Elevated phosphatase of regenerating liver 3 (PRL-3) promotes cytoskeleton reorganization, cell migration and invasion in endometrial stromal cells from endometrioma

Abstract

Study question: Is phosphatase of regenerating liver-3 (PRL-3) associated with increased motility of endometriotic cells from endometrioma?

Summary answer: Elevated PRL-3 promotes cytoskeleton reorganization, cell migration and invasion of endometrial stromal cells (ESCs) from endometrioma.

What is known already: Overexpression of PRL-3 is associated with cancer cell migration, invasion and metastatic phenotype.

Study design, size, duration: Primary human ESCs were isolated from eutopic endometrium of women without endometriosis (EuCo, n = 10), with histologically proven endometrioma (EuEM, n = 19) and from the cyst wall of ovarian endometriosis (OvEM, n = 26).

Participants/materials, setting, methods: The expression of PRL-3 in ESCs derived from EuCo, EuEM and OvEM at different phases of menstrual cycle were compared. The protein and mRNA levels of PRL-3 were examined by western blot and RT-qPCR, respectively. ESCs from OvEM were transfected with/without short hairpin RNA (shRNA) or small interfering RNA (siRNA). Additionally, a plasmid-mediated delivery system was used to achieve PRL-3 overexpression in ESCs from EuEM. The cellular distribution of F-actin and α-tubulin were examined by immunocytochemistry. Cell motility was evaluated by a transwell migration/invasion assay.

Main results and the role of chance: The protein and mRNA levels of PRL-3 are significantly elevated in ESCs from OvEM compared with EuCo and EuEM. The expression of PRL-3 was not altered between proliferative phase and secretory phase in ESCs from all groups. Knockdown of PRL-3 significantly modified the distribution of F-actin and α-tubulin cytoskeleton, inhibited cell migration and invasion. Endogenous inhibition of PRL-3 attenuated the expression of Ras homolog gene family members A and C (RhoA, RhoC), Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) and matrix metalloproteinase (MMP) 9, but not MMP2 in ESCs from OvEM. Additionally, overexpression of PRL-3 in ESCs from EuEM up-regulates cell migration and invasion, and increases the expression of RhoA, RhoC, ROCK1 and MMP9.

Limitations, reasons for caution: Lack of in vivo animal studies is the major limitation of our report. Our results should be further confirmed in a larger cohort of patients and extended to include eutopic and ectopic endometrium from patients with peritoneal endometriosis at different stages of the disease.

Wider implications of the findings: Our study describes that elevated expression of PRL-3 contributes to the cell motility of ESCs from endometrioma. The results emphasize the importance of metastatic-related factor PRL-3 in the pathogenesis of endometrioma.

Study funding/competing interest: This work was supported by National Natural Science Foundation of China (No. 81170546) and Zhejiang Medicine Science and Technology Projects (No. Y13H040003). The authors declare no conflict of interest.

Keywords: Ras homolog gene family members; Rho-associated coiled-coil-containing protein kinase 1; cytoskeleton; endometrioma; endometriosis; invasion; matrix metalloproteinase; migration; phosphatase of regenerating liver-3.