Emerging roles of miR-210 and other non-coding RNAs in the hypoxic response

Expression of miR-210 in relation to other measures of hypoxia and prediction of benefit from hypoxia modification in patients with bladder cancer

BACKGROUND

The addition of hypoxia modifiers carbogen and nicotinamide (CON) to radiotherapy (RT) improved overall survival (OS) in bladder cancer patients in the BCON phase III clinical trial. We investigate whether expression of hsa-miR-210 in BCON patient samples reflects hypoxia and predicts benefit from hypoxia modification.

METHODS

In all, 183 T1-T4a bladder cancer samples were available for miR-210 analysis. A total of 86 received RT+CON and 97 received RT alone. TaqMan qPCR plates were used to assess miR-210 expression. Patients were classified as low (

RESULTS

Patients with high miR-210 had a trend towards improved 5-year OS with RT+CON (53.2%) compared with RT alone (37.8%; hazard ratio (HR) 1.68, 95% CI 0.95-2.95, P=0.07). No benefit was seen with low miR-210 (HR 1.02, 95% CI 0.58-1.79, P=0.97). High miR-210 was significantly associated with high HIF-1α protein (P=0.001), CA9 protein (P=0.0004), Glut-1 protein (P=0.001), 26-gene hypoxia score (P=0.007), tumour necrosis (P=0.02) and concurrent pTis (P=0.03).

CONCLUSIONS

High miR-210 may reflect hypoxia in bladder cancer. However, its ability to predict benefit from hypoxia modification does not improve upon other hypoxia markers. Investigation as part of a miRNA hypoxia signature may reveal the full potential of miR-210.

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Key Words

• bladder cancer
• microrna
• hypoxic modification
• necrosis
• biomarker
• radiotherapy
• carbogen and nicotinamide

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MESH Headings

• Aged
• Aged, 80 and over
• Cell Hypoxia/genetics
• Female
• Humans
• Male
• MicroRNAs/genetics
• Middle Aged
• Urinary Bladder Neoplasms/genetics
• Urinary Bladder Neoplasms/pathology

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Grants

• 11359 Cancer Research UK
• G0300648 Medical Research Council
• 16466 Cancer Research UK
• G0801525 Medical Research Council
• 18974 Cancer Research UK

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Affiliation(s)

J J Irlam-Jones Translational Radiobiology Group, Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Manchester M20 4BX, UK
A Eustace Translational Radiobiology Group, Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Manchester M20 4BX, UK
H Denley Department of Histopathology, Central Manchester University Hospitals NHS Foundation Trust, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK
A Choudhury Christie Hospital, Wilmslow Road, Manchester M20 4BX, UK
A L Harris Molecular Oncology Laboratories, Department of Oncology, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford University, Oxford OX3 9DS, UK
P J Hoskin Cancer Centre, Mount Vernon Hospital, Rickmansworth Road, Northwood, Middlesex HA6 2RN, UK
C M L West Translational Radiobiology Group, Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Manchester M20 4BX, UK

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MicroRNAs as prognostic molecular signatures in renal cell carcinoma: a systematic review and meta-analysis

This is a systematic review of studies investigating the prognostic value of different microRNAs (miRs) in renal cell carcinoma (RCC). Twenty-seven relevant studies were identified, with a total of 2578 subjects. We found that elevated expression of miR-21, miR-1260b, miR-210, miR-100, miR-125b, miR-221, miR-630, and miR-497 was associated with a poor prognosis in RCC patients. Conversely, decreased expression of miR-106b, miR-99a, miR-1826, miR-215, miR-217, miR-187, miR-129–3p, miR-23b, miR-27b, and miR-126 was associated with a worse prognosis. We performed meta-analyses on studies to address the prognostic value of miR-21, miR-126, miR-210, and miR-221. This revealed that elevated miR-21 expression was associated with shorter overall survival (OS; hazard ratio [HR], 2.29; 95% confidence interval [CI], 1.28–4.08), cancer specific survival (CSS; HR, 4.16; 95% CI, 2.49–6.95), and disease free survival (DFS; HR, 2.15; 95% CI, 1.16–3.98). The decreased expression of miR-126 was associated with shorter CSS (HR, 0.35; 95% CI, 0.15–0.85), OS (HR, 0.45; 95% CI, 0.30–0.69), and DFS (HR 0.30; 95% CI, 0.18–0.50). Our comprehensive systematic review reveals that miRs, especially miR-21 and miR-126, could be promising prognostic markers and useful therapeutic targets in RCC.

Insights into the Regulatory Role of Non-coding RNAs in Cancer Metabolism

Cancer represents a complex disease originated from alterations in several genes leading to disturbances in important signaling pathways in tumor biology, favoring heterogeneity that promotes adaptability and pharmacological resistance of tumor cells. Metabolic reprogramming has emerged as an important hallmark of cancer characterized by the presence of aerobic glycolysis, increased glutaminolysis and fatty acid biosynthesis, as well as an altered mitochondrial energy production. The metabolic switches that support energetic requirements of cancer cells are closely related to either activation of oncogenes or down-modulation of tumor-suppressor genes, finally leading to dysregulation of cell proliferation, metastasis and drug resistance signals. Non-coding RNAs (ncRNAs) have emerged as one important kind of molecules that can regulate altered genes contributing, to the establishment of metabolic reprogramming. Moreover, diverse metabolic signals can regulate ncRNA expression and activity at genetic, transcriptional, or epigenetic levels. The regulatory landscape of ncRNAs may provide a new approach for understanding and treatment of different types of malignancies. In this review we discuss the regulatory role exerted by ncRNAs on metabolic enzymes and pathways involved in glucose, lipid, and amino acid metabolism. We also review how metabolic stress conditions and tumoral microenvironment influence ncRNA expression and activity. Furthermore, we comment on the therapeutic potential of metabolism-related ncRNAs in cancer.

Hypoxic regulation of the noncoding genome and NEAT1

Activation of hypoxia pathways is both associated with and contributes to an aggressive phenotype across multiple types of solid cancers. The regulation of gene transcription by hypoxia-inducible factor (HIF) is a key element in this response. HIF directly upregulates the expression of many hundreds of protein-coding genes, which act to both improve oxygen delivery and to reduce oxygen demand. However, it is now becoming apparent that many classes of noncoding RNAs are also regulated by hypoxia, with several (e.g. micro RNAs, long noncoding RNAs and antisense RNAs) under direct transcriptional regulation by HIF. These hypoxia-regulated, noncoding RNAs may act as effectors of the indirect response to HIF by acting on specific coding transcripts or by affecting generic RNA-processing pathways. In addition, noncoding RNAs may also act as modulators of the HIF pathway, either by integrating other physiological responses or, in the case of HIF-regulated, noncoding RNAs, by providing negative or positive feedback and feedforward loops that affect upstream or downstream components of the HIF cascade. These hypoxia-regulated, noncoding transcripts play important roles in the aggressive hypoxic phenotype observed in cancer.

Elevation of Circulating miR-210-3p in High-Altitude Hypoxic Environment

Background: The induction of miR-210-3p, a master hypoxamir, is a consistent feature of the hypoxic response in both normal and malignant cells. However, whether miR-210-3p acts as a circulating factor in response to a hypoxic environment remains unknown. The current study aimed to examine the effect of a high-altitude hypoxic environment on circulating miR-210-3p.

Methods: We examined and compared the levels of miR-210-3p using TaqMan-based qRT-PCR in both peripheral blood cells and plasma from 84 ethnic Chinese Tibetans residing at 3560 m, 46 newly arrived migrant Han Chinese (Tibet Han) and 82 Han Chinese residing at 8.9 m (Nanjing Han). Furthermore, we analyzed the correlations of miR-210-3p with hematological indices.

Results: The relative concentrations of miR-210-3p to internal reference U6 in blood cells were significantly higher in the Tibet Han group (1.01 ± 0.11, P < 0.001) and in the Tibetan group (1.17 ± 0.09, P < 0.001) than in the Nanjing Han group (0.51 ± 0.04). The absolute concentrations of plasma miR-210-3p were also markedly elevated in the Tibet Han group (503.54 ± 42.95 fmol/L, P = 0.004) and in the Tibetan group (557.78 ± 39.84 fmol/L, P < 0.001) compared to the Nanjing Han group (358.39 ± 16.16 fmol/L). However, in both blood cells and plasma, miR-210-3p levels were not significantly different between the Tibet Han group and the Tibetan group (P = 0.280, P = 0.620, respectively). Plasma miR-210-3p concentrations were positively correlated with miR-210-3p levels in blood cells (r = 0.192, P = 0.005). Furthermore, miR-210-3p levels in both blood cells and plasma showed strong positive correlations with red blood cell counts and hemoglobin and hematocrit values.

Conclusion: These data demonstrated, for the first time, that miR-210-3p might act as a circulating factor in response to hypoxic environments and could be associated with human adaptation to life at high altitudes.

Hypoxia promotes the invasion and metastasis of laryngeal cancer cells via EMT

The purpose of this study is to explore the role of hypoxia on the invasion and metastasis of laryngeal carcinoma. The invasion and migration ability of laryngeal cancer SCC10A cell was detected by transwell assay. Western blot was applied to analyze the expression of EMT-related proteins. Fifty-seven samples from postoperative patients with laryngeal cancer were collected to study. Immunohistochemistry was used to examine the expression of GLUT-1 and EMT-related proteins (Vim, E-cad, N-cad) in normal laryngeal squamous epithelial tissue, laryngeal cancer adjacent tissues and laryngeal squamous cell carcinoma tissues. Hypoxia promoted laryngeal cancer cell invasion and migration. Hypoxia also enhanced the expression of GLUT-1, vimentin and N-cad, which exist statistically significant correlation with the clinical staging and lymph node metastases (P < 0.05). The expression of GLUT-1 is positively correlated with Vim and N-cad expression in laryngeal squamous cell carcinoma tissues, but negatively correlated with E-cad expression. The patient survival rate with the positive expression of GLUT-1, Vim and N-cad becomes much shorter compared with those with negative expression of GLUT-1, Vim and N-cad (P < 0.05). Hypoxia promoted laryngeal cancer cell invasion and migration via EMT.

Cardiac Extracellular Vesicles in Normal and Infarcted Heart

Heart is a complex assembly of many cell types constituting myocardium, endocardium and epicardium that intensively communicate to each other in order to maintain the proper cardiac function. There are many types of intercellular intracardiac signals, with a prominent role of extracellular vesicles (EVs), such as exosomes and microvesicles, for long-distant delivering of complex messages. Cardiomyocytes release EVs, whose content could significantly vary depending on the stimulus. In stress, such as hypoxia, inflammation or injury, cardiomyocytes increase secretion of EVs. In hypoxic conditions, cardiac EVs are enriched with angiogenic and prosurvival factors. In acute myocardial infarction (AMI), damaged cardiac muscle cells produce EVs with increased content of angiogenic, anti-apoptotic, mitogenic and growth factors in order to induce repair and healing of the infarcted myocardium. Exosomal microRNAs play a central role in cardiac regeneration. In AMI, circulating cardiac EVs abundantly contain cardiac-specific miRNAs that serve as indicators of cardiac damage and have a big diagnostic potential as AMI biomarkers. Cardioprotective and regenerative properties of exosomes derived from cardiac and non-cardiac stem/progenitor cells are very helpful to be used in cell-free cardiotherapy and regeneration of post-infarct myocardium.

microRNA regulation of the embryonic hypoxic response in Caenorhabditis elegans

Layered strategies to combat hypoxia provide flexibility in dynamic oxygen environments. Here we show that multiple miRNAs are required for hypoxic survival responses during C. elegans embryogenesis. Certain miRNAs promote while others antagonize the hypoxic survival response. We found that expression of the mir-35 family is regulated by hypoxia in a HIF-1-independent manner and loss of mir-35-41 weakens hypoxic survival mechanisms in embryos. In addition, correct regulation of the RNA binding protein, SUP-26, a mir-35 family target, is needed for survival in chronic hypoxia. The identification of the full mRNA target repertoire of these miRNAs will reveal the miRNA-regulated network of hypoxic survival mechanisms in C. elegans.

The role of hypoxia-induced miR-210 in cancer progression

Prolonged hypoxia, the event of insufficient oxygen, is known to upregulate tumor development and growth by promoting the formation of a neoplastic environment. The recent discovery that a subset of cellular microRNAs (miRs) are upregulated during hypoxia, where they function to promote tumor development, highlights the importance of hypoxia-induced miRs as targets for continued investigation. miRs are short, non-coding transcripts involved in gene expression and regulation. Under hypoxic conditions, miR-210 becomes highly upregulated in response to hypoxia inducing factors (HIFs). HIF-1α drives miR-210’s overexpression and the resultant alteration of cellular processes, including cell cycle regulation, mitochondria function, apoptosis, angiogenesis and metastasis. Here we discuss hypoxia-induced dysregulation of miR-210 and the resultant changes in miR-210 protein targets that regulate cancer progression. Potential methods of targeting miR-210 as a therapeutic tool are also explored.

Disruptions in follicle cell functions in the ovaries of rhesus monkeys during summer

Oocytes isolated from female rhesus monkeys following standard ovarian stimulation protocols during the summer months displayed a reduced capacity to mature compared with stimulation during the normal breeding season. Because the gene expression profiles of oocyte-associated cumulus cells and mural granulosa cells (CCs and GCs) are indicative of altered oocyte quality and can provide insight into intrafollicular processes that may be disrupted during oogenesis, we performed array-based transcriptome comparisons of CCs and GCs from summer and normal breeding season stimulation cycles. Summer CCs and GCs both display deficiencies in expression of mRNAs related to cell proliferation, angiogenesis, and endocrine signaling, as well as reduced expression of glycogen phosphorylase. Additionally, CCs display deficiencies in expression of mRNAs related to stress response. These results provide the first insight into the specific molecular pathways and processes that are disrupted in the follicles of rhesus macaque females during the summer season. Some of the changes seen in summer GCs and CCs have been reported in humans and in other model mammalian species. This suggests that the seasonal effects seen in the rhesus monkey may help us to understand better the mechanisms that contribute to reduced oocyte quality and fertility in humans.

Diagnostic value of plasma miR-210 combined with serum tumor markers in pancreatic cancer

AIM: To evaluate the diagnostic value of the combination of plasma miR-210 with serum tumor markers in patients with pancreatic cancer.

METHODS: Sixty patients with pancreatic cancer, twenty patients with chronic pancreatitis, and ten normal people were included in the study. Total RNA was extracted from plasma samples for measurement of miR-210 levels using real-time PCR. Simultaneously, serum tumor markers carbohydrate antigen 199 (CA199), CA242 and carcino-embryonic antigen (CEA) were determined. The relationship between miR-210 levels and clinical characteristics of pancreatic cancer patients was analyzed. The diagnostic efficiency of combination of plasma miR-210 with serum tumor markers CA199, CA242, and CEA in pancreatic cancer patients was evaluated.

RESULTS: The relative abundance of plasma miR-210 was significantly higher in the pancreatic cancer group than in the chronic pancreatitis and normal groups (4.12 ± 4.51 vs 1.49 ± 3.94, -1.73 ± 4.82; P < 0.01 for both). Plasma miR-210 levels showed no significant correlation with CA199, CA242, CEA, tumor diameter, TNM stage or clinical stage in pancreatic cancer patients. Analysis using a binary logistic regression model showed that the diagnostic sensitivity and specificity of miR-210 alone were 96.7% and 50% for the pancreatic cancer group vs normal group, 95% and 25% for the pancreatic cancer group vs chronic pancreatitis group, and 86.7% and 40% for the pancreatic cancer group vs chronic pancreatitis and normal group. When plasma miR-210 was combined with serum tumor markers CA199, CA242, or CEA, the sensitivity and specificity in the three groups were 96.7% and 70%, 90% and 85%, 86.7% and 90%, respectively.

CONCLUSION: The combination of plasma miR-210 with serum tumor markers CA199, CA242 or CEA can improve diagnostic efficiency in patients with pancreatic cancer.

miR-210 is a prognostic marker in clear cell renal cell carcinoma

Accurate assessment of prognosis of clear cell renal cell carcinoma (ccRCC) is key in optimizing management plans to fit individual patient needs. miRNAs are short noncoding single-stranded RNAs that control the expression of target genes and may act as cancer biomarkers. We analyzed the expression of miR-210 in 276 cases of primary ccRCC and compared its expression in 40 pairs of adjacent normal and cancerous tissues. We assessed its expression in primary and metastatic tumors, in the common RCC subtypes, and the benign oncocytoma. The results were validated with an independent data set from The Cancer Genome Atlas. miR-210 was significantly overexpressed in ccRCC compared with normal kidney. miR-210(+) patients had a statistically higher chance of disease recurrence [hazard ratio (HR), 1.82; P = 0.018] and shorter overall survival (HR, 2.46; P = 0.014). In multivariate analysis, miR-210 lost its statistically significant association with shorter disease-free survival and overall survival after adjusting for tumor size and tumor, node, metastasis stage. Papillary RCC showed comparable miR-210 overexpression, whereas decreased up-regulation was seen in chromophobe RCC and oncocytoma. A number of predicted targets that might be involved in carcinogenesis and aggressive tumor behavior were identified. miR-210 is a potential therapeutic target and independent marker of poor prognosis of ccRCC.

Negative regulation of Hif1a expression and TH17 differentiation by the hypoxia-regulated microRNA miR-210

MicroRNA-210 (miR-210) is a signature microRNA of hypoxia. We found robust increase (>100-fold) of miR-210 abundance in activated T cells, especially in the T_H17 lineage. Hypoxia synergized with T cell receptor (TCR)–CD28 stimulation to accelerate and increase the magnitude of Mir210 expression. Mir210 was directly regulated by HIF-1α, a key regulator of T_H17 polarization. Surprisingly, Hif1a was identified as a miR-210-target, suggesting negative-feedback by miR-210 to inhibit HIF-1α protein expression. Deletion of Mir210 promoted T_H17 differentiation under conditions with limited oxygen. In experimental colitis, miR-210 reduced Hif1a transcript abundance, reduced the proportion of cells producing inflammatory cytokines and controlled disease severity. Our study identifies miR-210 as an important regulator of T cell differentiation in hypoxia, which can limit immunopathology.