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Published on: May 23, 2014
Molecular tools to reestablish progestin control of endometrial cancer cell proliferation
1Division of Basic Reproductive Science, Department of Obstetrics and Gynecology, The University of Colorado Health Sciences Center, Denver, USA.
Objective:
Endometrial cancers often arise in a setting of estrogen stimulation unopposed by the differentiating effects of progesterone. Our laboratory and others have previously shown that progesterone receptor down-regulation or perturbation of progesterone receptor isoform A or B expression is associated with the development of poorly differentiated endometrial cancers that are not growth inhibited by progestins. The purpose of these studies was to reestablish high progesterone receptor isoform A and B gene expressions in such endometrial cancer cells and to examine the effects of progestin treatment on cell growth and metastatic potential after this transformation.
Study Design:
To induce high levels of expression of the progesterone receptor isoforms in KLE and Hec50 endometrial cancer cells, adenoviral vectors encoding the genes for progesterone receptor isoforms A and B were created. The characteristic ability of cancer cells to grow independently of anchorage to the surrounding solid matrix was measured by counting colony formation on soft agar for 8 to 14 days. Cell proliferation in response to a time course of progestin treatment was tested with flow cytometry.
Results:
After treatment with a control vector without a progesterone receptor--encoding insert, no effect of progestin treatment on cell proliferation was found; after treatment with vectors encoding progesterone receptor isoform A or B, however, progestin treatment resulted in significant inhibition of cell growth. The anchorage-independent cell growth on soft agar assay showed that by 8 to 14 days the number of cell colonies was reduced by 50% relative to control preparations in the presence of progesterone receptor isoform A plus progestin (P <.0001, both Hec50 and KLE cell lines) and by 90% in the presence of progesterone receptor isoform B plus progestin (P <.0001, both Hec50 and KLE cell lines). Progestin treatment also resulted in a time-dependent reduction in cell proliferation as measured by flow cytometry. Although transfection with both progesterone receptor isoforms A and B reduced cell proliferation according to our assays, progesterone receptor isoform B caused a much more dramatic decrease in cell growth (P =.001, Hec50 cells; P <.0001, KLE cells).
Conclusion:
In poorly differentiated endometrial cancer cells that are resistant to progestin therapy, adenovirus-induced expressions of progesterone receptors A and B reestablish progestin control of endometrial cancer cell proliferation.
Insights
Restoring progesterone receptors A and B in endometrial cancer cells re-sensitized them to progestin therapy. This approach significantly inhibited cancer cell growth and anchorage-independent proliferation, offering a potential new treatment strategy.
Area of Science:
- Gynecologic Oncology
- Molecular Biology
- Cancer Research
Background:
- Endometrial cancers often develop with high estrogen and low progesterone, leading to poorly differentiated tumors resistant to progestin therapy.
- Down-regulation or altered expression of progesterone receptor (PR) isoforms A and B is linked to aggressive endometrial cancer phenotypes.
- Restoring PR expression may re-sensitize resistant endometrial cancer cells to progestin treatment.
Purpose of the Study:
- To re-establish high expression of progesterone receptor isoforms A and B in endometrial cancer cells.
- To investigate the effects of progestin treatment on cell growth and metastatic potential after restoring PR expression.
Main Methods:
- Adenoviral vectors encoding PR isoforms A and B were used to induce high PR expression in KLE and Hec50 endometrial cancer cells.
- Anchorage-independent growth was assessed by soft agar colony formation assays.
- Cell proliferation was measured using flow cytometry in response to progestin treatment.
Main Results:
- Progestin treatment significantly inhibited cell growth in cells expressing PR isoforms A or B, unlike control cells.
- Expression of PR isoform A with progestin reduced colony formation by 50%, while PR isoform B with progestin reduced it by 90%.
- Progestin treatment led to a time-dependent reduction in cell proliferation, with PR isoform B showing a more pronounced effect.
Conclusions:
- Adenovirus-mediated re-expression of PR isoforms A and B re-establishes progestin sensitivity in poorly differentiated, progestin-resistant endometrial cancer cells.
- This approach offers a potential strategy to restore progestin control over endometrial cancer cell proliferation.
- PR isoform B demonstrated a stronger inhibitory effect on cell growth compared to PR isoform A.
