Progesterone receptor gene restriction fragment length polymorphisms in human breast tumors

We examined the progesterone receptor (PgR) gene in tissue from both primary human breast tumors and normal placentas, detecting restriction fragment length polymorphisms (RFLPs) with the restriction endonucleases Pst I/Sst I and HindIII. There was a general agreement of the Pst I and Sst I polymorphisms in any individual tumor, suggesting that they define two alleles in the human PgR locus, one being characterized by a deletion of about 300 base pairs with respect to the other. Both primary human breast tumor specimens (n = 36) and human term placentas (n = 48) displayed similar allele frequencies and typical mendelian distribution of these Pst I/Sst I alleles. The previously reported HindIII PgR RFLP was also investigated in 132 breast tumors. The HindIII PgR gene RFLP did not display typical mendelian distribution in the breast tumors; the factors affecting the HindIII allele frequencies are presently unknown. Neither the HindIII RFLP nor the deletion defined by Pst I and Sst I correlated with PgR expression as determined by a ligand-binding assay, suggesting that neither is related to the heterogeneity of PgR expression seen in breast tumors.