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Systemic interleukin 2 therapy for human prostate tumors in a nude mouse model
J A Triest1, D J Grignon, M L Cher
1Department of Urology, Barbara Ann Karmanos Cancer Institute at Wayne State University School of Medicine and Harper Hospital, Detroit, Michigan 48201, USA.
Abstract:
Once the regional lymph nodes become involved in prostate carcinoma, 85% of patients develop distant metastases within 5 years, and metastatic disease is difficult to treat. We have investigated the effect of systemic interleukin 2 (IL-2) treatment on metastatic prostate carcinoma using a xenograft tumor model. Cells from a PC-3/IF cell line, produced by intrafemoral injection of human PC-3 prostate carcinoma cells, were injected in the prostate of Balb/c nude mice. Prostate tumors and para-aortic lymph nodes were resected, and tumor cells were recultured and passaged in the prostate in vivo to produce new cell lines. On day 6 following prostatic injection of these cell lines, mice were treated with i.p. injections of IL-2 at 25,000-50,000 units/ day for 5 consecutive days. The effect of IL-2 on tumor progression was assessed, and histological studies were performed on prostate tumor and lymph node sections. The tumor cell lines generated by serial prostate injection were tumorigenic and metastasized to regional para-aortic lymph nodes. Tumors of 0.4 cm were obtained by day 16 and grew to 1-1.5 cm by day 40 with metastasis to para-aortic lymph nodes. Following two to three weekly courses of 5 days of 25,000-40,000 units/day of IL-2, the growth of prostate tumors was inhibited by 94%. Higher doses of 50,000 units/ day were toxic. Histologically, prostate sections showed vascular damage manifested by multifocal hemorrhages and an influx of lymphocytes and polymorphonuclear cells into disintegrating tumors and areas of necrosis containing numerous apoptotic cells. In contrast to control mice, para-aortic lymph nodes were not enlarged in responding mice. These findings suggest that systemic IL-2 therapy can induce an antitumor response in prostate tumors and control their growth and metastasis.
Insights
Systemic interleukin 2 (IL-2) therapy significantly inhibited prostate tumor growth and metastasis in mice. This treatment induced an antitumor response, reducing tumor size by 94% and preventing lymph node spread.
Area of Science:
- Oncology
- Immunotherapy
- Translational Research
Background:
- Metastatic prostate carcinoma poses a significant clinical challenge, with high rates of distant metastasis after lymph node involvement.
- Effective treatments for metastatic prostate cancer, particularly after lymph node spread, are urgently needed.
Purpose of the Study:
- To investigate the efficacy of systemic interleukin 2 (IL-2) in controlling metastatic prostate carcinoma using a preclinical xenograft model.
- To evaluate the impact of IL-2 on tumor progression, metastasis, and host immune response in prostate cancer.
Main Methods:
- A human prostate carcinoma cell line (PC-3/IF) was used to establish tumors in the prostates of Balb/c nude mice.
- Tumor-bearing mice received systemic injections of IL-2 (25,000-50,000 units/day) for 5 consecutive days, repeated in courses.
- Tumor growth, metastasis to para-aortic lymph nodes, and histological changes were assessed.
Main Results:
- Systemic IL-2 treatment, at doses of 25,000-40,000 units/day, inhibited prostate tumor growth by 94%.
- Histological analysis revealed vascular damage, inflammatory cell infiltration, necrosis, and apoptosis within tumors.
- IL-2 treatment prevented the enlargement of para-aortic lymph nodes, indicating control of metastasis.
Conclusions:
- Systemic IL-2 therapy demonstrates significant potential in controlling the growth and metastasis of prostate carcinoma.
- IL-2 induces a potent antitumor response, characterized by tumor vascular damage and immune cell infiltration.
- These findings support further investigation of IL-2 as a therapeutic strategy for metastatic prostate cancer.