Objective: To investigate the regulation of human progesterone receptor isoforms A and B in uterine endometrial carcinoma by estrogen and insulin-like growth factor-1 (IGF-I) so as to provide theoretical basis for clinical hormone treatment of uterine endothelium cancer.
Methods: The uterine endometrial adenocarcinoma cell line HEC-IB and the breast cancer cell line MCF-7 were cultured in vitro. The HEC-IB cells were stimulated by 10 nmol/L estrogen and 20 ng/ml IGF-I respectively for 72 h. The MCF-7 cells were stimulated by 10 nmol/L estrogen for 72 h. Western blotting was used to examine the protein levels of the two isoforms of receptors of progesterone. RNA was extracted from the cells. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of the isoform B.
Results: (1) Western blotting showed that the photodensity values of hPRA and hPRB did not change significantly after the HEC-IB cells were stimulated by estrogen for 72 hours (P = 0.716, and 0.391 respectively), however, the hPRA and hPRB were significantly down-regulated after IGF-I had been given for 72h (P = 0.008 and 0.002 respectively). After MCF-7 cell was given estrogen for 72 h hPR-A tended to be up- regulated but this change had no significant difference (P = 0.074) however, hPRB was significantly up- regulated (P = 0.044). (2) RT-PCR showed that hPRB mRNA was not expressed in HEC-IB cells originally, and became positive after stimulation by estrogen and IGF-1 for 72 hours respectively, however, the expression level being higher in the HEC-IB cells stimulated by estrogen than in those stimulated by IGF-1. hPRB was not expressed in MCF-7 cells originally too, and became positive after simulation by estrogen and IGF-1 for 72 hours respectively, however, the expression level being higher in the MCF-7 cells stimulated by estrogen than in those stimulated by IGF-1.
Conclusion: (1) Estrogen and IGF-I regulate hPR isoforms and have cell specialty. (2) Estrogen and IGF-I up- regulate hPRB mRNA at gene level or transcription level, but there are some inhibitory factors which make the protein production become less after transcription.