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

Deletion of mdig enhances H3K36me3 and metastatic potential of the triple negative breast cancer cells

In this report, we provide evidence showing diminished expression of the mineral dust-induced gene (mdig), a previously identified oncogenic gene, in human triple negative breast cancer (TNBC). Using a mouse model of orthotopic xenograft of the TNBC MDA-MB-231 cells, we demonstrate that mdig promotes the growth of primary tumors but inhibits metastasis of these cells in vivo. Knockout of mdig resulted in an enhancement of H3K36me3 in the genome and upregulation of some X chromosome-linked genes for cell motility, invasion, and metastasis. Silencing MAGED2, one of the most upregulated and H3K36me3-enriched genes resulted from mdig depletion, can partially reverse the invasive migration of the mdig knockout cells. The anti-metastatic and inhibitory role of mdig on H3K36me3 was cross-validated in another cell line, A549 lung cancer cells. Together, our data suggest that mdig is antagonist against H3K36me3 that enforces expression of genes, such as MAGED2, for cell invasion and metastasis.

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Loss of mdig expression in TNBC and metastatic breast cancer

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Knockout of mdig enforces metastasis of the TNBC cells

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Mdig antagonizes H3K36me3 that promotes expression of X-linked metastatic genes

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Silencing MAGED2 reduces invasive migration of the mdig knockout cells

Epigenetics and environment in breast cancer: New paradigms for anti-cancer therapies

Breast cancer remains the most frequently diagnosed cancer in women worldwide. Delayed presentation of the disease, late stage at diagnosis, limited therapeutic options, metastasis, and relapse are the major factors contributing to breast cancer mortality. The development and progression of breast cancer is a complex and multi-step process that incorporates an accumulation of several genetic and epigenetic alterations. External environmental factors and internal cellular microenvironmental cues influence the occurrence of these alterations that drives tumorigenesis. Here, we discuss state-of-the-art information on the epigenetics of breast cancer and how environmental risk factors orchestrate major epigenetic events, emphasizing the necessity for a multidisciplinary approach toward a better understanding of the gene-environment interactions implicated in breast cancer. Since epigenetic modifications are reversible and are susceptible to extrinsic and intrinsic stimuli, they offer potential avenues that can be targeted for designing robust breast cancer therapies.

Depletion of Mdig Changes Proteomic Profiling in Triple Negative Breast Cancer Cells

Triple-negative breast cancers are highly aggressive with an overall poor prognosis and limited therapeutic options. We had previously investigated the role of mdig, an oncogenic gene induced by some environmental risk factors, on the pathogenesis of breast cancer. However, a comprehensive analysis of the proteomic profile affected by mdig in triple-negative breast cancer has not been determined yet. Using label-free bottom-up quantitative proteomics, we compared wildtype control and mdig knockout MDA-MB-231 cells and identified the proteins and pathways that are significantly altered with mdig deletion. A total of 904 differentially expressed (p < 0.005) proteins were identified in the KO cells. Approximately 30 pathways and networks linked to the pathogenicity of breast cancer were either up- or downregulated, such as EIF2 signaling, the unfolded protein response, and isoleucine degradation I. Ingenuity Pathway Analysis established that the differentially expressed proteins have relevant biological actions in cell growth, motility, and malignancy. These data provide the first insight into protein expression patterns in breast cancer associated with a complete disruption of the mdig gene and yielded substantial information on the key proteins, biological processes, and pathways modulated by mdig that contribute to breast cancer tumorigenicity and invasiveness.

MDIG, a 2‑oxoglutarate‑dependent oxygenase, acts as an oncogene and predicts the prognosis of multiple types of cancer

Recent studies have indicated that mineral dust‑induced gene (MDIG) is an oncogene induced by environmental factors, which has a key role in the development and progression of various tumor types, through epigenetic modifications; however, there are no previous pan‑cancer analyses of MDIG. In the present study, a comprehensive pan‑cancer analysis of MDIG was performed using public databases. The results demonstrated that MDIG was upregulated in tumor tissue samples compared with normal tissue, that it was present in all cancer cell lines and it was closely associated with the prognosis of patients with different tumor types. Furthermore, MDIG expression was closely associated with the immunological characteristics of the tumor microenvironment (TME), such as the frequency of tumor‑infiltrating immune cells, TME‑relevant signatures, immunostimulatory genes, immune checkpoint genes, chemokine receptor genes, tumor mutational burden and microsatellite instability. In parallel, high expression of MDIG was associated with improved overall survival of patients and this was verified in a cohort of patients who had received anti‑programmed cell death 1 ligand 1 treatment. Furthermore, high expression of MDIG led to multiple drug resistance in The Cancer Genome Atlas‑lung adenocarcinoma cohort. In addition, gene set variant analysis and gene set enrichment analysis indicated that MDIG was involved in cell cycle regulation. In vitro experiments suggested that MDIG promoted cell proliferation through the mTOR complex 2/Akt and pyruvate dehydrogenase kinase 1/Akt signaling pathways. In summary, the present study suggests that MDIG may be a prognostic biomarker and therapeutic target for various cancer types.

The bioinformatics analysis of RIOX2 gene in lung adenocarcinoma and squamous cell carcinoma

Lung cancer is characterized by high morbidity and mortality rates, and it has become an important public health issue worldwide. The occurrence and development of tumors is a multi-gene and multi-stage complex process. As an oncogene, ribosomal oxygenase 2 (RIOX2) has been associated with a variety of cancers. In this article, we analyzed the correlation between RIOX2 expression and methylation in lung cancer based on the databases including the cancer genome atlas (TCGA) (https://portal.gdc.cancer.gov/) and the gene expression omnibus (GEO) (https://www.ncbi.nlm.nih.gov/geo/). It was found that RIOX2 is highly expressed in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) tissues, whose expression is negatively correlated with its methylation level. In this regard, methylation at cg09716038, cg14773523, cg14941179, and cg22299097 had a significant negative correlation with RIOX2 expression in LUAD, whereas in LUSC, methylation at cg09716038, cg14773523, cg14941179, cg22299097, cg05451573, cg10779801, and cg23629183 is negatively correlated with RIOX2 expression. According to the analysis based on the databases, RIOX2 gene could not be considered as the independent prognostic biomarker in lung adenocarcinoma or squamous cell lung cancer. However, the molecular mechanism of RIOX2 gene in the development of lung cancer may be helpful in improving lung cancer therapy.

Environmentally-induced mdig contributes to the severity of COVID-19 through fostering expression of SARS-CoV-2 receptor NRPs and glycan metabolism

The novel β-coronavirus, SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19), has infected more than 177 million people and resulted in 3.84 million death worldwide. Recent epidemiological studies suggested that some environmental factors, such as air pollution, might be the important contributors to the mortality of COVID-19. However, how environmental exposure enhances the severity of COVID-19 remains to be fully understood. In the present report, we provided evidence showing that mdig, a previously reported environmentally-induced oncogene that antagonizes repressive trimethylation of histone proteins, is an important regulator for SARS-CoV-2 receptors neuropilin-1 (NRP1) and NRP2, cathepsins, glycan metabolism and inflammation, key determinants for viral infection and cytokine storm of the patients. Depletion of mdig in bronchial epithelial cells by CRISPR-Cas-9 gene editing resulted in a decreased expression of NRP1, NRP2, cathepsins, and genes involved in protein glycosylation and inflammation, largely due to a substantial enrichment of lysine 9 and/or lysine 27 trimethylation of histone H3 (H3K9me3/H3K27me3) on these genes as determined by ChIP-seq. Meanwhile, we also validated that environmental factor arsenic is able to induce mdig, NRP1 and NRP2, and genetic disruption of mdig lowered expression of NRP1 and NRP2. Furthermore, mdig may coordinate with the Neanderthal variants linked to an elevated mortality of COVID-19. These data, thus, suggest that mdig is a key mediator for the severity of COVID-19 in response to environmental exposure and targeting mdig may be the one of the effective strategies in ameliorating the symptom and reducing the mortality of COVID-19.

Pathological and Prognostic Indications of the mdig Gene in Human Lung Cancer

BACKGROUND/AIMS

The mineral-dust-induced gene mdig is a lung-cancer-associated oncogene. The focus of this study is to evaluate the expression status of mdig in lung cancer and to assess its influence in predicting the patient's overall survival.

METHODS

Using high-density tissue microarrays and clinical samples of synchronous multiple primary lung cancer (SMPLC), we investigated the expression of mdig through immunohistochemistry and utilized the open-access lung cancer patient databases containing genomic and transcriptomic data from the UCSC Xena and TCGA web platforms to determine the prognostic values of mdig expression status among different subtypes of lung cancer.

RESULTS

mdig is upregulated in smokers and in lung squamous cell carcinoma. High mdig expression predicted poor overall survival in lung squamous cell carcinoma and female smokers. Among tumor tissues from SMPLC patients, we not only unraveled the highest positive rate of mdig expression, but also revealed a unique cytoplasmic, rather than nuclear localization of mdig protein. Furthermore, by inspecting some pathological but not cancerous lung tissues, we believe that mdig is required for the transformation of non-cancerous lung cells to the fully-fledged cancer cells.

CONCLUSION

These data suggested that mdig is involved in various stages of lung carcinogenesis, possibly through the epigenetic regulation on some critical cancer-associated genes, and increased mdig expression is an important prognostic factor for some types of lung cancer.

Cooperation between NRF2-mediated transcription and MDIG-dependent epigenetic modifications in arsenic-induced carcinogenesis and cancer stem cells

Environmental exposure to arsenic, a well-established carcinogen linked to a number of human cancers, is a public health concern in many areas of the world. Despite extensive studies on the molecular mechanisms of arsenic-induced carcinogenesis, how initial cellular responses, such as activation of stress kinases and the generation of reactive oxygen species, converge to affect the transcriptional and/or epigenetic reprogramming required for the malignant transformation of normal cells or normal stem cells remains to be elucidated. In this review, we discuss some recent discoveries showing how the transcription factor NRF2 and an epigenetic regulator, MDIG, contribute to the arsenic-induced generation of cancer stem-like cells (CSCs) as determined by applying CRISPR-Cas9 gene editing and chromosome immunoprecipitation followed by DNA sequencing (ChIP-seq).

Mdig promotes oncogenic gene expression through antagonizing repressive histone methylation markers

The mineral dust-induced gene (mdig) is overexpressed in a number of human cancers, suggesting critical roles of this gene played on the pathogenesis of cancers. Unlike several other JmjC-domain containing proteins that exhibit histone demethylase activity, it remains enigmatic whether mdig is involved in the demethylation processes of the histone proteins. Methods: To provide direct evidence suggesting contribution of mdig to the demethylation of histone proteins, we recently examined the histone methylation profiles in human bronchial epithelial cells as well as two cancer cell lines with mdig knockout through CRISPR-Cas9 gene editing. Results: Global histone methylation analysis revealed a pronounced increase of the repressive histone trimethylation in three different cell types with mdig depletion, including trimethylation of lysines 9 and 27 on histone H3 (H3K9me3, H3K27me3) and trimethylation of lysine 20 of histone H4 (H4K20me3). Importantly, data from both ChIP-seq and RNA-seq suggested that genetic disruption of mdig enriches repressive histone trimethylation and inhibits expression of target genes in the oncogenic pathways of cell growth, stemness of the cells, tissue fibrosis, and cell motility. Conclusion: Taken together, our study provides the first insight into the molecular effects of mdig as an antagonist for repressive histone methylation markers and suggests that targeting mdig may represent a new area to explore in cancer therapy.

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.

Dynamic regulation of epigenetic demethylation by oxygen availability and cellular redox

The chromatin structure of the mammalian genome must facilitate both precisely-controlled DNA replication together with tightly-regulated gene transcription. This necessarily involves complex mechanisms and processes which remain poorly understood. It has long been recognised that the epigenetic landscape becomes established during embryonic development and acts to specify and determine cell fate. In addition, the chromatin structure is highly dynamic and allows for both cellular reprogramming and homeostatic modulation of cell function. In this respect, the functions of epigenetic "erasers", which act to remove covalently-linked epigenetic modifications from DNA and histones are critical. The enzymatic activities of the TET and JmjC protein families have been identified as demethylases which act to remove methyl groups from DNA and histones, respectively. Further, they are characterised as members of the Fe(II)- and 2-oxoglutarate-dependent dioxygenase superfamily. This provides the intriguing possibility that their enzymatic activities may be modulated by cellular metabolism, oxygen availability and redox-based mechanisms, all of which are likely to display dynamic cell- and tissue-specific patterns of flux. Here we discuss the current evidence for such [O₂]- and redox-dependent regulation of the TET and Jmjc demethylases and the potential physiological and pathophysiological functional consequences of such regulation.

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.

Loss of mdig expression enhances DNA and histone methylation and metastasis of aggressive breast cancer

We previously reported that expression of an environmentally induced gene, mineral dust-induced gene (mdig), predicts overall survival in breast cancer patients. In the present report, we further demonstrate the differential roles of mdig between earlier- and later-stage breast cancers. In noncancerous breast, mdig is a proliferation factor for cell growth and cell motility. In breast cancer, however, higher levels of mdig negatively regulate the migration and invasion of cancer cells. Assessment of global DNA methylation, chromatin accessibility and H3K9me3 heterochromatin signature suggests that silencing mdig enhances DNA and histone methylation. Through immunostaining and data mining, we found that mdig is significantly upregulated in noninvasive and/or earlier-stage breast cancers. In contrast, in triple-negative and other invasive breast cancers, diminished mdig expression was noted, indicating that the loss of mdig expression could be an important feature of aggressive breast cancers. Taken together, our data suggest that mdig is a new biomarker that likely promotes tumor growth in the early stages of breast cancer while acting as a tumor suppressor to inhibit invasion and metastasis in later-stage tumors.

Differential expression of an environmentally-induced gene appears to influence the growth of breast cancer tumors, thus providing a valuable biomarker and therapeutic target. Environmental factors can influence cancerous tumor development by interfering with epigenetic processes such as DNA and histone methylation. For example, the mineral dust induced gene (mdig) is over-expressed in coal miners who are susceptible to lung cancer. Now, Fei Chen, a pioneer in toxicology and carcinogenesis research at the Wayne State University in Detroit, USA, and his team have demonstrated that mdig also plays important roles in breast cancer. The gene is upregulated in early, non-invasive tumors, where it regulates cell growth, motility and invasion by influencing DNA and histone methylation. However, mdig expression drops in later stage or more aggressive tumor types. When the researchers abrogated mdig expression completely, they observed an enhanced DNA and histone methylation, suggesting the gene has a demethylase role and is implicated in regulating the epigenetic landscape under neoplastic conditions.

Pathological and prognostic role of mdig in pancreatic cancer

Pancreatic cancer is a highly aggressive malignant disease having very limited therapeutic options that ultimately results in its poor prognosis. It is still elusive on the etiology and tumorigenic mechanisms of pancreatic cancer. In the present report, we provide evidence showing involvement of the mineral dust-induced gene (mdig) in the pathogenesis and prognosis of the pancreatic cancer. Using immunohistochemistry approach on human pancreatic cancer tissue microarray, we found differential expression of mdig in pancreatic adenocarcinoma and normal pancreas. Based on the staining intensities of mdig in these tissue samples, we found that 12% of the cancer tissues were strongly positive for mdig, 39% and 31% were moderately and weakly positive respectively. Several alternatively spliced mdig mRNAs were detected in the selected pancreatic cancer cell lines. Through R2 platform for the patient survival analysis (http://r2.amc.nl), we found that enrichment of some specific exon of mdig predicates different survival rate of the pancreatic cancer patients. In summary, our findings may help in assessing the role of mdig in the pathogenesis of the pancreatic cancer and the prognosis of the pancreatic cancer patients.

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.

Ankyrin G expression is associated with androgen receptor stability, invasiveness, and lethal outcome in prostate cancer patients

Ankyrin G (ANK3) is a member of the Ankyrin family, which functions to provide cellular stability by anchoring the cytoskeleton to the plasma membrane. Deregulation of ANK3 expression has been observed in multiple human cancers but its mechanism remains unknown. ANK3 expression in relation to disease progression and patients' outcome was investigated in two cohorts of prostate cancer (PCA). Mechanistic studies were carried out in vitro and in vivo using several PCA cell lines and the avian embryo model. Silencing ANK3 resulted in significant reduction of cell proliferation through an AR-independent mechanism. Decreased ANK3 expression delayed S phase to G2/M cell cycle transition and reduced the expression of cyclins A and B. However, cells with knocked-down ANK3 exhibited significant increase in cell invasion through an AR-dependent mechanism. Furthermore, we found that ANK3 is a regulator of AR protein stability. ANK3 knockdown also promoted cancer cell invasion and extravasations in vivo using the avian embryo model (p < 0.01). In human samples, ANK3 expression was dramatically upregulated in high grade intraepithelial neoplasia (HGPIN) and localized PCA (p < 0.0001). However, it was downregulated castration resistant stage (p < 0.0001) and showed inverse relation to Gleason score (p < 0.0001). In addition, increased expression of ANK3 in cancer tissues was correlated with better cancer-specific survival of PCA patients (p = 0.012).

KEY MESSAGE

Silencing ANK3 results in significant reduction of cell proliferation through an AR-independent mechanism. ANK3 knockdown results in significant increase in cell invasion through an AR-dependent mechanism. ANK3 is a regulator of AR protein stability. ANK3 knockdown also promotes cancer cell invasion and extravasation in vivo using the avian embryo model.

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.

MINA controls proliferation and tumorigenesis of glioblastoma by epigenetically regulating cyclins and CDKs via H3K9me3 demethylation

It is generally known that histone demethylases regulate gene transcription by altering the methylate status on histones, but their roles in cancers and the underlying molecular mechanisms still remain unclear. MYC-induced nuclear antigen (MINA) is reported to be a histone demethylase and highly expressed in many cancers. Here, for the first time, we show that MINA is involved in glioblastoma carcinogenesis and reveal the probable mechanisms of it in cell-cycle control. Kaplan-Meier analysis of progression-free survival showed that high MINA expression was strongly correlated with poor outcome and advancing tumor stage. MINA knockdown significantly repressed the cell proliferation and tumorigenesis abilities of glioblastoma cells in vitro and in vivo that were rescued by overexpressing the full-length MINA afterwards. Microarray analysis after knockdown of MINA revealed that MINA probably regulated glioblastoma carcinogenesis through the predominant cell-cycle pathways. Further investigation showed that MINA deficiency led to a cell-cycle arrest in G1 and G2 phases. And among the downstream genes, we found that cyclins and cyclin-dependent kinases were directly activated by MINA via the demethylation of H3K9me3.

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.

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.

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.

Altered β1,6-GlcNAc branched N-glycans impair TGF-β-mediated epithelial-to-mesenchymal transition through Smad signalling pathway in human lung cancer

The change of oligosaccharide structure has been revealed to be crucial for glycoproteins' biological functions and cell biological characteristics. N-acetylglucosaminy transferase V (GnT-V), a key enzyme catalysing the reaction of adding β1, 6-N-acetylglucosamine (GlcNAc) on asparagine-linked oligosaccharides of cell proteins, has been implicated to a metastastic-promoting oncoprotein in some carcinomas. However, this correlation might not be subjected to all types of cancers, for example, in non-small cell lung cancers, low level of GnT-V expression is associated with relatively short survival time and poor prognosis. To explain the role of GnT-V in lung cancer progression, we studied the association of GnT-V expression with lung cancer EMT behaviour. We found that GnT-V expression was correlated with epithelial marker positively and mesenchymal marker negatively. GnT-V levels, as well as β1,6-GlcNAc branched N-glycans, were strongly reduced in TGF-β1-induced EMT of human lung adenocarcinoma A549 cells. Further studies showed that suppression of β1,6-GlcNAc branched N-glycans by inhibitor or GnT-V silencing in A549 cells could promote TGF-β1-induced EMT-like changes, cell migration and invasion. Meanwhile, overexpression of GnT-V impaired TGF-β1-induced EMT, migration and invasion. It suggests that GnT-V suppresses the EMT process of lung cancer cells through inhibiting the TGF-β/Smad signalling and its downstream transcription factors in a GnT-V catalytic activity–dependent manner. Taken together, the present study reveals a novel mechanism of GnT-V as a suppressor of both EMT and invasion in human lung cancer cells, which may be useful for fully understanding N-glycan's biological roles in lung cancer progression.

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.

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.