Seeking new anti-cancer agents from autophagy-regulating natural products

Synthesis and Biological Activity of 2-Chloro-8-methoxy-5-methyl-5H-indolo [2,3-b] Quinoline for the Treatment of Colorectal Cancer by Modulating PI3K/AKT/mTOR Pathways

Developing novel drugs from natural products has proven to be a very effective strategy. Neocryptolepine was isolated from Cryptolepis sanguinolenta, a traditional endemic African herb, which exerts a wide range of biological activities such as antimalaria, antibacterial, and antitumor. 2-Chloro-8-methoxy-5-methyl-5H-indolo [2,3-b] quinoline (compound 49) was synthesized, and its cytotoxicity was assessed on pancreatic cancer PANC-1 cells, colorectal cancer HCT116 cells, liver cancer SMMC-7721 cells, and gastric cancer AGS cells in vitro. The results of the in vitro assay showed that compound 49 exerted remarkable cytotoxicity on colorectal cancer HCT116 and Caco-2 cells. The cytotoxicity of compound 49 to colorectal cancer HCT116 cells was 17 times higher than that of neocryptolepine and to human normal intestinal epithelial HIEC cells was significantly reduced. Compound 49 exhibited significant cytotoxicity against the colorectal cancer HCT116 and Caco-2 cells, with IC50 of 0.35 and 0.54 μM, respectively. The mechanism of cytotoxicity of compound 49 to colorectal cancer HCT116 and Caco-2 cells was further investigated. The results showed that compound 49 could inhibit colony formation and cell migration. Moreover, compound 49 could arrest the cell cycle at the G2/M phase, promote the production of reactive oxygen species, reduce mitochondrial membrane potential, and induce apoptosis. The results of Western blot indicated that compound 49 showed cytotoxicity on HCT116 and Caco-2 cells by modulating the PI3K/AKT/mTOR signaling pathway. In conclusion, these results suggested that compound 49 may be a potentially promising lead compound for the treatment of colorectal cancer.

Antioxidants activities of phytochemicals perspective modulation of autophagy and apoptosis to treating cancer

The study of chemicals extracted from natural sources should be encouraged due to the significant number of cancer deaths each year and the financial burden imposed by this disease on society. The causes of almost all cancers involve a combination of lifestyle, environmental factors, and genetic and inherited factors. Modern medicine researchers are increasingly interested in traditional phytochemicals as they hold potential for new bioactive compounds with medical applications. Recent publications have provided evidence of the antitumor properties of phytochemicals, a key component of traditional Chinese medicine, thereby opening new avenues for their use in modern medicine. Various studies have demonstrated a strong correlation between apoptosis and autophagy, two critical mechanisms involved in cancer formation and regulation, indicating diverse forms of crosstalk between them. Phytochemicals have the ability to activate both pro-apoptotic and pro-autophagic pathways. Therefore, understanding how phytochemicals influence the relationship between apoptosis and autophagy is crucial for developing a new cancer treatment strategy that targets these molecular mechanisms. This review aims to explore natural phytochemicals that have demonstrated anticancer effects, focusing on their role in regulating the crosstalk between apoptosis and autophagy, which contributes to uncontrolled tumor cell growth. Additionally, the review highlights the limitations and challenges of current research methodologies while suggesting potential avenues for future research in this field.

Natural products targeting macroautophagy signaling in hepatocellular carcinoma therapy: Recent evidence and perspectives

Hepatocellular carcinoma (HCC), presently the second leading cause of global cancer-related mortality, continues to pose significant challenges in the realm of medical oncology, impacting both clinical drug selection and mechanistic research. Recent investigations have unveiled autophagy-related signaling as a promising avenue for HCC treatment. A growing body of research has highlighted the pivotal role of autophagy-modulating natural products in inhibiting HCC progression. In this context, we provide a concise overview of the fundamental autophagy mechanism and delineate the involvement of autophagic signaling pathways in HCC development. Additionally, we review pertinent studies demonstrating how natural products regulate autophagy to mitigate HCC. Our findings indicate that natural products exhibit cytotoxic effects through the induction of excessive autophagy, simultaneously impeding HCC cell proliferation by autophagy inhibition, thereby depriving HCC cells of essential energy. These effects have been associated with various signaling pathways, including PI3K/AKT, MAPK, AMPK, Wnt/β-catenin, Beclin-1, and ferroautophagy. These results underscore the considerable therapeutic potential of natural products in HCC treatment. However, it is important to note that the present study did not establish definitive thresholds for autophagy induction or inhibition by natural products. Further research in this domain is imperative to gain comprehensive insights into the dual role of autophagy, equipping us with a better understanding of this double-edged sword in HCC management.

Efficacy and Mechanisms of Natural Products as Therapeutic Interventions for Chronic Respiratory Diseases

Chronic respiratory diseases are long-term conditions affecting the airways and other lung components that are characterized by a high prevalence, disability rate, and mortality rate. Further optimization of their treatment is required. Natural products, primarily extracted from organisms, possess specific molecular and structural formulas as well as distinct chemical and physical properties. These characteristics grant them the advantages of safety, gentleness, accessibility, and minimal side effects. The numerous advances in the use of natural products for treating chronic respiratory diseases have provided a steady source of motivation for new drug research and development. In this paper, we introduced the pathogenesis of chronic respiratory diseases and natural products. Furthermore, we classified natural products according to their mechanism for treating chronic respiratory diseases and describe the ways in which these products can alleviate the pathological symptoms. Simultaneously, we elaborate on the signal transduction pathways and biological impacts of natural products' targeting. Additionally, we present future prospects for natural products, considering their combination treatment approaches and administration methods. The significance of this review extends to both the research on preventing and treating chronic respiratory diseases, as well as the advancement of novel drug development in this field.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Targeting Autophagy with Natural Products as a Potential Therapeutic Approach for Cancer

Macro-autophagy (autophagy) is a highly conserved eukaryotic intracellular process of self-digestion caused by lysosomes on demand, which is upregulated as a survival strategy upon exposure to various stressors, such as metabolic insults, cytotoxic drugs, and alcohol abuse. Paradoxically, autophagy dysfunction also contributes to cancer and aging. It is well known that regulating autophagy by targeting specific regulatory molecules in its machinery can modulate multiple disease processes. Therefore, autophagy represents a significant pharmacological target for drug development and therapeutic interventions in various diseases, including cancers. According to the framework of autophagy, the suppression or induction of autophagy can exert therapeutic properties through the promotion of cell death or cell survival, which are the two main events targeted by cancer therapies. Remarkably, natural products have attracted attention in the anticancer drug discovery field, because they are biologically friendly and have potential therapeutic effects. In this review, we summarize the up-to-date knowledge regarding natural products that can modulate autophagy in various cancers. These findings will provide a new position to exploit more natural compounds as potential novel anticancer drugs and will lead to a better understanding of molecular pathways by targeting the various autophagy stages of upcoming cancer therapeutics.

Exploring the Role of Autophagy Dysfunction in Neurodegenerative Disorders

Autophagy is a catabolic pathway by which misfolded proteins or damaged organelles are engulfed by autophagosomes and then transported to lysosomes for degradation. Recently, a great improvement has been done to explain the molecular mechanisms and roles of autophagy in several important cellular metabolic processes. Besides being a vital clearance pathway or a cell survival pathway in response to different stresses, autophagy dysfunction, either upregulated or down-regulated, has been suggested to be linked with numerous neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Impairment at different stages of autophagy results in the formation of large protein aggregates and damaged organelles, which leads to the onset and progression of different neurodegenerative disorders. This article elucidates the recent progress about the role of autophagy in neurodegenerative disorders and explains how autophagy dysfunction is linked with the pathogenesis of such disorders as well as the novel potential autophagy-associated therapies for treating them.

Long non-coding RNA ADAMTS9-AS2 inhibits liver cancer cell proliferation, migration and invasion

Long non-coding RNA (lncRNA) ADAM metallopeptidase with thrombospondin type 1 motif 9 antisense RNA 2 (ADAMTS9-AS2) is involved in various types of cancer, such as ovarian cancer, lung cancer and clear cell renal cell carcinoma. However, the roles of ADAMTS9-AS2 in liver cancer are not completely understood. The present study aimed to determine the functional role of ADAMTS9-AS2 in human liver cancer and investigate the potential underlying molecular mechanisms. The expression levels of ADAMTS9-AS2 and ADAMTS9 were determined following ADAMTS9-AS2 overexpression and knockdown. The results indicated that ADAMTS9-AS2 overexpression and knockdown increased and decreased ADAMTS9 mRNA and protein expression levels, respectively, indicating that alterations in ADAMTS9 expression corresponded with ADAMTS9-AS2 expression. Subsequently, the effects of ADAMTS9-AS2 on liver cancer cell proliferation, migration and invasion were analyzed by performing Cell Counting Kit-8, wound healing and Transwell assays, respectively. The results demonstrated that ADAMTS9-AS2 inhibited liver cancer cell proliferation, migration and invasion. Finally, the effect of ADAMTS9 on PI3K/AKT/mTOR signaling pathway-associated proteins [AKT, phosphorylated-AKT, phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit β (PIK3CB), mTOR and phosphorylated-mTOR], several key autophagy-related proteins [light chain 3-I/II (LC3-I/II), beclin 1 (BECN1) and sequestosome 1 (SQSTM1)] and apoptosis-related proteins (Bax and Bcl-2) was detected via western blotting. The results suggested that ADAMTS9-AS2 downregulated the phosphorylation of AKT and mTOR, the protein expression level of PIK3CB, as well as the expression levels of autophagy protein SQSTM1 and antiapoptotic protein Bcl-2. By contrast, ADAMTS9-AS2 upregulated the expression levels of autophagy proteins LC3-II and BECN1, and the proapoptotic protein Bax. Collectively, ADAMTS9-AS2 inhibited liver cancer cell proliferation, migration and invasion via inhibiting the PI3K/AKT/mTOR signaling pathway. The present study provided a novel insight into the role of ADAMTS9-AS2 in liver cancer.

Design of a Novel Nucleus-Targeted NLS-KALA-SA Nanocarrier to Delivery Poorly Water-Soluble Anti-Tumor Drug for Lung Cancer Treatment

In this study, we designed a novel nucleus-targeted nanocarrier (NLS-KALA-SA, NKSN) consisting of Kala peptide (KALA), nuclear localization signal (NLS) and stearic acid (SA) using Fmoc solid phase synthesis method. We chose Curcumin (CUR), Paclitaxel (PTX), Ginsenoside compound K(CK) as models of poorly water-soluble antitumor drugs, The drugs loaded NLS-KALA-SA nanoparticles (CUR/NKSN, PTX/NKSN, CK/NKSN) were obained by the dialysis method, their physicochemical properties were determined and antitumor activity were evaluated. The NLS-KALA-SA nanoparticles were spherical shaped with an average size of 76.4 ± 7.6 mm and a zeta potential of 43.7 ± 5.8 mV. The drug-loaded NLS-KALA-SA nanoparticles were above 86.1% and 17.1% in entrapment efficiency and drug loading capacity, and had sustained drug release behavior. Biodistribution and cellular uptake study exhibited that PTX/NKSN mainly distributed in tumor site of A549-bearing mice, and coumarin-6(C6) loaded NLS-KALA-SA nanoparticle (C6/NKSN) was predominantly accumulated in the nucleus of A549 cells. Western blot analysis indicated that PTX/NKSN could more remarkably inhibit Bcl-2 expression and enhance the expression of Bax and Caspase-3 as compared to the controls in A549 cells. Cell apoptosis and antitumor activity study showed that PXT/NKSN could more obviously induce apoptosis of A549 cells compared with free PXT, the PTX/NKSN administration was more effective than free PTX for lung cancer treatment and displayed mild toxicity in A549-bearing mice. The results demonstrates that the NLS-KALA-SA nanoparticles system could enhance the antitumor effects of the encapsulated drug and reduce tissue toxicity due to its long circulating properties and tumor targeting, which might provide a promising strategy for lung cancer treatment.

Mitochondrial functional and structural impairment is involved in the antitumor activity of δ-tocotrienol in prostate cancer cells

The therapeutic options for castration-resistant prostate cancer (CRPC) are still limited. Natural bioactive compounds were shown to possess pro-death properties in different tumors. We previously reported that δ-tocotrienol (δ-TT) induces apoptosis, paraptosis and autophagy in CRPC cells. Here, we investigated whether δ-TT might exert its activity by impairing mitochondrial functions. We demonstrated that, in PC3 and DU145 cells, δ-TT impairs mitochondrial respiration and structural dynamics. In both cell lines, δ-TT triggers mitochondrial Ca²⁺ and ROS overload. In PC3 cells, both Ca²⁺ and ROS mediate the δ-TT-related anticancer activities (decrease of cell viability, apoptosis, paraptosis, autophagy and mitophagy). As expected, in autophagy-defective DU145 cells, Ca²⁺ overload was involved in δ-TT-induced pro-death effects but not in autophagy and mitophagy. In this cell line, we also demonstrated that ROS overload is not involved in the anticancer activities of δ-TT, supporting a low susceptibility of these cells to ROS-related oxidative stress. Taken together, these data demonstrate that, in CRPC cells, δ-TT triggers cell death by inducing mitochondrial functional and structural impairments, providing novel mechanistic insights in its antitumor activity.

Semisynthesis of novel magnolol-based Mannich base derivatives that suppress cancer cells via inducing autophagy

Magnolol, a natural bioactive neolignan, was found in the bark of a traditional Chinese medicine Magnoliae officinalis ("Hou Po" in Chinese). In this study, thrity-two magnolol-based Mannich base derivatives 3a-p and 4a-p were synthesized, and evaluated for their anti-proliferative activities against a panel of human tumor cell lines (T47D, MCF-7, Hela and A549). Among all derivatives, compound 3p displayed the most potent antiproliferative activity against T47D, MCF-7 and Hela cell lines with IC₅₀ values of 0.91, 3.32 and 1.71 μM, respectively. Compared with the parental magnolol and the positive drug cisplatin, 3p exhibited up to 76.1-fold and 10.3-fold enhancement of cytotoxic effect on T47D cancer cells, respectively. Mechanism study revealed that the most potent derivative 3p suppressed cancer cells via inducing autophagy. Moreover, 3p also possessed suppressive effects on migration of T47D and Hela cancer cells. In addition, some interesting structure-activity relationships (SARs) were also summarized.

Autophagy-regulating N-heterocycles derivatives as potential anticancer agents

As a double-edged sword, autophagy in cancer cells could either suppress or promote tumorigenesis. Nowadays, more and more natural compounds with autophagy-regulating activities exhibit therapeutic effects against various cancers. N-Heterocycle derivatives plays an important role for discovery new drugs. In this review, we summarize and classify 116 N-heterocycle derivatives with autophagy-regulating activities in the past decade into 12 classes according to structure characteristics. The structural features, bioactivities, mechanism and problems faced in this field are discussed and reported for the first time. Some of these even exhibited outstanding in vivo antitumor activities, including bisaminoquinoline (3), pancratistatin (8), 10-hydroxyevodiamine (18), lycorine (28), piperine (31) and iridium (III) complex (57), which are potential drug candidates for antitumor therapy.

Licochalcone A restrains microphthalmia-associated transcription factor expression and growth by activating autophagy in melanoma cells via miR-142-3p/Rheb/mTOR pathway

Licochalcone A (LCA) was found to possess anticancer effects. This study aimed to investigate the anticancer effects and mechanisms of LCA in melanoma. A375 and B16 melanoma cells were stimulated with LCA, MTT assay was used to assess cell proliferation. Expression of miR-142-3p, microphthalmia-associated transcription factor (MITF, which regulates melanin production) and autophagy-related genes was determined by Real-time PCR or western blot. The apoptosis was analyzed by flow cytometry and caspase-3 activity. The roles of miR-142-3p and Ras homolog enriched in brain (Rheb) in LCA-affected cells were investigated by gain- and loss-of functions. LCA inhibited proliferation and MITF expression, but increased apoptosis and autophagy of melanoma cells. Moreover, LCA elevated miR-142-3p expression, but decreased its target gene Rheb expression. The effects of LCA on melanoma cells were abrogated by miR-142-3p inhibitor or Rheb overexpression. LCA suppressed mTOR signaling activation via Rheb. Additionally, rapamycin (a mTOR antagonist) notably attenuated the effects of Rheb on the autophagy, proliferation, apoptosis, and MITF expression in LCA-treated melanoma cells. In conclusion, LCA restrained MITF expression and growth by activating autophagy in melanoma cells via miR-142-3p/Rheb/mTOR pathway. This study suggested that LCA might be a potential therapeutic candidate for prevention and treatment of melanoma.

Resveratrol As A Natural Regulator Of Autophagy For Prevention And Treatment Of Cancer

Resveratrol, as a natural product compound, has been recently attracted much attention for its potent effects on cancer. Cancer is a serious disease threatening human survival and social development. Autophagy is a cellular pathway to realize the metabolic needs of the cell itself and the renewal of some organelles and plays opposing, context-dependent role in tumorigenesis. So the regulation of autophagy is of great significance in the treatment of cancer. p62, as an autophagy adaptor protein, is a preferred target for autophagy and is constantly controlled by constitutive autophagy. As a tumor-suppression mechanism, autophagy deficiency is common in tumors, which results in aberrant accumulation of p62 and activates p62-regulated pathways, such as activation of mTOR in nutrient sensing, and the activation of the Keap1-Nrf2 pathway for antioxidant stress, which are associated with cancer development. In this review, we emphasize that resveratrol can induce autophagy in the treatment of cancer and accelerates the degradation of p62, and then, the mTOR activation is blocked and Nrf2 activation is suppressed. As a result, the multidrug resistance of cancer cells can be reversed by resveratrol.

Mechanism and medical implications of mammalian autophagy

Autophagy is a highly conserved catabolic process induced under various conditions of cellular stress, which prevents cell damage and promotes survival in the event of energy or nutrient shortage and responds to various cytotoxic insults. Thus, autophagy has primarily cytoprotective functions and needs to be tightly regulated to respond correctly to the different stimuli that cells experience, thereby conferring adaptation to the ever-changing environment. It is now apparent that autophagy is deregulated in the context of various human pathologies, including cancer and neurodegeneration, and its modulation has considerable potential as a therapeutic approach.

Ampelopsin-sodium induces apoptosis in human lung adenocarcinoma cell lines by promoting tubulin polymerization in vitro

Previous studies have demonstrated that ampelopsin (AMP), a type of flavonoid isolated from the stems and leaves of Ampelopsis grossedentata, exhibits anti-cancer activity in various types of cancer. Conversion of AMP into its sodium salt (AMP-Na) conferred enhanced solubility and stability to it. The present study aimed to evaluate the anti-cancer activity of AMP-Na in human lung adenocarcinoma cell lines and to investigate its mechanisms of action. Cell proliferation and viability were assessed by MTT and colony formation assays, and cell migration was determined using a scratch wound healing assay. The cell cycle distribution, apoptosis rate and tubulin immunofluorescence intensity were analyzed using flow cytometry, the cell ultra-microstructure was examined using transmission electron microscopy and the accumulation of tubulin was determined using laser confocal microscopy. The results demonstrated that AMP-Na significantly inhibited the proliferation, clonogenicity and migration of human lung adenocarcinoma cells. Furthermore, AMP-Na induced SPC-A-1 cell apoptosis, and promoted tubulin polymerization. The results suggested that the underlying mechanisms of AMP-Na may involve targeting of microtubules and tubulin polymerization to subsequently disrupt mitosis and induce cell cycle arrest at the S-phase.

Anticancer Effects of Constituents of Herbs Targeting Osteosarcoma

Osteosarcoma is a rare primary malignancy of bone that is prone to early metastasis. Resection surgery and chemotherapeutic regimens are current standard treatments for osteosarcoma. However, the long-term survival rate of patients with osteosarcoma is low due to a high risk of metastasis. Hence, a new approach is urgently needed to improve the treatment of osteosarcoma. Compared with chemotherapy, natural active constituents isolated from herbs exhibit less adverse effects and better anti-tumor effects. This study aimed to summarize the anticancer effects of constituents of herbs on the progression and metastasis of osteosarcoma cells. It showed that many constituents of herbs inhibited osteosarcoma by targeting proliferation, matrix metalloproteinases, integrin and cadherin, and angiogenesis. The findings might be beneficial for the development of new drugs and treatment strategies.

Recent progress in the role of autophagy in neurological diseases

Autophagy (here refers to macroautophagy) is a catabolic pathway by which large protein aggregates and damaged organelles are first sequestered into a double-membraned structure called autophago-some and then delivered to lysosome for destruction. Recently, tremen-dous progress has been made to elucidate the molecular mechanism and functions of this essential cellular metabolic process. In addition to being either a rubbish clearing system or a cellular surviving program in response to different stresses, autophagy plays important roles in a large number of pathophysiological conditions, such as cancer, diabetes, and especially neurodegenerative disorders. Here we review recent progress in the role of autophagy in neurological diseases and discuss how dysregulation of autophagy initiation, autophagosome formation, maturation, and/or au-tophagosome-lysosomal fusion step contributes to the pathogenesis of these disorders in the nervous system.

Daucosterol induces autophagic-dependent apoptosis in prostate cancer via JNK activation

Plant sterols (phytosterols) have been widely accepted as a natural anti-cancer agent in multiple malignant tumors. This study was designed to investigate the functions of daucosterol in prostate cancer progression and its possible molecular mechanisms. Our results showed that daucosterol inhibited cell proliferation and induced cell cycle arrest. Moreover, daucosterol treatment obviously promoted apoptosis and autophagy. An autophagy inhibitor, 3-methyladenine (3-MA) was proved to counteract daucosterol-triggered autophagy, growth inhibition, and apoptosis, indicating that daucosterol-induced apoptotic response was dependent on autophagy. Additionally, treatment with daucosterol resulted in increased phosphorylation of c-Jun N-terminal kinase (JNK). Furthermore, pre-treatment with a JNK-specific inhibitor SP600125 abated daucosterol-elicited autophagy and apoptotic cell death. Taken together, our findings demonstrated that daucosterol blocked prostate cancer growth at least partly through inducing autophagic-dependent apoptosis via activating JNK signaling, providing a promising candidate for the development of antitumor drugs in prostate cancer treatment.

Indole Alkaloid Derivative B, a Novel Bifunctional Agent That Mitigates 5-Fluorouracil-Induced Cardiotoxicity

Clinically approved therapeutics that mitigate chemotherapy-induced cardiotoxicity, a serious adverse effect of chemotherapy, are lacking. The aim of this study was to determine the putative protective capacity of a novel indole alkaloid derivative B (IADB) against 5-fluorouracil (5-FU)-induced cardiotoxicity. To assess the free-radical scavenging activities of IADB, the acetylcholine-induced relaxation assay in rat thoracic aorta was used. Further, IADB was tested in normal and cancer cell lines with assays gauging autophagy induction. We further examined whether IADB could attenuate cardiotoxicity in 5-FU-treated male ICR mice. We found that IADB could serve as a novel bifunctional agent (displaying both antioxidant and autophagy-modulating activities). Further, we demonstrated that IADB induced production of cytosolic autophagy-associated structures in both cancer and normal cell lines. We observed that IADB cytotoxicity was much lower in normal versus cancer cell lines, suggesting an enhanced potency toward cancer cells. The cardiotoxicity induced by 5-FU was significantly relieved in animals pretreated with IADB. Taken together, IADB treatment, in combination with chemotherapy, may lead to reduced cardiotoxicity, as well as the reduction of anticancer drug dosages that may further improve chemotherapeutic efficacy with decreased off-target effects. Our data suggest that the use of IADB may be therapeutically beneficial in minimizing cardiotoxicity associated with high-dose chemotherapy. On the basis of the redox status difference between normal and tumor cells, IADB selectively induces autophagic cell death, mediated by reactive oxygen species overproduction, in cancer cells. This novel mechanism could reveal novel therapeutic targets in chemotherapy-induced cardiotoxicity.

Resibufogenin suppresses transforming growth factor-β-activated kinase 1-mediated nuclear factor-κB activity through protein kinase C-dependent inhibition of glycogen synthase kinase 3

Resibufogenin (RB), one of the major active compounds of the traditional Chinese medicine Chansu, has received considerable attention for its potency in cancer therapy. However, the anticancer effects and the underlying mechanisms of RB on pancreatic cancer remain elusive. Here, we found that RB inhibited the viability and induces caspase‐dependent apoptosis in human pancreatic cancer cells Panc‐1 and Aspc. Resibufogenin‐induced apoptosis was through inhibition of constitutive nuclear factor‐κB (NF‐κB) activity and its target genes’ expression, which was caused by downregulation of transforming growth factor‐β‐activated kinase 1 (TAK1) levels and suppression of IκB kinase activity in Panc‐1 and Aspc cells. This induction of TAK1‐mediated NF‐κB inactivation by RB was associated with increased glycogen synthase kinase‐3 (GSK‐3) phosphorylation and subsequent suppression of its activity. Moreover, RB‐induced GSK‐3 phosphorylation/inactivation acted through activation of protein kinase C but not Akt. Finally, RB suppressed human pancreatic tumor xenograft growth in athymic nude mice. Thus, our findings reveal a novel mechanism by which RB suppresses TAK1‐mediated NF‐κB activity through protein kinase C‐dependent inhibition of GSK‐3. Our findings provide a rationale for the potential application of RB in pancreatic cancer therapy.

Autophagy and doxorubicin resistance in cancer

Doxorubicin (DOX), also known as adriamycin, is a DNA topoisomerase II inhibitor and belongs to the family of anthracycline anticancer drugs. DOX is used for the treatment of a wide variety of cancer types. However, resistance among cancer cells has emerged as a major barrier to effective treatment using DOX. Currently, the role of autophagy in cancer resistance to DOX and the mechanisms involved have become one of the areas of intense investigation. More and more preclinical data are being obtained on reversing DOX resistance through modulation of autophagy as one of the promising therapeutic strategies. This review summarizes the recent advances in autophagy-targeting therapies that overcome DOX resistance from in-vitro studies to animal models for exploration of novel delivery systems. In-depth understanding of the mechanisms of autophagy regulation in relation to DOX resistance and development of molecularly targeted autophagy-modulating agents will provide a promising therapeutic strategy for overcoming DOX resistance in cancer treatment.

Can modulators of apolipoproteinB biogenesis serve as an alternate target for cholesterol-lowering drugs?

Understanding the molecular defects underlying cardiovascular disease is necessary for the development of therapeutics. The most common method to lower circulating lipids, which reduces the incidence of cardiovascular disease, is statins, but other drugs are now entering the clinic, some of which have been approved. Nevertheless, patients cannot tolerate some of these therapeutics, the drugs are costly, and/or the treatments are approved for only rare forms of disease. Efforts to find alternative treatments have focused on other factors, such as apolipoproteinB (apoB), which transports cholesterol in the blood stream. The levels of apoB are regulated by endoplasmic reticulum (ER) associated degradation as well as by a post ER degradation pathway in model systems, and we suggest that these events provide novel therapeutic targets. We discuss first how cardiovascular disease arises and how cholesterol is regulated, and then summarize the mechanisms of action of existing treatments for cardiovascular disease. We then review the apoB biosynthetic pathway, focusing on steps that might be amenable to therapeutic interventions.

Design, synthesis and biological evaluation of anti-pancreatic cancer activity of plinabulin derivatives based on the co-crystal structure

Based on the co-crystal structures of tubulin with plinabulin and Compound 1 (a derivative of plinabulin), a total of 18 novel plinabulin derivatives were designed and synthesized. Their biological activities were evaluated against human pancreatic cancer BxPC-3 cell lines. Two novel Compounds 13d and 13e exhibited potent activities with IC₅₀ at 1.56 and 1.72 nM, respectively. The tubulin polymerization assay indicated that these derivatives could inhibit microtubule polymerization. Furthermore, the interaction between tubulin and these compounds were elucidated by molecular docking. The binding modes of Compounds 13d and 13e were similar to the co-crystal structure of Compound 1. H-π interaction was observed between the aromatic hydrogen of thiophene moiety with Phe20, which could enhance their binding affinities.

Enhancement of oral bioavailability of magnolol by encapsulation in mixed micelles containing pluronic F127 and L61

OBJECTIVES

We aimed to prepare novel magnolol-loaded mixed micelles (MAG-M) by pluronic F127 and L61 to overcome the challenges of magnolol's poor solubility and then further improve its oral bioavailability.

METHODS

Magnolol-loaded mixed micelles containing pluronic F127 and L61 were prepared by an organic solvent evaporation method. Physicochemical, transport experiment across Caco-2 cell monolayers and pharmacokinetic studies were performed to characterize MAG-M and to determine the final improvement of the oral bioavailability.

KEY FINDINGS

The MAG-M solution was transparent and colourless with average size, polydispersity index and zeta potential of 228.0 ± 2.1 nm, 0.298 ± 0.012 and -0.89 ± 0.02 mV. The micelle solution has a higher EE% and DL% of 81.57 ± 1.49% and 27.58 ± 0.53%, respectively. TEM result showed that the morphology of MAG-M was homogeneous and spherical shape. The dilution stability of MAG-M was no significant change in particle size and entrapment efficiency. MAG was demonstrated a sustained-release behaviour after encapsulated in micelles. MAG permeability across a Caco-2 cell monolayer was enhanced, and the pharmacokinetics study of MAG-M showed a 2.83-fold increase in relative oral bioavailability compared with raw MAG.

CONCLUSIONS

The mixed micelles containing pluronic F127 and L61 as drug delivery system provided a well strategy for resolving the poor solubility and bioavailability problems of MAG.

Autophagy: a new pathway for traditional Chinese medicine

Autophagy is a major intracellular degradation pathway that sequesters multiple cytoplasmic components, including accumulated proteins, damaged organelles, or invading micro-organisms and delivers them to lysosomes for degradation. Autophagy dysregulation is implicated in the pathogenesis of multiple diseases, such as aging, cancers, diabetes. The latest insights into molecular mechanisms of autophagy lead to the discovery of potential drug targets. Traditional drugs with new clinical applications are not only commonly found in western medicines, but also highlighted in traditional Chinese medicines (TCMs). Recent research findings shed light on the potential novel applications and formulation of TCMs via regulation of autophagy, indicating autophagy modulation may be an important mechanism underlying the therapeutic effect of TCMs in treating diseases. Here, we summarize the roles of autophagy in the pharmacological actions of TCMs and discuss to discover ideal autophagy modulators from TCMs with considerably higher selectivity for various human disease treatment.

Resveratrol suppresses melanoma by inhibiting NF-κB/miR-221 and inducing TFG expression

Resveratrol (Res) is a natural compound with anti-cancer effects. The goal of this study is to evaluate the suppression of Res in melanoma and investigate its relationship with miRNAs during this process. The in vitro and in vivo anti-cancer abilities of Res were evaluated using cellular assays and animal model. Two melanoma cell lines (A375 and MV3) were used for both in vitro assay and in vivo experiments. qRT-PCR and Western blot were used to detect the changes in gene expressions and protein levels. Dual-luciferase reporter assay and bioinformatic tools were used to further confirm the protein binding and activation of targeted genes. In vitro experiments showed Res significantly decreased the expression of miR-221, an oncogenic microRNA, which was confirmed by the overexpression of miR-221 with or without Res treatment. Mechanistically, we showed that the inhibition of miR-221 by Res was achieved by regulating NF-κB (RELA) activity. In the meantime, we also identified that TFG, a tumor suppressor gene, was a target of miR-221. Finally, using in vivo melanoma model, we confirmed the tumor suppressive effects of Res and our in vitro regulatory network. Res displayed a significant anti-tumor effect on melanoma cells both in vitro and in vivo. The cellular mechanism under this effect involves miRNA regulation.