An immunohistochemical study with an estrogen receptor-related protein (ER-D5) in human colorectal cancer.

The ER-D5 antigen is a protein associated with the estrogen receptor that is present only in estrogen receptor-positive tissues. To clarify the estrogen receptor in colon cancer, the localization of ER-D5 was studied immunohistochemically. Forty-three of 171 (25.1%) specimens of colon cancer showed reactivity for ER-D5. Reactivity was seen only in the cytoplasm. No reactivity was seen in cancer limited to the mucosa or in adenoma, but submucosal cancers showed a rate of positivity similar to cancers that involved lamina muscularis and beyond. Estradiol staining was done on serial sections from 56 specimens. There was a significant relationship between reactivity for estradiol and that for ER-D5. In the 15 specimens where both ER-D5 and estradiol were positive, the distribution of estradiol was similar to that of ER-D5. It was concluded that the immunohistochemical localization of ER-D5 indirectly shows that of the estrogen receptor in colorectal cancer tissues.