Detection of breast tumor progesterone receptor isoforms with the PR-enzyme immunoassay kit (Abbott). Effect of heat shock proteins on epitope recognition.
Eighty-nine human breast tumor progesterone receptors were assayed both by a radioligand assay (RLA; 3H-ORG-2058) and by the enzyme immunoassay from Abbott Laboratories (PR-EIA). The correlation obtained between the two methods was EIA = 0.83 RLA + 4.1 fmol/mg protein (r = 0.83). Great discrepancies were observed with EIA/RLA ratios varying from 0.5 to 2. After KCl 0.4 mol/l dissociation and chromatographic separation of 8 PR isoforms [12], the two PR polymeric forms (isoforms 1 and 2) which remained bound to the hsp90 heat shock protein were not or only partially detected by EIA, whereas PR-hsp70 isoforms were highly detected with EIA/RLA ratios increased up to 3.8. Free PR-A and PR-B proteins and the PR-truncated form (52 kDa) were never detected by EIA. Thus, the final result of PR assay using the Abbott method depends directly on the amount of PR-hsp70 isoforms produced through KCl dissociation during the overnight incubation of PR with the KD68 coated beads.
Goussard
J
J
Laboratoire d'analyses isotopiques, centre François-Baclesse, Caen, France.
Lemoisson
E
E
Cren
H
H
D001943:Breast Neoplasms / Q000378:metabolism*; D000939:Epitopes / Q000378:metabolism; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007527:Isoenzymes / Q000032:analysis*; D011869:Radioligand Assay; D011980:Receptors, Progesterone / Q000032:analysis* / Q000737:chemistry / Q000276:immunology
D000939:Epitopes; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D007527:Isoenzymes; D011980:Receptors, Progesterone