Low intensity ultrasound promotes the sensitivity of rat brain glioma to Doxorubicin by down-regulating the expressions of p-glucoprotein and multidrug resistance protein 1 in vitro and in vivo

Potential of Natural Products in the Treatment of Glioma: Focus on Molecular Mechanisms

Despite the waning of traditional treatments for glioma due to possible long-term issues, the healing possibilities of substances derived from nature have been reignited in the scientific community. These natural substances, commonly found in fruits and vegetables, are considered potential alternatives to pharmaceuticals, as they have been shown in prior research to impact pathways surrounding cancer progression, metastases, invasion, and resistance. This review will explore the supposed molecular mechanisms of different natural components, such as berberine, curcumin, coffee, resveratrol, epigallocatechin-3-gallate, quercetin, tanshinone, silymarin, coumarin, and lycopene, concerning glioma treatment. While the benefits of a balanced diet containing these compounds are widely recognized, there is considerable scope for investigating the efficacy of these natural products in treating glioma.

Active targeted delivery of theranostic thermo/pH dual-responsive magnetic Janus nanoparticles functionalized with folic acid/fluorescein ligands for enhanced DOX combination therapy of rat glioblastoma

Doxorubicin (DOX), a chemotherapy drug, has demonstrated limited efficacy against glioblastoma, an aggressive brain tumor with resistance attributed to the blood-brain barrier (BBB). This study aims to overcome this challenge by proposing the targeted delivery of magnetic Janus nanoparticles (MJNPs) functionalized with folic acid ligands, fluorescent dye, and doxorubicin (DOX/MJNPs-FLA). The properties of these nanoparticles were comprehensively evaluated using bio-physiochemical techniques such as Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), zeta potential analysis, high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM), fluorescence microscopy, MTT assay, hemolysis assay, and liver enzyme level evaluation. Dual-controlled DOX release was investigated under different pH and temperature conditions. Additionally, the impact of DOX/MJNPs-FLA on apoptosis induction in tumor cells, body weight, and survival time of cancerous animals was assessed. The targeted delivery system was assessed using C6 and OLN-93 cell lines as representatives of cancerous and healthy cell lines, respectively, alongside Wistar rat tumor-bearing models. Results from Prussian blue staining and confocal microscopy tests demonstrated the effective targeted internalization of MJNPs-FLA by glioblastoma cells. Additionally, we investigated the biodistribution of the nanoparticles utilizing fluorescence imaging techniques. This enabled us to track the distribution pattern of MJNPs-FLA in vivo, shedding light on their movement and accumulation within the biological system. Furthermore, the combination of chemotherapy and magnetic hyperthermia exhibited enhanced efficacy in inducing apoptosis, as evidenced by the increase of the pro-apoptotic Bax gene and a decrease in the anti-apoptotic Bcl-2 gene. Remarkably, this combination treatment did not cause any hepatotoxicity. This study highlights the potential of DOX/MJNPs-FLA as carriers for therapeutic and diagnostic agents in the context of theranostic applications for the treatment of brain malignancies. Additionally, it demonstrates the promising performance of DOX/MJNPs-FLA in combination treatment through passive and active targeting.

Ultrasound-responsive microbubbles and nanodroplets: A pathway to targeted drug delivery

Ultrasound-responsive agents have shown great potential as targeted drug delivery agents, effectively augmenting cell permeability and facilitating drug absorption. This review focuses on two specific agents, microbubbles and nanodroplets, and provides a sequential overview of their drug delivery process. Particular emphasis is given to the mechanical response of the agents under ultrasound, and the subsequent physical and biological effects on the cells. Finally, the state-of-the-art in their pre-clinical and clinical implementation are discussed. Throughout the review, major challenges that need to be overcome in order to accelerate their clinical translation are highlighted.

LINC00883 Promotes Drug Resistance of Glioma Through a microRNA-136/NEK1-Dependent Mechanism

Objective

Accumulating evidence has highlighted the roles of long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) of microRNAs (miRNAs) through their binding sites in the progression of glioma. Hereby, we aim to explore the role of LINC00883 as a regulator of miR-136 and its target, NIMA-related kinase 1 (NEK1), thus, its involvement in the drug resistance of glioma cells.

Methods and Results

Mechanistic investigations by dual-luciferase reporter, RNA pull-down, and RNA-binding protein immunoprecipitation (RIP) assays indicated that LINC00883 bound to miR-136, thereby blocking miR-136-induced downregulation of NEK1. Through gain-of-function experiments in U251 cells that presented a high drug resistance, we found that ectopic expression of LINC00883 resulted in increased MRP (encoding multidrug resistance-associated protein), limited cell apoptosis, and increased proliferation. Expectedly, depleting LINC00883 yielded tumor-suppressive and anti-chemoresistance effects on U251 cells by increasing miR-136 and inhibiting NEK1. Next, drug-resistant glioma cell line SOWZ1, drug-sensitive glioma cell line SOWZ2, and drug-resistant glioma cell line SOWZ2-BCNU (SOWZ2 cultured in BCNU) were applied to validate the roles of LINC00883 in the regulation of multidrug resistance. LINC00883 knockdown suppressed the viability of SWOZ1, SWOZ2, and SWOZ2-BCNU cells.

Conclusion

In conclusion, LINC00883 knockdown reduces drug resistance in glioma. Hence, our study provides a future strategy to prevent drug resistance-induced therapeutic failure in glioma.

Advances in Biological Application of and Research on Low-Frequency Ultrasound

In recent years, the in-depth study of low-frequency sonophoresis (LFS) has greatly elucidated its biological effects in various therapeutic applications, including drug delivery, enhanced healing, thrombolytic technology, anti-inflammatory effects and tumor treatment. Specifically, numerous studies have reported its use in drug delivery and synergistic antitumor activity, indicating a new treatment direction for cancer. However, there are significant gaps in the understanding of LFS in terms of frequency and sound intensity safety; these issues are becoming increasingly important in understanding the biological effects of LFS ultrasound. This article reviews the treatment mechanism and current applications of LFS technology and discusses and summarizes its safety and application prospects.

Real-Time Passive Acoustic Mapping Using Sparse Matrix Multiplication

Passive acoustic mapping enables the spatiotemporal monitoring of cavitation with circulating microbubbles during focused ultrasound (FUS)-mediated blood-brain barrier opening. However, the computational load for processing large data sets of cavitation maps or more complex algorithms limit the visualization in real-time for treatment monitoring and adjustment. In this study, we implemented a graphical processing unit (GPU)-accelerated sparse matrix-based beamforming and time exposure acoustics in a neuronavigation-guided ultrasound system for real-time spatiotemporal monitoring of cavitation. The system performance was tested in silico through benchmarking, in vitro using nonhuman primate (NHP) and human skull specimens, and demonstrated in vivo in NHPs. We demonstrated the stability of the cavitation map for integration times longer than 62.5 [Formula: see text]. A compromise between real-time displaying and cavitation map quality obtained from beamformed RF data sets with a size of 2000 ×128 ×30 (axial [Formula: see text]) was achieved for an integration time of [Formula: see text], which required a computational time of 0.27 s (frame rate of 3.7 Hz) and could be displayed in real-time between pulses at PRF = 2 Hz. Our benchmarking tests show that the GPU sparse-matrix algorithm processed the RF data set at a computational rate of [Formula: see text]/pixel/sample, which enables adjusting the frame rate and the integration time as needed. The neuronavigation system with real-time implementation of cavitation mapping facilitated the localization of the cavitation activity and helped to identify distortions due to FUS phase aberration. The in vivo test of the method demonstrated the feasibility of GPU-accelerated sparse matrix computing in a close to a clinical condition, where focus distortions exemplify problems during treatment. These experimental conditions show the need for spatiotemporal monitoring of cavitation with real-time capability that enables the operator to correct or halt the sonication in case substantial aberrations are observed.

Biomedical and Pharmacological Uses of Fluorescein Isothiocyanate Chitosan-Based Nanocarriers

Chitosan-based nanocarriers (ChNCs) are considered suitable drug carriers due to their ability to encapsulate a variety of drugs and cross biological barriers to deliver the cargo to their target site. Fluorescein isothiocyanate-labeled chitosan-based NCs (FITC@ChNCs) are used extensively in biomedical and pharmacological applications. The main advantage of using FITC@ChNCs consists of the ability to track their fate both intra and extracellularly. This journey is strictly dependent on the physico-chemical properties of the carrier and the cell types under investigation. Other applications make use of fluorescent ChNCs in cell labeling for the detection of disorders in vivo and controlling of living cells in situ. This review describes the use of FITC@ChNCs in the various applications with a focus on understanding their usefulness in labeled drug-delivery systems.

Significance and Mechanisms of P-glycoprotein in Central Nervous System Diseases

P-glycoprotein (P-gp) is a member of ATP-Binding Cassette (ABC) transporter family. Because of its characteristic luminal surface location, high transport potency and structural specificity, Pgp is regarded as a selective gatekeeper of the Blood Brain Barrier (BBB) to prevent the entry of toxins or unwanted substances into the brain. In recent years, increasing evidence has shown that P-gp is involved in the immune inflammatory response in the Central Nervous System (CNS) disorders by regulating microglia activation, and mediating immune cell migration. Furthermore, Glucocorticoid Receptor (GR) may play a crucial role in P-gp-mediated microglia activation and immune cell migration via GR-mediated mRNA decay. In this article, we will review P-gp structure, distribution, function, regulatory mechanisms, inhibitors and effects of P-gp in the pathogenesis of several CNS diseases and will discuss the role of P-gp in microglia activation, immune cell migration and the relationship with cytokine secretion.

SIRT1 and AROS suppress doxorubicin-induced apoptosis via inhibition of GSK3β activity in neuroblastoma cells

SIRT1, the best-characterized member of the sirtuin family of deacetylases, is involved in cancer, apoptosis, inflammation, and metabolism. Active regulator of SIRT1 (AROS) was the first identified direct regulator of SIRT1. An increasing number of reports have indicated that SIRT1 plays an important role in controlling brain tumors. Here, we demonstrated that depletion of SIRT1 and AROS increases doxorubicin-mediated apoptosis in human neuroblastoma SH-SY5Y cells. Glycogen synthase kinase 3β (GSK3β) promoted doxorubicin-mediated apoptosis, but this effect was abolished by overexpression of SIRT1 and AROS. Interestingly, SIRT1 and AROS interacted with GSK3β and increased inhibitory phosphorylation of GSK3β on Ser9. Finally, we determined that AROS cooperates with SIRT1 to suppress GSK3β acetylation. Taken together, our results suggest that SIRT1 and AROS inhibit GSK3β activity and provide additional insight into drug resistance in the treatment of neuroblastoma.

The Role of Ultrasound-Driven Microbubble Dynamics in Drug Delivery: From Microbubble Fundamentals to Clinical Translation

In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size and physicochemistry of the bubble shell) that play a key role in microbubble-cell interactions and in the associated therapeutic outcome. Additionally, new techniques that may provide additional control over the treatment, such as monodisperse microbubble formulations, tunable ultrasound scanners, and cavitation detection techniques, are discussed. An in-depth understanding of the aspects presented in this work could eventually lead the way to more efficient and tailored microbubble-assisted ultrasound therapy in the future.

Feedback control of microbubble cavitation for ultrasound-mediated blood-brain barrier disruption in non-human primates under magnetic resonance guidance

Focused ultrasound (FUS) in combination with microbubbles is capable of noninvasive, site-targeted delivery of drugs through the blood-brain barrier (BBB). Although acoustic parameters are reproducible in small animals, their control remains challenging in primates due to skull heterogeneity. This study describes a 7-T magnetic resonance (MR)-guided FUS system designed for BBB disruption in non-human primates (NHP) with a robust feedback control based on passive cavitation detection (PCD). Contrast enhanced T₁-weighted MR images confirmed the BBB opening in NHP sonicated during 2 min with 500-kHz frequency, pulse length of 10 ms, and pulse repetition frequency of 5 Hz. The safe acoustic pressure range from 185 ± 22 kPa to 266 ± 4 kPa in one representative case was estimated from combining data from the acoustic beam profile with the BBB opening and hemorrhage profiles obtained from MR images. A maximum amount of MR contrast agent at focus was observed at 30 min after sonication with a relative contrast enhancement of 67% ± 15% (in comparison to that found in muscles). The feedback control based on PCD using relative spectra was shown to be robust, allowing comparisons across animals and experimental sessions. Finally, we also demonstrated that PCD can test acoustic coupling conditions, which improves the efficacy and safety of ultrasound transmission into the brain.

The reversal of MRP1 expression induced by low-frequency and low-intensity ultrasound and curcumin mediated by VEGF in brain glioma

Purpose: To explore the effect of curcumin and low-frequency and low-intensity ultrasound (LFLIU) on C6 and U87 cell, and whether LFLIU could inhibit multidrug resistance protein 1 (MRP1) by increasing the sensitivity of curcumin via vascular epithelial growth factor (VEGF)/PI3K/Akt signaling pathway targeting.

Methods: C6 and U87 cells were treated with various doses of curcumin and/or different intensities of LFLIU for 60 s. After 24 hrs, the effects of curcumin and/or LFLIU on the proliferation of C6 and U87 cells were examined. Real-time PCR and western blot analysis were used to detect the expression of VEGF and MRP1 at both mRNA and protein levels. The expression of MRP1 in C6 and U87 cells was also determined following stimulation with recombinant human VEGF and/or LY294002.

Results: Curcumin and LFLIU inhibited the proliferation of glioma cells in an intensity- or dose-dependent manner. Furthermore, survivin was significant after combined treatment compares with that of curcumin or LFLIU treatment alone. VEGF and MRP1 were highly expressed in C6 and U87 cells, curcumin and LFLIU alone or in combination could decrease the expression of both VEGF and MRP1. MRP1 expression was down-regulated following LY294002 treatment, which blocked after exposure to VEGF.

Conclusion: The synergistic effects, such as a higher inhibition rate, and lower expressions of MRP1 and VEGF, of combined curcumin and LFLIU against glioma was much better than that of a single treatment. The down-regulation of MRP1 may be related with the VEGF/PI3K/Akt pathway in glioma.

Therapeutic Effect of Cabazitaxel and Blood-Brain Barrier opening in a Patient-Derived Glioblastoma Model

Treatment of glioblastoma and other diseases in the brain is especially challenging due to the blood-brain barrier, which effectively protects the brain parenchyma. In this study we show for the first time that cabazitaxel, a semi-synthetic derivative of docetaxel can cross the blood-brain barrier and give a significant therapeutic effect in a patient-derived orthotopic model of glioblastoma. We show that the drug crosses the blood-brain barrier more effectively in the tumor than in the healthy brain due to reduced expression of p-glycoprotein efflux pumps in the vasculature of the tumor. Surprisingly, neither ultrasound-mediated blood-brain barrier opening (sonopermeation) nor drug formulation in polymeric nanoparticles could increase either accumulation of the drug in the brain or therapeutic effect. This indicates that for hydrophobic drugs, sonopermeation of the blood brain barrier might not be sufficient to achieve improved drug delivery. Nonetheless, our study shows that cabazitaxel is a promising drug for the treatment of brain tumors.

The effects of ultrasound exposure on P-glycoprotein-mediated multidrug resistance in vitro and in vivo

Background

Multidrug resistance (MDR) is often responsible for the failure of chemotherapy treatment, and current strategies for cancer MDR are not adequately satisfying as to their efficacy and safety. In this study, we sought to determine the anti-MDR effects of ultrasound (US) irradiation and its underlying mechanisms against drug-resistance.

Methods

MDR variant MCF-7/ADR cell lines and endothelial cell lines were used to determine the appropriate ultrasound intensity for in vitro experiments. MCF-7/ADR cell and HEPG2/ADM cells were used to assess the anti-MDR effect of US irradiation. Intracellular adriamycin (ADM) accumulation, Cell viability, cell proliferation and cell apoptosis were evaluated after ADM + US treatment or ADM treatment alone. MCF-7/ADR xenograft mice were used to investigate the appropriate ultrasound intensity for in vivo experiments and its effect on the long-term prognosis. Underlining mechanisms by which ultrasound exposure reversing MDR phenotype were investigated both in vitro and in vivo.

Results

Combination of ADM and 0.74 W/cm² US irradiation enhanced ADM intracellular concentration and nuclear accumulation in MCF-7/ADR and HEPG2/ADM cells, compared to those treated with ADM alone. Enhanced cellular ADM uptake and nuclei localization was associated with increased cytotoxicity of ADM to ADM-resistant cells, lower ADM-resistant cell viability and proliferative cell ratio, and higher apoptotic cell ratio. More importantly, US exposure increased the effectiveness of ADM to inhibit tumor growth in MCF-7/ADR xenograft mice. Mechanistically, US exposure promoted ADM accumulation in MDR cells mainly through down-regulation of P-glycoprotein (P-gp), which is dependent on US-induced intracellular reactive oxygen species (ROS) production. US-induced oxidative stress promoted miR-200c-3p and miR-34a-3p expression by forming miR-200c/34a/ZEB1 double-negative feedback loop. Finally, US-induced miR-200c/34a overexpression decreased P-gp expression and reversed MDR phenotype.

Conclusion

US irradiation could reverse MDR phenotype by activating ROS-ZEB1-miR200c/34a-P-gp signal pathway. Our findings offer a new and promising strategy for sensitizing cells to combat MDR and to improve the therapeutic index of chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0900-6) contains supplementary material, which is available to authorized users.

Effects of low-intensity ultrasound combined with low-dose carboplatin in an orthotopic hamster model of tongue cancer: A preclinical study

Low-intensity ultrasound (LIUS) combined with chemotherapy is an innovative modality for cancer treatment, but its effect on orthotopic carcinoma remains unknown. Our previous study revealed that LIUS enhanced the growth inhibitory effects of several chemotherapeutic drugs in nude mice with transplanted tumors. In the present study, we used 7,12-dimethylbenz(alpha)anthracene to induce orthotopic tongue carcinogenesis in hamsters. We used the first-line chemotherapy drug for tongue cancer, carboplatin (CBP) in combination with LIUS to investigate the synergistic effect. The results revealed that LIUS combined with low-dose CBP enhanced the inhibitory effects of CBP on tumor growth, prolonged survival, and did not increase the incidence of side-effects. It also enhanced the inherent DNA damage caused by CBP, suppressed the expression of the DNA repair proteins O⁶-methylguanine DNA methyltransferase (MGMT) and Chk1, and increased the expression of DNA damage-inducible protein GADD45α. Furthermore, compared with CBP alone, LIUS combined with CBP reduced the expression of cyclin D1 and cyclin B1, induced the expression of caspase-3, cleaved caspase-3, caspase-8, Bax, and Bak, and inhibited the expression of Bcl-2. Examination of clinical samples revealed that MGMT, Chk1, and Gadd45α were higher in OTSCC than in adjacent normal tissue. Hence, our results indicated that LIUS enhanced the ability of low-dose CBP to damage DNA in an orthotopic hamster model of tongue cancer, induced apoptosis, inhibited tumor growth and progression, while it did not increase the toxic side-effects of the drug, suggesting additional clinical benefits for patients treated with the combination of CBP with LIUS.

Glycosylation Changes in Brain Cancer

Protein glycosylation is a posttranslational modification that affects more than half of all known proteins. Glycans covalently bound to biomolecules modulate their functions by both direct interactions, such as the recognition of glycan structures by binding partners, and indirect mechanisms that contribute to the control of protein conformation, stability, and turnover. The focus of this Review is the discussion of aberrant glycosylation related to brain cancer. Altered sialylation and fucosylation of N- and O-glycans play a role in the development and progression of brain cancer. Additionally, aberrant O-glycan expression has been implicated in brain cancer. This Review also addresses the clinical potential and applications of aberrant glycosylation for the detection and treatment of brain cancer. The viable roles glycans may play in the development of brain cancer therapeutics are addressed as well as cancer-glycoproteomics and personalized medicine. Glycoprotein alterations are considered as a hallmark of cancer while high expression in body fluids represents an opportunity for cancer assessment.

Ultrasound-mediated delivery and distribution of polymeric nanoparticles in the normal brain parenchyma of a metastatic brain tumour model

The treatment of brain diseases is hindered by the blood-brain barrier (BBB) preventing most drugs from entering the brain. Focused ultrasound (FUS) with microbubbles can open the BBB safely and reversibly. Systemic drug injection might induce toxicity, but encapsulation into nanoparticles reduces accumulation in normal tissue. Here we used a novel platform based on poly(2-ethyl-butyl cyanoacrylate) nanoparticle-stabilized microbubbles to permeabilize the BBB in a melanoma brain metastasis model. With a dual-frequency ultrasound transducer generating FUS at 1.1 MHz and 7.8 MHz, we opened the BBB using nanoparticle-microbubbles and low-frequency FUS, and applied high-frequency FUS to generate acoustic radiation force and push nanoparticles through the extracellular matrix. Using confocal microscopy and image analysis, we quantified nanoparticle extravasation and distribution in the brain parenchyma. We also evaluated haemorrhage, as well as the expression of P-glycoprotein, a key BBB component. FUS and microbubbles distributed nanoparticles in the brain parenchyma, and the distribution depended on the extent of BBB opening. The results from acoustic radiation force were not conclusive, but in a few animals some effect could be detected. P-glycoprotein was not significantly altered immediately after sonication. In summary, FUS with our nanoparticle-stabilized microbubbles can achieve accumulation and displacement of nanoparticles in the brain parenchyma.

Macrophage migration inhibitory factor rescues mesenchymal stem cells from doxorubicin-induced senescence though the PI3K-Akt signaling pathway

Doxorubicin (DOXO), an anthracycline antibiotic, is a commonly used anticancer drug. Despite its widespread usage, the therapeutic effects of DOXO are limited by its cardiotoxicity. Mesenchymal stem cell (MSC)-based therapies have had positive outcomes in the treatment of DOXO-induced cardiac damage; however, DOXO exerts toxic effects on MSCs, decreasing the effectiveness of MSC therapy. Macrophage migration inhibitory factor (MIF) promotes MSC survival and rejuvenation, and thus is a promising candidate to protect MSCs against DOXO-induced injury. The present study revealed that DOXO induced the senescence of MSCs, resulting in decreased proliferation, viability and paracrine effects. However, pretreatment with MIF improved the proliferation rate, viability, paracrine function, telomere length and telomerase activity of MSCs. Furthermore, the results indicated that the molecular mechanism underlying the anti-senescent function of MIF involved the phosphatidylinositol 3-kinase (PI3K)-RAC-α serine/threonine-protein kinase (Akt) signaling pathway, which MIF activated. In agreement with this finding, silencing Akt was identified to abolish the anti-senescent effect of MIF. In addition, MIF decreased oxidative stress in MSCs, as revealed by the decreased production of reactive oxygen species and malondialdehyde, and the increased activity of superoxide dismutase. These results indicate that MIF can rescue MSCs from a state of DOXO-induced senescence by inhibiting oxidative stress and activating the PI3K-Akt signaling pathway. Thus, treatment with MIF may have an important therapeutic application for the rejuvenation of MSCs in patients with cancer being treated with DOXO.

Doxorubicin combined with low intensity ultrasound suppresses the growth of oral squamous cell carcinoma in culture and in xenografts

Background

Oral squamous cell carcinoma (OSCC) invades surrounding tissues by upregulating matrix metalloproteinases (MMPs) -2 and −9, which causes over-expression of the Hedgehog signaling proteins Shh and Gli-1 and degradation of the extracellular matrix, thereby creating a “highway” for tumor invasion. We explored the potential of low intensity ultrasound (LIUS) and doxorubicin (DOX) to inhibit the formation of this “highway”.

Methods

MTT assays were used to examine OSCC cell viability after exposure to LIUS and DOX. The cell morphological changes and ultrastructure were detected by scanning electron microscopy and transmission electron microscopy. Endogenous autophagy-associated proteins were analyzed by immunofluorescent staining and western blotting. Cell migration and invasion abilities were evaluated by Transwell assays. Collagen fiber changes were evaluated by Masson’s trichrome staining. Invasion-associated proteins were analyzed by immunohistochemistry and western blotting.

Results

LIUS of 1 W/cm² increased the in vitro DOX uptake into OSCC by nearly 3-fold in three different cell lines and induced transient autophagic vacuoles on the cell surface. The combination of LIUS and 0.2 μg/ml DOX inhibited tumor cell viability and invasion, promoted tumor stromal collagen deposition, and prolonged the survival of mice. This combination also down-regulated MMP-2, MMP-9, Shh and Gli-1 in tumor xenografts. Collagen fiber expression was negatively correlated with the expression of these proteins in human OSCC samples.

Conclusions

Our findings suggest that effective low dosages of DOX in combination with LIUS can inhibit cell proliferation, migration and invasion, which might be through MMP-2/9 production mediated by the Hedgehog signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0633-y) contains supplementary material, which is available to authorized users.

Effects on P-Glycoprotein Expression after Blood-Brain Barrier Disruption Using Focused Ultrasound and Microbubbles

Many blood-borne substances attempting to pass through the luminal membrane of brain endothelial cells are acted upon by a variety of metabolizing enzymes or are actively expelled back into the capillary lumen by embedded efflux transporters, such as Permeability-glycoprotein (Pgp). Overexpression of this protein has also been linked to multidrug resistance in cancer cells. Previous studies have shown that focused ultrasound (FUS), when combined with a microbubble agent, has ability to temporarily disrupt blood-brain barrier (BBBD). In this work, we investigated whether modulation of Pgp expression is part of the FUS-induced effects. We found that ultrasound can temporarily suppress Pgp expression. When BBBD was produced at 0.55 MPa, Pgp was suppressed up to 48 hours and restored by 72 hours. At 0.81 MPa, suppression can last 72 hours or longer. These findings support the idea that microbubble-enhanced FUS disrupts the functional components of the BBB through suppression of drug efflux.

Evaluation of permeability, doxorubicin delivery, and drug retention in a rat brain tumor model after ultrasound-induced blood-tumor barrier disruption

Drug delivery in brain tumors is challenging because of the presence of blood-brain barrier (BBB) and the blood-tumor barrier (BTB). Focused ultrasound (FUS) combined with microbubbles can enhance the permeability of the BTB in brain tumors, as well as disrupting the BBB in the surrounding tissue. In this study, dynamic contrast-enhanced Magnetic Resonance Imaging (DCE-MRI) was used to characterize FUS-induced permeability changes in a rat glioma model and in the normal brain and to investigate the relationship between these changes and the resulting concentration of the chemotherapy agent doxorubicin (DOX). 9L gliosarcoma cells were implanted in both hemispheres in male rats. At day 10-12 after implantation, FUS-induced BTB disruption using 690kHz ultrasound and Definity microbubbles was performed in one of the tumors and in a normal brain region in each animal. After FUS, DOX was administered at a dose of 5.67mg/kg. The resulting DOX concentration was measured via fluorometry at 1 or 24h after FUS. The transfer coefficient K_trans describing extravasation of the MRI contrast agent Gd-DTPA was significantly increased in both the sonicated tumors and in the normal brain tissue (P<0.001) between the two DCE-MRI acquisitions obtained before and after FUS, while no significant difference was found in the controls (non-sonicated tumor/normal brain tissue). DOX concentrations were also significantly larger than controls in both the sonicated tumors and in the normal tissue volumes at 1 and 24h after sonication. The DOX concentrations were significantly larger (P<0.01) in the control tumors harvested 1h after FUS than in those harvested at 24h, when the tumor concentrations were not significantly different than in the non-sonicated normal brain. In contrast, there was no significant difference in the DOX concentrations between the tumors harvested at 1 and 24h after FUS or in the concentrations measured in the brain at these time points. The transfer coefficient K_trans for Gd-DTPA and the drug concentrations showed a good linear correlation (R²=0.56). Overall, these data suggest that FUS and microbubbles can not only increase DOX delivery across the BBB and BTB, but that it is retained in the tissue at significantly enhanced levels for at least 24h. Such enhanced retention may increase the potency of this chemotherapy agent and allow for reduced systemic doses. Furthermore, MRI-based estimates of Gd-DTPA transport across these barriers might be useful to estimate local DOX concentrations in the tumor and in the surrounding normal tissue.

Localized Down-regulation of P-glycoprotein by Focused Ultrasound and Microbubbles induced Blood-Brain Barrier Disruption in Rat Brain

Multi-drug resistant efflux transporters found in Blood-Brain Barrier (BBB) acts as a functional barrier, by pumping out most of the drugs into the blood. Previous studies showed focused ultrasound (FUS) induced microbubble oscillation can disrupt the BBB by loosening the tight junctions in the brain endothelial cells; however, no study was performed to investigate its impact on the functional barrier of the BBB. In this study, the BBB in rat brains were disrupted using the MRI guided FUS and microbubbles. The immunofluorescence study evaluated the expression of the P-glycoprotein (P-gp), the most dominant multi-drug resistant protein found in the BBB. Intensity of the P-gp expression at the BBB disruption (BBBD) regions was significantly reduced (63.2 ± 18.4%) compared to the control area. The magnitude of the BBBD and the level of the P-gp down-regulation were significantly correlated. Both the immunofluorescence and histologic analysis at the BBBD regions revealed no apparent damage in the brain endothelial cells. The results demonstrate that the FUS and microbubbles can induce a localized down-regulation of P-gp expression in rat brain. The study suggests a clinically translation of this method to treat neural diseases through targeted delivery of the wide ranges of brain disorder related drugs.

Combination of Protoporphyrin IX-mediated Sonodynamic Treatment with Doxorubicin Synergistically Induced Apoptotic Cell Death of a Multidrug-Resistant Leukemia K562/DOX Cell Line

The main objective of this study was to evaluate the efficacy of administration of doxorubicin (DOX) in combination with protoporphyrin IX (PpIX)-assisted low-level therapeutic ultrasound (US) in K562/DOX cells as a potential strategy in cancer therapy. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to determine the cytotoxicity of different treatments. Apoptosis was analyzed using annexin V-PE/7-amino-actinomycin D staining. Changes in DNA fragmentation, intracellular reactive oxygen species production, cellular membrane permeability, P-glycoprotein expression and DOX uptake were analyzed with flow cytometry. Under optimal conditions, PpIX-US significantly aggravated DOX-induced K562/DOX cell death, compared with either monotherapy. Synergistic potentiation of DNA damage, generation of reactive oxygen species and P-glycoprotein inhibition were observed. Plasma membrane integrity changed slightly after US exposure, and DOX uptake was notably improved after PpIX-US exposure. The results indicate that PpIX-US could increase the susceptibility of tumors to antineoplastic drugs, suggesting a clinical potential method for sonodynamic therapy-mediated tumor chemotherapy.

Effect of low-intensity pulsed ultrasound on biocompatibility and cellular uptake of chitosan-tripolyphosphate nanoparticles

Using low molecular weight chitosan nanoparticles (CNPs) prepared by an ionic gelation method, the authors report the effect of low-intensity pulsed ultrasound (US) on cell viability and nanoparticle uptake in cultured murine preosteoblasts. Particle size and zeta potential are measured using dynamic light scattering, and cell viability is evaluated using the of [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] assay. Results show that 30 min delivery of CNPs at 0.5 mg/mL is able to prevent loss of cell viability due to either serum starvation or subsequent exposure to US (1 W/cm(2) or 2 W/cm(2), up to 1 min). Additionally, flow cytometry data suggest that there is a close association between cellular membrane integrity and the presence of CNPs when US at 2 W/cm(2) is administered.