Electrochemotherapy with Mitomycin C Potentiates Apoptosis Death by Inhibiting Autophagy in Squamous Carcinoma Cells

New effective and less painful high frequency electrochemotherapy protocols: From optimization on 3D models to pilot study on veterinary patients

Electroporation, a physical method that permeabilizes cell membranes, is increasingly used in cancer treatment. By enhancing the uptake of hydrophilic antitumor drugs, it boosts their cytotoxic effects and has proven effective in both human and veterinary medicine through electrochemotherapy. However, this treatment requires loco-regional or even general anesthesia, as electrical pulses cause muscle contractions and pain. Several clinical studies have demonstrated that application of high frequency pulses (above 5000 Hz) and short pulse duration (under 11 μs) causes much less discomfort to patients. In order to reduce the pain associated with contractions while maintaining the effectiveness of the treatment, we have developed new protocols using a high-frequency generator that delivers electric field pulses at a pulse repetition rate up to 2 MHz, associated to a multipolar electrode. In vitro tests on colorectal cancer cells were performed to assess the efficiency of cisplatin and bleomycin in inducing cell death. The efficiency obtained after one single treatment on both cell suspensions and on 3D multicellular spheroid models were similar to the ones obtained using ESOPE (European standard operating procedures for electrochemotherapy) protocol, which is currently used in clinics. In addition, as tumor cells die in an immunogenic cell death (ICD) mode and can release danger associated molecular patterns (DAMPs), major hallmarks of ICD were evaluated following the treatment by quantifying the apoptotic cell death, caspases 3/7 activation and key DAMPs. Subsequently, pilot studies on small number of conscious cats and horses under mild sedation confirmed that these protocols did not cause any noticeable muscle contractions and resulted in either partial or complete responses. New high-frequency electroporation protocols, described herein, show great promise in shifting electrochemotherapy into an effective and painless cancer treatment.

Co-inhibition of RAGE and TLR4 sensitizes pancreatic cancer to irreversible electroporation in mice by disrupting autophagy

Irreversible electroporation (IRE) is a local ablative treatment for patients with pancreatic cancer. During the IRE procedure, high-intensity electric pulses are released intratumorally to disrupt plasma membranes and induce cell death. Since the intensity of the pulsed electric field (PEF) can be decreased by the tumor microenvironment, some cancer cells are subjected to a sublethal PEF and may survive to cause tumor recurrence later. Autophagy activation induced by anticancer therapies is known to promote treatment resistance. In this study, we investigated whether autophagy is activated in residual cancer cells after IRE and assessed the roles it plays during tumor recurrence. Subcutaneous KPC-A548 or Panc02 murine pancreatic cancer cell line xenograft mouse models were established; once the tumors reached 7 mm in one dimension, the tumor-bearing mice were subjected to IRE. For in vitro sublethal PEF treatment, the pancreatic cancer cell suspension was in direct contact with the electrodes and pulsed at room temperature. We showed that autophagy was activated in surviving residual cells, as evidenced by increased expression of LC3 and p62. Suppression of autophagy with hydroxychloroquine (60 mg/kg, daily intraperitoneal injection) markedly increased the efficacy of IRE. We demonstrated that autophagy activation can be attributed to increased expression of high-mobility group box 1 (HMGB1); co-inhibition of two HMGB1 receptors, receptor for advanced glycosylation end products (RAGE) and Toll-like receptor 4 (TLR4), suppressed autophagy activation by upregulating the PI3K/AKT/p70 ribosomal S6 protein kinase (p70S6K) axis and sensitized pancreatic cancer cells to PEF. We prepared a polymeric micelle formulation (M-R/T) encapsulating inhibitors of both RAGE and TLR4. The combination of IRE and M-R/T (equivalent to RAGE inhibitor at 10.4 mg/kg and TLR4 inhibitor at 5.7 mg/kg, intravenous or intraperitoneal injection every other day) significantly promoted tumor apoptosis, suppressed cell cycle progression, and prolonged animal survival in pancreatic tumor models. This study suggests that disruption of HMGB1-mediated autophagy with nanomedicine is a promising strategy to enhance the response of pancreatic cancer to IRE.

Electrochemotherapy for head and neck cancers: possibilities and limitations

Head and neck cancer continues to be among the most prevalent types of cancer globally, yet it can be managed with appropriate treatment approaches. Presently, chemotherapy and radiotherapy stand as the primary treatment modalities for various groups and regions affected by head and neck cancer. Nonetheless, these treatments are linked to adverse side effects in patients. Moreover, due to tumor resistance to multiple drugs (both intrinsic and extrinsic) and radiotherapy, along with numerous other factors, recurrences or metastases often occur. Electrochemotherapy (ECT) emerges as a clinically proven alternative that offers high efficacy, localized effect, and diminished negative factors. Electrochemotherapy involves the treatment of solid tumors by combining a non-permeable cytotoxic drug, such as bleomycin, with a locally administered pulsed electric field (PEF). It is crucial to employ this method effectively by utilizing optimal PEF protocols and drugs at concentrations that do not possess inherent cytotoxic properties. This review emphasizes an examination of diverse clinical practices of ECT concerning head and neck cancer. It specifically delves into the treatment procedure, the choice of anti-cancer drugs, pre-treatment planning, PEF protocols, and electroporation electrodes as well as the efficacy of tumor response to the treatment and encountered obstacles. We have also highlighted the significance of assessing the spatial electric field distribution in both tumor and adjacent tissues prior to treatment as it plays a pivotal role in determining treatment success. Finally, we compare the ECT methodology to conventional treatments to highlight the potential for improvement and to facilitate popularization of the technique in the area of head and neck cancers where it is not widespread yet while it is not the case with other cancer types.

Nanoelectropulse delivery for cell membrane perturbation and oxidation in human colon adenocarcinoma cells with drug resistance

Ultrashort electric pulses in the nanosecond range (nsPEF) can affect extra- and intracellular lipid structures and can also alternate cell functioning reversibly and irreversibly. Several of the nsPEF effects are due to the abrupt rise in intracellular free calcium levels and calcium ions influx from the outside. Calcium is one of the most important factors in cell proliferation, differentiation, and cell death (apoptosis or necrosis). Manipulating calcium levels using electroporation can have different effects on normal and malignant cells. This study aimed to examine the impact of nsPEFs, combined with 1 mM Ca²⁺ in human colon adenocarcinoma cell lines: sensitive- LoVo and drug resistant-LoVoDX. In this study 200 pulses of 10 ns and high voltage (12.5-50 kVcm^-1) were used. Cell viability was determined by MTT and clonogenic assay. Proteasomal activity, GSH/GSSG assay, ROS production, and PALS-1 protein were evaluated as oxidative stress markers and protein damage. Cell morphology was visualized by AFM, SEM, and confocal microscopy imaging. The results revealed that nsPEF with 1 mM Ca²⁺ is cytotoxic, particularly for LoVoDX cells, and safe for normal cells. NsPEF provoked ROS release, altered cell polarity, and destabilized cell morphology. These results can be important for future protocols for colon adenocarcinoma using calcium nsPEF.

Electrochemotherapy: An Alternative Strategy for Improving Therapy in Drug-Resistant SOLID Tumors

Simple Summary

Chemotherapy is becoming an increasingly difficult antitumor therapy to practice due to the multiple mechanisms of drug resistance. To overcome the problem, it is possible to use alternative techniques, such as electrochemotherapy, which involves the simultaneous administration of the electrical pulse (electroporation) and the treatment with the drug in order to improve the effectiveness of the drug against the tumor. Electroporation has improved the efficacy of some chemotherapeutic agents, such bleomycin, cisplatin, mitomycin C, and 5-fluorouracil. The results of in vitro, veterinary, and clinical oncology studies are promising on various cancers, such as metastatic melanoma. The purpose of this review is to give an update on the state of the art of electrochemotherapy against the main solid tumors in the preclinical, clinical, and veterinary field.

Abstract

Electrochemotherapy (ECT) is one of the innovative strategies to overcome the multi drug resistance (MDR) that often occurs in cancer. Resistance to anticancer drugs results from a variety of factors, such as genetic or epigenetic changes, an up-regulated outflow of drugs, and various cellular and molecular mechanisms. This technology combines the administration of chemotherapy with the application of electrical pulses, with waveforms capable of increasing drug uptake in a non-toxic and well tolerated mechanical system. ECT is used as a first-line adjuvant therapy in veterinary oncology, where it improves the efficacy of many chemotherapeutic agents by increasing their uptake into cancer cells. The chemotherapeutic agents that have been enhanced by this technique are bleomycin, cisplatin, mitomycin C, and 5-fluorouracil. After their use, a better localized control of the neoplasm has been observed. In humans, the use of ECT was initially limited to local palliative therapy for cutaneous metastases of melanoma, but phase I/II studies are currently ongoing for several histotypes of cancer, with promising results. In this review, we described the preclinical and clinical use of ECT on drug-resistant solid tumors, such as head and neck squamous cell carcinoma, breast cancer, gynecological cancer and, finally, colorectal cancer.