scholarly journals SEMA6A/RhoA/YAP Axis Mediates Tumor-Stroma Interactions and Prevents Response to Dual BRAF/MEK Inhibition in BRAF-Mutant Melanoma

2021 ◽  
Author(s):  
Rossella Loria ◽  
Valentina Laquintana ◽  
Stefano Scalera ◽  
Rocco Fraioli ◽  
Valentina Caprara ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Cell Model ◽  
Therapy Resistance ◽  
Melanoma Cells ◽  
Mek Inhibition ◽  
Cytoskeleton Remodeling ◽  
Melanoma Patients ◽  
Braf Mutant

Abstract Background: Despite the promise of dual BRAF/MEK inhibition as a therapy for BRAF-mutant (BRAF-mut) melanoma, heterogeneous responses have been observed in patients, thus predictors of benefit from therapy are needed. We have previously identified semaphorin 6A (SEMA6A) as a BRAF-mut-associated protein involved in actin cytoskeleton remodeling. The purpose of the present study is to dissect the role of SEMA6A in the biology of BRAF-mut melanoma, and to explore its predictive potential towards dual BRAF/MEK inhibition.Methods: SEMA6A expression was assessed by immunohistochemistry in melanoma cohort RECI1 (N=112) and its prognostic potential was investigated in BRAF-mut melanoma patients from DFCI and TCGA datasets (N=258). The molecular mechanisms regulated by SEMA6A to sustain tumor aggressiveness and targeted therapy resistance were investigated in vitro by using BRAF-mut and BRAF-wt melanoma cell lines, an inducible SEMA6A silencing cell model and a microenvironment-mimicking fibroblasts-coculturing model. Finally, SEMA6A prediction of benefit from dual BRAF/MEK inhibition was investigated in melanoma cohort RECI2 (N=14).Results: Our results indicate higher protein expression of SEMA6A in BRAF-mut compared with BRAF-wt melanoma patients and show that SEMA6A is a prognostic indicator in BRAF-mut melanoma from TCGA and DFCI patients cohorts. In BRAF-mut melanoma cells, SEMA6A coordinates actin cytoskeleton remodeling by the RhoA-dependent activation of YAP and dual BRAF/MEK inhibition by dabrafenib+trametinib induces SEMA6A/RhoA/YAP axis. In microenvironment-mimicking co-culture condition, fibroblasts confer to melanoma cells a proliferative stimulus and protect them from targeted therapies, whereas SEMA6A depletion rescues the efficacy of dual BRAF/MEK inhibition. Finally, in BRAF-mut melanoma patients treated with dabrafenib+trametinib, high SEMA6A predicts shorter recurrence-free interval. Conclusions: Overall, our results indicate that SEMA6A contributes to microenvironment-coordinated evasion of melanoma cells from dual BRAF/MEK inhibition and it might be a good candidate predictor of short-term benefit from dual BRAF/MEK inhibition.

scholarly journals Bilirubin Restrains the Anticancer Effect of Vemurafenib on BRAF-Mutant Melanoma Cells Through ERK-MNK1 Signaling

2021 ◽  
Vol 11 ◽  
Author(s):  
Yufan Tan ◽  
Xiaoyu Zhong ◽  
Xizhi Wen ◽  
Leyi Yao ◽  
Zhenlong Shao ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Animal Experiments ◽  
Underlying Mechanism ◽  
Melanoma Cells ◽  
Anticancer Effect ◽  
Braf Mutations ◽  
Melanoma Patients ◽  
Induced Apoptosis ◽  
Braf Mutant

Melanoma, the most threatening cancer in the skin, has been considered to be driven by the carcinogenic RAF-MEK1/2-ERK1/2 signaling pathway. This signaling pathway is usually mainly dysregulated by mutations in BRAF or RAS in skin melanomas. Although inhibitors targeting mutant BRAF, such as vemurafenib, have improved the clinical outcome of melanoma patients with BRAF mutations, the efficiency of vemurafenib is limited in many patients. Here, we show that blood bilirubin in patients with BRAF-mutant melanoma treated with vemurafenib is negatively correlated with clinical outcomes. In vitro and animal experiments show that bilirubin can abrogate vemurafenib-induced growth suppression of BRAF-mutant melanoma cells. Moreover, bilirubin can remarkably rescue vemurafenib-induced apoptosis. Mechanically, the activation of ERK-MNK1 axis is required for bilirubin-induced reversal effects post vemurafenib treatment. Our findings not only demonstrate that bilirubin is an unfavorable for patients with BRAF-mutant melanoma who received vemurafenib treatment, but also uncover the underlying mechanism by which bilirubin restrains the anticancer effect of vemurafenib on BRAF-mutant melanoma cells.

scholarly journals The TGFβ Family in Human Placental Development at the Fetal-Maternal Interface

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 453
Author(s):  
Susana M. Chuva de Sousa Lopes ◽  
Marta S. Alexdottir ◽  
Gudrun Valdimarsdottir
Keyword(s):  
Stem Cell ◽  
Transforming Growth Factor Beta ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Cell Model ◽  
Embryonic Stem ◽  
Model Systems ◽  
Special Focus ◽  
Placental Development

Emerging data suggest that a trophoblast stem cell (TSC) population exists in the early human placenta. However, in vitro stem cell culture models are still in development and it remains under debate how well they reflect primary trophoblast (TB) cells. The absence of robust protocols to generate TSCs from humans has resulted in limited knowledge of the molecular mechanisms that regulate human placental development and TB lineage specification when compared to other human embryonic stem cells (hESCs). As placentation in mouse and human differ considerably, it is only with the development of human-based disease models using TSCs that we will be able to understand the various diseases caused by abnormal placentation in humans, such as preeclampsia. In this review, we summarize the knowledge on normal human placental development, the placental disease preeclampsia, and current stem cell model systems used to mimic TB differentiation. A special focus is given to the transforming growth factor-beta (TGFβ) family as it has been shown that the TGFβ family has an important role in human placental development and disease.

scholarly journals MAP Kinase Pathway Alterations in BRAF-Mutant Melanoma Patients with Acquired Resistance to Combined RAF/MEK Inhibition

2013 ◽  
Vol 4 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Nikhil Wagle ◽  
Eliezer M. Van Allen ◽  
Daniel J. Treacy ◽  
Dennie T. Frederick ◽  
Zachary A. Cooper ◽  
...  
Keyword(s):  
Map Kinase ◽  
Acquired Resistance ◽  
Mek Inhibition ◽  
Melanoma Patients ◽  
Map Kinase Pathway ◽  
Braf Mutant ◽  
Kinase Pathway

scholarly journals ROS-Induced GATA4 and GATA6 Downregulation Inhibits StAR Expression in LPS-Treated Porcine Granulosa-Lutein Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Xiaolu Qu ◽  
Leyan Yan ◽  
Rihong Guo ◽  
Hui Li ◽  
Zhendan Shi
Keyword(s):  
Molecular Mechanisms ◽  
Cell Model ◽  
Animal Husbandry ◽  
Dependent Manner ◽  
Progesterone Production ◽  
Progesterone Synthesis ◽  
Porcine Granulosa Cell ◽  
Underlying Mechanisms ◽  
Dose Dependent

LPS is a major endotoxin produced by gram-negative bacteria, and exposure to it commonly occurs in animal husbandry. Previous studies have shown that LPS infection disturbs steroidogenesis, including progesterone production, and subsequently decreases animal reproductive performance. However, little information about the underlying mechanisms is available thus far. In the present study, an in vitro-luteinized porcine granulosa cell model was used to study the underlying molecular mechanisms of LPS treatment. We found that LPS significantly inhibits progesterone production and downregulates the expressions of progesterone synthesis-associated genes (StAR, CYP11A1, and 3β-HSD). Furthermore, the levels of ROS were significantly increased in an LPS dose-dependent manner. Moreover, transcriptional factors GATA4 and GATA6, but not NR5A1, were significantly downregulated. Elimination of LPS-stimulated ROS by melatonin or vitamin C could restore the expressions of GATA4, GATA6, and StAR. In parallel, StAR expression was also inhibited by the knockdown of GATA4 and GATA6. Based on these data, we conclude that LPS impairs StAR expression via the ROS-induced downregulation of GATA4 and GATA6. Collectively, these findings provide new insights into the understanding of reproductive losses in animals suffering from bacterial infection and LPS exposure.

scholarly journals Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals—Illustrated with Four Actin Cytoskeleton Proteins

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 672 ◽  
Author(s):  
Zain Akram ◽  
Ishtiaq Ahmed ◽  
Heike Mack ◽  
Ramandeep Kaur ◽  
Richard C. Silva ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Budding Yeast ◽  
Animal Cell ◽  
Molecular Genetic ◽  
In Vivo Studies ◽  
Yeast Saccharomyces Cerevisiae ◽  
Higher Eukaryotes

The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.

scholarly journals Pak2 is required for actin cytoskeleton remodeling, TCR signaling, and normal thymocyte development and maturation

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Hyewon Phee ◽  
Byron B Au-Yeung ◽  
Olga Pryshchep ◽  
Kyle Leonard O'Hagan ◽  
Stephanie Grace Fairbairn ◽  
...  
Keyword(s):  
T Cell ◽  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Thymocyte Development ◽  
Tcr Signaling ◽  
Critical Function ◽  
Cytoskeletal Remodeling ◽  
Single Positive ◽  
Cytoskeleton Remodeling ◽  
P21 Activated Kinase

The molecular mechanisms that govern thymocyte development and maturation are incompletely understood. The P21-activated kinase 2 (Pak2) is an effector for the Rho family GTPases Rac and Cdc42 that regulate actin cytoskeletal remodeling, but its role in the immune system remains poorly understood. In this study, we show that T-cell specific deletion of Pak2 gene in mice resulted in severe T cell lymphopenia accompanied by marked defects in development, maturation, and egress of thymocytes. Pak2 was required for pre-TCR β-selection and positive selection. Surprisingly, Pak2 deficiency in CD4 single positive thymocytes prevented functional maturation and reduced expression of S1P1 and KLF2. Mechanistically, Pak2 is required for actin cytoskeletal remodeling triggered by TCR. Failure to induce proper actin cytoskeletal remodeling impaired PLCγ1 and Erk1/2 signaling in the absence of Pak2, uncovering the critical function of Pak2 as an essential regulator that governs the actin cytoskeleton-dependent signaling to ensure normal thymocyte development and maturation.

scholarly journals Molecular Mechanisms of Anti-Melanogenic Gedunin Derived from Neem Tree (Azadirachta indica) Using B16F10 Mouse Melanoma Cells and Early-Stage Zebrafish

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 330
Author(s):  
Hwang-Ju Jeon ◽  
Kyeongnam Kim ◽  
Chaeeun Kim ◽  
Myoung-Jin Kim ◽  
Tae-Oh Kim ◽  
...  
Keyword(s):  
Skin Color ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Melanoma Cells ◽  
Ultraviolet Rays ◽  
Melanin Production ◽  
Zebrafish Model ◽  
Mouse Melanoma

Melanogenesis represents a series of processes that produce melanin, a protective skin pigment (against ultraviolet rays), and determines human skin color. Chemicals reducing melanin production have always been in demand in the cosmetic market because of skincare interests, such as whitening. The main mechanism for inhibiting melanin production is the inhibition of tyrosinase (TYR), a key enzyme for melanogenesis. Here, we evaluated gedunin (Ged), a representative limonoid, for its anti-melanogenesis action. Melanin production in vitro was stimulated by alpha-melanocyte stimulating hormone (α-MSH) in B16F10 mouse melanoma cells. Ged reduced α-MSH-stimulated melanin production, inhibiting TYR activity and protein amount. We confirmed this result in vivo in a zebrafish model for melanogenesis. There was no sign of toxicity and malformation of zebrafish embryos during development in all treated concentrations. Ged reduced the number of produced zebrafish embryo pigment dots and melanin contents of embryos. The highly active concentration of Ged (100 µM) was much lower than the positive control, kojic acid (8 mM). Hence, Ged could be a fascinating candidate for anti-melanogenesis reagents.

scholarly journals Pleiotropic effects of FGFR1 on cell proliferation, survival, and migration in a 3D mammary epithelial cell model

2005 ◽  
Vol 171 (4) ◽  
pp. 663-673 ◽  
Author(s):  
Wa Xian ◽  
Kathryn L. Schwertfeger ◽  
Tracy Vargo-Gogola ◽  
Jeffrey M. Rosen
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Mammary Epithelial Cell ◽  
Molecular Mechanisms ◽  
Cell Model ◽  
Smooth Muscle Actin ◽  
Three Dimensional ◽  
Mammary Epithelial ◽  
Matrix Metalloproteinase 3

Members of the fibroblast growth factor (FGF) family and the FGF receptors (FGFRs) have been implicated in mediating various aspects of mammary gland development and transformation. To elucidate the molecular mechanisms of FGFR1 action in a context that mimics polarized epithelial cells, we have developed an in vitro three-dimensional HC11 mouse mammary epithelial cell culture model expressing a drug-inducible FGFR1 (iFGFR1). Using this conditional model, iFGFR1 activation in these growth-arrested and polarized mammary acini initially led to reinitiation of cell proliferation, increased survival of luminal cells, and loss of cell polarity, resulting in the disruption of acinar structures characterized by the absence of an empty lumen. iFGFR1 activation also resulted in a gain of invasive properties and the induction of matrix metalloproteinase 3 (MMP-3), causing the cleavage of E-cadherin and increased expression of smooth muscle actin and vimentin. The addition of a pan MMP inhibitor abolished these phenotypes but did not prevent the effects of iFGFR1 on cell proliferation or survival.

scholarly journals Inhibitory effects of Lang-du extract on the in vitro and in vivo growth of melanoma cells and its molecular mechanisms of action

2010 ◽  
Vol 62 (4) ◽  
pp. 357-366 ◽  
Author(s):  
Liping Wang ◽  
Huiying Duan ◽  
Yishan Wang ◽  
Kun Liu ◽  
Peng Jiang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Melanoma Cells ◽  
Mechanisms Of Action ◽  
Inhibitory Effects ◽  
In Vivo Growth

scholarly journals The Downregulation of EIF3a Contributes to Vemurafenib Resistance in Melanoma By Activating ERK Via PPP2R1B

2021 ◽  
Author(s):  
Shilong Jiang ◽  
Zhibin Wang ◽  
Tao Zhu ◽  
Ting Jiang ◽  
Jiangfeng Fei ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Regulatory Protein ◽  
Braf Inhibitor ◽  
Melanoma Cells ◽  
Braf V600e ◽  
Luciferase Assay ◽  
Translation Regulation ◽  
Therapeutic Benefits ◽  
New Strategy ◽  
Melanoma Patients

Abstract Background: Vemurafenib, a BRAF V600E inhibitor, provides therapeutic benefits for melanoma patients, but the frequently emergence of drug resistance remains a challenge. Understanding the mechanisms behind vemurafenib resistance may generate novel therapeutic strategy for melanoma patients. Methods: KEGG analysis for eIF3a-mediated pathway and identified the KRAS pathway was significantly enriched after silencing eIF3a. The role of eIF3a in vemurafenib chemosensitivity were investigated by CCK8, and clonogenic assay. To explore the underlying molecular mechanisms of eIF3a on regulating ERK, we performed a series of overexpression and knockdown experiments. In addition, luciferase assay and RIP assay were used to demonstrate the translation regulation between eIF3a and PPP2R1B. The association between eIF3a and PPP2R1B mRNA expression was analyzed using the TCGA datasets. Results: we demonstrated that eIF3a, a translational regulatory protein, was an important mediator involved in vemurafenib resistance. EIF3a expression was significantly lower in vemurafenib-resistant A375 melanoma cells (A375R) compared with the parental A375 cells. Overexpression of eIF3a enhanced the sensitivity of BRAF inhibitor by downregulating p-ERK expression. We further revealed that eIF3a controls ERK activity though regulating the phosphatase PPP2R1B expression via translation mechanism, thus determining the sensitivity of vemurafenib in melanoma cells. In addition, the positive relationship between eIF3a and PPP2R1B was also demonstrated in tumor samples from HPA and TCGA database. Conclusion: eIF3a is a potential prognostic predictor for vemurafenib therapy, which may provide new strategy for predicting vemurafenib responses in clinical treatment.

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