Expression of miR-23a by apoptotic regulators in human cancer: A review

Human papillomavirus type 16 E7 promotes cell viability and migration in cervical cancer by regulating the miR-23a/HOXC8 axis

BACKGROUND

Human papillomavirus (HPV) is a risk factor for the occurrence of cervical cancer (CC). Here, we aimed to explore the role of HPV16 in CC and identify the underlying mechanism.

METHODS

The expression of miR-23a, HPV16 E6/E7 and homeobox C8 (HOXC8) was measured by quantitative real-time PCR or western blot. Cell viability and migration were evaluated using cell counting kit-8, Transwell and wound healing assays. The targeting relationship between miR-23a and HOXC8 was revealed by dual-luciferase reporter assay.

RESULTS

miR-23a was downregulated in HPV16-positive (HPV16+) CC tissues and HPV16+ and HPV18+ cells. Additionally, E6/E7 expression was increased in CC cells. Then, we found that E7, rather than E6, positively regulated miR-23a expression. miR-23a suppressed cell viability and migration, whereas E7 overexpression abrogated this suppression. miR-23a targeted HOXC8, which reversed miR-23a-mediated cell viability and migration.

CONCLUSIONS

HPV16 E7-mediated miR-23a suppressed CC cell viability and migration by targeting HOXC8, suggesting a novel mechanism of HPV-induced CC.

The microRNomes of Chinese hamster ovary (CHO) cells and their extracellular vesicles, and how they respond to osmotic and ammonia stress

A new area of focus in Chinese hamster ovary (CHO) biotechnology is the role of small (exosomes) and large (microvesicles or microparticles) extracellular vesicles (EVs). CHO cells in culture exchange large quantities of proteins and RNA through these EVs, yet the content and role of these EVs remain elusive. MicroRNAs (miRs or miRNA) are central to adaptive responses to stress and more broadly to changes in culture conditions. Given that EVs are highly enriched in miRs, and that EVs release large quantities of miRs both in vivo and in vitro, EVs and their miR content likely play an important role in adaptive responses. Here we report the miRNA landscape of CHO cells and their EVs under normal culture conditions and under ammonia and osmotic stress. We show that both cells and EVs are highly enriched in five miRs (among over 600 miRs) that make up about half of their total miR content, and that these highly enriched miRs differ significantly between normal and stress culture conditions. Notable is the high enrichment in miR-92a and miR-23a under normal culture conditions, in contrast to the high enrichment in let-7 family miRs (let-7c, let-7b, and let-7a) under both stress conditions. The latter suggests a preserved stress-responsive function of the let-7 miR family, one of the most highly preserved miR families across species, where among other functions, let-7 miRs regulate core oncogenes, which, depending on the biological context, may tip the balance between cell cycle arrest and apoptosis. While the expected-based on their profound enrichment-important role of these highly enriched miRs remains to be dissected, our data and analysis constitute an important resource for exploring the role of miRs in cell adaptation as well as for synthetic applications.

Promising Biomarkers in Head and Neck Cancer: The Most Clinically Important miRNAs

Head and neck cancers (HNCs) comprise a heterogeneous group of tumors that extend from the oral cavity to the upper gastrointestinal tract. The principal etiologic factors for oral tumors include tobacco smoking and alcohol consumption, while human papillomavirus (HPV) infections have been accused of a high incidence of pharyngeal tumors. Accordingly, HPV detection has been extensively used to categorize carcinomas of the head and neck. The diverse nature of HNC highlights the necessity for novel, sensitive, and precise biomarkers for the prompt diagnosis of the disease, its successful monitoring, and the timely prognosis of patient clinical outcomes. In this context, the identification of certain microRNAs (miRNAs) and/or the detection of alterations in their expression patterns, in a variety of somatic fluids and tissues, could serve as valuable biomarkers for precision oncology. In the present review, we summarize some of the most frequently studied miRNAs (including miR-21, -375, -99, -34a, -200, -31, -125a/b, -196a/b, -9, -181a, -155, -146a, -23a, -16, -29, and let-7), their role as biomarkers, and their implication in HNC pathogenesis. Moreover, we designate the potential of given miRNAs and miRNA signatures as novel diagnostic and prognostic tools for successful patient stratification. Finally, we discuss the currently ongoing clinical trials that aim to identify the diagnostic, prognostic, or therapeutic utility of miRNAs in HNC.

BH3-Only Proteins Noxa and Puma Are Key Regulators of Induced Apoptosis

Apoptosis is an evolutionarily conserved and tightly regulated cell death pathway. Physiological cell death is important for maintaining homeostasis and optimal biological conditions by continuous elimination of undesired or superfluous cells. The BH3-only pro-apoptotic members are strong inducers of apoptosis. The pro-apoptotic BH3-only protein Noxa activates multiple death pathways by inhibiting the anti-apoptotic Bcl-2 family protein, Mcl-1, and other protein members leading to Bax and Bak activation and MOMP. On the other hand, Puma is induced by p53-dependent and p53-independent apoptotic stimuli in several cancer cell lines. Moreover, this protein is involved in several physiological and pathological processes, such as immunity, cancer, and neurodegenerative diseases. Future heat shock research could disclose the effect of hyperthermia on both Noxa and BH3-only proteins. This suggests post-transcriptional mechanisms controlling the translation of both Puma and Noxa mRNA in heat-shocked cells. This study was also the chance to recapitulate the different reactional mechanisms investigated for caspases.

Mefunidone Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is one of the most common and devastating interstitial lung diseases with poor prognosis. Currently, few effective drugs are available for IPF. Hence, we sought to explore the role of mefunidone (MFD), a newly synthesized drug developed by our team, in lung fibrosis. In this study, MFD was found to attenuate bleomycin (BLM) -induced lung fibrosis and inflammation in mice according to Ashcroft and alveolitis scoring. The protein contents and total cell counts in bronchoalveolar lavage fluids of BLM-treated mice were also lowered by MFD. Moreover, the elevation of TGF-β/Smad2 and phosphorylation of MAPK pathways was repressed by MFD. Additionally, MFD attenuated the swelling and vacuolization of mitochondria, lowered the ratio of apoptotic cells, restored the mitochondrial membrane potential, and reversed the expression of cleaved-caspase 3, Bcl-2 and Bax. Meanwhile, the level of epithelial marker, E-cadherin, was restored by MFD, while the levels of mesenchymal markers such as Snail and vimentin were down-regulated by MFD. Besides, MFD inhibited the expression of fibronectin and α-smooth muscle actin in TGF-β treated normal human lung fibroblasts. Thus, our findings suggested that MFD could ameliorate lung fibrosis, cell apoptosis and EMT potentially via suppression of TGF-β/Smad2 and MAPK pathways.

Low concentration of Bupivacaine ameliorates painful diabetic neuropathy by mediating miR-23a/PDE4B axis in microglia

Bupivacaine (Bup) has a certain research basis in pain-related diseases, but it has not been studied in painful diabetic neuropathy. In this study, we investigated the role of Bupivacaine in painful diabetic neuropathy. Mouse model with painful diabetic neuropathy was established, and then treated with different concentrations of Bupivacaine. The blood glucose level in the tail vein and the changes in body weight was measured. The mechanical allodynia, thermal hyperalgesia and thermal allodynia was assessed by pain behavioral tests. Microglia were treated with high glucose (HG) and different concentrations of Bupivacaine. The levels of inflammatory cytokines were detected by using Enzyme-linked immunosorbent assays. Dual luciferase reporter assay explored the relationship between miR-23a and phosphodiesterase 4 B (PDE4B). The results displayed that Bupivacaine ameliorated the mechanical allodynia, thermal hyperalgesia, and thermal allodynia in mice with painful diabetic neuropathy, and is more effective at low concentration. Moreover, low concentration of Bupivacaine inhibited inflammation and promoted miR-23a expression in mice with painful diabetic neuropathy and in microglia induced by HIGH GLUCOSE. Overexpression of miR-23a reduced the levels of inflammatory cytokines by down-regulating PDE4B expression. Knockdown of miR-23a reversed the inhibition effect of Bupivacaine on microglial inflammation. These results revealed that low concentration of Bupivacaine inhibited microglial inflammation through down-regulating PDE4B via miR-23a, thereby attenuated painful diabetic neuropathy.

Loss of STAT5A promotes glucose metabolism and tumor growth through miRNA-23a-AKT signaling in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Here, we identified that increased miR‐23a expression in HCC tissues was associated with worse survival. More importantly, we found that STAT5A was a target of miR‐23a, whose levels significantly decreased in tumor tissues. Stable expression of STAT5A in Huh7 cells suppressed glucose metabolism and tumor growth. Finally, this study showed that increased miR‐23a negatively regulated STAT5A, which further activated AKT signaling to enable rapid metabolism for accelerated tumor growth in HCC. Taken together, our results demonstrated that the miR‐23a‐STAT5A‐AKT signaling pathway is critical to alter glucose metabolism in HCC and may offer new opportunities for effective therapy.

MicroRNA-23a-3p Down-Regulation in Active Pulmonary Tuberculosis Patients with High Bacterial Burden Inhibits Mononuclear Cell Function and Phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 Signaling via Targeting IRF1/SP1

The aim of this study is to explore the role of microRNAs (miR)-21/23a/146a/150/155 targeting the toll-like receptor pathway in active tuberculosis (TB) disease and latent TB infection (LTBI). Gene expression levels of the five miRs and predicted target genes were assessed in peripheral blood mononuclear cells from 46 patients with active pulmonary TB, 15 subjects with LTBI, and 17 non-infected healthy subjects (NIHS). THP-1 cell lines were transfected with miR-23a-3p mimics under stimuli with Mycobacterium TB-specific antigens. Both miR-155-5p and miR-150-5p gene expressions were decreased in the active TB group versus the NIHS group. Both miR-23a-3p and miR-146a-5p gene expressions were decreased in active TB patients with high bacterial burden versus those with low bacterial burden or control group (LTBI + NIHS). TLR2, TLR4, and interleukin (IL)10 gene expressions were all increased in active TB versus NIHS group. MiR-23a-3p mimic transfection reversed ESAT6-induced reduction of reactive oxygen species generation, and augmented ESAT6-induced late apoptosis and phagocytosis, in association with down-regulations of the predicted target genes, including tumor necrosis factor (TNF)-α, TLR4, TLR2, IL6, IL10, Notch1, IL6R, BCL2, TGF-β1, SP1, and IRF1. In conclusion, the down-regulation of miR-23a-3p in active TB patients with high bacterial burden inhibited mononuclear cell function and phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 signaling via targeting IRF1/SP1.

Overexpression of microRNA-145 inhibits tumorigenesis through autophagy in chemotherapy and radiation resistant neuroblastoma cells

MicroRNA-145 (miR-145) plays a suppressive role in the process of tumorigenesis and an important role in induction of autophagy. However, the exact role of miR-145 in therapeutically resistant neuroblastoma cells remain elusive. Herein, we sought to evaluate the effects of miR-145 overexpression in chemo‑ and radiation-resistant neuroblastoma cells. We hypothesized that miR-145 affects the aggressiveness of resistant cells by enhancing autophagy. We established Cisplatin-resistant (CDDP-R), Vincristine-resistant (Vin-R), and radiation-resistant (Rad-R) neuroblastoma cells and found that miR-145 expression was significantly decreased in the resistant cells compared to the parental cells. Exogenously expression of miR-145 inhibited oncogenic properties such as proliferation, clonogenicity, anchorage-independent growth, cell migration, and tubule formation in the resistant cells. In addition, we also found that an autophagy protein marker, LC3, was only minimally expressed in the resistant cells. In particular, when miR-145 was overexpressed in the resistant cells, LC3 I and II were expressed and an increased punctate fluorescence of LC3 protein was found indicating the induction of autophagy. Taken together, our data suggests that miR-145 inhibits tumorigenesis and aggressiveness via modulation of autophagy in neuroblastoma.

miR-21-5p Under-Expression in Patients with Obstructive Sleep Apnea Modulates Intermittent Hypoxia with Re-Oxygenation-Induced-Cell Apoptosis and Cytotoxicity by Targeting Pro-Inflammatory TNF-α-TLR4 Signaling

The purpose of this study is to explore the anti-inflammatory role of microRNAs (miR)-21 and miR-23 targeting the TLR/TNF-α pathway in response to chronic intermittent hypoxia with re-oxygenation (IHR) injury in patients with obstructive sleep apnea (OSA). Gene expression levels of the miR-21/23a, and their predicted target genes were assessed in peripheral blood mononuclear cells from 40 treatment-naive severe OSA patients, and 20 matched subjects with primary snoring (PS). Human monocytic THP-1 cell lines were induced to undergo apoptosis under IHR exposures, and transfected with miR-21-5p mimic. Both miR-21-5p and miR-23-3p gene expressions were decreased in OSA patients as compared with that in PS subjects, while TNF-α gene expression was increased. Both miR-21-5p and miR-23-3p gene expressions were negatively correlated with apnea hypopnea index and oxygen desaturation index, while TNF-α gene expression positively correlated with apnea hypopnea index. In vitro IHR treatment resulted in decreased miR-21-5p and miR-23-3p expressions. Apoptosis, cytotoxicity, and gene expressions of their predicted target genes—including TNF-α, ELF2, NFAT5, HIF-2α, IL6, IL6R, EDNRB, and TLR4—were all increased in response to IHR, while all were reversed with miR-21-5p mimic transfection under IHR condition. The findings provide biological insight into mechanisms by which IHR-suppressed miRs protect cell apoptosis via inhibit inflammation, and indicate that over-expression of the miR-21-5p may be a new therapy for OSA.

Overexpression of miR-17 is correlated with liver metastasis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in men and women. The presence of systemic disease, with metastatic spread to distant sites such as the liver, considerably reduces the survival rate in CRC. Cancer stem cells contribute to the metastatic potential of CRC. However, the mechanism underlying metastasis in CRC remains unclear. Thus, this study aimed to examine the expression of microRNAs (miRNAs) in CRC stem cells in cases of liver metastases and assess their correlation with clinicopathological features.

METHODS

miRNAs showing high expression in liver metastases and primary lesions were selected through data mining of gene expression omnibus datasets, and miRNAs characteristic of stem cells were selected through COREMINE medical text mining. Subsequently, paired formalin-fixed paraffin-embedded tissue samples of primary CRC and liver metastasis from 30 patients were examined for the expression of miRNAs common to these lists (hsa-miR-20a, hsa-miR-26b, hsa-miR-146a, hsa-miR-17, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a) using quantitative real-time polymerase chain reaction. Further, miRNA expression was compared between liver metastases and the primary tumor in each patient and the factors associated with differential expression were analyzed.

RESULTS

hsa-miR-17 was significantly upregulated in liver metastases (P < .05), but no significant difference in the expression of hsa-miR-26b, hsa-miR-146a, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a was observed between primary tumors and liver metastases. The higher expression of hsa-miR-17 in liver metastases was associated with the administration of neoadjuvant chemotherapy and tumor differentiation (P < .05) but was not associated with age, sex, tumor location, or lymphatic metastasis.

CONCLUSIONS

High expression of miR-17 may contribute to liver metastasis in CRC. Therefore, an in-depth understanding of its downstream pathways could help in elucidating the mechanisms underlying liver metastases in CRC. However, additional studies are warranted to validate these findings.

MiRNA-610 acts as a tumour suppressor to depress the cisplatin resistance in hepatocellular carcinoma through targeted silencing of hepatoma-derived growth factor

INTRODUCTION

Hepatic malignancy is one of the most common malignant neoplasms around the globe, and hepatocellular carcinoma (HCC) is the most common type. In this study, the roles and mechanisms of MiRNA-610 in the chemo resistance of HCC will be discussed.

MATERIAL AND METHODS

The expression of MiRNA-610 and hepatoma-derived growth factor (HDGF) in HCC tissues and cell line was detected by quantitative real-time PCR. The proliferation and chemo resistance were analysed by MTT assay. Flow cytometry was used to examine the apoptosis rate. Luciferase reporter assay was used to verify the correlation between MiRNA-610 and HDGF. HDGF protein expression was detected by Western blot.

RESULTS

Our study confirmed the low-expression of MiRNA-610 in HCC tissues and cell line. Its low expression was related to high T stages and poor differentiation of HCC, and was a prognostic factor for HCC. MiRNA-610 upregulation inhibited cell proliferation and induced apoptosis of HepG2 cells. MiRNA-610 enhancement decreased the half maximal inhibitory concentration for cisplatin (DDP) and depressed the DDP resistance in HepG2 cells. The specific correlation between MiRNA-610 and HDGF was tested by luciferase reporter assay and western blot. The transfection with HDGF expression vector up-regulated the expression of HDGF protein silenced by MiRNA-610 enhancement. HDGF overexpression was found to reverse partly the regulatory roles of MiRNA-610 on malignancy and DDP resistance.

CONCLUSIONS

MiRNA-610 not only played a tumour suppressor role in HCC but also affected chemo resistance to DDP. This role is mainly mediated through targeted silencing of the HDGF gene, which may offer a new potential therapeutic target and improve the clinical therapeutic effect for HCC.

Circulating Extracellular Vesicle MicroRNA as Diagnostic Biomarkers in Early Colorectal Cancer-A Review

Colorectal cancer (CRC) is one of the most common malignancies in the developed world, with global deaths expected to double in the next decade. Disease stage at diagnosis is the single greatest prognostic indicator for long-term survival. Unfortunately, early stage CRC is often asymptomatic and diagnosis frequently occurs at an advanced stage, where long-term survival can be as low as 14%. Circulating microRNAs encapsulated in extracellular vesicles (EVs) have recently come to prominence as novel diagnostic markers for cancer. EV-miRNAs are dysregulated in the circulation of CRC patients compared to healthy controls, and several specific miRNA candidates have been posited as diagnostic markers, including miR-21, miR-23a, miR-1246, and miR-92a. This review outlines the current landscape of EV-miRNAs as potential diagnostic markers for CRC, with a specific focus on those able to detect early stage disease.

Examination of the Role of miR-23a in the Development of Thermotolerance

BACKGROUND

Thermotolerance is an acquired state of increased heat resistance that occurs following exposure to non-lethal proteotoxic stress. A large body of evidences implicates that molecular chaperon members belonging to the heat shock protein family could be acting as potential mediators of the thermotolerant state.

OBJECTIVE

Recent evidence has demonstrated heat shock proteins HSP90, HSP70 and HSP27 have inhibited heat-induced cell death by intervening at various steps in stressinduced apoptotic pathways. Previous studies have shown that HSP70 prevented heatinduced apoptosis by preventing the NOXA dependent decrease in MCL-1 levels leading to both BAX activation and cytochrome c release from mitochondria. We have also demonstrated that HSP70 expressing cells have enhanced levels of miR-23a prevent heat-induced increase in NOXA levels and suppress apoptosis.

METHODS

Stably transfected cell lines expressing either a control shRNA or a miR-23a targeting shRNA are quantified using both RT-PCR and semi-quantitative RT-PCR to determine the effect of different hyperthermic exposure treatment on miR-23a and Noxa mRNA expression levels.

RESULTS

This study shows that thermotolerant-induced pre-heat shock treatment is capable of increasing miR-23a levels. Furthermore, stable cell clones expressing a miR- 23a targeting shRNA having reduced miR-23a levels are incapable of developing a thermotolerance state, leading to apoptosis.

CONCLUSION

These results demonstrate the novel finding that miR-23a is an important factor in the development of the thermotolerant state.

Secondary Structural Model of Human MALAT1 Reveals Multiple Structure-Function Relationships

Human metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is an abundant nuclear-localized long noncoding RNA (lncRNA) that has significant roles in cancer. While the interacting partners and evolutionary sequence conservation of MALAT1 have been examined, much of the structure of MALAT1 is unknown. Here, we propose a hypothetical secondary structural model for 8425 nucleotides of human MALAT1 using three experimental datasets that probed RNA structures in vitro and in various human cell lines. Our model indicates that approximately half of human MALAT1 is structured, forming 194 helices, 13 pseudoknots, five structured tetraloops, nine structured internal loops, and 13 intramolecular long-range interactions that give rise to several multiway junctions. Evolutionary conservation and covariation analyses support 153 of 194 helices in 51 mammalian MALAT1 homologs and 42 of 194 helices in 53 vertebrate MALAT1 homologs, thereby identifying an evolutionarily conserved core that likely has important functional roles in mammals and vertebrates. Data mining revealed that RNA modifications, somatic cancer-associated mutations, and single-nucleotide polymorphisms may induce structural rearrangements that sequester or expose binding sites for several cancer-associated microRNAs. Our findings reveal new mechanistic leads into the roles of MALAT1 by identifying several intriguing structure–function relationships in which the dynamic structure of MALAT1 underlies its biological functions.

MicroRNAs play an important role in contributing to arsenic susceptibility in the chronically exposed individuals of West Bengal, India

Arsenic exposure by groundwater contamination is a menace which threatens more than 26 million individuals of West Bengal. Interestingly, with similar levels of arsenic exposure, only 15-20% of the population show arsenic-induced skin lesions, the hallmarks of chronic arsenic toxicity, but the rest do not. In this study, our aim was to identify whether microRNAs (miRNA) have any role to play in causing such arsenic susceptibility. Global plasma miRNA profiling was done in 12 arsenic-exposed individuals with skin lesions and 12 exposed individuals without skin lesions. Two hundred two miRNAs were found to be differentially regulated between the two study groups. Results were validated by quantitative real-time PCR in 30 exposed subjects from each of the groups, which showed that among others miR-21, miR-23a, miR-27a, miR-122, miR-124, miR-126, miR-619, and miR-3613 were significantly upregulated and miR-1282 and miR-4530 were downregulated in the skin lesion group compared with the no skin lesion group. Bioinformatic analyses predicted that these altered miRNAs have targets in 7 different biochemical pathways, including glycerophospholipid metabolism, colorectal cancer, glycosphingolipid biosynthesis, T cell receptor signaling, and neurotrophin signaling pathways; glycerophospholipid metabolism pathway being the most enriched pathway. Association study show that these microRNAs contribute significantly to the increased prevalence of other non-dermatological health effects like conjunctival irritations of the eyes and respiratory distress in the study subjects. To our knowledge, this is the first study of its kind involving miRNA expressions contributing to arsenic susceptibility in the exposed population of West Bengal.

MicroRNA-23a inhibits osteogenesis of periodontal mesenchymal stem cells by targeting bone morphogenetic protein signaling

OBJECTIVES

To investigate the role of microRNA-23a (miR-23a) in the osteogenesis of periodontal mesenchymal stem cells (PDLSCs) in periodontitis.

MATERIALS AND METHODS

Gingival crevicular fluid samples were collected from 21 control subjects and 29 patients with chronic periodontitis. MiR-23a was determined by quantitative real-time PCR. PDLSCs were transfected with miR-23a overexpressing lentiviruses. Subsequently, PDLSCs were induced with osteogenic differentiation media. Osteogenic differentiation of PDLSCs was assessed by alkaline phosphatase activity assay, Alizarin red staining, and qRT-PCT detection of osteogenic gene expression. Western blot was performed to detect the protein levels of the SMAD family member 1/5/9 (Smad1/5/9) and their phosphorylation level. TargetScan was used to predict the target gene of miR-23a. Cotransfections of bone morphogenetic protein receptor type 1B (BMPR1B) and miR-23a applied to explore the relationship between BMPR1B and miR-23a.

RESULTS

MiR-23a was significantly increased in PDLSCs and gingival crevicular fluid of periodontitis patients. Patients with gingival crevicular fluid miR-23a levels above a threshold showed more clinical indicators of periodontitis. After periodontal therapy, miR-23a levels significantly decreased. Overexpression miR-23a inhibited osteogenesis of PDLSCs, which was evidenced by reduced Alizarin Red S and osteogenic gene expressions. In addition, miR-23a inhibited the phosphorylation of Smad1/5/9. TargetScan predicted that BMPR1B is a target gene of miR-23a. Overexpression of BMPR1B abolished the effects caused by overexpression of miR-23a.

CONCLUSION

Our study provides novel evidence that miR-23a acts as a negative regulator of osteogenesis in periodontitis patients'PDLSCs and that miR-23a may serve as a biomarker and potential target of periodontitis.

miR-23a promotes invasion of glioblastoma via HOXD10-regulated glial-mesenchymal transition

Glioblastoma is the most aggressive and invasive brain tumor and has a poor prognosis; elucidating the underlying molecular mechanisms is essential to select molecular targeted therapies. Here, we investigated the effect of microRNAs on the marked invasiveness of glioblastoma. U373 glioblastoma cells were infected with 140 different microRNAs from an OncomiR library, and the effects of the invasion-related microRNAs and targeted molecules were investigated after repeated Matrigel invasion assays. Screening of the OncomiR library identified miR-23a as a key regulator of glioblastoma invasion. In six glioblastoma cell lines, a positive correlation was detected between the expression levels of miR-23a and invasiveness. A luciferase reporter assay demonstrated that homeobox D10 (HOXD10) was a miR-23a-target molecule, which was verified by high scores from both the PicTar and miRanda algorithms. Forced expression of miR-23a induced expression of invasion-related molecules, including uPAR, RhoA, and RhoC, and altered expression of glial-mesenchymal transition markers such as Snail, Slug, MMP2, MMP9, MMP14, and E-cadherin; however, these changes in expression levels were reversed by HOXD10 overexpression. Thus, miR-23a significantly promoted invasion of glioblastoma cells with polarized formation of focal adhesions, while exogenous HOXD10 overexpression reversed these phenomena. Here, we identify miR-23a-regulated HOXD10 as a pivotal regulator of invasion in glioblastoma, providing a novel mechanism for the aggressive invasiveness of this tumor and providing insight into potential therapeutic targets.

Researchers in Japan have identified key genetic players in an aggressive form of brain cancer. Glioblastoma is the most invasive type of brain tumor, with a five-year survival rate of just 7%. To investigate its invasiveness, a team led by Shinya Tanaka of Hokkaido University tested the effect of 140 microRNAs on glioblastoma cells. They found that miR-23a increased the invasiveness of the cells. Further research revealed that miR-23a reduces the level of the regulatory gene HOXD10 by destroying the protein it encodes. This reduction leads to changes in the expression of genes regulated by HOXD10, increasing affected cells’ invasiveness and altering their morphology. The miR-23a/HOXD10 pathway revealed here not only provides insight into the biology of glioblastoma but also offers a potential therapeutic target.

Aflatoxin B1 and M1: Biological Properties and Their Involvement in Cancer Development

Aflatoxins are fungal metabolites found in feeds and foods. When the ruminants eat feedstuffs containing Aflatoxin B1 (AFB1), this toxin is metabolized and Aflatoxin M1 (AFM1) is excreted in milk. International Agency for Research on Cancer (IARC) classified AFB1 and AFM1 as human carcinogens belonging to Group 1 and Group 2B, respectively, with the formation of DNA adducts. In the last years, some epidemiological studies were conducted on cancer patients aimed to evaluate the effects of AFB1 and AFM1 exposure on cancer cells in order to verify the correlation between toxin exposure and cancer cell proliferation and invasion. In this review, we summarize the activation pathways of AFB1 and AFM1 and the data already reported in literature about their correlation with cancer development and progression. Moreover, considering that few data are still reported about what genes/proteins/miRNAs can be used as damage markers due to AFB1 and AFM1 exposure, we performed a bioinformatic analysis based on interaction network and miRNA predictions to identify a panel of genes/proteins/miRNAs that can be used as targets in further studies for evaluating the effects of the damages induced by AFB1 and AFM1 and their capacity to induce cancer initiation.

PGC1α: Friend or Foe in Cancer?

The PGC1 family (Peroxisome proliferator-activated receptor γ (PPARγ) coactivators) of transcriptional coactivators are considered master regulators of mitochondrial biogenesis and function. The PGC1α isoform is expressed especially in metabolically active tissues, such as the liver, kidneys and brain, and responds to energy-demanding situations. Given the altered and highly adaptable metabolism of tumor cells, it is of interest to investigate PGC1α in cancer. Both high and low levels of PGC1α expression have been reported to be associated with cancer and worse prognosis, and PGC1α has been attributed with oncogenic as well as tumor suppressive features. Early in carcinogenesis PGC1α may be downregulated due to a protective anticancer role, and low levels likely reflect a glycolytic phenotype. We suggest mechanisms of PGC1α downregulation and how these might be connected to the increased cancer risk that obesity is now known to entail. Later in tumor progression PGC1α is often upregulated and is reported to contribute to increased lipid and fatty acid metabolism and/or a tumor cell phenotype with an overall metabolic plasticity that likely supports drug resistance as well as metastasis. We conclude that in cancer PGC1α is neither friend nor foe, but rather the obedient servant reacting to metabolic and environmental cues to benefit the tumor cell.

Regulation of stressed-induced cell death by the Bcl-2 family of apoptotic proteins

Apoptosis is often deregulated in a number of human diseases. Heat-induced apoptosis is a model system for studying the consequences of protein misfolding and is mediated by the Bcl-2 family of proteins. This family consists of both pro-apoptotic and anti-apoptotic members that control mitochondrial integrity. The BH3-only pro-apoptotic members are strong inducers of apoptotic cell death. Protein damaging stress can activate a process of cellular destruction known as apoptosis. The pro-apoptotic BH3-only proteins and transcription factors activate this death pathway by inhibiting the anti-apoptotic Bcl-2 family proteins eliminating cancer cells in a short period of time.