Expression Of LATS1 Research Articles

CADM1 associates with Hippo pathway core kinases; membranous co-expression of CADM1 and LATS2 in lung tumors predicts good prognosis.

Cell adhesion molecule‐1 (CADM1) is a member of the immunoglobulin superfamily that functions as a tumor suppressor of lung tumors. We herein demonstrated that CADM1 interacts with Hippo pathway core kinases and enhances the phosphorylation of YAP1, and also that the membranous co–expression of CADM1 and LATS2 predicts a favorable prognosis in lung adenocarcinoma. CADM1 significantly repressed the saturation density elevated by YAP1 overexpression in NIH3T3 cells. CADM1 significantly promoted YAP1 phosphorylation on Ser 127 and downregulated YAP1 target gene expression at confluency in lung adenocarcinoma cell lines. Moreover, CADM1 was co–precipitated with multiple Hippo pathway components, including the core kinases MST1/2 and LATS1/2, suggesting the involvement of CADM1 in the regulation of the Hippo pathway through cell‐cell contact. An immunohistochemical analysis of primary lung adenocarcinomas (n = 145) revealed that the histologically low‐grade subtype frequently showed the membranous co–expression of CADM1 (20/22, 91% of low‐grade; 61/91, 67% of intermediate grade; and 13/32, 41% of high‐grade subtypes; P < 0.0001) and LATS2 (22/22, 100% of low‐grade; 44/91, 48% of intermediate‐grade; and 1/32, 3% of high‐grade subtypes; P < 0.0001). A subset analysis of disease‐free survival revealed that the membranous co–expression of CADM1 and LATS2 was a favorable prognosis factor (5‐year disease‐free survival rate: 83.8%), even with nuclear YAP1‐positive expression (5‐year disease‐free survival rate: 83.7%), whereas nuclear YAP1‐positive cases with the negative expression of CADM1 and LATS2 had a poorer prognosis (5‐year disease‐free survival rate: 33.3%). These results indicate that the relationship between CADM1 and Hippo pathway core kinases at the cell membrane is important for suppressing the oncogenic role of YAP1.

Lats1/2-Mediated Alteration of Hippo Signaling Pathway Regulates the Fate of Bone Marrow-Derived Mesenchymal Stem Cells.

Bone marrow-derived mesenchymal stem cells (BMSCs) can be used to enhance lung repair in acute respiratory distress syndrome (ARDS); however, the repairing effect is limited by poor homing and retention of BMSCs. The purpose of this study was to investigate whether Lats1 and Lats2-mediated alteration of Hippo signaling pathway could promote the differentiation, proliferation, and migration of BMSCs. BMSCs were transduced by lentiviral vectors for high and low expression of Lats1 and Lats2. The expression levels of Lats1, Lats2, YAP, and 14-3-3, respectively, were assessed to clarify the regulatory effects of Lats1 and Lats2 on Hippo signaling. Osteogenic (Runx2 and OSX) and adipogenic (C/EBPα and PPAR-γ) transcription factors were determined to clarify the effects of Hippo signaling on BMSCs differentiation. The effects of Hippo signaling on BMSCs proliferation and horizontal and vertical migration were also measured by CCK-8, scratch assay, and Transwell migration assay, respectively. Lentiviral transduction efficiency could reach 93.11%–97.14%. High and low expression of Lats1 and Lats2 could activate and inhibit the Hippo signaling pathway, respectively. High and low expression of Lats1 and Lats2 could inhibit and promote BMSCs differentiation into osteoblasts and adipocytes. High and low expression of Lats1 and Lats2 could inhibit and promote BMSCs proliferation and horizontal and vertical migration, respectively. Our studies suggest that Lats1/2-meidiated inhibition of Hippo signaling in BMSCs may optimize their effects of tissue repair in ARDS, suggesting a novel strategy for enhancing disease therapeutics.

LATS1 and LATS2 suppress breast cancer progression by maintaining cell identity and metabolic state.

Deregulated activity of LArge Tumor Suppressor (LATS) tumor suppressors has broad implications on cellular and tissue homeostasis. We examined the consequences of down-regulation of either LATS1 or LATS2 in breast cancer. Consistent with their proposed tumor suppressive roles, expression of both paralogs was significantly down-regulated in human breast cancer, and loss of either paralog accelerated mammary tumorigenesis in mice. However, each paralog had a distinct impact on breast cancer. Thus, LATS2 depletion in luminal B tumors resulted in metabolic rewiring, with increased glycolysis and reduced peroxisome proliferator-activated receptor γ (PPARγ) signaling. Furthermore, pharmacological activation of PPARγ elicited LATS2-dependent death in luminal B-derived cells. In contrast, LATS1 depletion augmented cancer cell plasticity, skewing luminal B tumors towards increased expression of basal-like features, in association with increased resistance to hormone therapy. Hence, these two closely related paralogs play distinct roles in protection against breast cancer; tumors with reduced expression of either LATS1 or LATS2 may rewire signaling networks differently and thus respond differently to anticancer treatments.

Abstract B43: Disruption of the YAP-LATS2 feedback loop switches ovarian cells from YAP-induced senescence to malignant transformation

Abstract Introduction: Dysregulation of the Hippo signaling pathway leads to tumorigenesis in many organs and tissues. Our previous studies show that Yes-associated protein (YAP) induces tumorigenesis in immortalized ovarian surface epithelial cells and fallopian tube secretory epithelial cells. However, the role of Hippo/YAP signaling pathway in primary human ovarian cells is unknown. Aims: The present study seeks to: 1) determine the role of the Hippo/YAP pathway in primary human ovarian cells and 2) investigate the molecular mechanism by which interruption of the Hippo pathway regulates ovarian cell malignant transformation. Methods: Primary human ovarian surface epithelial (hOSE) cells and granulosa cells (hGCs) were employed as cellular models to determine potential roles of the core components of the Hippo/YAP pathway in ovarian cells. CRISPR/Cas9-based gene knockout system, lentiviral-based gene expression system, and siRNAs were utilized to manipulate the expression and activities of the major components of the Hippo/YAP pathway. Soft agar assays and xenograft mouse models were used to examine the role of the Hippo/YAP pathway in tumorigenesis. Results: Ectopic expression of YAP, the major oncogenic effector of the Hippo pathway, induced cell cycle arrest and cellular senescence in cultured primary hOSE cells and hGCs. Importantly, we found that LATS2, a major upstream suppressor of YAP, was elevated in both natural replicative and YAP-induced senescence. Knockout of LATS2 in primary hOSE cells not only diminished natural replicative senescence, but also prevented YAP-induced cellular senescence. Overexpression of LATS2 in primary hOSE cells sped the progression of natural replicative and YAP-induced senescence. Further studies showed that constitutive activation of YAP stimulated the expression of LATS2 in hOSE cells, indicating that YAP and LATS2 formed a negative feedback loop to regulate cellular senescence. Intriguingly, we found that constitutive activation of YAP in LATS2-deficient hOSE cells induced malignant transformation and tumor formation in a xenograft mouse model. Finally, our mechanistic studies showed that the ectopic expression of LATS2 in primary hOSE cells significantly increased expression of several major components of the DREAM (dimerization partner, RB-Like, E2F, and multi-vulval class B) complex, which represses gene expression during cellular quiescence, suggesting that the Hippo/YAP pathway may control cell fate via regulating assembly of DREAM complex. Conclusion: Our results suggest that LATS2 and YAP, two major components of the Hippo/YAP pathway, form a negative feedback loop to control cellular senescence and prevent ovarian cells from malignant transformation. Disruption of the Hippo pathway and the subsequent loss of the YAP-LATS2 negative feedback system may switch ovarian cells from YAP-induced senescence to tumorigenesis. Citation Format: Chunbo He, Xiangmin Lv, Huang Cong, Guohua Hua, Bowen Ma, Xingcheng Chen, Peter C. Angeletti, Jixin Dong, Jin Zhou, Bo Rueda, John S. Davis, Cheng Wang. Disruption of the YAP-LATS2 feedback loop switches ovarian cells from YAP-induced senescence to malignant transformation. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B43.

Hypermethylated LATS2 gene with decreased expression in female breast cancer: A case control study from North India

BackgroundLATS2, a presumed tumor suppressor gene located on chromosome 13q11–12 is involved in cell growth related activity like regulation of cell cycle at G1/S. The reduced expression of LATS2 has been reported in many tumors; including tumors of Breast, which is to the best of our knowledge has not been studied in north Indian female breast cancer population. ObjectiveHere, we looked upon the expression pattern and methylation status of the LATS2 gene in north Indian female breast cancer cases to further strengthen its role as a tumor suppressor gene and more importantly as a cancer biomarker. MethodsmRNA expression level was determined by real time PCR in 140 Breast cancer patients, Protein expression was studied by Immunohistochemistry and Promoter methylation was studied by Methylation specific PCR. All findings were correlated with clinicopathological features. ResultsLATS2 mRNA expression was remarkably downregulated in 67.85% (95/140) cases. The expression of Large Associated Tumor Suppressor 2 at protein level was also absent in 67.85% (95/140) cases. The absence of LATS2 protein strongly correlated with promoter hypermethylation where 91 out of a total of 107 hyper methylated cases showed absence of protein (91/107, 85%). The absence of LATS2 protein was strongly significant with HER2 neu status (0.01), TNM staging (0.009) and Molecular subtype (0.024). ConclusionThe decreased expression in breast cancer seems to be associated with hypermethylation of LATS2 promoter regions. Further LATS2 as a tumor suppressor can be recognized as a promising Biomarker in Breast cancer pathogenesis. Though, further studies, targeting larger sets of breast cancer population are required to establish LATS2 as a promising biomarker.

Downregulation of MiR-31 stimulates expression of LATS2 via the hippo pathway and promotes epithelial-mesenchymal transition in esophageal squamous cell carcinoma

BackgroundDysregulation of miRNAs is associated with cancer development by coordinately suppressing abundant target genes. Emerging evidence indicates that miR-31 plays a dual role in tumorigenicity. However, whether miR-31 plays as an oncogene in esophageal squamous cell carcinoma (ESCC) and the potential target molecules are still unclear. MiR-31 role in ESCC was investigated and an association of the target molecules with EMT was identified in the progression of ESCC.MethodsWestern blot assays and qRT-PCR was performed to detect the protein and mRNA levels. We investigated the role of miR-31 in the regulation of LATS2 expression in ESCC cell lines via functional assays both in vivo and in vitro. The luciferase reporter assays was conducted to confirm LATS2 is a potential target of miR-31. Immunohistochemistry was used to measure LATS2 and TAZ expression in normal and ESCC tissue.ResultsLATS2 is a component of the Hippo tumor-suppressive signaling pathway. Frequent loss of heterozygosity of LATS2 has been reported in esophageal cancer. We analyzed the reciprocal expression regulation of miR-31 and LATS2 and demonstrated that LATS2 expression was elevated by down-regulation of miR-31 at the post-transcriptional level in ESCC. Moreover, miR-31 significantly suppressed the luciferase activity of mRNA combined with the LATS2 3′-UTR, a key molecule in the Hippo pathway. Then, LATS2 consequently promoted the translocation of TAZ, which was examined using immunohistochemistry. Silencing of miR-31 significantly inhibited the cell proliferation, induced apoptosis and decreased the ability of migration/invasion in vitro. LATS2 impedes ESCC cell proliferation and invasion by suppressing miR-31, as well as mice xenograft model in vivo. Meanwhile, the nuclear localization of LATS2 constrained the phosphorylation of TAZ. Then, the expression level of TAZ was notably heightened with a high risk of recurrence compared to that observed in the low-risk patients, as well as, the higher expression associated with a poor survival.ConclusionsOur study demonstrated that overexpression of miR-31 undertook an oncogenic role in ESCC by repressing expression of LATS2 via the Hippo Pathway and activating epithelial-mesenchymal transition. LATS2 and TAZ could be potential novel molecular markers for predicting the risk of recurrence and prognosis of ESCC.

Morin attenuates diethylnitrosamine-induced rat liver fibrosis and hepatic stellate cell activation by co-ordinated regulation of Hippo/Yap and TGF-β1/Smad signaling

Despite great progress in understanding the activation of hepatic stellate cells (HSCs) during liver fibrosis, therapeutic approaches to inhibit HSC activation remain very limited. Recent reports highlight Yes-associated protein (Yap) and transforming growth factor-β1 (TGF-β1) as critical regulators of HSC activation and henceforth a compound targeting Hippo/Yap and TGF-β1/Smad pathways would be a potential anti-fibrotic candidate. Morin, a dietary flavonoid, was earlier reported to inhibit HSC proliferation and induction of apoptosis of cultured HSCs, mainly by suppressing Wnt/β-catenin and NF-κB signaling, but its effect on Hippo/Yap and TGF-β1/Smad pathways was not determined. To address this concern, this study was carried out in cultured LX-2 cells and diethylnitrosamine-induced fibrotic rats. Morin activated hippo signaling through significantly increased expression of Mst1 and Lats1 with decreased expression of transcriptional effectors Yap/TAZ, thereby prevented HSC activation and also suppressed the expression of exacerbated TGF-β/Smad signaling molecules such as TGF-β1, p-Smad2/3, collagen-I, MMP-2, MMP-9 and TIMP-1 in cultured LX-2 and DEN induced fibrotic rats. Both the in vitro and in vivo results clearly showed that, morin by acting on Hippo/Yap and TGF-β1/Smad pathways, ameliorated experimental liver fibrosis, indicating that morin has potential for effective treatment of liver fibrosis.

The role of miR-372 in ovarian carcinoma cell proliferation

ObjectivesMicroRNA-372 has been shown to be associated with multiple tumors' development and progression, by regulating the expression of proteins involved in cell cycle and apoptosis. However, the specific mechanism and function of miR-372 in ovarian carcinoma are not clear. Our study explored the role of miR-372 in ovarian carcinoma cell cycle and proliferation. Materials and methodsMiR-372 expression was quantified in normal ovarian tissue, benign tumors, primary ovarian carcinomas and metastatic omentum by qRT-PCR. MTT assay and plate clone formation assay were performed to evaluate the cell viability and proliferation. EDU assay and cell apoptosis assay were also used to determine cell growth. We used Western Blot to analysis expression of the known miR-372 targets. ResultsWe found that miR-372 expression was significantly lower in ovarian carcinoma than normal ovarian tissues and benign tumors. Moreover, miR-372 overexpression showed significant inhibition of cell proliferation and promoted cell apoptosis. Western Blot revealed that miR-372 downregulated the expression of ATAD2, LATS2, P62, DKK1 and cyclinA1 to inhibit the proliferation of cells. ConclusionsOur findings indicate that miR-372 has a prominent role in inhibiting tumor growth and it is a valuable target for ovarian cancer therapy.

MicroRNAs in Cardiac Conduction System

The cardiac conduction system (CCS) is required for initiating and maintaining regular rhythmic heartbeats and the CCS defects can give rise to cardiac arrhythmia, a leading cause for morbidity worldwide. MicroRNAs (miRs) are small non‐coding RNAs that repress gene expression post‐transcriptionally. We found that miR‐17‐92 is actively expressed in the CCS. Specific disruption of miR‐17‐92 in the CCS gave rise to cardiac arrhythmias in mice. We combined different screenings and identified miR‐17‐92 and its homologous cluster miR‐106b‐25 as candidate miR function in atrial fibrillation (AF), the most common adult arrhythmia. Intracardiac electrical stimulation revealed that mice with miR‐17‐92 and miR‐106b‐25 deficiency were predisposed to pacing‐induced AF. Mice with miR‐17‐92 cardiac‐specific conditional knockout (CKO) had spontaneous arrhythmias. miR‐17‐92 and miR‐106b‐25 directly repress expression of the sinoatrial node (SAN) program gene such as Shox2 and Tbx3. Notably, miR‐17‐92 also represses Hippo signaling, an ancient organ size control pathway represses cardiomyocyte proliferation and regeneration. miR‐17‐92 directly represses expression of the core Hippo component Lats2. Hippo disruption in the CCS also gave rise to cardiac arrhythmias in mice. Chromatin immunoprecipitation deep sequencing (ChIP‐Seq) data using antibody of Yap, the Hippo signaling effector, suggested that Hippo signaling regulates genes involved in the CCS homeostasis. Together, our data indicate a critical function of miR in maintaining the CCS homeostasis and avoiding arrhythmogenesis.

Clinicopathological Significance of Large Tumor Suppressor (LATS) Expression in Gastric Cancer.

PurposeThe aims of this study were to evaluate the expression of the large tumor suppressor (LATS) genes LATS1 and LATS2 by immunohistochemical staining of gastric cancer, and to evaluate the clinicopathological significance of LATS expression and its correlation with overall survival (OS).Materials and MethodsLATS1 and LATS2 expression in a tissue microarray was detected by immunohistochemistry, using 264 gastric cancer specimens surgically resected between July 2006 and December 2009.ResultsLow expression of LATS1 was significantly associated with more advanced American Joint Committee on Cancer (AJCC) stage (P=0.001) and T stage (P=0.032), lymph node (LN) metastasis (P=0.040), perineural invasion (P=0.042), poor histologic grade (P=0.007), and diffuse-type histology by the Lauren classification (P=0.033). Low expression of LATS2 was significantly correlated with older age (≥65, P=0.027), more advanced AJCC stage (P=0.001) and T stage (P=0.001), LN metastasis (P=0.004), perineural invasion (P=0.004), poor histologic grade (P<0.001), and diffuse-type histology by the Lauren classification (P<0.001). Kaplan-Meier survival analysis revealed significantly poor OS rates in the groups with low LATS1 (P=0.037) and LATS2 (P=0.037) expression.ConclusionsExpression of LATS1 or LATS2 is a significant marker for a good prognosis in patients with gastric cancer.

Sphingosylphosphorylcholine regulates the Hippo signaling pathway in a dual manner

Sphingosylphosphorylcholine (SPC) is a bioactive sphingolipid which regulates many cancer-related processes, including cellular proliferation. The Hippo signaling pathway consists of a cascade of tumor suppressive kinases Mst1/2 and Lats1/2 and their downstream targets YAP and TAZ which are generally pro-proliferative transcriptional regulators. Direct phosphorylation by Lats1/2 causes inhibition or degradation of YAP/TAZ and down-regulation of their target genes. We found SPC treatment of MDA-MB-435S breast cancer cells to strongly inhibit their proliferation and to induce a sustained Lats2 protein expression (6–24h). Therefore, we hypothesized that Hippo signaling might mediate the anti-proliferative SPC response. We also saw a cell density-dependent increase in S127-phosphorylated YAP (pS127-YAP) and a decrease in mRNA levels of YAP target genes (CTGF, Cyr61) in response to long (9h) SPC treatment. Knockdown of S1P receptor 2 (S1P2) prevented the SPC-induced up-regulation of Lats2 and attenuated the anti-proliferative effect of SPC. However, while knockdown of Lats2 alone or in combination with Lats1 expectedly increased basal proliferation it did not attenuate the SPC-induced inhibition of proliferation. Exogenous expression of wild-type or kinase-dead Lats2 and knockdown of YAP/TAZ also had no effect on the anti-proliferative SPC response. It has been previously shown that activation of S1P2-G12/13 by sphingosine-1-phosphate (S1P) leads to rapid de-phosphorylation and up-regulation of YAP. Similarly, we saw a decrease in pS127-YAP and an increase in total YAP levels with short (1h) SPC treatment as well as a subsequent transient increase in YAP target gene expression. Inhibition of S1P2 prevented the SPC-induced YAP de-phosphorylation. The rapid YAP activation and subsequent up-regulation of Lats2 mRNA does not constitute a negative feedback loop as knockdown of YAP/TAZ did not inhibit SPC-induced Lats2 expression. In conclusion, in this study we show that SPC is able to regulate Hippo signaling in a dual and opposite manner, causing an initial activation of YAP followed by an inhibition. However, even the strong SPC-induced effects seen in Lats2 and YAP did not mediate the anti-proliferative SPC response.

Photoreceptor proliferation and dysregulation of cell cycle genes in early onset inherited retinal degenerations

BackgroundMitotic terminally differentiated photoreceptors (PRs) are observed in early retinal degeneration (erd), an inherited canine retinal disease driven by mutations in the NDR kinase STK38L (NDR2).ResultsWe demonstrate that a similar proliferative response, but of lower magnitude, occurs in two other early onset disease models, X-linked progressive retinal atrophy 2 (xlpra2) and rod cone dysplasia 1 (rcd1). Proliferating cells are rod PRs, and not microglia or Müller cells. Expression of the cell cycle related genes RB1 and E2F1 as well as CDK2,4,6 was up-regulated, but changes were mutation-specific. Changes in cyclin expression differed across all genes, diseases and time points analyzed, although CCNA1 and CCNE1 expression increased with age in the three models suggesting that there is a dysregulation of cell cycle gene expression in all three diseases. Unique to erd, however, are mutation-specific changes in the expression of NDR kinases and Hippo signaling members with increased expression of MOB1 and LATS1 in the newly generated hybrid rod/S-cones.ConclusionsOur data raise the intriguing possibility that terminally differentiated normal PRs are kept from dividing by NDR2-MOB1 interaction. Furthermore, they provide the framework for the selection of candidate genes for further investigation as potential targets of therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2477-9) contains supplementary material, which is available to authorized users.

Survival kinase genes present prognostic significance in glioblastoma.

Cancer biomarkers with a strong predictive power for diagnosis/prognosis and a potential to be therapeutic targets have not yet been fully established. Here we employed a loss-of-function screen in glioblastoma (GBM), an infiltrative brain tumor with a dismal prognosis, and identified 20 survival kinase genes (SKGs). Survival analyses using The Cancer Genome Atlas (TCGA) datasets revealed that the expression of CDCP1, CDKL5, CSNK1E, IRAK3, LATS2, PRKAA1, STK3, TBRG4, and ULK4 stratified GBM prognosis with or without temozolomide (TMZ) treatment as a covariate. For the first time, we found that GBM patients with a high level of NEK9 and PIK3CB had a greater chance of having recurrent tumors. The expression of CDCP1, IGF2R, IRAK3, LATS2, PIK3CB, ULK4, or VRK1 in primary GBM tumors was associated with recurrence-related prognosis. Notably, the level of PIK3CB in recurrent tumors was much higher than that in newly diagnosed ones. Congruent with these results, genes in the PI3K/AKT pathway showed a significantly strong correlation with recurrence rate, further highlighting the pivotal role of PIK3CB in the disease progression. Importantly, 17 SKGs together presented a novel GBM prognostic signature. SKGs identified herein are associated with recurrence rate and present prognostic significance in GBM, thereby becoming attractive therapeutic targets.

Expression of LATS mRNA in mantle cell lymphoma and its clinical significance

To investigate the expression level of large tumor suppressor (LATS)1, LATS2 mRNA and its prognostic value in mantle cell lymphoma (MCL). A total of 36 B-NHL cases (including MCL 16 cases, chronic lymphoblastic leukemia (CLL) 11 cases, splenic marginal zone cell lymphoma (SMZL) 9 cases) and 8 healthy donors were enrolled in this study from January 2008 to April 2011 in our Lymphoma Clinic Center. The mRNA level of Yap (effector of Hippo pathway) and LATS1, LATS2 mRNA were detected by using real-time quantitative PCR. Log expression values of real-time quantitative PCR data were used in this analysis. The YAP mRNA expression level in MCL, CLL and SMZL patient were significantly higher than that in health donor (lg: 1.97±0.79, 1.83±0.54, 2.12±0.42 vs 1.21±1.56, all P<0.05). The expression level of LATS1, LATS2 mRNA in MCL was significantly correlated with molecular cytogenetic aberrations, progression free survival (PFS) and overall survival (OS). The LATS1 expression level was statistically lower in the group of MCL with delection P53 than the group of MCL without delection P53 (lg: 0.75±0.27 vs 1.10±0.19, P=0.035). And the LATS1 expression level was statistically lower in the death group than the survival group (lg: 0.76±0.27 vs 1.15±0.17, P=0.026). The PFS and OS were significantly longer in the MCL patients with high level of LATS1 than that of other MCL patients ((70.4±32.7) vs (5.6±2.2) months, P=0.044; (123.8±22.0) vs (7.7±2.2) months, P=0.017). Hippo pathway is dysfunctional in B-NHL, especially in MCL.The reduced expression of LATS1, LATS2 in MCL patients is associated with progressive disease, and might be an important prognostic factor in MCL.

Expression of LATS family proteins in ovarian tumors and its significance.

Epithelial ovarian cancer is composed of a diverse group of tumors that can be derived from the fallopian tube, endometrium, or ovary. In this study, we explored the expression levels of LATS family members in ovarian tumors using normal ovaries, fallopian tubes, and endometrium as controls. Immunohistochemistry studies of LATS1, LATS2, Pax8, and calretinin were performed on normal ovary, fallopian tube, normal endometrium, and ovarian tumor sections. Statistical analyses were conducted using the χ(2) test, Fisher exact test, or Kruskal-Wallis H test. Patient survival was analyzed using the Kaplan-Meier method. LATS1 was expressed in normal ovarian epithelia, endometrium, and fallopian tubes, whereas LATS2 expression was observed in the normal fallopian tubes and endometrium. High expressions of LATS1 and LATS2 in serous cystadenomas gradually decreased in borderline cystadenomas and carcinomas, respectively. However, an opposite expression pattern was observed in mucinous tumors. Low expressions of LATS1 and LATS2 were also detected in clear cell carcinoma. Both LATS1 and LATS2 expression levels significantly correlated with recurrence and stage; LATS1 levels were also related with tumor grades in serous carcinoma. However, univariate and multivariate Cox regression analyses revealed that high expression of LATS1 was associated with better prognosis in patients with serous carcinoma. Both LATS1 and LATS2 were not related with the clinical variables in mucinous and clear cell carcinoma. LATS1 expression levels might be a valuable survival indicator in ovarian serous carcinoma.

Angiomotin promotes breast cancer cell proliferation and invasion.

Angiomotin (Amot) is a multifunctional protein involved in endothelial cell migration and tube formation and angiogenesis. However, the biological role and molecular mechanism for the abnormal expression of Amot in breast cancer is poorly understood. The aim of the present study was to examine the function of and relationship between Amot and the Hippo-Yes-associated protein (YAP) pathway. The expression and location of Amot was examined in breast cancer tissues and cell lines using immunohistochemistry, real-time polymerase chain reaction analysis (RT-PCR), western blotting and immunofluorescence. ANOVA, Student's t-test, Wilcoxon and Chi-square tests were utilized to determine the association of Amot expression with clinically relevant parameters. Stable Amot knockdown MCF-7 cells (MCF-7 Amot KD) were generated to investigate the impact of Amot downregulation on the growth and invasion of MCF-7 cells invitro. Western blotting was applied to detect the expression of the Hippo-YAP pathway protein in the MCF-7 cells. It was observed that Amot was highly expressed in breast cancer tissues, but weakly expressed in adjacent non-cancerous tissues. Additionally, the expression level of Amot was correlated with that of Ki-67. In MCF-7 cells, Amot downregulation resulted in a significant decrease of cell proliferation and invasiveness. Following Amot knockdown in MCF-7 cells, the expression of YAP, YAP/TAZ and LATS1 was decreased. In particular, the expression of YAP was markedly reduced in the nucleoprotein. The results suggested that Amot was highly expressed in breast cancer tissues and was important in the promotion of breast cancer cell proliferation and invasion. In addition, there was a more intimate connection between Amot and Hippo-YAP pathway.

New genetic variants of LATS1 detected in urinary bladder and colon cancer.

LATS1, the large tumor suppressor 1 gene, encodes for a serine/threonine kinase protein and is implicated in cell cycle progression. LATS1 is down-regulated in various human cancers, such as breast cancer, and astrocytoma. Point mutations in LATS1 were reported in human sarcomas. Additionally, loss of heterozygosity of LATS1 chromosomal region predisposes to breast, ovarian, and cervical tumors. In the current study, we investigated LATS1 genetic variations including single nucleotide polymorphisms (SNPs), in 28 Egyptian patients with either urinary bladder or colon cancers. The LATS1 gene was amplified and sequenced and the expression of LATS1 at the RNA level was assessed in 12 urinary bladder cancer samples. We report, the identification of a total of 29 variants including previously identified SNPs within LATS1 coding and non-coding sequences. A total of 18 variants were novel. Majority of the novel variants, 13, were mapped to intronic sequences and un-translated regions of the gene. Four of the five novel variants located in the coding region of the gene, represented missense mutations within the serine/threonine kinase catalytic domain. Interestingly, LATS1 RNA steady state levels was lost in urinary bladder cancerous tissue harboring four specific SNPs (16045 + 41736 + 34614 + 56177) positioned in the 5′UTR, intron 6, and two silent mutations within exon 4 and exon 8, respectively. This study identifies novel single-base-sequence alterations in the LATS1 gene. These newly identified variants could potentially be used as novel diagnostic or prognostic tools in cancer.

Hippo Signaling Pathway Reveals a Spatio-Temporal Correlation with the Size of Primordial Follicle Pool in Mice

Background: The Hippo signaling pathway, a highly conserved cell signaling system, exists in most multicellular organisms and regulates cell proliferation, differentiation, and apoptosis. It has been reported that the members of Hippo signaling are expressed in mammalian ovaries, but the exact functions of this pathway in primordial follicle development remains unclear. Methods: To analyze the spatio-temporal correlation between the core component of Hippo pathway and the size of primordial follicle pool, Western blot, Real-time PCR and immunohistochemistry were used, and the expression and localization of MST1, LATS2 and YAP1 mRNA and protein were examined in 3 d, 1 m, 5 m, 16 m postnatal mice ovary and the culture model of mice primordial follicle in vitro. Results: Both the protein and mRNA expression of the MST1 and LATS2 were decreased significantly as mouse age increased (p < 0.05), however, the mRNA expression of them increased significantly in 16 m compared with 5 m as well as the protein expression of LATS2.The expression of YAP showed the opposite trend, and the significant protein expression of pYAP was increased before 1 m, after which no significant change was observed. Moreover, the ratio of pYAP/YAP decreased significantly. Culturing ovaries for 8 d in vitro resulted in the activation of primordial follicles in 3 d postnatal mice ovaries, and these developed into primary follicles with the expression of PCNA increasing significantly (p < 0.05). The mRNA and protein expression of MST and LATS decreased significantly (p < 0.05), and the expression of YAP increased significantly (p < 0.05, p < 0.01), whereas the ratio of pYAP/YAP decreased significantly (p < 0.05). Conclusion: The above results reveal that the expression of the core components of Hippo pathway changed during mouse follicular development, especially before and after primordial follicle activation in vitro. The primordial follicle activation may be related to the significant decrease of the ratio of pYAP1/YAP1. In conclusion, Hippo signaling pathway expressed in mice ovaries and have spatio-temporal correlation with the size of primordial follicle pool.

Down-regulation of LATS2 in non-small cell lung cancer promoted the growth and motility of cancer cells.

LATS2 (Large tumor suppressor) has been reported to be dys-regulated in several cancer types. However, its function in non-small cell lung cancer (NSCLC) remains poorly understood. Here, it was found that the expression level of LATS2 was decreased in NSCLC tissues. Moreover, forced expression of LATS2 in NSCLC cells inhibited cell growth and migration, while knockdown of the expression of LATS2 promoted the tumorigenicity of NSCLC cells. Mechanistically, LATS2 was found to negatively regulate NF-κB signaling in NSCLC cells. Taken together, our study suggested that down-regulation of LATS2 was very important in the progression of NSCLC, and restoring the function of LATS2 might be a promising therapeutic strategy for NSCLC.

Expression of LATS1 contributes to good prognosis and can negatively regulate YAP oncoprotein in non-small-cell lung cancer

Large tumor suppressor (LATS) is a Ser/Thr kinase originally isolated from Drosophila. Recent studies demonstrate that LATS is an important member of the Hippo pathway which can regulate organ size and cell proliferation. However, little is known about the expression and clinical significance of LATS in lung cancer. In this study, we aimed to assess the clinical significance and biological functions of LATS1 in non-small-cell lung cancer (NSCLC). We investigated the expression of LATS1 in 136 cases of NSCLC tissue and 30 cases of normal lung tissue by immunohistochemical staining. The results confirmed that LATS1 expression was higher in normal lung tissues, but significantly lower in NSCLC tissues. Moreover, the expression of LATS1 in NSCLC was significantly correlated with p-TNM stage (p = 0.038) and lymph node metastasis (p = 0.014). Importantly, the loss of LATS1 expression was associated with short overall survival. Further study in NSCLC cell lines in which LATS1 was either overexpressed or depleted confirmed that LATS1 markedly inhibited cell proliferation and invasion and could regulate the nuclear location of yes-associated protein (YAP). These results indicate that LATS1 may play an important role in NSCLC, and may serve as a novel therapeutic target of NSCLC.