In vivo electrogene transfer of interleukin-12 inhibits tumor growth and lymph node and lung metastases in mouse mammary carcinomas.
BACKGROUND
Human breast cancer metastasizes mainly to lymph nodes, lungs, liver, and bone; in the majority of cases, it is the development of metastases which leads to death. In order to suppress mammary cancer metastasis, we applied in vivo electrogene transfer (non-viral method) as a means of interleukin-12 (IL-12) gene therapy on highly metastatic murine mammary cancer model.


METHODS
Metastatic mammary tumors induced by inoculation in BALB/c female mice were treated by intratumoral injections of either a plasmid vector containing IL-12 or empty vector and then subjected to in vivo electrogene transfer once a week for 8 weeks.


RESULTS
Treatment with IL-12 resulted in elevation of both IL-12 and IFNgamma levels in mammary tumors and in serum and intratumoral levels of CD4 and CD8 proteins were also increased. Tumor volumes and lymphatic and pulmonary metastases were significantly reduced. The histopathological changes induced by IL-12 characteristically included marked inflammation, increased apoptosis, decreased DNA synthesis, peripheral influx of significantly greater numbers of active macrophages, and reduced blood microvessel density, and apoptotic vascular endothelial cells were frequently seen. Western blotting showed decreases in VEGFR-3 of tumors exposed to IL-12 gene therapy. In adjuvant immunofluorescence studies, the CD31-positive endothelial cells of microvessels showed decreased VEGFR-3 expression in IL-12-treated tumors. However, apparent alterations in VEGFR-3 expression of podoplanin-positive lymphatic endothelial cells were not observed in IL-12-treated tumors. Although recombinant IL-12 did not inhibit tubular formation of human umbilical vein endothelial cells in a Matrigel assay, recombinant IFNgamma did completely suppress the tubular formation.


CONCLUSIONS
In vivo electrogene transfer of IL-12 exerts strong anti-tumorigenic and anti-metastatic effects likely due to T-cell-mediated immune responses as well as anti-angiogenic action.
Shibata
Masa-Aki
MA
Department of Anatomy and Biology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka 569-8686, Japan.
Ito
Yuko
Y
Morimoto
Junji
J
Kusakabe
Ken
K
Yoshinaka
Ryoji
R
Otsuki
Yoshinori
Y
D000818:Animals; D004594:Electrophysiology; D005260:Female; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D007150:Immunohistochemistry; D018664:Interleukin-12 / Q000096:biosynthesis / Q000235:genetics* / Q000627:therapeutic use; D008175:Lung Neoplasms / Q000556:secondary*; D015674:Mammary Neoplasms, Animal / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D009362:Neoplasm Metastasis / Q000517:prevention & control; D009389:Neovascularization, Pathologic; D010957:Plasmids; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000096:biosynthesis
D018664:Interleukin-12; D040321:Vascular Endothelial Growth Factor Receptor-3