The Hippo signaling pathway controls organ size and tumorigenesis through a kinase cascade that inactivates Yes-associated protein (YAP). Here, we show that YAP plays a central role in controlling the progression of cervical cancer. Our results suggest that YAP expression is associated with a poor prognosis for cervical cancer. TGF-α and amphiregulin (AREG), via EGFR, inhibit the Hippo signaling pathway and activate YAP to induce cervical cancer cell proliferation and migration. Activated YAP allows for up-regulation of TGF-α, AREG, and EGFR, forming a positive signaling loop to drive cervical cancer cell proliferation. HPV E6 protein, a major etiological molecule of cervical cancer, maintains high YAP protein levels in cervical cancer cells by preventing proteasome-dependent YAP degradation to drive cervical cancer cell proliferation. Results from human cervical cancer genomic databases and an accepted transgenic mouse model strongly support the clinical relevance of the discovered feed-forward signaling loop. Our study indicates that combined targeting of the Hippo and the ERBB signaling pathways represents a novel therapeutic strategy for prevention and treatment of cervical cancer.

Mechanisms underlying ovarian cancer initiation and progression are unclear. Herein, we report that the Yes-associated protein (YAP), a major effector of the Hippo tumor suppressor pathway, interacts with ERBB signaling pathways to regulate the initiation and progression of ovarian cancer. Immunohistochemistry studies indicate that YAP expression is associated with poor clinical outcomes in patients. Overexpression or constitutive activation of YAP leads to transformation and tumorigenesis in human ovarian surface epithelial cells, and promotes growth of cancer cells in vivo and in vitro. YAP induces expression of EGF receptors (EGFR, ERBB3) and production of EGF-like ligands (HBEGF, NRG1 and NRG2). HBEGF or NRG1, in turn, activates YAP and stimulates cancer cell growth. Knockdown of ERBB3 or HBEGF eliminates YAP effects on cell growth and transformation, while knockdown of YAP abrogates NRG1- and HBEGF-stimulated cell proliferation. Collectively, our study demonstrates the existence of HBEGF&NRGs/ERBBs/YAP/HBEGF&NRGs autocrine loop that controls ovarian cell tumorigenesis and cancer progression.

Land use is one of the key factors affecting soil erosion in the Loess Plateau of China. This paper examines soil erosion under different land uses and land-use combinations using 137 Cs tracing in the Yangjuangou Catchment, a tributary of the Yan River in the Loess Plateau of Northern Shaanxi Province. The results show that the order of 137 Cs activity in different land uses decreases sequentially from mature forest to grass to young forest to orchard to terrace crop, indicating that the mature forests had the lowest erosion rates while the terraced cropland produced the highest erosion amount. The majority of 137 Cs is distributed in the top 0-10 cm of the soil layer. The 137 Cs activity in mature forest and grass soil is signifi cantly higher than in other land uses. Three land-use combinations on the hillslope were selected to study the relationship between land-use combination and soil erosion. The mixtures of 'grass (6 years old) + mature forest (25 years old) + grass (25 years old)' and 'grass (6 years old) + young forest (6 years old) + mature forest (25 years old) + grass (25 years old)' are better for soil erosion control, lowering soil erosion amount by 42% compared with a land-use combination of 'grass (6 years old) and shrub (6 years old)'. The results provide an important basis for optimizing land-use combinations to control soil erosion on slopes and may also result in important ecological benefi ts.

The Hippo signaling pathway has been implicated as a conserved regulator of organ size in both Drosophila and mammals. Yes associated protein (YAP), the central component of the Hippo signaling cascade, functions as an oncogene in several malignancies. Ovarian granulosa cell tumors (GCT) are characterized by enlargement of ovary, excess production of estrogen, high frequency of recurrence and potential of malignancy and metastasis. Whether the Hippo pathway plays a role in the pathogenesis of GCT is unknown. This study was conducted to examine the expression of YAP in human adult GCTs and to determine the role of YAP in the proliferation and steroidogenesis of GCT cells. Compared with age-matched normal human ovaries, GCT tissues exhibited higher levels of YAP expression. YAP protein was predominantly expressed in the nucleus of tumor cells, whereas the non-tumor ovarian stromal cells expressed very low levels of YAP. YAP was also expressed in cultured primary human granulosa cells and in KGN and COV434 GCT cell lines. siRNA-mediated knockdown of YAP in KGN cells resulted in a significant reduction in cell proliferation (P<0.001). Conversely, overexpression of wild-type YAP or a constitutively active YAP mutant resulted in a significant increase in KGN cell proliferation and migration. Moreover, YAP knockdown reduced FSH-induced aromatase (CYP19A1) protein expression and estrogen production in KGN cells. These results demonstrate that YAP plays an important role in regulating GCT cell proliferation, migration and steroidogenesis. Targeting the Hippo/YAP pathway may provide a novel therapeutic approach for GCT.

Adult human bone marrow-derived stem cells, having the ability to differentiate into cells of multiple lineages, have been isolated and propagated by varied protocols, including positive (CD105(+))/negative (CD45(-)GlyA(-)) selection with immunomagnetic beads, or direct plating into selective culture media. Each substratum-adherent cell population was subjected to a systematic analysis of their cell surface markers and differentiation potential. In the initial stages of culture, each cell population proliferated slowly, reaching confluence in 10-14 days. Adherent cells proliferated at similar rates whether cultured in serum-free medium supplemented with basic fibroblast growth factor, medium containing 2% fetal bovine serum (FBS) supplemented with epidermal growth factor and platelet-derived growth factor, or medium containing 10% FBS alone. Cell surface marker analysis revealed that more than 95% of the cells were positive for CD105/endoglin, a putative mesenchymal stem cell marker, and negative for CD34, CD31, and CD133, markers of hematopoietic, endothelial, and neural stem cells, respectively, regardless of cell isolation and propagation method. CD44 expression was variable, apparently dependent on serum concentration. Functional similarity of the stem cell populations was also observed, with each different cell population expressing the cell type-specific markers beta-tubulin, type II collagen, and desmin, and demonstrating endothelial tube formation when cultured under conditions favoring neural, cartilage, muscle, and endothelial cell differentiation, respectively. On the basis of these data, adult human bone marrow-derived stem cells cultured in adherent monolayer are virtually indistinguishable, both physically and functionally, regardless of the method of isolation or proliferative expansion.

The G-protein-coupled estrogen receptor 1 (GPER) has recently been reported to mediate the non-genomic action of estrogen in different types of cells and tissues. G-1 (1-[4-(6-bromobenzo[1,3] dioxol-5yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone) was developed as a potent and selective agonist for GPER. G-1 has been shown to induce the expression of genes and activate pathways that facilitate cancer cell proliferation by activating GPER. Here we demonstrate that G-1 has an anticancer potential with a mechanism similar to vinca alkaloids, the commonly used chemotherapy drugs. We found that G-1 blocks tubulin polymerization and thereby interrupts microtubule assembly in ovarian cancer cells leading to the arrest of cell cycle in the prophase of mitosis and the suppression of ovarian cancer cell proliferation. G-1 treatment also induces apoptosis of ovarian cancer cells. The ability of G-1 to target microtubules to suppress ovarian cancer cell proliferation makes it a promising candidate drug for treatment of ovarian cancer.

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Although the role of the Hippo signaling pathway in development and tumorigenesis has been extensively studied in multiple organs, its role in ovarian follicle development remains largely unknown. Here, we report that Yes‐Associated Protein 1 (YAP1), the major effector of Hippo signaling, is spatiotemporally expressed in ovarian granulosa cells and plays a critical role in the regulation of follicle development. We found that the active form of YAP1 (nuclear YAP1) was predominantly expressed in proliferative granulosa cells, whereas the inactive form of YAP1 (cytoplasmic YAP1) was mainly detected in luteal cells (terminally differentiated granulosa cells). Pharmacological inhibition of YAP1 activity disrupted mouse ovarian follicle development in vitro and in vivo. Foxl2 promoter–driven knockout of Yap1 in ovarian granulosa cells resulted in increased apoptosis of granulosa cells, decreased number of corpora lutea, reduced ovarian size, and subfertility in transgenic mice. However, Cyp19a1 promoter–driven knockout of Yap1 in differentiated granulosa cells of preovulatory follicles and luteal cells of corpora lutea had no effect on ovarian morphology and fertility. Mechanistic studies demonstrated that YAP1 interacted with epidermal growth factor receptor and TGF‐β signaling pathways to regulate granulosa cell proliferation, differentiation, and survival. Results from this study identify YAP1 as a critical regulator of granulosa cell proliferation and differentiation. Balanced expression and activation of YAP1 is essential for follicle development and successful reproduction. YAP1 is a promising target for treatment of subfertility associated with abnormal granulosa cell function.—Lv, X., He, C., Huang, C., Wang, H., Hua, G., Wang, Z., Zhou, J., Chen, X., Ma, B., Timm, B. K., Maclin, V., Dong, J., Rueda, B. R., Davis, J. S., Wang, C. Timely expression and activation of YAP1 in granulosa cells is essential for ovarian follicle development. FASEB J. 33, 10049–10064 (2019). http://www.fasebj.org