Electrochemo-gene therapy of cancer: intratumoral delivery of interleukin-12 gene and bleomycin synergistically induced therapeutic immunity and suppressed subcutaneous and metastatic melanomas in mice

Abstract

To treat established melanoma in mice, intratumoral transfer of bleomycin and/or an interleukin (IL)-12 expression vector was performed by means of electroporation. Although either bleomycin alone or the IL12 gene alone significantly suppressed the subcutaneous tumors, the combination therapy drastically improved the therapeutic outcome. Three of eight mice (37.5%) that received both bleomycin and the IL12 gene showed complete remission of the preestablished tumors and rejected subsequent rechallenge with the tumor cells. We also examined whether electrochemo-gene therapy for subcutaneous tumor mass induced suppression of pulmonary metastasis that had been established by intravenous inoculation of the melanoma cells. Although metastatic foci were significantly reduced in number in groups that were given IL12 gene alone or bleomycin plus IL12 gene, it was only the combination therapy that significantly prolonged the mean survival period of the tumor-bearing animals. Natural killer (NK) and cytotoxic T lymphocyte cytolytic activities were markedly enhanced in the mice that received the chemo-gene therapy, while IL12 gene therapy alone partially elevated the NK cytotoxicity. The present study suggests that the electroporation-mediated delivery of the IL12 gene and bleomycin synergistically elicits innate and adaptive anti-melanoma immune responses, resulting in marked suppression of the treated tumors as well as bystander metastatic lesions.

Therapeutic RNA interference of malignant melanoma by electrotransfer of small interfering RNA targeting Mitf

“…55,56,[59][60][61] Electroporation was applied to RNAi by Pekarik et al 62 who transfected synthetic siRNA in ovo into chick embryos, while we first documented electrotransfer of siRNA into a mammalian organ in vivo. 53 We also employed electroporation to therapeutic RNAi for rheumatoid arthritis in rat, indicating that the articular disorder was drastically ameliorated by silencing tumor necrosis factor-a in inflammatory sinovial tissue.…”

“…59 To transfect B16 in vitro, the siRNA duplex was incubated with RNAiFect (Qiagen, Hilden, Germany) and the resultant complex was added to B16 cell cultures according to the manufacturer's protocol. Cells were then incubated at 371C in 5% CO 2 /95% humidified air (standard conditions) before analysis.…”

Local delivery system of cytotoxic agents to tumors by focused sonoporation

“…Tumor size on perpendicular axes was measured daily and tumor volume was calculated by the formula: (Volume (mm )/2). 19 Tumors that had reached an average volume of 55-65 mm 3 at 14 days after transplantation were used in the following experiments. In some experiments, tumor that had reached a volume of 30 mm 3 after transplantation was used for immunoblot analysis as described below.…”

Gene Therapy Progress and Prospects: Electroporation and other physical methods

“…22 In another study, electrotransfer of a combination of bleomycin and a plasmid encoding IL-12 not only produced complete remission in a proportion of mice carrying a subcutaneous melanoma but also provided a significant protective effect against established metastases. 23 Given the success of electrotransfer of bleomycin in many clinical trials, 3 the combination with gene transfer appears to offer further potential in the delivery of a clinically effective treatment.…”