Differential genomic and proteomic profiles of synthetics progestins in the breast

S Mirkin, DF Archer

CONRAD, The Jones Institute for Reproductive Medicine, Norfolk, Virginia, United States

Objective The molecular mechanisms of gene regulation in the breast by progestins used in contraception are poorly characterized. Some data suggest that progestins play a significant role in the growth of breast tumors. Our objectives are to investigate gene and protein expression profiles using different progestins in the T47-D breast cancer cell line.

Design T47-D cells were treated with medroxyprogesterone (MPA), levonorgestrel (LNG) and norethindrone (NET). For genomic analysis, RNA was extracted. cDNA arrays were produced containing 2000 sequence of clones spotted. Labeled cRNA were hybridized to the array and the signal quantified. For proteomics analysis, Surface-Enhanced Laser Desorption Ionization (SELDI) was used. Cells were lysed and protein lysates were loaded robotically on IMAC chip. Each protein peak was labeled and its intensity normalized for total ion current.

Results All progestins modified approximately the same number of genes (15% of the array ) + 2 fold. MPA upregulated more genes related with breast cancer growth (Stat5a, GAS and HOXA 10) than the other compounds. Angiogenic genes were upregulated with MPA (VEGF 11 fold, TNF 9 fold). BCL2 was down regulated by MPA, but not with NET or LNG. SELDI spectra reveled a different proteomic fingerprint with each of the 3 compounds investigated.

Conclusion Genomic and proteomic analyses identified a differential gene and protein expression profile between MPA, NET and LNG in the T47-D cells. MPA upregulated more genes related with breast cancer growth and angiogenesis than the other two progestins. SELDI reveled a differential effect at protein level of these 3 synthetics progestins confirming genomic findings. Based on these data we suggest that synthetic progestins may have a differential effect on breast cancer tumor growth.