Immunoexpression of Steroid Hormone Receptors and Proliferation Markers in Uterine Leiomyoma and Normal Myometrial Tissues from the Miniature Pig Sus scrofa

摘要

Uterine leiomyomas in miniature pet pigs occur similarly to that in women with regards to frequency, age, parity and cycling. Clinical signs, gross and histologic features of the porcine tumors closely resemble uterine leiomyomas (fibroids) in women. Although fibroids are hormonally responsive in women, the role of estrogen and progesterone has not been elucidated. Current animal models present challenges in data extrapolation to humans. In this study, immunohistochemistry was used to assess the expression of the steroid hormone receptors, ER-α, ER-β and PR, and cell proliferation markers, PCNA and Ki-67, in tumor and matched myometrial tissues sampled from miniature pigs. A “quickscore” method was used to determine receptor expression, and percent labeling indices were calculated for the markers. ER-α/β and PR were localized to nuclei of smooth muscle cells in both tissues. PR expression was intense and diffuse throughout all tissues, with correlation between tumors and matched myometria. Conversely, ER-α expression was more variable between the tissues and animals. ER-β expression was low. PCNA and Ki-67 were localized to the nucleus and expression varied among tumors; however, normal tissues were overall negative. These findings support further investigation into the use of the miniature pig as a model of fibroids in women.