SAT-723 Effects of Organohalogenated Endocrine Disrupting Chemicals on Cell Proliferation and Gene Expression in GH3 Somatolactotropes

Abstract

Endocrine Disrupting Chemicals (EDCs) are substances that have been increasingly implicated in many serious pathologies, such as tumor formation, metabolic, growth and reproductive disorders. The economic and health burden of exposure to these compounds has an annual predicted cost in excess of €150 billion, across the EU regions alone. Of the growing list of compounds that act as EDCs, the organohalogenated compounds (OHCs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) have been associated with an increased risk of pituitary disease. We have previously reported that feline patients with hypersomatotropism (acromegaly) are exposed to elevated levels of PBDEs and PCBs in their environment. However, the mechanisms by which these compounds might directly influence somatotroph function have yet to be established. In this study, we use the GH3 rat somatolactotrope cell line to investigate how two PCB congeners - 138 and 153 - influence cell proliferation (using a Crystal Violet assay) and somatotrope gene expression (using a multiplex RT-qPCR approach to examine expression of Esr1, Esr2, Sstr1, Sstr2, Sstr3, Sstr4, Sstr5, Insr, Tshr, Pou1f1, Ghrhr2, Gh). GH3 cells were treated with Phenol Red-free media in the absence or presence of either PCB138 or 153 (-10 to -6 M), or in combination (-10 to -6M) for up to 72h. Treatment with either PCB alone, or in combination, caused significant concentration-dependent, biphasic changes in cell proliferation at each time point, but with a different profile of response on each day (significantly increased at high pM/low nM concentrations); there was no evidence of toxicity at maximum concentrations (-6M). Gene expression changes were determined in GH3 cells treated in the absence or presence of either -8M or -6M PCB138 or 153 for 24h. Differential effects of these compounds were seen on the expression of Sstr3, Sstr4, Sstr5 and Insr; all other gene transcripts were unaffected. These findings reveal that GH3 cells exposed to physiologically relevant concentrations of PCB138 and 153, alone or in combination, show concentration-dependent increases in cell proliferation; furthermore, the expression of genes associated with therapeutic targets for the treatment of acromegaly (i.e. SSTRs) are differentially affected by exposure to PCB138 and 153. Our data indicate a potential mechanism for EDCs in the onset of acromegaly, that require further, in vivo, investigations.