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Regression of rat mammary tumors associated with suppressed growth hormone
Abstract:
Serum growth hormone (GH) was suppressed in female rats bearing mammary tumors induced by 7, 12, dimethylbenz(a)anthracene (DMBA) or N-nitrosomethylurea(NMU). Serum GH was suppressed due to treatment with a human GH analog produced by the plerocercoid stage of the tapeworm Spirometra mansonoides. Rats treated with plerocercoid growth factor (PGF) via plerocercoid infection had accelerated growth rates despite marked reductions in GH levels. Approximately two-thirds of the mammary tumors induced by either DMBA or NMU regressed during three weeks of exposure to PGF while most of the control tumors continued to grow. The data support an important regulatory role for GH in growth of mammary tumors in rats.
Insights
Plerocercoid growth factor (PGF) suppressed serum growth hormone (GH) in rats, leading to mammary tumor regression. This suggests GH plays a key role in regulating mammary tumor growth.
Area of Science:
- Endocrinology
- Oncology
- Parasitology
Background:
- Mammary tumors can be induced by chemical carcinogens like DMBA and NMU.
- Serum growth hormone (GH) levels are implicated in the growth of various tumors.
- The plerocercoid stage of Spirometra mansonoides produces a growth factor (PGF).
Purpose of the Study:
- To investigate the effect of plerocercoid growth factor (PGF) on serum growth hormone (GH) levels in rats with chemically induced mammary tumors.
- To determine the impact of PGF on the regression of mammary tumors.
- To explore the regulatory role of GH in mammary tumor development.
Main Methods:
- Induction of mammary tumors in female rats using 7,12-dimethylbenz(a)anthracene (DMBA) or N-nitrosomethylurea (NMU).
- Administration of PGF via plerocercoid infection to experimental groups.
- Monitoring of serum GH levels and tumor size in both treated and control groups.
- Assessment of tumor regression rates over a three-week period.
Main Results:
- Serum GH levels were suppressed in rats treated with PGF.
- Despite reduced GH, treated rats exhibited accelerated growth rates.
- Approximately two-thirds of mammary tumors regressed in rats treated with PGF.
- Control tumors generally continued to grow during the study period.
Conclusions:
- Plerocercoid growth factor (PGF) effectively suppresses serum growth hormone (GH).
- PGF can induce significant regression of DMBA- or NMU-induced mammary tumors in rats.
- Growth hormone (GH) plays a crucial regulatory role in the progression of mammary tumors.