Relation between receptor status and ultrastructure in breast cancer: E+P+ versus E-P-

Invasive breast cancer specimens were selected, which were either estrogen and progesterone receptor positive (E+P+), (30 cases) or both negative (E-P-). Light microscopical typing and grading were performed. From electron microscopic sections 27 nuclear and cytoplasmic features were recorded. Both estrogen and progesterone receptor content were evaluated using agar gel electrophoresis. As regards grading, highly differentiated tumors were significantly associated with E+P+ receptor status. Among the nuclear ultrastructural features, marked polymorphia, irregular chromatin distribution and multiple nucleoli were associated with lack of receptors. E+P+ tumors more often had surface structures which establish cell interconnection, such as desmosomes, halfdesmosomes and membrane interdigitations, and structures indicating special membrane differentiation, such as microvilli and intracytoplasmic ductuli. Most correlations with receptor content were observed in the assortment of cytoplasmic organelles studied. E-P- tumors were rich in organelles which indicate high metabolic activity, such as mitochondria and ribosomes. A polar organization and smooth ER were more frequent in E+P+ tumors. The biochemical-ultrastructural correlations presented in this study support the hypothesis that the formation of steroid receptors runs parallel to the individual degree of cytoplasmic and nuclear organization and is independent of the histological tumor type. The functional integrity of the complete estrogen response mechanism in E+P+ tumors is indicated by high grades of ultrastructural organization.