CD44 antibody-targeted liposomal nanoparticles for molecular imaging and therapy of hepatocellular carcinoma

l-Histidine Crystals as Efficient Vehicles to Deliver Hydrophobic Molecules

l-Histidine (l-His) molecules can form highly ordered fluorescent crystals with tunable size and geometry. The polymorph A crystal of l-His contains hydrophobic domains within the structure's interior. Here, we demonstrate that these hydrophobic domains can serve as vehicles for highly efficient entrapment and transport of hydrophobic small molecules. This strategy shows the ability of l-His crystals to mask the hydrophobicity of various small molecules, helping to address issues related to their poor solubility and low bioavailability. Furthermore, we demonstrate that we can modify the surface of these crystals to define their function, suggesting the significance of l-His crystals in designing site-specific and bioresponsive platforms. As a demonstration, we use l-His crystals with loaded doxorubicin, featuring hyaluronic acid covalently bonded on the crystal surface, controlling its release in response to hyaluronidase. This strategy for entrapment of hydrophobic small molecules suggests the potential of l-His crystals for targeted drug-delivery applications.

Liposomal Nanostructures for Drug Delivery in Gastrointestinal Cancers

Gastrointestinal (GI) cancers like liver, pancreatic, colorectal, and gastric cancer remain some of the most difficult and aggressive cancers. Nanoparticles like liposomes had been approved in the clinic for cancer therapy dating as far back as 1995. Over the years, liposomal formulations have come a long way, facing several roadblocks and failures, and advancing by optimizing formulations and incorporating novel design approaches to navigate therapeutic delivery challenges. The first liposomal formulation for a GI cancer drug was approved recently in 2015, setting the stage for further clinical developments of liposome-based delivery systems for therapies against GI malignancies. This article reviews the design considerations and strategies that can be used to deliver drugs to GI tumors, the wide range of therapeutic agents that have been explored in preclinical as well as clinical studies, and the current therapies that are being investigated in the clinic against GI malignancies.

Low-toxicity transferrin-guided polymersomal doxorubicin for potent chemotherapy of orthotopic hepatocellular carcinoma in vivo

Hepatocellular carcinoma (HCC) remains one of the most lethal malignancies. The current chemotherapy with typically low tumor uptake and high toxicity reveals a poor anti-HCC efficacy. Here, we report transferrin-guided polycarbonate-based polymersomal doxorubicin (Tf-Ps-Dox) as a low-toxic and potent nanotherapeutic agent for effective treatment of liver tumor using a transferrin receptor (TfR)-positive human liver tumor SMMC-7721 model. Tf-Ps-Dox was facilely fabricated with small size of ca. 75 nm and varying Tf densities from 2.2% to 7.0%, by postmodification of maleimide-functionalized Ps-Dox (Dox loading content of 10.6 wt%) with thiolated transferrin. MTT assays showed that Tf-Ps-Dox had an optimal Tf surface density of 3.9%. The cellular uptake, intracellular Dox level, and anticancer efficacy of Tf-Ps-Dox to SMMC-7721 cells were inhibited by supplementing free transferrin, which supports that Tf-Ps-Dox is endocytosed through TfR. Interestingly, Tf-Ps-Dox exhibited a high accumulation of 8.5%ID/g (percent injected dose per gram of tissue) in subcutaneous SMMC-7721 tumors, which was 2- and 3-fold higher than that of nontargeted Ps-Dox and clinically used liposomal Dox formulation (Lipo-Dox), respectively. The median survival times of mice bearing orthotopic SMMC-7721 tumors increased from 82, 88 to 96 days when treated with Tf-Ps-Dox at Dox doses from 8, 12 to 16 mg/kg, which was significantly longer than that of Ps-Dox at 8 mg/kg (58 days) and Lipo-Dox at 4 mg/kg (48 days) or PBS (36 days). Notably, unlike Lipo-Dox, no body weight loss and damage to major organs could be discerned for all Tf-Ps-Dox groups, indicating that Tf-Ps-Dox caused low systemic toxicity. This transferrin-dressed polymersomal doxorubicin provides a potent and low-toxic treatment modality for human hepatocellular carcinoma. STATEMENT OF SIGNIFICANCE: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Vast work has focused on developing HCC-targeted nanotherapeutics. However, none of the nanotherapeutics has advanced to clinics, partly because the ligands used have not been validated in patients. Transferrin (Tf) is a natural ligand for transferrin receptor (TfR) that is overexpressed on cancerous cells, and it is currently under clinical trials (MBP-426 and CALAA-01) for the treatment of solid tumors. We designed Tf-functionalized polymersomal doxorubicin (Tf-Ps-Dox) for targeted therapy of orthotopic SMMC-7721 tumor in nude mice. Tf-Ps-Dox showed potent anti-HCC efficacy and significantly improved survival time with low toxicity as compared with nontargeted Ps-Dox and clinical liposomal Dox (Lipo-Dox). Hence, Tf-Ps-Dox is very appealing for targeted treatment of HCC.

The Evolving Landscape of Cancer Stem Cells and Ways to Overcome Cancer Heterogeneity

Cancer stem cells (CSCs) with therapeutic resistance and plasticity can be found in various types of tumors and are recognized as attractive targets for treatments. As CSCs are derived from tissue stem or progenitor cells, and/or dedifferentiated mature cells, their signal transduction pathways are critical in the regulation of CSCs; chronic inflammation causes the accumulation of genetic mutations and aberrant epigenetic changes in these cells, potentially leading to the production of CSCs. However, the nature of CSCs appears to be stronger than the treatments of the past. To improve the treatments targeting CSCs, it is important to inhibit several molecules on the signaling cascades in CSCs simultaneously, and to overcome cancer heterogeneity caused by the plasticity. To select suitable target molecules for CSCs, we have to explore the landscape of CSCs from the perspective of cancer stemness and signaling systems, based on the curated databases of cancer-related genes. We have been studying the integration of a broad range of knowledge and experiences from cancer biology, and also from other interdisciplinary basic sciences. In this review, we have introduced the concept of developing novel strategies targeting CSCs.

The Photothermal Effect of Targeted Methotrexate-Functionalized Multi-Walled Carbon Nanotubes on MCF7 Cells

Our goal is to reduce the release rate of methotrexate (MTX) and increase cell death efficiency.Carboxylated multi-walled carbon nanotubes (MWCNT-COOH) were functionalized with MTX as a cytotoxic agent, FA as a targeting moiety and polyethylene amine (PEI) as a hydrophilic agent. Ultimately, MWCNT-MTX and MWCNT-MTX-PEI-FA were synthesized. Methotrexate release studies were conducted in PBS and cytotoxic studies were carried out by means of the MTT tassay. Methotrexate release studies from these two carriers demonstrated that the attachment of PEI-FA onto MWCNT-MTX reduces the release rate of methotrexate. The IC50 of MWCNT-MTX-PEI-FA and MWCNT-MTX have been calculated as follows: 9.89 ± 0.38 and 16.98 ± 1.07 µg/mL, respectively. Cytotoxic studies on MWCNT-MTX-PEI-FA and MWCNT-MTX in the presence of an IR laser showed that at high concentrations, they had similar toxicities due to the MWCNT's photothermal effect. Targeting effect studies in the presence of the IR laser on the cancer cells have shown that MWCNT-MTX-PEI-FA, MWCNT-MTX, and f-MWCNT have triggered the death of cancer cells by 55.11 ± 1.97%, 49.64 ± 2.44%, and 37 ± 0.70%, respectively. The release profile of MTX in MWCNT-MTX-PEI-FA showed that the presence of PEI acts as a barrier against release and reduces the MTX release rate. In the absence of a laser, MWCNT-MTX-PEI-FA exhibits the highest degree of cytotoxicity. In the presence of a laser, the cytotoxicity of MWCNT-MTX and MWCNT-MTX-PEI-FA has no significant difference. Targeting studies have shown that MWCNT-MTX-PEI-FA can be absorbed by cancer cells exclusively.

Advances in Receptor-Mediated, Tumor-Targeted Drug Delivery

Receptor-mediated drug delivery presents an opportunity to enhance therapeutic efficiency by accumulating drug within the tissue of interest and reducing undesired, off-target effects. In cancer, receptor overexpression is a platform for binding and inhibiting pathways that shape biodistribution, toxicity, cell binding and uptake, and therapeutic function. This review will identify tumor-targeted drug delivery vehicles and receptors that show promise for clinical translation based on quantitative in vitro and in vivo data. The authors describe the rationale to engineer a targeted drug delivery vehicle based on the ligand, chemical conjugation method, and type of drug delivery vehicle. Recent advances in multivalent targeting and ligand organization on tumor accumulation are discussed. Revolutionizing receptor-mediated drug delivery may be leveraged in the therapeutic delivery of chemotherapy, gene editing tools, and epigenetic drugs.

Cancer stem cells in hepatocellular carcinoma: an overview and promising therapeutic strategies

The poor clinical outcome of hepatocellular carcinoma (HCC) patients is ascribed to the resistance of HCC cells to traditional treatments and tumor recurrence after curative therapies. Cancer stem cells (CSCs) have been identified as a small subset of cancer cells which have high capacity for self-renewal, differentiation and tumorigenesis. Recent advances in the field of liver CSCs (LCSCs) have enabled the identification of CSC surface markers and the isolation of CSC subpopulations from HCC cells. Given their central role in cancer initiation, metastasis, recurrence and therapeutic resistance, LCSCs constitute a therapeutic opportunity to achieve cure and prevent relapse of HCC. Thus, it is necessary to develop therapeutic strategies to selectively and efficiently target LCSCs. Small molecular inhibitors targeting the core stemness signaling pathways have been actively pursued and evaluated in preclinical and clinical studies. Other alternative therapeutic strategies include targeting LCSC surface markers, interrupting the CSC microenvironment, and altering the epigenetic state. In this review, we summarize the properties of CSCs in HCC and discuss novel therapeutic strategies that can be used to target LCSCs.

Hyaluronic acid/doxorubicin nanoassembly-releasing microspheres for the transarterial chemoembolization of a liver tumor

Doxorubicin (DOX)-loaded, hyaluronic acid-ceramide (HACE) nanoassembly-releasing poly(lactic-co-glycolic acid) (PLGA) microspheres (MSs) were developed for transarterial chemoembolization (TACE) therapy of liver cancer. DOX/HACE MSs with a mean diameter of 27 μm and a spherical shape were prepared based on the modified emulsification method. Their in vitro biodegradability in artificial biological fluids was observed. A more sustained drug release pattern was observed from DOX/HACE MS than from DOX MS at pH 7.4. The cellular internalization efficiency of DOX of the DOX/HACE MS group was higher than that of the DOX MS group in liver cancer cells (HepG2 and McA-RH7777 cells), mainly due to CD44 receptor-mediated endocytosis of the released DOX/HACE nanoassembly. In both HepG2 and McA-RH7777 cells, the antiproliferation and apoptotic potentials of the DOX/HACE MS were significantly higher than those of the DOX MS (p < .05). Notably, in the McA-RH7777 tumor-implanted rat models, a better tumor growth suppression, a lower tumor viable portion, and a higher incidence of apoptosis were presented in the DOX/HACE MS group than in the DOX MS group after intra-arterial (IA) administration. DOX/HACE-based nanoassembly release from the DOX/HACE MS seems to elevate the cellular accumulation of DOX and its anticancer activities. The developed DOX/HACE MS can be used as a drug-loaded HA nanoassembly-releasing MS system for TACE therapy of liver cancer.

MSCs inhibit tumor progression and enhance radiosensitivity of breast cancer cells by down-regulating Stat3 signaling pathway

The acquisition of radioresistance by breast cancer cells during radiotherapy may lead to cancer recurrence and poor survival. Signal transducer and activator of transcription 3 (Stat3) is activated in breast cancer cells and, therefore, may be an effective target for overcoming therapeutic resistance. Mesenchymal stem cells (MSCs) have been investigated for use in cancer treatment. Here, we investigated the potential of MSC conditioned medium (MSC-CM) in sensitizing breast cancer to radiotherapy. It was found that MSC-CM could inhibit the level of activated Stat3, suppress cancer growth, and exhibit synergetic effects with radiation treatment in vitro and in vivo. Furthermore, MSC-CM reduced the ALDH-positive cancer stem cells (CSCs) population, modulated several potential stem cell markers, and decreased tumor migration, as well as metastasis. These results demonstrate that MSC-CM suppresses breast cancer cells growth and sensitizes cancer cells to radiotherapy through inhibition of the Stat3 signaling pathway, thus, providing a novel strategy for breast cancer therapy by overcoming radioresistance.

Sialic-Acid-Anchored Micelles: A Hierarchical Targeting Device for Enhanced Tumor Tissue Accumulation and Cellular Internalization

Targeted drug delivery systems (TDDS) have attracted wide attention for their reduced drug side effects and improved antitumor efficacy in comparison with traditional preparations. While targeting moieties in existing TDDS have principally focused on recognition of receptors on the surface of tumor cells, accumulation into tumor tissue only could be performed by enhanced permeability and retention effects and active transportation into tumor cells. Doxorubicin (DOX)-loaded sialic acid-dextran (Dex)-octadecanoic acid (OA) micelles (SA-Dex-OA/DOX) were designed for targeting hepatocellular carcinoma effectively. The synthesized conjugates could self-aggregate to form micelles with a critical micelle concentration of 27.6 μg·mL^-1 and diameter of 54.53 ± 3.23 nm. SA-Dex-OA micelles incorporated with 4.36% DOX-loading content could prolong in vitro drug release to 96 h with 80% of final release. Cellular transportation studies revealed that SA-Dex-OA micelles mediated more efficient DOX delivery into Bel-7402 cells than those without SA modification. In vivo biodistribution testing demonstrated that SA-Dex-OA/ICG micelles showed 3.05-fold higher accumulation into Bel-7402 tumors. The recognition of overexpressed E-selectin in inflammatory tumor vascular endothelial cells led to a large accumulation of SA-Dex-OA/ICG micelles into tumor tissue, and the E-selectin upregulated on the surface of tumor cells contributed to active cellular transportation into tumor cells. Accordingly, SA-Dex-OA/DOX exhibited prior suppression of Bel-7402 tumor growth greater than that of Dex-OA/DOX micelles and free DOX (the tumor inhibition: 79.2% vs 61.0 and 51.3%). These results suggest that SA-functionalized micelles with dual targeting properties have high potential for liver cancer therapy.

PD-1 blockade in combination with zoledronic acid to enhance the antitumor efficacy in the breast cancer mouse model

Background

Blockade of PD-1 receptor may provide proof of concepts for the activity of an immune-modulation approach for the treatment of breast cancer (BC). Zoledronic acid (ZA) has been proven to inhibit angiogenesis, invasion, and adhesion of tumor cells. The aim of this study was to investigate the potential of monoclonal antibody against T cell checkpoint PD-1 in combination with chemotherapeutic drug ZA in BC mouse model.

Methods

The 4 T1-fLuc mouse BC model was used in this study. The anti-tumor efficacy of anti-PD-1 antibody alone or in combination with ZA was monitored by measuring bioluminescence imaging (BLI) and tumor volume. At the end of study, the flow cytometry was used to determine the immune cell population in tumors after different treatment.

Results

The results showed that mice treated with the combination therapy of anti-PD-1 antibody plus ZA exhibited better antitumor response compared to untreated controls or single therapy with no obvious toxicity.

Conclusion

Our study provides preclinical evidence for the enhanced BC treatment benefit through targeting co-signal molecules by combining anti-PD-1 antibody plus ZA treatment.

Antibody-modified liposomes for tumor-targeting delivery of timosaponin AIII

Introduction

Timosaponin AIII (TAIII), as a steroid saponin in Anemarrhena asphodeloides, has favorable potential as an antitumor candidate. However, its hydrophobicity and low bioavailability severely limit its in vivo antitumor efficacy.

Methods

To overcome this drawback, TAIII-loaded liposomes (LP) were prepared to improve TAIII solubility and extend its circulation time. Furthermore, anti-CD44 antibody-modified LP (CD44-LP) was prepared to enhance the therapeutic index of TAIII. The LP and CD44-LP were also characterized through their biological activity, target selective binding and uptake, and in vivo pharmacokinetics.

Results

Compared with free TAIII, both LP and CD44-LP possessed a desirable sustained-release profile in vitro, with ~14.2- and 10.7-fold longer TAIII half-life, respectively, and 1.7- and 1.9-fold larger area under the curve, respectively. LP and CD44-LP enhanced TAIII antitumor activity against HepG2 cells and in a xenograft mouse model without detectable toxicity. In particular, CD44-LP exhibited notably higher cytotoxicity than did LP, with a lower half-maximal inhibitory concentration (48 h). CD44-LP exhibited stronger tumor inhibition, and the tumor inhibitory effect was 1.3-fold that of LP. Furthermore, confocal laser scanning microscopy and in vivo near-infrared imaging of a xenograft mouse model revealed that compared with LP, CD44-LP could effectively enhance tumor accumulation.

Conclusion

Taken together, the results indicate that both CD44-LP and LP can considerably extend TAIII circulation time, increase tumor-targeted accumulation, and enhance antitumor activity. Thus, the anti-CD44 antibody-modified liposome is a promising candidate for treating CD44-positive cancer with considerable antitumor effects.

Cancer stem cells (CSCs), cervical CSCs and targeted therapies

Accumulating evidence has shown that cancer stem cells (CSCs) have a tumour-initiating capacity and play crucial roles in tumour metastasis, relapse and chemo/radio-resistance. As tumour propagation initiators, CSCs are considered to be promising targets for obtaining a better therapeutic outcome. Cervical carcinoma is the most common gynaecological malignancy and has a high cancer mortality rate among females. As a result, the investigation of cervical cancer stem cells (CCSCs) is of great value. However, the numbers of cancer cells and corresponding CSCs in malignancy are dynamically balanced, and CSCs may reside in the CSC niche, about which little is known to date. Therefore, due to their complicated molecular phenotypes and biological behaviours, it remains challenging to obtain “purified” CSCs and continuously culture CSCs for further in vitro studies without the cells losing their stem properties. At present, CSC-related markers and functional assays are used to purify, identify and therapeutically target CSCs both in vitro and in vivo. Nevertheless, CSC-related markers are not universal to all tumour types, although some markers may be valid in multiple tumour types. Additionally, functional identifications based on CSC-specific properties are usually limited in in vivo studies. Furthermore, an optimal method for identifying potential CCSCs in CCSC studies has not been previously published, and these techniques are currently of great importance. This article updates our knowledge on CSCs and CCSCs, reviews potential stem cell markers and functional assays for identifying CCSCs, and describes the potential of targeting CCSCs in the treatment of cervical carcinoma.

Efficient targeted tumor imaging and secreted endostatin gene delivery by anti-CD105 immunoliposomes

BACKGROUND

Anti-CD105 mAb-conjugated immunoliposomes, loaded with secreted mouse endostatin gene, were developed for targeted tumor imaging and antiangiogenic gene therapy.

METHODS

The liposomes were investigated for size, zeta-potential, lipid content, antibody binding ability, and pcDNA loading capacity. The ability of immunoliposomes to target tumor-derived endothelial cells and perform gene transfer in vitro was measured and their basic biocompatibility was evaluated. A nude mouse/breast cancer xenograft model was used to examine the tumor internalization of fluorescent-labeled liposomes and the clinical potential of immnuoliposomes loaded with pcDNA3.1-CSF1-endostatin.

RESULTS

Loaded immunoliposomes were homogenously distributed with a well-defined spherical shape and bilayer, diameter of 122 ± 11 nm, and zeta potential + 1.40 mV. No significant differences were observed in body weight, liver index, oxidative stress, or liver and kidney function in mice after liposomes exposure. The addition of CD105 mAb to liposomes conferred the ability to target tumor-derived endothelial cells in vitro and in vivo. Systemic intravenous administration of fluorescent immunoliposomes in the xenograft model resulted in selective and efficient internalization in tumor vasculature. Treatment of mice with pcDNA3.1-CSF1-endostatin-loaded immunoliposomes suppressed tumor growth by 71%.

CONCLUSIONS

These data demonstrate the advantages of using anti-CD105 mAb-conjugated immunoliposomes to enhance tumor targeting, imaging, and gene transfer applications.

Surface Engineering of Nanoparticles for Targeted Delivery to Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-associated deaths worldwide. There is a lack of efficient therapy for HCC; the only available first-line systemic drug, sorafenib, can merely improve the average survival by two months. Among the efforts to develop an efficient therapy for HCC, nanomedicine has drawn the most attention, owing to its unique features such as high drug-loading capacity, intrinsic anticancer activities, integrated diagnostic and therapeutic functionalities, and easy surface engineering with targeting ligands. Despite its tremendous advantages, no nanomedicine can be effective unless it successfully targets the tumor site, which is a challenging task. In this review, the features of HCC are described, and the physiological hurdles that prevent nanoparticles from targeting HCC are discussed. Then, the surface physicochemical factors of nanoparticles that can influence targeting efficiency are discussed. Finally, a thorough description of the physiological barriers that nanomedicine must conquer before uptake by HCC cells if possible is provided, as well as the surface engineering approaches to nanomedicine to achieve targeted delivery to HCC cells. The physiological hurdles and corresponding solutions summarized in this review provide a general guide for the rational design of HCC targeting nanomedicine systems.

EGFR-targeted multifunctional polymersomal doxorubicin induces selective and potent suppression of orthotopic human liver cancer in vivo

Liver cancer is a globally leading malignancy that has a poor five-year survival rate of less than 20%. The systemic chemotherapeutics are generally ineffective for liver cancers partly due to fast clearance and low tumor uptake. Here, we report that GE11 peptide functionalized polymersomal doxorubicin (GE11-PS-DOX) effectively targets and inhibits epidermal growth factor receptor (EGFR)-positive SMMC7721 orthotopic human liver tumor xenografts in mice. GE11-PS-DOX with a GE11 surface density of 10% displayed a high drug loading of 15.4 wt%, a small size of 78 nm, and glutathione-triggered release of DOX. MTT assays, flow cytometry and confocal microscopy studies revealed that GE11-PS-DOX mediated obviously more efficient DOX delivery into SMMC7721 cells than the non-targeting PS-DOX and clinically used liposomal doxorubicin (Lipo-DOX) controls. The in vivo studies showed that GE11-PS-DOX had a long circulation time and an extraordinary accumulation in the tumors (13.3 %ID/g). Interestingly, GE11-PS-DOX caused much better treatment of SMMC7721 orthotopic liver tumor-bearing mice as compared to PS-DOX and Lipo-DOX. The mice treated with GE11-PS-DOX (12 mg DOX equiv./kg) exhibited a significantly improved survival rate (median survival time: 130 days versus 70 and 38 days for PS-DOX at 12 mg DOX equiv./kg and Lipo-DOX at 6 mg DOX equiv./kg, respectively) and achieved 50% complete regression. Notably, GE11-PS-DOX induced obviously lower systemic toxicity than Lipo-DOX. EGFR-targeted multifunctional polymersomal doxorubicin with improved efficacy and safety has a high potential for treating human liver cancers.

STATEMENT OF SIGNIFICANCE

Liver cancer is one of the top five leading causes of cancer death worldwide. The systemic chemotherapeutics and biotherapeutics generally have a low treatment efficacy for hepatocellular carcinoma partly due to fast clearance and/or low tumor uptake. Nanomedicines based on biodegradable micelle and polymersomes offer a most promising treatment for malignant liver cancers. Their clinical effectiveness remains, however, suboptimal owing to issues like inadequate systemic stability, low tumor accumulation and selectivity, and poor control over drug release. Here we report that GE11 peptide-functionalized, disulfide-crosslinked multifunctional polymersomal doxorubicin (GE11-PS-DOX) can effectively suppress the growth of orthotopic SMMC7721 human liver tumors in nude mice. They showed significantly decreased systemic toxicity and improved mouse survival rate with 3.4-fold longer median survival time as compared to clinically used pegylated liposomal doxorubicin (Lipo-DOX) and achieving 50% complete regression. GE11-PS-DOX, based on PEG-PTMC is biodegradable, nontoxic, and easy to prepare, appears as a safe, robust, versatile and all-function-in-one nanoplatform that has a high potential in targeted chemotherapy of EGFR expressed hepatocellular carcinoma.

Five-Part Pentameric Nanocomplex Shows Improved Efficacy of Doxorubicin in CD44+ Cancer Cells

The CD44 receptor is common among many cancer types where overexpression is synonymous with poor prognosis in prostate, glioma, and breast cancer. More notably CD44 overexpression has been shown in a number of different cancer stem cells (CSC) which are present in many solid tumors and drive growth, recurrence, and resistance to conventional therapies. Triple negative breast cancer CSCs correlate to worse prognosis and early relapse due to higher drug resistance and increased tumor heterogeneity and thus are prime targets for anticancer therapy. To specifically target cells overexpressing CD44 receptors, including CSCs, we synthesized a pentameric nanocomplex (PNC) containing gold nanoparticles, doxorubicin (Dox) conjugated to thiolated hyaluronic acid via an acid-labile hydrazone bond, and thiolated poly(ethylene glycol) DNA CD44 aptamer. In vitro drug release was highest at 8 h time point at acidic pH (pH 4.7) and in 10 mM glutathione. The PNC is almost an order of magnitude more effective than Dox alone in CD44+ cells versus CD44 low cells. Functionally, the PNC reduced CSC self-renewal. The PNC provides a therapeutic strategy that can improve the efficiency of Dox and decrease nontargeted toxicity thereby prolonging its use to individual patients.

New molecular targets for functionalized nanosized drug delivery systems in personalized therapy for hepatocellular carcinoma

Hepatocellular carcinoma, the most frequent solid tumor of the liver, has a very poor prognosis, being the second most common cause of death from cancer worldwide. The incidence and mortality of this liver tumor are increasing in most areas of the world as a consequence of aging and the emerging of new risk factors such as the metabolic syndrome, beside the recognized role of hepatitis B and C viral infections and alcohol abuse. Despite the increasing knowledge on the molecular mechanisms underlying hepatic carcinogenesis, effective therapeutic strategies are still an unmet clinical need. Efforts have been made to develop selective drugs as well as effective targeted drug delivery systems. The development of novel drug carriers for therapeutic molecules can indeed offer a valuable strategy to ameliorate the efficacy of HCC treatment. In this review, we discuss recent drug delivery strategies for HCC treatment based on the exploitation of targeted nanoparticles (NPs). Indeed, a few of these platforms have achieved an advanced stage of preclinical development. Here, we review the most promising drug nanovehicles based on both synthetic and natural polymers, including polysaccharides that have emerged for their biocompatibility and biodegradability. To maximize site-selectivity and therapeutic efficacy, drug delivery systems should be functionalized with ligands which can specifically recognize and bind targets expressed by HCC, namely cell membrane associated antigens, receptors or biotransporters. Cell surface and intracellular molecular targets are exploited either to selectively deliver drug-loaded nanovehicles or to design novel selective therapeutics. In conclusion, the combination of novel and safe drug delivery strategies based on site-specific targeted drug nanovehicles with therapeutic molecular targets may significantly improve the pharmacological efficacy for the treatment of HCC.

Iron depletion is a novel therapeutic strategy to target cancer stem cells

Adequate iron levels are essential for human health. However, iron overload can act as catalyst for the formation of free radicals, which may cause cancer. Cancer stem cells (CSCs), which maintain the hallmark stem cell characteristics of self-renewal and differentiation capacity, have been proposed as a driving force of tumorigenesis and metastases. In the present study, we investigated the role of iron in the proliferation and stemness of CSCs, using the miPS-LLCcm cell model. Although the anti-cancer agents fluorouracil and cisplatin suppressed the proliferation of miPS-LLCcm cells, these drugs did not alter the expression of stemness markers, including Nanog, SOX2, c-Myc, Oct3/4 and Klf4. In contrast, iron depletion by the iron chelators deferasirox and deferoxamine suppressed the proliferation of miPS-LLCcm cells and the expression of stemness markers. In an allograft model, deferasirox inhibited the growth of miPS-LLCcm implants, which was associated with decreased expression of Nanog and Sox2. Altogether, iron appears to be crucial for the proliferation and maintenance of stemness of CSCs, and iron depletion may be a novel therapeutic strategy to target CSCs.

Single-walled carbon nanotube: One specific inhibitor of cancer stem cells in osteosarcoma upon downregulation of the TGFβ1 signaling

Cancer stem cells (CSCs) are believed to have a critical role in tumorigenesis, metastasis, therapeutic resistance or recurrence. Therefore, strategies designed to specifically target and eliminate CSCs have become one of the most promising and desirable ways for tumor treatment. Osteosarcoma stem cells (OSCs), the CSCs in osteosarcoma (OS), are critically associated with OS progression. Here, we show that single-walled carbon nanotubes (SWCNTs), including unmodified SWCNT (SWCNT-Raw) and SWCNT-COOH, have the ability to specifically inhibit the process of TGFβ1-induced OS cells dedifferentiation, prevent the stem cell phenotypes acquisition in OS cells and reduce the OSC viability under conditions which mimic the OS microenvironment. Concurrently, SWCNT treatment significantly down-regulates the expression of OSC markers in OS, and markedly reduces the tumor microvessel density and tumor growth. Furthermore, we found that SWCNT could suppress the TGFβ1-induced activation of TGFβ type I receptor and downstream signaling, which are key for the OSC formation and maintenance. Our results reveal an unexpected function of SWCNT in negative modulation of OSCs, and provide significant implications for the potential CSCs-targeted therapeutic applications of SWCNT.

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of cancers. In this review, the importance of CSCs in cancer development and therapeutic response has been stated. Different CSCs cluster of differentiation (CD) biomarkers and their specific function and applications in the treatment of cancers have been discussed, Special attention has been made on targeted nano-delivery systems. In this regard, several examples have been illustrated concerning specific natural and artificial ligands against CSCs CD biomarkers that could be decorated on various nanoparticulated drug delivery systems to enhance therapeutic index of chemotherapeutic agents or anticancer gene therapy. The outlook of CSCs biomarkers discovery and therapeutic/diagnostic applications was discussed.

The Implications and Future Perspectives of Nanomedicine for Cancer Stem Cell Targeted Therapies

Cancer stem cells (CSCs) are believed to exhibit distinctive self-renewal, proliferation, and differentiation capabilities, and thus play a significant role in various aspects of cancer. CSCs have significant impacts on the progression of tumors, drug resistance, recurrence and metastasis in different types of malignancies. Due to their primary role, most researchers have focused on developing anti-CSC therapeutic strategies, and tremendous efforts have been put to explore methods for selective eradication of these therapeutically resistant CSCs. In recent years, many reports have shown the use of CSCs-specific approaches such as ATP-binding cassette (ABC) transporters, blockade of self-renewal and survival of CSCs, CSCs surface markers targeted drugs delivery and eradication of the tumor microenvironment. Also, various therapeutic agents such as small molecule drugs, nucleic acids, and antibodies are said to destroy CSCs selectively. Targeted drug delivery holds the key to the success of most of the anti-CSCs based drugs/therapies. The convention CSCs-specific therapeutic agents, suffer from various problems. For instance, limited water solubility, small circulation time and inconsistent stability of conventional therapeutic agents have significantly limited their efficacy. Recent advancement in the drug delivery technology has demonstrated that specially designed nanocarrier-based drug delivery approaches (nanomedicine) can be useful in delivering sufficient amount of drug molecules even in the most interiors of CSCs niches and thus can overcome the limitations associated with the conventional free drug delivery methods. The nanomedicine has also been promising in designing effective therapeutic regime against pump-mediated drug resistance (ATP-driven) and reduces detrimental effects on normal stem cells. Here we focus on the biological processes regulating CSCs' drug resistance and various strategies developed so far to deal with them. We also review the various nanomedicine approaches developed so far to overcome these CSCs related issues and their future perspectives.

Silencing PPA1 inhibits human epithelial ovarian cancer metastasis by suppressing the Wnt/β-catenin signaling pathway

Inorganic pyrophosphatase (PPA1) activity is a key determinant of cellular inorganic pyrophosphate levels, and its expression is correlated with growth of several solid tumors. To investigate this relationship, we first examined PPA1 expression in human epithelial ovarian cancer (EOC) samples, and found that PPA1 was overexpressed in tumors from EOC patients. Higher PPA1 levels correlated with advanced grades, stages, and poor survival in EOC patients. Examination of PPA1 function in EOC revealed that silencing PPA1 inhibited EOC migration, epithelial-mesenchymal transition (EMT), and metastasis in vitro and in vivo. In addition, PPA1 may promote the dephosphorylation and translocation of β-catenin. These results demonstrate that silencing PPA1 inhibits EOC metastasis by suppressing the Wnt/β-catenin signaling pathway. Strategies for downregulating PPA1 may have therapeutic potential for the prevention and treatment of EOC.

Hyaluronic acid-conjugated lipoplexes for targeted delivery of siRNA in a murine metastatic lung cancer model

We have investigated the impact of hyaluronic acid (HA)-coating on the targeting capacity of siRNA lipoplexes to CD44-overexpressing tumor cells. Cellular uptake and localization of HA-lipoplexes were evaluated by flow cytometry and fluorescence microscopy and both methods showed that these lipoplexes were rapidly internalized and localized primarily within the cytoplasm. Inhibition of luciferase expression on the A549-luciferase lung cancer cell line was achieved in vitro using an anti-Luc siRNA. 81% of luciferase gene expression inhibition was obtained in vitro with HA-lipoplexes at +/- ratio 2. In vivo, in a murine A549 metastatic lung cancer model, the treatment with HA-lipoplexes carrying anti-luciferase siRNA led to a statistically significant decrease of luciferase expression as opposed to progressive increase with non-modified lipoplexes or NaCl 0.9%. The reduction of the expression of luciferase mRNA tumor of mice treated with HA-lipoplexes supported the inhibition effect due to siRNA. These results highlight the potential of HA-lipoplexes in CD44-targeting siRNA delivery.

Targeting cancer stem cells by using chimeric antigen receptor-modified T cells: a potential and curable approach for cancer treatment

Cancer stem cells (CSCs), a subpopulation of tumor cells, have self-renewal and multi-lineage differentiation abilities that play an important role in cancer initiation, maintenance, and metastasis. An accumulation of evidence indicates that CSCs can cause conventional therapy failure and cancer recurrence because of their treatment resistance and self-regeneration characteristics. Therefore, approaches that specifically and efficiently eliminate CSCs to achieve a durable clinical response are urgently needed. Currently, treatments with chimeric antigen receptor-modified T (CART) cells have shown successful clinical outcomes in patients with hematologic malignancies, and their safety and feasibility in solid tumors was confirmed. In this review, we will discuss in detail the possibility that CART cells inhibit CSCs by specifically targeting their cell surface markers, which will ultimately improve the clinical response for patients with various types of cancer. A number of viewpoints were summarized to promote the application of CSC-targeted CART cells in clinical cancer treatment. This review covers the key aspects of CSC-targeted CART cells against cancers in accordance with the premise of the model, from bench to bedside and back to bench.

Liposomal Nanoparticles Carrying anti-IL6R Antibody to the Tumour Microenvironment Inhibit Metastasis in Two Molecular Subtypes of Breast Cancer Mouse Models

Tumour microenvironment (TME) contributes significantly towards potentiating the stemness and metastasis properties of cancer cells. IL6-Stat3 is one of the important cell signaling pathways in mediating the communication between tumour and immune cells. Here, we have systematically developed a novel anti-CD44 antibody-mediated liposomal nanoparticle delivery system loaded with anti-IL6R antibody, which could specifically target the TME of CD44⁺ breast cancer cells in different mouse models for triple negative and luminal breast cancer. This nanoparticle had an enhanced and specific tumour targeting efficacy with dramatic anti-tumour metastasis effects in syngeneic BALB/c mice bearing 4T1 cells as was in the syngeneic MMTV-PyMT mice. It inhibited IL6R-Stat3 signaling and moderated the TME, characterized by the reduced expression of genes encoding Stat3, Sox2, VEGFA, MMP-9 and CD206 in the breast tissues. Furthermore, this nanoparticle reduced the subgroups of Sox2⁺ and CD206⁺ cells in the lung metastatic foci, demonstrating its inhibitory effect on the lung metastatic niche for breast cancer stem cells. Taken together, the CD44 targeted liposomal nanoparticles encapsulating anti-IL6R antibody achieved a significant effect to inhibit the metastasis of breast cancer in different molecular subtypes of breast cancer mouse models. Our results shed light on the application of nanoparticle mediated cancer immune-therapy through targeting TME.

A multifunctional silver nanocomposite for the apoptosis of cancer cells and intracellular imaging

A multifunctional silver nanoparticle based nanocomposite for specific cancer cell therapy andin situimaging.

Identification of Stem-Like Cells in Atrial Myxoma by Markers CD44, CD19, and CD45

Atrial myxoma is the most frequent tumor arising mainly in atrial septum and its origin remains uncertain. It has been reported that a subpopulation of stem-like cells are present in benign tumors and responsible for tumor initiation and maintenance. In this study, we investigated whether stem-like cells could contribute to the atrial cardiac myxoma. Immunohistology data confirmed that a population of cells bearing the surface markers CD19, CD45, and CD44 resided in a mucopolysaccharide-rich matrix of myxoma. Moreover, we isolated myxoma cells with phase-bright culture method and confirmed that myxoma derived cells express robust level of CD19, CD45, and CD44. Furthermore, the pluripotency of this population of cells also was validated by cardiomyocytes and smooth muscle cells differentiation in vitro. Our results indicate that primary cardiac myxoma may arise from mesenchymal stem cells with the ability to generate tumors with multilineage differentiation. In conclusion, this study for the first time verified that stem-like cells are present in atrial myxoma and this population of cells may have the capacity for myxoma initiation and progression.

Ligand-based targeted therapy: a novel strategy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with high morbidity and mortality worldwide. Chemotherapy is recommended to patients with intermediate or advanced stage cancer. However, the conventional chemotherapy yields low desired response rates due to multidrug resistance, fast clearance rate, nonspecific delivery, severe side effects, low drug concentration in cancer cells, and so on. Nanoparticle-mediated targeted drug delivery system can surmount the aforementioned obstacles through enhanced permeability and retention effect and active targeting as a novel approach of therapeutics for HCC in recent years. The active targeting is triggered by ligands on the delivery system, which recognize with and internalize into hepatoma cells with high specificity and efficiency. This review focuses on the latest targeted delivery systems for HCC and summarizes the ligands that can enhance the capacity of active targeting, to provide some insight into future research in nanomedicine for HCC.

A Redox-Sensitive and RAGE-Targeting Nanocarrier for Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma (HCC) is an aggressive malignancy and the second leading cause of cancer death worldwide. Most current therapeutic agents lack the tumor-targeting efficiency and result in a nonselective biodistribution in the body. In our previous study, we identified a peptide Ala-Pro-Asp-Thr-Lys-Thr-Gln (APDTKTQ) that can selectively bind to the receptor of advanced glycation end-products (RAGE), an immunoglobulin superfamily cell surface molecule overexpressed during HCC malignant progression. Here, we report the design of a mixed micelles system modified with this peptide to target HCC cells. Specifically, we modified Pluronic F68 (F68) with APDTKTQ (F68-APDTKTQ), and we conjugated d-α-tocopheryl polyethylene glycol succinate (TPGS) with poly(lactic-co-glycolic acid) (PLGA) by a disulfide linker (TPGS-S-S-PLGA). We mixed TPGS-S-S-PLGA and F68-APDTKTQ (TSP/FP) to form a micelle, followed by the loading of oridonin (ORI). The prepared micelles showed a homogeneously spherical shape without aggregation, triggered an increased cellular uptake, and induced apoptosis in more cells than did the free ORI. Taken together, these results demonstrate the potential of this APDTKTQ-modified ORI-loaded TSP/FP mixed micelle system as a promising strategy for HCC-targeting therapy.

Nanomedicine strategies for sustained, controlled, and targeted treatment of cancer stem cells of the digestive system

Cancer stem cells (CSCs) constitute a small proportion of the cancer cells that have self-renewal capacity and tumor-initiating ability. They have been identified in a variety of tumors, including tumors of the digestive system. CSCs exhibit some unique characteristics, which are responsible for cancer metastasis and recurrence. Consequently, the development of effective therapeutic strategies against CSCs plays a key role in increasing the efficacy of cancer therapy. Several potential approaches to target CSCs of the digestive system have been explored, including targeting CSC surface markers and signaling pathways, inducing the differentiation of CSCs, altering the tumor microenvironment or niche, and inhibiting ATP-driven efflux transporters. However, conventional therapies may not successfully eradicate CSCs owing to various problems, including poor solubility, stability, rapid clearance, poor cellular uptake, and unacceptable cytotoxicity. Nanomedicine strategies, which include drug, gene, targeted, and combinational delivery, could solve these problems and significantly improve the therapeutic index. This review briefly summarizes the ongoing development of strategies and nanomedicine-based therapies against CSCs of the digestive system.

Regulation of Transdifferentiation and Retrodifferentiation by Inflammatory Cytokines in Hepatocellular Carcinoma

Liver cancers are typically inflammation-associated cancers characterized by close communication between the tumor cells and the tumor environment. This supportive inflammatory environment contributes to the establishment of a pathologic niche consisting of transformed epithelial cells, tumor-educated fibroblasts, endothelial cells, and immunosuppressive immature myeloid cells. Stromal and infiltrated immune cells help determine tumor fate, but the tumor cells themselves, including cancer stem cells, also influence the surrounding cells. This bidirectional communication generates an intricate network of signals that promotes tumor growth. Cell plasticity, which includes transdifferentiation and retrodifferentiation of differentiated cells, increases tumor heterogeneity. Plasticity allows non-cancer stem cells to replenish the cancer stem cell pool, initiate tumorigenesis, and escape the effects of therapeutic agents; it also promotes tumor aggressiveness. There is increasing evidence that an inflammatory environment promotes the retrodifferentiation of tumor cells into stem or progenitor cells; this could account for the low efficacies of some chemotherapies and the high rates of cancer recurrence. Increasing our understanding of the signaling network that connects inflammation with retrodifferentiation could identify new therapeutic targets, and lead to combined therapies that are effective against highly heterogeneous tumors.

Ultrasound-guided therapeutic modulation of hepatocellular carcinoma using complementary microRNAs

Treatment options for patients with hepatocellular carcinoma (HCC) are limited, in particular in advanced and drug resistant HCC. MicroRNAs (miRNA) are non-coding small RNAs that are emerging as novel drugs for the treatment of cancer. The aim of this study was to assess treatment effects of two complementary miRNAs (sense miRNA-122, and antisense antimiR-21) encapsulated in biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA-NP), administered by an ultrasound-guided and microbubble-enhanced delivery approach in doxorubicin-resistant and non-resistant human HCC xenografts. Proliferation and invasiveness of human HCC cells after miRNA-122/antimiR-21 and doxorubicin treatment were assessed in vitro. Confocal microscopy and qRT-PCR were used to visualize and quantitate successful intracellular miRNA-loaded PLGA-NP delivery. Up and down-regulation of miRNA downstream targets and multidrug resistance proteins and extent of apoptosis were assessed in vivo in treated human HCC xenografts in mice. Compared to single miRNA therapy, combination therapy with the two complementary miRNAs resulted in significantly (P<0.05) stronger decrease in cell proliferation, invasion, and migration of HCC cells as well as higher resensitization to doxorubicin. Ultrasound-guided delivery significantly increased in vivo miRNA-loaded PLGA-NP delivery in human HCC xenografts compared to control conditions by 5-9 fold (P<0.001). miRNA-loaded PLGA-NP were internalized in HCC cells and anti-apoptotic proteins were down regulated with apoptosis in ~27% of the tumor volume of doxorubicin-resistant human HCC after a single treatment with complementary miRNAs and doxorubicin. Thus, ultrasound-guided delivery of complementary miRNAs is highly efficient in the treatment of doxorubicin- resistant and non-resistant HCC. Further development of this new treatment approach could aid in better treatment of patients with HCC.

Embryonic stem cell preconditioned microenvironment suppresses tumorigenic properties in breast cancer

Background

Microenvironment is being increasingly recognized as a critical determinant in tumor progression and metastasis. However, the appropriate regulatory mechanism to maintain the normal balance between differentiation and self-renewal of the cancer cell in microenvironment is not well known.

Methods

4T1 breast cancer cells were treated with embryonic stem (ES) cell conditioned medium which was collected from mouse ES cells. Inhibition of tumor cell growth was based on the reduction of cell proliferation and viability, and inhibition of aggressive properties of tumor cells were examined using the wound-healing and mammosphere assays. The expression of stem cell-associated genes was detected by quantitative RT-PCR.

Results

We used a real-time imaging system to investigate the effect of the mouse ES cell microenvironment on aggressive breast cancer cells in vitro and in vivo. Exposure of breast cancer cells in mouse ES cell conditioned medium resulted in inhibition of growth, migration, metastasis, and angiogenesis of cancer cells. For many tumors, aggressive properties were tightly related to Stat3 signaling activation. We specifically discovered that the ES cell microenvironment sufficiently suppressed Stat3 signaling pathway activation in aggressive tumor cells, leading to a reduction in tumorigenesis and invasiveness.

Conclusions

We identified important functions of Stat3 and their implications for antitumor effects of ES cell conditioned medium. Some factors secreted by ES cells could efficiently suppress Stat3 pathway activation in breast cancer cells, and were then involved in cancer cell growth, survival, invasion, and migration. This study may act as a platform to understand tumor cell plasticity and may offer new therapeutic strategies to inhibit breast cancer progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0360-x) contains supplementary material, which is available to authorized users.

Targeting Colorectal Cancer Stem-Like Cells with Anti-CD133 Antibody-Conjugated SN-38 Nanoparticles

Cancer stem-like cells play a key role in tumor development, and these cells are relevant to the failure of conventional chemotherapy. To achieve favorable therapy for colorectal cancer, PEG-PCL-based nanoparticles, which possess good biological compatibility, were fabricated as nanocarriers for the topoisomerase inhibitor, SN-38. For cancer stem cell therapy, CD133 (prominin-1) is a theoretical cancer stem-like cell (CSLC) marker for colorectal cancer and is a proposed therapeutic target. Cells with CD133 overexpression have demonstrated enhanced tumor-initiating ability and tumor relapse probability. To resolve the problem of chemotherapy failure, SN-38-loaded nanoparticles were conjugated with anti-CD133 antibody to target CD133-positive (CD133(+)) cells. In this study, anti-CD133 antibody-conjugated SN-38-loaded nanoparticles (CD133Ab-NPs-SN-38) efficiently bound to HCT116 cells, which overexpress CD133 glycoprotein. The cytotoxic effect of CD133Ab-NPs-SN-38 was greater than that of nontargeted nanoparticles (NPs-SN-38) in HCT116 cells. Furthermore, CD133Ab-NPs-SN-38 could target CD133(+) cells and inhibit colony formation compared with NPs-SN-38. In vivo studies in an HCT116 xenograft model revealed that CD133Ab-NPs-SN-38 suppressed tumor growth and retarded recurrence. A reduction in CD133 expression in HCT116 cells treated with CD133Ab-NPs-SN-38 was also observed in immunohistochemistry results. Therefore, this CD133-targeting nanoparticle delivery system could eliminate CD133-positive cells and is a potential cancer stem cell targeted therapy.

Zoledronic acid prevents the tumor-promoting effects of mesenchymal stem cells via MCP-1 dependent recruitment of macrophages

Zoledronic acid (ZA) has been tested in clinical trials as an additive therapy for early-stage breast cancer. However, the mechanism by which ZA exerts its antitumor activity is still unclear. The aim of this study is to investigate whether the prevention of tumor growth by ZA is through regulating the mesenchymal stem cells (MSC)-monocyte chemotactic protein 1 (MCP-1)-macrophages axis in the tumor microenvironment.

To address this issue, MDA-MB-231-FLUC human breast cancer cells were cultured and injected either alone, or coupled with MSC into the mammary fat pads of nude mice. MSC were treated with either ZA or untreated. Tumor growth was determined by using an in vivo bioluminescence imaging (BLI) and the tumor-associated macrophages (TAMs) in tumor tissues were immunohistochemically analyzed by using CD206 antibody. The effects of ZA on the cytokine related gene expression of MSC were assessed by using real-time PCR.

In this study, we found that ZA-treated mice showed a significant delay in tumor growth. In addition, our data revealed that ZA weakened the ability of MSC to promote tumor growth by impairing TAMs recruitment and tumor vascularization. Furthermore, it was found that ZA decreased MCP-1 expression of MSC, and therefore reduced the recruitment of TAMs to the tumor sites and hence inhibited the tumor growth.

Altogether, our study demonstrated ZA can prevent the tumor-promoting effects of MSC. The antitumor effects of ZA were caused by decreasing the MCP-1 expression of MSC, which further decreased the infiltration of TAMs into tumor sites, and therefore inhibited the tumor growth.

A pH-sensitive stearoyl-PEG-poly(methacryloyl sulfadimethoxine)-decorated liposome system for protein delivery: An application for bladder cancer treatment

Stealth pH-responsive liposomes for the delivery of therapeutic proteins to the bladder epithelium were prepared using methoxy-poly(ethylene glycol)5kDa-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (mPEG5kDa-DSPE) and stearoyl-poly(ethylene glycol)-poly(methacryloyl sulfadimethoxine) copolymer (stearoyl-PEG-polySDM), which possesses an apparent pKa of 7.2. Liposomes of 0.2:0.6:100, 0.5:1.5:100 and 1:3:100 mPEG5kDa-DSPE/stearoyl-PEG-polySDM/(soybean phosphatidylcholine+cholesterol) molar ratios were loaded with bovine serum albumin (BSA) as a protein model. The loading capacity was 1.3% w/w BSA/lipid. At pH7.4, all liposome formulations displayed a negative zeta-potential and were stable for several days. By pH decrease or addition to mouse urine, the zeta potential strongly decreased, and the liposomes underwent a rapid size increase and aggregation. Photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) analyses showed that the extent of the aggregation depended on the stearoyl-PEG-polySDM/lipid molar ratio. Cytofluorimetric analysis and confocal microscopy showed that at pH6.5, the incubation of MB49 mouse bladder cancer cells and macrophages with fluorescein isothiocyanate-labelled-BSA (FITC-BSA) loaded and N-(Lissamine Rhodamine B sulfonyl)-1, 2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (rhodamine-DHPE) labelled 1:3:100 mPEG5kDa-DSPE/stearoyl-PEG-polySDM/lipid molar ratio liposomes resulted in a time-dependent liposome association with the cells. At pH7.4, the association of BSA-loaded liposomes with the MB49 cells and macrophages was remarkably lower than at pH6.5. Confocal images of bladder sections revealed that 2h after the instillation, liposomes at pH7.4 and control non-responsive liposomes at pH7.4 or 6.5 did not associate nor delivered FITC-BSA to the bladder epithelium. On the contrary, the pH-responsive liposome formulation set at pH6.5 and soon administered to mice by bladder instillation showed that, 2h after administration, the pH-responsive liposomes efficiently delivered the loaded FITC-BSA to the bladder epithelium.

Modifying the tumor microenvironment using nanoparticle therapeutics

Treatment of cancer has come a long way from the initial 'radical surgeries' to the multimodality treatments. For the major part of the last century, cancer was considered as a monocellular disorder, and treatment strategies were designed according to that hypothesis. However, the mortality rate from cancer continued to be high and a comprehensive treatment remained elusive. Recent progress in research has demonstrated that tumors are a complex network of neoplastic and non-neoplastic cells. The non-neoplastic cells, which are collectively called stroma, assist in tumor survival and progression. It has been shown that disrupting the tumor-stromal balance leads to significant effects on the tumor survival, and effective treatment can be achieved by targeting one or more of the stromal components. In this review, we summarize the roles of various stromal components in promoting tumor progression, and discuss innovative nanoparticle-mediated drug targeting strategies for stromal depletion and the subsequent effects on the tumors. Perspectives and the future directions are also provided. WIREs Nanomed Nanobiotechnol 2016, 8:891-908. doi: 10.1002/wnan.1406 For further resources related to this article, please visit the WIREs website.

Gastric cancer stem cells: evidence, potential markers, and clinical implications

Gastric cancer is a significant global health problem. It is the fifth most common cancer and third leading cause of cancer-related death worldwide (Torre et al. in CA Cancer J Clin 65(2):87-108, 2015). Despite advances in treatment, overall prognosis remains poor, due to tumour relapse and metastasis. There is an urgent need for novel therapeutic approaches to improve clinical outcomes in gastric cancer. The cancer stem cell (CSC) model has been proposed to explain the high rate of relapse and subsequent resistance of cancer to current systemic treatments (Vermeulen et al. in Lancet Oncol 13(2):e83-e89, 2012). CSCs have been identified in many solid malignancies, including gastric cancer, and have significant clinical implications, as targeting the CSC population may be essential in preventing the recurrence and spread of a tumour (Dewi et al. in J Gastroenterol 46(10):1145-1157, 2011). This review seeks to summarise the current evidence for CSC in gastric cancer, with an emphasis on candidate CSC markers, clinical implications, and potential therapeutic approaches.

pH-Responsive Hyaluronic Acid-Based Mixed Micelles for the Hepatoma-Targeting Delivery of Doxorubicin

The tumor targetability and stimulus responsivity of drug delivery systems are crucial in cancer diagnosis and treatment. In this study, hepatoma-targeting mixed micelles composed of a hyaluronic acid-glycyrrhetinic acid conjugate and a hyaluronic acid-l-histidine conjugate (HA-GA/HA-His) were prepared through ultrasonic dispersion. The formation and characterization of the mixed micelles were confirmed via ¹H-NMR, particle size, and ζ potential measurements. The in vitro cellular uptake of the micelles was evaluated using human liver carcinoma (HepG2) cells. The antitumor effect of doxorubicin (DOX)-loaded micelles was investigated in vitro and in vivo. Results indicated that the DOX-loaded HA-GA/HA-His micelles showed a pH-dependent controlled release and were remarkably absorbed by HepG2 cells. Compared with free DOX, the DOX-loaded HA-GA/HA-His micelles showed a higher cytotoxicity to HepG2 cells. Moreover, the micelles effectively inhibited tumor growth in H22 cell-bearing mice. These results suggest that the HA-GA/HA-His mixed micelles are a good candidate for drug delivery in the prevention and treatment of hepatocarcinoma.

Multifunctionalized iron oxide nanoparticles for selective drug delivery to CD44-positive cancer cells

Nanomedicine nowadays offers novel solutions in cancer therapy and diagnosis by introducing multimodal treatments and imaging tools in one single formulation. Nanoparticles acting as nanocarriers change the solubility, biodistribution and efficiency of therapeutic molecules, reducing their side effects. In order to successfully  apply these novel therapeutic approaches, efforts are focused on the biological functionalization of the nanoparticles to improve the selectivity towards cancer cells. In this work, we present the synthesis and characterization of novel multifunctionalized iron oxide magnetic nanoparticles (MNPs) with antiCD44 antibody and gemcitabine derivatives, and their application for the selective treatment of CD44-positive cancer cells. The lymphocyte homing receptor CD44 is overexpressed in a large variety of cancer cells, but also in cancer stem cells (CSCs) and circulating tumor cells (CTCs). Therefore, targeting CD44-overexpressing cells is a challenging and promising anticancer strategy. Firstly, we demonstrate the targeting of antiCD44 functionalized MNPs to different CD44-positive cancer cell lines using a CD44-negative non-tumorigenic cell line as a control, and verify the specificity by ultrastructural characterization and downregulation of CD44 expression. Finally, we show the selective drug delivery potential of the MNPs by the killing of CD44-positive cancer cells using a CD44-negative non-tumorigenic cell line as a control. In conclusion, the proposed multifunctionalized MNPs represent an excellent biocompatible nanoplatform for selective CD44-positive cancer therapy in vitro.

Enhanced immunotherapy of SM5-1 in hepatocellular carcinoma by conjugating with gold nanoparticles and its in vivo bioluminescence tomographic evaluation

SM5-1 is a humanized mouse monoclonal antibody, targeting an over-expressed membrane protein of approximately 230 kDa in hepatocellular carcinoma (HCC). SM5-1 can be used for target therapy in hepatocellular carinoma due to its ability of inhibiting cell growth and inducing apoptosis. However, the tumor inhibition efficacy of SM5-1 in HCC cancer treatment remains low. In this study, we synthesized SM5-1-conjugated gold nanoparticles (Au-SM5-1 NPs) and investigated their anticancer efficacy in HCC both in vitro and in vivo. The tumor inhibition rates of Au-SM5-1 NPs for subcutaneous tumor mice were 40.10% ± 4.34%, 31.37% ± 5.12%, and 30.63% ± 4.87% on day 12, 18, and 24 post-treatment as determined by bioluminescent intensity. In addition, we investigated the antitumor efficacy of Au-SM5-1 NPs in orthotopic HCC tumor models. The results showed that the inhibition rates of Au-SM5-1 NPs can reach up to 39.64% ± 4.87% on day 31 post-treatment determined by the bioluminescent intensity of the abdomen in tumor-bearing mice. Furthermore, three-dimensional reconstruction results of the orthotopic tumor revealed that Au-SM5-1 NPs significantly inhibited tumor growth compared with SM5-1 alone. Our results suggested that the developed Au-SM5-1 NPs has great potential as an antibody-based nano-drug for HCC therapy.

Drug delivery system targeting advanced hepatocellular carcinoma: Current and future

Hepatocellular carcinoma (HCC) has a fairly high morbidity and is notoriously difficult to treat due to long latent period before detection, multidrug resistance and severe drug-related adverse effects from chemotherapy. Targeted drug delivery systems (DDS) that can selectively deliver therapeutic drugs into tumor sites have demonstrated a great potential in cancer treatment, which could be utilized to resolve the limitations of conventional chemotherapy. Numerous preclinical studies of DDS have been published, but targeted DDS for HCC has yet to be made for practical clinical use. Since rational targeted DDS design should take cancer-specific properties into consideration, we have reviewed the biological and physicochemical properties of HCC extensively to provide a comprehensive understanding on HCC, and recent DDS studies on HCC, aiming to find some potential targeted DDSs for HCC treatment and a meaningful platform for further development of HCC treatments.

FROM THE CLINICAL EDITOR

Hepatocellular carcinoma has a high incidence worldwide and is known to be multidrug resistant. Thus, intensive research is being carried out to find better chemotherapeutic agents as well as new drug delivery systems. In this article, the authors reviewed in depth the current challenges facing new drug designs and also outlined novel targeted drug delivery systems (DDS) in the fight against HCC.