Overexpression of the myc target gene Mina53 in advanced renal cell carcinoma

Predicting role of Myc-induced nuclear antigen 53 in determining the development and severity of systemic lupus erythematosus

Introduction

Systemic lupus erythematosus (SLE) as an autoimmune disease can relate to an imbalance between regulatory T cells (Tregs) and Th17 cells. Previous reports have shown that Myc-induced nuclear antigen (Mina) 53 protein is involved in the developments of Tregs and Th17 cells. Therefore, the current study focused on determining whether Mina53 level is correlated to the severity of SLE.

Methods

The blood samples were collected from 60 patients with SLE (30 cases with mild SLE and 30 cases with severe SLE) and 30 healthy subjects. The serum concentration of Mina53 was measured using enzyme-linked immunosorbent assay (ELISA). The expression of Mina53 gene was assessed using real-time PCR method after extracting RNA from isolated peripheral blood mononuclear cells and synthesizing cDNA.

Results

Patients with SLE showed significant increases in the serum level and gene expression of Mina53 compared to healthy subjects (P<0.001). Furthermore, serum level and gene expression of Mina53 showed significant effects on SLE disease and its severity (P<0.01). There was the highest sensitivity and maximum specificity in the cut-off point of Mina53 serum level equal to 125.4 (area under the curve (AUC)=0.951) and Mina53 expression level equal to 8.5 (AUC=0.88) for SLE diagnosis. The cut-off point of Mina53 serum level equal to 139.5 (AUC=0.854) and the cut-off point of Mina53 expression level equal to 8.5 (AUC=0.788) had the highest sensitivity and maximum specificity determining severe forms of SLE.

Discussion

Our results showed that the changes in serum and expression levels of Mina53 have significant effects on SLE disease and its severity. These levels may be considered as diagnostic and predictive markers for SLE.

MYC-targeted genes predict distant recurrence in patients with ocular adnexal extranodal marginal zone lymphoma

Ocular adnexal extranodal marginal zone lymphoma (OA-EMZL) is the most frequent subtype of ocular adnexal lymphoma, with a high propensity for recurrence. Distant recurrence (DR) as an essential prognostic event has unique clinical risk factors, but whether distinct molecular features exist remains poorly understood. Here, we identified potential biomarkers using proteomic analysis of 27 OA-EMZL samples. The MYC-targeted genes PCNA, MCM6, and MCM4 were identified as candidates. MYC-targeted genes were further identified as the most significantly activated gene set in patients with DR. The candidate genes were verified in samples from 11 patients with DR and 33 matched controls using immunohistochemistry. The 3-year and 5-year AUC values of MCM6 (0.699 and 0.757) were higher than those of Ki-67 (0.532 and 0.592). High expressions of MCM6 and MCM4 were significantly associated with shorter distant recurrence-free survival (Log-rank p = 0.017, Log-rank p = 0.0053). Multivariate Cox regression identified MCM6 expression as an independent risk factor for DR (HR, 6.86; 95% CI, 1.32-35.79; P = 0.02). Knockdown of c-Myc in B cells resulted in decreased MCM6 and MCM4 expression and reduced proliferative capacity. Our results suggest that activation of the MYC-targeted gene is a distinct molecular feature of DR in OA-EMZL. MYC-targeted gene, MCM6, is a promising pathological biomarker for DR.

The JmjC-domain protein NO66/RIOX-1 affects the balance between proliferation and maturation in acute myeloid leukemia

As epigenetic regulators are frequently dysregulated in acute myeloid leukemia (AML) we determined expression levels of the JmjC-protein NO66 in AML cell lines and sub fractions of healthy human hematopoietic cells. NO66 is absent in the AML cell lines KG1/KG1a which consist of cells with the immature CD34⁺/CD38^- phenotype and is regarded as a "stem cell-like" model system. Similarly, NO66 is not detectable in CD34⁺/CD38^- cells purified from healthy donors but is clearly expressed in the more committed CD34⁺/CD38⁺ cell population. Loss of NO66 expression in KG1/KG1a cells is due to hyper-methylation of its promoter and is released by DNA-methyltransferase inhibitors. In KG1a cells stably expressing exogenous wild type (KG1a66wt) or enzymatically inactive mutant (KG1a66mut) NO66, respectively, the wild type protein inhibited proliferation and rDNA transcription. Gene expression profiling revealed that the expression of NO66 induces a transcriptional program enriched for genes with roles in proliferation and maturation (e.g.EPDR1, FCER1A, CD247, MYCN, SNORD13). Genes important for the maintenance of stem cell properties are downregulated (e.g. SIRPA, Lin28B, JAML). Our results indicate that NO66 induces lineage commitment towards myeloid progenitor cell fate and suggest that NO66 contributes to loss of stem cell properties.

Low expression of miR-let-7a promotes cell growth and invasion through the regulation of c-Myc in oral squamous cell carcinoma

In oral squamous cell carcinoma (OSCC), abnormal expression of microRNAs has been extensively reported. MiR-let-7a has been validated as a critical regulator of multiple cancers, but the biological process involved and its potential role in OSCC remain unknown.We first analyzed the differential expression of miR-let-7a in cancer tissues, adjacent noncancerous tissues and cell lines. The functional role of miR-let-7a in OSCC cell lines was evaluated by using colony formation assays, cell proliferation and transwell invasion assays in vitro. In addition, subcutaneous xenotransplantation of miR-let-7a transfected cells into nude mouse model was carried out to explore the potential function of miR-let-7a in vivo.miR-let-7a levels were found to be significantly downregulated in OSCC tissues compared with matched normal tissues (n = 60), and lower expression of miR-let-7a was related to poor prognosis in OSCC patients. Overexpression of MiR-let-7a induced a suppression in proliferation, invasion and migration and inhibited tumourigenesis in the nude mouse model. We also determined that c-Myc may serve as a direct target of miR-let-7a; furthermore, upregulated c-Myc expression could partially rescue the effects caused by miR-let-7a overexpression. miR-let-7a is low expression in OSCC, and promotes tumor development by directly targeting c-Myc. Our results may provide a potential therapeutic role for miR-let-7a in human OSCC.

MDIG promotes cisplatin resistance of lung adenocarcinoma by regulating ABC transporter expression via activation of the WNT/β-catenin signaling pathway

Mineral dust-induced gene (MDIG) is a proto- oncogene associated with lung cancer that serves a key role in the biological processes of tumorigenesis. The aim of the present study was to determine whether MDIG is involved in cisplatin (DDP) resistance in lung adenocarcinoma, and to investigate the associated molecular mechanism. In the present study, MDIG-knockdown and MDIG-overexpressing A549 cells and DDP-resistant A549/DDP cells were initially constructed, and then the mRNA and protein expression levels of MDIG and ATP-binding cassette (ABC) transporters (ABCB1, ABCC1, ABCG2), and the expression levels of the major associated proteins in the WNT/β-catenin pathway were determined by reverse transcription-quantitative PCR and Western blotting experiments. The results revealed that the mRNA and protein expression levels of MDIG in A549/DDP cells were significantly higher compared with those in A549 cells, and that the protein expression levels of MDIG increased in a dose-dependent manner with increasing DDP concentrations. Overexpression of MDIG in A549 and A549/DDP cells led to an increase in the IC₅₀ value, whereas silencing of MDIG led to a clear reduction in the IC₅₀ value. The overexpression of MDIG in the A549 and A549/DDP cells markedly upregulated the mRNA and protein expression levels of ABCB1, ABCC1, ABCG2, WNT family member 5A, WNT family member 3A and active β-catenin, and these were markedly decreased following MDIG silencing. Taken together, these results demonstrated that the DDP resistance of lung adenocarcinoma may be associated with an upregulation of MDIG expression, and that the expression levels of MDIG are positively associated with the degree of DDP resistance. Furthermore, MDIG promoted the expression of ABC transporters in tumor cells by activating the WNT/β-catenin signaling pathway, which may, in turn, lead to DDP resistance in lung adenocarcinoma.

New discoveries of mdig in the epigenetic regulation of cancers

Mineral dust-induced gene (mdig) encodes a member of the evolutionarily conserved JmjC family proteins that play fundamental roles in regulating chromatin-based processes as well as transcription of the genes in eukaryotic cells. This gene is also named as myc-induced nuclear antigen 53 (MINA), nucleolar protein 52 (NO52) and ribosomal oxygenase 2 (RIOX2). Increased expression of mdig had been noted in a number of human cancers, esp. lung cancer. Emerging evidence suggests that the oncogenic activity of mdig is most likely achieved through its regulation on the demethylation of histone proteins, despite it lacks the structural identities of the demethylases. Here, we discuss the latest discoveries on the characteristics of the mdig protein and its roles in a wide variety of normal and carcinogenic processes. We will also provide perspectives on how mdig is involved in the maintenance and differentiation of the embryonic stem cells, somatic stem cells and cancer stem cells.

The small members of the JMJD protein family: Enzymatic jewels or jinxes?

Jumonji C domain-containing (JMJD) proteins are mostly epigenetic regulators that demethylate histones. However, a hitherto neglected subfamily of JMJD proteins, evolutionarily distant and characterized by their relatively small molecular weight, exerts different functions by hydroxylating proteins and RNA. Recently, unsuspected proteolytic and tyrosine kinase activities were also ascribed to some of these small JMJD proteins, further increasing their enzymatic versatility. Here, we discuss the ten human small JMJD proteins (HIF1AN, HSPBAP1, JMJD4, JMJD5, JMJD6, JMJD7, JMJD8, RIOX1, RIOX2, TYW5) and their diverse physiological functions. In particular, we focus on the roles of these small JMJD proteins in cancer and other maladies and how they are modulated in diseased cells by an altered metabolic milieu, including hypoxia, reactive oxygen species and oncometabolites. Because small JMJD proteins are enzymes, they are amenable to inhibition by small molecules and may represent novel targets in the therapy of cancer and other diseases.

Hydroxylation of protein constituents of the human translation system: structural aspects and functional assignments

During the current decade, data on the post-translational hydroxylation of specific amino acid residues of some ribosomal proteins and translation factors in both eukaryotes and eubacteria have accumulated. The reaction is catalyzed by dedicated oxygenases (so-called ribosomal oxygenases), whose action is impaired under hypoxia conditions. The modification occurs at amino acid residues directly involved in the formation of the main functional sites of ribosomes and factors. This review summarizes currently available data on the specific hydroxylation of protein constituents of eukaryotic and eubacterial translation systems with a special emphasis on the human system, as well as on the links between hypoxia impacts on the operation of ribosomal oxygenases, the functioning of the translational apparatus and human health problems.

Effects of mdig on proliferation and apoptosis of lung cancer cells

Expression of mineral dust-induced gene (mdig) in lung cancer NCI-H1650 cells was detected to investigate the effects of mdig on proliferation and apoptosis of NCI-H1650 cells. NCI-H1650 lung cancer cells were cultured in vitro. The expression of mdig in NCI-H1650 cells was lowered using ribonucleic acid interference (RNAi) technique. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to detect the effects of mdig small interfering RNA (siRNA) on messenger RNA (mRNA) and the protein expression of mdig in lung cancer NCI-H1650 cells, respectively. The effect of mdig on the proliferation of NCI-H1650 cells was observed through 3-(4,5)-dimethylthiazol (-z-y1)-3,5-di-phenyl tetrazolium bromide (MTT) assay, and flow cytometry was used to detect the impact of mdig on cell cycle and apoptosis of NCI-H1650 cells. The influence of mdig on caspase-3 and poly (ADP-ribose) polymerase 1 (PARP1) proteins in NCI-H1650 cells were investigated via western blot analysis. The results of RT-qPCR and western blot analysis showed that mdig siRNA obviously inhibited the expression of mRNA and protein of mdig in NCI-H1650 cells. Results of the MTT assay showed mdig siRNA could significantly reduce the proliferation ability of NCI-H1650 cells. In addition cell cycle detection showed that mdig siRNA caused NCI-H1650 cell arrest at G1 phase. Apoptosis detection results indicated that mdig siRNA promoted apoptosis of NCI-H1650 cells. Western-blot analysis revealed that mdig siRNA upregulated the expression of cleaved caspase-3 and cleaved PARP1 proteins in NCI-H1650 cells. Mdig is highly expressed in lung cancer NCI-H1650 cells while mdig siRNA can inhibit proliferation of NCI-H1650 cells and accelerate apoptosis. The underlying mechanism may be related to inhibited cell cycle progression and upregulated expression of cleavage proteins (cleaved caspase-3 and cleaved PARP1).

The emerging roles of ribosomal histidyl hydroxylases in cell biology, physiology and disease

Hydroxylation is a novel protein modification catalyzed by a family of oxygenases that depend on fundamental nutrients and metabolites for activity. Protein hydroxylases have been implicated in a variety of key cellular processes that play important roles in both normal homeostasis and pathogenesis. Here, in this review, we summarize the current literature on a highly conserved sub-family of oxygenases that catalyze protein histidyl hydroxylation. We discuss the evidence supporting the biochemical assignment of these emerging enzymes as ribosomal protein hydroxylases, and provide an overview of their role in immunology, bone development, and cancer.

lncRNA involvement in hepatocellular carcinoma metastasis and prognosis

Eukaryotic lncRNAs are RNA molecules defined to be greater than 200 bp in length that are not translated to a protein and operate through several mechanisms, including participating in chromatin remodeling and methylation, influencing the integrity and stability of proteins and complexes, or acting as a sponge for miRNA inhibition. A number of recent studies have concentrated on the relationship between long non-coding RNAs (lncRNAs) and cancer. Hepatocellular carcinoma (HCC) is the most prevalent histological type of liver tumors, accounting for about 80 % of the cases worldwide. Lack of proper molecular markers for diagnosis of HCC and treatment evaluation is a significant problem. Dysregulated expression of HCC-related lncRNAs such as MEG-3, MALAT1, HULC, HOTAIR, and H19 have been identified and closely related with tumorigenesis, metastasis, prognosis and diagnosis. In this review, we summarized recent highlighted functions and molecular mechanisms of the most extensively studied lncRNAs in the pathophysiology of hepatocellular carcinoma and their potential for serving as probable therapeutic targets.

SETDB2 and RIOX2 are differentially expressed among renal cell tumor subtypes, associating with prognosis and metastization

Increasing detection of small renal masses by imaging techniques entails the need for accurate discrimination between benign and malignant renal cell tumors (RCTs) as well as among malignant RCTs, owing to differential risk of progression through metastization. Although histone methylation has been implicated in renal tumorigenesis, its potential as biomarker for renal cell carcinoma (RCC) progression remains largely unexplored. Thus, we aimed to characterize the differential expression of histone methyltransferases (HMTs) and histone demethylases (HDMs) in RCTs to assess their potential as metastasis biomarkers. We found that SETDB2 and RIOX2 (encoding for an HMT and an HDM, respectively) expression levels was significantly altered in RCTs; these genes were further selected for validation by quantitative RT-PCR in 160 RCTs. Moreover, SETDB2, RIOX2, and three genes encoding for enzymes involved in histone methylation (NO66, SETD3, and SMYD2), previously reported by our group, were quantified (RT-PCR) in an independent series of 62 clear cell renal cell carcinoma (ccRCC) to assess its potential role in ccRCC metastasis development. Additional validation was performed using TCGA dataset. SETDB2 and RIOX2 transcripts were overexpressed in RCTs compared to renal normal tissues (RNTs) and in oncocytomas vs. RCCs, with ccRCC and papillary renal cell carcinoma (pRCC) displaying the lowest levels. Low SETDB2 expression levels and higher stage independently predicted shorter disease-free survival. In our 62 ccRCC cohort, significantly higher RIOX2, but not SETDB2, expression levels were depicted in cases that developed metastasis during follow-up. These findings were not apparent in TCGA dataset. We concluded that SETDB2 and RIOX2 might be involved in renal tumorigenesis and RCC progression, especially in metastatic spread. Moreover, SETDB2 expression levels might independently discriminate among RCC subgroups with distinct outcome, whereas higher RIOX2 transcript levels might identify ccRCC cases with more propensity to endure metastatic dissemination.

Differential prognostic value of MYC immunohistochemistry in subtypes of papillary renal cell carcinoma

The histomorphological subtyping of papillary renal cell carcinomas (pRCCs) has improved the predictions of patients' long-term survival. Based on our previous results, we hypothesized that the MYC proto-oncogene would show differential expression in pRCC subtypes. Using a multi-institutional cohort of 204 pRCC patients we assessed the additional value of the immunohistochemical markers MYC, MINA53, and Ki67 in predicting patient's long-term survival. The clinical endpoints were overall survival (OS) and cancer-specific survival (CSS). Nomograms were constructed to predict each patient's risk of death (OS). The incorporation of the MYC staining patterns allowed the stratification of pRCC type 1 patients into better and worse prognostic groups. None of the patients with pRCC type 1 tumors and favorable MYC staining patterns died from tumor-related causes. This prognostic value was independent of the patient's age at surgery, the pathological tumor stage and presence of lymph node invasion. we could show that the immunohistochemical assessment of MYC and the histomorphological subtyping of pRCC stratifies pRCC type 1 tumors with regard to OS and CSS. The determination of the histomorphologic pRCC subtype in combination with the MYC immunohistochemical staining patterns allows a more accurate prediction of patients' individual risk of death.

Dysfunction of IKZF1/MYC/MDIG axis contributes to liver cancer progression through regulating H3K9me3/p21 activity

MDIG is known to be overexpressed in many types of human cancers and has demonstrated predictive power in the prognosis of cancer, although the functions and mechanisms of MDIG in liver cancer, especially in hepatocellular carcinoma (HCC), are still unknown. In this study, we report that MDIG and MYC were negatively regulated by IKZF1. MDIG overexpression substantially promoted HCC cell proliferation, cell migration and spreading, whereas knockdown of MDIG would reverse above-mentioned effect. MDIG effects on tumour cell growth were further demonstrated in a tumour xenograft model. Moreover, MDIG had effects on the level of p21(CIP1/WAF1) via H3K9me3 expression in HCC. MDIG was also found to be closely related to the sorafenib resistance of HCC cells in vitro. Clinically, we found that MDIG was frequently overexpressed in human HCCs (69.7% n=155) and was significantly associated with histological grade and hepatitis B virus infection. Our findings indicate that MDIG plays an important role in HCC progression via MDIG/H3K9me3/p21(CIP1/WAF1) signalling and serves as a potential therapeutic target.

Proteomic Characterization of the World Trade Center dust-activated mdig and c-myc signaling circuit linked to multiple myeloma

Several epidemiological studies suggested an increased incidence rate of multiple myeloma (MM) among first responders and other individuals who exposed to World Trade Center (WTC) dust. In this report, we provided evidence showing that WTC dust is potent in inducing mdig protein and/or mRNA in bronchial epithelial cells, B cells and MM cell lines. An increased mdig expression in MM bone marrow was observed, which is associated with the disease progression and prognosis of the MM patients. Through integrative genomics and proteomics approaches, we further demonstrated that mdig directly interacts with c-myc and JAK1 in MM cell lines, which contributes to hyperactivation of the IL-6-JAK-STAT3 signaling important for the pathogenesis of MM. Genetic silencing of mdig reduced activity of the major downstream effectors in the IL-6-JAK-STAT3 pathway. Taken together, these data suggest that WTC dust may be one of the key etiological factors for those who had been exposed for the development of MM by activating mdig and c-myc signaling circuit linked to the IL-6-JAK-STAT3 pathway essential for the tumorigenesis of the malignant plasma cells.

The proteomic investigation reveals interaction of mdig protein with the machinery of DNA double-strand break repair

To investigate how mineral dust-induced gene (mdig, also named as mina53, MINA, or NO52) promotes carcinogenesis through inducing active chromatin, we performed proteomics analyses for the interacting proteins that were co-immunoprecipitated by anti-mdig antibody from either the lung cancer cell line A549 cells or the human bronchial epithelial cell line BEAS-2B cells. On SDS-PAGE gels, three to five unique protein bands were consistently observed in the complexes pulled-down by mdig antibody, but not the control IgG. In addition to the mdig protein, several DNA repair or chromatin binding proteins, including XRCC5, XRCC6, RBBP4, CBX8, PRMT5, and TDRD, were identified in the complexes by the proteomics analyses using both Orbitrap Fusion and Orbitrap XL nanoESI-MS/MS in four independent experiments. The interaction of mdig with some of these proteins was further validated by co-immunoprecipitation using antibodies against mdig and its partner proteins, respectively. These data, thus, provide evidence suggesting that mdig accomplishes its functions on chromatin, DNA repair and cell growth through interacting with the partner proteins.

MYC-induced nuclear antigen (MINA) and preeclampsia

BACKGROUND

Inadequate trophoblast invasion and the subsequent inflammatory response have been implicated in preeclampsia (PE) pathogenesis. Because MYC-induced nuclear antigen (MINA) gene expression is involved in cell proliferation and differentiation, inflammatory response modulation, and the unpaired regulation of which is associated with human diseases, we sought to investigate the connection between MINA and PE.

OBJECTIVE

The aim of this study was to evaluate the possible relationship between the MINA rs4857304 variant and susceptibility to PE development as well as to estimate placental MINA gene expression and its association with PE.

METHODS

About 242 pregnant women (126 PE cases and 116 controls) were included. MINA genotyping and gene expression were evaluated by quantitative real-time polymerase chain reaction using TaqMan probes.

RESULTS

The G/G genotype of the MINA rs4857304 variant was associated with severe PE (p = 0.027, OR = 1.8, 95% CI = 1.8-3.2). Carriers of one G allele of the MINA rs4857304 variant exhibited a 1.7-fold increased risk of severe PE (p = 0.029, 95% CI = 1.1-3.0). MINA was underexpressed in preeclamptic placentas and MINA expression differed between the mild and severe PE groups. Differences in the expression levels of MINA were found among women with the T/T genotype of the rs4857304 polymorphism and carriers of at least one G allele (p = 0.024).

CONCLUSION

PE and its severity are associated with the underexpression of placental MINA, and the G/G genotype of the MINA rs4857304 variant may modify the risk of severe PE among the PE cases evaluated.

Oncoprotein mdig contributes to silica-induced pulmonary fibrosis by altering balance between Th17 and Treg T cells

Mineral dust-induced gene (mdig, also named Mina53) was first identified from alveolar macrophages of the coal miners with chronic lung inflammation or fibrosis, but how this gene is involved in lung diseases is poorly understood. Here we show that heterozygotic knockout of mdig (mdig+/-) ameliorates silica-induced lung fibrosis by altering the balance between Th17 cells and Treg cells. Relative to the wild type (WT) mice, infiltration of the macrophages and Th17 cells was reduced in lungs from silica-exposed mdig+/- mice. In contrast, an increased infiltration of the T regulatory (Treg) cells to the lung intestitium was observed in the mdig+/- mice treated with silica. Both the number of Th17 cells in the lung lymph nodes and the level of IL-17 in the bronchoalveolar lavage fluids were decreased in the mdig+/- mice in response to silica. Thus, these results suggest that mdig may contribute to silica-induced lung fibrosis by altering the balance between Th17 and Treg cells. Genetic deficiency of mdig impairs Th17 cell infiltration and function, but favors infiltration of the Treg cells, the immune suppressive T cells that are able to limit the inflammatory responses by repressing the Th17 cells and macrophages.

Mild Glucose Starvation Induces KDM2A-Mediated H3K36me2 Demethylation through AMPK To Reduce rRNA Transcription and Cell Proliferation

Environmental conditions control rRNA transcription. Previously, we found that serum and glucose deprivation induces KDM2A-mediated H3K36me2 demethylation in the rRNA gene (rDNA) promoter and reduces rRNA transcription in the human breast cancer cell line MCF-7. However, the molecular mechanism and biological significance are still unclear. In the present study, we found that glucose starvation alone induced the KDM2A-dependent reduction of rRNA transcription. The treatment of cells with 2-deoxy-d-glucose, an inhibitor of glycolysis, reduced rRNA transcription and H3K36me2 in the rDNA promoter, both of which were completely dependent on KDM2A in low concentrations of 2-deoxy-d-glucose, that is, mild starvation conditions. The mild starvation induced these KDM2A activities through AMP-activated kinase (AMPK) but did not affect another AMPK effector of rRNA transcription, TIF-IA. In the triple-negative breast cancer cell line MDA-MB-231, the mild starvation also reduced rRNA transcription in a KDM2A-dependent manner. We detected KDM2A in breast cancer tissues irrespective of their estrogen receptor, progesterone receptor, and HER2 status, including triple-negative cancer tissues. In both MCF-7 and MDA-MB-231 cells, mild starvation reduced cell proliferation, and KDM2A knockdown suppressed the reduction of cell proliferation. These results suggest that under mild glucose starvation AMPK induces KDM2A-dependent reduction of rRNA transcription to control cell proliferation.

Current understanding of mdig/MINA in human cancers

Mineral dust-induced gene, mdig has recently been identified and is known to be overexpressed in a majority of human cancers and holds predictive power in the poor prognosis of the disease. Mdig is an environmentally expressed gene that is involved in cell proliferation, neoplastic transformation and immune regulation. With the advancement in deciphering the prognostic role of mdig in human cancers, our understanding on how mdig renders a normal cell to undergo malignant transformation is still very limited. This article reviews the current knowledge of the mdig gene in context to human neoplasias and its relation to the clinico-pathologic factors predicting the outcome of the disease in patients. It also emphasizes on the promising role of mdig that can serve as a potential candidate for biomarker discovery and as a therapeutic target in inflammation and cancers. Considering the recent advances in understanding the underlying mechanisms of tumor formation, more preclinical and clinical research is required to validate the potential of using mdig as a novel biological target of therapeutic and diagnostic value.

Potential effects of Mina53 on tumor growth in human pancreatic cancer

Myc-induced nuclear antigen (Mina53) is a protein with a molecular weight of 53 kDa expression of which is induced by c-Myc. Increased expression of Mina53 is documented in some human carcinomas. In this study, we found markedly increased Mina53 expression in pancreatic cancer tissue specimens. This expression did not correlate with clinicopathological characteristics, such as sex, age, and presence of distant metastasis. However, there was a statistically significant association with histological differentiation, TNM stage, and lymph node metastases. To study functional role of Mina53, we silenced its expression by siRNA in PANC-1 cells. These cells were arrested in the G2/M phase, and apoptosis rates were increased. In conclusion, increased expression of Mina53 may play an important role in the development of human pancreatic cancer. Mina53 can be used as a marker for pancreatic cancer and may potentially be exploited as a target for treatment of pancreatic cancer.

Mdig, a lung cancer-associated gene, regulates cell cycle progression through p27(KIP1)

Mineral dust-induced gene (mdig) can accelerate cell proliferation. The aim of this study is to investigate the mechanism by which mdig regulates cell proliferation. A549 cells were transfected with siRNA specifically targeting mdig. Cell proliferation and cell cycle progression were measured using MTT assay and cell cycle analysis, respectively. Furthermore, real-time reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was performed in A549 cells transfected with mdig siRNA to examine the expression levels of the cell cycle related genes such as p18(INK4c), p19(INK4d), p21(WAF/CIP1), p27(KIP1), p57(KIP2), cyclin D1, and cyclin E. To further explore the effect of mdig on p27(KIP1), the expression levels of total p27(KIP1) and its subtypes pT187-p27(KIP1) and pS10-p27(KIP1) were assessed by Western blotting. In vivo, Western blotting was performed to check the expression levels of mdig and p27(KIP1) in human lung cancer tissues, para-cancerous normal lung tissues, and para-bronchial stumps. Knockdown of mdig induced increases in p27(KIP1), both on mRNA and protein levels. Furthermore, the phosphorylation of p27(KIP1) at its Thr187 site was also inhibited. Importantly, in lung cancer tissues, upregulation of mdig expression accompanies with the downregulation of p27(KIP1) expression and in bronchial stump, vice versa. The data suggest that mdig-mediated inhibition of p27(KIP1) is important for cell proliferation and tumor formation and reveal therapeutic potential of p27(KIP1) for lung cancer.

Modifying the maker: Oxygenases target ribosome biology

The complexity of the eukaryotic protein synthesis machinery is partly driven by extensive and diverse modifications to associated proteins and RNAs. These modifications can have important roles in regulating translation factor activity and ribosome biogenesis and function. Further investigation of ‘translational modifications’ is warranted considering the growing evidence implicating protein synthesis as a critical point of gene expression control that is commonly deregulated in disease. New evidence suggests that translation is a major new target for oxidative modifications, specifically hydroxylations and demethylations, which generally are catalyzed by a family of emerging oxygenase enzymes that act at the interface of nutrient availability and metabolism. This review summarizes what is currently known about the role or these enzymes in targeting rRNA synthesis, protein translation and associated cellular processes.

Mdig de-represses H19 large intergenic non-coding RNA (lincRNA) by down-regulating H3K9me3 and heterochromatin

Mineral dust-induced gene (mdig) had been linked to the development of human lung cancers associated with environmental exposure to mineral dust, tobacco smoke or other carcinogens. In the present studies, we demonstrated that the overexpression of mdig in A549 adenocarcinomic human alveolar type II epithelial cells decreases the heterochromatin conformation of the cells and de-represses the transcription of genes in the tandemly repeated DNA regions. Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression. Silencing mdig by either shRNA or siRNA not only increased the level of H3K9me3 in the promoter region of H19 but also attenuated the transcription of H19 long non-coding RNA. Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3. Clinically, we found that higher levels of mdig and H19 expression correlate with poorer survival of the lung cancer patients. Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

Mdig de-represses H19 large intergenic non-coding RNA (lincRNA) by down-regulating H3K9me3 and heterochromatin

Mineral dust-induced gene (mdig) had been linked to the development of human lung cancers associated with environmental exposure to mineral dust, tobacco smoke or other carcinogens. In the present studies, we demonstrated that the overexpression of mdig in A549 adenocarcinomic human alveolar type II epithelial cells decreases the heterochromatin conformation of the cells and de-represses the transcription of genes in the tandemly repeated DNA regions. Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression. Silencing mdig by either shRNA or siRNA not only increased the level of H3K9me3 in the promoter region of H19 but also attenuated the transcription of H19 long non-coding RNA. Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3. Clinically, we found that higher levels of mdig and H19 expression correlate with poorer survival of the lung cancer patients. Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

Carcinogenic metalloid arsenic induces expression of mdig oncogene through JNK and STAT3 activation

Environmental or occupational exposure to arsenic, a chemical element classified as metalloid, has been associated with cancer of the lung, skin, bladder, liver, etc. Mdig (mineral dust-induced gene) is a newly identified oncogene linked to occupational lung diseases and lung cancer. It is unclear whether mdig is also involved in arsenic-induced malignant transformation of the lung cells. By using human bronchial epithelial cells and human lung cancer cell lines, we showed that arsenic was able to induce expression of mdig. We further demonstrated that this mdig induction by arsenic was partially dependent on the JNK and STAT3 signaling pathways. Disruption of the JNK or STAT3 by either chemical inhibitors or siRNAs diminished arsenic-induced accumulation of mdig mRNA and protein. Furthermore, we also showed that microRNA-21 (miR-21) and Akt were down-stream effectors of the JNK and STAT3 signaling pathways in arsenic-induced mdig expression. Transfection of the cells with anti-miR-21 or pre-treatment of the cells with Akt inhibitor blunted mdig induction by arsenic. Clinically, the levels of mdig can be applied to predict the disease progression, the first progression (FP), in non-small cell lung cancer (NSCLC) patients. Taken together, our data suggest that mdig may play important roles on the pathogenesis of arsenic-induced lung cancer and that JNK and STAT3 signaling pathways are essential in mediating arsenic-induced mdig expression.

Structure and functional analysis of YcfD, a novel 2-oxoglutarate/Fe²⁺-dependent oxygenase involved in translational regulation in Escherichia coli

The 2-oxoglutarate (2OG)/Fe²⁺-dependent oxygenases (2OG oxygenases) are a large family of proteins that share a similar overall three-dimensional structure and catalyze a diverse array of oxidation reactions. The Jumonji C (JmjC)-domain-containing proteins represent an important subclass of the 2OG oxygenase family that typically catalyze protein hydroxylation; however, recently, other reactions have been identified, such as tRNA modification. The Escherichia coli gene, ycfD, was predicted to be a JmjC-domain-containing protein of unknown function based on primary sequence. Recently, YcfD was determined to act as a ribosomal oxygenase, hydroxylating an arginine residue on the 50S ribosomal protein L-16 (RL-16). We have determined the crystal structure of YcfD at 2.7 Å resolution, revealing that YcfD is structurally similar to known JmjC proteins and possesses the characteristic double-stranded β-helix fold or cupin domain. Separate from the cupin domain, an additional globular module termed α-helical arm mediates dimerization of YcfD. We further have shown that 2OG binds to YcfD using isothermal titration calorimetry and identified key binding residues using mutagenesis that, together with the iron location and structural similarity with other cupin family members, allowed identification of the active site. Structural homology to ribosomal assembly proteins combined with GST (glutathione S-transferase)-YcfD pull-down of a ribosomal protein and docking of RL-16 to the YcfD active site support the role of YcfD in regulation of bacterial ribosome assembly. Furthermore, overexpression of YcfD is shown to inhibit cell growth signifying a toxic effect on ribosome assembly.

Paradoxical roles of mineral dust induced gene on cell proliferation and migration/invasion

Increased expression of mineral dust-induced gene (mdig, also named as mina53, MINA, or NO52) has been observed in a number of human cancers. The mechanism of how mdig contribute to the pathogenesis of cancer remains to be fully elucidated. In this report, we demonstrated that overexpression of mdig decreased the nuclear staining signal by 4′,6-diamidino-2-phenylindole (DAPI), along with a considerable enhancement in cell proliferation. Silencing mdig by shRNA resulted in a statistically significant decrease of cell proliferation. Intriguingly, mdig overexpression reduced the capacity of the cells in migration and invasion in vitro, whereas silencing mdig by shRNA/siRNA enhanced migration and invasion. Clinically, we found that increased expression of mdig in cancer tissues correlates with poorer overall survival of the lung cancer patients, esp., for those without lymph node metastasis. Taken together, our results suggest that mdig plays opposite roles on cell growth and motility, which possibly indicates the paradoxical effect of mdig at the different stages of carcinogenesis.

The roles of Jumonji-type oxygenases in human disease

The iron- and 2-oxoglutarate-dependent oxygenases constitute a phylogenetically conserved class of enzymes that catalyze hydroxylation reactions in humans by acting on various types of substrates, including metabolic intermediates, amino acid residues in different proteins and various types of nucleic acids. The discovery of jumonji (Jmj), the founding member of a class of Jmj-type chromatin modifying enzymes and transcriptional regulators, has culminated in the discovery of several branches of histone lysine demethylases, with essential functions in regulating the epigenetic landscape of the chromatin environment. This work has now been considerably expanded into other aspects of epigenetic biology and includes the discovery of enzymatic steps required for methyl-cytosine demethylation as well as modification of RNA and ribosomal proteins. This overview aims to summarize the current knowledge on the human Jmj-type enzymes and their involvement in human pathological processes, including development, cancer, inflammation and metabolic diseases.

Mina53, a novel molecular marker for the diagnosis and prognosis of gastric adenocarcinoma

Mina53 is a direct novel target protein of Myc. The present study investigated the expression of mina53 and c-myc in gastric carcinoma and the relationship between Mina53 expression and clinicopathological features. The expression levels of mina53 and c-myc mRNA and protein in gastric cancers and the adjacent normal tissues from 12 patients were assessed by laser-capture microdissection (LCM) combined with quantitative polymerase chain reaction (qPCR) and western blotting, respectively. Immunohistochemical analysis was used to evaluate the expression of the Mina53 protein in normal gastric tissues (n=30), chronic atrophic gastritis without intestinal metaplasia (n=44), intestinal metaplasia (n=34), gastric dysplasia (n=36), intestinal-type gastric carcinoma (IGC) (n=30) and diffuse-type gastric carcinoma (DGC) (n=34). The correlation between expression of mina53 and patient survival time was also investigated. The expression levels of mina53 and c-myc mRNA in the gastric carcinomas were found to be higher when compared to these levels in the adjacent normal tissues. In addition, the expression levels of Mina53 and c-Myc protein in gastric carcinomas were higher when compared with levels in the adjacent normal epithelium. mina53 expression was significantly increased during gastric carcinogenesis and was correlated with different clinicopathological factors in IGC and DGC. The prognosis of patients with low expression of Mina53 was more favorable when compared to the prognosis of patients with high expression of Mina53. mina53 expression was gradually elevated during gastric carcinogenesis, and the overexpression of mina53 was correlated with different clinicopathological features between DGC and IGC cases. Furthermore, the prognosis of gastric carcinoma patients was significantly correlated with the expression of Mina53.

Transcriptional activation of Mina by Sp1/3 factors

Mina is an epigenetic gene regulatory protein known to function in multiple physiological and pathological contexts, including pulmonary inflammation, cell proliferation, cancer and immunity. We showed previously that the level of Mina gene expression is subject to natural genetic variation linked to 21 SNPs occurring in the Mina 5′ region [1]. In order to explore the mechanisms regulating Mina gene expression, we set out to molecularly characterize the Mina promoter in the region encompassing these SNPs. We used three kinds of assays – reporter, gel shift and chromatin immunoprecipitation – to analyze a 2 kb genomic fragment spanning the upstream and intron 1 regions flanking exon 1. Here we discovered a pair of Mina promoters (P1 and P2) and a P1-specific enhancer element (E1). Pharmacologic inhibition and siRNA knockdown experiments suggested that Sp1/3 transcription factors trigger Mina expression through additive activity targeted to a cluster of four Sp1/3 binding sites forming the P1 promoter. These results set the stage for comprehensive analysis of Mina gene regulation from the context of tissue specificity, the impact of inherited genetic variation and the nature of upstream signaling pathways.

Increased expression of mdig predicts poorer survival of the breast cancer patients

Breast cancer is the most common cancer and the second leading cause of cancer death among women of all races and Hispanic origin populations in the United States. In the present study, we reported that the survival time of the breast cancer patients is influenced by the expression level of mdig, a previously identified lung cancer-associated oncogene encoding a JmjC-domain protein. By checking the expression levels of mRNA and protein of mdig through both RT-PCR and immunohistochemistry in samples from 204 patients, we noticed that about 30% of breast cancer samples showed increased expression of mdig. Correlation of the mdig expression levels with the survival time of the breast cancer patients indicated a clear inverse relationship between mdig expression and patient survival, including poorer overall survival, distant metastasis free survival, relapse free survival, and post-progression survival. Taken together, these data suggest that an increased expression of mdig is an important prognostic factor for poorer survival time of the breast cancer patients.

Ablation of Mina53 in mice reduces allergic response in the airways

The mina53 (myc-induced nuclear antigen with a 53 kDa molecular mass; also known as mina) was identified as a direct transcriptional target of the oncoprotein Myc and encodes a conserved protein in vertebrates. While Mina53 is known to be associated with tumorigenesis, it is not clear what role Mina53 plays in non-neoplastic tissues. To directly address the roles of Mina53 in non-neoplastic tissues, we created mina53-deficient mice. Both male and female mina53-deficient mice reached adulthood and were fertile, suggesting that Mina53 is dispensable for the basic developmental processes. Since we found that Mina53 was expressed in cells responsible for immune responses, we investigated whether Mina53 was involved in immune responses. When mice were exposed intranasally to house dust mites as an allergen, the airway tract showed hyperresponsiveness to methacholine in wild-type mice but not in mina53-deficient mice. The mina53-deficient mice also showed a significantly reduced migration of immune cells, including eosinophils, into bronchoalveolar lavage fluid compared with wild-type mice. The levels of Th2 cytokines, IL-4 and IL-5, produced in response to house dust mites were lower in the mina53-deficient mice than in wild-type mice. The level of IFN-γ in bronchoalveolar lavage fluid was significantly decreased by exposure to house dust mites in wild-type mice but not in the mina53-deficient mice. These results suggest that Mina53 plays a role in the allergic response to inhaled allergens, possibly through controlling IL-4 production.

Oxygenase-catalyzed ribosome hydroxylation occurs in prokaryotes and humans

The finding that oxygenase-catalyzed protein hydroxylation regulates animal transcription raises questions as to whether the translation machinery and prokaryotic proteins are analogously modified. Escherichia coli ycfD is a growth-regulating 2-oxoglutarate oxygenase catalyzing arginyl hydroxylation of the ribosomal protein Rpl16. Human ycfD homologs, Myc-induced nuclear antigen (MINA53) and NO66, are also linked to growth and catalyze histidyl hydroxylation of Rpl27a and Rpl8, respectively. This work reveals new therapeutic possibilities via oxygenase inhibition and by targeting modified over unmodified ribosomes.

pVHL-mediated transcriptional repression of c-Myc by recruitment of histone deacetylases

The biological functions of Myc are to regulate cell growth,apoptosis, cell differentiation and stem-cell self-renewal. Abnormal accumulation of c-Myc is able to induce excessive proliferation of normal cells. von Hippel-Lindau protein(pVHL) is a key regulator of hypoxia-inducible factor 1α(HIF1α), thus accumulation and hyperactivation of HIF1α is the most prominent feature of VHL-mutated renal cell carcinoma. Interestingly, the Myc pathway is reported to be activated in renal cell carcinoma even though the precise molecular mechanism still remains to be established. Here, we demonstrated that pVHL locates at the c-Myc promoter region through physical interaction with Myc. Furthermore, pVHL reinforces HDAC1/2 recruitment to the Myc promoter, which leads to the auto-suppression of Myc. Therefore, one possible mechanism of Myc auto-suppression by pVHL entails removing histone acetylation. Our study identifies a novel mechanism for pVHL-mediated negative regulation of c-Myc transcription.

Associations of the single-nucleotide polymorphisms of the Mina gene with the development of asthma in Chinese Han children: a case-control study

The single-nucleotide polymorphisms (SNPs) of the Mina gene in animals are associated with the development of Th2-mediated diseases. However, there is no information whether the association occurs in humans. This case-control study aimed at examining the potential association of the SNP of the Mina gene with the development of asthma in Chinese Han children. The DNA genotypes and serum immunoglobulin E and interleukin-4 levels of 202 asthmatic patients and 191 nonasthmatic subjects were determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry method and enzyme-linked immunosorbent assay, respectively. We found that the frequency of the T allele of rs4857304, but not rs832081, rs832078, rs9879532, and rs17374916, in the Mina gene in asthmatic patients was significantly higher than that of controls (p = 0.0199). Using a recessive model, we found that the percentage of patients with TT homozygous rs4857304 was significantly higher than that of controls (p = 0.0282, odds ratio=1.568, 95% confidence interval=1.048-2.346). Further, the mean levels of serum immunoglobulin E and interleukin-4 in the patients with TT genotype of rs4857304 were significantly higher than that of patients with the G allele (p = 0.000 and p = 0.03, respectively). Apparently, the T allele of rs4857304 of the Mina gene may be associated with increased risk for the development of asthma in Chinese Han children.

von Hippel-Lindau protein promotes Skp2 destabilization on DNA damage

Germline mutations in the von Hippel-Lindau (VHL) tumor suppressor gene cause VHL disease, a rare and autosomal-dominant genetic syndrome. Because VHL protein (pVHL) is the master regulator of hypoxia-inducible factor alpha (HIFα), the most prominent feature of VHL disease is the deregulation of HIFα proteins. However, the precise mechanism by which the loss of pVHL function contributes to tumorigenesis is not fully understood. Here, we show that pVHL destabilizes the F-box protein Skp2, a chief component of Skp, Cullin, F-box-containing complex that promotes DNA synthesis in the S phase. The β-domain of pVHL interacts with Skp2, stimulating proteasome-dependent Skp2 degradation, but the destabilization of Skp2 does not depend on the E3 ubiquitin ligase activity of pVHL. Notably, the generation of DNA damage induces Skp2 degradation, which is attenuated by the suppression of endogenous pVHL expression. One possible mechanism of pVHL-dependent Skp2 degradation entails the antagonizing of Akt-mediated Skp2 phosphorylation, which maintains Skp2 stability. Reintroduction of VHL into VHL-null renal cell carcinoma (RCC) cells decreased Skp2 levels and restored DNA damage-dependent Skp2 degradation. These results identify the tumor suppressor function of pVHL in delaying the S-phase progression to inhibit cell proliferation on DNA damage. Clinically, this report explains as to why Skp2 accumulates abnormally in RCC tissues.

Significance of expression of Mina53 in colon cancer

AIM: To detect the expression of Mina53 (myc-induced nuclear antigen with a molecular mass of 53 000 Da) and to analyze its clinical significance in colon cancer.

METHODS: The expression of Mina53 and Ki67 mRNAs was detected by real-time PCR in 51 colon cancer samples, 19 colon adenoma samples, and 20 normal colon tissue samples.

RESULTS: The expression level of Mina53 in colon cancer was significantly higher than those in colon adenoma and normal colon tissue (1.369 ± 0.874 vs 0.453 ± 0.233, 0.347 ± 0.128, both P < 0.05). Mina53 expression was significantly associated with tumor differentiation, Dukes stage, distant metastasis, and lymph node metastasis in colon cancer (all P < 0.05). Mina53 expression was positively associated with Ki67 expression in colon cancer (r = 0.727, P < 0.01).

CONCLUSION: Mina53 was overexpressed in colon cancer, which may be associated with tumor proliferation. Mina53 may play an important role in the carcinogenesis of colon carcinoma.

A phase II trial of doxorubicin and gemcitabine in renal cell carcinoma with sarcomatoid features: ECOG 8802

Sarcomatoid features can arise in renal cell carcinoma of any subtype and are associated with a poor prognosis. Doxorubicin and gemcitabine in a limited series showed activity in aggressive renal tumors and we wished to formally assess the combination in patients with renal cell carcinoma specifically containing sarcomatoid features. The Eastern Cooperative Oncology Group (ECOG) conducted a phase II trial of doxorubicin 50 mg/m(2) IV push and gemcitabine 1,500 mg/m(2) IV over 30 min every 2 weeks in 39 patients with locally advanced or metastatic renal cell carcinoma with sarcomatoid features. Ten patients (26%) had grade 3 toxicity, and four patients (11%) had grade 4 toxicities. Although most toxicity was from myelosuppression, one patient died on study from cardiac dysfunction after a cumulative dose of 450 mg/m(2) doxorubicin. Six (16%) patients experienced responses (5 partial responses and 1 complete response), and ten (26%) patients had stable disease. In addition, another patient had an unconfirmed partial response and an additional patient experienced over 50% decrease in her tumor burden after an initial progression. The median overall survival was 8.8 months, and the median progression-free survival was 3.5 months. We conclude that the combination of doxorubicin and gemcitabine, inactive in patients with mostly clear cell histology, demonstrated responses in patients with RCC with sarcomatoid features. We acknowledge the toxicity of this combination but note that limited treatment options exist for this aggressive histology. Only through prospective multicenter trials with comprehensive central pathology review will better treatment options be identified.

Long-term survival of patients with sarcomatoid renal cell cancer treated with chemotherapy

Sarcomatoid renal cell cancer is associated with a very poor prognosis, characterized by rapid progression of advanced disease. We previously reported the outcome of 18 patients with advanced sarcomatoid renal cell cancer treated with a regimen consisting of doxorubicin, 50 mg/m2 and gemcitabine, 1,500-2,000 mg/m2, administered every two weeks with growth factor support (A/G). Among the 18 patients, there were two complete and 5 partial responses and two patients with stable disease of more than 6 months of duration. We now report long-term survival of 4 patients with stage IV sarcomatoid renal cell carcinoma treated with this regimen at the 1,500 mg/m2 dose of gemcitabine, and achieving complete response (2 patients), or rendered complete responders following surgery after maximum response (2 patients). The two complete responders are alive, disease free at 6+ and 8+ years after starting A/G, and the 2 patients rendered CR by surgery survived 3½ and 6 years, respectively. Both died of progressive disease, one with clear cell recurrence, one with sarcomatoid recurrence. In summary, this regimen is associated with a high response rate, overall improvement in progression free survival and occasional meaningful long-term survival in a disease expected to be fatal within one year.

JmjC enzyme KDM2A is a regulator of rRNA transcription in response to starvation

The rate-limiting step in ribosome biogenesis is the transcription of ribosomal RNA, which is controlled by environmental conditions. The JmjC enzyme KDM2A/JHDM1A/FbxL11 demethylates mono- and dimethylated Lys 36 of histone H3, but its function is unclear. Here, we show that KDM2A represses the transcription of ribosomal RNA. KDM2A was localized in nucleoli and bound to the ribosomal RNA gene promoter. Overexpression of KDM2A repressed the transcription of ribosomal RNA in a demethylase activity-dependent manner. When ribosomal RNA transcription was reduced under starvation, a cell-permeable succinate that inhibited the demethylase activity of KDM2A prevented the reduction of ribosomal RNA transcription. Starvation reduced the levels of mono- and dimethylated Lys 36 of histone H3 marks on the rDNA promoter, and treatment with the cell-permeable succinate suppressed the reduction of the marks during starvation. The knockdown of KDM2A increased mono- and dimethylated Lys 36 of histone H3 marks, and suppressed the reduction of ribosomal RNA transcription under starvation. These results show a novel mechanism by which KDM2A activity is stimulated by starvation to reduce ribosomal RNA transcription.

Accelerated expression of a Myc target gene Mina53 in aggressive hepatocellular carcinoma

AIM

Expressions of the myc target genes Mina53 and mimitin are high in esophageal squamous cell carcinoma and colon cancer, and their relationship to cell proliferation and patient prognosis has been reported. Because c-myc gene expression is closely related to hepatocellular carcinoma (HCC) growth or formation and/or maintenance, we examined the Mina53 and mimitin expressions in HCC.

METHODS

Surgically resected 53 HCC tissues were immunohistochemically examined for Mina53 and mimitin expressions and their relationship to clinicopathological factors.

RESULTS

Diffuse Mina53 expression was observed in the nuclei of cancer cells in the tumor nodule, but was often strong at the periphery of tumor nodules. Diffuse or scattered expression of mimitin was observed in the cytoplasm of HCC cells in tumor nodules. Mina53 expression was higher in poorly differentiated HCC than in well-differentiated HCC, and significant relationship to histological grade was observed. The cases with a high Mina53 expression also had a high expression of a proliferation marker MIB-1. This suggested the involvement of Mina53 in cell proliferation. Mina53 expression was high in the tumors of >2 cm of diameter than in </=2 cm (P < 0.01). Mimitin expression tended to be high in tumors of >2 cm, but no significant relationship was observed either to histological grade, MIB-1 expression, or the other clinicopathologic factors.

CONCLUSIONS

Our findings suggested that Mina53 expression is accelerated in HCC with a lower histological grade, with cell proliferation capability, or with a larger diameter, and Mina53 is related to biological malignancy of HCC.

Expression of Mina53, a novel c-Myc target gene, is a favorable prognostic marker in early stage lung cancer

Mina53, a novel target gene product of c-Myc, is overexpressed in various malignancies. We previously demonstrated that Mina53 is overexpressed in lung cancer patients from the early clinical stages. In this paper, the association between disease prognosis and Mina53 expression in lung cancer patients is analyzed; we found that overexpression of Mina53 in lung cancer patients is associated with favorable prognosis. Statistical analysis using the Kaplan-Meier method showed that patients with negative staining for Mina53 had significantly shorter survival than patients with positive staining for Mina53, especially in stage I or with squamous cell carcinoma. Because the major cause of death in lung cancer patients after surgery is distant metastasis, the effect on cancer cell invasiveness was analyzed for the mechanisms involved in the association with favorable outcome. Overexpression of Mina53 in H226B, a lung squamous cell carcinoma cell line, inhibited cancer cell invasion. Transfection with mina53 shRNA increased the number of invading cells. These results suggest that Mina53 immunostaining is a useful prognostic marker--especially in the early stage of lung cancer--and that Mina53 negative patients should be managed particularly carefully after surgery.

Histone demethylases and cancer

Epigenetic modifications are heritable chromatin alterations that contribute to the temporal and spatial interpretation of the genome. The epigenetic information is conveyed through a multitude of chemical modifications, including DNA methylation, reversible modifications of histones, and ATP-dependent nucleosomal remodeling. Deregulation of the epigenetic machinery contributes to the development of several pathologies, including cancer. Chromatin modifications are multiple and interdependent and they are dynamically modulated in the course of various biological processes. Combinations of chromatin modifications give rise to a complex code that is superimposed on the genetic code embedded into the DNA sequence to regulate cell function. This review addresses the role of epigenetic modifications in cancer, focusing primarily on histone methylation marks and the enzymes catalyzing their removal.

Mina53, a novel c-Myc target gene, is frequently expressed in lung cancers and exerts oncogenic property in NIH/3T3 cells

PURPOSE

Mina53, whose expression is directly induced by c-Myc, is overexpressed in various cancers and plays an important role in cell growth. To clarify the involvement of Mina53 in lung cancers, we investigated its expression in human lung cancer tissues as well as in various lung cancer cell lines.

METHODS

Mina53 expression was determined by real-time RT-PCR, western blotting, and immunohistochemistry using lung cancer cell lines, normal human bronchial epithelial cells, and lung cancer tissues. Biological effects of Mina53 were evaluated by soft agar colony formation assay and tumorigenicity in nude mice using Mina53-transfected NIH/3T3 cells. cDNA microarray analysis was performed to determine the gene alteration by Mina53 and confirmation was made using real-time RT-PCR with mina53 expression plasmid or mina53 shRNA-transfected NIH/3T3 cells.

RESULTS

We observed that 62% of patients evidenced overexpression of Mina53 from the early clinical stages of lung cancer. Differences according to gender, smoking status, or histologic type were not statistically significant. Forced expression of Mina53 in NIH/3T3 cells induced cell transformation, and mina53-transfected NIH/3T3 clones produced tumors in nude mice, demonstrating that Mina53 has oncogenic potential. cDNA microarray revealed that 254 genes had altered expression in a mina53-transfected NIH/3T3 clone. Mina53 regulates several genes related to cell adhesion and metabolism, which have also been reported to be regulated by c-Myc. Genes regulated by Mina53, but not by c-Myc included cytokine/growth factor related genes such as EGFR, IL-6, and HGF.

CONCLUSION

Our results suggest that Mina53 plays an important role in carcinogenesis and may be a target for cancer prevention.

Mina53, a novel c-Myc target gene, is frequently expressed in lung cancers and exerts oncogenic property in NIH/3T3 cells

PURPOSE

Mina53, whose expression is directly induced by c-Myc, is overexpressed in various cancers and plays an important role in cell growth. To clarify the involvement of Mina53 in lung cancers, we investigated its expression in human lung cancer tissues as well as in various lung cancer cell lines.

METHODS

Mina53 expression was determined by real-time RT-PCR, western blotting, and immunohistochemistry using lung cancer cell lines, normal human bronchial epithelial cells, and lung cancer tissues. Biological effects of Mina53 were evaluated by soft agar colony formation assay and tumorigenicity in nude mice using Mina53-transfected NIH/3T3 cells. cDNA microarray analysis was performed to determine the gene alteration by Mina53 and confirmation was made using real-time RT-PCR with mina53 expression plasmid or mina53 shRNA-transfected NIH/3T3 cells.

RESULTS

We observed that 62% of patients evidenced overexpression of Mina53 from the early clinical stages of lung cancer. Differences according to gender, smoking status, or histologic type were not statistically significant. Forced expression of Mina53 in NIH/3T3 cells induced cell transformation, and mina53-transfected NIH/3T3 clones produced tumors in nude mice, demonstrating that Mina53 has oncogenic potential. cDNA microarray revealed that 254 genes had altered expression in a mina53-transfected NIH/3T3 clone. Mina53 regulates several genes related to cell adhesion and metabolism, which have also been reported to be regulated by c-Myc. Genes regulated by Mina53, but not by c-Myc included cytokine/growth factor related genes such as EGFR, IL-6, and HGF.

CONCLUSION

Our results suggest that Mina53 plays an important role in carcinogenesis and may be a target for cancer prevention.