Current Drug Targets (v.17, #8)

Meet Our Editorial Board Member: by Mark J. Walker (851-851).

Editorial (Thematic Issue: AMPK: New Frontiers in Human Diseases) by Mario D. Cordero, Benoit Viollet (852-852).

Targeting AMPK Signaling Pathway to Overcome Drug Resistance for Cancer Therapy by Zhiyu Wang, Pengxi Liu, Qianjun Chen, Shigui Deng, Xiaoyan Liu, Honglin Situ, Shaowen Zhong, Swei Hann, Yi Lin (853-864).
Mulitdrug resistance (MDR) is one of critical factorslimiting the efficacy of cancer chemoor radiotherapy. Emerging evidence has indicated that MDR is a complex process regulated by multiple factors, among which stress response molecules are considered as central players. AMP-activated protein kinase (AMPK) is a major regulator balancing energy supply and ultimately protects cells from harmful stresses via coordinating multiple metabolic pathways Notably, AMPK activation was recently shown to mediate the metabolism reprogramming in drug resistant cancer cells including promoting Warburg effects and mitochondrial biogenesis. Furthermore, AMPK activity has also been shown to regulate the self-renewal ability of cancer stem cells that are often refractory to chemotherapy. In addition, AMPK phosphorylation was critical in mediating autophagy induction, a process demonstrated to be effective in chemosensitivity modulation via degrading cellular components to satisfy nutrients requirement under stressful condition. Meanwhile, drug discovery targeting AMPK has been developed to validate the pathological significance of AMPK in cancer prevention and treatment. Although conflicting evidence focusing on the AMPK modulation for cancer treatment is still remained, this might be attributed to differences in AMPK isotypes in specific tissues, off-targets effects, the degree and duration of drug administration and experimental setting of stress conditions. This review will focus on AMPK mediated resistance to cancer therapy and discuss its potential therapeutic implication and targeting drug development.

AMPK as a New Attractive Therapeutic Target for Disease Prevention: The Role of Dietary Compounds AMPK and Disease Prevention by Massimiliano Gasparrini, Francesca Giampieri, Josè M. Alvarez Suarez, Luca Mazzoni, Tamara Y. Forbes Hernandez, Josè L. Quiles, Pedro Bullon, Maurizio Battino (865-889).
AMPK is a serine/threonine protein kinase that has the function of maintaining the balance between ATP production and consumption in most eukaryotic cells. It plays a relevant role in regulating cellular metabolism, preserving cellular energy homeostasis, and is involved in many other cellular processes as well as metabolic ones, including cell cycle regulation and endothelial and vascular relaxation. Recently, the effects of naturally occurring compounds able to prevent and treat diseases through AMPK activation have attracted the attention of many researchers. Among such compounds, flavonoids found in natural sources, like quercetin, genistein, epigallocatechins, resveratrol, have been proposed as AMPK activators. This review summarizes and updates the most recent findings concerning the mechanisms through which different dietary compounds, from plant foods, affect the AMPK pathway in healthy and pathological in vitro and in vivo models, paying particular attention to molecular mechanisms involved in diabetes, obesity, metabolic syndrome, cardiovascular disease and cancer.

AMPK in Neurodegenerative Diseases: Implications and Therapeutic Perspectives by Claudia Marinangeli, Sébastien Didier, Valérie Vingtdeux (890-907).
Maintaining proper energy levels in brain neurons is crucial for many cerebral functions such as synaptic transmission, vesicle recycling and axonal transport. AMP-activated protein kinase (AMPK) is the main energy sensor of all living cells. Beside its role as a crucial whole-body energy sensor in hypothalamic neurons, AMPK is also expressed in neurons throughout the brain where it might play additional fundamental roles. For instance, AMPK might be involved in brain development, neuronal polarization and neuronal activity. In addition, recent evidences suggest that AMPK deregulation might participate in neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis and ischemic stroke. Therefore, AMPK is emerging as a potential therapeutic target for these neurodegenerative diseases. Here, we will review the recent literature regarding the physiological and pathological role of AMPK in the brain and discuss the resulting potential therapeutic implications.

Pathological pain is an enormous medical problem that places a significant burden on patients and can result from an injury that has long since healed or be due to an unidentifiable cause. Although treatments exist, they often either lack efficacy or have intolerable side effects. More importantly, they do not reverse the changes in the nervous system mediating pathological pain, and thus symptoms often return when therapies are discontinued. Consequently, novel therapies are urgently needed that have both improved efficacy and disease-modifying properties. Here we highlight an emerging target for novel pain therapies, adenosine monophosphate-activated protein kinase (AMPK). AMPK is capable of regulating a variety of cellular processes including protein translation, activity of other kinases, and mitochondrial metabolism, many of which are thought to contribute to pathological pain. Consistent with these properties, preclinical studies show positive, and in some cases disease-modifying effects of either pharmacological activation or genetic regulation of AMPK in models of nerve injury, chemotherapy-induced peripheral neuropathy (CIPN), postsurgical pain, inflammatory pain, and diabetic neuropathy. Given the AMPK-activating ability of metformin, a widely prescribed and well-tolerated drug, these preclinical studies provide a strong rationale for both retrospective and prospective human pain trials with this drug. They also argue for the development of novel AMPK activators, whether orthosteric, allosteric, or modulators of events upstream of the kinase. Together, this review will present the case for AMPK as a novel therapeutic target for pain and will discuss future challenges in the path toward development of AMPK-based pain therapeutics.

AMPK As A Target in Rare Diseases by David Cotán, Marina Villanueva Paz, Elizabet Alcocer-Gómez, Juan Garrido-Maraver, Manuel Oropesa-Ávila, Mario de la Mata, Ana Delgado Pavón, Isabel de Lavera, Fernando Galán, Patricia Ybot-González, José A. Sánchez-Alcázar (921-931).
The AMP-activated protein kinase (AMPK) has emerged as an important sensor of signals that control cellular energy balance in all eukaryotes. AMPK is also involved in fatty acid oxidation, glucose transport, antioxidant defense, mitochondrial biogenesis and the modulation of inflammatory processes. The numerous roles of AMPK in cell physiological and pathological states justified the notable increase in the number of publications in previous years, with almost 1500 scientific articles relative to this kinase in 2014. Due to its role in maintaining energy balance, a dysfunction in AMPK signalling pathway may result in perturbations at the systemic level that contribute to the development of many disease conditions. Among them, more than 7000 poorly-known rare diseases are particularly of social and scientific interest because they are usually chronically debilitating or even lifethreatening and lack effective and safe treatment. Several authors have demonstrated AMPK alterations and the beneficial effect of treatments with drugs regulating AMPK activity in some of these low prevalence pathologies. Among these rare diseases in which AMPK can play an important pathological role are mitochondrial disorders, muscular dystrophies, cardiovascular diseases, neurodegenerative pathologies, or even some types of cancer for the importance of AMPK as a suppressor of cell proliferation. This review focuses on current knowledge about the pathophysiological roles of AMPK and future approaches as therapeutic targeting in rare diseases.

AMPK Function in Aging Process by Rocío Ruiz, Eva María Pérez-Villegas, Ángel Manuel Carrión (932-941).
Aging involves the progressive deterioration of physiological functions, diminishing the individual's capacity for survival. Indeed, aging is the main risk factor for cancer, diabetes, cardiovascular disorders and neurodegenerative diseases. The discovery that the rate of aging is controlled by conserved genetic and biochemical pathways represented an unprecedented advance in aging research. The AMPK protein is a metabolic sensor that acts as a qualified cellular housekeeper, as well as controlling energy homeostasis and resistance to stress. Thus, the correct regulation of this factor enhances health and survival. In this manuscript we will review the molecular pathways regulated by AMPK that are related to the aging process, paying special attention to mitochondrial dysfunction, metabolic deregulation, cell senescence and autophagy.

AMP-activated Protein Kinase As a Target For Pathogens: Friends Or Foes? by Diana Moreira, Ricardo Silvestre, Anabela Cordeiro-da-Silva, Jérôme Estaquier, Marc Foretz, Benoit Viollet (942-953).
Intracellular pathogens are known to manipulate host cell regulatory pathways to establish an optimal environment for their growth and survival. Pathogens employ active mechanisms to hijack host cell metabolism and acquire existing nutrient and energy store. The role of the cellular energy sensor AMP-activated protein kinase (AMPK) in the regulation of cellular energy homeostasis is well documented. Here, we highlight recent advances showing the importance of AMPK signaling in pathogen-host interactions. Pathogens interact with AMPK by a variety of mechanisms aimed at reprogramming host cell metabolism to their own benefit. Stimulation of AMPK activity provides an efficient process to rapidly adapt pathogen metabolism to the major nutritional changes often encountered during the different phases of infection. However, inhibition of AMPK is also used by pathogens to manipulate innate host response, indicating that AMPK appears relevant to restriction of pathogen infection. We also document the effects of pharmacological AMPK modulators on pathogen proliferation and survival. This review illustrates intricate pathogen-AMPK interactions that may be exploited to the development of novel anti-pathogen therapies.

Targeted Thromboelastographic (TEG) Blood Component and Pharmacologic Hemostatic Therapy in Traumatic and Acquired Coagulopathy by Mark Walsh, Stephanie Fritz, Daniel Hake, Michael Son, Sarah Greve, Manar Jbara, Swetha Chitta, Braxton Fritz, Adam Miller, Mary K Bader, Jonathon McCollester, Sophia Binz, Alyson Liew-Spilger, Scott Thomas, Anton Crepinsek, Faisal Shariff, Victoria Ploplis, Francis J. Castellino (954-970).
Trauma-induced coagulopathy (TIC) is a recently described condition which traditionally has been diagnosed by the common coagulation tests (CCTs) such as prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and fibrinogen levels. The varying sensitivity and specificity of these CCTs have led trauma coagulation researchers and clinicians to use Viscoelastic Tests (VET) such as Thromboelastography (TEG) to provide Targeted Thromboelastographic Hemostatic and Adjunctive Therapy (TTHAT) in a goal directed fashion to those trauma patients in need of hemostatic resuscitation. This review describes the utility of VETs, in particular, TEG, to provide TTHAT in trauma and acquired non-trauma-induced coagulopathy.