MicroRNAs and liver cancer associated with iron overload:Therapeutic targets unravelled

Primary liver cancer is a global disease that is on the increase.Hepatocellular carcinoma(HCC)accounts for most primary liver cancers and has a notably low survival rate,largely attributable to late diagnosis,resistance to treatment,tumour recurrence and metastasis.MicroRNAs(miRNAs/miRs)are regulatory RNAs that modulate protein synthesis.miRNAs are involved in several biological and pathological processes including the development and progression of HCC.Given the poor outcomes with current HCC treatments,miRNAs represent an important new target for therapeutic intervention.Several studies have demonstrated their role in HCC development and progression.While many risk factors underlie the development of HCC,one process commonly altered is iron homeostasis.Iron overload occurs in several liver diseases associated with the development of HCC including Hepatitis C infection and the importance of miRNAs in iron homeostasis and hepatic iron overload is well characterised.Aberrant miRNA expression in hepatic fibrosis and injury response have been reported,as have dysregulated miRNA expression patterns affecting cell cycle progression,evasion of apoptosis,invasion and metastasis.In2009,miR-26a delivery was shown to prevent HCC progression,highlighting its therapeutic potential.Several studies have since investigated the clinical potential of other miRNAs with one drug,Miravirsen,currently in phaseⅡclinical trials.miRNAs also have potential as biomarkers for the diagnosis of HCC and to evaluate treatment efficacy.Ongoing studies and clinical trials suggest miRNA-based treatments and diagnostic methods will have novel clinical applications for HCC in the coming years,yielding improved HCC survival rates and patient outcomes.

Z α-1 antitrypsin deficiency and the endoplasmic reticulum stress response

The serine proteinase inhibitor α-1 antitrypsin(AAT) is produced principally by the liver at the rate of 2 g/d.It is secreted into the circulation and provides an antiprotease protective screen throughout the body but most importantly in the lung,where it can neutralise the activity of the serine protease neutrophil elastase.Mutations leading to def iciency in AAT are associated with liver and lung disease.The most notable is the Z AAT mutation,which encodes a misfolded variant of the AAT protein in which the glutamic acid at position 342 is replaced by a lysine.More than 95% of all individuals with AAT def iciency carry at least one Z allele.ZAAT protein is not secreted effectively and accumulates intracellularly in the endoplasmic reticulum(ER) of hepatocytes and other AAT-producing cells.This results in a loss of function associated with decreased circulating and intrapulmonary levels of AAT.However,the misfolded protein acquires a toxic gain of function that impacts on the ER.A major function of the ER is to ensure correct protein folding.ZAAT interferes with this function and promotes ER stress responses and inflammation.Here the signalling pathways activated during ER stress in response to accumulation of ZAAT are described and therapeutic strategies that can potentially relieve ER stress are discussed.

Inhaled hypertonic saline for cystic fibrosis: Reviewing the potential evidence for modulation of neutrophil signalling and function

Cystic fibrosis(CF) is a multisystem disorder with significantly shortened life expectancy. The major cause of mortality and morbidity is lung disease with increasing pulmonary exacerbations and decline in lung function predicting significantly poorer outcomes. The pathogenesis of lung disease in CF is characterised in part by decreased airway surface liquid volume and subsequent failure of normal mucociliary clearance. This leads to accumulation of viscous mucus in the CF airway, providing an ideal environment for bacterial pathogens to grow and colonise, propagating airway inflammation in CF. The use of nebulised hypertonic saline(HTS) treatments has been shown to improve mucus clearance in CF and impact positively upon exacerbations, quality of life, and lung function. Several mechanisms of HTS likely improve outcome, resulting in clinically relevant enhancement in disease parameters related to increase in mucociliary clearance. There is increasing evidence to suggest that HTS is also beneficial through its anti-inflammatory properties and its ability to reduce bacterial activity and biofilm formation. This review will first describe the use of HTS in treatment of CF focusing on its efficacy and tolerability. The emphasis will then change to the potential benefits of aerosolized HTS for the attenuation of receptor mediated neutrophil functions, including down-regulation of oxidative burst activity, adhesion molecule expression, and the suppression of neutrophil degranulation of proteolytic enzymes.