Prognostic value of EZH2, paxillin expression and DNA ploidy of breast adenocarcinoma: correlation to pathologic predictors

PURPOSE

The objective of this study was to examine the association of EZH2 and paxillin expression and DNA ploidy status with pathological parameters of breast cancer, aiming to correlate tumor phenotype with its malignant behavior.

METHODS

EZH2 and paxillin expression and DNA ploidy were evaluated in imprint smear samples obtained from 105 breast tumors after surgical removal.

RESULTS

Increased expression of paxillin was associated with p53 expression (p=0.005), Ki-67 expression (p=0.018) and EZH2 expression (p<0.0001). EZH2 expression correlated with estrogen receptor (ER) and progesterone receptor (PR) status (p=0.01 and p=0.035, respectively), and expression of p53 and Ki-67 (p=0.007 and p<0.0001, respectively). Aneuploid tumors were significantly correlated with poor differentiation (p=0.000), stage of disease (p=0.000), size of the primary tumor (p=0.015), presence of nodal metastasis (p=0.001), ER status (p=0.008), cerbB2 status (p=0.012), and expression of Ki-67 (p=0.001) and EGFR (p=0.018). Multivariate analysis of ploidy results using paxillin and EZH2 expression as dependent variables revealed that aneuploid tumors were associated with disease stage and grade of differentiation, cerbB2 expression and EZH2 expression.

CONCLUSION

Our results show that aneuploid tumors, EZH2 expression and paxillin expression correlate with more aggressive phenotype of breast cancer.

Expression of claudin, paxillin and FRA-1 in non-nodular breast lesions in association with microcalcifications

CONTEXT AND OBJECTIVE

The possible role of adhesion molecules in early breast carcinogenesis has been shown in the literature. We aimed to analyze early adhesion imbalances in non-nodular breast lesions and their association with precursor lesions, in order to ascertain whether these alterations exist and contribute towards early carcinogenesis.

DESIGN AND SETTING

Retrospective cross-sectional study based on medical records at a private radiological clinic in São Paulo, Brazil.

METHODS

We retrospectively reviewed the medical records of all consecutive women attended between August 2006 and July 2007 who presented mammographic evidence of breast microcalcifications classified as Breast Imaging Reporting and Data System Atlas (BI-RADS) type 4. These women underwent stereotaxic biopsy. Clinical, radiological and pathological data were collected, and immunohistochemical assays searched for claudin, paxillin, FRA-1 and HER-2.

RESULTS

Over this period, 127 patients were evaluated. Previous BI-RADS diagnoses showed that 69 cases were in category 4A, 47 in 4B and 11 in 4C. Morphological assessment showed benign entities in 86.5%. Most of the benign lesions showed preserved claudin expression, associated with paxillin (P < 0.001). Paxillin and HER-2 expressions were correlated. FRA-1 expression was also strongly associated with HER-2 expression (P < 0.001).

CONCLUSIONS

Although already present in smaller amounts, imbalance of adhesion molecules is not necessarily prevalent in non-nodular breast lesions. Since FRA-1 expression reached statistically significant correlations with radiological and morphological diagnoses and HER-2 status, it may have a predictive role in this setting.

Raster image correlation spectroscopy in live cells

Raster image correlation spectroscopy (RICS) is a noninvasive technique to detect and quantify events in a live cell, including concentration of molecules and diffusion coefficients of molecules; in addition, by measuring changes in diffusion coefficients, RICS can indirectly detect binding. Any specimen containing fluorophores that can be imaged with a laser scanning microscope can be analyzed using RICS. There are other techniques to measure diffusion coefficients and binding; however, RICS fills a unique niche. It provides spatial information and can be performed in live cells using a conventional confocal microscope. It can measure a range of diffusion coefficients that is not accessible with any other single optical correlation-based technique. In this article we describe a protocol to obtain raster scanned images with an Olympus FluoView FV1000 confocal laser scanning microscope using Olympus FluoView software to acquire data and SimFCS software to perform RICS analysis. Each RICS measurement takes several minutes. The entire procedure can be completed in ∼2 h. This procedure includes focal volume calibration using a solution of fluorophores with a known diffusion coefficient and measurement of the diffusion coefficients of cytosolic enhanced green fluorescent protein (EGFP) and EGFP-paxillin.

Dynamics and mechanism of p130Cas localization to focal adhesions

The docking protein p130Cas is a major Src substrate involved in integrin signaling and mechanotransduction. Tyrosine phosphorylation of p130Cas in focal adhesions (FAs) has been linked to enhanced cell migration, invasion, proliferation, and survival. However, the mechanism of p130Cas targeting to FAs is uncertain, and dynamic aspects of its localization have not been explored. Using live cell microscopy, we show that fluorophore-tagged p130Cas is a component of FAs throughout the FA assembly and disassembly stages, although it resides transiently in FAs with a high mobile fraction. Deletion of either the N-terminal Src homology 3 (SH3) domain or the Cas-family C-terminal homology (CCH) domain significantly impaired p130Cas FA localization, and deletion of both domains resulted in full exclusion. Focal adhesion kinase was implicated in the FA targeting function of the p130Cas SH3 domain. Consistent with their roles in FA targeting, both the SH3 and CCH domains were found necessary for p130Cas to fully undergo tyrosine phosphorylation and promote cell migration. By revealing the capacity of p130Cas to function in FAs throughout their lifetime, clarifying FA targeting mechanism, and demonstrating the functional importance of the highly conserved CCH domain, our results advance the understanding of an important aspect of integrin signaling.

Viscum album agglutinin-I induces degradation of cytoskeletal proteins in leukaemia PLB-985 cells differentiated toward neutrophils: cleavage of non-muscle myosin heavy chain-IIA by caspases

The role of the anti-cancer agent Viscum album agglutinin-I (VAA-I) in leukaemia PLB-985 cells differentiated toward a neutrophil-like phenotype by dimethylsulphoxide (PLB-985D) has never been studied. This study investigated whether or not VAA-I can induce cytoskeletal breakdown in PLB-985D cells, as previously observed in undifferentiated PLB-985 cells. VAA-I was found to induce apoptosis in PLB-985D cells, as assessed by cytology and by degradation of gelsolin, an event known to occur via caspase-3 activation. VAA-I induced cytoskeletal breakdown based on the disruption of the F-actin network and cleavage of paxillin, vimentin and lamin B(1). In addition, we demonstrated, for the first time, that non-muscle myosin heavy chain IIA (NMHC-IIA) was cleaved by VAA-I treatment. Degradation of NMHC-IIA was reversed by the pan caspase inhibitor z-VAD-fmk in PLB-985D cells and neutrophils. However, unlike lamin B(1), no NMHC-IIA was detected on the cell surface of apoptotic neutrophils. In conclusion, PLB-985D cells responded in a similar manner to neutrophils regarding the degradation of the tested cytoskeletal. Therefore, PLB-985D cells may provide a suitable substitute for neutrophils in screening experiments, preventing extensive neutrophil cell isolation.

Mechanical stretch has contrasting effects on mediator release from bronchial epithelial cells, with a rho-kinase-dependent component to the mechanotransduction pathway

INTRODUCTION

In vivo, the airway epithelium stretches and relaxes with each respiratory cycle, but little is known about the effect this pattern of elongation and relaxation has on bronchial epithelial cells. We have used a model of cell deformation to measure the effect of stretch on inflammatory cytokine release by the BEAS 2B cell line, and to examine the method of mechanotransduction in these cells.

METHODS

BEAS 2B cells were cyclically stretched using the Flexercell system. IL-8 and RANTES protein and RNA levels were measured after different elongations, rates and duration of stretch. An inhibitor of Rho (Ras Homologous)-associated kinases was used, to assess the effect of blocking downstream of integrin signalling. Immunofluorescent staining of paxillin was used to study the effect of stretch on the distribution of focal contacts and the organisation of the actin cytoskeleton.

RESULTS

IL-8 release by BEAS 2B cells was increased by cytokine stimulation and stretch, whereas RANTES levels in the cell supernatant decreased after stretch in a dose-, time- and rate-dependent manner. Thirty percent elongation at 20 cycles/min for 24h increased IL-8 levels by over 100% (P < 0.01). Blocking rho kinase using Y-27632 inhibited the effect of stretch on IL-8 release by the BEAS 2B cells. Immunofluorescent staining demonstrated that stretch caused dramatic disassembly of focal adhesions and resulted in the redistribution of paxillin to the peri-nuclear region.

CONCLUSION

This study demonstrates a marked effect of stretch on bronchial epithelial cell function. We propose that stretch modulates epithelial cell function via the activation of rho kinases. The observation that stretch promotes focal adhesion disassembly suggests a mechanism whereby focal adhesion turnover (coordination of assembly and disassembly) is essential for mechanotransduction in bronchial epithelial cells.

Age-related changes in focal adhesions lead to altered cell behavior in tendon fibroblasts

During aging the increase in collagen cross-linking and total amount of collagen in tendon leads to a decline in both its flexibility and its ability to heal after injury. Fibroblasts are responsible for the synthesis of the macromolecules that constitute tendonous tissue. The ability of fibroblasts to maintain tissue homeostasis is compromised with increasing age underlying many of the age-related pathologies of the musculoskeletal system. This leads to a slowdown in connective tissue healing. Whether these deficits are due to changes in connective tissue, structure or to changes in tendon fibroblast function is unknown. We show that tendon fibroblasts from old mice have an altered morphology, reduced level of function, and exhibit changes in protein transport, compared to fibroblasts from young mice. The fibroblasts from old mice are not senescent, they are distinct phenotypes. Achilles tendon fibroblasts from old mice have low motility and proliferation, a poorly organised actin cytoskeleton and a different localisation of key focal adhesion proteins compared to the same cells from young mice. Additionally we found more of the protein misfolding indicator protein, GADD 153, in fibroblasts from old tendon. These results indicate that changes in tendon fibroblast function may well explain the age-related decline in tendon healing.

Promotion by fibronectin of collagen gel contraction mediated by human corneal fibroblasts

Collagen contraction mediated by corneal fibroblasts (CFs) is implicated in the maintenance of corneal shape. Given that fibronectin is expressed at sites of corneal stromal wounding, we investigated the effect of fibronectin on CF-mediated collagen gel contraction. Human CFs were cultured in a three-dimensional gel of type I collagen in the absence or presence of various extracellular matrix (ECM) components. The contraction of collagen gels mediated by CFs was evaluated by measurement of changes in gel diameter. The formation of stress fibers and focal adhesions in CFs was examined by fluorescence microscopy. The abundance of paxillin, phosphorylated paxillin, integrins alpha5, beta1, and alpha2, and alpha-smooth muscle actin in CFs was examined by immunoblot analysis. Fibronectin promoted CF-mediated collagen gel contraction in a concentration- and time-dependent manner. Other ECM proteins or glycosaminoglycans did not exhibit such an effect. Fibronectin also induced cell spreading, the formation of stress fibers, and the establishment of focal adhesions containing paxillin in CFs cultured in three-dimensional collagen gels. In addition, it increased the amounts of paxillin, phosphorylated paxillin, and integrins alpha5 and beta1 in these cells. The expression of integrin alpha2 and alpha-smooth muscle actin was not affected by fibronectin, however. Furthermore, the peptide GRGDSP (an antagonist of fibronectin receptors) blocked the stimulatory effect of fibronectin on CF-mediated collagen gel contraction. These results suggest that fibronectin promoted CF-mediated collagen gel contraction in a manner dependent on the formation of stress fibers and focal adhesions, the activation of paxillin, and the up-regulation of integrin alpha5beta1. Fibronectin may therefore contribute to the maintenance of corneal shape by CFs during the healing of stromal wounds.

Roles of microfilaments and microtubules in paxillin dynamics

We investigated the roles of microfilaments and microtubules in the localization and tyrosine phosphorylation of paxillin, a focal adhesion-associated signaling molecule, in bovine aortic endothelial cells (BAECs). Paxillin tyrosine phosphorylation is inhibited by cytochalasin D (CD), but slightly increased by colchicine and paclitaxol (taxol). CD also caused an overall disassembly of paxillin-containing focal adhesions (paxillin-FAs) and translocation of paxillin to the cytoplasm and perinuclear region with a diffuse distribution. Meanwhile, colchicine and taxol caused a disassembly of paxillin-FAs from cell periphery and lamellipodia, and their assembly in cell center. These results indicate that actin filaments are important in paxillin assembly in the FAs of the whole ECs and that microtubules are critical in paxillin assembly in cell periphery and lamellipodia; thus the microfilaments and microtubules play differential roles in the dynamics of paxillin assembly/disassembly. Our findings also suggest that tyrosine phosphorylation is an important element in paxillin dynamics at FAs.

Rac1 and RhoA promote neurite outgrowth through formation and stabilization of growth cone point contacts

Growth cone advance depends on coordinated membrane protrusion and adhesion to the extracellular matrix. Although many studies have addressed the mechanisms responsible for membrane protrusion, the assembly of integrin-dependent adhesion sites known as point contacts remains poorly understood in growth cones. We show balanced Rac1 activity controls both leading edge protrusion and point contact dynamics during neurite outgrowth. Immunocytochemistry and live imaging of paxillin-green fluorescent protein (GFP) showed that inhibiting Rac1 blocked point contact formation, whereas Rac1 overactivation produced small, unstable point contacts. Both inhibition and overactivation of Rac1 reduced the persistence of lamellar protrusions and neurite outgrowth. Inhibition of ROCK (Rho kinase), a RhoA effector, perturbed protrusion and point contact dynamics similar to Rac1 overactivation. Moreover, the repulsive guidance cue Semaphorin 3A, which signals through Rac1, destabilizes point contacts. Together, our data suggest that coordinated Rho GTPase activities regulate neurite outgrowth through point contact formation and stabilization of membrane protrusion.

In situ analysis of integrin and growth factor receptor signaling pathways in human glioblastomas suggests overlapping relationships with focal adhesion kinase activation

Deregulated integrin signaling is common in cancers, including glioblastoma. Integrin binding and growth factor receptor signaling activate focal adhesion kinase (FAK) and subsequently up-regulate extracellular regulated kinases (ERK-1/2), leading to cell-cycle progression and cell migration. Most studies of this pathway have used in vitro systems or tumor lysate-based approaches. We examined these pathways primarily in situ using a panel of 30 glioblastomas and gene expression arrays, immunohistochemistry, and fluorescence in situ hybridization, emphasizing the histological distribution of molecular changes. Within individual tumors, increased expression of FAK, p-FAK, paxillin, ERK-1/2, and p-ERK-1/2 occurred in regions of elevated EGFR and/or PDGFRA expression. Moreover, FAK activation levels correlated with EGFR and PDGFRA expression, and p-FAK and EGFR expression co-localized at the single-cell level. In addition, integrin expression was enriched in EGFR/PDGFRA-overexpressing areas but was more regionally confined than FAK, p-FAK, and paxillin. Integrins beta8 and alpha5beta1 were most commonly expressed, often in a perinecrotic or perivascular pattern. Taken together, our data suggest that growth factor receptor overexpression facilitates alterations in the integrin signaling pathway. Thus, FAK may act in glioblastoma as a downstream target of growth factor signaling, with integrins enhancing the impact of such signaling in the tumor microenvironment.