Effect of interleukin-7 gene transfection into ovarian carcinoma cell line SKOV3 in vitro and in vivo

Abstract

Objective. To investigate the effect of interleukin-7 (IL-7) gene transfection into an established ovarian carcinoma cell line (SKOV3) in vitro and evaluate the tumorigenicity of SKOV3-IL-7 in severe combined immunodeficient (SCID) mice. Methods. IL-7 gene was transfected into SKOV3 cells by liposome. IL-7 mRNA and protein of SKOV3-IL-7 and their parental control cells were detected by reverse transcriptive-polymerase chain reaction (RT-PCR) and Western blot, respectively. The levels of IL-7, IL-2, TNFα and TGFβ1 in the supernatant were detected by ELISA. The cell cycle, HLA-ABC, HLA-DR and ICAM-1 expressions were assayed by flow cytometry. The sensitivities of tumor cells to lymphokine-activated killer (LAK) cells were measured by lactate dehydrogenase (LDH) release assay. Tumorigenicities of SKOV3-IL-7 and their parental cells in SCID mice were evaluated by macro- and histological examination, while IL-7 expression and secretion were detected by immunohistochemistry and ELISA. Results. IL-7 mRNA and protein were detectable in SKOV3-IL-7 only. ICAM-1 expression was significantly higher and TGFβ1 level in culture supernatants was significantly decreased in SKOV-IL-7, all other variables remained unchanged. The proliferative activity and cell cycle of SKOV3-IL-7 were unchanged. The cytotoxic sensitivity of SKOV3-IL-7 to LAK cells was significantly higher. Both gene-transfected and nontransfected SKOV3 cells were successfully inoculated into the peritoneal cavities of SCID mice. IL-7 proteins in plasmas and tumor tissues were detectable only in SCID mice inoculated with SKOV3-IL-7. The IL-7 engineered murine tumor models revealed better general aspects, reduced tumor development and dissemination. Conclusions. IL-7 gene transfection into SKOV3 cells downregulates TGFβ1 secretion, upregulates ICAM-1 expression and enhances sensitivity to LAK cells in vitro. The tumorigenicity of IL-7 engineered cells in SCID mice is reduced. These findings may offer support to the development of cytokine gene therapy for ovarian carcinoma.