Stilbenoids and Flavonoids from Cajanus cajan (L.) Millsp. and Their α-Glucosidase Inhibitory Activities.

Two new stilbenoids, cajanstilbenoid C (1) and cajanstilbenoid D (2), together with eight other known stilbenoids (3-10) and seventeen known flavonoids (11-27), were isolated from the petroleum ether and ethyl acetate portions of the 95% ethanol extract of leaves of Cajanus cajan (L.) Millsp. The planar structures of the new compounds were elucidated by NMR and high-resolution mass spectrometry, and their absolute configurations were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) values. All the compounds were assayed for their inhibitory activities against yeast α-glucosidase. The results demonstrated that compounds 3, 8-9, 11, 13, 19-21, and 24-26 had strong inhibitory activities against α-glucosidase, with compound 11 (IC50 = 0.87 ± 0.05 µM) exhibiting the strongest activity. The structure-activity relationships were preliminarily summarized. Moreover, enzyme kinetics showed that compound 8 was a noncompetitive inhibitor, compounds 11, 24-26 were anticompetitive, and compounds 9 and 13 were mixed-competitive.

Synthetic flavagline derivative 1-chloroacetylrocaglaol promotes apoptosis in K562 erythroleukemia cells through miR-17-92 cluster genes.

Chronic myeloid leukemia accounts for human deaths worldwide and could enhance sevenfold by 2050. Thus, the treatment regimen for this disorder is highly crucial at this time. Flavaglines are a natural class of cyclopentane benzofurans exhibiting various bioactivities like anticancer action. Despite the antiproliferative activity of flavaglines against diverse cancer cells, their roles and mechanism of action in chronic myeloid leukemia (CML) remain poorly understood. Thus, this study examines the antiproliferative effect of a newly synthesized flavagline derivative, 1-chloracetylrocaglaol (A2074), on erythroleukemia K562 cells and the zebrafish xenograft model. The study revealed that A2074 could inhibit proliferation, promote apoptosis, and boost megakaryocyte differentiation of K562 cells. This flavagline downregulated c-MYC and miR-17-92 cluster genes, targeting upregulation of the apoptotic protein Bcl-2-like protein 11 (BIM). The work uncovered a critical role of the c-MYC-miR-17-92-BIM axis in the growth and survival of CML cells.

Erythropoietin Signaling in the Microenvironment of Tumors and Healthy Tissues.

Erythropoietin (EPO), the primary cytokine of erythropoiesis, stimulates both proliferation and differentiation of erythroid progenitors and their maturation to red blood cells. Basal EPO levels maintain the optimum levels of circulating red blood cells. However, during hypoxia, EPO secretion and its expression is elevated drastically in renal interstitial fibroblasts, thereby increasing the number of erythroid progenitors and accelerating their differentiation to mature erythrocytes. A tight regulation of this pathway is therefore of paramount importance. The biological response to EPO is commenced through the involvement of its cognate receptor, EPOR. The receptor-ligand complex results in homodimerization and conformational changes, which trigger downstream signaling events and cause activation or inactivation of critical transcription factors that promote erythroid expansion. In recent years, recombinant human EPO (rEPO) has been widely used as a therapeutic tool to treat a number of anemias induced by infection, and chemotherapy for various cancers. However, several studies have uncovered a tumor promoting ability of EPO in man, which likely occurs through EPOR or alternative receptor(s). On the other hand, some studies have demonstrated a strong anticancer activity of EPO, although the mechanism still remains unclear. A thorough investigation of EPOR signaling could yield enhanced understanding of the pathobiology for a variety of disorders, as well as the potential novel therapeutic strategies. In this chapter, in addition to the clinical relevance of EPO/EPOR signaling, we review its anticancer efficacy within various tumor microenvironments.

A New Indole Derivative, LWX-473, Overcomes Glucocorticoid Resistance in Jurkat Cells by Activating Mediators of Apoptosis.

BACKGROUND: Glucocorticoids (GCs) are commonly used as the primary chemotherapy for lymphoid malignancies, including acute lymphoblastic leukemia (ALL). However, the development of GC resistance limits their prolonged use. METHODS: In this study, we investigated the potential of a newly synthesized indole derivative called LWX-473, in combination with the classic GC Dexamethasone (DEX), to enhance the responsiveness of Jurkat cells to GC treatment. RESULTS: Our findings demonstrate that LWX-473 alone or in combination with DEX significantly improves GC-induced cell apoptosis and arrests the cell cycle in the G1 phase. Notably, the combination of LWX-473 and DEX exhibits superior efficacy in killing Jurkat cells compared to LWX-473 alone. Importantly, this compound demonstrates reduced toxicity towards normal cells. CONCLUSIONS: Our study reveals that LWX-473 has the ability to restore the sensitivity of Jurkat cells to DEX by modulating the mitochondrial membrane potential, activating the expression of DEX-liganded glucocorticoid receptor (GR), and inhibiting key molecules in the JAK/STAT signaling pathway. These findings suggest that LWX-473 could be a potential therapeutic agent for overcoming GC resistance in lymphoid malignancies.

B4 suppresses lymphoma progression by inhibiting fibroblast growth factor binding protein 1 through intrinsic apoptosis.

Lymphoma positions as the fifth most common cancer, in the world, reporting remarkable deaths every year. Several promising strategies to counter this disease recently include utilizing small molecules that specifically target the lymphoma cellular proteins to overwhelm its progression. FGFBP1 is a soluble intracellular protein that progresses cancer cell proliferation and is upregulated in several cancers. Therefore, inhibiting FGFBP1 could significantly slow down lymphoma progression through triggering apoptosis. Thus, in this study, a flavonoid B4, isolated from Cajanus cajan, has been investigated for its effects of B4 on lymphoma, specifically as an FGFBP1 inhibitor. B4 could selectively hinder the growth of lymphoma cells by inducing caspase-dependent intrinsic apoptosis through G1/S transition phase cell cycle arrest. RNA sequencing analysis revealed that B4 regulates the genes involved in B-cell proliferation and DNA replication by inhibiting FGFBP1 in vitro. B4 increases the survival rate of lymphoma mice. B4 also represses the growth of patient-derived primary lymphoma cells through FGFBP1 inhibition. Drug affinity responsive target stability experimentations authorize that B4 powerfully binds to FGFBP1. The overexpression of FGFBP1 raises the pharmacological sensitivity of B4, supplementing its specific action on lymphoma cells. This study pioneers the estimation of B4 as a possible anticancer agent for lymphoma treatment. These outcomes highlight its selective inhibitory effects on lymphoma cell growth by downregulating FGFBP1 expression through intrinsic apoptosis, causing mitochondrial and DNA damage, ultimately leading to the inhibition of lymphoma progression. These suggest B4 may be a novel FGFBP1 inhibitor for the lymphoma treatment.

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.

Garmultin-A Incites Apoptosis in CB3 Cells Through miR-17-5p by Attenuating Poly (ADP-Ribose) Polymerase-1.

Background: Leukemia accounts for a large number of deaths, worldwide, every year. Treating this ailment is always a challenging job. Recently, oncogenic miRNA leading to apoptosis are highly promising targets of many natural products. In this study, Garmultin-A (GA), isolated from the bark of Garcinia multiflora, was elucidated for its anti-leukemic effect in CB3 cells. Methods: The effect of the compound on CB3 cell viability was detected by MTT assay and apoptosis by FITC Annexin V/PI and Hochest 33258 staining. The western blot analysis assessed the BAX, BCL2, cMYC, pERK, and PARP-1 protein levels. Autodock analysis predicted the ligand-protein interactions. q-RT-PCR quantified the miR-17-5p expression. Luciferase assay confirmed the interaction between PARP-1 and miR-17-5p. Results: We uncover that GA leads to apoptosis by inducing overexpression of miR-17-5p and significantly downregulate PARP-1 protein levels in CB3 cells. The overexpression of miR-17-5p promotes apoptosis, and the miR-17-5p antagomirs restore GA-triggered apoptosis. Notably, we disclose that PARP-1 is a direct target of miR-17-5p. Increased pro-apoptotic and reduced anti-apoptosis protein levels were also observed in GA-treated CB3 cells. Conclusion: These results provide critical insights that GA could induce apoptosis in CB3 cells through targeting miR-17-5p by attenuating PARP-1. Thus, GA could act as a novel therapeutic agent for erythroleukemia.

Stilbene B10 induces apoptosis and tumor suppression in lymphoid Raji cells by BTK-mediated regulation of the KRAS/HDAC1/EP300/PEBP1 axis.

Lymphoma is a cancer of the lymphoid cells that originated in matured B or T cells. The bioactive natural compounds can efficiently treat this disease with lesser side effects. Thus, in this study, a natural stilbene B10 (3-methoxy 5-hydroxy stilbene) isolated from Cajanus cajan (Pigeon Pea) was screened for its anti-proliferative efficacy against 13 cancer cell lines. B10 showed a potential effect on the human lymphoma (Raji) cells. Cytotoxicity analysis of B10 has revealed IC50 concentrations in Raji cells at low doses (18 µM) than other cancer cell lines. The B10 could significantly cause dose and time-dependent inhibition in the proliferation of Raji cells triggering intrinsic apoptosis and S/G1 phase cellular arrest. There was an increased expression of phospho-γ-H2A.X and decreased expression of cyclin D1, causing DNA damage and cell cycle arrest, post- B10 treatments. The mitochondrial membrane potential (MMP) variations observed after B10 treatment led to changes in Bax/Bcl-2 ratio, cytochrome C release, and enhanced expression of cleaved caspase3, 9, PARP-1, and APAF-1. The B10 inhibited the proliferation of Raji cells by significantly downregulating the expression of KRAS, BTK, MDM2, P-JAK2, P-STAT3, PI3K, HDAC1/2, SIRT7, and EP300. The treatment upregulated the tumor suppressor genes PEBP1 and SAP18. Thus, the study could reveal the selective inhibitory effects of B10 on lymphoma, suggesting it as a probable innovative chemotherapeutic agent.

UM171 cooperates with PIM1 inhibitors to restrict HSC expansion markers and suppress leukemia progression.

The pyrimido-indole derivative UM171 promotes human Hematopoietic Stem Cells Expansion (HSCE), but its impact on leukemia is not known. Herein, we show in a mouse model of erythroleukemia that UM171 strongly suppresses leukemia progression. UM171 inhibits cell cycle progression and apoptosis of leukemic cells in culture. The effect of UM171 on leukemia differentiation was accompanied by increased expression of HSCE markers. RNAseq analysis combined with Q-RT-PCR and western blotting revealed that the PIM1 protein kinase is highly elevated in response to UM171 treatment. Moreover, docking analysis combined with immunoprecipitation assays revealed high binding affinity of UM171 to PIM1. Interestingly, pan-PIM kinase inhibitors counteracted the effect of UM171 on HSCE marker expression and PIM1 transcription, but not its suppression of leukemic cell growth. Moreover, combination treatment with UM171 and a pan-PIM inhibitor further suppressed leukemic cell proliferation compared to each drug alone. To uncover the mechanism of growth inhibition, we showed strong upregulation of the cyclin-dependent kinase inhibitor P21CIP1 and the transcription factor KLF2 by UM171. In accordance, KLF2 knockdown attenuated growth inhibition by UM171. KLF2 upregulation by UM171 is also responsible for the activation of P21CIP1 in leukemic cells leading to a G1/S arrest and suppression of leukemogenesis. Thus, suppression of leukemic growth by UM171 through KLF2 and P21CIP1 is thwarted by PIM-mediated expansion of leukemic stemness, uncovering a novel therapeutic modality involving combined UM171 plus PIM inhibitors.

An immunotherapeutic approach to decipher the role of long non-coding RNAs in cancer progression, resistance and epigenetic regulation of immune cells.

Immunotherapeutic treatments are gaining attention due to their effective anti-tumor response. Particularly, the revolution of immune checkpoint inhibitors (ICIs) produces promising outcomes for various cancer types. However, the usage of immunotherapy is limited due to its low response rate, suggesting that tumor cells escape the immune surveillance. Rapid advances in transcriptomic profiling have led to recognize immune-related long non-coding RNAs (LncRNAs), as regulators of immune cell-specific gene expression that mediates immune stimulatory as well as suppression of immune response, indicating LncRNAs as targets to improve the efficacy of immunotherapy against tumours. Moreover, the immune-related LncRNAs acting as epigenetic modifiers are also under deep investigation. Thus, herein, is a summarised knowledge of LncRNAs and their regulation in the adaptive and innate immune system, considering their importance in autophagy and predicting putative immunotherapeutic responses.

Ubash3b promotes TPA-mediated suppression of leukemogenesis through accelerated downregulation of PKCδ protein.

Acquired drug-resistance, often involving downregulation or mutations in the target protein, is a major caveat in precision medicine. Understanding mechanisms of resistance to therapeutic drugs may unravel strategies to overcome or prevent them. We previously identified phorbol ester (PE) compounds such as TPA that induce Protein Kinase δ (PKCδ), thereby suppressing leukemogenesis. Here we identified erythroleukemia cell lines that resist PEs and showed that reduced PKCδ protein expression underlies drug resistance. Reduced level of PKCδ in resistant cell lines was due to its phosphorylation followed by protein degradation. Indeed, proteasome inhibition prevented PE-induced loss of PKCδ. Accordingly, a combination of TPA and the proteasome inhibitor ALLN significantly suppressed leukemia in a mouse model of leukemia. PKCδ downregulation by TPA was independent of the downstream MAPK/ERK/P38/JNK pathway. Instead, expression of ubiquitin-associated and SH3 domain-containing protein b (Ubash3b) was induced by TPA, which leads to PKCδ protein dephosphorylation and degradation. This specific degradation was blocked by RNAi-mediated depletion of Ubash3b. In drug-sensitive leukemic cells, TPA did not induce Ubash3b, and consequently, PKCδ levels remained high. A PE-resistant cell line derived from PE-treated sensitive cells exhibited very low PKCδ expression. In these drug resistance cells, a Ubash3b independent mechanism led to PKCδ degradation. Thus, PE compounds in combination with proteasome or specific inhibitors for Ubash3b, or other factors can overcome resistance to TPA, leading to durable suppression of leukemic growth. These results identify Ubash3b as a potential target for drug development.

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.

L20, a Calothrixin B analog, induces intrinsic apoptosis on HEL cells through ROS/γ-H2AX/p38 MAPK pathway.

Erythroleukemia is a malignant disease in the blood system. Quinones consists of a class of antitumor agents. Calothrixin B is a carbazole-1,4-quinone alkaloid isolated from Calothrix cyanobacteria with a unique indolo[3,2-j] phenanthridine framework. This study aimed to investigate the anti-leukemic effect of the new Calothrixin B derivative, L20, and to dig up the underlying mechanisms. Cytotoxicity analysis of L20 has revealed that it shows significant IC50 concentrations in HEL cells at low doses (1.10 ± 0.05 µM) than in K562, and KG-1a (5.46 ± 3.09, and 1.82 ± 1.08 µM respectively). The study even revealed that the L20 could induce a dose and time-dependent cellular death in HEL cells. The L20 increased expression of phospho-γ-H2A.X and phospho-p38 in HEL cells, causing DNA damage and nuclear alterations due to the G2/M phase cell cycle arrest. The HEL cells even lost the mitochondrial membrane potential (MMP) and resulted in the release of reactive oxygen species (ROS). Additionally, L20 inhibited the proliferation of HEL cells by inducing apoptosis through the mitochondrial pathway, depending on the caspase family. The study even established this may be due to the upregulation of the p-P38MAPK and downregulation of p-ERK. Pretreatment with P38/ERK inhibitors, SB203580, and U0126, decreased L20-induced apoptosis. These findings indicated that L20 induced mitochondrial mediated-apoptosis and G2/M arrest through DNA damage and modulation of p38 MAPK pathways. Thus, the study suggests L20, a chemical analog of Calothrixin B, as a novel chemotherapeutic agent against erythroleukemia.

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.

A C21-steroidal derivative suppresses T-cell lymphoma in mice by inhibiting SIRT3 via SAP18-SIN3.

The SIN3 repressor complex and the NAD-dependent deacetylase SIRT3 control cell growth, and development as well as malignant transformation. Even then, a little known about cross-talks between these two chromatin modifiers or whether their interaction explored therapeutically. Here we describe the identification of a C21-steroidal derivative compound, 3-O-chloroacetyl-gagamine, A671, which potently suppresses the growth of mouse and human T-cell lymphoma and erythroleukemia in vitro and preclinical models. A671 exerts its anti-neoplastic effects by direct interaction with Histone deacetylase complex subunit SAP18, a component of the SIN3 suppressor complex. This interaction stabilizes and activates SAP18, leading to transcriptional suppression of SIRT3, consequently to inhibition of proliferation and cell death. The resistance of cancer cells to A671 correlated with diminished SAP18 activation and sustained SIRT3 expression. These results uncover the SAP18-SIN3-SIRT3 axis that can be pharmacologically targeted by a C21-steroidal agent to suppress T-cell lymphoma and other malignancies.