Research perspectives: gold nanoparticles in cancer theranostics

Harnessing the power of targeted metal nanocarriers mediated photodynamic and photothermal therapy

The treatment of cancer has become a profoundly intricate procedure. Traditional treatment methods, including chemotherapy, surgery and radiotherapy, have been utilized, while notable progress has been achieved in recent years. Among targeted therapies for cancer, folic acid (FA) conjugated metal-based nanoparticles (NP) have emerged as an innovative strategy, namely for photodynamic therapy (PDT) and photothermal therapy (PTT). These NP exploit the strong attraction between FA and folate receptors, which are excessively produced in several cancer cells, in order to enable precise administration and improved effectiveness of treatment. During PDT, metal-based NP functionalized with FA are used as photosensitizers which are activated by light, and produce reactive oxygen species that cause cancer cells to undergo apoptosis. Within the framework of PTT, these NP effectively transform light energy into concentrated heat, specifically targeting and destroying tumor cells. This review examines the fundamental mechanisms by which these NP improve the effectiveness of PDT and PTT while simultaneously presenting important findings that demonstrate the effectiveness of FA-functionalized MNP in laboratory and animal models. In addition, the paper also discusses the problems and potential directions for their clinical translation.

X-ray-Fluorescence Imaging for In Vivo Detection of Gold-Nanoparticle-Labeled Immune Cells: A GEANT4 Based Feasibility Study

The growing field of cellular therapies in regenerative medicine and oncology calls for more refined diagnostic tools that are able to investigate and monitor the function and success of said therapies. X-ray Fluorescence Imaging (XFI) can be applied for molecular imaging with nanoparticles, such as gold nanoparticles (GNPs), which can be used in immune cell tracking. We present a Monte Carlo simulation study on the sensitivity of detection and associated radiation dose estimations in an idealized setup of XFI in human-sized objects. Our findings demonstrate the practicability of XFI in human-sized objects, as immune cell tracking with a minimum detection limit of 4.4 × 105 cells or 0.86 μg gold in a cubic volume of 1.78 mm3 can be achieved. Therefore, our results show that the current technological developments form a good basis for high sensitivity XFI.

Metal Nanoparticles for Photodynamic Therapy: A Potential Treatment for Breast Cancer

Breast cancer (BC) is the most common malignant tumor in women worldwide, which seriously threatens women’s physical and mental health. In recent years, photodynamic therapy (PDT) has shown significant advantages in cancer treatment. PDT involves activating photosensitizers with appropriate wavelengths of light, producing transient levels of reactive oxygen species (ROS). Compared with free photosensitizers, the use of nanoparticles in PDT shows great advantages in terms of solubility, early degradation, and biodistribution, as well as more effective intercellular penetration and targeted cancer cell uptake. Under the current circumstances, researchers have made promising efforts to develop nanocarrier photosensitizers. Reasonably designed photosensitizer (PS) nanoparticles can be achieved through non-covalent (self-aggregation, interfacial deposition, interfacial polymerization or core-shell embedding and physical adsorption) or covalent (chemical immobilization or coupling) processes and accumulate in certain tumors through passive and/or active targeting. These PS loading methods provide chemical and physical stability to the PS payload. Among nanoparticles, metal nanoparticles have the advantages of high stability, adjustable size, optical properties, and easy surface functionalization, making them more biocompatible in biological applications. In this review, we summarize the current development and application status of photodynamic therapy for breast cancer, especially the latest developments in the application of metal nanocarriers in breast cancer PDT, and highlight some of the recent synergistic therapies, hopefully providing an accessible overview of the current knowledge that may act as a basis for new ideas or systematic evaluations of already promising results.

Review of the Mechanism of Nanocarriers and Technological Developments in the Field of Nanoparticles for Applications in Cancer Theragnostics

Cancer cannot be controlled by the usage of drugs alone, and thus, nanotechnology is an important technique that can provide the drug with an impetus to act more effectively. There is adequate availability of anticancer drugs that are classified as alkylating agents, hormones, or antimetabolites. Nanoparticle (NP) carriers increase the residence time of the drug, thereby enhancing the survival rate of the drug, which otherwise gets washed off owing to the small size of the drug particles by the excretory system. For example, for enhancing the circulation, a coating of nonfouling polymers like PEG and dextran is done. Famous drugs such as doxorubicin (DOX) are commonly encapsulated inside the nanocomposite. The various classes of nanoparticles are used to enhance drug delivery by aiding it to fight against the tumor. Targeted therapy aims to attack the cells with features common to the cancer cells while minimizing damage to the normal cell, and these therapies work in one in four ways. Some block the cancer cells from reproducing newer cells, others release toxic substances to kill the cancer cells, some stimulate the immune system to destroy the cancer cells, and some block the growth of more blood vessels around cancer cells, which starve the cells of the nutrients, which is needed for their growth. This review aims to testify the advancements nanotechnology has brought in cancer therapy, and its statements are supported with recent research findings and clinical trial results.

Endoplasmic Reticulum Stress Provocation by Different Nanoparticles: An Innovative Approach to Manage the Cancer and Other Common Diseases

A proper execution of basic cellular functions requires well-controlled homeostasis including correct protein folding. Endoplasmic reticulum (ER) implements such functions by protein reshaping and post-translational modifications. Different insults imposed on cells could lead to ER stress-mediated signaling pathways, collectively called the unfolded protein response (UPR). ER stress is also closely linked with oxidative stress, which is a common feature of diseases such as stroke, neurodegeneration, inflammation, metabolic diseases, and cancer. The level of ER stress is higher in cancer cells, indicating that such cells are already struggling to survive. Prolonged ER stress in cancer cells is like an Achilles' heel, if aggravated by different agents including nanoparticles (NPs) may be exhausted off the pro-survival features and can be easily subjected to proapoptotic mode. Different types of NPs including silver, gold, silica, graphene, etc. have been used to augment the cytotoxicity by promoting ER stress-mediated cell death. The diverse physico-chemical properties of NPs play a great role in their biomedical applications. Some special NPs have been effectively used to address different types of cancers as these particles can be used as both toxicological or therapeutic agents. Several types of NPs, and anticancer drug nano-formulations have been engineered to target tumor cells to enhance their ER stress to promote their death. Therefore, mitigating ER stress in cancer cells in favor of cell death by ER-specific NPs is extremely important in future therapeutics and understanding the underlying mechanism of how cancer cells can respond to NP induced ER stress is a good choice for the development of novel therapeutics. Thus, in depth focus on NP-mediated ER stress will be helpful to boost up developing novel pro-drug candidates for triggering pro-death pathways in different cancers.

Induction of antitumor immunity in mice by the combination of nanoparticle-based photothermolysis and anti-PD-1 checkpoint inhibition

Generation of durable tumor-specific immune response without isolation and expansion of dendritic cells or T cells ex vivo remains a challenge. In this study, we investigated the impact of nanoparticle-mediated photothermolysis in combination with checkpoint inhibition on the induction of systemic antitumor immunity. Photothermolysis based on near-infrared light-absorbing copper sulfide nanoparticles and 15-ns laser pulses combined with the immune checkpoint inhibitor anti-PD-1 antibody (αPD-1) increased tumor infiltration by antigen-presenting cells and CD8-positive T lymphocytes in the B16-OVA mouse model. Moreover, combined photothermolysis, polymeric conjugate of the Toll-like receptor 9 agonist CpG, and αPD-1 significantly prolonged mouse survival after re-inoculation of tumor cells at a distant site compared to individual treatments alone in the poorly immunogenic syngeneic ID8-ip1-Luc ovarian tumor model. Thus, photothermolysis is a promising interventional technique that synergizes with Toll-like receptor 9 agonists and immune checkpoint inhibitors to enhance the abscopal effect in tumors.

Near Infrared Fluorescence Imaging in Nano-Therapeutics and Photo-Thermal Evaluation

The unresolved and paramount challenge in bio-imaging and targeted therapy is to clearly define and demarcate the physical margins of tumor tissue. The ability to outline the healthy vital tissues to be carefully navigated with transection while an intraoperative surgery procedure is performed sets up a necessary and under-researched goal. To achieve the aforementioned objectives, there is a need to optimize design considerations in order to not only obtain an effective imaging agent but to also achieve attributes like favorable water solubility, biocompatibility, high molecular brightness, and a tissue specific targeting approach. The emergence of near infra-red fluorescence (NIRF) light for tissue scale imaging owes to the provision of highly specific images of the target organ. The special characteristics of near infra-red window such as minimal auto-fluorescence, low light scattering, and absorption of biomolecules in tissue converge to form an attractive modality for cancer imaging. Imparting molecular fluorescence as an exogenous contrast agent is the most beneficial attribute of NIRF light as a clinical imaging technology. Additionally, many such agents also display therapeutic potentials as photo-thermal agents, thus meeting the dual purpose of imaging and therapy. Here, we primarily discuss molecular imaging and therapeutic potentials of two such classes of materials, i.e., inorganic NIR dyes and metallic gold nanoparticle based materials.

Nanomedicines for renal disease: current status and future applications

Treatment and management of kidney disease currently presents an enormous global burden, and the application of nanotechnology principles to renal disease therapy, although still at an early stage, has profound transformative potential. The increasing translation of nanomedicines to the clinic, alongside research efforts in tissue regeneration and organ-on-a-chip investigations, are likely to provide novel solutions to treat kidney diseases. Our understanding of renal anatomy and of how the biological and physico-chemical properties of nanomedicines (the combination of a nanocarrier and a drug) influence their interactions with renal tissues has improved dramatically. Tailoring of nanomedicines in terms of kidney retention and binding to key membranes and cell populations associated with renal diseases is now possible and greatly enhances their localization, tolerability, and efficacy. This Review outlines nanomedicine characteristics central to improved targeting of renal cells and highlights the prospects, challenges, and opportunities of nanotechnology-mediated therapies for renal diseases.

Interventional Nanotheranostics of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for over 90% of all pancreatic cancer. Nanoparticles (NPs) offer new opportunities for image-guided therapy owing to the unique physicochemical properties of the nanoscale effect and the multifunctional capabilities of NPs. However, major obstacles exist for NP-mediated cancer theranostics, especially in PDAC. The hypovascular nature of PDAC may impede the deposition of NPs into the tumor after systemic administration, and most NPs localize predominantly in the mononuclear phagocytic system, leading to a relatively poor tumor-to-surrounding-organ uptake ratio. Image guidance combined with minimally invasive interventional procedures may help circumvent these barriers to poor drug delivery of NPs in PDAC. Interventional treatments allow regional drug delivery, targeted vascular embolization, direct tumor ablation, and the possibility of disrupting the stromal barrier of PDAC. Interventional treatments also have potentially fewer complications, faster recovery, and lower cost compared with conventional therapies. This work is an overview of current image-guided interventional cancer nanotheranostics with specific attention given to their applications for the management of PDAC.

Oligonucleotide-based theranostic nanoparticles in cancer therapy

Theranostic approaches, combining the functionality of both therapy and imaging, have shown potential in cancer nanomedicine. Oligonucleotides such as small interfering RNA and microRNA, which are powerful therapeutic agents, have been effectively employed in theranostic systems against various cancers. Nanoparticles are used to deliver oligonucleotides into tumors by passive or active targeting while protecting the oligonucleotides from nucleases in the extracellular environment. The use of quantum dots, iron oxide nanoparticles and gold nanoparticles and tagging with contrast agents, like fluorescent dyes, optical or magnetic agents and various radioisotopes, has facilitated early detection of tumors and evaluation of therapeutic efficacy. In this article, we review the advantages of theranostic applications in cancer therapy and imaging, with special attention to oligonucleotide-based therapeutics.

Knockdown of HMGB1 improves apoptosis and suppresses proliferation and invasion of glioma cells

BACKGROUND

The purposes of this study were to explore the effects of high mobility group protein box 1 (HMGB1) gene on the growth, proliferation, apoptosis, invasion, and metastasis of glioma cells, with an attempt to provide potential therapeutic targets for the treatment of glioma.

METHODS

The expressions of HMGB1 in glioma cells (U251, U-87MG and LN-18) and one control cell line (SVG p12) were detected by real time PCR and Western blotting, respectively. Then, the effects of HMGB1 on the biological behaviors of glioma cells were detected: the expression of HMGB1 in human glioma cell lines U251 and U-87MG were suppressed using RNAi technique, then the influences of HMGB1 on the viability, cycle, apoptosis, and invasion abilities of U251 and U-87MG cells were analyzed using in a Transwell invasion chamber. Also, the effects of HMGB1 on the expressions of cyclin D1, Bax, Bcl-2, and MMP 9 were detected.

RESULTS

As shown by real-time PCR and Western blotting, the expression of HMGB1 significantly increased in glioma cells (U251, U-87MG, and LN-18) in comparison with the control cell line (SVG p12); the vitality, proliferation and invasive capabilities of U251 and U-87MG cells in the HMGB1 siRNA-transfected group were significantly lower than those in the blank control group and negative control (NC) siRNA group (P<0.05) but showed no significant difference between the blank control group and NC siRNA group. The percentage of apoptotic U251 and U-87MG cells was significantly higher in the HMGB1 siRNA-transfected group than in the blank control group and NC siRNA group (P<0.05) but was similar between the latter two groups. The HMGB1 siRNA-transfected group had significantly lower expression levels of Cyclin D1, Bcl-2, and MMP-9 protein in U251 and U-87MG cells and significantly higher expression of Bax protein than in the blank control group and NC siRNA group (P<0.05); the expression profiles of cyclin D1, Bax, Bcl-2, and MMP 9 showed no significant change in both blank control group and NC siRNA group.

CONCLUSIONS

HMGB1 gene may promote the proliferation and migration of glioma cells and suppress its effects of apoptosis. Inhibition of the expression of HMGB1 gene can suppress the proliferation and migration of glioma cells and promote their apoptosis. Our observations provided a new target for intervention and treatment of glioma.

Image-guided interventional therapy for cancer with radiotherapeutic nanoparticles

One of the major limitations of current cancer therapy is the inability to deliver tumoricidal agents throughout the entire tumor mass using traditional intravenous administration. Nanoparticles carrying beta-emitting therapeutic radionuclides that are delivered using advanced image-guidance have significant potential to improve solid tumor therapy. The use of image-guidance in combination with nanoparticle carriers can improve the delivery of localized radiation to tumors. Nanoparticles labeled with certain beta-emitting radionuclides are intrinsically theranostic agents that can provide information regarding distribution and regional dosimetry within the tumor and the body. Image-guided thermal therapy results in increased uptake of intravenous nanoparticles within tumors, improving therapy. In addition, nanoparticles are ideal carriers for direct intratumoral infusion of beta-emitting radionuclides by convection enhanced delivery, permitting the delivery of localized therapeutic radiation without the requirement of the radionuclide exiting from the nanoparticle. With this approach, very high doses of radiation can be delivered to solid tumors while sparing normal organs. Recent technological developments in image-guidance, convection enhanced delivery and newly developed nanoparticles carrying beta-emitting radionuclides will be reviewed. Examples will be shown describing how this new approach has promise for the treatment of brain, head and neck, and other types of solid tumors.

Targeted therapy with MXD3 siRNA, anti-CD22 antibody and nanoparticles for precursor B-cell acute lymphoblastic leukaemia

Conventional chemotherapy for precursor B-cell (preB) acute lymphoblastic leukaemia (ALL) has limitations that could be overcome by targeted therapy. Previously, we discovered a potential therapeutic molecular target, MDX3 (MAX dimerization protein 3), in preB ALL. In this study, we hypothesize that an effective siRNA therapy for preB ALL can be developed using antiCD22 antibody (αCD22 Ab) and nanoparticles. We composed nanocomplexes with super paramagnetic iron oxide nanoparticles (SPIO NPs), αCD22 Abs and MXD3 siRNA molecules based on physical interactions between the molecules. We demonstrated that the MXD3 siRNA-αCD22 Ab-SPIO NP complexes entered leukaemia cells and knocked down MXD3, leading the cells to undergo apoptosis and resulting in decreased live cell counts in the cell line Reh and in primary preB ALL samples in vitro. Furthermore, the cytotoxic effects of the MXD3 siRNA-αCD22 Ab-SPIO NP complexes were significantly enhanced by addition of the chemotherapy drugs vincristine or doxorubicin. We also ruled out potential cytotoxic effects of the MXD3 siRNA-αCD22 Ab-SPIO NP complexes on normal primary haematopoietic cells. Normal B cells were affected while CD34-positive haematopoietic stem cells and non-B cells were not. These data suggest that MXD3 siRNA-αCD22 Ab-SPIO NP complexes have the potential to be a new targeted therapy for preB ALL.

Positron emission tomography image-guided drug delivery: current status and future perspectives

Positron emission tomography (PET) is an important modality in the field of molecular imaging, which is gradually impacting patient care by providing safe, fast, and reliable techniques that help to alter the course of patient care by revealing invasive, de facto procedures to be unnecessary or rendering them obsolete. Also, PET provides a key connection between the molecular mechanisms involved in the pathophysiology of disease and the according targeted therapies. Recently, PET imaging is also gaining ground in the field of drug delivery. Current drug delivery research is focused on developing novel drug delivery systems with emphasis on precise targeting, accurate dose delivery, and minimal toxicity in order to achieve maximum therapeutic efficacy. At the intersection between PET imaging and controlled drug delivery, interest has grown in combining both these paradigms into clinically effective formulations. PET image-guided drug delivery has great potential to revolutionize patient care by in vivo assessment of drug biodistribution and accumulation at the target site and real-time monitoring of the therapeutic outcome. The expected end point of this approach is to provide fundamental support for the optimization of innovative diagnostic and therapeutic strategies that could contribute to emerging concepts in the field of “personalized medicine”. This review focuses on the recent developments in PET image-guided drug delivery and discusses intriguing opportunities for future development. The preclinical data reported to date are quite promising, and it is evident that such strategies in cancer management hold promise for clinically translatable advances that can positively impact the overall diagnostic and therapeutic processes and result in enhanced quality of life for cancer patients.