Divalproex sodium enhances the anti-leukemic effects of imatinib in chronic myeloid leukemia cells partly through SIRT1

HDAC inhibitors: Promising agents for leukemia treatment

The essential role of epigenetic modification in the pathogenesis of a series of cancers have gradually been recognized. Histone deacetylase (HDACs), as well-known epigenetic modulators, are responsible for DNA repair, cell proliferation, differentiation, apoptosis and angiogenesis. Studies have shown that aberrant expression of HDACs is found in many cancer types. Thus, inhibition of HDACs has provided a promising therapeutic approach alternative for these patients. Since HDAC inhibitor (HDACi) vorinostat was first approved by the Food and Drug Administration (FDA) for treating cutaneous T-cell lymphoma (CTCL) in 2006, the combination of HDAC inhibitors with other molecules such as chemotherapeutic drugs has drawn much attention in current cancer treatment, especially in hematological malignancies therapy. Up to now, there have been more than twenty HDAC inhibitors investigated in clinic trials with five approvals being achieved. Indeed, Histone deacetylase inhibitors promote or enhance several different anticancer mechanisms and therefore are in evidence as potential antileukemia agents. In this review, we will focus on possible mechanisms by how HDAC inhibitors exert therapeutic benefit and their clinical utility in leukemia.

Isoliquiritigenin from licorice flavonoids attenuates NLRP3-mediated pyroptosis by SIRT6 in vascular endothelial cells

ETHNOPHARMACOLOGIC RELEVANCE

Licorice is a traditional Chinese medicine that has been used for cardiovascular diseases. Recent studies found that supplementation with licorice extracts attenuated the development of atherosclerosis (AS) in hypercholesterolemic patients. Many studies have shown that licorice flavonoids, the main active components of licorice, have a variety of pharmacological effects, including anti-inflammation, regulation of lipid metabolism, and antioxidation. However, the key active components against AS in licorice flavonoids are still unclear.

AIM OF THE STUDY

The aim of this paper is to investigate the active components of licorice flavonoids that exert anti-atherosclerotic effects and the underlying mechanisms.

MATERIALS AND METHODS

Network pharmacology was used to screen the active components of licorice flavonoids that have anti-atherosclerotic effects. Combining bioinformatics analysis and in vitro studies, the effects and underlying mechanisms of the active component isoliquiritigenin (ISL) on cell pyroptosis were further investigated in tumor necrosis factor (TNF)-α-treated human umbilical vein endothelial cells (HUVECs).

RESULTS

We constructed a compound-target network and screened 3 active components, namely, ISL, glabridin, and naringenin in licorice flavonoids. The half maximal effective concentration values of these 3 components suggested that ISL was the key active component against TNF-α-induced endothelial cell injury. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that ISL could potentially treat AS via the nucleotide-binding and oligomerization domain (NOD)-like receptor signaling pathway. An in vitro study verified that ISL suppressed TNF-α-induced NLRP3 activation and pyroptosis in HUVECs. The molecular docking and cellular thermal shift assay showed good compatibility between ISL and class III histone deacetylase sirtuin 6 (SIRT6). Moreover, we found that ISL upregulated the expression of SIRT6 in TNF-α-treated HUVECs. Further study found that SIRT6 knockdown reduced the inhibitory effect of ISL on pyroptosis, whereas the NLRP3 inhibitor reversed this process in TNF-α-treated HUVECs.

CONCLUSIONS

Our results demonstrate that ISL is a key active component of licorice flavonoids. ISL attenuates NLRP3-mediated vascular endothelial cell pyroptosis via SIRT6, and SIRT6 may be a potential target of ISL for the treatment of AS.

Combined effects on leukemia cell growth by targeting sphingosine kinase 1 and sirtuin 1 signaling

Targeting multiple signaling pathways is a potential novel therapeutic strategy for the treatment of leukemias. Leukemia cells express high levels of sphingosine kinase 1 (Sphk1) and sirtuin 1 (SIRT1). However, to the best of our knowledge, their interaction and potential synergistic inhibitory effects on the growth and survival of leukemia cells have not been investigated. The present study revealed the role of the Sphk1/S1P/SIRT1 axis in K562, KCL22 and TF1 cells and hypothesized that the inhibition of Sphk1 and SIRT1 had synergistic effects on the growth and survival of leukemia cells. Cell viability was tested using a Cell Counting Kit-8 assay and cell colony forming assay. Cell apoptosis was detected using Annexin V-APC/PI staining. The stages of the cell cycle were measured using PI staining. Protein levels were measured by western blotting. Treatment of leukemia cells with S1P resulted in the upregulation of SIRT1 expression, whereas inhibition of Sphk1 induced SIRT1 downregulation in leukemia cells. Both SKI-II and EX527 actively suppressed growth, blocked cell cycle progression and induced apoptosis of leukemia cells. Furthermore, inhibition of Sphk1 and SIRT1 exhibited suppressive effects on the growth and survival of leukemia cells. Notably, the inhibition of Sphk1 and SIRT1 suppressed cell growth and induced apoptosis of T-315I mutation-harboring cells. Additionally, treatment with SKI-II and EX527 suppressed the ERK and STAT5 pathways in leukemia cells. These data indicated that targeting the Sphk1/S1P/SIRT1 axis may be a novel therapeutic strategy for the treatment of leukemia.

Imatinib mesylate affects extracellular ATP catabolism and expression of NTPDases in a chronic myeloid leukemia cell line

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm, characterized by the occurrence of the t(9;22)(q34;q11) translocation. First-line therapy for CML consists of treatment with imatinib mesylate, which selectively inhibits the BCR-ABL protein by competing for its ATP-binding site. Adenine nucleotide signaling is modulated by the ectonucleotidases and this pathway is related to tumorigenic processes. Considering the relationship between ATP and cancer, we aimed to evaluate the influence of imatinib mesylate on the expressions and functions of the NTPDase and ecto-5'-nucleotidase (CD73) enzymes in imatinib-sensitive and -resistant K-562 cell lines. mRNA analysis showed that K-562 cells express all ENTPDs and NT5E. However, when treated with imatinib mesylate for 24 h, the expression of ENTPD1, -2, -3 and -5 increased, leading to a higher nucleotides hydrolysis rate. HPLC analysis identified increased ATP degradation in cells after 24 h of treatment, with consequent ADP and AMP formation, corroborating the increase in gene and protein expression of ectonucleotidases as observed in previous results. On the other hand, we observed that imatinib-resistant K-562 cells presented a decrease in nucleotide hydrolysis and expressions of ENTPD1 and -5. These results suggest an involvement of imatinib in modulating ectonucleotidases in CML that will need further investigation. Since these ectonucleotidases have important catalytic activities in the tumor microenvironment, their modulation in CML cells may represent an important therapeutic approach to regulate levels of extracellular adenine nucleotides.

CAY10683 and imatinib have synergistic effects in overcoming imatinib resistance via HDAC2 inhibition in chronic myeloid leukemia

Imatinib (IM) is utilized for targeting the BCR-ABL fusion protein and as such, chronic myeloid leukemia (CML) is considered to be a curable disorder for which patients can achieve a long survival. However, 15-20% CML cases end up with IM resistance that will develop into the accelerated stage and eventually the blast crisis, thereby restricting the treatment choices and giving rise to a dismal survival rate. Histone deacetylases (HDACs) have been identified to modulate the oncogene as well as tumor suppressor gene activities, and they play crucial parts in tumorigenesis. It is found recently that IM combined with HDAC inhibitors (HDACi) can serve as a promising means of overcoming IM resistance in CML cases. Santacruzamate A (CAY10683) has been developed as one of the selective and powerful HDACi to resist HDAC2. Therefore, in this study, we aimed to examine whether CAY10683 combined with IM could serve as the candidate antitumor treatment for CML cases with IM resistance. The influences of CAY10683 combined with IM on the cell cycle arrest, apoptosis, and viability of CML cells with IM resistance were investigated, and it was discovered that the combined treatment exerted synergistic effects on managing the IM resistance. Moreover, further studies indicated that CAY10683 combined with IM mainly exerted synergistic effects through inhibiting HDAC2 in K562-R and LAMA84-R cells with IM resistance. Besides, the PI3K/Akt signal transduction pathway was found to mediate the HDAC2 regulation of CML cells with IM resistance. Eventually, it was also discovered, based on the xenograft mouse model, that the combined treatment dramatically suppressed CML proliferation in vivo. To sum up, findings in the current study indicate that CAY10683 combined with IM can be potentially used as the candidate treatment for CML with IM resistance.

Nicotinic-nAChR signaling mediates drug resistance in lung cancer

Lung cancer is the leading cause of cancer death worldwide. Cigarette smoking is the most common risk factor for lung carcinoma; other risks include genetic factors and exposure to radon gas, asbestos, secondhand smoke, and air pollution. Nicotine, the primary addictive constituent of cigarettes, contributes to cancer progression through activation of nicotinic acetylcholine receptors (nAChRs), which are membrane ligand-gated ion channels. Activation of nicotine/nAChR signaling is associated with lung cancer risk and drug resistance. We focused on nAChR pathways activated by nicotine and its downstream signaling involved in regulating apoptotic factors of mitochondria and drug resistance in lung cancer. Increasing evidence suggests that several sirtuins play a critical role in multiple aspects of cancer drug resistance. Thus, understanding the consequences of crosstalk between nicotine/nAChRs and sirtuin signaling pathways in the regulation of drug resistance could be a critical implication for cancer therapy.

miR‑128 is upregulated in epilepsy and promotes apoptosis through the SIRT1 cascade

The present study aimed to examine the functional and molecular effects of miR‑128 in epilepsy, in order to investigate its potential protective mechanisms. Firstly, miR‑128 expression in rats with lithium chloride‑induced epilepsy was demonstrated to be increased compared with the control rats. Subsequently, results from an in vitro epilepsy model demonstrated that overexpression of miR‑128 promoted nerve cell apoptosis, increased the protein expression of tumor protein p53, BCL2 associated X (Bax) and Cytochrome c, and enhanced caspase‑3/9 activity, whereas it suppressed the protein expression of sirtuin 1 (SIRT1). In addition, these alterations may be reversed by the downregulation of miR‑128. Furthermore, treatment with CAY10602, a SIRT1 agonist, reduced the effects of miR‑128 on nerve cells in vitro. Treatment with pifithrin‑β hydrobromide, a p53 inhibitor, was additionally able to mitigate the effects of miR‑128 in vitro. In conclusion, the present findings indicated that anti‑miR‑128 may exert neuroprotective effects in epilepsy, through the SIRT1/p53/Bax/Cytochrome c/caspase signaling pathway.

Chronic myeloid leukemia-derived exosomes attenuate adipogenesis of adipose derived mesenchymal stem cells via transporting miR-92a-3p

Cancer-associated cachexia (CAC) has tremendous effects on the patient's tolerance to chemotherapy and the quality of life, especially in the advanced stages, such as the acute and terminal stages of chronic myeloid leukemia (CML). However, the underlying mechanisms and mediators remain unclear. Here, we showed that mice injected with CML-derived exosomes had significant weight loss and great drop of body fat rate. In the meanwhile, we found that CML-derived exosomes could be taken up by adipose tissue, and, in turn, suppressed the adipogenic ability of adipose-derived mesenchymal stem cells (ADSCs). By RNA sequencing, miR-92a-3p was found highly expressed in both CML cells and the derivative exosomes. Mechanistically, miR-92a-3p inhibited adipogenesis of ADSCs via posttranscriptionally decreasing C/EBPα expression when transferred into the ADSCs with the exosomes, and encapsulating miR-92a-3p inhibitor into CML exosomes blocked the antiadipogenic effects of CML exosomes. In addition, we also found that miR-92a-3p was highly expressed in exosomes from some other types of cancers that cause cachexia. These results demonstrate that adipogenesis inhibition by tumor-derived exosomes, mainly exosomal microRNAs like miR-92a-3p, are the main mediators for CAC.

The function of miRNA‑153 against isoflurane‑induced neurotoxicity via Nrf2/ARE cytoprotection

The present study aimed to investigate the function of micro (mi)RNA‑153 against isoflurane‑induced neurotoxicity and its mechanism. In isoflurane‑induced mice, miRNA‑153 expression was downregulated compared with in the control group. Downregulation of miRNA‑153 induced neurocyte apoptosis, reduced cell growth and promoted oxidative stress in an in vitro model. Overexpression of miRNA‑153 reduced oxidative stress, promoted cell growth and inhibited neurocyte apoptosis within an in vitro model. Downregulation of miRNA‑153 suppressed nuclear erythroid‑2 related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway, which was induced via the overexpression of miRNA‑153 in vitro. The Nrf2 agonist, dimethyl fumarate (2.5 µM), induced the Nrf2/ARE signaling pathway and reduced oxidative stress to induce neurocyte apoptosis in vitro following treatment with anti‑miRNA‑153. The results of the present study suggested the function of miRNA‑153 against neurotoxicity via Nrf2/ARE‑mediated cytoprotection.

Hydroxytyrosol NO regulates oxidative stress and NO production through SIRT1 in diabetic mice and vascular endothelial cells

BACKGROUND

Vascular complications are major causes of disability and death in people with diabetes mellitus (DM). Nitric oxide (NO) supplement may help prevent vascular complications and is an attractive treatment option for DM. Hydroxytyrosol (HT) is a major polyphenol in olive oil. It is mainly used as a dietary supplement because of its antioxidant effect.

PURPOSE

We aimed to determine the effects of hydroxytyrosol nitric oxide (HT-NO) on oxidative stress and NO level as well as related mechanisms.

STUDY DESIGN/METHODS

The effects of HT-NO on oxidative stress and NO level were examined by using diabetic mouse model and HUVECs.

RESULTS

Our results showed that HT-NO has antioxidant and NO-releasing activities in vitro and in DM mice. HT-NO not only decreased blood glucose and oxidative stress but also increased NO level and deacetylase Sirtuin 1 (SIRT1) expression in DM mice and high glucose (HG)-stimulated HUVECs. Further studies found that SIRT1 activation augmented the effect of HT-NO on eNOS phosphorylation in HG-stimulated HUVECs. However, the promotive effect of HT-NO on eNOS phosphorylation was abolished by SIRT1 knockdown. Most importantly, HT-NO inhibited reactive oxygen species (ROS) production through SIRT1 in HUVECs. The ROS scavenger enhanced the effect of HT-NO on eNOS phosphorylation.

CONCLUSION

These results suggest that HT-NO regulates oxidative stress and NO production partly through SIRT1 in DM mice and HG-stimulated HUVECs.

Design, synthesis and biological evaluation of 2-amino-N-(2-aminophenyl)thiazole-5-carboxamide derivatives as novel Bcr-Abl and histone deacetylase dual inhibitors

A novel design approach: combination of Bcr-Abl and HDAC inhibitory activity in one molecule to produce dual inhibitors.