G Protein-coupled Estrogen Receptor 1 (GPER1) Regulates Expression of SERPINE1/PAI-1 and Inhibits Tumorigenic Potential of Cervical Squamous Cell Carcinoma Cells In Vitro.

Background/aim: G protein-coupled estrogen receptor 1 (GPER1) appears to play a tumor-suppressive role in cervical squamous cell carcinoma (CSCC)GPER1 suppression leads to significantly increased expression of serpin family E member 1 (SERPINE1)/protein plasminogen activator inhibitor type 1 (PAI-1). The question arises, what role does SERPINE1/PAI-1 play in GPER1-dependent tumorigenic potential of CSCC.

Materials and methods: SiHa and C33A CSCC cells were treated with GPER1 agonist G1 or antagonist G36. SERPINE1/PAI-1 expression was suppressed by RNAi and success was confirmed by RT-qPCR. Protein expression of PAI-1 was quantified by Western blot. Viability was analyzed using resazurin assay, while migration was investigated using gap closure. Colony and tumor sphere formation were used to test clonogenicity.

Results: After G1 treatment, viability of SiHa and C33A cells remained unchanged. Cell migration was dose-dependently reduced. SiHa and C33A cells formed significantly fewer and smaller colonies as well as spheroids. Furthermore, treatment with G1 led to decreased expression of SERPINE1/PAI-1, while blockade of GPER1 with G36 resulted in significantly increased SERPINE1/PAI-1 expression. After suppression of SERPINE1/PAI-1 in SiHa cells using RNAi, cell viability remained unaffected; however, significantly smaller colonies were formed, and fewer and smaller spheroids were developed. Cell migration remained unaffected.

Conclusion: Activation of GPER1 reduces clonogenicity and migration of CSCC cells and suppresses expression of SERPINE1/PAI-1. Suppression of SERPINE1/PAI-1 in CSCC cells reduces tumorigenic potential. GPER1 may be a suitable target for suppression of SERPINE1/PAI-1 in CSCC. However, SERPINE1/PAI-1 does not appear to be the decisive factor for GPER1-regulated cell migration.