Progesterone-induced inhibition of growth and differential regulation of gene expression in PRA- and/or PRB-expressing endometrial cancer cell lines.
OBJECTIVE
Progesterone plays an important role in controlling proliferation and differentiation of the human endometrium. Because there are two progesterone receptor isoforms (PRA and PRB), it was important to generate tools to be able to study the role of these two progesterone receptors separately.


METHODS
Using stable transfection techniques, both human progesterone receptor isoforms (hPRA and hPRB) were reintroduced into a hPR-negative subclone of the well-differentiated endometrial cancer cell line Ishikawa. Several Ishikawa subcell lines were constructed, each expressing different levels of hPRA, hPRB, or hPRA and hPRB, respectively.


RESULTS
These Ishikawa subcell lines showed a marked progesterone-induced growth inhibition with induction of apoptosis after long-term culture in the presence of hormone. Upon measuring gene regulation, a clear difference in regulation of expression of the selected genes by progesterone treatment was observed between the PRA-, PRB-, or PRA/B-expressing cell lines. Integrin beta4 (ITGB4) was only regulated in PRA-expressing cells; amphiregulin was highly regulated in PRB-expressing cells; insulin-like growth factor binding protein 3 (IGFBP3) was only regulated in PRB- and PRA/B-expressing cells; and metallothionein 1L (MT1L) was highly regulated in PRA/B-expressing cells. Interestingly, based on literature data, these genes can be implicated in induction of apoptosis, but are modulated here in such a way that suggests induction of resistance against apoptosis.


CONCLUSIONS
Reintroduction of PRs into Ishikawa cells rescued progesterone responsiveness in these cells. Furthermore, using these human endometrial cancer subcell lines, clear and distinct functional differences between the PR isoforms were observed.
Smid-Koopman
Ellen
E
Department of Obstetrics and Gynecology, Erasmus Medical Center, Rotterdam, The Netherlands.
Kuhne
Liesbeth C M
LC
Hanekamp
Eline E
EE
Gielen
Susanne C J P
SC
De Ruiter
Petra E
PE
Grootegoed
J Anton
JA
Helmerhorst
Theo J M
TJ
Burger
Curt W
CW
Brinkmann
Albert O
AO
Huikeshoven
Frans J
FJ
Blok
Leen J
LJ
D017209:Apoptosis; D002454:Cell Differentiation; D049109:Cell Proliferation; D016889:Endometrial Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D011374:Progesterone / Q000502:physiology*; D020033:Protein Isoforms; D011980:Receptors, Progesterone / Q000096:biosynthesis*; D014162:Transfection; D014407:Tumor Cells, Cultured
D020033:Protein Isoforms; D011980:Receptors, Progesterone; C101118:progesterone receptor A; C097314:progesterone receptor B; D011374:Progesterone