Overcoming resistance to mitochondrial apoptosis by BZML-induced mitotic catastrophe is enhanced by inhibition of autophagy in A549/Taxol cells

Chemoproteomics Reveals Glaucocalyxin A Induces Mitochondria-Dependent Apoptosis of Leukemia Cells via Covalently Binding to VDAC1

Chronic myelogenous leukemia (CML) that is resistant to tyrosine kinase inhibitors is one of the deadliest hematologic malignancies, and the T315I mutation in the breakpoint cluster region-Abelson (BCR-ABL) kinase domain is the most prominent point mutation responsible for imatinib resistance in CML. Glaucocalyxin A (GLA), a natural bioactive product derived from the Rabdosia rubescens plant, has strong anticancer activity. In this study, the effect and molecular mechanism of GLA on imatinib-sensitive and imatinib-resistant CML cells harboring T315I mutation via a combined deconvolution strategy of chemoproteomics and label-free proteomics is investigated. The data demonstrated that GLA restrains proliferation and induces mitochondria-dependent apoptosis in both imatinib-sensitive and resistant CML cells. GLA covalently binds to the cysteine residues of mitochondrial voltage-dependent anion channels (VDACs), resulting in mitochondrial damage and overflow of intracellular apoptotic factors, eventually leading to apoptosis. In addition, the combination of GLA with elastin, a mitochondrial channel VDAC2/3 inhibitor, enhances mitochondria-dependent apoptosis in imatinib-sensitive and -resistant CML cells, representing a promising therapeutic approach for leukemia treatment. Taken together, the results show that GLA induces mitochondria-dependent apoptosis via covalently targeting VDACs in CML cells. GLA may thus be a candidate compound for the treatment of leukemia.

Targeted therapy for non-small-cell lung cancer: New insights into regulated cell death combined with immunotherapy

Non-small-cell lung cancer (NSCLC), which has a high rate of metastatic spread and drug resistance, is the most common subtype of lung cancer. Therefore, NSCLC patients have a very poor prognosis and a very low chance of survival. Human cancers are closely linked to regulated cell death (RCD), such as apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis. Currently, small-molecule compounds targeting various types of RCD have shown potential as anticancer treatments. Moreover, RCD appears to be a specific part of the antitumor immune response; hence, the combination of RCD and immunotherapy might increase the inhibitory effect of therapy on tumor growth. In this review, we summarize small-molecule compounds used for the treatment of NSCLC by focusing on RCD and pharmacological systems. In addition, we describe the current research status of an immunotherapy combined with an RCD-based regimen for NSCLC, providing new ideas for targeting RCD pathways in combination with immunotherapy for patients with NSCLC in the future.

Perspectives and mechanisms for targeting mitotic catastrophe in cancer treatment

Mitotic catastrophe is distinct from other cell death modes due to unique nuclear alterations characterized as multi and/or micronucleation. Mitotic catastrophe is a common and virtually unavoidable consequence during cancer therapy. However, a comprehensive understanding of mitotic catastrophe remains lacking. Herein, we summarize the anticancer drugs that induce mitotic catastrophe, including microtubule-targeting agents, spindle assembly checkpoint kinase inhibitors, DNA damage agents and DNA damage response inhibitors. Based on the relationships between mitotic catastrophe and other cell death modes, we thoroughly evaluated the roles played by mitotic catastrophe in cancer treatment as well as its advantages and disadvantages. Some strategies for overcoming its shortcomings while fully utilizing its advantages are summarized and proposed in this review. We also review how mitotic catastrophe regulates cancer immunotherapy. These summarized findings suggest that the induction of mitotic catastrophe can serve as a promising new therapeutic approach for overcoming apoptosis resistance and strengthening cancer immunotherapy.

S-72, a Novel Orally Available Tubulin Inhibitor, Overcomes Paclitaxel Resistance via Inactivation of the STING Pathway in Breast Cancer

Microtubule-targeting agents are widely used as active anticancer drugs. However, drug resistance always emerges after their long-term use, especially in the case of paclitaxel, which is the cornerstone of all subtypes of breast cancer treatment. Hence, the development of novel agents to overcome this resistance is vital. This study reports on a novel, potent, and orally bioavailable tubulin inhibitor called S-72 and evaluated its preclinical efficacy in combating paclitaxel resistance in breast cancer and the molecular mechanisms behind it. We found that S-72 suppresses the proliferation, invasion and migration of paclitaxel-resistant breast cancer cells in vitro and displays desirable antitumor activities against xenografts in vivo. As a characterized tubulin inhibitor, S-72 typically inhibits tubulin polymerization and further triggers mitosis-phase cell cycle arrest and cell apoptosis, in addition to suppressing STAT3 signaling. Further studies showed that STING signaling is involved in paclitaxel resistance, and S-72 blocks STING activation in paclitaxel-resistant breast cancer cells. This effect further restores multipolar spindle formation and causes deadly chromosomal instability in cells. Our study offers a promising novel microtubule-destabilizing agent for paclitaxel-resistant breast cancer treatment as well as a potential strategy that can be used to improve paclitaxel sensitivity.

MiR-217 regulates autophagy through OPG/RANKL/RANK in giant cell tumors

BACKGROUND

Increasing evidence suggests that microRNAs (miRNAs) play a crucial role in cancer development and progression. Our previous study showed remarkably lower levels of miR-217 in GCT cells and tissues, and miR-217 re-expression inhibited the occurrence and development of GCT in vitro; however, the associated mechanisms remain unknown. Thus, this study aimed to explore the mechanisms underlying the proliferation inhibitory effect of miR-217 in GCT cells.

METHODS

The proliferative potential of the GCT cells was measured with an MTT assay and BrdU straining. Changes in GCT cell migration and invasion was assessed by a transwell assay. Finally, Western blot and RT-PCR assays were employed to evaluate OPG/RANKL/RANK signaling pathway-related protein expression.

RESULTS

The excessive upregulation of miR-217 markedly suppressed GCT cell proliferation and tumorigenesis both in vitro and in vivo. miR-217 overexpression could inhibit the OPG/RANKL/RANK signaling pathway in vitro and in vivo. Furthermore, ALP activity was significantly decreased in GCT cells following miR-217 treatment. Importantly, miR-217 could inhibit autophagy-related protein expression and autophagosome/autolysosome formation in GCT cells and tissues.

CONCLUSION

These results suggest that miR-217 upregulation could inhibit the occurrence and development of GCT by blocking autophagy. These findings offer an effective therapeutic target to improve the survival rates of patients with CGT in the future.

Autophagy in cancer resistance to paclitaxel: Development of combination strategies

Paclitaxel, a compound naturally occurring in yew, is a commonly used drug for the treatment of different types of cancer. Unfortunately, frequent cancer cell resistance significantly decreases its anticancer effectivity. The main reason for the resistance development is the paclitaxel-induced phenomenon of cytoprotective autophagy occurring by different mechanisms of action in dependence on a cell type and possibly even leading to metastases. Paclitaxel also induces autophagy in cancer stem cells, which greatly contributes to tumor resistance development. Paclitaxel anticancer effectivity can be predicted by the presence of several autophagy-related molecular markers, such as tumor necrosis factor superfamily member 13 in triple-negative breast cancer or cystine/glutamate transporter encoded by the SLC7A11 gene in ovarian cancer. Nevertheless, the undesired effects of paclitaxel-induced autophagy can be eliminated by paclitaxel co-administration with autophagy inhibitors, such as chloroquine. Interestingly, in certain cases, it is worthy of potentiating autophagy by paclitaxel combination with autophagy inducers, for instance, apatinib. A modern strategy in anticancer research is also to encapsulate chemotherapeutics into nanoparticle carriers or develop their novel derivatives with improved anticancer properties. Hence, in this review article, we summarize not only the current knowledge of paclitaxel-induced autophagy and its role in cancer resistance but mainly the possible drug combinations based on paclitaxel and their administration in nanoparticle-based formulations as well as paclitaxel analogs with autophagy-modulating properties.

SIRT1 regulates mitotic catastrophe via autophagy and BubR1 signaling

Mitotic catastrophe (MC) is a suppressive mechanism that mediates the elimination of mitosis-deficient cells through apoptosis, necrosis or senescence after M phase block. SIRT1 is involved in the regulation of several cellular processes, including autophagy. However, the relationship between SIRT1 and MC has been largely obscure. Our study highlights that SIRT1 might be involved in the regulation of MC. We have shown that degradation of the SIRT1 protein via proteasome and lysosomal pathway was accompanied by MC induced via BMH-21. Overexpression of SIRT1 alleviated MC by decreasing the proportion of apoptotic and multinuclear cells induced by G2/M block and triggered autophagy whereas knockdown of SIRT1 aggravated MC and repressed autophagy. Furthermore, we found that serum starvation triggered autophagy evidently generated lower MC whereas siRNA of ATG5/7 suppressed autophagy leading to higher MC. ChIP analysis revealed that SIRT1 could bind to the promoter of BubR1, a component of spindle assembly checkpoint (SAC), to upregulate its expression. Overexpression of BubR1 decreased MC whereas knockdown of BubR1 increased it. These results reveal that SIRT1 regulates MC through autophagy and BubR1 signaling, and provide evidence for SIRT1, autophagy and BubR1 being the potential cancer therapeutic targets.

DHW-221, a Dual PI3K/mTOR Inhibitor, Overcomes Multidrug Resistance by Targeting P-Glycoprotein (P-gp/ABCB1) and Akt-Mediated FOXO3a Nuclear Translocation in Non-small Cell Lung Cancer

Multidrug resistance (MDR) is considered as a primary hindrance for paclitaxel failure in non-small cell lung cancer (NSCLC) patients, in which P-glycoprotein (P-gp) is overexpressed and the PI3K/Akt signaling pathway is dysregulated. Previously, we designed and synthesized DHW-221, a dual PI3K/mTOR inhibitor, which exerts a remarkable antitumor potency in NSCLC cells, but its effects and underlying mechanisms in resistant NSCLC cells remain unknown. Here, we reported for the first time that DHW-221 had favorable antiproliferative activity and suppressed cell migration and invasion in A549/Taxol cells in vitro and in vivo. Importantly, DHW-221 acted as a P-gp inhibitor via binding to P-gp, which resulted in decreased P-gp expression and function. A mechanistic study revealed that the DHW-221-induced FOXO3a nuclear translocation via Akt inhibition was involved in mitochondrial apoptosis and G0/G1 cell cycle arrest only in A549/Taxol cells and not in A549 cells. Interestingly, we observed that high-concentration DHW-221 reinforced the pro-paraptotic effect via stimulating endoplasmic reticulum (ER) stress and the mitogen-activated protein kinase (MAPK) pathway. Additionally, intragastrically administrated DHW-221 generated superior potency without obvious toxicity via FOXO3a nuclear translocation in an orthotopic A549/Taxol tumor mouse model. In conclusion, these results demonstrated that DHW-221, as a novel P-gp inhibitor, represents a prospective therapeutic candidate to overcome MDR in Taxol-resistant NSCLC treatment.

2-Methoxy-5((3,4,5-trimethosyphenyl) seleninyl) phenol causes G2/M cell cycle arrest and apoptosis in NSCLC cells through mitochondrial apoptotic pathway and MDM2 inhibition

Nonsmall cell lung cancer (NSCLC) is one of the most common malignancies and needs novel and effective chemotherapy. In this study, our purpose is to explore the anticancer effects of 2-methoxy-5((3,4,5-trimethosyphenyl) seleninyl) phenol (SQ) on human NSCLC (A549 and H460) cells. We found that SQ suppressed the proliferation of NSCLC cells in time- and dose-dependent manners, and blocked the cells at G2/M phase, which was relevant to microtubule depolymerization. Additionally, SQ induced A549 and H460 cell apoptosis by activating the mitochondrial apoptotic pathway. Further, we demonstrated that SQ enhanced the generation of reactive oxygen species (ROS), and pretreatment with N-acetyl- L-cysteine (NAC) attenuated SQ-induced cell apoptosis. Meanwhile, SQ mediated-ROS generation caused DNA damage in A549 and H460 cells. Our data also revealed that SQ-induced apoptosis was correlated with the inhibition of mouse double minute 2 (MDM2) in A549 and H460 cells. In summary, our research indicates that the novel compound SQ has great potential for therapeutic treatment of NSCLC in future.

Autophagy and cancer treatment: four functional forms of autophagy and their therapeutic applications

Cancer is the leading cause of death worldwide. Drugs play a pivotal role in cancer treatment, but the complex biological processes of cancer cells seriously limit the efficacy of various anticancer drugs. Autophagy, a self-degradative system that maintains cellular homeostasis, universally operates under normal and stress conditions in cancer cells. The roles of autophagy in cancer treatment are still controversial because both stimulation and inhibition of autophagy have been reported to enhance the effects of anticancer drugs. Thus, the important question arises as to whether we should try to strengthen or suppress autophagy during cancer therapy. Currently, autophagy can be divided into four main forms according to its different functions during cancer treatment: cytoprotective (cell survival), cytotoxic (cell death), cytostatic (growth arrest), and nonprotective (no contribution to cell death or survival). In addition, various cell death modes, such as apoptosis, necrosis, ferroptosis, senescence, and mitotic catastrophe, all contribute to the anticancer effects of drugs. The interaction between autophagy and these cell death modes is complex and can lead to anticancer drugs having different or even completely opposite effects on treatment. Therefore, it is important to understand the underlying contexts in which autophagy inhibition or activation will be beneficial or detrimental. That is, appropriate therapeutic strategies should be adopted in light of the different functions of autophagy. This review provides an overview of recent insights into the evolving relationship between autophagy and cancer treatment.

Survivin suppression heightens BZML-induced mitotic catastrophe to overcome multidrug resistance by removing therapy-induced senescent A549/Taxol cells

Mitotic catastrophe (MC) is a newly identified type of anticancer mechanism for multidrug resistance (MDR) prevention. However, the long cellular death process resulting from MC is not beneficial for anticancer treatment. BZML is a novel colchicine-binding site inhibitor which can overcome MDR by inducing MC; however, BZML-induced MC cells underwent a long cellular death process. Thus, to improve anticancer therapies based on drug-induced MC, BZML-induced MC was served as a model to further study the underlying molecular mechanisms in the process of MC. Here, BZML could induce p53-dependent senescence in A549/Taxol cells, a MDR cell line. This senescence was a secondary effect of MC in overcoming MDR. During MC, BZML-induced destruction of protein-degradation system contributed not only to an increase of p53 protein but also to the accumulation of survivin in nucleus of A549/Taxol cells. Importantly, the nuclear accumulation of survivin was not the inducer but the result of BZML-induced MC, and it promoted the survival of senescent cells. Moreover, it provided additional vulnerability and critical opportunities for sequentially applied therapies. Further, targeting survivin with YM155 accelerated the death of MC cells by timely eliminating therapy-induced senescent cells and strengthening the efficiency of BZML in overcoming MDR in A549/Taxol cells. Collectively, nuclear accumulation of survivin delayed cellular death during MC by promoting the survival of BZML-induced senescent A549/Taxol cells. Moreover, "one-two punch" approach to cancer treatment based on combination therapy with YM155 for survivin suppression might be a new strategy for potentiating MC to overcome MDR.

Eugenol-Induced Autophagy and Apoptosis in Breast Cancer Cells via PI3K/AKT/FOXO3a Pathway Inhibition

The use of natural compounds is promising in approaches to prevent and treat cancer. The long-term application of most currently employed chemotherapy techniques has toxic side effects. Eugenol, a phenolic phytochemical extracted from certain essential oils, has an anti-cancer effect. The modulation of autophagy can promote either the survival or apoptosis of cancer cells. Triple-negative (MDA-MB-231) and HER2 positive (SK-BR-3) breast cancer cell lines were treated with different doses of eugenol. Apoptosis was detected by a flow-cytometry technique, while autophagy was detected by acridine orange. Real-time PCR and Western blot assays were applied to investigate the effect of eugenol on the gene and protein expression levels of autophagy and apoptotic genes. Treating cells with different concentrations of eugenol significantly inhibited cell proliferation. The protein levels of AKT serine/threonine kinase 1 (AKT), forkhead box O3 (FOXO3a), cyclin dependent kinase inhibitor 1A (p21), cyclin-dependent kinase inhibitor (p27), and Caspase-3 and -9 increased significantly in Eugenol-treated cells. Eugenol also induced autophagy by upregulating the expression levels of microtubule-associated protein 1 light chain 3 (LC3) and downregulating the expression of nucleoporin 62 (NU p62). Eugenol is a promising natural anti-cancer agent against triple-negative and HER2-positive breast cancer. It appears to work by targeting the caspase pathway and by inducing autophagic cell death.

QTMP, a Novel Thiourea Polymer, Causes DNA Damage to Exert Anticancer Activity and Overcome Multidrug Resistance in Colorectal Cancer Cells

Colorectal cancer (CRC) is one of the most common malignancies, and multidrug resistance (MDR) severely restricts the effectiveness of various anticancer drugs. Therefore, the development of novel anticancer drugs for the treatment of CRC patients with MDR is necessary. Quaternized thiourea main-chain polymer (QTMP) is a self-assembled nanoparticle with good water solubility. Notably, QTMP is not a P-glycoprotein (P-gp) substrate, and it exhibits potent cytotoxic activity against CRC cells, including HCT116/DDP and P-gp-mediated multidrug-resistant Caco2 cells. QTMP also exhibits a strong anticancer activity against SW480 cells in vivo. Interestingly, reactive oxygen species (ROS) and reactive nitrogen species (RNS) production were increased in a concentration-dependent manner in QTMP-treated HCT116, SW480 and Caco2 cells. Importantly, QTMP causes DNA damage in these CRC cells via direct insertion into the DNA or regulation of ROS and/or RNS production. QTMP also induces caspase-dependent apoptosis via overproduction of ROS and RNS. Therefore, QTMP is a promising anticancer therapeutic agent for patients with CRC, including those cancer cells with P-gp-mediated MDR. The present study also indicates that the design and synthesis of anticancer drugs based on thiourea polymers is promising and valuable, thereby offering a new strategy to address MDR, and provides reference resources for further investigations of thiourea polymers.

Strongylocentrotus nudos Egg Polysaccharide induces autophagy and apoptosis in leukaemia cells by regulating mitochondrial function

In this study, we investigated the ability of the Polysaccharide from the Eggs of Strongylocentrotus nudus (SEP) to regulate cellular autophagy and apoptosis in leukaemia cells. Human acute myeloid leukaemia (AML) cells (HL60) and murine AML cells (L1210) treated with SEP were used to assess viability using Cell Counting Kit‐8, cytotoxicity by measuring lactate dehydrogenase release, the generation of reactive oxygen species (ROS) by DCFH‐DA staining. In addition, we utilized a mouse model of leukaemia in which L1210 cells were injected into DBA/2 mice by sub‐axillary injection. Treatment with SEP decreased cell viability, increased in cytotoxicity and increased the release of ROS in a dose‐dependent manner. SEP treatment was also associated with the activation of pro‐apoptotic proteins cleaved caspase‐3, cleaved caspase‐9 and cleaved poly (ADP‐ribose) polymerase (PARP). Activation of the apoptotic pathway led to the release of cytochrome C (CytoC) into the cytosol of the cell resulting in decreased membrane potential. The effect of SEP treatment was depended on the activation of the nuclear factor kappa‐B (NF‐κB) signalling pathway as SEP treatment led to an increase in NF‐κB phosphorylation, and inhibition of NF‐κB signalling using PDTC blocked SEP‐mediated activation of apoptosis. Treatment with SEP also prolonged survival time in our leukaemia mouse model and was associated with diminished tumour volume, increased leucocyte and lymphocyte proliferation, promoted pro‐inflammatory factor release in serum and enhanced immune function. Taken together, these data suggest that SEP inhibits the progression of leukaemia by initiating mitochondrial dysfunction, autophagy, and apoptosis via the NF‐κB signalling pathway.

1,2,3-Triazole tethered 2-mercaptobenzimidazole derivatives: design, synthesis and molecular assessment toward C6 glioma cell line

Aim: Glioblastoma multiforme (GBM) is an aggressive cancer with very limited clinical therapies. Herein, we have designed novel mercaptobenzimidazole derivatives (1-7) as multitarget antineoplastic drugs and assessed their antiproliferative profiles on an experimental model for GBM, the C6 glioma line. Results: The target compounds were synthesized in few steps with reasonable yields (33-90%). Compounds 1 (∼18 μM) and 4 (∼20 μM) showed dose-dependent antiproliferative effects on C6 glioma and significantly increased early apoptosis, but only 4 disrupted the cell cycle progression and did not induce autophagy. Docking simulations suggested these compounds as dual kinase and colchicine binding site inhibitors. Conclusion: In spite of the limited selective toxicity, 4 hold the potential to be further optimized for the treatment of GBM.

5-(3,4,5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) targets tubulin and DNA to induce anticancer activity and overcome multidrug resistance in colorectal cancer cells

Colorectal cancer (CRC) is one of the most common malignancies, and multidrug resistance (MDR) reduces the efficiency of anticancer drugs. Therefore, the development of novel anticancer drugs that are highly active against CRC with MDR is urgently needed. Our previous study showed that 5-(3,4,5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) is not a P-glycoprotein (P-gp) substrate and has a potent anticancer effect against paclitaxel -sensitive or -resistant non-small-cell lung cancer (NSCLC) in vitro and in vivo. In the present study, we found that BZML exhibited strong anticancer activity not only in sensitive CRC cells (SW480 and HCT-116 cells) but also in intrinsically drug-resistant CRC cells (Caco2 cells). In addition, by targeting the colchicine binding site, BZML inhibited tubulin polymerization, which induced G2/M phase arrest, and it caused DNA damage by directly targeting DNA or producing ROS. Further, BZML induced apoptosis through the time-dependent ROS-mediated mitochondrial apoptotic pathway in the CRC cells. Additionally, BZML inhibited P-gp-mediated drug efflux and enhanced the inhibition of the cell growth that had been induced by paclitaxel or doxorubicin in Caco2 cells. In summary, BZML is a multi-targeted anticancer drug that targets tubulin and DNA, and the mechanisms underlying its potent anticancer activity involve disrupting microtubule assembly, causing DNA damage, inducing cell cycle arrest and eventually activating the ROS-mediated mitochondrial apoptotic pathway in SW480, HCT-116 and Caco2 cells. Therefore, the novel compound BZML is a promising anticancer drug that has tremendous potential for CRC treatment, especially for the treatment of drug-resistant CRC.

Overcoming resistance to mitochondrial apoptosis by BZML-induced mitotic catastrophe is enhanced by inhibition of autophagy in A549/Taxol cells

OBJECTIVES

Our previous in vitro study showed that 5-(3, 4, 5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) is a novel colchicine binding site inhibitor with potent anti-cancer activity against apoptosis resistance in A549/Taxol cells through mitotic catastrophe (MC). However, the mechanisms underlying apoptosis resistance in A549/Taxol cells remain unknown. To clarify these mechanisms, in the present study, we investigated the molecular mechanisms of apoptosis and autophagy, which are closely associated with MC in BZML-treated A549 and A549/Taxol cells.

METHODS

Xenograft NSCLC models induced by A549 and A549/Taxol cells were used to evaluate the efficacy of BZML in vivo. The activation of the mitochondrial apoptotic pathway was assessed using JC-1 staining, Annexin V-FITC/PI double-staining, a caspase-9 fluorescence metric assay kit and western blot. The different functional forms of autophagy were distinguished by determining the impact of autophagy inhibition on drug sensitivity.

RESULTS

Our data showed that BZML also exhibited desirable anti-cancer activity against drug-resistant NSCLC in vivo. Moreover, BZML caused ROS generation and MMP loss followed by the release of cytochrome c from mitochondria to cytosol in both A549 and A549/Taxol cells. However, the ROS-mediated apoptotic pathway involving the mitochondria that is induced by BZML was only fully activated in A549 cells but not in A549/Taxol cells. Importantly, we found that autophagy acted as a non-protective type of autophagy during BZML-induced apoptosis in A549 cells, whereas it acted as a type of cytoprotective autophagy against BZML-induced MC in A549/Taxol cells.

CONCLUSIONS

Our data suggest that the anti-apoptosis property of A549/Taxol cells originates from a defect in activation of the mitochondrial apoptotic pathway, and autophagy inhibitors can potentiate BZML-induced MC to overcome resistance to mitochondrial apoptosis.