Chemical approaches to targeting drug resistance in cancer stem cells

Deeply Implantable, Shape-Morphing, 3D MicroLEDs for Pancreatic Cancer Therapy

Controlled photooxidation-mediated disruption of collagens in the tumor microenvironment can reduce desmoplasia and enhance immune responsiveness. However, achieving effective light delivery to solid tumors, particularly those with dynamic volumetric changes like pancreatic ductal adenocarcinoma (PDAC), remains challenging and limits the repeated and sustained photoactivation of drugs. Here, 3D, shape-morphing, implantable photonic devices (IPDs) are introduced that enable tumor-specific and continuous light irradiation for effective metronomic photodynamic therapy (mPDT). This IPD adheres seamlessly to the surface of orthotopic PDAC tumors, mitigating issues related to mechanical mismatch, delamination, and internal lesions. In freely moving mouse models, mPDT using the IPD with close adhesion significantly reduces desmoplastic tumor volume without causing cytotoxic effects in healthy tissues. These promising in vivo results underscore the potential of an adaptable and unidirectional IPD design in precisely targeting cancerous organs, suggesting a meaningful advance in light-based therapeutic technologies.

Therapeutic Applications of Rosmarinic Acid in Cancer-Chemotherapy-Associated Resistance and Toxicity

Chemotherapeutic drugs and radiotherapy are fundamental treatments to combat cancer, but, often, the doses in these treatments are restricted by their non-selective toxicities, which affect healthy tissues surrounding tumors. On the other hand, drug resistance is recognized as the main cause of chemotherapeutic treatment failure. Rosmarinic acid (RA) is a polyphenol of the phenylpropanoid family that is widely distributed in plants and vegetables, including medicinal aromatic herbs, consumption of which has demonstrated beneficial activities as antioxidants and anti-inflammatories and reduced the risks of cancers. Recently, several studies have shown that RA is able to reverse cancer resistance to first-line chemotherapeutics, as well as play a protective role against toxicity induced by chemotherapy and radiotherapy, mainly due to its scavenger capacity. This review compiles information from 56 articles from Google Scholar, PubMed, and ClinicalTrials.gov aimed at addressing the role of RA as a complementary therapy in cancer treatment.

Notch-3 affects chemoresistance in colorectal cancer via DNA base excision repair enzymes

Colon cancer is the second leading cause of cancer death. With over 153,000 new CRC cases predicted, it is the third most commonly diagnosed cancer. Early detection can lead to curative surgical intervention, but recurrent and late metastatic disease is frequently treated with chemotherapeutic options based on induction of DNA damage. Understanding mechanism(s) that regulate DNA damage repair within colon tumor cells is essential to developing effective therapeutic strategies. The Notch signaling pathway is known to participate in normal colon development and we have recently described a pathway by which Notch-1, Notch-3 and Smad may regulated EMT and stem-like properties in colon tumor cells, promoting tumorigenesis. Little is known about how Notch may regulate drug resistance. In this study, we used shRNA to generate colon tumor cells with loss of Notch-3 expression. These cells exhibited reduced expression of the base-excision repair proteins PARP1 and APE1, along with increased sensitivity to ara-c and cisplatin. These data point to a pathway in which Notch-3 signaling can regulate DNA repair within colon tumor cells and suggests that targeting Notch-3 may be an effective approach to rendering colon tumors sensitive to chemotherapeutic drugs.

Therapeutic vulnerabilities of cancer stem cells and effects of natural products

Covering: 1995 to 2022Tumors possess both genetic and phenotypic heterogeneity leading to the survival of subpopulations post-treatment. The term cancer stem cells (CSCs) describes a subpopulation that is resistant to many types of chemotherapy and which also possess enhanced migratory and anchorage-independent growth capabilities. These cells are enriched in residual tumor material post-treatment and can serve as the seed for future tumor re-growth, at both primary and metastatic sites. Elimination of CSCs is a key goal in enhancing cancer treatment and may be aided by application of natural products in conjunction with conventional treatments. In this review, we highlight molecular features of CSCs and discuss synthesis, structure-activity relationships, derivatization, and effects of six natural products with anti-CSC activity.

Synergistic Encapsulation of Paclitaxel and Sorafenib by Methoxy Poly(Ethylene Glycol)-b-Poly(Caprolactone) Polymeric Micelles for Ovarian Cancer Therapy

Ovarian cancer has a high mortality rate due to difficult detection at an early stage. It is necessary to develop a novel anticancer treatment that demonstrates improved efficacy while reducing toxicity. Here, using the freeze-drying method, micelles encapsulating paclitaxel (PTX) and sorafenib (SRF) with various polymers were prepared, and the optimal polymer (mPEG-b-PCL) was selected by measuring drug loading (%), encapsulation efficiency (%), particle size, polydispersity index, and zeta potential. The final formulation was selected based on a molar ratio (PTX:SRF = 1:2.3) with synergistic effects on two ovarian cancer cell lines (SKOV3-red-fluc, HeyA8). In the in vitro release assay, PTX/SRF micelles showed a slower release than PTX and SRF single micelles. In pharmacokinetic evaluation, PTX/SRF micelles showed improved bioavailability compared to PTX/SRF solution. In in vivo toxicity assays, no significant differences were observed in body weight between the micellar formulation and the control group. The anticancer effect of PTX/SRF combination therapy was improved compared to the use of a single drug. In the xenografted BALB/c mouse model, the tumor growth inhibition rate of PTX/SRF micelles was 90.44%. Accordingly, PTX/SRF micelles showed improved anticancer effects compared to single-drug therapy in ovarian cancer (SKOV3-red-fluc).

Milk-Derived Antimicrobial Peptides: Overview, Applications, and Future Perspectives

The growing consumer awareness towards healthy and safe food has reformed food processing strategies. Nowadays, food processors are aiming at natural, effective, safe, and low-cost substitutes for enhancing the shelf life of food products. Milk, besides being a rich source of nutrition for infants and adults, serves as a readily available source of precious functional peptides. Due to the existence of high genetic variability in milk proteins, there is a great possibility to get bioactive peptides with varied properties. Among other bioactive agents, milk-originated antimicrobial peptides (AMPs) are gaining interest as attractive and safe additive conferring extended shelf life to minimally processed foods. These peptides display broad-spectrum antagonistic activity against bacteria, fungi, viruses, and protozoans. Microbial proteolytic activity, extracellular peptidases, food-grade enzymes, and recombinant DNA technology application are among few strategies to tailor specific peptides from milk and enhance their production. These bioprotective agents have a promising future in addressing the global concern of food safety along with the possibility to be incorporated into the food matrix without compromising overall consumer acceptance. Additionally, in conformity to the current consumer demands, these AMPs also possess functional properties needed for value addition. This review attempts to present the basic properties, synthesis approaches, action mechanism, current status, and prospects of antimicrobial peptide application in food, dairy, and pharma industry along with their role in ensuring the safety and health of consumers.

Targeting cancer stem cells and signalling pathways through phytochemicals: A promising approach against colorectal cancer

BACKGROUND

Cancer stem cells (CSCs) are strongly associated with high tumourigenicity, chemotherapy or radiotherapy resistance, and metastasis and recurrence, particularly in colorectal cancer (CRC). Therefore, targeting CSCs may be a promising approach. Recently, discovery and research on phytochemicals that effectively target colorectal CSCs have been gaining popularity because of their broad safety profile and multi-target and multi-pathway modes of action.

PURPOSE

This review aimed to elucidate and summarise the effects and mechanisms of phytochemicals with potential anti-CSC agents that could contribute to the better management of CRC.

METHODS

We reviewed PubMed, EMBASE, Web of Science, Ovid, ScienceDirect and China National Knowledge Infrastructure databases from the original publication date to March 2022 to review the mechanisms by which phytochemicals inhibit CRC progression by targeting CSCs and their key signalling pathways. Phytochemicals were classified and summarised based on the mechanisms of action.

RESULTS

We observed that phytochemicals could affect the biological properties of colorectal CSCs. Phytochemicals significantly inhibit self-renewal, migration, invasion, colony formation, and chemoresistance and induce apoptosis and differentiation of CSCs by regulating the Wnt/β-catenin pathway (e.g., diallyl trisulfide and genistein), the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathway (e.g., caffeic acid and piperlongumine), the neurogenic locus notch homolog protein pathway (e.g., honokiol, quercetin, and α-mangostin), the Janus kinase-signal transducer and activator of transcription pathway (e.g., curcumin, morin, and ursolic acid), and other key signalling pathways. It is worth noting that several phytochemicals, such as resveratrol, silibinin, evodiamine, and thymoquinone, highlight multi-target and multi-pathway effects in restraining the malignant biological behaviour of CSCs.

CONCLUSIONS

This review demonstrates the potential of targeted therapies for colorectal CSCs using phytochemicals. Phytochemicals could serve as novel therapeutic agents for CRC and aid in drug development.

Formulation of Boron Encapsulated Smart Nanocapsules for Targeted Drug Delivery to the Brain

Drug delivery through the Blood–Brain Barrier (BBB) represents a significant challenge. Despite the current strategies to circumvent the BBB, nanotechnology offers unprecedented opportunities for combining selective delivery, improved bioavailability, drug protection, and enhanced pharmacokinetics profiles. Chitosan nanocarriers allow for a more efficacious strategy at the cellular and sub-cellular levels. Boron Neutron Capture Therapy (BNCT) is a targeted chemo-radiotherapeutic technique that allows the selective depletion of cancer cells by means of selective tagging of cancer cells with 10B, followed by irradiation with low-energy neutrons. Consequently, the combination of a polymer-based nanodelivery system enclosing an effective BNCT pharmacophore can potentially lead to the selective delivery of the load to cancer cells beyond the BBB. In this work, synthesized novel boronated agents based on carborane-functionalized Delocalized Lipophilic Cations (DLCs) are assessed for safety and selective targeting of tumour cells. The compounds are then encapsulated in nanocarriers constituted by chitosan to promote permeability through the BBB. Additionally, chitosan was used in combination with polypyrrole to form a smart composite nanocapsule, which is expected to release its drug load with variations in pH. Results indicate the achievement of more selective boron delivery to cells via carboranyl DLCs. Finally, preliminary cell studies indicate no toxicity was detected in chitosan nanocapsules, further enhancing its viability as a potential delivery vehicle in the BNCT of brain tumours.

The IVF-generated human embryonic microenvironment reverses progestin resistance in endometrial cancer cells by inducing cancer stem cell differentiation

Progestin resistance is a critical factor that prevents patients with endometrial cancer (EC) from receiving conservative therapy. However, the etiology remains elusive. Cancer stem cells (CSCs) may be a contributing factor to progestin resistance in EC. These cells share similar stemness properties with embryonic stem cells that have a multipotent but differential naïve phenotype. Embryonic stem cells are programed to self-renew, to differentiate and to show plasticity toward a normal cellular phenotype in their defined microenvironment. However, whether this microenvironment may promote CSC differentiation toward a better responsive phenotype and reverse progestin resistance has not yet been clarified. In the current study, we found that progestin resistance of endometrial CSCs can be improved or reversed by using in vitro fertilization (IVF)-generated embryonic sac-derived fluid containing the embryonic microenvironment. Furthermore, suppression or reversal of progestin resistance was mediated by placental alkaline phosphatase (ALPP), a factor secreted into the embryonic microenvironment by IVF-generated blastocysts. ALPP significantly reversed progestin resistance by facilitating endometrial CSC differentiation through downregulating the stemness genes NANOG, OCT4 and SOX2. We further showed that the downregulation of NANOG, OCT4 and SOX2 by ALPP was carried out by TET1/2-mediated epigenetic modulation of the promoter regions of these genes. Such changes at the molecular level initiated endometrial CSC differentiation and promoted a better responsive endometrial cancer phenotype. In fact, their response to progestin treatment was similar to that of well-differentiated endometrioid carcinoma cells without CSCs. ALPP could be a novel target in the process to overcome progestin resistance, and such findings may provide a new approach for the conservative treatment of endometrial cancer.

Research Progress in the Synthesis of Targeting Organelle Carbon Dots and Their Applications in Cancer Diagnosis and Treatment

With increasing knowledge about diseases at the histological, cytological to sub-organelle level, targeting organelle therapy has gradually been envisioned as an approach to overcome the shortcomings of poor specificity and multiple toxic side effects on tissues and cell-level treatments using the currently available therapy. Organelle carbon dots (CDs) are a class of functionalized CDs that can target organelles. CDs can be prepared by a "synchronous in situ synthesis method" and "asynchronous modification method." The superior optical properties and good biocompatibility of CDs can be preserved, and they can be used as targeting particles to carry drugs into cells while reducing leakage during transport. Given the excellent organelle fluorescence imaging properties, targeting organelle CDs can be used to monitor the physiological metabolism of organelles and progression of human diseases, which will provide advanced understanding and accurate diagnosis and targeted treatment of cancers. This study reviews the methods used for preparation of targeting organelle CDs, mechanisms of accurate diagnosis and targeted treatment of cancer, as well as their application in the area of cancer diagnosis and treatment research. Finally, the current difficulties and prospects for targeting organelle CDs are prospected.

Nanotechnology-based siRNA delivery strategies for treatment of triple negative breast cancer

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterized by absence of estrogen (ER) receptor, progesterone (PR) receptor, and human epidermal growth factor-2 (HER-2) receptor. TNBC is an aggressive disease that develops early Chemoresistance. The major pitfall associated is its poor prognosis, low overall survival, high relapse, and mortality as compared to other types of breast cancer. Chemotherapy could be helpful but do not contribute to an increase in survival of patient. To overcome such obstacles, in our article we explored advanced therapy using genes and nanocarrier along with its conjugation to achieve high therapeutic profile with reduced side effect. siRNAs are one of the class of RNA associated with gene silencing. They also regulate the expression of certain proteins that are involved in development of tumor cells. But they are highly unstable. So, for efficient delivery of siRNA, very intelligent, efficient delivery systems are required. Several nanotechnologies based non-viral vectors such as liposome, micelles, nanoparticles, dendrimers, exosomes, nanorods and nanobubbles etc. offers enormous unique properties such as nanometric size range, targeting potential with the capability to link with several targeting moieties for the gene delivery. These non-viral vectors are much safer, effective and efficient system for the delivery of genes along with chemotherapeutics. This review provides an overview of TNBC, conventional and advanced treatment approach of TNBC along with understanding of current status of several nanocarriers used for the delivery of siRNA for the treatment of TNBC.

Synergistic ultrasonic biophysical effect-responsive nanoparticles for enhanced gene delivery to ovarian cancer stem cells

Ovarian cancer stem cells (OCSCs) that are a subpopulation within bulk tumor survive chemotherapy and conduce to chemo-resistance and tumor relapse. However, conventional gene delivery is unsuitable for the on-demand content release, which limits OCSCs therapeutic utility. Here, we reported ultrasound-targeted microbubble destruction (UTMD)-triggerable poly(ethylene glycol)-disulfide bond-polyethylenimine loaded microbubble (PSP@MB). Taking advantage of glutathione (GSH) responsiveness, ultrasound triggering and spatiotemporally controlled release manner, PSP@MB is expected to realize local gene delivery for OCSCs treatment. But the biophysical mechanisms of gene delivery via PSP@MB and ultrasound remain unknown. The aim of this study is to determine the potential of gene delivery to OCSCs via ultrasonic synergistic biophysical effects and GSH-sensitive PSP@MB. The GSH-sensitive disulfide bond cleavable properties of PSP@MB were confirmed by ¹H NMR spectra and infrared spectroscopy. The biophysical mechanisms between PSP@MB and cells were confirmed by scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) to optimize the ultrasonic gene delivery system. The gene transfection via ultrasound and PSP@MB was closely related to the biophysical mechanisms (sonoporation, enhanced-endocytosis, sonoprinting, and endosomal escape). Ultrasound combined with PSP@MB successfully delivered aldehyde dehydrogenase 1 (ALDH1) short hairpin RNA (shRNA) plasmid to OCSCs and promoted apoptosis of OCSCs. The gene transfection rate and apoptosis rate were (18.41 ± 2.41)% and (32.62 ± 2.36)% analyzed by flow cytometry separately. This study showed that ultrasound triggering and GSH responsive PSP@MB might provide a novel strategy for OCSCs treatment via sonoporation and enhanced-endocytosis.

Design and Synthesis of New Withaferin A Inspired Hedgehog Pathway Inhibitors

Withanolides constitute a well-known family of plant-based alkaloids characterised by widespread biological properties, including the ability of interfering with Hedgehog (Hh) signalling pathway. Following our interest in natural products and in anticancer compounds, we report here the synthesis of a new class of Hh signalling pathway inhibitors, inspired by withaferin A, the first isolated member of withanolides. The decoration of our scaffolds was rationally supported by in silico studies, while functional evaluation revealed promising candidates, confirming once again the importance of natural products as inspiration source for the discovery of novel bioactive compounds. A stereoselective approach, based on Brown chemistry, allowed the obtainment and the functional evaluation of the enantiopure hit compounds.

Lovastatin Inhibits EMT and Metastasis of Triple-Negative Breast Cancer Stem Cells Through Dysregulation of Cytoskeleton-Associated Proteins

Triple-negative breast cancer (TNBC) is more aggressive and has poorer prognosis compared to other subtypes of breast cancer. Epithelial-to-mesenchymal transition (EMT) is a process in which epithelial cells transform into mesenchymal-like cells capable of migration, invasion, and metastasis. Recently, we have demonstrated that lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor and a lipid-lowering drug, could inhibit stemness properties of cancer stem cells (CSCs) derived from TNBC cell in vitro and in vivo. This study is aimed at investigating whether lovastatin inhibits TNBC CSCs by inhibiting EMT and suppressing metastasis and the mechanism involved. In the present study, we found that lovastatin dysregulated lysine succinylation of cytoskeleton-associated proteins in CSCs derived from TNBC MDA-MB-231 cell. Lovastatin inhibited EMT as demonstrated by down-regulation of the protein levels of Vimentin and Twist in MDA-MB-231 CSCs in vitro and vivo and by reversal of TGF-β1-induced morphological change in MCF10A cells. Lovastatin also inhibited the migration of MDA-MB-231 CSCs. The disruption of cytoskeleton in TNBC CSCs by lovastatin was demonstrated by the reduction of the number of pseudopodia and the relocation of F-actin cytoskeleton. Combination of lovastatin with doxorubicin synergistically inhibited liver metastasis of MDA-MB-231 CSCs. Bioinformatics analysis revealed that higher expression levels of cytoskeleton-associated genes were characteristic of TNBC and predicted survival outcomes in breast cancer patients. These data suggested that lovastatin could inhibit the EMT and metastasis of TNBC CSCs in vitro and in vivo through dysregulation of cytoskeleton-associated proteins.

The potential of photodynamic therapy in current breast cancer treatment methodologies

Photodynamic Therapy (PDT) has been known for over a hundred years, and currently gaining in acceptance as an alternative cancer treatment. Light delivery is still a difficult problem in deep cancer treatment with PDT. Only near-infrared light in the 700-1100 nm range can penetrate deeply into the tissue because most tissue chromophores, including oxyhemoglobin, deoxyhemoglobin, melanin and fat, poorly absorb in the near infrared window. The light sources used in PDT are lasers, arc lamps, light-emitting diodes and fluorescent lamps. PDT has been used for many different clinical applications. PDT may be excellent alternative in the treatment and diagnosis of breast cancer compared to the conventional surgery, chemotherapy and radiotherapy. The basic elements of PDT are an appropriate photosensitizer (PS), oxygen, and light. The effectiveness of photodynamic therapy depends on the induction of photocytotoxic reactions, which are the result of light activation of PS), pre-administered to the body. The condition for initiating PDT processes is light absorption by PS and subsequent localized generation of cytotoxic reactive oxygen species. This study is a review of empirical research aimed at improving the therapy and diagnosis of breast cancer using PDT based on the physicochemical differences in healthy and diseased tissues and the tissues undergoing treatment.

Assessing the prognostic value of stemness-related genes in breast cancer patients

Breast cancer (BC) is currently one of the deadliest tumors worldwide. Cancer stem cells (CSCs) are a small group of tumor cells with self-renewal and differentiation abilities and high treatment resistance. One of the reasons for treatment failures is the inability to completely eliminate tumor stem cells. By using the edgeR package, we identified stemness-related differentially expressed genes in GSE69280. Via Lasso-penalized Cox regression analysis and univariate Cox regression analysis, survival genes were screened out to construct a prognostic model. Via nomograms and ROC curves, we verified the accuracy of the prognostic model. We selected 4 genes (PSMB9, CXCL13, NPR3, and CDKN2C) to establish a prognostic model from TCGA data and a validation model from GSE24450 data. We found that the low-risk score group had better OS than the high-risk score group, whether using TCGA or GSE24450 data. A prognostic model including four stemness-related genes was constructed in our study to determine targets of breast cancer stem cells (BCSCs) and improve the treatment effect.

Natural and herbal compounds targeting breast cancer, a review based on cancer stem cells

Cancer stem cells (CSCs) are known as the major reason for therapy resistance. Recently, natural herbal compounds are suggested to have a significant role in inhibiting the breast cancer stem cells (BCSCs). The aim of this study was to explore the effective natural herbal compounds against BCSCs.This review article was designed based on the BCSCs, mechanisms of therapy resistance and natural herbal compounds effective to inhibit their activity. Therefore, Science direct, PubMed and Scopus databases were explored and related original articles were investigated from 2010 to 2019. BCSCs use different mechanisms including special membrane transporters, anti-apoptotic, pro-survival, and self-renewal- related signaling pathways. Natural herbal compounds could disturb these mechanisms, therefore may inhibit or eradicate the BCSCs. Studies show that a broad range of plants, either as a food or medicine, contain anti-cancer agents that phenolic components and their different derivatives share a large quantity. Natural herbal compounds play a pivotal role in the eradication of BCSCs, through the inhibition of biological activities and induction of apoptosis. Although it is necessary to conduct more clinical investigation.

A review of nanotechnology-based approaches for breast cancer and triple-negative breast cancer

Breast cancer (BC) is one of the most prevalent cancers in women. Triple-negative breast cancer (TNBC) in which the three major receptors i.e. estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), are absent is known to express the most aggressive phenotype and increased metastasis which results in the development of resistance to chemotherapy. It offers various therapeutic advantages in treating BC and TNBC. Nanotechnology offers various unique characteristics such as small size (nanometric), active and passive targeting, and the ability to attach multiple targeting moieties, controlled release, and site-specific targeting. This review focuses on conventional drug therapies, recent treatment strategies, and unique therapeutic approaches available for BC and TNBC. The role of breast cancer stem cells in the recurrence of BC and TNBC has also been highlighted. Several chemotherapeutic agents delivered using nanocarriers such as polymeric nanoparticles/micelles, metallic/inorganic NPs, and lipid-based NPs (Liposome, solid-lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs)), etc. with excellent responses in the treatment of BC/TNBC along with breast cancer stem cells have been discussed in details. Moreover, the application of nanomedicine including CRISPR nanoparticle, exosomes for the treatment of BC/TNBC and other molecular targets available such as poly (ADP-ribose) polymerase (PARP), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor (VEGF), etc. for further exploration have also been discussed.

Role of cancer stem cells in the development of giant cell tumor of bone

The primary bone tumor is usually observed in adolescence age group which has been shown to be part of nearly 20% of the sarcomas known today. Giant cell tumor of bone (GCTB) can be benign as well as malignant tumor which exhibits localized dynamism and is usually associated with the end point of a long bone. Giant cell tumor (GCT) involves mononuclear stromal cells which proliferate at a high rate, multinucleated giant cells and stromal cells are equally present in this type of tumor. Cancer stem cells (CSCs) have been confirmed to play a potential role in the development of GCT. Cancer stem cell-based microRNAs have been shown to contribute to a greater extent in giant cell tumor of bone. CSCs and microRNAs present in the tumors specifically are a great concern today which need in-depth knowledge as well as advanced techniques to treat the bone cancer effectively. In this review, we attempted to summarize the role played by cancer stem cells involving certain important molecules/factors such as; Mesenchymal Stem Cells (MSCs), miRNAs and signaling mechanism such as; mTOR/PI3K-AKT, towards the formation of giant cell tumor of bone, in order to get an insight regarding various effective strategies and research advancements to obtain adequate knowledge related to CSCs which may help to focus on highly effective treatment procedures for bone tumors.

Red-Emissive Carbon Quantum Dots for Nuclear Drug Delivery in Cancer Stem Cells

Large doses of anticancer drugs entering cancer cell nuclei are found to be effective at killing cancer cells and increasing chemotherapeutic effectiveness. Here we report red-emissive carbon quantum dots, which can enter into the nuclei of not only cancer cells but also cancer stem cells. After doxorubicin was loaded at the concentration of 30 μg/mL on the surfaces of carbon quantum dots, the average cell viability of HeLa cells was decreased to only 21%, while it was decreased to 50% for free doxorubicin. The doxorubicin-loaded carbon quantum dots also exhibited a good therapeutic effect by eliminating cancer stem cells. This work provides a potential strategy for developing carbon quantum-dot-based anticancer drug carriers for effective eradication of cancers.

Cordyceps militarisExerts Antitumor Effect on Carboplatin-Resistant Ovarian Cancer via Activation of ATF3/TP53 Signaling In Vitro and In Vivo

This study aimed to investigate the effect of Cordyceps militaris extract on the proliferation and apoptosis of carboplatin- resistant SKOV-3 and determine the underlying mechanisms for overcoming carboplatin resistance in human ovarian cancer. We cultured the carboplatin-resistant SKOV-3 cells in vitro until the exponential growth phase and then treated with different concentrations of C. militaris for 24, 48, and 72 hours. We performed cell proliferation assay, cell morphological change assessment using transmission electron microscopy, apoptosis assay, and immunoblotting to measure the protein expression of caspase-3 and -8, poly (ADP-ribose) polymerase (PARP)-1, B-cell lymphoma (Bcl)-2, and activating transcription factor 3 (ATF3)/TP53 signaling-related proteins. As a result, C. militaris reduced the viability of carboplatin-resistant SKOV-3 and induced morphological disruptions in a dose- and time-dependent manner. The gene expression profiles indicated a reprogramming pattern of the previously known and unknown genes and transcription factors associated with the action of TCTN3 on carboplatin-resistant SKOV-3 cells. We also confirmed the C. militaris-induced activation of the ATF3/TP53 pathway. Immunoblotting indicated that cotreatment of C. militaris and carboplatin-mediated ATF3/TP53 upregulation induced apoptosis in the carboplatin-resistant SKOV-3 cells, which are involved in the serial activation of pro-apoptotic proteins, including Bcl-2, Bax, caspases, and PARP-1. Further, when the ATF3 and TP53 expression increased, the CHOP and PUMA expressions were upregulated. Consequently, the upregulated CHOP/PUMA expression activated the positive regulation of the apoptotic signaling pathway. In addition, it decreased the Bcl-2 expression, leading to marked ovarian cancer cells sensitive to carboplatin by enhancing apoptosis. We then corroborated these results using in vivo experiments. Taken together, C. militaris inhibits carboplatin-resistant SKOV-3 cell proliferation and induces apoptosis possibly through ATF3/TP53 signaling upregulation and CHOP/PUMA activation. Therefore, our findings provide new insights into the treatment of carboplatin-resistant ovarian cancer using C. militaris.

Reversal of Multidrug Resistance in Cancer by Multi-Functional Flavonoids

Multidrug resistance (MDR) resulting from different defensive mechanisms in cancer is one of the major obstacles of clinical treatment. To circumvent MDR many reversal agents have been developed, but most of them fail in clinical trials due to severely adverse effects. Recently, certain natural products have been reported to overcome MDR, including flavonoids which are abundant in plants, foods, and herbs. The structure of flavonoids can be abbreviated as C6-C3-C6 (C for carbon), and further categorized into flavonoids, iso-flavonoids and neo-flavonoids, according to their structural backbones. Flavonoids possess multiple bioactivities, and a growing body of research has indicated that both flavonoids and iso-flavonoids can either kill or re-sensitize conventional chemotherapeutics to resistant cancer cells. Here, we summarize the research and discuss the underlying mechanisms, concluding that these flavonoids do not function as specific regulators of target proteins, but rather as multi-functional agents that negatively regulate the key factors contributing to MDR.

Dopamine receptor antagonists induce differentiation of PC-3 human prostate cancer cell-derived cancer stem cell-like cells

BACKGROUND

The objective of this study was to determine whether PC-3 human prostate cancer cell-derived cancer stem cells (CSC)-like cells grown in a regular cell culture plate not coated with a matrix molecule might be useful for finding differentiation-inducing agents that could alter properties of prostate CSC.

METHODS

Monolayer cells prepared from sphere culture of PC-3 cells were characterized for the presence of pluripotency and tumorigenicity. They were then applied to screen a compound library to find compounds that could induce morphology changes of cells. Mechanisms of action of compounds selected from the chemical library that induced the loss of pluripotency of cells were also investigated.

RESULTS

C5A cells prepared from PC-3 cell-derived sphere culture expressed pluripotency markers such as Oct4, Sox2, and Klf4. C5A cells were highly proliferative. They were invasive in vitro and tumorigenic in vivo. Some dopamine receptor antagonists such as thioridazine caused reduction of pluripotency markers and tumorigenicity. Thioridazine, unlike promazine, inhibited phosphorylation of AMPK in a dose dependent manner. BML-275, an AMPK inhibitor, also induced differentiation of C5A cells as seen with thioridazine whereas A769663, an AMPK activator, blocked its differentiation-inducing ability. Transfection of C5A cells with siRNAs of dopamine receptor subtypes revealed that knockdown of DRD2 or DRD4 induced morphology changes of C5A cells.

CONCLUSIONS

Some dopamine receptor antagonists such as thioridazine can induce differentiation of CSC-like cells by inhibiting phosphorylation of AMPK. Binding to DRD2 or DRD4 might have mediated the action of thioridazine involved in the differentiation of CSC-like cells.

Recent advances in understanding tumor stroma-mediated chemoresistance in breast cancer

Although solid tumors comprise malignant cells, they also contain many different non-malignant cell types in their micro-environment. The cellular components of the tumor stroma consist of immune and endothelial cells combined with a heterogeneous population of stromal cells which include cancer-associated fibroblasts. The bi-directional interactions between tumor and stromal cells therefore substantially affect tumor cell biology.Herein, we discuss current available information on these interactions in breast cancer chemo-resistance. It is acknowledged that stromal cells extrinsically alter tumor cell drug responses with profound consequences for therapy efficiency, and it is therefore essential to understand the molecular mechanisms which contribute to these substantial alterations because they provide potential targets for improved cancer therapy. Although breast cancer patient survival has improved over the last decades, chemo-resistance still remains a significant obstacle to successful treatment.Appreciating the important experimental evidence of mesenchymal stromal cells and cancer-associated fibroblast involvement in breast cancer clinical practice can therefore have important therapeutic implications.

A novel binuclear hydrazone-based Cd(II) complex is a strong pro-apoptotic inducer with significant activity against 2D and 3D pancreatic cancer stem cells

A novel binuclear Cd complex (1) with hydrazone-based ligand was prepared and characterized by spectroscopy and single crystal X-ray diffraction techniques. Complex 1 reveals a strong pro-apoptotic activity in both human, mammary adenocarcinoma cells (MCF-7) and pancreatic AsPC-1 cancer stem cells (CSCs). While apoptosis undergoes mostly caspase-independent, 1 stimulates the activation of intrinsic pathway with noteworthy down regulation of caspase-8 activity in respect to non-treated controls. Distribution of cells over mitotic division indicates that 1 caused DNA damage in both cell lines, which is confirmed in DNA interaction studies. Compared to 1, cisplatin (CDDP) does not achieve cell death in 2D cultured AsPC-1 cells, while induces different pattern of cell cycle changes and caspase activation in 2D cultured MCF-7 cells, implying that these two compounds do not share similar mechanism of action. Additionally, 1 acts as a powerful inducer of mitochondrial superoxide production with dissipated trans-membrane potential in the majority of the treated cells already after 6 h of incubation. On 3D tumors, 1 displays a superior activity against CSC model, and at 100 μM induces disintegration of spheroids within 2 days of incubation. Fluorescence spectroscopy, along with molecular docking show that compound 1 binds to the minor groove of DNA. Compound 1 binds to the human serum albumin (HSA) showing that the HSA can effectively transport and store 1 in the human body. Thus, our current study strongly supports further investigations on antitumor activity of 1 as a drug candidate for the treatment of highly resistant pancreatic cancer.

Targeting cancer stem cells with dietary phytochemical - Repositioned drug combinations

The tumor microenvironment is complex with the cancer stem cell (CSC) as a member within its community. This population possesses the capacity to self-renew and to cause cellular heterogeneity of the tumor. CSCs are resistant to conventional anti-proliferative drugs. In order to be curative, it is imperative that CSCs must be eliminated by cancer therapy. A variety of dietary phytochemicals and repositioned drugs can act synergistically with conventional anti-cancer agents. In this review, we advocate the development of a novel approach, namely combination therapy by incorporating both phytochemicals and repositioned drugs to target CSCs. We cover select dietary phytochemicals (curcumin, resveratrol, EGCG, genistein) and repurposed drugs (metformin, niclosamide, thioridazine, chloroquine). Five of the eight (curcumin, resveratrol, EGCG, genistein, metformin) are listed in "The Halifax Project", that explores "the concept of a low-toxicity 'broad-spectrum' therapeutic approach that could simultaneously target many key pathways and mechanisms" [1]. For these compounds, we discuss their mechanisms of action, in which models their anti-CSC activities were identified, as well as advantages, challenges and potentials of combination therapy.

pH- and GSH-Sensitive Hyaluronic Acid-MP Conjugate Micelles for Intracellular Delivery of Doxorubicin to Colon Cancer Cells and Cancer Stem Cells

A dual-sensitive polymeric drug conjugate (HA-SS-MP) was synthesized by conjugating hydrophobic 6-mercaptopurine (MP) to thiolated hyaluronic acid (HA) as the carrier and ligand to deliver doxorubicin (Dox) to parental colon cancer and colon cancer stem cells. Because of the amphiphilic nature of HA-SS-MP, it was self-assembled in the aqueous media, and Dox was physically encapsulated in the core of the micelles. The particle size and the zeta potential of the micelle were analyzed by dynamic light scattering (DLS), and the morphology of the micelle was investigated using transmission electron microscopy (TEM). Drug release study results revealed more drug release at pH 5.0 in the presence of GSH than that at the physiological pH value. The cytotoxicity of free Dox was slightly greater than that of Dox-loaded HA-SS-MP micelles. In vitro cytotoxicity of HA-SS-MP and Dox-loaded HA-SS-MP micelles was greater for cancer stem cells (HCT116-CSCs) than for parental HCT116 colon cancer cells and L929 normal fibroblast cells. The MTT and flow cytometry results confirmed that free HA competitively inhibited Dox-loaded HA-SS-MP uptake. Similarly, flow cytometry results revealed anti-CD44 antibody competitively inhibited cellular uptake of Rhodamine B isothiocyanate conjugated micelles, which confirms that the synthesized micelle is uptaken via CD44 receptor. Cell cycle analysis revealed that free drugs and Dox-loaded HA-SS-MP arrested parental HCT116 colon cancer cells at the S phase, while cell arrest was observed at the G0G1 phase in HCT116-CSCs. In addition, ex vivo biodistribution study showed that Dox-loaded HA-SS-MP micelles were accumulated more in the tumor region than in any other organ. Furthermore, the in vivo results revealed that Dox-loaded HA-SS-MP micelles exhibited more therapeutic efficacy than the free drugs in inhibiting tumor growth in BALB/C nude mice. Overall, the results suggested that the synthesized micelles could be promising as a stimuli carrier and ligand for delivering Dox to colon cancer cells and also to eradicate colon cancer stem cells.

Breast cancer stem cells: Features, key drivers and treatment options

The current view is that breast cancer is a stem cell disease characterized by the existence of cancer cells with stem-like features and tumor-initiating potential. These cells are made responsible for tumor dissemination and metastasis. Common therapies by chemotherapeutic drugs fail to eradicate these cells and rather increase the pool of cancer stem cells in tumors, an effect that may increase the likelyhood of recurrence. Fifteen years after the first evidence for a small stem-like subpopulation playing a major role in breast cancer initiation has been published a large body of knowledge has been accumulated regarding the signaling cascades and proteins involved in maintaining stemness in breast cancer. Differences in the stem cell pool size and in mechanisms regulating stemness in the different breast cancer subtypes have emerged. Overall, this knowledge offers new approaches to intervene with breast cancer stem cell activity. New options are particularly needed for the treatment of triple-negative breast cancer subtype, which is particularly rich in cancer stem cells and is also the subtype for which specific therapies are still not available.

Heteronanoparticles by Self-Assembly of Ecdysteroid and Doxorubicin Conjugates To Overcome Cancer Resistance

Heteronanoparticles (H-NPs) consisting of conjugates characterized by a squalene tail linked to doxorubicin and ecdysteroid derivatives are presented. Biological evaluation on A2780ADR cell line confirms not only the maintenance of the activity of the parental drug but also the ability to overcome cancer resistance. The in vitro cell uptake was demonstrated, and the involvement of an endosomal-mediated pathway was suggested.

Imidazole Alkaloids and Their Zinc Complexes from the Calcareous Marine Sponge Leucetta chagosensis

Five new imidazole derivatives (1-5), together with eight related known alkaloids, were isolated from a calcareous marine sponge, Leucetta chagosensis, collected from the South China Sea. Their structures were fully characterized by spectroscopic methods. Structurally, 1 possesses an unusual skeleton featuring imidazole and oxazolone rings linked via a nitrogen atom, whereas 2 bears an intriguing guanylurea-substituted imidazole ring. Compounds 4 and 5 were identified as zinc complexes; they represent the metal complex analogues of naamidine J (6) and pyronaamidine (7), respectively. Among the isolated compounds, 2 and 5 showed significant inhibitory activities toward the LPS-induced production of IL-6 in the human acute monocytic leukemia cell line THP-1, and 7 displayed cytotoxicity against MCF-7, PC9, A549, and breast cancer stem cells (MCF-7-Oct4-GFP) with IC₅₀ values of 5.2, 5.6, 7.8, and 10 μM, respectively.

Functional disruption of the Golgi apparatus protein ARF1 sensitizes MDA-MB-231 breast cancer cells to the antitumor drugs Actinomycin D and Vinblastine through ERK and AKT signaling

Increasing evidence indicates that the Golgi apparatus plays active roles in cancer, but a comprehensive understanding of its functions in the oncogenic transformation has not yet emerged. At the same time, the Golgi is becoming well recognized as a hub that integrates its functions of protein and lipid biosynthesis to signal transduction for cell proliferation and migration in cancer cells. Nevertheless, the active function of the Golgi apparatus in cancer cells has not been fully evaluated as a target for combined treatment. Here, we analyzed the effect of perturbing the Golgi apparatus on the sensitivity of the MDA-MB-231 breast cancer cell line to the drugs Actinomycin D and Vinblastine. We disrupted the function of ARF1, a protein necessary for the homeostasis of the Golgi apparatus. We found that the expression of the ARF1-Q71L mutant increased the sensitivity of MDA-MB-231 cells to both Actinomycin D and Vinblastine, resulting in decreased cell proliferation and cell migration, as well as in increased apoptosis. Likewise, the combined treatment of cells with Actinomycin D or Vinblastine and Brefeldin A or Golgicide A, two disrupting agents of the ARF1 function, resulted in similar effects on cell proliferation, cell migration and apoptosis. Interestingly, each combined treatment had distinct effects on ERK1/2 and AKT signaling, as indicated by the decreased levels of either phospho-ERK1/2 or phospho-AKT. Our results suggest that disruption of Golgi function could be used as a strategy for the sensitization of cancer cells to chemotherapy.

Antipsychotic dopamine receptor antagonists, cancer, and cancer stem cells

Cancer is one of the deadliest diseases in the world. Despite extensive studies, treating metastatic cancers remains challenging. Years of research have linked a rare set of cells known as cancer stem cells (CSCs) to drug resistance, leading to the suggestion that eradication of CSCs might be an effective therapeutic strategy. However, few drug candidates are active against CSCs. New drug discovery is often a lengthy process. Drug screening has been advantageous in identifying drug candidates. Current understanding of cancer biology has revealed various clues to target cancer from different points of view. Many studies have found dopamine receptors (DRs) in various cancers. Therefore, DR antagonists have attracted a lot of attention in cancer research. Recently, a group of antipsychotic DR antagonists has been demonstrated to possess remarkable abilities to restrain and sensitize CSCs to existing chemotherapeutics by a process called differentiation approach. In this review, we will describe current aspects of CSC-targeting therapeutics, antipsychotic DR antagonists, and their extraordinary abilities to fight cancer.

Nanoparticle Delivery of miR-34a Eradicates Long-term-cultured Breast Cancer Stem Cells via Targeting C22ORF28 Directly

Rationale: Cancer stem cells (CSCs) have been implicated as the seeds of therapeutic resistance and metastasis, due to their unique abilities of self-renew, wide differentiation potentials and resistance to most conventional therapies. It is a proactive strategy for cancer therapy to eradicate CSCs. Methods: Tumor tissue-derived breast CSCs (BCSC), including XM322 and XM607, were isolated by fluorescence-activated cell sorting (FACS); while cell line-derived BCSC, including MDA-MB-231.SC and MCF-7.SC, were purified by magnetic-activated cell sorting (MACS). Analyses of microRNA and mRNA expression array profiles were performed in multiple breast cell lines. The mentioned nanoparticles were constructed following the standard molecular cloning protocol. Tissue microarray analysis has been used to study 217 cases of clinical breast cancer specimens. Results: Here, we have successfully established four long-term maintenance BCSC that retain their tumor-initiating biological properties. Our analyses of microarray and qRT-PCR explored that miR-34a is the most pronounced microRNA for investigation of BCSC. We establish hTERT promoter-driven VISA delivery of miR-34a (TV-miR-34a) plasmid that can induce high throughput of miR-34a expression in BCSC. TV-miR-34a significantly inhibited the tumor-initiating properties of long-term-cultured BCSC in vitro and reduced the proliferation of BCSC in vivo by an efficient and safe way. TV-miR-34a synergizes with docetaxel, a standard therapy for invasive breast cancer, to act as a BCSC inhibitor. Further mechanistic investigation indicates that TV-miR-34a directly prevents C22ORF28 accumulation, which abrogates clonogenicity and tumor growth and correlates with low miR-34 and high C22ORF28 levels in breast cancer patients. Conclusion: Taken together, we generated four long-term maintenance BCSC derived from either clinical specimens or cell lines, which would be greatly beneficial to the research progress in breast cancer patients. We further developed the non-viral TV-miR-34a plasmid, which has a great potential to be applied as a clinical application for breast cancer therapy.

Targeting oral cancer stemness and chemoresistance by isoliquiritigenin-mediated GRP78 regulation

Cancer stem cells (CSCs) are cells that drive tumorigenesis, contributing to metastasis and cancer recurrence as well as resistance to chemotherapy of oral squamous cell carcinomas (OSCC). Therefore, approaches to target CSCs become the subject of intense research for cancer therapy. In this study, we demonstrated that isoliquiritigenin, a chalcone-type flavonoid isolated from licorice root, exhibited more toxicity in oral cancer stem cells (OSCC-CSCs) compared to normal cells. Treatment of isoliquiritigenin not only inhibited the self-renewal ability but also reduced the expression of CSC markers, including the ALDH1 and CD44. In addition, the capacities of OSCC-CSCs to invade, metastasize and grow into a colony were suppressed by isoliquiritigenin. Most importantly, we showed that isoliquiritigenin potentiated chemotherapy along with downregulated expression of an ABC transporter that is associated with drug resistance, ABCG2. Moreover, a combination of isoliquiritigenin and Cisplatin significantly repressed the invasion and colony formation abilities of OSCC-CSCs. Our results suggested that administration of isoliquiritigenin reduced the protein expression of mRNA and membrane GRP78, a critical mediator of tumor biology. Overexpression of GRP78 reversed the inhibitory effect of isoliquiritigenin on OSCC-CSCs. Furthermore, isoliquiritigenin retarded the tumor growth in nude mice bearing OSCC xenografts. Taken together, these findings showed that isoliquiritigenin is an effective natural compound that can serve as an adjunct to chemotherapy for OSCC.

Heteronanoparticles by self-Assembly of Doxorubicin and Cyclopamine Conjugates

The preparation of heteronanoparticles (NPs) with doxorubicin (DOXO) and cyclopamine (CYP) conjugates is presented. Biological evaluation on A431 cell lines confirms the maintenance of the activity of the parental drugs. The in vivo study shows that self-assembled NPs reduce tumor growth and toxicity of chemotherapy.

Identification of T cell target antigens in glioblastoma stem-like cells using an integrated proteomics-based approach in patient specimens

Glioblastoma (GBM) is a highly aggressive brain tumor and still remains incurable. Among others, an immature subpopulation of self-renewing and therapy-resistant tumor cells-often referred to as glioblastoma stem-like cells (GSCs)-has been shown to contribute to disease recurrence. To target these cells personalized immunotherapy has gained a lot of interest, e.g. by reactivating pre-existing anti-tumor immune responses against GSC antigens. To identify T cell targets commonly presented by GSCs and their differentiated counterpart, we used a proteomics-based separation of GSC proteins in combination with a T cell activation assay. Altogether, 713 proteins were identified by LC-ESI-MS/MS mass spectrometry. After a thorough filtering process, 32 proteins were chosen for further analyses. Immunogenicity of corresponding peptides was tested ex vivo. A considerable number of these antigens induced T cell responses in GBM patients but not in healthy donors. Moreover, most of them were overexpressed in primary GBM and also highly expressed in recurrent GBM tissues. Interestingly, expression of the most frequent T cell target antigens could also be confirmed in quiescent, slow-cycling GSCs isolated in high purity by the DEPArray technology. Finally, for a subset of these T cell target antigens, an association between expression levels and higher T cell infiltration as well as an increased expression of positive immune modulators was observed. In summary, we identified novel immunogenic proteins, which frequently induce tumor-specific T cell responses in GBM patients and were also detected in vitro in therapy-resistant quiescent, slow-cycling GSCs. Stable expression of these T cell targets in primary and recurrent GBM support their suitability for future clinical use.

(-)-Epigallocatechin-3-Gallate Inhibits Colorectal Cancer Stem Cells by Suppressing Wnt/β-Catenin Pathway

The beneficial effects of tea consumption on cancer prevention have been generally reported, while (−)-Epigallocatechin-3-gallate (EGCG) is the major active component from green tea. Cancer stem cells (CSCs) play a crucial role in the process of cancer development. Targeting CSCs may be an effective way for cancer intervention. However, the effects of EGCG on colorectal CSCs and the underlying mechanisms remain unclear. Spheroid formation assay was used to enrich colorectal CSCs from colorectal cancer cell lines. Immunoblotting analysis and quantitative real-time polymerase chain reaction were used to measure the alterations of critical molecules expression. Immunofluorescence staining analysis was also used to determine the expression of CD133. We revealed that EGCG inhibited the spheroid formation capability of colorectal cancer cells as well as the expression of colorectal CSC markers, along with suppression of cell proliferation and induction of apoptosis. Moreover, we illustrated that EGCG downregulated the activation of Wnt/β-catenin pathway, while upregulation of Wnt/β-catenin diminished the inhibitory effects of EGCG on colorectal CSCs. Taken together, this study suggested that EGCG could be an effective natural compound targeting colorectal CSCs through suppression of Wnt/β-catenin pathway, and thus may be a promising agent for colorectal cancer intervention.

Cytoprotective effect of neuropeptides on cancer stem cells: vasoactive intestinal peptide-induced antiapoptotic signaling

Cancer stem cells (CSCs) are increasingly considered to be responsible for tumor initiation, metastasis and drug resistance. The drug resistance mechanisms activated in CSCs have not been thoroughly investigated. Although neuropeptides such as vasoactive intestinal peptide (VIP) can promote tumor growth and activate antiapoptotic signaling in differentiated cancer cells, it is not known whether they can activate antiapoptotic mechanisms in CSCs. The objectives of this study are to unravel the cytoprotective effects of neuropeptides and identify antiapoptotic mechanisms activated by neuropeptides in response to anticancer drug treatment in CSCs. We enriched and purified CSCs (CD44^+/high/CD24^-/low or CD133⁺ population) from breast and prostate cancer cell lines, and demonstrated their stemness phenotype. Of the several neuropeptides tested, only VIP could protect CSCs from drug-induced apoptosis. A functional correlation was found between drug-induced apoptosis and dephosphorylation of proapoptotic Bcl2 family protein BAD. Similarly, VIP-induced cytoprotection correlated with BAD phosphorylation at Ser112 in CSCs. Using pharmacological inhibitors and dominant-negative proteins, we showed that VIP-induced cytoprotection and BAD phosphorylation are mediated via both Ras/MAPK and PKA pathways in CSCs of prostate cancer LNCaP and C4-2 cells, but only PKA signaling was involved in CSCs of DUVIPR (DU145 prostate cancer cells ectopically expressing VIP receptor) and breast cancer MCF7 cells. As each of these pathways partially control BAD phosphorylation at Ser112, both have to be inhibited to block the cytoprotective effects of VIP. Furthermore, VIP is unable to protect CSCs that express phosphorylation-deficient mutant-BAD, suggesting that BAD phosphorylation is essential. Thus, antiapoptotic signaling by VIP could be one of the drug resistance mechanisms by which CSCs escape from anticancer therapies. Our findings suggest the potential usefulness of VIP receptor inhibition to eliminate CSCs, and that targeting BAD might be an attractive strategy for development of novel therapeutics.

Chitosan nanoparticle-mediated co-delivery of shAtg-5 and gefitinib synergistically promoted the efficacy of chemotherapeutics through the modulation of autophagy

Background

Autophagy reportedly plays vital and complex roles in many diseases. During times of starvation or energy deficiency, autophagy will occur at higher levels to provide cells with the nutrients or energy necessary to survive in stressful conditions. Some anti-cancer drugs induce protective autophagy and reduce cell apoptosis. Autophagy can adversely affect apoptosis, and blocking autophagy will increase the sensitivity of cells to apoptosis signals.

Methods

We designed chitosan nanoparticles (NPs) to promote the co-delivery of gefitinib (an anti-cancer drug) and shRNA-expressing plasmid DNA that targets the Atg-5 gene (shAtg-5) as an autophagy inhibitor to improve anti-cancer effects and autophagy mediation.

Results

The results showed that when compared to treatment with a single drug, chitosan NPs were able to facilitate the intracellular distribution of NPs, and they improved the transfection efficiency of gene in vitro. The co-delivery of gefitinib and shAtg-5 increased cytotoxicity, induced significant apoptosis through the prohibition of autophagy, and markedly inhibited tumor growth in vivo.

Conclusions

The co-delivery of gefitinib/shAtg-5 in chitosan NPs produced superior anti-cancer efficacy via the internalization effect of NPs, while blocking autophagy with shAtg-5 enhanced the synergistic antitumor efficacy of gefitinib.

Relevance of mortalin to cancer cell stemness and cancer therapy

Mortalin/mtHsp70 is a member of Hsp70 family of proteins. Enriched in a large variety of cancers, it has been shown to contribute to the process of carcinogenesis by multiple ways including inactivation of tumor suppressor p53 protein, deregulation of apoptosis and activation of EMT signaling. In this study, we report that upregulation of mortalin contributes to cancer cell stemness. Several cancer cell stemness markers, such as ABCG2, OCT-4, CD133, ALDH1, CD9, MRP1 and connexin were upregulated in mortalin-overexpressing cells that showed higher ability to form spheroids. These cells also showed higher migration, and were less responsive to a variety of cancer chemotherapeutic drugs. Of note, knockdown of mortalin by specific shRNA sensitized these cells to all the drugs used in this study. We report that low doses of anti-mortalin molecules, MKT-077 and CAPE, also caused similar sensitization of cancer cells to chemotherapeutic drugs and hence are potential candidates for effective cancer chemotherapy.

Exosome-Based Cancer Therapy: Implication for Targeting Cancer Stem Cells

Drug resistance, difficulty in specific targeting and self-renewal properties of cancer stem cells (CSCs) all contribute to cancer treatment failure and relapse. CSCs have been suggested as both the seeds of the primary cancer, and the roots of chemo- and radio-therapy resistance. The ability to precisely deliver drugs to target CSCs is an urgent need for cancer therapy, with nanotechnology-based drug delivery system being one of the most promising tools to achieve this in the clinic. Exosomes are cell-derived natural nanometric vesicles that are widely distributed in body fluids and involved in multiple disease processes, including tumorigenesis. Exosome-based nanometric vehicles have a number of advantages: they are non-toxic, non-immunogenic, and can be engineered to have robust delivery capacity and targeting specificity. This enables exosomes as a powerful nanocarrier to deliver anti-cancer drugs and genes for CSC targeting therapy. Here, we will introduce the current explorations of exosome-based delivery system in cancer therapy, with particular focus on several exosomal engineering approaches that have improved their efficiency and specificity for CSC targeting.

Hypoxia inducible factor down-regulation, cancer and cancer stem cells (CSCs): ongoing success stories

In cancers, hypoxia inducible factor 1 (HIF-1) is an over-expressed transcription factor, which regulates a large set of genes involved in tumour vascularization, metastases, and cancer stem cells (CSCs) formation and self-renewal. This protein has been identified as a relevant target in oncology and several HIF-1 modulators are now marketed or in advanced clinical trials. The purpose of this review is to summarize the advances in the understanding of its regulation and its inhibition, from the medicinal chemist point of view. To this end, we selected in the recent literature relevant examples of "hit" compounds, including small-sized organic molecules, pseudopeptides and nano-drugs, exhibiting in vitro and/or in vivo both anti-HIF-1 and anti-tumour activities. Whenever possible, a particular emphasis has been dedicated to compounds that selectively target CSCs.

Boron-containing delocalised lipophilic cations for the selective targeting of cancer cells

To limit the incidence of relapse, cancer treatments must not promote the emergence of drug resistance in tumour and cancer stem cells. Under the proviso that a therapeutic amount of boron is selectively delivered to cancer cells, Boron Neutron Capture Therapy (BNCT) may represent one approach that meets this requirement. To this end, we report the synthesis and pharmacology of several chemical entities, based on boron-rich carborane moieties that are functionalised with Delocalized Lipophilic Cations (DLCs), which selectively target the mitochondria of tumour cells. The treatment of tumour and cancer stem cells (CSCs) with such DLC-functionalized carboranes (DLC-carboranes) induces cell growth arrest that is both highly cancer-cell-selective and permanent. Experiments involving cultures of normal and cancer cells show that only normal cells exhibit recapitulation of their proliferation potential upon removal of the DLC-carborane treatment. At the molecular level, the pharmacological effect of DLC-carboranes is exerted through activation of the p53/p21 axis.

Xanthohumol, a Prenylated Chalcone from Hops, Inhibits the Viability and Stemness of Doxorubicin-Resistant MCF-7/ADR Cells

Xanthohumol is a unique prenylated flavonoid in hops (Humulus lupulus L.) and beer. Xanthohumol has been shown to possess a variety of pharmacological activities. There is little research on its effect on doxorubicin-resistant breast cancer cells (MCF-7/ADR) and the cancer stem-like cells exiting in this cell line. In the present study, we investigate the effect of xanthohumol on the viability and stemness of MCF-7/ADR cells. Xanthohumol inhibits viability, induces apoptosis, and arrests the cell cycle of MCF-7/ADR cells in a dose-dependent manner; in addition, xanthohumol sensitizes the inhibition effect of doxorubicin on MCF-7/ADR cells. Interestingly, we also find that xanthohumol can reduce the stemness of MCF-7/ADR cells evidenced by the xanthohumol-induced decrease in the colony formation, the migration, the percentage of side population cells, the sphere formation, and the down-regulation of stemness-related biomarkers. These results demonstrate that xanthohumol is a promising compound targeting the doxorubicin resistant breast cancer cells and regulating their stemness, which, therefore, will be applied as a potential candidate for the development of a doxorubicin-resistant breast cancer agent and combination therapy of breast cancer.