Combined effect of Hsp90 inhibitor geldanamycin and parthenolide via reactive oxygen species-mediated apoptotic process on epithelial ovarian cancer cells

The therapeutic effect and mechanism of parthenolide in skeletal disease, cancers, and cytokine storm

Parthenolide (PTL or PAR) was first isolated from Magnolia grandiflora and identified as a small molecule cancer inhibitor. PTL has the chemical structure of C15H20O3 with characteristics of sesquiterpene lactones and exhibits the biological property of inhibiting DNA biosynthesis of cancer cells. In this review, we summarise the recent research progress of medicinal PTL, including the therapeutic effects on skeletal diseases, cancers, and inflammation-induced cytokine storm. Mechanistic investigations reveal that PTL predominantly inhibits NF-κB activation and other signalling pathways, such as reactive oxygen species. As an inhibitor of NF-κB, PTL appears to inhibit several cytokines, including RANKL, TNF-α, IL-1β, together with LPS induced activation of NF-κB and NF-κB -mediated specific gene expression such as IL-1β, TNF-α, COX-2, iNOS, IL-8, MCP-1, RANTES, ICAM-1, VCAM-1. It is also proposed that PTL could inhibit cytokine storms or hypercytokinemia triggered by COVID-19 via blocking the activation of NF-κB signalling. Understanding the pharmacologic properties of PTL will assist us in developing its therapeutic application for medical conditions, including arthritis, osteolysis, periodontal disease, cancers, and COVID-19-related disease.

Regulation of ROS-Dependent JNK Pathway by 2'-Hydroxycinnamaldehyde Inducing Apoptosis in Human Promyelocytic HL-60 Leukemia Cells

The present study demonstrated that 2'-hydroxycinnamaldehyde (2'-HCA) induced apoptosis in human promyelocytic leukemia HL-60 cells through the activation of mitochondrial pathways including (1) translocation of Bim and Bax from the cytosol to mitochondria, (2) downregulation of Bcl-2 protein expression, (3) cytochrome c release into the cytosol, (4) loss of mitochondrial membrane potential (ΔΨ_m), and (5) caspase activation. 2'-HCA also induced the activation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase1/2 (ERK1/2) in HL-60 cells. The pharmacological and genetic inhibition of JNK effectively prevented 2'-HCA-induced apoptosis and activator protein-1 (AP-1)-DNA binding. In addition, 2'-HCA resulted in the accumulation of reactive oxygen species (ROS) and depletion of intracellular glutathione (GSH) and protein thiols (PSH) in HL-60 cells. NAC treatment abrogated 2'-HCA-induced JNK phosphorylation, AP-1-DNA binding, and Bim mitochondrial translocation, suggesting that oxidative stress may be required for 2'-HCA-induced intrinsic apoptosis. Xenograft mice inoculated with HL-60 leukemia cells demonstrated that the intraperitoneal administration of 2'-HCA inhibited tumor growth by increasing of TUNEL staining, the expression levels of nitrotyrosine and pro-apoptotic proteins, but reducing of PCNA protein expression. Taken together, our findings suggest that 2'-HCA induces apoptosis via the ROS-dependent JNK pathway and could be considered as a potential therapeutic agent for leukemia.

Parthenolide as Cooperating Agent for Anti-Cancer Treatment of Various Malignancies

Primary and acquired resistance of cancer to therapy is often associated with activation of nuclear factor kappa B (NF-κB). Parthenolide (PN) has been shown to inhibit NF-κB signaling and other pro-survival signaling pathways, induce apoptosis and reduce a subpopulation of cancer stem-like cells in several cancers. Multimodal therapies that include PN or its derivatives seem to be promising approaches enhancing sensitivity of cancer cells to therapy and diminishing development of resistance. A number of studies have demonstrated that several drugs with various targets and mechanisms of action can cooperate with PN to eliminate cancer cells or inhibit their proliferation. This review summarizes the current state of knowledge on PN activity and its potential utility as complementary therapy against different cancers.

Hsp72 Is an Intracellular Target of the α,β-Unsaturated Sesquiterpene Lactone, Parthenolide

The electrophilic natural product parthenolide has generated significant interest as a model for potential chemotherapeutics. Similar to other α,β-unsaturated carbonyl electrophiles, parthenolide induces the heat shock response in leukemia cells, potentially through covalent adduction of heat shock proteins. Other thiol-reactive electrophiles have also been shown to induce the heat shock response as well as to covalently adduct members of the heat shock protein family, such as heat shock protein 72 (Hsp72). To identify sites of modification of Hsp72 by parthenolide, we used high-resolution tandem mass spectrometry to detect 10 lysine, histidine, and cysteine residues of recombinant Hsp72 as modified in vitro by 10 and 100 μM parthenolide. To further ascertain that modification of Hsp72 by parthenolide occurs inside cells and not simply as an in vitro artifact, an alkyne-labeled derivative of parthenolide was synthesized to enable enrichment and detection of protein targets of parthenolide using copper-catalyzed [3 + 2] azide-alkyne cycloaddition. The alkyne-labeled parthenolide derivative displays an half maximal inhibitory concentration (IC₅₀) in undifferentiated acute monocytic leukemia cells (THP-1) of 13.1 ± 1.1 μM, whereas parthenolide has an IC₅₀ of 4.7 ± 1.1 μM. Concentration dependence of protein modification by the alkyne-parthenolide derivative was demonstrated, as well as in vitro adduction of Hsp72. Following treatment of THP-1 cells in culture by the alkyne-parthenolide, adducted proteins were isolated with neutravidin resin and detected by immunoblotting in the enriched protein fraction. Hsp70 proteins were detected in the enriched proteins, indicating that Hsp70 proteins were adducted intracellularly by the alkyne-parthenolide derivative.

Geldanamycin and Its Derivatives Inhibit the Growth of Myeloma Cells and Reduce the Expression of the MET Receptor

Introduction. Geldanamycin (GA) is an ansamycin antibiotic that exhibits potent anti-neoplastic properties. The aim of this study was to assess the impact of GA and its derivatives on the growth and invasiveness of myeloma cell lines and CD138+ cells derived from the bone marrow of patients with multiple myeloma. Materials and methods. We evaluated cell proliferation, survival, apoptosis, cell cycle of myeloma cells, and the expression of cell surface proteins after incubation with geldanamycin or its derivatives. Results. GA and its analogs have an effect on myeloma cells by inhibiting their growth in a time and dose-dependent manner. Myeloma cell lines demonstrated decreased proliferation after incubation with 10 nM of GA or 100 nM GA analogs. The first significant effects of GA on U266 cells was observed after 24 hours. After 24 hours, U266 cells incubated with 100 nM GA were in both early and late stages of apoptosis; 17AEP and 17DMAG caused apoptosis of similar intensity to GA. It has been observed that GA and its derivatives cause caspase-3 activation. Analysis of the activity of AKT and MAP 42/44 kinases was performed by incubating U266 cells for 24 and 48 hours in100 nM of GA and its derivatives. After 24 hours incubation, no significant changes in protein expression were observed, while after 48 hours, the strongest changes were seen in AKT protein expression after incubation with GA and 17AEP-GA. In studies of the cell cycle, it was found that 100 nM 17AEP-GA and 17-DMAP-GA cause cell cycle abnormalities. We observed a nearly two-fold increase in U266 cells in the G1 phase and a simultaneous decrease in the percentage of cells in the G2/M phase, indicating that cells were halted in the G1 phase. In the case of the INA6 cells, proliferation was halted in both the G1 and G2/M phases. Conclusions. GA and the analogues that we tested can inhibit myeloma cell growth by induction of apoptosis and blockage of cell cycle progression, and have an effect on the down-regulation of the MET receptor. The GA derivatives tested, despite their modifications still retain strong anticancer properties. Specifically, two analogues of GA, 17AEP-GA and 17DMAG due to their properties can be more effective and safer chemotherapeutic agents than 17AAG, which is currently used and described in literature.

Parthenolide Sensitizes Human Colorectal Cancer Cells to Tumor Necrosis Factor-related Apoptosis-inducing Ligand through Mitochondrial and Caspase Dependent Pathway

BACKGROUND/AIMS

Combination therapy utilizing tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in conjunction with other anticancer agents, is a promising strategy to overcome TRAIL resistance in malignant cells. Recently, parthenolide (PT) has proved to be a promising anticancer agent, and several studies have explored its use in combination therapy. Here, we investigated the molecular mechanisms by which PT sensitizes colorectal cancer (CRC) cells to TRAIL-induced apoptosis.

METHODS

HT-29 cells (TRAIL-resistant) were treated with PT and/or TRAIL for 24 hours. The inhibitory effect on proliferation was detected using the 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Annexin V staining, cell cycle analysis, and Hoechst 33258 staining were used to assess apoptotic cell death. Activation of an apoptotic pathway was confirmed by Western blot.

RESULTS

Treatment with TRAIL alone inhibited the proliferation of HCT 116 cells in a dose-dependent manner, whereas proliferation was not affected in HT-29 cells. Combination PT and TRAIL treatment significantly inhibited cell growth and induced apoptosis of HT-29 cells. We observed that the synergistic effect was associated with misregulation of B-cell lymphoma 2 (Bcl-2) family members, release of cytochrome C to the cytosol, activation of caspases, and increased levels of p53.

CONCLUSION

Combination therapy using PT and TRAIL might offer an effetive strategy to overcome TRAIL resistance in certain CRC cells.

Regulation of survival and chemoresistance by HSP90AA1 in ovarian cancer SKOV3 cells

Previous researches have showed that HSP90AA is important in ovarian cancer, but the mechanism of HSP90AA is still unknown. This study aimed to investigate the role of the potential therapy target protein HSP90AA1 in ovarian cancer. The level of HSP90AA1 in ovarian cancer SKOV3 cell line was altered by RNAi and overexpression. Survival of these cell lines was investigated by tetrazolium-based assay and fluorescence-activated cell sorter (FACS). The chemosensitivity to cisplatin of the cell was also tested by FACS when HSP90AA1 was overexpressed. HSP90AA1 RNAi inhibited the proliferation of ovarian cancer SKOV3 cell line and increased the apoptosis. Furthermore, overexpression of HSP90AA1 decreased the chemosensitivity to cisplatin of SKOV3 cells and overexpression of HSP90AA1 could partially rescue the survival rate of SKOV3 cells which were treated with cisplatin. HSP90AA1 is required for the survival and proliferation of SKOV3 cells. High level of HSP90AA1 can increase chemoresistance to cisplatin of SKOV3 cells.