Electrochemotherapy with bleomycin and cisplatin enhances cytotoxicity in primary and metastatic uveal melanoma cell lines in vitro

Abstract

Electrochemotherapy (ECT) enhances responsiveness to cytotoxic drugs in numerous cell lines in vitro. Clinically ECT is widely applied for skin tumor ablation and has shown efficacy in treating non-resectable colorectal liver metastases. There is limited experience of ECT for ocular tumor therapy. We investigated the cytotoxic effect of bleomycin and cisplatin in combination with electroporation on chemoresistant human uveal melanoma (UM) cell lines in vitro. Four UM cell lines (Mel 270, 92-1, OMM-1, OMM-2.5) were treated with electroporation (pulse amplitude 300-1000 V/cm, 8-80 pulses, 100 μs, 5 Hz) and increasing concentrations of bleomycin and cisplatin (0-7.5 μg/ml). Cell survival was analyzed by MTT viability assay after 36 hours. UM cell lines were resistant to both bleomycin and cisplatin. In combination with electro- poration, the effects of bleomycin and cisplatin were increased 8-70 fold and 3-15 fold, respectively, in all UM cell lines. At the lowest concentration of bleomycin tested (1 μg/ml), viability was maximally reduced in all UM cell lines by ≥69% with electroporation conditions of 750 V/cm and 20 pulses. All UM cell lines were more resistant to cisplatin; however, electro- poration of 1000 V/cm and 8 pulses resulted in similar reductions in cell viability of 92-1, Mel270 with 2.5 μg/ml cisplatin, OMM2-5 cells with 5 μg/ml cisplatin and OMM1 cells with 1 μg/ml cisplatin. In vitro ECT with bleomycin or cisplatin is more effective than the highest concentration of the antineoplastic drug or electroporation alone, opening new perspectives in primary and metastatic UM treatment.

Recent Advances in Electrochemotherapy

“…The reasons for difference in response are multifaceted and include physical features pertinent to electrochemotherapy, such as unavailability of the drug and insufficient coverage with electric field and biological, pertinent to patient, such as previous treatments, difference in tumor microenvironment, mutational status, and so on. 2,14,18 Thus, electrochemotherapy is still evaluated in different types of cancer, either in vitro or in vivo, including colon carcinoma CT26 (in vitro) 19 ; bladder cancer SW780 (in vitro and in vivo) 20 ; fibroblasts, human umbilical vein endothelial cells (HUVEC; in vitro) and two squamous cell carcinomas, CAL-27 and SCC-4 (in vitro) 21 ; ovarian cell lines OvBH-1 and SKOV-3 (in vitro) 22 ; human neuroblastoma SH-SY5Y cells (in vitro) 23 ; BRAF-mutated melanoma cells (SK-MEL-28) and their counterpart without mutation, CHL-1 cells (in vitro) 24 ; chemoresistant uveal melanoma cells (Mel 270, 92-1, OMM-1, OMM-2) (in vitro) 25 ; primary cells from metastatic pancreatic tumors (in vitro) 26 ; human papillomavirus (HPV)-positive head and neck squamous cell carcinoma 2A3 (in vitro and in vivo) 27 ; Lewis lung carcinoma and CT 25 colorectal carcinoma (in vivo) 28 ; conjunctival melanoma CRMM1 and CRMM2 and normal conjunctival epithelial cells HCjE-Gi (in vitro) 29 ; radioresistant head and neck squamous cell carcinoma Fa-DuRR (in vitro and in vivo) 30 ; and small cell lung cancer H69AR cells (in vitro). 31 In general, it was demonstrated that electrochemotherapy with bleomycin or cisplatin causes immunogenic cell death in colon carcinoma 19,28 ; that human endothelial cells are more susceptible to electrochemotherapy than tumor cells, 21 supporting the antivascular effect in vivo; that electrochemotherapy is effective in ovarian carcinoma cells resistant to standard therapy 22 ; and that electrochemotherapy is also effective in neuroblastoma and primary pancreatic tumor cells, which was not demonstrated before.…”

“…27 For electrochemotherapy with bleomycin, it was demonstrated that it is more effective in melanoma cells that harbor BRAF mutation 24 and in melanoma cells that are chemoresistant. 25 In addition, electrochemotherapy with bleomycin is more effective in radioresistant head and neck tumors than electrochemotherapy with cisplatin, 30 and it is also effective against small cell lung cancer cells. 31 Recently, it was shown that pancreatic tumor cells died from necroptosis rather than from necrosis or apoptosis after electrochemotherapy with bleomycin, cisplatin, and oxaliplatin.…”

Electrochemotherapy Using Doxorubicin and Nanosecond Electric Field Pulses: A Pilot in Vivo Study

“…At the same time, the pulse parameters represent only half of the electrochemotherapy treatment components, while the other half depends on the chemotherapeutic drug. Currently, bleomycin and cisplatin are dominating the field [ 9 , 27 , 28 , 29 ], while other approaches using doxorubicin [ 29 , 30 ], vinorelbine [ 13 ] or even paclitaxel [ 16 ] are emerging.…”

Image Analysis of 3D Conjunctival Melanoma Cell Cultures Following Electrochemotherapy

“…The drawbacks of its application are localized pain, muscle contraction, erythema and edema [ 14 ]. The effect of ECT in ocular melanomas remains unclear, since the research and acquired knowledge in this field is very limited [ 17 , 18 , 19 ].…”