Autophagy and cancer: Can tetrandrine be a potent anticancer drug in the near future?

Tetrandrine activates STING/TBK1/IRF3 pathway to potentiate anti-PD-1 immunotherapy efficacy in non-small cell lung cancer

The efficacy of PD-1 therapy in non-small cell lung cancer (NSCLC) patients remains unsatisfactory. Activating the STING pathway is a promising strategy to improve PD-1 inhibitor efficacy. Here, we found tetrandrine (TET), an anti-tumor compound extracted from a medicinal plant commonly used in traditional Chinese medicine, has the ability to inhibit NSCLC tumor growth. Mechanistically, TET induces nuclear DNA damage and increases cytosolic dsDNA, thereby activating the STING/TBK1/IRF3 pathway, which in turn promotes the tumor infiltration of dendritic cells (DCs), macrophages, as well as CD8+ T cells in mice. In vivo imaging dynamically monitored the increased activity of the STING pathway after TET treatment and predicted the activation of the tumor immune microenvironment. We further revealed that the combination of TET with αPD-1 monoclonal antibody (αPD-1 mAb) yields significant anti-cancer effects by promoting CD8+ T cell infiltration and enhancing its cell-killing effect, which in turn reduced the growth of tumors and prolonged survival of NSCLC mice. Therefore, TET effectively eliminates NSCLC cells and enhances immunotherapy efficacy through the activation of the STING pathway, and combining TET with anti-PD-1 immunotherapy deserves further exploration for applications.

Design, synthesis, and biological antitumor evaluation of tetrahydroisoquinoline derivatives

Cancer, as a public health issue, is the leading cause of death worldwide. Tetrahydroisoquinoline derivatives have effective biological activities and can be used as potential therapeutic agents for antitumor drugs. In this work, we designed and synthesized a series of novel tetrahydroisoquinoline compounds and evaluated their antitumor activity in vitro on several representative human cancer cell lines. The results showed that the vast majority of compounds showed good inhibitory activities against the cancer cell lines of HCT116, MDA-MB-231, HepG2, and A375.

Efficacy and safety of tetrandrine in treatment of rheumatoid arthritis: a meta-analysis

OBJECTIVES

To explore the efficacy and safety of tetrandrine in the treatment of rheumatoid arthritis.

METHODS

Randomized controlled studies of tetrandrine in the treatment of rheumatoid arthritis were searched in CNKI, VIP, Wanfang database, SinoMed, PubMed, Springer, Web of Science and Cochrane Central Register of Controlled Trails databases. A meta-analysis was conducted using R 3.5.3 software to evaluate the clinical outcomes, including the total effective rate, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), visual analogue scale (VAS), disease activity score (DAS), tender joint count (TJC), swollen joint count (SJC), and morning stiffness duration, as well as adverse events of rheumatoid arthritis patients.

RESULTS

A total of 10 articles were included in the study. The meta-analysis indicated that tetrandrine significantly improved the total effective rate (OR=3.27, 95%CI: 2.01-5.37, P<0.01), ESR (SMD=1.12, 95%CI: 0.06-2.19, P<0.05), CRP (SMD=0.75, 95%CI: 0.28-1.22, P<0.01), VAS (SMD=0.64, 95%CI: 0.29-1.00, P<0.01), TJC (SMD=1.16, 95%CI: 0.58-1.74, P<0.01), SJC (SMD=0.85, 95%CI: 0.40-1.31, P<0.01), and morning stiffness (SMD=1.09, 95%CI: 0.68-1.50, P<0.01). However, no statistical significance was found in RF (SMD=1.70, 95%CI: －1.10-4.51, P>0.05) and DAS (SMD=0.26, 95%CI: －0.59-1.11, P>0.05). The overall incidence of adverse events associated with tetrandrine treatment for rheumatoid arthritis was 20% (95%CI: 12%-27%, I2=60%, P<0.05), with mild severity and favorable outcomes.

CONCLUSIONS

Tetrandrine is effective in the treatment of RA patients with a mild degree of adverse events.

Tetrandrine alleviates pulmonary fibrosis by inhibiting alveolar epithelial cell senescence through PINK1/Parkin-mediated mitophagy

Idiopathic pulmonary fibrosis (IPF) is a fatal and insidious interstitial lung disease. So far, there are no effective drugs for preventing the disease process. Cellular senescence plays a critical role in the development of IPF, with the senescence and insufficient mitophagy of alveolar epithelial cells being implicated in its pathogenesis. Tetrandrine is a natural alkaloid which is now produced synthetically. It was known that the tetrandrine has anti-fibrotic effects, but the efficacy and mechanisms are still not well evaluated. Here, we reveal the roles of tetrandrine on AECs senescence and the antifibrotic effects by using a bleomycin challenged mouse model of pulmonary fibrosis and a bleomycin-stimulated mouse alveolar epithelial cell line (MLE-12). We performed the β-galactosidase staining, immunohistochemistry and fluorescence to assess senescence in MLE-12 cells. The mitophagy levels were detected by co-localization of LC3 and COVIX. Our findings indicate that tetrandrine suppressed bleomycin-induced fibroblast activation and ultimately blocked the increase of collagen deposition in mouse model lung tissue. It has significantly inhibited the bleomycin-induced senescence and senescence-associated secretory phenotype (SASP) in alveolar epithelial cells (AECs). Mechanistically, tetrandrine suppressed the decrease of mitochondrial autophagy-related protein expression to rescue the bleomycin-stimulated impaired mitophagy in MLE-12 cells. We revealed that knockdown the putative kinase 1 (PINK1) gene by a short interfering RNA (siRNA) could abolish the ability of tetrandrine and reverse the MLE-12 cells senescence, which indicated the mitophagy of MLE-12 cells is PINK1 dependent. Our data suggest the tetrandrine could be a novel and effective drug candidate for lung fibrosis and senescence-related fibrotic diseases.

Application of Nanoparticles for Efficient Delivery of Quercetin in Cancer Cells

Quercetin (Qu, 3,5,7,3', 4'-pentahydroxyflavanone) is a natural polyphenol compound abundantly found in health food or plant-based products. In recent decades, Qu has gained significant attention in the food, cosmetic, and pharmaceutic industries owning to its wide beneficial therapeutic properties such as antioxidant, anti-inflammatory and anticancer activities. Despite the favorable roles of Qu in cancer therapy due to its numerous impacts on the cell signaling axis, its poor chemical stability and bioavailability, low aqueous solubility as well as short biological half-life have limited its clinical application. Recently, drug delivery systems based on nanotechnology have been developed to overcome such limitations and enhance the Qu biodistribution following administration. Several investigations have indicated that the nano-formulation of Qu enjoys more remarkable anticancer effects than its free form. Furthermore, incorporating Qu in various nano-delivery systems improved its sustained release and stability, extended its circulation time, enhanced its accumulation at target sites, and increased its therapeutic efficiency. The purpose of this study was to provide a comprehensive review of the anticancer properties of various Qu nano-formulation to augment their effects on different malignancies. Various targeting strategies for improving Qu delivery, including nanoliposomes, lipids, polymeric, micelle, and inorganic nanoparticle NPs, have been discussed in this review. The results of the current study illustrated that a combination of appropriate nano encapsulation approaches with tumor-oriented targeting delivery might lead to establishing QU nanoparticles that can be a promising technique for cancer treatment.

Mechanism of ferroptosis in breast cancer and research progress of natural compounds regulating ferroptosis

Breast cancer is the most prevalent cancer worldwide and its incidence increases with age, posing a significant threat to women's health globally. Due to the clinical heterogeneity of breast cancer, the majority of patients develop drug resistance and metastasis following treatment. Ferroptosis, a form of programmed cell death dependent on iron, is characterized by the accumulation of lipid peroxides, elevated levels of iron ions and lipid peroxidation. The underlying mechanisms and signalling pathways associated with ferroptosis are intricate and interconnected, involving various proteins and enzymes such as the cystine/glutamate antiporter, glutathione peroxidase 4, ferroptosis inhibitor 1 and dihydroorotate dehydrogenase. Consequently, emerging research suggests that ferroptosis may offer a novel target for breast cancer treatment; however, the mechanisms of ferroptosis in breast cancer urgently require resolution. Additionally, certain natural compounds have been reported to induce ferroptosis, thereby interfering with breast cancer. Therefore, this review not only discusses the molecular mechanisms of multiple signalling pathways that mediate ferroptosis in breast cancer (including metastasis, invasion and proliferation) but also elaborates on the mechanisms by which natural compounds induce ferroptosis in breast cancer. Furthermore, this review summarizes potential compound types that may serve as ferroptosis inducers in future tumour cells, providing lead compounds for the development of ferroptosis-inducing agents. Last, this review proposes the potential synergy of combining natural compounds with traditional breast cancer drugs in the treatment of breast cancer, thereby suggesting future directions and offering new insights.

Tetrandrine synergizes with MAPK inhibitors in treating KRAS-mutant pancreatic ductal adenocarcinoma via collaboratively modulating the TRAIL-death receptor axis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies lacking effective therapies. KRAS mutations that occur in over 90% of PDAC are major oncogenic drivers of PDAC. The MAPK signaling pathway plays a central role in KRAS-driven oncogenic signaling. However, pharmacological inhibitors of the MAPK pathway are poorly responded in KRAS-mutant PDAC, raising a compelling need to understand the mechanism behind and to seek new therapeutic solutions. Herein, we perform a screen utilizing a library composed of 800 naturally-derived bioactive compounds to identify natural products that are able to sensitize KRAS-mutant PDAC cells to the MAPK inhibition. We discover that tetrandrine, a natural bisbenzylisoquinoline alkaloid, shows a synergistic effect with MAPK inhibitors in PDAC cells and xenograft models. Mechanistically, pharmacological inhibition of the MAPK pathway exhibits a double-edged impact on the TRAIL-death receptor axis, transcriptionally upregulating TRAIL yet downregulating its agonistic receptors DR4 and DR5, which may explain the limited therapeutic outcomes of MAPK inhibitors in KRAS-mutant PDAC. Of great interest, tetrandrine stabilizes DR4/DR5 protein via impairing ubiquitination-mediated protein degradation, thereby allowing a synergy with MAPK inhibition in inducing apoptosis in KRAS-mutant PDAC. Our findings identify a new combinatorial approach for treating KRAS-mutant PDAC and highlight the role of TRAIL-DR4/DR5 axis in dictating the therapeutic outcome in KRAS-mutant PDAC.

Preliminary Study on the Effect and Molecular Mechanism of Tetrandrine in Alleviating Pulmonary Inflammation and Fibrosis Induced by Silicon Dioxide

This study aims to explore the molecular mechanism of tetrandrine (Tet) in alleviating pulmonary inflammation and fibrosis induced by silica (SiO2) from the perspective of autophagy. C57BL/6J mice were selected as experimental animals, and SiO2 was exposed by intranasal instillation. Tet was intervened by oral gavage. The mice were euthanized on the 7th and 42nd day of SiO2 exposure, and lung tissues were collected for histopathological, molecular biological, immunological, and transmission electron microscopy analysis. The results showed that SiO2 exposure could lead to significant lung inflammation and fibrosis, while Tet could significantly reduce SiO2 exposure-induced lung inflammation and fibrosis. Molecular mechanism research indicated that, compared with SiO2 expose group, Tet intervention could significantly reduce the expression levels of inflammatory cytokines and fibrosis markers (TNF-α, IL-1β, MCP-1, TGF-β1, HYP, Col-I, and Fn), and regulate the expression of key molecules ATG7, microtubule-associated protein 1 light chain 3B (LC3B), and P62 in the autophagy pathway to improve the blocking of autophagic flux, promote the recovery of autophagic lysosomal system function, and inhibit apoptosis. In summary, Tet can alleviate silica-induced lung inflammation and fibrosis, which may be achieved by regulating the expression of key molecules in the autophagy process and associated apoptotic pathway.

Liposome encapsulated anticancer drugs on autophagy in cancer cells - current and future perspective

Autophagy act as a double-edged sword in cancer with both tumor promoting and inhibiting roles. Under normal conditions of autophagy, the damaged cell organelles and other debris degrade inside the lysosome to provide energy and macromolecular precursors. However, enhanced autophagy can lead to apoptosis and programmed cell death highlighting its significance in cancer therapy. Liposome-based drug delivery systems for treating cancer patients have significant advantages over their non-formulated or free drug counterparts which could be effectively used to manipulate autophagy pathway in cancer patients. In the current review, drug uptake by the cells and its role in autophagy-mediated cancer cell death are discussed. Besides, the challenges and translational difficulties associated with the use of liposome-based chemotherapeutic drugs in clinical trials and in biomedical applications are also discussed.

Blocking autophagy by the two-pore channels antagonist tetrandrine improves sorafenib-induced death of hepatocellular carcinoma cells

Sorafenib, an oral multi-kinase inhibitor, used to treat hepatocellular carcinoma (HCC). However, drug resistance is still common in several HCC patients. This complex mechanism is not yet fully elucidated, driving the search for new therapeutic targets to potentiate the antitumoral effect of sorafenib. Recent findings have linked the expression of Two-Pore Channels (TPCs) receptors with the development and progression of cancer. TPCs receptors are stimulated by NAADP, a Ca²⁺ messenger, and inhibited by their antagonists Ned-19 and tetrandrine. Here, we investigate the participation of TPCs inhibition in cell death and autophagy in sorafenib-treated HCC cells. Here, we show that the association of sorafenib with tetrandrine increased sorafenib-induced cell death accompanied by increased lysotracker fluorescence intensity. In contrast, these effects were not observed after treating these cells with Ned-19. The pharmacological TPC antagonists by Ned-19 and tetrandrine or siRNA-mediated TPC1/2 inhibition decreased sorafenib-induced Ca²⁺ release, reinforcing the participation of TPCs in sorafenib HCC responses. Furthermore, the association tetrandrine and sorafenib blocked autophagy through ERK1/2 pathway inhibition, which represents a putative target for potentiating HCC cell death. Therefore, our study proposes the use of tetrandrine analogs with the aim of improving sorafenib therapy. Also, our data also allow us to suggest that TPCs may be a new target in anticancer therapies.

Iridium(III) complexes inhibit the proliferation and migration of BEL-7402 cells through the PI3K/AKT/mTOR signaling pathway

Iridium(III) complexes are largely studied as anti-cancer complexes due to their excellent anti-cancer activity. In this article, two new iridium(III) complexes [Ir(piq)₂(THPIP)]PF₆ (THPIP = 2,4-di-tert-butyl-6-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenol, piq = deprotonated 1-phenylisoquinoline) (Ir1) and [Ir(bzq)₂(THPIP)]PF₆ (bzq = deprotonated benzo[h]quinolone) (Ir2) were synthesized. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays showed that complex Ir1 exhibits moderate activity (IC₅₀ = 29.9 ± 4.6 μM) and Ir2 shows high cytotoxicity (IC₅₀ = 9.8 ± 1.8 μM) against BEL-7402 cells. Further studies on the mechanism showed that Ir1 and Ir2 induced apoptosis by changing the mitochondrial membrane potential, Ca²⁺ release, ROS accumulation, and cell cycle arrest at the S phase. The complexes can effectively inhibit cell colony formation and migration. The expression of B-cell lymphoma-2 (Bcl-2) family proteins, PI3K (phosphatidylinositol 3-kinase), AKT (protein kinase B), mTOR (mammalian target of rapamycin), and p-mTOR was studied by immunoblotting. Complexes Ir1 and Ir2 downregulated the expression of anti-apoptotic protein Bcl-2 and increased the expression of autophagy-related proteins of Beclin-1 and LC3-II. Further experiments showed that the complexes inhibited the production of glutathione (GSH) and increased the amounts of malondialdehyde (MDA). Fluorescence of HMGB1 was significantly increased. We also investigated the effect of the complexes on the expression of genes using RNA-sequence analysis, we further calculated the lowest binding energies between the complexes and proteins using molecular docking. Taken together, the above results indicated that complexes Ir1 and Ir2 induce apoptosis in BEL-7402 cells through a ROS-mediated mitochondrial dysfunction and inhibition of the PI3K/AKT/mTOR signaling pathway.

A novel class of C14-sulfonate-tetrandrine derivatives as potential chemotherapeutic agents for hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common malignancy of the liver, exhibits high recurrence and metastasis. Structural modifications of natural products are crucial resources of antitumor drugs. This study aimed to synthesize C-14 derivatives of tetrandrine and evaluate their effects on HCC. Forty C-14 sulfonate tetrandrine derivatives were synthesized and their in vitro antiproliferative was evaluated against four hepatoma (HepG-2, SMMC-7721, QGY-7701, and SK-Hep-1) cell lines. For all tested cells, most of the modified compounds were more active than the lead compound, tetrandrine. In particular, 14-O-(5-chlorothiophene-2-sulfonyl)-tetrandrine (33) exhibited the strongest antiproliferative effect, with half-maximal inhibitory concentration values of 1.65, 2.89, 1.77, and 2.41 μM for the four hepatoma cell lines, respectively. Moreover, 33 was found to induce apoptosis via a mitochondria-mediated intrinsic pathway via flow cytometry and western blotting analysis. In addition, colony formation, wound healing, and transwell assays demonstrated that 33 significantly inhibited HepG-2 and SMMC-7721 cell proliferation, migration, and invasion, indicating that it might potentially be a candidate for an anti-HCC therapy in the future.

Plant-derived bisbenzylisoquinoline alkaloid tetrandrine prevents human podocyte injury by regulating the miR-150-5p/NPHS1 axis

Podocytes have become a crucial target for kidney disease. Tetrandrine (TET), the main active component of a Chinese medicine formula Fangji Huangqi Tang, has shown a positive effect on various renal diseases. We aimed to investigate the effect and mechanism of TET on podocytes. The targeting relationship between microRNA (miR)-150-5p and nephrosis 1 (NPHS1) was determined by a dual-luciferase reporter gene assay. Cell proliferation, migration, and apoptosis were detected by cell counting kit-8, Transwell, and flow cytometry assays, respectively. The expression of miR-150-5p and NPHS1 was detected by RT-qPCR. The levels of Nephrin, Caspase-3, Bcl-2, Bax, E-cadherin, and α-smooth muscle actin were detected by Western blot. TET prompted cell viability and inhibited migration and apoptosis of puromycin aminonucleoside-induced human podocytes (HPC) in a dose-dependent manner. miR-150-5p directly targeted NPHS1 and was upregulated in damaged HPC. TET decreased the miR-150-5p expression and increased the level of NPHS1 and Nephrin. Overexpressed miR-150-5p inhibited the expression of NPHS1 and Nephrin, and reversed the protective effects of TET on injured HPC. TET protects the biological function of HPC by suppressing the miR-150-5p/NPHS1 axis. It reveals that TET may be a potential drug and miR150-5p is a potential therapeutic target for the treatment of podocyte injury.

Fusion assays for screening of fusion inhibitors targeting SARS-CoV-2 entry and syncytia formation

Virus fusion process is evolutionarily conserved and provides a promising pan-viral target. Cell-cell fusion leads to syncytial formation and has implications in pathogenesis, virus spread and immune evasion. Drugs that target these processes can be developed into anti-virals. Here, we have developed sensitive, rapid, adaptable fusion reporter gene assays as models for plasma membrane and alternative fusion pathways as well as syncytial fusion in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and have confirmed their specificity using neutralizing antibodies and specific protease inhibitors. The fusion report gene assays are more sensitive and unbiased than morphological fusion assay. The fusion assays can differentiate between transmembrane serine protease 2 (TMPRSS2)-dependency in TMPRSS2(+) cells and trypsin-dependency in angiotensin-converting enzyme 2 (ACE2)(+)TMPRSS2(-) cells. Moreover, we have identified putative novel fusion processes that are triggered by an acidic pH with and without trypsin. Coupled with morphological fusion criteria, we have found that syncytia formation is enhanced by TMPRSS2 or trypsin. By testing against our top drug hits previously shown to inhibit SARS-CoV-2 pseudovirus infection, we have identified several fusion inhibitors including structurally related lopsided kite-shaped molecules. Our results have important implications in the development of universal blockers and synergistic therapeutics and the small molecule inhibitors can provide important tools in elucidating the fusion process.

Focusing on the Role of Natural Products in Overcoming Cancer Drug Resistance: An Autophagy-Based Perspective

Autophagy is a critical cellular adaptive response in tumor formation. Nutritional deficiency and hypoxia exacerbate autophagic flux in established malignancies, promoting tumor cell proliferation, migration, metastasis, and resistance to therapeutic interventions. Pro-survival autophagy inhibition may be a promising treatment option for advanced cancer. Furthermore, excessive or persistent autophagy is cytotoxic, resulting in tumor cell death. Targeted autophagy activation has also shown significant promise in the fight against tumor drug resistance. Several research groups have examined the ability of natural products (NPs) such as alkaloids, terpenoids, polyphenols, and anthraquinones to serve as autophagy inhibitors or activators. The data support the capacity of NPs that promote lethal autophagy or inhibit pro-survival autophagy from being employed against tumor drug resistance. This paper discusses the potential applications of NPs that regulate autophagy in the fight against tumor drug resistance, some limitations of the current studies, and future research needs and priorities.

Tetrandrine Inhibits Skeletal Muscle Differentiation by Blocking Autophagic Flux

Tetrandrine is well known to act as a calcium channel blocker. It is a potential candidate for a tumor chemotherapy drug without toxicity. Tetrandrine inhibits cancer cell proliferation and induces cell death through apoptosis and autophagy. As cancer patients usually experience complications with sarcopenia or muscle injury, we thus assessed the effects of tetrandrine on skeletal muscle cells. We report in this study that a low dose of tetrandrine (less than 5 μM) does not affect the proliferation of C2C12 myoblasts, but significantly inhibits myogenic differentiation. Consistently, tetrandrine inhibited muscle regeneration after BaCl₂-induced injury. Mechanistic experiments showed that tetrandrine decreased the p-mTOR level and increased the levels of LC3 and SQSTM1/p62 during differentiation. Ad-mRFP-GFP-LC3B transfection experiments revealed that the lysosomal quenching of GFP signals was suppressed by tetrandrine. Furthermore, the levels of DNM1L/Drp1, PPARGA1 and cytochrome C (Cyto C), as well as caspase 3 activation and ROS production, were decreased following tetrandrine administration, indicating that the mitochondrial network signaling was inhibited. Our results indicate that tetrandrine has dual effects on autophagic flux in myoblasts during differentiation, activation in the early stage and blockade in the late stage. The ultimate blocking of autophagic flux by tetrandrine led to the disruption of mitochondria remodeling and inhibition of myogenic differentiation. The inhibitory effects of tetrandrine on skeletal muscle differentiation may limit its application in advanced cancer patients. Thus, great attention should be paid to the clinical use of tetrandrine for cancer therapy.