Glyphosate induces growth of estrogen receptor alpha positive cholangiocarcinoma cells via non-genomic estrogen receptor/ERK1/2 signaling pathway

Previous studies showed that glyphosate stimulates breast cancer cell growth via estrogen receptors. The present study investigated the effect of glyphosate on the estrogen signaling pathway involved in the induction of cholangiocarcinoma (CCA) cell growth. HuCCA-1, RMCCA-1 and MMNK-1 were chosen for comparison. The effects of glyphosate on cell growth, cell cycle and molecular signaling pathways were measured. The results showed that HuCCA-1 cells expressed estrogen receptor alpha (ER alpha), while ER alpha was not detected in RMCCA-1 and MMNK-1 cells. ER alpha was mostly expressed in cytoplasmic compartment of HuCCA-1 cells. Estradiol (E2) (10(-11)-10(-5) M) induced cell proliferation in HuCCA-1 but not in RMCCA-1 and MMNK-1 cells. Glyphosate at the same concentration range also induced HuCCA-1 cell proliferation. The S phase of the cell cycle, and protein levels of the cyclin family were significantly increased after treatment of glyphosate or E2. Both compounds also induced the expression of proliferative signaling-related proteins including ER alpha, VEGFR2, pERK, PI3K(p85), and PCNA. These effects of glyphosate and E2 were abolished by the ER antagonist, 4-hydroxytamoxifen and U0126, a MEK inhibitor. The data from this study indicate that glyphosate can induce cell growth in ERa positive CCA cells through non-genomic estrogen receptor/ERK1/2 signaling pathway.