Interferon-alpha and interleukin-12 gene therapy of cancer: interferon-alpha induces tumor-specific immune responses while interleukin-12 stimulates non-specific killing.
Cytokine gene therapy is applied in clinical studies of tumors, and IFN-alpha and IL-12 are widely used for cancer immunotherapy. Using a poorly immunogenic murine colorectal cancer cell line, MC38, we compared antitumor effects of IFN-alpha and IL-12. Transduced MC38 cell lines expressing IFN-alpha or IL-12 (MC38-IFNalpha or MC38-IL12, respectively) were established using retroviral vectors. Transduction of IFN-alpha or IL-12 gene to MC38 cells significantly reduced tumorigenicity in immunocompetent mice. When tumor-free mice initially injected with MC38-IFNalpha or MC38-IL12 cells were reinjected contralaterally with wild-type MC38 cells (MC38-WT) after 35 days, 7 of 12 or 2 of 12 mice rejected MC38-WT cells, respectively. In therapy-model mice with established tumor derived from MC38-WT cells, inoculation of gene-transduced cells significantly suppressed growth of the tumor in MC38-IFNalpha-inoculated groups, but not in the IL-12-inoculated group. Immunohistologic and flow cytometric analyses showed marked infiltration of CD8(+) cells in wild-type tumors of mice inoculated with IFN-alpha-expressing cells. Leukocyte-depletion experiments implicated CD8(+) T cells in tumor rejection induced by IFN-alpha-transduction; both CD8(+) T cells and natural killer cells were implicated in the more modest antitumor effect from IL-12 expression. To investigate induction of tumor-specific immune responses, we stimulated splenocytes from tumor-free mice twice in vitro with genetically modified MC38 cells. In vitro stimulations with MC38-IFNalpha cells induced definite MC38-specific lysis, but not stimulations with MC38-IL-12 cells. Injecting combination of MC38-IFNalpha and MC38-IL-12 cells caused an additive antitumor effect in the therapy model. These data suggested that IFN-alpha induces cytotoxic T lymphocytes and elicits long-lasting tumor-specific immunity, whereas IL-12 seems to stimulate non-specific killing. With additional refinements, combined IFN-alpha and IL-12 gene therapy might warrant clinical trials.
Second Department of Internal Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, 142-8666 Tokyo, Japan.
Jun-Ichi
J
Eguchi
Kazumasa
K
Hiroishi
Shigeaki
S
Ishii
Keiji
K
Mitamura
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D015316:Genetic Therapy / Q000379:methods*; D016898:Interferon-alpha / Q000235:genetics* / Q000627:therapeutic use*; D018664:Interleukin-12 / Q000235:genetics* / Q000276:immunology / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000276:immunology / Q000628:therapy*; D012190:Retroviridae / Q000235:genetics; D013154:Spleen / Q000166:cytology; D013997:Time Factors; D014407:Tumor Cells, Cultured
D016898:Interferon-alpha; D018664:Interleukin-12