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Production and response of a human prostatic cancer line to transforming growth factor-like molecules
A MacDonald1, G D Chisholm, F K Habib
1University Department of Surgery (WGH), Western General Hospital, Edinburgh, UK.
Abstract:
Serum-free media conditioned by the androgen insensitive human prostate cancer cell line DU145 showed immunological transforming growth factor-alpha (TGF alpha) activity, as well as competing activity in epidermal growth factor (EGF) radioreceptor assays (RRA). Furthermore, there were factors in the conditioned media which inhibited and stimulated DNA synthesis by DU145 cells in a dose-dependent fashion. Fractionation of the concentrated conditioned media by reverse-phase high performance liquid chromatography revealed several peaks containing EGF-like competitive activity only one of which demonstrated TGF alpha activity. However, none of the peaks corresponded to immunoreactive EGF. Measurement of EGF receptors on DU145 cells by competition and saturation analysis revealed high levels of receptors (mean +/- s.d. = 2.5 +/- 1 x 10(5) surface receptors per cell) which were of high affinity (Kd +/- s.d. = 1.0 +/- 0.5 nmol l-1). Although DU145 cells express high levels of EGF receptors, DNA synthesis was only minimally affected by exogenous EGF and TGF alpha.
Insights
Prostate cancer cells (DU145) produce transforming growth factor-alpha (TGF alpha) and epidermal growth factor (EGF)-like factors. These factors have minimal impact on DU145 cell DNA synthesis despite high EGF receptor levels.
Area of Science:
- Oncology
- Cell Biology
- Biochemistry
Background:
- Androgen-insensitive prostate cancer cells, such as DU145, can secrete growth factors.
- Epidermal Growth Factor (EGF) and its receptors play crucial roles in cell proliferation and cancer progression.
Purpose of the Study:
- To investigate the presence and activity of EGF-like factors in DU145 cell conditioned media.
- To characterize the EGF receptors on DU145 cells and their response to exogenous growth factors.
Main Methods:
- Conditioned media from DU145 cells were analyzed for growth factor activity using radioreceptor assays (RRA).
- Reverse-phase high-performance liquid chromatography (RP-HPLC) was used for factor fractionation.
- EGF receptor levels and affinity on DU145 cells were quantified via competition and saturation analyses.
Main Results:
- DU145 conditioned media exhibited transforming growth factor-alpha (TGF alpha) activity and EGF-like competitive activity.
- Fractionation identified specific peaks with EGF-like activity, but none matched immunoreactive EGF.
- DU145 cells possess a high number of high-affinity EGF receptors.
- Exogenous EGF and TGF alpha showed minimal effect on DU145 cell DNA synthesis.
Conclusions:
- Androgen-insensitive prostate cancer cells secrete bioactive TGF alpha and EGF-like substances.
- Despite high EGF receptor expression, DU145 cells demonstrate limited responsiveness to EGF and TGF alpha, suggesting complex regulatory mechanisms in prostate cancer growth.