Making sense in antisense: therapeutic potential of noncoding RNAs in diabetes-induced vascular dysfunction

Therapeutic strategies targeting AMPK-dependent autophagy in cancer cells

Macroautophagy is a health-modifying process of engulfing misfolded or aggregated proteins or damaged organelles, coating these proteins or organelles into vesicles, fusion of vesicles with lysosomes to form autophagic lysosomes, and degradation of the encapsulated contents. It is also a self-rescue strategy in response to harsh environments and plays an essential role in cancer cells. AMP-activated protein kinase (AMPK) is the central pathway that regulates autophagy initiation and autophagosome formation by phosphorylating targets such as mTORC1 and unc-51 like activating kinase 1 (ULK1). AMPK is an evolutionarily conserved serine/threonine protein kinase that acts as an energy sensor in cells and regulates various metabolic processes, including those involved in cancer. The regulatory network of AMPK is complicated and can be regulated by multiple upstream factors, such as LKB1, AKT, PPAR, SIRT1, or noncoding RNAs. Currently, AMPK is being investigated as a novel target for anticancer therapies based on its role in macroautophagy regulation. Herein, we review the effects of AMPK-dependent autophagy on tumor cell survival and treatment strategies targeting AMPK.

Unveiling the druggable RNA targets and small molecule therapeutics

The increasing appreciation for the crucial roles of RNAs in infectious and non-infectious human diseases makes them attractive therapeutic targets. Coding and non-coding RNAs frequently fold into complex conformations which, if effectively targeted, offer opportunities to therapeutically modulate numerous cellular processes, including those linked to undruggable protein targets. Despite the considerable skepticism as to whether RNAs can be targeted with small molecule therapeutics, overwhelming evidence suggests the challenges we are currently facing are not outside the realm of possibility. In this review, we highlight the most recent advances in molecular techniques that have sparked a revolution in understanding the RNA structure-to-function relationship. We bring attention to the application of these modern techniques to identify druggable RNA targets and to assess small molecule binding specificity. Finally, we discuss novel screening methodologies that support RNA drug discovery and present examples of therapeutically valuable RNA targets.

Associations between miR-661, miR-1202, lncRNA-HOTAIR, lncRNA-GAS5 and MMP9 in differentiated M2-macrophages of patients with varicose veins

BACKGROUND

The venous hypertension is suggested as the main cause of varicose disease. Some mediators and growth factors are known as the responsible of cellular events for the progression of venous perturbations. The aim of this study was to investigate non-coding (nc) RNA and MMP9 expression levels in macrophages differentiated from monocytes of patients with varicose veins.

METHODS

The monocytes were isolated from the whole blood samples by RosetteSep kit and were differentiated to macrophages M2 using M-CSF factor. The based on ncRNA-gene network, lncRNA-GAS5, lncRNA-HOTAIR, miRNA-661, miRNA-1202, and MMP9 were selected. The gene expression levels were measured by RT-qPCR technique.

RESULTS

Data showed that the MMP9 gene expression increased (P=0.003) while the GAS5, miRNA-661, and miRNA-1202 expression levels reduced significantly in the differentiated macrophages of patients (P=0.035, P=0.009, and P=0.015, respectively). Furthermore, the MMP9 gene expression levels were conversely related to the GAS5, HOTAIR, miRNA-661 and miRNA-1202 expression levels.

CONCLUSIONS

The results suggested that the lncRNA-GAS5, miRNA-661, miRNA-1202 and MMP9 are involved in varicose disease.

Endothelial cell regulation through epigenetic mechanisms: Depicting parallels and its clinical application within an intra-islet microenvironment

The intra-islet endothelial cells (ECs), the building blocks of islet microvasculature, govern a number of cellular and pathophysiological processes associated with the pancreatic tissue. These cells are key to the angiogenic process and essential for islet revascularization after transplantation. Understanding fundamental mechanisms by which ECs regulate the angiogenic process is important as these cells maintain and regulate the intra-islet environment facilitated by a complex signaling crosstalk with the surrounding endocrine cells. In recent years, many studies have demonstrated the impact of epigenetic regulation on islet cell development and function. This review will present an overview of the reports involving endothelial epigenetic mechanisms particularly focusing on histone modifications which have been identified to play a critical role in governing EC functions by modifying the chromatin structure. A better understanding of epigenetic mechanisms by which these cells regulate gene expression and function to orchestrate cellular physiology and pathology is likely to offer improved insights on the functioning and regulation of an intra-islet endothelial microvascular environment.

Systemic effects of AGEs in ER stress induction in vivo

Emerging evidence indicates that accumulation of advanced glycation end products (AGEs) in human tissues may contribute to cell injury, inflammation and apoptosis through induction of endoplasmic reticulum (ER) stress. Human metabolism relies on ER homeostasis for the coordinated response of all metabolic organs by controlling the synthesis and catabolism of various nutrients. In vitro studies have demonstrated AGE-induced enhancement of unfolded protein response (UPR) in different cell types including endothelial, neuronal, pancreatic cells and podocytes, suggesting this crosstalk as an underlying pathological mechanism that contributes to metabolic diseases. In this minireview, we describe in vivo studies undertaken by our group and others that demonstrate the diverse systemic effects of AGEs in ER stress induction in major metabolic tissues such as brain, kidney, liver and pancreas of normal mice. Administration of high-AGEs content diet to normal mice for the period of 4 weeks upergulates the mRNA and protein levels of ER chaperone Bip (GRP78) indicative of UPR initiation in all major metabolic organs and induces activation of the pivotal transcription factor XBP1 that regulates glucose and lipid metabolism. Furthermore, animals with genetic ablation of UPR-activated transcription factor C/EBP homologous protein CHOP allocated in high-AGEs diet, exhibited relative resistance to UPR induction (BiP levels) and XBP1 activation in major metabolic organs. Since CHOP presents a critical mediator that links accumulation and aggregation of unfolded proteins with induction of oxidative stress and ER stress-related apoptosis, it is revealed as an important molecular target for the management of metabolic diseases.

Epigenetic regulation of endothelial-cell-mediated vascular repair

Maintenance of vascular integrity is essential for the prevention of vascular disease and for recovery following cardiovascular, cerebrovascular and peripheral vascular events including limb ischemia, heart attack and stroke. Endothelial stem/progenitor cells have recently gained considerable interest due to their potential use in stem cell therapies to mediate revascularization after ischemic injury. Therefore, there is an urgent need to understand fundamental mechanisms regulating vascular repair in specific cell types to develop new beneficial therapeutic interventions. In this review, we highlight recent studies demonstrating that epigenetic mechanisms (including post-translational modifications of DNA and histones as well as non-coding RNA-mediated processes) play essential roles in the regulation of endothelial stem/progenitor cell functions through modifying chromatin structure. Furthermore, we discuss the potential of using small molecules that modulate the activities of epigenetic enzymes to enhance the vascular repair function of endothelial cells and offer insight on potential strategies that may accelerate clinical applications.

A long non-coding RNA, GAS5, plays a critical role in the regulation of miR-21 during osteoarthritis

Growth Arrest-Specific 5 (GAS5) is known to negatively regulate cell survival and is aberrantly expressed in several cancers. The influence of GAS5 on osteoarthritis (OA) has not been determined. To address this, articular chondrocytes were isolated from relatively normal (Non-OA) and clear OA regions (OA) of cartilage in total knee replacement (TKR) patients and biopsied normal cartilage. We found that GAS5 was up-regulated in OA chondrocytes compared with Non-OA and normal chondrocytes. The over-expression of GAS5 increased the expression levels of several MMPs, such as MMP-2, MMP-3, MMP-9, MMP-13, and ADAMTS-4; stimulated apoptosis; and suppressed autophagic responses. Furthermore, we subsequently identified miR-21 as a regulator of GAS5 during OA pathogenesis. The expression level of miR-21 was significantly reduced in OA patients, and the ectopic expression of GAS5 is capable of suppressing miR-21 induction. Consistent with GAS5 experiments, the introduction of miR-21 stimulated the apoptosis of chondrocytes and inhibited the expression levels of autophagic complexes, including LC-3B. In vivo, we found that the introduction of miR-21 into the cartilage of OA mice significantly stimulated cartilage destruction. Together, these results show that GAS5 contributes to the pathogenesis of OA by acting as a negative regulator of miR-21 and thereby regulating cell survival.

Resistin: insulin resistance to malignancy

Adipose tissue is recognized as an endocrine organ that secretes bioactive substances known as adipokines. Excess adipose tissue and adipose tissue dysfunction lead to dysregulated adipokine production that can contribute to the development of obesity-related co-morbidities. Among the various adipokines, resistin, which was initially considered as a determinant of the emergence of insulin resistance in obesity, has appeared as an important link between obesity and inflammatory processes. Several experimental and clinical studies have suggested an association between increased resistin levels and severe conditions associated with obesity such as cardiovascular disease and malignancies. In this review, we present the growing body of evidence that human resistin is an inflammatory biomarker and potential mediator of obesity-associated diseases. A common pathway seems to involve the combined alteration of immune and inflammatory processes that favor metabolic disturbances, atherosclerosis and carcinogenesis. The mode of action and the signaling pathways utilized by resistin in its interactions with target cells could involve oxidative and nitrosative stress. Therefore, resistin could function as a key molecule in the complications of obesity development and could potentially be used as a diagnostic and prognostic marker.