The nuclear to cytoplasmic shift of ING5 protein during colorectal carcinogenesis with their distinct links to pathologic behaviors of carcinomas☆

Tctp, a unique Ing5-binding partner, inhibits the chromatin binding of Enok in Drosophila

The MOZ/MORF histone acetyltransferase complex is highly conserved in eukaryotes and controls transcription, development, and tumorigenesis. However, little is known about how its chromatin localization is regulated. Inhibitor of growth 5 (ING5) tumor suppressor is a subunit of the MOZ/MORF complex. Nevertheless, the in vivo function of ING5 remains unclear. Here, we report an antagonistic interaction between Drosophila Translationally controlled tumor protein (TCTP) (Tctp) and ING5 (Ing5) required for chromatin localization of the MOZ/MORF (Enok) complex and H3K23 acetylation. Yeast two-hybrid screening using Tctp identified Ing5 as a unique binding partner. In vivo, Ing5 controlled differentiation and down-regulated epidermal growth factor receptor signaling, whereas it is required in the Yorkie (Yki) pathway to determine organ size. Ing5 and Enok mutants promoted tumor-like tissue overgrowth when combined with uncontrolled Yki activity. Tctp depletion rescued the abnormal phenotypes of the Ing5 mutation and increased the nuclear translocation of Ing5 and chromatin binding of Enok. Nonfunctional Enok promoted the nuclear translocation of Ing5 by reducing Tctp, indicating a feedback mechanism between Tctp, Ing5, and Enok to regulate histone acetylation. Therefore, Tctp is essential for H3K23 acetylation by controlling the nuclear translocation of Ing5 and chromatin localization of Enok, providing insights into the roles of human TCTP and ING5-MOZ/MORF in tumorigenesis.

In silico analysis prediction of HepTH1-5 as a potential therapeutic agent by targeting tumour suppressor protein networks

Many studies reported that the activation of tumour suppressor protein, p53 induced the human hepcidin expression. However, its expression decreased when p53 was silenced in human hepatoma cells. Contrary to Tilapia hepcidin TH1-5, HepTH1-5 was previously reported to trigger the p53 activation through the molecular docking approach. The INhibitor of Growth (ING) family members are also shown to directly interact with p53 and promote cell cycle arrest, senescence, apoptosis and participate in DNA replication and DNA damage responses to suppress the tumour initiation and progression. However, the interrelation between INGs and HepTH1-5 remains unknown. Therefore, this study aims to identify the mechanism and their protein interactions using in silico approaches. The finding revealed that HepTH1-5 and its ligands had interacted mostly on hotspot residues of ING proteins which involved in histone modifications via acetylation, phosphorylation, and methylation. This proves that HepTH1-5 might implicate in an apoptosis signalling pathway and preserve the protein structure and function of INGs by reducing the perturbation of histone binding upon oxidative stress response. This study would provide theoretical guidance for the design and experimental studies to decipher the role of HepTH1-5 as a potential therapeutic agent for cancer therapy. Communicated by Ramaswamy H. Sarma.

The roles of ING5 in cancer: A tumor suppressor

As a Class II tumor suppressor, ING5 contains nuclear localization signal, plant homeodomain, novel conserved region, and leucine zipper-like domains. ING5 proteins form homodimer into a coil-coil structure, and heterodimers with ING4, histone H3K4me3, histone acetyltransferase (HAT) complex, Tip60, Cyclin A1/CDK2, INCA1 and EBNA3C for the transcription of target genes. The acetylated proteins up-regulated by ING5 are preferentially located in nucleus and act as transcription cofactors, chromatin and DNA binding functions, while those down-regulated by ING5 mostly in cytoplasm and contribute to metabolism. ING5 promotes the autoacetylation of HAT p300, p53, histone H3 and H4 for the transcription of downstream genes (Bax, GADD45, p21, p27 and so forth). Transcriptionally, YY1 and SRF up-regulate ING5 mRNA expression by the interaction of YY1-SRF-p53-ING5 complex with ING5 promoter. Translationally, ING5 is targeted by miR-196, miR-196a, miR-196b-5p, miR-193a-3p, miR-27-3p, miR-200b/200a/429, miR-1307, miR-193, miR-222, miR-331-3p, miR-181b, miR-543 and miR-196-b. ING5 suppresses proliferation, migration, invasion and tumor growth of various cancer cells via the suppression of EGFR/PI3K/Akt, IL-6/STAT3, Akt/NF-κB/NF-κB/MMP-9 or IL-6/CXCL12 pathway. ING5-mediated chemoresistance is closely linked to anti-apoptosis, overexpression of chemoresistant genes, the activation of PI3K/Akt/NF-κB and Wnt/β-catenin signal pathways. Histologically, ING5 abrogation in gastric stem-like and pdx1-positive cells causes gastric dysplasia and cancer, and conditional ING5 knockout in pdx1-positive and gastric chief cells increases MNU-induced gastric carcinogenesis. Intestinal ING5 deletion increases AOM/DSS- induced colorectal carcinogenesis and decreases high-fat-diet weight. The overexpression and nucleocytoplasmic translocation of ING5 are seen during carcinogenesis, and ING5 expression was inversely associated with aggressive behaviors and poor prognosis in a variety of cancers. These findings indicated that ING5 might be used for a molecular marker for carcinogenesis and following progression, and as a target for gene therapy if its chemoresistant function might be ameliorated.

BRPF1-KAT6A/KAT6B Complex: Molecular Structure, Biological Function and Human Disease

The bromodomain and PHD finger-containing protein1 (BRPF1) is a member of family IV of the bromodomain-containing proteins that participate in the post-translational modification of histones. It functions in the form of a tetrameric complex with a monocytic leukemia zinc finger protein (MOZ or KAT6A), MOZ-related factor (MORF or KAT6B) or HAT bound to ORC1 (HBO1 or KAT7) and two small non-catalytic proteins, the inhibitor of growth 5 (ING5) or the paralog ING4 and MYST/Esa1-associated factor 6 (MEAF6). Mounting studies have demonstrated that all the four core subunits play crucial roles in different biological processes across diverse species, such as embryonic development, forebrain development, skeletal patterning and hematopoiesis. BRPF1, KAT6A and KAT6B mutations were identified as the cause of neurodevelopmental disorders, leukemia, medulloblastoma and other types of cancer, with germline mutations associated with neurodevelopmental disorders displaying intellectual disability, and somatic variants associated with leukemia, medulloblastoma and other cancers. In this paper, we depict the molecular structures and biological functions of the BRPF1-KAT6A/KAT6B complex, summarize the variants of the complex related to neurodevelopmental disorders and cancers and discuss future research directions and therapeutic potentials.

Transcriptional Regulation of ING5 and its Suppressive Effects on Gastric Cancer

ING5 targets histone acetyltransferase or histone deacetylase complexes for local chromatin remodeling. Its transcriptional regulation and suppressive effects on gastric cancer remain elusive. Luciferase assay, EMSA, and ChIP were used to identify the cis-acting elements and trans-acting factors of the ING5 gene. We analyzed the effects of SAHA on the aggressive phenotypes of ING5 transfectants, and the effects of different ING5 mutants on aggressive phenotypes in SGC-7901 cells. Finally, we observed the effects of ING5 abrogation on gastric carcinogenesis. EMSA and ChIP showed that both SRF (−717 to −678 bp) and YY1 (−48 to 25bp) interacted with the promoter of ING5 and up-regulated ING5 expression in gastric cancer via SRF-YY1-ING5-p53 complex formation. ING5, SRF, and YY1 were overexpressed in gastric cancer, (P<0.05), and associated with worse prognosis of gastric cancer patients (P<0.05). ING5 had positive relationships with SRF and YY1 expression in gastric cancer (P<0.05). SAHA treatment caused early arrest at S phase in ING5 transfectants of SGC-7901 (P<0.05), and either 0.5 or 1.0 μM SAHA enhanced their migration and invasion (P<0.05). The wild-type and mutant ING5 transfectants showed lower viability and invasion than the control (P<0.05) with low CDC25, VEGF, and MMP-9 expression. Gastric spontaneous adenocarcinoma was observed in Atp4b-cre; ING5^f/f, Pdx1-cre; ING5^f/f, and K19-cre; ING5^f/f mice. ING5 deletion increased the sensitivity of MNU-induced gastric carcinogenesis. ING5 mRNA might be a good marker of gastric carcinogenesis, and poor prognosis. ING5 expression was positively regulated by the interaction of SRF-YY1-ING5-p53 complex within the ING5 promoter from −50 bp upstream to the transcription start site. ING5 deletion might contribute to the tumorigenesis and histogenesis of gastric cancer.

ING5 inhibits cancer aggressiveness by inhibiting Akt and activating p53 in prostate cancer

Prostate cancer (PCa) is one of the most common types of cancer in men. In several recent studies, chromosomal deletions in the q arm of chromosome 2, where ING5 resides within, have been identified in various cancer types including PCa. In this study, we investigate the role of ING5 as a tumor suppressor in PCa. We examined the expression level of ING5 in tissue samples and cell lines using quantitative real-time polymerase chain reaction and western blot analysis. We tested the in vitro tumor suppressor potential of ING5 in PC3 and LNCaP cells stably overexpressing it using cell viability, colony formation, migration, invasion, and apoptosis assays. We then investigated the effects of ING5 on the Akt and p53 signaling using western blot analysis. We show that ING5 is significantly downregulated in PCa tumor tissue samples and cell lines compared with the corresponding controls. In vitro assays demonstrate that ING5 effectively suppresses proliferative, clonogenic, migratory, and invasive potential and induce apoptosis in PCa cells. ING5 may potentially exert its anti-tumor potential by inhibiting AKT and inducing p53 signaling pathways. Our findings demonstrate that ING5 possesses tumor suppressor roles in vitro, pointing its importance during the prostatic carcinogenesis processes.

The Biological and Clinical Relevance of Inhibitor of Growth (ING) Genes in Non-Small Cell Lung Cancer

Carcinogenic mutations allow cells to escape governing mechanisms that commonly inhibit uncontrolled cell proliferation and maintain tightly regulated homeostasis between cell death and survival. Members of the inhibition of growth (ING) family act as tumor suppressors, governing cell cycle, apoptosis and cellular senescence. The molecular mechanism of action of ING genes, as well as their anchor points in pathways commonly linked to malignant transformation of cells, have been studied with respect to a variety of cancer specimens. This review of the current literature focuses specifically on the action mode of ING family members in lung cancer. We have summarized data from in vitro and in vivo studies, highlighting the effects of varying levels of ING expression in cancer cells. Based on the increasing insight into the function of these proteins, the use of ING family members as clinically useful biomarkers for lung cancer detection and prognosis will probably become routine in everyday clinical practice.

The Tumor Suppressor ING5 Is a Dimeric, Bivalent Recognition Molecule of the Histone H3K4me3 Mark

The INhibitor of Growth (ING) family of tumor suppressors regulates the transcriptional state of chromatin by recruiting remodeling complexes to sites with histone H3 trimethylated at lysine 4 (H3K4me3). This modification is recognized by the plant homeodomain (PHD) present at the C-terminus of the five ING proteins. ING5 facilitates histone H3 acetylation by the HBO1 complex, and also H4 acetylation by the MOZ/MORF complex. We show that ING5 forms homodimers through its N-terminal domain, which folds independently into an elongated coiled-coil structure. The central region of ING5, which contains the nuclear localization sequence, is flexible and disordered, but it binds dsDNA with micromolar affinity. NMR analysis of the full-length protein reveals that the two PHD fingers of the dimer are chemically equivalent and independent of the rest of the molecule, and they bind H3K4me3 in the same way as the isolated PHD. We have observed that ING5 can form heterodimers with the highly homologous ING4, and that two of three primary tumor-associated mutants in the N-terminal domain strongly destabilize the coiled-coil structure. They also affect cell proliferation and cell cycle phase distribution, suggesting a driver role in cancer progression.

ING5 is a Potential Target for Osteosarcoma Therapy

Osteosarcoma is one of the most common primary malignant bone tumors. The inhibitor of growth family of protein 5 has been identified as a tumor suppressor in many cancers. In this study, we confirmed the downregulation of the both inhibitor of growth family of protein 5 and messenger RNA levels in cancer tissues using Western blot and real-time polymerase chain reaction. In order to find the antitumor roles of inhibitor of growth family of protein 5, osteosarcoma cells, HOS, and MG63 were transfected with the plasmid pCDNA-3.1-inhibitor of growth family of protein 5. Overexpression of Inhibitor of growth family of protein 5 could induce apoptosis and inhibit cell proliferation in osteosarcoma cells. Furthermore, Western blot analysis showed that p-Smad2, p-Smad3, and Smad4 were increased in inhibitor of growth family of protein 5-expressing osteosarcoma cells. Our results indicated that overexpression of inhibitor of growth family of protein 5 in osteosarcoma cells induces apoptosis by activating the Smad pathway, thus proposing a promising role for inhibitor of growth family of protein 5 in treatment of patients with osteosarcoma.

Expression pattern and level of ING5 protein in normal and cancer tissues

Inhibitor of growth family 5 (ING5) functions as a type-II tumor suppressor gene and exerts an important role in DNA repair, apoptotic induction, proliferative inhibition, chromatin remodeling and the invasion process. In the present study, immunohistochemistry was performed to characterize the expression profile of ING5 protein on a tissue microarray containing mouse and human normal tissues, and human cancer tissues, including hepatocellular (n=62), renal clear cell (n=62), pancreatic (n=62), esophageal squamous cell (n=45), cervical squamous cell (n=31), breast (n=144), gastric (n=196), colorectal (n=96), endometrial (n=96) and lung carcinoma (n=192). In the mouse tissues, ING5 expression was detected in the cytoplasm of neurons, the nephric tubule and glomerulus, alveolar epithelium, gastrointestinal glands, squamous epithelium of the skin and skeletal muscles. By contrast, ING5 was localized to the cell nucleus in breast tissues. In human tissues, ING5 protein was primarily localized in the cytoplasm. However, ING5 was detected in the cytoplasm and nucleus in various types of normal tissues, including the tongue, stomach, intestine, lung and breast. In total, ING5 expression was detected in 400/986 cancer tissues (40.6%). In the majority of cases, ING5 expression was observed to be restricted to the cytoplasm. However, ING5 was also detected in the nucleus in a number of cancer tissues, including gastric, colorectal and lung carcinoma. Notably, ING5 was more frequently expressed in breast (79.9%), colorectal (56.3%) and endometrial carcinoma (50.0%). The incidence of ING5 expression in hepatocellular carcinoma (14.5%) and pancreatic carcinoma (22.6%) was low. These findings indicate that ING5 may be involved in cell regeneration and be associated with colorectal carcinogenesis.

ING5-mediated antineuroblastoma effects of suberoylanilide hydroxamic acid

Neuroblastoma is the most common extracranial solid neuroendocrine cancer and is one of the leading causes of death in children. To improve clinical outcomes and prognosis, discovering new promising drugs and targeted medicine is essential. We found that applying Suberoylanilide hydroxamic acid (SAHA; Vorinostat, a histone deacetylase inhibitor) and MG132 (a proteasome inhibitor) to SH-SY5Y cells synergistically suppressed proliferation, glucose metabolism, migration, and invasion and induced apoptosis and cell cycle arrest. These effects occurred both concentration and time dependently and were associated with the effects observed with inhibitor of growth 5 (ING5) overexpression. SAHA and MG132 treatment increased the expression levels of ING5, PTEN, p53, Caspase-3, Bax, p21, and p27 but decreased the expression levels of 14-3-3, MMP-2, MMP-9, ADFP, Nanog, c-myc, CyclinD1, CyclinB1, and Cdc25c concentration dependently, similar to ING5. SAHA may downregulate miR-543 and miR-196-b expression to enhance the translation of ING5 protein, which promotes acetylation of histones H3 and H4. All three proteins (ING5 and acetylated histones H3 and H4) were recruited to the promoters of c-myc, Nanog, CyclinD1, p21, and p27 for complex formation, thereby regulating the mRNA expression of downstream genes. ING5 overexpression and SAHA and/or MG132 administration inhibited tumor growth in SH-SY5Y cells by suppressing proliferation and inducing apoptosis. The expression of acetylated histones H3 and ING5 may be closely linked to the tumor size of neuroblastomas. In summary, SAHA and/or MG132 can synergistically suppress the malignant phenotypes of neuroblastoma cells through the miRNA-ING5-histone acetylation axis and via proteasomal degradation, respectively. Therefore, the two drugs may serve as potential treatments for neuroblastoma.

The down-regulated ING5 expression in lung cancer: a potential target of gene therapy

ING5 can interact with p53, thereby inhibiting cell growth and inducing apoptosis. We found that ING5 overexpression not only inhibited proliferation, migration, and invasion, but also induced G2 arrest, differentiation, autophagy, apoptosis, glycolysis and mitochondrial respiration in lung cancer cells. ING5 transfection up-regulated the expression of Cdc2, ATG13, ATG14, Beclin-1, LC-3B, AIF, cytochrome c, Akt1/2/3, ADFP, PFK-1 and PDPc, while down-regulated the expression of Bcl-2, XIAP, survivin,β-catenin and HXK1. ING5 transfection desensitized cells to the chemotherapy of MG132, paclitaxel, and SAHA, which paralleled with apoptotic alteration. ING5 overexpression suppressed the xenograft tumor growth by inhibiting proliferation and inducing apoptosis. ING5 expression level was significantly higher in normal tissue than that in lung cancer at both protein and mRNA levels. Nuclear ING5 expression was positively correlated with ki-67 expression and cytoplasmic ING5 expression. Cytoplasmic ING5 expression was positively associated with lymph node metastasis, and negatively with age, lymphatic invasion or CPP32 expression. ING5 expression was different in histological classification: squamous cell carcinoma > adenocarcinoma > large cell carcinoma > small cell carcinoma. Taken together, our data suggested that ING5 downregulation might involved in carcinogenesis, growth, and invasion of lung cancer and could be considered as a promising marker to gauge the aggressiveness of lung cancer. It might be employed as a potential target for gene therapy of lung cancer.

Overexpression of ING5 inhibits HGF-induced proliferation, invasion and EMT in thyroid cancer cells via regulation of the c-Met/PI3K/Akt signaling pathway

The inhibitor of growth 5 (ING5), a novel member of the ING family, is involved in diverse biological processes such as cell growth, apoptosis and DNA repair. Recently, ING5 has been reported to be associated with cancer development. However, its specific role in thyroid cancer has yet to be elucidated. In this study, we found that the expression of ING5 was significantly down-regulated in human thyroid cancer tissues and cell lines. In addition, overexpression of ING5 markedly inhibited hepatocyte growth factor (HGF)-induced proliferation, invasion and epithelial-mesenchymal transition (EMT) of thyroid cancer cells as well as suppressed the tumor growth and metastasis in vivo. Furthermore, our data showed that the c-Met/PI3K/Akt signaling pathway was responsible for the inhibitory effect of ING5 on the thyroid cancer. Taken together, these findings provided an essential basis for the tumor-suppression role of ING5 in thyroid cancer.

The roles of ING5 expression in ovarian carcinogenesis and subsequent progression: a target of gene therapy

Here, we found that ING5 overexpression suppressed cell viability, glucose metabolism, migration, invasion and epithelial-mesenchymal transition, and induced cell arrest, apoptosis, senescence, autophagy and fat accumulation in ovarian cancer cells. ING5-mediated chemoresistance was positively linked to apoptotic resistance and chemoresistance-related gene expression. ING5 overexpression suppressed tumor growth of ovarian cancer by decreasing proliferation, and inducing apoptosis and autophagy. ING5 mRNA level was lower in ovarian cancer than normal ovary, and borderline than benign tumors (p < 0.05), and negatively correlated with vascular invasion, lymphatic invasion and FIGO staging of ovarian cancer (p < 0.05). ING5 protein was less expressed in primary cancer than normal ovary (p < 0.05). There was a negative correlation between ING5 mRNA expression and the overall or progression-free survival time of the cancer patients with Grade 2, Grade 3, and stage I cancer (p < 0.05). Immunohistochemically, ING5 was less expressed in serous and mucinous adenocarcinoma than miscellaneous subtypes, and positively correlated with dedifferentiation and ki-67 expression of ovarian cancer (p < 0.05). These data suggested that down-regulated ING5 expression might be involved in ovarian carcinogenesis possibly by suppressing aggressive phenotypes, including proliferation, tumor growth, migration, invasion, and anti-apoptosis.

Epigenomics of Total Acute Sleep Deprivation in Relation to Genome-Wide DNA Methylation Profiles and RNA Expression

Despite an established link between sleep deprivation and epigenetic processes in humans, it remains unclear to what extent sleep deprivation modulates DNA methylation. We performed a within-subject randomized blinded study with 16 healthy subjects to examine the effect of one night of total sleep deprivation (TSD) on the genome-wide methylation profile in blood compared with that in normal sleep. Genome-wide differences in methylation between both conditions were assessed by applying a paired regression model that corrected for monocyte subpopulations. In addition, the correlations between the methylation of genes detected to be modulated by TSD and gene expression were examined in a separate, publicly available cohort of 10 healthy male donors (E-GEOD-49065). Sleep deprivation significantly affected the DNA methylation profile both independently and in dependency of shifts in monocyte composition. Our study detected differential methylation of 269 probes. Notably, one CpG site was located 69 bp upstream of ING5, which has been shown to be differentially expressed after sleep deprivation. Gene set enrichment analysis detected the Notch and Wnt signaling pathways to be enriched among the differentially methylated genes. These results provide evidence that total acute sleep deprivation alters the methylation profile in healthy human subjects. This is, to our knowledge, the first study that systematically investigated the impact of total acute sleep deprivation on genome-wide DNA methylation profiles in blood and related the epigenomic findings to the expression data.

The nucleocytoplasmic translocation and up-regulation of ING5 protein in breast cancer: a potential target for gene therapy

Here, we found that ING5 overexpression resulted in a lower proliferation, reduced glucose metabolism, S arrest, decreased migration and invasion, apoptotic induction, fat accumulation, autophagy, senescence and mesenchymal-epithelial–transition of breast cancer cells. It also suppressed the tumor growth of breast cancer cells by inhibiting proliferation, inducing apoptosis and autophagy. ING5-mediated chemoresistance was positively linked to Akt and NF-κB activation, MRP1 and GST-π overexpression, and FBXW7 hypoexpression. ING5 expression was higher in breast cancer than normal tissue at both mRNA and protein levels. ING5 mRNA expression was positively correlated with relapse- and distant metastasis-free survival rates. Nuclear ING5 expression showed gradual decrease from breast normal tissue, fibroadenoma, adenomatosis, primary to metastatic cancers, while versa for cytoplasmic ING5. Nuclear ING5 expression was negatively correlated with distant metastasis and p53 hypoexpression, while cytoplasmic ING5 expression was positively correlated with tumor size and ER expression. These data suggested that up-regulated expression and nucleocytoplasmic translocation of ING5 protein were observed in breast cancer. The higher expression of nuclear ING5 was inversely linked to worse clinicopathological behaviors of breast cancer by in vivo and vitro reversing aggressive phenotypes. Therefore, it should be employed as a biomarker to indicate the tumorigenesis and aggressiveness of breast cancer, and as a potential target for gene therapy.

The roles of ING5 in gliomas: a good marker for tumorigenesis and a potential target for gene therapy

To elucidate the anti-tumor effects and molecular mechanisms of ING5 on glioma cells, we overexpressed it in U87 cells, and examined the phenotypes and their relevant molecules. It was found that ING5 overexpression suppressed proliferation, energy metabolism, migration, invasion, and induced G₂/M arrest, apoptosis, dedifferentiation, senescence, mesenchymal- epithelial transition and chemoresistance to cisplatin, MG132, paclitaxel and SAHA in U87 cells. There appeared a lower expression of N-cadherin, Twist, Slug, Zeb1, Zeb2, Snail, Ac-H3, Ac-H4, Cdc2, Cdk4 and XIAP, but a higher expression of Claudin 1, Histones 3 and 4, p21, p53, Bax, β-catenin, PI₃K, Akt, and p-Akt in ING5 transfectants. ING5 overexpression suppressed tumor growth of U87 cells in nude mice by inhibiting proliferation and inducing apoptosis. Down-regulated ING5 expression was closely linked to the tumorigenesis and histogenesis of glioma. These data indicated that ING5 expression might be considered as a good marker for the tumorigenesis and histogenesis of gliomas. It might be employed as a potential target for gene therapy of glioma. PI₃K/Akt or β-catenin/TCF-4 activation might be positively linked to chemotherapeutic resistance, mediated by ING5.

ING5 suppresses breast cancer progression and is regulated by miR-24

BACKGROUND

The inhibitor of growth (ING) gene family of tumor suppressors is involved in multiple cellular functions such as cell cycle regulation, apoptosis, and chromatin remodeling. ING5 is a new member of the ING family whose function and regulation remain largely unknown.

METHODS

Quantitative real-time PCR and western blot were used to examine the expression levels of ING5 in breast cancer tissues. The miRNAs that potentially targeted ING5 were determined by bioinformatics analysis and luciferase reporter assay. Cell viability assay, transwell invasion and apoptosis assay were used to characterize the changes induced by overexpressing or knocking down miR-24 or ING5. Hematoxylin and eosin (H&E) staining and immunohistochemical staining for ING5 and Ki-67 were used for xenograft assays in BALB/c nude mice.

RESULTS

We showed that the ING5 protein rather than the mRNA, was significantly downregulated in breast cancer tissues. We also investigated the potential function of ING5 in breast tumorigenesis and found that ING5 suppressed the proliferation and invasion of breast cancer cells and promoted their apoptosis. Furthermore, we explored the molecular mechanisms accounting for the dysregulation of ING5 in breast cancer cells and identified an oncomiR, miR-24, as a direct upstream regulator of ING5. We revealed that miR-24 had the opposite effects to those of ING5 on breast cancer cells and could accelerate xenografted tumor growth in vivo.

CONCLUSION

Our findings uncover the tumor-suppressive role of ING5 and the regulatory pathway of ING5 in breast cancer and may provide insights into the molecular mechanisms of breast carcinogenesis.

INGs are potential drug targets for cancer

PURPOSE

The inhibitor of growth (ING) family consists of ING1, ING2, ING3, ING4 and ING5, which function as the type II tumor suppressors. INGs regulate cell proliferation, senescence, apoptosis, differentiation, angiogenesis, DNA repair, metastasis, and invasion by multiple pathways. In addition, INGs increase cancer cell sensitivity for chemotherapy and radiotherapy, while clinical observations show that INGs are frequently lost in some types of cancers. The aim of the study was to summarize the recent progress regarding INGs regulating tumor progression.

METHODS

The literatures of INGs regulating tumor progression were searched and assayed.

RESULTS

The regulating signaling pathways of ING1, ING2, ING3 or ING4 on tumor progression were shown. The mechanisms of INGs on tumor suppression were also assayed.

CONCLUSIONS

This review better summarized the signaling mechanism of INGs on tumor suppression, which provides a candidate therapy strategy for cancers.

MiR-1307 promotes ovarian cancer cell chemoresistance by targeting the ING5 expression

Background

We aimed to investigate the function of miR-1307 in chemoresistance and to explore its chemoresistance mechanism in ovarian cancer.

Methods

IC50 determination was used to test the chemoresistance profling in ovarian cancer cells. QRT-PCR or western blot was used to validate the expression level of miR-1307 and candidate gene or protein. Colony formation assay and FITC-labeled enhanced Annexin V immunofluorescence were used to compare cell proliferation and apoptosis ability, respectively. The potential target gene and its biological function of miRNA-1307 were also analyzed. Bioinformatics and Luciferase Reporter Gene Assay were conducted to validate the regulation of miRNA-1307 on the ING5 expression. Xenografts assay was used to demonstrate the inhibiting effect of miR-1307 ASO and Taxol therapy against ovarian cancer in vivo.

Results

MiR-1307 was over-expressed in chemoresistant ovarian cancer cell line A2780/Taxol, and over-expression or loss of miR-1307 promoted or inhabited chemoresistance. And we also found that the over-expression of miR-1307 promoted proliferation and inhibited apoptosis in ovarian cancer cells. Besides, we demonstrated that ING5 was a direct target of miR-1307 and miR-1307 down-regulated the ING5 expression in ovarian cancer cells. Additionally, we showed that ING5 inhibited cell proliferation, promoted cell apoptosis and inhabited chemoresistance reversely. Furthermore, the up-regulated ability of cell apoptosis and down-regulated ability of chemoresistance following the loss of miR-1307 was reversed by adding ING5 siRNA in vitro. Finally, we proved the inhibiting effect of miR-1307 ASO and Taxol therapy by increasing the ING5 expression against ovarian cancer through xenografts assay in vivo.

Conclusion

Our results suggested that miR-1307 could promote ovarian cancer chemoresistance by targeting the ING5 expression and miR-1307 might serve as a therapeutic target for ovarian cancer.

ING5 suppresses proliferation, apoptosis, migration and invasion, and induces autophagy and differentiation of gastric cancer cells: a good marker for carcinogenesis and subsequent progression

Here, we found that ING5 overexpression increased autophagy, differentiation, and decreased proliferation, apoptosis, migration, invasion and lamellipodia formation in gastric cancer cells, while ING5 knockdown had the opposite effects. In SGC-7901 transfectants, ING5 overexpression caused G₁ arrest, which was positively associated with 14-3-3 overexpression, Cdk4 and c-jun hypoexpression. The induction of Bax hypoexpression, Bcl-2, survivin, 14-3-3, PI3K, p-Akt and p70S6K overexpression by ING5 decreased apoptosis in SGC-7901 cells. The hypoexpression of MMP-9, MAP1B and flotillin 2 contributed to the inhibitory effects of ING5 on migration and invasion of SGC-7901 cells. ING5 overexpression might activate both β-catenin and NF-κB pathways in SGC-7901 cells, and promote the expression of down-stream genes (c-myc, VEGF, Cyclin D1, survivin, and interleukins). Compared with the control, ING5 transfectants displayed drug resistance to triciribine, paclitaxel, cisplatin, SAHA, MG132 and parthenolide, which was positively related to their apoptotic induction and the overexpression of chemoresistance-related genes (MDR1, GRP78, GRP94, IRE, CD147, FBXW7, TOP1, TOP2, MLH1, MRP1, BRCP1 and GST-π). ING5 expression was higher in gastric cancer than matched mucosa. It was inversely associated with tumor size, dedifferentiation, lymph node metastasis and clinicopathological staging of cancer. ING5 overexpression suppressed growth, blood supply and lung metastasis of SGC-7901 cells by inhibiting proliferation, enhancing autophagy and apoptosis in xenograft models. It was suggested that ING5 expression might be employed as a good marker for gastric carcinogenesis and subsequent progression by inhibiting proliferation, growth, migration, invasion and metastasis. ING5 might induce apoptotic and chemotherapeutic resistances of gastric cancer cells by activating β-catenin, NF-κB and Akt pathways.

ING5 inhibits cancer aggressiveness via preventing EMT and is a potential prognostic biomarker for lung cancer

The proteins of the Inhibitor of Growth (ING) candidate tumor suppressor family are involved in multiple cellular functions such as cell cycle regulation, apoptosis, and chromatin remodeling. ING5 is the new member of the family whose actual role in tumor suppression is not known. Here we show that ING5 overexpression in lung cancer A549 cells inhibited cell proliferation and invasiveness, while ING5 knockdown in lung cancer H1299 cells promoted cell aggressiveness. ING5 overexpression also abrogated tumor growth and invasive abilities of lung cancer cells in mouse xenograft models. Further study showed that ING5 overexpression inhibited EMT indicated by increase of E-cadherin and decrease of N-cadherin, Snail and slug at mRNA and protein levels, which was accompanied with morphological changes. cDNA microarray and subsequent qRT-PCR validation revealed that ING5 significantly downregulated expression of EMT (epithelial to mesenchymal transition)-inducing genes including CEACAM6, BMP2 and CDH11. Clinical study by tissue microarray showed that nuclear ING5 negatively correlated with clinical stages and lymph node metastasis of lung cancer. Furthermore, high level of nuclear ING5 was associated with a better prognosis. Taken together, these findings uncover an important role for ING5 as a potent tumor suppressor in lung cancer growth and metastasis.

ING5 is phosphorylated by CDK2 and controls cell proliferation independently of p53

Inhibitor of growth (ING) proteins have multiple functions in the control of cell proliferation, mainly by regulating processes associated with chromatin regulation and gene expression. ING5 has been described to regulate aspects of gene transcription and replication. Moreover deregulation of ING5 is observed in different tumors, potentially functioning as a tumor suppressor. Gene transcription in late G1 and in S phase and replication is regulated by cyclin-dependent kinase 2 (CDK2) in complex with cyclin E or cyclin A. CDK2 complexes phosphorylate and regulate several substrate proteins relevant for overcoming the restriction point and promoting S phase. We have identified ING5 as a novel CDK2 substrate. ING5 is phosphorylated at a single site, threonine 152, by cyclin E/CDK2 and cyclin A/CDK2 in vitro. This site is also phosphorylated in cells in a cell cycle dependent manner, consistent with it being a CDK2 substrate. Furthermore overexpression of cyclin E/CDK2 stimulates while the CDK2 inhibitor p27^KIP1 represses phosphorylation at threonine 152. This site is located in a bipartite nuclear localization sequence but its phosphorylation was not sufficient to deregulate the subcellular localization of ING5. Although ING5 interacts with the tumor suppressor p53, we could not establish p53-dependent regulation of cell proliferation by ING5 and by phospho-site mutants. Instead we observed that the knockdown of ING5 resulted in a strong reduction of proliferation in different tumor cell lines, irrespective of the p53 status. This inhibition of proliferation was at least in part due to the induction of apoptosis. In summary we identified a phosphorylation site at threonine 152 of ING5 that is cell cycle regulated and we observed that ING5 is necessary for tumor cell proliferation, without any apparent dependency on the tumor suppressor p53.

SIRT1 expression is associated with a poor prognosis, whereas DBC1 is associated with favorable outcomes in gastric cancer

Clinical trials of histone deacetylase (HDAC) inhibitors as antitumor therapy have been conducted for gastric cancer. Expression of SIRT1, a class III HDAC, is related to poor prognosis in some malignancies. We investigated the correlation between SIRT1 expression and progression and prognosis of gastric cancers comparing with molecules linked to SIRT1 in order to better predict the efficacy of HDAC inhibitors in treating this disease. We evaluated SIRT1 expression by western blot in 51 cases and SIRT1, DBC1, acetylated H4K16 (H4K16Ac), acetylated H3K9 (H3K9Ac), and p53 by immunohistochemistry (IHC) in 557 cases of gastric cancer. Western blotting showed that SIRT1 high expression related with statistics to advanced tumor progression, positive lymphatic invasion, positive venous invasion, and advanced stage but not to poor prognosis. IHC revealed that SIRT1 high expression correlated with worse clinico-pathological prognostic factors as same as in western blotting and related poor prognosis both by univariate and multivariate analyses. By the contrast, DBC1 and H4K16Ac were related to favorable prognostic factors and linked to favorable prognosis by univariate analysis but not by multivariate analysis. H3K16Ac correlated only favorable prognostic factors. Results of p53 were very similar to those of SIRT1. We found that SIRT1 high expression closely correlates with progression and prognosis in gastric cancer patients. And it was also indicated that SIRT1 acts as an oncogene by the results of DBC1, H4K16Ac, and H3K9Ac and might be a target molecule of HDAC inhibitor treatment for gastric cancer patients.

Keep-ING balance: tumor suppression by epigenetic regulation

Cancer cells accumulate genetic and epigenetic changes that alter gene expression to drive tumorigenesis. Epigenetic silencing of tumor suppressor, cell cycle, differentiation and DNA repair genes contributes to neoplastic transformation. The ING (inhibitor of growth) proteins (ING1-ING5) have emerged as a versatile family of growth regulators, phospholipid effectors, histone mark sensors and core components of HDAC1/2 - and several HAT chromatin-modifying complexes. This review will describe the characteristic pathways by which ING family proteins differentially affect the Hallmarks of Cancer and highlight the various epigenetic mechanisms by which they regulate gene expression. Finally, we will discuss their potentials as biomarkers and therapeutic targets in epigenetic treatment strategies.

Histone acetyltransferase Hbo1 destabilizes estrogen receptor α by ubiquitination and modulates proliferation of breast cancers

The estrogen receptor (ER) is a key molecule for growth of breast cancers. It has been a successful target for treatment of breast cancers. Elucidation of the ER expression mechanism is of importance for designing therapeutics for ER-positive breast cancers. However, the detailed mechanism of ER stability is still unclear. Here, we report that histone acetyltransferase Hbo1 promotes destabilization of estrogen receptor α (ERα) in breast cancers through lysine 48-linked ubiquitination. The acetyltransferase activity of Hbo1 is linked to its activity for ERα ubiquitination. Depletion of Hbo1 and anti-estrogen treatment displayed a potent growth suppression of breast cancer cell line. Hbo1 modulated transcription by ERα. Mutually exclusive expression of Hbo1 and ERα was observed in roughly half of the human breast tumors examined in the present study. Modulation of ER stability by Hbo1 in breast cancers may provide a novel therapeutic possibility.

Aberrant expression miR-196a is associated with abnormal apoptosis, invasion, and proliferation of pancreatic cancer cells

OBJECTIVES

MiR-196a levels inversely correlated with survival in pancreatic adenocarcinoma patients. However, the functional contributions of miR-196a to pancreatic cancer remain unclear.

METHODS

Three lentiviral vectors encoding microRNA miR-196a precursor, inhibitor, and scrambled microRNA oligomer were transfected into Panc-1 cells, respectively. Then we explored the regulation of inhibitor of growth 5 (ING5) expression by miR-196a and its impact on apoptosis, invasion, and growth of pancreatic cancer cells. The lentiviral transfected Panc-1 cells were surgically implanted into the pancreas of mice. In vivo tumor growth and ING5 expression were measured.

RESULTS

Down-regulation of ING5 expression was detected in cells transfected with miR-196a precursor (P < 0.01), accompanied by less apoptosis, increased invasion, and proliferation compared with control cells (P < 0.05). Cells transfected with miR-196a inhibitor revealed an opposite trend. Smaller detectable tumors were found in only 60% of mice after implantation of Lenti.miR-196a inhibitor-transfected Panc-1 cells compared with controls (360.7 ± 303.6 mm vs 511.58 ± 365.9 mm in controls; P < 0.01).

CONCLUSION

Our results provide experimental evidence to support aberrant expression of miR-196a is associated with abnormal apoptosis, invasion, and proliferation of pancreatic cancer cells.

Regulation of p53 by ING family members in suppression of tumor initiation and progression

The INhibitor of Growth (ING) family is an evolutionarily conserved set of proteins, implicated in suppression of initiation and progression of cancers in various tissues. They promote cell cycle arrest, cellular senescence and apoptosis, participate in stress responses, regulate DNA replication and DNA damage responses, and inhibit cancer cell migration, invasion, and angiogenesis of the tumors. At the molecular level, ING proteins are believed to participate in chromatin remodeling and transcriptional regulation of their target genes. However, the best known function of ING proteins is their cooperation with p53 tumor suppressor protein in tumor suppression. All major isoforms of ING family members can promote the transactivition of p53 and the majority of them are shown to directly interact with p53. In addition, ING proteins are thought to interact with and modulate the function of auxiliary members of p53 pathway, such as MDM2, ARF , p300, and p21, indicating their widespread involvement in the regulation and function of this prominent tumor suppressor pathway. It seems that p53 pathway is the main mechanism by which ING proteins exert their functions. Nevertheless, regulation of other pathways which are not relevant to p53, yet important for tumorigenesis such as TGF-β and NF-κB, by ING proteins is also observed. This review summarizes the current understanding of the mutual interactions and cooperation between different members of ING family with p53 pathway and implications of this cooperation in the suppression of cancer initiation and progression.

The pathobiological features of gastrointestinal cancers (Review)

Gastrointestinal adenocarcinoma (GIA) is a common malignant disease worldwide. Its tumorigenesis and progression is a multistage process with the involvement of a multifactorial etiology. Knowledge regarding altered expression of these genes during carcinogenesis may not only provide information about the molecular events during the initiation and progression of cancer, but may also result in the discovery of biological markers for the evaluation of cancer diagnosis and prognosis. In this review, we assessed molecular markers of pathogenesis, invasion, metastasis and prognosis, such as tumor suppressor and metastasis suppressor genes, and angiogenesis, cell adhesion, cell mobility, ER stress, mucin production, threonine protein kinase and REG family protein expression, by the establishment of tissue microarray (TMA) of GIA and immunohistochemistry (IHC) by intermittent microwave irradiation and in situ hybridization (ISH). Finally, we characterized the pathobiological features of Lauren's and WHO subtypes. It was found that the aberrant and cell-specific expression of these molecules is important in the malignant transformation of gastrointestinal epithelium and subsequent progression. These molecules also underlie the histogenic mechanisms of gastric carcinoma according to Lauren's and WHO classification. The combination of TMA, IHC and ISH may be widely applied to screen for molecular markers in GIA.

The inhibitor of growth protein 5 (ING5) depends on INCA1 as a co-factor for its antiproliferative effects

The proteins of the Inhibitor of Growth (ING) family are involved in multiple cellular functions such as cell cycle regulation, apoptosis, and chromatin remodeling. For ING5, its actual role in growth suppression and the necessary partners are not known. In a yeast-two-hybrid approach with human bone marrow derived cDNA, we identified ING5 as well as several other proteins as interaction partners of Inhibitor of cyclin A1 (INCA1) that we previously characterized as a novel interaction partner of cyclin A1/CDK2. ING5 expression in leukemic AML blasts was severely reduced compared to normal bone marrow. In line, ING5 inhibited bone marrow colony formation upon retroviral transduction. However, Inca1(-/-) bone marrow colony formation was not suppressed by ING5. In murine embryonic fibroblast (MEF) cells from Inca1(+/+) and Inca1(-/-) mice, overexpression of ING5 suppressed cell proliferation only in the presence of INCA1, while ING5 had no effect in Inca1(-/-) MEFs. ING5 overexpression induced a delay in S-phase progression, which required INCA1. Finally, ING5 overexpression enhanced Fas-induced apoptosis in Inca1(+/+) MEFs, while Inca1(-/-) MEFs were protected from Fas antibody-induced apoptosis. Taken together, these results indicate that ING5 is a growth suppressor with suppressed expression in AML whose functions depend on its interaction with INCA1.

Expression profile of the REG gene family in colorectal carcinoma

Regenerating (REG) gene family belongs to the calcium-dependent lectin gene superfamily and encodes small multifunctional secretory proteins, which might be involved in cell proliferation, differentiation, and carcinogenesis. To clarify REG expression profile in colorectal carcinoma (CRC), the authors examined the expression of REG Iα, Iβ, III, HIP/PAP, and REG IV by immunohistochemistry on tissue microarray. The expression of REG Iα, III, and HIP/PAP was more frequently observed in the CRCs than adjacent non-neoplastic mucosa (p < 0.001), whereas it was the converse for REG Iβ and IV (p < 0.001). The expression of REG Iα, Iβ, III, and HIP/PAP was negatively correlated with the depth of invasion of CRCs (p < 0.05). The REG Iβ and HIP/PAP were less expressed in CRCs with than without venous invasion (p < 0.05). The positive rates of REG Iα and HIP/PAP were significantly higher in CRCs without than with lymph node metastasis (p < 0.05). Mucinous carcinoma more frequently expressed REG IV protein than well- and moderately differentiated ones (p < 0.05). There was a positive relationship between REG Iα, Iβ, III, and HIP/PAP expression (p < 0.05). Survival analysis indicated the REG Iβ or HIP/PAP expression was positively linked to favorable prognosis of carcinoma patients (p < 0.05). This study indicated that aberrant REG expression might be closely linked to the pathogenesis, invasion, or lymph node metastasis of CRCs. REG Iβ and HIP/PAP could be considered reliable markers of favorable prognosis of CRC patients.