Matrine, a potential c-Myc inhibitor, suppresses ribosome biogenesis and nucleotide metabolism in myeloid leukemia

Matrine regulates miR-495-3p/miR-543/PDK1 axis to repress the progression of acute myeloid leukemia via the Wnt/β-catenin pathway

Acute myeloid leukemia (AML) is a commonly hematological malignancy with feature of rapidly increased immature myeloid cells in bone marrow. The anti-tumor activity of matrine has been reported in various cancers. However, the functional role of matrine in AML progression still needs to be studied. Cell growth, apoptosis and cell cycle arrest in AML cells were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and flow cytometry, respectively. The levels of adenosine triphosphate (ATP)/adenosine diphosphate (ADP) ratio, lactate production and glucose consumption were detected to evaluate glycolysis. Dual-luciferase reporter assay was conducted to determine the relationships between phosphoinositide-dependent kinase 1 (PDK1) and microRNA-495-3p (miR-495-3p)/microRNA-543 (miR-543) in AML cells. The results showed that matrine inhibited cell proliferation, glycolysis, and accelerated cell apoptosis and cell cycle arrest in AML cells. MiR-495-3p/miR-543 was lowly expressed, and PDK1 was highly expressed in AML. Functionally, both miR-495-3p and miR-543 could reverse the effects of matrine on cell proliferation, glycolysis, apoptosis and cell cycle arrest in AML cells. Mechanistically, miR-495-3p/miR-543 directly targeted PDK1, and the inhibition impacts of miR-495-3p/miR-543 on AML progression could be rescued by PDK1 overexpression. Moreover, matrine also could regulate PDK1 expression to suppress AML progression. Besides, matrine modulated miR-495-3p/miR-543/PDK1 axis to inhibit the Wnt/β-catenin pathway. In summary, matrine hampered the progression of AML through targeting miR-495-3p and miR-543 to attenuate PDK1 expression, thereby repressing the Wnt/β-catenin pathway.

PAICS as a potential target for cancer therapy linking purine biosynthesis to cancer progression

Tumor cells are required to undergo metabolic reprogramming for rapid development and progression, and one of the metabolic characteristics of cancer cells is the excessive synthesis and utilization of nucleotides. Abnormally increased nucleotides and their metabolites not only directly accelerate tumor cell progression but also indirectly act on stromal cells in the tumor microenvironment (TME) via a paracrine manner to regulate tumor progression. Purine nucleotides are mainly produced via de novo nucleotide synthesis in tumor cells; therefore, intervening in their synthesis has emerged as a promising strategy in anti-tumor therapy. De novo purine synthesis is a 10-step reaction catalyzed by six enzymes to synthesize inosine 5-monophosphate (IMP) and subsequently synthesize AMP and GMP. Phosphoribosylaminoimidazole carboxylase/phosphori-bosylaminoimidazole succinocarboxamide synthetase (PAICS) is a bifunctional enzyme that catalyzes de novo purine synthesis. Aberrantly elevated PAICS expression in various tumors is associated with poor prognosis. Evidence suggests that PAICS and its catalytic product, N-succinylcarboxamide-5-aminoimidazole ribonucleotide (SAICAR), could inhibit tumor cell apoptosis and promote the growth, epithelial-mesenchymal transition (EMT), invasion, and metastasis by regulating signaling pathways such as pyruvate kinase M2 (PKM2), extracellular signal-related kinases 1 and 2 (ERK1/2), focal adhesion kinase (FAK) and so on. This review summarizes the structure, biological functions and the molecular mechanisms of PAICS in cancer development and discusses its potential to be a target for tumor therapy.