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Macrophage colony-stimulating factor complementary DNA: a candidate for gene therapy in metastatic melanoma
1(Department of Dermatology), University of Colorado Cancer Center, University of Colorado Health Sciences Center, Denver 80262, USA.
Background:
At present, there is no highly effective treatment for metastatic melanoma. Innovative approaches aimed at inducing a more effective immune response against tumors have shown promising results in animal models. One approach involves the genetic modification of tumor cells so that they produce cytokines that stimulate an immune response.
Purpose:
The aim of this study was to determine the effectiveness of cytokine gene therapy for metastatic melanoma in a murine melanoma model.
Methods:
B16F10 murine melanoma cells, which readily metastasize to the lungs, were transduced with a retroviral vector containing genes encoding neomycin resistance and human macrophage colony-stimulating factor (M-CSF). The presence of M-CSF messenger RNA in transduced cells was examined by coupled reverse transcription and polymerase chain reaction. Concentrations of soluble M-CSF in cell culture supernatants were determined by enzyme-linked immunosorbent assays (ELISAs). A clonal cell line, designated N+/CSF+, that expressed and secreted M-CSF was identified. Another clonal cell line, designated N+/CSF-, did not secrete M-CSF at levels detectable by ELISA. B16F10, N+/CSF-, and N+/CSF+ cells, individually or in combination, were injected intravenously or subcutaneously into C57BL/6 mice; we then evaluated the tumorigenicity and metastatic behavior of the cells, as well as the immune responses and survival of the mice. The immune responses assayed were the cytotoxic T lymphocyte (CTL) and peritoneal exudate cell (PEC) tumoricidal activities.
Results:
Injection of B16F10 cells into the tail vein of C57BL/6 mice led to the establishment of lung metastases by week 2 and death by week 8. Injection of the N+/CSF+ or N+/CSF- cells led to the establishment of lung metastases that were detected at 2 and 3 weeks, respectively; however, these metastatic lesions were eliminated, and the animals had survival rates similar to those of the noninjected control mice. Injection of mice with a mixture of B16F10 and N+/CSF- cells resulted in the development of metastatic disease and 0% survival at 8 weeks, whereas mice that had been given an injection of a mixture of B16F10 and N+/CSF+ cells had an 80% survival rate at 8 weeks and survived at least two times longer (P = .007). The CTL and PEC tumoricidal activities in animals given an injection of N+/CSF+ cells suggested that monocytes and lymphocytes were responsible for the observed antitumor response.
Conclusion:
These findings suggest that the expression of M-CSF by genetically modified melanoma cells caused an effective antitumor immune response in host C57BL/6 mice and, thus, prolonged survival over that observed in the control mice.
Insights
Genetically modified melanoma cells producing macrophage colony-stimulating factor (M-CSF) effectively triggered an antitumor immune response in mice. This cytokine gene therapy significantly improved survival rates in a metastatic melanoma model.
Area of Science:
- Immunology
- Oncology
- Gene Therapy
Background:
- Metastatic melanoma lacks effective treatments, necessitating innovative therapeutic strategies.
- Enhancing the host immune response against tumors is a promising approach.
- Genetic modification of tumor cells to produce cytokines can stimulate anti-tumor immunity.
Purpose of the Study:
- To evaluate the efficacy of cytokine gene therapy using macrophage colony-stimulating factor (M-CSF) for metastatic melanoma.
- To assess the impact of M-CSF expressing melanoma cells on tumor growth, immune response, and survival in a murine model.
Main Methods:
- B16F10 melanoma cells were genetically modified using retroviral vectors to express M-CSF.
- Transduced cells (N+/CSF+) and control cells (N+/CSF-) were characterized for M-CSF expression and secretion.
- Mice were injected with modified or unmodified melanoma cells, alone or in combination, and monitored for tumor development, immune response (CTL, PEC), and survival.
Main Results:
- M-CSF expressing melanoma cells (N+/CSF+) led to the elimination of metastatic lesions and normal survival rates.
- Mice injected with a combination of B16F10 and N+/CSF+ cells showed an 80% survival rate at 8 weeks, significantly longer than controls.
- Enhanced cytotoxic T lymphocyte (CTL) and peritoneal exudate cell (PEC) activities indicated a robust anti-tumor immune response.
Conclusions:
- M-CSF expression in genetically modified melanoma cells effectively stimulates an anti-tumor immune response.
- This cytokine gene therapy approach significantly prolongs survival in a murine model of metastatic melanoma.
- The findings support M-CSF gene therapy as a potential strategy for treating metastatic melanoma.