Pharmacologic targeting of the P-TEFb complex as a therapeutic strategy for chronic myeloid leukemia.

BACKGROUND: The positive transcription elongation factor b (P-TEFb) kinase activity is involved in the process of transcription. Cyclin-dependent kinase 9 (CDK9), a core component of P-TEFb, regulates the process of transcription elongation, which is associated with differentiation and apoptosis in many cancer types. Wogonin, a natural CDK9 inhibitor isolated from Scutellaria baicalensis. This study aimed to investigate the involved molecular mechanisms of wogonin on anti- chronic myeloid leukemia (CML) cells. MATERIALS AND METHODS: mRNA and protein levels were analysed by RT-qPCR and western blot. Flow cytometry was used to assess cell differentiation and apoptosis. Cell transfection, immunofluorescence analysis and co-immunoprecipitation (co-IP) assays were applied to address the potential regulatory mechanism of wogonin. KU-812 cells xenograft NOD/SCID mice model was used to assess and verify the mechanism in vivo. RESULTS: We reported that the anti-CML effects in K562, KU-812 and primary CML cells induced by wogonin were regulated by P-TEFb complex. We also confirmed the relationship between CDK9 and erythroid differentiation via knockdown the expression of CDK9. For further study the mechanism of erythroid differentiation induced by wogonin, co-IP experiments were used to demonstrate that wogonin increased the binding between GATA-1 and FOG-1 but decreased the binding between GATA-1 and RUNX1, which were depended on P-TEFb. Also, wogonin induced apoptosis and decreased the mRNA and protein levels of MCL-1 in KU-812 cells, which is the downstream of P-TEFb. In vivo studies showed wogonin had good anti-tumor effects in KU-812 xenografts NOD/ SCID mice model and decreased the proportion of human CD45+ cells in spleens of mice. We also verified that wogonin exhibited anti-CML effects through modulating P-TEFb activity in vivo. CONCLUSIONS: Our study indicated a special mechanism involving the regulation of P-TEFb kinase activity in CML cells, providing evidences for further application of wogonin in CML clinical treatment. Video Abstract.

LW-213 induces cell apoptosis in human cutaneous T-cell lymphomas by activating PERK-eIF2α-ATF4-CHOP axis.

Cutaneous T-cell lymphoma (CTCL) is characterized by a heterogeneous group of extranodal non-Hodgkin lymphomas, in which monoclonal T lymphocytes infiltrate the skin. LW-213, a derivative of wogonin, was found to induce cell apoptosis in chronic myeloid leukemia (CML). In this study, we investigated the effects of LW-213 on CTCL cells and the underlying mechanisms. We showed that LW-213 (1-25 µM) dose-dependently inhibited human CTCL cell lines (Hut-102, Hut-78, MyLa, and HH) with IC50 values of around 10 µM, meanwhile it potently inhibited primary leukemia cells derived from peripheral blood of T-cell lymphoma patients. We revealed that LW-213-induced apoptosis was accompanied by ROS formation and the release of calcium from endoplasmic reticulum (ER) through IP3R-1channel. LW-213 selectively activated CHOP and induced apoptosis in Hut-102 cells via activating PERK-eIF2α-ATF4 pathway. Interestingly, the degree of apoptosis and expression of ER stress-related proteins were alleviated in the presence of either N-acetyl cysteine (NAC), an ROS scavenger, or 2-aminoethyl diphenylborinate (2-APB), an IP3R-1 inhibitor, implicating ROS/calcium-dependent ER stress in LW-213-induced apoptosis. In NOD/SCID mice bearing Hut-102 cell line xenografts, administration of LW-213 (10 mg/kg, ip, every other day for 4 weeks) markedly inhibited the growth of Hut-102 derived xenografts and prolonged survival. In conclusion, our study provides a new insight into the mechanism of LW-213-induced apoptosis, suggesting the potential of LW-213 as a promising agent against CTCL.

LW-213, a newly synthesized flavonoid, induces G2/M phase arrest and apoptosis in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell neoplasm characterized by an uncontrolled proliferation of moderately and well differentiated cells of the granulocytic lineage. LW-213, a newly synthesized flavonoid compound, was found to exert antitumor effects against breast cancer through inducing G2/M phase arrest. We investigated whether LW-213 exerted anti-CML effects and the underlying mechanisms. We showed that LW-213 inhibited the growth of human CML cell lines K562 and imatinid-resistant K562 (K562r) in dose- and time-dependent manners with IC50 values at the low µmol/L levels. LW-213 (5, 10, 15 µM) caused G2/M phase arrest of K562 and K562r cells via reducing the activity of G2/M phase transition-related proteins Cyclin B1/CDC2 complex. LW-213 treatment induced apoptosis of K562 and K562r cells via inhibiting the expression of CDK9 through lysosome degradation, thus leading to the suppression of RNAPII phosphorylation, down-regulation of a short-lived anti-apoptic protein MCL-1. The lysosome inhibitor, NH4Cl, could reverse the anti-CML effects of LW-213 including CDK9 degradation and apoptosis. LW-213 treatment also degraded the downstream proteins of BCR-ABL1, such as oncoproteins AKT, STAT3/5 in CML cells, which was blocked by NH4Cl. In primary CML cells and CD34+ stem cells, LW-213 maintained its pro-apoptotic activity. In a K562 cells-bearing mice model, administration of LW-213 (2.5, 5.0 mg/kg, ip, every other day for 4 weeks) dose-dependently prolonged the survival duration, and significantly suppressed huCD45+ cell infiltration and expression of MCL-1 in spleens. Taken together, our results demonstrate that LW-213 may be an efficient agent for CML treatment.

Mitotic catastrophe and p53-dependent senescence induction in T-cell malignancies exposed to nonlethal dosage of GL-V9.

Mitotic catastrophe of cancer cells induced by drugs is characterized by low dosage and low toxicity, representing a significant advantage in the cancer treatment. Effective therapeutic options are limited for T-cell malignancies patients who are still treated by high-dose multiagent chemotherapy, potentially followed by hematopoietic stem cell transplantation, highlighting the urgency for identification of more effective anti-T-cell malignancies drugs. The use of antineoplastic drugs which induced tumor cell mitotic catastrophe would be a new strategy for cancer therapy. Nevertheless, there is still no effective mitotic catastrophe agent in T-cell malignancies. Our study showed that nonlethal dosage (ND) of GL-V9 (5-hydroxy-8-methoxy-2-phenyl-7-(4-(pyrrolidin-1-yl) butoxy) 4 H-chromen-4-one) (2 µM), a potential anticancer drug, not only attenuated cell growth and survival, but also arrested the cell cycle in G2/M phase and induced multipolar spindles, nuclear alterations (micronucleation and multinucleation), which are the most prominent morphological characteristics of mitotic catastrophe, in T-cell malignancies cell lines including Jurkat, HuT-102, and HuT-78. Moreover, ND GL-V9 could trigger DNA damage, and significantly influence several mitosis-associated proteins. Besides, results showed that ND GL-V9 increased the activity of senescence-associated ß-galactosidase (SA-ß-Gal) following the induction of mitotic catastrophe in Jurkat and HuT-102 cells with intact p53, while causing apoptosis in p53-deficient HuT-78 cells. We concluded that the anti-T-cell malignancies effects of ND GL-V9 and clarified the precise regulation in the process of mitosis under the action of GL-V9 in T-cell malignancies. Our data provided new evidence for the study of T-cell malignancies treatment associated with mitotic catastrophe and cellular senescence induction.

Targeting lysosomal HSP70 induces acid sphingomyelinase-mediated disturbance of lipid metabolism and leads to cell death in T cell malignancies.

BACKGROUND: T cell malignancies proliferate vigorously, are highly dependent on lysosomal function, with limited therapeutic options. Deregulation of lysosomal structure and function has been confirmed to be a key role in the treatment of hematologic malignant disease. METHODS: Cell counting kit 8 and Annexin V/PI staining were used to assess the cell viability and apoptosis rate. Flow cytometry, liquid chromatography mass spectrometry, immunofluorescence and western blot were performed to detect the effect on lysosomes. Drug affinity responsive target stability, molecular docking and cellular thermal shift assay were employed to confirm the target protein of V8 on lysosomes. A xenograft model was constructed in NOD/SCID mice to assess the effect and mechanism. RESULTS: V8, a new lysosomotropic compound, could be rapidly trapped by lysosomes and accumulation in lysosomes, contributing to lysosomal-dependent cell death by evoking lysosomal membrane permeabilization (LMP), accompanied with disrupted lysosome and autophagic flux. Mechanistically, heat shock protein 70 (HSP70) was identified as the binding target of V8 in lysosome. As a downstream effect of targeting HSP70, enzymatic activity of acid sphingomyelinase (ASM) was inhibited, which induced disturbance of lipid metabolism, instability of lysosomal membrane, and leakage of cathepsin B and D, leading to LMP-mediated cell death. In vivo study showed V8 well controlled the growth of the tumour and confirmed lysosomal cell death induced by V8. CONCLUSIONS: Collectively, this study suggests targeting lysosomal HSP70-ASM axis by V8 illustrates the great value of drug therapy for T cell malignancies and the unlimited potential of lysosomal targeting for cancer therapy.

Lysosomal membrane permeabilization mediated apoptosis involve in perphenazine-induced hepatotoxicity in vitro and in vivo.

Antipsychotic drugs represent a class of lysosomotropic drugs widely used in clinical practice. However, the hepatotoxicity of these drugs has been reported in recent years. Therefore, understanding the changes in cellular homeostasis mediated by these drugs is of great significance for revealing the true mechanisms underlying hepatotoxicity. Perphenazine is a classical antipsychotic drug that can reportedly induce extrapyramidal and sympatholytic side effects. The present research focuses on the toxicity effect of perphenazine on normal human hepatocytes. To assess the hepatotoxicity of continuous administration of perphenazine and investigate potential mechanisms related to apoptosis, human normal L02 hepatocytes were exposed to 10-40 µM perphenazine in vitro. The results showed that perphenazine inhibited cell viability in a concentration and time-dependent manner. Furthermore, 30 µM perphenazine induced intense lysosome vacuolation, impaired lysosomal membrane, and induced lysosomal membrane permeabilization (LMP), ultimately triggering lysosomal cell death in L02 cells. Knockdown cathepsin D(CTSD) also ameliorated perphenazine-induced liver injury via the inhibition of LMP. In vivo, ICR mice received intragastric administration of 10-180 mg/kg B.W. perphenazine every other day for 21 days. 180 mg/kg perphenazine significantly increased histological injury and aminotransferases compared with control. Taken together, our findings suggest that perphenazine can trigger hepatotoxicity through lysosome disruption both in vitro and in vivo.

Cholesterol-associated lysosomal disorder triggers cell death of hematological malignancy: Dynamic analysis on cytotoxic effects of LW-218.

The integrity of lysosomes is of vital importance to survival of tumor cells. We demonstrated that LW-218, a synthetic flavonoid, induced rapid lysosomal enlargement accompanied with lysosomal membrane permeabilization in hematological malignancy. LW-218-induced lysosomal damage and lysosome-dependent cell death were mediated by cathepsin D, as the lysosomal damage and cell apoptosis could be suppressed by depletion of cathepsin D or lysosome alkalization agents, which can alter the activity of cathepsins. Lysophagy, was initiated for cell self-rescue after LW-218 treatment and correlated with calcium release and nuclei translocation of transcription factor EB. LW-218 treatment enhanced the expression of autophagy-related genes which could be inhibited by intracellular calcium chelator. Sustained exposure to LW-218 exhausted the lysosomal capacity so as to repress the normal autophagy. LW-218-induced enlargement and damage of lysosomes were triggered by abnormal cholesterol deposition on lysosome membrane which caused by interaction between LW-218 and NPC intracellular cholesterol transporter 1. Moreover, LW-218 inhibited the leukemia cell growth in vivo. Thus, the necessary impact of integral lysosomal function in cell rescue and death were illustrated.

One-Two Punch Therapy for the Treatment of T-Cell Malignancies Involving p53-Dependent Cellular Senescence.

T-cell malignancies are still difficult to treat due to a paucity of plans that target critical dependencies. Drug-induced cellular senescence provides a permanent cell cycle arrest during tumorigenesis and cancer development, particularly when combined with senolytics to promote apoptosis of senescent cells, which is an innovation for cancer therapy. Here, our research found that wogonin, a well-known natural flavonoid compound, not only had a potential to inhibit cell growth and proliferation but also induced cellular senescence in T-cell malignancies with nonlethal concentration. Transcription activity of senescence-suppression human telomerase reverse transcriptase (hTERT) and oncogenic C-MYC was suppressed in wogonin-induced senescent cells, resulting in the inhibition of telomerase activity. We also substantiated the occurrence of DNA damage during the wogonin-induced aging process. Results showed that wogonin increased the activity of senescence-associated ß-galactosidase (SA-ß-Gal) and activated the DNA damage response pathway mediated by p53. In addition, we found the upregulated expression of BCL-2 in senescent T-cell malignancies because of the antiapoptotic properties of senescent cells. Following up this result, we identified a BCL-2 inhibitor Navitoclax (ABT-263), which was highly effective in decreasing cell viability and inducing apoptotic cell death in wogonin-induced senescent cells. Thus, the "one-two punch" approach increased the sensibility of T-cell malignancies with low expression of BCL-2 to Navitoclax. In conclusion, our research revealed that wogonin possesses potential antitumor effects based on senescence induction, offering a better insight into the development of novel therapeutic methods for T-cell malignancies.

FV-429 induces autophagy blockage and lysosome-dependent cell death of T-cell malignancies via lysosomal dysregulation.

It is widely accepted that lysosomes are essential for cell homeostasis, and autophagy plays an important role in tumor development. Here, we found FV-429, a synthetic flavonoid compound, inhibited autophagy flux, promoted autophagosomes accumulation, and inhibited lysosomal degradation in T-cell malignancies. These effects were likely to be achieved by lysosomal dysregulation. The destructive effects of FV-429 on lysosomes resulted in blockage of lysosome-associated membrane fusion, lysosomal membrane permeabilization (LMP), and cathepsin-mediated caspase-independent cell death (CICD). Moreover, we initially investigated the effects of autophagy inhibition by FV-429 on the therapeutic efficacy of chemotherapy and found that FV-429 sensitized cancer cells to chemotherapy agents. Our findings suggest that FV-429 could be a potential novel autophagy inhibitor with notable antitumor efficacy as a single agent.

Natural HDAC-1/8 inhibitor baicalein exerts therapeutic effect in CBF-AML.

BACKGROUND: Although targeting histone deacetylases (HDACs) may be an effective strategy for core binding factor-acute myeloid leukemia (CBF-AML) harboring t(8;21) or inv(16), HDAC inhibitors are reported to be limited by drug-resistant characteristic. Our purpose is to evaluate the anti-leukemia effects of Baicalein on CBF-AML and clarify its underlying mechanism. METHODS: Enzyme activity assay was used to measure the activity inhibition of HDACs. Rhodamine123 and RT-qPCR were employed to evaluate the distribution of drugs and the change of ATP-binding cassette (ABC) transporter genes. CCK8, Annexin V/PI, and FACS staining certified the effects of Baicalein on cell growth, apoptosis, and differentiation. Duolink and IP assay assessed the interaction between HDAC-1 and ubiquitin, HSP90 and AML1-ETO, and Ac-p53 and CBFß-MYH11. AML cell lines and primary AML cells-bearing NOD/SCID mice models were used to evaluate the anti-leukemic efficiency and potential mechanism of Baicalein in vivo. RESULTS: Baicalein showed HDAC-1/8 inhibition to trigger growth suppression and differentiation induction of AML cell lines and primary AML cells. Although the inhibitory action on HDAC-1 was mild, Baicalein could induce the degradation of HDAC-1 via ubiquitin proteasome pathway, thereby upregulating the acetylation of Histone H3 without promoting ABC transporter genes expression. Meanwhile, Baicalein increased the acetylation of HSP90 and lessened its connection to AML1/ETO, consequently leading to degradation of AML1-ETO in t(8;21)q(22;22) AML cells. In inv(16) AML cells, Baicalein possessed the capacity of apoptosis induction accompanied with p53-mediated apoptosis genes expression. Moreover, CBFß-MYH11-bound p53 acetylation was restored via HDAC-8 inhibition induced by Baicalein contributing the diminishing of survival of CD34+  inv(16) AML cells. CONCLUSIONS: These findings improved the understanding of the epigenetic regulation of Baicalein, and warrant therapeutic potential of Baicalein for CBF-AML.

Involvement of p53 Acetylation in Growth Suppression of Cutaneous T-Cell Lymphomas Induced by HDAC Inhibition.

Cutaneous T-cell lymphomas (CTCLs) represent a rare form of non-Hodgkin lymphomas characterized by an accumulation of malignant CD4+ T cells in the skin. TP53 genetic alteration is one of the most prevalent genetic abnormalities in CTCLs. Therefore, it is a promising target for innovative therapeutic approaches. We found that p53 could physically interact with histone deacetylase (HDAC) 1 and HDAC8, and was subsequently deacetylated to lose its function in CTCL cells, and the p53 downstream apoptosis-associated genes were repressed. Thus, the anti-CTCL activity displayed by HDAC inhibitors depends on p53 status. However, recent studies have reported that HDAC inhibitors could induce a wide variety of drug-resistant characteristics in cancer cells by regulating ATP-binding cassette transporters. Moreover, we discovered that Baicalein, a natural product, exhibited an inhibitory effect on HDAC1 and HDAC8. Though the inhibition of HDAC1 was mild, Baicalein could induce the degradation of HDAC1 through the ubiquitin proteasome pathway, thereby markedly upregulating the acetylation of histone H3 without promoting ATP-binding cassette transporter gene expression. In terms of the mechanism, Baicalein showed better growth inhibition than traditional HDAC inhibitors in CTCLs. This study indicates a special mechanism of HDAC1 and HDAC8 and p53 in T-cell lymphoma cells and identifies a potential and safe natural HDAC inhibitor for the treatment of CTCLs.

GL-V9 exerts anti-T cell malignancies effects via promoting lysosome-dependent AKT1 degradation and activating AKT1/FOXO3A/BIM axis.

T-cell malignancies are characterized by the excessive proliferation of hematopoietic precursor cells of T-cell lineage lymphocytes in the bone marrow. Previous studies suggest that T-cell malignancies are usually accompanied by highly activated PI3K/AKT signaling which confers the ability of cancer cells to proliferate and survive. Here, we found that GL-V9, a newly synthesized flavonoid compound, had a potent to inhibit the activation of AKT1 and induce the cell apoptosis in T-cell malignancies including cell lines and primary lymphoblastic leukemia. Results showed that GL-V9-induced degradation of AKT1 blocked PI3K/AKT1 signaling and the degradation of AKT1 could be reversed by NH4Cl, an inhibitor of lysosomal function. Inhibiting AKT1 promoted dephosphorylation of FOXO3A and its nuclear translocation. We further demonstrated that GL-V9-induced apoptosis effects were dependent on the binding of FOXO3A to the BIM promoter, resulting in the production of BH3-only protein BIM. Moreover, GL-V9 showed a more persistent and stronger apoptosis induction effects than pharmacologic PI3K inhibitor. The in vivo studies also verified that GL-V9 possessed the anti-tumor effects by reducing the leukemic burden in T-ALL-bearing BALB/c nude mice. In conclusion, our study provides a new insight into the mechanism of GL-V9-induced apoptosis, suggesting the potency of GL-V9 to be a promising agent against T-cell malignancies.