Does YAP influence cell proliferation and apoptosis in benign epithelial odontogenic lesions?

OBJECTIVE: To analyze the immunohistochemical expression of YAP and its correlation with markers involved in cell proliferation and apoptosis in benign epithelial odontogenic lesions. STUDY DESIGN: The sample consisted of 95 cases of odontogenic lesions (25 dentigerous cysts, 30 non-syndromic odontogenic keratocysts, 30 conventional ameloblastomas, and 10 unicystic ameloblastomas) and 10 dental follicles used as normal odontogenic tissue. The histological sections were submitted to immunohistochemistry with YAP, cyclin D1, Ki-67, and Bcl-2 antibodies. Immunoexpression was analyzed qualitatively and quantitatively using an adapted method. The collected data were analyzed descriptively and statistically (p ≤ 0.05). RESULTS: The highest YAP expression was observed in odontogenic keratocysts, followed by unicystic ameloblastomas and conventional ameloblastomas, which exhibited moderate immunoreactivity predominantly in peripheral cells. Furthermore, significant differences in YAP immunoexpression were observed between the groups analyzed, with significant positive correlations between YAP and cyclin D1 in dentigerous cysts and unicystic ameloblastomas and between YAP and Ki-67 in unicystic ameloblastomas (p < 0.05). However, there were no statistically significant correlations between YAP and Bcl-2 immunoexpression in the groups studied. CONCLUSION: YAP may influence epithelial cell proliferation in odontogenic cysts and tumors, suggesting its possible participation in the progression of the odontogenic lesions studied.

ß-catenin ameliorates myocardial infarction by preventing YAP-associated apoptosis.

OBJECTIVE: To explore whether the effect of ß-catenin on MI and MI-induced cardiomyocyte apoptosis is YAP-dependent. METHODS: The authors established an MI rat model by ligating the anterior descending branch of the left coronary artery, and an MI cell model by treating cardiomyocytes with H2O2. RESULTS: ß-catenin downregulation was observed in MI cardiac tissues and in H2O2-treated cardiomyocytes. Lentiviral-CTNNB1 was administered to MI rats to upregulate ß-catenin expression in MI cardiac tissue. ß-catenin recovery reduced the myocardial infarct area, fibrosis, and apoptotic cell death in MI rats. H2O2 treatment attenuated cell viability and induced cell death in cardiomyocytes, whereas ß-catenin overexpression partially reversed these changes. Moreover, H2O2 treatment caused the deactivation of Yes-Associated Protein (YAP), as detected by increased YAP phosphorylation and reduced the nuclear localization of YAP. Upregulation of ß-catenin expression reactivated YAP in H2O2-treated cardiomyocytes. Reactivation of YAP was achieved by administration of Mitochonic Acid-5 (MA-5) to H2O2-treated cardiomyocytes, and deactivation of YAP by CIL56 treatment in ß-catenin-overexpressing H2O2-treated cardiomyocytes. MA-5 administration increased cell viability and repressed apoptosis in H2O2-treated cardiomyocytes, whereas CIL56 treatment counteracted the effects of ß-catenin overexpression on cell survival and apoptosis. CONCLUSIONS: The present data indicate that ß-catenin and YAP are effective treatment targets for MI, blocking the apoptotic death of cardiomyocytes.

Análise imuno-histoquímica da Yes-Associated Protein (YAP) e sua influência sobre a proliferação celular e a apoptose em lesões odontogênicas epiteliais benignas / Immunohistochemical analysis of Yes-Associated Protein (YAP) and its influence on cell proliferation and apoptosis in benign epithelial odontogenic lesions

Introdução: Os cistos e tumores odontogênicos são lesões que apresentam comportamento biológico heterogêneo e patogênese ainda não totalmente esclarecida. A Yes-associated protein (YAP) atua como um regulador transcricional de genes envolvidos na proliferação celular e na apoptose, participando da ativação de vias associadas ao crescimento cístico e à progressão neoplásica. Objetivo: Analisar a expressão imuno-histoquímica da proteína YAP e correlacioná-la com marcadores envolvidos na proliferação celular e na apoptose em lesões odontogênicas epiteliais benignas. Metodologia: A amostra consistiu de 95 casos de lesões odontogênicas - 25 cistos dentígeros (CDs), 30 CO não sindrômicos (COs), 30 AMB convencionais (AMB-Cs) e 10 AMB unicísticos (AMB-Us) -, além de 10 espécimes de folículo dentários (FD). Foi realizada coleta dos dados clinico-demográficos dos casos, bem como análise morfológica para melhor caracterização da amostra. Os cortes histológicos foram submetidos à técnica imuno-histoquímica através da utilização dos anticorpos YAP, ciclina D1, Ki-67 e Bcl-2, e a análise da expressão destes foi realizada quali-quantitativamente, mediante metodologia adaptada. Os dados coletados seguiram para análise descritiva e estatística (p ≤ 0,05). Resultados: Houve discreta predileção por mulheres (n = 55; 57,6%) e por indivíduos na faixa etária dos 21 aos 40 anos (n = 50; 47,6%), sendo a região posterior de mandíbula mais afetada (64%). A análise da imunoexpressão de YAP revelou maiores níveis de expressão em COs, especialmente nas camadas basal e parabasal, seguido dos AMB-Us e AMB-Cs, que demonstraram moderada imunorreatividade, predominantemente nas células periféricas. Além disso, houve diferenças significativas quanto à imunoexpressão de YAP entre os grupos analisados, com existência de correlações positivas e estatisticamente significativas entre YAP e ciclina D1 em CDs e AMB-Us, e entre YAP e Ki-67 em AMB-Us (p < 0,05). Todavia, entre a imunoexpressão YAP e Bcl-2, foi verificada ausência de correlação estatisticamente significativa. Conclusões: A YAP pode exercer influência sobre a proliferação celular do epitélio de cistos e tumores odontogênicos, auxiliando, assim, na progressão das diferentes lesões odontogênicas (AU).

Background: Odontogenic cysts and tumors present heterogeneous biological behavior, and their etiopathogenesis is not fully understood yet. Yes-associated protein (YAP) acts as a transcriptional regulator of genes involved in cell proliferation and apoptosis, activating pathways associated with cystic growth and neoplastic progression. Objective: To analyze the immunohistochemical expression of YAP protein and correlate it with markers involved in cell proliferation and apoptosis in benign epithelial odontogenic lesions. Methods: The sample consisted of 95 cases of odontogenic lesions - 25 dentigerous cysts (DCs), 30 non-syndromic odontogenic keratocyst (OKCs), 30 conventional AMB (C-AMBs), and 10 unicystic AMB (UAMBs) -, in addition to 10 specimens of dental follicles (DF). Clinicodemographic data collection was carried out, as well as morphological analysis for better characterization of the sample. The histological sections were submitted to the immunohistochemical technique using YAP, cyclin D1, Ki-67, and Bcl-2 antibodies, and their immunoexpression analysis was performed qualitatively and quantitatively, through an adapted methodology. The collected data were submitted for descriptive and statistical analysis (p ≤ 0.05). Results: There was a slight predilection for women (n = 55; 57.6%) and individuals aged between 21 and 40 years (n = 50; 47.6%), with the posterior region of the mandible as the most affected site (64%). Analysis of YAP immunoexpression revealed higher expression levels in OKCs, especially in the basal and parabasal layers, followed by U-AMBs and C-AMBs, which showed moderate immunoreactivity, predominantly in peripheral cells. In addition, there were significant differences in YAP immunoexpression between the analyzed groups, with positive and statistically significant correlations between YAP and cyclin D1 in DCs and U-AMBs, and between YAP and Ki-67 in U-AMBs (p < 0.05). However, between YAP and Bcl-2 immunoexpression, there was no statistically significant correlation. Conclusions: YAP may influence on the cell proliferation of odontogenic cysts and tumors epithelium, thus helping with the progression of the different odontogenic lesions (AU) .

β-catenin ameliorates myocardial infarction by preventing YAP-associated apoptosis

Abstract Objective: To explore whether the effect of β-catenin on MI and MI-induced cardiomyocyte apoptosis is YAP-dependent. Methods: The authors established an MI rat model by ligating the anterior descending branch of the left coronary artery, and an MI cell model by treating cardiomyocytes with H2O2. Results: β-catenin downregulation was observed in MI cardiac tissues and in H2O2-treated cardiomyocytes. Lentiviral-CTNNB1 was administered to MI rats to upregulate β-catenin expression in MI cardiac tissue. β-catenin recovery reduced the myocardial infarct area, fibrosis, and apoptotic cell death in MI rats. H2O2 treatment attenuated cell viability and induced cell death in cardiomyocytes, whereas β-catenin overexpression partially reversed these changes. Moreover, H2O2 treatment caused the deactivation of Yes-Associated Protein (YAP), as detected by increased YAP phosphorylation and reduced the nuclear localization of YAP. Upregulation of β-catenin expression reactivated YAP in H2O2-treated cardiomyocytes. Reactivation of YAP was achieved by administration of Mitochonic Acid-5 (MA-5) to H2O2-treated cardiomyocytes, and deactivation of YAP by CIL56 treatment in β-catenin-overexpressing H2O2-treated cardiomyocytes. MA-5 administration increased cell viability and repressed apoptosis in H2O2-treated cardiomyocytes, whereas CIL56 treatment counteracted the effects of β-catenin overexpression on cell survival and apoptosis. Conclusions: The present data indicate that β-catenin and YAP are effective treatment targets for MI, blocking the apoptotic death of cardiomyocytes.

Assessment of YAP gene polymorphisms and arsenic interaction in Mexican women with breast cancer.

The identification of gene-environment interactions related to breast cancer reveals the biological and molecular mechanisms underlying the disease and allows the distinction of women at high risk from women at lower risk, which could decrease the morbimortality of this neoplasm. The current study evaluated the association between polymorphisms rs1820453 and rs11225161 of the Yes-associated protein (YAP) gene in women with breast cancer exposed to arsenic (As) through drinking water. In total, 182 women were assessed for the frequency of YAP rs1820453 and rs11225161 polymorphisms and As urinary levels. The results demonstrated a positive and significant association between breast cancer and smoking, type of drinking water, and levels of AsIII , AsV and inorganic As (iAs) but not the YAP gene polymorphisms evaluated. In conclusion, our data showed that the source of drinking water and AsV and iAs urinary levels increased the risk for breast cancer, but no interactions between YAP gene polymorphisms and As urinary levels were found.

Association between YAP expression in neoplastic and non-neoplastic breast tissue with arsenic urinary levels.

The Hippo pathway regulates cell proliferation and apoptosis and it has been noted that loss of critical components of this pathway can lead to uncontrolled cell growth. Yes-associated protein (YAP) is an important component of this Hippo pathway because YAP is the nuclear effector of the Hippo tumor suppressor pathway and it is crucial for the response to oxidative stress induced by cellular process and by different xenobiotics, including arsenic. It has been proposed that YAP dysregulation can contribute to a malignant cellular phenotype acting as both a tumor suppressor and an oncogene. The aim of the study was to assess and compare the expression of YAP in neoplastic and non-neoplastic breast tissue of women chronically exposed to arsenic through drinking water. YAP expression was assessed by immunohistochemistry in 120 breast biopsies from women with breast cancer and from women with other non-neoplastic breast pathologies. Arsenic concentration was quantified in urine. The results disclosed a significant lower percentage of cytoplasm YAP expression in cases and that YAP high-intensity staining in the cytoplasm but not in the nucleus decreases the risk for breast cancer. In conclusion, our overall data suggest that YAP may act as a tumor suppressor protein because their reduced expression in cases, which can induce an environment favorable for inhibition of apoptosis and promoting cellular proliferation by increasing genetic instability of cells, which might contribute to the pathogenesis of cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Yes-associated protein (YAP) expression is involved in epithelial-mesenchymal transition in hepatocellular carcinoma.

PURPOSE: To investigate biological impact of the downregulation of yes-associated protein (YAP) through RNA interference in the process of epithelial-mesenchymal transition in MHCC97H and MHCC97L. METHODS: MHCC97H and MHCC97L cells were transiently transfected by YAP-siRNA. Furthermore, protein expressions and mRNA levels of characteristic markers of epithelial-mesenchymal transition (E-cadherin, N-cadherin) were examined by Western blotting and real-time polymerase chain reaction, and transwell invasion assay was used to detect changes of invasiveness of MHCC97H and MHCC97L cells. RESULTS: The transfected group with YAP-siRNA in MHCC97H after 72 h by Western blotting showed obviously higher expression of E-cadherin compared with the control group (P < 0.05), and lower expression of N-cadherin (P < 0.05). In MHCC97L cells, the expression of E-cadherin was also significantly increased (P < 0.05); however, N-cadherin expression did not significantly change (P > 0.05). Moreover, compared with the control group, Transwell invasion assay showed that the number of the transfected groups was significantly decreased in MHCC97H and MHCC97L cell lines (both P < 0.05). The result of real-time polymerase chain reaction indicated that mRNA levels of E-cadherin increased (P < 0.05), but the mRNA levels of N-cadherin did not significantly change (P > 0.05) in these two cell lines, indicating some effects of post-transcriptional regulation mechanism after silencing YAP. CONCLUSIONS: YAP expression in human hepatocellular carcinoma cell lines MHCC97H and MHCC97L is closely related with the characteristic markers of epithelial-mesenchymal transition, N-cadherin and E-cadherin expression.

YAP expression in normal and neoplastic breast tissue: an immunohistochemical study.

BACKGROUND AND AIMS: Yes-associated protein (YAP) is a transcriptional factor involved in normal cell proliferation, apoptosis and carcinogenesis; however, its contribution to breast cancer (BC) is still controversial. We undertook this study to compare the expression of YAP by immunohistochemistry (IHC) in normal breast tissue of women without breast cancer (BC) (controls), non-neoplastic breast tissue in women with cancer (internal controls) and in four different subtypes of invasive ductal carcinoma. METHODS: There were 17 controls and 105 tumor cases (53 luminal A, 15 luminal B, 20 overexpression of HER2 and 17 triple negative cases) studied by IHC. Statistical analysis included χ(2) for linear trend (Extended Mantel-Haenszel). RESULTS: There were 40% of internal controls that showed expression of YAP in myoepithelial cells, whereas in controls expression was 100%. In controls, 3/17 (17.6%) showed cytoplasmic staining in luminal cells. There was a significant difference in nuclear expression between the ductal BC subtypes. Luminal A had 4% of positive cases with <10% of cells affected in each case; in contrast, there were 17-20% of positive cases in the other groups with 50% or more of stained cells. YAP expression in stromal cells was not observed in controls or in triple-negative cases, and luminal B pattern had the highest YAP nuclear expression (20%). CONCLUSIONS: YAP showed decreased expression in tumor cells compared with normal breast tissue. These findings are consistent with a role of YAP as a suppressor gene in BC and show differences in YAP expression in different patterns of ductal BC.