Candidate Tumor Suppressor Research Articles

Longitudinal study of leukocyte DNA methylation and biomarkers for cancer risk in older adults

BackgroundChanges in DNA methylation over the course of life may provide an indicator of risk for cancer. We explored longitudinal changes in CpG methylation from blood leukocytes, and likelihood of future cancer diagnosis.MethodsPeripheral blood samples were obtained at baseline and at follow-up visit from 20 participants in the Health, Aging and Body Composition prospective cohort study. Genome-wide CpG methylation was assayed using the Illumina Infinium Human MethylationEPIC (HM850K) microarray.ResultsGlobal patterns in DNA methylation from CpG-based analyses showed extensive changes in cell composition over time in participants who developed cancer. By visit year 6, the proportion of CD8+ T-cells decreased (p-value = 0.02), while granulocytes cell levels increased (p-value = 0.04) among participants diagnosed with cancer compared to those who remained cancer-free (cancer-free vs. cancer-present: 0.03 ± 0.02 vs. 0.003 ± 0.005 for CD8+ T-cells; 0.52 ± 0.14 vs. 0.66 ± 0.09 for granulocytes). Epigenome-wide analysis identified three CpGs with suggestive p-values ≤10− 5 for differential methylation between cancer-free and cancer-present groups, including a CpG located in MTA3, a gene linked with metastasis. At a lenient statistical threshold (p-value ≤3 × 10− 5), the top 10 cancer-associated CpGs included a site near RPTOR that is involved in the mTOR pathway, and the candidate tumor suppressor genes REC8, KCNQ1, and ZSWIM5. However, only the CpG in RPTOR (cg08129331) was replicated in an independent data set. Analysis of within-individual change from baseline to Year 6 found significant correlations between the rates of change in methylation in RPTOR, REC8 and ZSWIM5, and time to cancer diagnosis.ConclusionThe results show that changes in cellular composition explains much of the cross-sectional and longitudinal variation in CpG methylation. Additionally, differential methylation and longitudinal dynamics at specific CpGs could provide powerful indicators of cancer development and/or progression. In particular, we highlight CpG methylation in the RPTOR gene as a potential biomarker of cancer that awaits further validation.

LncRNA TUSC8 inhibits the invasion and migration of cervical cancer cells via miR‐641/PTEN axis

Cervical cancer (CC) is the fourth leading cause of cancer-related death in women worldwide. There is an urgent need to find novel targets for the treatment of CC. Recently, microRNA have emerged as critical factors in tumorigenesis. In this study, we aimed to investigate the mechanism of miR-641 on the migration and invasion of CC cells. In silico analysis revealed putative interaction between miR-641 and phosphatase and tensin homolog (PTEN) RNA/lncRNA tumor suppressor candidate 8 (TUSC8). Hence we evaluated the expression of TUSC8, miR-641, and PTEN. We found that the expressions of TUSC8 and PTEN were decreased in CC tissues, whereas miR-641 expression was increased. Inhibition of miR-641 suppressed the migration and invasion of Hela cells. In addition, TUSC8 and PTEN were upstream and downstream target molecule of miR-641, respectively. Overexpression of TUSC8 promoted PTEN expression, and suppressed the invasion and migration of Hela cells, whereas miR-641 mimic treatment changed the effects. These results demonstrated that overexpression of TUSC8 could inhibit the invasion and migration of CC cells by upregulating PTEN via miR-641.

ING3 is required for ATM signaling and DNA repair in response to DNA double strand breaks

Inhibitor of Growth 3 (ING3) is a candidate tumor suppressor gene whose expression is lost in tumors such as hepatocellular carcinoma, head and neck squamous cell carcinoma and melanoma. In the present study, we show that ING3-depleted human cells and yeast cells deleted for its ortholog YNG2 are sensitive to DNA damage suggesting a conserved role in response to such stress. In human cells, ING3 is recruited to DNA double strand breaks and is required for ATM activation. Remarkably, in response to doxorubicin, ATM activation is dependent on ING3 but not on TIP60, whose recruitment to DNA breaks also depends on ING3. These events lead to ATM-mediated phosphorylation of NBS1 and the subsequent recruitment of RNF8, RNF168, 53BP1, and BRCA1, which are major mediators of the DNA damage response. Accordingly, upon genotoxic stress, DNA repair by non-homologous end joining (NHEJ) or homologous recombination (HR) were impaired in absence of ING3. Finally, immunoglobulin class switch recombination (CSR), a physiological mechanism requiring NHEJ repair, was impaired in the absence of ING3. Since deregulation of DNA double strand break repair is associated with genomic instability, we propose a novel function of ING3 as a caretaker tumor suppressor involved in the DNA damage signaling and repair.

Propofol-induced miR-219-5p inhibits growth and invasion of hepatocellular carcinoma through suppression of GPC3-mediated Wnt/β-catenin signalling activation.

Propofol is one of the most extensively used intravenous anaesthetic agents, which has been found to improve the surgical intervention outcome of several types of cancer, including hepatocellular carcinoma (HCC). Additionally, in vitro and in vivo experiments have also indicated that propofol affects the biological behaviour of HCC. However, the underlying mechanisms of the surgical resection of HCC with propofol have not been fully understood. In the present study, we aimed to investigate the underlying mechanism of propofol inhibition of the growth and invasion of HCC cells. Our results showed that treatment with propofol suppressed the proliferation, invasion and migration of HCC in vitro. The subcutaneous xenograft tumour and orthotopic xenograft tumour experiments in nude mice showed that propofol significantly decreased tumour volumes, growth rates and the liver orthotopic xenograft tumour in vivo. Furthermore, the underlying mechanism investigations of the suppressive effects of propofol on HCC cells revealed that propofol treatment upregulated the expression levels of the candidate tumour suppressor miR-219-5p. Silencing of propofol-induced miR-219-5p using anti-miR-219-5p abrogated the inhibitory effects on the proliferation, migration and invasion of HCC cells exerted by propofol treatment. Additionally, we demonstrated that propofol reversed the epithelial-mesenchymal transition of Huh7 and SMMC7721 cells via miR-219-5p induction. The molecular mechanism behind these findings is that propofol-induced miR-219-5p inhibits HCC cell progression by targeting glypican-3 and subsequently resultsin the inhibition of Wnt/β-catenin signalling. Taken together, our study provides new insights into the advantages of the surgical intervention of HCC with propofol anaesthetization.

The PHLPP2 phosphatase is a druggable driver of prostate cancer progression.

Metastatic prostate cancer commonly presents with targeted, bi-allelic mutations of the PTEN and TP53 tumor suppressor genes. In contrast, however, most candidate tumor suppressors are part of large recurrent hemizygous deletions, such as the common chromosome 16q deletion, which involves the AKT-suppressing phosphatase PHLPP2. Using RapidCaP, a genetically engineered mouse model of Pten/Trp53 mutant metastatic prostate cancer, we found that complete loss of Phlpp2 paradoxically blocks prostate tumor growth and disease progression. Surprisingly, we find that Phlpp2 is essential for supporting Myc, a key driver of lethal prostate cancer. Phlpp2 dephosphorylates threonine-58 of Myc, which renders it a limiting positive regulator of Myc stability. Furthermore, we show that small-molecule inhibitors of PHLPP2 can suppress MYC and kill PTEN mutant cells. Our findings reveal that the frequent hemizygous deletions on chromosome 16q present a druggable vulnerability for targeting MYC protein through PHLPP2 phosphatase inhibitors.

Dysregulation of miR484-TUSC5 axis takes part in the progression of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. miR-484 is previously reported to be a crucial modulator during the process from precancerous lesion to cancer. Tumour suppressor candidate 5 (TUSC5) is a potential tumour suppressor, but its expression and function in HCC are obscure. In this study, we aimed to explore the roles of miR-484 and TUSC5 in HCC, and clarify the relationship between them. We demonstrated that miR-484 was significantly up-regulated in HCC, while TUSC5 was down-regulated. TUSC5 was validated as the target gene of miR-484 and both of them were associated with the prognosis of HCC patients. miR-484 mimics markedly promoted the malignant phenotypes while TUSC5 plasmid had the opposite effect. In conclusion, miR-484/TUSC5 is potential diagnostic biomarkers and therapy targets for HCC.

Downregulation of CYB5D2 is associated with breast cancer progression

We report here that CYB5D2 is associated with tumor suppression function in breast cancer (BC). CYB5D2 expression was significantly reduced in tamoxifen resistant MCF7 cells and in MCF7 cell-derived xenografts treated with TAM. CYB5D2 overexpression induced apoptosis in MCF7 cells; CYB5D2 knockdown enhanced MCF7 cell proliferation. Using the TCGA and Curtis datasets within the Oncomine database, CYB5D2 mRNA expression was downregulated in primary BCs vs breast tissues and HER2-positive or triple negative BCs vs estrogen receptor (ER)-positive BCs. Using the TCGA and Metabric datasets (n = 817 and n = 2509) within cBioPortal, 660 and 4891 differentially expressed genes (DEGs) in relation to CYB5D2 were identified. These DEGs were enriched in pathways governing cell cycle progression, progesterone-derived oocyte maturation, oocyte-meiosis, estrogen-mediated S-phase entry, and DNA metabolism. CYB5D2 downregulation decreased overall survival (OS, p = 0.0408). A CYB5D2-derived 21-gene signature was constructed and robustly correlated with OS shortening (p = 5.72e-12), and independently predicted BC deaths (HR = 1.28; 95% CI 1.08–1.52; p = 0.004) once adjusting for known clinical factors. CYB5D2 reductions displayed relationship with mutations in PIK3CA, GATA3, MAP3K1, CDH1, TP53 and RB1. Impressively, 85% (560/659) of TP53 mutations occurred in the 21-gene signature-positive BC. Collectively, we provide the first evidence that CYB5D2 is a candidate tumor suppressor of BC.

ZFR promotes cell proliferation and tumor development in colorectal and liver cancers

Colorectal cancer (CRC) and liver cancer are the second and fourth leading causes of cancer-related deaths in the whole world, respectively, and each year over 1.6 million people die from these diseases. To identify driver genes in CRC and liver cancer, we have performed Sleeping Beauty transposon mutagenesis screens in mouse models. Zinc finger RNA binding protein, ZFR, was one of the novel candidate cancer genes identified in these forward genetic screens. Consistent with this discovery, a pan-cancer analysis of sequencing results of thousands of human cancer genomes demonstrated that ZFR is a potential potent oncogene. In this study, we aimed to investigate ZFR's roles in both types of cancer and found that overexpression of ZFR in CRC and liver cancer cells led to accelerated tumor development. Consistently, knockdown of ZFR resulted in significantly decelerated tumor development. ZFR overexpression also promoted tumor development of immortalized mouse liver cells. ZFR overexpression and shRNA knockdown led to accelerated and decelerated cell proliferation, respectively, indicating that ZFR promotes tumor development mainly by regulating cell proliferation. To identify ZFR's targets in transcription, we performed whole transcriptome sequencing using ZFR small interfering RNAs in a primary human colon cell line. All potential target genes were validated by real time PCR. FAM49B was a tumor suppressor candidate for ZFR targets. When we knocked down the expression of FAM49B in CRC and liver cancer cells, we observed significantly accelerated cell proliferation, consistent with the results with ZFR overexpression. The results presented here demonstrate the oncogenic role of ZFR in both CRC and liver cancer, providing a potential drug target for both cancers' treatment. We also identified ZFR's potential transcriptional targets, and further investigations on those targets, especially FAM49B, will help us understand more about the important role of ZFR in digestive system cancers.

PTPRK suppresses progression and chemo-resistance of colon cancer cells via direct inhibition of pro-oncogenic CD133.

Receptor‐type protein tyrosine phosphatase κ (PTPRK) is considered to be a candidate tumor suppressor. PTPRK dephosphorylates CD133, which is a stem cell marker; phosphorylated CD133 accelerates xenograft tumor growth of colon cancer cells through the activation of AKT, but the functional significance of this has remained elusive. In this study, we have demonstrated that knockdown of PTPRK potentiates the pro‐oncogenic CD133–AKT pathway in colon cancer cells. Intriguingly, depletion of PTPRK significantly reduced sensitivity to the anti‐cancer drug oxaliplatin and was accompanied by up‐regulation of phosphorylation of Bad, a downstream target of AKT. Together, our present observations strongly suggest that the CD133–PTPRK axis plays a pivotal role in the regulation of colon cancer progression as well as drug resistance.

Overexpression of lncRNA TUSC7 reduces cell migration and invasion in colorectal cancer.

Colorectal cancer (CRC) is a highly heterogeneous disease worldwide. Long non‑coding RNA (lncRNA) tumor suppressor candidate 7 (TUSC7) plays a crucial role in the development of several cancers. However, the role of TUSC7 in the tumorigenesis of CRC has not been explored. The TUSC7‑overexpressing CRC cell lines SW480 and CaCo‑2 were generated to investigate the effects of TUSC7 on the growth, migration, invasion and epithelial‑mesenchymal transition (EMT) of CRC cells. CCK‑8, wound‑healing and Transwell assays were used to evaluate CRC cell proliferation, migration and invasion. The mRNA and protein expression of TUSC7 were detected by quantitative real‑time PCR and immunoblotting, respectively. In the present study, we observed that the expression of TUSC7 was decreased in CRC cells compared to the expression in the normal colon epithelial cell line NCM460. Moreover, overexpression of TUSC7 inhibited CRC cell proliferation, metastasis, invasion and EMT. These findings indicated that TUSC7 is involved in CRC development.

CIAPIN1 Targeted NHE1 and ERK1/2 to Suppress NSCLC Cells' Metastasis and Predicted Good Prognosis in NSCLC Patients Receiving Pulmonectomy.

Objective Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) acts as a downstream effector of the receptor tyrosine kinase-Ras signaling pathway and has been reported as a candidate tumor suppressor gene in various cancers. Our current study was aimed at investigating the prognostic impact of CIAPIN1 on Non-Small-Cell Lung Carcinoma (NSCLC) patients and the effect of CIAPIN1 on NSCLC A549 cells' metastasis. Methods Western blot analysis was applied to detect CIAPIN1 expression; Kaplan-Meier survival analysis was used to evaluate the effect of CIAPIN1 on NSCLC patients' prognosis. Wound healing assay, Transwell chamber invasion analysis, and tumorigenicity assay in BALB/c nude mice were used to measure the metastasis potential of A549 cells. Results We found that CIAPIN1 overexpression indicated good survival duration during the follow-up period. CIAPIN1 overexpression inhibited the migration, invasion, MMPs, and EMT-associated markers in A549 cells. Further, NHE1 (Na+/H+ exchanger 1) expression and ERK1/2 phosphorylation decreased along with CIAPIN1 upregulation. Importantly, treating A549 cells with CIAPIN1 overexpression with the NHE1-specific inhibitor, Cariporide, further inhibited the metastatic capacity, MMP expression, EMT-associated markers, and phosphorylated ERK1/2. Treatment with the MEK1-specific inhibitor, PD98059, induced nearly the same suppression of CIAPIN1 overexpression-dependent metastatic capacity, MMP expression, and EMT-associated markers as was observed with Cariporide. Further, Cariporide and PD98059 exert synergistical suppression of A549 cells' metastatic capacity. Conclusion Thus, the current results implied a potential management by which CIAPIN1 upregulation may have a crucial effect on the suppression of NSCLC, indicating that overexpression of CIAPIN1 might serve as a combination with chemotherapeutical agents in NSCLC therapy.

MicroRNA-663 facilitates the growth, migration and invasion of ovarian cancer cell by inhibiting TUSC2

BackgroundMicroRNAs (miRNAs) have emerged as the critical modulators of the tumorigenesis and tumor progression.MethodsThe levels of miR-663 in ovarian cancer cell lines and clinical tissues were detected using qRT-PCR assays. The Transwell invasion and wound healing assay were conducted to assess the roles of miR-663 in the migration and invasion of ovarian cancer cell in vitro. Rescue assays were carried out to confirm the contribution of tumor suppressor candidate 2 (TUSC2) in the aggressiveness of cancer cell which was regulated by miR-663.ResultsThe levels of miR-663 were up-regulated in ovarian cancer tissues in comparison with the corresponding normal tissues. Up-regulation of miR-663 increased the proliferation, colony formation, migration and invasion of ovarian cancer SKOV3 cell. Additional, over-expression of miR-663 increased the tumor growth of SKOV3 in xenograft model. Bioinformatics analysis and luciferase reporter assay identified that miR-663 decreased the level of TUSC2 via binding to the 3′-UTR of TUSC2 gene. Finally, the expression of TUSC2 was inversely associated with the level of miR-663 in ovarian carcinoma tissue and over-expression of TUSC2 inhibited the migration and invasion abilities of SKOV3 that was promoted by miR-663.ConclusionAltogether, these results indicate that miR-663 acts as a potential tumor-promoting miRNA through targeting TUSC2 in ovarian cancer.

Promoter hypermethylation-mediated downregulation of tumor suppressor gene SEMA3B and lncRNA SEMA3B-AS1 correlates with progression and prognosis of esophageal squamous cell carcinoma.

Frequent deletions of tumor-suppressor genes at chromosome 3p21.3 have been detected in esophageal squamous cell carcinoma (ESCC). As a candidate tumor suppressor gene, semaphorin 3B (SEMA3B) is located at 3p21.3 and is frequently inactivated in several tumors. However, the role and inactivation mechanisms of SEMA3B and its antisense long non-coding RNA (lncRNA) SEMA3B-AS1 in the carcinogenesis of ESCC have not been fully elucidated. The present study was conducted to investigate the role, epigenetic inactivation mechanisms, and prognostic value of SEMA3B and SEMA3B-AS1 in ESCC tumorigenesis and prognosis. Frequent downregulation of SEMA3B and SEMA3B-AS1 was detected in esophageal cancer cells and ESCC tissues, and the expression level of SEMA3B and SEMA3B-AS1 in ESCC tissues was correlated with TNM stage and lymph node metastasis. SEMA3B and SEMA3B-AS1 shared the same CpG island in the promoter region and the expression of both genes might be regulated by the promoter methylation status. Furthermore, transcription factor Sp1 activated SEMA3B or SEMA3B-AS1 transcription and the promoter hypermethylation of SEMA3B and SEMA3B-AS1 influenced Sp1 binding ability. Moreover, over-expression of SEMA3B and SEMA3B-AS1 suppressed the viability and invasion of esophageal cancer cells in vitro. SEMA3B-AS1 influenced the protein expression of SEMA3B. SEMA3B or SEMA3B-AS1 expression and promoter methylation status were correlated with ESCC patients' survival. Thus, these findings suggest that SEMA3B and SEMA3B-AS1 may act as tumor suppressors and may serve as potential targets for antitumor therapy.

TUSC3 as a potential biomarker for prognosis in clear cell renal cell carcinoma.

The aim of the present study was to explore the expression levels of tumor suppressor candidate 3 (TUSC3) in human clear cell renal cell carcinoma (ccRCC) and its clinical value. Immunohistochemical staining, western blotting and reverse transcription-quantitative polymerase chain reaction were used to detect TUSC3 expression in paracancerous normal tissues and ccRCC tissues. The tissues were derived from the pathological specimens of 54 patients with ccRCC. Additionally, associations among TUSC3 expression and histological grade and clinicopathological staging of ccRCC were investigated. The results of these comparisons revealed that TUSC3 expression in ccRCC tissues was significantly lower than that in paracancerous tissues (P<0.05). TUSC3 expression in the high differentiation group was higher than that in the median and low differentiation groups (P<0.05). Expression levels of TUSC3 in stage I and II tissues were higher than those in stage III and IV tissues (P<0.05). The expression levels of TUSC3 in the lymph node metastasis group were lower than those in the non-lymph node metastasis group (P<0.05). In conclusion, the expression levels of TUSC3 in human ccRCC tissues were downregulated compared with those found in normal human renal tissue, and TUSC3 may inhibit the progression of ccRCC. Furthermore, the TUSC3 gene may be used as a promising tumor marker for the early diagnosis and prognosis of ccRCC.

LPLUNC1 stabilises PHB1 by counteracting TRIM21-mediated ubiquitination to inhibit NF-\u03baB activity in nasopharyngeal carcinoma

Long-palate, lung and nasal epithelium clone 1 (LPLUNC1) is a tumour suppressor gene in nasopharyngeal carcinoma (NPC), and low expression of LPLUNC1 is associated with poor prognosis. Our previous study showed that LPLUNC1 upregulates Prohibitin 1 (PHB1), a pleiotropic protein that functions as a tumour suppressor gene in various cancers. Low expression of PHB1 was also found to be associated with the poor prognosis of NPC patients. However, the mechanisms by which LPLUNC1 upregulates PHB1 and the potential role of PHB1 in NPC are unclear. Here, we found that LPLUNC1 stabilised PHB1 by inhibiting PHB1 ubiquitination, which is mediated by E3 ligase TRIM21. LPLUNC1 competitively impaired the binding of PHB1 to TRIM21 due to its stronger binding affinity to PHB1, suppressing the ubiquitination of PHB1. Therefore, our study indicates that PHB1 acted as a tumour suppressor gene by inhibiting NF-κB activity. Depletion of PHB1 significantly attenuated the anti-tumour effects of LPLUNC1 in NPC cells, and the inhibitory effect of LPLUNC1 on NF-κB activity was thus reversed. Together, our findings revealed a novel mechanism underlying the anticancer effect of LPLUNC1 and clarified that PHB1 may represent a novel, promising candidate tumour suppressor gene in NPC, with potential therapeutic target value.

MicroRNA‑663b downregulation inhibits proliferation and induces apoptosis in bladder cancer cells by targeting TUSC2.

The present study aimed to explore the role and underlying molecular mechanism of microRNA‑663b (miR‑663b) in the tumorigenesis of bladder cancer. The miR‑663b expression in human bladder cancer tissues and cell lines was measured determined reverse transcription‑quantitative polymerase chain reaction. TargetScan was used to predict the potential targets of miR‑663b, and a dual‑luciferase reporter assay was performed to validate tumor suppressor candidate 2 (TUSC2) as a target of miR‑663b. Cell Counting Kit‑8 was used for cell viability analysis, and cell apoptosis was evaluated by flow cytometry. In addition, western blot analysis was performed to detect protein expression in current study. The findings suggested that miR‑663b was upregulated in bladder cancer tissues and cell lines compared with normal tissue and cells. TUSC2 was validated as a direct target of miR‑663b and was negatively regulated by miR‑663b. miR‑663b inhibition significantly reduced the viability of T24 cells, and T24 cell apoptosis was markedly induced. In addition, miR‑663b inhibition enhanced the expression levels of p53 and p21 in T24 cells. Furthermore, the changes caused by miR‑663b inhibitor in T24 cells were eliminated by TUSC2 gene silencing. In conclusion, inhibition of miR‑663b reduced viability and induced apoptosis in bladder cancer cells by targeting TUSC2. These findings provide a promising novel therapeutic target for bladder cancer treatment.

Integrated Analysis of Germline and Tumor DNA Identifies New Candidate Genes Involved in Familial Colorectal Cancer.

Colorectal cancer (CRC) shows aggregation in some families but no alterations in the known hereditary CRC genes. We aimed to identify new candidate genes which are potentially involved in germline predisposition to familial CRC. An integrated analysis of germline and tumor whole-exome sequencing data was performed in 18 unrelated CRC families. Deleterious single nucleotide variants (SNV), short insertions and deletions (indels), copy number variants (CNVs) and loss of heterozygosity (LOH) were assessed as candidates for first germline or second somatic hits. Candidate tumor suppressor genes were selected when alterations were detected in both germline and somatic DNA, fulfilling Knudson’s two-hit hypothesis. Somatic mutational profiling and signature analysis were also performed. A series of germline-somatic variant pairs were detected. In all cases, the first hit was presented as a rare SNV/indel, whereas the second hit was either a different SNV (3 genes) or LOH affecting the same gene (141 genes). BRCA2, BLM, ERCC2, RECQL, REV3L and RIF1 were among the most promising candidate genes for germline CRC predisposition. The identification of new candidate genes involved in familial CRC could be achieved by our integrated analysis. Further functional studies and replication in additional cohorts are required to confirm the selected candidates.

Combined analysis and validation for DNA methylation and gene expression profiles associated with prostate cancer

BackgroundProstate cancer (PCa) is a malignancy cause of cancer deaths and frequently diagnosed in male. This study aimed to identify tumor suppressor genes, hub genes and their pathways by combined bioinformatics analysis.MethodsA combined analysis method was used for two types of microarray datasets (DNA methylation and gene expression profiles) from the Gene Expression Omnibus (GEO). Differentially methylated genes (DMGs) were identified by the R package minfi and differentially expressed genes (DEGs) were screened out via the R package limma. A total of 4451 DMGs and 1509 DEGs, identified with nine overlaps between DMGs, DEGs and tumor suppressor genes, were screened for candidate tumor suppressor genes. All these nine candidate tumor suppressor genes were validated by TCGA (The Cancer Genome Atlas) database and Oncomine database. And then, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed by DAVID (Database for Annotation, Visualization and Integrated Discovery) database. Protein–protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. At last, Kaplan–Meier analysis was performed to validate these genes.ResultsThe candidate tumor suppressor genes were IKZF1, PPM1A, FBP1, SMCHD1, ALPL, CASP5, PYHIN1, DAPK1 and CASP8. By validation in TCGA database, PPM1A, DAPK1, FBP1, PYHIN1, ALPL and SMCHD1 were significant. The hub genes were FGFR1, FGF13 and CCND1. These hub genes were identified from the PPI network, and sub-networks revealed by these genes were involved in significant pathways.ConclusionIn summary, the study indicated that the combined analysis for identifying target genes with PCa by bioinformatics tools promote our understanding of the molecular mechanisms and underlying the development of PCa. And the hub genes might serve as molecular targets and diagnostic biomarkers for precise diagnosis and treatment of PCa.

ING5 inhibits lung cancer invasion and epithelial-mesenchymal transition by inhibiting the WNT/β-catenin pathway.

BackgroundING5 is the last member of the Inhibitor of Growth (ING) candidate tumor suppressor family that has been implicated in multiple cellular functions, including cell cycle regulation, apoptosis, and chromatin remodeling. Our previous study showed that ING5 overexpression inhibits lung cancer aggressiveness and epithelial–mesenchymal transition (EMT), with unknown mechanisms.MethodsWestern blotting was used to detect total and phosphorylated levels of β‐catenin and EMT‐related proteins. Immunofluorescent staining was used to observe E‐cadherin expression. Proliferation and colony formation, wound healing, and Transwell migration and invasion assays were performed to study the proliferative and invasive abilities of cancer cells.ResultsING5 overexpression promotes phosphorylation of β‐catenin at Ser33/37, leading to a decreased β‐catenin protein level. Small hairpin RNA‐mediated ING5 knockdown significantly increased the β‐catenin level and inhibited phosphorylation of β‐catenin S33/37. Treatment with the WNT/β‐catenin inhibitor XAV939 inhibited ING5‐knockdown promoted proliferation, colony formation, migration, and invasion of lung cancer A549 cells, with increased phosphorylation of β‐catenin S33/37 and a decreased β‐catenin level. XAV939 also impaired ING5‐knockdown‐induced EMT, as indicated by upregulated expression of the EMT marker E‐cadherin, an epithelial marker; and decreased expression of N‐cadherin, a mesenchymal marker, and EMT‐related transcription factors, including Snail, Slug, Twist, and Smad3. Furthermore, XAV939 could inhibit the activation of both IL‐6/STAT3 and PI3K/Akt signaling pathways.ConclusionING5 inhibits lung cancer invasion and EMT by inhibiting the WNT/β‐catenin pathway.

ING3 is required for ATM signaling and DNA repair in response to DNA double strand breaks.

Inhibitor of Growth 3 (ING3) is a candidate tumor suppressor gene whose expression is lost in tumors such as hepatocellular carcinoma, head and neck squamous cell carcinoma and melanoma. In the present study, we show that ING3-depleted human cells and yeast cells deleted for its ortholog YNG2 are sensitive to DNA damage suggesting a conserved role in response to such stress. In human cells, ING3 is recruited to DNA double strand breaks and is required for ATM activation. Remarkably, in response to doxorubicin, ATM activation is dependent on ING3 but not on TIP60, whose recruitment to DNA breaks also depends on ING3. These events lead to ATM-mediated phosphorylation of NBS1 and the subsequent recruitment of RNF8, RNF168, 53BP1, and BRCA1, which are major mediators of the DNA damage response. Accordingly, upon genotoxic stress, DNA repair by non-homologous end joining (NHEJ) or homologous recombination (HR) were impaired in absence of ING3. Finally, immunoglobulin class switch recombination (CSR), a physiological mechanism requiring NHEJ repair, was impaired in the absence of ING3. Since deregulation of DNA double strand break repair is associated with genomic instability, we propose a novel function of ING3 as a caretaker tumor suppressor involved in the DNA damage signaling and repair.