Dietary compound isoliquiritigenin targets GRP78 to chemosensitize breast cancer stem cells via β-catenin/ABCG2 signaling

Isoliquiritigenin limits inflammasome activation of macrophage via docking into Syk to alleviate murine non-alcoholic fatty liver disease

Isoliquiritigenin (ISL) is a chalcone-type flavonoid derived from the root of licorice with antioxidant, anti-inflammatory, anti-tumour and neuroprotective properties. ISL has been proven to downregulate the productions of IL-1β, TNF-α and IL-6 by macrophages. However, detailed molecular mechanisms of this modulation remain elusive. Here, ISL suppressed Syk phosphorylation and CD80, CD86, IL-1β, TNF-α and IL-6 expressions in lipopolysaccharide-stimulated macrophages ex vivo. ApoC3-transgenic (ApoC3TG) mice had more activated macrophages. ISL was also able to downregulate the inflammatory activities of macrophages from ApoC3TG mice. Administration of ISL inhibited Syk activation and inflammatory activities of macrophages in ApoC3TG mice in vivo. The treatment of ISL further alleviated MCD-induced non-alcoholic fatty liver disease (NAFLD) in wild-type and ApoC3TG mice, accompanied by less recruitment and activation of liver macrophages. Due to the inhibition of Syk phosphorylation, ISL-treated macrophages displayed less production of cytoplasmic ROS, NLRP3, cleaved-GSDMD and cleaved-IL-1β, suggesting less inflammasome activation. Finally, the molecular docking study demonstrated that ISL bound to Syk directly with the Kd of 1.273 × 10-8 M. When the Syk expression was knocked down by its shRNA, the inhibitory effects of ISL on activated macrophages disappeared, indicating that Syk was at least one of key docking-molecules of ISL. Collectively, ISL could alleviate MCD-induced NAFLD in mice involved with the inhibition of macrophage inflammatory activity by the blockade of Syk-induced inflammasome activation.

Recent strategies to overcome breast cancer resistance

Breast cancer is potentially a lethal disease and a leading cause of death in women. Chemotherapy and radiotherapy are the most frequently used treatment options. Drug resistance in advanced breast cancer limits the therapeutic output of treatment. The leading cause of resistance in breast cancer is endocrine and hormonal imbalance, particularly in triple negative and HER2 positive breast cancers. The efflux of drugs due to p-gp's activity is another leading cause of resistance. Breast cancer resistant protein also contributes significantly. Strategies used to combat resistance include the use of nanoparticles to target drug delivery by co-delivery of chemotherapeutic drugs and genes (siRNA and miRNA) that help to down-regulate genes causing resistance. The siRNA is specific and effectively silences p-gp and other proteins causing resistance. The use of chemosensitizers is also effective in overcoming resistance. Chemo-sensitizers sensitize cancer cells to the effects of chemotherapeutic drugs. Novel anti-neoplastic agents such as antibody-drug conjugates and mesenchymal stem cells are also effective tools used to improve the therapeutic response in breast cancer. Similarly, combination of photo/thermal ablation with chemotherapy can act to overcome breast cancer resistance. In this review, we focus on the mechanism of breast cancer resistance and the nanoparticle-based strategies used to combat resistance in breast cancer.

The crucial role of fascin-1 in the pathogenesis, metastasis, and chemotherapeutic resistance of breast cancer

Breast cancer (BC) is the most common type of cancer in women to be diagnosed, and it is also the second leading cause of cancer death in women globally. It is the disease that causes the most life years adjusted for disability lost among women, making it a serious worldwide health issue. Understanding and interpreting carcinogenesis and metastatic pathways is critical for curing malignancy. Fascin-1 was recognized as an actin-bundling protein with parallel, rigid bundles as a result of the cross-linking of F-actin microfilaments. Increasing levels of fascin-1 have been associated with bad prognostic profiles, aggressiveness of clinical courses, and poor survival outcomes in a variety of human malignancies. Cancer cells that overexpress fascin-1 have higher capabilities for proliferation, invasion, migration, and metastasis. Fascin-1 is being considered as a potential target for therapy as well as a potential biomarker for diagnostics in a variety of cancer types. This review aims to provide an overview of the FSCN1 gene and its protein structure, elucidate its physiological and pathological roles, and throw light on its involvement in the initiation, development, and chemotherapeutic resistance of BC.

Recent advances in small molecule and peptide inhibitors of glucose-regulated protein 78 for cancer therapy

Glucose-regulated protein 78 (GRP78) is one of key endoplasmic reticulum (ER) chaperone proteins that regulates the unfolded protein response (UPR) to maintain ER homeostasis. As a core factor in the regulation of the UPR, GRP78 takes a critical part in the cellular processes required for tumorigenesis, such as proliferation, metastasis, anti-apoptosis, immune escape and chemoresistance. Overexpression of GRP78 is closely correlated with tumorigenesis and poor prognosis in various malignant tumors. Targeting GRP78 is regarded as a potentially promising therapeutic strategy for cancer therapy. Although none of the GRP78 inhibitors have been approved to date, there have been several studies of GRP78 inhibitors. Herein, we comprehensively review the structure, physiological functions of GRP78 and the recent progress of GRP78 inhibitors, and discuss the structures, in vitro and in vivo efficacies, and merits and demerits of these inhibitors to inspire further research. Additionally, the feasibility of GRP78-targeting proteolysis-targeting chimeras (PROTACs), disrupting GRP78 cochaperone interactions, or covalent inhibition are also discussed as novel strategies for drugs discovery targeting GRP78, with the hope that these strategies can provide new opportunities for targeted GRP78 antitumor therapy.

A comprehensive review: Botany, phytochemistry, traditional uses, pharmacology, and toxicology of Spatholobus suberectus vine stems

ETHNOPHARMACOLOGICAL RELEVANCE

Spatholobus suberectus vine stem (SSVS) is the dried lianoid stem of the leguminous plant, Spatholobus suberectus Dunn, which is mainly distributed in China and some Southeast Asian countries. Due to its notable effects of promoting blood circulation and tonifying blood, regulating menstruation and relieving pain, this phytomedicine has been used in traditional Chinese medicine for hundreds of years.

AIM OF THE STUDY

This review is designed to provide a comprehensive profile of SSVS concerning its botany, traditional uses, phytochemistry, quality control, pharmacology, pharmacokinetics, and toxicology and attempts to provide a scientific basis and future directions for further research and development.

MATERIALS AND METHODS

Related document information was collected with the help of databases such as the Web of Science, Science Direct, PubMed, China National Knowledge Infrastructure (CNKI) and Flora of China.

RESULTS

SSVS is reported to be traditionally used to treat rheumatic arthralgia, numbness and paralysis, blood deficiency, irregular menstruation and other gynecological diseases. Botanical studies have revealed that there are some confusable varieties in some specific locations with a long history. Additionally, 145 chemical constituents have been isolated and identified from SSVS, including flavonoids, organic acids, terpenoids, lignans, and phenolic glycosides. Pharmacological studies have shown that SSVS has a variety of effects, such as nervous system regulation, and antioxidative, antitumor, antiviral, antidiabetic, and anti-inflammatory effects. However, in regard to the absorption-distribution-metabolism-elimination-toxicity (ADMET) of SSVS, few studies have been carried out, and few articles have been published.

CONCLUSION

With a long history of traditional uses, a variety of bioactive phytochemicals and a wide range of definite pharmacological activities, SSVS is believed to have great potential in clinical applications and further research, development and exploitation. The precise action mechanisms, rational quality control and quality markers, and explicit ADMET routes should be highlighted in the future, which might provide effective help to safely, effectively and sustainably use this herbal medicine.

Anticancer Potential of Natural Chalcones: In Vitro and In Vivo Evidence

There is no doubt that significant progress has been made in tumor therapy in the past decades. However, the discovery of new molecules with potential antitumor properties still remains one of the most significant challenges in the field of anticancer therapy. Nature, especially plants, is a rich source of phytochemicals with pleiotropic biological activities. Among a plethora of phytochemicals, chalcones, the bioprecursors of flavonoid and isoflavonoids synthesis in higher plants, have attracted attention due to the broad spectrum of biological activities with potential clinical applications. Regarding the antiproliferative and anticancer effects of chalcones, multiple mechanisms of action including cell cycle arrest, induction of different forms of cell death and modulation of various signaling pathways have been documented. This review summarizes current knowledge related to mechanisms of antiproliferative and anticancer effects of natural chalcones in different types of malignancies including breast cancers, cancers of the gastrointestinal tract, lung cancers, renal and bladder cancers, and melanoma.

Glycyrrhizae Radix et Rhizoma: The popular occurrence of herbal medicine applied in classical prescriptions

Glycyrrhizae Radix et Rhizoma is a well-known herbal medicine with a wide range of pharmacological functions that has been used throughout Chinese history. This review presents a comprehensive introduction to this herb and its classical prescriptions. The article discusses the resources and distribution of species, methods of authentication and determination chemical composition, quality control of the original plants and herbal medicines, dosages use, common classical prescriptions, indications, and relevant mechanisms of the active content. Pharmacokinetic parameters, toxicity tests, clinical trials, and patent applications are discussed. The review will provide a good starting point for the research and development of classical prescriptions to develop herbal medicines for clinical use.

Tumor Microenvironment-Responsive Nanoherb Delivery System for Synergistically Inhibition of Cancer Stem Cells

Multidrug resistance in cancer stem cells (CSCs) is a major barrier to chemotherapy; hence, developing CSC-specific targeted nanocarriers for efficient drug delivery is critical. In this study, monodisperse hollow-structured MnO₂ (H-MnO₂) with a mesoporous shell was created for efficient targeted drug delivery. An effective therapeutic compound isoliquiritigenin (ISL) was confirmed to inhibit the lung cancer stem-cell phenotype by natural compound screening based on integrated microfluidic devices. The resultant H-MnO₂ showed a high drug-loading content of the potent CSC-targeting compound ISL and near-infrared fluorescent dye indocyanine green (ICG). In addition, H-MnO₂ was successively modified with hyaluronic acid (HA) to enhance targeting CSCs with high CD44 expression levels. The H-MnO₂@(ICG + ISL)@HA nanocomposites displayed promising chemotherapeutic and photothermal treatment capabilities, as well as NIR-triggered drug release, which showed excellent CSC-killing effects and tumor inhibition efficacy. Meanwhile, the development of the tumor was effectively restrained by NIR-triggered phototherapy and prominent chemotherapy without obvious side effects after tail vein injection of the nanocomposites in vivo. In summary, the prepared nanocomposites accomplished synergistic cancer therapy that targets CSCs, offering a versatile platform for lung cancer diagnosis and treatment.

HSP70 Family in Cancer: Signaling Mechanisms and Therapeutic Advances

The 70 kDa heat shock proteins (HSP70s) are a group of highly conserved and inducible heat shock proteins. One of the main functions of HSP70s is to act as molecular chaperones that are involved in a large variety of cellular protein folding and remodeling processes. HSP70s are found to be over-expressed and may serve as prognostic markers in many types of cancers. HSP70s are also involved in most of the molecular processes of cancer hallmarks as well as the growth and survival of cancer cells. In fact, many effects of HSP70s on cancer cells are not only related to their chaperone activities but rather to their roles in regulating cancer cell signaling. Therefore, a number of drugs directly or indirectly targeting HSP70s, and their co-chaperones have been developed aiming to treat cancer. In this review, we summarized HSP70-related cancer signaling pathways and corresponding key proteins regulated by the family of HSP70s. In addition, we also summarized various treatment approaches and progress of anti-tumor therapy based on targeting HSP70 family proteins.

Role of Medicinal plant-derived Nutraceuticals as a potential target for the treatment of breast cancer

Breast cancer (BC) is one of the most challenging cancers to treat, accounting for many cancer-related deaths. Over some years, chemotherapy, hormone treatment, radiation, and surgeries have been used to treat cancer. Unfortunately, these treatment options are unsuccessful due to crucial adverse reactions and multidrug tolerance/resistance. Although it is clear that substances in the nutraceuticals category have a lot of anti-cancer activity, using a supplementary therapy strategy, in this case, could be very beneficial. Nutraceuticals are therapeutic agents, which are nutrients that have drug-like characteristics and can be used to treat diseases. Plant nutraceuticals categorized into polyphenols, terpenoids, vitamins, alkaloids, and flavonoids are part of health food products, that have great potential for combating BC. Nutraceuticals can reduce BC's severity, limit malignant cell growth, and modify cancer-related mechanisms. Nutraceuticals acting by attenuating Hedgehog, Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Notch, and Wnt/β-catenin signaling are the main pathways in controlling the self-renewal of breast cancer stem cells (BCSCs). This article reviews some important nutraceuticals and their modes of action, which can be very powerful versus BC. PRACTICAL APPLICATIONS: Nutraceuticals' importance to the control and diagnosis of breast cancer is undeniable and cannot be overlooked. Natural dietary compounds have a wide range of uses and have been used in traditional medicine. In addition, these natural chemicals can enhance the effectiveness of other traditional medicines. They may also be used as a treatment process independently because of their capacity to affect several cancer pathways. This study highlights a variety of natural chemicals, and their mechanisms of action, routes, synergistic effects, and future potentials are all examined.

A Review of the Pharmacological Potential of Spatholobus suberectus Dunn on Cancer

Spatholobus suberectus Dunn (SSD) has been extensively employed in Traditional Chinese Medicine to treat several ailments. SSD and its active compounds are effective therapeutic agents for treating a variety of diseases with negligible side effects. Therefore, we aimed to investigate its phytochemistry, pharmacology, and potential therapeutic effects exclusively in cancer prevention and treatment. Phytochemical and pharmacological information was collected and arranged in a rational order. SSD has been frequently attributed to having antioxidant, anti-diabetic, anti-inflammatory, hematopoietic, neuroprotective, antimicrobial, and anticancer properties. Evidence has indicated that the bioactive constituents in SSD have attracted increasing scientific attention due to their preventive role in cancers. Further, the present review provides the current information on the health implications of SSD, thus allowing for future clinical trials to explore its restorative benefits. All data of in vitro and animal investigations of SSD, as well as its effect on human health, were obtained from an electronic search and library database. The diverse pharmacological potential of SSD provides an opportunity for preclinical drug discovery, and this comprehensive review strongly indicates that SSD is an excellent anti-tumorigenic agent that modulates or prevents breast cancer.

Natural products as chemo-radiation therapy sensitizers in cancers

Cancer is a devastating disease and is the second leading cause of death worldwide. Surgery, chemotherapy (CT), and/or radiation therapy (RT) are the treatment of choice for most advanced tumors. Unfortunately, treatment failure due to intrinsic and acquired resistance to the current CT and RT is a significant challenge associated with poor patient prognosis. There is an urgent need to develop and identify agents that can sensitize tumor cells to chemo-radiation therapy (CRT) with minimal cytotoxicity to the healthy tissues. While many recent studies have identified the underlying molecular mechanisms and therapeutic targets for CRT failure, using small molecule inhibitors to chemo/radio sensitize tumors is associated with high toxicity and increased morbidity. Natural products have long been used as chemopreventive agents in many cancers. Combining many of these compounds with the standard chemotherapeutic agents or with RT has shown synergistic effects on cancer cell death and overall improvement in patient survival. Based on the available data, there is strong evidence that natural products have a robust therapeutic potential along with CRT and their well-known chemopreventive effects in many solid tumors. This review article reports updated literature on different natural products used as CT or RT sensitizers in many solid tumors. This is the first review discussing CT and RT sensitizers together in cancer.

The Chaperone System in Breast Cancer: Roles and Therapeutic Prospects of the Molecular Chaperones Hsp27, Hsp60, Hsp70, and Hsp90

Breast cancer (BC) is a major public health problem, with key pieces of information needed for developing preventive and curative measures still missing. For example, the participation of the chaperone system (CS) in carcinogenesis and anti-cancer responses is poorly understood, although it can be predicted to be a crucial factor in these mechanisms. The chief components of the CS are the molecular chaperones, and here we discuss four of them, Hsp27, Hsp60, Hsp70, and Hsp90, focusing on their pro-carcinogenic roles in BC and potential for developing anti-BC therapies. These chaperones can be targets of negative chaperonotherapy, namely the elimination/blocking/inhibition of the chaperone(s) functioning in favor of BC, using, for instance, Hsp inhibitors. The chaperones can also be employed in immunotherapy against BC as adjuvants, together with BC antigens. Extracellular vesicles (EVs) in BC diagnosis and management are also briefly discussed, considering their potential as easily accessible carriers of biomarkers and as shippers of anti-cancer agents amenable to manipulation and controlled delivery. The data surveyed from many laboratories reveal that, to enhance the understanding of the role of the CS in BS pathogenesis, one must consider the CS as a physiological system, encompassing diverse members throughout the body and interacting with the ubiquitin–proteasome system, the chaperone-mediated autophagy machinery, and the immune system (IS). An integrated view of the CS, including its functional partners and considering its highly dynamic nature with EVs transporting CS components to reach all the cell compartments in which they are needed, opens as yet unexplored pathways leading to carcinogenesis that are amenable to interference by anti-cancer treatments centered on CS components, such as the molecular chaperones.

Isoliquiritigenin Inhibits Gastric Cancer Stemness, Modulates Tumor Microenvironment, and Suppresses Tumor Growth through Glucose-Regulated Protein 78 Downregulation

Chemotherapy is the treatment of choice for gastric cancer; however, the currently available therapeutic drugs for treatment have limited efficacy. Cancer stemness and the tumor microenvironment may play crucial roles in tumor growth and chemoresistance. Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum chaperone facilitating protein folding and cell homeostasis during stress and may participate in chemoresistance. Isoliquiritigenin (ISL) is a bioactive flavonoid found in licorice. In this study, we demonstrated the role of GRP78 in gastric cancer stemness and evaluated GRP78-mediated stemness inhibition, tumor microenvironment regulation, and chemosensitivity promotion by ISL. ISL not only suppressed GRP78-mediated gastric cancer stem cell–like characteristics, stemness-related protein expression, and cancer-associated fibroblast activation but also gastric tumor growth in xenograft animal studies. The findings indicated that ISL is a promising candidate for clinical use in combination chemotherapy.

The Potential of Plant-Derived Extracts and Compounds to Augment Anticancer Effects of Chemotherapeutic Drugs

Plant extracts comprise a complex mixture of natural compounds with diverse biological activities including anticancer activities. This has made the use of plant extracts a trending strategy in cancer treatment. In addition, plants' active constituents such as polyphenols could confer protective effects on normal cells against damage by free radicals as well as lessen the toxicity of chemotherapeutic drugs. Recently, many emerging studies revealed the combinatory uses of plant extracts and individual therapeutic compounds that could be a promising panacea in hampering multiple signaling pathways involved in cancer development and progression. Besides enhancing the therapeutic efficacy, this has also been proven to reduce the dosage of chemotherapeutic drugs used, and hence overcome multiple drug resistance and minimize treatment side effects. Notably, combined use of plant extracts with chemotherapeutics drugs was shown to enhance anticancer effects through modulating various signaling pathways, such as P13K/AKT, NF-κB, JNK, ERK, WNT/β-catenin, and many more. Hence, this review aims to comprehensively summarize both In Vitro and In Vivo mechanisms of actions of well-studied plant extracts, such as Ganoderma Lucidum, Korean red ginseng, Garcinia sp., curcumin, and luteolin extracts in augmenting anticancer properties of the conventional chemotherapeutic drugs from an extensive literature search of recent publications.

Repurposing Multiple-Molecule Drugs for COVID-19-Associated Acute Respiratory Distress Syndrome and Non-Viral Acute Respiratory Distress Syndrome via a Systems Biology Approach and a DNN-DTI Model Based on Five Drug Design Specifications

The coronavirus disease 2019 (COVID-19) epidemic is currently raging around the world at a rapid speed. Among COVID-19 patients, SARS-CoV-2-associated acute respiratory distress syndrome (ARDS) is the main contribution to the high ratio of morbidity and mortality. However, clinical manifestations between SARS-CoV-2-associated ARDS and non-SARS-CoV-2-associated ARDS are quite common, and their therapeutic treatments are limited because the intricated pathophysiology having been not fully understood. In this study, to investigate the pathogenic mechanism of SARS-CoV-2-associated ARDS and non-SARS-CoV-2-associated ARDS, first, we constructed a candidate host-pathogen interspecies genome-wide genetic and epigenetic network (HPI-GWGEN) via database mining. With the help of host-pathogen RNA sequencing (RNA-Seq) data, real HPI-GWGEN of COVID-19-associated ARDS and non-viral ARDS were obtained by system modeling, system identification, and Akaike information criterion (AIC) model order selection method to delete the false positives in candidate HPI-GWGEN. For the convenience of mitigation, the principal network projection (PNP) approach is utilized to extract core HPI-GWGEN, and then the corresponding core signaling pathways of COVID-19-associated ARDS and non-viral ARDS are annotated via their core HPI-GWGEN by KEGG pathways. In order to design multiple-molecule drugs of COVID-19-associated ARDS and non-viral ARDS, we identified essential biomarkers as drug targets of pathogenesis by comparing the core signal pathways between COVID-19-associated ARDS and non-viral ARDS. The deep neural network of the drug–target interaction (DNN-DTI) model could be trained by drug–target interaction databases in advance to predict candidate drugs for the identified biomarkers. We further narrowed down these predicted drug candidates to repurpose potential multiple-molecule drugs by the filters of drug design specifications, including regulation ability, sensitivity, excretion, toxicity, and drug-likeness. Taken together, we not only enlighten the etiologic mechanisms under COVID-19-associated ARDS and non-viral ARDS but also provide novel therapeutic options for COVID-19-associated ARDS and non-viral ARDS.

Down-regulating GRP78 reverses pirarubicin resistance of triple negative breast cancer by miR-495-3p mimics and involves the p-AKT/mTOR pathway

Due to the lack of known therapeutic targets for triple-negative breast cancer (TNBC), chemotherapy is the only available pharmacological treatment. Pirarubicin (tetrahydropyranyl Adriamycin, THP) is the most commonly used anthracycline chemotherapy agent. However, TNBC has a high recurrence rate after chemotherapy, and the mechanisms of chemoresistance and recurrence are not entirely understood. To study the chemoresistance mechanisms, we first screened compounds on a pirarubicin-resistant cell line (MDA-MB-231R) derived from MDA-MB-231. The drug resistance index of MDA-MB-231R cells was approximately five times higher than that of MDA-MB-231 cells. MDA-MB-231R cells have higher GRP78 and lower miR-495-3p expression levels than MDA-MB-231 cells. Transfecting MDA-MB-231R cells with a siGRP78 plasmid reduced GRP78 expression, which restored pirarubicin sensitivity. Besides, transfecting MDA-MB-231R cells with miR-495-3p mimics increased miR-495-3p expression, which also reversed pirarubicin chemoresistance. Cell counting kit-8 (CCK-8), EdU, wound healing, and Transwell assays showed that the miR-495-3p mimics also inhibited cell proliferation and migration. Based on our results, miR-495-3p mimics could down-regulate GRP78 expression via the p-AKT/mTOR signaling pathway in TNBC cells. Remarkably, chemo-resistant and chemo-sensitive TNBC tissues had opposite trends in GRP78 and miR-495-3p expressions. The lower the GRP78 and the higher the miR-495-3p expression, the better prognosis in TNBC patients. Therefore, the mechanism of pirarubicin resistance might involve the miR-495-3p/GRP78/Akt axis, which would provide a possible strategy for treating TNBC.

Glycyrrhiza glabra (Licorice): A Comprehensive Review on Its Phytochemistry, Biological Activities, Clinical Evidence and Toxicology

There are more than 30 species of Glycyrrhiza genus extensively spread worldwide. It was the most prescribed herb in Ancient Egyptian, Roman, Greek, East China, and the West from the Former Han era. There are various beneficial effects of licorice root extracts, such as treating throat infections, tuberculosis, respiratory, liver diseases, antibacterial, anti-inflammatory, and immunodeficiency. On the other hand, traditional medicines are getting the attraction to treat many diseases. Therefore, it is vital to screen the medicinal plants to find the potential of new compounds to treat chronic diseases such as respiratory, cardiovascular, anticancer, hepatoprotective, etc. This work comprehensively reviews ethnopharmacological uses, phytochemistry, biological activities, clinical evidence, and the toxicology of licorice, which will serve as a resource for future clinical and fundamental studies. An attempt has been made to establish the pharmacological effect of licorice in different diseases. In addition, the focus of this review article is on the molecular mechanism of licorice extracts and their four flavonoids (isoliquiritigenin, liquiritigenin, lichalocone, and glabridin) pharmacologic activities. Licorice could be a natural alternative for current therapy to exterminate new emerging disorders with mild side effects. This review will provide systematic insights into this ancient drug for further development and clinical use.

HSP70s in Breast Cancer: Promoters of Tumorigenesis and Potential Targets/Tools for Therapy

The high frequency of breast cancer worldwide and the high mortality among women with this malignancy are a serious challenge for modern medicine. A deeper understanding of the mechanisms of carcinogenesis and emergence of metastatic, therapy-resistant breast cancers would help development of novel approaches to better treatment of this disease. The review is dedicated to the role of members of the heat shock protein 70 subfamily (HSP70s or HSPA), mainly inducible HSP70, glucose-regulated protein 78 (GRP78 or HSPA5) and GRP75 (HSPA9 or mortalin), in the development and pathogenesis of breast cancer. Various HSP70-mediated cellular mechanisms and pathways which contribute to the oncogenic transformation of mammary gland epithelium are reviewed, as well as their role in the development of human breast carcinomas with invasive, metastatic traits along with the resistance to host immunity and conventional therapeutics. Additionally, intracellular and cell surface HSP70s are considered as potential targets for therapy or sensitization of breast cancer. We also discuss a clinical implication of Hsp70s and approaches to targeting breast cancer with gene vectors or nanoparticles downregulating HSP70s, natural or synthetic (small molecule) inhibitors of HSP70s, HSP70-binding antibodies, HSP70-derived peptides, and HSP70-based vaccines.

Targeting Cancer Stem Cells by Dietary Agents: An Important Therapeutic Strategy against Human Malignancies

As a multifactorial disease, treatment of cancer depends on understanding unique mechanisms involved in its progression. The cancer stem cells (CSCs) are responsible for tumor stemness and by enhancing colony formation, proliferation as well as metastasis, and these cells can also mediate resistance to therapy. Furthermore, the presence of CSCs leads to cancer recurrence and therefore their complete eradication can have immense therapeutic benefits. The present review focuses on targeting CSCs by natural products in cancer therapy. The growth and colony formation capacities of CSCs have been reported can be attenuated by the dietary agents. These compounds can induce apoptosis in CSCs and reduce tumor migration and invasion via EMT inhibition. A variety of molecular pathways including STAT3, Wnt/β-catenin, Sonic Hedgehog, Gli1 and NF-κB undergo down-regulation by dietary agents in suppressing CSC features. Upon exposure to natural agents, a significant decrease occurs in levels of CSC markers including CD44, CD133, ALDH1, Oct4 and Nanog to impair cancer stemness. Furthermore, CSC suppression by dietary agents can enhance sensitivity of tumors to chemotherapy and radiotherapy. In addition to in vitro studies, as well as experiments on the different preclinical models have shown capacity of natural products in suppressing cancer stemness. Furthermore, use of nanostructures for improving therapeutic impact of dietary agents is recommended to rapidly translate preclinical findings for clinical use.

Targeting GRP78 enhances the sensitivity of HOS osteosarcoma cells to pyropheophorbide-α methyl ester-mediated photodynamic therapy via the Wnt/β-catenin signaling pathway

Photodynamic therapy (PDT), which is a new method for treating tumors, has been used in the treatment of cancer. In-depth research has shown that PDT cannot completely kill tumor cells, indicating that tumor cells are resistant to PDT. Glucose regulatory protein 78 (GRP78), which is a key regulator of endoplasmic reticulum stress, has been confirmed to be related to tumor resistance and recurrence, but there are relatively few studies on the further mechanism of GRP78 in PDT. Our experiment aimed to observe the role of GRP78 in HOS human osteosarcoma cells treated with pyropheophorbide-α methyl ester-mediated photodynamic therapy (MPPα-PDT) and to explore the possible mechanism by which the silencing of GRP78 expression enhances the sensitivity of HOS osteosarcoma cells to MPPα-PDT. HOS osteosarcoma cells were transfected with siRNA-GRP78. Apoptosis and reactive oxygen species (ROS) levels were detected by Hoechst staining and flow cytometry, cell viability was detected by Cell Counting Kit-8 assay, GRP78 protein fluorescence intensity was detected by immunofluorescence, and apoptosis-related proteins, cell proliferation-related proteins, and Wnt pathway-related proteins were detected by western blot. The results showed that MPPα-PDT can induce HOS cell apoptosis and increase GRP78 expression. After successful siRNA-GRP78 transfection, HOS cell proliferation was decreased, and apoptosis-related proteins expressions was increased, Wnt/β-catenin-related proteins expressions was decreased, and ROS levels was increased. In summary, siRNA-GRP78 enhances the sensitivity of HOS cells to MPPα-PDT, the mechanism may be related to inhibiting Wnt pathway activation and increasing ROS levels.

Castration-Induced Downregulation of SPARC in Stromal Cells Drives Neuroendocrine Differentiation of Prostate Cancer

Fatal neuroendocrine differentiation (NED) of castration-resistant prostate cancer is a recurrent mechanism of resistance to androgen deprivation therapies (ADT) and antiandrogen receptor pathway inhibitors (ARPI) in patients. The design of effective therapies for neuroendocrine prostate cancer (NEPC) is complicated by limited knowledge of the molecular mechanisms governing NED. The paucity of acquired genomic alterations and the deregulation of epigenetic and transcription factors suggest a potential contribution from the microenvironment. In this context, whether ADT/ARPI induces stromal cells to release NED-promoting molecules and the underlying molecular networks are unestablished. Here, we utilized transgenic and transplantable mouse models and coculture experiments to unveil a novel tumor-stroma cross-talk that is able to induce NED under the pressure of androgen deprivation. Castration induced upregulation of GRP78 in tumor cells, which triggers miR29-b-mediated downregulation of the matricellular protein SPARC in the nearby stroma. SPARC downregulation enabled stromal cells to release IL6, a known inducer of NED. A drug that targets GRP78 blocked NED in castrated mice. A public, human NEPC gene expression dataset showed that Hspa5 (encoding for GRP78) positively correlates with hallmarks of NED. Finally, prostate cancer specimens from patients developing local NED after ADT showed GRP78 upregulation in tumor cells and SPARC downregulation in the stroma. These results point to GRP78 as a potential therapeutic target and to SPARC downregulation in stromal cells as a potential early biomarker of tumors undergoing NED. SIGNIFICANCE: Tumor-stroma cross-talk promotes neuroendocrine differentiation in prostate cancer in response to hormone therapy via a GRP78/SPARC/IL6 axis, providing potential therapeutic targets and biomarkers for neuroendocrine prostate cancer.

Molecular Mechanisms Underlying the Anti-Breast Cancer Stem Cell Activity of Pterocladia capillacea and Corallina officinalis Polysaccharides

OBJECTIVE

This study aimed to appraise the activity of Pterocladia capillacea and Corallina officinalis polysaccharides against breast cancer stem cells (BCSCs). P. capillacea and C. officinalis polysaccharides were characterized to be sulfated polysaccharide-protein complexes.

METHODS

Cytotoxicity of the polysaccharides against MDA-MB-231 and MCF-7 cell lines along with their impact on CD44+/CD24- and aldehyde dehydrogenase 1(ALDH1) positive BCSC population were determined. Their effect on gene expression of CSC markers, Wnt/β-catenin and Notch signaling pathways was evaluated.

RESULTS

P. capillacea and C. officinalis polysaccharides inhibited the growth of breast cancer cells and reduced BCSC subpopulation. P. capillacea polysaccharides significantly down-regulated OCT4, SOX2, ALDH1A3 and vimentin in MDA-MB-231 as well as in MCF-7 cells except for vimentin that was up-regulated in MCF-7 cells. C. officinalis polysaccharides exhibited similar effects except for OCT4 that was up-regulated in MDA-MB-231 cells. Significant suppression of Cyclin D1 gene expression was noted in MDA-MB-231 and MCF-7 cells treated with P. capillacea or C. officinalis polysaccharides. β-catenin and c-Myc genes were significantly down-regulated in MDA-MB-231 cells treated with C. officinalis and P. capillacea polysaccharides, respectively, while being up-regulated in MCF-7 cells treated with either of them. Additionally, P. capillacea and C. officinalis polysaccharides significantly down-regulated Hes1 gene in MCF-7 cells despite increasing Notch1 gene expression level. However, significant down-regulation of Notch1 gene was observed in MDA-MB-231 cells treated with P. capillacea polysaccharides.

CONCLUSION

Collectively, this study provides evidence for the effectiveness of P. capillacea and C. officinalis polysaccharides in targeting BCSCs through interfering with substantial signaling pathways contributing to their functionality.

Targeting cancer stem cells by nutraceuticals for cancer therapy

Accumulating evidence has demonstrated that cancer stem cells (CSCs) play an essential role in tumor progression and reoccurrence and drug resistance. Multiple signaling pathways have been revealed to be critically participated in CSC development and maintenance. Emerging evidence indicates that numerous chemopreventive compounds, also known as nutraceuticals, could eliminate CSCs in part via regulating several signaling pathways. Therefore, in this review, we will describe the some natural chemopreventive agents that target CSCs in a variety of human malignancies, including soy isoflavone, curcumin, resveratrol, tea polyphenols, sulforaphane, quercetin, indole-3-carbinol, 3,3'-diindolylmethane, withaferin A, apigenin, etc. Moreover, we discuss that eliminating CSCs by nutraceuticals might be a promising strategy for treating human cancer via overcoming drug resistance and reducing tumor reoccurrence.

Chalcone Derivatives: Role in Anticancer Therapy

Chalcones (1,3-diaryl-2-propen-1-ones) are precursors for flavonoids and isoflavonoids, which are common simple chemical scaffolds found in many naturally occurring compounds. Many chalcone derivatives were also prepared due to their convenient synthesis. Chalcones as weandhetic analogues have attracted much interest due to their broad biological activities with clinical potentials against various diseases, particularly for antitumor activity. The chalcone family has demonstrated potential in vitro and in vivo activity against cancers via multiple mechanisms, including cell cycle disruption, autophagy regulation, apoptosis induction, and immunomodulatory and inflammatory mediators. It represents a promising strategy to develop chalcones as novel anticancer agents. In addition, the combination of chalcones and other therapies is expected to be an effective way to improve anticancer therapeutic efficacy. However, despite the encouraging results for their response to cancers observed in clinical studies, a full description of toxicity is required for their clinical use as safe drugs for the treatment of cancer. In this review, we will summarize the recent advances of the chalcone family as potential anticancer agents and the mechanisms of action. Besides, future applications and scope of the chalcone family toward the treatment and prevention of cancer are brought out.

Autophagic Inhibition of Caveolin-1 by Compound Phyllanthus urinaria L. Activates Ubiquitination and Proteasome Degradation of β-catenin to Suppress Metastasis of Hepatitis B-Associated Hepatocellular Carcinoma

Compound Phyllanthus urinaria L. (CP) is a traditional Chinese medicine (TCM) formula for cancer treatment in the clinic, particularly during progression of hepatitis B-associated hepatocellular carcinoma (HBV-associated HCC). Nevertheless, its anti-metastatic action and mechanisms are not well elucidated. In this study, CP was found to exert remarkable inhibitory effects on the proliferation, migration and invasion of HBV-associated HCC cells. The following network and biological analyses predicted that CP mainly targeted Caveolin-1 (Cav-1) to induce anti-metastatic effects, and Wnt/β-catenin pathway was one of the core mechanisms of CP action against HBV-associated HCC. Further experimental validation implied that Cav-1 overexpression promoted metastasis of HBV-associated HCC by stabilizing β-catenin, while CP administration induced autophagic degradation of Cav-1, activated the Akt/GSK3β-mediated proteasome degradation of β-catenin via ubiquitination activation, and subsequently attenuated the metastasis-promoting effect of Cav-1. In addition, the anti-cancer and anti-metastatic action of CP was further confirmed by in vivo and ex vivo experiments. It was found that CP inhibited the tumor growth and metastasis of HBV-associated HCC in both mice liver cancer xenograft and zebrafish xenotransplantation models. Taken together, our study not only highlights the novel function of CP formula in suppressing metastasis of HBV-associated HCC, but it also addresses the critical role of Cav-1 in mediating Akt/GSK3β/β-catenin axis to control the late-phase of cancer progression.

Autophagy Blockade by Ai Du Qing Formula Promotes Chemosensitivity of Breast Cancer Stem Cells Via GRP78/β-Catenin/ABCG2 Axis

Accumulating evidence suggests that the root of drug chemoresistance in breast cancer is tightly associated with subpopulations of cancer stem cells (CSCs), whose activation is largely dependent on taxol-promoting autophagy. Our pilot study identified GRP78 as a specific marker for chemoresistance potential of breast CSCs by regulating Wnt/β-catenin signaling. Ai Du Qing (ADQ) is a traditional Chinese medicine formula that has been utilized in the treatment cancer, particularly during the consolidation phase. In the present study, we investigated the regulatory effects and molecular mechanisms of ADQ in promoting autophagy-related breast cancer chemosensitivity. ADQ with taxol decreasing the cell proliferation and colony formation of breast cancer cells, which was accompanied by suppressed breast CSC ratio, limited self-renewal capability, as well as attenuated multi-differentiation. Furthermore, autophagy in ADQ-treated breast CSCs was blocked by taxol via regulation of β-catenin/ABCG2 signaling. We also validated that autophagy suppression and chemosensitizing activity of this formula was GRP78-dependent. In addition, GRP78 overexpression promoted autophagy-inducing chemoresistance in breast cancer cells by stabilizing β-catenin, while ADQ treatment downregulated GRP78, activated the Akt/GSK3β-mediated proteasome degradation of β-catenin via ubiquitination activation, and consequently attenuated the chemoresistance-promoted effect of GRP78. In addition, both mouse breast cancer xenograft and zebrafish xenotransplantation models demonstrated that ADQ inhibited mammary tumor growth, and the breast CSC subpopulation showed obscure adverse effects. Collectively, this study not only reveals the chemosensitizating mechanism of ADQ in breast CSCs, but also highlights the importance of GRP78 in mediating autophagy-promoting drug resistance via β-catenin/ABCG2 signaling.

Novel molecular regulators of breast cancer stem cell plasticity and heterogeneity

Tumors consist of heterogeneous cell populations, and tumor heterogeneity plays key roles in regulating tumorigenesis, metastasis, recurrence and resistance to anti-tumor therapies. More and more studies suggest that cancer stem cells (CSCs) promote tumorigenesis, metastasis, recurrence and drug resistance as well as are the major source for heterogeneity of cancer cells. CD24^-CD44⁺ and ALDH⁺ are the most common markers for breast cancer stem cells (BCSCs). Previous studies showed that different BCSC markers label different BCSC populations, indicating the heterogeneity of BCSCs. Therefore, defining the regulation mechanisms of heterogeneous BCSCs is essential for precisely targeting BCSCs and treating breast cancer. In this review, we summarized the novel regulators existed in BCSCs and their niches for BCSC heterogeneity which has been discovered in recent years, and discussed their regulation mechanisms and the latest corresponding cancer treatments, which will extend our understanding on BCSC heterogeneity and plasticity, and provide better prognosis prediction and more efficient novel therapeutic strategies for breast cancer.

Dietary Phytochemicals as a Potential Source for Targeting Cancer Stem Cells

The tumor microenvironment is composed of various types of cells that lead to tumor heterogeneity. In the middle of these populations, cancer stem cells play a vital role in the initiation and progression of cancer cells and are capable of self-renewal and differentiation processes. These cancer stem cells are resistant to conventional therapy such as chemotherapy and radiotherapy. To eradicate the cancer stem cells in the tumor environment, various natural product has been found in recent years. In this review, we have selected some of the natural products based on anticancer potential including targeting cancer cells and cancer stem cells. Further, this review explains the molecular mechanism of action of these natural products in various cancer stem cells. Therefore, targeting a multi-drug resistant cancer stem cell by natural products is a novel method to reduce drug resistance and adverse effect during conventional therapy.

Perspectives on the Role of Isoliquiritigenin in Cancer

Isoliquiritigenin (2',4',4-trihydroxychalcone, ISL), one of the most important bioactive compounds with a chalcone structure, is derived from licorice root. Licorice is commonly known as Glycyrrhiza, including Glycyrrhiza uralensis, Glycyrrhiza radix, and Glycyrrhiza glabra, which are generally available in common foods and Chinese herbal medicines based on a wide variety of biological functions and pharmacological effects, and its derivative (ISL) is utilized as a food additive and adjunct disease treatment. In this review, we summarized the progress over the last 10 years in the targeted pathways and molecular mechanisms of ISL that are involved in the regulation of the onset and progression of different types of cancers.

Adaptive response of resistant cancer cells to chemotherapy

Despite advances in cancer therapeutics and the integration of personalized medicine, the development of chemoresistance in many patients remains a significant contributing factor to cancer mortality. Upon treatment with chemotherapeutics, the disruption of homeostasis in cancer cells triggers the adaptive response which has emerged as a key resistance mechanism. In this review, we summarize the mechanistic studies investigating the three major components of the adaptive response, autophagy, endoplasmic reticulum (ER) stress signaling, and senescence, in response to cancer chemotherapy. We will discuss the development of potential cancer therapeutic strategies in the context of these adaptive resistance mechanisms, with the goal of stimulating research that may facilitate the development of effective cancer therapy.

Wnt signaling in breast cancer: biological mechanisms, challenges and opportunities

Wnt signaling is a highly conserved signaling pathway that plays a critical role in controlling embryonic and organ development, as well as cancer progression. Genome-wide sequencing and gene expression profile analyses have demonstrated that Wnt signaling is involved mainly in the processes of breast cancer proliferation and metastasis. The most recent studies have indicated that Wnt signaling is also crucial in breast cancer immune microenvironment regulation, stemness maintenance, therapeutic resistance, phenotype shaping, etc. Wnt/β-Catenin, Wnt-planar cell polarity (PCP), and Wnt-Ca2+ signaling are three well-established Wnt signaling pathways that share overlapping components and play different roles in breast cancer progression. In this review, we summarize the main findings concerning the relationship between Wnt signaling and breast cancer and provide an overview of existing mechanisms, challenges, and potential opportunities for advancing the therapy and diagnosis of breast cancer.

Counteracting Chemoresistance with Metformin in Breast Cancers: Targeting Cancer Stem Cells

Despite the leaps and bounds in achieving success in the management and treatment of breast cancers through surgery, chemotherapy, and radiotherapy, breast cancer remains the most frequently occurring cancer in women and the most common cause of cancer-related deaths among women. Systemic therapeutic approaches, such as chemotherapy, although beneficial in treating and curing breast cancer subjects with localized breast tumors, tend to fail in metastatic cases of the disease due to (a) an acquired resistance to the chemotherapeutic drug and (b) the development of intrinsic resistance to therapy. The existence of cancer stem cells (CSCs) plays a crucial role in both acquired and intrinsic chemoresistance. CSCs are less abundant than terminally differentiated cancer cells and confer chemoresistance through a unique altered metabolism and capability to evade the immune response system. Furthermore, CSCs possess active DNA repair systems, transporters that support multidrug resistance (MDR), advanced detoxification processes, and the ability to self-renew and differentiate into tumor progenitor cells, thereby supporting cancer invasion, metastasis, and recurrence/relapse. Hence, current research is focusing on targeting CSCs to overcome resistance and improve the efficacy of the treatment and management of breast cancer. Studies revealed that metformin (1, 1-dimethylbiguanide), a widely used anti-hyperglycemic agent, sensitizes tumor response to various chemotherapeutic drugs. Metformin selectively targets CSCs and improves the hypoxic microenvironment, suppresses the tumor metastasis and inflammation, as well as regulates the metabolic programming, induces apoptosis, and reverses epithelial-mesenchymal transition and MDR. Here, we discuss cancer (breast cancer) and chemoresistance, the molecular mechanisms of chemoresistance in breast cancers, and metformin as a chemo-sensitizing/re-sensitizing agent, with a particular focus on breast CSCs as a critical contributing factor to acquired and intrinsic chemoresistance. The review outlines the prospects and directions for a better understanding and re-purposing of metformin as an anti-cancer/chemo-sensitizing drug in the treatment of breast cancer. It intends to provide a rationale for the use of metformin as a combinatory therapy in a clinical setting.

Natural Compounds Targeting Cancer Stem Cells: A Promising Resource for Chemotherapy

BACKGROUND

Cancer Stem Cells (CSCs) are the subpopulation of cancer cells which are directly involved in drug resistance, metastases to distant organ and cancer recurrence.

METHODS

A systematic literature search was conducted through various electronic databases including, Pubmed, Scopus, Google scholar using the keywords "cancer stem cells" and "natural compounds" in the present study. Articles published between 1999 and 2019 were reviewed. All the expositions concerning CSCs associated cancer pathogenesis and therapy resistance, as well as targeting these properties of CSCs by natural compounds were selected for the current study.

RESULTS

Natural compounds have always been thought as a rich source of biologically active principles, which target aberrantly activated signaling pathways and other modalities of CSCs, while tethering painful side effects commonly involved in the first-line and second-line chemo-radiotherapies. In this review, we have described the key signaling pathways activated in CSCs to maintain their survival and highlighted how natural compounds interrupt these signaling pathways to minimize therapy resistance, pathogenesis and cancer recurrence properties of CSCs, thereby providing useful strategies to treat cancer or aid in cancer therapy improvement. Like normal stem cells, CSCs rely on different signaling pathways and other properties for their maintenance. Therefore, the success of cancer treatment depends on the development of proper anti-neoplastic drugs capable of intercepting those signaling pathways as well as other properties of CSCs in order to eradicate this evasive subpopulation of cancer cells.

CONCLUSION

Compounds of natural origin might act as an outstanding source to design novel therapies against cancer stem cells.

Preliminary Virtual Screening Studies to Identify GRP78 Inhibitors Which May Interfere with SARS-CoV-2 Infection

SARS-CoV-2 Spike protein was predicted by molecular docking to bind the host cell surface GRP78, which was suggested as a putative good molecular target to inhibit Covid-19. We aimed to confirm that GRP78 gene expression was increased in blood of SARS-CoV-2 (+) versus SARS-CoV-2 (-) pneumonia patients. In addition, we aimed to identify drugs that could be repurposed to inhibit GRP78, thus with potential anti-SARS-CoV-2 activity. Gene expression studies were performed in 10 SARS-CoV-2 (-) and 24 SARS-CoV-2 (+) pneumonia patients. A structure-based virtual screen was performed with 10,761 small molecules retrieved from DrugBank, using the GRP78 nucleotide binding domain and substrate binding domain as molecular targets. Results indicated that GRP78 mRNA levels were approximately four times higher in the blood of SARS-CoV-2 (+) versus SARS-CoV-2 (-) pneumonia patients, further suggesting that GRP78 might be a good molecular target to treat Covid-19. In addition, a total of 409 compounds were identified with potential as GRP78 inhibitors. In conclusion, we found preliminary evidence that further proposes GRP78 as a possible molecular target to treat Covid-19 and that many clinically approved drugs bind GRP78 as an off-target effect. We suggest that further work should be urgently carried out to confirm if GRP78 is indeed a good molecular target and if some of those drugs have potential to be repurposed for SARS-CoV-2 antiviral activity.

Molecular Chaperones in Cancer Stem Cells: Determinants of Stemness and Potential Targets for Antitumor Therapy

Cancer stem cells (CSCs) are a great challenge in the fight against cancer because these self-renewing tumorigenic cell fractions are thought to be responsible for metastasis dissemination and cases of tumor recurrence. In comparison with non-stem cancer cells, CSCs are known to be more resistant to chemotherapy, radiotherapy, and immunotherapy. Elucidation of mechanisms and factors that promote the emergence and existence of CSCs and their high resistance to cytotoxic treatments would help to develop effective CSC-targeting therapeutics. The present review is dedicated to the implication of molecular chaperones (protein regulators of polypeptide chain folding) in both the formation/maintenance of the CSC phenotype and cytoprotective machinery allowing CSCs to survive after drug or radiation exposure and evade immune attack. The major cellular chaperones, namely heat shock proteins (HSP90, HSP70, HSP40, HSP27), glucose-regulated proteins (GRP94, GRP78, GRP75), tumor necrosis factor receptor-associated protein 1 (TRAP1), peptidyl-prolyl isomerases, protein disulfide isomerases, calreticulin, and also a transcription heat shock factor 1 (HSF1) initiating HSP gene expression are here considered as determinants of the cancer cell stemness and potential targets for a therapeutic attack on CSCs. Various approaches and agents are discussed that may be used for inhibiting the chaperone-dependent development/manifestations of cancer cell stemness.

Dietary Compound Isoliquiritigenin, an Antioxidant from Licorice, Suppresses Triple-Negative Breast Tumor Growth via Apoptotic Death Program Activation in Cell and Xenograft Animal Models

Patients with triple-negative breast cancer have few therapeutic strategy options. In this study, we investigated the effect of isoliquiritigenin (ISL) on the proliferation of triple-negative breast cancer cells. We found that treatment with ISL inhibited triple-negative breast cancer cell line (MDA-MB-231) cell growth and increased cytotoxicity. ISL reduced cell cycle progression through the reduction of cyclin D1 protein expression and increased the sub-G1 phase population. The ISL-induced apoptotic cell population was observed by flow cytometry analysis. The expression of Bcl-2 protein was reduced by ISL treatment, whereas the Bax protein level increased; subsequently, the downstream signaling molecules caspase-3 and poly ADP-ribose polymerase (PARP) were activated. Moreover, ISL reduced the expression of total and phosphorylated mammalian target of rapamycin (mTOR), ULK1, and cathepsin B, whereas the expression of autophagic-associated proteins p62, Beclin1, and LC3 was increased. The decreased cathepsin B cause the p62 accumulation to induce caspase-8 mediated apoptosis. In vivo studies further showed that preventive treatment with ISL could inhibit breast cancer growth and induce apoptotic and autophagic-mediated apoptosis cell death. Taken together, ISL exerts an effect on the inhibition of triple-negative MDA-MB-231 breast cancer cell growth through autophagy-mediated apoptosis. Therefore, future studies of ISL as a supplement or alternative therapeutic agent for clinical trials against breast cancer are warranted.

Bioinformatics Studies Provide Insight into Possible Target and Mechanisms of Action of Nobiletin against Cancer Stem Cells

OBJECTIVE

Nobiletin treatment on MDA-MB 231 cells reduces the expression of CXC chemokine receptor type 4 (CXCR4), which is highly expressed in cancer stem cell populations in tumor patients. However, the mechanisms of nobiletin in cancer stem cells (CSCs) remain elusive. This study was aimed to explore the potential target and mechanisms of nobiletin in cancer stem cells using bioinformatics approaches.

METHODS

Gene expression profiles by public COMPARE predicting the sensitivity of tumor cells to nobiletin. Functional annotations on gene lists are carried out with The Database for Annotation, Visualization and Integrated Discovery (DAVID) v6.8, and WEB-based GEne SeT Analysis Toolkit (WebGestalt). The protein-protein interaction (PPI) network was analyzed by STRING-DB and visualized by Cytoscape.

RESULTS

Microarray analyses reveal many genes involved in protein binding, transcriptional and translational activity. Pathway enrichment analysis revealed breast cancer regulation of estrogen signaling and Wnt/ß-catenin by nobiletin. Moreover, three hub genes, i.e. ESR1, NCOA3, and RPS6KB1 and one significant module were filtered out and selected from the PPI network.

CONCLUSION

Nobiletin might serve as a lead compound for the development of CSCs-targeted drugs by targeting estrogen and Wnt/ß-catenin signaling. Further studies are needed to explore the full therapeutic potential of nobiletin in cancer stem cells.
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Insights into new mechanisms and models of cancer stem cell multidrug resistance

The acquisition of genetic alterations, clonal evolution, and the tumor microenvironment promote cancer progression, metastasis and therapy resistance. These events correspond to the establishment of the great phenotypic heterogeneity and plasticity of cancer cells that contribute to tumor progression and resistant disease. Targeting resistant cancers is a major challenge in oncology; however, the underlying processes are not yet fully understood. Even though current treatments can reduce tumor size and increase life expectancy, relapse and multidrug resistance (MDR) ultimately remain the second cause of death in developed countries. Recent evidence points toward stem-like phenotypes in cancer cells, promoted by cancer stem cells (CSCs), as the main culprit of cancer relapse, resistance (radiotherapy, hormone therapy, and/or chemotherapy) and metastasis. Many mechanisms have been proposed for CSC resistance, such as drug efflux through ABC transporters, overactivation of the DNA damage response (DDR), apoptosis evasion, prosurvival pathways activation, cell cycle promotion and/or cell metabolic alterations. Nonetheless, targeted therapy toward these specific CSC mechanisms is only partially effective to prevent or abolish resistance, suggesting underlying additional causes for CSC resilience. This article aims to provide an integrated picture of the MDR mechanisms that operate in CSCs' behavior and to propose a novel model of tumor evolution during chemotherapy. Targeting the pathways mentioned here might hold promise and reveal new strategies for future clinical therapeutic approaches.

Heat Shock Proteins: Agents of Cancer Development and Therapeutic Targets in Anti-Cancer Therapy

Heat shock proteins (HSPs) constitute a large family of molecular chaperones classified by their molecular weights, and they include HSP27, HSP40, HSP60, HSP70, and HSP90. HSPs function in diverse physiological and protective processes to assist in maintaining cellular homeostasis. In particular, HSPs participate in protein folding and maturation processes under diverse stressors such as heat shock, hypoxia, and degradation. Notably, HSPs also play essential roles across cancers as they are implicated in a variety of cancer-related activities such as cell proliferation, metastasis, and anti-cancer drug resistance. In this review, we comprehensively discuss the functions of HSPs in association with cancer initiation, progression, and metastasis and anti-cancer therapy resistance. Moreover, the potential utilization of HSPs to enhance the effects of chemo-, radio-, and immunotherapy is explored. Taken together, HSPs have multiple clinical usages as biomarkers for cancer diagnosis and prognosis as well as the potential therapeutic targets for anti-cancer treatment.

Betulinic Acid Suppresses Breast Cancer Metastasis by Targeting GRP78-Mediated Glycolysis and ER Stress Apoptotic Pathway

Targeting aberrant metabolism is a promising strategy for inhibiting cancer growth and metastasis. Research is now geared towards investigating the inhibition of glycolysis for anticancer drug development. Betulinic acid (BA) has demonstrated potent anticancer activities in multiple malignancies. However, its regulatory effects on glycolysis and the underlying molecular mechanisms are still unclear. BA inhibited invasion and migration of highly aggressive breast cancer cells. Moreover, BA could suppress aerobic glycolysis of breast cancer cells presenting as a reduction of lactate production, quiescent energy phenotype transition, and downregulation of aerobic glycolysis-related proteins. In this study, glucose-regulated protein 78 (GRP78) was also identified as the molecular target of BA in inhibiting aerobic glycolysis. BA treatment led to GRP78 overexpression, and GRP78 knockdown abrogated the inhibitory effect of BA on glycolysis. Further studies demonstrated that overexpressed GRP78 activated the endoplasmic reticulum (ER) stress sensor PERK. Subsequent phosphorylation of eIF2α led to the inhibition of β-catenin expression, which resulted in the inhibition of c-Myc-mediated glycolysis. Coimmunoprecipitation assay revealed that BA interrupted the binding between GRP78 and PERK, thereby initiating the glycolysis inhibition cascade. Finally, the lung colonization model validated that BA inhibited breast cancer metastasis in vivo, as well as suppressed the expression of aerobic glycolysis-related proteins. In conclusion, our study not only provided a promising drug for aerobic glycolysis inhibition but also revealed that GRP78 is a novel molecular link between glycolytic metabolism and ER stress during tumor metastasis.

The interaction between SPARC and GRP78 interferes with ER stress signaling and potentiates apoptosis via PERK/eIF2α and IRE1α/XBP-1 in colorectal cancer

Therapy-refractory disease is one of the main contributors of treatment failure in cancer. In colorectal cancer (CRC), SPARC can function as a sensitizer to conventional chemotherapy by enhancing apoptosis by interfering with the activity of Bcl-2. Here, we examine a novel mechanism by which SPARC further potentiates apoptosis via its modulation of the unfolded protein response (UPR). Using mass spectrometry to identify SPARC-associated proteins, GRP78 was identified as a protein partner for SPARC in CRC. In vitro studies conducted to assess the signaling events resulting from this interaction, included induction of ER stress with tunicamycin, 5-fluorouracil (5-FU), and irinotecan (CPT-11). We found that the interaction between GRP78 and SPARC increased during exposure to 5-FU, CPT-11, and tunicamycin, resulting in an attenuation of GRP78’s inhibition of apoptosis. In addition, we also show that SPARC can sensitize CRC cells to PERK/eIF2α and IRE1α/XBP-1 UPR signaling by interfering with ER stress following binding to GRP78, which leads to ER stress-associated cell death in CRC cells. In line with these findings, a lower expression of GRP78 relative to SPARC in CRC is associated with a lower IC₅₀ for 5-FU in either sensitive or therapy-refractory CRC cells. Interestingly, this observation correlates with tissue microarray analysis of 143 human CRC, where low GRP78 to SPARC expression level was prognostic of higher survival rate (P = 0.01) in individuals with CRC. This study demonstrates that modulation of UPR signaling by SPARC promotes ER stress-associated death and potentiates apoptosis. This may be an effective strategy that can be combined with current treatment options to improve therapeutic efficacy in CRC.

Pharmacological effectors of GRP78 chaperone in cancers

The protein chaperone GRP78 is a master regulator of endoplasmic reticulum (ER) functions and is frequently over-expressed at the surface of cancer cells where it contributes to chemo-resistance. It represents a well-studied ER stress marker but an under-explored target for new drug development. This review aims to untangle the structural and functional diversity of GRP78 modulators, covering over 130 natural products, synthetic molecules, specific peptides and monoclonal antibodies that target GRP78. Several approaches to promote or to incapacitate GRP78 are presented, including the use of oligonucleotides and specific cell-delivery peptides often conjugated to cytotoxic payloads to design GRP78-targeted therapeutics. A repertoire of drugs that turn on/off GRP78 is exposed, including molecules which bind directly to GRP78, principally to its ATP site. There exist many options to regulate positively or negatively the expression of the chaperone, or to interfere with its cellular trafficking. This review provides a molecular cartography of GRP78 pharmacological effectors and adds weight to the notion that GRP78 repressors could represent promising anticancer therapeutics, notably as regards limiting chemo-resistance of cancer cells. The potential of GRP78-targeting drugs in other therapeutic modalities is also evoked.

Prevention of breast cancer by dietary polyphenols-role of cancer stem cells

Breast cancer is a common malignancy with poor prognosis. Cancer cells are heterogeneous and cancer stem cells (CSCs) are primarily responsible for tumor relapse, treatment-resistance and metastasis, so for breast cancer stem cells (BCSCs). Diets are known to be associated with carcinogenesis. Food-derived polyphenols are able to attenuate the formation and virulence of BCSCs, implying that these compounds and their analogs might be promising agents for preventing breast cancer. In the present review, we summarized the origin and surface markers of BCSCs and possible mechanisms responsible for the inhibitory effects of polyphenols on BCSCs. The suppressive effects of common dietary polyphenols against BCSCs, such as curcumin, epigallocatechin gallate (EGCG) and related polyphenolic compounds were further discussed.

Network Pharmacology-Based Validation of Caveolin-1 as a Key Mediator of Ai Du Qing Inhibition of Drug Resistance in Breast Cancer

Chinese formulas have been paid increasing attention in cancer multidisciplinary therapy due to their multi-targets and multi-substances property. Here, we aim to investigate the anti-breast cancer and chemosensitizing function of Ai Du Qing (ADQ) formula made up of Hedyotis diffusa, Curcuma zedoaria (Christm.) Rosc., Astragalus membranaceus (Fisch.) Bunge, and Glycyrrhiza uralensis Fisch. Our findings revealed that ADQ significantly inhibited cell proliferation in both parental and chemo-resistant breast cancer cells, but with little cytotoxcity effects on the normal cells. Besides, ADQ was found to facilitate the G2/M arresting and apoptosis induction effects of paclitaxel. Network pharmacology and bioinformatics analysis further demonstrated that ADQ yielded 132 candidate compounds and 297 potential targets, and shared 22 putative targets associating with breast cancer chemoresponse. Enrichment analysis and experimental validation demonstrated that ADQ might improve breast cancer chemosensitivity via inhibiting caveolin-1, which further triggered expression changes of cell cycle-related proteins p21/cyclinB1 and apoptosis-associated proteins PARP1, BAX and Bcl-2. Besides, ADQ enhanced in vivo paclitaxel chemosensitivity on breast cancer. Our study not only uncovers the novel function and mechanisms of ADQ in chemosensitizing breast cancer at least partly via targeting caveolin-1, but also sheds novel light in utilizing network pharmacology in Chinese Medicine research.