Models of crk adaptor proteins in cancer

Integrative Multi-OMICs Identifies Therapeutic Response Biomarkers and Confirms Fidelity of Clinically Annotated, Serially Passaged Patient-Derived Xenografts Established from Primary and Metastatic Pediatric and AYA Solid Tumors

Establishment of clinically annotated, molecularly characterized, patient-derived xenografts (PDXs) from treatment-naïve and pretreated patients provides a platform to test precision genomics-guided therapies. An integrated multi-OMICS pipeline was developed to identify cancer-associated pathways and evaluate stability of molecular signatures in a panel of pediatric and AYA PDXs following serial passaging in mice. Original solid tumor samples and their corresponding PDXs were evaluated by whole-genome sequencing, RNA-seq, immunoblotting, pathway enrichment analyses, and the drug−gene interaction database to identify as well as cross-validate actionable targets in patients with sarcomas or Wilms tumors. While some divergence between original tumor and the respective PDX was evident, majority of alterations were not functionally impactful, and oncogenic pathway activation was maintained following serial passaging. CDK4/6 and BETs were prioritized as biomarkers of therapeutic response in osteosarcoma PDXs with pertinent molecular signatures. Inhibition of CDK4/6 or BETs decreased osteosarcoma PDX growth (two-way ANOVA, p < 0.05) confirming mechanistic involvement in growth. Linking patient treatment history with molecular and efficacy data in PDX will provide a strong rationale for targeted therapy and improve our understanding of which therapy is most beneficial in patients at diagnosis and in those already exposed to therapy.

Silencing of the CrkL gene reverses the doxorubicin resistance of K562/ADR cells through regulating PI3K/Akt/MRP1 signaling

BACKGROUND

Doxorubicin is a first-line chemotherapy agent on human myelogenous leukemia clinical treatment, but the development of chemoresistance has largely limited curative effect. In this study, we aimed to evaluate the biological function and molecular mechanisms of CrkL to Doxorubicin resistance.

METHODS

Quantitative reverse transcription-PCR (qRT-PCR) assay was performed to examine the expression of CrkL in K562 and K562/ADR cells. The expression of CrkL was silenced through RNA interference technology. MTT assay and flow cytometry were performed to detect the proliferation inhibition and apoptosis rate after CrkL siRNA transfection. The protein expression changes of PI3K/AKT/MRP1 pathway induced by CrkL siRNA were observed by Western Blot assay. Xenograft tumor model was carried out to observe tumor growth in vivo.

RESULTS

We observed that silencing of CrkL could effectively increase apoptosis rate induced by doxorubicin and dramatically reversed doxorubicin resistance in K562/ADR cells. Further studies revealed knockdown CrkL expression suppressed PI3K/Akt/MRP1 signaling, which indicated CrkL siRNA reversed doxorubicin effect through regulating PI3K/Akt/MRP1 pathway. In addition, overexpression of MRP1 could evidently reduce apoptosis rate and reversed the inhibitory effects of doxorubicin resistance caused by CrkL siRNA on K562/ADR cells. Finally, in vivo experiments revealed that CrkL silencing acted a tumor-suppressing role in myelogenous leukemia via regulating PI3K/Akt/MRP1 signaling.

CONCLUSION

Together, we indicated that CrkL is up-regulated in myelogenous leukemia cells and silencing of CrkL could reverse Doxorubicin resistance effectively. These results show a potential novel strategy for intervention chemoresistance in myelogenous leukemia during chemotherapy.

Epigenetic Silencing of MicroRNA-126 Promotes Cell Growth in Marek's Disease

During latency, herpesvirus infection results in the establishment of a dormant state in which a restricted set of viral genes are expressed. Together with alterations of the viral genome, several host genes undergo epigenetic silencing during latency. These epigenetic dysregulations of cellular genes might be involved in the development of cancer. In this context, Gallid alphaherpesvirus 2 (GaHV-2), causing Marek’s disease (MD) in susceptible chicken, was shown to impair the expression of several cellular microRNAs (miRNAs). We decided to focus on gga-miR-126, a host miRNA considered a tumor suppressor through signaling pathways controlling cell proliferation. Our objectives were to analyze the cause and the impact of miR-126 silencing during GaHV-2 infection. This cellular miRNA was found to be repressed at crucial steps of the viral infection. In order to determine whether miR-126 low expression level was associated with specific epigenetic signatures, DNA methylation patterns were established in the miR-126 gene promoter. Repression was associated with hypermethylation at a CpG island located in the miR-126 host gene epidermal growth factor like-7 (EGFL-7). A strategy was developed to conditionally overexpress miR-126 and control miRNAs in transformed CD4+ T cells propagated from Marek’s disease (MD) lymphoma. This functional assay showed that miR-126 restoration specifically diminishes cell proliferation. We identified CT10 regulator of kinase (CRK), an adaptor protein dysregulated in several human malignancies, as a candidate target gene. Indeed, CRK protein levels were markedly reduced by the miR-126 restoration.

Crk and CrkL as Therapeutic Targets for Cancer Treatment

Crk and CrkL are cellular counterparts of the viral oncoprotein v-Crk. Crk and CrkL are overexpressed in many types of human cancer, correlating with poor prognosis. Furthermore, gene knockdown and knockout of Crk and CrkL in tumor cell lines suppress tumor cell functions, including cell proliferation, transformation, migration, invasion, epithelial-mesenchymal transition, resistance to chemotherapy drugs, and in vivo tumor growth and metastasis. Conversely, overexpression of tumor cells with Crk or CrkL enhances tumor cell functions. Therefore, Crk and CrkL have been proposed as therapeutic targets for cancer treatment. However, it is unclear whether Crk and CrkL make distinct or overlapping contributions to tumor cell functions in various cancer types because Crk or CrkL have been examined independently in most studies. Two recent studies using colorectal cancer and glioblastoma cells clearly demonstrated that Crk and CrkL need to be ablated individually and combined to understand distinct and overlapping roles of the two proteins in cancer. A comprehensive understanding of individual and overlapping roles of Crk and CrkL in tumor cell functions is necessary to develop effective therapeutic strategies. This review systematically discusses crucial functions of Crk and CrkL in tumor cell functions and provides new perspectives on targeting Crk and CrkL in cancer therapy.

CRKL promotes hepatocarcinoma through enhancing glucose metabolism of cancer cells via activating PI3K/Akt

Abnormal glucose metabolism may contribute to cancer progression. As a member of the CRK (v-crk sarcoma virus CT10 oncogene homologue) adapter protein family, CRKL (CRK-like) associated with the development and progression of various tumours. However, the exact role and underlying mechanism of CRKL on energy metabolism remain unknown. In this study, we investigated the effect of CRKL on glucose metabolism of hepatocarcinoma cells. CRKL and PI3K were found to be overexpressed in both hepatocarcinoma cells and tissues; meanwhile, CRKL up-regulation was positively correlated with PI3K up-regulation. Functional investigations revealed that CRKL overexpression promoted glucose uptake, lactate production and glycogen synthesis of hepatocarcinoma cells by up-regulating glucose transporters 1 (GLUT1), hexokinase II (HKII) expression and down-regulating glycogen synthase kinase 3β (GSK3β) expression. Mechanistically, CRKL promoted glucose metabolism of hepatocarcinoma cells via enhancing the CRKL-PI3K/Akt-GLUT1/HKII-glucose uptake, CRKL-PI3K/Akt-HKII-glucose-lactate production and CRKL-PI3K/Akt-Gsk3β-glycogen synthesis. We demonstrate CRKL facilitates HCC malignancy via enhancing glucose uptake, lactate production and glycogen synthesis through PI3K/Akt pathway. It provides interesting fundamental clues to CRKL-related carcinogenesis through glucose metabolism and offers novel therapeutic strategies for hepatocarcinoma.

miR-124-3p Suppresses the Invasiveness and Metastasis of Hepatocarcinoma Cells via Targeting CRKL

Abnormal expressions of microRNAs are involved in growth and progression of human cancers including hepatocellular carcinoma (HCC). An adaptor protein CRKL plays a pivotal role in HCC growth, whereas miR-124-3p downregulation is associated with clinical stage and the poor survival of patients. However, the relationship between miR-124-3p and CRKL and the molecular mechanisms through which they regulate HCC metastasis remains unclear. In the current work, we explored miR-124-3p and its correlation with CRKL expression in HCC patient tissues. We found that miR-124-3p deficiency is inversely co-related with CRKL overexpression in tumorous tissues of HCC patients, which was also consistent in HCCLM3 and Huh7 HCC cell lines. Target validation data shows that miR-124-3p directly targets CRKL. The overexpression of miR-124-3p reverses the CRKL expression at both mRNA and protein levels and inhibits the cell development, migration, and invasion. Mechanistic investigations showed that CRKL downregulation suppresses the ERK pathway and EMT process, and concomitant decrease in invasion and metastasis of HCC cells. The expressions of key molecules in the ERK pathway such as RAF, MEK, ERK1/2, and pERK1/2 and key promoters of EMT such as N-cadherin and vimentin were downregulated, whereas E-cadherin, a key suppression indicator of EMT, was upregulated. MiR-124-3p-mediated CRKL suppression led to BAX/BCL-2 increase and C-JUN downregulation, which inhibited the cell proliferation and promoted the apoptosis in HCC cells. Collectively, our data illustrates that miR-124-3p acts as an important tumor-suppressive miRNA to suppress HCC carcinogenesis through targeting CRKL. The miR-124-3p-CRKL axial regulated pathway may offer valuable indications for cancer research, diagnosis, and treatment.

microRNA-132 inhibits the proliferation, migration, and invasion of ovarian cancer cells by regulating CT10 oncogenic gene homolog II-related signaling pathways

BACKGROUND

Despite a large amount of evidence showing the involvement of microRNA-132 (miR-132) in the occurrence and prognosis of many different types of cancer, the role of miR-132 in ovarian cancer and its potential molecular mechanism have yet to be fully explained.

METHOD

We studied the biological function and molecular mechanism of miR-132 in ovarian cancer cell lines and clinical tissue samples using quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot, Luciferase reporter assay, CCK8 test, colony formation test, and scratch and Transwell assays.

RESULTS

The expression level of miR-132 was significantly reduced in ovarian cancer cell lines and clinical tissue samples. When the level of miR-132 was increased, the proliferation, colony-forming, migration, and invasion abilities of ovarian cancer cells were significantly inhibited. We found that miR-132 inhibits the expression of transcription factor CT10 Oncogenic Gene Homologue II (CRKII) through specific targeting of mRNA 3'-UTR. We also observed a significant increase in CRKII expression in ovarian cancer. Notably, CRKII expression was negatively correlated with miR-132 expression in clinical ovarian cancer tissue. Down-regulation of CRKII had a similar inhibitory effect on miR-132 overexpression in ovarian cancer cells, while excessive expression of CRKII reversed the inhibitory effect mediated by the excessive expression of miR-132.

CONCLUSIONS

miR-132 inhibits the proliferation, invasion, and migration abilities of ovarian cancer cells through targeting CRKII.

Novel role for CRK adaptor proteins as essential components of SRC/FAK signaling for epithelial-mesenchymal transition and colorectal cancer aggressiveness

Epithelial-mesenchymal transition (EMT) is a cell plasticity process required for metastasis and chemoresistance of carcinoma cells. We report a crucial role of the signal adaptor proteins CRK and CRKL in promoting EMT and tumor aggressiveness, as well as resistance against chemotherapy in colorectal and pancreatic carcinoma. Genetic loss of either CRKL or CRK partially counteracted EMT in three independent cancer cell lines. Strikingly, complete loss of the CRK family shifted cells strongly toward the epithelial phenotype. Cells exhibited greatly increased E-cadherin and grew as large, densely packed clusters, completely lacked invasiveness and the ability to undergo EMT induced by cytokines or genetic activation of SRC. Furthermore, CRK family-deficiency significantly reduced cell survival, proliferation and chemoresistance, as well as ERK1/2 phosphorylation and c-MYC protein levels. In accordance, MYC-target gene expression was identified as novel hallmark process positively regulated by CRK family proteins. Mechanistically, CRK proteins were identified as pivotal amplifiers of SRC/FAK signaling at focal adhesions, mediated through a novel positive feedback loop depending on RAP1. Expression of the CRK family and the EMT regulator ZEB1 was significantly correlated in samples from colorectal cancer patients, especially in invasive regions. Further, high expression of CRK family genes was significantly associated with reduced survival in locally advanced colorectal cancer, as well as in pan-cancer datasets from the TCGA project. Thus, CRK family adaptor proteins are promising therapeutic targets to counteract EMT, chemoresistance, metastasis formation and minimal residual disease. As proof of concept, CRK family-mediated oncogenic signaling was successfully inhibited by a peptide-based inhibitor.

Secretome profiling of PC3/nKR cells, a novel highly migrating prostate cancer subline derived from PC3 cells

Prostate cancer (PCa) is the most common cancer among men worldwide. Most PCa cases are not fatal; however, the outlook is poor when PCa spreads to another organ. Bone is the target organ in about 80% of patients who experience metastasis from a primary PCa tumor. In the present study, we characterized the secretome of PC3/nKR cells, which are a new subline of PC3 cells that were originally isolated from nude mice that were implanted with PC3 cells without anti-natural killer (NK) cell treatment. Wound healing and Transwell assays revealed that PC3/nKR cells had increased migratory and invasive activities in addition to a higher resistance to NK cells-induced cytotoxicity as compared to PC3 cells. We quantitatively profiled the secreted proteins of PC3/nKR and PC3 cells by liquid chromatography-tandem mass spectrometry analysis coupled with 2-plex tandem mass tag labeling. In total, 598 secretory proteins were identified, and 561 proteins were quantified, among which 45 proteins were secreted more and 40 proteins were secreted less by PC3/nKR cells than by PC3 cells. For validation, the adapter molecule crk, serpin B3, and cystatin-M were analyzed by western blotting. PC3/nKR cells showed the selective secretion of NKG2D ligand 2, HLA-A, and IL-6, which may contribute to their NK cell-mediated cytotoxicity resistance, and had a high secretion of crk protein, which may contribute to their high migration and invasion properties. Based on our secretome analysis, we propose that PC3/nKR cells represent a new cell system for studying the metastasis and progression of PCa.

ACAP4 interacts with CrkII to promote the recycling of integrin β1

ACAP4, a GTPase-activating protein (GAP) for the ADP-ribosylation factor 6 (ARF6), plays import roles in cell migration, cell polarity, vesicle trafficking and tumorigenesis. Similarly, the ubiquitously expressed adaptor protein CrkII functions in a wide range of cellular activities, including cell proliferation, T cell adhesion and activation, tumorigenesis, and bacterial pathogenesis. Here, we demonstrate that ACAP4 physically interacts with CrkII. Biochemical experiments revealed that ACAP4^550-660 and the SH3N domain of CrkII are responsible for the interaction. Functional characterization showed that the interaction is required for the recruitment of ACAP4 to the plasma membrane where ACAP4 functions to regulate the recycling of the signal transducer integrin β1. Thus, we suggest that the CrkII-ACAP4 complex may be involved in regulation of cell adhesion.

Stromal integrin α11 regulates PDGFR-β signaling and promotes breast cancer progression

Cancer-associated fibroblasts (CAFs) are key actors in modulating the progression of many solid tumors such as breast cancer (BC). Herein, we identify an integrin α11/PDGFRβ+ CAF subset displaying tumor-promoting features in BC. In the preclinical MMTV-PyMT mouse model, integrin α11-deficiency led to a drastic reduction of tumor progression and metastasis. A clear association between integrin α11 and PDGFRβ was found at both transcriptional and histological levels in BC specimens. High stromal integrin α11/PDGFRβ expression was associated with high grades and poorer clinical outcome in human BC patients. Functional assays using five CAF subpopulations (one murine, four human) revealed that integrin α11 promotes CAF invasion and CAF-induced tumor cell invasion upon PDGF-BB stimulation. Mechanistically, integrin α11 pro-invasive activity relies on its ability to interact with PDGFRβ in a ligand-dependent manner and to promote its downstream JNK activation, leading to the production of tenascin C, a pro-invasive matricellular protein. Pharmacological inhibition of PDGFRβ and JNK impaired tumor cell invasion induced by integrin α11-positive CAFs. Collectively, our study uncovers an integrin α11-positive subset of pro-tumoral CAFs that exploits PDGFRβ/JNK signalling axis to promote tumor invasiveness in BC.

CRKII overexpression promotes the in vitro proliferation, migration and invasion potential of murine hepatocarcinoma Hca-P cells

Lymphatic metastasis is a major mechanism of tumor metastasis. The present study aimed to investigate the association of CRKII, a member of the CRK family, with the in vitro malignant behaviors of a murine hepatocarcinoma Hca-P cell line, with a lymph node metastatic rate of ~25%. Total mRNA was extracted from Hca-P cells, and then the murine CRKII gene was amplified by polymerase chain reaction and cloned into the pEASY-blunt cloning vector. Subsequently, the recombinant pcDNA3.1/V5-HisB-CRKII plasmid was constructed and transfected into Hca-P cells. Western blotting indicated that the CRKII expression level in pcDNA3.1/V5-HisB-CRKII-Hca-P cells was increased by ~185%, compared with pcDNA3.1/V5-HisB-Hca-P cells. The stable overexpression of CRKII enhanced the in vitro proliferation ability, as measured with a Cell Counting Kit-8 assay, and the colony forming capacity was measured with a soft agar colony forming assay for Hca-P cells. The in vitro migration and invasion capacities of Hca-P cells were increased by ~179 and 156% in Hca-P cells, respectively, following the stable upregulation of CRKII. Collectively, the recombinant pcDNA3.1/V5-HisB-CRKII-Hca-P plasmid was constructed successfully. Additionally, the CRKII expression level was positively associated with the in vitro proliferation, migration and invasion malignant properties of Hca-P cells.

The Tumor Suppressor SASH1 Interacts With the Signal Adaptor CRKL to Inhibit Epithelial-Mesenchymal Transition and Metastasis in Colorectal Cancer

BACKGROUND & AIMS

The tumor-suppressor sterile α motif- and Src-homology 3-domain containing 1 (SASH1) has clinical relevance in colorectal carcinoma and is associated specifically with metachronous metastasis. We sought to identify the molecular mechanisms linking decreased SASH1 expression with distant metastasis formation.

METHODS

SASH1-deficient, SASH1-depleted, or SASH1-overexpressing HCT116 colon cancer cells were generated by the Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated 9-method, RNA interference, and transient plasmid transfection, respectively. Epithelial-mesenchymal transition (EMT) was analyzed by quantitative reverse-transcription polymerase chain reaction, immunoblotting, immunofluorescence microscopy, migration/invasion assays, and 3-dimensional cell culture. Yeast 2-hybrid assays and co-immunoprecipitation/mass-spectrometry showed V-Crk avian sarcoma virus CT10 oncogene homolog-like (CRKL) as a novel interaction partner of SASH1, further confirmed by domain mapping, site-directed mutagenesis, co-immunoprecipitation, and dynamic mass redistribution assays. CRKL-deficient cells were generated in parental or SASH1-deficient cells. Metastatic capacity was analyzed with an orthotopic mouse model. Expression and significance of SASH1 and CRKL for survival and response to chemotherapy was assessed in patient samples from our department and The Cancer Genome Atlas data set.

RESULTS

SASH1 expression is down-regulated during cytokine-induced EMT in cell lines from colorectal, pancreatic, or hepatocellular cancer, mediated by the putative SASH1 promoter. Deficiency or knock-down of SASH1 induces EMT, leading to an aggressive, invasive phenotype with increased chemoresistance. SASH1 counteracts EMT through interaction with the oncoprotein CRKL, inhibiting CRKL-mediated activation of SRC kinase, which is crucially required for EMT. SASH1-deficient cells form significantly more metastases in vivo, depending entirely on CRKL. Patient tumor samples show significantly decreased SASH1 and increased CRKL expression, associated with significantly decreased overall survival. Patients with increased CRKL expression show significantly worse response to adjuvant chemotherapy.

CONCLUSIONS

We propose SASH1 as an inhibitor of CRKL-mediated SRC signaling, introducing a potentially druggable mechanism counteracting chemoresistance and metastasis formation.

Murine chronic graft-versus-host disease proteome profiling discovers CCL15 as a novel biomarker in patients

Improved diagnostic and treatment methods are needed for chronic graft-versus-host disease (cGVHD), the leading cause of late nonrelapse mortality (NRM) in long-term survivors of allogenic hematopoietic cell transplantation. Validated biomarkers that facilitate disease diagnosis and classification generally are lacking in cGVHD. Here, we conducted whole serum proteomics analysis of a well-established murine multiorgan system cGVHD model. We discovered 4 upregulated proteins during cGVHD that are targetable by genetic ablation or blocking antibodies, including the RAS and JUN kinase activator, CRKL, and CXCL7, CCL8, and CCL9 chemokines. Donor T cells lacking CRK/CRKL prevented the generation of cGVHD, germinal center reactions, and macrophage infiltration seen with wild-type T cells. Whereas antibody blockade of CCL8 or CXCL7 was ineffective in treating cGVHD, CCL9 blockade reversed cGVHD clinical manifestations, histopathological changes, and immunopathological hallmarks. Mechanistically, elevated CCL9 expression was present predominantly in vascular smooth muscle cells and uniquely seen in cGVHD mice. Plasma concentrations of CCL15, the human homolog of mouse CCL9, were elevated in a previously published cohort of 211 cGVHD patients compared with controls and associated with NRM. In a cohort of 792 patients, CCL15 measured at day +100 could not predict cGVHD occurring within the next 3 months with clinically relevant sensitivity/specificity. Our findings demonstrate for the first time the utility of preclinical proteomics screening to identify potential new targets for cGVHD and specifically CCL15 as a diagnosis marker for cGVHD. These data warrant prospective biomarker validation studies.

CRKL Mediates p110β-Dependent PI3K Signaling in PTEN-Deficient Cancer Cells

The p110β isoform of PI3K is preferentially activated in many tumors deficient in the phosphatase and tensin homolog (PTEN). However, the mechanism(s) linking PTEN loss to p110β activation remain(s) mysterious. Here, we identify CRKL as a member of the class of PI3Kβ-interacting proteins. Silencing CRKL expression in PTEN-null human cancer cells leads to a decrease in p110β-dependent PI3K signaling and cell proliferation. In contrast, CRKL depletion does not impair p110α-mediated signaling. Further study showed that CRKL binds to tyrosine-phosphorylated p130Cas in PTEN-null cancer cells. Since Src family kinases are known both to be regulated by PTEN and to phosphorylate and activate p130Cas, we tested and found that Src inhibition cooperated with p110β inhibition to suppress the growth of PTEN-null cells. These data suggest both a potential mechanism linking PTEN loss to p110β activation and the possible benefit of dual inhibition of Src and PI3K for PTEN-null tumors.

Structure-guided design of a potent peptide inhibitor targeting the interaction between CRK and ABL kinase

CT-10 regulator of kinase (CRK) proteins play important roles in human cancer metastasis and invasion. Moreover, CRK proteins are the major phosphorylation substrates of ABL kinase and its oncogenic mutant BCR-ABL kinase. The interaction between CRK and BCR-ABL plays important roles in chronic myeloid leukemia. Hence, inhibiting the interaction of CRK with BCR-ABL is an attractive way to attenuate cancer metastasis. Herein, we report the development of a peptide inhibitor, PRM-3, targeting the interaction between CRK-II and ABL kinase. PRM-3 binds to the N-terminal SH3 (nSH3) domain in CRK-II with a 10 nM affinity and prevents the interaction between CRK-II and ABL kinase. An in vitro biochemical assay demonstrated that PRM-3 inhibits the ABL-dependent phosphorylation of CRK-II more effectively than imatinib. Remarkably, PRM-3 also inhibited the CRK phosphorylation by T315I-ABL kinase, which is resistant to all first- and second-generation tyrosine kinase inhibitors. Our study provides a promising alternative approach to overcome the drug resistance of ABL kinase.

MicroRNAs mediated regulation of MAPK signaling pathways in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a severe problem throughout the world and requires identification of novel targets for its treatment. This multifactorial disease accounts for about 15% of the all diagnosed leukemia cases. Mitogen-activated protein kinase (MAPK) signaling pathway is crucial for the cell survival and its dysregulation is being implicated in various types of cancers. In here, we have discussed the potential role of various miRNAs that are found involved in regulating the proteins cascades of MAPK signaling pathway associated with CML. An emphasis has been paid to summarize the influence of various miRNAs in elevating or suppressing the expression level of significant proteins such as miR-203, miR-196a, miR-196b, miR-30a, miR-29b, miR-138 in BCR-ABL tyrosine kinase; miR-126, miR-221, miR-128, miR-15a, miR-188-5p, miR-17 in CRK family proteins; miR-155, miR-181a with SOS proteins; miR-155, miR-19a, with KRAS proteins; miR-19a with RAF1 protein; and miR-17, miR-19a, miR-17-92 cluster with MAPK/ERK proteins. In light of ever-increasing importance and ever-widening regulatory roles of miRNAs in cells, we have reviewed the recent progress in the field of miRNAs and have tried to suggest them as controlling targets for various protein cascades of MAPK signaling pathway. An understanding of the supervisory mechanism of MAPK by miRNAs might provide novel targets for treating CML.

Fibroblast Growth Requires CT10 Regulator of Kinase (Crk) and Crk-like (CrkL)

CT10 regulator of kinase (Crk) and Crk-like (CrkL) are the cellular counterparts of the viral oncogene v-Crk Elevated levels of Crk and CrkL have been observed in many human cancers; inhibition of Crk and CrkL expression reduced the tumor-forming potential of cancer cell lines. Despite a close relationship between the Crk family proteins and tumorigenesis, how Crk and CrkL contribute to cell growth is unclear. We ablated endogenous Crk and CrkL from cultured fibroblasts carrying floxed alleles of Crk and CrkL by transfection with synthetic Cre mRNA (synCre). Loss of Crk and CrkL induced by synCre transfection blocked cell proliferation and caused shrinkage of the cytoplasm and the nucleus, formation of adherens junctions, and reduced cell motility. Ablation of Crk or CrkL alone conferred a much more modest reduction in cell proliferation. Reintroduction of CrkI, CrkII, or CrkL individually rescued cell proliferation in the absence of the endogenous Crk and CrkL, suggesting that Crk and CrkL play overlapping functions in regulating fibroblast growth. Serum and basic FGF induced phosphorylation of Akt, MAP kinases, and S6 kinase and Fos expression in the absence of Crk and CrkL, suggesting that cells lacking Crk and CrkL are capable of initiating major signal transduction pathways in response to extracellular stimuli. Furthermore, cell cycle and cell death analyses demonstrated that fibroblasts lacking Crk and CrkL become arrested at the G₁-S transition and undergo a modest apoptosis. Taken together, our results suggest that Crk and CrkL play essential overlapping roles in fibroblast growth.

Prognostic value of microRNA-126 and CRK expression in gastric cancer

Background

MicroRNA (miR)-126, acting as a tumor suppressor, has been reported to inhibit the invasion of gastric cancer cells in part by targeting v-crk sarcoma virus CT10 oncogene homologue (CRK). The aim of this study was to investigate the clinical significance of miR-126/CRK axis in gastric cancer.

Methods

miR-126 and CRK mRNA expression levels were detected by real-time quantitative reverse transcription polymerase chain reaction in 220 self-pairs of gastric cancer and adjacent noncancerous tissues.

Results

Expression levels of miR-126 and CRK mRNA in gastric cancer tissues were, respectively, lower and higher than those in adjacent noncancerous tissues (both P<0.001). Low miR-126 expression and high CRK expression, alone or in combination, were all significantly associated with positive lymph node and distant metastases and advanced TNM stage of human gastric cancer (all P<0.05). We also found that the overall survival rates of the patients with low miR-126 expression and high CRK expression were, respectively, shorter than those with high miR-126 expression and low CRK expression. Interestingly, miR-126-low/CRK-high expression was associated with a significantly worse overall survival of all miR-126/CRK groups (P<0.001). Moreover, multivariate analysis identified miR-126 and/or CRK expression as independent prognostic factors for patients with gastric cancer. Notably, the prognostic relevance of miR-126 and/or CRK expression was more obvious in the subgroup of patients with TNM stage IV.

Conclusion

Dysregulation of miR-126/CRK axis may promote the malignant progression of human gastric cancer. miR-126 and CRK combined expression may serve as an independent predictor of overall survival in patients with advanced gastric cancer.

Abelson kinase acts as a robust, multifunctional scaffold in regulating embryonic morphogenesis

The importance of Abl kinase activity, the F-actin–binding site, and scaffolding ability in Abl’s many cell biological roles during Drosophila morphogenesis is examined. Abl is a robust multidomain scaffold with different protein motifs and activities contributing differentially to diverse cellular behaviors.

Abelson family kinases (Abls) are key regulators of cell behavior and the cytoskeleton during development and in leukemia. Abl’s SH3, SH2, and tyrosine kinase domains are joined via a linker to an F-actin–binding domain (FABD). Research on Abl’s roles in cell culture led to several hypotheses for its mechanism of action: 1) Abl phosphorylates other proteins, modulating their activity, 2) Abl directly regulates the cytoskeleton via its cytoskeletal interaction domains, and/or 3) Abl is a scaffold for a signaling complex. The importance of these roles during normal development remains untested. We tested these mechanistic hypotheses during Drosophila morphogenesis using a series of mutants to examine Abl’s many cell biological roles. Strikingly, Abl lacking the FABD fully rescued morphogenesis, cell shape change, actin regulation, and viability, whereas kinase-dead Abl, although reduced in function, retained substantial rescuing ability in some but not all Abl functions. We also tested the function of four conserved motifs in the linker region, revealing a key role for a conserved PXXP motif known to bind Crk and Abi. We propose that Abl acts as a robust multidomain scaffold with different protein motifs and activities contributing differentially to diverse cellular behaviors.

Reduction of CRKL expression in patients with partial DiGeorge syndrome is associated with impairment of T-cell functions

BACKGROUND

Partial DiGeorge syndrome (pDGS) is caused by deletion of the 22q11.2 region. Within this region lies CrK-like (CRKL), a gene encoding an adapter protein belonging to the Crk family that is involved in the signaling cascade of IL-2, stromal cell-derived factor 1α, and type I interferon. Although recurrent infections can be observed in patients with deletion of chromosome 22 syndrome, the immune pathogenesis of this condition is yet not fully understood.

OBJECTIVE

We aimed to investigate the role of CRKL in T-cell functional responses in patients affected with pDGS.

METHODS

Protein expression levels and phosphorylation of CRKL were evaluated in patients with pDGS. T-cell functional assays in vitro and gene-silencing experiments were also performed.

RESULTS

CRKL protein expression, as well as its phosphorylation, were reduced in all patients with pDGS, especially on IL-2 stimulation. Moreover, T cells presented impaired proliferation and reduced IL-2 production on anti-CD3/CD28 stimulation and decreased c-Fos expression. Finally, CRKL silencing in Jurkat T cells resulted in impaired T-cell proliferation and reduced c-Fos expression.

CONCLUSIONS

The impaired T-cell proliferation and reduction of CRKL, phosphorylated CRKL, and c-Fos levels suggest a possible role of CRKL in functional deficiencies of T cells in patients with pDGS.

Cyclophilin A promotes cell migration via the Abl-Crk signaling pathway

Cyclophilin A (CypA) is overexpressed in a number of human cancer types, but the mechanisms by which the protein promotes oncogenic properties of cells are not understood. Here we demonstrate that CypA binds the CrkII adaptor protein and prevents it from switching to the inhibited state. CrkII influences cell motility and invasion by mediating signaling through its SH2 and SH3 domains. CrkII Tyr221 phosphorylation by the Abl or EGFR kinases induces an inhibited state of CrkII by means of an intramolecular SH2-pTyr221 interaction, causing signaling interruption. We show that the CrkII phosphorylation site constitutes a binding site for CypA. Recruitment of CypA sterically restricts the accessibility of Tyr221 to kinases, thereby suppressing CrkII phosphorylation and promoting the active state. Structural, biophysical and in vivo data show that CypA augments CrkII-mediated signaling. A strong stimulation of cell migration is observed in cancer cells wherein both CypA and CrkII are greatly upregulated.

Sorbs1 and -2 Interact with CrkL and Are Required for Acetylcholine Receptor Cluster Formation

Crk and CrkL are noncatalytic adaptor proteins necessary for the formation of neuromuscular synapses which function downstream of muscle-specific kinase (MuSK), a receptor tyrosine kinase expressed in skeletal muscle, and the MuSK binding protein Dok-7. How Crk/CrkL regulate neuromuscular endplate formation is not known. To better understand the roles of Crk/CrkL, we identified CrkL binding proteins using mass spectrometry and have identified Sorbs1 and Sorbs2 as two functionally redundant proteins that associate with the initiating MuSK/Dok-7/Crk/CrkL complex, regulate acetylcholine receptor (AChR) clustering in vitro, and are localized at synapses in vivo.

The role of CRKL in breast cancer metastasis: insights from systems biology

Breast cancer metastasis is a complex and still weakly understood process that involves diverse cellular pathways. It accounts for the majority of deaths from breast cancer. Recently, microRNAs (miRNAs), small non-coding RNAs that regulate gene expression post-transcriptionally, have been shown to be involved in breast cancer metastasis. In particular, in a recent work it has been found that miR-429 may have a role in the inhibition of migration and invasion of breast cancer cells. Its target gene CRKL has been identified as a potential candidate. In this paper, by using systems biology tools we have shown that CRKL is involved in positive regulation of ERK1/2 signaling pathway and contribute to the regulation of LYN through a topological generalization of feed forward loop.

Up-Regulation of Oligodendrocyte Lineage Markers in the Cerebellum of Autistic Patients: Evidence from Network Analysis of Gene Expression

Autism is a neurodevelopmental disorder manifested by impaired social interaction, deficits in communication skills, restricted interests, and repetitive behaviors. In neurodevelopmental, neurodegenerative, and psychiatric disorders, glial cells undergo morphological, biochemical, and functional rearrangements, which are critical for neuronal development, neurotransmission, and synaptic connectivity. Cerebellar function is not limited to motor coordination but also contributes to cognition and may be affected in autism. Oligodendrocytes and specifically oligodendroglial precursors are highly susceptible to oxidative stress and excitotoxic insult. In the present study, we searched for evidence for developmental oligodendropathy in the context of autism by performing a network analysis of gene expression of cerebellar tissue. We created an in silico network model (OLIGO) showing the landscape of interactions between oligodendrocyte markers and demonstrated that more than 50 % (16 out of 30) of the genes within this model displayed significant changes of expression (corrected p value <0.05) in the cerebellum of autistic patients. In particular, we found up-regulation of OLIG2-, MBP-, OLIG1-, and MAG-specific oligodendrocyte markers. We postulate that aberrant expression of oligodendrocyte-specific genes, potentially related to changes in oligodendrogenesis, may contribute to abnormal cerebellar development, impaired myelination, and anomalous synaptic connectivity in autism spectrum disorders (ASD).

LASP1 is a novel BCR-ABL substrate and a phosphorylation-dependent binding partner of CRKL in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is characterized by a genomic translocation generating a permanently active BCR-ABL oncogene with a complex pattern of atypically tyrosine-phosphorylated proteins that drive the malignant phenotype of CML. Recently, the LIM and SH3 domain protein 1 (LASP1) was identified as a component of a six gene signature that is strongly predictive for disease progression and relapse in CML patients. However, the underlying mechanisms why LASP1 expression correlates with dismal outcome remained unresolved. Here, we identified LASP1 as a novel and overexpressed direct substrate of BCR-ABL in CML. We demonstrate that LASP1 is specifically phosphorylated by BCR-ABL at tyrosine-171 in CML patients, which is abolished by tyrosine kinase inhibitor therapy. Further studies revealed that LASP1 phosphorylation results in an association with CRKL - another specific BCR-ABL substrate and bona fide biomarker for BCR-ABL activity. pLASP1-Y171 binds to non-phosphorylated CRKL at its SH2 domain. Accordingly, the BCR-ABL-mediated pathophysiological hyper-phosphorylation of LASP1 in CML disrupts normal regulation of CRKL and LASP1, which likely has implications on downstream BCR-ABL signaling. Collectively, our results suggest that LASP1 phosphorylation might serve as an additional candidate biomarker for assessment of BCR-ABL activity and provide a first step toward a molecular understanding of LASP1 function in CML.

Abl Kinases Regulate HGF/Met Signaling Required for Epithelial Cell Scattering, Tubulogenesis and Motility

Tight regulation of receptor tyrosine kinases (RTKs) is crucial for normal development and homeostasis. Dysregulation of RTKs signaling is associated with diverse pathological conditions including cancer. The Met RTK is the receptor for hepatocyte growth factor (HGF) and is dysregulated in numerous human tumors. Here we show that Abl family of non-receptor tyrosine kinases, comprised of Abl (ABL1) and Arg (ABL2), are activated downstream of the Met receptor, and that inhibition of Abl kinases dramatically suppresses HGF-induced cell scattering and tubulogenesis. We uncover a critical role for Abl kinases in the regulation of HGF/Met-dependent RhoA activation and RhoA-mediated actomyosin contractility and actin cytoskeleton remodeling in epithelial cells. Moreover, treatment of breast cancer cells with Abl inhibitors markedly decreases Met-driven cell migration and invasion. Notably, expression of a transforming mutant of the Met receptor in the mouse mammary epithelium results in hyper-activation of both Abl and Arg kinases. Together these data demonstrate that Abl kinases link Met activation to Rho signaling and Abl kinases are required for Met-dependent cell scattering, tubulogenesis, migration, and invasion. Thus, inhibition of Abl kinases might be exploited for the treatment of cancers driven by hyperactivation of HGF/Met signaling.

N of 1 case reports of exceptional responders accrued from pancreatic cancer patients enrolled in first-in-man studies from 2002 through 2012

PURPOSE

To identify exceptional responders among patients with advanced pancreatic cancer enrolled in first-in-man (FIM) studies.

METHODS

A Scopus search identified 66 FIM studies that enrolled at least one patient with advanced pancreatic cancer between 2002-2012. Descriptive statistics were used to summarize categorical variables. We also screened CRKL amplifications in the FoundationOne™ pancreatic cancer database.

RESULTS

Most FIM studies included targeted therapies (76 vs. 24%). The most common targeted therapy involved cell cycle inhibitors (24%). Pharmacodynamic analyses were more frequently done in trials with targeted therapies (70 vs. 31%, p=0.006). Response rates were similar. Treatment-related death was 0.5%. Skin, cardiovascular and metabolic grade 3-4 toxicities were more frequent with targeted therapies. Four exceptional responses were identified including a complete response to bosutinib (Src Inhibitor) and partial responses to trametinib (MEK inhibitor) (2 patients) and CHR-3996 (histone deacetylase inhibitor). We found that CRKL amplifications, a potential biomarker for Src inhibitors, are present in 1% of PDA.

CONCLUSIONS

We retrospectively identified extraordinary responses among patients with advanced PDA enrolled in FIM studies with Src, HDAC and MEK inhibitors. We identified CRKL amplifications are present in 1% of PDA and need to be evaluated as predictive biomarker for Src inhibitors.

CrkL regulates SDF-1-induced breast cancer biology through balancing Erk1/2 and PI3K/Akt pathways

The adapter protein CrkL is required for regulating the malignant potential of human cancers. However, the regulatory mechanisms of CrkL on the stromal cell-derived factor 1 (SDF-1)/CXCR4 signaling pathways in breast cancer are not well characterized. Here, CXCR4 and CrkL proteins were tested in breast cancer cell lines and 60 primary breast cancer tissues. In vitro, the roles of CrkL in SDF-1-induced MDA-MB-231 cell cycle, invasion and migration were investigated. In the present study, CXCR4 and CrkL were highly expressed in MCF-7, MDA-MB-231, MDA-MB-231HM MDA-MB-468 and tumor tissues (80 and 60 %, respectively) and closely correlated with lymph node metastasis. In vitro studies revealed that SDF-1 induced the activation of CrkL, Erk1/2, Akt and matrix metallopeptidase 9 (MMP9) in MDA-MB-231 cells. The si-CrkL treatment significantly down-regulated the phosphorylated Erk1/2 (p-Erk1/2) and MMP9, but up-regulated p-Akt, compared with control. Importantly, wound-healing and transwell invasion assays showed that si-CrkL significantly impaired the wound closure and inhibited the SDF-1-induced invasion; similarly, flow cytometry showed that si-CrkL affected cell cycle. In conclusion, these results suggest that CrkL plays a regulatory role in the SDF-1-induced Erk1/2 and PI3K/Akt pathways and further managed the invasion and migration of breast cancer cells. Thus, CrkL may be recommended as an interesting therapeutic target for breast cancer.

Contribution of Crk adaptor proteins to host cell and bacteria interactions

The Crk adaptor family of proteins comprises the alternatively spliced CrkI and CrkII isoforms, as well as the paralog Crk-like (CrkL) protein, which is encoded by a different gene. Initially thought to be involved in signaling during apoptosis and cell adhesion, this ubiquitously expressed family of proteins is now known to play essential roles in integrating signals from a wide range of stimuli. In this review, we describe the structure and function of the different Crk proteins. We then focus on the emerging roles of Crk adaptors during Enterobacteriaceae pathogenesis, with special emphasis on the important human pathogens Salmonella, Shigella, Yersinia, and enteropathogenic Escherichia coli. Throughout, we remark on opportunities for future research into this intriguing family of proteins.

CRKL overexpression suppresses in vitro proliferation, invasion and migration of murine hepatocarcinoma Hca-P cells

The signal adaptor CRK family protein play important roles in cancer cell progression, proliferation, migration and invasion. Previously, we showed that CRK was involved in lymphatic metastatic potential of murine hepatocarcinoma cells. In current work, as a member of CRK family, chicken tumour virus number 10 regulator of kinase-like protein (CRKL) was revealed to be associated with malignant behaviors of Hca-P, a murine HCC cell with lymph node metastatic (LNM) rate of ∼25%. CRKL overexpression in Hca-P by a constructed eukaryotic expression vector of pcDNA3.1/V5-HisB-CRKL significantly ameliorated its malignant biological properties. CCK-8 and soft agar colony formation assays indicated CRKL overexpression significantly inhibits the cell proliferation and colony formation abilities of Hca-P. Additionally, transwell assays indicated that the Hca-P cell migration and invasion capacities were apparently reduced following CRKL overexpression. As Hca-P is an ideal hepatocarcinoma cell model with low (initial) LNM potential, CRKL is shown to act as a potential suppressor and to provide new insight for both the malignant behaviors of hepatocarcinoma cells and lymphatic metastasis mechanism of hepatocarcinoma.

Crk-like adapter protein is required for TGF-β-induced AKT and ERK-signaling pathway in epithelial ovarian carcinomas

Crk-like adapter protein (CrkL) was identified as an important biomarker in epithelial ovarian carcinomas. At the same time, the transforming growth factor β (TGF-β) pathway plays a key role in oncogenesis of advanced cancers. However, more detailed regulation mechanisms are still unclear. So we investigated the role of CrkL in TGF-β pathways in epithelial ovarian carcinomas. The small interfering RNA (siRNA) was used to suppress CrkL in serous papillary cystic adenocarcinoma (SKOV-3) cell line, TGF-β downstream signal molecules AKT and ERK phosphorylation status was tested using the Western blot. Wound healing assay was used to evaluate the capacity of cell migration and proliferation. In this study, CrkL can be activated by TGF-β1 treatment and inhibited by siCrkL. CrkL knockdown markedly suppressed the phosphorylated ERK (p-ERK) as well as the phosphorylated AKT (p-AKT) (p < 0.001) compared with control or TGF-β1 alone. On the other hand, CrkL knockdown could significantly affect SKOV3 wound closure (p < 0.001) using wound healing assay compared to siControl. In conclusion, CrkL protein is required for TGF-β signal pathways through AKT and ERK pathway, which can mediate the development of epithelial ovarian carcinomas. CrkL plays a key regulation role in TGF-β signaling pathway of epithelial ovarian carcinomas, and this study suggested CrkL could be suggested as an efficient target in ovarian cancer treatment.

The clinical implications of Crk-like adaptor protein expression in papillary thyroid microcarcinoma

Papillary thyroid microcarcinoma (PMC) is the most common subtype of thyroid carcinomas with satisfactory prognosis. Crk-like (CrkL) adaptor protein was identified in the development of many carcinomas. However, the clinical implications of CrkL protein in PMC were still unknown. Here, we conducted immunohistochemistry to test and analyze CrkL expression in papillary thyroid carcinoma (PTC) (50 cases), PMC (50 cases), and nodular goiter (50 cases), and then western blot further identified the expression of CrkL proteins. In our present study, the positive rate and the mean optical density (MOD) value of CrkL expression in PTC and PMC tissues were statistically significantly different, compared with nodular goiter (p = 0.021, 0.037) and normal thyroid tissues (p = 0.003, 0.009), respectively. In addition, CrkL expression was not associated with age, gender, and tumor number. Conversely, significant differences between CrkL expression and metastasis (p < 0.01) and violation of capsule (p < 0.01) were observed. Notably, western blot indeed identified that the metastasis group of either PTC or PMC tissues had about twofold increased expression of CrkL compared with their non-metastasis groups (p < 0.05). In conclusion, CrkL is highly expressed in papillary thyroid carcinoma and papillary thyroid microcarcinoma and closely correlated to metastasis. Therefore, it is essential to carry out neck lymph node clearance in patients with papillary thyroid microcarcinoma.

Phosphorylation of Dok1 by Abl family kinases inhibits CrkI transforming activity

The Crk SH2/SH3 adaptor and the Abl nonreceptor tyrosine kinase were first identified as oncoproteins, and both can induce tumorigenesis when overexpressed or mutationally activated. We previously reported the surprising finding that inhibition or knockdown of Abl family kinases enhanced transformation of mouse fibroblasts by CrkI. Abl family inhibitors are currently used or are being tested for treatment of human malignancies, and our finding raised concerns that such inhibitors might actually promote the growth of tumors overexpressing CrkI. Here, we identify the Dok1 adaptor as the key effector for the enhancement of CrkI transformation by Abl inhibition. We show that phosphorylation of tyrosines 295 and 361 of Dok1 by Abl family kinases suppresses CrkI transforming activity, and that upon phosphorylation these tyrosines bind the SH2 domains of the Ras inhibitor p120 RasGAP. Knockdown of RasGAP resulted in a similar enhancement of CrkI transformation, consistent with a critical role for Ras activity. Imaging studies using a FRET sensor of Ras activation revealed alterations in the localization of activated Ras in CrkI-transformed cells. Our results support a model in which Dok1 phosphorylation normally suppresses localized Ras pathway activity in Crk-transformed cells via recruitment and/or activation of RasGAP, and that preventing this negative feedback mechanism by inhibiting Abl family kinases leads to enhanced transformation by Crk.

Significant evidence of linkage for a gene predisposing to colorectal cancer and multiple primary cancers on 22q11

Objectives:

The genetic basis of colorectal cancer (CRC) is not completely specified. Part of the difficulty in mapping predisposition genes for CRC may be because of phenotypic heterogeneity. Using data from a population genealogy of Utah record linked to a statewide cancer registry, we identified a subset of CRC cases that exhibited familial clustering in excess of that expected for all CRC cases in general, which may represent a genetically homogeneous subset of CRC.

Methods:

Using a new familial aggregation method referred to as the subset genealogic index of familiality (subsetGIF), combined with detailed information from a statewide tumor registry, we identified a subset of CRC cases that exhibited excess familial clustering above that expected for CRC: CRC cases who had at least one other primary tumor at a different site. A genome-wide linkage analysis was performed on a set of high-risk CRC pedigrees that included multiple CRC cases with additional primaries to identify evidence for predisposition loci.

Results:

A total of 13 high-risk CRC pedigrees with multiple CRC cases with other primary cancers were identified. Linkage analysis identified one pedigree with a significant linkage signal at 22q11 (LOD (logarithm (base 10) of odds)=3.39).

Conclusions:

A predisposition gene or variant for CRC that also predisposes to other primary cancers likely resides on chromosome 22q11. The ability to use statewide population genealogy and tumor registry data was critical to identify an informative subset of CRC cases that is possibly more genetically homogeneous than CRC in general, and may have improved statistical power for predisposition locus identification in this study.

The association of Crk-like adapter protein with poor prognosis in glioma patients

Glioma is the most common of brain tumors that greatly affects patient survival. In our precious study, Crk-like adapter protein (CrkL) was identified as a key regulator in glioblastoma development [1]. Here, we aimed to investigate the correlation of CrkL with patient prognosis as well as pathological indicators. Immunohistochemistry was available to evaluate CrkL expression in 49 gliomas of distinct malignancy grade, and positive stained sites were analyzed. CrkL protein was detected in cell lines by Western blot as well. We observed CrkL protein stained in 59.2 % (29 out of 49) of all glioma tissues, including 41.4 % of low-grade (I + II) gliomas, and 85.0 % of high-grade (III + IV) gliomas. Of four grades, grade IV exhibited the highest CrkL level. CrkL protein was also identified in cell lines NHA, U87, U251, T98G, and A172 by Western blot. On the other hand, CrkL expression was significantly associated with the patient's age and WHO grade, and patients with high CrkL expression had a significantly shorter median survival time (17 months) than those (median survival time 52 months) with low CrkL expression (p<0.001). According to Cox regression, CrkL can be suggested as an independent prognostic factor. In conclusion, CrkL is differently expressed in different grades of gliomas, and correlated to WHO grade. CrkL also independently indicates poor prognosis in old glioma patients, which can further be recommended as an effective prognostic biomarker or therapeutic target.

Transcriptomic and phospho-proteomic analyzes of erythroblasts expanded in vitro from normal donors and from patients with polycythemia vera

Erythropoiesis is a tightly regulated process which becomes decoupled from its normal differentiation program in patients with polycythemia vera (PV). Somatic mutations in JAK2 are commonly associated with this myeloid proliferative disorder. To gain insight into the molecular events that are required for abnormally developing erythroid cells to escape dependence on normal growth signals, we performed in vitro expansion of mature erythroblasts (ERY) from seven normal healthy donors and from seven polycythemic patients in the presence of IL3, EPO, SCF for 10, 11, or 13 days. Normal ERYs required exposure to the glucocorticoid dexamethasone (Dex) for expansion, while PV-derived ERYs expanded in the absence of dexamethasone. RNA expression profiling revealed enrichment of two known oncogenes, GPR56 and RAB4a, in PV-derived ERYs along with reduced expression levels of transcription factor TAL1 (ANOVA FDR < 0.05). While both normal and polycythemic-derived ERYs integrated signaling cascades for growth, they did so via different signaling pathways which are represented by their differential phospho-profiles. Our results show that normal ERYs displayed greater levels of phosphorylation of EGFR, PDGFRβ, TGFβ, and cKit, while PV-derived ERYs were characterized by increased phosphorylation of cytoplasmic kinases in the JAK/STAT, PI3K, and GATA1 pathways. Together these data suggest that PV erythroblast expansion and maturation may be maintained and enriched in the absence of dexamethasone through reduced TAL1 expression and by accessing additional signaling cascades. Members of this acquired repertoire may provide important insight into the pathogenesis of aberrant erythropoiesis in myeloproliferative neoplasms such as polycythemia vera.

PTPN4 negatively regulates CrkI in human cell lines

PTPN4 is a widely expressed non-receptor protein tyrosine phosphatase. Although its overexpression inhibits cell growth, the proteins with which it interacts to regulate cell growth are unknown. In this study, we identified CrkI as a PTPN4-interacting protein using a yeast two-hybrid, and confirmed this interaction using in vitro GST pull-down and co-immunoprecipitation and co-localization assays. We further determined the interactional regions as the SH3 domain of CrkI and the proline-rich region between amino acids 462 and 468 of PTPN4. Notably, overexpression of PTPN4 inhibits CrkI-mediated proliferation and wound healing of HEK293T cells, while knockdown of PTPN4 by siRNA in Hep3B cells enhances CrkI-mediated cell growth and motility. Moreover, our data show that ectopic expression of PTPN4 reduces the phosphorylation level of CrkI in HEK293T cells. These findings suggest that PTPN4 negatively regulates cell proliferation and motility through dephosphorylation of CrkI.