miR-34a confers chemosensitivity through modulation of MAGE-A and p53 in medulloblastoma

Altered methylation of imprinted genes in neuroblastoma: implications for prognostic refinement

BACKGROUND

Neuroblastoma (NB) is a complex disease, and the current understanding of NB biology is limited. Deregulation in genomic imprinting is a common event in malignancy. Since imprinted genes play crucial roles in early fetal growth and development, their role in NB pathogenesis could be suggested.

METHODS

We examined alterations in DNA methylation patterns of 369 NB tumours at 49 imprinted differentially methylated regions (DMRs) and assessed its association with overall survival probabilities and selected clinical and genomic features of the tumours. In addition, an integrated analysis of DNA methylation and allele-specific copy number alterations (CNAs) was performed, to understand the correlation between the two molecular events.

RESULTS

Several imprinted regions with aberrant methylation patterns in NB were identified. Regions that underwent loss of methylation in > 30% of NB samples were DMRs annotated to the genes NDN, SNRPN, IGF2, MAGEL2 and HTR5A and regions with gain of methylation were NNAT, RB1 and GPR1. Methylation alterations at six of the 49 imprinted DMRs were statistically significantly associated with reduced overall survival: MIR886, RB1, NNAT/BLCAP, MAGEL2, MKRN3 and INPP5F. RB1, NNAT/BLCAP and MKRN3 were further able to stratify low-risk NB tumours i.e. tumours that lacked MYCN amplification and 11q deletion into risk groups. Methylation alterations at NNAT/BLCAP, MAGEL2 and MIR886 predicted risk independently of MYCN amplification or 11q deletion and age at diagnosis. Investigation of the allele-specific CNAs demonstrated that the imprinted regions that displayed most alterations in NB tumours harbor true epigenetic changes and are not result of the underlying CNAs.

CONCLUSIONS

Aberrant methylation in imprinted regions is frequently occurring in NB tumours and several of these regions have independent prognostic value. Thus, these could serve as potentially important clinical epigenetic markers to identify individuals with adverse prognosis. Incorporation of methylation status of these regions together with the established risk predictors may further refine the prognostication of NB patients.

An Immunohistochemical Study of MAGE Proteins in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one the most common primary malignancies with high mortality and morbidity. The melanoma-associated antigen (MAGE) gene family includes several genes that are highly expressed in numerous human cancers, making many of them part of the cancer-testis antigen (CTA) family. MAGE-C1 is expressed in various malignancies but is absent in normal cells, except for the male germ line. Its presence is associated with a worse prognosis, increased tumor aggressiveness, and lymph node invasion. Similarly, MAGE-C2 is linked to the development of various malignant tumors. Despite these associations, the roles and mechanisms of MAGE-C1/MAGE-C2 in HCC remain unclear. This study aimed to evaluate the expression of MAGE-C1 and MAGE-C2 in HCC and correlate it with clinicohistological characteristics. Our findings indicated that MAGE-C1 expression is associated with a higher number of nodules, elevated AFP levels, HBV or HCV positivity, older age, male sex, and lymph node invasion. MAGE-C2 expression was correlated with these characteristics and the presence of cirrhosis. These results align with the limited literature, which suggests a correlation between MAGE expression and older age and HBV infection. Consequently, our study suggests that MAGE-C1 and MAGE-C2 are promising novel biomarkers for prognosis and potential therapeutic targets in HCC.

MAGE-A10 Protein Expression in Advanced High Grade Serous Ovarian Cancer Is Associated with Resistance to First-Line Platinum-Based Chemotherapy

Ovarian cancer has a dismal prognosis. Standard treatment following surgery relies on platinum-based chemotherapy. However, sizeable percentages of patients are unresponsive. Identification of markers predicting the response to chemotherapy might help select eligible patients and spare non-responding patients from treatment-associated toxicity. Cancer/testis antigens (CTAs) are expressed by healthy germ cells and malignant cells of diverse histological origin. This expression profile identifies them as attractive targets for cancer immunotherapies. We analyzed the correlations between expression of MAGE-A10 and New York esophageal-1 cancer (NY-ESO-1) CTAs at the protein level and the effectiveness of platinum-based chemotherapy in patients with advanced-stage high-grade serous ovarian carcinoma (HGSOC). MAGE-A10 and NY-ESO-1 protein expression was analyzed by immunohistochemistry (IHC) in formalin-fixed, paraffin-embedded samples from 93 patients with advanced-stage HGSOC treated at our institutions between January 1996 and December 2013. The correlation between the expression of these markers and response to platinum-based chemotherapy, evaluated according to RECIST 1.1 criteria and platinum sensitivity, measured as platinum-free interval (PFI), progression free (PFS), and overall survival (OS) was explored. The MAGE-A10 protein expression predicted unresponsiveness to platinum-based chemotherapy (p = 0.005), poor platinum sensitivity (p < 0.001), poor PFS (p < 0.001), and OS (p < 0.001). Multivariate analysis identified MAGE-A10 protein expression as an independent predictor of poor platinum sensitivity (p = 0.005) and shorter OS (p < 0.001). Instead, no correlation was observed between the NY-ESO-1 protein expression and response to platinum-based chemotherapy (p = 0.832), platinum sensitivity (p = 0.168), PFS (p = 0.126), and OS (p = 0.335). The MAGE-A10 protein expression reliably identified advanced-stage HGSOC unresponsive to platinum-based chemotherapy. Targeted immunotherapy could represent an important alternative therapeutic option in these cancers.

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Deciphering the role of MitomiRs in cancer: A comprehensive review

MicroRNAs (miRNAs) are short non-coding RNAs that regulate many metabolic and signal transduction pathways. The role of miRNAs, usually found in the cytoplasm, in regulating gene expression and cancer progression has been extensively studied in the last few decades. However, very recently, miRNAs were found to localize in the mitochondria. MiRNAs that specifically localize in the mitochondria and the cytoplasmic miRNAs associated with mitochondria that directly or indirectly modulate specific mitochondrial functions are termed as "mitomiRs". Although it is not clear about the origin of mitomiRs that are situated within mitochondria (nuclear or mitochondrial origin), it is evident that they have specific functions in modulating gene expression and regulating important mitochondrial metabolic pathways. Through this review, we aim to delineate the mechanisms by which mitomiRs alter mitochondrial metabolic pathways and influence the initiation and progression of cancer. We further discuss the functions of particular mitomiRs, which have been widely studied in the context of mitochondrial metabolism and oncogenic signaling pathways. Based on the current knowledge, we can conclude that mitomiRs contribute significantly to mitochondrial function and metabolic regulation, and that dysregulation of mitomiRs can aid the proliferation of cancer cells. Therefore, the less explored area of mitomiRs' biology can be an important topic of research investigation in the future for targeting cancer cells.

MAGE-I proteins and cancer-pathways: A bidirectional relationship

Data emerged from the last 20 years of basic research on tumor antigens positioned the type I MAGE (Melanoma Antigen GEnes - I or MAGE-I) family as cancer driver factors. MAGE-I gene expression is mainly restricted to normal reproductive tissues. However, abnormal re-expression in cancer unbalances the cell status towards enhanced oncogenic activity or reduced tumor suppression. Anomalous MAGE-I gene re-expression in cancer is attributed to altered epigenetic-mediated chromatin silencing. Still, emerging data indicate that MAGE-I can be regulated at protein level. Results from different laboratories suggest that after its anomalous re-expression, specific MAGE-I proteins can be regulated by well-known signaling pathways or key cellular processes that finally potentiate the cancer cell phenotype. Thus, MAGE-I proteins both regulate and are regulated by cancer-related pathways. Here, we present an updated review highlighting the recent findings on the regulation of MAGE-I by oncogenic pathways and the potential consequences in the tumor cell behavior.

Effects of microRNAs and long non-coding RNAs on chemotherapy response in glioma

Glioma is the most prevalent invasive primary tumor of the central nervous system. Glioma cells can spread and infiltrate into normal surrounding brain tissues. Despite the standard use of chemotherapy and radiotherapy after surgery in glioma patients, treatment resistance is still a problem, as the underlying mechanisms are still not fully understood. Non-coding RNAs are widely involved in tumor progression and treatment resistance mechanisms. In the present review, we discuss the pathways by which microRNAs and long non-coding RNAs can affect resistance to chemotherapy and radiotherapy, as well as offer potential therapeutic options for future glioma treatment.

Epigenetic mechanisms in paediatric brain tumours: regulators lose control

Epigenetic mechanisms are essential to regulate gene expression during normal development. However, they are often disrupted in pathological conditions including tumours, where they contribute to their formation and maintenance through altered gene expression. In recent years, next generation genomic techniques has allowed a remarkable advancement of our knowledge of the genetic and molecular landscape of paediatric brain tumours and have highlighted epigenetic deregulation as a common hallmark in their pathogenesis. This review describes the main epigenetic dysregulations found in paediatric brain tumours, including at DNA methylation and histone modifications level, in the activity of chromatin-modifying enzymes and in the expression of non-coding RNAs. How these altered processes influence tumour biology and how they can be leveraged to dissect the molecular heterogeneity of these tumours and contribute to their classification is also addressed. Finally, the availability and value of preclinical models as well as the current clinical trials exploring targeting key epigenetic mediators in paediatric brain tumours are discussed.

Role of MicroRNAs in the Development and Progression of the Four Medulloblastoma Subgroups

Medulloblastoma is the most frequent malignant brain tumour in children. Medulloblastoma originate during the embryonic stage. They are located in the cerebellum, which is the area of the central nervous system (CNS) responsible for controlling equilibrium and coordination of movements. In 2012, medulloblastoma were divided into four subgroups based on a genome-wide analysis of RNA expression. These subgroups are named Wingless, Sonic Hedgehog, Group 3 and Group 4. Each subgroup has a different cell of origin, prognosis, and response to therapies. Wingless and Sonic Hedgehog medulloblastoma are so named based on the main mutation originating these tumours. Group 3 and Group 4 have generic names because we do not know the key mutation driving these tumours. Gene expression at the post-transcriptional level is regulated by a group of small single-stranded non-coding RNAs. These microRNA (miRNAs or miRs) play a central role in several cellular functions such as cell differentiation and, therefore, any malfunction in this regulatory system leads to a variety of disorders such as cancer. The role of miRNAs in medulloblastoma is still a topic of intense clinical research; previous studies have mostly concentrated on the clinical entity of the single disease rather than in the four molecular subgroups. In this review, we summarize the latest discoveries on miRNAs in the four medulloblastoma subgroups.

Noncoding RNAs in pediatric brain tumors: Molecular functions and pathological implications

Brain tumors are common solid pediatric malignancies and the main reason for cancer-related death in the pediatric setting. Recently, evidence has revealed that noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), play a critical role in brain tumor development and progression. Therefore, in this review article, we describe the functions and molecular mechanisms of ncRNAs in multiple types of cancer, including medulloblastoma, pilocytic astrocytoma, ependymoma, atypical teratoid/rhabdoid tumor, glioblastoma, diffuse intrinsic pontine glioma, and craniopharyngioma. We also mention the limitations of using ncRNAs as therapeutic targets because of the nonspecificity of ncRNA targets and the delivery methods of ncRNAs. Due to the critical role of ncRNAs in brain oncogenesis, targeting aberrantly expressed ncRNAs might be an effective strategy to improve the outcomes of pediatric patients with brain tumors.

The Role of MicroRNAs in Therapeutic Resistance of Malignant Primary Brain Tumors

Brain tumors in children and adults are challenging tumors to treat. Malignant primary brain tumors (MPBTs) such as glioblastoma have very poor outcomes, emphasizing the need to better understand their pathogenesis. Developing novel strategies to slow down or even stop the growth of brain tumors remains one of the major clinical challenges. Modern treatment strategies for MPBTs are based on open surgery, chemotherapy, and radiation therapy. However, none of these treatments, alone or in combination, are considered effective in controlling tumor progression. MicroRNAs (miRNAs) are 18-22 nucleotide long endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level by interacting with 3'-untranslated regions (3'-UTR) of mRNA-targets. It has been proven that miRNAs play a significant role in various biological processes, including the cell cycle, apoptosis, proliferation, differentiation, etc. Over the last decade, there has been an emergence of a large number of studies devoted to the role of miRNAs in the oncogenesis of brain tumors and the development of resistance to radio- and chemotherapy. Wherein, among the variety of molecules secreted by tumor cells into the external environment, extracellular vesicles (EVs) (exosomes and microvesicles) play a special role. Various elements were found in the EVs, including miRNAs, which can be transported as part of these EVs both between neighboring cells and between remotely located cells of different tissues using biological fluids. Some of these miRNAs in EVs can contribute to the development of resistance to radio- and chemotherapy in MPBTs, including multidrug resistance (MDR). This comprehensive review examines the role of miRNAs in the resistance of MPBTs (e.g., high-grade meningiomas, medulloblastoma (MB), pituitary adenomas (PAs) with aggressive behavior, and glioblastoma) to chemoradiotherapy and pharmacological treatment. It is believed that miRNAs are future therapeutic targets in MPBTs and such the role of miRNAs needs to be critically evaluated to focus on solving the problems of resistance to therapy this kind of human tumors.

Epigenetic-Based Therapy-A Prospective Chance for Medulloblastoma Patients' Recovery

Medulloblastoma (MB) is one of the most frequent and malignant brain tumors in children. The prognosis depends on the advancement of the disease and the patient's age. Current therapies, which include surgery, chemotherapy, and irradiation, despite being quite effective, cause significant side effects that influence the central nervous system's function and cause neurocognitive deficits. Therefore, they substantially lower the quality of life, which is especially severe in a developing organism. Thus, there is a need for new therapies that are less toxic and even more effective. Recently, knowledge about the epigenetic mechanisms that are responsible for medulloblastoma development has increased. Epigenetics is a phenomenon that influences gene expression but can be easily modified by external factors. The best known epigenetic mechanisms are histone modifications, DNA methylation, or noncoding RNAs actions. Epigenetic mechanisms comprehensively explain the complex phenomena of carcinogenesis. At the same time, they seem to be a potential key to treating medulloblastoma with fewer complications than past therapies. This review presents the currently known epigenetic mechanisms that are involved in medulloblastoma pathogenesis and the potential therapies that use epigenetic traits to cure medulloblastoma while maintaining a good quality of life and ensuring a higher median overall survival rate.

miRNAs Modulate the Dichotomy of Cisplatin Resistance or Sensitivity in Breast Cancer: An Update of Therapeutic Implications

Cisplatin has a broad-spectrum antitumor activity and is widely used for the treatment of various malignant tumors. However, acquired or intrinsic resistance of cisplatin is a major problem for patients during the therapy. Recently, it has been reported Cancer Stem Cell (CSC)-derived drug resistance is a great challenge of tumor development and recurrence; therefore, the sensitivity of Breast Cancer Stem Cells (BCSCs) to cisplatin is of particular importance. Increasing evidence has shown that there is a relationship between cisplatin resistance/sensitivity genes and related miRNAs. It is known that dysregulation of relevant miRNAs plays a critical role in regulating target genes of cisplatin resistance/sensitivity in various pathways such as cellular uptake/efflux, Epithelial-Mesenchymal Transition (EMT), hypoxia, and apoptosis. Furthermore, the efficacy of the current chemotherapeutic drugs, including cisplatin, for providing personalized medicine, can be improved by controlling the expression of miRNAs. Thus, potential targeting of miRNAs can lead to miRNA-based therapies, which will help overcome drug resistance and develop more effective personalized anti-cancer and cotreatment strategies in breast cancer. In this review, we summarized the general understandings of miRNAregulated biological processes in breast cancer, particularly focused on the role of miRNA in cisplatin resistance/ sensitivity.

The comprehensive landscape of miR-34a in cancer research

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

An appraisal on molecular and biochemical signalling cascades during arsenic-induced hepatotoxicity

Arsenic is a ubiquitous metalloid compound commonly found in the environment, and it is usually found in combination with sulphur and metals. Arsenic is considered as a therapeutic as well as poisoning agent since ancient times. It causes toxic effects on different organs, mainly the liver. In this review, we focused on the molecular mechanism of arsenic-induced hepatotoxicity. Here we envisaged the bridge between arsenic and hepatotoxicity with particular focus on the level of hepatic enzymes such as ALT, AST, and ALP. Here, we attempted to elucidate the role of arsenic in redox imbalance on increased oxidative stress (elevated level of ROS, MDA and NO) and decreased antioxidant levels such as reduced GSH, catalase, and SOD. Oxidative stress induces mitochondrial dysfunction via apoptosis (AKT-PKB, MAPK, PI3/AKT, PKCδ-JNK, AKT/ERK, p53 pathways), fibrosis (TGF-β/Smad pathway), and necrosis and inflammation (TNF-α, NF-ĸB, IL-1, and IL-6). Along with that, arsenic activates caspases and Bax, decreases Bcl2 through mitochondrial dysfunction, and induces apoptosis regulatory mechanism. We believe the alteration of all these pathways leads to arsenic-induced hepatotoxicity.

A comprehensive analysis of the MAGE family as prognostic and diagnostic markers for hepatocellular carcinoma

The Melanoma Antigen Gene (MAGE) family is a large, highly conserved group of proteins which was reported to participate in the progression of multiple cancers in humans. However, the function of distinct MAGE genes in hepatocellular carcinoma (HCC) is largely unclear. In this study, we comprehensively evaluated the expression, clinical significance, genetic alteration, interaction network and functional enrichment of MAGEs in HCC. Our research showed that many MAGE genes were dysregulated in HCC. Among them, MAGEA1, MAGEC2, MAGED1, MAGED2, MAGEF1 and MAGEL2 were significantly associated with clinical stage and differentiation of HCC. MAGED1, MAGED2, MAGEA6, MAGEA12, MAGEA10, MAGEB4, MAGEL2 and MAGEC3 significantly correlated with HCC prognosis. Further functional enrichment analysis suggested the dysregulated MAGEs may play important roles in signal transduction. These results indicate that multiple dysregulated MAGEs might play important roles in the development of HCC and can be exploited as useful biomarkers for diagnosis and treatment in HCC.

Genetic and Epigenetic Modulation of Drug Resistance in Cancer: Challenges and Opportunities

Cancer is a complex disease that has the ability to develop resistance to traditional therapies. The current chemotherapeutic treatment has become increasingly sophisticated, yet it is not 100% effective against disseminated tumours. Anticancer drugs resistance is an intricate process that ascends from modifications in the drug targets suggesting the need for better targeted therapies in the therapeutic arsenal. Advances in the modern techniques such as DNA microarray, proteomics along with the development of newer targeted drug therapies might provide better strategies to overcome drug resistance. This drug resistance in tumours can be attributed to an individual's genetic differences, especially in tumoral somatic cells but acquired drug resistance is due to different mechanisms, such as cell death inhibition (apoptosis suppression) altered expression of drug transporters, alteration in drug metabolism epigenetic and drug targets, enhancing DNA repair and gene amplification. This review also focusses on the epigenetic modifications and microRNAs, which induce drug resistance and contributes to the formation of tumour progenitor cells that are not destroyed by conventional cancer therapies. Lastly, this review highlights different means to prevent the formation of drug resistant tumours and provides future directions for better treatment of these resistant tumours.

Aberrantly expressed microRNAs and their implications in childhood central nervous system tumors

Even though the treatment of childhood cancer has evolved significantly in recent decades, aggressive central nervous system (CNS) tumors are still a leading cause of morbidity and mortality in this population. Consequently, the identification of molecular targets that can be incorporated into diagnostic practice, effectively predict prognosis, follow treatment response, and materialize into potential targeted therapeutic approaches are still warranted. Since the first evidence of the participation of miRNAs in cancer development and progression 20 years ago, notable progress has been made in the basic understanding of the contribution of their dysregulation as epigenetic driver of tumorigenesis. Nevertheless, among the plethora of articles in the literature, microRNA profiling of pediatric tumors are scarce. This article gives an overview of the recent advances in the diagnostic/prognostic potential of miRNAs in a selection of pediatric CNS tumors: medulloblastoma, ependymoma, pilocytic astrocytoma, glioblastoma, diffuse intrinsic pontine glioma, atypical teratoid/rhabdoid tumors, and choroid plexus tumors.

The role of miR-34 in cancer drug resistance

Resistance to conventional chemotherapy remains a major cause of cancer relapse and cancer-related deaths. Therefore, there is an urgent need to overcome resistance barriers. To improve cancer treatment approaches, it is critical to elucidate the basic mechanisms underlying drug resistance. Increasingly, the mechanisms involving micro-RNAs (miRNAs) are studied because miRNAs are also considered practical therapeutic options due to high degrees of specificity, efficacy, and accuracy, as well as their ability to target multiple genes at the same time. Years of research have firmly established miR-34 as a key tumor suppressor miRNA whose target genes are involved in drug resistance mechanisms. Indeed, numerous articles show that low levels of circulating miR-34 or tumor-specific miR-34 expression are associated with poor response to chemotherapy. In addition, elevation of inherently low miR-34 levels in resistant cancer cells effectively restores sensitivity to chemotherapeutic agents. Here, we review this literature, also highlighting some contradictory observations. In addition, we discuss the potential utility of miR-34 expression as a predictive biomarker for chemotherapeutic drug response. Although caution needs to be exercised, miR-34 is emerging as a biomarker that could improve cancer precision medicine.

miR-128-3p contributes to mitochondrial dysfunction and induces apoptosis in glioma cells via targeting pyruvate dehydrogenase kinase 1

Glioma, like most cancers, possesses a unique bioenergetic state of aerobic glycolysis known as the Warburg effect, which is a dominant phenotype of most tumor cells. Glioma tumors exhibit high glycolytic metabolism with increased lactate production. Data derived from the gene expression profiling interactive analysis (GEPIA) database show that pyruvate dehydrogenase kinase 1 (PDK1) is significantly highly expressed in glioma tissues compared with corresponding normal tissues. PDK1 is a key enzyme in the transition of glycolysis to tricarboxylic acid cycle, via inactivating PDH and converting oxidative phosphorylation to Warburg effect, resulting in increment of lactate production. Silencing of PDK1 expression resulted in reduced lactate and ATP, accumulation of ROS, mitochondrial damage, decreased cell growth, and increased cell apoptosis. Aberrant expression of miR-128 has been observed in many human malignancies. Mechanistically, we discover that overexpressed miR-128-3p disturbs the Warburg effect in glioma cells via reducing PDK1. Our experiments confirmed that the miR-128-3p/PDK1 axis played a pivotal role in cancer cell metabolism and growth. Collectively, these findings suggest that therapeutic strategies to modulate the Warburg effect, such as targeting of PDK1, might act as a potential therapeutic target for glioma treatment.

The therapeutic and diagnostic potential of regulatory noncoding RNAs in medulloblastoma

Medulloblastoma, a central nervous system tumor that predominantly affects children, always requires aggressive therapy. Nevertheless, it frequently recurs as resistant disease and is associated with high morbidity and mortality. While recent efforts to subclassify medulloblastoma based on molecular features have advanced our basic understanding of medulloblastoma pathogenesis, optimal targets to increase therapeutic efficacy and reduce side effects remain largely undefined. Noncoding RNAs (ncRNAs) with known regulatory roles, particularly long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), are now known to participate in medulloblastoma biology, although their functional significance remains obscure in many cases. Here we review the literature on regulatory ncRNAs in medulloblastoma. In providing a comprehensive overview of ncRNA studies, we highlight how different lncRNAs and miRNAs have oncogenic or tumor suppressive roles in medulloblastoma. These ncRNAs possess subgroup specificity that can be exploited to personalize therapy by acting as theranostic targets. Several of the already identified ncRNAs appear specific to medulloblastoma stem cells, the most difficult-to-treat component of the tumor that drives metastasis and acquired resistance, thereby providing opportunities for therapy in relapsing, disseminating, and therapy-resistant disease. Delivering ncRNAs to tumors remains challenging, but this limitation is gradually being overcome through the use of advanced technologies such as nanotechnology and rational biomaterial design.

Functional and mechanistic studies reveal MAGEA3 as a pro-survival factor in pancreatic cancer cells

Background

In the era of personalized therapy, functional annotation of less frequent genetic aberrations will be instrumental in adapting effective therapeutic in clinic. Overexpression of Melanoma associated antigen A3 (MAGEA3) is reported in certain pancreatic cancer (PCA) patients. The major objective of the current study was to investigate the functional role of MAGEA3 in pancreatic cancer cells (PCCs) growth and survival.

Methods

Using overexpression (tet-on regulated system and constitutive expression system) and knockdown (by siRNA and shRNA) approach, we dissected the mechanistic role of MAGEA3 in pancreatic cancer pathogenesis. We generated MAGEA3 expressing stable PCA cell lines and mouse primary pancreatic epithelial cells. MAGEA3 was also depleted in certain MAGEA3 positive PCCs by siRNA or shRNA. The stable cells were subjected to in vitro assays like proliferation and survival assays under growth factor deprivation or in the presence of cytotoxic drugs. The MAGEA3 overexpressing or depleted stable PCCs were evaluated in vivo using xenograft model to check the role of MAGEA3 in tumor progression. We also dissected the mechanism behind the MAGEA3 role in tumor progression using western blot analysis and CCL2 neutralization.

Results

MAGEA3 overexpression in PCA cells did not alter the cell proliferation but protected the cells during growth factor deprivation and also in the presence of cytotoxic drugs. However, depletion of MAGEA3 in MAGEA3 positive cells resulted in reduced cell proliferation and increased apoptosis upon growth factor deprivation and also in response to cytotoxic drugs. The in vivo xenograft study revealed that overexpression of MAGEA3 promoted tumor growth however depleting the same hindered the tumor progression. Mechanistically, our in vitro and in vivo study revealed that MAGEA3 has tumor-promoting role by reducing macro-autophagy and overexpressing pro-survival molecules like CCL2 and survivin.

Conclusion

Our data proves tumor-promoting role of MAGEA3 and provides the rationale to target MAGEA3 and/or its functional mediators like CCL2 for PCA, which may have a better impact in PCA therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1272-2) contains supplementary material, which is available to authorized users.

Alkylating anticancer agents and their relations to microRNAs

Alkylating agents represent an important class of anticancer drugs. The occurrence and emergence of tumor resistance to the treatment with alkylating agents denotes a severe problem in the clinics. A detailed understanding of the mechanisms of activity of alkylating drugs is essential in order to overcome drug resistance. In particular, the role of non-coding microRNAs concerning alkylating drug activity and resistance in various cancers is highlighted in this review. Both synthetic and natural alkylating agents, which are approved for cancer therapy, are discussed concerning their interplay with microRNAs.

Polymeric Co-Delivery Systems in Cancer Treatment: An Overview on Component Drugs' Dosage Ratio Effect

Multiple factors are involved in the development of cancers and their effects on survival rate. Many are related to chemo-resistance of tumor cells. Thus, treatment with a single therapeutic agent is often inadequate for successful cancer therapy. Ideally, combination therapy inhibits tumor growth through multiple pathways by enhancing the performance of each individual therapy, often resulting in a synergistic effect. Polymeric nanoparticles prepared from block co-polymers have been a popular platform for co-delivery of combinations of drugs associated with the multiple functional compartments within such nanoparticles. Various polymeric nanoparticles have been applied to achieve enhanced therapeutic efficacy in cancer therapy. However, reported drug ratios used in such systems often vary widely. Thus, the same combination of drugs may result in very different therapeutic outcomes. In this review, we investigated polymeric co-delivery systems used in cancer treatment and the drug combinations used in these systems for synergistic anti-cancer effect. Development of polymeric co-delivery systems for a maximized therapeutic effect requires a deeper understanding of the optimal ratio among therapeutic agents and the natural heterogenicity of tumors.

miR miR on the wall, who's the most malignant medulloblastoma miR of them all?

microRNAs (miRNAs) have wide-ranging effects on large-scale gene regulation. As such, they play a vital role in dictating normal development, and their aberrant expression has been implicated in cancer. There has been a large body of research on the role of miRNAs in medulloblastoma, the most common malignant brain tumor of childhood. The identification of the 4 molecular subgroups with distinct biological, genetic, and transcriptional features has revolutionized the field of medulloblastoma research over the past 5 years. Despite this, the growing body of research on miRNAs in medulloblastoma has largely focused on the clinical entity of a single disease rather than the molecular subgroups. This review begins by highlighting the role of miRNAs in development and progresses to explore their myriad of implications in cancer. Medulloblastoma is characterized by increased proliferation, inhibition of apoptosis, and maintenance of stemness programs-features that are inadvertently regulated by altered expression patterns in miRNAs. This review aims to contextualize the large body of work on miRNAs within the framework of medulloblastoma subgroups. The goal of this review is to stimulate new areas of research, including potential therapeutics, within a rapidly growing field.

miR‑34a regulates the chemosensitivity of retinoblastoma cells via modulation of MAGE‑A/p53 signaling

The present study aimed to explore the combined role of microRNA (miR)-34a, melanoma antigen-A (MAGE‑A) and p53 in altering the chemosensitivity of retinoblastoma (RB) cells. Human RB and adjacent tumor tissues, as well as human RB cell lines (HXO‑Rb44, SO‑Rb50, Y79 and WERI‑Rb-1) were used. In addition, four chemotherapeutic drugs, including carboplatin, etoposide, Adriamycin and vincristine, were used to treat the cell lines, in order to evaluate the sensitivity of RB cells. Furthermore, miR‑34a expression was detected by reverse transcription-quantitative polymerase chain reaction, and western blotting was implemented to quantify expression levels of MAGE‑A and p53. A luciferase reporter gene assay was used to validate the targeted association between miR‑34a and MAGE‑A. The results indicated that SO‑Rb50 cells exhibited the highest resistance to carboplatin, Adriamycin and vincristine (P<0.05), whereas HXO‑Rb44 cells revealed the highest inhibition rate in response to etoposide (P<0.05) out of the four cell lines. Furthermore, reduced miR‑34a expression and increased MAGE‑A expression significantly elevated the survival rate and viability of SO‑Rb50 cells following drug treatment (all P<0.05). miR‑34a was also demonstrated to directly target MAGE‑A, thereby significantly promoting the viability of RB cells and depressing apoptosis (P<0.05). p53, which was subjected to modulation by miR‑34a and MAGE‑A, also significantly reduced the proliferation rate of RB cells (P<0.05). In conclusion, the miR‑34a/MAGE‑A/p53 axis may be conducive to enhancing the efficacies of chemotherapeutic treatments for RB.

Tumor suppressive miR-6775-3p inhibits ESCC progression through forming a positive feedback loop with p53 via MAGE-A family proteins

Accumulating evidences indicate that microRNAs (miRNAs) play vital roles in multiple diseases, including cancer. In the present study, we showed that miR-6775-3p plays a tumor suppressive role in esophageal squamous cell carcinoma (ESCC). High expression miR-6775-3p is associated with good clinical outcomes of ESCC patients. Over-expression of miR-6775-3p inhibited tumor growth and liver metastasis of ESCC xenograft tumors. Enforced expression of miR-6775-3p inhibited ESCC cell proliferation, migration, and invasion. KEGG pathway analysis revealed that miR-6775-3p was associated with the genes on “pathway in cancer”. Mechanically, miR-6775-3p inhibited the expression of tumor antigens MAGE-A family through direct binding the 3′UTR region of MAGE-A mRNAs, and attenuated MAGE-A-inhibited transcriptional activity of tumor suppressor p53. In addition, miR-6775-3p also directly inhibits its host gene SLC7A5 which has been reported to play oncogenic roles in cancer progression. Interestingly, miR-6775-3p and its host gene SLC7A5 were directly transcriptionally induced by p53. Thus, for the first time, our study proposed a novel positive feedback regulation between miR-6775-3p and p53 via MAGE-A family, which plays crucial role in ESCC progression.

Epigenetic regulation of MAGE family in human cancer progression-DNA methylation, histone modification, and non-coding RNAs

The melanoma antigen gene (MAGE) proteins are a group of highly conserved family members that contain a common MAGE homology domain. Type I MAGEs are relevant cancer-testis antigens (CTAs), and originally considered as attractive targets for cancer immunotherapy due to their typically high expression in tumor tissues but restricted expression in normal adult tissues. Here, we reviewed the recent discoveries and ideas that illustrate the biological functions of MAGE family in cancer progression. Furthermore, we also highlighted the current understanding of the epigenetic mechanism of MAGE family expression in human cancers.

A Self-Training Subspace Clustering Algorithm under Low-Rank Representation for Cancer Classification on Gene Expression Data

Accurate identification of the cancer types is essential to cancer diagnoses and treatments. Since cancer tissue and normal tissue have different gene expression, gene expression data can be used as an efficient feature source for cancer classification. However, accurate cancer classification directly using original gene expression profiles remains challenging due to the intrinsic high-dimension feature and the small size of the data samples. We proposed a new self-training subspace clustering algorithm under low-rank representation, called SSC-LRR, for cancer classification on gene expression data. Low-rank representation (LRR) is first applied to extract discriminative features from the high-dimensional gene expression data; the self-training subspace clustering (SSC) method is then used to generate the cancer classification predictions. The SSC-LRR was tested on two separate benchmark datasets in control with four state-of-the-art classification methods. It generated cancer classification predictions with an overall accuracy 89.7 percent and a general correlation 0.920, which are 18.9 and 24.4 percent higher than that of the best control method respectively. In addition, several genes (RNF114, HLA-DRB5, USP9Y, and PTPN20) were identified by SSC-LRR as new cancer identifiers that deserve further clinical investigation. Overall, the study demonstrated a new sensitive avenue to recognize cancer classifications from large-scale gene expression data.

BAI1 Suppresses Medulloblastoma Formation by Protecting p53 from Mdm2-Mediated Degradation

Adhesion G protein-coupled receptors (ADGRs) encompass 33 human transmembrane proteins with long N termini involved in cell-cell and cell-matrix interactions. We show the ADGRB1 gene, which encodes Brain-specific angiogenesis inhibitor 1 (BAI1), is epigenetically silenced in medulloblastomas (MBs) through a methyl-CpG binding protein MBD2-dependent mechanism. Knockout of Adgrb1 in mice augments proliferation of cerebellar granule neuron precursors, and leads to accelerated tumor growth in the Ptch1+/- transgenic MB mouse model. BAI1 prevents Mdm2-mediated p53 polyubiquitination, and its loss substantially reduces p53 levels. Reactivation of BAI1/p53 signaling axis by a brain-permeable MBD2 pathway inhibitor suppresses MB growth in vivo. Altogether, our data define BAI1's physiological role in tumorigenesis and directly couple an ADGR to cancer formation.

hMAGEA2 promotes progression of breast cancer by regulating Akt and Erk1/2 pathways

Breast cancer is the most abundant cancer worldwide and a severe problem for women. Notably, breast cancer has a high mortality rate, mainly because of tumor progression and metastasis. Triple-negative breast cancer (TNBC) is highly progressive and lacks the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Therefore, there are no established therapeutic targets against TNBC. In this study, we investigated whether the expression of human melanoma-associated antigen A2 (MAGEA2) is associated with TNBC. We found that hMAGEA2 is significantly overexpressed in human TNBC tissues; we also observed oncogenic properties using TNBC cell lines (MDA-MB-231 and MDA-MB-468). The overexpression of hMAGEA2 in MDA-MB-231 cell line showed dramatically increased cellular proliferation, colony formation, invasion, and xenograft tumor formation and growth. Conversely, knockdown of hMAEGA2 in MDA-MB-468 cell line suppressed cellular proliferation, colony formation, and xenograft tumor formation. Additionally, we showed that hMAGEA2 regulated the activation of Akt and Erk1/2 signaling pathways. These data indicate that hMAGEA2 is important for progression of TNBC and may serve as a novel molecular therapeutic target.

MicroRNA-34a induces transdifferentiation of glioma stem cells into vascular endothelial cells by targeting Notch pathway

The function of microRNA-34a (miR-34a) in transdifferentiation of glioma stem cells (GSCs) into vascular endothelial cells (VECs) was explored by focusing on Notch ligand Delta-like 1 (Dll1). MiR-34a mimics was transfected into CD133 + glioma cell U251. The angiogenesis feature of miR-34a transfected U251 cells was investigated and the expressions of CD31, CD34, Vwf, Notch 1, and Dll1 were quantified. Length of branching vessel-like structures in the miR-34a transfected U251 cells was significantly higher than control cells. The VEC feature of miR-34a overexpressed U251 cells was further confirmed by the expressions of CD31, CD34, and vWF. Transfection of miR-34a decreased the expression of Notch 1 and Dll1. Furthermore, the miR-34a overexpression-enhanced tube formation of GSCs was suppressed when the decreased expression of Dll1 was restored. The current study highlighted the potential of miR-34a as an inducer in GSCs' transdifferentiation into VECs by targeting Dll1.

miRNA Regulation in Gliomas: Usual Suspects in Glial Tumorigenesis and Evolving Clinical Applications

In recent years, an increasing role for noncoding small RNAs (miRNA) has been uncovered in carcinogenesis. These oligonucleotides can promote degradation and/or inhibit translation of key mRNAs. Recent studies have also highlighted a possible role for miRNAs in adult and pediatric brain tumors, including high- and low-grade gliomas, medulloblastoma, ependymoma, and neoplasms associated with neurofibromatosis type 1. Gliomas represent the most common category of primary intraparenchymal brain tumors, and, for example, manipulation of signaling pathways, through inhibition of PTEN transcription appears to be an important function of miRNA dysregulation through miR-21, miR-106b, and miR-26a. Moreover, altered miRNA expression in gliomas play roles in the regulation of common tumorigenic processes, including receptor tyrosine kinase signaling, angiogenesis, invasion, suppression of differentiation, cell cycle enhancement, and inhibition of apoptosis. Suppression of differentiation requires the downregulation of a number of miRNAs that are both enriched in the brain and required for terminal glial differentiation, including miR-219 and miR-338. Our evolving understanding about the biology of gliomas make them attractive for miRNA study, given that recent evidence suggests that epigenetic and subtle genetic changes may contribute to their pathogenesis. Identification of key miRNAs also provides a rationale for developing robust biomarkers and inhibitory RNA strategies for therapeutic purposes in glioma patients.

Biomarkers in hepatocellular carcinoma: an overview

Current methods for HCC diagnosis have not an optimal diagnostic accuracy. The detection of more than one biomarker seems to improve their individual performance and provide an accurate HCC diagnosis approach. Individual gene expression seems to influence whether or not the treatment is successful, since several molecules have interfere with cancer associated pathways and have been related to poor prognosis which condition the lack of effective treatment options. Areas covered: Novel biomarkers have been proposed as a useful tool in each patient prognosis. This article aims to review the recent evidence based on HCC biomarkers which seems to have a regulative role according to tumor cell development leading to a specific biological response. Epigenetic regulation, miRNAs, and genome sequencing analysis propose molecular expression signatures as novel biomarkers which allowed achieve the major goal for the use of biomarkers in clinical practice. Moreover, a deeper analysis for determine the diagnostic accuracy of biomarkers has been made. Expert commentary: To improve of methodological designs and sample sizes are needed in order to support the role of biomarkers in HCC. Furthermore, is necessary to consider HCC etiologies and all clinic disease context to carried out clinical phase studies to thrust biomarkers application.

Interactions between anticancer active platinum complexes and non-coding RNAs/microRNAs

Platinum(II) complexes such as cisplatin, carboplatin and oxaliplatin are clinically approved for the therapy of various solid tumors. Challenging pathogenic properties of cancer cells and the response of cancers towards platinum-based drugs are strongly influenced by non-coding small RNA molecules, the microRNAs (miRNAs). Both increased platinum activity and formation of tumor resistance towards platinum drugs are controlled by miRNAs. This review gives an overview of the interactions between platinum-based drugs and miRNAs, and their influence on platinum activity in various cancer types is discussed.

Pomegranate protects against arsenic-induced p53-dependent ROS-mediated inflammation and apoptosis in liver cells

Molecular mechanisms involved in arsenic-induced toxicity are complex and elusive. Liver is one of the most favored organs for arsenic toxicity as methylation of arsenic occurs mostly in the liver. In this study, we have selected a range of environmentally relevant doses of arsenic to examine the basis of arsenic toxicity and the role of pomegranate fruit extract (PFE) in combating it. Male Swiss albino mice exposed to different doses of arsenic presented marked hepatic injury as evident from histological and electron microscopic studies. Increased activities of enzymes alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatase corroborated extensive liver damage. It was further noted that arsenic exposure initiated reactive oxygen species (ROS)-dependent apoptosis in the hepatocytes involving loss of mitochondrial membrane potential. Arsenic significantly increased nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB), coupled with increase in phosphorylated Iκ-B, possibly as adaptive cellular survival strategies. Arsenic-induced oxidative DNA damage to liver cells culminated in p53 activation and increased expression of p53 targets like miR-34a and Bax. Pomegranate polyphenols are known to possess remarkable antioxidant properties and are capable of protecting normal cells from various stimuli-induced oxidative stress and toxicities. We explored the protective role of PFE in ameliorating arsenic-induced hepatic damage. PFE was shown to reduce ROS generation in hepatocytes, thereby reducing arsenic-induced Nrf2 activation. PFE also inhibited arsenic-induced NF-κB-inflammatory pathway. Data revealed that PFE reversed arsenic-induced hepatotoxicity and apoptosis by modulating the ROS/Nrf2/p53-miR-34a axis. For the first time, we have mapped the possible signaling pathways associated with arsenic-induced hepatotoxicity and its rescue by pomegranate polyphenols.

The Magea gene cluster regulates male germ cell apoptosis without affecting the fertility in mice

While apoptosis is essential for male germ cell development, improper activation of apoptosis in the testis can affect spermatogenesis and cause reproduction defects. Members of the MAGE-A (melanoma antigen family A) gene family are frequently clustered in mammalian genomes and are exclusively expressed in the testes of normal animals but abnormally activated in a wide variety of cancers. We investigated the potential roles of these genes in spermatogenesis by generating a mouse model with a 210-kb genomic deletion encompassing six members of the Magea gene cluster (Magea1, Magea2, Magea3, Magea5, Magea6 and Magea8). Male mice carrying the deletion displayed smaller testes from 2 months old with a marked increase in apoptotic germ cells in the first wave of spermatogenesis. Furthermore, we found that Magea genes prevented stress-induced spermatogenic apoptosis after N-ethyl-N-nitrosourea (ENU) treatment during the adult stage. Mechanistically, deletion of the Magea gene cluster resulted in a dramatic increase in apoptotic germ cells, predominantly spermatocytes, with activation of p53 and induction of Bax in the testes. These observations demonstrate that the Magea genes are crucial in maintaining normal testicular size and protecting germ cells from excessive apoptosis under genotoxic stress.

Oncogenic cancer/testis antigens: prime candidates for immunotherapy

Recent developments have set the stage for immunotherapy as a supplement to conventional cancer treatment. Consequently, a significant effort is required to further improve efficacy and specificity, particularly the identification of optimal therapeutic targets for clinical testing. Cancer/testis antigens are immunogenic, highly cancer-specific, and frequently expressed in various types of cancer, which make them promising candidate targets for cancer immunotherapy, including cancer vaccination and adoptive T-cell transfer with chimeric T-cell receptors. Our current understanding of tumor immunology and immune escape suggests that targeting oncogenic antigens may be beneficial, meaning that identification of cancer/testis antigens with oncogenic properties is of high priority. Recent work from our lab and others provide evidence that many cancer/testis antigens, in fact, have oncogenic functions, including support of growth, survival and metastasis. This novel insight into the function of cancer/testis antigens has the potential to deliver more effective cancer vaccines. Moreover, immune targeting of oncogenic cancer/testis antigens in combination with conventional cytotoxic therapies or novel immunotherapies such as checkpoint blockade or adoptive transfer, represents a highly synergistic approach with the potential to improve patient survival.

Role of MicroRNAs in Malignant Glioma

Objective:

This overview seeked to bring together the microRNA (miRNA) researches on biogenesis and bio-function in these areas of clinical diagnosis and therapy for malignant glioma.

Data Sources:

Using the keyword terms “glioma” and “miRNA,” we performed the literature search in PubMed, Ovid, and web.metstr.com databases from their inception to October 2014.

Study Selection:

In screening out the quality of the articles, factors such as clinical setting of the study, the size of clinical samples were taken into consideration. Animal studied for verification and reviews article were also included in our data collection.

Results:

Despite many advance in miRNA for malignant glioma, further studies were still required to focus on the following aspects: (i) Improving the understanding about biogenesis of miRNA and up-down regulation; (ii) utilizing high-throughput miRNA expression analysis to screen out the core miRNA for glioma; (iii) Focusing related miRNAs on the signal transduction pathways that regulate the proliferation and growth of glioma.

Conclusions:

We discussed the most promising miRNA, correlative signaling pathway and their relation with gliomas in the way of prompting miRNA target into being a clinical therapeutic strategy.

Induction of antigen-specific cytotoxic T-cell response by dendritic cells generated from ecto-mesenchymal stem cells infected with an adenovirus containing the MAGE-D4a gene

The present study aimed to investigate the feasibility of using ecto-mesenchymal stem cell (EMSC)-derived dendritic cells (DCs) for glioma immunotherapy following infection by a recombinant adenovirus containing the melanoma-associated antigen D4a (MAGE-D4a) gene. The ex vivo cultured EMSCs were infected by the adenoviral plasmid containing MAGE-D4a (pAd/MAGE-D4a). Efficiency of transfection was evaluated through the detection of green fluorescent protein-marked MAGE-D4a. The MAGE-EMSCs were induced to differentiate into DCs, termed as MAGE-EMSCs-DCs. The morphology was subsequently analyzed under a microscope, and methyl thiazolyl tetrazolium (MTT) and interferon-γ (IFN-γ) assays were performed to analyze the cytotoxicity of the MAGE-EMSC-DCs on the human glioma U251 cell line. Following purification by magnetic-activated cell sorting, the EMSCs grew into swirls, with a long spindle shape and were fibroblast-like. The gene transfected with recombinant adenovirus vectors maintained high and stable expression levels of MAGE-D4a, and its efficiency was increased in a multiplicity of infection-dependent manner. The results of the MTT assay indicated that the T cells, primed by the recombinant MAGE-D4a-infected EMSC-DCs in vitro, recognized MAGE-D4a-expressing tumor cell lines in a human leukocyte antigen class I-restricted manner, and evoked a higher cytotoxic T cell (CTL) response. The CTL response induced by the MAGE-EMSC-DCs, co-cultured with the U251 cells for 24 h, produced 765.0 pg/ml IFN-γ, which was significantly greater when compared to the control wells. T lymphocytes stimulated by MAGE-EMSC-DCs evoke a higher CTL response to human glioma cell lines, and may serve as a promising therapeutic modality for the treatment of MAGE-D4a-expressing glioma.

Melanoma associated antigen (MAGE)-A3 promotes cell proliferation and chemotherapeutic drug resistance in gastric cancer

BACKGROUND

Melanoma-associated antigen (MAGE)-A3 is a member of the family of cancer-testis antigens and has been found to be epigenetically regulated and aberrantly expressed in various cancer types. It has also been found that MAGE-A3 expression may correlate with an aggressive clinical course and with chemo-resistance. The objectives of this study were to assess the relationship between MAGE-A3 promoter methylation and expression and (1) gastric cancer patient survival and (2) its functional consequences in gastric cancer-derived cells.

METHODS

Samples from two independent gastric cancer cohorts (including matched non-malignant gastric samples) were included in this study. MAGE-A3 methylation and mRNA expression levels were determined by methylation-specific PCR (MSP) and quantitative real-time PCR (qPCR), respectively. MAGE-A3 expression was knocked down in MKN1 gastric cancer-derived cells using miRNAs. In addition, in vitro cell proliferation, colony formation, apoptosis, cell cycle, drug treatment, immunohistochemistry and Western blot assays were performed.

RESULTS

Clinical analysis of 223 primary patient-derived samples (ntumor = 161, nnormal = 62) showed a significant inverse correlation between MAGE-A3 promoter methylation and expression in the cancer samples (R = -0.63, p = 5.99e-19). A lower MAGE-A3 methylation level was found to be associated with a worse patient survival (HR: 1.5, 95 % CI: 1.02-2.37, p = 0.04). In addition, we found that miRNA-mediated knockdown of MAGE-A3 expression in MKN1 cells caused a reduction in its proliferation and colony forming capacities, respectively. Under stress conditions MAGE-A3 was found to regulate the expression of Bax and p21. MAGE-A3 knock down also led to an increase in Puma and Noxa expression, thus contributing to an enhanced docetaxel sensitivity in the gastric cancer-derived cells.

CONCLUSIONS

From our results we conclude that MAGE-A3 expression is regulated epigenetically by promoter methylation, and that its expression contributes to gastric cell proliferation and drug sensitivity. This study underscores the potential implications of MAGE-A3 as a therapeutic target and prognostic marker in gastric cancer patients.

HPV-p53-miR-34a axis in HPV-associated cancers

Human papillomaviruses (HPVs) are known to cause many cancers by altering multiple signalling pathways through their oncogene integration into host genome and expression. Studies have shown that many microRNAs (miRs) may function as oncogenes (called as oncomiRs) to promote an oncogenic effect. MiR-34a among the reported oncomiRs is a key player in the carcinogenesis caused by infection with HPVs. In this mini-review, we summarise the roles of miR-34a in HPV-caused cancers. MiR-34a is transcriptionally regulated by tumour suppressor p53. HPV oncogene E6 inhibits expression of p53 to decrease the levels of miR-34a, leading to the increased expression of multiple genes which are targeted by miR-34a. The upregulation of these genes increases cancer cell proliferation, survival and migration in HPV-associated cancers.

Next generation sequencing of microRNAs from isogenic neuroblastoma cell lines isolated before and after treatment

Neuroblastoma is a pediatric cancer of the developing sympathetic nervous system. High risk neuroblastoma patients typically undergo an initial remission in response to treatment, followed by recurrence of aggressive tumors that have become refractory to further treatment. Recent works have underlined the involvement of microRNAs (miRNAs) in neuroblastoma development and evolution of drug resistance. In this study we have used deep sequencing technology to identify miRNAs differentially expressed in neuroblastoma cell lines isolated from 6 patients at diagnosis and at relapse after intensive treatments. This approach revealed a panel of 42 differentially expressed miRNAs, 8 of which were upregulated and 34 were downregulated. Most strikingly, the 14q32 miRNA clusters encode 22 of the downregulated miRNAs. Reduced expression of 14q32 miRNAs in tumors associated with poor prognosis factors was confirmed in a cohort consisting of 226 primary neuroblastomas. In order to gain insight into the nature of the genes that may be affected by the differentially expressed miRNAs we utilized Ingenuity Pathway Analysis (IPA). This analysis revealed several biological functions and canonical pathways associated with cancer progression and drug resistance. The results of this study contribute to the identification of miRNAs involved in the complex processes of surviving therapeutic treatment and developing drug resistance in neuroblastoma.

miRNAs and ovarian cancer: a miRiad of mechanisms to induce cisplatin drug resistance

Ovarian cancer is the most aggressive gynecological cancer. One reason for the low 5-year survival rate of under 40% is that ovarian tumors usually acquire resistance to the platinum-based compounds used to treat them. Resistance to one such compound, cisplatin, can arise via numerous mechanisms that can be categorized as pre-, post-, on- or off-target. Pre-target mechanisms prevent accumulation of cisplatin in the cell, on-target mechanisms allow DNA damage to be repaired more efficiently, post-target mechanisms prevent the damage from inducing apoptosis and off-target mechanisms increase resistance via unrelated compensatory mechanisms. miRNAs are short non-coding RNAs that influence cellular function by repressing gene expression. Here we describe how miRNAs can induce cisplatin resistance in ovarian cancer cells via pre-, post-, on- and off-target mechanisms. A better understanding of how miRNAs feed into the mechanisms of drug resistance will inform the rational design of combination therapies for ovarian cancer.

A microRNA-1280/JAG2 network comprises a novel biological target in high-risk medulloblastoma

Over-expression of PDGF receptors (PDGFRs) has been previously implicated in high-risk medulloblastoma (MB) pathogenesis. However, the exact biological functions of PDGFRα and PDGFRβ signaling in MB biology remain poorly understood. Here, we report the subgroup specific expression of PDGFRα and PDGFRβ and their associated biological pathways in MB tumors. c-MYC, a downstream target of PDGFRβ but not PDGFRα, is involved in PDGFRβ signaling associated with cell proliferation, cell death, and invasion. Concurrent inhibition of PDGFRβ and c-MYC blocks MB cell proliferation and migration synergistically. Integrated analysis of miRNA and miRNA targets regulated by both PDGFRβ and c-MYC reveals that increased expression of JAG2, a target of miR-1280, is associated with high metastatic dissemination at diagnosis and a poor outcome in MB patients. Our study may resolve the controversy on the role of PDGFRs in MB and unveils JAG2 as a key downstream effector of a PDGFRβ-driven signaling cascade and a potential therapeutic target.