Distinct roles for paxillin and Hic-5 in regulating breast cancer cell morphology, invasion, and metastasis

A comparative analysis of paxillin and Hic-5 proximity interactomes

Focal adhesions serve as structural and signaling hubs, facilitating bidirectional communication at the cell-extracellular matrix interface. Paxillin and the related Hic-5 (TGFβ1i1) are adaptor/scaffold proteins that recruit numerous structural and regulatory proteins to focal adhesions, where they perform both overlapping and discrete functions. In this study, paxillin and Hic-5 were expressed in U2OS osteosarcoma cells as biotin ligase (BioID2) fusion proteins and used as bait proteins for proximity-dependent biotinylation in order to directly compare their respective interactomes. The fusion proteins localized to both focal adhesions and the centrosome, resulting in biotinylation of components of each of these structures. Biotinylated proteins were purified and analyzed by mass spectrometry. The list of proximity interactors for paxillin and Hic-5 comprised numerous shared core focal adhesion proteins that likely contribute to their similar functions in cell adhesion and migration, as well as proteins unique to paxillin and Hic-5 that have been previously localized to focal adhesions, the centrosome, or the nucleus. Western blotting confirmed biotinylation and enrichment of FAK and vinculin, known interactors of Hic-5 and paxillin, as well as several potentially unique proximity interactors of Hic-5 and paxillin, including septin 7 and ponsin, respectively. Further investigation into the functional relationship between the unique interactors and Hic-5 or paxillin may yield novel insights into their distinct roles in cell migration.

Unveiling the Multifaceted Capabilities of Endophytic Aspergillus flavus Isolated from Annona squamosa Fruit Peels against Staphylococcus Isolates and HCoV 229E-In Vitro and In Silico Investigations

Recently, there has been a surge towards searching for primitive treatment strategies to discover novel therapeutic approaches against multi-drug-resistant pathogens. Endophytes are considered unexplored yet perpetual sources of several secondary metabolites with therapeutic significance. This study aims to isolate and identify the endophytic fungi from Annona squamosa L. fruit peels using morphological, microscopical, and transcribed spacer (ITS-rDNA) sequence analysis; extract the fungus's secondary metabolites by ethyl acetate; investigate the chemical profile using UPLC/MS; and evaluate the potential antibacterial, antibiofilm, and antiviral activities. An endophytic fungus was isolated and identified as Aspergillus flavus L. from the fruit peels. The UPLC/MS revealed seven compounds with various chemical classes. The antimicrobial activity of the fungal ethyl acetate extract (FEA) was investigated against different Gram-positive and Gram-negative standard strains, in addition to resistant clinical isolates using the agar diffusion method. The CPE-inhibition assay was used to identify the potential antiviral activity of the crude fungal extract against low pathogenic human coronavirus (HCoV 229E). Selective Gram-positive antibacterial and antibiofilm activities were evident, demonstrating pronounced efficacy against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). However, the extract exhibited very weak activity against Gram-negative bacterial strains. The ethyl acetate extract of Aspergillus flavus L exhibited an interesting antiviral activity with a half maximal inhibitory concentration (IC50) value of 27.2 µg/mL against HCoV 229E. Furthermore, in silico virtual molecular docking-coupled dynamics simulation highlighted the promising affinity of the identified metabolite, orienting towards three MRSA biotargets and HCoV 229E main protease as compared to reported reference inhibitors/substrates. Finally, ADME analysis was conducted to evaluate the potential oral bioavailability of the identified metabolites.

Paxillin phase separation promotes focal adhesion assembly and integrin signaling

Focal adhesions (FAs) are transmembrane protein assemblies mediating cell-matrix connection. Although protein liquid-liquid phase separation (LLPS) has been tied to the organization and dynamics of FAs, the underlying mechanisms remain unclear. Here, we experimentally tune the LLPS of PXN/Paxillin, an essential scaffold protein of FAs, by utilizing a light-inducible Cry2 system in different cell types. In addition to nucleating FA components, light-triggered PXN LLPS potently activates integrin signaling and subsequently accelerates cell spreading. In contrast to the homotypic interaction-driven LLPS of PXN in vitro, PXN condensates in cells are associated with the plasma membrane and modulated by actomyosin contraction and client proteins of FAs. Interestingly, non-specific weak intermolecular interactions synergize with specific molecular interactions to mediate the multicomponent condensation of PXN and are efficient in promoting FA assembly and integrin signaling. Thus, our data establish an active role of the PXN phase transition into a condensed membrane-associated compartment in promoting the assembly/maturation of FAs.

NOX4 alleviates breast cancer cell aggressiveness by co-ordinating mitochondrial turnover through PGC1α/Drp1 axis

Triple Negative Breast Cancer (TNBC) is a highly aggressive form of breast cancer, with few treatment options. This study investigates the complex molecular mechanism by which NADPH oxidase 4 (NOX4), a major ROS producer in mitochondria, affects the aggressiveness of luminal and triple-negative breast cancer cells (TNBCs). We found that NOX4 expression was differentially regulated in luminal and TNBC cells, with a positive correlation to their epithelial characteristics. Time dependent analysis revealed that TNBCs exhibits higher steady-state ROS levels than luminal cells, but NOX4 silencing increased ROS levels in luminal breast cancer cells and enhanced their ability to migrate and invade. In contrast, NOX4 over expression in TNBCs had the opposite effect. The mouse tail-vein experiment showed that the group injected with NOX4 silenced luminal cells had a higher number of lung metastases compared to the control group. Mechanistically, NOX4 enhanced PGC1α dependent mitochondrial biogenesis and attenuated Drp1-mediated mitochondrial fission in luminal breast cancer cells, leading to an increased mitochondrial mass and elongated mitochondrial morphology. Interestingly, NOX4 silencing increased mitochondrial ROS (mtROS) levels without affecting mitochondrial (Δψm) and cellular integrity. Inhibition of Drp1-dependent fission with Mdivi1 reversed the effect of NOX4-dependent mitochondrial biogenesis, dynamics, and migration of breast cancer cells. Our findings suggest that NOX4 expression diminishes from luminal to a triple negative state, accompanied by elevated ROS levels, which may modulate mitochondrial turnover to attain an aggressive phenotype. The study provides potential insights for targeted therapies for TNBCs.

TGFB1I1 promotes cell proliferation and migration in urothelial carcinoma

Urothelial carcinoma (UC) is common cancer worldwide with a high prevalence in Taiwan, especially in the upper urinary tract, including the renal pelvis and ureter, also classifying as upper urinary tract urothelial carcinoma. Here, we aim to find a representative prognostic marker that strongly correlates to this type of carcinoma. Transforming growth factor beta-1-induced transcript 1 (TGFB1I1) is a cofactor of cellular TGF-β1 and interacts with various nuclear receptors. The previous study showed that TGFB1I1 promotes focal adhesion formation, contributing to the epithelial-mesenchymal transition (EMT) with actin cytoskeleton and vimentin through TGFB1I1 regulation. We aim to reveal the role of TGFB1I1 in the tumorigenesis of UC. In silico and clinicopathological data of upper urinary tract urothelial carcinoma (UTUC) and urinary bladder urothelial carcinoma (UBUC) were accessed and analyzed for IHC staining regarding tumor characteristics, including survival outcome. Finally, an in vitro study was performed to demonstrate the biological changes of UC cells. In UTUC, overexpression of TGFB1I1 was significantly correlated with advanced tumor stage, papillary configuration, and frequent mitosis. Meanwhile, overexpression of TGFB1I1 was significantly correlated with advanced tumor stage and histological grade in UBUC. Moreover, the in vitro study shows that TGFB1I1 affects cell proliferation, viability, migration and wound healing. The EMT markers also decreased upon TGFB1I1 knockdown. In this study, we identified that TGFB1I1 regulates UC cell proliferation and viability and induces the EMT to facilitate cell migration in vitro, leading to its essential role in promoting tumor aggressiveness in both UTUC and UBUC.

Paxillin/HDAC6 regulates microtubule acetylation to promote directional migration of keratinocytes driven by electric fields

Endogenous electric fields (EFs) have been demonstrated to facilitate wound healing by directing the migration of epidermal cells. Despite the identification of numerous molecules and signaling pathways that are crucial for the directional migration of keratinocytes under EFs, the underlying molecular mechanisms remain undefined. Previous studies have indicated that microtubule (MT) acetylation is linked to cell migration, while Paxillin exerts a significant influence on cell motility. Therefore, we postulated that Paxillin could enhance EF-induced directional migration of keratinocytes by modulating MT acetylation. In the present study, we observed that EFs (200 mV/mm) induced migration of human immortalized epidermal cells (HaCaT) towards the anode, while upregulating Paxillin, downregulating HDAC6, and increasing the level of microtubule acetylation. Our findings suggested that Paxillin plays a pivotal role in inhibiting HDAC6-mediated microtubule acetylation during directional migration under EF regulation. Conversely, downregulation of Paxillin decreased microtubule acetylation and electrotaxis of epidermal cells by promoting HDAC6 expression, and this effect could be reversed by the addition of tubacin, an HDAC6-specific inhibitor. Furthermore, we observed that EFs also mediated the polarization of Paxillin and acetylated α-tubulin, which is critical for directional migration. In conclusion, our study revealed that MT acetylation in EF-guided keratinocyte migration is regulated by the Paxillin/HDAC6 signaling pathway, providing a novel theoretical foundation for the molecular mechanism of EF-guided directional migration of keratinocytes.

Paxillin knockout in mouse granulosa cells increases fecundity†

Paxillin is an intracellular adaptor protein involved in focal adhesions, cell response to stress, steroid signaling, and apoptosis in reproductive tissues. To investigate the role of paxillin in granulosa cells, we created a granulosa-specific paxillin knockout mouse model using Cre recombinase driven by the Anti-Müllerian hormone receptor 2 gene promoter. Female granulosa-specific paxillin knockout mice demonstrated increased fertility in later reproductive age, resulting in higher number of offspring when bred continuously up to 26 weeks of age. This was not due to increased numbers of estrous cycles, ovulated oocytes per cycle, or pups per litter, but this was due to shorter time to pregnancy and increased number of litters in the granulosa-specific paxillin knockout mice. The number of ovarian follicles was not significantly affected by the knockout at 30 weeks of age. Granulosa-specific paxillin knockout mice had slightly altered estrous cycles but no difference in circulating reproductive hormone levels. Knockout of paxillin using clustered regularly interspaced short palindromic repeat-associated protein 9 (CRISPR-Cas9) in human granulosa-derived immortalized KGN cells did not affect cell proliferation or migration. However, in cultured primary mouse granulosa cells, paxillin knockout reduced cell death under basal culture conditions. We conclude that paxillin knockout in granulosa cells increases female fecundity in older reproductive age mice, possibly by reducing granulosa cell death. This study implicates paxillin and its signaling network as potential granulosa cell targets in the management of age-related subfertility.

Fyn-Mediated Paxillin Tyrosine 31 Phosphorylation Regulates Migration and Invasion of Breast Cancer Cells

Metastasis is the leading cause of death in breast cancer patients due to the lack of effective therapies. Elevated levels of paxillin expression have been observed in various cancer types, with tyrosine phosphorylation shown to play a critical role in driving cancer cell migration. However, the specific impact of the distinct tyrosine phosphorylation events of paxillin in the progression of breast cancer remains to be fully elucidated. Here, we found that paxillin overexpression in breast cancer tissue is associated with a patient's poor prognosis. Paxillin knockdown inhibited the migration and invasion of breast cancer cells. Furthermore, the phosphorylation of paxillin tyrosine residue 31 (Tyr31) was significantly increased upon the TGF-β1-induced migration and invasion of breast cancer cells. Inhibiting Fyn activity or silencing Fyn decreases paxillin Tyr31 phosphorylation. The wild-type and constitutively active Fyn directly phosphorylate paxillin Tyr31 in an in vitro system, indicating that Fyn directly phosphorylates paxillin Tyr31. Additionally, the non-phosphorylatable mutant of paxillin at Tyr31 reduces actin stress fiber formation, migration, and invasion of breast cancer cells. Taken together, our results provide direct evidence that Fyn-mediated paxillin Tyr31 phosphorylation is required for breast cancer migration and invasion, suggesting that targeting paxillin Tyr31 phosphorylation could be a potential therapeutic strategy for mitigating breast cancer metastasis.

Paxillin regulates Rab5-mediated vesicle motility through modulating microtubule acetylation

Rab GTPase-mediated vesicle trafficking of cell surface proteins, including integrins, through endocytic and recycling pathways is important in controlling cell-extracellular matrix interactions during cell migration. The focal adhesion adaptor protein, paxillin, plays a central role in regulating adhesion dynamics and was previously shown to promote anterograde vesicle trafficking through modulation of microtubule acetylation via its inhibition of the deacetylase HDAC6. The role of paxillin in retrograde trafficking is unknown. Herein, we identified a role for paxillin in the modulation of the Rab5 GTPase, which is necessary for regulating early endosome dynamics and focal adhesion turnover. Using MDA-MB-231 breast cancer cells and paxillin (-/-) fibroblasts, paxillin was shown to impact Rab5-associated vesicle size and distribution, as well as Rab5 GTPase activity, through its modulation of HDAC6. Using a combination of real-time imaging and particle tracking analysis, paxillin was shown to promote Rab5-associated vesicle motility through inhibition of HDAC6-mediated micro-tubule deacetylation, along with the localization of active integrin to focal adhesions.

Arctigenin hinders the invasion and metastasis of cervical cancer cells via the FAK/paxillin pathway

Context

Cervical cancer is the most common gynecological pernicious tumor with high morbidity and mortality worldwide, especially in developing countries. Arctigenin (ARG), a nature-derived component, has exhibited anti-tumor activity in various tumors.

Objective

To explore the effect of ARG on cervical cancer.

Materials and methods

The effect and mechanism of ARG on cervical cancer cells were explored by cell counting kit-8 (CCK-8), flow cytometry, transwell and Western blot assays. Additionally, in vivo experiment was conducted in xenografted mice by immunohistochemistry (IHC), terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) and Western blot assays.

Results

ARG treatment induced both concentration-dependent and time-dependent reductions in the cell viability of SiHa and HeLa cells with a IC50 value of 9.34 μM and 14.45 μM, respectively. ARG increased the apoptosis rate and the protein levels of cleaved-caspase 3 and E-cadherin, but decreased the invaded cell numbers and the protein levels of Vimentin and N-cadherin in vitro. Mechanically, ARG inhibited the expression of focal adhesion kinase (FAK)/paxillin pathway, which was confirmed by the overexpression of FAK in SiHa cells. The inhibitory role of overexpression of FAK in proliferation and invasion, as well as its promoted role in apoptosis were reversed with ARG treatment. Meanwhile, ARG suppressed growth and metastasis, and enhanced apoptosis in vivo. Consistently, ARG administration reduced the relative protein level of p-FAK/FAK and p-paxillin/paxillin in tumor tissues of xenografted mice.

Conclusion

ARG inhibited proliferation, invasion and metastasis, but enhanced apoptosis of cervical cancer via the FAK/paxillin axis.

Rapid cancer cell perineural invasion utilizes amoeboid migration

The invasion of nerves by cancer cells, or perineural invasion (PNI), is potentiated by the nerve microenvironment and is associated with adverse clinical outcomes. However, the cancer cell characteristics that enable PNI are poorly defined. Here, we generated cell lines enriched for a rapid neuroinvasive phenotype by serially passaging pancreatic cancer cells in a murine sciatic nerve model of PNI. Cancer cells isolated from the leading edge of nerve invasion showed a progressively increasing nerve invasion velocity with higher passage number. Transcriptome analysis revealed an upregulation of proteins involving the plasma membrane, cell leading edge, and cell movement in the leading neuroinvasive cells. Leading cells progressively became round and blebbed, lost focal adhesions and filipodia, and transitioned from a mesenchymal to amoeboid phenotype. Leading cells acquired an increased ability to migrate through microchannel constrictions and associated more with dorsal root ganglia than nonleading cells. ROCK inhibition reverted leading cells from an amoeboid to mesenchymal phenotype, reduced migration through microchannel constrictions, reduced neurite association, and reduced PNI in a murine sciatic nerve model. Cancer cells with rapid PNI exhibit an amoeboid phenotype, highlighting the plasticity of cancer migration mode in enabling rapid nerve invasion.

Lack of Paxillin phosphorylation promotes single-cell migration in vivo

Focal adhesions are structures that physically link the cell to the extracellular matrix for cell migration. Although cell culture studies have provided a wealth of information regarding focal adhesion biology, it is critical to understand how focal adhesions are dynamically regulated in their native environment. We developed a zebrafish system to visualize focal adhesion structures during single-cell migration in vivo. We find that a key site of phosphoregulation (Y118) on Paxillin exhibits reduced phosphorylation in migrating cells in vivo compared to in vitro. Furthermore, expression of a non-phosphorylatable version of Y118-Paxillin increases focal adhesion disassembly and promotes cell migration in vivo, despite inhibiting cell migration in vitro. Using a mouse model, we further find that the upstream kinase, focal adhesion kinase, is downregulated in cells in vivo, and cells expressing non-phosphorylatable Y118-Paxillin exhibit increased activation of the CRKII-DOCK180/RacGEF pathway. Our findings provide significant new insight into the intrinsic regulation of focal adhesions in cells migrating in their native environment.

The explorations of dynamic interactions of paxillin at the focal adhesions

Paxillin is one of the most important adapters in integrin-mediated adhesions that performs numerous crucial functions relying on its dynamic interactions. Its structural behavior serves different purposes, providing a base for several activities. The various domains of paxillin display different functions in the whole process of cell movements and have a significant role in cell adhesion, migration, signal transmission, and protein-protein interactions. On the other hand, some paxillin-associated proteins provide a unique spatiotemporal mechanism for regulating its dynamic characteristics in the tissue homeostasis and make it a more complex and decisive protein at the focal adhesions. This review briefly describes the structural adaptations and molecular mechanisms of recruitment of paxillin into adhesions, explains paxillin's binding dynamics and impact on adhesion stability and turnover, and reveals a variety of paxillin-associated regulatory mechanisms and how paxillin is embedded into the signaling networks.

ADT-OH inhibits malignant melanoma metastasis in mice via suppressing CSE/CBS and FAK/Paxillin signaling pathway

Hydrogen sulfide (H2S) is widely recognized as the third endogenous gas signaling molecule and may play a key role in cancer biological processes. ADT-OH (5-(4-hydroxyphenyl)-3H-1,2-dithiocyclopentene-3-thione) is one of the most widely used organic donors for the slow release of H2S and considered to be a potential anticancer compound. In this study, we investigated the antimetastatic effects of ADT-OH in highly metastatic melanoma cells. A tail-vein-metastasis model was established by injecting B16F10 and A375 cells into the tail veins of mice, whereas a mouse footpad-injection model was established by injecting B16F10 cells into mouse footpads. We showed that administration of ADT-OH significantly inhibited the migration and invasion of melanoma cells in the three different animal models. We further showed that ADT-OH dose-dependently inhibited the migration and invasion of B16F10, B16F1 and A375 melanoma cells as evaluated by wound healing and Transwell assays in vitro. LC-MS/MS and bioinformatics analyses revealed that ADT-OH treatment inhibited the EMT process in B16F10 and A375 cells by reducing the expression of FAK and the downstream response protein Paxillin. Overexpression of FAK reversed the inhibitory effects of ADT-OH on melanoma cell migration. Moreover, after ADT-OH treatment, melanoma cells showed abnormal expression of the H2S-producing enzymes CSE/CBS and the AKT signaling pathways. In addition, ADT-OH significantly suppressed the proliferation of melanoma cells. Collectively, these results demonstrate that ADT-OH inhibits the EMT process in melanoma cells by suppressing the CSE/CBS and FAK signaling pathways, thereby exerting its antimetastatic activity. ADT-OH may be used as an antimetastatic agent in the future.

Paxillin: A Hub for Mechano-Transduction from the β3 Integrin-Talin-Kindlin Axis

Focal adhesions are specialized integrin-dependent adhesion complexes, which ensure cell anchoring to the extracellular matrix. Focal adhesions also function as mechano-signaling platforms by perceiving and integrating diverse physical and (bio)chemical cues of their microenvironment, and by transducing them into intracellular signaling for the control of cell behavior. The fundamental biological mechanism of creating intracellular signaling in response to changes in tensional forces appears to be tightly linked to paxillin recruitment and binding to focal adhesions. Interestingly, the tension-dependent nature of the paxillin binding to adhesions, combined with its scaffolding function, suggests a major role of this protein in integrating multiple signals from the microenvironment, and accordingly activating diverse molecular responses. This minireview offers an overview of the molecular bases of the mechano-sensitivity and mechano-signaling capacity of core focal adhesion proteins, and highlights the role of paxillin as a key component of the mechano-transducing machinery based on the interaction of cells to substrates activating the β3 integrin-talin1-kindlin.

Paxillin Promotes Breast Tumor Collective Cell Invasion through Maintenance of Adherens Junction Integrity

Distant organ metastasis is linked to poor prognosis during cancer progression. The expression level of the focal adhesion adapter protein paxillin varies among different human cancers, but its role in tumor progression is unclear. Herein, we utilize a newly generated PyMT mammary tumor mouse model with conditional paxillin ablation in breast tumor epithelial cells, combined with in vitro 3D tumor organoids invasion analysis and 2D calcium switch assays, to assess the roles for paxillin in breast tumor cell invasion. Paxillin had little effect on primary tumor initiation and growth but is critical for the formation of distant lung metastasis. In paxillin-depleted 3D tumor organoids, collective cell invasion was substantially perturbed. Two-dimensional cell culture revealed paxillin-dependent stabilization of adherens junctions (AJ). Mechanistically, paxillin is required for AJ assembly through facilitating E-cadherin endocytosis and recycling and HDAC6-mediated microtubule acetylation. Furthermore, Rho GTPase activity analysis and rescue experiments with a RhoA activator or Rac1 inhibitor suggest paxillin is potentially regulating the E-cadherin-dependent junction integrity and contractility through control of the balance of RhoA and Rac1 activities. Together, these data highlight new roles for paxillin in the regulation of cell-cell adhesion and collective tumor cell migration to promote the formation of distance organ metastases. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].

Brain and Breast Cancer Cells with PTEN Loss of Function Reveal Enhanced Durotaxis and RHOB Dependent Amoeboid Migration Utilizing 3D Scaffolds and Aligned Microfiber Tracts

BACKGROUND

Glioblastoma multiforme (GBM) and metastatic triple-negative breast cancer (TNBC) with PTEN mutations often lead to brain dissemination with poor patient outcome, thus new therapeutic targets are needed. To understand signaling, controlling the dynamics and mechanics of brain tumor cell migration, we implemented GBM and TNBC cell lines and designed 3D aligned microfibers and scaffolds mimicking brain structures.

METHODS

3D microfibers and scaffolds were printed using melt electrowriting. GBM and TNBC cell lines with opposing PTEN genotypes were analyzed with RHO-ROCK-PTEN inhibitors and PTEN rescue using live-cell imaging. RNA-sequencing and qPCR of tumor cells in 3D with microfibers were performed, while scanning electron microscopy and confocal microscopy addressed cell morphology.

RESULTS

In contrast to the PTEN wildtype, GBM and TNBC cells with PTEN loss of function yielded enhanced durotaxis, topotaxis, adhesion, amoeboid migration on 3D microfibers and significant high RHOB expression. Functional studies concerning RHOB-ROCK-PTEN signaling confirmed the essential role for the above cellular processes.

CONCLUSIONS

This study demonstrates a significant role of the PTEN genotype and RHOB expression for durotaxis, adhesion and migration dependent on 3D. GBM and TNBC cells with PTEN loss of function have an affinity for stiff brain structures promoting metastasis. 3D microfibers represent an important tool to model brain metastasizing tumor cells, where RHO-inhibitors could play an essential role for improved therapy.

Homeostatic membrane tension constrains cancer cell dissemination by counteracting BAR protein assembly

Malignancy is associated with changes in cell mechanics that contribute to extensive cell deformation required for metastatic dissemination. We hypothesized that the cell-intrinsic physical factors that maintain epithelial cell mechanics could function as tumor suppressors. Here we show, using optical tweezers, genetic interference, mechanical perturbations, and in vivo studies, that epithelial cells maintain higher plasma membrane (PM) tension than their metastatic counterparts and that high PM tension potently inhibits cancer cell migration and invasion by counteracting membrane curvature sensing/generating BAR family proteins. This tensional homeostasis is achieved by membrane-to-cortex attachment (MCA) regulated by ERM proteins, whose disruption spontaneously transforms epithelial cells into a mesenchymal migratory phenotype powered by BAR proteins. Consistently, the forced expression of epithelial–mesenchymal transition (EMT)-inducing transcription factors results in decreased PM tension. In metastatic cells, increasing PM tension by manipulating MCA is sufficient to suppress both mesenchymal and amoeboid 3D migration, tumor invasion, and metastasis by compromising membrane-mediated mechanosignaling by BAR proteins, thereby uncovering a previously undescribed mechanical tumor suppressor mechanism.

Changes in cell mechanics contribute to cancer cell dissemination. Here the authors show that high plasma membrane (PM) tension inhibits cancer dissemination by counteracting mechanosensitive BAR family protein assembly, while restoration of PM tension phenotypically convert malignant cells into a non-motile epithelial cell state.

Ventral stress fibers induce plasma membrane deformation in human fibroblasts

Interactions between the actin cytoskeleton and the plasma membrane are important in many eukaryotic cellular processes. During these processes, actin structures deform the cell membrane outward by applying forces parallel to the fiber's major axis (as in migration) or they deform the membrane inward by applying forces perpendicular to the fiber's major axis (as in the contractile ring during cytokinesis). Here we describe a novel actin-membrane interaction in human dermal myofibroblasts. When labeled with a cytosolic fluorophore, the myofibroblasts displayed prominent fluorescent structures on the ventral side of the cell. These structures are present in the cell membrane and colocalize with ventral actin stress fibers, suggesting that the stress fibers bend the membrane to form a "cytosolic pocket" that the fluorophores diffuse into, creating the observed structures. The existence of this pocket was confirmed by transmission electron microscopy. While dissolving the stress fibers, inhibiting fiber protein binding, or inhibiting myosin II binding of actin removed the observed pockets, modulating cellular contractility did not remove them. Taken together, our results illustrate a novel actin-membrane bending topology where the membrane is deformed outward rather than being pinched inward, resembling the topological inverse of the contractile ring found in cytokinesis.

Advanced mesoporous silica nanocarriers in cancer theranostics and gene editing applications

Targeted nanomaterials for cancer theranostics have been the subject of an expanding volume of research studies in recent years. Mesoporous silica nanoparticles (MSNs) are particularly attractive for such applications due to possibilities to synthesize nanoparticles (NPs) of different morphologies, pore diameters and pore arrangements, large surface areas and various options for surface functionalization. Functionalization of MSNs with different organic and inorganic molecules, polymers, surface-attachment of other NPs, loading and entrapping cargo molecules with on-desire release capabilities, lead to seemingly endless prospects for designing advanced nanoconstructs exerting multiple functions, such as simultaneous cancer-targeting, imaging and therapy. Describing composition and multifunctional capabilities of these advanced nanoassemblies for targeted therapy (passive, ligand-functionalized MSNs, stimuli-responsive therapy), including one or more modalities for imaging of tumors, is the subject of this review article, along with an overview of developments within a novel and attractive research trend, comprising the use of MSNs for CRISPR/Cas9 systems delivery and gene editing in cancer. Such advanced nanconstructs exhibit high potential for applications in image-guided therapies and the development of personalized cancer treatment.

Generation of 3D Tumor Spheroids with Encapsulating Basement Membranes for Invasion Studies

In the past, in vitro studies of invasion and tumor progression were performed primarily using cancer cells cultured on a flat, two‐dimensional (2D) surface in a monolayer. In recent years, however, many studies have demonstrated differences in cell signaling and cell migration between 2D and 3D cell cultures. Traditional 2D monolayer cancer cell invasion models do not fully recapitulate 3D cell‐to‐cell and cell−to−extracellular matrix interactions that in vivo models can provide. Moreover, although in vivo animal models are irreplaceable for studying tumor biology and metastasis, they are costly, time‐consuming, and impractical for answering preliminary questions. Thus, emergent and evolving 3D spheroid cell culture models have changed the way we study tumors and their interactions with their surrounding extracellular matrix. In the case of breast cancer, metastasis of breast cancer tumors results in high mortality rates, and thus development of robust cell culture models that are reproducible and practical for studying breast cancer progression is important for ultimately developing preventatives for cancer metastasis. This article provides a set of protocols for generating uniform spheroids with a thin sheet of basement membrane for studying the initial invasion of mammary epithelial cells into a surrounding collagen‐rich extracellular matrix. Details are provided for generating 3D spheroids with a basement membrane, polymerizing collagen I, embedding the spheroids in the 3D collagen gel, and immunostaining the spheroids for invasion studies. Published 2020. U.S. Government.

Basic Protocol 1: Growth of uniformly sized tumor spheroids with an encapsulating basement membrane

Basic Protocol 2: Polymerization and embedding of tumor spheroids in a 3D type I collagen gel

Alternate Protocol: Embedding of tumor spheroids in collagen gels using a sandwich method

Basic Protocol 3: Fixing and immunostaining of tumor spheroids embedded in 3D collagen gels

Roles of Porphyromonas gulae proteases in bacterial and host cell biology

Porphyromonas gulae, an animal-derived periodontal pathogen, expresses several virulence factors, including fimbria, lipopolysaccharide (LPS) and proteases. We previously reported that its invasive efficiency was dependent on fimbriae types. In addition, P. gulae LPS increased inflammatory responses via toll-like receptors. The present study was conducted to investigate the involvement of P. gulae proteases in bacterial and host cell biology. Porphyromonas gulae strains showed an ability to agglutinate mouse erythrocytes and also demonstrated co-aggregation with Actinomyces viscosus, while the protease inhibitors antipain, PMSF, TLCK and leupeptin diminished P. gulae proteolytic activity, resulting in inhibition of haemagglutination and co-aggregation with A. viscosus. In addition, specific proteinase inhibitors were found to reduce bacterial cell growth. Porphyromonas gulae inhibited Ca9-22 cell proliferation in a multiplicity of infection- and time-dependent manner. Additionally, P. gulae-induced decreases in cell contact and adhesion-related proteins were accompanied by a marked change in cell morphology from well spread to rounded. In contrast, inhibition of protease activity prevented degradation of proteins, such as E-cadherin, β-catenin and focal adhesion kinase, and also blocked inhibition of cell proliferation. Together, these results indicate suppression of the amount of human proteins, such as γ-globulin, fibrinogen and fibronectin, by P. gulae proteases, suggesting that a novel protease complex contributes to bacterial virulence.

Structural and functional analysis of LIM domain-dependent recruitment of paxillin to αvβ3 integrin-positive focal adhesions

The LIM domain-dependent localization of the adapter protein paxillin to β3 integrin-positive focal adhesions (FAs) is not mechanistically understood. Here, by combining molecular biology, photoactivation and FA-isolation experiments, we demonstrate specific contributions of each LIM domain of paxillin and reveal multiple paxillin interactions in adhesion-complexes. Mutation of β3 integrin at a putative paxillin binding site (β3^VE/YA) leads to rapidly inward-sliding FAs, correlating with actin retrograde flow and enhanced paxillin dissociation kinetics. Induced mechanical coupling of paxillin to β3^VE/YA integrin arrests the FA-sliding, thereby disclosing an essential structural function of paxillin for the maturation of β3 integrin/talin clusters. Moreover, bimolecular fluorescence complementation unveils the spatial orientation of the paxillin LIM-array, juxtaposing the positive LIM4 to the plasma membrane and the β3 integrin-tail, while in vitro binding assays point to LIM1 and/or LIM2 interaction with talin-head domain. These data provide structural insights into the molecular organization of β3 integrin-FAs.

HDAC6 regulates microtubule stability and clustering of AChRs at neuromuscular junctions

Microtubules (MTs) are known to be post-translationally modified at the neuromuscular junction (NMJ), hence increasing their stability. To date however, the function(s) of the dynamic MT network and its relative stability in the formation and maintenance of NMJs remain poorly described. Stabilization of the MT is dependent in part on its acetylation status, and HDAC6 is capable of reversing this post-translational modification. Here, we report that HDAC6 preferentially accumulates at NMJs and that it contributes to the organization and the stability of NMJs. Indeed, pharmacological inhibition of HDAC6 protects against MT disorganization and reduces the size of acetylcholine receptor (AChR) clusters. Moreover, the endogenous HDAC6 inhibitor paxillin interacts with HDAC6 in skeletal muscle cells, colocalizes with AChR aggregates, and regulates the formation of AChR. Our findings indicate that the focal insertion of AChRs into the postsynaptic membrane is regulated by stable MTs and highlight how an MT/HDAC6/paxillin axis participates in the regulation of AChR insertion and removal to control the structure of NMJs.

Switching between blebbing and lamellipodia depends on the degree of non-muscle myosin II activity

Cells can adopt both mesenchymal and amoeboid modes of migration through membrane protrusive activities, namely formation of lamellipodia and blebbing. How the molecular players control the transition between lamellipodia and blebs is yet to be explored. Here, we show that addition of the ROCK inhibitor Y27632 or low doses of blebbistatin, an inhibitor of non-muscle myosin II (NMII) ATPase activity and filament partitioning, induces blebbing to lamellipodia conversion (BLC), whereas addition of low doses of ML7, an inhibitor of myosin light chain kinase (MLCK), induces lamellipodia to blebbing conversion (LBC) in human MDA-MB-231 cells. Similarly, siRNA-mediated knockdown of ROCK and MLCK induces BLC and LBC, respectively. Interestingly, both blebs and lamellipodia membrane protrusions are able to maintain the ratio of phosphorylated to unphosphorylated regulatory light chain at cortices when MLCK and ROCK, respectively, are inhibited either pharmacologically or genetically, suggesting that MLCK and ROCK activities are interlinked in BLC and LBC. Such BLCs and LBCs are also inducible in other cell lines, including MCF7 and MCF10A. These studies reveal that the relative activity of ROCK and MLCK, which controls both the ATPase activity and filament-forming property of NMII, is a determining factor in whether a cell exhibits blebbing or lamellipodia.

Hic-5 is required for activation of pancreatic stellate cells and development of pancreatic fibrosis in chronic pancreatitis

Accumulated evidence suggests that activated pancreatic stellate cells (PSCs) serve as the main source of the extracellular matrix proteins accumulated under the pathological conditions leading to pancreatic fibrosis in chronic pancreatitis (CP). However, little is known about the mechanisms of PSC activation. PSCs have morphologic and functional similarities to hepatic stellate cells, which are activated by hydrogen peroxide-inducible clone-5 (Hic-5), a TGF-β1-induced protein. In this study, we investigated whether Hic-5 activates PSCs, which promote pancreatic fibrosis development in CP. Hic-5-knockout and wild type mice were subjected to caerulein injection to induce CP. Hic-5 expression was strongly upregulated in activated PSCs from human CP tissue and from mouse pancreatic fibrosis in caerulein-induced CP. Hic-5 deficiency significantly attenuated mouse pancreatic fibrosis and PSC activation in the experimental murine CP model. Mechanistically, Hic-5 knock down significantly inhibited the TGF-β/Smad2 signaling pathway, resulting in reduced collagen production and α-smooth muscle actin expression in the activated PSCs. Taken together, we propose Hic-5 as a potential marker of activated PSCs and a novel therapeutic target in CP treatment.

Paxillin family of focal adhesion adaptor proteins and regulation of cancer cell invasion

The paxillin family of proteins, including paxillin, Hic-5, and leupaxin, are focal adhesion adaptor/scaffolding proteins which localize to cell-matrix adhesions and are important in cell adhesion and migration of both normal and cancer cells. Historically, the role of these proteins in regulating the actin cytoskeleton through focal adhesion-mediated signaling has been well documented. However, studies in recent years have revealed additional functions in modulating the microtubule and intermediate filament cytoskeletons to affect diverse processes including cell polarization, vesicle trafficking and mechanosignaling. Expression of paxillin family proteins in stromal cells is also important in regulating tumor cell migration and invasion through non-cell autonomous effects on the extracellular matrix. Both paxillin and Hic-5 can also influence gene expression through a variety of mechanisms, while their own expression is frequently dysregulated in various cancers. Accordingly, these proteins may serve as valuable targets for novel diagnostic and treatment approaches in cancer.

Paxillin knockdown suppresses metastasis and epithelial‑mesenchymal transition in colorectal cancer via the ERK signalling pathway

Paxillin (PXN) is a cytoplasmic protein that plays an important role in regulating focal adhesion, cytoskeletal rearrangements and cell motility. The present study aimed to investigate the role of PXN in the metastasis of human colorectal cancer (CRC) and its possible mechanisms. Immunohistochemical staining of tissues from 102 surgical CRC patients revealed that high PXN expression was positively correlated with tumour‑node‑metastasis (TNM) stage, lymph node metastasis, distant metastasis, and recurrence at distant sites after radical surgery. In 24 cases of stage IV CRC, PXN expression in liver metastasis was higher than that in the matched primary tumour. The knockdown of PXN inhibited the proliferation, migration and invasion potential of SW480 cells in vitro and in vivo. Transmission electron microscopy revealed the effect of PXN on ultrastructural characteristics, observed mainly in microvilli and desmosomes. The downregulation of PXN decreased the activation of extracellular regulated protein kinase (ERK) and suppressed the epithelial‑mesenchymal transition (EMT) process. Following the downregulation of PXN, the addition of an ERK activator or inhibitor restored or further suppressed EMT, respectively, accompanied by corresponding changes in cell migration and invasion. Collectively, the present results confirmed the important role of PXN in CRC metastasis and revealed that PXN regulated EMT progression via the ERK signalling pathway. PXN may represent a future therapeutic strategy to prevent the EMT‑associated progression and invasion of CRC.

Computational models of melanoma

Genes, proteins, or cells influence each other and consequently create patterns, which can be increasingly better observed by experimental biology and medicine. Thereby, descriptive methods of statistics and bioinformatics sharpen and structure our perception. However, additionally considering the interconnectivity between biological elements promises a deeper and more coherent understanding of melanoma. For instance, integrative network-based tools and well-grounded inductive in silico research reveal disease mechanisms, stratify patients, and support treatment individualization. This review gives an overview of different modeling techniques beyond statistics, shows how different strategies align with the respective medical biology, and identifies possible areas of new computational melanoma research.

Hepatitis B virus X protein promotes tumor invasion and poor prognosis in hepatocellular carcinoma via phosphorylation of paxillin at Serine 178 by activation of the c-Jun NH2-terminal kinase

Hepatitis B virus X protein (HBx) plays critical roles in hepatocellular tumorigenesis by activating different signaling pathways, including the c-Jun NH2-terminal kinase (JNK) pathway. Phosphorylation of paxillin (PXN) promotes cell migration via activation of the JNK signaling pathway, but PXN overexpression is not associated with poor outcome in patients with hepatocellular carcinoma (HCC). HBx gene manipulation and Western blotting indicated that phosphorylation of PXN at Serine 178 (p^S178-PXN) by HBx may promote invasiveness in HCC cells via HBx-mediated JNK activation. Immunohistochemical analysis indicated a positive correlation between p^S178-PXN and HBx expression levels in tumor specimens. The overall survival (OS) and relapse-free survival (RFS) were poorer in patients with high-p^S178-PXN expressing or high-HBx expressing tumors than in patients with low-p^S178-PXN expressing or low-HBx expressing tumors. In conclusion, phosphorylation of PXN at Serine 178 by HBx-mediated JNK activation may therefore play a critical role in tumor invasiveness and poor prognosis in patients with HBV-infected hepatocellular tumors. The expression levels of p^S178-PXN may be a reliable prognostic biomarker to predict the clinical outcomes in patients with HBV-associated HCC.

The role of hydrogen peroxide-inducible clone-5 in tumor progression

The poor prognosis of cancers such as hepatocellular carcinoma is due to high recurrence rate mainly caused by metastasis. Target therapy aiming at critical signal molecules within these pathways is one of the promising strategies for the prevention of metastasis. Hydrogen peroxide-inducible clone-5 (Hic-5), which belongs to the paxillin superfamily, is emerging as a potential target along the metastatic signaling pathway. Hic-5 and paxillin share similar structural features; however, there are a lot of different biochemical properties between them, including tissue-specific distribution, regulation of gene expression, critical signal cascade, and the impacts on cellular phenotypes. This review focus on the recent studies of Hic-5 related to its impacts on signal transduction and transcription responsible for tumor progression. Hic-5 may regulate mitogen-activated protein kinase cascade for cell migration and invasion in various systems. Hic-5 can mediate transforming growth factor-β1-induced epithelial-mesenchymal transition (EMT) via RhoA- and Src-dependent signaling. Moreover, Hic-5 plays a central role in a positive feedback Hic-5-NADPH oxidase-ROS-JNK signal cascade. This sustained signaling is required for regulating EMT-related genes including E-cadherin, Snail, MMP9, and Zeb-1. In addition, Hic-5 can be a transcription coregulatory factor for a lot of nuclear receptors. Owing to the critical role of Hic-5 in signal transduction and transcription responsible for tumor progression, it can be a potential therapeutic target for the prevention of tumor metastasis.

Fluid flow-induced activation of subcellular AMPK and its interaction with FAK and Src

AMP-activated protein kinase (AMPK) is a metabolic energy sensor that plays a critical role in cancer cell survival and growth. While the physical microenvironment is believed to influence tumor growth and progression, its role in AMPK regulation remains largely unknown. In the present study, we evaluated AMPK response to mechanical forces and its interaction with other mechano-responsive signaling proteins, FAK and Src. Using genetically encoded biosensors that can detect AMPK activities at different subcellular locations (cytosol, plasma membrane, nucleus, mitochondria, and Golgi apparatus), we observed that AMPK responds to shear stress in a subcellular location-dependent manner in breast cancer cells (MDA-MB-231). While normal epithelial cells (MCF-10A) also similarly responded to shear stress, they are less sensitive to shear stress compared to MDA-MB-231 cells. Inhibition of FAK and Src significantly decreased the basal activity level of AMPK at all five subcellular locations in MDA-MB-231 cells and selectively blocked shear stress-induced AMPK activation. Moreover, testing with cytoskeletal drugs revealed that myosin II might be the critical mediator of shear stress-induced AMPK activation in MDA-MB-231 cells. These findings suggest that breast cancer cells and normal epithelial cells may have different mechanosensitivity in AMPK signaling and that FAK and Src as well as the myosin II-dependent signaling pathway are involved in subcellular AMPK mechanotransduction in breast cancer cells.

HIC-5 in cancer-associated fibroblasts contributes to esophageal squamous cell carcinoma progression

Esophageal squamous cell carcinoma (ESCC) remains one of the most common malignancies in China and has a high metastasis rate and poor prognosis. Cancer-associated fibroblasts (CAFs), a prominent component of the tumor microenvironment, can affect tumor progression and metastasis, but the underlying mechanism remains unclear. There are no studies that explore the role of hydrogen peroxide-inducible clone 5 (HIC-5) in ESCC or compare the role of HIC-5 in CAFs and adjacent noncancerous normal fibroblasts (NFs). In this study, we isolated primary CAFs and NFs from ESCC patients. HIC-5 was highly expressed in CAFs from the tumor stroma of human ESCC patients. HIC-5 knockdown in CAFs inhibited the migration and invasion of ESCC cells in vitro. Supernatant CCL2 levels of CAFs were significantly higher after TGF-β stimulation and lower after knocking down HIC-5 expression, independent of TGF-β treatment. HIC-5 knockdown in CAFs led xenograft tumors derived from ESCC cells mixed with CAFs to present more regular morphology, express higher CDH1, and lower CCL2. Further RNA-seq data showed that HIC-5 has distinct biological functions in CAFs vs. NFs, especially in cell movement and the Rho GTPase signaling kinase pathway, which was verified by wound-healing assays and western blotting. An ESCC tissue microarray revealed that increased HIC-5 expression in the tumor stroma was associated with positive lymph node metastasis and a higher TNM stage. In summary, we identified that stromal HIC-5 was a predictive risk factor for lymph node metastasis in human ESCC and that CAF-derived HIC-5 regulated ESCC cell migration and invasion by regulating cytokines and modifying the ECM.

Hic-5 in pancreatic stellate cells affects proliferation, apoptosis, migration, invasion of pancreatic cancer cells and postoperative survival time of pancreatic cancer

Pancreatic cancer is one of the most severe types of tumors, with a 5-year survival rate of less than 7%. The prognosis and treatment of pancreatic cancer are largely limited by the extent of tumor invasion and the presence of lymph node and distant metastases. Therefore, exploring the biological behavior of pancreatic cancer cells (PCCs) is extremely important for the understanding, diagnosis, and treatment of pancreatic cancer. Current studies have shown that pancreatic stellate cells (PSCs) regulate the biological behavior of PCCs, such as their proliferation, apoptosis, invasion, and migration, by remodeling the extracellular matrix. Though Hic-5 is an important gene in PSCs, no study has investigated the regulation of PCCs by Hic-5. Here, we demonstrate that Hic-5 expression is upregulated in pancreatic cancer and that siRNA transfection can effectively inhibit Hic-5 expression. Compared to the control group, Hic-5 inhibition significantly reduced proliferation, increased apoptosis, and reduced invasion and migration of PCCs. Moreover, the inhibition of Hic-5 expression simultaneously reduced matrix metalloproteinase-9 (MMP-9) expression. Statistical analysis revealed that Hic-5 expression was higher among the pancreatic cancer group than among the normal group and was negatively correlated with postoperative survival time among patients with pancreatic cancer. These results have important clinical significance for further exploring the molecular mechanism involved in Hic-5-mediated invasion and metastasis of pancreatic cancer and ameliorating the prognosis of patients with pancreatic cancer.

The focal adhesion scaffold protein Hic-5 regulates vimentin organization in fibroblasts

Focal adhesion (FA)-stimulated reorganization of the F-actin cytoskeleton regulates cellular size, shape, and mechanical properties. However, FA cross-talk with the intermediate filament cytoskeleton is poorly understood. Genetic ablation of the FA-associated scaffold protein Hic-5 in mouse cancer-associated fibroblasts (CAFs) promoted a dramatic collapse of the vimentin network, which was rescued following EGFP-Hic-5 expression. Vimentin collapse correlated with a loss of detergent-soluble vimentin filament precursors and decreased vimentin S72/S82 phosphorylation. Additionally, fluorescence recovery after photobleaching analysis indicated impaired vimentin dynamics. Microtubule (MT)-associated EB1 tracking and Western blotting of MT posttranslational modifications indicated no change in MT dynamics that could explain the vimentin collapse. However, pharmacological inhibition of the RhoGTPase Cdc42 in Hic-5 knockout CAFs rescued the vimentin collapse, while pan-formin inhibition with SMIFH2 promoted vimentin collapse in Hic-5 heterozygous CAFs. Our results reveal novel regulation of vimentin organization/dynamics by the FA scaffold protein Hic-5 via modulation of RhoGTPases and downstream formin activity.

The Leptin induced Hic-5 expression and actin puncta formation by the FAK/Src-dependent pathway in MCF10A mammary epithelial cells

Introduction: Leptin is a hormone secreted by adipocytes that has been associated with the epithelial-mesenchymal transition (EMT). Additionally, leptin promotes the migration and invasion of mammary epithelial cells through the activation of FAK and Src kinases, which are part of a regulatory complex of signaling pathways that promotes the expression of proteins related to the formation of proteolytic structures involved in the invasion and progression of cancer. Recently, overexpression and activation of Hic-5 during the EMT have been shown to induce the formation of actin puncta; these structures are indicative of the formation and functionality of invadopodia, which promote the local degradation of extracellular matrix components and cancer metastasis. Objective: To evaluate the role of FAK and Src kinases in the expression of Hic-5 during the epithelial-mesenchymal transition induced by leptin in MCF10A cells. Materials and methods: We used specific inhibitors of FAK (PF-573228) and Src (PP2) to evaluate Hic-5 expression and subcellular localization by Western blot and immunofluorescence assays and to investigate the formation of actin puncta by epifluorescence in MCF10A cells stimulated with leptin. Results: Leptin induced an increase in Hic-5 expression and the formation of actin puncta. Pretreatment with inhibitors of FAK (PF-573228) and Src (PP2) promoted a decrease in Hic-5 expression and actin puncta formation in the non-tumorigenic mammary epithelial cell line MCF10A. Conclusion: In MCF10A cells, leptin-induced Hic-5 expression and perinuclear localization, as well as the formation of actin puncta through a mechanism dependent on the kinase activity of FAK and Src.

Hydrogen peroxide inducible clone-5 sustains NADPH oxidase-dependent reactive oxygen species-c-jun N-terminal kinase signaling in hepatocellular carcinoma

Target therapy aiming at critical molecules within the metastatic signal pathways is essential for prevention of hepatocellular carcinoma (HCC) progression. Hic-5 (hydrogen peroxide inducible clone-5) which belongs to the paxillin superfamily, can be stimulated by a lot of metastatic factors, such as transforming growth factor (TGF-β), hepatocyte growth factor (HGF), and reactive oxygen species (ROS). Previous studies implicated Hic-5 cross-talks with the ROS-c-jun N-terminal kinase (JNK) signal cascade in a positive feedback manner. In this report, we addressed this issue in a comprehensive manner. By RNA interference and ectopic Hic-5 expression, we demonstrated Hic-5 was essential for activation of NADPH oxidase and ROS generation leading to activation of downstream JNK and c-jun transcription factor. This was initiated by interaction of Hic-5 with the regulator and adaptor of NADPH oxidase, Rac1 and Traf4, respectively, which may further phosphorylate the nonreceptor tyrosine kinase Pyk2 at Tyr881. On the other hand, promoter activity assay coupled with deletion mapping and site directed mutagenesis strategies demonstrated the distal c-jun and AP4 putative binding regions (943–1126 bp upstream of translational start site) were required for transcriptional activation of Hic-5. Thus Hic-5 was both downstream and upstream of NADPH oxidase-ROS-JNK-c-jun cascade. This signal circuit was essential for regulating the expression of epithelial mesenchymal transition (EMT) factors, such as Snail, Zeb1, E-cadherin, and matrix metalloproteinase 9, involved in HCC cell migration and metastasis. Due to the limited expression of Hic-5 in normal tissue, it can be a promising therapeutic target for preventing HCC metastasis.

Targeting Cell Adhesion Molecules via Carbonate Apatite-Mediated Delivery of Specific siRNAs to Breast Cancer Cells In Vitro and In Vivo

While several treatment strategies are applied to cure breast cancer, it still remains one of the leading causes of female deaths worldwide. Since chemotherapeutic drugs have severe side effects and are responsible for development of drug resistance in cancer cells, gene therapy is now considered as one of the promising options to address the current treatment limitations. Identification of the over-expressed genes accounting for constitutive activation of certain pathways, and their subsequent knockdown with specific small interfering RNAs (siRNAs), could be a powerful tool in inhibiting proliferation and survival of cancer cells. In this study, we delivered siRNAs against mRNA transcripts of over-regulated cell adhesion molecules such as catenin alpha 1 (CTNNA1), catenin beta 1 (CTNNB1), talin-1 (TLN1), vinculin (VCL), paxillin (PXN), and actinin-1 (ACTN1) in human (MCF-7 and MDA-MB-231) and murine (4T1) cell lines as well as in the murine female Balb/c mice model. In order to overcome the barriers of cell permeability and nuclease-mediated degradation, the pH-sensitive carbonate apatite (CA) nanocarrier was used as a delivery vehicle. While targeting CTNNA1, CTNNB1, TLN1, VCL, PXN, and ACTN1 resulted in a reduction of cell viability in MCF-7 and MDA-MB-231 cells, delivery of all these siRNAs via carbonate apatite (CA) nanoparticles successfully reduced the cell viability in 4T1 cells. In 4T1 cells, delivery of CTNNA1, CTNNB1, TLN1, VCL, PXN, and ACTN1 siRNAs with CA caused significant reduction in phosphorylated and total AKT levels. Furthermore, reduced band intensity was observed for phosphorylated and total MAPK upon transfection of 4T1 cells with CTNNA1, CTNNB1, and VCL siRNAs. Intravenous delivery of CTNNA1 siRNA with CA nanoparticles significantly reduced tumor volume in the initial phase of the study, while siRNAs targeting CTNNB1, TLN1, VCL, PXN, and ACTN1 genes significantly decreased the tumor burden at all time points. The tumor weights at the end of the treatments were also notably smaller compared to CA. This successfully demonstrates that targeting these dysregulated genes via RNAi and by using a suitable delivery vehicle such as CA could serve as a promising therapeutic treatment modality for breast cancers.

Hic-5 regulates Src-induced invadopodia rosette formation and organization

Fibroblasts transformed by the proto-oncogene Src form individual invadopodia that can spontaneously self-organize into large matrix-degrading superstructures called rosettes. However, the mechanisms by which the invadopodia can spatiotemporally reorganize their architecture is not well understood. Here, we show that Hic-5, a close relative of the scaffold protein paxillin, is essential for the formation and organization of rosettes in active Src-transfected NIH3T3 fibroblasts and cancer-associated fibroblasts. Live cell imaging, combined with domain-mapping analysis of Hic-5, identified critical motifs as well as phosphorylation sites that are required for the formation and dynamics of rosettes. Using pharmacological inhibition and mutant expression, we show that FAK kinase activity, along with its proximity to and potential interaction with the LD2,3 motifs of Hic-5, is necessary for rosette formation. Invadopodia dynamics and their coalescence into rosettes were also dependent on Rac1, formin, and myosin II activity. Superresolution microscopy revealed the presence of formin FHOD1 and INF2-mediated unbranched radial F-actin fibers emanating from invadopodia and rosettes, which may facilitate rosette formation. Collectively, our data highlight a novel role for Hic-5 in orchestrating the organization of invadopodia into higher-order rosettes, which may promote the localized matrix degradation necessary for tumor cell invasion.

Cytosolic phospholipase A2α modulates cell-matrix adhesion via the FAK/paxillin pathway in hepatocellular carcinoma

Objective

To explore the effect of cytosolic phospholipase A2α (cPLA2α) on hepatocellular carcinoma (HCC) cell adhesion and the underlying mechanisms.

Methods

Cell adhesion, detachment, and hanging-drop assays were utilized to examine the effect of cPLA2α on the cell-matrix and cell-cell adhesion. Downstream substrates and effectors of cPLA2α were screened via a phospho-antibody microarray. Associated signaling pathways were identified by the functional annotation tool DAVID. Candidate proteins were verified using Western blot and colocalization was investigated via immunofluorescence. Western blot and immunohistochemistry were used to detect protein expression in HCC tissues. Prognosis evaluation was conducted using Kaplan-Meier and Cox-proportional hazards regression analyses.

Results

Our findings showed that cPLA2α knockdown decreases cell-matrix adhesion but increases cell-cell adhesion in HepG2 cells. Microarray analysis revealed that phosphorylation of multiple proteins at specific sites were regulated by cPLA2α. These phosphorylated proteins were involved in various biological processes. In addition, our results indicated that the focal adhesion pathway was highly enriched in the cPLA2α-relevant signaling pathway. Furthermore, cPLA2α was found to elevate phosphorylation levels of FAK and paxillin, two crucial components of focal adhesion. Moreover, localization of p-FAK to focal adhesions in the plasma membrane was significantly reduced with the downregulation of cPLA2α. Clinically, cPLA2α expression was positively correlated with p-FAK levels. Additionally, high expression of both cPLA2α and p-FAK predicted the worst prognoses for HCC patients.

Conclusions

Our study indicated that cPLA2α may promote cell-matrix adhesion via the FAK/paxillin pathway, which partly explains the malignant cPLA2α phenotype seen in HCC.

A Comparative Quantitative LC-MS/MS Profiling Analysis of Human Pancreatic Adenocarcinoma, Adjacent-Normal Tissue, and Patient-Derived Tumour Xenografts

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide; it develops in a relatively symptom-free manner, leading to rapid disease progression and metastasis, leading to a 5-year survival rate of less than 5%. A lack of dependable diagnostic markers and rapid development of resistance to conventional therapies are among the problems associated with management of the disease. A better understanding of pancreatic tumour biology and discovery of new potential therapeutic targets are important goals in pancreatic cancer research. This study describes the comparative quantitative LC-MS/MS proteomic analysis of the membrane-enriched proteome of 10 human pancreatic ductal adenocarcinomas, 9 matched adjacent-normal pancreas and patient-derived xenografts (PDXs) in mice (10 at F1 generation and 10 F2). Quantitative label-free LC-MS/MS data analysis identified 129 proteins upregulated, and 109 downregulated, in PDAC, compared to adjacent-normal tissue. In this study, analysing peptide MS/MS data from the xenografts, great care was taken to distinguish species-specific peptides definitively derived from human sequences, or from mice, which could not be distinguished. The human-only peptides from the PDXs are of particular value, since only human tumour cells survive, and stromal cells are replaced during engraftment in the mouse; this list is, therefore, enriched in tumour-associated proteins, some of which might be potential therapeutic or diagnostic targets. Using human-specific sequences, 32 proteins were found to be upregulated, and 113 downregulated in PDX F1 tumours, compared to primary PDAC. Differential expression of CD55 between PDAC and normal pancreas, and expression across PDX generations, was confirmed by Western blotting. These data indicate the value of using PDX models in PDAC research. This study is the first comparative proteomic analysis of PDAC which employs PDX models to identify patient tumour cell-associated proteins, in an effort to find robust targets for therapeutic treatment of PDAC.

A mitochondrial ROS pathway controls matrix metalloproteinase 9 levels and invasive properties in RAS-activated cancer cells

Matrix metalloproteinases (MMPs) are tissue‐remodeling enzymes involved in the processing of various biological molecules. MMPs also play important roles in cancer metastasis, contributing to angiogenesis, intravasation of tumor cells, and cell migration and invasion. Accordingly, unraveling the signaling pathways controlling MMP activities could shed additional light on cancer biology. Here, we report a molecular axis, comprising the molecular adaptor hydrogen peroxide‐inducible clone‐5 (HIC‐5), NADPH oxidase 4 (NOX4), and mitochondria‐associated reactive oxygen species (mtROS), that regulates MMP9 expression and may be a target to suppress cancer metastasis. We found that this axis primarily downregulates mtROS levels which stabilize MMP9 mRNA. Specifically, HIC‐5 suppressed the expression of NOX4, the source of the mtROS, thereby decreasing mtROS levels and, consequently, destabilizing MMP9 mRNA. Interestingly, among six cancer cell lines, only EJ‐1 and MDA‐MB‐231 cells exhibited upregulation of NOX4 and MMP9 expression after shRNA‐mediated HIC‐5 knockdown. In these two cell lines, activating RAS mutations commonly occur, suggesting that the HIC‐5–mediated suppression of NOX4 depends on RAS signaling, a hypothesis that was supported experimentally by the introduction of activated RAS into mammary epithelial cells. Notably, HIC‐5 knockdown promoted lung metastasis of MDA‐MB‐231 cancer cells in mice. The tumor growth of HIC‐5–silenced MDA‐MB‐231 cells at the primary sites was comparable to that of control cells. Consistently, the invasive properties of the cells, but not their proliferation, were enhanced by the HIC‐5 knockdown in vitro. We conclude that NOX4‐mediated mtROS signaling increases MMP9 mRNA stability and affects cancer invasiveness but not tumor growth.

Hic-5 expression is a major indicator of cancer cell morphology, migration, and plasticity in three-dimensional matrices

The focal adhesion proteins Hic-5 and paxillin have been previously identified as key regulators of MDA-MB-231 breast cancer cell migration and morphologic mesenchymal-amoeboid plasticity in three-dimensional (3D) extracellular matrices (ECMs). However, their respective roles in other cancer cell types have not been evaluated. Herein, utilizing 3D cell-derived matrices and fibronectin-coated one-dimensional substrates, we show that across a variety of cancer cell lines, the level of Hic-5 expression serves as the major indicator of the cells primary morphology, plasticity, and in vitro invasiveness. Domain mapping studies reveal sites critical to the functions of both Hic-5 and paxillin in regulating phenotype, while ectopic expression of Hic-5 in cell lines with low endogenous levels of the protein is sufficient to induce a Rac1-dependent mesenchymal phenotype and, in turn, increase amoeboid-mesenchymal plasticity and invasion. We show that the activity of vinculin, when coupled to the expression of Hic-5 is required for the mesenchymal morphology in the 3D ECM. Taken together, our results identify Hic-5 as a critical modulator of tumor cell phenotype that could be utilized in predicting tumor cell migratory and invasive behavior in vivo.

Possible roles for glucocorticoid signalling in breast cancer

Our understanding of breast cancer biology, and our ability to manipulate breast cancers have grown exponentially in the last 20 years. Much of that expansion has focused on the roles of steroids in driving these neoplasms. Initially this research focused on estrogens and progesterone receptors, and more recently on androgen actions in breast cancers. This review aims to make the case for glucocorticoids as the next essential steroid subclass that contributes significantly to our understanding of steroidogenic regulation of these neoplasms. Glucocorticoids have the potential to play multiple roles in the regulation of breast cancers including their control of cellular differentiation, apoptosis and proliferation. Beyond this they also act as a master integrator of organ homeostats in relation to such as circadian rhythms and stress responses. Therefore a better understanding of glucocorticoids and breast cancer could help to explain some of the epidemiological links between circadian disruption and/or stress and breast cancer development. Finally glucocorticoids are currently used during chemotherapeutic treatment in breast cancer therapy and yet results of various studies suggest that this may have an adverse impact on treatment success. This review aims to summarise the current evidence for glucocorticoids as actors in breast cancer and then suggest future essential approaches in order to determine the roles of glucocorticoids in this disease.

Paxillin actions in the nucleus

Paxillin is a group III LIM domain protein that is best characterized as a cytoplasmic scaffold/adaptor protein that functions primarily as a mediator of focal adhesion. However, emerging studies indicate that paxillin's functions are far broader. Not only does paxillin appear to regulate cytoplasmic kinase signaling, but it also cycles between the cytoplasm and nucleus, and may serve as an important regulator of mRNA trafficking and subsequent translation. Herein, we provide some insights suggesting that paxillin, like its relative Hic-5, has nuclear binding partners and mediates critical processes within the nucleus, at least in part functioning as coregulator of nuclear receptors and nuclear kinases to mediate genomic signaling.

The serum protein profile of early parity which induces protection against breast cancer

Early parity reduces the risk of breast cancer in women while nulliparity and late parity increase the risk of breast cancer. In order to translate this protection to women where early pregnancy is not feasible, much work has focused on understanding how parity confers protection against breast cancer, the molecular mechanisms by which this occurs is still not well understood. Healthy parous and nulliparous women were recruited for this study. We assessed serum protein profiles of early parous, late parous, and nulliparous women using the Phospho Explorer antibody array. Significantly altered proteins identified were validated by Western blot analysis. In silico analysis was performed with the data obtained. Our findings indicate increased phosphorylation levels of CDK1, AKT1 and Epo-R increased cell cycle and cell proliferation in late/nulliparous women. Increased levels of LIMK1, paxillin, caveolin-1, and tyrosine hydroxylase in late/nulliparous women demonstrate enhanced cell stress while decreased activity of p-p53 and pRAD51 in late/nulliparous women indicates decreased apoptosis and increased genomic instability. Further, increased levels of pFAK, pCD3zeta, pSTAT5B, MAP3K8 in early parous women favor enhanced innate/adaptive immunity. Overall, we have identified a unique protein signature that is responsible for the decreased risk of breast cancer and these proteins can also serve as biomarkers to predict the risk of breast cancer.

Hic-5 regulates fibrillar adhesion formation to control tumor extracellular matrix remodeling through interaction with tensin1

The linearization of the stromal extracellular matrix (ECM) by cancer associated fibroblasts (CAFs) facilitates tumor cell growth and metastasis. However, the mechanism by which the ECM is remodeled is not fully understood. Hic-5 (TGFβ1i1), a focal adhesion scaffold protein, has previously been reported to be crucial for stromal ECM deposition and remodeling in vivo. Herein we show that CAFs lacking Hic-5 exhibit a significant reduction in the ability to form fibrillar adhesions, a specialized form of focal adhesion that promote fibronectin fibrillogenesis. Hic-5 was found to promote fibrillar adhesion formation through a newly characterized interaction with tensin1. Furthermore, Src dependent phosphorylation of Hic-5 facilitated the interaction with tensin1 to prevent β1 integrin internalization and trafficking to the lysosome. The interaction between Hic-5 and tensin1 was mechanosensitive, promoting fibrillar adhesion formation and fibronectin fibrillogenesis in a rigidity dependent fashion. Importantly, this Src dependent mechanism was conserved in three-dimensional (3D) ECM environments. Immunohistochemistry of tensin1 showed enrichment in CAFs in vivo, which was abrogated upon deletion of Hic-5. Interestingly, elevated Hic-5 expression correlates with reduced distant metastasis free survival in patients with basal-like, HER2+ and grade 3 tumors. Thus, we have identified Hic-5 as a crucial regulator of ECM remodeling in CAFs by promoting fibrillar adhesion formation through a novel interaction with tensin1.

FAK and paxillin, two potential targets in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer in large part due to late diagnosis and a lack of effective screening tests. In spite of recent progress in imaging, surgery and new therapeutic options for pancreatic cancer, the overall five-year survival still remains unacceptably low. Numerous studies have shown that focal adhesion kinase (FAK) is activated in many cancers including PDAC and promotes cancer progression and metastasis. Paxillin, an intracellular adaptor protein that plays a key role in cytoskeletal organization, connects integrins to FAK and plays a key role in assembly and disassembly of focal adhesions. Here, we have reviewed evidence in support of FAK as a potential therapeutic target and summarized related combinatorial therapies.