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Detection and characterization of a pancreatic tumor inhibitory factor
1Department of Surgical Oncology, Roswell Park Memorial Institute, Buffalo, New York 14263.
Abstract:
Numerous growth factors which stimulate cellular proliferation have been identified and characterized. Little information is available on autocrine factors that inhibit growth. The objective of this study was to determine if an established human pancreatic cancer cell line, RWP-1, produced such a tumor growth inhibitory factor (TIF). RWP-1 serum-free conditioned media (CM) was concentrated and its effect on DNA synthesis was determined by measuring incorporation of [3H]thymidine. CM inhibited [3H]thymidine incorporation in a dose-dependent and nontoxic manner with all cell lines tested. TIF activity was stable at 56 degrees C, labile at 95 degrees C and partially inactivated by acid, reduction/alkylation, and enzymatic digestion. The TIF exhibited differential activity against the tested cell lines and was found to be active against a normal murine fibroblast line. The TIF appears to be a polypeptide with a molecular weight greater than 5000 Da. Attempts at isolation of TIF with affinity and ion-exchange chromatography have thus far been unsuccessful, implying that more than one factor may be involved. RWP-1 TIF is a potentially important factor because of its role in the regulation of cellular proliferation.
Insights
Researchers discovered a tumor growth inhibitory factor (TIF) produced by human pancreatic cancer cells. This TIF regulates cellular proliferation and shows potential for cancer research.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Growth factors stimulating cellular proliferation are well-documented.
- Limited knowledge exists regarding autocrine factors that inhibit tumor growth.
Purpose of the Study:
- To investigate if the human pancreatic cancer cell line RWP-1 produces a tumor growth inhibitory factor (TIF).
Main Methods:
- RWP-1 serum-free conditioned media (CM) was concentrated.
- The effect of CM on DNA synthesis was measured via [3H]thymidine incorporation.
- Characterization of TIF properties including stability and molecular weight.
Main Results:
- Concentrated CM inhibited [3H]thymidine incorporation in a dose-dependent and non-toxic manner across tested cell lines.
- The TIF demonstrated stability at 56°C but was labile at 95°C.
- TIF activity was partially inactivated by acid, reduction/alkylation, and enzymatic digestion, suggesting a polypeptide nature (>5000 Da).
- The TIF showed differential activity against various cell lines, including a normal murine fibroblast line.
Conclusions:
- The RWP-1 cell line produces a TIF that regulates cellular proliferation.
- The TIF is a polypeptide with a molecular weight greater than 5000 Da.
- Further research is needed for TIF isolation due to potential involvement of multiple factors.
