Molecular underpinnings of cytoskeletal cross-talk.

Cross-talk between the microtubule and actin networks has come under intense scrutiny following the realization that it is crucial for numerous essential processes, ranging from cytokinesis to cell migration. It is becoming increasingly clear that proteins long-considered highly specific for one or the other cytoskeletal system do, in fact, make use of both filament types. How this functional duality of "shared proteins" has evolved and how their coadaptation enables cross-talk at the molecular level remain largely unknown. We previously discovered that the mammalian adaptor protein melanophilin of the actin-associated myosin motor is one such "shared protein," which also interacts with microtubules in vitro. In a hypothesis-driven in vitro and in silico approach, we turn to early and lower vertebrates and ask two fundamental questions. First, is the capability of interacting with microtubules and actin filaments unique to mammalian melanophilin or did it evolve over time? Second, what is the functional consequence of being able to interact with both filament types at the cellular level? We describe the emergence of a protein domain that confers the capability of interacting with both filament types onto melanophilin. Strikingly, our computational modeling demonstrates that the regulatory power of this domain on the microscopic scale alone is sufficient to recapitulate previously observed behavior of pigment organelles in amphibian melanophores. Collectively, our dissection provides a molecular framework for explaining the underpinnings of functional cross-talk and its potential to orchestrate the cell-wide redistribution of organelles on the cytoskeleton.

Myosin Va's adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro.

Pigment organelles, or melanosomes, are transported by kinesin, dynein, and myosin motors. As such, melanosome transport is an excellent model system to study the functional relationship between the microtubule- and actin-based transport systems. In mammalian melanocytes, it is well known that the Rab27a/melanophilin/myosin Va complex mediates actin-based transport in vivo. However, pathways that regulate the overall directionality of melanosomes on the actin/microtubule networks have not yet been delineated. Here, we investigated the role of PKA-dependent phosphorylation on the activity of the actin-based Rab27a/melanophilin/myosin Va transport complex in vitro. We found that melanophilin, specifically its C-terminal actin-binding domain (ABD), is a target of PKA. Notably, in vitro phosphorylation of the ABD closely recapitulated the previously described in vivo phosphorylation pattern. Unexpectedly, we found that phosphorylation of the ABD affected neither the interaction of the complex with actin nor its movement along actin tracks. Surprisingly, the phosphorylation state of melanophilin was instead important for reversible association with microtubules in vitro. Dephosphorylated melanophilin preferred binding to microtubules even in the presence of actin, whereas phosphorylated melanophilin associated with actin. Indeed, when actin and microtubules were present simultaneously, melanophilin's phosphorylation state enforced track selection of the Rab27a/melanophilin/myosin Va transport complex. Collectively, our results unmasked the regulatory dominance of the melanophilin adaptor protein over its associated motor and offer an unexpected mechanism by which filaments of the cytoskeletal network compete for the moving organelles to accomplish directional transport on the cytoskeleton in vivo.

Making cytological diagnoses on digital images using the iPath network.

BACKGROUND: The iPath telemedicine platform Basel is mainly used for histological and cytological consultations, but also serves as a valuable learning tool. AIM: To study the level of accuracy in making diagnoses based on still images achieved by experienced cytopathologists, to identify limiting factors, and to provide a cytological image series as a learning set. METHOD: Images from 167 consecutive cytological specimens of different origin were uploaded on the iPath platform and evaluated by four cytopathologists. Only wet-fixed and well-stained specimens were used. The consultants made specific diagnoses and categorized each as benign, suspicious or malignant. RESULTS: For all consultants, specificity and sensitivity regarding categorized diagnoses were 83-92 and 85-93%, respectively; the overall accuracy was 88-90%. The interobserver agreement was substantial (κ = 0.791). The lowest rate of concordance was achieved in urine and bladder washings and in the identification of benign lesions. CONCLUSION: Using a digital image set for diagnostic purposes implies that even under optimal conditions the accuracy rate will not exceed to 80-90%, mainly because of lacking supportive immunocytochemical or molecular tests. This limitation does not disqualify digital images for teleconsulting or as a learning aid. The series of images used for the study are open to the public at http://pathorama.wordpress.com/extragenital-cytology-2013/.

Malignant biliary stenosis: conventional cytology versus DNA image cytometry.

BACKGROUND: The aim of this study is to evaluate the utility of image cytometry (ICM)-DNA analysis on cytological brush specimens in improving the sensitivity and diagnostic accuracy for biliary neoplasias. METHODS: A total of 71 patients with 89 samples of biliary tree brushing from a stenosis were included in this prospective study. Conventional cytology (CC) and DNA ploidy using ICM of the brushing were performed. Benign or malignant findings were confirmed by surgical exploration or a clinical follow-up of at least 12 months. RESULTS: Diagnosis was confirmed by clinical follow-up in 44 cases and surgical investigation or histology in 41 cases. A definitive diagnosis of the smears resulted in 40 malignant and 49 benign diagnoses. The sensitivity was 0.666 for CC and 0.658 for ICM, and the specificity was 0.920 and 0.937, respectively. The positive predictive value (PPV) was 0.866 for CC and 0.900 for ICM. McNemar's test did not reveal a significant difference between CC and ICM (P=0.803). Agreement of the two methods was found in 73 samples, raising specificity to 0.998 but not sensitivity (0.725). CONCLUSIONS: ICM-DNA seems not to improve significantly the PPV and NPV for detecting neoplasias of the biliary tract compared to CC. Nevertheless a clinical advantage can be seen in the agreement of the two methods in diagnosing dysplasia or cancer, since it did not show false positive results.

The prognostic value of cytology and fluorescence in situ hybridization in the follow-up of nonmuscle-invasive bladder cancer after intravesical Bacillus Calmette-Guérin therapy.

Molecular markers reliably predicting failure or success of Bacillus Calmette-Guérin (BCG) in the treatment of nonmuscle-invasive urothelial bladder cancer (NMIBC) are lacking. The aim of our study was to evaluate the value of cytology and chromosomal aberrations detected by fluorescence in situ hybridization (FISH) in predicting failure to BCG therapy. Sixty-eight patients with NMIBC were prospectively recruited. Bladder washings collected before and after BCG instillation were analyzed by conventional cytology and by multitarget FISH assay (UroVysion, Abbott/Vysis, Des Plaines, IL) for aberrations of chromosomes 3, 7, 17 and 9p21. Persistent and recurrent bladder cancers were defined as positive events during follow-up. Twenty-six of 68 (38%) NMIBC failed to BCG. Both positive post-BCG cytology and positive post-BCG FISH were significantly associated with failure of BCG (hazard ratio (HR)= 5.1 and HR= 5.6, respectively; p < 0.001 each) when compared to those with negative results. In the subgroup of nondefinitive cytology (all except those with unequivocally positive cytology), FISH was superior to cytology as a marker of relapse (HR= 6.2 and 1.4, respectively). Cytology and FISH in post-BCG bladder washings are highly interrelated and a positive result predicts failure to BCG therapy in patients with NMIBC equally well. FISH is most useful in the diagnostically less certain cytology categories but does not provide additional information in clearly malignant cytology.

[Oral erythroplakia and erythroleukoplakia: red and red-white dysplastic lesions of the oral mucosa--part 2: cytodiagnosis, pathogenesis, therapy, and prognostic aspects]. / Erythroplakie und Erythroleukoplakie: Rote und rot-weisse Risikoläsionen der Mundhöhlenschleimhaut. Teil 2: Aktuelle Aspekte zur Zytodiagnostik, Pathogenese, Therapie und Prognose.

The second part of the present review article presents and discusses the current literature regarding cytodiagnostic aspects, pathogenesis, therapy, incidence of recurrence, and malignant transformation rate of oral erythroplakia (OE) and oral erythroleukoplakia (OEL). Oral cytopathology, eventually in combination with DNA cytometry, can add valuable information to conventional histopathology, but is not able yet to replace the aforementioned. Numerous molecular genetic variants have been studied in precancerous lesions to gain knowledge about the prognosis of these lesions. Still, there are no evidence-based parameters available to safely detect precursor lesions that will undergo malignant transformation in the future. Excision of OE and OEL should be performed with a margin of safety using the CO2 laser or a scalpel. Data about incidence of recurrence and malignant tranformation rates of OE are mostly based upon case reports or case series. The OEL has a significantly higher risk of malignant transformation than oral leukoplakias.

[Oral erythroplakia and erythroleukoplakia: red and red-white dysplastic lesions of the oral mucosa--part 1: epidemiology, etiology, histopathology and differential diagnosis]. / Erythroplakie und Erythroleukoplakie: Rote und rot-weisse Risikoläsionen der Mundhöhlenschleimhaut. Teil 1: Epidemiologie, Atiologie, Histopathologie und Differenzialdiagnose.

Oral erythroplakia (OE) and oral erythroleukoplakia (OEL; synonym: speckled leukoplakia) are working diagnoses for red and red-white lesions of the oral mucosa after exclusion of all other possible diagnoses for lesions with a similar clinical appearance. A good knowledge of oral medicine and possible differential diagnoses of oral mucosal pathologies is mandatory to correctly detect OE and OEL on this exclusion basis. In the present review article in a series of two, epidemiologic data, etiologic factors, possible differential diagnoses, and the histopathologic characteristics of OE and OEL will be presented and discussed regarding the current literature. A thorough histopathologic examination of these epithelial precursor lesions is mandatory to recognise the presence and the severity of epithelial dysplasia, which is a decisive factor for the subsequent treatment planning.

[High risk lesions of the oral mucosa--Diagnosis, therapy and follow-up in two cases]. / Risikoläsionen der Mundhöhlenschleimhaut: Diagnostik, Therapie und Nachsorge anhand zweier Fallberichte.

Stomatologic lesions at risk to develop an oral squamous cell carcinoma (OSCC) such as oral leukoplakia, erythroplakia/erythroleukoplakia, or oral lichen planus, need an early detection, diagnosis and a long-term/lifelong follow-up to prevent malignant transformation. In the following report, two patients are presented with oral mucosal lesions, who were referred, diagnosed, treated, and underwent follow-up examinations at the Stomatology Service of the Department of Oral Surgery and Stomatology at the University of Bern. These two cases emphasize the importance of early detection and managment of precancerous lesions or initial stages of OSCC. Additionally, risk factors, such as tobacco and alcohol consumption and their influence on stomatologic lesions and their prognosis, will be discussed.

Multitarget fluorescence in situ hybridization elucidates equivocal lung cytology.

The category of equivocal respiratory cytology is a common diagnostic dilemma to both cytopathologists and clinicians. Chromosomal alterations are a hallmark of cancer but are rare or absent in benign conditions. The goal of this study was to test the ability of multitarget fluorescence in situ hybridization (FISH) for dissecting equivocal respiratory cytology into reactive and malignant categories. A consecutive series of 54 Papanicolaou-stained cytologic specimens of the lung was analyzed. The Papanicolaou-stained atypical cell groups were photographed, and the exact locations on the specimens were saved using automated stage and relocation software. The specimens were hybridized with a multitarget FISH probe that contains a mixture of fluorescent probes to the centromeric region of chromosome 6 and to the 5p15, 8q24 (site of the MYC gene) and 7p12 (site of the EGFR gene) loci. The hybridized atypical cells were selectively scored after relocation. A final diagnosis was available in 45 patients, revealing lung carcinoma in 55.5% (n = 25), no evidence of malignancy in 37.8% (n = 17), and pulmonary metastasis of another primary carcinoma in 6.7% (n = 3). FISH results were negative in all 17 patients with benign pulmonary disease and positive in 20 of the 25 patients (80%) with lung carcinoma (p < 0.0001). The sensitivity, specificity, and positive and negative predictive values for detection of malignancy were 79%, 100%, 100%, and 74%, respectively. These data suggest that multitarget FISH in conjunction with automated relocation is a powerful approach for the elucidation of equivocal lung cytology.

[White sponge naevus. Report of a family with respect to histopathologic, cytopathologic and DNA-cytometric aspects]. / Der weisse Schleimhautnävus. Ein Familienbericht unter Berücksichtigung histo- und zytopathologischer Aspekte sowie der DNA-Zytometriebefunde.

The white sponge naevus is a rare benign, hereditary autosomal dominant disorder of the mucosa. The oral mucosa is most often affected, but vaginal and anal mucosal surfaces may also be involved. Clinically, a whitish-grey, ragged, and folded surface that has no clear demarcation and appears sponge-like is characteristic, often creating problems in differential diagnosis. A potential risk for malignant transformation of white sponge naevus lesions has not been reported. The therapy for this benign hereditary disorder is unknown, however does not appear to be necessary. In the present report of a family with known white sponge naevus in three different generations, clinical, histopathologic, cytopathologic, DNA-cytomertric, and genetic aspects are described and discussed.

Cytologically malignant lymphoid pericardial effusion with benign clinical outcome.

BACKGROUND: Isolated malignant pericardial effusion is a manifestation of primary cardiac lymphoma (PCL) and primary effusion lymphoma (PEL), rare types of non-Hodgkin's lymphoma (NHL). The diagnosis is based on different cytological methods and analyses including DNA-image cytometry (ICM-DNA). DNA-aneuploidy has been reported to be highly specific for malignancy. CASE DESCRIPTIONS AND RESULTS: A 75-year-old man and a 66-year-old woman underwent urgent pericardiocentesis for cardiac tamponade due to large pericardial effusion. In both patients pericardial fluid analysis showed highly atypical blastic lymphoid cells expressing CD45 (both patients) and CD20 (assessed only in one patient), and ICM-DNA revealed significant DNA-aneuploidy (2c deviation index 9.22 and 10.73 respectively, 75% and 60% respectively of the target nuclei in aneuploid areas). Extensive staging examinations did not identify any other tumour manifestation. Although in neither of the two patients systemic chemotherapy was administered, both were free of cancer after a follow-up of ten and nine years respectively. CONCLUSIONS: Despite the highly atypical cytomorphology including unequivocal DNA aneuploidy, long-term survival in both patients strongly suggests that pronounced reactive lymphocytic changes are probably due to viral pericarditis rather than PCL or PEL as underlying conditions. It seems that DNA-aneuploidy may be not absolutely specific for the detection of malignant lymphoid cells in pericardial fluid.

Fluorescence in situ hybridization in the definitive diagnosis of malignant mesothelioma in effusion cytology.

BACKGROUND: Distinction of malignant mesothelioma (MM) from reactive mesothelial cells (RM) in effusions is notoriously difficult. The aim of our study was to test chromosomal aberrations detected by fluorescence in situ hybridization (FISH) in the diagnosis of MM in effusion cytology and to explore the potential role of p16, p14, and p15 gene methylation as an alternative mechanism of tumor suppressor gene inactivation. METHODS: Fifty-two effusions of biopsy-proven MM and 28 benign effusions were retrospectively analyzed by multitarget FISH assay for aberrations of chromosomes 3, 7, 17, and 9p21. In case of a negative result, the corresponding MM biopsy specimen was analyzed. Methylation-specific polymerase chain reaction (MSP) for p16, p14, and p15 was performed on FISH-negative MM biopsy specimens. RESULTS: Seventy-nine percent of effusions with biopsy-proven MM had chromosomal aberrations, with loss of 9p21 as the most common finding. All benign effusions were FISH negative. Sensitivity, specificity, and positive and negative predictive values for detection of MM by FISH were 79%, 100%, 100%, and 72%, respectively. Six of nine FISH-negative effusions with biopsy-proven MM were also FISH negative in the MM biopsy specimens. Four of five FISH-negative biopsy specimens showed promoter methylation in p16 and p14 as compared with one of 12 benign controls. CONCLUSIONS: FISH is a sensitive and highly specific method for the definitive diagnosis of MM in effusion cytology. In the subset of FISH-negative MM, tumor suppressor genes on the chromosomal region 9p21 are often inactivated by promoter methylation.

An online quiz uncovers limitations of morphology in equivocal lung cytology.

BACKGROUND: Equivocal atypia in respiratory cytology can be a diagnostic challenge. In such cases fluorescence in situ hybridization (FISH) may be used for the analysis of chromosomal aberrations and often allows a reliable distinction of benign and malignant cells. METHODS: An online picture gallery of 30 respiratory cytologic preparations comprising 23 specimens with equivocal cytology as well as 5 positive and 2 negative controls was prepared (www.unibas.ch/patho/lungenzyto/loesung). The final diagnoses were confirmed by clinical follow-up or biopsy or both. Each of the illustrated cell groups was analyzed by multitarget FISH after PAP image capturing and automatic relocalization. RESULTS: The online questionnaire was completed by 137 cytomorphologists from all continents. The control cases were assessed accurately to a significantly higher percentage than the equivocal cases. In equivocal cases participants more often made false-positive than false-negative diagnoses. In 2 patients with benign conditions (tuberculosis and pulmonary capillaritis) the rate of false-positive answers was remarkably high (31.4% and 62.8% respectively). The result of the 20 best-performing participants for the 5 cases with the highest percentage of inaccurate answers was not better than if they had chosen their answer by chance. CONCLUSIONS: These data illustrate that single cells or cell clusters of a subgroup of equivocal lung cytology are a diagnostic challenge even for highly experienced morphologists. Internet-based tests are able to reveal limitations of cytomorphology.