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Eribulin, an inhibitor of microtubule dynamics, is used for treating breast cancers and sarcomas. The microtubule-destabilizing protein stathmin may modulate the antiproliferative activity of eribulin on breast cancer cells and leiomyosarcoma cells. The antitumor activity of eribulin in ovarian cancers has not been fully explored, so the present study aimed to determine the antitumor efficacy of eribulin and the involvement of stathmin in ovarian cancers. In a xenograft model of ovarian cancer, eribulin treatment reduced the tumor weight, which was accompanied by an increased level of phosphorylated stathmin. Eribulin stimulated the phosphorylation of stathmin in cultured cancer cell lines. The eribulin-induced phosphorylation of stathmin was inhibited by treatment with FTY720, an activator of protein phosphatase 2A (PP2A), and eribulin downregulated the expression of PP2A subunits. Furthermore, stathmin knockdown abrogated the inhibitory effects of eribulin on cell viability. Eribulin enhanced the antiproliferative effects of paclitaxel and concomitantly decreased stathmin expression. These results suggest that eribulin-induced phosphorylation of stathmin, mediated in part by PP2A downregulation, reduces stathmin activity and enhances the antiproliferative effects of paclitaxel in ovarian cancer. Collectively, the results of this study indicate that eribulin may suppress the proliferation of ovarian cancer cells partly by regulating the activity of stathmin.

Decidualization - the differentiation of endometrial stromal cells (ESCs) into decidual cells - is a crucial step for successful embryo implantation and placentation that is initiated in the secretory phase of the menstrual cycle. During decidualization, ESCs undergo proliferation arrest and secrete inflammatory mediators, including senescence-associated secretory phenotype (SASP). Although several senolytic agents improve age-related diseases, their effects on cellular senescence in decidualizing ESCs has not been explored. To do this, we treated decidualized ESCs with the senolytic agents Quercetin (Que), Dasatinib (Das), and BPTES. Que decreased the number of senescence-associated β-galactosidase (SA-β-Gal) positive cells and expression of senescence markers in ESCs treated with the decidual stimulus (dibutyryl-cAMP plus progesterone: DP). Concomitantly, Que markedly increased the expression of the decidualization markers IGFBP1, PRL, and FOXO1, in decidualizing ESCs. Similar to Que, Das also stimulated decidualization. Treatment with a combination of Que and Das synergistically increased the expression of decidualization markers and senescence markers compared with treatment with Que or Das alone. However, BPTES did not enhance the expression of decidualization markers. These results imply that treatment with Que and/or Das can remove senescent decidual cells and enhance the decidualization of the rest of ESCs. Thus, senolytic modulation of abnormal ESC decidualization could alleviate infertility caused by dysfunctions of endometrial receptivity and embryo implantation.

Endometriosis is characterized by the presence of inflamed and fibrotic endometrial tissue outside the uterine cavity. Previously, we found decreased SERPINA1 (alpha-1 antitrypsin) expression in endometriosis-like lesions in a mouse model of endometriosis, suggesting that it exacerbated inflammation in these lesions. However, the molecular mechanism(s) by which SERPINA1 affects expression of inflammatory factors and development of endometriotic lesions have not been fully characterized. To investigate the role of intracellular SERPINA1 in endometrial stromal cells (ESCs), we performed RNA sequence analysis using RNA extracted from ESCs in which SERPINA1 was knocked down. The analysis identified several toll-like receptor (TLR)-related factors as being upregulated. Silencing of SERPINA1 increased expression of TLR3 and TLR4 in ESCs, as well as several TLR signaling pathway components, including MYD88, IRAK1/4, interleukin (IL)-1β, and interferon (IFN)-β. TLR3 or TLR4 agonists increased expression of inflammatory factors in SERPINA1-knockdown ESCs, whereas TLR3 or TLR4 inhibitors decreased expression. In addition, treatment with recombinant IL-1β or IFN-β increased expression of MYD88 and inflammatory factors in ESCs. Immunohistochemical analysis of endometriotic tissues showed that TLR3, TLR4, and MYD88 were localized in endometriosis lesions. Taken together, the data suggest that reduced expression of SERPINA1 induces expression of inflammatory factors by ESCs, which in turn are associated with TLR3/4, IL-1β, and IFN-β signaling. Regulation of intracellular SERPINA1 levels in ESCs may be a strategy to inhibit inflammatory responses in endometriotic lesions.

The pathogenesis of hypertensive disorder of pregnancy (HDP), which affects about 10% of pregnant women, is still incompletely understood. Our previous study showed that endoplasmic reticulum (ER) stress influences high-temperature requirement A serine peptidase 1 (HTRA1) expression and trophoblast invasion. However, the involvement of ER stress in the regulation of HTRA subtype expression and pathophysiology of HDP has not been characterized in extravillous trophoblasts (EVTs). To investigate this, HTR8/SVneo EVTs cell line was treated with the ER stress inducers Thapsigargin (Thap) or Tunicamycin (Tuni). Treatment with either Thap or Tuni inhibited trophoblast invasion, reduced HTRA1 and HTRA3 expression, but did not alter HTRA2 or HTRA4 expression. Knockdown of HTRA1 or HTRA3 also inhibited trophoblast invasion. Furthermore, treatment with either ER stress inducer or HTRA1 silencing increased the ratio of soluble fms-like tyrosine kinase-1/placental growth factor (sFLT1/PlGF), which is a marker of HDP. Immunohistochemical analysis revealed that HTRA1 is localized to EVTs and the endometrial decidua in the placenta of patients with HDP. These results suggest that factors that cause ER stress could result in the inhibition of EVTs invasion via HTRA1.

Endometriosis is characterized by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal hemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, menstruation-related factors, PGE2 and thrombin (P/T), a PAR1 agonist induced epithelial-mesenchymal transition (EMT) of endometrial cells under hypoxia. However, the molecular mechanisms by which P/T induce development of endometriosis have not been fully characterized. To investigate the effects of P/T, RNA extracted from endometrial stromal cells (ESCs) treated with P/T were subjected to RNA sequence analysis, and identified activin A, FOS, and GATA2 as upregulated genes. Activin A increased the expression of connective tissue growth factor (CTGF) and mesenchymal marker genes in ESCs. CTGF induced the expression of fibrosis marker type I collagen, fibronectin, and α-smooth muscle actin (αSMA), indicating fibroblast to myofibroblast transdifferentiation (FMT) of ESCs. In addition, activin A, FOS, GATA2, CTGF, and αSMA were localized in endometriosis lesions. Taken together, our data show that P/T induces changes resembling EMT and FMT in ectopic ESCs derived from retrograde menstruation, and that these are associated with fibrotic changes in the lesions. Pharmacological means that block P/T-induced activin A and CTGF signaling may be strategies to inhibit fibrosis in endometriotic lesions.

Stathmin, a phosphoprotein that modulates microtubule dynamics, is highly expressed in breast cancer cells. Eribulin, a microtubule‐depolymerizing agent, is used to treat patients with advanced breast cancer. However, the detailed mechanisms underlying the action of eribulin during microtubule catastrophe, and the interaction between eribulin and stathmin dynamics, remain unclear. Here, we investigated the role of stathmin in the antiproliferative activity of eribulin in breast cancer cells. Eribulin induced phosphorylation of stathmin in MCF7 and MDA‐MB‐231 cells; this was attenuated by an inhibitor of protein kinase A (H89) and an inhibitor of Ca2+/calmodulin‐dependent kinase II (KN62). In addition, expression of phosphorylated stathmin was reduced by the protein phosphatase PP2A activator FTY720 but increased by the PP2A inhibitor okadaic acid. Of note, expression of PP2A subunits in eribulin‐treated cells decreased, although eribulin did not affect the phosphatase activity of recombinant PP2A directly. Furthermore, the antiproliferative effect of eribulin was stronger in stathmin‐overexpressing cells. These results suggest that stathmin dynamics are closely associated with the antiproliferative effects of eribulin and stathmin is a possible biomarker for predicting the therapeutic effects of eribulin in breast cancer patients., Eribulin, a microtubule targeting agent phosphorylates stathmin by activating the PKA and CaMKII pathways, and by downregulating PP2A level in breast cancer cells. Overexpression of stathmin potentiates the antiproliferative effects of eribulin.

The appropriate differentiation of endometrial stromal cells (ESCs) into decidual cells is required for embryo implantation and subsequent placentation into humans. Decidualization is accompanied by the appearance of senescent-like cells. We recently reported the secretory phase-specific downregulation of endometrial progesterone receptor membrane component 1 (PGRMC1) and enhanced decidualization upon PGRMC1 knockdown and inhibition in cultured ESCs. However, it remains unknown whether PGRMC1 is involved in cellular senescence during decidualization. Here, we showed that the small interfering RNA (siRNA)-mediated knockdown of PGRMC1 and the inhibition of PGRMC1 by AG-205 increased the expression of the transcription factor forkhead box protein O1 (FOXO1) and the senescence-associated β-galactosidase activity in cAMP analog- and progesterone-treated ESCs. Furthermore, the knockdown of FOXO1 repressed the decidual senescence induced by siRNA-based PGRMC1 knockdown or AG-205 treatment. Taken together, the decreased PGRMC1 expression in ESCs may accelerate decidualization and cellular senescence via the upregulation of FOXO1 expression for appropriate endometrial remodeling and embryo implantation during the secretory phase.