Tetrandrine-Induced Autophagy in MDA-MB-231 Triple-Negative Breast Cancer Cell through the Inhibition of PI3K/AKT/mTOR Signaling

Phytochemical-mediated modulation of autophagy and endoplasmic reticulum stress as a cancer therapeutic approach

Autophagy and endoplasmic reticulum (ER) stress are conserved processes that generally promote survival, but can induce cell death when physiological thresholds are crossed. The pro-survival aspects of these processes are exploited by cancer cells for tumor development and progression. Therefore, anticancer drugs targeting autophagy or ER stress to induce cell death and/or block the pro-survival aspects are being investigated extensively. Consistently, several phytochemicals have been reported to exert their anticancer effects by modulating autophagy and/or ER stress. Various phytochemicals (e.g., celastrol, curcumin, emodin, resveratrol, among others) activate the unfolded protein response to induce ER stress-mediated apoptosis through different pathways. Similarly, various phytochemicals induce autophagy through different mechanisms (namely mechanistic target of Rapamycin [mTOR] inhibition). However, phytochemical-induced autophagy can function either as a cytoprotective mechanism or as programmed cell death type II. Interestingly, at times, the same phytochemical (e.g., 6-gingerol, emodin, shikonin, among others) can induce cytoprotective autophagy or programmed cell death type II depending on cellular contexts, such as cancer type. Although there is well-documented mechanistic interplay between autophagy and ER stress, only a one-way modulation was noted with some phytochemicals (carnosol, capsaicin, cryptotanshinone, guangsangon E, kaempferol, and δ-tocotrienol): ER stress-dependent autophagy. Plant extracts are sources of potent phytochemicals and while numerous phytochemicals have been investigated in preclinical and clinical studies, the search for novel phytochemicals with anticancer effects is ongoing from plant extracts used in traditional medicine (e.g., Origanum majorana). Nonetheless, the clinical translation of phytochemicals, a promising avenue for cancer therapeutics, is hindered by several limitations that need to be addressed in future studies.

Promoter hypomethylated PDZK1 acts as a tumorigenic gene in glioma by interacting with AKT1

Glioma is the most frequently diagnosed primary brain tumor and typically has a poor prognosis because of malignant proliferation and invasion. It is urgent to elucidate the mechanisms driving glioma tumorigenesis and develop novel treatments to address this deadly disease. Here, we first revealed that PDZK1 is expressed at high levels in gliomas. Promoter hypomethylation may cause high expression of PDZK1 in glioma. Knockdown of PDZK1 inhibits glioma cell proliferation and invasion in vitro. Mechanistically, further investigations revealed that the loss of PDZK1 expression by siRNA inhibited the activation of the AKT/mTOR signaling pathway, leading to cell cycle arrest and apoptosis. Clinically, high expression of PDZK1 predicts a poorer prognosis for glioma patients than low expression of PDZK1. Overall, our study revealed that PDZK1 acts as a novel oncogene in glioma by binding to AKT1 and maintaining the activation of the AKT/mTOR signaling pathway. Thus, PDZK1 may be a potential therapeutic target for glioma.

miR-125b reverses cisplatin resistance by regulating autophagy via targeting RORA/BNIP3L axis in lung adenocarcinoma

The platinum-based chemotherapy is one of the most frequently used treatment protocols for lung adenocarcinoma (LUAD), and chemoresistance, however, usually results in treatment failure and limits its application in the clinic. It has been shown that microRNAs (miRNAs) play a significant role in tumor chemoresistance. In this study, miR-125b was identified as a specific cisplatin (DDP)-resistant gene in LUAD, as indicated by the bioinformatics analysis and the real-time quantitative PCR assay. The decreased serum level of miR-125b in LUAD patients was correlated with the poor treatment response rate and short survival time. MiR-125b decreased the A549/DDP proliferation, and the multiple drug resistance- and autophagy-related protein expression levels, which were all reversed by the inhibition of miR-125b. In addition, xenografts of human tumors in nude mice were suppressed by miR-125b, demonstrating that through autophagy regulation, miR-125b could reverse the DDP resistance in LUAD cells, both in vitro and in vivo. Further mechanistic studies indicated that miR-125b directly repressed the expression levels of RORA and its downstream BNIP3L, which in turn inhibited autophagy and reversed chemoresistance. Based on these findings, miR-125b in combination with DDP might be an effective treatment option to overcome DDP resistance in LUAD.

The therapeutic potential of natural metabolites in targeting endocrine-independent HER-2-negative breast cancer

Breast cancer (BC) is a heterogenous disease, with prognosis and treatment options depending on Estrogen, Progesterone receptor, and Human Epidermal Growth Factor Receptor-2 (HER-2) status. HER-2 negative, endocrine-independent BC presents a significant clinical challenge with limited treatment options. To date, promising strategies like immune checkpoint inhibitors have not yielded breakthroughs in patient prognosis. Despite being considered archaic, agents derived from natural sources, mainly plants, remain backbone of current treatment. In this context, we critically analyze novel naturally-derived drug candidates, elucidate their intricate mechanisms of action, and evaluate their pre-clinical in vitro and in vivo activity in endocrine-independent HER-2 negative BC. Since pre-clinical research success often does not directly correlate with drug approval, we focus on ongoing clinical trials to uncover current trends. Finally, we demonstrate the potential of combining cutting-edge technologies, such as antibody-drug conjugates or nanomedicine, with naturally-derived agents, offering new opportunities that utilize both traditional cytotoxic agents and new metabolites.

Novel sulfonyl-substituted tetrandrine derivatives for colon cancer treatment by inducing mitochondrial apoptosis and inhibiting PI3K/AKT/mTOR pathway

Tetrandrine (TET) possesses multiple pharmacological activities and could suppress tumor proliferation via PI3K pathway inhibition. However, inferior antitumor activity and potential toxicity limit its clinical application. In the present study, a series of 14-sulfonamide and sulfonate TET derivatives were designed, synthesized, and evaluated for biological activities. Through structural-activity relationship studies, compound 3c with α, β-unsaturated carbonyl group exhibited the most potent activity against all tested tumor cell lines (including Hela, HCT116, HepG2, MCF-7, and SHSY5Y), as well as negligible toxicity against normal cell lines LO2 and HEK293. Additionally, compound 3c effectively inhibited HCT116 and CT26 cell proliferation in vitro with increased cell proportion in the G2/M phase, activated the mitochondrial apoptosis pathway, and induced colon cancer cell apoptosis by suppressing the PI3K/AKT/mTOR pathway. The further molecular docking results confirmed that compound 3c is potentially bound to multiple residues in PI3K with a stronger binding affinity than TET. Ultimately, compound 3c dramatically suppressed tumor growth in the CT26 xenograft tumor model, without noticeable visceral toxicity detected in the high-dose group. In summary, compound 3c might present new insights for designing new PI3K inhibitors and be a potential candidate for colon cancer treatment.

Nanoemulsion potentiates the anti-cancer activity of Myricetin by effective inhibition of PI3K/AKT/mTOR pathway in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is a heterogeneous tumor with a poor prognosis and high metastatic potential, resulting in poor clinical outcomes, necessitating investigation to devise effective therapeutic strategies. Multiple studies have substantiated the anti-cancer properties of the naturally occurring flavonoid "Myricetin" in various malignancies. However, the therapeutic application of Myricetin is impeded by its poor water solubility and low oral bioavailability. To overcome this limitation, we aimed to develop nanoemulsion of Myricetin (Myr-NE) and evaluate its advantage over Myricetin alone in TNBC cells. The nanoemulsion was formulated using Capryol 90 (oil), Tween 20 (surfactant), and Transcutol HP (co-surfactant). The optimized nano-formulation underwent an evaluation to determine its size, zeta potential, morphology, stability, drug encapsulation efficiency, and in vitro release properties. The anti-cancer activity of Myr-NE was further studied to examine its distinct impact on intracellular drug uptake, cell-viability, anti-tumor signaling, oxidative stress, clonogenicity, and cell death, compared with Myricetin alone in MDA-MB-231 (TNBC) cells. The in vitro drug release and intracellular drug uptake of Myricetin was significantly increased in Myr-NE formulation as compared to Myricetin alone. Moreover, Myr-NE exhibited significant inhibition of cell proliferation, clonogenicity, and increased apoptosis with ~ 2.5-fold lower IC50 as compared to Myricetin. Mechanistic investigation revealed that nanoemulsion augmented the anti-cancer efficacy of Myricetin, most likely by inhibiting the PI3K/AKT/mTOR pathway, eventually leading to enhanced cell death in TNBC cells. The study provides substantial experimental evidence to support the notion that the Myr-NE formulation has the potential to be an effective therapeutic drug for TNBC treatment.

Molecular targets, therapeutic agents and multitasking nanoparticles to deal with cancer stem cells: A narrative review

There is increasing evidence that malignant tumors are initiated and maintained by a sub-population of tumor cells that have similar biological properties to normal adult stem cells. This very small population of Cancer Stem Cells (CSC) comprises tumor initiating cells responsible for cancer recurrence, drug resistance and metastasis. Conventional treatments such as chemotherapy, radiotherapy and surgery, in addition to being potentially toxic and non-specific, may paradoxically increase the population, spread and survival of CSCs. Next-generation sequencing and omics technologies are increasing our understanding of the pathways and factors involved in the development of CSCs, and can help to discover new therapeutic targets against CSCs. In addition, recent advances in nanomedicine have provided hope for the development of optimal specific therapies to eradicate CSCs. Moreover, the use of artificial intelligence and nano-informatics can elucidate new drug targets, and help to design drugs and nanoparticles (NPs) to deal with CSCs. In this review, we first summarize the properties of CSCs and describe the signaling pathways and molecular characteristics responsible for the emergence and survival of CSCs. Also, the location of CSCs within the tumor and the effect of host factors on the creation and maintenance of CSCs are discussed. Newly discovered molecular targets involved in cancer stemness and some novel therapeutic compounds to combat CSCs are highlighted. The optimum properties of anti-CSC NPs, including blood circulation and stability, tumor accumulation and penetration, cellular internalization, drug release, endosomal escape, and aptamers designed for specific targeting of CSCs are covered. Finally, some recent smart NPs designed for therapeutic and theranostic purposes to overcome CSCs are discussed.

Natural-Product-Derived Adjunctive Treatments to Conventional Therapy and Their Immunoregulatory Activities in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an invasive and persistent subtype of breast cancer that is likely to be resistant to conventional treatments. The rise in immunotherapy has created new modalities to treat cancer, but due to high costs and unreliable efficacy, adjunctive and complementary treatments have sparked interest in enhancing the efficacy of currently available treatments. Natural products, which are bioactive compounds derived from natural sources, have historically been used to treat or ameliorate inflammatory diseases and symptoms. As TNBC patients have shown little to no response to immunotherapy, the potential of natural products as candidates for adjuvant immunotherapy is being explored, as well as their immunomodulatory effects on cancer. Due to the complexity of TNBC and the ever-changing tumor microenvironment, there are challenges in determining the feasibility of using natural products to enhance the efficacy or counteract the toxicity of conventional treatments. In view of technological advances in molecular docking, pharmaceutical networking, and new drug delivery systems, natural products show promise as potential candidates in adjunctive therapy. In this article, we summarize the mechanisms of action of selected natural-product-based bioactive compounds and analyze their roles and applications in combination treatments and immune regulation.

Hyperthermia and doxorubicin release by Fol-LSMO nanoparticles induce apoptosis and autophagy in breast cancer cells

Background: Studies on the anticancer effects of lanthanum strontium manganese oxide (LSMO) nanoparticles (NPs)-mediated hyperthermia at cellular and molecular levels are scarce. Materials & methods: LSMO NPs conjugated with folic acid (Fol-LSMO NPs) were synthesized, followed by doxorubicin-loading (DoxFol-LSMO NPs), and their effects on breast cancer cells were investigated. Results: Hyperthermia (45°C) and combination treatments exhibited the highest (∼95%) anticancer activity with increased oxidative stress. The involvement of intrinsic mitochondria-mediated apoptotic pathway and induction of autophagy was noted. Cellular and molecular evidence confirmed the crosstalk between apoptosis and autophagy, involving Beclin1, Bcl2 and Caspase-3 genes with free reactive oxygen species presence. Conclusion: The study confirmed hyperthermia and doxorubicin release by Fol-LSMO NPs induces apoptosis and autophagy in breast cancer cells.

A functional role for Serum Amyloid A in the molecular regulation of autophagy in breast cancer

It has been established that the acute phase protein, Serum amyloid A (SAA), which is usually synthesized by the liver, is also synthesized by cancer cells and cancer-associated cells in the tumor microenvironment. SAA also activates modulators of autophagy, such as the PI3K/Akt and MAPK signaling pathways. However, the role of SAA in autophagy in breast cancer still remains to be elucidated. The aim of this study was to investigate the role of SAA in the regulation of signaling pathways and autophagy in in vitro and in vivo models of breast cancer. The MDA-MB-231 and MCF7 cell lines were transiently transfected to overexpress SAA1. A tumor-bearing SAA1/2 knockout mouse model was also utilized in this study. SAA1 overexpression activated ERK signaling in the MDA-MB-231 cells, downregulated the PI3K pathway protein, PKB/Akt, in the MCF7 cell line, while SAA1/2 knockout also inhibited Akt. Furthermore, SAA1 overexpression in vitro downregulated autophagy, while the expression of SQSTM1/p62 was increased in the MCF7 cells, and SAA1/2 knockout induced autophagy in vivo. SAA overexpression in the MDA-MB-231 and MCF7 cells resulted in an increase in cell viability and increased the expression of the proliferation marker, MCM2, in the MCF7 cells. Furthermore, knockout of SAA1/2 resulted in an altered inflammatory profile, evident in the decrease of plasma IL-1β, IL-6 and IL-10, while increasing the plasma levels of MCP-1 and TNF-α. Lastly, SAA1/2 knockout promoted resistance to apoptosis and necrosis through the regulation of autophagy. SAA thus regulates autophagy in breast cancer cells to promote tumorigenesis.

Progress on structural modification of Tetrandrine with wide range of pharmacological activities

Tetrandrine (Tet), derived from the traditional Chinese herb Fangji, is a class of natural alkaloids with the structure of bisbenzylisoquinoline, which has a wide range of physiological activities and significant pharmacfological effects. However, studies and clinical applications have revealed a series of drawbacks such as its poor water solubility, low bioavailability, and the fact that it can be toxic to humans. The results of many researchers have confirmed that chemical structural modifications and nanocarrier delivery can address the limited application of Tet and improve its efficacy. In this paper, we summarize the anti-tumor efficacy and mechanism of action, anti-inflammatory efficacy and mechanism of action, and clinical applications of Tet, and describe the progress of Tet based on chemical structure modification and nanocarrier delivery, aiming to explore more diverse structures to improve the pharmacological activity of Tet and provide ideas to meet clinical needs.

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.

Inositol monophosphatase 1 (IMPA1) promotes triple-negative breast cancer progression through regulating mTOR pathway and EMT process

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, which is characterized by high heterogeneity and metabolic dysregulation. Inositol monophosphatase 1(IMPA1) is critical for the metabolism of inositol, which has profound effects on gene expression and other biological processes. Here, we report for the first time that IMPA1 was upregulated in TNBC cell lines and tissues, and enhanced cell colony formation and proliferation in vitro and tumorigenicity in vivo. Additionally, IMPA1 promoted cell motility in vitro and metastatic lung colonization in vivo. Mechanistic investigations by transcriptome sequencing revealed that 4782 genes were differentially expressed between cells with IMPA1 knockdown and control cells. Among the differentially expressed genes after IMPA1 knockdown, five significantly altered genes were verified via qRT-PCR assays. Morerover, we found that the expression profile of those five targets as a gene set was significantly associated with IMPA1 status in TNBC cells. As this gene set was associated with mTOR pathway and epithelial-mesenchymal transition (EMT) process, we further confirmed that IMPA1 induced mTOR activity and EMT process, which at least in part contributed to IMPA1-induced TNBC progression. Collectively, our findings reveal a previously unrecognized role of IMPA1 in TNBC progression and identify IMPA1 as a potential target for TNBC therapy.

Origanum syriacum L. Attenuates the Malignant Phenotype of MDA-MB231 Breast Cancer Cells

Breast cancer is the leading cause of cancer-related deaths among women. Among breast cancer types, triple negative breast cancer (TNBC) is the most aggressive, and is resistant to hormonal and chemotherapeutic treatments. As such, alternative approaches that may provide some benefit in fighting this debilitating pathology are critically needed; hence the utilization of herbal medicine. Origanum syriacum L., one of the most regularly consumed plants in the Mediterranean region, exhibits antiproliferative effect on several cancer cell lines. However, whether this herb modulates the malignant phenotype of TNBC remains poorly investigated. Here, we show that in MDA-MB-231, a TNBC cell line, Origanum syriacum L. aqueous extract (OSE) inhibited cellular viability, induced autophagy determined by the accumulation of lipidized LC3 II, and triggered apoptosis. We also show that OSE significantly promoted homotypic cell-cell adhesion while it decreased cellular migration, adhesion to fibronectin, and invasion of MDA-MB-231 cells. This was supported by decreased activity of focal adhesion kinase (FAK), reduced α2 integrin expression, and downregulation of secreted PgE₂, MMP2 and MMP-9, in OSE-treated cells. Finally, we also show that OSE significantly inhibited angiogenesis and downregulated the level of nitric oxide (NO) production. Our findings demonstrate the ability of OSE to attenuate the malignant phenotype of the MDA-MB-231 cells, thus presenting Origanum syriacum L. as a promising potential source for therapeutic compounds for TNBC.

Design, Synthesis, and Biological Evaluation of N14-Amino Acid-Substituted Tetrandrine Derivatives as Potential Antitumor Agents against Human Colorectal Cancer

As a typical dibenzylisoquinoline alkaloid, tetrandrine (TET) is clinically used for the treatment of silicosis, inflammatory pulmonary, and cardiovascular diseases in China. Recent investigations have demonstrated the outstanding anticancer activity of this structure, but its poor aqueous solubility severely restricts its further development. Herein, a series of its 14-N-amino acid-substituted derivatives with improved anticancer effects and aqueous solubility were designed and synthesized. Among them, compound 16 displayed the best antiproliferative activity against human colorectal cancer (HCT-15) cells, with an IC50 value of 0.57 μM. Compared with TET, 16 was markedly improved in terms of aqueous solubility (by 5-fold). Compound 16 significantly suppressed the colony formation, migration, and invasion of HCT-15 cells in a concentration-dependent manner, with it being more potent in this respect than TET. Additionally, compound 16 markedly impaired the morphology and motility of HCT-15 cells and induced the death of colorectal cancer cells in double-staining and flow cytometry assays. Western blot results revealed that 16 could induce the autophagy of HCT-15 cells by significantly decreasing the content of p62/SQSTM1 and enhancing the Beclin-1 level and the ratio of LC3-II to LC3-I. Further study showed that 16 effectively inhibited the proliferation, migration, and tube formation of umbilical vein endothelial cells, manifesting in a potent anti-angiogenesis effect. Overall, these results revealed the potential of 16 as a promising candidate for further preclinical studies.

Natural Products in Preventing Tumor Drug Resistance and Related Signaling Pathways

Drug resistance is still an obstacle in cancer therapy, leading to the failure of tumor treatment. The emergence of tumor drug resistance has always been a main concern of oncologists. Therefore, overcoming tumor drug resistance and looking for new strategies for tumor treatment is a major focus in the field of tumor research. Natural products serve as effective substances against drug resistance because of their diverse chemical structures and pharmacological effects. We reviewed the signaling pathways involved in the development of tumor drug resistance, including Epidermal growth factor receptor (EGFR), Renin-angiotensin system (Ras), Phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), Wnt, Notch, Transforming growth factor-beta (TGF-β), and their specific signaling pathway inhibitors derived from natural products. This can provide new ideas for the prevention of drug resistance in cancer therapy.

Tetrandrine Citrate Suppresses Breast Cancer via Depletion of Glutathione Peroxidase 4 and Activation of Nuclear Receptor Coactivator 4-Mediated Ferritinophagy

Tetrandrine citrate (TetC), a novel tetrandrine salt with high water solubility, demonstrates a potent antitumor activity in chronic myeloid leukemia. Studies have indicated an important role of ferroptosis in breast cancer (BC). However, whether TetC inhibits BC progression via ferroptosis has never been explored. In the present study, we showed that TetC had a significant inhibitory effect on the proliferation and migration of MCF7 and MDA-MB-231 cells. Then, we combined TetC with different inhibitors to determine which form of cell death could be driven by TetC. MTT assay showed that ferrostatin (Fer-1) demonstrated the most potent effect on improving TetC-induced cell death in contrast to other inhibitors. TetC was also shown to significantly increase the mRNA level of prostaglandin-endoperoxide synthase 2 (Ptgs2), a ferroptosis marker. Further studies showed that TetC significantly suppressed the expression of glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1) but increased the expression of nuclear receptor coactivator 4 (NCOA4) in MCF7 and MDA-MB-231 cells even in the presence of erastin or Ras-selective lethal 3 (RSL3). Collectively, we showed novel data that ferroptosis was a major form of TetC-induced cell death. Moreover, TetC-induced ferroptotic cell death was achieved via suppressing GPX4 expression and activating NCOA4-mediated ferritinophagy in BC cells.

Targeting lactate metabolism and glycolytic pathways in the tumor microenvironment by natural products: A promising strategy in combating cancer

Anticancer drugs are not purely effective because of their toxicity, side effects, high cost, inaccessibility, and associated resistance. On the other hand, cancer is a complex public health problem that could intelligently adopt different signaling pathways and alter the body's metabolism to escape from the immune system. One of the cancer strategies to metastasize is modifying pH in the tumor microenvironment, ranging between 6.5 and 6.9. As a powerful determiner, lactate is responsible for this acidosis. It is involved in immune stimulation, including innate and adaptive immunity, apoptotic-related factors (Bax/Bcl-2, caspase), and glycolysis pathways (e.g., GLUT-1, PKM2, PFK, HK2, MCT-1, and LDH). Lactate metabolism, in turn, is interconnected with several dysregulated signaling mediators, including PI3K/Akt/mTOR, AMPK, NF-κB, Nrf2, JAK/STAT, and HIF-1α. Because of lactate's emerging and critical role, targeting lactate production and its transporters is important for preventing and managing tumorigenesis. Hence, exploring and developing novel promising anticancer agents to minimize human cancers is urgent. Based on numerous studies, natural secondary metabolites as multi-target alternative compounds with health-promoting properties possess more high effectiveness and low side effects than conventional agents. Besides, the mechanism of multi-targeted natural sources is related to lactate production and cancer-associated cross-talked factors. This review focuses on targeting the lactate metabolism/transporters, and lactate-associated mediators, including glycolytic pathways. Besides, interconnected mediators to lactate metabolism are also targeted by natural products. Accordingly, plant-derived secondary metabolites are introduced as alternative therapies in combating cancer through modulating lactate metabolism and glycolytic pathways.

Targeting the two-pore channel 2 in cancer progression and metastasis

The importance of Ca²⁺ signaling, and particularly Ca²⁺ channels, in key events of cancer cell function such as proliferation, metastasis, autophagy and angiogenesis, has recently begun to be appreciated. Of particular note are two-pore channels (TPCs), a group of recently identified Ca²⁺-channels, located within the endolysosomal system. TPC2 has recently emerged as an intracellular ion channel of significant pathophysiological relevance, specifically in cancer, and interest in its role as an anti-cancer drug target has begun to be explored. Herein, an overview of the cancer-related functions of TPC2 and a discussion of its potential as a target for therapeutic intervention, including a summary of clinical trials examining the TPC2 inhibitors, naringenin, tetrandrine, and verapamil for the treatment of various cancers is provided.

Tetrandrine reduces oxidative stress, apoptosis, and extracellular matrix degradation and improves intervertebral disc degeneration by inducing autophagy

Tetrandrine (TET) was reported to be an autophagy agonist, and the activating autophagy could delay intervertebral disc degeneration (IDD). Our study focused on exploring whether TET attenuated tert butyl hydrogen peroxide (TBHP)-induced nucleus pulposus (NP) cell injury and delayed rat IDD by inducing autophagy. In vitro, cytotoxicity was detected by MTT assay, ROS was measured with DCFH-DA probe, MDA, and SOD content was evaluated through ELISA, NP cell apoptosis was tested by flow cytometry, protein expression was detected by Western blot, in particular, LC3 expression was assessed by immunofluorescence. In vivo, pathological changes were estimated by HE and safranin-O staining, related protein expression was measured by immunohistochemistry, and the apoptosis was detected by TUNEL. Compared with the control group, oxidative stress, apoptosis, and extracellular matrix (ECM) degradation were increased, the expression of cleaved caspase-3,9, aggrecan and collagen II were reduced, and the expression of MMP13 and ADAMTS5 were up-regulated in TBHP-treated NP cells. Moreover, TET could reverse the effect of TBHP on NP cells. Further, TET enhanced autophagy in NP cells by amplifying the LC3 II/LC3 I/ratio and reducing p62 expression, which attenuated oxidative stress, apoptosis, and ECM degradation in TBHP-treated NP cells. In addition, in vivo, TET delayed rat IDD, increased the expression of LC3 and collagen II, and weakened apoptosis. TET inhibited oxidative stress, apoptosis, and ECM degradation in TBHP-treated NP cells by inducing autophagy, and alleviated IDD. These indicated that TET might be a potential candidate drug for the treatment of IDD.

Dihydromyricetin ameliorates oxygen‑glucose deprivation and re‑oxygenation‑induced injury in HT22 cells by activating the Wnt/β‑catenin signaling pathway

Dihydromyricetin (DMY) is a natural flavonoid that possesses a wide range of pharmacological properties. The aim of the present study was to determine whether DMY could protect against nerve cell injury following ischemic stroke through antioxidant and neuroprotective effects. The effects of DMY on the viability, oxidative stress and apoptosis of HT22 cells following oxygen‑glucose deprivation and re‑oxygenation (OGD/R) were examined using MTT, lactate dehydrogenase (LDH), superoxide (SOD), malondialdehyde (MDA), western blot and TUNEL assays. Furthermore, Wnt/β‑catenin signaling proteins in OGD/R‑stimulated HT22 cells were detected in the presence or absence of DMY. In a separate experiment, the effect of DMY on OGD/R‑induced HT22 cell injury was also observed in the presence of the Wnt/β‑catenin inhibitor, XAV939. The results demonstrated that DMY had no impact on the survival of untreated HT22 cells, although DMY treatment significantly increased cell viability and inhibited cytotoxicity, oxidative stress and apoptosis following OGD/R. In addition, DMY upregulated the expression of Wnt/β‑catenin in OGD/R‑stimulated HT22 cells. In conclusion, DMY protected HT22 cells from OGD/R‑induced oxidative stress and apoptosis, and its effects may be mediated by the activation of the Wnt/β‑catenin signaling pathway.

Immune Effect of Active Components of Traditional Chinese Medicine on Triple-Negative Breast Cancer

Triple-negative breast cancers are heterogeneous, poorly prognostic, and metastatic malignancies that result in a high risk of death for patients. Targeted therapy for triple-negative breast cancer has been extremely challenging due to the lack of expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Clinical treatment regimens for triple-negative breast cancer are often based on paclitaxel and platinum drugs, but drug resistance and side effects from the drugs frequently lead to treatment failure, thus requiring the development of new therapeutic platforms. In recent years, research on traditional Chinese medicine in modulating the immune function of the body has shown that it has the potential to be an effective treatment option against triple-negative breast cancer. Active components of herbal medicines such as alkaloids, flavonoids, polyphenols, saponins, and polysaccharides have been shown to inhibit cancer cell proliferation and metastasis by activating inflammatory immune responses and can modulate tumor-related signaling pathways to further inhibit the invasion of triple-negative breast cancer. This paper reviews the immunomodulatory mechanisms of different herbal active ingredients against triple-negative breast cancer and provides an outlook on the challenges and directions of development for the treatment of triple-negative breast cancer with herbal active ingredients.

Tetrandrine Suppresses Human Brain Glioblastoma GBM 8401/luc2 Cell-Xenografted Subcutaneous Tumors in Nude Mice In Vivo

Tetrandrine (TET), a bisbenzylisoquinoline (BBI) alkaloid, is isolated from the plant Stephania tetrandra S. Moore and has a wide range of biological activity, including anticancer properties in vitro and in vivo. At first, we established a luciferase-expressing stable clone that was named GBM 8401/luc2 cells. Herein, the primary results indicated that TET reduced the total cell viability and induced cell apoptosis in GBM 8401/luc2 human glioblastoma cells. However, there is no available information showing that TET suppresses glioblastoma cells in vivo. Thus, we investigated the effects and mechanisms of TET on a GBM 8401/luc2 cell-generated tumor in vivo. After the tumor volume reached 100-120 mm³ in subcutaneously xenografted nude mice, all of the mice were randomly divided into three groups: Group I was treated with phosphate-buffered solution (PBS) containing 0.1% dimethyl sulfoxide, Group II with 25 mg/kg of TET, and Group III with 50 mg/kg of TET. All mice were given the oral treatment of PBS or TET by gavage for 21 days, and the body weight and tumor volumes were recorded every 5 days. After treatment, individual tumors, kidneys, livers, and spleens were isolated from each group. The results showed that TET did not affect the body weights, but it significantly decreased the tumor volumes. The TET treatment at 50 mg/kg had a two-fold decrease in tumor volumes than that at 25 mg/kg when compared to the control. TET decreased the total photon flux, and treatment with TET at 50 mg/kg had a lower total photon flux than that at 25 mg/kg, as measured by a Xenogen IVIS imaging system. Moreover, the higher TET treatment had lower tumor volumes and weights than those of the lower dose. The apoptosis-associated protein expression in the tumor section was examined by immunohistochemical analysis, and the results showed that TET treatment reduced the levels of c-FLIP, MCL-1, and XIAP but increased the signals of cleaved-caspase-3, -8, and -9. Furthermore, the hematoxylin and eosin (H & E) staining of kidney, liver, and spleen tissues showed no significant difference between the TET-treated and control groups. Overall, these observations demonstrated that TET suppressed subcutaneous tumor growth in a nude-mice model via the induction of cell apoptosis.

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.

Phytochemicals as PI3K/ Akt/ mTOR Inhibitors and Their Role in Breast Cancer Treatment

BACKGROUND

Breast cancer is the predominant form of cancer in women; various cellular pathways are involved in the initiation and progression of breast cancer. Among the various types of breast cancer that differ in their growth factor receptor status, PI3K/Akt signaling is a common pathway where all these converge. Thus, the PI3K signaling is of great interest as a target for breast cancer prevention; however, it is less explored.

OBJECTIVE

The present review is aimed to provide a concise outline of the role of PI3K/Akt/mTOR pathway in breast carcinogenesis and its progression events, including metastasis, drug resistance and stemness. The review emphasizes the role of natural and synthetic inhibitors of PI3K/Akt/m- TOR pathway in breast cancer prevention.

METHODS

The data were obtained from PubMed/Medline databases, Scopus and Google patent literature.

RESULTS

PI3K/Akt/mTOR signaling plays an important role in human breast carcinogenesis; it acts on the initiation and progression events associated with it. Numerous molecules have been isolated and identified as promising drug candidates by targeting the signaling pathway. Results from clinical studies confirm their application in the treatment of human breast cancer alone and in combination with classical chemotherapeutics as well as monoclonal antibodies.

CONCLUSION

PI3K/mTOR signaling blockers have evolved as promising anticancer agents by interfering breast cancer development and progression at various stages. Natural products and bioactive components are emerging as novel inhibitors of PI3K signaling and more research in this area may yield numerous drug candidates.

New Insight into Triple-Negative Breast Cancer Therapy: The Potential Roles of Endoplasmic Reticulum Stress and Autophagy Mechanisms

BACKGROUND

Breast cancer is accounted as the fifth leading cause of mortality among the other cancers. Notwithstanding, Triple Negative Breast Cancer (TNBC) is responsible for 15-20% of breast cancer mortality. Despite many investigations, it remains incurable in part due to insufficient understanding of its exact mechanisms.

METHODS

A literature search was performed in PubMed, SCOPUS and Web of Science databases using the keywords autophagy, Endoplasmic Reticulum (ER) stress, apoptosis, TNBC and the combinations of these keywords.

RESULTS

It was found that autophagy plays a dual role in cancer, so that it may decrease the viability of tumor cells or act as a cytoprotective mechanism. It then appears that using compounds having modulatory effects on autophagy is of importance in terms of induction of autophagic cell death and diminishing the proliferation and metastasis of tumor cells. Also, ER stress can be modulated in order to stimulate apoptotic and autophagic cell death in tumor cells.

CONCLUSION

Perturbation in the signaling pathways related to cell survival leads to the initiation and progression of cancer. Regarding the advancement in the cancer pathology, it seems that modulation of autophagy and ER stress are promising.

The Effect and Mechanism of Asymmetric Dimethylarginine Regulating Trophoblastic Autophagy on Fetal Growth Restriction

Fetal growth restriction (FGR) is an important cause of perinatal death and adverse pregnancy outcomes. Asymmetric dimethylarginine (ADMA) is associated with FGR, but the mechanisms have not been thoroughly studied. Here, we determined the levels of ADMA and autophagy-related molecules in human blood samples and placental tissues. And we also used the human chorionic carcinoma cell line BeWo to investigate the mechanism of ADMA-induced FGR in vitro. Compared with the control group, ADMA levels in maternal blood and placenta were increased in patients with FGR, and the birth weight (BW) percentile was negatively correlated with maternal serum ADMA concentration in the FGR group. The expression of mammalian target of rapamycin (mTOR) in the placenta of the FGR group was lower than the control group, while the expression of Beclin-1 and microtubule-associated protein 1 light chain 3-II (LC3-II)/LC3-I was significantly increased in the FGR group. And the expression of matrix metalloproteinase 9 (MMP9) was decreased in the placenta of patients with FGR. In in vitro cell experiments, compared with the control group, the expression of mTOR and MMP9 in BeWo cells was decreased and the expression of Beclin-1 and LC3-II/LC3-I was increased in the ADMA-treated group. Moreover, ADMA had favorable effects on the formation of autophagic vacuoles, and the autophagy inhibitor 3-Methyladenine (3-MA) could reduce the autophagy-induction effect of ADMA on BeWo cells. This study found that ADMA could participate in the occurrence of FGR through inducing autophagy in trophoblasts.

Proliferation, migration and invasion of triple negative breast cancer cells are suppressed by berbamine via the PI3K/Akt/MDM2/p53 and PI3K/Akt/mTOR signaling pathways

Breast cancer is the second most common cause of cancer-associated mortality among women worldwide, and triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Berbamine (BBM) is a traditional Chinese medicine used for the treatment of leukopenia without any obvious side effects. Recent reports found that BBM has anti-cancer effects. The present study aimed to investigate the effects of BBM on TNBC cell lines and the underlying molecular mechanism. MDA-MB-231 cells and MCF-7 cells, two TNBC cell lines, were treated with various concentrations of BBM. A series of bioassays including MTT, colony formation, EdU staining, apoptosis, trypan blue dye, wound healing, transwell, ELISA and western blotting assays were performed. The results showed that BBM significantly inhibited cell proliferation of MDA-MB-231 cells (P<0.05; IC₅₀=22.72 µM) and MCF-7 cells (P<0.05; IC₅₀=20.92 µM). BBM (20 µM) decreased the apoptosis ratio (percentage of absorbance compared with the control group) by 28.4±3.3% (P<0.05) in MDA-MB-231 cells, and 62.4±24.6% (P<0.05) in MCF-7 cells. In addition, BBM inhibited cell migration and invasion of TNBC cells. Furthermore, the expression levels of PI3K, phosphorylated-Akt/Akt, COX-2, LOX, MDM2 and mTOR were downregulated by BBM, and the expression of p53 was upregulated by BBM. These results indicated that BBM may suppress the development of TNBC via regulation of the PI3K/Akt/MDM2/p53 and PI3K/Akt/mTOR signal pathways. Therefore, BBM might be used as a drug candidate for the treatment of TNBC in the future.

Capsaicin suppresses breast cancer cell viability by regulating the CDK8/PI3K/Akt/Wnt/β‑catenin signaling pathway

Breast cancer displays high morbidity and mortality. Despite exerting certain effects, traditional treatments cannot eliminate every cancer cell and may kill normal cells due to inaccurate targeting. However, as a traditional Chinese medicine, capsaicin, an active compound extracted from chili peppers, has displayed potent anticarcinogenic activities in vitro and in vivo, but the underlying mechanism is not completely understood. The pharmacological effects of capsaicin on tumors was evaluated in MDA MB 231 breast cancer cells. The MTT, cell scratch assay, cell cycle analysis, cell transfection, reverse transcription‑quantitative PCR and western blotting were performed to investigate the potential antitumor mechanisms of capsaicin. In the present study, the potential anticancer mechanism underlying capsaicin in MDA‑MB‑231 cells in vitro was investigated. Capsaicin significantly inhibited MDA‑MB‑231 breast cancer cell viability and migration compared with the control group. The flow cytometry results indicated that capsaicin induced G2/M cell cycle arrest in MDA‑MB‑231 cells. In addition, capsaicin significantly reduced the expression of cyclin‑dependent kinase 8 (CDK8) in breast cancer cells compared with the control group. Moreover, LV‑CDK8 small interfering RNA‑transduced MDA‑MB‑231 cells displayed lower CDK8 mRNA and protein expression levels compared with LV‑negative control‑shRNA‑transduced cells. Furthermore, capsaicin significantly reduced the expression levels of phosphorylated (p)‑PI3K, p‑Akt, Wnt and β‑catenin in vitro compared with the control group. Collectively, the results of the present study suggested that capsaicin inhibited breast cancer cell viability, induced G2/M cell cycle arrest, reduced CDK8 expression levels, decreased the phosphorylation of PI3K and Akt and downregulated Wnt and β‑catenin expression levels in MDA‑MB‑231 cells.

SLFN5 influences proliferation and apoptosis by upregulating PTEN transcription via ZEB1 and inhibits the purine metabolic pathway in breast cancer

Human Schlafen-5 (SLFN5) is aberrantly involved in tumorigenesis in several types of cancer. However, its implications in breast cancer (BRCA) are unknown. Herein, we demonstrated that SLFN5 expression is negatively associated with the tumour growth of human BRCA using GEO database analysis and clinical sample immunostaining. Lentiviral overexpression of SLFN5 in BRCA cell lines suppressed tumourigenicity in nude mice. Knockdown and overexpression of SLFN5 in BRCA cell lines proved that SLFN5 can inhibit cell proliferation and colony formation and promote apoptosis by upregulating the transcription of a known cancer suppressor gene (the phosphatase and tensin homologue on chromosome 10, PTEN), resulting in molecular changes in the downstream AKT pathway and in proliferation/apoptosis. Lentiviral knockdown and overexpression of ZEB1 blocked the changes in the PTEN and AKT pathways and in the colony formation ability caused by SLFN5 knockdown and overexpression, respectively. Luciferase reporter assays demonstrated that ZEB1 can inhibit the PTEN promoter activity in MCF7 cells by binding to a motif in the PTEN promoter. Metabonomics analysis showed that SLFN5 influences many metabolic pathways and especially decreases purine metabolites, including inosine, xanthine, and hypoxanthine. In conclusion, our findings suggest that SLFN5 may be an important protective factor against BRCA, as it regulates PTEN transcription, the AKT pathway, and proliferation/apoptosis via ZEB1 mediation and inhibits the purine metabolic pathway. Thus, SLFN5 may be a potential therapeutic target for BRCA.

Tetrandrine sensitizes nasopharyngeal carcinoma cells to irradiation by inducing autophagy and inhibiting MEK/ERK pathway

Radioresistance was the main reason for local recurrence and metastasis of nasopharyngeal carcinoma. Tetrandrine is reported as an antitumor drug via inducing cell cycle arrest and apoptosis. In this study, the radiosensitization effects of maximum noncytotoxic doses of tetrandrine in nasopharyngeal carcinoma were analyzed both in vitro and in vivo, using MTT assay, western blot, TUNEL, and HE staining. It was found that the maximum dose of tetrandrine inhibited the phosphorylation of ERK and MEK induced by irradiation, and significantly enhanced irradiation-induced cell growth inhibition in nasopharyngeal carcinoma cells CNE1, CNE2, and C666-1. The ERK activator and overexpression of ERK reversed the radiosensitization effect of tetrandrine. About 50 mg/kg of tetrandrine which was used as the maximum noncytotoxic dose of tetrandrine in vivo, enhanced the radiosensitivity of the xenograft tumor and increased the apoptosis rate of the xenograft tumor cells caused by irradiation, while did not raise the side effect of the treatment. Moreover, tetrandrine increased autophagy in nasopharyngeal carcinoma cells. These results suggested that the maximum noncytotoxic dose of tetrandrine sensitized nasopharyngeal carcinoma to irradiation by inhibiting MEK/ERK pathway and inducing autophagy.

Tumor suppressive activity of miR-424-5p in breast cancer cells through targeting PD-L1 and modulating PTEN/PI3K/AKT/mTOR signaling pathway

AIMS

MicroRNAs (miRs) are key modulators of cellular processes such as proliferation, apoptosis, as well as anti-cancer immune responses. Here, we evaluated the role of miR-424-5p in breast cancer (BC) and investigated its effects on T cell-related immune response.

MAIN METHODS

BC tissues and cell lines were prepared and the expression of miR-424-5p and PD-L1, as well as the underlying molecular pathways, were assessed via qRT-PCR and western blotting. The MTT assay and flow cytometry were used to assess the effect of miR-424-5p on proliferation, apoptosis, autophagy, and cell cycle progression. The co-culture of T cells with MDA-MB-231 was performed for evaluating the role of miR-424-5p in rescuing T cell exhaustion.

KEY FINDINGS

The results indicated the down-regulation of miR-424-5p and up-regulation of PD-L1 expression in BC tissue specimens. MiR-424-5p transfection into PD-L1 overexpressing MDA-MB-231 cells decreased the expression of PD-L1. Also, miR-424-5p could reduce MDA-MB-231 cell viability through modulating apoptosis and autophagy pathways. Furthermore, miR-424-5p transfection leads to decreased colony formation and increased cell number at the G2/M phase. Western blot analysis illustrated that miR-424-5p could exert its anti-proliferative effect via modulating PTEN/PI3K/AKT/mTOR pathway. Moreover, it was demonstrated that suppression of PD-L1 by miR-424-5p could participate in regulating the expression of effector cytokines in T cells.

SIGNIFICANCE

MiR-424-5p could be considered as a potential tumor-suppressor miR in regulating BC cellular growth, apoptosis, and T cell-related immune response through targeting PD-L1, and its downstream mediators. Therefore, we recognized miR-424-5p as a promising candidate for miR restoration therapy in BC patients.

Hydroxytyrosol and Oleuropein Inhibit Migration and Invasion of MDA-MB-231 Triple-Negative Breast Cancer Cell via Induction of Autophagy

BACKGROUND

Breast Cancer (BC) is the leading cause of cancer-related deaths among women. As such, novel chemotherapeutic agents are urgently needed, especially for Triple-Negative Breast Cancer (TNBC). Hydroxytyrosol (HT) and Oleuropein (OL) are rich in olive oil, which is associated with a low occurrence of BC. However, the effects and mechanisms of action of HT and OL in BC cells are still unclear. This study aimed to explore the molecular mechanisms underlying the antitumor effect of HT and OL in TNBC.

METHODS

TNBC MDA-MB-231 cells were treated with HT and OL in combination with Hepatocyte Growth Factor (HGF), rapamycin (Rapa, an inducer of autophagy) or 3-methyladenine (3-MA, an inhibitor of autophagy). Cell viability, migration, invasion, and autophagy signaling were analyzed by scratch assays, transwell migration assays, and Western blot analysis.

RESULTS

Treatment with HT or OL reduced MDA-MB-231 cell viability in a dose-dependent manner. MDAMB- 231 cells were more sensitive to HT treatment than OL treatment. Rapa treatment could significantly block HGF-induced MDA-MB-231 cell migration and invasion, suggesting that inhibition of autophagy could promote migration and invasion. Moreover, HT or OL treatment significantly suppressed HGF or 3-MA induced cell migration and invasion by reversing LC3-II/LC3-I and Beclin-1 downregulation and reversing p62 upregulation.

CONCLUSION

These data indicated that HT and OL may inhibit migration and invasion of TNBC cells by activating autophagy. These findings provide potential therapeutic strategies that target autophagy to limit the pathogenesis and progression of BC.

Tetrandrine: a review of its anticancer potentials, clinical settings, pharmacokinetics and drug delivery systems

OBJECTIVES

Tetrandrine, a natural bisbenzylisoquinoline alkaloid, possesses promising anticancer activities on diverse tumours. This review provides systematically organized information on cancers of tetrandrine in vivo and in vitro, discuss the related molecular mechanisms and put forward some new insights for the future investigations.

KEY FINDINGS

Anticancer activities of tetrandrine have been reported comprehensively, including lung cancer, colon cancer, bladder cancer, prostate cancer, ovarian cancer, gastric cancer, breast cancer, pancreatic cancer, cervical cancer and liver cancer. The potential molecular mechanisms corresponding to the anticancer activities of tetrandrine might be related to induce cancer cell apoptosis, autophagy and cell cycle arrest, inhibit cell proliferation, migration and invasion, ameliorate metastasis and suppress tumour cell growth. Pharmaceutical applications of tetrandrine combined with nanoparticle delivery system including liposomes, microspheres and nanoparticles with better therapeutic efficiency have been designed and applied encapsulate tetrandrine to enhance its stability and efficacy in cancer treatment.

SUMMARY

Tetrandrine was proven to have definite antitumour activities. However, the safety, bioavailability and pharmacokinetic parameter studies on tetrandrine are very limited in animal models, especially in clinical settings. Our present review on anticancer potentials of tetrandrine would be necessary and highly beneficial for providing guidelines and directions for further research of tetrandrine.

Anticancer Activity of Tetrandrine by Inducing Apoptosis in Human Breast Cancer Cell Line MDA-MB-231 In Vivo

Tetrandrine (TET) is an alkaloid extracted from a traditional Chinese medicinal plant. It exerts remarkable anticancer activity and induces apoptotic cell death in various human cancer cells. The present study aimed to investigate the effects of TET on the inhibition of tumor growth and the induction of apoptosis in MDA-MB-231 breast cancer in xenograft mice. Tumor weight and volume were measured. The histopathological changes in the tumor tissue were observed. Immunohistochemistry analysis of Bcl-2-associated X protein (Bax) and B-cell lymphoma/leukemia-2 (Bcl-2) was carried out. The expression of apoptosis-associated genes and proteins, such as cysteine aspartic acid-specific protease-3 (Caspase-3), Survivin, Bax, Bcl-2, BH3-interacting domain death agonist (Bid), and poly ADP-ribose polymerase (PARP), was measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. TET inhibited tumor growth and induced apoptosis in TNBC cell line MDA-MB-231. The mechanism underlying this effect might be mediated by TET-upregulated Caspase-3, Bax, and Bid and downregulated by Bcl-2, Survivin, and PARP. Taken together, this study supported the fact that TET is a promising therapeutic agent for the treatment of TNBC, thereby providing experimental evidence for its use in the treatment of breast cancer.

Tetrandrine Reverses Paclitaxel Resistance in Human Ovarian Cancer via Inducing Apoptosis, Cell Cycle Arrest Through β-Catenin Pathway

Background

Paclitaxel (PTX) resistance is a great obstacle for the treatment of ovarian cancer. A previous study indicated that tetrandrine (TET) could induce the apoptosis of ovarian cancer cells. This study aimed to explore the effect of TET in combination with PTX on PTX resistance in ovarian cancer cells.

Materials and Methods

CCK-8 assay, flow cytometry and wound healing assays were used to detect the proliferation, apoptosis and migration of PTX-resistant SKOV3 cells (SKOV3/PTX). The expressions of Bax, Bcl-2, cleaved caspase 3, β-catenin, c-Myc, cyclin D1 and p21 in SKOV3/PTX cells were detected with Western blot. In vivo animal study was performed finally.

Results

In this study, the inhibitory effects of PTX on the proliferation and migration of SKOV3/PTX cells were markedly enhanced by TET. In addition, PTX-induced apoptosis in SKOV3/PTX cells was significantly enhanced by the treatment of TET via upregulating the levels of Bax and cleaved caspase 3, and downregulating the expression of Bcl-2. Moreover, combination of TET and PTX obviously induced cell cycle arrest in SKOV3/PTX cells via increasing the level of p21 and decreasing the levels of c-Myc and Cyclin D1. Meanwhile, combination of TET with PTX significantly decreased the expression of β-catenin in SKOV3/PTX cells. In vivo experiments further confirmed that TET enhanced the anti-tumor effect of PTX in SKOV3/PTX xenograft model.

Conclusion

We found that TET could enhance the sensitivity of SKOV3/PTX cells to PTX via inhibiting the β-catenin/c-Myc/Cyclin D1 signaling pathway. Therefore, PTX combined with TET might be considered as a potential approach for the treatment of PTX-resistant ovarian cancer.

Hydroxytyrosol and Oleuropein Inhibit Migration and Invasion via Induction of Autophagy in ER-Positive Breast Cancer Cell Lines (MCF7 and T47D)

Hydroxytyrosol (HT) and oleuropein (OL), the most abundant of the phenolic compounds in olives, have anticancer properties against breast cancer (BC). However, little attention has been paid to the mechanism of HT or OL in BC cells. The objective of this study was to identify the underlying molecular mechanisms of these compounds. ER-positive BC MCF7 and T47D cells were treated with HT and OL in combination with hepatocyte growth factor (HGF), rapamycin (Rapa, an agonist of autophagy) or 3-methyladenine (3-MA, an inhibitor of autophagy). Cell viability, metastasis capability and autophagy-related proteins were evaluated by wound healing assays, Transwell assays and Western blot. HT and OL reduced the cell viability of MCF-7 and T47D cells in a dose-dependent manner. Both cells were more sensitive to HT than OL. In addition, Rapa significantly inhibited HGF-induced migration and invasion, indicating that metastases of both BC cells could be inhibited by suppression of autophagy. Moreover, HT and OL significantly blocked HGF- or 3-MA-induced cell migration and invasion by reversing LC3II/LC3I and Beclin-1 downregulation and p62 upregulation. These findings revealed that HT and OL could suppress migration and invasion by activating autophagy in ER-positive BC cells, which might be a promising therapeutic strategy.

Cell-Free Coelomic Fluid Extracts of the Sea Urchin Arbacia lixula Impair Mitochondrial Potential and Cell Cycle Distribution and Stimulate Reactive Oxygen Species Production and Autophagic Activity in Triple-Negative MDA-MB231 Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a highly malignant tumor histotype which lacks effective targeted therapies, thereby being considered as the most aggressive form of breast carcinoma. To identify novel compounds which could counteract TNBC cell growth, we explored the in vitro effects of crude extracts and <10 kDa-filtered fractions of the coelomic fluid obtained from the sea urchin Arbacia lixula on TNBC MDA-MB231 cells. We examined cell viability, cycle distribution, apoptotic/autophagic activity, and mitochondrial polarization/cell redox status. Here, we report the first data demonstrating an anti-TNBC effect by A. lixula-derived coelomic fluid extracts. Thus, identification of the water-soluble bioactive component(s) contained in the extracts deserve(s) further investigation aimed to devise novel promising prevention and/or treatment agents effective against highly malignant breast tumors.

Fangjihuangqi Decoction inhibits MDA-MB-231 cell invasion in vitro and decreases tumor growth and metastasis in triple-negative breast cancer xenografts tumor zebrafish model

Triple-negative breast cancer (TNBC) is a basal-like cancer which is considered to be more intrusive, have a poorer prognosis and chemoresistance. TNBC is characterized by the presence of epithelial to mesenchymal transition (EMT) that plays a major role in the progression of the cancer. In the present study, we first use a classic prescription of Chinese medicine Fangjihuangqi Decoction to treat TGFβ1-induced MDA-MB-231 cells in vitro. Our data showed that TGFβ1-induced MDA-MB-231 cell morphology change, promoted MDA-MB 231 invasion, increased Vimentin expression, and decreased E-cadherin expression. Further, Fangjihuangqi Decoction-medicated serum (FHS) treated both MDA-MB 231 cells and TGFβ1-induced MDA-MB-231 cells. Results showed that Fangjihuangqi Decoction could inhibit cell proliferation, reduce cell invasion, increase E-cadherin expression, and decrease EMT markers. Secondly, we established a xenograft tumor zebrafish model to assess Fangjihuangqi Decoction inhibition of cancer cell proliferation and invasion. Our results indicated that Fangjihuangqi Decoction could inhibit tumor growth, restrain the sprouts number of tumor neovascularization, and reduce the length of tumor neoplastic lymphatics by increasing E-cadherin expression and decreasing EMT markers in TNBC xenograft tumor zebrafish model. Overall, our studies provide evidences that Fangjihuangqi Decoction could inhibit TNBC, reverse EMT, and contribute to antimetastasis by increasing E-cadherin expression and decreasing EMT markers, which provide an experimental basis for clinical application of Fangjihuangqi Decoction on TNBC treatment.

A critical review: traditional uses, phytochemistry, pharmacology and toxicology of Stephania tetrandra S. Moore (Fen Fang Ji)

ABSTRACT

Stephania tetrandra S. Moore (S. tetrandra) is distributed widely in tropical and subtropical regions of Asia and Africa. The root of this plant is known in Chinese as "Fen Fang Ji". It is commonly used in traditional Chinese medicine to treat arthralgia caused by rheumatism, wet beriberi, dysuria, eczema and inflamed sores. Although promising reports have been published on the various chemical constituents and activities of S. tetrandra, no review comprehensively summarizes its traditional uses, phytochemistry, pharmacology and toxicology. Therefore, the review aims to provide a critical and comprehensive evaluation of the traditional use, phytochemistry, pharmacological properties, pharmacokinetics and toxicology of S. tetrandra in China, and meaningful guidelines for future investigations.

Cytotoxic Potential of the Coelomic Fluid Extracted from the Sea Cucumber Holothuria tubulosa against Triple-Negative MDA-MB231 Breast Cancer Cells

Growing evidence has demonstrated that the extracts of different holothurian species exert beneficial effects on human health. Triple negative breast cancers (TNBC) are highly malignant tumors that present a poor prognosis due to the lack of effective targeted therapies. In the attempt to identify novel compounds that might counteract TNBC cell growth, we studied the effect of the exposure of the TNBC cell line MDA-MB231 to total and filtered aqueous extracts of the coelomic fluid obtained from the sea cucumber Holoturia tubulosa, a widespread species in the Mediterranean Sea. In particular, we examined cell viability and proliferative behaviour, cell cycle distribution, apoptosis, autophagy, and mitochondrial metabolic/cell redox state. The results obtained indicate that both total and fractionated extracts are potent inhibitors of TNBC cell viability and growth, acting through both an impairment of cell cycle progression and mitochondrial transmembrane potential and a stimulation of cellular autophagy, as demonstrated by the increase of the acidic vesicular organelles and of the intracellular protein markers beclin-1, and total LC3 and LC3-II upon early exposure to the preparations. Identification of the water-soluble bioactive component(s) present in the extract merit further investigation aiming to develop novel prevention and/or treatment agents efficacious against highly metastatic breast carcinomas.

Metformin represses the pathophysiology of AAA by suppressing the activation of PI3K/AKT/mTOR/autophagy pathway in ApoE-/- mice

Background

The protective effect of metformin (MET) on abdominal aortic aneurysm (AAA) has been reported. However, the related mechanism is still poor understood. In this study, we deeply investigated the role of metformin in AAA pathophysiology.

Methods

Angiotensin II (Ang-II) was used to construct the AAA model in ApoE^−/− mice. The related mechanism was explored using Western blot and quantitative real time PCR (qRT-PCR). We also observed the morphological changes in the abdominal aorta and the influence of metformin on biological behaviors of rat abdominal aortic VSMCs.

Results

The PI3K/AKT/mTOR pathway was activated in aneurysmal wall tissues of AAA patients and rat model. Treatment with metformin inhibited the breakage and preserved the elastin structure of the aorta, the loss of collagen, and the apoptosis of aortic cells. In addition, metformin significantly suppressed the activation of the PI3K/AKT/mToR pathway and decreased the mRNA and protein levels of LC3B and Beclin1, which were induced by Ang-II. Moreover, PI3K inhibitors enhanced the effect of metformin while PI3K agonists largely reversed this effect. Interestingly, the cell proliferation, apoptosis, migration and autophagy of vascular smooth muscle cells (VSMCs) induced by Ang-II were also decreased following metformin treatment. PI3K inhibitors and agonists strengthened and weakened the effects of metformin in VSMCs, respectively.

Conclusions

Metformin represses the pathophysiology of AAA by inhibiting the activation of PI3K/AKT/mTOR/autophagy pathway. This repression may be useful as a new therapeutic strategy for AAA.

Insight into the roles of tyrosine on rCHO cell performance in fed-batch cultures

Tyrosine (Tyr), as one of the least soluble amino acids, is essential to monoclonal antibody (mAb) production in recombinant Chinese hamster ovary (rCHO) cell cultures since its roles on maintaining the specific productivity (q_mAb) and avoiding Tyr sequence variants. To understand the effects of Tyr on cell performance and its underlying mechanisms, rCHO cell-producing mAbs were cultivated at various cumulative Tyr addition concentrations (0.6 to 5.5 mM) in fed-batch processes. Low Tyr concentrations gave a much lower peak viable cell density (VCD) during the growth phase and also induced rapid cell death and pH decrease during the production phase, resulting in a low efficient fed-batch process. Autophagy was initiated following the inhibition of mTOR under the Tyr starvation condition. Excessive autophagy subsequently induced autophagic cell death, which was found as the major type of cell death in this study. Additionally, the results obtained here demonstrate that the decrease in culture pH under the Tyr starvation condition was associated with the autophagy and such pH drop might be attributed to the lysosome acidification and cell lysis.