Breast Cancer Cell Line Phenotype Affects Sonoporation Efficiency Under Optimal Ultrasound Microbubble Conditions

Synchronized Chemotherapy/Photothermal Therapy/Sonodynamic Therapy of Human Triple-Negative and Estrogen Receptor-Positive Breast Cancer Cells Using a Doxorubicin-Gold Nanoclusters-Albumin Nanobioconjugate

OBJECTIVE

Novel strategies for treating triple-negative breast cancer (TNBC) are ongoing because of the lack of standard-of-care treatment. Nanoframed materials with a protein pillar are considered a valuable tool for designing multigoals of energy-absorbing/medication cargo and are a bridge to cross-conventional treatment strategies.

METHODS

Nanobioconjugates of gold nanoclusters-bovine serum albumin (AuNCs-BSA) and doxorubicin-AuNCs-BSA (Dox-AuNCs-BSA) were prepared and employed as a simultaneous double photosensitizer/sonosensitizer and triple chemotherapeutic/photosensitizer/sonosensitizer, respectively.

RESULTS

The highly stable AuNCs-BSA and Dox-AuNCs-BSA have ζ potentials of -29 and -18 mV, respectively, and represent valuable photothermal and sonodynamic activities for the combination of photothermal therapy and sonodynamic therapy (PTT/SDT) and synchronized chemotherapy/photothermal therapy/sonodynamic therapy (CTX/PTT/SDT) of human TNBC cells, respectively. The efficiency of photothermal conversion of AuNCs-BSA was calculated to be a promising value of 32.9%. AuNCs-BSA and Dox-AuNCs-BSA were activated on either laser light irradiation or ultrasound exposure with the highest efficiency on the combination of both types of radiation. CTX/PTT/SDT of MCF-7 and MDA-MB-231 breast cancer cell lines by Dox-AuNCs-BSA were evaluated with the MTT cell proliferation assay and found to progress synergistically.

CONCLUSION

Results of the MTT assay, detection of the generation of intracellular reactive oxygen species and occurrence of apoptosis in the cells confirmed that CTX/PTT/SDT by Dox-AuNCs-BSA was attained with lower needed doses of the drug and improved tumor cell ablation, which would result in the enhancement of therapeutic efficacy and overcoming of therapeutic resistance.

AMPK is required for recovery from metabolic stress induced by ultrasound microbubble treatment

Ultrasound-stimulated microbubble (USMB) treatment is a promising strategy for cancer therapy. USMB promotes drug delivery by sonoporation and enhanced endocytosis, and also impairs cell viability. However, USMB elicits heterogeneous effects on cell viability, with apparently minimal effects on a subset of cells. This suggests that mechanisms of adaptation following USMB allow some cells to survive and/or proliferate. Herein, we used several triple negative breast cancer cells to identify the molecular mechanisms of adaptation to USMB-induced stress. We found that USMB alters steady-state levels of amino acids, glycolytic intermediates, and citric acid cycle intermediates, suggesting that USMB imposes metabolic stress on cells. USMB treatment acutely reduces ATP levels and stimulates the phosphorylation and activation of AMP-activated protein kinase (AMPK). AMPK is required to restore ATP levels and support cell proliferation post-USMB treatment. These results suggest that AMPK and metabolic perturbations are likely determinants of the antineoplastic efficacy of USMB treatment.

The Impact of Extracellular Ca2+ and Nanosecond Electric Pulses on Sensitive and Drug-Resistant Human Breast and Colon Cancer Cells

Simple Summary

The drug resistance phenomenon in cancer constantly induces problems in therapeutic protocols. Pulsed electric fields (PEFs) seem to be a promising method in drug molecule delivery. Here we have proved that electroporation supported by calcium ions can alternate the activity of drug resistance proteins. Our results indicated that MDR1 expression is not significantly modified by nanosecond electroporation in multidrug-resistant cells. However, PEF significantly inhibited MDR1 activity and cell viability when combined with calcium ions.

Abstract

(1) Background: Calcium electroporation (CaEP) is based on the application of electrical pulses to permeabilize cells (electroporation) and allow cytotoxic doses of calcium to enter the cell. (2) Methods: In this work, we have used doxorubicin-resistant (DX) and non-resistant models of human breast cancer (MCF-7/DX, MCF-7/WT) and colon cancer cells (LoVo, LoVo/DX), and investigated the susceptibility of the cells to extracellular Ca²⁺ and electric fields in the 20 ns–900 ns pulse duration range. (3) Results: We have observed that colon cancer cells were less susceptible to PEF than breast cancer cells. An extracellular Ca²⁺ (2 mM) with PEF was more disruptive for DX-resistant cells. The expression of glycoprotein P (MDR1, P-gp) as a drug resistance marker was detected by the immunofluorescent (CLSM) method and rhodamine-123 efflux as an MDR1 activity. MDR1 expression was not significantly modified by nanosecond electroporation in multidrug-resistant cells, but a combination with calcium ions significantly inhibited MDR1 activity and cell viability. (4) Conclusions: We believe that PEF with calcium ions can reduce drug resistance by inhibiting drug efflux activity. This phenomenon of MDR mechanism disruption seems promising in anticancer protocols.

Sonoporation: Underlying Mechanisms and Applications in Cellular Regulation

Ultrasound combined with microbubble-mediated sonoporation has been applied to enhance drug or gene intracellular delivery. Sonoporation leads to the formation of openings in the cell membrane, triggered by ultrasound-mediated oscillations and destruction of microbubbles. Multiple mechanisms are involved in the occurrence of sonoporation, including ultrasonic parameters, microbubbles size, and the distance of microbubbles to cells. Recent advances are beginning to extend applications through the assistance of contrast agents, which allow ultrasound to connect directly to cellular functions such as gene expression, cellular apoptosis, differentiation, and even epigenetic reprogramming. In this review, we summarize the current state of the art concerning microbubble‐cell interactions and sonoporation effects leading to cellular functions.

Modifications of Plasma Membrane Organization in Cancer Cells for Targeted Therapy

Modifications of the composition or organization of the cancer cell membrane seem to be a promising targeted therapy. This approach can significantly enhance drug uptake or intensify the response of cancer cells to chemotherapeutics. There are several methods enabling lipid bilayer modifications, e.g., pharmacological, physical, and mechanical. It is crucial to keep in mind the significance of drug resistance phenomenon, ion channel and specific receptor impact, and lipid bilayer organization in planning the cell membrane-targeted treatment. In this review, strategies based on cell membrane modulation or reorganization are presented as an alternative tool for future therapeutic protocols.

The effect of low frequency and low intensity ultrasound combined with microbubbles on the sonoporation efficiency of MDA-MB-231 cells

Background

Ultrasound can produce certain biophysical effects including thermal and non-thermal effects on cells. Sonoporation, the most widely studied non-thermal biological effect of ultrasound, is considered to be the basis for new therapeutic applications. Ultrasound irradiation can increase the permeability of cell membranes through sonoporous effect, which makes molecules like those of drugs, protein, and DNA that normally cannot pass through the cell membranes be able to enter cells. Considering the poor therapeutic effect and poor prognosis of triple negative breast cancer, we aimed to explore the experimental conditions and find the optimal parameters to improve the therapeutic efficacy of chemotherapeutic drugs for MDA-MB-231 cells.

Methods

By establishing an experimental and control group, our study investigated the effect of low frequency and low intensity ultrasound combined with microbubbles on MDA-MB-231 cell membrane permeability at different times. We conducted factorial cross-design and set 3 levels of ultrasound intensity: 230, 300, and 370 mW/cm²; 3 levels of irradiation time: 1, 2, and 3 minutes; and 6 levels of microbubble doses: 0, 0.2, 0.4, 0.6, 0.8, and 1 mL.

Results

Results show that ultrasound intensity, time of irradiation, and microbubbles concentration are not only related to but also have interactive effects on the sonoporation efficiency of MDA-MB-231 cells, with the rank order being sound intensity, irradiation time, and microbubble concentration. The average positive rates (%) of FD4 staining in sound intensities of 230, 300, and 370 mW/cm² levels were 1.20±0.71, 13.80±5.86, and 10.71±4.36, respectively; and in irradiated times of 1, 2, and 3 min they were 7.54±5.95, 9.74±8.42, and 8.59±5.80, respectively. When the microbubbles increased according to the gradient of 0, 0.2, 0.4, 0.6, 0.8, and 1 mL, the positive rates (%) of FD4 staining were 7.32±5.89, 9.26±7.39, 8.31±5.67, 10.12±8.42, 8.67±7.23, and 7.72±6.24.

Conclusions

In our study, the optimal parameters of the sonoporous effect for MDA-MB-231 cells were 300 mW/cm² of ultrasound intensity, 2 minutes of irradiation time, and 20% microbubbles concentration.

New FH peptide-modified ultrasonic nanobubbles for delivery of doxorubicin to cancer-associated fibroblasts

Aim: To synthesize and evaluate a novel FH peptide-modified ultrasonic nanobubble-loading doxorubicin (FH-NB-DOX) for specially cancer-associated fibroblasts (CAFs) targeting and eradication. Materials & methods: The characteristics, cytotoxicity, contrast-enhanced ultrasound imaging (CEUI), targeting ability and specially eradicating CAFs of these NBs were investigated. Results: FH-NB-DOX (about 208 nm) showed a good CEUI, and achieved higher targeting ability due to the conjunction ability of FH peptide to tenascin C protein high-level expressed in CAFs. Under ultrasound irradiation, FH-NB-DOX could delivery more DOX into CAFs, thus exhibited stronger eradication role compared with NB-DOX and free DOX. Conclusion: These new NBs, which combines the advantages of targeted theranostic agent and CEUI, is expected to be a potential approach for tumor therapy based on CAF targeting.

Sonoporation of Cells by a Parallel Stable Cavitation Microbubble Array

Sonoporation is a targeted drug delivery technique that employs cavitation microbubbles to generate transient pores in the cell membrane, allowing foreign substances to enter cells by passing through the pores. Due to the broad size distribution of microbubbles, cavitation events appear to be a random process, making it difficult to achieve controllable and efficient sonoporation. In this work a technique is reported using a microfluidic device that enables in parallel modulation of membrane permeability by an oscillating microbubble array. Multirectangular channels of uniform size are created at the sidewall to generate an array of monodispersed microbubbles, which oscillate with almost the same amplitude and resonant frequency, ensuring homogeneous sonoporation with high efficacy. Stable harmonic and high harmonic signals emitted by individual oscillating microbubbles are detected by a laser Doppler vibrometer, which indicates stable cavitation occurred. Under the influence of the acoustic radiation forces induced by the oscillating microbubble, single cells can be trapped at an oscillating microbubble surface. The sonoporation of single cells is directly influenced by the individual oscillating microbubble. The parallel sonoporation of multiple cells is achieved with an efficiency of 96.6 ± 1.74% at an acoustic pressure as low as 41.7 kPa.

Sonoporation of Cells by a Parallel Stable Cavitation Microbubble Array

Sonoporation is a targeted drug delivery technique that employs cavitation microbubbles to generate transient pores in the cell membrane, allowing foreign substances to enter cells by passing through the pores. Due to the broad size distribution of microbubbles, cavitation events appear to be a random process, making it difficult to achieve controllable and efficient sonoporation. In this work a technique is reported using a microfluidic device that enables in parallel modulation of membrane permeability by an oscillating microbubble array. Multirectangular channels of uniform size are created at the sidewall to generate an array of monodispersed microbubbles, which oscillate with almost the same amplitude and resonant frequency, ensuring homogeneous sonoporation with high efficacy. Stable harmonic and high harmonic signals emitted by individual oscillating microbubbles are detected by a laser Doppler vibrometer, which indicates stable cavitation occurred. Under the influence of the acoustic radiation forces induced by the oscillating microbubble, single cells can be trapped at an oscillating microbubble surface. The sonoporation of single cells is directly influenced by the individual oscillating microbubble. The parallel sonoporation of multiple cells is achieved with an efficiency of 96.6 ± 1.74% at an acoustic pressure as low as 41.7 kPa.