Lactate receptor HCAR1 regulates cell growth, metastasis and maintenance of cancer­specific energy metabolism in breast cancer cells.

Under aerobic conditions, the preferential use of anaerobic glycolysis by tumour cells leads to a high level of lactate accumulation in tumour microenvironment. Lactate acts not only as a cellular energy source but also as a signalling molecule that regulates cancer cell growth, metastasis and metabolism. It has been reported that a G­protein­coupled receptor for lactate named hydroxycarboxylic acid receptor 1 (HCAR1) is highly expressed in numerous types of cancer, but the detailed mechanism remains unclear. In the present study, it was reported that HCAR1 is highly expressed in breast cancer cells. Genetic deletion of HCAR1 in MCF7 cells leads to reduced cell proliferation and migration. Moreover, it was observed that knockout (KO) of HCAR1 attenuated the expression and activity of phosphofructokinase and hexokinase, key rate­limiting enzymes in glycolysis. Using an extracellular flux analyzer, it was showed that KO of HCAR1 promoted a metabolic shift towards a decreased glycolysis state, as evidenced by a decreased extracellular acidification rate and increased oxygen consumption rate in MCF7 cells. Taken together, our results suggested that lactate acts through HCAR1 as a metabolic regulator in breast cancer cells that may be therapeutically exploited.

Sphingosine-1-Phosphate-Triggered Expression of Cathelicidin LL-37 Promotes the Growth of Human Bladder Cancer Cells.

It has been proven that tumour growth and progression are regulated by a variety of mediators released during the inflammatory process preceding the tumour appearance, but the role of inflammation in the development of bladder cancer is ambiguous. This study was designed around the hypothesis that sphingosine-1-phosphate (S1P), as a regulator of several cellular processes important in both inflammation and cancer development, may exert some of the pro-tumorigenic effects indirectly due to its ability to regulate the expression of human cathelicidin (hCAP-18). LL-37 peptide released from hCAP-18 is involved in the development of various types of cancer in humans, especially those associated with infections. Using immunohistological staining, we showed high expression of hCAP-18/LL-37 and sphingosine kinase 1 (the enzyme that forms S1P from sphingosine) in human bladder cancer cells. In a cell culture model, S1P was able to stimulate the expression and release of hCAP-18/LL-37 from human bladder cells, and the addition of LL-37 peptide dose-dependently increased their proliferation. Additionally, the effect of S1P on LL-37 release was inhibited in the presence of FTY720P, a synthetic immunosuppressant that blocks S1P receptors. Together, this study presents the possibility of paracrine relation in which LL-37 production following cell stimulation by S1P promotes the development and growth of bladder cancer.

Effect of information fields from written texts on cell growth and mitochondrial functions in-vitro: An exploratory study.

OBJECTIVE: Mitochondria are considered a portal to receive, process and integrate external energy and information to maintain cellular homeostasis. We examined the effect of Chinese texts with positive and negative meaning on the growth and mitochondrial functions using a mouse kidney collecting duct cell line called M1 cells. METHODS: To avoid skewing the results due to differential handling of the cells or analyzing the results, we conducted experiments by keeping the texts and blanks covered in brown opaque envelopes, exposed the cells to randomly selected envelopes and examined the differences over time. All operators involved in the experiments did not know the contents of the envelopes until the end of the experiments, and all data are expressed relative to the controls. RESULTS: Cell growth rate was not affected for the group treated with positive information but was significantly reduced by 18% when treated with negative information. At the biochemical level, positive texts significantly increased whole cell adenosine triphosphate (ATP) and glutathione (GSH) by 22% and 21% respectively. CONCLUSIONS: This study for the first time demonstrated the effect of written words on specific biochemical measures in cultured mammalian cells.

TLR2 activation promotes tumour growth and associates with patient survival and chemotherapy response in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, and is plagued by a paucity of targeted treatment options and tumour resistance to chemotherapeutics. The causal link between chronic inflammation and PDAC suggests that molecular regulators of the immune system promote disease pathogenesis and/or therapeutic resistance, yet their identity is unclear. Here, we couple endoscopic ultrasound-guided fine-needle aspiration, which captures tumour biopsies from all stages, with whole transcriptome profiling of PDAC patient primary tumours to reveal enrichment of the innate immune Toll-like receptor 2 (TLR2) molecular pathway. Augmented TLR2 expression associated with a 4-gene "TLR2 activation" signature, and was prognostic for survival and predictive for gemcitabine-based chemoresistance. Furthermore, antibody-mediated anti-TLR2 therapy suppressed the growth of human PDAC tumour xenografts, independent of a functional immune system. Our results support TLR2-based therapeutic targeting for precision medicine in PDAC, with further clinical utility that TLR2 activation is prognostic and predictive for chemoresponsiveness.

CLK1/SRSF5 pathway induces aberrant exon skipping of METTL14 and Cyclin L2 and promotes growth and metastasis of pancreatic cancer.

BACKGROUND: Both aberrant alternative splicing and m6A methylation play complicated roles in the development of pancreatic cancer (PC), while the relationship between these two RNA modifications remains unclear. METHODS: RNA sequencing (RNA-seq) was performed using 15 pairs of pancreatic ductal adenocarcinoma (PDAC) tissues and corresponding normal tissues, and Cdc2-like kinases 1 (CLK1) was identified as a significantly upregulated alternative splicing related gene. Real-time quantitative PCR (qPCR) and western blotting were applied to determine the CLK1 levels. The prognostic value of CLK1 was elucidated by Immunohistochemistry (IHC) analyses in two independent PDAC cohorts. The functional characterizations and mechanistic insights of CLK1 in PDAC growth and metastasis were evaluated with PDAC cell lines and nude mice. SR-like splicing factors5250-Ser (SRSF5250-Ser) was identified as an important target phosphorylation site by phosphorylation mass spectrometry. Through transcriptome sequencing, Methyltransferase-like 14exon10 (METTL14exon10) and Cyclin L2exon6.3 skipping were identified as key alternative splicing events regulated by the CLK1-SRSF5 axis. RIP assays, RNA-pulldown and CLIP-qPCR were performed to confirm molecular interactions and the precise binding sites. The roles of the shift of METTL14exon 10 and Cyclin L2exon6.3 skipping were surveyed. RESULTS: CLK1 expression was significantly increased in PDAC tissues at both the mRNA and protein levels. High CLK1 expression was associated with poor prognosis. Elevated CLK1 expression promoted growth and metastasis of PC cells in vitro and in vivo. Mechanistically, CLK1 enhanced phosphorylation on SRSF5250-Ser, which inhibited METTL14exon10 skipping while promoted Cyclin L2exon6.3 skipping. In addition, aberrant METTL14exon 10 skipping enhanced the N6-methyladenosine modification level and metastasis, while aberrant Cyclin L2exon6.3 promoted proliferation of PDAC cells. CONCLUSIONS: The CLK1/SRSF5 pathway induces aberrant exon skipping of METTL14 and Cyclin L2, which promotes growth and metastasis and regulates m6A methylation of PDAC cells. This study suggests the potential prognostic value and therapeutic targeting of this pathway in PDAC patients.

Inhibition of retinoic acid receptor α phosphorylation represses the progression of triple-negative breast cancer via transactivating miR-3074-5p to target DHRS3.

BACKGROUND: Retinoids are promising agents in the treatment of different types of neoplasia including estrogen receptor-positive breast cancers, whereas refractoriness/low sensitivity is observed in triple-negative breast cancer (TNBC) subtype. However, the reason for these diverse retinoid-sensitivity remains elusive. METHODS: Determinants of retinoid sensitivity were investigated using immunohistochemistry of primary patient samples, and identified retinoic acid receptor α (RARα) as a putative factor. The anti-tumor activity of hypo-phosphorylated RARα was investigated in TNBC cell models and a xenograft mouse model. Next, miRNA sequencing analysis was performed to identify the target miRNA of RARα, and luciferase reporter was used to confirm the direct target gene of miR-3074-5p. RESULTS: We discovered that serine-77 residue of RARα was constantly phosphorylated, which correlated with TNBC's resistance to retinoids. Overexpression of a phosphorylation-defective mutant RARαS77A mimicked activated RARα and repressed TNBC cell progression both in vitro and in vivo, via activating cell cycle arrest, apoptosis, and cytotoxic autophagy, independent of RARα agonists. We further revealed that the anti-tumor action of RARαS77A was, at least in part, mediated by the up-regulation of miR-3074-5p, which directly targeted DHRS3, a reductase negatively associated with TNBC patient survival. Our results suggest that the inhibition of RARαS77 phosphorylation by either expressing RARαS77A or inhibiting RARα's phosphokinase CDK7, can bypass RA stimuli to transactivate tumor-suppressive miR-3074-5p and reduce oncogenic DHRS3, thus overcoming the RA-resistance of TNBC. CONCLUSION: The novel regulatory network, involving RARαS77 phosphorylation, miR-3074-5p, and DHRS3, emerges as a new target for TNBC treatment.

miR-548b Suppresses Melanoma Cell Growth, Migration, and Invasion by Negatively Regulating Its Target Gene HMGB1.

Background: Melanoma is one of the most aggressive malignancies. Exploration of metastasis-related genes will improve the clinical outcomes of patients with melanoma. Recently, microRNAs (miRNAs) have been implicated in regulating the aggressiveness of melanoma. In the current study, the author demonstrated the expression of miR-548b and its functions in melanoma. Materials and Methods: The expression levels of miR-548b and high mobility group protein 1 (HMGB1) in melanoma specimens and adjacent normal tissues were examined using the quantitative real-time PCR method. The Cell Counting Kit-8 (CCK-8), wound healing test, and Transwell assays were conducted to examine the impact of miR-548b on aggressive phenotypes of melanoma cells. The protein expression of HMGB1 was detected by Western blot. The tumor growth of melanoma cells in vivo was analyzed using the transplanted tumor model. The expression of HMGB1 in vivo was assessed using immunohistochemistry assay. Results: miR-548b was significantly downregulated in the melanoma sample when compared with adjacent normal tissues. In addition, low levels of miR-548b were related to poor overall survival in patients with melanoma. As predicted, overexpression of miR-548b suppressed the growth and metastasis-associated traits of melanoma cells. Furthermore, the luciferase reporter gene assay and Western blotting revealed that HMGB1 was a target of miR-548b and its expression level was negatively modulated by miR-548b. Several rescue experiments indicated that reintroduction of HMGB1 abolished the inhibiting effects of miR-548b on melanoma cells. Finally, the author demonstrated that upregulation of miR-548b repressed melanoma cell growth in vivo. Conclusions: All these findings demonstrate that miR-548b serves as a cancer-suppressive miRNA in human melanoma by inhibiting HMGB1.

Lipid droplet storage promotes murine pancreatic tumor growth.

Hypoxia Inducible Lipid Droplet Associated (HILPDA) is frequently overexpressed in tumors and promotes neutral lipid storage. The impact of Hilpda on pancreatic ductal adenocarcinoma (PDAC) tumor growth is not known. In order to evaluate Hilpda­dependent lipid storage mechanisms, expression of Hilpda in murine pancreatic cells (KPC) was genetically manipulated. Lipid droplet (LD) abundance and triglyceride content in vitro were measured, and model tumor growth in nu/nu mice was determined. The results showed that excess lipid supply increased triglyceride storage and LD formation in KPC cells in a HILPDA­dependent manner. Contrary to published results, inhibition of Adipose Triglyceride Lipase (ATGL) did not ameliorate the triglyceride abundance differences between Hilpda WT and KO cells. Hilpda ablation significantly decreased the growth rate of model tumors in immunocompromised mice. In conclusion, Hilpda is a positive regulator of triglyceride storage and lipid droplet formation in murine pancreatic cancer cells in vitro and lipid accumulation and tumor growth in vivo. Our data suggest that deregulated ATGL is not responsible for the absence of LDs in KO cells in this context.

c-Src facilitates tumorigenesis by phosphorylating and activating G6PD.

Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme in pentose phosphate pathway (PPP), excessive activation of which has been considered to be involved in tumorigenesis. Here, we show that tyrosine kinase c-Src interacts with and phosphorylates G6PD at Tyr 112. This phosphorylation enhances catalytic activity of G6PD by dramatically decreasing its Km value and increasing its Kcat value for substrate glucose-6-phosphate. Activated G6PD therefore augments the PPP flux for NADPH and ribose-5-phosphate production which is required for detoxification of intracellular reactive oxygen species (ROS) and biosynthesis of cancer cells, and eventually contributes to tumorigenesis. Consistently, c-Src activation is closely correlated with tyrosine phosphorylation and activity of G6PD in clinical colorectal cancer samples. We thus uncover another aspect of c-Src in promoting cell proliferation and tumorigenesis, deepening our understanding of c-Src as a proto-oncogene.

Platelets as messengers of early-stage cancer.

Platelets have an important role in tumor angiogenesis, growth, and metastasis. The reciprocal interaction between cancer and platelets results in changes of several platelet characteristics. It is becoming clear that analysis of these platelet features could offer a new strategy in the search for biomarkers of cancer. Here, we review the human studies in which platelet characteristics (e.g., count, volume, protein, and mRNA content) are investigated in early-stage cancer. The main focus of this paper is to evaluate which platelet features are suitable for the development of a blood test that could detect cancer in its early stages.

Viscoelastic substrate decouples cellular traction force from other related phenotypes.

Survival and maintenance of normal physiological functions depends on continuous interaction of cells with its microenvironment. Cells sense the mechanical properties of underlying substrate by applying force and modulate their behaviour in response to the resistance offered by the substrate. Most of the studies addressing cell-substrate mechanical interactions have been carried out using elastic substrates. Since tissues within our body are viscoelastic in nature, here we explore the effect of substrate's viscoelasticity on various properties of mesenchymal stem cells. Here, we used two sets of polyacrylamide substrates having similar storage modulus (G' = 1.1-1.6 kPa) but different loss modulus (G" = 45 Pa and 300 Pa). We report that human mesenchymal stem cells spread more but apply less force on the viscoelastic substrate (substrate with higher loss modulus). We further investigated the effect of substrate viscoelasticity on the expression of other contractility-associated proteins such as focal adhesion (FA) proteins (Vinculin, Paxillin, Talin), cytoskeletal proteins (actin, mysion, intermediate filaments, and microtubules) and mechano-sensor protein Yes-Associated Protein (YAP). Our results show that substrate viscoelasticity decouples cellular traction from other known traction related phenotypes.

Impaired in vitro growth response of plasma-treated cardiomyocytes predicts poor outcome in patients with transthyretin amyloidosis.

OBJECTIVES: Direct toxic effects of transthyretin amyloid in patient plasma upon cardiomyocytes are discussed. However, no data regarding the relevance of this putative effect for clinical outcome are available. In this monocentric prospective study, we analyzed cellular hypertrophy after phenylephrine stimulation in vitro in the presence of patient plasma and correlated the cellular growth response with phenotype and prognosis. METHODS AND RESULTS: Progress in automated microscopy and image analysis allows high-throughput analysis of cell morphology. Using the InCell microscopy system, changes in cardiomyocyte's size after treatment with patient plasma from 89 patients suffering from transthyretin amyloidosis and 16 controls were quantified. For this purpose, we propose a novel metric that we named Hypertrophic Index, defined as difference in cell size after phenylephrine stimulation normalized to the unstimulated cell size. Its prognostic value was assessed for multiple endpoints (HTX: death/heart transplantation; DMP: cardiac decompensation; MACE: combined) using Cox proportional hazard models. Cells treated with plasma from healthy controls and hereditary transthyretin amyloidosis with polyneuropathy showed an increase in Hypertrophic Index after phenylephrine stimulation, whereas stimulation after treatment with hereditary cardiac amyloidosis or wild-type transthyretin patient plasma showed a significantly attenuated response. Hypertrophic Index was associated in univariate analyses with HTX (hazard ratio (HR) high vs low: 0.12 [0.02-0.58], p = 0.004), DMP: (HR 0.26 [0.11-0.62], p = 0.003) and MACE (HR 0.24 [0.11-0.55], p < 0.001). Its prognostic value was independent of established risk factors, cardiac TroponinT or N-terminal prohormone brain natriuretic peptide (NTproBNP). CONCLUSIONS: Attenuated cardiomyocyte growth response after stimulation with patient plasma in vitro is an independent risk factor for adverse cardiac events in ATTR patients.

HN1 promotes tumor growth and metastasis of anaplastic thyroid carcinoma by interacting with STMN1.

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies frequently associated with extrathyroidal extension and metastasis through pathways that remain unclear. Analysis of the cancer genome atlas (TCGA) database and an independent cohort showed that the expression of hematological and neurological expressed 1 (HN1) was higher in thyroid cancers than in normal tissues, and negatively correlated with progression-free survival. RT-PCR and immunohistochemistry revealed higher HN1 expression in ATC compared to healthy tissues and papillary thyroid carcinoma (PTC). HN1 knockdown attenuated migration and invasion of ATC cells, whereas HN1 overexpression increased migration and invasion of PTC cells. HN1 reduced the acetylation of α-tubulin and promoted progression through epithelial-mesenchymal transition of ATC cells and mouse xenografts. HN1 knockdown significantly attenuated TGF-ß-induced mesenchymal phenotype, and inhibited tumor formation and growth of ATC xenografts in nude mice. Loss of STMN1 decreased the malignant potential of HN1, whereas HN1 knockdown in combination with STMN1 overexpression restored the aggressive properties of ATC cells. HN1 increased STMN1 mRNA expression, and prevented STMN1 ubiquitination and subsequent degradation. These results demonstrate that HN1 interacts with STMN1 and drives ATC aggressiveness.

The Ubiquitin-Specific Peptidase USP18 Promotes Lipolysis, Fatty Acid Oxidation, and Lung Cancer Growth.

Ubiquitin specific peptidase 18 (USP18), previously known as UBP43, is the IFN-stimulated gene 15 (ISG15) deconjugase. USP18 removes ISG15 from substrate proteins. This study reports that USP18-null mice (vs. wild-type mice) exhibited lower lipolysis rates, altered fat to body weight ratios, and cold sensitivity. USP18 is a regulator of lipid and fatty acid metabolism. Prior work established that USP18 promotes lung tumorigenesis. We sought to learn whether this occurs through altered lipid and fatty acid metabolism. Loss of USP18 repressed adipose triglyceride lipase (ATGL) expression; gain of USP18 expression upregulated ATGL in lung cancer cells. The E1-like ubiquitin activating enzyme promoted ISG15 conjugation of ATGL and destabilization. Immunoprecipitation assays confirmed that ISG15 covalently conjugates to ATGL. Protein expression of thermogenic regulators was examined in brown fat of USP18-null versus wild-type mice. Uncoupling protein 1 (UCP1) was repressed in USP18-null fat. Gain of USP18 expression augmented UCP1 protein via reduced ubiquitination. Gain of UCP1 expression in lung cancer cell lines enhanced cellular proliferation. UCP1 knockdown inhibited proliferation. Beta-hydroxybutyrate colorimetric assays performed after gain of UCP1 expression revealed increased cellular fatty acid beta-oxidation, augmenting fatty acid beta-oxidation in Seahorse assays. Combined USP18, ATGL, and UCP1 profiles were interrogated in The Cancer Genome Atlas. Intriguingly, lung cancers with increased USP18, ATGL, and UCP1 expression had an unfavorable survival. These findings reveal that USP18 is a pharmacologic target that controls fatty acid metabolism. IMPLICATIONS: USP18 is an antineoplastic target that affects lung cancer fatty acid metabolism.

Knockdown of EMMPRIN (OX47) in MRMT-1 Carcinoma Cells Inhibits Tumor Growth and Decreases Cancer-Induced Bone Destruction and Pain.

PURPOSE: Bone destruction and pain caused by cancer is one of the most devastating complications of cancer patients with bone metastases, and it seriously affects the quality of patients' life. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a cell adhesion molecule with increased expression in a variety of tumors. This study focused to clarify the specific function of EMMPRIN in bone metastasis of breast cancer. MATERIALS AND METHODS: Adenovirus with shRNA-EMMPRIN was transfected into MRMT-1 rat breast carcinoma cells, and the MRMT-1 cells with different expression levels of EMMPRIN were implanted into the bone marrow cavity of rat tibia. Next, the effect of down-regulation of EMMPRIN was evaluated as follows: bone damage was detected by X-ray radiological and tartrate-resistant acid phosphatase staining; the tumor burden was evaluated by hematoxylin and eosin staining; the test of pain-related behaviors was assessed used the bilateral paw withdrawal mechanical threshold; and the levels of secretory factors in tumor conditioned medium were determined by using enzyme-linked immunosorbent assay. RESULTS: We found that down-regulation of EMMPRIN in tumor cells can simultaneously reduce tumor burden, relieve cancer-induced bone destruction and pain. CONCLUSION: EMMPRIN is expected to be a therapeutic target for relieving bone metastasis of breast cancer and alleviating cancer-induced bone destruction and pain. The method of targeting EMMPRIN may be a promising strategy for the treatment of cancer in the future.

Ribosome 18S m6A Methyltransferase METTL5 Promotes Translation Initiation and Breast Cancer Cell Growth.

N6 methylation at adenosine 1832 (m6A1832) of mammalian 18S rRNA, occupying a critical position within the decoding center, is modified by a conserved methyltransferase, METTL5. Here, we find that METTL5 shows strong substrate preference toward the 18S A1832 motif but not the other reported m6A motifs. Comparison with a yeast ribosome structural model unmodified at this site indicates that the modification may facilitate mRNA binding by inducing conformation changes in the mammalian ribosomal decoding center. METTL5 promotes p70-S6K activation and proper translation initiation, and the loss of METTL5 significantly reduces the abundance of polysome. METTL5 expression is elevated in breast cancer patient samples and is required for growth of several breast cancer cell lines. We further find that Caenorhabditis elegans lacking the homolog metl-5 develop phenotypes known to be associated with impaired translation. Altogether, our findings uncover critical and conserved roles of METTL5 in the regulation of translation.

Self-generated persistent random forces drive phase separation in growing tumors.

A single solid tumor, composed of nearly identical cells, exhibits heterogeneous dynamics. Dynamics of cells in the core is glass-like, whereas those in the periphery undergoes diffusive or super-diffusive behavior. Quantification of heterogeneity using the mean square displacement or the self-intermediate scattering function, which involves averaging over the cell population, hides the complexity of the collective movement. Using the t-distributed stochastic neighbor embedding (t-SNE), a popular unsupervised machine learning dimensionality reduction technique, we show that the phase space structure of an evolving colony of cells, driven by cell division and apoptosis, partitions into nearly disjoint sets composed principally of the core and periphery cells. The non-equilibrium phase separation is driven by the differences in the persistence of self-generated active forces induced by cell division. Extensive heterogeneity revealed by t-SNE paves the way toward understanding the origins of intratumor heterogeneity using experimental imaging data.

ZEB1-activated LINC01123 accelerates the malignancy in lung adenocarcinoma through NOTCH signaling pathway.

Growing incidence of lung adenocarcinoma (LUAD) has been detected recently. Multiple long non-coding RNAs (lncRNAs) have been proven as tumor facilitators or inhibitors by extensive works. Present study concentrated on characterizing the potential role of LINC01123 in LUAD. We explored the differential expression of LINC01123 through qRT-PCR and found the amplification of LINC01123 in LUAD cell lines. It was ascertained that LINC01123 was definitely responsible for the malignant processes of LUAD cells. Further, we validated the ceRNA network of LINC01123/miR-449b-5p/NOTCH1 in LUAD via mechanical experiments. As a transcriptional factor related to epithelial mesenchymal transition (EMT), ZEB1 was responsible for the transcriptional activation of both LINC01123 and NOTCH1. The involvement of NOTCH signaling in LUAD was interrogated through evaluating functional changes after treating with FLI-06 (NOTCH pathway suppressor). It showed that FLI-06-caused NOTCH signaling inactivation suppressed malignant functions in LUAD cells. Additionally, LINC01123 facilitated NOTCH1-dependent NOTCH signaling activation. Rescue experiments probed the modulatory function of LINC01123/miR-449b-5p/NOTCH1 in LUAD cellular processes. Altogether, ZEB1-activated LINC01123 accelerates the malignancy in LUAD through miR-449b-5p/NOTCH1 axis-mediated NOTCH signaling pathway, while NOTCH1 boosts ZEB1 in return. These observations suggest the huge potential of LINC01123 as a new target for LUAD therapy.

MiR-920 and LSP1 co-regulate the growth and migration of glioblastoma cells by modulation of JAK2/STAT5 pathway.

This study probes the function and mechanism of lymphocyte-specific protein 1 (LSP1) in glioblastoma pathogenesis. According to the data acquired from TCGA, Oncomine and GEO databases, the expression and prognostic value of LSP1 and miR-920 in glioblastoma patients were analyzed. The expression levels of LSP1 in U251 and A172 cell lines were analyzed by qRT-PCR and western blotting. CCK8, colony formation and transwell assays were utilized to test glioblastoma cell malignant abilities. Furthermore, the associations between LSP1 and miR-920 were indentified by bioinformatics analysis and rescue assays. Moreover, the protein expression levels of p-JAK2, JAK2, p-STAT5 and STAT5, as the hallmark of JAK/STAT5 signaling, were detected by western blotting. The observations showed that LSP1 was highly augmented in glioblastoma samples. Additionally, up-regulation of LSP1 was associated with a unfavorable prognosis in glioblastoma patients. Biological experiments revealed that depletion of LSP1 significantly suppressed the proliferation, invasion and migration of U251 and A172 cells. MiR-920, as an upstream regulator of LSP1, negatively modulated LSP1 expression and promoted U251 cells malignant behaviors after miR-920 inhibitor treatment. However, together knockdown LSP1 and miR-920 inhibited these effects. Moreover, the expression levels of p-JAK2 and p-STAT5 were increased or decreased in U251 cells after transfection of miR-920 inhibitor or si-LPS1. Taken together, miR-920 might blocked the malignant development of glioblastoma cells, which is possibly realized by targeting LSP1 and modulation of JAK/STAT5 pathway. These findings implied that miR-920/LSP1 was a potential therapeutic target for glioblastoma treatment.

p190A RhoGAP induces CDH1 expression and cooperates with E-cadherin to activate LATS kinases and suppress tumor cell growth.

The ARHGAP35 gene encoding p190A RhoGAP (p190A) is significantly altered by both mutation and allelic deletion in human cancer, but the functional implications of such alterations are not known. Here, we demonstrate for the first time that p190A is a tumor suppressor using a xenograft mouse model with carcinoma cells harboring defined ARHGAP35 alterations. In vitro, restoration of p190A expression in carcinoma cells promotes contact inhibition of proliferation (CIP) through activation of LATS kinases and phosphorylation of the proto-oncogenic transcriptional co-activator YAP. In contrast, p190A forms harboring recurrent cancer mutations exhibit loss of function in modulating the Hippo pathway, inducing CIP, as well as attenuated suppression of tumor growth in mice. We determine that p190A promotes mesenchymal to epithelial transition (MET) and elicits expression of a cassette of epithelial adherens junction-associated genes in a cell density-dependent manner. This cassette includes CDH1 encoding E-cadherin, which amplifies p190A-mediated LATS activation and is necessary for CIP. Oppositely, we establish that p190A is obligatory for E-cadherin to activate LATS kinases and induce CIP. Collectively, this work defines a novel mechanism by which p190A and E-cadherin cooperate in modulating Hippo signaling to suppress tumor cell growth.