γ-Secretase inhibition affects viability, apoptosis, and the stem cell phenotype of endometriotic cells

Ferulic acid, ligustrazine, and tetrahydropalmatine display the anti-proliferative effect in endometriosis through regulating Notch pathway

AIMS

With an ambiguous anti-proliferative mechanism, the combination of ferulic acid, ligustrazine, and tetrahydropalmatine (FLT) shows good anti-endometriosis (EMS) activity. In EMS, the expression of Notch pathway and its role in proliferation are not yet unclear. In this study, we sought to uncover the role of Notch pathway's effect and FLT's anti-proliferative mechanism on EMS proliferation.

MAIN METHODS

In autograft and allograft EMS models, the proliferating markers (Ki67, PCNA), Notch pathway, and the effect of FLT on them were detected. Then, the anti-proliferative influence of FLT was measured in vitro. The proliferating ability of endometrial cells was investigated with a Notch pathway activator (Jagged 1 or VPA) or inhibitor (DAPT) alone, or in combination with FLT separately.

KEY FINDINGS

FLT presented the inhibitory effect on ectopic lesions in 2 EMS models. The proliferating markers and Notch pathway were promoted in ectopic endometrium, but FLT showed the counteraction. Meantime, FLT restrained the endometrial cell growth and clone formation along with a reduction in Ki67 and PCNA. Jagged 1 and VPA stimulated the proliferation. On the contrary, DAPT displayed the anti-proliferating effect. Furthermore, FLT exhibited an antagonistic effect on Jagged 1 and VPA by downregulating Notch pathway and restraining proliferation. FLT also displayed a synergistic effect on DAPT.

SIGNIFICANCE

This study indicated that the overexpressing Notch pathway induced EMS proliferation. FLT attenuated the proliferation by inhibiting Notch pathway.

The Musashi RNA-binding proteins in female cancers: insights on molecular mechanisms and therapeutic relevance

RNA-binding proteins have increasingly been identified as important regulators of gene expression given their ability to bind distinct RNA sequences and regulate their fate. Mounting evidence suggests that RNA-binding proteins are involved in the onset and progression of multiple malignancies, prompting increasing interest in their potential for therapeutic intervention.The Musashi RNA binding proteins Musashi-1 and Musashi-2 were initially identified as developmental factors of the nervous system but have more recently been found to be ubiquitously expressed in physiological tissues and may be involved in pathological cell behavior. Both proteins are increasingly investigated in cancers given dysregulation in multiple tumor entities, including in female malignancies. Recent data suggest that the Musashi proteins serve as cancer stem cell markers as they contribute to cancer cell proliferation and therapy resistance, prompting efforts to identify mechanisms to target them. However, as the picture remains incomplete, continuous efforts to elucidate their role in different signaling pathways remain ongoing.In this review, we focus on the roles of Musashi proteins in tumors of the female - breast, endometrial, ovarian and cervical cancer - as we aim to summarize current knowledge and discuss future perspectives.

Revisiting the Syndecans: Master Signaling Regulators with Prognostic and Targetable Therapeutic Values in Breast Carcinoma

Syndecans (SDC1 to 4), a family of cell surface heparan sulfate proteoglycans, are frequently expressed in mammalian tissues. SDCs are aberrantly expressed either on tumor or stromal cells, influencing cancer initiation and progression through their pleiotropic role in different signaling pathways relevant to proliferation, cell-matrix adhesion, migration, invasion, metastasis, cancer stemness, and angiogenesis. In this review, we discuss the key roles of SDCs in the pathogenesis of breast cancer, the most common malignancy in females worldwide, focusing on the prognostic significance and molecular regulators of SDC expression and localization in either breast tumor tissue or its microenvironmental cells and the SDC-dependent epithelial–mesenchymal transition program. This review also highlights the molecular mechanisms underlying the roles of SDCs in regulating breast cancer cell behavior via modulation of nuclear hormone receptor signaling, microRNA expression, and exosome biogenesis and functions, as well as summarizing the potential of SDCs as promising candidate targets for therapeutic strategies against breast cancer.

Impact of Musashi-1 and Musashi-2 Double Knockdown on Notch Signaling and the Pathogenesis of Endometriosis

The stem cell marker and RNA-binding protein Musashi-1 is overexpressed in endometriosis. Musashi-1-siRNA knockdown in Ishikawa cells altered the expression of stem cell related genes, such as OCT-4. To investigate the role of both human Musashi homologues (MSI-1 and MSI-2) in the pathogenesis of endometriosis, immortalized endometriotic 12-Z cells and primary endometriotic stroma cells were treated with Musashi-1- and Musashi-2-siRNA. Subsequently, the impact on cell proliferation, cell apoptosis, cell necrosis, spheroid formation, stem cell phenotype and the Notch signaling pathway was studied in vitro. Using the ENDOMET Turku Endometriosis database, the gene expression of stem cell markers and Notch signaling pathway constituents were analyzed according to localization of the endometriosis lesions. The database analysis demonstrated that expression of Musashi and Notch pathway-related genes are dysregulated in patients with endometriosis. Musashi-1/2-double-knockdown increased apoptosis and necrosis and reduced stem cell gene expression, cell proliferation, and the formation of spheroids. Musashi silencing increased the expression of the anti-proliferation mediator p21. Our findings suggest the therapeutic potential of targeting the Musashi–Notch axis. We conclude that the Musashi genes have an impact on Notch signaling and the pathogenesis of endometriosis through the downregulation of proliferation, stemness characteristics and the upregulation of apoptosis, necrosis and of the cell cycle regulator p21.

Collagen I triggers directional migration, invasion and matrix remodeling of stroma cells in a 3D spheroid model of endometriosis

Endometriosis is a painful gynecological condition characterized by ectopic growth of endometrial cells. Little is known about its pathogenesis, which is partially due to a lack of suitable experimental models. Here, we use endometrial stromal (St-T1b), primary endometriotic stromal, epithelial endometriotic (12Z) and co-culture (1:1 St-T1b:12Z) spheroids to mimic the architecture of endometrium, and either collagen I or Matrigel to model ectopic locations. Stromal spheroids, but not single cells, assumed coordinated directional migration followed by matrix remodeling of collagen I on day 5 or 7, resembling ectopic lesions. While generally a higher area fold increase of spheroids occurred on collagen I compared to Matrigel, directional migration was not observed in co-culture or in 12Z cells. The fold increase in area on collagen I was significantly reduced by MMP inhibition in stromal but not 12Z cells. Inhibiting ROCK signalling responsible for actomyosin contraction increased the fold increase of area and metabolic activity compared to untreated controls on Matrigel. The number of protrusions emanating from 12Z spheroids on Matrigel was decreased by microRNA miR-200b and increased by miR-145. This study demonstrates that spheroid assay is a promising pre-clinical tool that can be used to evaluate small molecule drugs and microRNA-based therapeutics for endometriosis.

Uterine Stem Cells and Benign Gynecological Disorders: Role in Pathobiology and Therapeutic Implications

Stem cells in the endometrium and myometrium possess an immense regenerative potential which is necessary to maintain the menstrual cycle and support pregnancy. These cells, as well as bone marrow stem cells, have also been implicated in the development of common benign gynecological disorders including leiomyomas, endometriosis and adenomyosis. Current evidence suggests the conversion of uterine stem cells to tumor initiating stem cells in leiomyomas, endometriosis stem cells, and adenomyosis stem cells, acquiring genetic and epigenetic alterations for the progression of each benign condition. In this comprehensive review, we aim to summarize the progress that has been made to characterize the involvement of stem cells in the pathogenesis of benign gynecologic conditions which, despite their enormous burden, are not yet fully understood. We focus on the stem cell characteristics and aberrations that contribute to the development of benign gynecological disorders and the possible clinical implications of what is known so far. Lastly, we discuss the role of uterine stem cells in the setting of regenerative medicine, particularly in the treatment of Asherman syndrome.Graphical abstract.

The Heparan Sulfate Sulfotransferases HS2ST1 and HS3ST2 Are Novel Regulators of Breast Cancer Stem-Cell Properties

Heparan sulfate (HS) is a glycosaminoglycan found mainly in its protein-conjugated form at the cell surface and the extracellular matrix. Its high sulfation degree mediates functional interactions with positively charged amino acids in proteins. 2-O sulfation of iduronic acid and 3-O sulfation of glucosamine in HS are mediated by the sulfotransferases HS2ST and HS3ST, respectively, which are dysregulated in several cancers. Both sulfotransferases regulate breast cancer cell viability and invasion, but their role in cancer stem cells (CSCs) is unknown. Breast CSCs express characteristic markers such as CD44⁺/CD24^−/low, CD133 and ALDH1 and are involved in tumor initiation, formation, and recurrence. We studied the influence of HS2ST1 and HS3ST2 overexpression on the CSC phenotype in breast cancer cell lines representative of the triple-negative (MDA-MB-231) and hormone-receptor positive subtype (MCF-7). The CD44⁺/CD24^−/low phenotype was significantly reduced in MDA-MB-231 cells after overexpression of both enzymes, remaining unaltered in MCF-7 cells. ALDH1 activity was increased after HS2ST1 and HS3ST2 overexpression in MDA-MB-231 cells and reduced after HS2ST1 overexpression in MCF-7 cells. Colony and spheroid formation were increased after HS2ST1 and HS3ST2 overexpression in MCF-7 cells. Moreover, MDA-MB-231 cells overexpressing HS2ST1 formed more colonies and could not generate spheres. The phenotypic changes were associated with complex changes in the expression of the stemness-associated notch and Wnt-signaling pathways constituents, syndecans, heparanase and Sulf1. The results improve our understanding of breast CSC function and mark a subtype-specific impact of HS modifications on the CSC phenotype of triple-negative and hormone receptor positive breast cancer model cell lines.

miR-142-3p Reduces the Size, Migration, and Contractility of Endometrial and Endometriotic Stromal Cells by Targeting Integrin- and Rho GTPase-Related Pathways That Regulate Cytoskeletal Function

Downregulated microRNA-142-3p signaling contributes to the pathogenesis of endometriosis, an invasive disease where the lining of the uterus grows at ectopic locations, by yet incompletely understood mechanisms. Using bioinformatics and in vitro assays, this study identifies cytoskeletal regulation and integrin signaling as two relevant categories of miR-142-3p targets. qPCR revealed that miR-142-3p upregulation in St-T1b cells downregulates Rho-associated protein kinase 2 (ROCK2), cofilin 2 (CFL2), Ras-related C3 botulinum toxin substrate 1 (RAC1), neural Wiskott-Aldrich syndrome protein (WASL), and integrin α-V (ITGAV). qPCR and Western-blotting showed miR-142-3p effect on WASL and ITGAV was significant also in primary endometriotic stroma cells. Luciferase reporter assays in ST-T1b cells then confirmed direct regulation of ITGAV and WASL. On the functional side, miR-142-3p upregulation significantly reduced ST-T1b cell size, the size of vinculin plaques, migration through fibronectin-coated transwell filters, and the ability of ST-T1b and primary endometriotic stroma cells to contract collagen I gels. These results suggest that miR-142-3p has a strong mechanoregulatory effect on endometrial stroma cells and its external administration reduces the invasive endometrial phenotype. Within the limits of an in vitro investigation, our study provides new mechanistic insights into the pathogenesis of endometriosis and provides a perspective for the development of miR-142-3p based drugs for inhibiting invasive growth of endometriotic cells.

Knockdown of Musashi RNA Binding Proteins Decreases Radioresistance but Enhances Cell Motility and Invasion in Triple-Negative Breast Cancer

The therapeutic potential of Musashi (MSI) RNA-binding proteins, important stemness-associated gene expression regulators, remains insufficiently understood in breast cancer. This study identifies the interplay between MSI protein expression, stem cell characteristics, radioresistance, cell invasiveness and migration. MSI-1, MSI-2 and Notch pathway elements were investigated via quantitative polymerase chain reaction (qPCR) in 19 triple-negative breast cancer samples. Measurements were repeated in MDA-MB-231 cells after MSI-1 and -2 siRNA-mediated double knockdown, with further experiments performed after MSI silencing. Flow cytometry helped quantify expression of CD44 and leukemia inhibitory factor receptor (LIFR), changes in apoptosis and cell cycle progression. Proliferation and irradiation-induced effects were assessed using colony formation assays. Radiation-related proteins were investigated via Western blots. Finally, cell invasion assays and digital holographic microscopy for cell migration were performed. MSI proteins showed strong correlations with Notch pathway elements. MSI knockdown resulted in reduction of stem cell marker expression, cell cycle progression and proliferation, while increasing apoptosis. Cells were radiosensitized as radioresistance-conferring proteins were downregulated. However, MSI-silencing-mediated LIFR downregulation resulted in enhanced cell invasion and migration. We conclude that, while MSI knockdown results in several therapeutically desirable consequences, enhanced invasion and migration need to be counteracted before knockdown advantages can be fully exploited.