Factors affecting the loss of MED12-mutated leiomyoma cells during in vitro growth

// Jeannine Bloch 1 , Carsten Holzmann 1 , Dirk Koczan 2 , Burkhard Maria Helmke 3 , Jörn Bullerdiek 1, 4 1 Institute of Medical Genetics, University Rostock Medical Center, D-18057 Rostock, Germany 2 Institute of Immunology, University Rostock Medical Center, D-18057 Rostock, Germany 3 Institute of Pathology, Elbe Kliniken, Klinikum Stade, D-21682 Stade, Germany 4 Center of Human Genetics, University of Bremen, D-28359 Bremen, Germany Correspondence to: Jörn Bullerdiek, email: joern.bullerdiek@med.uni-rostock.de Keywords: MED12 mutations, uterine leiomyomas, in vitro growth, model system, cell culture Received: July 28, 2016 Accepted: March 08, 2017 Published: March 30, 2017 ABSTRACT Uterine leiomyomas (UL) are the most prevalent symptomatic human tumors at all and somatic mutations of the gene encoding mediator subcomplex 12 ( MED12 ) constitute the most frequent driver mutations in UL. Recently, a rapid loss of mutated cells during in vitro growth of UL-derived cell cultures was reported, resulting in doubts about the benefits of UL-derived cell cultures. To evaluate if the rapid loss of MED12 -mutated cells in UL cell cultures depends on in vitro passaging, we set up cell cultures from nine UL from 40–50 year old Caucasian patients with at least one UL. Cultured UL cells were investigated for loss of MED12 -mutated cells. Genetic characterization of native tumor samples and adjacent myometrium was done by array analysis. “Aged” primary cultures without passaging were compared to cells of three subsequent passages. Comparative analyses of the mutated/non-mutated ratios between native tissue, primary cells, and cultured tumor cells revealed a clear decrease of MED12 -mutated cells. None of the tumors showed gross alterations of the array profiles, excluding the presence of gross genomic imbalances besides the MED12 mutations as a reason for the intertumoral variation in the loss of MED12 -mutated cells. Albeit at a lesser rate, loss of MED12 -mutated cells from cell cultures of UL occurs even without passaging thus indicating the requirement of soluble factors or matrix components lacking in vitro . Identification of these factors can help to understand the mechanisms of the growth of the most frequent type of uterine leiomyomas and to decipher novel drug targets.