Key proteins of invadopodia are overexpressed in oral squamous cell carcinoma suggesting an important role of MT1-MMP in the tumoral progression.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is the most relevant malignant neoplasm among all head and neck tumours due to its high prevalence and unfavourable prognosis. Tumour invasion and metastasis that affect prognosis are result of a set of complex events that cells with invasive potential use to spread to other regions. These cells use several mechanisms to invade tissues, including a type of finger-like membrane protrusion called invadopodia. This study aims to investigate the immunoexpression of invaopodia related-proteins TKs5, cortactin, TKs4 and MT1-MMP in OSCC and correlate it to clinicopathological data. METHODS: An immunohistochemical evaluation of fifty cases of OSCCs and 20 cases of oral mucosa (OM) were assessed. The expression of invadopodia proteins were analysed in comparison to normal tissue (OM) and correlated to different clinical-stage and histological grade of OSCC. RESULTS: TKs5, cortactin, TKs4 and MT1-MMP were significantly overexpressed in OSCC when compared to OM (p < 0.0001). Among tumour stages, TKs5 showed a statistical difference in immunolabelling between stage I and III (p = 0.026). Cortactin immunolabelling was statistically higher in grade I than in grade II and III. No differences were seen on TKs4 expression based on tumour staging or grading. MT1-MMP was higher expressed and showed statistical difference between stages I and III and grades I compared to II and III. CONCLUSIONS: The invadopodia related-proteins were found to be overexpressed in OSCC when compared to OM, suggesting invadopodia formation and activity. Besides overexpressed in OSCC, cortactin, TKs4 and TKs5 showed no or ambiguous differences in protein expression when compared among clinical-stages or histological grades groups. Conversely, the expression of MT1-MMP increased in advanced stages and less differentiated tumours, suggesting MT1-MMP expression as a promising prognostic marker in OSCC.

TKS5-positive invadopodia-like structures in human tumor surgical specimens.

Invadopodia, cancer cell protrusions with proteolytic activity, are functionally associated with active remodeling of the extracellular matrix. Here, we show that the invadopodia-related protein TKS5 is expressed in human pancreatic adenocarcinoma lines, and demonstrate that pancreatic cancer cells depend on TKS5 for invadopodia formation and function. Immunofluorescence staining of human pancreatic cancer cells reveals that TKS5 is a marker of mature and immature invadopodia. We also analyze the co-staining patterns of TKS5 and the commonly used invadopodia marker Cortactin, and find only partial co-localization of these two proteins at invadopodia, with a large fraction of TKS5-positive invadopodia lacking detectable levels of Cortactin. Whereas compelling evidence exist on the role of invadopodia as mediators of invasive migration in cultured cells and in animal models of cancer, these structures have never been detected inside human tumors. Here, using antibodies against TKS5 and Cortactin, we describe for the first time structures strongly resembling invadopodia in various paraffin-embedded human tumor surgical specimens from pancreas and other organs. Our results strongly suggest that invadopodia are present inside human tumors, and warrants further investigation on their regulation and occurrence in surgical specimens, and on the value of TKS5 antibodies as pathological research and diagnostic tools.

ATM-Mediated Phosphorylation of Cortactin Involved in Actin Polymerization Promotes Breast Cancer Cells Migration and Invasion.

BACKGROUND/AIMS: The ataxia-telangiectasia mutated (ATM) protein kinase is critical for the maintenance of genomic stability and acts as tumor suppressor. Although evidence shows that a DNA damage-independent ATM (oxidized ATM) may be involved in cancer progression, the underlying mechanism is still unclear. METHODS: Immunohistochemistry, immunofluorescence and western blotting were applied to detect the levels of oxidized ATM. Transwell assay was used to detect the cell migration and invasion abilities in different treatments. Quantitative phosphoproteome analysis was performed using hypoxic BT549 cells, in the presence or absence of Ku60019, a specific inhibitor of ATM kinase. The phosphorylated cortactin, the target protein of oxidized ATM, was confirmed by immunoprecipitation-western blots and in vitro kinase assay. The functions of phosphorylated cortactin were studied by specific short hairpin RNA, site-directed mutation, transwell assay, and actin polymerization assay. RESULTS: Enhanced oxidized ATM proteins were present not only in the advanced and invasive breast tumor tissues but also malignant hypoxic breast cancer cells, in the absence of DNA damage. Loss of ATM expression or inhibiting oxidized ATM kinase activity reduced breast cancer cell migration and invasion. Using quantitative phosphoproteomics approach, 333 oxidized ATM target proteins were identified, some of these proteins govern key signaling associated with gap junction, focal adhesion, actin cytoskeleton rearrangement. Cortactin, one of the biggest changed phospho-protein, is a novel oxidized ATM-dependent target in response to hypoxia. Mechanically, we reveal that hypoxia-activated ATM can enhance the binding affinity of cortactin with Arp2/3 complex by phosphorylating cortactin at serine 113, and as a result, in favor of breast cancer cell migration and invasion. CONCLUSION: Oxidized ATM can phosphorylate cortactin at serine 113, playing a critical role in promoting breast tumor cell mobility and invasion via actin polymerization.

Expression and clinical significance of cortactin protein in ovarian neoplasms.

OBJECTIVE: To examine the expression of cortactin in epithelial ovarian cancer, and discuss the relationship between the expression of cortactin and the clinical pathology characteristics in epithelial ovarian cancer, as well as clinical significance. METHODS: The expression of cortactin was detected using real-time fluorescence quantitative PCR and immunohistochemical SP method in epithelial ovarian cancer. RESULTS: (1) The relative content of cortactin mRNA in epithelial ovarian cancer tissue was higher than that in benign control tissue, and expression was related to histological classification and FIGO stage. (2) Cortactin protein was localized in the cytoplasm and membrane of tumor cells. The positive rate of cortactin was 73.3 % in epithelial ovarian cancer, and the rate of cortactin expression was related to histological classification. (3) The average survival period of epithelial ovarian cancer patients with positive expression of cortactin was 19.5 ± 1.2 months (95 % CI 14.6-21.4 months), compared with 34.5 ± 4.3 months in the negative expression group (95 % CI 22.1-25.9 months). Univariate survival analysis showed that: negative expression of cortactin had a significant survival advantage (χ (2) = 5.739, P = 0.017). A cox regression model for multivariate analysis revealed that cortactin was an independent prognostic factor for epithelial ovarian cancer (P = 0.001; RR = 6.452, 95 % CI 2.289-7.112). CONCLUSIONS: Negative expression of cortactin was an independent prognostic factor and had a survival advantage. This suggested that cells with poor differentiation showed increasing motility. Cortactin is closely related to poor prognosis.

Vascular endothelial growth factor-C upregulates cortactin and promotes metastasis of esophageal squamous cell carcinoma.

BACKGROUND: Vascular endothelial growth factor-C (VEGF-C) plays an important role during cancer progression and metastasis through activation of VEGF receptors. However, the role of VEGF-C in esophageal squamous cell carcinoma (ESCC) remains unclear. METHODS: The expression of VEGF-C in advanced stages of esophageal cancer was examined by immunohistochemistry and its expression was correlated with the protein level of cortactin (CTTN) by Western blot. Knockdown and overexpression of the CTTN protein were respectively performed to investigate the effects on VEGF-C-enhanced ESCC migration/invasion by in vitro transwell assay, cell tracing assay, and tumor growth/experimental metastasis in animal models. RESULTS: The expression of VEGF-C was positively correlated with tumor status and poor clinical prognosis in patient with esophageal cancer. VEGF-C-upregulated CTTN expression contributed the migration/invasive abilities of ESCC cell lines through Src-mediated downregulation of miR-326. Moreover, knockdown of CTTN expression significantly abolished VEGF-C-induced tumor growth and experimental lung metastasis in vivo. CONCLUSIONS: Upregulation of CTTN is critical for VEGF-C-mediated tumor growth and metastasis of ESCC. These finding suggest that VEGF-C upregulated CTTN expression through Src-mediated downregulation of miR-326. CTTN may be a crucial mediator of VEGF-C-involved ESCC metastasis, which provides a potential target for diagnosis and individualized treatment in clinical practice.

Expression of SIRT1 and cortactin is associated with progression of non-small cell lung cancer.

Cortactin is an F-actin binding protein involved in cell migration and tumor metastasis. Recent reports suggest that silent mating-type information regulation 2 homologue 1 (sirtuin1; SIRT1) enhances the function of cortactin and promotes cell migration. We investigated SIRT1 and cortactin expression in 144 invasive non-small cell lung cancers (NSCLC) and 19 adenocarcinomas in situ (AIS) by immunohistochemistry and evaluated their clinicopathological significance in NSCLC. Positive SIRT1 and cortactin expression was observed in 67% (96 of 144) and 58% (84 of 144) of patients with invasive NSCLC, respectively. SIRT1 and cortactin expression was significantly associated with unfavorable clinicopathological factors, including high pathological T stage, lymph node metastasis, and advanced tumor invasion (AIS vs. invasive adenocarcinoma). Cortactin was significantly associated with high pathological T stage and lymph node metastasis in SIRT1-positive tumors. Cytoplasmic SIRT1 was significantly associated with high pathological T stage and large tumor size compared to that of nuclear SIRT1. Large tumor size, high pathological T stage, lymph node metastasis, and cytoplasmic SIRT1 expression were significantly associated with shorter overall survival in a univariate analysis. Our findings suggest that SIRT1 and cortactin may play a role in the progression of NSCLC and may cooperate during tumor progression in NSCLC.

Prognostic significance of Tks5 expression in gliomas.

A pathological hallmark of gliomas is their extensive invasion into the brain parenchyma regardless of tumour grade. Clinically this is a major factor in tumour recurrence as surgery and adjuvant therapies are unable to eradicate all the infiltrating malignant cells. Tyrosine kinase substrate with five SH3 domains (Tks5, also known as SH3PXD2A) and cortactin are required for the formation of invadopodia, actin-based protrusions of tumour cells with associated proteolytic activity implicated in tumour invasion. We investigated the prognostic significance of Tks5 and cortactin expression in 57 patients with various grades of glioma. Expression of Tks5 or cortactin occurred in all grades of tumours and expression of Tks5, but not cortactin, was associated with significantly reduced patient survival among glioma patients. This association was clearest in patients with low-grade astrocytomas and oligoastrocytomas. These results suggest a prognostic relevance for the Tks5 invadopodial protein in glial-derived brain tumours.

VEGF and cortactin expression are independent predictors of tumor recurrence following curative resection of gastric cancer.

INTRODUCTION: To investigate the clinicopathological role of expression of vascular endothelial growth factor (VEGF) and cortactin, as well as whether their expression are independent predictors of tumor recurrence following curative resection of gastric cancer. METHODS: One hundred twenty-eight patients with gastric cancer were included in this study. Formalin-fixed paraffin-embedded specimens were stained for VEGF and cortactin, and the correlation between the staining, clinicopathological parameters and prognostic power were analyzed. RESULTS: Of the 128 patients studied, 58 (45.3%) and 71 (55.5%) cases were strongly positive for VEGF and cortactin, respectively. VEGF expression correlated with Lauren classification (P < 0.001), pathological tumor stage (P < 0.001), and pathological tumor node metastasis (TNM) stage (P = 0.003). Cortactin expression correlated with pathological lymph node stage (P = 0.018), pathological TNM stage (P < 0.001), and degree of differentiation (P < 0.001). There were statistically significant associations between tumor recurrence and VEGF expression (P = 0.023), and cortactin expression (P < 0.001). In multivariate analysis, pathological TNM stage, VEGF expression, and cortactin expression were independent prognostic influence on disease-free survival (P < 0.001, 0.022, and 0.034, respectively). CONCLUSIONS: VEGF and cortactin may be a good biomarker to be applied in clinic to predict the prognosis of patients with curatively resected gastric cancer.

Cortactin gene amplification and expression in breast cancer: a chromogenic in situ hybridisation and immunohistochemical study.

Amplification of 11q13 is found in approximately 15% of breast cancers. Cyclin D1 (CCND1) has been reported to be the 'driver' of this amplicon, however, multiple genes map to the smallest region of amplification of 11q13. Out of these genes, cortactin (CTTN) has been shown to be consistently overexpressed at the mRNA level in tumours harbouring 11q13 amplification. The aims of this study are to define whether CTTN is consistently co-amplified with the main core of the 11q13 amplicon, whether it is consistently overexpressed when amplified and to determine correlations between CTTN amplification and overexpression with clinicopathological features of breast cancers and survival of breast cancer patients. CTTN and CCND1 chromogenic in situ hybridisation (CISH) probes and a validated monoclonal antibody against CTTN were applied to a tissue microarray of a cohort of breast cancers from patients treated with anthracycline-based chemotherapy. CTTN and CCND1 amplifications were found in 12.3 and 12.4% of cases, respectively. All cases harbouring CTTN amplification also displayed CCND1 amplification. High expression of CTTN was found in 10.8% of cases and was associated with CTTN amplification, expression of 'basal' markers and topoisomerase IIα. Exploratory subgroup analysis of tumours devoid of 11q13 amplification revealed that high expression of CTTN in the absence of CTTN gene amplification was associated with lymph node negative disease, lack of hormone receptors and FOXA1, expression of 'basal' markers, high Ki-67 indices, p53 nuclear expression, and basal-like and triple negative phenotypes. CTTN expression and CTTN gene amplification were not associated with disease-, metastasis-free and overall survival. In conclusion, CTTN is consistently co-amplified with CCND1 and expressed at higher levels in breast cancers harbouring 11q13 amplification, suggesting that CTTN may also constitute one of the drivers of this amplicon. CTTN expression is not associated with the outcome of breast cancer patients treated with anthracycline-based chemotherapy.

Epidermal growth factor-dependent enhancement of invasiveness of squamous cell carcinoma of the breast.

Factors that promote the aggressiveness of squamous cell carcinoma of the breast are not well understood. To examine the involvement of cell motility and the mechanism of this behavior, a squamous cell carcinoma cell line of the breast (HBC9) was established from a metastatic lymph node of a Japanese woman. HBC9 expressed epidermal growth factor receptor (EGFR), but was negative for Her2 or Her3.The invasive ability of HBC9 was compared with that of four breast ductal carcinoma cell lines by Matrigel invasion assay. EGF stimulation induced the formation of surface protrusions and cell migration in HBC9 cells, and significantly increased the number of cells migrating through the Matrigel. The invasive ability of HBC9 was compared with other cell lines of breast carcinoma; it was much greater than that of MCF-7, BT474, or HBC5, but did not differ significantly from that of MDA-MB-231. Observation of the surface protrusions of HBC9 by confocal laser microscopy revealed co-localization of Arp2 and N-WASP with actin polymerization, detected by visualization with phalloidin, indicating that the protrusions induced by EGF were invadopodia. In HBC9 cells, cortactin also co-localized with the N-WASP/Arp2/3 complex in the protrusions. Immunohistochemistry of 12 cases of squamous cell carcinoma of the breast revealed expression of cortactin and EGFR in all of them, and this was confirmed by western blotting in two cases. These results suggest that EGF-dependent enhancement of cell motility by formation of invadopodia associated with cortactin is a cause of the clinical aggressiveness of squamous cell carcinoma of the breast.

Cortactin, fascin and survivin expression associated with clinicopathological parameters in brain gliosarcoma.

Gliosarcoma is a very rare primary neoplasm of the central nervous system classified as a variant of glioblastoma. Cortactin, fascin and survivin have been found in several human cancers to play important roles in tumor progression, but the expression pattern of these biomarkers in gliosarcoma is unclear. Immunostaining for cortactin, fascin and survivin was assessed in 6 surgical specimens of brain gliosarcoma, and the relationship between the expression of these biomarkers and tumor size or clinical parameters were examined. Five of our six patients with gliosarcoma survived 3-17 months. One patient is still alive for more than 24 months. The mean immunostaining scores for cortactin were significantly higher in the gliomatous (score 236.6 +/- 45.4) and sarcomatous (score 233.3 +/- 51.4) components than in normal brain tissues (score 21.6 +/- 6.6). The mean cytoplasmic immunostaining scores for fascin and survivin were also significantly higher in the gliomatous and sarcomatous components than in normal brain tissues. In addition, survivin was also stained in the nucleus of tumor cells. Linear regression analysis showed that fascin score in the gliomatous component was significantly associated with tumor size (R = 0.69) and the fascin score in the sarcomatous component was significantly associated with patient's age (R = 0.87). In addition, the survivin cytoplasmic scores in the gliomatous and sarcomatous components were inversely associated with tumor size. Our results demonstrated that over-expression of cortactin, fascin and survivin is associated with malignant transformation of brain gliosarcoma. Development of drugs that target cortactin, fascin and survivin expression may be therapeutic to patients with gliosarcoma.

Cortactin, fascin, and survivin expression associated with clinicopathological parameters in esophageal squamous cell carcinoma.

Cortactin, fascin, and survivin have been documented in several human cancers and play important roles in tumor progression. We collected 57 surgical specimens, including esophageal squamous cell carcinomas (SqCC; 7 well-differentiated, 15 moderately differentiated, and 24 poorly differentiated), 3 dysplasias, and 8 normal esophageal tissues. Tissue microarrays were constructed and the immunostaining scores for cortactin, fascin, and survivin were assessed. In 46 SqCC specimens, we examined the relationship between the expression of three biomarkers and tumor differentiation or clinical parameters. Higher immunostaining scores for cortactin, fascin, and survivin correlated positively with tumor differentiation of esophageal SqCC. Univariate survival analysis showed significantly worse prognosis in patients with high scores of cortactin (>or=290), fascin (>or=245), and survivin (score >or= 175), poor differentiation, T4 stage, positive for lymph node metastasis, and positive for distant metastasis. In multivariate survival analysis, high scores of survivin (>or=175) and poor differentiation were independent risk factors for worse prognosis. Our results demonstrated that higher expression of survivin may be related to tumor progression and it is an independent risk factor for poor survival time of esophageal SqCC. Survivin may be a good biomarker to be applied in clinic to predict the prognosis of esophageal SqCC.

Distinctive clinicopathological associations of amplification of the cortactin gene at 11q13 in head and neck squamous cell carcinomas.

Amplification of the 11q13 region is a prevalent genetic alteration in head and neck squamous cell carcinoma (HNSCC). We investigated the clinical significance of cortactin (CTTN) and cyclin D1 (CCND1) amplification in both malignant transformation and tumour progression. CTTN and CCND1 amplification was analysed by differential and real-time PCR in a prospective series of laryngeal/pharyngeal carcinomas and archival premalignant tissues. CTTN mRNA and protein expression were respectively determined by real-time RT-PCR and immunohistochemistry, and correlated with gene status. Molecular alterations were associated with clinicopathological parameters and disease outcome. CTTN and CCND1 amplifications were respectively found in 75 (37%) and 90 (45%) tumours. Both correlated with advanced disease; however, only CTTN amplification was associated with recurrence and reduced disease-specific survival (p = 0.0022). Strikingly, CTTN amplification differentially influenced survival depending on tumour site (p = 0.0001 larynx versus p = 0.68 pharynx) and was an independent predictor of reduced survival in the larynx (p = 0.04). CCND1 amplification was detected in early tumourigenesis and increased with the severity of dysplasia. Importantly, CTTN amplification was only found in high-grade dysplasias that progressed to invasive carcinoma. CTTN gene status strongly correlated with mRNA and protein expression. Furthermore, CTTN overexpression correlated significantly with reduced disease-specific survival (p = 0.018). Taken together, these data indicate that CTTN may serve as a valuable biomarker to identify patients with laryngeal tumours at high risk of recurrence and poor outcome.

Aberrant expression of cortactin and fascin are effective markers for pathogenesis, invasion, metastasis and prognosis of gastric carcinomas.

Tumor metastasis depends on cell adhesiveness, motility and deformability, resulting from quantitative alterations and rearrangement of various actin-binding cytoskeletal components, such as cortactin and fascin. To clarify the involvement of cortactin and fascin expression in tumorigenesis and progression of gastric carcinoma, we performed immunohistochemistry (IHC) on tissue microarray containing gastric carcinomas, adenomas and adjacent non-neoplastic mucosa (ANNM) using the antibodies against cortactin (Ab-466, -421) and fascin as well as a comparison of their expression with clinicopathological parameters of the tumors. Gastric carcinoma cell lines MKN28, AGS, MKN45, KATO-III and HGC-27 were studied for both proteins by IHC. Cortactin-466 was found to be highly expressed in adenoma, compared with ANNMs and carcinoma (p<0.05), and more frequently in ANNMs than in carcinoma (p<0.05). Cortactin-421 expression was higher in gastric carcinomas than in adenoma and ANNMs (p<0.05). There was increased fascin expression in gastric carcinoma and adenoma than in ANNMs (p<0.05). Most of the gastric carcinoma cell lines showed expression of cortactin and fascin at different levels. Cortactin-466 expression was inversely correlated with tumor size, depth of invasion, lymphatic and venous invasion, lymph node metastasis and UICC staging (p<0.05). The converse was observed for cortactin-421 and fascin (p<0.05). There was stronger positivity of both cortactins in intestinal- versus diffuse-type carcinomas (p<0.05). Univariate analysis indicated the cumulative survival rate of patients with positive cortactin-466 expression to be higher than without its expression even stratified according to the depth of invasion (p<0.05). However, it was the converse for fascin (p<0.05). Multivariate analysis showed that age, depth of invasion, lymphatic invasion, lymph node metastasis, UICC staging and Lauren's classification were independent prognostic factors for carcinomas (p<0.05). It was suggested that aberrant expression of cortactin and fascin possibly contributes to the pathogenesis, growth, invasion and metastasis of gastric carcinomas. Thus, they may be objective and effective markers to indicate the pathobiological behaviors and prognosis of gastric carcinomas.

Identification of disulfide-containing chemical cross-links in proteins using MALDI-TOF/TOF-mass spectrometry.

Cross-linking can be used to identify spatial relationships between amino acids in proteins or protein complexes. A rapid and sensitive method for identifying the site of protein cross-linking using dithiobis(sulfosuccinimidyl propionate) (DTSSP) is presented and illustrated with experiments using murine cortactin, actin and acyl-CoA thioesterase. A characteristic 66 Da doublet, which arises from the asymmetric fragmentation of the disulfide of DTSSP-modified peptides, is observed in the mass spectra obtained under MALDI-TOF/TOF-MS conditions and allows rapid assignment of cross-links in modified proteins. This doublet is observed not only for linear cross-linked peptides but also in the mass spectra of cyclic cross-linked peptides when simultaneous fragmentation of the disulfide and the peptide backbone occurs. We suggest a likely mechanism for this fragmentation. We use guanidinylation of the cross-linked peptides with O-methyl isourea to extend the coverage of cross-linked peptides observed in this MALDI-MS technique. The methodology we report is robust and amenable to automation, and permits the analysis of native cystines along with those introduced by disulfide-containing cross-linkers.

[Expression and clinical significance of EMS1 gene in gastric carcinoma].

BACKGROUND & OBJECTIVE: EMS1 (chromosome eleven, band q13, mammary tumor and squamous cell carcinoma-associated gene 1) is correlated to the genesis, progression, invasion and metastasis of some malignancies. This study was to investigate the expression of EMS1 protein in gastric carcinoma, and to explore its correlation to the carcinogenesis of gastric carcinoma. METHODS: The expression of EMS1 protein in 20 specimens of normal gastric mucosa, 38 specimens of intraepithelial neoplasia, and 146 specimens of gastric carcinoma was detected by immunohistochemistry. RESULTS: EMS1 protein was expressed in cytoplasm. The positive rate of EMS1 protein was significantly higher in gastric carcinoma than in intraepithelial neoplasia and normal gastric mucosa (89.7% vs. 68.4% and 20.0%, P<0.001), and significantly higher in intraepithelial neoplasia than in normal gastric mucosa (P<0.001). The positive rate of EMS1 protein was significantly lower in the gastric carcinomas at early stages than in those at advanced stages (60.9% vs. 95.1%, P<0.001), and significantly higher in the gastric carcinomas with lymph node metastases than in those without lymph node metastases (96.8% vs. 77.0%, P<0.001). EMS1 protein expression had no correlations to sex, age, tumor differentiation and diameter. CONCLUSION: EMS1 protein expression is related to the carcinogenesis, lymph node metastasis and clinical stage of gastric carcinoma.

Cortactin expression predicts poor survival in laryngeal carcinoma.

Amplification of the 11q13 region is one of the most frequent aberrations in squamous cell carcinomas of the head and neck region (HNSCC). Amplification of 11q13 has been shown to correlate with the presence of lymph node metastases and decreased survival. The 11q13.3 amplicon carries numerous genes including cyclin D1 and cortactin. Recently, we reported that FADD becomes overexpressed upon amplification and that FADD protein expression predicts for lymph node positivity and disease-specific mortality. However, the gene within the 11q13.3 amplicon responsible for this correlation is yet to be identified. In this paper, we compared, using immunohistochemical analysis for cyclin D1, FADD and cortactin in a series of 106 laryngeal carcinomas which gene correlates best with lymph node metastases and increased disease-specific mortality. Univariate Cox regression analysis revealed that high expression of cyclin D1 (P=0.016), FADD (P=0.003) and cortactin (P=0.0006) predict for increased risk to disease-specific mortality. Multivariate Cox analysis revealed that only high cortactin expression correlates with disease-specific mortality independent of cyclin D1 and/or FADD. Of genes located in the 11q13 amplicon, cortactin expression is the best predictor for shorter disease-specific survival in late stage laryngeal carcinomas.

Prognostic significance of cortactin levels in head and neck squamous cell carcinoma: comparison with epidermal growth factor receptor status.

Cortactin is an actin-binding Src substrate involved in cell motility and invasion. In this study, we sought to examine the prognostic importance of cortactin protein expression in head and neck squamous cell carcinoma (HNSCC). To do so, cortactin and EGF receptor (EGFR) expression was retrospectively evaluated by immunohistochemistry in a tissue microarray composed of 176 HNSCCs with a mean follow-up time of 5 years. Cortactin immunoreactivity was weak to absent in normal epithelial tissue. Overexpression of the protein in 77 out of 176 tumours (44%) was associated with more advanced tumour-node-metastasis stage and higher histologic grade. Cortactin overexpression was associated with significantly increased local recurrence rates (49 vs 28% for high and low expressing carcinomas, respectively), decreased disease-free survival (17 vs 61%), and decreased the 5-year overall survival of (21 vs 58%), independently of the EGFR status. In multivariate analysis, cortactin expression status remained an independent prognostic factor for local recurrence, disease-free survival, and overall survival. Importantly, we identified a subset of patients with cortactin-overexpressing tumours that displayed low EGFR levels and a survival rate that equalled that of patients with tumoral overexpression of both EGFR and cortactin. These findings identify cortactin as a relevant prognostic marker and may have implications for targeted therapies in patients with HNSCC.

Actin filament organization of foot processes in vertebrate glomerular podocytes.

We investigated the actin filament organization and immunolocalization of actin-binding proteins (alpha-actinin and cortactin) in the podocyte foot processes of eight vertebrate species (lamprey, carp, newt, frog, gecko, turtle, quail, and rat). Three types of actin cytoskeleton were found in these foot processes. (1) A cortical actin network with cortactin filling the space between the plasma membrane and the other actin cytoskeletons described below was found in all of the species examined here. The data indicated that the cortical actin network was the minimal essential actin cytoskeleton for the formation and maintenance of the foot processes in vertebrate podocytes. (2) An actin bundle with alpha-actinin existing along the longitudinal axis of foot process above the level of slit diaphragms was only observed in quail and rat. (3) An actin fascicle consisting of much fewer numbers of actin filaments than that of the actin bundle was observed in the species other than quail and rat, but at various frequencies. These findings suggest that the actin bundle is an additional actin cytoskeleton reflecting a functional state peculiar to quail and rat glomeruli. Considering the higher intraglomerular pressure and the extremely thin filtration barrier in birds and mammals, the foot processes probably mainly protect the thinner filtration barrier from the higher internal pressure occurring in quail and rat glomeruli. Therefore, we consider that the actin bundle plays a crucial role in the mechanical protection of the filtration barrier. Moreover, the actin fascicle may be a potential precursor of the actin bundle.