Research progress of meliaceous limonoids from 2011 to 2021.

FLI1 regulates inflammation-associated genes to accelerate leukemogenesis.

Cholesterol plays vital roles in human physiology; abnormal levels have deleterious pathological consequences. In cancer, elevated or reduced expression of cholesterol biosynthesis is associated with good or poor prognosis, but the underlying mechanisms are largely unknown. The limonoid compounds A1542 and A1543 stimulate ERK/MAPK by direct binding, leading to leukemic cell death and suppression of leukemia in mouse models. In this study, we investigated the downstream consequences of these ERK/MAPK agonists in leukemic cells. We employed RNAseq analysis combined with Q-RT-PCR, western blot and bioinformatics to identify and confirm genes whose expression was altered by A1542 and A1543 in leukemic cells. ShRNA lentiviruses were used to silence gene expression. Cell culture and an animal model (BALB/c) of erythroleukemia induced by Friend virus were utilized to validate effects of cholesterol on leukemia progression. RNAseq analysis of A1542-treated cells revealed the induction of all 18 genes implicated in cholesterol biosynthesis. Expression of these cholesterol genes was blocked by cedrelone, an ERK inhibitor. The cholesterol inhibitor lovastatin diminished ERK/MAPK activation by A1542, thereby reducing leukemic cell death induced by this ERK1/2 agonist. Growth inhibition by cholesterol was observed both at the intracellular level, and when orally administrated into a leukemic mouse model. Both HDL and LDL also suppressed leukemogenesis, implicating these lipids as important prognostic markers for leukemia progression. Mechanistically, knockdown experiments revealed that the activation of SREBP1/2 by A1542-A1543 was responsible for induction of only a sub-set of cholesterol biosynthesis genes. Induction of other regulatory factors by A1542-A1543 including EGR1, AP1 (FOS + JUN) LDLR, IER2 and others may cooperate with SREBP1/2 to induce cholesterol genes. Indeed, pharmacological inhibition of AP1 significantly inhibited cholesterol gene expression induced by A1542. In addition to leukemia, high expression of cholesterol biosynthesis genes was found to correlate with better prognosis in renal cancer. This study demonstrates that ERK1/2 agonists suppress leukemia and possibly other types of cancer through transcriptional stimulation of cholesterol biosynthesis genes.

/pdf/erk-activation-via-a1542-3-limonoids-attenuates-3mhj35nrl2.pdf

ERK activation via A1542/3 limonoids attenuates erythroleukemia through transcriptional stimulation of cholesterol biosynthesis genes.

Acute myeloid leukemia (AML) is an aggressive type of human leukemia with a low survival rate, and its complete remission remains challenging. Although chemotherapy is the first-line treatment of AML, it exerts toxicity in noncancerous cells when used in high doses, thus necessitating the development of novel compounds with a high therapeutic window. This study aimed to investigate the anticancer effects of several compounds derived from the fruits of Melia azedarach (a tree with medicinal properties). Among them, 1-cinnamoyltrichilinin (CT) was found to strongly suppress the viability of HL-60 human leukemia cells. CT treatment induced apoptosis and increased nuclear fragmentation and fractional DNA content in HL-60 cells in a dose-dependent manner. CT induced phosphorylation of p38 mitogen-activated protein kinases (p38), though not of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), and activated Bcl-2 family proteins towards the proapoptosis and cleavage of caspase-3 and poly (ADP-ribose) polymerase. Both CT-mediated apoptosis and apoptotic protein expression were reversed by treatment with the p38 inhibitor, thereby indicating the p38 pathway to be critical in CT-stimulated apoptosis. The results collectively indicated CT to suppress HL-60 survival by activating the p38 pathway and inducing apoptosis, hence being a novel potential therapeutic agent for AML.

1-Cinnamoyltrichilinin from Melia azedarach Causes Apoptosis through the p38 MAPK Pathway in HL-60 Human Leukemia Cells.

Transcription factor Fli-1 as a new target for antitumor drug development.

MAPK/ERK kinases transmit signals from many growth factors/kinase receptors during normal cell growth/differentiation, and their dysregulation is a hallmark of diverse types of cancers. A plethora of drugs were developed to block this kinase pathway for clinical application. With the exception of a recently identified agent, EQW, most of these inhibitors target upstream factors but not ERK1/2; no activator of ERK1/2 is currently available. A library of compounds isolated from medicinal plants of China was screened for anti-cancer activities. Three limonoid compounds, termed A1541–43, originally isolated from the plant Melia azedarach, exhibiting strong anti-leukemic activity. The anti-neoplastic activity and the biological target of these compounds were explored using various methods, including western blotting, flow cytometry, molecular docking and animal model for leukemia. Compounds A1541–43, exhibiting potent anti-leukemic activity, was shown to induce ERK1/2 phosphorylation. In contrast, the natural product Cedrelone, which shares structural similarities with A1541–43, functions as a potent inhibitor of ERK1/2. We provided evidence that A1541–43 and Cedrelone specifically target ERK1/2, but not the upstream MAPK/ERK pathway. Computational docking analysis predicts that compounds A1541–43 bind a region in ERK1/2 that is distinct from that to which Cedrelone and EQW bind. Interestingly, both A1541–43, which act as ERK1/2 agonists, and Cedrelone, which inhibit these kinases, exerted strong anti-proliferative activity against multiple leukemic cell lines, and induced robust apoptosis as well as erythroid and megakaryocytic differentiation in erythroleukemic cell lines. These compounds also suppressed tumor progression in a mouse model of erythroleukemia. This study identifies for the first time activators of ERK1/2 with therapeutic potential for the treatment of cancers driven by dysregulation of the MAPK/ERK pathway and possibly for other disorders.

/pdf/selective-erk1-2-agonists-isolated-from-melia-azedarach-with-1qmrh1m5ag.pdf

Selective ERK1/2 agonists isolated from Melia azedarach with potent anti-leukemic activity

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ERK activation via A1542/3 limonoids attenuates erythroleukemia through transcriptional stimulation of cholesterol biosynthesis genes.

Selective ERK1/2 agonists isolated from Melia azedarach with potent anti-leukemic activity