Charge heterogeneity of human mammary tumor estrogen receptors. Relationship with a hormonal sensitivity tumor marker.
A high resolution quantitative method for estrogen receptor analysis has been elaborated using isoelectric focusing in 0.5% agarose gel, without any prior trypsin digestion. The 23 cytosols analyzed were stabilized by molybdate and prepared from human mammary tumors with progesterone receptors (PR + cytosols) or without (PR - cytosols). Progesterone receptor was used as a tumoral hormonal sensitivity marker. The estrogen receptors usually resolved as 4 isoform peaks of close isoelectric points. In PR - cytosols, the mean pI values were 4.7, 5.5, 6 and 6.5. Significant differences between the two cytosol populations were observed concerning pI 4.7 and 6.5 isoforms. In PR - cytosols, the pI 4.7 isoform occurred in greater proportions than in PR + cytosols, whereas lower proportions of pI 6.5 isoform were seen. The comparison between high performance size exclusion chromatography profiles and isoelectric focusing patterns, before and after cytosol incubation at 28 degrees C with KCl (0.4 M), confirmed an oligomer structure for the pI 4.7 isoform and suggested a monomer structure (Stokes radius 2.9 mm) for the pI 6.5 estrogen receptor isoform. The results indicated that isoelectric focusing analysis of estrogen receptors could be useful in the prediction of breast cancer hormonal sensitivity.
Bailleul
S
S
Laboratoire d'Analyses Isotopiques, Centre François Baclesse, Caen, France.
Gauduchon
P
P
Malas
J P
JP
Lechevrel
C
C
Roussel
G
G
Goussard
J
J
D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000378:metabolism*; D003600:Cytosol / Q000032:analysis; D005260:Female; D006801:Humans; D007525:Isoelectric Focusing; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism
D014408:Biomarkers, Tumor; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone