Overexpression Of Cortactin Research Articles

Cortactin controls bone homeostasis through regulating the differentiation of osteoblasts and osteoclasts.

Cortactin (CTTN), a cytoskeletal protein and substrate of Src kinase, is implicated in tumor aggressiveness. However, its role in bone cell differentiation remains unknown. The current study revealed that CTTN was upregulated during osteoblast and adipocyte differentiation. Functional experiments demonstrated that CTTN promoted the in vitro differentiation of mesenchymal stem/progenitor cells into osteogenic and adipogenic lineages. Mechanistically, CTTN was able to stabilize the protein level of mechanistic target of rapamycin kinase (mTOR), leading to the activation of mTOR signaling. In-depth investigation revealed that CTTN could bind with casitas B lineage lymphoma-c (c-CBL) and counteract the function of c-CBL, a known E3 ubiquitin ligase responsible for the proteasomal degradation of mTOR. Silencing c-Cbl alleviated the impaired differentiation of osteoblasts and adipocytes caused by CTTN siRNA, while silencing mTOR mitigated the stimulation of osteoblast and adipocyte differentiation induced by CTTN overexpression. Notably, transplantation of CTTN-silenced bone marrow stromal cells (BMSCs) into the marrow of mice led to a reduction in trabecular bone mass, accompanied by a decrease in osteoblasts and an increase in osteoclasts. Furthermore, CTTN-silenced BMSCs expressed higher levels of receptor activator of nuclear factor κB ligand (RANKL) than control BMSCs did and promoted osteoclast differentiation when cocultured with bone marrow-derived osteoclast precursor cells. This study provides evidence that CTTN favors osteoblast differentiation by counteracting the c-CBL-induced degradation of mTOR and inhibits osteoclast differentiation by downregulating the expression of RANKL. It also suggests that maintaining an appropriate level of CTTN expression may be advantageous for maintaining bone homeostasis.

Focal adhesion kinase activation by calcium-dependent calpain is involved in chronic lymphocytic leukaemia cell aggressiveness.

Signalling events downstream the B-cell receptor (BCR) are central for the survival and progression of chronic lymphocytic leukaemia (CLL) cells. Focal adhesion kinase (FAK), regulated through calpain, interacts with molecules of BCR signalling, cytoskeletal modelling and disease progression, such as Src/Lyn, cortactin and HS1. Hypothesizing that FAK might play a key role in CLL pathogenesis, we observed a down-modulation of FAK whole form, associated with FAK cleavage due to calpain activity upon BCR stimulation. Patients, whose cells were able to release Ca++ after BCR stimulation, had less amount of full-length FAK, which translated into a higher presence of cleaved/activated form of the protein phosphorylated at Y397, these features being mostly shown by immunoglobulin heavy chain (IGHV)-unmutated poor-prognosis patients. Moreover, we found that cortactin and HS1 proteins were overexpressed in those cells, suggesting a possible interplay with FAK. Treatment with the FAK inhibitor Defactinib was able to induce apoptosis in CLL cells. In conclusion, the malignant phenotype in unfavourable-prognosis patients seems to be encouraged by the overexpression of cortactin and HS1, that, together with FAK, may be involved in a druggable pathogenetic pathway in CLL.

Cortactin contributes to the tumorigenesis of gastric cancer by activating ERK/MMP pathway

Gastric cancer is a malignant tumor with high mortality and high incidence. This study aims to explore the function and molecular mechanism of Cortactin on gastric cancer progression in vitro and in vivo. A bioinformatics analysis from TCGA displayed that Cortactin was highly expressed in gastric cancer samples, and patients with a high Cortactin level had a worse survival rate. Subsequently, we investigated the specific mechanism of action of A in gastric cancer by collecting patient samples for immunohistochemistry, WB, qRT-PCR, cell transfection, cell invasion and metastasis, and constructing tumor xenografts in nude mice. Overexpression of Cortactin inhibited apoptosis and enhanced cellular proliferation and mobility in AGS cells, while those activities were reversed by the knockdown of MMP2 or MMP9. Conversely, the deletion of Cortactin induced apoptosis and suppressed cell growth and metastasis in SGC7901 cells, whereas those behaviors were inhibited by overexpression of MMP2 or MMP9. Additionally, the ERK pathway was activated by Cortactin upregulation. In vivo studies presented that overexpression of Cortactin promoted tumor growth, increased Ki67 expression, and reduced caspase 3 expression, which was reversed by ERK inhibitor treatment. In conclusion, Cortactin acted as an oncogene in gastric cancer and exerted its function by ERK/MMP2/MMP9 signaling pathway.

Cortactin expression in a Norwegian cohort of human papilloma virus negative oral squamous cell carcinomas of the mobile tongue.

Oral squamous cell carcinoma of the tongue (OTSCC) is the most common malignancy among oral squamous cell carcinomas and is frequently associated with an unfavorable prognosis. Local spread and distant metastasis are important causes of poor prognosis in OTSCC. Cortactin amplification and overexpression, a common molecular alteration in oral squamous cell carcinomas, have been linked to invasion and metastasis of tumor cells. However, the intra-tumor expression pattern and prognostic significance of cortactin in human papillomavirus (HPV) negative OTSCC is not fully investigated. Immunohistochemical analysis using tissue microarray consisting of formalin-fixed and paraffin-embedded HPV negative OTSCC (n=123) specimens showed overexpression of cortactin at tissue cores from invading fronts as compared to the corresponding center cores. High overall cortactin expression was found to be associated with advanced (larger) tumor size and the occurrence of distance metastasis. Kaplan-Meier survival analysis showed that patients with high overall cortactin expression were associated with reduced 5-year survival. Multivariate Cox regression analysis identified high cortactin expression to be an independent prognostic factor in OTSCC. Additionally, siRNA-mediated silencing of cortactin was found to suppress the proliferative and invasive abilities of OTSCC cells in an organotypic co-culture model. Overexpression of cortactin is a promising prognostic marker in HPV-negative OTSCC.

T cell functions and organ infiltration by leukemic T cells require cortactin.

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that is still fatal in many cases. T cell blasts are characterized by hyperactivation and strong proliferative and migratory capacities. The chemokine receptor CXCR4 is involved in mediating malignant T cell properties, and cortactin has been shown to control CXCR4 surface localization in T-ALL cells. We have previously shown that cortactin overexpression is correlated with organ infiltration and relapse in B-ALL. However, the role of cortactin in T cell biology and T-ALL remains elusive. Here, we analyzed the functional relevance of cortactin for T cell activation and migration and the implications for T-ALL development. We found that cortactin is upregulated in response to T cell receptor engagement and recruited to the immune synapse in normal T cells. Loss of cortactin caused reduced IL-2 production and proliferation. Cortactin-depleted T cells showed defects in immune synapse formation and migrated less due to impaired actin polymerization in response to T cell receptor and CXCR4 stimulation. Leukemic T cells expressed much higher levels of cortactin compared to normal T cells that correlated with greater migratory capacity. Xenotransplantation assays in NSG mice revealed that cortactin-depleted human leukemic T cells colonized the bone marrow significantly less and failed to infiltrate the central nervous system, suggesting that cortactin overexpression drives organ infiltration, which is a major complication of T-ALL relapse. Thus, cortactin could serve as a potential therapeutic target for T-ALL and other pathologies involving aberrant T cell responses.

Cortactin expression in muscle-invasive and nonmuscle-invasive urinary bladder carcinoma in patients live in Sohag City, Egypt

Abstract Background Bladder carcinoma (BC) is the ninth most prevalent cancer worldwide. However, it represents the most frequently occurring cancer in Egypt, where infection by Schistosoma haematobium is an endemic health problem. BCs are clinically subdivided into different stages according to invasion of the muscle layer and distant metastasis. Invasion of the surrounding tissues and metastasis are characteristic issues in malignant tumors. Malignant cells rearrange the intracellular actin filaments in the form of an assembly of branched network in the direction of cell movement. The well-formed actin assembly must be anchored by an adhesive-like protein named cortactin (CTTN). CTTN overexpression has been detected in various human malignant neoplasms. The aim of this study was to evaluate the expression of CTTN in BC and to correlate such expression with different parameters such as depth of invasion, nodal metastasis, and bilharzial infestation. Patients and methods The current study enrolled 66 patients with BCs. Formalin-fixed and paraffin-embedded tissue blocks were prepared from each specimen. Hematoxylin and eosin tissue sections were prepared to confirm the diagnosis of BCs, determine tumor phenotype, assess degree of invasion, and detect any evidence of bilharzial infestation. Corresponding tissue sections were stained by antihuman CTTN antibody using the immunohistochemical approach. Results Overexpression of CTTN was associated with muscle invasion by neoplastic cells (P<0.001), advanced pathological T category (P=0.002), and presence of metastatic deposits in the regional lymph nodes (P<0.001). Conclusion Overexpression of CTTN in BC is associated with increased tumor invasion and nodal metastasis.

Respiratory syncytial virus disrupts the airway epithelial barrier by decreasing cortactin and destabilizing F-actin.

ABSTRACTRespiratory syncytial virus (RSV) infection is the leading cause of acute lower respiratory tract infection in young children worldwide. Our group recently revealed that RSV infection disrupts the airway epithelial barrier in vitro and in vivo. However, the underlying molecular pathways were still elusive. Here, we report the critical roles of the filamentous actin (F-actin) network and actin-binding protein cortactin in RSV infection. We found that RSV infection causes F-actin depolymerization in 16HBE cells, and that stabilizing the F-actin network in infected cells reverses the epithelial barrier disruption. RSV infection also leads to significantly decreased cortactin in vitro and in vivo. Cortactin-knockout 16HBE cells presented barrier dysfunction, whereas overexpression of cortactin protected the epithelial barrier against RSV. The activity of Rap1 (which has Rap1A and Rap1B forms), one downstream target of cortactin, declined after RSV infection as well as in cortactin-knockout cells. Moreover, activating Rap1 attenuated RSV-induced epithelial barrier disruption. Our study proposes a key mechanism in which RSV disrupts the airway epithelial barrier via attenuating cortactin expression and destabilizing the F-actin network. The identified pathways will provide new targets for therapeutic intervention toward RSV-related disease. This article has an associated First Person interview with the first author of the paper.

Dietary patterns in association with the expression of pro-metastatic genes in primary breast cancer.

Metastasis is a major leading cause of mortality in female breast cancer (BrCa). Cellular motility is a pathological process of metastasis remarked by the overexpression of cortactin (CTTN), Ras homolog family member-A (RhoA), and Rho-associated kinase (ROCK) genes.Their balanceisresponsible forupholding the integrity of healthy epithelial cell junctions. This study aimed to explore the associations between a posteriori dietary patterns and theexpression levels of pro-metastatic genes in primary BrCa. In this consecutive case series, 215 eligible women, newly diagnosed with histologically confirmednon-metastatic BrCa (stage I-IIIA), were recruited from Hospitals in Tabriz, NorthwesternIran (2015-2017). The tumoral expression levels of genes were quantified using real-time reverse transcription-polymerase chain reaction. Dietary data assessment was carried out using a validated food frequency questionnaire. Three dietary patterns were identified using principal component analysis (KMO = 0.699). Adherence to the "vegan" pattern (vegetables, fruits, legumes, nuts, seeds, and whole grains) was inversely associated with the expression levels of RhoA (ORAdj.T3vs.T1 = 0.24, 95%CI 0.07-0.79) and ROCK (ORAdj.T3vs.T1 = 0.26, 95%CI 0.08-0.87). In addition, the highest adherence to the "prudent" pattern (spices, seafood, dairy, and vegetable oils) decreased the odds of overexpressions at RhoA (ORAdj.T3vs.T1 = 0.26, 95%CI 0.08-0.84) and ROCK genes (ORAdj.T3vs.T1 = 0.29, 95%CI 0.09-0.95). The highest adherence to "Western" pattern (meat, processed meat, hydrogenated fat, fast food, refined cereals, sweets, and soft drinks) was a risk factor associated with the overexpression of RhoA (ORAdj.T3vs.T1 = 3.15, 95%CI 1.12-8.85). Adherence to healthy dietary patterns was significantly associated with the downregulation of pro-metastatic genes. Findings provided new implications to advance the nutrigenomic knowledge to prevent the odds ofover-regulations in pro-metastatic genes of theprimary BrCa.

The Helicobacter pylori type IV secretion system upregulates epithelial cortactin expression by a CagA- and JNK-dependent pathway.

Cortactin represents an important actin-binding factor, which controls actin-cytoskeletal remodelling in host cells. In this way, cortactin has been shown to exhibit crucial functions both for cell movement and tumour cell invasion. In addition, the cortactin gene cttn is amplified in various cancer types of humans. Helicobacter pylori is the causative agent of multiple gastric diseases and represents a significant risk factor for the development of gastric adenocarcinoma. It has been repeatedly shown that H. pylori manipulates cancer-related signal transduction events in infected gastric epithelial cells such as the phosphorylation status of cortactin. In fact, H. pylori modifies the activity of cortactin's binding partners to stimulate changes in the actin-cytoskeleton, cell adhesion and motility. Here we show that H. pylori infection of cultured AGS and Caco-2 cells for 24-48 hr leads to the overexpression of cortactin by 2-3 fold at the protein level. We demonstrate that this activity requires the integrity of the type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI) as well as the translocated effector protein CagA. We further show that ectopic expression of CagA is sufficient to stimulate cortactin overexpression. Furthermore, phosphorylation of CagA at the EPIYA-repeat region is not required, suggesting that this CagA activity proceeds in a phosphorylation-independent fashion. Inhibitor studies further demonstrate that the involved signalling pathway comprises the mitogen-activated protein kinase JNK (c-Jun N-terminal kinase), but not ERK1/2 or p38. Taken together, using H. pylori as a model system, this study discovered a previously unrecognised cortactin activation cascade by a microbial pathogen. We suggest that H. pylori targets cortactin to manipulate the cellular architecture and epithelial barrier functions that can impact gastric cancer development. TAKE AWAYS: Helicobacter pylori infection induces overexpression of cortactin at the protein level Cortactin upregulation requires the T4SS and effector protein CagA Ectopic expression of CagA is sufficient to stimulate cortactin overexpression Overexpression of cortactin proceeds CagA phosphorylation-independent The involved host cell signalling pathway comprises the MAP kinase JNK.

Quantitative acetylome and phosphorylome analysis reveals Girdin affects pancreatic cancer progression through regulating Cortactin.

The actin-binding protein Girdin is involved in a variety of cellular processes, including pancreatic cancer. The objective of this study is to explore the role and the mechanism of Girdin in pancreatic cancer by quantitative acetylome and phosphorylome analysis. We firstly found that Girdin was overexpressed in pancreatic cancer tissue and increased expression of Girdin was associated with tumor size and stage of patients with pancreatic cancer. We established the shRNA knockdown of Girdin in PANC-1 and Aspc-1 cells, and we found that shGirdin inhibited proliferation, migration and invasion, and promoted apoptosis. Subsequently, we identified and quantified 5,338 phosphorylated sites in 2,263 proteins that changed in response to Girdin knockdown, and identified a similar set of Girdin-responsive acetylome data as well. Additional data revealed that down-regulation of Girdin affected Cortactin phosphorylation and acetylation, suggesting Cortactin as an important regulatory target of Girdin. Moreover, we found that overexpression of Cortactin could rescue the effect of shGirdin on proliferation, apoptosism, migration and invasion of pancreatic cancer cells. In general, our results provided new insights into the mechanisms of Girdin function including cell proliferation, migration and invasion, and offer biomarker candidates for clinical evaluation of Girdin.

Inhibition of Src, SIRT1 or HDAC6 Reduces Transendothelial Migration of Acute Lymphoblastic Leukemia B cells

B‐cell acute lymphoblastic leukemia (B‐ALL) is the most common leukemia in children. B‐ALL cells have the ability to extravasate and infiltrate bone marrow and organs such as lungs, testis and central nervous system. Dynamic actin cytoskeletal remodeling is needed to accomplish transendothelial migration. Cortactin is an actin‐binding protein which accumulates in lamellipodia and invadopodia and regulates neutrophil transendothelial migration during inflammation. Cortactin is overexpressed in B‐cells of B‐ALL patients, and significantly correlates with bone marrow colonization, organ infiltration, drug resistance and disease relapse. Cortactin is a target of Src kinase, and the deacetylases SIRT1 and HDAC6 and as such is prone for post‐translational modifications that regulate its function and localization. Phosphorylation of cortactin at residue Y421 supports lamellipodia and invadopodia formation, whereas acetylation of cortactin diminishes its affinity for F‐actin and decreases cell migration. However, it remains to be explored whether these modifications are required for the migratory advantage that cortactin overexpression bestows on B‐ALL cells. Thus, in this project, we investigate: first, whether pharmacological inhibition of Src, HDAC6 and SIRT1 in leukemic B‐cells reduce transendothelial migration and bone marrow colonization; and second, whether these effects depend on cortactin overexpression. We found that cortactin is constitutively phosphorylated at Y421 in the pre‐B ALL cell line REH and that this phosphorylation is increased after CXCL12 stimulation over time. Of note, Src kinase inhibition with PP2 in leukemic B cells reduced phospho‐cortactin levels and impaired leukemic cell transmigration across HUVEC monolayers and BM organoid colonization. These data suggest that src‐mediated cortactin phosphorylation is required to trigger transmigration. This idea will be further corroborated using cortactin‐depleted REH cells. Moreover, SIRT1 inhibition with EX‐527 and HDAC6 inhibition with Tubastatin‐A also significantly reduced transendothelial migration and bone marrow organoid colonization suggesting that cortactin activation is also regulated by its acetylation status. Taken together, these findings highlight the importance of post‐translational modifications for the regulation of migratory processes of leukemic B cells. Future analysis of the underlying exact molecular mechanisms will contribute to a better understanding of B‐ALL disease progression.

The Role of the Actin‐Binding Protein Cortactin in the Activation of T Cells: Implications for T‐Cell Acute Lymphoblastic Leukemia

T‐cell acute lymphoblastic leukemia (T‐ALL) is an aggressive neoplasm due to high rates of organ infiltration and relapse, which are major obstacles for curing the disease. Infiltration of T‐ALL cells requires extravasation, a migratory process highly dependent on actin cytoskeleton dynamics. Cortactin is an actin‐binding protein that regulates actin remodeling and thus cell migration. Recently, we showed that cortactin overexpression in B‐cell ALL was correlated with infiltration, steroid treatment failure and relapse. However, it is unknown whether cortactin is expressed in leukemic T cells and what role it plays in T‐ALL biology. We analyzed cortactin expression in murine and human normal T cells and T‐ALL cell lines, and cortactin functions using different in vitro and in vivo methods such as transendothelial migration and xenotransplantation assays. We observed that the human leukemic T cell lines Jurkat, CEM and Molt‐3, as well as the leukemic murine T cell line 6645/4 expressed the 80 kDa WT isoform of cortactin. Importantly, all cell lines had significantly higher levels of cortactin than normal resting CD3+ cells. In addition, leukemic T cells transmigrated, infiltrated and colonized bone marrow organoids significantly more than normal T cells. Of note, in vivo xenotransplantation assays revealed that infiltrated leukemic T cells diminished cortactin expression suggesting that cortactin is needed for initial organ invasion, but not for subsequent functions within the organ. As leukemic cells display hyperactive TCR signaling, we examined cortactin and HS1 levels after activation of T cells. To this end, we used α‐CD3 and α‐CD28 to stimulate resting normal CD3+ cells and leukemic T cells, and found that in CD3+, Jurkat and CEM cells, cortactin was up‐regulated during activation (~1000 fold‐over resting) in a time‐dependent manner, reaching a peak after full activation at 72 hours. Cortactin upregulation was also seen after phorbol 12‐myristate 13‐acetate and ionomycin stimulation in all cells. Importantly, levels of the hematopoietic homologue of cortactin, HS1, diminished as cortactin expression increased in CD3+ cells. Taken together, our results show that cortactin is overexpressed in leukemic T cells to endow them with enhanced migratory abilities. Cortactin is upregulated in both leukemic and normal T cells upon activation suggesting that cortactin might be an important protein for effector functions of activated T cells such as cytokine secretion.

EPHB2 carried on small extracellular vesicles induces tumor angiogenesis via activation of ephrin reverse signaling.

Angiogenesis is a key process that allows nutrient uptake and cellular trafficking and is coopted in cancer to enable tumor growth and metastasis. Recently, extracellular vesicles (EVs) have been shown to promote angiogenesis; however, it is unclear what unique features EVs contribute to the process. Here, we studied the role of EVs derived from head and neck squamous cell carcinoma (HNSCC) in driving tumor angiogenesis. Small EVs (SEVs), in the size range of exosomes (50-150 nm), induced angiogenesis both in vitro and in vivo. Proteomic analysis of HNSCC SEVs revealed the cell-to-cell signaling receptor ephrin type B receptor 2 (EPHB2) as a promising candidate cargo to promote angiogenesis. Analysis of patient data further identified EPHB2 overexpression in HNSCC tumors to be associated with poor patient prognosis and tumor angiogenesis, especially in the context of overexpression of the exosome secretion regulator cortactin. Functional experiments revealed that EPHB2 expression in SEVs regulated angiogenesis both in vitro and in vivo and that EPHB2 carried by SEVs stimulates ephrin-B reverse signaling, inducing STAT3 phosphorylation. A STAT3 inhibitor greatly reduced SEV-induced angiogenesis. These data suggest a model in which EVs uniquely promote angiogenesis by transporting Eph transmembrane receptors to nonadjacent endothelial cells to induce ephrin reverse signaling.

Overexpression and Tyr421-phosphorylation of cortactin is induced by three-dimensional spheroid culturing and contributes to migration and invasion of pancreatic ductal adenocarcinoma (PDAC) cells

BackgroundThe nucleation-promoting factor cortactin is expressed and promotes tumor progression and metastasis in various cancers. However, little is known about the biological role of cortactin in the progression of pancreatic ductal adenocarcinoma (PDAC).MethodsCortactin and phosphorylated cortactin (Y421) were investigated immunohistochemically in 66 PDAC tumor specimens. To examine the functional role of cortactin in PDAC, we modulated cortactin expression by establishing two cortactin knockout cell lines (Panc-1 and BxPC-3) with CRISPR/Cas9 technique. Cortactin knockout was verified by immunoblotting and immunofluorescence microscopy and functional effects were determined by cell migration and invasion assays. A proteomic screening approach was performed to elucidate potential binding partners of cortactin.ResultsImmunohistochemically, we observed higher cortactin expression and Tyr421-phosphorylation in PDAC metastases compared to primary tumor tissues. In PDAC cell lines Panc-1 and BxPC-3, knockdown of cortactin impaired migration and invasion, while cell proliferation was not affected. Three-dimensional spheroid culturing as a model for collective cell migration enhanced cortactin expression and Tyr421-phosphorylation. The activation of cortactin as well as the migratory capacity of PDAC cells could significantly be reduced by dasatinib, a Src family kinase inhibitor. Finally, we identified gelsolin as a novel protein interaction partner of cortactin in PDAC.ConclusionOur data provides evidence that cohesive cell migration induces cortactin expression and phosphorylation as a prerequisite for the gain of an invasive, pro-migratory phenotype in PDAC that can effectively be targeted with dasatinib.

Prognostic and clinicopathological significance of CTTN/cortactin alterations in head and neck squamous cell carcinoma: Systematic review and meta-analysis.

To evaluate the prognostic significance of CTTN/cortactin alterations in head and neck squamous cell carcinoma (HNSCC). We searched PubMed, Embase, Web of Science, and Scopus for studies published before May 2018. We conducted a meta-analysis to quantify the impact of CTTN/cortactin alterations on clinicopathological and survival variables. Eighteen studies (1633 patients) met inclusion criteria. Quantitative evaluation revealed a strong association of CTTN/cortactin alterations with N+ status (P < .001), higher T status (P < .001), advanced clinical stage (P < .001), high histological grade (P = .001), and lower overall survival (OS) (P < .001). We found heterogeneity in T status, histological grade, and OS and observed small-study effects on N status and OS. In subgroup analyses, a significant association of CTTN amplification and cortactin overexpression with the above variables was preserved. The strongest association between CTTN/cortactin alterations and a worse outcome was observed in the subgroups of Asian patients and pharyngolaryngeal squamous cell carcinomas. CTTN/cortactin alterations should be evaluated to predict the HNSCC prognosis.

ATP13A2 facilitates HDAC6 recruitment to lysosome to promote autophagosome–lysosome fusion

Mutations in ATP13A2 cause Kufor-Rakeb syndrome, an autosomal recessive form of juvenile-onset atypical Parkinson's disease (PD). Recent work tied ATP13A2 to autophagy and other cellular features of neurodegeneration, but how ATP13A2 governs numerous cellular functions in PD pathogenesis is not understood. In this study, the ATP13A2-deficient mouse developed into aging-dependent phenotypes resembling those of autophagy impairment. ATP13A2 deficiency impaired autophagosome-lysosome fusion in cultured cells and in in vitro reconstitution assays. In ATP13A2-deficient cells or Drosophila melanogaster or mouse tissues, lysosomal localization and activity of HDAC6 were reduced, with increased acetylation of tubulin and cortactin. Wild-type HDAC6, but not a deacetylase-inactive mutant, restored autophagosome-lysosome fusion, antagonized cortactin hyperacetylation, and promoted lysosomal localization of cortactin in ATP13A2-deficient cells. Mechanistically, ATP13A2 facilitated recruitment of HDAC6 and cortactin to lysosomes. Cortactin overexpression in cultured cells reversed ATP13A2 deficiency-associated impairment of autophagosome-lysosome fusion. PD-causing ATP13A2 mutants failed to rescue autophagosome-lysosome fusion or to promote degradation of protein aggregates and damaged mitochondria. These results suggest that ATP13A2 recruits HDAC6 to lysosomes to deacetylate cortactin and promotes autophagosome-lysosome fusion and autophagy. This study identifies ATP13A2 as an essential molecular component for normal autophagy flux in vivo and implies potential treatments targeting HDAC6-mediated autophagy for PD.

Correlation of focal adhesion kinase expression with nodal metastasis in patients with head and neck cutaneous squamous cell carcinoma.

Focal adhesion kinase (FAK) and cortactin overexpression is frequently detected in a variety of cancers, and has been associated with poor clinical outcome. However, there are no data in cutaneous squamous cell carcinoma (cSCC). To investigate the relationship of FAK and cortactin expression with the clinicopathologic features and the impact on the prognosis of cSCC patients. FAK and cortactin expression was analyzed by immunohistochemistry on paraffin-embedded tissue samples from 100 patients with cSCC, and correlated with the clinical data. FAK overexpression was a significant risk factor for nodal metastasis with crude and adjusted ratios (HRs) of 2.04, (95% CI [1.08-3.86], [P = 0.029]) and 2.23 (95% CI [1.01-4.91], [P = 0.047]), respectively. Cortactin expression was not a significant risk factor for nodal metastasis. These findings demonstrate that FAK overexpression is an independent predictor of nodal metastasis that might be helpful for risk stratification and management of patients with cSCC.

Cortactin expression: Association with disease progression and survival in oral squamous cell carcinoma.

Cortactin (CTTN) is located on chromosome 11q13 and is associated with invasiveness in various cancer entities. CTTN protein expression could be a prognosticator of oral squamous cell carcinoma (OSCC) in terms of recurrence and survival. CTTN-dependent invasion was performed using migration assay in human papillomavirus-negative head and neck squamous cell carcinoma (HNSCC) cells. Cortactin protein analysis in tissue microarrays was used for correlation with clinical parameters, as well as for survival analysis. Gene expression profiling in HNSCC cells was performed to unreveal CTTN signaling. Knockdown of CTTN in HNSCC cells showed less invasion in vitro. Gene expression profiling showed various deregulated genes known to be involved in progression. We confirmed the link between CTTN overexpression and progression in a large clinical cohort. High expression was associated with worse overall and progression-free survival. We propose CTTN for managing OSCC in terms of adjuvant therapy and aftercare. Furthermore, our study reveals new potential targets in CTTN signaling for individualized OSCC therapy.

Abnormal regulation of BCR signalling by c-Cbl in chronic lymphocytic leukaemia.

Abnormalities of molecules involved in signal transduction pathways are connected to Chronic Lymphocytic Leukemia (CLL) pathogenesis and a critical role has been already ascribed to B-Cell Receptor (BCR)-Lyn axis. E3 ubiquitin ligase c-Cbl, working together with adapter protein CIN85, controls the degradation of protein kinases involved in BCR signaling. To investigate cell homeostasis in CLL, we studied c-Cbl since in normal B cells it is involved in the ubiquitin-dependent Lyn degradation and in the down-regulation of BCR signaling. We found that c-Cbl is overexpressed and not ubiquitinated after BCR engagement. We observed that c-Cbl did not associate to CIN85 in CLL with respect to normal B cells at steady state, nor following BCR engagement. c-Cbl association to Lyn was not detectable in CLL after BCR stimulation, as it happens in normal B cells. In some CLL patients, c-Cbl is constitutively phosphorylated at Y731 and in the same subjects, it associated to regulatory subunit p85 of PI3K. Moreover, c-Cbl is constitutive associated to Cortactin in those CLL patients presenting Cortactin overexpression and bad prognosis. These results support the hypothesis that c-Cbl, rather than E3 ligase activity, could have an adaptor function in turn influencing cell homeostasis in CLL.

Cortactin as a potential predictor of second esophageal neoplasia in hypopharyngeal carcinoma

ObjectiveHypopharyngeal carcinoma has a very poor prognosis. The high incidence of second esophageal neoplasia is one of the major causes. To establish an efficient follow-up scheme for increasing the diagnostic yield and reducing the adverse impact of second esophageal neoplasia on survival, the purpose of this study was to explore a biomarker to predict second esophageal neoplasia. MethodsIn this retrospective cohort study, consecutive tissue specimens from those patients who underwent tumor resection between September 2007 and October 2015 were collected. Gene amplification was performed by real-time PCR. The expression of cortactin was evaluated by immunohistochemistry. The predictive risk factors of developing second esophageal neoplasia and prognostic factors related to survival were analyzed. ResultsA total of 187 patients were included with a mean follow-up of 48months (12–118months). Second esophageal tumors were found in 53 (28.3%), including 41 (21.9%) esophageal squamous cell carcinoma and 12 severe dysplasia. The results of multivariate analyses revealed that age (OR 2.81, 95% CI 1.16–6.78), cortactin overexpression (OR 2.49, 95% CI 1.17–5.33), and stage IV versus I (OR 6.49, 95% CI 1.68–25.18) were independent predictors of second esophageal neoplasia, and second esophageal neoplasia (HR 1.78, 95% CI 1.05–3.01) was an independent predictor of overall survival. ConclusionThis is the first report to identify a potential biomarker for predicting second esophageal neoplasia in patients with hypopharyngeal carcinoma. In those patients with cortactin overexpression and younger age (≤60years old), close surveillance for second esophageal neoplasia is required. In addition, the real effect of cortactin overexpression on development of primary esophageal carcinoma is required to be validated in a large cohort study.