Abstract
Endometriosis is generally characterized as a tumor-like disease because of its potential for distant metastasis and local tissue invasion, while whether osteopontin (OPN) plays a role in the pathogenesis of endometriosis has not been thoroughly investigated. We investigated the expression of OPN, urokinase plasminogen activator (uPA), phosphatidylinositol 3 kinase (PI3K), and phospho-PI3 kinase (p-PI3K) in endometrial stromal cells (ESCs). The serum concentration of OPN was determined by enzyme-linked immunosorbent assays (ELISA). OPN was downregulated to explore the corresponding change of uPA, p-PI3K, F-actin, and α-tubulin. The expression of OPN, uPA, PI3K, and p-PI3K was evaluated by western blot and quantitative real-time PCR (RT-qPCR) and the expression of F-actin and α-tubulin was confirmed by immunofluorescence assay. The proliferation and migration abilities of ESCs were investigated by CCK8, transwell, and wound scratch assays. Endometrial OPN, p-PI3K, and uPA expressions and serum OPN levels were increased in patients with endometriosis compared with the control. The expressions of p-PI3K, uPA, and α-tubulin were decreased by siRNA-OPN interference in ectopic ESCs. Activation and inhibition of the PI3K pathway apparently upregulate and downregulate uPA expression. Knockdown of OPN and inhibition of the PI3K pathway remarkably inhibited cell migration in ectopic ESCs. Meanwhile, activation of the PI3K pathway promoted the migration ability of ectopic ESCs. OPN may regulate the expression of uPA through the PI3K signal pathway to affect the migration ability of ESCs, indicating that OPN, uPA, and the PI3K pathway may be potential targets for interrupting development of endometriosis.
Highlights
Endometriosis, defined as the implantation and periodic growth of endometrial glands and stroma at extra-uterine sites, is a common benign gynecological disease with a heavy social and economic burden since symptoms of endometriosis include chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility
Most cells were positive for vimentin and negative for pan cytokeratin, which means the success of primary culture of endometrial stromal cells (ESCs)
OPN plays a crucial role in progression and metastasis in cancer through cell migration, invasion, anti-apoptosis, angiogenesis, and abnormal activated immunocytes
Summary
Endometriosis, defined as the implantation and periodic growth of endometrial glands and stroma at extra-uterine sites, is a common benign gynecological disease with a heavy social and economic burden since symptoms of endometriosis include chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility. Endometriosis is characterized as a benign disease with some properties of malignant tissues such as hyperplasia, cell invasion, and induction of metastasis [4,5,6,7,8,9] This fact suggests that certain signaling molecules and corresponding signaling pathways, playing roles in invasion and metastasis of many commonly occurring cancers, might be involved in endometriosis. Osteopontin (OPN), called secreted phosphoprotein 1 (SPP-1), is a 70-kDa secreted phosphorylated glycoprotein which is one of the important molecular targets in cancer progression and metastasis [10] It was originally isolated from bone matrix [11] and has been found in a variety of tissues including kidney, brain, pancreas, lung bronchi, secretory glands, salivary glands, lactating breast, and some tumor tissues [12,13,14,15,16]. Wound scratch, and cell counting kit-8 (CCK8) assays were conducted to evaluate the migration and proliferation abilities of ESCs
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