Role of Signal Regulatory Protein α in Arsenic Trioxide-induced Promyelocytic Leukemia Cell Apoptosis

Traditional Chinese medicine for acute myelocytic leukemia therapy: exploiting epigenetic targets

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy with historically high mortality rates. The treatment strategies for AML is still internationally based on anthracyclines and cytarabine, which remained unchanged for decades. With the rapid advance on sequencing technology, molecular targets of leukemogenesis and disease progression related to epigenetics are constantly being discovered, which are important for the prognosis and treatment of AML. Traditional Chinese medicine (TCM) is characterized by novel pharmacological mechanisms, low toxicity and limited side effects. Several biologically active ingredients of TCM are effective against AML. This review focuses on bioactive compounds in TCM targeting epigenetic mechanisms to address the complexities and heterogeneity of AML.

ATPR induces acute promyelocytic leukemia cells differentiation and cycle arrest via the lncRNA CONCR/DDX11/PML-RARα signaling axis

Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia (AML) with a high mortality rate, and the production of PML-RARα fusion protein is the cause of its pathogenesis. Our group has synthesized a novel compound, 4-amino-2-trifluoromethyl-phenyl retinate (ATPR), by structural modification of All-trans retinoic acid (ATRA), which has strong cell differentiation-inducing effects and inhibits the expression of PML-RARα. In this study, acute promyelocytic leukemia NB4 cells before and after ATPR induction were analyzed by whole transcriptome microarray, and the expression of lncRNA CONCR was found to be significantly downregulated. The role of CONCR in ATPR-induced cell differentiation and cycle arrest was explored through overexpression and silencing of CONCR. And then the database was used to predict that CONCR may bind to DEAD/H-Box Helicase 11 (DDX11) protein to further explore the role of CONCR binding to DDX11. The results showed that ATPR could reduce the expression of CONCR, and overexpression of CONCR could reverse the ATPR-induced cell differentiation and cycle blocking effect, and conversely silencing of CONCR could promote this effect. RNA immunoprecipitation (RIP) experiments showed that CONCR could bind to DDX11, the protein expression levels of DDX11 and PML-RARα were elevated after overexpression of CONCR. These results suggest that ATPR can regulate the expression of DDX11 through CONCR to affect the expression of PML-RARα fusion protein, which in turn induces the differentiation and maturation of APL cells.

SIRPα: A key player in innate immunity

Signal regulatory protein alpha (SIRPα) is a crucial inhibitory regulator expressed on the surface of myeloid cells, including macrophages, dendritic cells, monocytes, neutrophils, and microglia. SIRPα plays an indispensable role in innate immune and adoptive immune responses in cancer immunology, tissue homeostasis, and other physiological or phycological conditions. This review provides an overview of the research history, ligands, signal transduction pathways, and functional mechanisms associated with SIRPα. Additionally, we summarize the therapeutic implications of targeting SIRPα as a promising novel strategy in immuno-oncology.

The regulation of CD47-SIRPα signaling axis by microRNAs in combination with conventional cytotoxic drugs together with the help of nano-delivery: a choice for therapy?

CD47, a member of the immunoglobulin superfamily, is an important "Don't Eat-Me" signal in phagocytosis process [clearance of apoptotic cells] as well as a regulator of the adaptive immune response. The lower level of CD47 on the cell surface leads to the clearance of apoptotic cells. Dysregulation of CD47 plays a critical role in the development of disorders, particularly cancers. In cancers, recognition of CD47 overexpression on the surface of cancer cells by its receptor, SIRPα on the phagocytic cells, inhibits phagocytosis of cancer cells. Thus, blocking of CD47-SIRPα signaling axis might be as a promising therapeutic target, which promotes phagocytosis of cancer cells, antigen-presenting cell function as well as adaptive T cell-mediated anti-cancer immunity. In this respect, it has been reported that CD47 expression can be regulated by microRNAs (miRNAs). MiRNAs can regulate phagocytosis of macrophages apoptotic process, drug resistance, relapse of disease, radio-sensitivity, and suppress cell proliferation, migration, and invasion through post-transcriptional regulation of CD47-SIRPα signaling axis. Moreover, the regulation of CD47 expression by miRNAs and combination with conventional cytotoxic drugs together with the help of nano-delivery represent a valuable opportunity for effective cancer treatment. In this review, we review studies that evaluate the role of miRNAs in the regulation of CD47-SIRPα in disorders to achieve a novel preventive, diagnostic, and therapeutic strategy.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Also, kindly confirm the details in the metadata are correct. Confirmed.Journal standard instruction requires a structured abstract; however, none was provided. Please supply an Abstract with subsections..Not confirmed. This is a review article. According to submission guidelines: "The abstract should be presented divided into subheadings (unless it is a mini or full review article)". Kindly check and confirm whether the corresponding authors and mail ID are correctly identified. Confirmed.

Arsenic induced epigenetic changes and relevance to treatment of acute promyelocytic leukemia and beyond

Epigenetic alterations regulate gene expression without changes in the DNA sequence. It is well-demonstrated that aberrant epigenetic changes contribute to the leukemogenesis of acute promyelocytic leukemia (APL). Arsenic trioxide (ATO) is one of the most common drugs used in the frontline treatment of APL that act through targeting and destabilizing the PML/RARα oncofusion protein. ATO together with all-trans retinoic acid (ATRA) lead to durable remission of more than 90% non-high-risk APL patients, turning APL treatment into a paradigm of oncoprotein targeted cure. Although relapse and drug resistance in APL are yet to be resolved in the clinic, epigenetic machineries might hold the key to address this issue. Further, ATO also showed promising anticancer activities against a variety of malignancies, but its application is particularly restricted due to limited understanding of the mechanism. Thus, a thorough understanding of epigenetic mechanism behind anti-leukemic effects of ATO would benefit the development of ATO-based anticancer strategy. Role of ATRA on APL associated epigenetic alterations has been extensively studied and reviewed. Recently, accumulating evidence suggest that ATO also induces some epigenetic changes that might favor APL eradication. In this article, we comprehensively discuss arsenic induced epigenetic changes and its relevance in APL treatment and beyond, so as to provide novel insights into overcoming arsenic resistance in APL and promote application of this drug to other malignancies.

Effects of Arsenic on wnt/β-catenin Signaling Pathway: A Systematic Review and Meta-analysis

We aimed to systematically evaluate the regulatory effect of arsenic on wnt/β-catenin signaling pathway and to provide theoretical basis for revealing the mechanism of the relationship between arsenic and cell proliferation. The meta-analysis was carried out using Revman5.2 and Stata13.0 to describe the differences between groups with standard mean difference. We found in normal cells that the levels of wnt3a, β-catenin, glycogen synthase kinase-3β phosphorylated at serine 9 (p-GSK-3β(Ser9)), cyclinD1, proto-oncogene c-myc, and vascular endothelial growth factor (VEGF) in the arsenic intervention group were higher than those in the control group, and the level of glycogen synthase kinase-3β (GSK-3β) was lower than that in the control group (P < 0.05, respectively). Subgroup analysis showed that for a long time period (>24 h), the level of β-catenin in the arsenic intervention group was higher than that in the control group, and the level of GSK-3β of the same long-time period (>24 h) with low-dose (≤5 μM) intervention was lower than those in the control group (P < 0.05, respectively). In cancer cells, the levels of β-catenin, cyclinD1, c-myc, and VEGF in the arsenic intervention group were lower than those in the control group, while the level of GSK-3β in the arsenic intervention group was higher than that in the control group (P < 0.05, respectively). Subgroup analysis showed that the levels of β-catenin, cyclinD1, and c-myc in the high-dose (>5 μM) arsenic intervention group were lower than those in the control group, and the levels of β-catenin and cyclinD1 in the high-dose (>5 μM) arsenic intervention group were lower than those in the low-dose (≤5 μM) arsenic intervention group (P < 0.05, respectively). In addition, the regulation of arsenic on β-catenin was dose-dependent in the range of arsenic concentration from 0 to 7.5 μM. This study revealed that arsenic could upregulate wnt/β-catenin signaling pathway in normal cells and downregulate it in cancer cells, and its effect was affected by time and dose.

OncomiR or antioncomiR: Role of miRNAs in Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is a hematopoietic progenitor/stem cell disorder in which neoplastic myeloblasts are stopped at an immature stage of differentiation and lost the normal ability of proliferation and apoptosis. MicroRNAs (miRNAs) are small noncoding, single-stranded RNA molecules that can mediate the expression of target genes. While miRNAs mean to contribute the developments of normal functions, abnormal expression of miRNAs and regulations on their corresponding targets have often been found in the developments of AML and described in recent years. In leukemia, miRNAs may function as regulatory molecules, acting as oncogenes or tumor suppressors. Overexpression of miRNAs can down-regulate tumor suppressors or other genes involved in cell differentiation, thereby contributing to AML formation. Similarly, miRNAs can down-regulate different proteins with oncogenic activity as tumor suppressors. We herein review the current data on miRNAs, specifically their targets and their biological function based on apoptosis in the development of AML.

Disulfiram/copper causes ROS levels alteration, cell cycle inhibition, and apoptosis in acute myeloid leukaemia cell lines with modulation in the expression of related genes

The majority of acute myeloid leukaemia (AML) patients will die from their disease or therapy-related complications. There is an inevitable need to improve the survival of AML patients. Previous studies show that disulfiram (DSF), an anti-alcoholism drug with a low toxicity profile, demonstrates anticancer behaviors. Here, we evaluated the cytotoxicity and mechanistic action of DSF on the AML cell lines KG-1, NB4, and U937. The microculture tetrazolium test revealed that DSF alone or in combination with copper (Cu) is highly toxic to the AML cells at concentrations lower than those achievable in the clinical setting, with Cu increasing the DSF-induced inhibition of metabolic activity. Flow cytometric analysis and QRT-PCR indicated that in the two cell lines, NB4 and U-937, DSF/Cu increased reactive oxygen species (ROS) levels in association with the induction of superoxide dismutase 2 (SOD2) expression and suppression of catalase (CAT). In the KG-1 cell line, DSF/Cu reduced the ROS levels in agreement with the induction of CAT expression. The cell cycle and apoptosis assessment by flow cytometry demonstrated that DSF/Cu induced G0/G1 cell cycle arrest and apoptosis. These were associated with the increased expression of FOXO tumor suppressors, decreased expression of the MYC oncogene and the modulation of their known target genes related to the cell cycle and apoptosis. Therefore, DSF/Cu caused the disturbance of the ROS balance, cell cycle arrest and apoptosis in AML cells in coordination with the modulation in expression of their related genes. These results propose the possible use of DSF in AML therapies.

microRNA-539 suppresses tumor growth and tumorigenesis and overcomes arsenic trioxide resistance in hepatocellular carcinoma

AIMS

Dysregulation of microRNAs (miRNAs) plays a critical role in tumor growth and progression. In this study, we sought to explore the expression and biological roles of miR-539 in hepatocellular carcinoma (HCC).

MAIN METHODS

The expression of miR-539 in human HCC tissues and cell lines was examined. The effects of miR-539 overexpression on cell growth, tumorigenicity, arsenic trioxide resistance of HCC cells were determined. The signaling pathways involved in the action of miR-539 in HCC were also investigated.

KEY FINDINGS

miR-539 was downregulated in HCC tissues and cells, relative to corresponding controls. Overexpression of miR-539 inhibited HCC cell viability and colony formation in vitro and impaired tumorigenesis of HCC cells in vivo. Transfection with miR-539 mimic significantly induced apoptosis in HepG2 cells, which was coupled with reduced expression of anti-apoptotic proteins Bcl-2 and Bcl-xL and decreased phosphorylation of Stat3. Overexpression of a constitutively active form of Stat3 partially blocked miR-539-mediated apoptosis. Enforced expression of miR-539 resensitized arsenic trioxide-resistant HCC cells to arsenic trioxide. Intratumoral delivery of miR-539 mimic significantly retarded the growth of xenograft tumors from arsenic trioxide-resistant HCC cells by about 35%, compared to delivery of control miRNA (P<0.05). In combination with arsenic trioxide, miR-539 mimic yielded about 80% decrease in tumor burden.

SIGNIFICANCE

miR-539 functions as a tumor suppressor in HCC and reexpression of this miRNA offers a potential therapeutic strategy for this disease.

MicroRNA-based screens for synthetic lethal interactions with c-Myc

microRNAs (miRs) are small, non-coding RNAs, which play crucial roles in the development and progression of human cancer. Given that miRs are stable, easy to synthetize and readily introduced into cells, they have been viewed as having potential therapeutic benefit in cancer. c-Myc (Myc) is one of the most commonly deregulated oncogenic transcription factors and has important roles in the pathogenesis of cancer, thus making it an important, albeit elusive therapeutic target. Here we review the miRs that have been identified as being both positive and negative targets for Myc and how these participate in the complex phenotypes that arise as a result of Myc-driven transformation. We also discussseveral recent reports of Myc-synthetic lethal interactions with miRs.These highlight the importance and complexity of miRs in Myc-mediated biological functions and the opportunities for Myc-driven human cancer therapies.