Lats1 suppresses centrosome overduplication by modulating the stability of Cdc25B

Live-cell FRET assay on the stoichiometry and affinity of the YAP complexes in MCF-7 cells

Yes-associated protein (YAP), a focal point of current biological research, is involved in regulating various life processes. In this report, live-cell fluorescence resonance energy transfer (FRET) imaging was employed to unravel the YAP complexes in MCF-7 cells. Fluorescence imaging of living cells co-expressing CFP (cyan fluorescent protein)-YAP and YFP (yellow fluorescent protein)-LATS1 (large tumor suppressor 1) plasmids revealed that YAP promoted LATS1 oligomerization around mitochondria. Moreover, FRET two-hybrid assay showed that YAP directly interacted with LATS1 to form dimer. Similarly, we found that YAP directly interacted with large tumor suppressor 2 (LATS2) to form a heterotrimer with 1:2 in cytoplasm and around mitochondria. In addition, YAP directly interacted with angiomotin (AMOT) to form a heterodimer in cytoplasm. However, YAP did not interact with O-linked N-acetylglucosamine transferase (OGT). Furthermore, FRET assay also indicated that YAP exhibited a higher affinity with AMOT, followed by LATS1, and least with LATS2. In summary, YAP directly interacts with LATS1 and AMOT to form a heterodimer, with LATS2 to form a heterotrimer with 1:2, and shows a preference for binding to AMOT, followed by LATS1, and lastly LATS2, providing new insights into the Hippo-YAP signaling pathway.

Decoding chromosomal instability insights in CRC by integrating omics and patient-derived organoids

BACKGROUND

Chromosomal instability (CIN) is involved in about 70% of colorectal cancers (CRCs) and is associated with poor prognosis and drug resistance. From a clinical perspective, a better knowledge of these tumour's biology will help to guide therapeutic strategies more effectively.

METHODS

We used high-density chromosomal microarray analysis to evaluate CIN level of patient-derived organoids (PDOs) and their original mCRC tissues. We integrated the RNA-seq and mass spectrometry-based proteomics data from PDOs in a functional interaction network to identify the significantly dysregulated processes in CIN. This was followed by a proteome-wGII Pearson correlation analysis and an in silico validation of main findings using functional genomic databases and patient-tissues datasets to prioritize the high-confidence CIN features.

RESULTS

By applying the weighted Genome Instability Index (wGII) to identify CIN, we classified PDOs and demonstrated a good correlation with tissues. Multi-omics analysis showed that our organoids recapitulated genomic, transcriptomic and proteomic CIN features of independent tissues cohorts. Thanks to proteotranscriptomics, we uncovered significant associations between mitochondrial metabolism and epithelial-mesenchymal transition in CIN CRC PDOs. Correlating PDOs wGII with protein abundance, we identified a subset of proteins significantly correlated with CIN. Co-localisation analysis in PDOs strengthened the putative role of IPO7 and YAP, and, through in silico analysis, we found that some of the targets give significant dependencies in cell lines with CIN compatible status.

CONCLUSIONS

We first demonstrated that PDO models are a faithful reflection of CIN tissues at the genetic and phenotypic level. Our new findings prioritize a subset of genes and molecular processes putatively required to cope with the burden on cellular fitness imposed by CIN and associated with disease aggressiveness.

Bystanders or active players: the role of extra centrosomes as signaling hubs

Centrosomes serve as microtubule-organizing organelles that function in spindle pole organization, cell cycle progression, and cilia formation. A non-canonical role of centrosomes that has gained traction in recent years is the ability to act as signal transduction centers. Centrosome amplification, which includes numerical and structural aberrations of centrosomes, is a candidate hallmark of cancer. The function of centrosomes as signaling centers in cancer cells with centrosome amplification is poorly understood. Establishing a model of how cancer cells utilize centrosomes as signaling platforms will help elucidate the role of extra centrosomes in cancer cell survival and tumorigenesis. Centrosomes act in a diverse array of cellular processes, including cell migration, cell cycle progression, and proteasomal degradation. Given that cancer cells with amplified centrosomes exhibit an increased number and larger area of these signaling platforms, extra centrosomes may be acting to promote tumor development by enhancing signaling kinetics in pathways that are essential for the formation and growth of cancer. In this review, we identify the processes centrosomes are involved in as signal transduction platforms and highlight ways in which cancer cells with centrosome amplification may be taking advantage of these mechanisms.

Consecutive palmitoylation and phosphorylation orchestrates NLRP3 membrane trafficking and inflammasome activation

NLRP3 inflammasome activation, essential for cytokine secretion and pyroptosis in response to diverse stimuli, is closely associated with various diseases. Upon stimulation, NLRP3 undergoes subcellular membrane trafficking and conformational rearrangements, preparing itself for inflammasome assembly at the microtubule-organizing center (MTOC). Here, we elucidate an orchestrated mechanism underlying these ordered processes using human and murine cells. Specifically, NLRP3 undergoes palmitoylation at two sites by palmitoyl transferase zDHHC1, facilitating its trafficking between subcellular membranes, including the mitochondria, trans-Golgi network (TGN), and endosome. This dynamic trafficking culminates in the localization of NLRP3 to the MTOC, where LATS1/2, pre-recruited to MTOC during priming, phosphorylates NLRP3 to further facilitate its interaction with NIMA-related kinase 7 (NEK7), ultimately leading to full NLRP3 activation. Consistently, Zdhhc1-deficiency mitigated LPS-induced inflammation and conferred protection against mortality in mice. Altogether, our findings provide valuable insights into the regulation of NLRP3 membrane trafficking and inflammasome activation, governed by palmitoylation and phosphorylation events.

Whole-Genome Doubling as a source of cancer: how, when, where, and why?

Chromosome instability is a well-known hallmark of cancer, leading to increased genetic plasticity of tumoral cells, which favors cancer aggressiveness, and poor prognosis. One of the main sources of chromosomal instability are events that lead to a Whole-Genome Duplication (WGD) and the subsequently generated cell polyploidy. In recent years, several studies showed that WGD occurs at the early stages of cell transformation, which allows cells to later become aneuploid, thus leading to cancer progression. On the other hand, other studies convey that polyploidy plays a tumor suppressor role, by inducing cell cycle arrest, cell senescence, apoptosis, and even prompting cell differentiation, depending on the tissue cell type. There is still a gap in understanding how cells that underwent WGD can overcome the deleterious effect on cell fitness and evolve to become tumoral. Some laboratories in the chromosomal instability field recently explored this paradox, finding biomarkers that modulate polyploid cells to become oncogenic. This review brings a historical view of how WGD and polyploidy impact cell fitness and cancer progression, and bring together the last studies that describe the genes helping cells to adapt to polyploidy.

LATS kinases and SLUG regulate the transition to advanced stage in aggressive oral cancer cells

The epithelial-to-mesenchymal transition (EMT) is a critical process by which cancer cells acquire malignant features. However, the molecular mechanism and functional implications of EMT and the mesenchymal-to-epithelial transition (MET) in tumor progression remain elusive. In this study, we established two aggressive cancer cell lines from the human oral cancer cell line SAS, mesenchymal-like SAS-m4 and epithelial-like SAS-δ. SAS-δ is a revertant cell obtained by inducing MET in SAS-m4. SAS-δ, but not SAS-m4, exhibited abnormal cell growth, including piled-up overgrowth and invasive tumor formation in the tongues of nude mice, suggesting that SAS-δ represented more advanced cancer cells than the parental SAS cells. EMT-related transcriptional factor SLUG is phosphorylated at T208 and partly stabilized by the Hippo pathway kinases, LATS1 and LATS2. Depletion of SLUG promoted the invasive activity of SAS-δ by increasing the protein levels of LATS1/2 and the proportion of the phosphorylated form among total SLUG protein. Our results suggest that the LATS1/2-SLUG axis regulates the transition of SAS cells to the advanced stage via repeated switching between EMT and MET. Therefore, an anti-SLUG-pT208 antibody would be valuable not alone as a malignant tumor marker antibody but also as a prognostic tool for patients with malignant disease.

The clinicopathological and prognostic significances of LATS1 expression in breast cancer

AIM

Large tumor suppressor gene 1 (LATS1) belongs to the PKA/PKG/PKC serine/threonine kinase subfamily of the Hippo signaling pathway and inactivates nuclear co-activators YAP1 and WWTR1 by phosphorylation. This study aimed to discern the clinicopathological and prognostic significances of LATS1 expression in breast cancer.

METHODS

We examined LATS1 expression in breast carcinogenesis and compared it with clinicopathological parameters and survival information of breast cancer patients using immunohistochemistry, western blotting, RT-PCR, and bioinformatics analysis.

RESULTS

LATS1 expression was downregulated in breast cancer at both mRNA and protein levels (P<0.05). LATS1 mRNA expression was negatively correlated with low ER and PR expression, aggressive subtypes (TNBC and HER2+ vs. luminal), and poor survival (P<0.05). Its protein expression was negatively linked to patient age, T stage, N stage, M stage histological grade, PR status, and unfavorable prognosis (P<0.05). There was a positive correlationship between nuclar and cytoplasmic LATS1 expression in breast cancer (P<0.05).

CONCLUSIONS

The downregulation of LATS1 expression plays a vital role in the carcinogenesis and progression of breast cancer. Thus, LATS1 loss was employed to indicate the aggressive behaviors and poor prognosis of breast cancer.

LATS1 is a central signal transmitter for achieving full type-I interferon activity

Interferons (IFNs) have broad-spectrum antiviral activity to resist virus epidemic. However, IFN antiviral efficacy needs to be greatly improved. Here, we reveal that LATS1 is a vital signal transmitter governing full type-I IFN (IFN-I) signaling activity. LATS1 constitutively binds with the IFN-I receptor IFNAR2 and is rapidly tyro-phosphorylated by Tyk2 upon IFN-I engagement. Tyro-phosphorylation of LATS1 promotes LATS1 activation and YAP degradation, thereby promoting IFN-mediated antiproliferation activity. Moreover, activated LATS1 translocates into the nucleus and induces CDK8-Ser62 phosphorylation, which in turn phosphorylates STAT1 at Ser727 and induces full IFN-I antiviral activity. LATS1 deficiency restricts in vivo IFN-I signaling and attenuates host antiviral immune response. Our study identifies IFN-I as a previously unidentified extracellular diffusible ligand signal for activation of the Hippo core LATS1 pathway and reveals Tyk2-LATS1-CDK8 as a complete signaling cascade controlling full IFN-I activity.

The Hippo Signaling Pathway in Cancer: A Cell Cycle Perspective

Simple Summary

Cancer is increasingly viewed as a cell cycle disease in that the dysregulation of the cell cycle machinery is a common feature in cancer. The Hippo signaling pathway consists of a core kinase cascade as well as extended regulators, which together control organ size and tissue homeostasis. The aberrant expression of cell cycle regulators and/or Hippo pathway components contributes to cancer development, and for this reason, we specifically focus on delineating the roles of the Hippo pathway in the cell cycle. Improving our understanding of the Hippo pathway from a cell cycle perspective could be used as a powerful weapon in the cancer battlefield.

Abstract

Cell cycle progression is an elaborate process that requires stringent control for normal cellular function. Defects in cell cycle control, however, contribute to genomic instability and have become a characteristic phenomenon in cancers. Over the years, advancement in the understanding of disrupted cell cycle regulation in tumors has led to the development of powerful anti-cancer drugs. Therefore, an in-depth exploration of cell cycle dysregulation in cancers could provide therapeutic avenues for cancer treatment. The Hippo pathway is an evolutionarily conserved regulator network that controls organ size, and its dysregulation is implicated in various types of cancers. Although the role of the Hippo pathway in oncogenesis has been widely investigated, its role in cell cycle regulation has not been comprehensively scrutinized. Here, we specifically focus on delineating the involvement of the Hippo pathway in cell cycle regulation. To that end, we first compare the structural as well as functional conservation of the core Hippo pathway in yeasts, flies, and mammals. Then, we detail the multi-faceted aspects in which the core components of the mammalian Hippo pathway and their regulators affect the cell cycle, particularly with regard to the regulation of E2F activity, the G1 tetraploidy checkpoint, DNA synthesis, DNA damage checkpoint, centrosome dynamics, and mitosis. Finally, we briefly discuss how a collective understanding of cell cycle regulation and the Hippo pathway could be weaponized in combating cancer.

The Dictyostelium Centrosome

The centrosome of Dictyostelium amoebae contains no centrioles and consists of a cylindrical layered core structure surrounded by a corona harboring microtubule-nucleating γ-tubulin complexes. It is the major centrosomal model beyond animals and yeasts. Proteomics, protein interaction studies by BioID and superresolution microscopy methods led to considerable progress in our understanding of the composition, structure and function of this centrosome type. We discuss all currently known components of the Dictyostelium centrosome in comparison to other centrosomes of animals and yeasts.

Cellular feedback dynamics and multilevel regulation driven by the hippo pathway

The Hippo pathway is a dynamic cellular signalling nexus that regulates differentiation and controls cell proliferation and death. If the Hippo pathway is not precisely regulated, the functionality of the upstream kinase module is impaired, which increases nuclear localisation and activity of the central effectors, the transcriptional co-regulators YAP and TAZ. Pathological YAP and TAZ hyperactivity consequently cause cancer, fibrosis and developmental defects. The Hippo pathway controls an array of fundamental cellular processes, including adhesion, migration, mitosis, polarity and secretion of a range of biologically active components. Recent studies highlight that spatio-temporal regulation of Hippo pathway components are central to precisely controlling its context-dependent dynamic activity. Several levels of feedback are integrated into the Hippo pathway, which is further synergized with interactors outside of the pathway that directly regulate specific Hippo pathway components. Likewise, Hippo core kinases also ‘moonlight’ by phosphorylating multiple substrates beyond the Hippo pathway and thereby integrates further flexibility and robustness in the cellular decision-making process. This topic is still in its infancy but promises to reveal new fundamental insights into the cellular regulation of this therapeutically important pathway. We here highlight recent advances emphasising feedback dynamics and multilevel regulation of the Hippo pathway with a focus on mitosis and cell migration, as well as discuss potential productive future research avenues that might reveal novel insights into the overall dynamics of the pathway.

Interaction of the Hippo Pathway and Phosphatases in Tumorigenesis

The Hippo pathway is an emerging tumor suppressor signaling pathway involved in a wide range of cellular processes. Dysregulation of different components of the Hippo signaling pathway is associated with a number of diseases including cancer. Therefore, identification of the Hippo pathway regulators and the underlying mechanism of its regulation may be useful to uncover new therapeutics for cancer therapy. The Hippo signaling pathway includes a set of kinases that phosphorylate different proteins in order to phosphorylate and inactivate its main downstream effectors, YAP and TAZ. Thus, modulating phosphorylation and dephosphorylation of the Hippo components by kinases and phosphatases play critical roles in the regulation of the signaling pathway. While information regarding kinase regulation of the Hippo pathway is abundant, the role of phosphatases in regulating this pathway is just beginning to be understood. In this review, we summarize the most recent reports on the interaction of phosphatases and the Hippo pathway in tumorigenesis. We have also introduced challenges in clarifying the role of phosphatases in the Hippo pathway and future direction of crosstalk between phosphatases and the Hippo pathway.

Expression of large tumour suppressor (LATS) kinases modulates chemotherapy response in advanced non-small cell lung cancer

Background

The Hippo signalling pathway plays an important role in regulating organ size and cell proliferation. Down-regulation of large tumour suppressor (LATS) protein homologs LATS1 or LATS2 has been found in lung cancer. LATS1 and LATS2 are the core components of the Hippo signalling pathway. LATS1 and LATS2 share some conserved structural features and exhibit redundant biological functions. The aim of this study was to dissect the interaction between these two homologs.

Methods

In lung adenocarcinoma (AD) cells, protein expression of LATS1 and LATS2 were determined by western blotting; cell viability and apoptosis were measured by MTT and annexin V staining after treatment with cisplatin; subcellular distributions of LATS proteins were determined by immunofluorescence microscopy; LATS2 expression was modulated by shRNA-mediated knockdown or ectopic expression in cancer cell lines.

Results

Manipulation of the expression of these two LATS kinases influenced cisplatin response in advanced lung AD cell lines. High LATS2-to-LATS1 ratio in H2023 cells was associated with cisplatin resistance, while low LATS2-to-LATS1 ratio in CL1-0 and CL83 cells was associated with sensitivity to cisplatin. Manipulating the LATS2-to-LATS1 ratio by LATS2 over-expression in CL1-0 and CL83 rendered them resistant to cisplatin treatment, whereas LATS2 knockdown in H2023 alleviated the LATS2-to-LATS1 ratio and sensitized cancer cells to cisplatin exposure.

Conclusions

Our data suggested that the ratio of expression of LATS kinases played a role in the modulation of cisplatin sensitivity in advanced lung AD, and targeting of LATS proteins as a novel therapeutic strategy for lung AD deserves further investigation.

The Centrosome Linker and Its Role in Cancer and Genetic Disorders

Centrosome cohesion, the joining of the two centrosomes of a cell, is increasingly appreciated as a major regulator of cell functions such as Golgi organization and cilia positioning. One major element of centrosome cohesion is the centrosome linker that consists of a growing number of proteins. The timely disassembly of the centrosome linker enables centrosomes to separate and assemble a functional bipolar mitotic spindle that is crucial for maintaining genomic integrity. Exciting new findings link centrosome linker defects to cell transformation and genetic disorders. We review recent data on the molecular mechanisms of the assembly and disassembly of the centrosome linker, and discuss how defects in the proper execution of these processes cause DNA damage and genomic instability leading to disease.

Aqueous extract of bulbus Fritillaria cirrhosa induces cytokinesis failure by blocking furrow ingression in human colon epithelial NCM460 cells

Bulbus Fritillariacirrhosa D. Don (BFC) has been widely used as an herbal medicament for respiratory diseases in China for over 2000 years. The ethnomedicinal effects of BFC have been scientifically verified, nevertheless its toxicity has not been completely studied. Previously, we have reported that the aqueous extract of BFC induces mitotic aberrations and chromosomal instability (CIN) in human colon epithelial NCM460 cells via dysfunctioning the mitotic checkpoint. Here, we extend this study and specifically focus on the influence of BFC on cytokinesis, the final step of cell division. One remarkable change in NCM460 cells following BFC treatment is the high incidence of binucleated cells (BNCs). More detailed investigation of the ana-telophases reveals that furrow ingression, the first stage of cytokinesis, is inhibited by BFC. Asynchronous cultures treatment demonstrates that furrow ingression defects induced by BFCs are highly associated with the formation of BNCs in ensuing interphase, indicating the BNCs phenotype after BFC treatment was resulted from cytokinesis failure. In line with this, the expression of genes involved in the regulation of furrow ingression is significantly de-regulated by BFC (e.g., LATS-1/2 and Aurora-B are upregulated, and YB-1 is downregulated). Furthermore, long-term treatment of BFC elucidates that the BNCs phenotype is transient and the loss of BNCs is associated with increased frequency of micronuclei and nuclear buds, two biomarkers of CIN. In supporting of these findings, the Nin Jiom Pei Pa Koa and Chuanbei Pipa Gao, two commercially available Chinese traditional medicines containing BFC, are able to induce multinucleation and CIN in NCM460 cells. Altogether, these data provide the first in vitro experimental evidence linking BFC to cytokinesis failure and suggest the resultant BNCs may be intermediates to produce CIN progenies.

Yorkie and JNK Control Tumorigenesis in Drosophila Cells with Cytokinesis Failure

Cytokinesis failure may result in the formation of polyploid cells, and subsequent mitosis can lead to aneuploidy and tumor formation. Tumor suppressor mechanisms limiting the oncogenic potential of these cells have been described. However, the universal applicability of these tumor-suppressive barriers remains controversial. Here, we use Drosophila epithelial cells to investigate the consequences of cytokinesis failure in vivo. We report that cleavage defects trigger the activation of the JNK pathway, leading to downregulation of the inhibitor of apoptosis DIAP1 and programmed cell death. Yorkie overcomes the tumor-suppressive role of JNK and induces neoplasia. Yorkie regulates the cell cycle phosphatase Cdc25/string, which drives tumorigenesis in a context of cytokinesis failure. These results highlight the functional significance of the JNK pathway in epithelial cells with defective cytokinesis and elucidate a mechanism used by emerging tumor cells to bypass this tumor-suppressive barrier and develop into tumors.

LATS1/2 kinases trigger self-renewal of cancer stem cells in aggressive oral cancer

Cancer stem cells (CSCs), which play important roles in tumor initiation and progression, are resistant to many types of therapies. However, the regulatory mechanisms underlying CSC-specific properties, including self-renewal, are poorly understood. Here, we found that LATS1/2, the core Hippo pathway-kinases, were highly expressed in the oral squamous cell carcinoma line SAS, which exhibits high capacity of CSCs, and that depletion of these kinases prevented SAS cells from forming spheres under serum-free conditions. Detailed examination of the expression and activation of LATS kinases and related proteins over a time course of sphere formation revealed that LATS1/2 were more highly expressed and markedly activated before initiation of self-renewal. Moreover, TAZ, SNAIL, CHK1/2, and Aurora-A were expressed in hierarchical, oscillating patterns during sphere formation, suggesting that the process consists of four sequential steps. Our results indicate that LATS1/2 trigger self-renewal of CSCs by regulating the Hippo pathway, the EMT, and cell division.

The hippo pathway provides novel insights into lung cancer and mesothelioma treatment

PURPOSE

Lung cancer and mesothelioma are two types of respiratory disease that have fatal courses and poor prognoses. Although a substantial number of targeted small molecules and antibody drugs have been developed, the 5-year survival rates of these patients remain relatively low. Moreover, most patients inevitably develop clinical resistance to treatment. Therefore, novel therapeutic options and cancer prognostic biomarkers are urgently needed.

METHODS

In this review, we summarized the recent literature from various electronic databases, including PubMed, and highlighted the most advanced findings regarding the hippo pathway in lung cancer and mesothelioma.

CONCLUSION

The hippo signaling transduction pathway has been demonstrated to play crucial roles in lung cancer and mesothelioma pathogenesis, including tumor development and multidrug resistance, and is emerging as a promising therapeutic target, potentially providing new tools for the detection of these tumors at an early stage.

Isolation of cancer cells with augmented spheroid-forming capability using a novel tool equipped with removable filter

Three-dimensional (3D) cell culture systems have been used to obtain multicellular spheroidal cell aggregates, or spheroids, from cancer cells. However, it is difficult to efficiently prepare large tumor-derived spheroids from cancer cells. To circumvent this problem, we here used a tool equipped with removal membrane, called Spheroid Catch, for the selection and enrichment of large-sized and/or size-matched spheroids from human squamous cell carcinoma (SAS cells) without loss of recovery. After a five-round process of selection and enrichment, we successfully isolated a subpopulation of SAS cells with augmented spheroid-forming capability, named eSAS: the efficiency of spheroid formation is 28.5% (eSAS) vs 16.8% (parental SAS). Notably, we found that some of eSAS cells survived after exposure of high doses of cisplatin in 3D culture. Moreover, orthotopic implantation by injecting eSAS cells into the tongues of nude mice showed reduced survival rate and increased tumor growth compared with those of nude mice injected with SAS cells. These results suggest that spheroids exhibiting properties of higher spheroid forming capacity can be efficiently collected by using Spheroid Catch. Indeed, genome-wide cDNA microarray and western blot analyses demonstrated higher mRNA and protein levels of hedgehog acyltransferase (HHAT), which is associated with stem maintenance in cell carcinoma by catalysing the N-palmitoylation of Hedgehog proteins, in eSAS cells than in SAS cells. We propose that Spheroid Catch could be useful for the study of spheroids, and potentially organoids, in the basic and clinical sciences, as an alternative method to other type of cell strainers.

Induction of miR-15a expression by tripterygium glycosides caused premature ovarian failure by suppressing the Hippo-YAP/TAZ signaling effector Lats1

Tripterygium glycosides (TGs) are chemotherapeutic drugs and immunosuppressant agents for the treatment of cancer and autoimmune diseases. We have previously reported that TGs induces premature ovarian failure (POF) by inducing cytotoxicity in ovarian granulosa cells (OGCs). Hence, we report that TGs suppress the expression of the Hippo-YAP/TAZ pathway in murine OGCs in vitro and in vivo. We found that the expressions of miR-181b, miR-15a, and miR-30d, were elevated significantly in the POF. Luciferase reporter assays confirmed that miR-15a targets Lats1 through a miR-15a binding site in the Lats1 3'UTR. Overexpression of miR-15a in mOGCs not only inhibited proliferation and growth of mOGCs, but also induced aging of mOGCs. Western blot and qPCR analysis indicated that miR-15a suppresses the expression of the Hippo-YAP/TAZ pathway in mOGCs. When the exogenous miR-15a was expressed on mouse OGCs, it could elevate the cytotoxicity effect of TG on mOGCs. We conclude that tripterygium glycosides promote cytotoxicity, senescence, and apoptosis in ovarian granulosa cells by inducing endogenous miR-15a expression and inhibiting the Hippo-YAP/TAZ pathway.

LATS1 inhibits metastasis and epithelial-mesenchymal transition in head and neck squamous cell carcinoma

LATS1 is a serine/threonine kinase of the Hippo signaling pathway that phosphorylates and inactivates transcriptional co-activators YAP1 and WWTR1. To investigate roles of LATS1 expression in head and neck squamous cell carcinomas (HNSCCs), we transfected LATS1-expressing plasmid into B88 cells and examined the phenotypes and their relevant molecules. LATS1 expression was analyzed using immunohistochemistry on tissue microarray, Oncomine, and TCGA databases. LATS1 overexpression was found to suppress growth, migration and invasion, and induce apoptosis, G2 arrest, and mesenchymal to epithelial transition (MET) (P < 0.05). Both increased expression of P21, Bax, and E-cadherin and decreased expression of Cyclin B1, D1, Bcl-2, and MMPs. Twist and N-cadherin were detected in B88 transfectants, in comparison to mock and control by Western blot. Nuclear LATS1 expression was weaker in primary cancers than in normal squamous tissue and dysplasia (P < 0.05) but versa for cytoplasmic counterpart (P < 0.05). Cytoplasmic LATS1 expression was positively correlated with lymph node metastasis (P < 0.05). Survival analysis showed that differentiation degree was an independent factor of long overall and relapse-free survival of HNSCC patients (P < 0.05). According to bioinformatics analysis, we found upregulated LATS1 mRNA expression in HNSCCs (P < 0.05). Cox proportional hazards model indicated that perineural invasion and distant metastasis were independent prognostic factors for overall survival of HNSCC (P < 0.05). These findings suggest nucleocytoplasmic translocation of LATS1 protein and upregulated expression of LATS1 mRNA during tumorigenesis of HNSCC. LATS1 mRNA overexpression may reverse aggressive phenotypes of HNSCC cells, as a gene therapy target.

The LATS1 and LATS2 tumor suppressors: beyond the Hippo pathway

Proper cellular functionality and homeostasis are maintained by the convergent integration of various signaling cascades, which enable cells to respond to internal and external changes. The Dbf2-related kinases LATS1 and LATS2 (LATS) have emerged as central regulators of cell fate, by modulating the functions of numerous oncogenic or tumor suppressive effectors, including the canonical Hippo effectors YAP/TAZ, the Aurora mitotic kinase family, estrogen signaling and the tumor suppressive transcription factor p53. While the basic functions of the LATS kinase module are strongly conserved over evolution, the genomic duplication event leading to the emergence of two closely related kinases in higher organisms has increased the complexity of this signaling network. Here, we review the LATS1 and LATS2 intrinsic features as well as their reported cellular activities, emphasizing unique characteristics of each kinase. While differential activities between the two paralogous kinases have been reported, many converge to similar pathways and outcomes. Interestingly, the regulatory networks controlling the mRNA expression pattern of LATS1 and LATS2 differ strongly, and may contribute to the differences in protein binding partners of each kinase and in the subcellular locations in which each kinase exerts its functions.