The path of GPR87: from a P2Y-like receptor to its role in cancer progression

GPR87 is a G protein-coupled seven-transmembrane receptor first described as an orphan receptor in 2001. Despite its high structural homology to several extracellular nucleotide-activated P2Y receptors and sharing conserved sequence motifs in transmembrane regions, identification of endogenous ligands from the class of nucleotides and their analogues has failed for GPR87. Although lysophosphatidic acid was proposed to be a natural ligand for this cell surface receptor, these data are preliminary and inconsistent, and IUPHAR is currently considering GPR87 as an orphan receptor. Thus, the endogenous ligands and physiological functions of GPR87 are still required to be determined and/or confirmed. The remarkably higher expression of GPR87 in human malignant tissues compared to the normal healthy ones clearly suggests that this receptor may be involved in the development and progression of cancerous neoplasms. Therefore, in this review article, the main focus is placed on the oncogenic role of GPR87 in various human malignancies, presenting it as a potential novel target site for therapeutic interventions using both humanized monoclonal antibodies and gene therapy but also selective antagonists which are still waiting for their identification. Furthermore, the importance of the expression of GPR87 as a predictive biomarker for evaluating the prognosis and overall survival of cancer patients is also highlighted.

Recommendation to Consume Plant Products for their Health Benefits may Take a Different Perspective with Global Warming

Abstract:

Over the past few decades, the multifaceted anticancer action of various plant-derived flavonoids has been demonstrated both in in vitro and in vivo preclinical experiments as well as in clinical trials and large-scale epidemiological studies. These secondary metabolites, synthesized in plants in response to different environmental stresses, can exert diverse biological activities in the human body after ingestion of plant-based foods. Flavonoids are indeed well-known for their antioxidant, anti-inflammatory, antiproliferative, proapoptotic, anti-migratory, antiinvasive, anti-metastatic, and anti-angiogenic properties, thereby preventing and slowing the development of different types of human cancers. Accordingly, more and more people all over the world have increased their everyday intake of fruits, vegetables, whole grains, and spices to get the benefits of flavonoids. In this commentary article, a critical view is presented on the possible gradual decrease in the health-promoting effects of edible and medicinal plant products related to changes in their flavonoid content and composition as a consequence of global warming. It is indeed generally accepted that biosynthesis and accumulation of certain flavonoids can be higher in plants cultivated in colder conditions, while a high temperature may even block the production of these agents. It only remains to be determined in the future as to what extent the lowering of flavonoids content in plant-based diets during global warming can contribute to continuously increasing worldwide incidence of new cancer cases, revealing the actual costs of human-induced environmental changes.

The low expression of matrix metalloproteinases: a key to longevity?

Over the past few decades, it has become clear that an excessive activity of matrix metalloproteinases (MMPs) can accelerate the progression and fatal outcomes of several serious age-related diseases, including atherosclerotic coronary heart disorders and various types of malignancies. These proteolytic enzymes mediate the degradation and remodeling of the extracellular matrix through cleaving its various components, thereby affecting many critical functions of surrounding cells and intercellular communication. Consequently, the low expression levels of MMPs can be important in the prevention and treatment of such chronic life-threatening pathologies, contributing to the better quality of life and longer life expectancy. In this review article, the pathogenic proteolytic roles of MMPs are examined in more detail, especially in the cases of heart attack and stroke as well as cancer invasion and metastasis, showing that these enzymes can be considered not only as diagnostic and prognostic biomarkers but also as important therapeutic targets in the fight against many age- and lifestyle-related serious disorders. The identification and development of suppressing agents with a selective activity towards specific MMPs have, however, still remained a complex and complicated challenge, in which natural plant-derived compounds are increasingly recognized as promising leads for the new-generation inhibitors.

Dual effect of nucleotides on P2Y receptors

The interaction of ADP, 2MeSADP, and ADPbetaS with the adenine nucleotide receptor P2Y1 in the hP2Y1-1321N1 cell line and of UDP with a receptor or receptors recognizing pyrimidine nucleotides in NG108-15 cells was studied over a wide range ofligand concentrations. Bell-shaped dose-response curves for stimulation of phosphoinositide hydrolysis were obtained in these cells. This dual behavior of the agonists studied was characterized by two dissociation constants, K(agon) and K(antag), which quantify the agonistic and antagonistic activity of these ligands and can be compared with the conventional EC50 and IC50 values, respectively. The data revealed a common pattern of agonistic and antagonistic behavior of nucleoside diphosphates and their derivatives at these two types of P2Y receptors, pointing to some similar properties of their nucleotide binding sites.