Suppressed Cell Spreading Research Articles

Timosaponin AIII Disrupts Cell-Extracellular Matrix Interactions through the Inhibition of Endocytic Pathways.

Timosaponin AIII (TAIII), a steroidal saponin isolated from the root of Anemarrhena asphodeloides Bunge, exhibits various pharmacological activities, including anti-cancer properties. TAIII inhibits the migration and invasion of various cancer cell types. However, the mechanism underlying how TAIII regulates the motility of cancer cells remains incompletely understood. In this study, we demonstrate that TAIII disrupted cell-extracellular matrix (ECM) interactions by inhibiting internalization of cell surface proteins, such as integrins. We found that TAIII inhibited cell adhesion on various ECMs. Structure-activity relationship analysis demonstrated that TAIII exhibited unique activity among the saponins from Anemarrhena asphodeloides Bunge and that the number and position of saccharide moieties were important for TAIII to exert its activity. Time lapse imaging revealed that TAIII also suppressed cell spreading on the ECM, membrane ruffling, and lamellipodia formation. Furthermore, we examined integrin β1 behaviors in response to TAIII treatment and found that TAIII blocked its internalization. These findings contribute to delineating the potential molecular mechanisms by which TAIII exerts anti-metastatic activity.

Selective Suppression of Integrin-Ligand Binding by Single Molecular Tension Probes Mediates Directional Cell Migration.

Cell migration interacting with continuously changing microenvironment, is one of the most essential cellular functions, participating in embryonic development, wound repair, immune response, and cancer metastasis. The migration process is finely tuned by integrin-mediated binding to ligand molecules. Although numerous biochemical pathways orchestrating cell adhesion and motility are identified, how subcellular forces between the cell and extracellular matrix regulate intracellular signaling for cell migration remains unclear. Here, it is showed that a molecular binding force across integrin subunits determines directional migration by regulating tension-dependent focal contact formation and focal adhesion kinase phosphorylation. Molecular binding strength between integrin αvβ3 and fibronectin is precisely manipulated by developing molecular tension probes that control the mechanical tolerance applied to cell-substrate interfaces. This data reveals that integrin-mediated molecular binding force reduction suppresses cell spreading and focal adhesion formation, attenuating the focal adhesion kinase (FAK)phosphorylation that regulates the persistence of cell migration. These results further demonstrate that manipulating subcellular binding forces at the molecular level can recapitulate differential cell migration in response to changes of substrate rigidity that determines the physical condition of extracellular microenvironment. Novel insights is provided into the subcellular mechanics behind global mechanical adaptation of the cell to surrounding tissue environments featuring distinct biophysical signatures.

Lidocaine inhibits migrationof tenocytesby downregulating focal adhesion kinaseand paxillin phosphorylation.

Lidocaine is the most frequently applied local infiltration anesthetic agent for treating tendinopathies. However, studies have discovered lidocaine to negatively affect tendon healing. In the current study, the molecular mechanisms and effects of lidocaine on tenocyte migration were evaluated. We treated tenocytes intrinsic to the Achilles tendons of Sprague-Dawley rats with lidocaine. The migration ability of cells was analyzed using electric cell-substrate impedance sensing (ECIS) and scratch wound assay. We then used a microscope to evaluate the cell spread. We assessed filamentous actin (F-actin) cytoskeleton formation through immunofluorescence staining. In addition, we used Western blot analysis to analyze the expression of phospho-focal adhesion kinase (FAK), FAK, phospho-paxillin, paxillin, and F-actin. We discovered that lidocaine had an inhibitory effect on the migration of tenocytes in the scratch wound assay and on the ECIS chip. Lidocaine treatment suppressed cell spreading and changed the cell morphology and F-actin distribution. Lidocaine reduced F-actin formation in the tenocyte during cell spreading; furthermore, it inhibited phospho-FAK, F-actin, and phospho-paxillin expression in the tenocytes. Our study revealed that lidocaine inhibits the spread and migration of tenocytes. The molecular mechanism potentially underlying this effect is downregulation of F-actin, phospho-FAK, and phospho-paxillin expression when cells are treated with lidocaine.

GEF-H1 Transduces FcεRI Signaling in Mast Cells to Activate RhoA and Focal Adhesion Formation during Exocytosis.

When antigen-stimulated, mast cells release preformed inflammatory mediators stored in cytoplasmic granules. This occurs via a robust exocytosis mechanism termed degranulation. Our previous studies revealed that RhoA and Rac1 are activated during mast cell antigen stimulation and are required for mediator release. Here, we show that the RhoGEF, GEF-H1, acts as a signal transducer of antigen stimulation to activate RhoA and promote mast cell spreading via focal adhesion (FA) formation. Cell spreading, granule movement, and exocytosis were all reduced in antigen-stimulated mast cells when GEF-H1 was depleted by RNA interference. GEF-H1-depleted cells also showed a significant reduction in RhoA activation, resulting in reduced stress fiber formation without altering lamellipodia formation. Ectopic expression of a constitutively active RhoA mutant restored normal morphology in GEF-H1-depleted cells. FA formation during antigen stimulation required GEF-H1, suggesting it is a downstream target of the GEF-H1-RhoA signaling axis. GEF-H1 was activated by phosphorylation in conjunction with antigen stimulation. Syk kinase is linked to the FcεRI signaling pathway and the Syk inhibitor, GS-9973, blocked GEF-H1 activation and also suppressed cell spreading, granule movement, and exocytosis. We concluded that during FcεRI receptor stimulation, GEF-H1 transmits signals to RhoA activation and FA formation to facilitate the exocytosis mechanism.

Abstract 2406: Mechanism of mSin1 regulation of cell migration

Abstract Studies have shown that mSin1, a major component of mTORC2, plays an important role in tumor cell migration and invasion as well as cancer metastasis. However, how mSin1 regulates cell migration is poorly understood. In this study, we found that knockout of mSin1 suppressed cell spreading and migration in mouse embryo fibroblasts (MEFs). Similarly, knockdown of mSin1 also inhibited cell spreading and migration in rhabdomyosarcoma (Rh30) and cervical cancer (HeLa) cells. Furthermore, we observed that knockout or knockdown of mSin1 reduced the activities of the small GTPases (RhoA and Rac1) in the cells. Ectopic expression of constitutively active Rac1, but not RhoA, partially attenuated the reduced cell spreading and migration induced by mSin1 deficiency. In addition, depletion of mSin1 remarkedly inhibited the phosphorylation of focal adhesion proteins, including focal adhesion kinase (FAK) at Tyr397 and paxillin at Tyr118 in the cells. The results suggest that mSin1 controls cell spreading and migration at least partly by mediating the activity of Rac1 and the phosphorylation of FAK. (Supported by the Feist-Weiller Cancer Center, LSU Health Sciences Center, Shreveport, LA, USA) Citation Format: Shile Huang, Lei Liu, Yan Luo. Mechanism of mSin1 regulation of cell migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2406.

Opposite functions of RapA and RapC in cell adhesion and migration in Dictyostelium

ABSTRACT There are three Rap proteins in Dictyostelium. RapA is a key regulator of cell adhesion and cytoskeletal rearrangement. Recently, RapC has been reported to be involved in cytokinesis, cell migration, and multicellular development. Here, we compare the functions of RapA and RapC using cells expressing or lacking Rap proteins, and confirm that RapA and RapC have opposite functions in cell spreading, adhesion, and migration. On the other hand, RapC has a unique function in cytokinesis and multicellular development. Activated RapA appears to stimulate spreading and adhesion of the cells to the substrate, possibly resulting in a decrease in the migration speed of the cells during chemotaxis without affecting the directionality, whereas RapC suppresses cell spreading and adhesion, thereby increasing the migration speed. Cells lacking RapC were defective in cytokinesis and multicellular development and showed multinucleation and formation of multiple tips from a mound during development. At the C-terminus, RapC has an additional stretch of amino acids, which is not found in RapA. The mechanism through which RapA and RapC perform their opposite functions in diverse cellular processes should be characterized further to understand the Rap signaling pathways in detail.

AGAP1 regulates subcellular localization of FilGAP and control cancer cell invasion

The Arf (ADP-ribosylation factor) GAPs (GTPase-activating proteins) regulate membrane trafficking and actin cytoskeleton. The molecular mechanism of how Arf GAPs regulate actin cytoskeleton remains to be elucidated. We identified AGAP1, a subtype of Arf GAP, as a binding protein of FilGAP, a Rac-specific GAP, in mammalian cells. AGAP1 binds to C-terminus of FilGAP whereas FilGAP binds to N-terminus of AGAP1 containing GLD domain. FilGAP co-localized with AGAP1 at intracellular vesicles and targeting of FilGAP at the vesicles requires its interaction with AGAP1. Consistently, depletion of endogenous AGAP1 induced the accumulation of endogenous FilGAP into paxillin-positive focal adhesions and actin cytoskeletal structures. Knockdown of endogenous AGAP1 suppressed cell spreading on collagen and the suppression was released by depletion of endogenous FilGAP. Moreover, depletion of AGAP1 in MDA-MB-231 cells promoted cell invasion in extracellular matrices and depletion of FilGAP blocked the invasion. Taken together, the present study suggests that AGAP1 may regulate subcellular localization of FilGAP and control cell migration and invasion through interaction with FilGAP.

Effect of Chirality on Cell Spreading and Differentiation: From Chiral Molecules to Chiral Self-Assembly.

The influence of chirality on cell behavior is closely related with relevant biological events; however, many recent studies only focus on the apparent chiral influence of supramolecular nanofibers and ignore the respective effects of molecular chirality and supramolecular chirality in biological processes. Herein, the inherent molecular and supramolecular chiral effects on cell spreading and differentiation are studied. Left-handed nanofibers (referring to supramolecular chirality) assembled from l-amino acid derivatives can enhance cell spreading and proliferation compared to flat l-surfaces (referring to molecular chirality). However, compared to the d-surfaces (referring to molecular chirality), right-handed nanofibers (referring to supramolecular chirality) derived from d-amino acid suppress cell spreading and proliferation, overturning the conventional view that a fibrous morphology generally enhances cell adhesion. The results directly suggest that the amplification of chirality from chiral molecules to chiral assemblies significantly enhances the effect on regulated cell behavior by supramolecular helical handedness. Moreover, cell differentiation is found to be chirality dependent. It suggests that both the l-amino acid derivatives and the left-handed fibers facilitate osteogenic differentiation. This study provides useful insight into understanding the origin of chiral expression from the molecular to the macroscopic level in nature.

Site-specific phosphorylation regulates the functions of kindlin-3 in a variety of cells.

Studies of isolated cells, mice, and humans have demonstrated the vital role of the FERM domain protein kindlin-3 in integrin activation in certain hematopoietic and non-hematopoietic cells, consequent to binding to integrin β-subunits. To explore regulatory mechanisms, we developed a monoclonal antibody that selectively recognizes the phosphorylated form of Ser484 (pS484) in kindlin-3. Activation of platelets, HEL megakaryocytic-like cells and BT549 breast cancer cells led to enhanced expression of pS484 as assessed by immunofluorescence or Western blotting. In platelets, pS484 rose rapidly and transiently upon stimulation. When a mutant form of kindlin-3, T482S484/AA kindlin-3, was transduced into mouse megakaryocytes, it failed to support activation of integrin αIIbβ3, whereas wild-type kindlin-3 did. In MDA-MB231 breast cancer cells, expression of T482S484/AA kindlin-3 suppressed cell spreading, migration, invasion, and VEGF production. Wild-type kindlin-3 expressing cells markedly increased tumor growth in vivo, whereas T482S484/AA kindlin-3 significantly blunted tumor progression. Thus, our data establish that a unique phosphorylation event in kindlin-3 regulates its cellular functions.

Discovery of the Oncogenic Parp1, a Target of bcr-abl and a Potential Therapeutic, in mir-181a/PPFIA1 Signaling Pathway

miR-181a is downregulated in leukemia and affects its progression, drug resistance, and prognosis. However, the exact mechanism of its targets in leukemia, particularly in chronic myelogenous leukemia (CML), has not previously been established. Here, we use a multi-omics approach to demonstrate that protein tyrosine phosphatase, receptor type, f polypeptide, leukocyte common antigen (LAR) interacting protein (liprin), alpha 1 (PPFIA1) is a direct target for miR-181a in CML. Phospho-array assay shows that multiple phosphorylated proteins, particularly KIT signaling molecules, were downregulated in PPFIA1 inhibition. Additionally, PPFIA1 bound PARP1, a common molecule downstream of both PPFIA1 and BCR/ABL, to upregulate KIT protein through activation of nuclear factor kappa B (NF-κB)-P65 expression. Targeted inhibition of PPFIA1 and PARP1 downregulated c-KIT level, inhibited CML cell growth, and prolonged mouse survival. Overall, we report a critical regulatory miR-181a/PPFIA1/PARP1/NF-κB-P65/KIT axis in CML, and our preclinical study supports that targeted PPFIA1 and PARP1 may serve as a potential CML therapy.

Absence of AIF1L contributes to cell migration and a poor prognosis of breast cancer

BackgroundBreast cancer is the most common fatal cancer in women worldwide. Previous studies have demonstrated that allograft inflammatory factor 1 like (AIF1L) plays a key role in mammary tumorigenesis, although the mechanism involved remains unclear.PurposeThe purpose of this study was to assess the clinicopathological and prognostic significance of AIF1L expression levels and biological function in breast cancer.Patients and methodsWe used immunohistochemistry to detect the expression of AIF1L in breast cancer. We also analyzed the expression of AIF1L in breast cancer using the Cancer Genome Atlas (TCGA) cohort and the Cancer Cell Line Encyclopedia (CCLE). Furthermore, both in vitro assays were used to determine the effect of AIF1L on malignant behavior in breast cancer cells.ResultsWe detected AIF1L expression in tissue microarrays through immunohistochemistry and found that protein expression was significantly lower in BC tissues (28.6%, 82/287) compared to tumor-adjacent tissues (58.3%, 28/48) (P=0.007). Kaplan-Meier survival analysis revealed that disease-specific survival in BC patients with low AIF1L protein expression was significantly poorer compared to normal controls (P=0.040). In the TCGA cohort, the AIF1L gene was downregulated and hypermethylated in tumor samples compared to normal controls. Bioinformatics analysis using CCLE predicted potential biological functions of AIF1L related to tight junctions, cell junctions and focal adhesion. Ectopic expression of AIF1L suppressed MDA-MB-231 migration and invasion. Further evidence confirmed that AIF1L overexpression suppressed cell spreading, altered cell shape and decreased protrusion formation, which was correlated with decreased focal adhesion kinase (FAK) and RhoA expression.ConclusionThese findings suggest that AIF1L is a potential prognostic biomarker that plays a vital role in regulating the cytoskeleton in breast cancer.

Chondrocyte Shapes and Detachment on a Thermoresponsive Poly(2-methoxyethyl acrylate) Analog for the Development of New Chondrocytes Subculture Substrate

Chondrocyte dedifferentiation during subculture prevents cartilage tissue engineering. The dedifferentiation is generally caused by cell spreading and trypsin treatment. Thus, it is expected that chondrocytes maintain their specific functions when the cells are subcultured on a substrate that can suppress cell spreading and allow the cells to detach without trypsin treatment. Here, we showed that thermoresponsive poly(2-methoxyethyl acrylate) and analogous polymers can be used to suppress cell spreading and detachment without trypsin treatment.

Collagen Gels with Different Fibrillar Microarchitectures Elicit Different Cellular Responses.

The extracellular matrix consists of a complex mixture of fibrillar proteins, in which the architecture and mechanical properties of the protein fibrils vary considerably in various tissues. Here, we systematically polymerized collagen gels at different temperatures, providing substrates with tunable mechanics and defined local microarchitecture. We studied the dependence of spreading dynamics, proliferation, migration, and differentiation of human mesenchymal stem cells (hMSCs) on the fibrillar properties as compared to the bulk properties of the matrix. We found that high fiber stiffness, together with shorter fiber lengths, limited the transfer of cellular traction forces to nearby fibers. As a result, cells were not able to build up sufficient tension, which suppressed cell spreading, proliferation, and migration. Cells on such fibers also showed limited focal adhesion formation and different lineage selection preferences. In contrast, cell spreading, proliferation, and migration was always associated with fiber recruitment, long-range deformations in the collagen gel networks and an increase in collagen density around cells. Typically, cells on such substrates had a preference for osteogenic differentiation and showed higher levels of focal adhesions formation. These results contribute to a further understanding of the mechanotransduction process and to the design criteria for future biomimetic materials for tissue-engineering applications.

Phosphorylation of Serine 402 Regulates RacGAP Protein Activity of FilGAP Protein

FilGAP is a Rho GTPase-activating protein (GAP) that specifically regulates Rac. FilGAP is phosphorylated by ROCK, and this phosphorylation stimulates its RacGAP activity. However, it is unclear how phosphorylation regulates cellular functions and localization of FilGAP. We found that non-phosphorylatable FilGAP (ST/A) mutant is predominantly localized to the cytoskeleton along actin filaments and partially co-localized with vinculin around cell periphery, whereas phosphomimetic FilGAP (ST/D) mutant is diffusely cytoplasmic. Moreover, phosphorylated FilGAP detected by Phos-tag is also mainly localized in the cytoplasm. Of the six potential phosphorylation sites in FilGAP tested, only mutation of serine 402 to alanine (S402A) resulted in decreased cell spreading on fibronectin. FilGAP phosphorylated at Ser-402 is localized to the cytoplasm but not at the cytoskeleton. Although Ser-402 is highly phosphorylated in serum-starved quiescent cells, dephosphorylation of Ser-402 is accompanied with the cell spreading on fibronectin. Treatment of the cells expressing wild-type FilGAP with calyculin A, a Ser/Thr phosphatase inhibitor, suppressed cell spreading on fibronectin, whereas cells transfected with FilGAP S402A mutant were not affected by calyculin A. Expression of constitutively activate Arf6 Q67L mutant stimulated membrane blebbing activity of both non-phosphorylatable (ST/A) and phosphomimetic (ST/D) FilGAP mutants. Conversely, depletion of endogenous Arf6 suppressed membrane blebbing induced by FilGAP (ST/A) and (ST/D) mutants. Our study suggests that Arf6 and phosphorylation of FilGAP may regulate FilGAP, and phosphorylation of Ser-402 may play a role in the regulation of cell spreading on fibronectin.

Induction of intermembrane adhesion by incorporation of synthetic adhesive molecules into cell membranes.

Modulation of cell adhesion by synthetic materials is useful for a wide range of biomedical applications. Here, we characterized cell adhesion mediated by a semisynthetic molecule, cholesteryl-modified gelatin (chol-gelatin). We found that this hybrid molecule facilitated cell adhesion by connecting two apposed membranes via multiple cholesterol moieties on the gelatin molecules, whereas unmodified gelatin did not bind to cell membranes. Analyses revealed that the rate of the formation of cell adhesions was increased by displaying more cholesterol moieties on the cell membrane. In contrast, the area of the cell adhesion site was unchanged by increasing the number of cholesterol molecules, suggesting that chol-gelatin may suppress cell spreading. Such restriction was not observed in cell adhesion mediated by the mutant of physiological adhesion protein CD2, which lacked its cytoplasmic domain and was unable to connect to cytoplasmic actin filaments, but had a similar affinity for its ligand compared with the chol-gelatin-cell membrane interaction. Further analysis suggested the restriction of cell spreading by chol-gelatin was largely independent of the modulation of the surface force, and thus we hypothesize that the restriction could be in part due to the modulation of cell membrane mechanics by membrane-incorporated chol-gelatin. Our study dissected the two roles of the hybrid molecule in cell adhesion, namely the formation of a molecular connection and the restriction of spreading, and may be useful for designing other novel synthetic agents to modulate various types of cell adhesions.

Trans-homophilic interaction of CADM1 activates PI3K by forming a complex with MAGuK-family proteins MPP3 and Dlg.

CADM1 (Cell adhesion molecule 1), a cell adhesion molecule belonging to the immunoglobulin superfamily, is involved in cell-cell interaction and the formation and maintenance of epithelial structure. Expression of CADM1 is frequently downregulated in various tumors derived from epithelial cells. However, the intracellular signaling pathways activated by CADM1-mediated cell adhesion remain unknown. Here, we established a cell-based spreading assay to analyze the signaling pathway specifically activated by the trans-homophilic interaction of CADM1. In the assay, MDCK cells expressing exogenous CADM1 were incubated on the glass coated with a recombinant extracellular fragment of CADM1, and the degree of cell spreading was quantified by measuring their surface area. Assay screening of 104 chemical inhibitors with known functions revealed that LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), efficiently suppressed cell spreading in a dose-dependent manner. Inhibitors of Akt and Rac1, downstream effectors of PI3K, also partially suppressed cell spreading, while the addition of both inhibitors blocked cell spreading to the same extent as did LY294002. Furthermore, MPP3 and Dlg, membrane-associated guanylate kinase homologs (MAGuK) proteins, connect CADM1 with p85 of PI3K by forming a multi-protein complex at the periphery of cells. These results suggest that trans-homophilic interaction mediated by CADM1 activates the PI3K pathway to reorganize the actin cytoskeleton and form epithelial cell structure.

Trans-homophilic interaction of CADM1 activates PI3K by forming a complex with MAGuK-family proteins MPP3 and Dlg.

CADM1 (Cell adhesion molecule 1), a cell adhesion molecule belonging to the immunoglobulin superfamily, is involved in cell-cell interaction and the formation and maintenance of epithelial structure. Expression of CADM1 is frequently down-regulated in various tumors derived from epithelial cells. However, the intracellular signaling pathways activated by CADM1-mediated cell adhesion remain unknown. Here, we established a cell-based spreading assay to analyze the signaling pathway specifically activated by the trans-homophilic interaction of CADM1. In the assay, MDCK cells expressing exogenous CADM1 were incubated on the glass coated with a recombinant extracellular fragment of CADM1, and the degree of cell spreading was quantified by measuring their surface area. Assay screening of 104 chemical inhibitors with known functions revealed that LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), efficiently suppressed cell spreading in a dose-dependent manner. Inhibitors of Akt and Rac1, downstream effectors of PI3K, also partially suppressed cell spreading, while the addition of both inhibitors blocked cell spreading to the same extent as did LY294002. Furthermore, MPP3 and Dlg, membrane-associated guanylate kinase homologs (MAGuK) proteins, connect CADM1 with p85 of PI3K by forming a multi-protein complex at the periphery of cells. These results suggest that trans-homophilic interaction mediated by CADM1 activates the PI3K pathway to reorganize the actin cytoskeleton and form epithelial cell structure.

MARVELD1 regulates integrin β1-mediated cell adhesion and actin organization via inhibiting its pre-mRNA processing

Cell adhesion on an extracellular matrix (ECM) participates in cell motility, invasion, cell signal transduction and gene expression. Many nuclear proteins regulate cell-ECM adhesion through managing the transcription of cell adhesion-related genes. Here, we identified MARVEL [MAL (The myelin and lymphocyte protein) and related proteins for vesicle trafficking and membrane link] domain containing 1 (MARVELD1) that could suppress cell spreading and complicate actin organization. Over-expression of MARVELD1 in NIH3T3 cells decreased the expression level of integrin β1 and vinculin, and further led to dephosphorylation of focal adhesion kinase (FAK) at Tyr 397. We also found that MARVELD1 partially colocalized with serine/arginine-rich splicing factor 2 (SC35) and interacted with nuclear cap binding protein subunit 2 (CBP20). Finally, we demonstrated that pre-mRNA processing of integrin β1 was affected by MARVELD1. Taken together, our studies demonstrate that MARVELD1 plays a role in pre-mRNA processing of integrin β1, and thereby regulates cell adhesion and cell motility. These studies provide a novel regulatory mechanism of cell-ECM adhesion by nuclear protein in cells.

The potassium–chloride cotransporter 2 promotes cervical cancer cell migration and invasion by an ion transport‐independent mechanism

K(+)-Cl(-) cotransporters (KCCs) play a fundamental role in epithelial cell function, both in the context of ionic homeostasis and also in cell morphology, cell division and locomotion. Unlike other ubiquitously expressed KCC isoforms, expression of KCC2 is widely considered to be restricted to neurons, where it is responsible for maintaining a low intracellular chloride concentration to drive hyperpolarising postsynaptic responses to the inhibitory neurotransmitters GABA and glycine. Here we report a novel finding that KCC2 is widely expressed in several human cancer cell lines including the cervical cancer cell line (SiHa). Membrane biotinylation assays and immunostaining showed that endogenous KCC2 is located on the cell membrane of SiHa cells. To elucidate the role of KCC2 in cervical tumuorigenesis, SiHa cells with stable overexpression or knockdown of KCC2 were employed. Overexpression of KCC2 had no significant effect on cell proliferation but dramatically suppressed cell spreading and stress fibre organization, while knockdown of KCC2 showed opposite effects. In addition, insulin-like growth factor 1 (IGF-1)-induced cell migration and invasiveness were significantly increased by overexpression of KCC2. KCC2-induced cell migration and invasion were not dependent on KCC2 transport function since overexpression of an activity-deficient mutant KCC2 still increased IGF-1-induced cell migration and invasion. Moreover, overexpression of KCC2 significantly diminished the number of focal adhesions, while knockdown of KCC2 increased their number. Taken together, our data establish that KCC2 expression and function are not restricted to neurons and that KCC2 serves to increase cervical tumourigenesis via an ion transport-independent mechanism.

Highlights of This Issue

Pericytes are critical in remodeling and stabilizing developing tumor vessels. PDGF-B induces pericyte migration and differentiation and is upregulated in several tumor types. Hamdan and colleagues show that increased PDGF-B in the tumor microenvironment is mediated by the production of SDF-1α. SDF-1α upregulated PDGF-B mRNA and protein in vitro and in vivo, whereas a specific shRNA downregulated PDGF-B. Luciferase and ChIP assays showed that PDGF-B induction by SDF-1α was transcriptionally mediated, involving binding of ELK-1 to the pdgf-b promoter. This SDF-1α/PDGF-B pathway induced bone marrow cells to differentiate into pericytes and may therefore become a new therapeutic target to inhibit vasculogenesis.Class 3 semaphorins have been shown to have tumor suppressive activities. In the current study, Nguyen and colleagues explored the role and regulation of SEMA3B and SEMA3F in endometrial cancer. Data showed a progressive decrease in SEMA3B and SEMA3F expression in human endometrial cancers. Treatment of endometrial cancer cell lines with progesterone or vitamin D restored the expression of SEMA3B and SEMA3F in cancer cells and inhibited growth and angiogenesis, suggesting that malignant behavior of cells can be reverted to their normal state by restoration of SEMA3 expression.MicroRNAs regulate gene expression by repression or degradation of mRNA of multiple target genes and, therefore, play an important role in angiogenesis, cell migration and invasion, especially in cancer. Changes in cell morphology and mobility are tightly regulated by the heterodimeric adhesion receptors, the integrins, whose bidirectional signaling function is crucial for both physiological and pathological conditions. Here, Augoff and coworkers show that miR-31, a key regulator of the cancer invasion-metastasis cascade, targets several α and β integrin subunits to suppress cell spreading in a ligand-specific manner in cancer cells.Melanoma secretes high levels of proinflammatory cytokines, including IL-1. To date, the expression of IL-1α and IL-1β in human melanoma and their functions and role(s) associated with tumor progression have yet to be elucidated. Here, Qin and colleagues examined IL-1α and IL-1β expression profiles in large-scale melanoma tissue samples and identified several important downstream molecules and kinase responders (SPAK/JNK) for endogenous IL-1 in human melanoma cells. This study suggests that IL-1α and IL-1β increase significantly from nevus to primary melanoma and interrupting IL-1 signaling can affect autophagy and inhibit growth of IL-1-positive melanoma cells.