Design, Synthesis, and Antileukemic Evaluation of a Novel Mikanolide Derivative Through the Ras/Raf/MEK/ERK Pathway.

Chronic myeloid leukemia (CML) accounts for a major cause of death in adult leukemia patients due to mutations or other reasons for dysfunction in the ABL proto-oncogene. The ubiquitous BCR-ABL expression stimulates CML by activating CDK1 and cyclin B1, promoting pro-apoptotic, and inhibiting antiapoptotic marker expression along with regulations in RAS pathway activation. Thus, inhibitors of cyclins and the RAS pathway by ERK are of great interest in antileukemic treatments. Mikanolide is a sesquiterpene dilactone isolated from several Asteraceae family Mikania sp. plants. Sesquiterpene dilactone is a traditional medicine for treating ailments, such as flu, cardiovascular diseases, bacterial infections, and other blood disorders. It is used as a cytotoxic agent as well. The need of the hour is potent chemotherapeutic agents with cytotoxic effects inhibition of proliferation and activation of apoptotic machinery. Recently, ERK inhibitors are used in clinics as anticancer agents. Thus, in this study, we synthesized 22-mikanolide derivatives that elucidated to be potent antileukemic agents in vitro. However, a bioactive mikanolide derivative, 3g, was found with potent antileukemic activity, through the Ras/Raf/MEK/ERK pathway. It can arrest the cell cycle by inhibiting phosphorylation of CDC25C, triggering apoptosis, and promoting DNA and mitochondrial damage, thus suggesting it as a potential chemotherapeutic agent for leukemia patients.

Germacranolide sesquiterpenes from Carpesium cernuum and their anti-leukemia activity.

In this study, three new germacranolide sesquiterpenes (1-3), together with six related known analogues (4-9) were isolated from the whole plant of Carpesium cernuum. Their structures were established by a combination of extensive NMR spectroscopic analysis, HR-ESIMS data, and ECD calculations. The anti-leukemia activities of all compounds towards three cell lines (HEL, KG-1a, and K562) were evaluated in vitro. Compounds 1-3 exhibited moderate cytotoxicity with IC50 values ranging from 1.59 to 5.47 µmol·L-1. Mechanistic studies indicated that 2 induced apoptosis by decreasing anti-apoptotic protein Bcl-2 and activating the caspase family in K562 cells. These results suggest that compound 2 is a potential anti-leukemia agent.

A natural acylphloroglucinol triggered antiproliferative possessions in HEL cells by impeding STAT3 signaling and attenuating angiogenesis in transgenic zebrafish model.

Leukemia is responsible for a reason of death, globally. Even though there are several treatment regimens available in the clinics against this disease, a perfect chemotherapeutic agent for the same is still under investigation. Natural plant-derived secondary metabolites are used in clinics to treat leukemia for better benefits with reduced side-effects. Likely, several bioactive compounds from Callistemon sp. were reported for their bioactive benefits. Furthermore, acylphloroglucinol derivatives from Callistemon salignus, showed both antimicrobial and cytotoxic activities in various adherent human cancer cell lines. Thus, in the present study, a natural acylphloroglucinol (2,6-dihydroxy-4-methoxyisobutyrophenone, L72) was tested for its antiproliferative efficacy in HEL cells. The MTT and the cell cycle analysis study revealed that L72 treatment can offer antiproliferative effects, both time and dose-dependent manner, causing G2/M cell cycle arrest. The western blot analysis revealed that L72 treatment triggered intrinsic apoptotic machinery and activated p21. Likewise, L72 could downregulate the gene expressions of XIAP, FLT3, IDH2, and SOD2, which was demonstrated by qPCR analysis, thus promoting its antiproliferative action. The L72 could impede STAT3 expression, which was evidenced by insilico autodock analysis and western blot analysis using STAT3 inhibitor, Pimozide. The treatment of transgenic (Flk-1+/egfr+) zebrafish embryos resulted in the STAT3 gene inhibition, proving its anti-angiogenic effect, as well. Thus, the study revealed that L72 could act as an antiproliferative agent, by triggering caspase-dependent intrinsic apoptosis, reducing cell proliferation by attenuating STAT3, and activating an anti-angiogenic pathway via Flk-1inhibition.

Incaspitolide A extracted from Carpesium cernuum induces apoptosis in vitro via the PI3K/AKT pathway in benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a common disease that occurs mainly in older men. The pathogenesis of BPH is complex and patients face a prolonged treatment course, and novel drugs with better selectivity and lower toxicity are required. Incaspitolide A (compound TMJ-12) is a germacrane-type sesquiterpenoid compound extracted from the plant Carpesium carnuum. Extracts of C. carnuum are known to exert suppressive effects on BPH-1 cells. In the present study, we investigated the molecular mechanisms underlying the suppressive effect of TMJ-12 specifically on BPH-1 cells. A cytotoxicity assay indicated that TMJ-12 inhibited BPH-1 cell proliferation, while flow cytometry assays showed that TMJ-12 induced G2/M phase cell cycle arrest and the apoptosis of BPH-1 cells. TMJ-12 was also shown to regulate the expression of several apoptosis- and cell cycle-related proteins, namely Bcl-2, Bax, Bad, Caspase-9, Caspase-3, cyclin-dependent kinase 1 (CDK1), Cyclin B1, CDC25C, and c-Myc, among others. Collapse of the mitochondrial membrane potential (ΔΨm) following exposure to TMJ-12 was detected with the JC-1 staining assay. Further investigation revealed that treatment with TMJ-12 inhibited the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway by increasing the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Taken together, the results suggest that TMJ-12 prevents BPH-1 cell proliferation via the PI3K/AKT pathway by inducing apoptosis and cell cycle arrest.

Paris Saponin VII Induces Apoptosis and Cell Cycle Arrest in Erythroleukemia Cells by a Mitochondrial Membrane Signaling Pathway.

BACKGROUND AND PURPOSE: Leukemia is considered a top-listed ailment, according to WHO, which contributes to the death of a major population of the world every year. Paris Saponin VII (PS), a saponin which was isolated from the roots of Trillium kamtschaticum, from our group, was reported to provide hemostatic, cytotoxic and antimicrobial activities. However, its molecular mechanism underlying the anti-proliferative effects remains unclear. Thus, this study hypothesized to assess that mechanism in PS treated HEL cells. METHODS: The MTT assay was used to analyze the PS inhibited cell viability in the HEL cells. We further found that PS could induce S phase cell cycle arrest through flow cytometry as well as the western blot analysis of intrinsic and extrinsic apoptotic molecules. RESULTS: The MTT assay showed the IC50 concentration of PS as 0.667µM. The study revealed that PS treatment inhibits cell proliferation dose-dependently. It further caused mitochondrial membrane potential changes by PS treatment. Mechanistic protein expression revealed a dose-dependent upsurge for Bid and Bim molecules, while Bcl2 and PARP expression levels were significantly (P<0.05) down-regulated in PS treated HEL cells resulting in caspase -3 release and increased the Bim levels upon 24h of incubation. CONCLUSION: These findings indicate that PS possesses an excellent anti-leukemic activity via the regulation of the mitochondrial pathway, leading to S phase cell cycle arrest and caspase-dependent apoptosis, suggesting it as a potential alternative chemotherapeutic agent for leukemia patients.

A natural small molecule induces megakaryocytic differentiation and suppresses leukemogenesis through activation of PKCδ/ERK1/2 signaling pathway in erythroleukemia cells.

Kaempferol-3-O-rhamnoside (KOR) has multiple potency involved in anti-cancer, anti-inflammatory and antibacterial actions. However, the potential roles of KOR and the analogues isolated from the leaves of Cyclocarya paliurus in anti-erythroleukemia remain unclear. In the present study, KOR and the two analogues (Kaempferol-3-O-(4″-O-acetyl-a-L-rhamnopyranoside) (KLR) and (kaempferol-3-O-α-L-(4″-E-p-coumaroyl) rhamnoside) (KCR) were isolated from leaves of Cyclocarya paliurus. Cell viability assay showed that KCR exerted an excellent anti-erythroleukemia activity. We observed that KCR not only significantly increased the percentage of G2 phase and apoptotic cells compared with control group, but also induced megakaryocytic differentiation in HEL and K562 cells by flow cytometry, indicating that KCR might inhibit cell proliferation through inducing differentiation-mediated apoptosis and cell cycle arrest. Mechanism investigation revealed that KCR treatment obviously increased phosphorylation levels of PKCδ and ERK1/2 as well as GATA1 expression. Taken together, these findings demonstrate that KCR induces megakaryocytic differentiation and suppresses leukemogenesis at least partly through activation of PKCδ/ERK1/2 signaling pathway in erythroleukemia cells. KCR may also serve as a promising natural compound for human erythroleukemia treatment.

BW18, a C-21 steroidal glycoside, exerts an excellent anti-leukemia activity through inducing S phase cell cycle arrest and apoptosis via MAPK pathway in K562 cells.

C-21 steroids displayed the activities of immunosuppressive, anti-inflammatory and anti-virus effects by the reports. However, its antitumor effects and molecular mechanism remain unclear. We previously isolated and identified a C-21 steroidal glycoside (BW18) from the root of Cynanchum atratum Bunge. This study was aimed to assess anti-leukemia activity and its underlying mechanism in K562 cells. MTT assay results showed that BW18 inhibited cell viability and proliferation of K562 cells. We also found that BW18 could induce S phase cell cycle arrest and apoptosis. Furthermore, our results demonstrated that BW18 regulated the expression of apoptosis and cell cycle related proteins. Mechanism investigation revealed that the anti-leukemia activity of BW18 may be mediated through MAPK pathway. These findings indicate that BW18 possesses an excellent anti-leukemia activity via regulating MAPK pathway leading to S phase cell cycle arrest and apoptosis, which suggested BW18 could be as a potential alternative therapeutic agent for CML patients.