NM23 downregulation and lysophosphatidic acid receptor EDG2/lpa1 upregulation during myeloid differentiation of human leukemia cells

Revisiting the role of lysophosphatidic acid in stem cell biology

Stem cells possess unique biological characteristics such as the ability to self-renew and to undergo multilineage differentiation into specialized cells. Whereas embryonic stem cells (ESC) can differentiate into all cell types of the body, somatic stem cells (SSC) are a population of stem cells located in distinct niches throughout the body that differentiate into the specific cell types of the tissue in which they reside in. SSC function mainly to restore cells as part of normal tissue homeostasis or to replenish cells that are damaged due to injury. Cancer stem-like cells (CSC) are said to be analogous to SSC in this manner where tumor growth and progression as well as metastasis are fueled by a small population of CSC that reside within the corresponding tumor. Moreover, emerging evidence indicates that CSC are inherently resistant to chemo- and radiotherapy that are often the cause of cancer relapse. Hence, major research efforts have been directed at identifying CSC populations in different cancer types and understanding their biology. Many factors are thought to regulate and maintain cell stemness, including bioactive lysophospholipids such as lysophosphatidic acid (LPA). In this review, we discuss some of the newly discovered functions of LPA not only in the regulation of CSC but also normal SSC, the similarities in these regulatory functions, and how these discoveries can pave way to the development of novel therapies in cancer and regenerative medicine.

NME/NM23/NDPK and Histidine Phosphorylation

The NME (Non-metastatic) family members, also known as NDPKs (nucleoside diphosphate kinases), were originally identified and studied for their nucleoside diphosphate kinase activities. This family of kinases is extremely well conserved through evolution, being found in prokaryotes and eukaryotes, but also diverges enough to create a range of complexity, with homologous members having distinct functions in cells. In addition to nucleoside diphosphate kinase activity, some family members are reported to possess protein-histidine kinase activity, which, because of the lability of phosphohistidine, has been difficult to study due to the experimental challenges and lack of molecular tools. However, over the past few years, new methods to investigate this unstable modification and histidine kinase activity have been reported and scientific interest in this area is growing rapidly. This review presents a global overview of our current knowledge of the NME family and histidine phosphorylation, highlighting the underappreciated protein-histidine kinase activity of NME family members, specifically in human cells. In parallel, information about the structural and functional aspects of the NME family, and the knowns and unknowns of histidine kinase involvement in cell signaling are summarized.

Ellagic acid and human cancers: a systems pharmacology and docking study to identify principal hub genes and main mechanisms of action

Research on anticancer properties of natural compounds, as effective materials that are available while causing minimal side effects, is growing. Ellagic acid (EA) is a well-known polyphenolic compound, which has been found in both free and complex modes in several medicinal plants such as pomegranate, walnut, and berries. Although many articles have reported anticancer properties for this compound, its mechanism of action has not been fully elucidated. In this study, we used several online and offline bioinformatics tools and databases to identify the mechanism of action of EA on various types of human malignancies including bladder, blood, breast, cervical, colorectal, liver, pancreas, and prostate cancers. In this context, after identifying and extracting EA-affected human genes/proteins that have been reported in various references, we built the related gene networks and determined functional hub genes. In addition, docking was performed to recognize target proteins that react directly with EA and are in fact most affected by this compound. Our findings revealed that EA exerts its anticancer effects by influencing specific hub genes in various types of cancers. Moreover, different cellular signaling pathways are affected by this natural compound. Generally, it turned out that EA probably exerts most of its anticancer activities, through induction of apoptosis, as well as P53 and WNT signaling pathways, and also by affecting the expression of several hub genes such as CDKN1A, CDK4, CDK2, CDK6, TP53, JUN, CCNA2, MAPK14, CDK1, and CCNB1 and especially interactions with some related proteins including P53, CDK6, and MAPK14.

Lysophosphatidic Acid and Hematopoiesis: From Microenvironmental Effects to Intracellular Signaling

Vertebrate hematopoiesis is a complex physiological process that is tightly regulated by intracellular signaling and extracellular microenvironment. In recent decades, breakthroughs in lineage-tracing technologies and lipidomics have revealed the existence of numerous lipid molecules in hematopoietic microenvironment. Lysophosphatidic acid (LPA), a bioactive phospholipid molecule, is one of the identified lipids that participates in hematopoiesis. LPA exhibits various physiological functions through activation of G-protein-coupled receptors. The functions of these LPARs have been widely studied in stem cells, while the roles of LPARs in hematopoietic stem cells have rarely been examined. Nonetheless, mounting evidence supports the importance of the LPA-LPAR axis in hematopoiesis. In this article, we have reviewed regulation of hematopoiesis in general and focused on the microenvironmental and intracellular effects of the LPA in hematopoiesis. Discoveries in these areas may be beneficial to our understanding of blood-related disorders, especially in the context of prevention and therapy for anemia.

The Function of NM23-H1/NME1 and Its Homologs in Major Processes Linked to Metastasis

Metastasis suppressor genes (MSGs) inhibit different biological processes during metastatic progression without globally influencing development of the primary tumor. The first MSG, NM23 (non-metastatic clone 23, isoform H1) or now called NME1 (stands for non-metastatic) was identified some decades ago. Since then, ten human NM23 paralogs forming two groups have been discovered. Group I NM23 genes encode enzymes with evolutionarily highly conserved nucleoside diphosphate kinase (NDPK) activity. In this review we summarize how results from NDPKs in model organisms converged on human NM23 studies. Next, we examine the role of NM23-H1 and its homologs within the metastatic cascade, e.g. cell migration and invasion, proliferation and apoptosis. NM23-H1 homologs are well known inhibitors of cell migration. Drosophila studies revealed that AWD, the fly counterpart of NM23-H1 is a negative regulator of cell motility by modulating endocytosis of chemotactic receptors on the surface of migrating cells in cooperation with Shibire/Dynamin; this mechanism has been recently confirmed by human studies. NM23-H1 inhibits proliferation of tumor cells by phosphorylating the MAPK scaffold, kinase suppressor of Ras (KSR), resulting in suppression of MAPK signalling. This mechanism was also observed with the C. elegans homolog, NDK-1, albeit with an inverse effect on MAPK activation. Both NM23-H1 and NDK-1 promote apoptotic cell death. In addition, NDK-1, NM23-H1 and their mouse counterpart NM23-M1 were shown to promote phagocytosis in an evolutionarily conserved manner. In summary, inhibition of cell migration and proliferation, alongside actions in apoptosis and phagocytosis are all mechanisms through which NM23-H1 acts against metastatic progression.

High Survivin and Low Zinc Finger of the Cerebellum 1 Expression Indicates Poor Prognosis in Triple-negative Breast Carcinoma

Purpose

Triple-negative breast carcinoma (TNBC) is accompanied with high risk of metastasis and recurrence. The present study aimed to explore the clinicopathological and prognostic roles of putative tumor-related genes in patients with TNBC.

Methods

Thirty pairs of frozen-thawed tumors were used to select reliable indicators via real-time quantitative polymerase chain reaction (RT-qPCR). Then, 150 pathology specimens were used to evaluate the expression of proteins in TNBC through immunohistochemistry. In addition, Kaplan-Meier curves and Cox regression analysis were also performed to analyze the overall survival and disease-free survival.

Results

RT-qPCR results indicated that among all the proteins analyzed using fresh-frozen TNBC samples, the expression levels of only Survivin and zinc finger of the cerebellum 1 (ZIC1) were obviously different from those in the corresponding normal tissues. Survivin and ZIC1 expression had opposite effects on the clinicopathological diagnosis and prognostic assessment in TNBC patients. Further, there was a negative correlation between Survivin and ZIC1 expression. In addition, the “Survivin-positive ZIC1-negative group” was associated with histologic grade, lymph node metastasis, and TNM staging (p < 0.001) and this was also an independent factor for evaluating the prognosis of TNBC in patients.

Conclusion

In summary, the expression levels of Survivin and ZIC1 in TNBC are different from those in normal tissues and are negatively correlated mutually. The combined detection of Survivin and ZIC1 expression levels could allow better comprehensive diagnosis and prognostic evaluation for TNBC patients.