Purinergic Receptors: Novel Targets for Cancer Immunotherapy

The ATP-dependent Pathways and Human Diseases

Adenosine triphosphate (ATP) is one of the most important molecules of life, present both inside the cells and extracellularly. It is an essential building block for nucleic acids biosynthesis and crucial intracellular energy storage. However, one of the most interesting functions of ATP is the role of a signaling molecule. Numerous studies indicate the involvement of ATP-dependent pathways in maintaining the proper functioning of individual tissues and organs. Herein, the latest data indicating the ATP function in the network of intra- and extracellular signaling pathways including purinergic signaling, MAP kinase pathway, mTOR and calcium signaling are collected. The main ATP-dependent processes maintaining the proper functioning of the nervous, cardiovascular and immune systems, as well as skin and bones, are summarized. The disturbances in the ATP amount, its cellular localization, or interaction with target elements may induce pathological changes in signaling pathways leading to the development of serious diseases. The impact of an ATP imbalance on the development of dangerous health dysfunctions such as neurodegeneration diseases, cardiovascular diseases (CVDs), diabetes mellitus, obesity, cancers and immune pathogenesis are discussed here.

Advances in Intracellular Calcium Signaling Reveal Untapped Targets for Cancer Therapy

Intracellular Ca2+ distribution is a tightly regulated process. Numerous Ca2+ chelating, storage, and transport mechanisms are required to maintain normal cellular physiology. Ca2+-binding proteins, mainly calmodulin and calbindins, sequester free intracellular Ca2+ ions and apportion or transport them to signaling hubs needing the cations. Ca2+ channels, ATP-driven pumps, and exchangers assist the binding proteins in transferring the ions to and from appropriate cellular compartments. Some, such as the endoplasmic reticulum, mitochondria, and lysosomes, act as Ca2+ repositories. Cellular Ca2+ homeostasis is inefficient without the active contribution of these organelles. Moreover, certain key cellular processes also rely on inter-organellar Ca2+ signaling. This review attempts to encapsulate the structure, function, and regulation of major intracellular Ca2+ buffers, sensors, channels, and signaling molecules before highlighting how cancer cells manipulate them to survive and thrive. The spotlight is then shifted to the slow pace of translating such research findings into anticancer therapeutics. We use the PubMed database to highlight current clinical studies that target intracellular Ca2+ signaling. Drug repurposing and improving the delivery of small molecule therapeutics are further discussed as promising strategies for speeding therapeutic development in this area.

Characteristics and the role of purinergic receptors in pathophysiology with focus on immune response

The nucleotide adenosine-5'-triphosphate (ATP) is mostly thought to be energy carrier, but evidence presented in multiple studies proves ATP involvement into variety of processes, due to its neuromodulatory capabilities. ATP and its metabolite-adenosine, bind to the purinergic receptors, which are divided into two types: adenosine binding P1 receptor and ADP/ATP binding P2 receptor. These receptors are expressed in different tissues and organs. Recent studies report their immunomodulatory characteristics, connected with varying immunological processes, such as immunological response or antigen presentation. Besides, they seem to play an important role in medical conditions such as bronchial asthma or variety of cancers. In this article, we would like to review recent discoveries on the field of purinergic receptors research focusing on their role in immunological system, and shed a new light upon the importance of these receptors in modern medicine development.