Alterations in the estrogen receptor alpha mRNA in the breast tumors of African American women

Several recent reports have shown that the mortality rate with breast cance r is about three times higher in African American women than in other popul ations. In addition, the available data also indicate that the tumors are v ery aggressive and poorly differentiated with a very low frequency of hormo ne receptors. To gain an insight into the factors that may be responsible f or their aggressive tumors, we investigated the transcript profiles of the estrogen receptor (ER), the most important prognostic factor in breast canc er, in the tumors derived from African American women. We analyzed 24 immun ohistochemically ER+ and 6 ER- malignant tumors for ER mRNA by reverse tran scription polymerase chain reaction using a number of primer pairs. For com parative purposes, 20 ER+ malignant tumor issues derived from Caucasian pat ients were also included, Our results showed that only 15 of the ER+ tumors from African American women patients had full-length wild-type receptor tr anscripts and the others exhibited alterations/truncations in exon 8. We al so found that the majority of tumors that had alterations/truncations in ex on 8 did not express the naturally occurring, more abundant exon 7 deletion transcript. Most of the tumors expressed exon 2, exons 2-3, and exon 5 del etion variant transcripts. Unexpectedly, 2 of the 6 immunohistochemically E R- tumors showed full-length wildtype receptor mRNA but none of the variant transcripts.