacent healthy lung tissues by real-time PCR, immunohistochemical staining, and western blotting. A549 lung cancer cells were transduced with lentivirus carrying small hairpin RNA (shRNA) against RAD54B (shRAD54B) or control shRNA (shCtrl), and cell proliferation, viability, apoptosis, and caspase 3/7 activity were evaluated.

Results

RAD54B protein expression was significantly higher in lung adenocarcinoma tissues than in healthy lung tissues. RAD54B gene expression was high in A549 cells but was efficiently knocked down using shRAD54B with an infection efficiency of 80% and a knockdown ratio of 72.2% compared with shCtrl. Suppressing RAD54B expression in A549 cells significantly reduced cell proliferation and caspase 3/7 activity, and significantly increased the apoptotic rate.

Conclusions

RAD54B exerts an oncogenic role in lung cancer cell proliferation.

Identification of Flap endonuclease 1 as a potential core gene in hepatocellular carcinoma by integrated bioinformatics analysis

Hepatocellular carcinoma (HCC) is a common yet deadly form of malignant cancer. However, the specific mechanisms involved in HCC diagnosis have not yet fully elucidated. Herein, we screened four publically available Gene Expression Omnibus (GEO) expression profiles (GSE14520, GSE29721, GSE45267 and GSE60502), and used them to identify 409 differentially expressed genes (DEGs), including 142 and 267 up- and down-regulated genes, respectively. The DAVID database was used to look for functionally enriched pathways among DEGs, and the STRING database and Cytoscape platform were used to generate a protein-protein interaction (PPI) network for these DEGs. The cytoHubba plug-in was utilized to detect 185 hub genes, and three key clustering modules were constructed with the MCODE plug-in. Gene functional enrichment analyses of these three key clustering modules were further performed, and nine core genes including BIRC5, DLGAP5, DTL, FEN1, KIAA0101, KIF4A, MCM2, MKI67, and RFC4, were identified in the most critical cluster. Subsequently, the hierarchical clustering and expression of core genes in TCGA liver cancer tissues were analyzed using the UCSC Cancer Genomics Browser, and whether elevated core gene expression was linked to a poor prognosis in HCC patients was assessed using the GEPIA database. The PPI of the nine core genes revealed an interaction between FEN1, MCM2, RFC4, and BIRC5. Furthermore, the expression of FEN1 was positively correlated with that of three other core genes in TCGA liver cancer tissues. FEN1 expression in HCC and other tumor types was assessed with the FIREBROWSE and ONCOMINE databases, and results were verified in HCC samples and hepatoma cells. FEN1 levels were also positively correlated with tumor size, distant metastasis and vascular invasion. In conclusion, we identified nine core genes associated with HCC development, offering novel insight into HCC progression. In particular, the aberrantly elevated FEN1 may represent a potential biomarker for HCC diagnosis and treatment.

RAD54B potentiates tumor growth and predicts poor prognosis of patients with luminal A breast cancer

RAD54B, a human paralog of RAD54 L, belongs to the SW12/SNF2 superfamily of helicases. Up to now, few studies have reported the role of RAD54B in breast cancer (BC). In this study, we reported that RAD54B was amplified and the expression of RAD54B was elevated in BC, as identified through a bioinformatics analysis of open databases (cBioPortal and Oncomine) and an immunohistochemical analysis of a tissue microarray (TMA). Analysis of Kaplan-Meier plotter (KM plotter) showed that high RAD54B transcription activity was critically linked with poor prognosis of BC patients, in particular those with the luminal A subtype. Gene set enrichment analysis (GSEA) performed on dataset GSE1456 demonstrated that gene expression signatures associated with survival, proliferation, cell cycle, apoptosis and p53 signaling were crucially enriched, when the level of RAD54B was elevated. Further, gain-of-function studies were conducted on luminal A BC cell lines MCF-7 and ZR-751 to validate these findings. Consistently, RAD54B knockdown suppressed cell proliferation in vitro, as well as delayed tumor growth in vivo. Collectively, our results address the biological role of RAD54B in the neoplastic process of luminal A BC. Bioinformatics analysis, additionally, indicates RAD54B with a predictive value for this BC subtype.

Flap endonuclease overexpression drives genome instability and DNA damage hypersensitivity in a PCNA-dependent manner

Overexpression of the flap endonuclease FEN1 has been observed in a variety of cancer types and is a marker for poor prognosis. To better understand the cellular consequences of FEN1 overexpression we utilized a model of its Saccharomyces cerevisiae homolog, RAD27. In this system, we discovered that flap endonuclease overexpression impedes replication fork progression and leads to an accumulation of cells in mid-S phase. This was accompanied by increased phosphorylation of the checkpoint kinase Rad53 and histone H2A-S129. RAD27 overexpressing cells were hypersensitive to treatment with DNA damaging agents, and defective in ubiquitinating the replication clamp proliferating cell nuclear antigen (PCNA) at lysine 164. These effects were reversed when the interaction between overexpressed Rad27 and PCNA was ablated, suggesting that the observed phenotypes were linked to problems in DNA replication. RAD27 overexpressing cells also exhibited an unexpected dependence on the SUMO ligases SIZ1 and MMS21 for viability. Importantly, we found that overexpression of FEN1 in human cells also led to phosphorylation of CHK1, CHK2, RPA32 and histone H2AX, all markers of genome instability. Our data indicate that flap endonuclease overexpression is a driver of genome instability in yeast and human cells that impairs DNA replication in a manner dependent on its interaction with PCNA.

Correlation between EZH2 and CEP55 and lung adenocarcinoma prognosis

OBJECTIVE

Recently, accumulated evidence indicates that the enhancer of zeste homologue 2 (EZH2) is highly expressed in a wide range of cancer types, including NSCLC. The downstream genes regulated by EZH2 were screened using bioinformatics analysis. This study aimed to analyse the correlation between the downstream genes of EZH2 and the prognosis of lung adenocarcinoma.

METHODS

Expression and methylation data of lung adenocarcinoma were downloaded from The Cancer Genome Atlas (TCGA) (https://cancergenome.nih.gov/) database, and data were categorized into EZH2 overexpression and EZH2 downregulation groups according to EZH2 expression. The genes that showed opposite trends of methylation and expression changes were screened, and the association of gene expression was calculated. Based on the String database, a protein association analysis was conducted to identify genes related to EZH2, which are referred to as EZH2 regulation candidate genes. According to gene expression (GSE27262) and methylation (GSE66836) chip data in the Gene Expression Omnibus (GEO) (https://www.ncbi.nlm.nih.gov/geo/) database, the genes with differential expression and methylation in lung adenocarcinoma tissues were analysed, and the trends of EZH2 regulation candidate gene expression and methylation were verified to identify the EZH2 regulation candidate genes. Subsequently, MethHC (http://methhc.mbc.nctu.edu.tw/php/index.php) and UALCAN (http://ualcan.path.uab.edu/index.html) were employed to verify changes in the expression and methylation of EZH2 downstream regulation candidate genes and to analyse the correlation between these genes and the prognosis of lung adenocarcinoma.

RESULTS

Expression and methylation data of lung adenocarcinoma were downloaded from TCGA database and categorized into EZH2 overexpression and EZH2 downregulation groups according to EZH2 expression. A total of 337 genes that showed opposite trends of methylation and expression changes were obtained. The protein association analysis using the String (https://string-db.org/) database showed that 61 genes interact with EZH2 and 61 genes represent EZH2 downstream regulation candidate genes. Moreover, 222 genes obtained from GSE27262 and GSE66836 chip data were negatively correlated with methylation and expression changes, and centrosomal protein 55 (CEP55) was identified as the EZH2 downstream regulation candidate gene. CEP55 was upregulated in lung adenocarcinoma tissues and showed low methylation. According to gene expression data from TCGA database, CEP55 and EZH2 exhibit higher levels in lung adenocarcinoma tissue than in adjacent normal tissue. Finally, the survival analysis revealed that EZH2 is not associated with the prognosis of lung adenocarcinoma, while CEP55 is related to lung adenocarcinoma prognosis.

CONCLUSION

Taken together, these results indicate that changes in EZH2 expression lead to changes in CEP55 expression in lung adenocarcinoma, and these changes are associated with its prognosis.

Inhibition of RAD54B suppresses proliferation and promotes apoptosis in hepatoma cells

RAD54 homolog B is a central motor protein of homologous recombination (HR), which plays an important role in the development and evolution of human cancer. Recent studies have indicated that RAD54B is aberrantly expressed in a variety of cancers and exhibits numerous biological functions, including participating in the repair of DNA double strand breaks. However, the expression and function of RAD54B in liver cancer have not yet been reported. The aim of the present study was to investigate the expression of RAD54B and elucidate its role in liver cancer cell lines by inhibiting RAD54B using a lentivirus-mediated shRNA interference system. We also assessed the effect of RAD54B on cell proliferation, colony formation, cell cycle distribution and cell apoptosis in BEL-7404 and SMMC-7721 cell lines using shRAD54B or shCtrl transfection. Furthermore, we analyzed the relationship between the expression of RAD54B protein, as measured by immunohistochemical staining, and the prognosis of patients with hepatoma. We found that RAD54B was highly expressed in liver cancer cell lines compared with the normal hepatic cell line LO2. Similarly, positive expression of RAD54B, which is associated with poor prognosis, was also observed in 52/83 samples of liver cancer tissue. Additionally, RAD54B downregulation significantly inhibited cell proliferation and colony formation, while also inducing G1/S cell cycle arrest and apoptosis in BEL-7404 and SMMC-7721 cells. These results indicated that RAD54B has oncogenic properties, and may be a potential treatment target for liver cancer patients.

Validation of EGFL6 expression as a prognostic marker in patients with lung adenocarcinoma in Taiwan: a retrospective study

OBJECTIVE

Lung adenocarcinoma is a non-small cell lung cancer, a common cancer in both genders, and has poor clinical outcome. Our aim was to evaluate the role of epidermal growth factor (EGF)-like domain multiple 6 (EGFL6) and its prognostic significance in lung adenocarcinoma.

METHODS

EGFL6 expression was studied by immunohistochemical staining of specimens from 150 patients with lung adenocarcinoma. The correlation between clinicopathological features and EGFL6 expression was quantitatively analysed. We used Kaplan-Meier analysis and Cox proportional hazard models to examine the prognostic value of EGFL6 in terms of overall survival.

RESULTS

No significant correlation was found between EGFL6 expression and clinical parameters. However, patients with high levels of EGFL6 expression showed a tendency towards poor prognosis, with borderline statistical significance. Grouping the patients according to a medium age value revealed a significant association between high EGFL6 expression and poor clinical outcome in young patients. This finding was further confirmed by grouping the patients into three groups according to age. HR in patients with high EGFL6 expression was higher in younger patients than in older patients.

CONCLUSION

High EGFL6 expression may serve as a marker for poor prognosis of lung adenocarcinoma, especially in younger patients.

Eight potential biomarkers for distinguishing between lung adenocarcinoma and squamous cell carcinoma

Lung adenocarcinoma (LADC) and squamous cell carcinoma (LSCC) are the most common non-small cell lung cancer histological phenotypes. Accurate diagnosis distinguishing between these two lung cancer types has clinical significance. For this study, we analyzed four Gene Expression Omnibus (GEO) datasets (GSE28571, GSE37745, GSE43580, and GSE50081). We then imported the datasets into the Gene-Cloud of Biotechnology Information online platform to identify genes differentially expressed in LADC and LSCC. We identified DSG3 (desmoglein 3), KRT5 (keratin 5), KRT6A (keratin 6A), KRT6B (keratin 6B), NKX2-1 (NK2 homeobox 1), SFTA2 (surfactant associated 2), SFTA3 (surfactant associated 3), and TMC5 (transmembrane channel-like 5) as potential biomarkers for distinguishing between LADC and LSCC. Receiver operating characteristic curve analysis suggested that KRT5 had the highest diagnostic value for discriminating between these two cancer types. Using the PrognoScan online survival analysis tool and the Kaplan-Meier Plotter, we found that high KRT6A or KRT6B levels, or low NKX2-1, SFTA3, or TMC5 levels correlated with unfavorable prognoses in LADC patients. Further studies will be needed to verify our findings in additional patient samples, and to elucidate the mechanisms of action of these potential biomarkers in non-small cell lung cancer.

Cellularly active N-hydroxyurea FEN1 inhibitors block substrate entry to the active site

The structure-specific nuclease human flap endonuclease-1 (hFEN1) plays a key role in DNA replication and repair and may be of interest as an oncology target. We present the crystal structure of inhibitor-bound hFEN1, which shows a cyclic N-hydroxyurea bound in the active site coordinated to two magnesium ions. Three such compounds had similar IC50 values but differed subtly in mode of action. One had comparable affinity for protein and protein-substrate complex and prevented reaction by binding to active site catalytic metal ions, blocking the necessary unpairing of substrate DNA. Other compounds were more competitive with substrate. Cellular thermal shift data showed that both inhibitor types engaged with hFEN1 in cells, and activation of the DNA damage response was evident upon treatment with inhibitors. However, cellular EC50 values were significantly higher than in vitro inhibition constants, and the implications of this for exploitation of hFEN1 as a drug target are discussed.