Tumor growth and angiogenesis is impaired in CIB1 knockout mice

Deubiquitination of CIB1 by USP14 promotes lenvatinib resistance via the PAK1-ERK1/2 axis in hepatocellular carcinoma

Background: Lenvatinib is the most common multitarget receptor tyrosine kinase inhibitor for the treatment of advanced hepatocellular carcinoma (HCC). Acquired resistance to lenvatinib is one of the major factors leading to the failure of HCC treatment, but the underlying mechanism has not been fully characterized. Methods: We established lenvatinib-resistant cell lines, cell-derived xenografts (CDXs) and patient-derived xenografts (PDXs) and obtained lenvatinib-resistant HCC tumor tissues for further study. Results: We found that ubiquitin-specific protease 14 (USP14) was significantly increased in lenvatinib-resistant HCC cells and tumors. Silencing USP14 significantly attenuated lenvatinib resistance in vitro and in vivo. Mechanistically, USP14 directly interacts with and stabilizes calcium- and integrin-binding protein 1 (CIB1) by reversing K48-linked proteolytic ubiquitination at K24, thus facilitating the P21-activated kinase 1 (PAK1)-ERK1/2 signaling axis. Moreover, in vivo adeno-associated virus 9 mediated transduction of CIB1 promoted lenvatinib resistance in PDXs, whereas CIB1 knockdown resensitized the response of PDXs to lenvatinib. Conclusions: These findings provide new insights into the role of CIB1/PAK1-ERK1/2 signaling in lenvatinib resistance in HCC. Targeting CIB1 and its pathways may be a novel pharmaceutical intervention for the treatment of lenvatinib-resistant HCC.

Role of calcium integrin-binding protein 1 in the mechanobiology of the liver endothelium

Liver sinusoidal endothelial cells (LSECs) dysfunction is a key process in the development of chronic liver disease (CLD). Progressive scarring increases liver stiffness in a winch-like loop stimulating a dysfunctional liver cell phenotype. Cellular stretching is supported by biomechanically modulated molecular factors (BMMFs) that can translocate into the cytoplasm to support mechanotransduction through cytoskeleton remodeling and gene transcription. Currently, the molecular mechanisms of stiffness-induced LSECs dysfunction remain largely unclear. Here we propose calcium- and integrin-binding protein 1 (CIB1) as BMMF with crucial role in LSECs mechanobiology in CLD. CIB1 expression and translocation was characterized in healthy and cirrhotic human livers and in LSECs cultured on polyacrylamide gels with healthy and cirrhotic-like stiffnesses. Following the modulation of CIB1 with siRNA, the transcriptome was scrutinized to understand downstream effects of CIB1 downregulation. CIB1 expression is increased in LSECs in human cirrhosis. In vitro, CIB1 emerges as an endothelial BMMF. In human umbilical vein endothelial cells and LSECs, CIB1 expression and localization are modulated by stiffness-induced trafficking across the nuclear membrane. LSECs from cirrhotic liver tissue both in animal model and human disease exhibit an increased amount of CIB1 in cytoplasm. Knockdown of CIB1 in LSECs exposed to high stiffness improves LSECs phenotype by regulating the intracellular tension as well as the inflammatory response. Our results demonstrate that CIB1 is a key factor in sustaining cellular tension and stretching in response to high stiffness. CIB1 downregulation ameliorates LSECs dysfunction, enhancing their redifferentiation, and reducing the inflammatory response.

Integrative public data-mining pipeline for the validation of novel independent prognostic biomarkers for lung adenocarcinoma

Aim: We aimed to develop a candidate-based integrative public data mining strategy for validation of novel prognostic markers in lung adenocarcinoma. Materials & methods: An in silico approach integrating meta-analyses of publicly available clinical information linked RNA expression, gene copy number and mutation datasets combined with independent immunohistochemistry and survival datasets. Results: After validation of pipeline integrity utilizing data from the well-characterized prognostic factor Ki-67, prognostic impact of the calcium- and integrin-binding protein, CIB1, was analyzed. CIB1 was overexpressed in lung adenocarcinoma which correlated with pathological tumor and pathological lymph node status and impaired overall/progression-free survival. In multivariate analyses, CIB1 emerged as UICC stage-independent risk factor for impaired survival. Conclusion: Our pipeline holds promise to facilitate further identification and validation of novel lung cancer-associated prognostic markers.

Characterization of the role of Samsn1 loss in multiple myeloma development

The protein SAMSN1 was recently identified as a putative tumor suppressor in multiple myeloma, with re-expression of Samsn1 in the 5TGM1/KaLwRij murine model of myeloma leading to a near complete abrogation of intramedullary tumor growth. Here, we sought to clarify the mechanism underlying this finding. Intratibial administration of 5TGM1 myeloma cells into KaLwRij mice revealed that Samsn1 had no effect on primary tumor growth, but that its expression significantly inhibited the metastasis of these primary tumors. Notably, neither in vitro nor in vivo migration was affected by Samsn1 expression. Both knocking-out SAMSN1 in the RPMI-8226 and JJN3 human myeloma cell lines, and retrovirally expressing SAMSN1 in the LP-1 and OPM2 human myeloma cell lines had no effect on either cell proliferation or migration in vitro. Altering SAMSN1 expression in these human myeloma cells did not affect the capacity of the cells to establish either primary or metastatic intramedullary tumors when administered intratibially into immune deficient NSG mice. Unexpectedly, the tumor suppressive and anti-metastatic activity of Samsn1 in 5TGM1 cells were not evidenced following cell administration either intratibially or intravenously to NSG mice. Crucially, the growth of Samsn1-expressing 5TGM1 cells was limited in C57BL/6/Samsn1-/- mice but not in C57BL/6 Samsn1+/+ mice. We conclude that the reported potent in vivo tumor suppressor activity of Samsn1 can be attributed, in large part, to graft-rejection from Samsn1-/- recipient mice. This has broad implications for the design and interpretation of experiments that utilize cancer cells and knockout mice that are mismatched for expression of specific proteins.

A gene therapeutic approach to inhibit calcium and integrin binding protein 1 ameliorates maladaptive remodelling in pressure overload

Aims

Chronic heart failure is becoming increasingly prevalent and is still associated with a high mortality rate. Myocardial hypertrophy and fibrosis drive cardiac remodelling and heart failure, but they are not sufficiently inhibited by current treatment strategies. Furthermore, despite increasing knowledge on cardiomyocyte intracellular signalling proteins inducing pathological hypertrophy, therapeutic approaches to target these molecules are currently unavailable. In this study, we aimed to establish and test a therapeutic tool to counteract the 22 kDa calcium and integrin binding protein (CIB) 1, which we have previously identified as nodal regulator of pathological cardiac hypertrophy and as activator of the maladaptive calcineurin/NFAT axis.

Methods and results

Among three different sequences, we selected a shRNA construct (shCIB1) to specifically down-regulate CIB1 by 50% upon adenoviral overexpression in neonatal rat cardiomyocytes (NRCM), and upon overexpression by an adeno-associated-virus (AAV) 9 vector in mouse hearts. Overexpression of shCIB1 in NRCM markedly reduced cellular growth, improved contractility of bioartificial cardiac tissue and reduced calcineurin/NFAT activation in response to hypertrophic stimulation. In mice, administration of AAV-shCIB1 strongly ameliorated eccentric cardiac hypertrophy and cardiac dysfunction during 2 weeks of pressure overload by transverse aortic constriction (TAC). Ultrastructural and molecular analyses revealed markedly reduced myocardial fibrosis, inhibition of hypertrophy associated gene expression and calcineurin/NFAT as well as ERK MAP kinase activation after TAC in AAV-shCIB1 vs. AAV-shControl treated mice. During long-term exposure to pressure overload for 10 weeks, AAV-shCIB1 treatment maintained its anti-hypertrophic and anti-fibrotic effects, but cardiac function was no longer improved vs. AAV-shControl treatment, most likely resulting from a reduction in myocardial angiogenesis upon downregulation of CIB1.

Conclusions

Inhibition of CIB1 by a shRNA-mediated gene therapy potently inhibits pathological cardiac hypertrophy and fibrosis during pressure overload. While cardiac function is initially improved by shCIB1, this cannot be kept up during persisting overload.

Proteomic identification of moesin upon exposure to acrolein

Background

Acrolein (allyl Aldehyde) as one of smoke irritant exacerbates chronic airway diseases and increased in sputum of patients with asthma and chronic obstructive lung disease. But underlying mechanism remains unresolved. The aim of study was to identify protein expression in human lung microvascular endothelial cells (HMVEC-L) exposed to acrolein.

Methods

A proteomic approach was used to determine the different expression of proteins at 8 h and 24 h after treatment of acrolein 30 nM and 300 nM to HMVEC-L. Treatment of HMVEC-L with acrolein 30 nM and 300 nM altered 21 protein spots on the two-dimensional gel, and these were then analyzed by MALDI-TOF MS.

Results

These proteins included antioxidant, signal transduction, cytoskeleton, protein transduction, catalytic reduction. The proteins were classified into four groups according to the time course of their expression patterns such as continually increasing, transient increasing, transient decreasing, and continually decreasing. For validation immunohistochemical staining and Western blotting was performed on lung tissues from acrolein exposed mice. Moesin was expressed in endothelium, epithelium, and inflammatory cells and increased in lung tissues of acrolein exposed mice compared with sham treated mice.

Conclusions

These results indicate that some of proteins may be an important role for airway disease exacerbation caused by acrolein exposure.

Electronic supplementary material

The online version of this article (10.1186/s12953-017-0130-4) contains supplementary material, which is available to authorized users.

Loss of CIB2 Causes Profound Hearing Loss and Abolishes Mechanoelectrical Transduction in Mice

Calcium and integrin-binding protein 2 (CIB2) belongs to a protein family with four known members, CIB1 through CIB4, which are characterized by multiple calcium-binding EF-hand domains. Among the family members, the Cib1 and Cib2 genes are expressed in mouse cochlear hair cells, and mutations in the human CIB2 gene have been associated with nonsyndromic deafness DFNB48 and syndromic deafness USH1J. To further explore the function of CIB1 and CIB2 in hearing, we established Cib1 and Cib2 knockout mice using the clustered regularly interspaced short palindromic repeat (CRISPR)-associated Cas9 nuclease (CRISPR/Cas9) genome editing technique. We found that loss of CIB1 protein does not affect auditory function, whereas loss of CIB2 protein causes profound hearing loss in mice. Further investigation revealed that hair cell stereocilia development is affected in Cib2 knockout mice. Noticeably, loss of CIB2 abolishes mechanoelectrical transduction (MET) currents in auditory hair cells. In conclusion, we show here that although both CIB1 and CIB2 are readily detected in the cochlea, only loss of CIB2 results in profound hearing loss, and that CIB2 is essential for auditory hair cell MET.

CIB2 interacts with TMC1 and TMC2 and is essential for mechanotransduction in auditory hair cells

Inner ear hair cells detect sound through deflection of stereocilia, the microvilli-like projections that are arranged in rows of graded heights. Calcium and integrin-binding protein 2 is essential for hearing and localizes to stereocilia, but its exact function is unknown. Here, we have characterized two mutant mouse lines, one lacking calcium and integrin-binding protein 2 and one carrying a human deafness-related Cib2 mutation, and show that both are deaf and exhibit no mechanotransduction in auditory hair cells, despite the presence of tip links that gate the mechanotransducer channels. In addition, mechanotransducing shorter row stereocilia overgrow in hair cell bundles of both Cib2 mutants. Furthermore, we report that calcium and integrin-binding protein 2 binds to the components of the hair cell mechanotransduction complex, TMC1 and TMC2, and these interactions are disrupted by deafness-causing Cib2 mutations. We conclude that calcium and integrin-binding protein 2 is required for normal operation of the mechanotransducer channels and is involved in limiting the growth of transducing stereocilia.

Inner ear hair cells detect sound through deflection of stereocilia that harbor mechanically-gated channels. Here the authors show that protein responsible for Usher syndrome, CIB2, interacts with these channels and is essential for their function and hearing in mice.

CIB1 contributes to oncogenic signalling by Ras via modulating the subcellular localisation of sphingosine kinase 1

CIB1 (calcium and integrin binding protein 1) is a small intracellular protein with numerous interacting partners, and hence has been implicated in various cellular functions. Recent studies have revealed emerging roles of CIB1 in regulating cancer cell survival and angiogenesis, although the mechanisms involved have remained largely undefined. In investigating the oncogenic function of CIB1, we initially found that CIB1 is widely up-regulated across a diverse range of cancers, with this up-regulation frequently correlating with oncogenic mutations of KRas. Consistent with this, we found that ectopic expression of oncogenic KRas and HRas in cells resulted in elevated CIB1 expression. We previously described the Ca²⁺-myristoyl switch function of CIB1, and its ability to facilitate agonist-induced plasma membrane localisation of sphingosine kinase 1 (SK1), a location where SK1 is known to elicit oncogenic signalling. Thus, we examined the role this may play in oncogenesis. Consistent with these findings, we demonstrated here that over-expression of CIB1 by itself is sufficient to drive localisation of SK1 to the plasma membrane and enhance the membrane associated enzymatic activity of SK1, as well as its oncogenic signalling. We subsequently demonstrated that elevated levels of CIB1 resulted in full neoplastic transformation, in a manner dependent on SK1. In agreement with our previous findings that SK1 is a downstream mediator of oncogenic signalling by Ras, we found that targeting CIB1 also inhibited neoplastic growth of cells induced by oncogenic Ras, suggesting an important pro-tumorigenic role for CIB1. Thus, we have demonstrated for the first time a role for CIB1 in neoplastic transformation, and revealed a novel mechanism facilitating oncogenic signalling by Ras and SK1.

CIB1: a small protein with big ambitions

Calcium- and integrin-binding protein 1 (CIB1) is a small, ubiquitously expressed protein that was first identified as an intracellular binding partner of a platelet-specific α-integrin cytoplasmic tail. Although early studies revealed a role for CIB1 in regulating platelet integrin activity, recent studies have indicated a more diverse role for CIB1 in many different cell types and processes, including calcium signaling, migration, adhesion, proliferation, and survival. Increasing evidence also points to a novel role for CIB1 in cancer and cardiovascular disease. In addition, an array of CIB1 binding partners has been identified that provide important insight into how CIB1 may regulate these processes. Some of these binding partners include the serine/threonine kinases, p21-activated kinase 1 (PAK1), apoptosis signal-regulating kinase 1 (ASK1), and polo-like kinase 3 (PLK3). Structural and mutational studies indicate that CIB1 binds most or all of its partners via a well-defined hydrophobic cleft. Although CIB1 itself lacks known enzymatic activity, it supports the PI3K/AKT and MEK/ERK oncogenic signaling pathways, in part, by directly modulating enzymes in these pathways. In this review, we discuss our current understanding of CIB1 and key questions regarding structure and function and how this seemingly diminutive protein impacts important signaling pathways and cellular processes in human health and disease.-Leisner, T. M., Freeman, T. C., Black, J. L., Parise, L. V. CIB1: a small protein with big ambitions.

Combined effect of insulin-like growth factor-1 and CC chemokine ligand 2 on angiogenic events in endothelial cells

Therapeutic angiogenesis may be applied in medical conditions to promote stimulation of angiogenesis. Angiogenesis is a multistep process, which includes endothelial cell proliferation, migration, and tube formation, which is mediated by various angiogenic polypeptides. Thus, studies that elucidate the cellular mechanisms involved in these processes are necessary to develop novel therapeutic strategies. This study investigated the in vitro effects of the pro-angiogenic factors, insulin-like growth factor-1 (IGF-1) and/or chemokine (CC motif) ligand 2 (CCL2), on endothelial cells. Flow cytometry analysis showed that IGF-1 and CCL2 treatment did not interfere with IGF-1 receptor (IGF-1R) expression, but CCL2 treatment increased CCL2 receptor (CCR2) expression. Immunofluorescence analysis revealed that the IGF-1/CCL2 combination induced a greater increase in fibronectin deposition, but the treatments did not alter the expression of the fibronectin receptors, CD49e and CD44. The interaction of fibronectin with cytokines demonstrated that IGF-1/CCL2 promoted changes in intermediate F-actin remodeling that may result in increased endothelial cell adhesion and cell migration mediated by fibronectin. Furthermore, IGF-1/CCL2 stimulated endothelial cells, grown on fibronectin, to form capillary-like structures and intercellular lumina with greater luminal area. These data suggest that IGF-1/CCL2 combination and a fibronectin matrix may contribute to the angiogenesis process to stimulate adhesion, migration, and tube formation by endothelial cells as a result of F-actin remodeling.

Potential compensation among group I PAK members in hindlimb ischemia and wound healing

PAKs are serine/threonine kinases that regulate cytoskeletal dynamics and cell migration. PAK1 is activated by binding to the small EF hand protein, CIB1, or to the Rho GTPases Rac1 or Cdc42. The role of PAK1 in angiogenesis was established based only on in vitro studies and its role in angiogenesis in vivo has never been examined. Here we tested the hypothesis that PAK1 is an essential regulator of ischemic neovascularization (arteriogenesis and angiogenesis) and wound healing using a global PAK1 knockout mouse. Neovascularization was assessed using unilateral hindlimb ischemia. We found that plantar perfusion, limb use and appearance were not significantly different between 6-8 week old PAK1-/- and PAK1+/+ mice throughout the 21-day period following hindlimb ischemia; however a slightly delayed healing was observed in 16 week old PAK1-/- mice. In addition, the wound healing rate, as assessed with an ear punch assay, was unchanged in PAK1-/- mice. Surprisingly, however, we observed a notable increase in PAK2 expression and phosphorylation in ischemic gastrocnemius tissue from PAK1-/- but not PAK1+/+ mice. Furthermore, we observed higher levels of activated ERK2, but not AKT, in ischemic and non-ischemic muscle of PAK1-/- mice upon hindlimb ischemic injury. A group I PAK inhibitor, IPA3, significantly inhibited endothelial cell sprouting from aortic rings in both PAK1-/- and PAK1+/+ mice, implying that PAK2 is a potential contributor to this process. Taken together, our data indicate that while PAK1 has the potential to contribute to neovascularization and wound healing, PAK2 may functionally compensate when PAK1 is deficient.

Identification of novel integrin binding partners for calcium and integrin binding protein 1 (CIB1): structural and thermodynamic basis of CIB1 promiscuity

The short cytoplasmic tails of the α- and β-chains of integrin adhesion receptors regulate integrin activation and cell signaling. Significantly less is known about proteins that bind to α-integrin cytoplasmic tails (CTs) as opposed to β-CTs to regulate integrins. Calcium and integrin binding protein 1 (CIB1) was previously identified as an αIIb binding partner that inhibits agonist-induced activation of the platelet-specific integrin, αIIbβ3. A sequence alignment of all α-integrin CTs revealed that key residues in the CIB1 binding site of αIIb are well-conserved, and was used to delineate a consensus binding site (I/L-x-x-x-L/M-W/Y-K-x-G-F-F). Because the CIB1 binding site of αIIb is conserved in all α-integrins and CIB1 expression is ubiquitous, we asked if CIB1 could interact with other α-integrin CTs. We predicted that multiple α-integrin CTs were capable of binding to the same hydrophobic binding pocket on CIB1 with docking models generated by all-atom replica exchange discrete molecular dynamics. After demonstrating novel in vivo interactions between CIB1 and other whole integrin complexes with co-immunoprecipitations, we validated the modeled predictions with solid-phase competitive binding assays, which showed that other α-integrin CTs compete with the αIIb CT for binding to CIB1 in vitro. Isothermal titration calorimetry measurements indicated that this binding is driven by hydrophobic interactions and depends on residues in the CIB1 consensus binding site. These new mechanistic details of CIB1-integrin binding imply that CIB1 could bind to all integrin complexes and act as a broad regulator of integrin function.

CIB1 prevents nuclear GAPDH accumulation and non-apoptotic tumor cell death via AKT and ERK signaling

CIB1 is a 22-kDa regulatory protein previously implicated in cell survival and proliferation. However, the mechanism by which CIB1 regulates these processes is poorly defined. Here we report that CIB1 depletion in SK-N-SH neuroblastoma and MDA-MB-468 breast cancer cells promotes non-apoptotic, caspase-independent cell death that is not initiated by increased outer mitochondrial membrane permeability or translocation of apoptosis-inducing factor to the nucleus. Instead, cell death requires nuclear GAPDH accumulation. Furthermore, CIB1 depletion disrupts two commonly dysregulated, oncogenic pathways– PI3K/AKT and Ras/MEK/ERK, resulting in a synergistic mechanism of cell death, which was mimicked by simultaneous pharmacological inhibition of both pathways, but not either pathway alone. In defining each pathway’s contributions, we found that AKT inhibition alone maximally induced GAPDH nuclear accumulation, whereas MEK/ERK inhibition alone had no effect on GAPDH localization. Concurrent GAPDH nuclear accumulation and ERK inhibition were required however, to induce a significant DNA damage response, which was critical to subsequent cell death. Collectively, our results indicate that CIB1 is uniquely positioned to regulate PI3K/AKT and MEK/ERK signaling and that simultaneous disruption of these pathways synergistically induces a nuclear GAPDH-dependent cell death. The mechanistic insights into cell death induced by CIB1 interference suggest novel molecular targets for cancer therapy.

Proteomic identification of CIB1 as a potential diagnostic factor in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), among the most common malignancies worldwide, remains a major threat to public health, and there is an urgent need to identify novel biomarkers for diagnosis, prognosis and targets for anti-cancer treatment. In this study, two-dimensional polyacrylamide gel electrophoresis coupled with ESI-Q-TOF MS/MS analysis was used to identify differentially expressed proteins among the HCC tumour centre, tumour margin and nontumourous liver tissues. In total, 52 spots with significant alteration were positively identified byMS/MSanalysis. Altered expression of representative proteins, including CIB1, was validated by Western blotting. Immunostaining suggested an increase tendency of CIB1 expression from nontumourous liver tissue to tumour centre. Knockdown of CIB1 expression by RNA interference led to the significant suppression of the cell growth in hepatoma HepG2 cells. These data suggest that CIB1 may be used as a novel prognostic factor and possibly an attractive therapeutic target for HCC.

Heme oxygenase 1 (HO-1) challenges the angiogenic switch in prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer-associated death in men. Once a tumor is established it may attain further characteristics via mutations or hypoxia, which stimulate new blood vessels. Angiogenesis is a hallmark in the pathogenesis of cancer and inflammatory diseases that may predispose to cancer. Heme oxygenase-1 (HO-1) counteracts oxidative and inflammatory damage and was previously reported to play a key role in prostate carcinogenesis. To gain insight into the anti-tumoral properties of HO-1, we investigated its capability to modulate PCa associated-angiogenesis. In the present study, we identified in PC3 cells a set of inflammatory and pro-angiogenic genes down-regulated in response to HO-1 overexpression, in particular VEGFA, VEGFC, HIF1α and α5β1 integrin. Our results indicated that HO-1 counteracts oxidative imbalance reducing ROS levels. An in vivo angiogenic assay showed that intradermal inoculation of PC3 cells stable transfected with HO-1 (PC3HO-1) generated tumours less vascularised than controls, with decreased microvessel density and reduced CD34 and MMP9 positive staining. Interestingly, longer term grown PC3HO-1 xenografts displayed reduced neovascularization with the subsequent down-regulation of VEGFR2 expression. Additionally, HO-1 repressed nuclear factor κB (NF-κB)-mediated transcription from an NF-κB responsive luciferase reporter construct, which strongly suggests that HO-1 may regulate angiogenesis through this pathway. Taken together, these data supports a key role of HO-1 as a modulator of the angiogenic switch in prostate carcinogenesis ascertaining it as a logical target for intervention therapy.