Figure 1.

Comparison of the relative expression of estrogen receptor (ER) variant truncated after sequences encoding exon 2 of the wild-type (WT) ER-α (ERC4) messenger RNAs between breast tumor and adjacent matched normal breast samples. (A) Total RNA extracted from frozen tissue sections from tumor (T) and adjacent normal (N) breast tissue samples was reverse transcribed and polymerase chain reaction (PCR) was amplified using ERU, ERL and C4L primers (see text). Radioactive PCR products were separated on a 6% acrylamide gel and visualized by autoradiography. Bands migrating at 149 and 536 base pairs were identified as corresponding to WT-ER and ERC4 variant messenger RNA, respectively. C, negative control (no complementary DNA added during the PCR reaction). (B) For each case, signals corresponding to ERC4 variant messenger RNA were quantified (see text) and expressed in arbitrary units for tumor (black column) and normal (white column) components. For each sample, the mean and the standard deviation of at least three different PCR assays are indicated. Cases are sorted by ER status (black bottom lane) and progesterone receptor (PR) status (gray bottom lane). The significance of the differences between tumor and normal matched components within each subgroup, as tested using the Wilcoxon matched-pair test, is indicated where P <0.05. M, molecular weight marker (fx174 Haelll digest, Gibco BRL, Grand Island, New York, NY).