Methylene diphosphonate-conjugated adriamycin liposomes: preparation, characteristics, and targeted therapy for osteosarcomas in vitro and in vivo

Phytic acid-modified manganese dioxide nanoparticles oligomer for magnetic resonance imaging and targeting therapy of osteosarcoma

Osteosarcoma is the most common malignant tumor in the skeletal system with high mortality. Phytic acid (PA) is a natural compound extracted from plant seeds, which shows certain antitumor activity and good bone targeting ability. To develop a novel theranostics for magnetic resonance imaging (MRI) and targeting therapy of osteosarcoma, we employed PA to modify manganese dioxide nanoparticles (MnO₂@PA NPs) for osteosarcoma treatment. The MnO₂ NPs oligomer was formed by PA modification with uniformed size distribution and negative zeta potential. Fourier-transform infrared spectroscopy, X-ray diffraction, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis demonstrated that PA has been successfully modified on MnO₂ NPs, and the structure of MnO₂@PA NPs is amorphous. In vitro experiments demonstrated that MnO₂@PA NPs oligomer can be efficiently internalized by tumor cell, and the internalized NPs can react with H₂O₂ under acid microenvironment to produce Mn²⁺ and O₂. In vivo experiments demonstrated that MnO₂@PA NPs oligomer can passively accumulate in tumor tissue, and the accumulated NPs can produce Mn²⁺ and O₂ for MRI and targeting therapy of osteosarcoma. In conclusion, we prepared a novel bone-targeting nano theranostics for MRI and therapy of osteosarcoma.

Targeted Delivery of Chemotherapeutic Agents for Osteosarcoma Treatment

Since osteosarcoma (OS) is an aggressive bone cancer with unknown molecular pathways of etiology and pathophysiology, improving patient survival has long been a challenge. The conventional therapy is a complex multidisciplinary management that include radiotherapy, chemotherapy which followed by surgery and then post-operative adjuvant chemotherapy. However, they have severe side effects because the majority of the medicines used have just a minor selectivity for malignant tissue. As a result, treating tumor cells specifically without damaging healthy tissue is currently a primary goal in OS therapy. The coupling of chemotherapeutic drugs with targeting ligands is a unique therapy method for OS that, by active targeting, can overcome the aforementioned hurdles. This review focuses on advances in ligands and chemotherapeutic agents employed in targeted delivery to improve the capacity of active targeting and provide some insight into future therapeutic research for OS.

Liposomes as multifaceted delivery system in the treatment of osteoporosis

Introduction: Treatment of osteoporosis with the available drug formulations is still challenging due to multiple associated limitations such as chronic treatment, off-target side effects, poor bone targeting, and low bioavailability. Adopting advanced bone-targeted drug delivery strategies like liposomes is one of the safe and effective approaches for osteoporosis treatment.Areas covered: This review summarizes the applications of liposomes in gene delivery, bone regeneration, bone-targeted delivery, and as a carrier for drug encapsulation in the treatment of osteoporosis. Details of all the supportive studies are discussed here and the bone-specific roles of the strategies like new generation liposomes in osteoporosis are elaborated. The future scope of performing in-depth research on the bone-targeted liposomes is discussed.Expert opinion: Liposomes-based bone-targeted delivery of therapeutics seems to be a promising approach for the effective treatment of osteoporosis. But till date, the tremendous in vitro and in vivo research on liposomes has failed to attain significant progress in their clinical translation. From bench to bedside success of the research an interdisciplinary collaboration between the preclinical and clinical experts engaged at different stages of liposomes development is required.

Surface engineering of nanoparticles with ligands for targeted delivery to osteosarcoma

Osteosarcoma is one of the most common malignant bone tumors which affect adolescents. Neoadjuvant chemotherapy followed by operation has become recommended for osteosarcoma treatment. Whereas, the effects of conventional chemotherapy are unsatisfactory because of multidrug resistance, fast clearance rate, nontargeted delivery, side effects and so on. Accordingly, Nanoparticle-mediated targeted drug delivery system (NTDDS) is recommended to be a novel treatment strategy for osteosarcoma. NTDDS can overcome the above obstacles by enhanced permeability and retention effect and active targeting. The active targeting of the delivery system is mainly based on ligands. In this study, we investigate and summarize the most common ligands used in the latest NTDDS for osteosarcoma. It might provide new insights into nanomedicine for osteosarcoma treatment.

Hyaluronated liposomes containing H2S-releasing doxorubicin are effective against P-glycoprotein-positive/doxorubicin-resistant osteosarcoma cells and xenografts

Doxorubicin (dox) is one of the first-line drug in osteosarcoma treatment but its effectiveness is limited by the efflux pump P-glycoprotein (Pgp) and by the onset of cardiotoxicity. We previously demonstrated that synthetic doxs conjugated with a H₂S-releasing moiety (Sdox) were less cardiotoxic and more effective than dox against Pgp-overexpressing osteosarcoma cells. In order to increase the active delivery to tumor cells, we produced hyaluronic acid (HA)-conjugated liposomes containing Sdox (HA-Lsdox), exploiting the abundance of the HA receptor CD44 in osteosarcoma. HA-Lsdox showed favorable drug-release profile and higher toxicity in vitro and in vivo than dox or the FDA-approved liposomal dox Caelyx^® against Pgp-overexpressing osteosarcoma, displaying the same cardiotoxicity profile of Caelyx^®. Differently from dox, HA-Lsdox delivered the drug within the endoplasmic reticulum (ER), inducing protein sulfhydration and ubiquitination, and activating a ER stress pro-apoptotic response mediated by CHOP. HA-Lsdox also sulfhydrated the nascent Pgp in the ER, reducing its activity. We propose HA-Lsdox as an innovative tool noteworthy to be tested in Pgp-overexpressing patients, who are frequently less responsive to standard treatments in which dox is one of the most important drugs.

Non-Viral Delivery System and Targeted Bone Disease Therapy

Skeletal systems provide support, movement, and protection to the human body. It can be affected by several life suffering bone disorders such as osteoporosis, osteoarthritis, and bone cancers. It is not an easy job to treat bone disorders because of avascular cartilage regions. Treatment with non-specific drug delivery must utilize high doses of systemic administration, which may result in toxicities in non-skeletal tissues and low therapeutic efficacy. Therefore, in order to overcome such limitations, developments in targeted delivery systems are urgently needed. Although the idea of a general targeted delivery system using bone targeting moieties like bisphosphonates, tetracycline, and calcium phosphates emerged a few decades ago, identification of carrier systems like viral and non-viral vectors is a recent approach. Viral vectors have high transfection efficiency but are limited by inducing immunogenicity and oncogenicity. Although non-viral vectors possess low transfection efficiency they are comparatively safe. A number of non-viral vectors including cationic lipids, cationic polymers, and cationic peptides have been developed and used for targeted delivery of DNA, RNA, and drugs to bone tissues or cells with successful consequences. Here we mainly discuss such various non-viral delivery systems with respect to their mechanisms and applications in the specific targeting of bone tissues or cells. Moreover, we discuss possible therapeutic agents that can be delivered against various bone related disorders.

Natural product derivative Gossypolone inhibits Musashi family of RNA-binding proteins

BACKGROUND

The Musashi (MSI) family of RNA-binding proteins is best known for the role in post-transcriptional regulation of target mRNAs. Elevated MSI1 levels in a variety of human cancer are associated with up-regulation of Notch/Wnt signaling. MSI1 binds to and negatively regulates translation of Numb and APC (adenomatous polyposis coli), negative regulators of Notch and Wnt signaling respectively.

METHODS

Previously, we have shown that the natural product (-)-gossypol as the first known small molecule inhibitor of MSI1 that down-regulates Notch/Wnt signaling and inhibits tumor xenograft growth in vivo. Using a fluorescence polarization (FP) competition assay, we identified gossypolone (Gn) with a > 20-fold increase in Ki value compared to (-)-gossypol. We validated Gn binding to MSI1 using surface plasmon resonance, nuclear magnetic resonance, and cellular thermal shift assay, and tested the effects of Gn on colon cancer cells and colon cancer DLD-1 xenografts in nude mice.

RESULTS

In colon cancer cells, Gn reduced Notch/Wnt signaling and induced apoptosis. Compared to (-)-gossypol, the same concentration of Gn is less active in all the cell assays tested. To increase Gn bioavailability, we used PEGylated liposomes in our in vivo studies. Gn-lip via tail vein injection inhibited the growth of human colon cancer DLD-1 xenografts in nude mice, as compared to the untreated control (P < 0.01, n = 10).

CONCLUSION

Our data suggest that PEGylation improved the bioavailability of Gn as well as achieved tumor-targeted delivery and controlled release of Gn, which enhanced its overall biocompatibility and drug efficacy in vivo. This provides proof of concept for the development of Gn-lip as a molecular therapy for colon cancer with MSI1/MSI2 overexpression.

Bisphosphonate conjugation for bone specific drug targeting

Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.

Bisphosphonate-Functionalized Imaging Agents, Anti-Tumor Agents and Nanocarriers for Treatment of Bone Cancer

Bone metastases result from the invasion of primary tumors to bone. Current treatment modalities include local treatments such as surgery and radiotherapy, while systemic treatments include chemotherapy and (palliative) treatment of skeletal metastases. Nevertheless, once bone metastases have been established they remain incurable leading to morbidity and mortality. Bisphosphonates are a well-established class of drugs, which are increasingly applied in the treatment of bone cancers owing to their effective inhibition of tumor cells and suppression of bone metastases. The increased understanding of the mechanism of action of bisphosphonates on bone and tumor cells has prompted the development of novel bisphosphonate-functionalized imaging and therapeutic agents. This review provides an update on the preclinical efficacy of bisphosphonate-functionalized fluorophore, anti-tumor agents and nanocarriers for the treatment of bone metastases. After an overview of the general characteristics of bisphosphonates and their mechanisms of action, an outline is provided on the various conjugation strategies that have become available to functionalize imaging agents, anti-tumor agents and nanocarriers with bisphosphonates. Finally, the efficacy of these bisphosphonate-modified agents and carriers in preclinical studies is evaluated by reviewing their potential to target tumors and inhibit tumor growth in clinically relevant animal models for the treatment of bone cancer.

Advances in Bone-targeted Drug Delivery Systems for Neoadjuvant Chemotherapy for Osteosarcoma

Targeted therapy for osteosarcoma includes organ, cell and molecular biological targeting; of these, organ targeting is the most mature. Bone-targeted drug delivery systems are used to concentrate chemotherapeutic drugs in bone tissues, thus potentially resolving the problem of reaching the desired foci and minimizing the toxicity and adverse effects of neoadjuvant chemotherapy. Some progress has been made in bone-targeted drug delivery systems for treatment of osteosarcoma; however, most are still at an experimental stage and there is a long transitional period to clinical application. Therefore, determining how to combine new, polymolecular and multi-pathway targets is an important research aspect of designing new bone-targeted drug delivery systems in future studies. The purpose of this article was to review the status of research on targeted therapy for osteosarcoma and to summarize the progress made thus far in developing bone-targeted drug delivery systems for neoadjuvant chemotherapy for osteosarcoma with the aim of providing new ideas for highly effective therapeutic protocols with low toxicity for patients with osteosarcoma.

Present Advances and Future Perspectives of Molecular Targeted Therapy for Osteosarcoma

Osteosarcoma (OS) is a bone cancer mostly occurring in pediatric population. Current treatment regime of surgery and intensive chemotherapy could cure about 60%-75% patients with primary osteosarcoma, however only 15% to 30% can be cured when pulmonary metastasis or relapse has taken place. Hence, novel precise OS-targeting therapies are being developed with the hope of addressing this issue. This review summarizes the current development of molecular mechanisms and targets for osteosarcoma. Therapies that target these mechanisms with updated information on clinical trials are also reviewed. Meanwhile, we further discuss novel therapeutic targets and OS-targeting drug delivery systems. In conclusion, a full insight in OS pathogenesis and OS-targeting strategies would help us explore novel targeted therapies for metastatic osteosarcoma.

Mitogen-activated protein kinase 7 promotes cell proliferation, migration and invasion in SOSP-M human osteosarcoma cell line

PURPOSE

Osteosarcoma (OS) is the most common primary bone tumor and has low cure rates. Our study aimed to evaluate the roles of mitogen-activated protein kinase 7 (MAPK7) in cell proliferation, migration and invasion using the SOSP-M human OS cell line as an in vitro model.

METHODS

SOSP-M cells were transfected with PCDNA3.1-MAPK7 and siRNA-MAPK7 plasmids using Lipofectamine 2000. Quantitative real-time polymerase chain reaction (RT-PCR) was performed to determine the relative expression level of MAPK7 and Western blot analysis was carried out to determine the expression level of ERK5 protein. Then MTT, scratch wound healing and Matrigel transwell assays were used to investigate the roles of MAPK7 expression in the proliferation, migration and invasion, respectively, of SOSP-M cells in vitro.

RESULTS

RT-PCR analysis showed that the expression level of MAPK7 increased significantly after transfection with PCDNA3.1-MAPK7 plasmid compared with the blank group, while it decreased significantly after transfection with siRNA-MAPK7 plasmid. Similar results for ERK5 expression were obtained by Western blot analysis. In addition, the cell proliferation rate, cell migration rate and invasive cell number in the PCDNA3.1-MAPK7 transfection group increased significantly compared with the blank group, while they decreased significantly in the siRNA-MAPK7 transfection group.

CONCLUSIONS

Our results indicate that overexpression of MAPK7 in human OS cells could promote cell proliferation, migration and invasion, whereas knockdown of MAPK7 expression had the opposite effect. All the results suggest that MAPK7 may serve as a potent target for drug development.

Mulberry-like dual-drug complicated nanocarriers assembled with apogossypolone amphiphilic starch micelles and doxorubicin hyaluronic acid nanoparticles for tumor combination and targeted therapy

A comprehensive strategy for the preparation of mulberry-like dual-drug complicated nanocarriers (MLDC NCs) with high drug loading and adjustable dual-drug ratio was developed. First, apogossypolone (ApoG2) amphiphilic starch micelles (AASt MCs) were prepared by self-assembly process, and doxorubicin (DOX) hyaluronic acid nanoparticles (DHA NPs) were prepared by DOX absorption with excess HA by electrostatic absorption. MLDC NCs were obtained by adsorption of 8-9 DHA NPs around one AASt MC via electrostatic interaction. UV-visible and fluorescence spectrophotometers were used to measure the entrapment efficiency and loading efficiency of the two drugs. Transmission electron microscope and dynamic light scattering method were used to observe the size distribution and morphology of the particles. The tumor-targeting feature caused by HA-receptor mediation was confirmed by in vitro cell uptake and in vivo near-infrared fluorescence imaging. MLDC NCs were found to possess a mulberry-like shape with a dynamic size of 83.1 ± 6.6 nm. The final encapsulation efficiencies of ApoG2 and DOX in MLDC NCs were 94 ± 1.7% and 87 ± 5.8% with respect to drug-loading capacities of 13.3 ± 1.2% and 13.1 ± 3.7%, respectively. Almost no ApoG2 release was found within 80 h and less than 30% of DOX was released into the outer phase even after 72 h. In vivo fluorescence imaging revealed that MLDC NCs had highly efficient targeting and accumulation at the tumor in vivo and was maintained for 96 h after being injected intravenously in mice. Low LD50 for the two drugs in MLDC NCs was found after acute toxicity test. One-fifth normal dosage of the two drugs in MLDC NCs exhibited significantly higher anti-tumor efficiency in reducing tumor size compared with free drugs combination or single drug-loaded nanoparticles individually, indicating that the mulberry-like dual-drug nanoplatform has a great potential in tumor therapy.

Nanomedicines in the future of pediatric therapy

Nanotechnology has become a key tool to overcome the main (bio)pharmaceutical drawbacks of drugs and to enable their passive or active targeting to specific cells and tissues. Pediatric therapies usually rely on the previous clinical experience in adults. However, there exists scientific evidence that drug pharmacokinetics and pharmacodynamics in children differ from those in adults. For example, the interaction of specific drugs with their target receptors undergoes changes over the maturation of the different organs and systems. A similar phenomenon is observed for toxicity and adverse effects. Thus, it is clear that the treatment of disease in children cannot be simplified to the direct adjustment of the dose to the body weight/surface. In this context, the implementation of innovative technologies (e.g., nanotechnology) in the pediatric population becomes extremely challenging. The present article overviews the different attempts to use nanotechnology to treat diseases in the pediatric population. Due to the relevance, though limited available literature on the matter, we initially describe from preliminary in vitro studies to preclinical and clinical trials aiming to treat pediatric infectious diseases and pediatric solid tumors by means of nanotechnology. Then, the perspectives of pediatric nanomedicine are discussed.

Hypoxia-sensitive bis(2-(2'-benzothienyl)pyridinato-N,C(3'))iridium[poly(n-butyl cyanoacrylate]/chitosan nanoparticles and their phosphorescence tumor imaging in vitro and in vivo

A new hypoxia-sensitive coordination compound, bis(2-(2'-benzothienyl)pyridinato-N,C(3'))iridium[poly(n-butyl cyanoacrylate)], hereafter denoted as (btp)2Ir(PBCA), is synthesized and characterized by (13)C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). (btp)2Ir(PBCA)/chitosan [(btp)2Ir(PBCA)/CS] nanoparticles (NPs) with a core-shell structure are prepared by a two-step fabrication process. The size distributions of these NPs are measured with a Malvern size analyzer, and their morphology is observed by transmission electron microscopy (TEM). The functional groups on the surface are confirmed by FTIR. Phosphorescence spectra are obtained and lifetimes are determined with a spectrophotofluorometer and a time-correlated single photon counting (TCSPC) apparatus, respectively. HeLa and CT26 cell lines are used to examine the cytotoxicity by the MTT assay, as well as to determine the imaging capability of the samples in air and nitrogen atmospheres, respectively. Tumor-bearing mouse models of colon adenocarcinoma are used for tumor imaging in vivo, and the imaging effect is evaluated with a Maestro 2 fluorescence imaging system. Compared with the hypoxia-associated probe bis(2-(2'-benzothienyl)pyridinato-N,C(3'))iridium(acetylacetonate) (BTP), the phosphorescence lifetime of (btp)2Ir(PBCA)/CS NPs significantly decreases, but the hypoxia-sensitivity increases after preparation of NPs. Apart from the significantly lower cytotoxicity, (btp)2Ir(PBCA)/CS NPs also enhance the tumor imaging effect by more than 10 times, maintaining the phosphorescence signal in tumor tissue for over 24 h and significantly decreasing the phosphorescence signal in normal tissue in vivo compared with the BTP probe.

Current therapeutic strategies and novel approaches in osteosarcoma

Osteosarcoma is the most frequent malignant primary bone tumor and a main cause of cancer-related death in children and adolescents. Although long-term survival in localized osteosarcoma has improved to about 60% during the 1960s and 1970s, long-term survival in both localized and metastatic osteosarcoma has stagnated in the past several decades. Thus, current conventional therapy consists of multi-agent chemotherapy, surgery and radiation, which is not fully adequate for osteosarcoma treatment. Innovative drugs and approaches are needed to further improve outcome in osteosarcoma patients. This review describes the current management of osteosarcoma as well as potential new therapies.

Bisphosphonates and cancer: what opportunities from nanotechnology?

Bisphosphonates (BPs) are synthetic analogues of naturally occurring pyrophosphate compounds. They are used in clinical practice to inhibit bone resorption in bone metastases, osteoporosis, and Paget's disease. BPs induce apoptosis because they can be metabolically incorporated into nonhydrolyzable analogues of adenosine triphosphate. In addition, the nitrogen-containing BPs (N-BPs), second-generation BPs, act by inhibiting farnesyl diphosphate (FPP) synthase, a key enzyme of the mevalonate pathway. These molecules are able to induce apoptosis of a number of cancer cells in vitro. Moreover, antiangiogenic effect of BPs has also been reported. However, despite these promising properties, BPs rapidly accumulate into the bone, thus hampering their use to treat extraskeletal tumors. Nanotechnologies can represent an opportunity to limit BP accumulation into the bone, thus increasing drug level in extraskeletal sites of the body. Thus, nanocarriers encapsulating BPs can be used to target macrophages, to reduce angiogenesis, and to directly kill cancer cell. Moreover, nanocarriers can be conjugated with BPs to specifically deliver anticancer agent to bone tumors. This paper describes, in the first part, the state-of-art on the BPs, and, in the following part, the main studies in which nanotechnologies have been proposed to investigate new indications for BPs in cancer therapy.