Enhanced sonodynamic antitumor effect of ultrasound in the presence of nonsteroidal anti-inflammatory drugs

Nanotechnology-enabled sonodynamic therapy against malignant tumors

Sonodynamic therapy (SDT) is an emerging approach for malignant tumor treatment, offering high precision, deep tissue penetration, and minimal side effects. The rapid advancements in nanotechnology, particularly in cancer treatment, have enhanced the efficacy and targeting specificity of SDT. Combining sonodynamic therapy with nanotechnology offers a promising direction for future cancer treatments. In this review, we first systematically discussed the anti-tumor mechanism of SDT and then summarized the common nanotechnology-related sonosensitizers and their recent applications. Subsequently, nanotechnology-related therapies derived using the SDT mechanism were elaborated. Finally, the role of nanomaterials in SDT combined therapy was also introduced.

Curcuminoid Chalcones: Synthesis, Stability, and New Neuroprotective and Sonosensitising Activities

The primary purpose of this work was to design and obtain a series of curcuminoid chalcone-NSAID hybrid derivatives. The ester-type hybrid compounds with ibuprofen (i), ketoprofen (ii), and naproxen (iii) were obtained in two ways, using the Claisen-Schmidt reaction and the Steglich esterification reaction. The designed molecules were successfully synthesised, and FT-IR, MS, and NMR spectroscopy confirmed their structures. Moreover, the cytotoxic effect of the sonodynamic therapy and the anti-inflammatory, antioxidant, and anticholinergic properties of some curcuminoid chalcones and curcuminoid chalcones hybrids were evaluated. The curcuminoid chalcone derivatives showed promising neuroprotective activity as sonosensitisers for sonodynamic therapy in the studied cell lines. Additionally, the stability of the ester-type hybrid compounds with promising activity was determined. The RP-HPLC method was used to observe the degradation of the tested compounds. Studies have shown that structural isomers of ester-type hybrid compounds (3ai, 3bi) are characterised by a similar susceptibility to degradation factors, i.e., they are extremely unstable in alkaline environments, very unstable in acidic environments, unstable in neutral environments, practically stable in oxidising environments, and photolabile in solutions and in the solid phase. These compounds maintain adequate stability in environment at pH 1.2 and 6.8, which may make them good candidates for developing formulations for oral administration.

Recent Clinical and Preclinical Advances in External Stimuli-Responsive Therapies for Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) has long been one of the most prevalent cancers worldwide; even though treatments such as surgery, chemotherapy, radiotherapy and immunotherapy have been proven to benefit the patients and prolong their survival time, the overall five-year survival rate is still below 50%. Hence, the development of new therapies for better patient management is an urgent need. External stimuli-responsive therapies are emerging therapies with promising antitumor effects; therapies such as photodynamic (PDT) and photothermal therapies (PTT) have been tested clinically in late-stage HNSCC patients and have achieved promising outcomes, while the clinical translation of sonodynamic therapy (SDT), radiodynamic therapy (RDT), microwave dynamic/thermodynamic therapy, and magnetothermal/magnetodynamic therapy (MDT/MTT) still lag behind. In terms of preclinical studies, PDT and PTT are also the most extensively studied therapies. The designing of nanoparticles and combinatorial therapies of PDT and PTT can be referenced in designing other stimuli-responsive therapies in order to achieve better antitumor effects as well as less toxicity. In this review, we consolidate the advancements and limitations of various external stimuli-responsive therapies, as well as critically discuss the prospects of this type of therapies in HNSCC treatments.

Current status and future perspective of sonodynamic therapy for cancer

There is a tremendous need for prevention and effective treatment of cancer due to the associated morbidity and mortality. In this study, we introduce sonodynamic therapy (SDT), which is expected to be a new cancer treatment modality. SDT is a promising option for minimally invasive treatment of solid tumors and comprises three different components: sonosensitizers, ultrasound, and molecular oxygen. These components are harmless individually, but in combination they generate cytotoxic reactive oxygen species (ROS). We will explore the molecular mechanism by which SDT kills cancer cells, the class of sonosensitizers, drug delivery methods, and in vitro and in vivo studies. At the same time, we will highlight clinical applications for cancer treatment. The progress of SDT research suggests that it has the potential to become an advanced field of cancer treatment in clinical application. In this article, we will focus on the mechanism of action of SDT and its application to cancer treatment, and explain key factors to aid in developing strategies for future SDT development.

The promising interplay between sonodynamic therapy and nanomedicine

Sonodynamic therapy (SDT) is a non-invasive approach for cancer treatment in which chemical compounds, named sonosensitizers, are activated by non-thermal ultrasound (US), able to deeply penetrate into the tissues. Despite increasing interest, the underlying mechanisms by which US triggers the sonosensitizer therapeutic activity are not yet clearly elucidate, slowing down SDT clinical application. In this review we will discuss the main mechanisms involved in SDT with particular attention to the sonosensitizers involved for each described mechanism, in order to highlight how much important are the physicochemical properties of the sonosensitizers and their cellular localization to predict their bioeffects. Moreover, we will also focus our attention on the pivotal role of nanomedicine providing the sonodynamic anticancer approach with the ability to shape US-responsive agents to enhance specific sonodynamic effects as the sonoluminescence-mediated anticancer effects. Indeed, SDT is one of the biomedical fields that has significantly improved in recent years due to the increased knowledge of nanosized materials. The shift of the nanosystem from a delivery system for a therapeutic agent to a therapeutic agent in itself represents a real breakthrough in the development of SDT. In doing so, we have also highlighted potential areas in this field, where substantial improvements may provide a valid SDT implementation as a cancer therapy.

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

As a novel noninvasive therapeutic modality combining low-intensity ultrasound and sonosensitizers, sonodynamic therapy (SDT) is promising for clinical translation due to its high tissue-penetrating capability to treat deeper lesions intractable by photodynamic therapy (PDT), which suffers from the major limitation of low tissue penetration depth of light. The effectiveness and feasibility of SDT are regarded to rely on not only the development of stable and flexible SDT apparatus, but also the screening of sonosensitizers with good specificity and safety. To give an outlook of the development of SDT equipment, the key technologies are discussed according to five aspects including ultrasonic dose settings, sonosensitizer screening, tumor positioning, temperature monitoring, and reactive oxygen species (ROS) detection. In addition, some state-of-the-art SDT multifunctional equipment integrating diagnosis and treatment for accurate SDT are introduced. Further, an overview of the development of sonosensitizers is provided from small molecular sensitizers to nano/microenhanced sensitizers. Several types of nanomaterial-augmented SDT are in discussion, including porphyrin-based nanomaterials, porphyrin-like nanomaterials, inorganic nanomaterials, and organic-inorganic hybrid nanomaterials with different strategies to improve SDT therapeutic efficacy. There is no doubt that the rapid development and clinical translation of sonodynamic therapy will be promoted by advanced equipment, smart nanomaterial-based sonosensitizer, and multidisciplinary collaboration.

Contemporary directions of application of low power ultrasounds in anticancer therapy

In the recent years, research has been conducted on the role of ultrasounds (US) in anticancer therapy. Although the mechanisms of impact on cancer cells have not yet been fully understood, it is known that the best results are obtained using low power ultrasound. Currently applying ultrasounds to organisms is considered in three areas of influence: thermal (thermic effect), cavitation (cavitation effect), other than thermal and cavitation ones (non-thermal, non-cavitation effect). Under the influence of ultrasonic wave with low power, the absorption of drugs is increased as well as of anti-angiogenic activity. Sonodynamic therapy is aimed at destroying dividing cancer cells through the formation of free radicals in the cavitation mechanism and in the presence of sonosensitizers. At the same time under the influence of US, local hyperthermia is generated. In vivo studies showed a synergistic increase in cytotoxicity due to the effects of ultrasonic hyperthermia and adriamycin. The thermal effect and inertial cavitation are described as two factors induced by US, which may lead to damage to the vascular network within the neoplastic lesion. A proportional increase in tumor echogenicity to the frequency range of the applied ultrasound wave has been demonstrated. The strategy of combining US with photosensitizers, chemotherapeutics or contrast agents is gaining more and more recognition. Obtained results from inter developed studies on antineoplastic sonodynamic therapy indicate that it may become a new additional cancer treatment strategy.

Direct Evidence of Multibubble Sonoluminescence Using Therapeutic Ultrasound and Microbubbles

The intense conditions generated in the core of a collapsing bubble have been the subject of intense scrutiny from fields as diverse as marine biology and nuclear fusion. In particular, the phenomenon of sonoluminescence, whereby a collapsing bubble emits light, has received significant attention. Sonoluminescence has been associated predominantly with millimeter-sized bubbles excited at low frequencies and under conditions far removed from those associated with the use of ultrasound in medicine. In this study, however, we demonstrate that sonoluminescence is produced under medically relevant exposure conditions by microbubbles commonly used as contrast agents for ultrasound imaging. This provides a mechanistic explanation for the somewhat controversial reports of "sonodynamic" therapy, in which light-sensitive drugs have been shown to be activated by ultrasound-induced cavitation. To illustrate this, we demonstrate the activation of a photodynamic therapy agent using microbubbles and ultrasound. Since ultrasound can be accurately focused at large tissue depths, this opens up the potential for generating light at locations that cannot be reached by external sources. This could be exploited both for diagnostic and therapeutic applications, significantly increasing the range of applications that are currently restricted by the limited penetration of light in the tissue.

Antiproliferative and Apoptosis-inducing Effect of exo-Protoporphyrin IX based Sonodynamic Therapy on Human Oral Squamous Cell Carcinoma

Sonodynamic therapy (SDT) is an innovative modality for cancer treatment. But the biological effect of SDT on oral squamous cell carcinoma has not been studied. Our previous study has shown that endo-Protoporphyrin IX based SDT (ALA-SDT) could induce apoptosis in human tongue squamous carcinoma SAS cells through mitochondrial pathway. Herein, we investigated the effect of exo- Protoporphyrin based SDT (PpIX-SDT) on SAS cells in vitro and in vivo. We demonstrated that PpIX-SDT increased the ratio of cells in the G₂/M phase and induced 3–4 times more cell apoptosis compared to sonocation alone. PpIX-SDT caused cell membrane damage prior to mitochondria damage and upregulated the expression of Fas and Fas L, while the effect was suppressed if cells were pre-treated with p53 inhibitor. Additionally, we examined the SDT-induced cell apoptosis in two cell lines with different p53 status. The increases of p53 expression and apoptosis rate in wild-type p53 SAS cells were found in the SDT group, while p53-mutated HSC-3 cells did not show such increase. Our data suggest that PpIX-SDT suppress the proliferation of SAS cells via arresting cell cycle at G₂/M phase and activating the extrinsic Fas-mediated membrane receptor pathway to induce apoptosis, which is regulated by p53.

Recent advances of sonodynamic therapy in cancer treatment

Sonodynamic therapy (SDT) is an emerging approach that involves a combination of low-intensity ultrasound and specialized chemical agents known as sonosensitizers. Ultrasound can penetrate deeply into tissues and can be focused into a small region of a tumor to activate a sonosensitizer which offers the possibility of non-invasively eradicating solid tumors in a site-directed manner. In this article, we critically reviewed the currently accepted mechanisms of sonodynamic action and summarized the classification of sonosensitizers. At the same time, the breath of evidence from SDT-based studies suggests that SDT is promising for cancer treatment.

Spectroscopic investigation on protein damage by ciprofloxacin under ultrasonic irradiation

In recent years, sonodynamic activities of many drugs have attracted more and more attention of researchers. The correlative study will promote the development of sonodynamic therapy (SDT) in anti-tumor treatment. In this work, bovine serum albumin (BSA) was used as a protein model to investigate the intensifying effects of ciprofloxacin (CPFX) ultrasonically induced protein damage by UV-vis and fluorescence spectra. Meanwhile, the conformation of BSA is changed upon the addition of CPFX and metal ions under ultrasound (US) so that the damaging site of BSA is considered. Various influencing factors, such as US irradiation time, metal ions, solution temperature and ionic strength, on the ultrasonically induced BSA damage are discussed. It was showed that CPFX could enhance ultrasonically induced BSA damage. The damage degree of BSA was aggravated with the increasing of US irradiation time, solution temperature, ionic strength as well as the addition of metal ions. Furthermore, the reactive oxygen species (ROS) in reaction system were detected by oxidation-extraction photometry (OEP). Experimental results also showed that US could activate CPFX to produce ROS, which were mainly determined as superoxide radical anion (.O2-) and hydroxyl radical (.OH).

Investigation on damage of BSA molecules under irradiation of low frequency ultrasound in the presence of FeIII-tartrate complexes

The interaction between bovine serum albumin (BSA) and Fe(III)-tartrate complexes ([Fe(III)(tar)(H(2)O)(3)](-) and [Fe(III)(tar)(2)](5-)) as well as the damage of BSA in the presence of Fe(III)-tartrate complexes under ultrasonic irradiation was studied by UV-vis and fluorescence spectra. In addition, the influences of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, ionic strength and solution acidity (pH value) were also examined on the damage of BSA. The results showed that the fluorescence quenching of BSA caused by the Fe(III)-tartrate complexes belonged to the static quenching. The BSA and Fe(III)-tartrate complexes interacted with each other mainly through weak interaction and coordinate actions. The corresponding binding association constants (K) and the binding site numbers (n) were calculated. The results were as follows: K(1)=1.67 x 10(3) L mol(-1) and n(1)=0.9699 for [Fe(III)(tar)(H(2)O)(3)](-), K(2)=1.54 x 10(3) L mol(-1) and n(2)=0.8754 for [Fe(III)(tar)(2)](5-). Otherwise, under ultrasonic irradiation the BSA molecules were obviously damaged by the Fe(III)-tartrate complexes. The damage degree rose up with the increase of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, pH value and ionic strength. And that, [Fe(III)(tar)(H(2)O)(3)](-) exhibited higher sonocatalytic activity in a way than [Fe(III)(tar)(2)](5-).

Ultrasound exposure in the presence of hematoporphyrin induced loss of membrane integral proteins and inactivity of cell proliferation associated enzymes in sarcoma 180 cells in vitro

Ultrasonically induced effects of hematoporphyrin (HPD) on cell damage and membrane protein alteration of S180 isolated tumor cells in vitro were investigated, and the potential mechanisms of sonodynamic therapy (SDT) inhibiting tumor growth were discussed. Tumor cells suspended in air-saturated PBS (pH 7.2) were exposed to ultrasound at 1.8 MHz for up to 180s in the presence and absence of HPD. The viability of cells was determined by a trypan blue exclusion test. To estimate the damage effects of SDT on plasma membrane of tumor cells primarily, membrane integral proteins (EGFR, Ras, Fas, FasL) and cell proliferation associated enzymes (adenylate cyclase and guanylate cyclase) were checked with immunochemical methods. The results indicated that the intensity threshold for ultrasonically induced cell damage at 1.8 MHz was 3 W/cm2. At this condition, the expression of the integral proteins was obviously inhibited and the activity of the enzymes was decreased post ultrasound treatment in the presence of 20 microg/ml HPD. Loss of the membrane proteins and inactivity of AC and GC post SDT was time-dependent. This paper reveals SDT can cause the loss of tumor cell membrane integral proteins and inactivity of the enzymes associated with cell proliferation which might be attributed to a sonochemical activation mechanism. The mechanisms by that tumor growth is inhibited by SDT can be understood as that the growth signaling pathway is partially interdicted and the resistance of tumor cells to the specifically activated immune cells is weakened.

Comparison between sonodynamic effect and photodynamic effect with photosensitizers on free radical formation and cell killing

Although enhancement of ultrasound-induced cell killing by photodynamic reagents has been shown, the sonochemical mechanism in detail is still not clear. Here, comparison between sonodynamic effect and photodynamic effect with photosensitizers at a concentration of 10 microM on free radical formation and cell killing was made. When electron paramagnetic-resonance spectroscopy (EPR) was used to detect 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (TAN) after photo-irradiation or sonication with 2,2,6,6-tetramethyl-4-piperidone (TMPD), the order of TAN formation in the photo-irradiated samples was as follows: rhodamine 6G (R6) > sulforhodamine B (SR) > hematoporphyrin (Hp) > rhodamine 123 (R123) > rose bengal (RB)>erythrosine B (Er) = 0; although there was time-dependent TAN formation when the samples were sonicated, no significant difference among these agents were observed. All these agents suppressed ultrasound-induced OH radical formation detected by EPR-spin trapping. Sensitizer-derived free radicals were markedly observed in SR, RB and Er, while trace level of radicals derived from R6 and R123 were observed. Enhancement of ultrasound-induced decrease of survival in human lymphoma U937 cells was observed at 1.5 W/cm(2) (less than inertial cavitation threshold) for R6, R123, SR and Er, and at 2.3 W/cm(2) for R6, R123, Er, RB and SR. On the other hand, photo-induced decrease of survival was observed for R6, Hp and RB at the same concentration (10 microM). These comparative results suggest that (1) (1)O(2) is not involved in the enhancement of ultrasound-induced loss of cell survival, (2) OH radicals and sensitizer-derived free radicals do not take part in the enhancement, and (3) the mechanism is mainly due to certain mechanical stress such as augmentation of physical disruption of cellular membrane by sensitizers in the close vicinity of cells and/or cavitation bubbles.

Enhanced antitumor activity of ultrasonic irradiation in the presence of new quinolone antibiotics in vitro

To determine if there is any synergistic antitumor effect of ultrasound (US) in the presence of new quinolone (NQ) antibiotics, 0.2 mM solutions of lomefloxacin hydrochloride (LFLX), sparfloxacin (SPFX), ciprofloxacin hydrochloride (CPFX), and gatifloxacin hydrate (GFLX) were tested as sonodynamic agents against sarcoma 180 cells in vitro. After US irradiation at 2 W/cm(2) for 30 and 60 s, the survival rates of tumor cells in the presence of NQ antibiotics were significantly lower than those in their absence (P < 0.001). In May-Giemsa smears, most of the tumor cells remained intact in the control group. However, in the 0.2 mM SPFX group, the tumor cells were mostly fragmented. The synergistic antitumor effect of SPFX was dose-dependent. Furthermore, when D-mannitol was used with SPFX, the survival rate of tumor cells after irradiation was comparable with that when SPFX alone was applied, but when L-histidine was used concurrently, the survival rate of tumor cells was significantly higher than that when SPFX alone was applied. These findings suggest that NQ antibiotics would exhibit useful antitumor activity under US irradiation, and that generation of singlet oxygen is involved in the process of cell damage.

Sonodynamic therapy--a review of the synergistic effects of drugs and ultrasound

Sonodynamic therapy, the ultrasound dependent enhancement of cytotoxic activities of certain compounds (sonosensitizers) in studies with cells in vitro and in tumor bearing animals, is reviewed. The attractive features of this modality for cancer treatment emerges from the ability to focus the ultrasound energy on malignancy sites buried deep in tissues and to locally activate a preloaded sonosensitizer. Possible mechanisms of sonodynamic therapy include generation of sonosensitizer derived radicals which initiate chain peroxidation of membrane lipids via peroxyl and/or alkoxyl radicals, the physical destabilization of the cell membrane by the sonosensitizer thereby rendering the cell more susceptible to shear forces or ultrasound enhanced drug transport across the cell membrane (sonoporation). Evidence against the role of singlet oxygen in sonodynamic therapy is discussed. The mechanism of sonodynamic therapy is probably not governed by a universal mechanism, but may be influenced by multiple factors including the nature of the biological model, the sonosensitizer and the ultrasound parameters. The current review emphasizes the effect of ultrasound induced free radicals in sonodynamic therapy.

A review of research into the uses of low level ultrasound in cancer therapy

The use of low power ultrasound in therapeutic medicine is a developing field and this review will concentrate on the applications of this technology in cancer therapy. The effects of low power ultrasound have been evaluated in terms of the biological changes induced in the structure and function of tissue. The main fields of study have been in sonodynamic therapy, improving chemotherapy, gene therapy and apoptosis therapy. The range of ultrasonic power levels that can be effectively employed in therapy appears to be narrow and this may have hindered past research in the applications in cancer treatment.

FCLA chemiluminescence from sonodynamic action in vitro and in vivo

In this work, the chemiluminescence method was engaged for the first time to detect the active oxygen species during sonodynamic action in vitro and in vivo. We used FCLA (3,7-dihydro-6-[4-[2-[N'-(5-fluoresceinyl)thioureido]-ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3-one sodium salt), which can selectively react with singlet oxygen ((1)O(2)) or superoxide anion (O(2)(-)) to emit photons, to detect in real time oxygen free radical formation in the sonosensitization of hematoporphyrin derivative. The results show that (1)O(2) is involved in the sonosensitization. In in vivo experiments, a tumor-imaging method by sonodynamic chemiluminescence detection was established. This method could have potential applications in clinics for tumor diagnosis.

Enhanced antitumor effect of ultrasound in the presence of piroxicam in a mouse air pouch model

The antitumor effects of piroxicam, a non-steroidal anti-inflammatory drug, on sarcoma 180 cells under ultrasonic irradiation were examined in a mouse air pouch model. When piroxicam was added to sarcoma 180 suspension under ultrasound irradiation (2 MHz, 10 W, 120 s), the mortality rate of tumor cells immediately after the irradiation and the survival rate of mice were significantly higher than those when ultrasound alone was applied, and these effects of piroxicam were dose-dependent. When D-mannitol was used with piroxicam, the mortality rate of the tumors cells after the irradiation was comparable with that when piroxicam alone was applied, but when L-histidine was used concurrently, the antitumor effect was significantly lower than that when piroxicam alone was applied. Histological examinations one week after the ultrasound irradiation in the presence of piroxicam showed sparse tumor tissue in the air pouch and normal appearance of the air pouch and surrounding tissue. The findings suggest that piroxicam enhances the anti-tumor effects of ultrasound in vivo by increasing the production of singlet oxygen without damage to tissue surrounding the tumor.