Hormonal therapy of breast cancer

Evaluation of transcriptional activity of the oestrogen receptor with sodium iodide symporter as an imaging reporter gene

BACKGROUND

Oestrogen receptors are ligand-dependent transcription factors whose activity is modulated either by oestrogens or by an alternative signalling pathway. Oestrogen receptors interact via a specific DNA-binding domain, the oestrogen responsive element (ERE), in the promoter region of sensitive genes. This binding leads to an initiation of gene expression and hormonal effects.

OBJECTIVE

To determine the transcriptional activity of the oestrogen receptor, we developed a molecular imaging system using sodium iodide symporter (NIS) as a reporter gene.

METHODS

The NIS reporter gene was placed under the control of an artificial ERE derived from pERE-TA-SEAP and named as pERE-NIS. pERE-NIS was transferred to MCF-7, human breast cancer cells, which highly expressed oestrogen receptor-alpha with lipofectamine. Stably expressing cells were generated by selection with G418 for 14 days. After treatment of 17beta-oestradiol and tamoxifen with serial doses, the (125)I uptake was measured for the determination of NIS expression. The inhibition of NIS activity was performed with 50 micromol x l(-1) potassium perchlorate.

RESULTS

The MCF7/pERE-NIS treated with 17beta-oestradiol accumulated (125)I up to 70-80% higher than did non-treated cells. NIS expression was increased according to increasing doses of 17beta-oestradiol. MCF7/pERE-NIS treated with tamoxifen also accumulated (125)I up to 50% higher than did non-treated cells. Potassium perchlorate completely inhibited (125)I uptake. When MDA-MB231 cells, the oestrogen receptor-negative breast cancer cells, were transfected with pERE-NIS, (125)I uptake of MDA-MB-231/pERE-NIS did not increase.

CONCLUSION

This pERE-NIS reporter system is sufficiently sensitive for monitoring transcriptional activity of the oestrogen receptor. Therefore, cis-enhancer reporter systems with ERE will be applicable to the development of a novel selective oestrogen receptor modulator with low toxicity and high efficacy.

Assessment of cyclin D1 overexpression as a prognostic factor in soft tissue sarcomas: role of laparoscopy and core needle biopsy

BACKGROUND

This study was designed to test cyclin D1 as a prognostic marker in patients with soft tissue sarcomas (STS), and to evaluate the usefulness of laparoscopy for determining cyclin D1 overexpression.

METHODS

The records of 62 patients with STS were collected: 28 with retroperitoneal STS (RSTS) and 34 with extremity STS (ESTS). A total of 51 patients underwent surgical resection, whereas 11 did not undergo surgery because of advanced tumor stage. Preoperative-intraoperative laparoscopic staging was performed for patients judged to be resectable at preoperative imaging.

RESULTS

Cyclin D1 was overexpressed in 30 (58.8%) of 51 resected patients and in 10 (90.9%) of 11 nonresected patients. Laparoscopy avoided unnecessary laparotomy in 9 (32.1%) of 28 RSTS patients.

CONCLUSIONS

High tumor grade, positive surgical margins, local recurrence, distant metastases, and cyclin D1 overexpression were related to poor survival. Multivariate analysis demonstrated cyclin D1 to be the only independent factor. Laparoscopy was shown to be useful for avoiding useless laparotomies.