Expression and intracellular localization of ACA and TRA-1-81 in smooth muscle cell tumors.

We studied the expression and intracellular localization of ACA and TRA-1-81 in smooth muscle cell tumors. The study was performed on tissue specimens obtained during surgery from patients with uterine leiomyoma and leiomyosarcoma (mean age 34 and 51 years, respectively). ACA was present in leiomyoma, leiomyosarcoma, and control myometrium. Intracellular expression of ACA varied in different types of tumors and was minimum in normal myometrium and maximum in leiomyosarcoma. Membrane localization of the protein is typical of common and cellular leiomyoma, while in the growth zones of mitotically active leiomyoma and leiomyosarcoma the reaction product was primarily located in tumor cell cytoplasm. TRA was detected in some leiomyosarcoma cells. Thus, ACA dysregulation was revealed in the growth zones of leiomyomas and in leiomyosarcomas, which manifested in enhanced expression of this protein and its detachment from the plasma membrane, which leads ACA translocation into the cytoplasm and nucleus of tumor cells and potentiates their proliferative activity.