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Characterization of membrane-associated growth inhibitor activity for Ehrlich ascites mammary carcinoma cells
Abstract:
Purified plasma membranes obtained from bovine milk or from bovine mammary gland inhibited in vitro growth of Ehrlich ascites mammary carcinoma cells. Plasma membranes derived from tumor cells or from tumor tissue were inactive. Growth inhibition by milk fat globule membranes was shown to be due to release of membrane-associated inhibitory factors into the medium. Gentle removal of proteins from the surface of milk fat globule membranes succeeded in recovery of a fraction inhibiting cell growth specifically. The same fraction contained the antigen cross-reacting with an antiserum raised against the previously purified 13 kD growth inhibitor from bovine mammary gland.
Insights
Plasma membranes from bovine milk inhibit cancer cell growth. These membranes contain a protein fraction that acts as a specific growth inhibitor, also identified as an antigen.
Area of Science:
- Biochemistry
- Cell Biology
- Cancer Research
Background:
- Plasma membranes from bovine milk and mammary glands have been investigated for biological activity.
- Ehrlich ascites mammary carcinoma cells are a model for cancer cell growth studies.
- Tumor-derived plasma membranes were previously found to be inactive against tumor cells.
Purpose of the Study:
- To investigate the in vitro effect of bovine milk and mammary gland plasma membranes on cancer cell growth.
- To identify the components within these membranes responsible for growth inhibition.
- To characterize the inhibitory fraction and its antigenic properties.
Main Methods:
- Purification of plasma membranes from bovine milk and mammary glands.
- In vitro incubation of plasma membranes with Ehrlich ascites mammary carcinoma cells.
- Fractionation of milk fat globule membranes to isolate inhibitory components.
- Protein removal from membrane surfaces.
- Antigenic cross-reactivity testing using antiserum against a known growth inhibitor.
Main Results:
- Plasma membranes from bovine milk and mammary glands inhibited Ehrlich ascites mammary carcinoma cell growth in vitro.
- Plasma membranes from tumor cells or tissue did not show inhibitory activity.
- Growth inhibition was attributed to factors released from milk fat globule membranes.
- A specific protein fraction, obtained by gentle surface protein removal, inhibited cell growth.
- This inhibitory fraction contained an antigen that cross-reacted with an antiserum for a known 13 kD bovine mammary gland growth inhibitor.
Conclusions:
- Bovine milk and mammary gland plasma membranes possess components that can inhibit cancer cell proliferation.
- The inhibitory activity is associated with specific, membrane-bound factors, particularly proteins.
- These findings suggest a potential role for milk-derived factors in cancer growth modulation.