Taxane-Grafted Metal-Oxide Nanoparticles as a New Theranostic Tool against Cancer: The Promising Example of Docetaxel-Functionalized Titanate Nanotubes on Prostate Tumors

Polymer-Based Hybrid Nanoarchitectures for Cancer Therapy Applications

Globally, cancer is affecting societies and is becoming an important cause of death. Chemotherapy can be highly effective, but it is associated with certain problems, such as undesired targeting and multidrug resistance. The other advanced therapies, such as gene therapy and peptide therapy, do not prove to be effective without a proper delivery medium. Polymer-based hybrid nanoarchitectures have enormous potential in drug delivery. The polymers used in these nanohybrids (NHs) provide them with their distinct properties and also enable the controlled release of the drugs. This review features the recent use of polymers in the preparation of different nanohybrids for cancer therapy published since 2015 in some reputed journals. The polymeric nanohybrids provide an advantage in drug delivery with the controlled and targeted delivery of a payload and the irradiation of cancer by chemotherapeutical and photodynamic therapy.

Radiation nanosensitizers in cancer therapy-From preclinical discoveries to the outcomes of early clinical trials

Improving the efficacy and spatial targeting of radiation therapy while sparing surrounding normal tissues has been a guiding principle for its use in cancer therapy. Nanotechnologies have shown considerable growth in terms of innovation and the development of new therapeutic approaches, particularly as radiosensitizers. The aim of this study was to systematically review how nanoparticles (NPs) are used to enhance the radiotherapeutic effect, including preclinical and clinical studies. Clinicaltrials.gov was used to perform the search using the following terms: radiation, cancer, and NPs. In this review, we describe the various designs of nano-radioenhancers, the rationale for using such technology, as well as their chemical and biological effects. Human trials are then discussed with an emphasis on their design and detailed clinical outcomes.

About the Influence of PEG Spacers on the Cytotoxicity of Titanate Nanotubes-Docetaxel Nanohybrids against a Prostate Cancer Cell Line

The association between chemotherapeutic drugs and metal oxide nanoparticles has sparked a rapidly growing interest in cancer nanomedicine. The elaboration of new engineered docetaxel (DTX)-nanocarriers based on titanate nanotubes (TiONts) was reported. The idea was to maintain the drug inside cancer cells and avoid multidrug resistance mechanisms, which often limit drug efficacy by decreasing their intracellular concentrations in tumor cells. HS-PEGn-COOH (PEG: polyethylene glycol, n = 3000, 5000, 10,000) was conjugated, in an organic medium by covalent linkages, on TiONts surface. This study aimed to investigate the influence of different PEG derivatives chain lengths on the TiONts colloidal stability, on the PEGn density and conformation, as well as on the DTX biological activity in a prostate cancer model (human PC-3 prostate adenocarcinoma cells). In vitro tests highlighted significant cytotoxicities of the drug after loading DTX on PEGn-modified TiONts (TiONts-PEGn-DTX). Higher grafting densities for shorter PEGylated chains were most favorable on DTX cytotoxicity by promoting both colloidal stability in biological media and cells internalization. This promising strategy involves a better understanding of nanohybrid engineering, particularly on the PEGylated chain length influence, and can thus become a potent tool in nanomedicine to fight against cancer.

Assessment of Pharmacokinetics, Toxicity, and Biodistribution of a High Dose of Titanate Nanotubes Following Intravenous Injection in Mice: A Promising Nanosystem of Medical Interest

Titanate nanotubes (TiNTs) produced by the static hydrothermal process present a promising nanosystem for nanomedicine. However, the behavior of these nanotubes in vivo is not yet clarified. In this work, for the first time, we investigated the toxicity of these materials, their pharmacokinetic profile, and their biodistribution in mice. A high dose of TiNTs (45 mg/kg) was intravenously injected in mice and monitored from 6 h to 45 days. The histological examination of organs and the analysis of liver and kidney function markers and then the inflammatory response were in agreement with a long-term innocuity of these nanomaterials. The parameters of pharmacokinetics revealed the rapid clarification of TiNTs from the bloodstream after 6 h of the intravenous injection which then mainly accumulated in the liver and spleen, and their degradation and clearance in these tissues were relatively slow (>4 weeks). Interestingly, an important property of these materials is their slow dissolution under the lysosome acid environment, rendering them biodegradable. It is noteworthy that TiNTs were directly eliminated in urine and bile ducts without obvious toxicity in mice. Altogether, all these typical in vivo tests studying the TiNT pharmacokinetics, toxicity, and biodistribution are supporting the use of these biocompatible nanomaterials in the biomedical field, especially as a nanocarrier-based drug delivery system.

Prognostic and Theranostic Applications of Positron Emission Tomography for a Personalized Approach to Metastatic Castration-Resistant Prostate Cancer

Metastatic castration-resistant prostate cancer (mCRPC) represents a condition of progressive disease in spite of androgen deprivation therapy (ADT), with a broad spectrum of manifestations ranging from no symptoms to severe debilitation due to bone or visceral metastatization. The management of mCRPC has been profoundly modified by introducing novel therapeutic tools such as antiandrogen drugs (i.e., abiraterone acetate and enzalutamide), immunotherapy through sipuleucel-T, and targeted alpha therapy (TAT). This variety of approaches calls for unmet need of biomarkers suitable for patients’ pre-treatment selection and prognostic stratification. In this scenario, imaging with positron emission computed tomography (PET/CT) presents great and still unexplored potential to detect specific molecular and metabolic signatures, some of whom, such as the prostate specific membrane antigen (PSMA), can also be exploited as therapeutic targets, thus combining diagnosis and therapy in the so-called “theranostic” approach. In this review, we performed a web-based and desktop literature research to investigate the prognostic and theranostic potential of several PET imaging probes, such as ¹⁸F-FDG, ¹⁸F-choline and ⁶⁸Ga-PSMA-11, also covering the emerging tracers still in a pre-clinical phase (e.g., PARP-inhibitors’ analogs and the radioligands binding to gastrin releasing peptide receptors/GRPR), highlighting their potential for defining personalized care pathways in mCRPC.

In vivo protein corona on nanoparticles: does the control of all material parameters orient the biological behavior?

Nanomaterials have a huge potential in research fields from nanomedicine to medical devices. However, surface modifications of nanoparticles (NPs) and thus of their physicochemical properties failed to predict their biological behavior. This requires investigating the "missing link" at the nano-bio interface. The protein corona (PC), the set of proteins binding to the NPs surface, plays a critical role in particle recognition by the innate immune system. Still, in vitro incubation offers a limited understanding of biological interactions and fails to explain the in vivo fate. To date, several reports explained the impact of PC in vitro but its applications in the clinical field have been very limited. Furthermore, PC is often considered as a biological barrier reducing the targeting efficiency of nano vehicles. But the protein binding can actually be controlled by altering PC both in vitro and in vivo. Analyzing PC in vivo could accordingly provide a deep understanding of its biological effect and speed up the transfer to clinical applications. This review demonstrates the need for clarifications on the effect of PC in vivo and the control of its behavior by changing its physicochemical properties. It unfolds the recent in vivo developments to understand mechanisms and challenges at the nano-bio interface. Finally, it reports recent advances in the in vivo PC to overcome and control the limitations of the in vitro PC by employing PC as a boosting resource to prolong the NPs half-life, to improve their formulations and thereby to increase its use for biomedical applications.

Taurine-Conjugated Mussel-Inspired Iron Oxide Nanoparticles with an Elongated Shape for Effective Delivery of Doxorubicin into the Tumor Cells

Multifunctional iron oxide magnetic nanoparticles, among them nanorods, were prepared with a mussel-inspired polydopamine (pDA) surface coating agent for cancer therapeutics. Taurine, a free sulfur-containing ß amino acid, was grafted on the pDA at the iron oxide nanoparticle surface to enhance its biocompatibility and targeted delivery action. Doxorubicin (DOX), an anticancer drug, was loaded on the prepared nanovehicles with an entrapment efficiency of 70.1%. Drug release kinetics were then analyzed using UV-vis and fluorescence spectroscopies, suggesting the pH-responsive behavior of the developed nanovehicle. The developed system was then tested on PC-3 cell lines to check its cellular response. Confocal microscopy observations and (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and Annexin V-FITC assays used to evaluate cell toxicity and apoptosis reveal a dose-dependent nature of nanorods and can overcome the side effects of using free DOX with a targeted action.

Docetaxel-loaded solid lipid nanoparticles prevent tumor growth and lung metastasis of 4T1 murine mammary carcinoma cells

BACKGROUND

Metastasis causes the most breast cancer-related deaths in women. Here, we investigated the antitumor effect of solid lipid nanoparticles (SLN-DTX) when used in the treatment of metastatic breast tumors using 4T1-bearing BALB/c mice.

RESULTS

Solid lipid nanoparticles (SLNs) were produced using the high-energy method. Compritol 888 ATO was selected as the lipid matrix, and Pluronic F127 and Span 80 as the surfactants to stabilize nanoparticle dispersion. The particles had high stability for at least 120 days. The SLNs' dispersion size was 128 nm, their polydispersity index (PDI) was 0.2, and they showed a negative zeta potential. SLNs had high docetaxel (DTX) entrapment efficiency (86%), 2% of drug loading and showed a controlled drug-release profile. The half-maximal inhibitory concentration (IC₅₀) of SLN-DTX against 4T1 cells was more than 100 times lower than that of free DTX after 24 h treatment. In the cellular uptake test, SLN-DTX was taken into the cells significantly more than free DTX. The accumulation in the G2-M phase was significantly higher in cells treated with SLN-DTX (73.7%) than in cells treated with free DTX (23.0%), which induced subsequent apoptosis. TEM analysis revealed that SLN-DTX internalization is mediated by endocytosis, and fluorescence microscopy showed DTX induced microtubule damage. In vivo studies showed that SLN-DTX compared to free docetaxel exhibited higher antitumor efficacy by reducing tumor volume (p < 0.0001) and also prevented spontaneous lung metastasis in 4T1 tumor-bearing mice. Histological studies of lungs confirmed that treatment with SLN-DTX was able to prevent tumor. IL-6 serum levels, ki-67 and BCL-2 expression were analyzed and showed a remarkably strong reduction when used in a combined treatment.

CONCLUSIONS

These results indicate that DTX-loaded SLNs may be a promising carrier to treat breast cancer and in metastasis prevention.

Titanate Nanotubes Engineered with Gold Nanoparticles and Docetaxel to Enhance Radiotherapy on Xenografted Prostate Tumors

Nanohybrids based on titanate nanotubes (TiONts) were developed to fight prostate cancer by intratumoral (IT) injection, and particular attention was paid to their step-by-step synthesis. TiONts were synthesized by a hydrothermal process. To develop the custom-engineered nanohybrids, the surface of TiONts was coated beforehand with a siloxane (APTES), and coupled with both dithiolated diethylenetriaminepentaacetic acid-modified gold nanoparticles (Au@DTDTPA NPs) and a heterobifunctional polymer (PEG₃₀₀₀) to significantly improve suspension stability and biocompatibility of TiONts for targeted biomedical applications. The pre-functionalized surface of this scaffold had reactive sites to graft therapeutic agents, such as docetaxel (DTX). This novel combination, aimed at retaining the AuNPs inside the tumor via TiONts, was able to enhance the radiation effect. Nanohybrids have been extensively characterized and were detectable by SPECT/CT imaging through grafted Au@DTDTPA NPs, radiolabeled with ¹¹¹In. In vitro results showed that TiONts-AuNPs-PEG₃₀₀₀-DTX had a substantial cytotoxic activity on human PC-3 prostate adenocarcinoma cells, unlike initial nanohybrids without DTX (Au@DTDTPA NPs and TiONts-AuNPs-PEG₃₀₀₀). Biodistribution studies demonstrated that these novel nanocarriers, consisting of AuNP- and DTX-grafted TiONts, were retained within the tumor for at least 20 days on mice PC-3 xenografted tumors after IT injection, delaying tumor growth upon irradiation.

Antitumor activity of a hydrogel loaded with lipophilic bismuth nanoparticles on cervical, prostate, and colon human cancer cells

The objective of this study was to analyze the antitumor activity of a hydrogel loaded with lipophilic bismuth nanoparticles on human cervical, prostate, and colon cancer cell lines. The effect of lipophilic bismuth nanoparticles on the viability of cancer cell lines (HeLa, DU145, and HCT-116) and non-cancer lung fibroblasts (HLF; LL 47[MaDo]) was determined with the MTT cell viability assay and compared with known antineoplastic drugs. The biocompatibility at an organismal level was verified in a murine model by histological examination. A lipophilic bismuth nanoparticle hydrogel at 50 µM time-dependently inhibited the growth of the three cancer cell lines, in a time-dependent way. A 1-hour exposure to 250 µM lipophilic bismuth nanoparticle hydrogel, inhibited the growth of the three cancer cell lines. The in-vitro efficacy of lipophilic bismuth nanoparticle was similar to the one of docetaxel and cisplatin, but without inhibiting the growth of non-cancer control cells. Histology confirmed the biocompatibility of lipophilic bismuth nanoparticles as there were no signs of cytotoxicity or tissue damage in any of the evaluated organs (kidney, liver, brain, cerebellum, heart, and jejunum). In conclusion, a lipophilic bismuth nanoparticle hydrogel is an innovative, low-cost alternative for the topical treatment of cervicouterine, prostate, and colon human cancers.

Polydopamine Modified Superparamagnetic Iron Oxide Nanoparticles as Multifunctional Nanocarrier for Targeted Prostate Cancer Treatment

Polydopamine (pDA)-modified iron oxide core-shell nanoparticles (IONPs) are developed and designed as nanovectors of drugs. Reactive quinone of pDA enhances the binding efficiency of various biomolecules for targeted delivery. Glutathione disulfide (GSSG), an abundant thiol species in the cytoplasm, was immobilized on the pDA-IONP surface. It serves as a cellular trigger to release the drug from the nanoparticles providing an efficient platform for the drug delivery system. Additionally, GSSG on the surface was further modified to form S-nitrosoglutathione that can act as nitric oxide (NO) donors. These NPs were fully characterized using a transmission electronic microscopy (TEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), zeta potential, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopies. Doxorubicin (DOX) and docetaxel (DTX) are two anticancer drugs, which were loaded onto nanoparticles with respective loading efficiencies of 243 and 223 µmol/g of IONPs, calculated using TGA measurements. DOX release study, using UV-vis spectroscopy, showed a pH responsive behavior, making the elaborated nanocarrier a potential drug delivery system. (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl) -2H-tetrazolium (MTS) and apoptosis assays were performed on PC3 cell lines to evaluate the efficiency of the developed nanocarriers. These nanoparticles thus can prove their worth in cancer treatment on account of their easy access to the site and release of drug in response to changes to internal parameters such as pH, chemicals, etc.

Current Trends in Cancer Nanotheranostics: Metallic, Polymeric, and Lipid-Based Systems

Theranostics has emerged in recent years to provide an efficient and safer alternative in cancer management. This review presents an updated description of nanotheranostic formulations under development for skin cancer (including melanoma), head and neck, thyroid, breast, gynecologic, prostate, and colon cancers, brain-related cancer, and hepatocellular carcinoma. With this focus, we appraised the clinical advantages and drawbacks of metallic, polymeric, and lipid-based nanosystems, such as low invasiveness, low toxicity to the surrounding healthy tissues, high precision, deeper tissue penetration, and dosage adjustment in a real-time setting. Particularly recognizing the increased complexity and multimodality in this area, multifunctional hybrid nanoparticles, comprising different nanomaterials and functionalized with targeting moieties and/or anticancer drugs, present the best characteristics for theranostics. Several examples, focusing on their design, composition, imaging and treatment modalities, and in vitro and in vivo characterization, are detailed herein. Briefly, all studies followed a common trend in the design of these theranostics modalities, such as the use of materials and/or drugs that share both inherent imaging (e.g., contrast agents) and therapeutic properties (e.g., heating or production reactive oxygen species). This rationale allows one to apparently overcome the heterogeneity, complexity, and harsh conditions of tumor microenvironments, leading to the development of successful targeted therapies.

In vitro interaction and biocompatibility of titanate nanotubes with microglial cells

Titanate nanotubes (TiONts) are promising agents for biomedical applications. Microglial activation and associated oxidative burst are major challenges in drug delivery applications across the brain. Here, TiONts were designed for drug delivery systems by functionalizing them with (3-aminopropyl) triethoxysilane (APTES), their interactions and biocompatibility were studied in vitro using murine microglial BV-2 cells. TiONts-APTES exposure resulted in increased ROS production and transient mitochondrial hyperpolarization. However, there was no indication of microglial proliferation in BV-2 cells as suggested by cell cycle analysis and morphology evaluation. The endocytosis as well as passive diffusion mediated TiONts-APTES internalization were proved by transmission electron microscopy (TEM) with and without amiloride, an endocytosis inhibiting agent. In addition, the TiONts-APTES exhibited good biocompatibility on microglial BV-2 cells as revealed by the plasma membrane integrity, lysosmal membrane integrity, morphology and viability analysis.

Docetaxel-titanate nanotubes enhance radiosensitivity in an androgen-independent prostate cancer model

Around 40% of high-risk prostate cancer patients who undergo radiotherapy (RT) will experience biochemical failure. Chemotherapy, such as docetaxel (DTX), can enhance the efficacy of RT. Multidrug resistance mechanisms often limit drug efficacy by decreasing intracellular concentrations of drugs in tumor cells. It is, therefore, of interest to develop nanocarriers of DTX to maintain the drug inside cancer cells and thus improve treatment efficacy. The purpose of this study was to investigate the use of titanate nanotubes (TiONts) to develop a TiONts-DTX nanocarrier and to evaluate its radiosensitizing in vivo efficacy in a prostate cancer model. In vitro cytotoxic activity of TiONts-DTX was evaluated using an MTS assay. The biodistribution of TiONts-DTX was analyzed in vivo by single-photon emission computed tomography. The benefit of TiONts-DTX associated with RT was evaluated in vivo. Eight groups with seven mice in each were used to evaluate the efficacy of the nanohybrid combined with RT: control with buffer IT injection ± RT, free DXL ± RT, TiONts ± RT and TiONts-DXL ± RT. Mouse behavior, health status and tumor volume were monitored twice a week until the tumor volume reached a maximum of 2,000 mm³. More than 70% of nanohybrids were localized inside the tumor 96 h after administration. Tumor growth was significantly slowed by TiONts-DTX associated with RT, compared with free DTX in the same conditions (P=0.013). These results suggest that TiONts-DTX improved RT efficacy and might enhance local control in high-risk localized prostate cancer.

Carbon nanomaterials sensitize prostate cancer cells to docetaxel and mitomycin C via induction of apoptosis and inhibition of proliferation

We have previously shown that carbon nanofibers (CNFs) and carbon nanotubes (CNTs) can sensitize prostate cancer (PCa) cells to platinum-based chemotherapeutics. In order to further verify this concept and to avoid a bias, the present study investigates the chemosensitizing potential of CNFs and CNTs to the conventional chemotherapeutics docetaxel (DTX) and mitomycin C (MMC), which have different molecular structures and mechanisms of action than platinum-based chemotherapeutics. DU-145 PCa cells were treated with DTX and MMC alone or in combination with the carbon nanomaterials. The impact of the monotreatments and the combinatory treatments on cellular function was then systematically analyzed by using different experimental approaches (viability, short-term and long-term proliferation, cell death rate). DTX and MMC alone reduced the viability of PCa cells to 94% and 68%, respectively, whereas a combined treatment with CNFs led to less than 30% remaining viable cells. Up to 17- and 7-fold higher DTX and MMC concentrations were needed in order to evoke a similar inhibition of viability as mediated by the combinatory treatments. In contrast, the dose of platinum-based chemotherapeutics could only be reduced by up to 3-fold by combination with carbon nanomaterials. Furthermore, combinatory treatments with CNFs led mostly to an additive inhibition of short- and long-term proliferation compared to the individual treatments. Also, higher cell death rates were observed in combinatory treatments than in monotreatments, e.g., a combination of MMC and CNFs more than doubled the cell death rate mediated by apoptosis. Combinations with CNTs showed a similar, but less pronounced impact on cellular functions. In summary, carbon nanomaterials in combination with DTX and MMC evoked additive to partly synergistic anti-tumor effects. CNFs and CNTs possess the ability to sensitize cancer cells to a wide range of structurally diverse chemotherapeutics and thus represent an interesting option for the development of multimodal cancer therapies. Co-administration of chemotherapeutics with carbon nanomaterials could result in a reduction of the chemotherapeutic dosage and thus limit systemic side effects.

Synthesis and characterization of chitosan-coated titanate nanotubes: towards a new safe nanocarrier

Chitosan-coated titanate nanotubes as promising new nanocarriers: two different approaches, two different behaviors.