DNA synthesis in estrogen receptor-positive human breast cancer takes place preferentially in estrogen receptor-negative cells.
The primary breast tumors of 27 patients were analyzed for the expression of estrogen receptors (ER) and DNA synthesis. Seventeen tumors were ER-positive, and the simultaneous expression of ER and DNA synthesis could be analyzed in 14 ER-positive tumors. DNA synthesis was measured through the thymidine labeling index (TLI). ER expression was detected by immunohistochemistry with monoclonal antibodies. In these tumors, 38.6% +/- 13.1% of the cells were ER-positive (average TLI = 0.60% +/- 0.70%), as opposed to the presence of 61.4% +/- 13.1% of ER-negative cells (average TLI = 0.65% +/- 0.53%). In 12 of 14 tumors, both ER-positive and ER-negative cells were found to be engaged in DNA synthesis, whereas in two tumors only ER-negative cells were synthesizing DNA. On the basis of the TLI and the proportion of ER-negative and ER-positive cells in the total population, it is suggested that the ER-positive and ER-negative compartments are interrelated in most tumors. In five tumors, the ER-negative compartment would be a precursor of the ER-positive segment, whereas in six tumors the ER-positive segment appears to be a precursor of the ER-negative one. In three tumors, no evidence of an interrelationship between both segments could be found. In the 14 tumors analyzed, it also was found that 69.1% +/- 21.3% of the DNA-synthesizing cells were ER-negative; this probably accounts for the temporary remissions observed after hormonal treatment in breast cancer.
Ballare
C
C
Hospital Mariano R. Castex, Buenos Aires, Argentina.
Bravo
A I
AI
Laucella
S
S
Sorin
I
I
Cerdeiro
R
R
Loza
J
J
Sousa Martinez
F
F
Guman
N
N
Mordoh
J
J
D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D004247:DNA / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D008940:Mitotic Index; D009363:Neoplasm Proteins / Q000032:analysis; D009367:Neoplasm Staging; D011960:Receptors, Estrogen / Q000032:analysis*
D009363:Neoplasm Proteins; D011960:Receptors, Estrogen; D004247:DNA