Effect of ATRA and ATO on the expression of tissue factor in NB4 acute promyelocytic leukemia cells and regulatory function of the inflammatory cytokines TNF and IL-1β

[Regulatory Effect of All-Trans Retinoic Acid on the Expression of IL-1β in Macrophages and the Mechanisms Involved]

Objective

To investigate the regulatory effect of all-trans retinoic acid (ATRA) on the expression interleukin-1β (IL-1β) in macrophages and the mechanisms involved.

Methods

Macrophages were treated with 1 μmol/L ATRA for 24 h before RNA-Sequence. Differentially expressed genes (DEGs) were screened out and analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, gene ontology (GO) functional analysis, and protein-protein interaction networks (PPI) analysis. After treatment with different doses of ATRA for 24 h, the expression of IL-1β was examined with qRT-PCR and Western blot. The activation of NF-κB signaling and caspase-1 was observed by Western blot and immunofluorescence staining.

Results

Compared with the blank control group, a total of 71 DEGs of macrophages were upregulated in the ATRA treatment group. KEGG analysis showed that the up-regulated DEGs were involved in IL-17 signaling pathway, tumor necrosis factor (TNF) signaling pathway, etc. GO analysis indicated that the up-regulated DEGs were involved in the biological processes of the production of IL-1β, response to lipopolysaccharide, etc. PPI analysis revealed that inflammatory cytokines, adhesion molecules, and chemokines were the key genes that ATRA acted on. In vitro experiments showed that ATRA promoted IL-1β expression in macrophages in a concentration-dependent manner. The expression of p-NF-κB, NF-κB, and caspase-1 were significantly increased by ATRA compared with those of the control group ( P<0.05), and p-NF-κB translocated to the cell nucleus in the ATRA group.

Conclusion

ATRA may promote the expression of IL-1β by activating NF-κB signaling and caspase-1 in macrophages, this study may provide evidence for the immune regulatory function of ATRA on macrophages.

Advances in the management of coagulopathy in acute promyelocytic leukemia

Since the introduction of all-trans retinoic acid and, more recently, arsenic trioxide into the therapy of acute promyelocytic leukemia (APL), significant improvements in patient outcomes have been achieved, and this disease has become the most curable subtype of acute myeloid leukemia. However, while primary leukemia resistance has virtually disappeared, a sizable fraction of APL patients still die before or during induction therapy. Hemorrhagic death still remains the major problem during this early phase of treatment and, to a lesser extent, deaths due to infection, differentiation syndrome and other causes. Patients with APL typically present with a range of laboratory abnormalities consistent with the diagnosis of disseminated intravascular coagulation and hyperfibrinolysis. This APL-associated coagulopathy, as a result of a dysregulation of the hemostatic system due to the imbalance between procoagulant, anticoagulant and profibrinolytic mechanisms, may show a variety of clinical manifestations, ranging from minimal bleeding or localized thrombosis to lethal or life-threatening hemorrhages or thrombotic events that sometimes occur concomitantly. Hemorrhagic events are the most common cause of death associated with APL coagulopathy, but thrombosis, a less recognized and probably underestimated life-threatening manifestation of the thrombo-hemorrhagic syndrome, is also a non-negligible cause of morbidity and mortality in patients with APL. In this article, we aim to discuss recent advances in the knowledge of pathogenesis, predictors of thrombo-hemorrhagic events, management of coagulopathy associated with APL and the controversial issues that still persist.

Mechanistic effects of arsenic trioxide on acute promyelocytic leukemia and other types of leukemias

Acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia characterized with a translocation between promyelocytic leukemia gene (PML) on chromosome 15 and retinoic acid receptor alpha gene (RARα) on chromosome 17. Transcription of this fusion gene results in PML/RARα fusion protein blocking expression of critical genes involved in differentiation of myeloid cells through interaction with RAR element. PML/RARα fusion protein prevents normal function of PML and RARα as well as inhibiting apoptosis. Arsenic trioxide (ATO) is an important agent for the treatment of relapsed and newly diagnosed APL. ATO induces apoptosis, autophagy, and partial cellular differentiation as well as inhibiting cell growth and angiogenesis. Recognition of signaling pathways and molecular mechanisms induced by ATO can be effective for discovering novel treatment strategies to target leukemia cells. Also, it can be developed for the treatment of a variety of cancer cells. This review provides a perspective on anticancerous effects of ATO on APL and leukemia cells.

A Novel Aurora Kinase Inhibitor Attenuates Leukemic Cell Proliferation Induced by Mesenchymal Stem Cells

Acute myeloid leukemia (AML) mesenchymal stem cells (MSCs) play an essential role in protecting leukemic cells from chemotherapeutic agents through activating a wide range of adhesion molecules and cytokines. Thus, more attention should be paid to attenuate the protection of leukemic cells by MSCs. By examining the gene expression files of MSCs from healthy donors and AML patients through high-throughput microarrays, we found that interleukin (IL)-6 was an important cytokine secreted by AML MSCs to protect leukemic cells, contributing to disease progression. Strikingly, Aurora A (AURKA) was activated by IL-6, offering a new target to interfere with leukemia. Importantly, a novel AURKA inhibitor, PW21, showed excellent AURKA kinase inhibitory activities and attenuated the interaction of leukemic cells and the microenvironment. PW21 inhibited MSC-induced cell proliferation, colony formation, and migration, and it induced cell apoptosis. Mechanically, PW21 could inhibit IL-6 secreted by MSCs. Moreover, we found that PW21 displayed a strong anti-leukemia effect on non-obese diabetic (NOD)-severe combined immunodeficiency (SCID) and murine MLL-AF9 leukemic models. PW21 significantly prolonged the survival of leukemic mice and eliminated the leukemic progenitor cells. AURKA inhibitor PW21 could provide a new approach for treatment of leukemia through blocking the protection by the leukemic microenvironment in clinical application.

Treatment outcomes of patients with acute promyelocytic leukaemia between 2000 and 2017, a retrospective, single centre experience

All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) are effective induction therapy for acute promyelocytic leukaemia (APL). However, early thrombo-haemorrhagic complications and mortality remain high. We aimed to investigate how the timing of ATRA initiation and the inclusion of ATO influence patient outcomes. Clinical records were retrospectively reviewed for all patients treated for APL in a single, tertiary centre during 2000-2017. Among 70 patients with APL, 36 (51.4%) presented with thrombo-haemorrhagic complications, and four (5.8%) died within 30 days. The median time to ATRA initiation was 11.2 (range 0-104) h from the time of admission. Patients requiring more transfusions started on ATRA sooner (P = 0.04). Patients with adverse early events did not start ATRA later (P = 0.99). Nevertheless, patients that required additional tests for diagnosis (PML immunofluorescence or molecular) started on ATRA later (28.5 versus 5.3 h; P < 0.0001), and had more thrombo-haemorrhagic complications (P = 0.04). Long-term survival was actually better in patients who started ATRA later (P = 0.03), which is likely explained by higher proportion of low risk patients in this group. Patients treated with ATO (n = 23) maintained higher fibrinogen levels and required less transfusions during induction (P < 0.05), with no disease-related deaths in this group over a median follow-up time of 37.8 months (interquartile range 44.9 months). In summary, fast ATRA initiation reduces early but not late adverse events in APL patients, and the inclusion of ATO helps further improve both early and late outcomes in APL.

Chemogenomics analysis of drug targets for the treatment of acute promyelocytic leukemia

The main challenges in treating acute promyelocytic leukemia (APL) are currently early mortality, relapse, refractory disease after induction therapy, and drug resistance to ATRA and ATO. In this study, a computational chemogenomics approach was used to identify new molecular targets and drugs for APL treatment. The transcriptional profiles induced by APL were compared with those induced by genetic or chemical perturbations. The genes that can reverse the transcriptional profiles induced by APL when perturbed were considered to be potential therapeutic targets for APL. Drugs targeting these genes or proteins are predicted to be able to treat APL if they can reverse the APL-induced transcriptional profiles. To improve the target identification accuracy of the above correlation method, we plotted the functional protein association networks of the predicted targets by STRING. The results determined PML, RARA, SPI1, HDAC3, CEBPA, NPM1, ABL1, BCR, PTEN, FOS, PDGFRB, FGFR1, NUP98, AFF1, and MEIS1 to be top candidates. Interestingly, the functions of PML, RARA, HDAC3, CEBPA, NPM1, ABL, and BCR in APL have been previously reported in the literature. This is the first chemogenomics analysis predicting potential APL drug targets, and the findings could be used to guide the design of new drugs targeting refractory and recurrent APL.

Glycated albumin stimulates expression of inflammatory cytokines in muscle cells

The effects of glycated albumin on the expression of inflammatory cytokines in differentiated myotubes were investigated. Glycated albumin stimulates the expression of TNF α, IL-1β, IL-6 and CCL-2 both at the mRNA and protein levels via the receptor of AGEs. Various cytokines demonstrated different kinetics of stimulation by glycated albumin. At a high glucose concentration, the stimulation effect was more pronounced than at a low one. At physiological concentrations of albumin and fructosamine, the stimulation effect of glycated albumin on inflammatory cytokine expression in myotubes was also observed. The induction of expression of all studied cytokines was sensitive to the inhibitors of JNK, p38 MAPK, MEK1/2, Src family protein kinases and NF-κB. At the same time, the induction of TNFα and IL-1β was diminished by the Ca²⁺/calmodulin-dependent protein kinase inhibitor, whereas the induction of IL-6 and CCL-2 was reduced by the inhibitor of phosphoinositide 3-kinase. Possible implications of observed stimulation of cytokine expression by glycated albumin in the development of diabetes mellitus symptoms are discussed.

TTP-like syndrome: novel concept and molecular pathogenesis of endotheliopathy-associated vascular microthrombotic disease

TTP is characterized by microangiopathic hemolytic anemia and thrombocytopenia associated with brain and kidney dysfunction. It occurs due to ADAMTS13 deficiency. TTP-like syndrome occurs in critically ill patients with the similar hematologic changes and additional organ dysfunction syndromes. Vascular microthrombotic disease (VMTD) includes both TTP and TTP-like syndrome because their underlying pathology is the same disseminated intravascular microthrombosis (DIT). Microthrombi are composed of platelet-unusually large von Willebrand factor multimers (ULVWF) complexes. TTP occurs as a result of accumulation of circulating ULVWF secondary to ADAMTS13 deficiency. This protease deficiency triggers microthrombogenesis, leading to "microthrombi" formation in microcirculation. Unlike TTP, TTP-like syndrome occurs in critical illnesses due to complement activation. Terminal C5b-9 complex causes channel formation to endothelial membrane, leading to endotheliopathy, which activates two different molecular pathways (i.e., inflammatory and microthrombotic). Activation of inflammatory pathway triggers inflammation. Activation of microthrombotic pathway promotes platelet activation and excessive endothelial exocytosis of ULVWF from endothelial cells (ECs). Overexpressed and uncleaved ULVWF become anchored to ECs as long elongated strings to recruit activated platelets, and assemble "microthrombi". In TTP, circulating microthrombi typically be lodged in microvasculature of the brain and kidney, but in TTP-like syndrome, microthrombi anchored to ECs of organs such as the lungs and liver as well as the brain and kidneys, leading to multiorgan dysfunction syndrome. TTP occurs as hereditary or autoimmune disease and is the phenotype of ADAMTS13 deficiency-associated VMTD. But TTP-like syndrome is hemostatic disorder occurring in critical illnesses and is the phenotype of endotheliopathy-associated VMTD. Thus, this author's contention is TTP and TTP-like syndrome are two distinctly different disorders with dissimilar underlying pathology and pathogenesis.