Immunohistochemical Glucagon-like Peptide-1 Receptor Expression in Human Insulinomas

Insulinomas are rare functional pancreatic neuroendocrine tumours, which metastasize in 10% of cases. As predicting the prognosis can be challenging, there is a need for the determination of clinicopathological factors associated with metastatic potential. The aim of this study is to evaluate the glucagon-like peptide-1 receptor (GLP-1R) expression in insulinomas and to analyse its association with clinicopathological features and patient outcome. This retrospective study involves pancreatic tumour tissue samples from fifty-two insulinoma patients. After histological re-evaluation, formalin-fixed paraffin-embedded tissue samples were processed into tissue microarrays and stained immunohistochemically with a monoclonal GLP-1R antibody. Forty-eight of the forty-nine (98%) non-metastatic tumours expressed GLP-1R, while one non-metastatic, multiple endocrine neoplasia type 1 (MEN1)-related tumour and all three of the metastatic tumours lacked GLP-1R expression. The lack of GLP-1R expression was associated with impaired overall survival, larger tumour diameter, higher Ki-67 PI and weaker insulin staining. Somatostatin receptor 1-5 expression did not differ between GLP-1R-positive and GLP-1R-negative insulinomas. In conclusion, the lack of GLP-1R expression is associated with metastatic disease and impaired survival in insulinoma patients. Thus, GLP-1R expression could be a useful biomarker in estimating the metastatic potential of the tumour and the prognosis of surgically treated patients.

Case report and review: Angiosarcoma with thrombocytopenia after total hip arthroplasty

Total hip arthroplasty (THA) is a common treatment for osteoarthritis and is also performed for other conditions, such as secondary arthritis due to developmental dysplasia of the hip. Various THA types may be complicated by osteolysis and an inflammatory pseudotumor due to an adverse reaction to metal debris. Rarely, THA has been associated with malignant tumors, but their causality remains unclear. In this case report, we describe a female patient with developmental dysplasia of the hip. She had undergone left metal-on-polyethylene THA, acetabular revision of the THA, and left total knee arthroplasty. In addition, she had a history of dyslipidemia and telangiectasia of the eyes, anemia, hiatal hernia, and pleuritis. A THA-associated mass (suspected to be a pseudotumor) had been detected during a previous hospital admission due to pleuritis. She was hospitalized due to swelling in her left lower limb, fatigue, and bruises. A clinical examination revealed anemia, thrombocytopenia, and growth of the suspected pseudotumor. Within 6 weeks, she presented with bleeding of the oral mucosa, hemoptysis, melena, severe thrombocytopenia that did not respond to treatment, elevated D-dimer and C-reactive protein levels, severe pain, increased osteolysis, and fractures around the THA. Infection or malignancy was suspected, but two trocar biopsies suggested an inflammatory pseudotumor. Since her anemia and thrombocytopenia were considered to have been caused by an inflammatory process within the suspected pseudotumor, her suspected pseudotumor and all THA components were surgically removed. However, she developed severe alveolar hemorrhaging and hypoxia and died 2 weeks after her surgery. Histopathological analysis of her surgical and autopsy samples revealed highly malignant angiosarcoma. Although individual cases of malignancies associated with THA have been reported, the literature lacks a clear association between THA and increased cancer risk. Most pseudotumors are non-malignant. The patient's case presented in this report exemplifies the challenges to the differential diagnosis of a THA-associated pseudotumor and rare angiosarcoma. Atypically rapid tumor growth, severe osteolysis, and deterioration in the general wellbeing suggest a malignant disease.

Immunohistochemical somatostatin receptor expression in insulinomas

Insulinomas are rare pancreatic neuroendocrine tumours. Most patients can be cured with surgery, but patients with a metastatic disease show impaired survival. The aim of this study was to evaluate somatostatin receptor (SSTR) 1-5 expression in insulinomas and to correlate the expression profile with clinicopathological variables and with patient outcome. This retrospective study involved 52 insulinoma patients. After histological re-evaluation, formalin-fixed paraffin-embedded tissue samples were processed into tissue microarrays and stained immunohistochemically with monoclonal SSTR1-5 antibodies. All the 52 tumours (49 non-metastatic, 3 metastatic) expressed at least one SSTR subtype. SSTR2 was expressed most frequently (71%), followed by SSTR3 (33%), SSTR1 (27%), SSTR5 (6%) and SSTR4 (0%). SSTR3 expression was associated with a larger tumour size (median diameter 19 mm vs. 13 mm, p = 0.043), and SSTR3 and SSTR5 expression were associated with impaired overall survival [HR 3.532 (95% CI 1.106-11,277), p = 0.033, and HR 6.805 (95% CI 1.364-33.955), p = 0.019 respectively]. Most insulinomas express SSTR2, which may be utilized in diagnostic imaging, and in planning individualized treatment strategies for insulinoma patients. Further studies are needed to clarify the association between SSTR profile and overall survival.

Association of CT findings with invasive subtypes and the new grading system of lung adenocarcinoma

AIM

To predict the differentiation between invasive growth patterns and new grades of lung adenocarcinoma (LAC) using computed tomography (CT).

MATERIALS AND METHODS

The CT features of 180 surgically treated LAC patients were compared retrospectively to pathological invasive subtypes and tumour grades as defined by the new grading system published in 2021 by the World Health Organization. Two radiologists reviewed the images semi-quantitatively and independently. Univariable and multivariable regression models were built from the statistical means of their assessments to predict invasive subtypes and grades. The area under the curve (AUC) calculation was used to select the best models. The Youden index was applied to determine the cut-off values for radiological parameters.

RESULTS

The acinar/papillary patterns were associated with ill-defined margins, lower consolidation/tumour ratio and air bronchogram. The solid growth pattern was associated with a well-defined margin and hypodensity, and the micropapillary (MP) subtype with spiculation. From Grades 1 to 3, the amount of air bronchogram decreased and the consolidation/tumour ratio increased. In the sub-analyses, the best model for differentiating Grade 2 from Grade 1 had the following CT features: solid/subsolid type, consolidation/tumour ratio, well-defined margin, and air bronchogram (AUC = 0.783) and Grade 3 from Grade 2: size of the consolidation part/whole tumour ratio, size of the consolidation part, and well-defined margin (AUC = 0.759). The interobserver agreements between the two radiologists varied between 0.67 and 0.98.

CONCLUSIONS

Air bronchogram, consolidation/tumour ratio, and well-defined margin are among the best imaging findings to discriminate between both invasive subtypes and the new grades in LAC.

Chondrosarcoma of the Chest Wall: A Single Institution Review of 50 Cases

INTRODUCTION

Chondrosarcoma (CS) is most common primary osseous tumor of the chest wall. The aim of this study was to report results from surgical procedures and evaluate clinical factors predicting survival of patients with chest wall CSs treated in a single tertiary sarcoma center.

MATERIALS AND METHODS

Fifty patients with primary CS located in the ribs and sternum were included. Details of the clinical data and oncological outcomes, including local recurrence (LR) and disease-specific survival (DSS), were collected.

RESULTS

The tumor was primarily originated in the sternum in 6 patients (12.5%) and in ribs 2 to 11 in the remaining patients. Specimens were histologically graded 1 in 13 patients (26%), 2 in 28 (56%), 3 in 8 (16%), and 1 (2%) as mesenchymal grade 3 CS. R0 margins were obtained in all cases. Reconstruction was warranted in 47 (94%) cases. Local recurrence developed in 3 (6%) patients, and the median time to LR was 17 (range, 16-68) months. Eight (16%) patients developed metastasis. Increasing tumor volume was a statistically significant factor for reduction of DSS.

CONCLUSIONS

Chondrosarcoma of the chest wall can be treated effectively with clear margins, resulting in lower LR rate and higher DSS than CS of the extremities and pelvis. Metastasis of the chest wall mostly occurs in high-grade tumors, and the locations of the metastases differ greatly from those observed in CS of the extremities and pelvis. Metastases are commonly extrapulmonary, indicating the need for postoperative follow-up with multiple imaging modalities to monitor recurrence and metastases.

BAP1 germline variants in Finnish patients with malignant mesothelioma

OBJECTIVES

Although asbestos exposure is the most common cause of malignant mesothelioma (MM), an aggressive cancer of the pleura or peritoneum, up to 7% of patients harbor a genetic predisposition to MM. Pathogenic germline variants in the BRCA1-associated protein 1 (BAP1) gene cause a dominantly inherited tumor predisposition syndrome, BAP1-TPDS, in which MM is the second most common associated cancer. Other frequent cancers in BAP1-TPDS are uveal melanoma (UM), cutaneous melanoma and renal cell carcinoma. Additionally patients can exhibit benign skin lesions, BAP1-inactivated nevi (BIN). Most BINs arise sporadically, but patients with BAP1-TPDS may harbor multiple BINs before other tumors or as the only indication of the syndrome. Our objective was to establish the frequency of pathogenic germline BAP1 variants in Finnish patients with MM.

MATERIALS AND METHODS

56 DNA samples archived in the Helsinki Biobank from Finnish patients with MM were sequenced for germline BAP1 variations. Formalin fixed paraffin embedded nevi from a pathogenic variant carrier were subjected to immunohistochemistry and exome sequencing.

RESULTS

Sanger sequencing identified one patient with Finnish founder mutation c.1780_1781insT, p.(G549Vfs*49) in BAP1. The carrier was diagnosed with MM over fifteen years before the cohorts mean onset age (mean 68, range 27 to 82) although the patient had no asbestos exposure or family history of BAP1-TPDS. However, the patient had three BINs removed prior to the MM. The c.1780_1781insT is now found from five Finnish BAP1-TPDS families with unknown common ancestor.

CONCLUSION

The frequency of pathogenic germline BAP1 variants in Finnish patients with MM is 1.8 % (95 % CI, 0.04 to 9.2), comparable to the frequency in Finnish patients with UM (1.9 %). The frequency of recurring BINs in patients with BAP1-TPDS should be studied further and genetic testing for BAP1 variants considered if the patient has ≥ 2 BAP1-TPDS core tumors, including BINs.

Single centre 30-year experience in treating retroperitoneal liposarcomas

BACKGROUND AND OBJECTIVES

Liposarcomas form a diverse group of tumors that represent the majority of retroperitoneal soft tissue sarcomas. Radical excision of these retroperitoneal liposarcomas is often challenging due to their large size and proximity to visceral organs and major vessels. Here we present the 30-year experience of our multidisciplinary sarcoma team in the treatment of these tumors and analysis of factors influencing survival.

METHODS

Patients with retroperitoneal liposarcomas treated in Helsinki University Hospital from 1987 to 2017 were reviewed. Local recurrence-free survival, metastases-free survival, and disease-specific survival were assessed with Kaplan-Meier analysis, and factors influencing survival were evaluated with Cox regression.

RESULTS

A total of 107 patients were identified. The median follow-up time was 5.4 years (interquartile range: 2.2-8.8 years). Local recurrence developed in 72% and metastases in 15% during follow-up. The 5-year disease-free survival was 31% and disease-specific survival was 66%. The multifactorial analysis revealed histological type and grade as predictors of disease-specific survival (P < .01) while multifocality carried a poor prognosis for local recurrence (P = .02) and higher histological grade for metastases (P < .01).

CONCLUSIONS

Retroperitoneal liposarcomas rarely metastasize but tend to recur locally. For tumors that have been resected with macroscopically clear margins, histological, type, and grade are significant predictors of survival.

Estrogen receptor beta expression correlates with proliferation in desmoid tumors

BACKGROUND AND OBJECTIVES

Estrogen receptor signaling and cyclin D1 have a major role in tumor cell proliferation in breast cancer. Desmoid tumors are rare neoplasms that may respond to endocrine treatment. The present study aimed to investigate the expression levels and the clinical relevance of estrogen receptor beta (ERβ) and cyclin D1 in desmoid tumors.

METHODS

This study consists of 83 patients with a surgically treated desmoid tumor. ERβ and cyclin D1 expression was examined by immunohistochemistry in tissue microarrays. Cyclin A and Ki67 were studied in our previous work.

RESULTS

Median ERβ expression was 10.8%. ERβ expression correlated with expression of the proliferation antigens Ki67 (r_p  = 0.35, P = 0.003), cyclin D1 (r_p  = 0.34, P = 0.004), and cyclin A (r_p  = 0.34, P = 0.004). ERβ immunoexpression showed a trend towards predictive impact for recurrence as a continuous variable. Further explorative analysis indicated that very high ERβ expression was related to high risk of relapse (hazard ratio [HR] 2.6; P = 0.02). Median cyclin D1 expression was 15.6%. High cyclin D1 expression was associated with high Ki67 and cyclin A expression. Cyclin D1 was not associated with time to recurrence.

CONCLUSIONS

ERβ and cyclin D1 immunopositivity correlated with high proliferation in desmoid tumors. High ERβ expression might be predictive for postoperative recurrence.

Pirfenidone decreases mesothelioma cell proliferation and migration via inhibition of ERK and AKT and regulates mesothelioma tumor microenvironment in vivo

Malignant mesothelioma is an aggressive cancer with poor prognosis. It is characterized by prominent extracellular matrix, mesenchymal tumor cell phenotypes and chemoresistance. In this study, the ability of pirfenidone to alter mesothelioma cell proliferation and migration as well as mesothelioma tumor microenvironment was evaluated. Pirfenidone is an anti-fibrotic drug used in the treatment of idiopathic pulmonary fibrosis and has also anti-proliferative activities. Mesothelioma cell proliferation was decreased by pirfenidone alone or in combination with cisplatin. Pirfenidone also decreased significantly Transwell migration/invasion and 3D collagen invasion. This was associated with increased BMP pathway activity, decreased GREM1 expression and downregulation of MAPK/ERK and AKT/mTOR signaling. The canonical Smad-mediated TGF-β signaling was not affected by pirfenidone. However, pirfenidone blocked TGF-β induced upregulation of ERK and AKT pathways. Treatment of mice harboring mesothelioma xenografts with pirfenidone alone did not reduce tumor proliferation in vivo. However, pirfenidone modified the tumor microenvironment by reducing the expression of extracellular matrix associated genes. In addition, GREM1 expression was downregulated by pirfenidone in vivo. By reducing two major upregulated pathways in mesothelioma and by targeting tumor cells and the microenvironment pirfenidone may present a novel anti-fibrotic and anti-cancer adjuvant therapy for mesothelioma.

Abstract LB-014: Pirfenidone as a new potential therapy for malignant mesothelioma

The purpose of this study was to examine pirfenidone (PFD) as a potential new therapy for malignant pleural mesothelioma. PFD is an anti-fibrotic drug used to treat idiopathic pulmonary fibrosis (IPF). PFD reduces fibrous tissue formation e.g. by downregulating the production of fibroblasts and procollagens and inhibiting TGFß, TNFα and PDGF pathways. Since mesothelioma shares characteristics with IPF alongside with the activation of PI3K/Akt/mTOR, EGF, PDGF, HGF, VEGF, FGF and TGF-β pathways, we assessed the effect of PFD on mesothelioma cells in vitro and in vivo.

In vitro studies were carried out using mesothelioma cell lines (JL-1, H2052, AB12) and primary mesothelioma cells. Cells treated with PFD and/or other agents (cisplatin, pemetrexed, MK-2206, PD98059, MG132) were subjected to cell viability assays, Transwell migration assays and 3D collagen or Matrigel growth and invasion assays. TGFβ/BMP, MAPK/Erk and Akt pathway activities were studied using luciferase reporter assays and human phospho-kinase array and validated with ELISA, RT-qPCR and Western blotting.

For in vivo xenograft studies mice were injected subcutaneously with primary human mesothelioma cells expressing luciferase marker. Mice were treated with pirfenidone daily for 60 days and tumor growth was followed by bioluminescent imaging. Proliferation was studied by IHC. Differential gene expression in treated vs. untreated tumors was analyzed using RNA sequencing.

We demonstrated that PFD treatment reduced significantly mesothelioma cell proliferation, migration and invasive growth in 3D in a concentration-dependent manner. The inhibitory effect of PFD increased when combined with cisplatin treatment in vitro. We also observed reduction of Akt and MAPK/Erk pathway activities and increase in BMP signaling in PFD treated tumor cells. Preliminary analyses of in vivo experiment revealed differential expression of multiple genes in pirfenidone treated vs. untreated tumors associated with a shift to more anti-fibrotic tumor microenvironment in PFD treated tumors. Expression profiles are currently under closer investigation.

We identified pirfenidone as an inhibitor of mesothelioma invasive growth and showed that it has anti-fibrotic effects to tumor microenvironment. Since mesotheliomas are often inherently chemoresistant in fibrotic microenvironment, the use of pirfenidone could aid in overcoming chemoresistance by loosening ECM barrier for better drug penetration into the tumor tissue. Based on the current research we suggest that pirfenidone should be subjected to more intensive study as potential adjuvant-therapy for malignant mesotheliomas.

Citation Format: Chang Li, Veronika Rezov, Emmi I. Joensuu, Ville Vartiainen, Mikko Rönty, Miao Yin, Marjukka Myllärniemi, Katri Koli. Pirfenidone as a new potential therapy for malignant mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-014.

High cyclin A expression, but not Ki67, is associated with early recurrence in desmoid tumors

BACKGROUND AND OBJECTIVES

Desmoid tumors are soft-tissue tumors originating from myofibroblasts with a tendency to recur after surgery. High expression of proliferation markers is associated with shortened progression-free and/or overall survival in many neoplasms, including soft-tissue sarcomas. We investigated the prognostic role of cyclin A and Ki67 in desmoid tumors by immunohistochemistry.

METHODS

The study included 76 patients with desmoid tumor operated at Helsinki University Hospital between 1987 and 2011. A tissue micro array (TMA) was constructed and the TMA sections were immunostained with cyclin A and Ki67 antibodies. A computer-assisted image analysis was performed.

RESULTS

Cyclin A expression was evaluable in 74 and Ki67 in 70 patients. Cyclin A immunopositivity varied from 0% to 9.9%, with a mean of 1.9%. Cyclin A expression correlated significantly with Ki67. Cyclin A expression was associated with recurrence-free survival (HR 1.9, 95% CI = 1.1-3.2, P = .02), as were positive margin (HR 6.0, 95% CI = 1.6-22.5, P = .008) and extremity location (HR 5.3, 95% CI = 1.7-16.8, P = 0.005). Ki67 immunopositivity varied from 0.33% to 13.8%, with a mean of 4.6%, but had no significant prognostic impact (HR 1.1, P = .2).

CONCLUSIONS

Our study indicates that cyclin A may be a new prognostic biomarker in surgically treated desmoid tumors.

Driver Gene and Novel Mutations in Asbestos-Exposed Lung Adenocarcinoma and Malignant Mesothelioma Detected by Exome Sequencing

BACKGROUND

Asbestos is a carcinogen linked to malignant mesothelioma (MM) and lung cancer. Some gene aberrations related to asbestos exposure are recognized, but many associated mutations remain obscure. We performed exome sequencing to determine the association of previously known mutations (driver gene mutations) with asbestos and to identify novel mutations related to asbestos exposure in lung adenocarcinoma (LAC) and MM.

METHODS

Exome sequencing was performed on DNA from 47 tumor tissues of MM (21) and LAC (26) patients, 27 of whom had been asbestos-exposed (18 MM, 9 LAC). In addition, 9 normal lung/blood samples of LAC were sequenced. Novel mutations identified from exome data were validated by amplicon-based deep sequencing. Driver gene mutations in BRAF, EGFR, ERBB2, HRAS, KRAS, MET, NRAS, PIK3CA, STK11, and ephrin receptor genes (EPHA1-8, 10 and EPHB1-4, 6) were studied for both LAC and MM, and in BAP1, CUL1, CDKN2A, and NF2 for MM.

RESULTS

In asbestos-exposed MM patients, previously non-described NF2 frameshift mutation (one) and BAP1 mutations (four) were detected. Exome data mining revealed some genes potentially associated with asbestos exposure, such as MRPL1 and SDK1. BAP1 and COPG1 mutations were seen exclusively in MM. Pathogenic KRAS mutations were common in LAC patients (42 %), both in non-exposed (n = 5) and exposed patients (n = 6). Pathogenic BRAF mutations were found in two LACs.

CONCLUSION

BAP1 mutations occurred in asbestos-exposed MM. MRPL1, SDK1, SEMA5B, and INPP4A could possibly serve as candidate genes for alterations associated with asbestos exposure. KRAS mutations in LAC were not associated with asbestos exposure.

Gremlin-1 Overexpression in Mouse Lung Reduces Silica-Induced Lymphocyte Recruitment - A Link to Idiopathic Pulmonary Fibrosis through Negative Correlation with CXCL10 Chemokine

Idiopathic pulmonary fibrosis (IPF) is characterized by activation and injury of epithelial cells, the accumulation of connective tissue and changes in the inflammatory microenvironment. The bone morphogenetic protein (BMP) inhibitor protein gremlin-1 is associated with the progression of fibrosis both in human and mouse lung. We generated a transgenic mouse model expressing gremlin-1 in type II lung epithelial cells using the surfactant protein C (SPC) promoter and the Cre-LoxP system. Gremlin-1 protein expression was detected specifically in the lung after birth and did not result in any signs of respiratory insufficiency. Exposure to silicon dioxide resulted in reduced amounts of lymphocyte aggregates in transgenic lungs while no alteration in the fibrotic response was observed. Microarray gene expression profiling and analyses of bronchoalveolar lavage fluid cytokines indicated a reduced lymphocytic response and a downregulation of interferon-induced gene program. Consistent with reduced Th1 response, there was a downregulation of the mRNA and protein expression of the anti-fibrotic chemokine CXCL10, which has been linked to IPF. In human IPF patient samples we also established a strong negative correlation in the mRNA expression levels of gremlin-1 and CXCL10. Our results suggest that in addition to regulation of epithelial-mesenchymal crosstalk during tissue injury, gremlin-1 modulates inflammatory cell recruitment and anti-fibrotic chemokine production in the lung.

Lung tissue proteomics identifies elevated transglutaminase 2 levels in stable chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by irreversible airflow limitation. Cigarette smoking represents the main risk factor, but the specific mechanisms of COPD are not completely understood. Our aim was to identify COPD-specific proteomic changes involved in disease onset and severity. A comparative proteomic analysis of 51 lung tissues from nonsmokers, smokers, smokers with mild to moderate (stage I-II) COPD, severe to very severe COPD (stage III-IV), and patients with α-1-antitrypsin deficiency (AATD) and idiopathic pulmonary fibrosis (IPF) was performed by cysteine-specific two-dimensional difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry. Selected COPD-specific changes were validated by immunoblotting and further by ELISA in 120 induced sputum and plasma samples from nonsmokers, smokers, and patients with COPD (stage I-III). Altogether 82 altered proteins were identified comprising COPD-, AATD-, and IPF-specific, overlapping, and unspecific changes. Cathepsin D (CTSD), dihydropyrimidinase-related protein 2 (DPYSL2), transglutaminase 2 (TGM2), and tripeptidyl-peptidase 1 (TPP1) were validated as COPD-specific. TGM2 was not associated with smoking and correlated with COPD severity in lung tissue. TGM2 levels in sputum and plasma were elevated in patients with COPD (stage II-III) and correlated with lung function. In conclusion, new proteins related to COPD onset and severity could be identified with TGM2 being a novel potential diagnostic and therapeutic target for COPD. Further studies in carefully characterized cohorts are required to validate the identified changes.

Elevated sputum BPIFB1 levels in smokers with chronic obstructive pulmonary disease: a longitudinal study

A previous study involving a proteomic screen of induced sputum from smokers and patients with chronic obstructive pulmonary disease (COPD) demonstrated elevated levels of bactericidal/permeability-increasing fold-containing protein B1 (BPIFB1). The aim of the present study was to further evaluate the association of sputum BPIFB1 levels with smoking and longitudinal changes in lung function in smokers with COPD. Sputum BPIFB1 was characterized by two-dimensional gel electrophoresis and mass spectrometry. The expression of BPIFB1 in COPD was investigated by immunoblotting and immunohistochemistry using sputum and lung tissue samples. BPIFB1 levels were also assessed in induced sputum from nonsmokers (n = 31), smokers (n = 169), and patients with COPD (n = 52) via an ELISA-based method. The longitudinal changes in lung function during the 4-year follow-up period were compared with the baseline sputum BPIFB1 levels. In lung tissue samples, BPIFB1 was localized to regions of goblet cell metaplasia. Secreted and glycosylated BPIFB1 was significantly elevated in the sputum of patients with COPD compared with that of smokers and nonsmokers. Sputum BPIFB1 levels correlated with pack-years and lung function as measured by forced expiratory volume in 1 s (FEV1) % predicted and FEV1/FVC (forced vital capacity) at baseline and after the 4-year follow-up in all participants. The changes in lung function over 4 years were significantly associated with BPIFB1 levels in current smokers with COPD. In conclusion, higher sputum concentrations of BPIFB1 were associated with changes of lung function over time, especially in current smokers with COPD. BPIFB1 may be involved in the pathogenesis of smoking-related lung diseases.

Upregulation of activin-B and follistatin in pulmonary fibrosis - a translational study using human biopsies and a specific inhibitor in mouse fibrosis models

Background

Activins are members of the TGF-ß superfamily of growth factors. First, we identified by expression array screening that activin-B and follistatin are upregulated in human idiopathic pulmonary fibrosis (IPF). Next, we wanted to clarify their specific role in lung fibrosis formation.

Methods

We used specific antibodies for activin-A and -B subunits and follistatin to measure and localize their levels in idiopathic pulmonary fibrosis and control lung biopsies. To inhibit activin signaling, we used soluble activin type IIB receptor fused to the Fc portion of human IgG1 (sActRIIB-Fc) in two different mouse models of pulmonary fibrosis.

Results

Activin-B and follistatin mRNA levels were elevated in the human IPF lung. Immunoreactivity to activin-A, -B and follistatin localized predominantly to the hyperplastic, activated alveolar epithelium, but was also seen in inflammatory cells. Mice treated with sActRIIB-Fc showed increased skeletal muscle mass and a clear reduction in alveolar cell counts in bronchoalveolar lavage fluid, but no significant antifibrotic effect in the lung was observed.

Conclusions

The upregulation of activin-B and follistatin in IPF is a novel finding. Our results indicate that activin inhibition is not an efficient tool for antifibrotic therapy, but could be useful in reducing alveolar cellular response to injury. Activin-B and follistatin levels may be useful as biomarkers of IPF.

Abstract 3449: Overexpression of activin A and B as well as altered activation of canonical and non-canonical signaling pathways in malignant mesothelioma

Activin A and B, members of the TGF-β superfamily, are regulators of differentiation, inflammation and wound healing. Dimeric activins bind to transmembrane activin type I and type II receptors and induce signaling through activation of the canonical Smad2/3 pathway as well as through activation of MAPK pathways. Depending on the tissue type activins can promote or inhibit cellular growth and/or migration. Activin A has recently been reported to have growth promoting properties in malignant mesothelioma (MM). MM is a rare and aggressive tumor originating most commonly from pleural mesothelial cells. It is asbestos exposure related malignancy that takes decades to develop. MM tumors are highly invasive and extremely resistant to conventional cancer therapy. Novel diagnostic markers and drug targets are urgently needed. We have characterized the expression of activins, follistatins and activin receptors in mesothelioma tumors and cultured mesothelioma cells. In addition, we have identified signaling pathways induced in mesothelioma cells by activin treatment. Expression of activins and receptors in mesothelioma tumors were analyzed by immunohistochemistry. Activins, follistatins and receptors in primary mesothelioma cells and in mesothelioma cell lines were analyzed at the level of mRNA and protein expression. Activation of Smad2/3 and Smad1/5/8 signaling pathways were analyzed by luciferase reporter assays and Western blotting. Activation of MAPK/JNK and MAPK/ERK pathways were analyzed by Western blotting. Immortalized but nonmalignant Met5A cells served as a control cell line. Activin A and B were strongly expressed in mesothelioma tumor tissue. Cultured primary mesothelioma cells and mesothelioma cell lines also expressed higher levels of activin A and B compared to Met5A cells. All activin receptors (ALK3, ALK4, ALK7, ACVR2A, ACVR2B) were found expressed in cultured mesothelioma cells. ACVR2A and ALK7 were significantly overexpressed in all mesothelioma cells. Majority of the mesothelioma cell lines had attenuated Smad2/3 activation upon activin stimulation. In Met5A and H28 cells there was activation of Smad2/3 as well as MAPK/JNK pathways. On the contrary, activation of MAPK/ERK pathway was detected in cells displaying attenuated Smad2/3 activation.Our results show that activin A and B are overexpressed in MM. This together with upregulation of specific activin receptors points to a role for activins in MM progression. Furthermore, we observed that mesothelioma cells have altered responses to activin stimulation, namely attenuation of canonical Smad2/3 signaling and increase in MAPK/ERK signaling. This is likely to have an impact on mesothelioma cell behavior and tumor progression.

Citation Format: Jenni A. Tamminen, Mikko Rönty, Eva Sutinen, Arja Pasternack, Olli Ritvos, Marjukka Myllärniemi, Katri Koli. Overexpression of activin A and B as well as altered activation of canonical and non-canonical signaling pathways in malignant mesothelioma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3449. doi:10.1158/1538-7445.AM2014-3449

ALK fusion and its association with other driver gene mutations in Finnish non-small cell lung cancer patients

Screening of anaplastic lymphoma tyrosine kinase (ALK) gene fusions in non-small cell lung cancer (NSCLC) patients enables the identification of the patients likely to benefit from ALK-targeted therapy. Our aim was to assess the prevalence of ALK fusion in Finnish NSCLC patients, which has not been reported earlier, and to study the presence of ALK fusion in relation to clinicopathological characteristics and other driver gene mutations. A total of 469 formalin-fixed paraffin-embedded tumor tissue specimens from Finnish NSCLC patients were screened for ALK fusion by immunohistochemistry (IHC). For confirmation of IHC results, fluorescence in situ hybridization (FISH) was conducted for 171 specimens. Next-generation sequencing was performed for all ALK-positive specimens to characterize the association of ALK fusion with mutations in targeted regions of 22 driver genes. Of the 469 tumors screened, 11 (2.3%) harbored an ALK fusion, including nine adenocarcinomas and two large cell carcinomas. The IHC results for all 11 ALK-positive and 160 random ALK-negative specimens were confirmed by FISH. ALK fusion was significantly associated with never/ex-light smoking history (P<0.001) and younger age (P=0.004). Seven ALK-positive tumors showed additional mutations; three in MET, one in MET and CTNNB1, two in TP53, and one in PIK3CA. Our results show that ALK fusion is an infrequent alteration in Finnish NSCLC patients. Although the majority of ALK-positive cases were adenocarcinomas, the fusion was also seen in large cell carcinomas. Further studies are needed to elucidate the clinical significance of the coexistence of ALK fusion with MET, TP53, CTNNB1, and PIK3CA mutations.

Mutated ephrin receptor genes in non-small cell lung carcinoma and their occurrence with driver mutations-targeted resequencing study on formalin-fixed, paraffin-embedded tumor material of 81 patients

Non-small cell lung carcinoma (NSCLC) is the most common subtype of lung cancer. The oncogenic potential of receptor tyrosine kinases (RTKs) is widely known and they are potential targets for tailored therapy. Ephrin receptors (Ephs) form the largest group of RTKs. Nevertheless, Ephs are not widely studied in NSCLC so far. The aim of our study was to investigate novel mutations of Eph genes (EPHA1-8, EPHB1-4, EPHB6) and their association with clinically relevant mutations in BRAF, EML4-ALK, EGFR, INSR, KDR, KRAS, MET, PDGFRA, PDGFRB, PIK3, PTEN, RET, and TP53 in NSCLC patients. Targeted resequencing was conducted on 81 formalin-fixed, paraffin-embedded NSCLC tumor specimens. We analyzed missense and nonsense mutations harbored in the coding regions of the selected genes. We found 18 novel mutations of Ephs in 20% (16 of 81) of the patients. Nearly half of these mutations occurred in the protein kinase domain. The mutations were not mutually exclusive with other clinically relevant mutations. Our study shows that Ephs are frequently mutated in NSCLC patients, and occur together with other known mutations relevant to the pathogenicity of NSCLC.

Identification and validation of human papillomavirus encoded microRNAs

We report here identification and validation of the first papillomavirus encoded microRNAs expressed in human cervical lesions and cell lines. We established small RNA libraries from ten human papillomavirus associated cervical lesions including cancer and two human papillomavirus harboring cell lines. These libraries were sequenced using SOLiD 4 technology. We used the sequencing data to predict putative viral microRNAs and discovered nine putative papillomavirus encoded microRNAs. Validation was performed for five candidates, four of which were successfully validated by qPCR from cervical tissue samples and cell lines: two were encoded by HPV 16, one by HPV 38 and one by HPV 68. The expression of HPV 16 microRNAs was further confirmed by in situ hybridization, and colocalization with p16INK4A was established. Prediction of cellular target genes of HPV 16 encoded microRNAs suggests that they may play a role in cell cycle, immune functions, cell adhesion and migration, development, and cancer. Two putative viral target sites for the two validated HPV 16 miRNAs were mapped to the E5 gene, one in the E1 gene, two in the L1 gene and one in the LCR region. This is the first report to show that papillomaviruses encode their own microRNA species. Importantly, microRNAs were found in libraries established from human cervical disease and carcinoma cell lines, and their expression was confirmed in additional tissue samples. To our knowledge, this is also the first paper to use in situ hybridization to show the expression of a viral microRNA in human tissue.

Comparison of targeted next-generation sequencing (NGS) and real-time PCR in the detection of EGFR, KRAS, and BRAF mutations on formalin-fixed, paraffin-embedded tumor material of non-small cell lung carcinoma-superiority of NGS

The development of tyrosine kinase inhibitor treatments has made it important to test cancer patients for clinically significant gene mutations that influence the benefit of treatment. Targeted next-generation sequencing (NGS) provides a promising method for diagnostic purposes by enabling the simultaneous detection of multiple mutations in various genes in a single test. The aim of our study was to screen EGFR, KRAS, and BRAF mutations by targeted NGS and commonly used real-time polymerase chain reaction (PCR) methods to evaluate the feasibility of targeted NGS for the detection of the mutations. Furthermore, we aimed to identify potential novel mutations by targeted NGS. We analyzed formalin-fixed, paraffin-embedded (FFPE) tumor tissue specimens from 81 non-small cell lung carcinoma patients. We observed a significant concordance (from 96.3 to 100%) of the EGFR, KRAS, and BRAF mutation detection results between targeted NGS and real-time PCR. Moreover, targeted NGS revealed seven nonsynonymous single-nucleotide variations and one insertion-deletion variation in EGFR not detectable by the real-time PCR methods. The potential clinical significance of these variants requires elucidation in future studies. Our results support the use of targeted NGS in the screening of EGFR, KRAS, and BRAF mutations in FFPE tissue material.

Targeted deep sequencing as a diagnostic and research method for detecting EGFR and ALK pathway driver genes in FFPE tissue of lung and colorectal carcinomas

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Background: Molecular targeted tyrosine kinase inhibitor (TKI) treatments have made it crucial to perform diagnostic tests of multiple molecular targets. In lung carcinoma there are close to ten clinically relevant gene mutations, copy number alterations and/or gene fusions, such as ALK, EGFR, ERBB2, KRAS, BRAF, MET, PTEN, PI3KCA, ROS1 and RET. Presently, several different tests are utilized, requiring a high amount of tumor material and long turnaround time. Next generation sequencing or targeted deep sequencing (TDS) has opened a new era for rapid genome-wide analyses of mutations, copy number alterations and gene fusions. Our aimwas to 1) prove feasibility for applying TDS to FFPE samples, 2) compare mutations detected by prevalent methods & TDS, and 3) mine novel clinically and biologically relevant genes in lung and colorectal carcinoma. Methods: For TDS, we selected 192 lung carcinoma and colorectal carcinoma related genes and microRNA genes, focusing on the EGFR and ALK pathways. In total, 98 FFPE specimens were studied. Agilent SureSelect system and Illumina sequencing was adopted for the analysis. For diagnostic validation the following genes were selected: EGFR, KRAS, BRAF, PTEN, PI3K, RET and ALK. TDS results were confirmed by PCR, FISH and IHC. Results: We focused on the genes selected for diagnostic validation. Successful results were obtained from all specimens. The results from TDS correlated significantly with those obtained from PCR, FISH, and IHC. Importantly, TDS revealed novel mutations not detected by targeted PCR. Conclusions: An enormous advantage of TDS is that multiple mutation screening can be achieved in one analysis (saving time and material), and most importantly, provides enormous amounts of novel information, for example understanding mechanisms for drug resistance. This study was supported by Finnish Academy, Sigrid Jusélius Foundation, Finnish Cancer Organizations, the special governmental subsidy research funds appropriated to the Helsinki and Uusimaa Hospital District (HUS EVO), Pfizer Oy, AstraZeneca AS, Lab21 Ltd, Abbott Molecular Inc.

Cell culture model predicts human disease: Altered expression of junction proteins and matrix metalloproteinases in cervical dysplasia

BACKGROUND

Cervical cancer is necessarily caused by human papillomaviruses, which encode three oncogenes manifesting their functions by interfering with a number of cellular proteins and pathways: the E5, E6, and E7 proteins. We have earlier found in our microarray studies that the E5 oncogene crucially affects the expression of cellular genes involved in adhesion and motility of epithelial cells.

METHODS

In order to biologically validate our previous experimental findings we performed immunohistochemical staining of a representative set of tissue samples from different grades of high-risk human papillomavirus associated cervical disease as well as normal squamous and columnar cervical epithelium. Three-dimensional collagen raft cultures established from E5-expressing and control epithelial cells were also examined. The expression of p16, matrix metalloproteinase (MMP) -7, MMP-16, cytokeratin (CK) 8/18, laminin, E-cadherin and beta-catenin was studied.

RESULTS

In agreement with our previous microarray studies, we found intense staining for E-cadherin and beta-catenin in adherens junctions even in high-grade cervical lesions. Staining for MMP-16 was increased in severe disease as well. No significant change in staining for MMP-7 and cytokeratin 8/18 along with the grade of cervical squamous epithelial disease was observed.

CONCLUSIONS

Here we have confirmed, using tissue material from human papillomavirus associated lesions, some of the cellular gene expression modifications that we earlier reported in an experimental system studying specifically the E5 oncogene of papillomaviruses. These findings were partially surprising in the context of cervical carcinogenesis and emphasize that the complexity of carcinogenesis is not yet fully understood. Microarray approaches provide a wide overwiev of gene expression in experimental settings, which may yield biologically valid biomarkers for disease diagnostics, prognosis, and follow-up.

Soft tissue sarcoma - a population-based, nationwide study with special emphasis on local control

BACKGROUND

A prospective diagnostics and treatment protocol for extremity and trunk wall soft tissue sarcoma (STS) was introduced by the Scandinavian Sarcoma Group in 1986 and it was also widely adopted in Finland. We have updated the protocol and made it more detailed at the Helsinki University Central Hospital. We retrospectively compared diagnostics and treatment of STS in a nationwide population-based material to this protocol with special emphasis on local control.

METHODS

Data for 219 patients with an STS of extremity or trunk wall diagnosed during 1998-2001 was retrieved from the nationwide Finnish Cancer Registry. Histologic review was performed. Treatment centres were divided into high-, intermediate- and low-volume centres based on the number of patients with final surgery during the study period.

RESULTS

Significantly more patients were operated with a preoperative histological or cytological diagnosis at high-volume centres. No preoperative diagnosis was a strong predictor for the patient to undergo more than one operation (p < 0.0001). Wide surgical margin was achieved more often at high-volume centres, but in all centre categories a considerable percentage of patients with inadequate surgical margin did not receive adjuvant radiation therapy. Local control at five years was 82% at high-volume centres, 61% at intermediate-volume centres treating highest percentage of deep tumours and 69% at low-volume centres (p = 0.046). Local control improved as the number of patients operated (surgical volume of the centre) increased.

CONCLUSION

The present quality-control study is the first nationwide population-based study to assess diagnostics and treatment of STS. When referred to a specialised sarcoma centre even patients with inadequate surgery can achieve good local control. STS is a rare cancer and its treatment should be centralised in Finland, which has 5.4 million inhabitants and approximately 100 new STSs of extremities and trunk wall annually.

SIRT1 protects against emphysema via FOXO3-mediated reduction of premature senescence in mice

Chronic obstructive pulmonary disease/emphysema (COPD/emphysema) is characterized by chronic inflammation and premature lung aging. Anti-aging sirtuin 1 (SIRT1), a NAD+-dependent protein/histone deacetylase, is reduced in lungs of patients with COPD. However, the molecular signals underlying the premature aging in lungs, and whether SIRT1 protects against cellular senescence and various pathophysiological alterations in emphysema, remain unknown. Here, we showed increased cellular senescence in lungs of COPD patients. SIRT1 activation by both genetic overexpression and a selective pharmacological activator, SRT1720, attenuated stress-induced premature cellular senescence and protected against emphysema induced by cigarette smoke and elastase in mice. Ablation of Sirt1 in airway epithelium, but not in myeloid cells, aggravated airspace enlargement, impaired lung function, and reduced exercise tolerance. These effects were due to the ability of SIRT1 to deacetylate the FOXO3 transcription factor, since Foxo3 deficiency diminished the protective effect of SRT1720 on cellular senescence and emphysematous changes. Inhibition of lung inflammation by an NF-κB/IKK2 inhibitor did not have any beneficial effect on emphysema. Thus, SIRT1 protects against emphysema through FOXO3-mediated reduction of cellular senescence, independently of inflammation. Activation of SIRT1 may be an attractive therapeutic strategy in COPD/emphysema.

Data-driven information retrieval in heterogeneous collections of transcriptomics data links SIM2s to malignant pleural mesothelioma

Motivation: Genome-wide measurement of transcript levels is an ubiquitous tool in biomedical research. As experimental data continues to be deposited in public databases, it is becoming important to develop search engines that enable the retrieval of relevant studies given a query study. While retrieval systems based on meta-data already exist, data-driven approaches that retrieve studies based on similarities in the expression data itself have a greater potential of uncovering novel biological insights.

Results: We propose an information retrieval method based on differential expression. Our method deals with arbitrary experimental designs and performs competitively with alternative approaches, while making the search results interpretable in terms of differential expression patterns. We show that our model yields meaningful connections between biological conditions from different studies. Finally, we validate a previously unknown connection between malignant pleural mesothelioma and SIM2s suggested by our method, via real-time polymerase chain reaction in an independent set of mesothelioma samples.

Availability:Supplementary data and source code are available from http://www.ebi.ac.uk/fg/research/rex.

Contact:samuel.kaski@aalto.fi

Supplementary Information:Supplementary data are available at Bioinformatics online.

Sputum proteomics identifies elevated PIGR levels in smokers and mild-to-moderate COPD

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality around the world. However, the exact mechanisms leading to COPD and its progression are still poorly understood. In this study, induced sputum was analyzed by cysteine-specific two-dimensional difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry to identify proteins involved in COPD pathogenesis. The comparison of nonsmokers, smokers, and smokers with moderate COPD revealed 15 changed proteins with the majority, including polymeric immunoglobulin receptor (PIGR), being elevated in smokers and subjects with COPD. PIGR, which is involved in specific immune defense and inflammation, was further studied in sputum, lung tissue, and plasma by Western blot, immunohistochemistry/image analysis, and/or ELISA. Sputum PIGR was characterized as glycosylated secretory component (SC). Lung PIGR was significantly elevated in the bronchial and alveolar epithelium of smokers and further increased in the alveolar area in mild to moderate COPD. Plasma PIGR was elevated in smokers and smokers with COPD compared to nonsmokers with significant correlation to obstruction. In conclusion, new proteins in smoking-related chronic inflammation and COPD could be identified, with SC/PIGR being one of the most prominent not only in the lung but also in circulating blood.

Ageing and long-term smoking affects KL-6 levels in the lung, induced sputum and plasma

Background

KL-6 is a high-molecular-weight glycoprotein classified as a human MUC1 mucin. It was hypothesized that KL-6 could be detectable in the circulating blood and especially in airway secretions in lung diseases associated with mucus production such as chronic obstructive pulmonary disease (COPD). Additional aims of this study were to investigate whether the levels of KL-6 in plasma and sputum are related to ageing and smoking history.

Methods

The concentrations of KL-6 in plasma and induced sputum supernatants from young and/or middle aged/elderly non-smokers, smokers and patients with COPD were assayed by ELISA (n = 201). The subjects were classified into five groups according to age, smoking status and presence of COPD. In addition, KL-6 expression in control and diseased lung i.e. samples from patients with COPD (n = 28), were analyzed by immunohistochemistry and digital image analysis.

Results

The plasma levels of KL-6 increased with age both in non-smokers and smokers. Among middle aged/elderly subjects, plasma KL-6 levels in all smokers regardless of COPD were significantly higher than in non-smokers, whereas sputum levels of KL-6 were significantly higher in COPD compared not only to non-smokers but also to smokers. KL-6 was more prominently expressed in the bronchiolar/alveolar epithelium in COPD than in the control lungs. Plasma and sputum KL-6 levels correlated inversely with obstruction and positively with smoking history and ageing. The linear multiple regression analysis confirmed that age and cigarette smoking had independent effects on plasma KL-6.

Conclusions

KL-6 increases with ageing and chronic smoking history, but prospective studies will be needed to elucidate the significance of KL-6 in chronic airway diseases.

A rare case of oral epithelioid sarcoma of the gingiva

Epithelioid sarcoma (ES) is a rare malignant soft tissue tumor. ES can be classified into proximal, distal, and fibroma-like subtypes. These tumors show both mesenchymal and epithelial immunophenotypes. Microscopically, the proximal type ES is usually characterized by nodules of spindle and epithelioid cells growing in granuloma-like pattern often presenting with central necrosis. Immunohistochemically these tumors are vimentin, pancytokeratin, and usually EMA (80%) positive. CD34 (50%) and CD99 (25%) may be positive, and occasionally SMA and S-100 immunopositivity has been reported. No specific genetic alterations have been found in ES. As far as we know, this is the first case in the literature to present ES in gingival mucosa.

Palladin interacts with SH3 domains of SPIN90 and Src and is required for Src-induced cytoskeletal remodeling

Palladin and SPIN90 are widely expressed proteins, which participate in modulation of actin cytoskeleton by binding to a variety of scaffold and signaling molecules. Cytoskeletal reorganization can be induced by activation of signaling pathways, including the PDGF receptor and Src tyrosine kinase pathways. In this study we have analyzed the interplay between palladin, SPIN90 and Src and characterized the role of palladin and SPIN90 in PDGF and Src-induced cytoskeletal remodeling. We show that the SH3 domains of SPIN90 and Src directly bind palladin's poly-proline sequence and the interaction controls intracellular targeting of SPIN90. In PDGF-treated cells, palladin and SPIN90 co-localize in actin-rich membrane ruffles and lamellipodia. The effect of PDGF on the cytoskeleton is at least partly mediated by the Src kinase since PP2, a selective Src kinase family inhibitor, blocked PDGF-induced changes. Furthermore, expression of active Src kinase resulted in coordinated translocation of both palladin and SPIN90 to membrane protrusions. Knock-down of endogenous SPIN90 did not inhibit Src-induced cytoskeletal rearrangement, whereas knock-down of palladin resulted in cytoskeletal disorganization and inhibition of remodeling. Further studies showed that palladin is tyrosine phosphorylated in cells expressing active Src indicating bidirectional interplay between palladin and Src. These results may have implications in understanding the invasive and metastatic phenotype of neoplastic cells induced by Src.

Involvement of palladin and alpha-actinin in targeting of the Abl/Arg kinase adaptor ArgBP2 to the actin cytoskeleton

Palladin and alpha-actinin are major components of stress fiber dense bodies, cardiomyocyte Z-discs and neuronal synapses. They function as structural molecules and cytoskeletal regulators but also as docking sites to other proteins. Both antisense and transient overexpression experiments have shown that palladin plays an important role in the regulation of actin cytoskeleton. ArgBP2 is a multi-domain scaffolding protein which shares both the tissue distribution and subcellular localization with palladin. ArgBP2 is directly linked to intracellular signaling cascades by its interaction with Abl family kinases, Pyk2 and the ubiquitin ligase Cbl. It has several actin associated binding partners and has been shown to regulate cytoskeletal dynamics. Here, we show by in vivo and in vitro methods that palladin's amino-terminal poly-proline sequences directly interact with the first carboxy-terminal SH3 domain of ArgBP2. We further demonstrate a direct interaction between alpha-actinin and the amino-terminal segment of ArgBP2. Immunoprecipitation and targeting assays suggest that a three-way complex of the proteins occurs in vivo. The interactions provide an explanation to the previously observed Z-disc-specific localization of ArgBP2 and indicate interplay between signaling adaptors and structural proteins of the Z-disc.

Molecular analysis of the interaction between palladin and alpha-actinin

Palladin is a novel component of stress fiber dense regions. Antisense and transient overexpression studies have indicated an important role for palladin in the regulation of actin cytoskeleton. Palladin colocalizes and coimmunoprecipitates with alpha-actinin, a dense region component, but the molecular details and functional significance of the interaction have not been studied. We show here a direct association between the two proteins and have mapped the binding site within a short sequence of palladin and in the carboxy-terminal calmodulin domain of alpha-actinin. Using transfection-based targeting assays, we show that palladin is involved in targeting of alpha-actinin to specific subcellular foci indicating a functional interplay between the two actin-associated proteins.

Nitric oxide donors retard wound healing in cultured rabbit gastric epithelial cell monolayers

Effects of nitric oxide (NO) on gastric wound healing were investigated in primary rabbit gastric epithelial cell cultures. We analyzed the speed of cell migration, proliferation, and apoptosis after creating a round wound on the cell cultures. The monolayers were incubated with or without the NO donor sodium nitroprusside, oxatriazolimine 1,2,3,4-oxatriazolium, 5amino-3-(3,4-dichlorophenylchloride), or the peroxynitrite generator 3-morpholinosydnomine-N-ethylcarbamide. The possible role of cGMP as a second messenger of NO was investigated with 8-bromo-cGMP. The role of O2(-*) was evaluated using diethyldithiocarbamate and pyrogallol. The effects of superoxide dismutase and allopurinol were also investigated. NO inhibited the speed of cell migration and proliferation and induced cell apoptosis in a dose- and time-dependent manner. The effects were augmented with O2(-*) generators and ameliorated by O2-(8) scavengers, whereas cGMP had no significant effect on wound healing. NO donors retard gastric wound healing by inhibiting migration and proliferation and inducing cell apoptosis. These effects do not seem to be mediated via cGMP, but O2(-*). or peroxynitrites may be involved.

Characterization of human palladin, a microfilament-associated protein

Actin-containing microfilaments control cell shape, adhesion, and contraction. In striated muscle, alpha-actinin and other Z-disk proteins coordinate the organization and functions of actin filaments. In smooth muscle and nonmuscle cells, periodic structures termed dense bodies and dense regions, respectively, are thought to serve functions analogous to Z-discs. We describe here identification and characterization of human palladin, a protein expressed mainly in smooth muscle and nonmuscle and distributed along microfilaments in a periodic manner consistent with dense regions/bodies. Palladin contains three Ig-domains most homologous to the sarcomeric Z-disk protein myotilin. The N terminus includes an FPPPP motif recognized by the Ena-Vasp homology domain 1 domain in Ena/vasodilatator-stimulated phosphoprotein (VASP)/Wiscott-Aldrich syndrome protein (WASP) protein family. Cytoskeletal proteins with FPPPP motif target Ena/VASP/WASP proteins to sites of actin modulation. We identified palladin in a yeast two-hybrid search as an ezrin-associated protein. An interaction between palladin and ezrin was further verified by affinity precipitation and blot overlay assays. The interaction was mediated by the alpha-helical domain of ezrin and by Ig-domains 2-3 of palladin. Ezrin is typically a component of the cortical cytoskeleton, but in smooth muscle cells it is localized along microfilaments. These cells express palladin abundantly and thus palladin may be involved in the microfilament localization of ezrin. Palladin expression was up-regulated in differentiating dendritic cells (DCs), coinciding with major cytoskeletal and morphological alterations. In immature DCs, palladin localized in actin-containing podosomes and in mature DCs along actin filaments. The regulated expression and localization suggest a role for palladin in the assembly of DC cytoskeleton.