Involvement of napsin A in the C- and N-terminal processing of surfactant protein B in type-II pneumocytes of the human lung

Orthotopic Models Using New, Murine Lung Adenocarcinoma Cell Lines Simulate Human Non-Small Cell Lung Cancer Treated with Immunotherapy

Understanding tumor-host immune interactions and the mechanisms of lung cancer response to immunotherapy is crucial. Current preclinical models used to study this often fall short of capturing the complexities of human lung cancer and lead to inconclusive results. To bridge the gap, we introduce two new murine monoclonal lung cancer cell lines for use in immunocompetent orthotopic models. We demonstrate how our cell lines exhibit immunohistochemical protein expression (TTF-1, NapA, PD-L1) and common driver mutations (KRAS, p53, and p110α) seen in human lung adenocarcinoma patients, and how our orthotopic models respond to combination immunotherapy in vivo in a way that closely mirrors current clinical outcomes. These new lung adenocarcinoma cell lines provide an invaluable, clinically relevant platform for investigating the intricate dynamics between tumor and the immune system, and thus potentially contributes to a deeper understanding of immunotherapeutic approaches to lung cancer treatment.

Insights into the Tumor Microenvironment-Components, Functions and Therapeutics

Similarly to our healthy organs, the tumor tissue also constitutes an ecosystem. This implies that stromal cells acquire an altered phenotype in tandem with tumor cells, thereby promoting tumor survival. Cancer cells are fueled by abnormal blood vessels, allowing them to develop and proliferate. Tumor-associated fibroblasts adapt their cytokine and chemokine production to the needs of tumor cells and alter the peritumoral stroma by generating more collagen, thereby stiffening the matrix; these processes promote epithelial-mesenchymal transition and tumor cell invasion. Chronic inflammation and the mobilization of pro-tumorigenic inflammatory cells further facilitate tumor expansion. All of these events can impede the effective administration of tumor treatment; so, the successful inhibition of tumorous matrix remodeling could further enhance the success of antitumor therapy. Over the last decade, significant progress has been made with the introduction of novel immunotherapy that targets the inhibitory mechanisms of T cell activation. However, extensive research is also being conducted on the stromal components and other cell types of the tumor microenvironment (TME) that may serve as potential therapeutic targets.

Hypomorphic pathogenic variant in SFTPB leads to adult pulmonary fibrosis

Biallelic pathogenic variants in the surfactant protein (SP)-B gene (SFTPB) have been associated with fatal forms of interstitial lung diseases (ILD) in newborns and exceptional survival in young children. We herein report the cases of two related adults with pulmonary fibrosis due to a new homozygous SFTPB pathogenic variant, c.582G>A p.(Gln194=). In vitro transcript studies showed that this SFTPB synonymous pathogenic variant induces aberrant splicing leading to three abnormal transcripts with the preservation of the expression of a small proportion of normal SFTPB transcripts. Immunostainings on lung biopsies of the proband showed an almost complete loss of SP-B expression. This hypomorphic splice variant has thus probably allowed the patients' survival to adulthood while inducing an epithelial cell dysfunction leading to ILD. Altogether, this report shows that SFTPB pathogenic variants should be considered in atypical presentations and/or early-onset forms of ILD particularly when a family history is identified.

Novel opportunities from bioimaging to understand the trafficking and maturation of intracellular pulmonary surfactant and its role in lung diseases

Pulmonary surfactant (PS), a complex mixture of lipids and proteins, is essential for maintaining proper lung function. It reduces surface tension in the alveoli, preventing collapse during expiration and facilitating re-expansion during inspiration. Additionally, PS has crucial roles in the respiratory system's innate defense and immune regulation. Dysfunction of PS contributes to various respiratory diseases, including neonatal respiratory distress syndrome (NRDS), adult respiratory distress syndrome (ARDS), COVID-19-associated ARDS, and ventilator-induced lung injury (VILI), among others. Furthermore, PS alterations play a significant role in chronic lung diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). The intracellular stage involves storing and releasing a specialized subcellular organelle known as lamellar bodies (LB). The maturation of these organelles requires coordinated signaling to organize their intracellular organization in time and space. LB's intracellular maturation involves the lipid composition and critical processing of surfactant proteins to achieve proper functionality. Over a decade ago, the supramolecular organization of lamellar bodies was studied using electron microscopy. In recent years, novel bioimaging tools combining spectroscopy and microscopy have been utilized to investigate the in cellulo intracellular organization of lamellar bodies temporally and spatially. This short review provides an up-to-date understanding of intracellular LBs. Hyperspectral imaging and phasor analysis have allowed identifying specific transitions in LB's hydration, providing insights into their membrane dynamics and structure. A discussion and overview of the latest approaches that have contributed to a new comprehension of the trafficking and structure of lamellar bodies is presented.

Genetic Associations with Coronavirus Susceptibility and Disease Severity

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) global public health emergency, and the disease it causes is highly variable in its clinical presentation. Host genetic factors are increasingly recognised as a determinant of infection susceptibility and disease severity. Several initiatives and groups have been established to analyse and review host genetic epidemiology associated with COVID-19 outcomes. Here, we review the genetic loci associated with COVID-19 susceptibility and severity focusing on the common variants identified in genome-wide association studies.

Disulfide bonds in the SAPA domain of the pulmonary surfactant protein B precursor

The disulfide bonds formed in the SAPA domain of a recombinant version of the NH₂-terminal propeptide (SP-B_N) from the precursor of human pulmonary surfactant protein B (SP-B) were identified through sequential digestion of SP-B_N with GluC/trypsin or thermolysin/GluC, followed by mass spectrometry (MS) analysis. MS spectra allowed identification of disulfide bonds between Cys³²-Cys⁴⁹ and Cys⁴⁰-Cys⁵⁵, and we propose a disulfide connectivity pattern of 1-3 and 2-4 within the SAPA domain, with the Cys residues numbered according to their position from the N-terminus of the propeptide sequence. The peaks with m/z ∼ 2136 and ∼ 1780 in the MS spectrum of the GluC/trypsin digest were assigned to peptides ²⁴AWTTSSLACAQGPE³⁷ and ⁴⁵QALQCR⁵⁰ linked by Cys³²-Cys⁴⁹ and ³⁸FWCQSLE⁴⁴ and ⁵¹ALGHCLQE⁵⁸ linked by Cys⁴⁰-Cys⁵⁵ respectively. Tandem mass spectrometry (MS/MS) analysis verified the position of the bonds. The results of the series ions, immonium ions and internal fragment ions were all compatible with the proposed 1-3/2-4 position of the disulfide bonds in the SAPA domain. This X-pattern differs from the kringle-type found in the SAPB domain of the SAPLIP proteins, where the first Cys in the sequence links to the last, the second to the penultimate and the third to the fourth one. Regarding the SAPB domain of the SP-B_N propeptide, the MS analysis of both digests identified the bond Cys¹⁰⁰-Cys¹¹², numbered 7-8, which is coincident with the bond position in the kringle motif. SIGNIFICANCE: The SAPLIP (saposin-like proteins) family encompasses several proteins with homology to saposins (sphingolipids activator proteins). These are proteins with mainly alpha-helical folds, compact packing including well conserved disulfide bonds and ability to interact with phospholipids and membranes. There are two types of saposin-like domains termed as Saposin A (SAPA) and Saposin B (SAPB) domains. While disulfide connectivity has been well established in several SAPB domains, the position of disulfide bonds in SAPA domains is still unknown. The present study approaches a detailed proteomic study to determine disulfide connectivity in the SAPA domain of the precursor of human pulmonary surfactant-associated protein SP-B. This task has been a challenge requiring the combination of different sequential proteolytic treatments followed by MS analysis including MALDI-TOF and tandem mass MS/MS spectrometry. The determination for first time of the position of disulfide bonds in SAPA domains is an important step to understand the structural determinants defining its biological functions.

Immune and epithelial determinants of age-related risk and alveolar injury in fatal COVID-19

Respiratory failure in COVID-19 is characterized by widespread disruption of the lung’s alveolar gas exchange interface. To elucidate determinants of alveolar lung damage, we performed epithelial and immune cell profiling in lungs from 24 COVID-19 autopsies and 43 uninfected organ donors ages 18–92 years. We found marked loss of type 2 alveolar epithelial (T2AE) cells and increased perialveolar lymphocyte cytotoxicity in all fatal COVID-19 cases, even at early stages before typical patterns of acute lung injury are histologically apparent. In lungs from uninfected organ donors, there was also progressive loss of T2AE cells with increasing age, which may increase susceptibility to COVID-19–mediated lung damage in older individuals. In the fatal COVID-19 cases, macrophage infiltration differed according to the histopathological pattern of lung injury. In cases with acute lung injury, we found accumulation of CD4⁺ macrophages that expressed distinctly high levels of T cell activation and costimulation genes and strongly correlated with increased extent of alveolar epithelial cell depletion and CD8⁺ T cell cytotoxicity. Together, our results show that T2AE cell deficiency may underlie age-related COVID-19 risk and initiate alveolar dysfunction shortly after infection, and we define immune cell mediators that may contribute to alveolar injury in distinct pathological stages of fatal COVID-19.

Primary Nasal Epithelial Cells as a Surrogate Cell Culture Model for Type-II Alveolar Cells to Study ABCA-3 Deficiency

ATP Binding Cassette Subfamily A Member 3 (ABCA-3) is a lipid transporter protein highly expressed in type-II alveolar (AT-II) cells. Mutations in ABCA3 can result in severe respiratory disease in infants and children. To study ABCA-3 deficiency in vitro, primary AT-II cells would be the cell culture of choice although sample accessibility is limited. Our aim was to investigate the suitability of primary nasal epithelial cells, as a surrogate culture model for AT-II cells, to study ABCA-3 deficiency. Expression of ABCA3, and surfactant protein genes, SFTPB and SFTPC, was detected in primary nasal epithelial cells but at a significantly lower level than in AT-II cells. ABCA-3, SP-B, and SP-C were detected by immunofluorescence microscopy in primary nasal epithelial cells. However, SP-B and SP-C were undetectable in primary nasal epithelial cells using western blotting. Structurally imperfect lamellar bodies were observed in primary nasal epithelial cells using transmission electron microscopy. Functional assessment of the ABCA-3 protein demonstrated that higher concentrations of doxorubicin reduced cell viability in ABCA-3 deficient nasal epithelial cells compared to controls in an assay-dependent manner. Our results indicate that there may be a role for primary nasal epithelial cell cultures to model ABCA-3 deficiency in vitro, although additional cell culture models that more effectively recapitulate the AT-II phenotype may be required.

A Novel Strategy for the Diagnosis of Pulmonary High-Grade Neuroendocrine Tumor

Correctly diagnosing a histologic type of lung cancer is important for selecting the appropriate treatment because the aggressiveness, chemotherapy regimen, surgical approach, and prognosis vary significantly among histologic types. Pulmonary NETs, which are characterized by neuroendocrine morphologies, represent approximately 20% of all lung cancers. In particular, high-grade neuroendocrine tumors (small cell lung cancer and large cell neuroendocrine tumor) are highly proliferative cancers that have a poorer prognosis than other non-small cell lung cancers. The combination of hematoxylin and eosin staining, Ki-67, and immunostaining of classic neuroendocrine markers, such as chromogranin A, CD56, and synaptophysin, are normally used to diagnose high-grade neuroendocrine tumors; however, they are frequently heterogeneous. This article reviews the diagnostic methods of lung cancer diagnosis focused on immunostaining. In particular, we describe the usefulness of immunostaining by Stathmin-1, which is a cytosolic phosphoprotein and a key regulator of cell division due to its microtubule depolymerization in a phosphorylation-dependent manner, for the diagnosis of high-grade neuroendocrine tumors.

Napsin A Expression in Human Tumors and Normal Tissues

Background: Novel aspartic proteinase of the pepsin family A (Napsin A, TAO1/TAO2) is a functional aspartic proteinase which is involved in the maturation of prosurfactant protein B in type II pneumocytes and the lysosomal protein catabolism in renal cells. Napsin A is highly expressed in adenocarcinomas of the lung and is thus commonly used to affirm this diagnosis. However, studies have shown that other tumors can also express Napsin A.

Methods: To comprehensively determine Napsin A expression in normal and tumor tissue, 11,957 samples from 115 different tumor types and subtypes as well as 500 samples of 76 different normal tissue types were evaluable by immunohistochemistry on tissue microarrays.

Results: Napsin A expression was present in 16 different tumor types. Adenocarcinoma of the lung (85.6%), clear cell adenocarcinoma of the ovary (71.7%), clear cell adenocarcinoma of the endometrium (42.8%), papillary renal cell carcinoma (40.2%), clear cell (tubulo) papillary renal cell carcinoma (16.7%), endometrial serous carcinoma (9.3%), papillary thyroid carcinoma (9.3%) and clear cell renal cell carcinoma (8.2%) were among the tumors with the highest prevalence of Napsin A positivity. In papillary and clear cell renal cell carcinoma, reduced Napsin A expression was linked to adverse clinic-pathological features (p ≤ 0.03).

Conclusion: This methodical approach enabled us to identify a ranking order of tumors according to their relative prevalence of Napsin A expression. The data also show that loss of Napsin A is linked to tumor dedifferentiation in renal cell carcinomas.

The Tumor Proteolytic Landscape: A Challenging Frontier in Cancer Diagnosis and Therapy

In recent decades, dysregulation of proteases and atypical proteolysis have become increasingly recognized as important hallmarks of cancer, driving community-wide efforts to explore the proteolytic landscape of oncologic disease. With more than 100 proteases currently associated with different aspects of cancer development and progression, there is a clear impetus to harness their potential in the context of oncology. Advances in the protease field have yielded technologies enabling sensitive protease detection in various settings, paving the way towards diagnostic profiling of disease-related protease activity patterns. Methods including activity-based probes and substrates, antibodies, and various nanosystems that generate reporter signals, i.e., for PET or MRI, after interaction with the target protease have shown potential for clinical translation. Nevertheless, these technologies are costly, not easily multiplexed, and require advanced imaging technologies. While the current clinical applications of protease-responsive technologies in oncologic settings are still limited, emerging technologies and protease sensors are poised to enable comprehensive exploration of the tumor proteolytic landscape as a diagnostic and therapeutic frontier. This review aims to give an overview of the most relevant classes of proteases as indicators for tumor diagnosis, current approaches to detect and monitor their activity in vivo, and associated therapeutic applications.

Trafficking of newly synthesized surfactant protein B to the lamellar body in alveolar type II cells

Lung surfactant accumulates in the lamellar body (LB) via not only the secretory (anterograde) pathway but also the endocytic (retrograde) pathway. Our previous studies suggested that the major surfactant components, phosphatidylcholine and surfactant protein A take independent trafficking routes in alveolar type II cells. Thus, trafficking of surfactant protein B (SP-B), a major hydrophobic surfactant apoprotein, should be re-evaluated by a straightforward method. Radiolabeling of cells and subsequent cell fractionation were employed to pursue the sequential trafficking of newly synthesized SP-B in rabbit alveolar type II cells. The LB fraction was prepared by gradient ultracentrifugation. Immunoprecipitation from the culture medium, total cells, and LB fraction was carried out with anti-SP-B antibody. Newly synthesized [³⁵S]-pro-SP-B (~ 42 kDa) was detected in the cells after 1 h. An ~ 8-kDa mature form of [³⁵S]-SP-B was detected in the cells after 3 h and in the LB after 6 h. Mature [³⁵S]-SP-B was predominant in the cells after 24 h, and the dominant portion was present in the LB. In contrast, only a small amount of mature [³⁵S]-SP-B was present in the culture medium. Molecular processing of ~ 42 kDa [³⁵S]-pro-SP-B and transport to the LB was inhibited by brefeldin A, which disassembles the Golgi apparatus. These results suggest that newly synthesized SP-B is sorted to the LB via the Golgi and stored until exocytosis. This pathway is distinct from the pathways reported for phosphatidylcholine and surfactant protein A.

Recessive missense LAMP3 variant associated with defect in lamellar body biogenesis and fatal neonatal interstitial lung disease in dogs

Neonatal interstitial lung diseases due to abnormal surfactant biogenesis are rare in humans and have never been reported as a spontaneous disorder in animals. We describe here a novel lung disorder in Airedale Terrier (AT) dogs with clinical symptoms and pathology similar to the most severe neonatal forms of human surfactant deficiency. Lethal hypoxic respiratory distress and failure occurred within the first days or weeks of life in the affected puppies. Transmission electron microscopy of the affected lungs revealed maturation arrest in the formation of lamellar bodies (LBs) in the alveolar epithelial type II (AECII) cells. The secretory organelles were small and contained fewer lamellae, often in combination with small vesicles surrounded by an occasionally disrupted common limiting membrane. A combined approach of genome-wide association study and whole exome sequencing identified a recessive variant, c.1159G>A, p.(E387K), in LAMP3, a limiting membrane protein of the cytoplasmic surfactant organelles in AECII cells. The substitution resides in the LAMP domain adjacent to a conserved disulfide bond. In summary, this study describes a novel interstitial lung disease in dogs, identifies a new candidate gene for human surfactant dysfunction and brings important insights into the essential role of LAMP3 in the process of the LB formation.

Pepstatin pull-down at high pH is a powerful tool for detection and analysis of napsin A

Napsin A is an intracellular aspartic protease and biomarker of various malignancies like lung adenocarcinoma and ovarian clear cell carcinoma, but its detection is usually limited to immunohistochemical techniques gaining excellent information on its distribution but missing information about posttranslational modifications (e.g. maturation state) of the protein. We present a protocol for specific enrichment of napsin A from clinical or biological specimens, that facilitates detailed analysis of the protein. By using the exceptionally broad pH range under which napsin A binds to its inhibitor pepstatin A we achieve highly selective binding of napsin A while other aspartic proteases have negligible affinity. Using this method we demonstrate that lung napsin A in many mammals is a heterogeneous enzyme with a characteristic ladder-like appearance in SDS-PAGE that might be caused by proteolytically processed N- and/or C-termini, in contrast to the more homogeneous form found in kidneys and primary lung adenocarcinoma.

Napsin A is negatively associated with EMT‑mediated EGFR‑TKI resistance in lung cancer cells

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‑TKI) have been used as a standard therapy for patients with lung cancer with EGFR‑activating mutations. Epithelial‑mesenchymal transition (EMT) has been reported to be associated with the development of EGFR‑TKI resistance, which limits the clinical efficacy of EGFR‑TKI. Therefore, investigating the resistance‑associated mechanism is required in order to elucidate an effective therapeutic approach to enhance the sensitivity of lung cancer to EGFR‑TKI. In the present study, EGFR‑TKI erlotinib‑sensitive H358, H322 and H441 lung cancer cells, erlotinib‑moderately sensitive A549 cells, and erlotinib‑insensitive HCC827 cells with EGFR‑mutation (exon 19 deletion) were used to detect the mRNA and protein expression of the EMT‑associated proteins E‑cadherin and vimentin, and napsin A, by reverse transcription‑quantitative polymerase chain reaction analysis and western blotting. It was observed that the E‑cadherin expression level in erlotinib‑sensitive cells was increased compared with the moderately sensitive A549 cells and HCC827 cells; however, vimentin exhibited opposite expression, suggesting a correlation between EMT and erlotinib sensitivity in lung cancer cells. The napsin A expression level was observed to be positively associated with erlotinib sensitivity. In addition, napsin A highly‑expressingH322 cells were used and napsin A‑silenced cells were constructed using small interfering RNA (siRNA) technology, and were induced by transforming growth factor (TGF)‑βl. It was observed that TGF‑βl partially induced the alterations in E‑cadherin and vimentin expression and the occurrence of EMT in napsin A highly‑expressing cells, while TGF‑βl significantly induced EMT via downregulation of E‑cadherin and upregulation of vimentin in napsin A‑silenced cells; cell proliferation and apoptosis assays demonstrated that TGF‑βl induced marked resistance to erlotinib in napsin A‑silenced cells compared with napsin A‑expression cells. These data indicated that napsin A expression may inhibit TGF‑βl‑induced EMT and was negatively associated with EMT‑mediated erlotinib resistance, suggesting that napsin A expression may improve the sensitivity of lung cancer cells to EGFR‑TKI through the inhibition of EMT.

Homo- and hetero-oligomerization of hydrophobic pulmonary surfactant proteins SP-B and SP-C in surfactant phospholipid membranes

Pulmonary surfactant is a lipid/protein mixture that reduces surface tension at the respiratory air-water interface in lungs. Among its nonlipidic components are pulmonary surfactant-associated proteins B and C (SP-B and SP-C, respectively). These highly hydrophobic proteins are required for normal pulmonary surfactant function, and whereas past literature works have suggested possible SP-B/SP-C interactions and a reciprocal modulation effect, no direct evidence has been yet identified. In this work, we report an extensive fluorescence spectroscopy study of both intramolecular and intermolecular SP-B and SP-C interactions, using a combination of quenching and FRET steady-state and time-resolved methodologies. These proteins are compartmentalized in full surfactant membranes but not in pure 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) vesicles, in accordance with their previously described preference for liquid disordered phases. From the observed static self-quenching and homo-FRET of BODIPY-FL labeled SP-B, we conclude that this protein forms homoaggregates at low concentration (lipid:protein ratio, 1:1000). Increases in polarization of BODIPY-FL SP-B and steady-state intensity of WT SP-B were observed upon incorporation of under-stoichiometric amounts of WT SP-C. Conversely, Marina Blue-labeled SP-C is quenched by over-stoichiometric amounts of WT SP-B, whereas under-stoichiometric concentrations of the latter actually increase SP-C emission. Time-resolved hetero-FRET from Marina Blue SP-C to BODIPY-FL SP-B confirm distinct protein aggregation behaviors with varying SP-B concentration. Based on these multiple observations, we propose a model for SP-B/SP-C interactions, where SP-C might induce conformational changes on SP-B complexes, affecting its aggregation state. The conclusions inferred from the present work shed light on the synergic functionality of both proteins in the pulmonary surfactant system.

Clinicopathological Characteristics and Mutations Driving Development of Early Lung Adenocarcinoma: Tumor Initiation and Progression

Lung cancer is the leading cause of cancer-related deaths worldwide, with lung adenocarcinoma representing the most common lung cancer subtype. Among all lung adenocarcinomas, the most prevalent subset develops via tumorigenesis and progression from atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to minimally invasive adenocarcinoma (MIA), to overt invasive adenocarcinoma with a lepidic pattern. This stepwise development is supported by the clinicopathological and molecular characteristics of these tumors. In the 2015 World Health Organization classification, AAH and AIS are both defined as preinvasive lesions, whereas MIA is identified as an early invasive adenocarcinoma that is not expected to recur if removed completely. Recent studies have examined the molecular features of lung adenocarcinoma tumorigenesis and progression. EGFR-mutated adenocarcinoma frequently develops via the multistep progression. Oncogene-induced senescence appears to decrease the frequency of the multistep progression in KRAS- or BRAF-mutated adenocarcinoma, whose tumor evolution may be associated with epigenetic alterations and kinase-inactive mutations. This review summarizes the current knowledge of tumorigenesis and tumor progression in early lung adenocarcinoma, with special focus on its clinicopathological characteristics and their associations with driver mutations (EGFR, KRAS, and BRAF) as well as on its molecular pathogenesis and progression.

Pulmonary large cell neuroendocrine carcinoma with adenocarcinoma-like features: napsin A expression and genomic alterations

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a highly aggressive malignancy, which was recently found to comprise three major genomic subsets: small cell carcinoma-like, non-small cell carcinoma (predominantly adenocarcinoma)-like, and carcinoid-like. To further characterize adenocarcinoma-like subset, here we analyzed the expression of exocrine marker napsin A, along with TTF-1, in a large series of LCNECs (n=112), and performed detailed clinicopathologic and genomic analysis of napsin A-positive cases. For comparison, we analyzed napsin A expression in other lung neuroendocrine neoplasms (177 carcinoids, 37 small cell carcinomas) and 60 lung adenocarcinomas. We found that napsin A was expressed in 15% of LCNEC (17/112), whereas all carcinoids and small cell carcinomas were consistently negative. Napsin A reactivity in LCNEC was focal in 12/17 cases, and weak or moderate in intensity in all cases, which was significantly lower in the extent and intensity than seen in adenocarcinomas (P<0.0001). The combination of TTF-1-diffuse/napsin A-negative or focal was typical of LCNEC but was rare in adenocarcinoma, and could thus serve as a helpful diagnostic clue. The diagnosis of napsin A-positive LCNECs was confirmed by classic morphology, diffuse labeling for at least one neuroendocrine marker, most consistently synaptophysin, and the lack of distinct adenocarcinoma component. Genomic analysis of 14 napsin A-positive LCNECs revealed the presence of mutations typical of lung adenocarcinoma (KRAS and/or STK11) in 11 cases. In conclusion, LCNECs are unique among lung neuroendocrine neoplasms in that some of these tumors exhibit low-level expression of exocrine marker napsin A, and harbor genomic alterations typical of adenocarcinoma. Despite the apparent close biological relationship, designation of adeno-like LCNEC as a separate entity from adenocarcinoma is supported by their distinctive morphology, typically diffuse expression of neuroendocrine marker(s) and aggressive behavior. Further studies are warranted to assess the clinical utility and optimal method of identifying adenocarcinoma-like and other subsets of LCNEC in routine practice.

Napsin A levels in epithelial lining fluid as a diagnostic biomarker of primary lung adenocarcinoma

BACKGROUND

It is crucial to develop novel diagnostic approaches for determining if peripheral lung nodules are malignant, as such nodules are frequently detected due to the increased use of chest computed tomography scans. To this end, we evaluated levels of napsin A in epithelial lining fluid (ELF), since napsin A has been reported to be an immunohistochemical biomarker for histological diagnosis of primary lung adenocarcinoma.

METHODS

In consecutive patients with indeterminate peripheral lung nodules, ELF samples were obtained using a bronchoscopic microsampling (BMS) technique. The levels of napsin A and carcinoembryonic antigen (CEA) in ELF at the nodule site were compared with those at the contralateral site. A final diagnosis of primary lung adenocarcinoma was established by surgical resection.

RESULTS

We performed BMS in 43 consecutive patients. Among patients with primary lung adenocarcinoma, the napsin A levels in ELF at the nodule site were markedly higher than those at the contralateral site, while there were no significant differences in CEA levels. Furthermore, in 18 patients who were undiagnosed by bronchoscopy and finally diagnosed by surgery, the napsin A levels in ELF at the nodule site were identically significantly higher than those at the contralateral site. In patients with non-adenocarcinoma, there were no differences in napsin A levels in ELF. The area under the receiver operator characteristic curve for identifying primary lung adenocarcinoma was 0.840 for napsin A and 0.542 for CEA.

CONCLUSION

Evaluation of napsin A levels in ELF may be useful for distinguishing primary lung adenocarcinoma.

Experimental study of peripheral-blood pro-surfactant protein B for screening non-small cell lung cancer

Purpose:

To evaluate the possibility of using peripheral-blood presurfactant protein B (Pro-SFTPB) for screening non-small cell lung cancer (NSCLC).

Methods:

A total of 873 healthy volunteers and 165 lung cancer patients hospitalized in the Fifth People's Hospital of Dalian were tested Pro-SFTPB once every half year from January 2014 to September 2015. The healthy volunteers were also conducted spiral computed tomography (CT) examination once every year. The data were then com-pared and statistically analyzed.

Results:

The positive expression rate of Pro-SFTPB in NSCLC was significantly higher than that in healthy volunteers, and significantly higher in lung adenocarcinoma than in squamous cell carcinoma; additionally, the expression rate was increased with the in-crease of smoking index, and the intergroup differences showed statistical signifi-cance (p≤0.05). The positive rate of newly diagnosed lung cancer was 29.55%, higher than healthy volunteers (22.34%), but there was no significant difference (p>0.05).

Conclusion:

Pro-SFTPB is over expressed in non-small cell lung cancer, especially in lung adeno-carcinoma, but it can't be used as a clinical screening tool for lung cancer.

When Is an Alveolar Type 2 Cell an Alveolar Type 2 Cell? A Conundrum for Lung Stem Cell Biology and Regenerative Medicine

Generating mature, differentiated, adult lung cells from pluripotent cells, such as induced pluripotent stem cells and embryonic stem cells, offers the hope of both generating disease-specific in vitro models and creating definitive and personalized therapies for a host of debilitating lung parenchymal and airway diseases. With the goal of advancing lung-regenerative medicine, several groups have developed and reported on protocols using defined media, coculture with mesenchymal components, or sequential treatments mimicking lung development, to obtain distal lung epithelial cells from stem cell precursors. However, there remains significant controversy about the degree of differentiation of these cells compared with their primary counterparts, coupled with a lack of consistency or uniformity in assessing the resultant phenotypes. Given the inevitable, exponential expansion of these approaches and the probable, but yet-to-emerge second and higher generation techniques to create such assets, we were prompted to pose the question, what makes a lung epithelial cell a lung epithelial cell? More specifically for this Perspective, we also posed the question, what are the minimum features that constitute an alveolar type (AT) 2 epithelial cell? In addressing this, we summarize a body of work spanning nearly five decades, amassed by a series of "lung epithelial cell biology pioneers," which carefully describes well characterized molecular, functional, and morphological features critical for discriminately assessing an AT2 phenotype. Armed with this, we propose a series of core criteria to assist the field in confirming that cells obtained following a differentiation protocol are indeed mature and functional AT2 epithelial cells.

Fibroblastic foci, covered with alveolar epithelia exhibiting epithelial-mesenchymal transition, destroy alveolar septa by disrupting blood flow in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease of unknown cause. IPF has a distinct histopathological pattern of usual interstitial pneumonia in which fibroblastic foci (FF) represent the leading edge of fibrotic destruction of the lung. Currently there are three major hypotheses for how FF are generated: (1) from resident fibroblasts, (2) from bone marrow-derived progenitors of fibroblasts, and (3) from alveolar epithelial cells that have undergone epithelial-mesenchymal transition (EMT). We found that FF dissociated capillary vessels from the alveolar epithelia, the basement membranes of which are fused in normal physiological conditions, and pushed the capillaries and elastic fibers down ~100 μm below the alveolar epithelia. Furthermore, the alveolar epithelial cells covering the FF exhibited a partial EMT phenotype. In addition, normal human alveolar epithelial cells in vitro underwent dynamic EMT in response to transforming growth factor-β signaling within 72 h. Because it seems that resident fibroblasts or bone marrow-derived cells cannot easily infiltrate and form FF between the alveolar epithelia and capillaries in tight contact with each other, FF are more likely to be derived from the epithelial-to-mesenchymal transitioned alveolar epithelia located over them. Moreover, histology and immunohistochemistry suggested that the FF formed in the lung parenchyma disrupt blood flow to the alveolar septa, thus destroying them. Consequently, collapse of the alveolar septa is likely to be the first step toward honeycombing in the lung during late stage IPF. On the basis of these findings, inhibition of transforming growth factor-β signaling, which can suppress EMT of the alveolar epithelial cells in vitro, is a potential strategy for treating IPF.

Lung surfactant metabolism: early in life, early in disease and target in cell therapy

Lung surfactant is a complex mixture of lipids and proteins lining the alveolar epithelium. At the air-liquid interface, surfactant lowers surface tension, avoiding alveolar collapse and reducing the work of breathing. The essential role of lung surfactant in breathing and therefore in life, is highlighted by surfactant deficiency in premature neonates, which causes neonatal respiratory distress syndrome and results in early death after birth. In addition, defects in surfactant metabolism alter lung homeostasis and lead to disease. Special attention should be paid to two important key cells responsible for surfactant metabolism: alveolar epithelial type II cells (AE2C) and alveolar macrophages (AM). On the one hand, surfactant deficiency coming from abnormal AE2C function results in high surface tension, promoting alveolar collapse and mechanical stress in the epithelium. This epithelial injury contributes to tissue remodeling and lung fibrosis. On the other hand, impaired surfactant catabolism by AM leads to accumulation of surfactant in air spaces and the associated altered lung function in pulmonary alveolar proteinosis (PAP). We review here two recent cell therapies that aim to recover the activity of AE2C or AM, respectively, therefore targeting the restoring of surfactant metabolism and lung homeostasis. Applied therapies successfully show either transplantation of healthy AE2C in fibrotic lungs, to replace injured AE2C cells and surfactant, or transplantation of bone marrow-derived macrophages to counteract accumulation of surfactant lipid and proteinaceous material in the alveolar spaces leading to PAP. These therapies introduce an alternative treatment with great potential for patients suffering from lung diseases.

Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling

Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.

Using electron microscopes to look into the lung

In the nineteenth century, there was a dispute about the existence of a lung alveolar epithelium which remained unsolved until the invention of electron microscopy (EM) and its application to the lung. From the early 1960s, Ewald Weibel became the master of lung EM. He showed that the alveolar epithelium is covered with a lining layer containing surfactant. Weibel also explained the phenomenon of "non-nucleated plates" observed already in 1881 by Albert Kölliker. Weibel's most significant contribution was to the development of stereological methods. Therefore, quantitative characterization of lung structure revealing structure-function relationships became possible. Today, the spectrum of EM methods to study the fine structure of the lung has been extended significantly. Cryo-preparation techniques are available which are necessary for immunogold labeling of molecules. Energy-filtering techniques can be used for the detection of elements. There have also been major improvements in stereology, thus providing a very versatile toolbox for quantitative lung phenotype analyses. A new dimension was added by 3D EM techniques. Depending on the desired sample size and resolution, the spectrum ranges from array tomography via serial block face scanning EM and focused ion beam scanning EM to electron tomography. These 3D datasets provide new insights into lung ultrastructure. Biomedical EM is an ever-developing field. Its high resolution remains unparalleled. Moreover, EM has the unique advantage of providing an "open view" into cells and tissues within their full architectural context. Therefore, EM will remain an indispensable tool for a better understanding of the lung's functional design.

Immunohistochemical Comparison of Ovarian and Uterine Endometrioid Carcinoma, Endometrioid Carcinoma With Clear Cell Change, and Clear Cell Carcinoma

Accurate distinction of clear cell carcinoma (CCC) from endometrioid carcinoma (EC) has important clinical implications, but, not infrequently, EC demonstrates clear cell change (EC-CC), mimicking CCC. We examined whether a panel of immunomarkers can help distinguish between these tumors. Sixty-four CCCs (40 ovarian and 24 uterine), 34 ECs (21 ovarian and 13 uterine), and 34 EC-CCs (6 ovarian and 28 uterine) were stained for HNF1β, BAF250a, Napsin A, ER, and PR. Intensity and extent of immunoreactivity was assessed. Fifty-seven of 64 (89%) CCCs, 14/34 (41%) EC-CCs, and 16/34 (47%) ECs expressed HNF1β, and 56/64 (88%) CCCs, 4/34 (12%) EC-CCs, and 1/34 (3%) ECs stained for Napsin A. Most CCCs demonstrated at least moderate and diffuse staining for both markers, whereas only focal and weak expression was identified in most EC-CC/EC. Compared to HNF1β, Napsin A showed increased specificity (93.0% vs. 55.9%, P<0.0001) and similar sensitivity (87.5% vs. 89.1%) in distinguishing CCC from EC-CC/EC. Thirteen of 64 (20%) CCCs, 6/34 (18%) EC-CCs, and 2/34 (6%) ECs showed loss of BAF250a. ER was expressed by 10/64 (16%) CCCs, 30/34 (88%) EC-CCs, and 33/34 (97%) ECs, whereas PR positivity was identified in 9/64 (14%) CCCs, 26/34 (77%) EC-CCs, and 33/34 (97%) ECs. The majority of EC and EC-CC demonstrated diffuse staining for ER/PR, whereas most CCCs showed very focal positivity. There is a statistically significant difference in HNF1β, Napsin A, ER, and PR immunoexpression between CCC and EC/EC-CC, with Napsin A being a more specific marker for CCC than HNF1β. Overall, the immunoprofile of EC-CC is more comparable to that of EC than CCC. The use of a panel of immunostains can help distinguish EC-CC from CCC.

The expression of TTF-1 and Napsin A in early-stage lung adenocarcinoma correlates with the results of surgical treatment

Non-small cell lung cancer (NSCLC) accounts for 80 % of lung cancers, and lung adenocarcinoma (ADC) is one of the main types of NSCLC. Although there are several studies on the relationship between lung ADC immunohistochemical diagnostic markers (thyroid transcription factor 1 (TTF-1) and Napsin A) and survival, some aspects of those studies could be improved. We examined the significance of the commonly used lung ADC diagnostic markers, including TTF-1, Napsin A, and CK7, in the prognosis of early-stage lung ADC. One hundred and nineteen cases of early-stage lung ADC (N0) were selected from the prospective database of lung cancer (Jan 2000 to Dec 2009). The expression levels of TTF-1, Napsin A, and CK7 in inventoried specimens were analyzed using tissue microarray (TMA) and immunohistochemical (IHC) analysis, and the effect of the expression level of each marker on patients' survival was examined. The diagnostic sensitivity and specificity of each marker for lung ADC were as follows: TTF-1, 87.0 and 90.1 %; Napsin A, 72.2 and 90.4 %; and CK7, 94.6 and 76.0 %, respectively. Patients with high expression levels of TTF-1 and Napsin A, and high co-expression levels of TTF-1/Napsin A had better survival rates than those with low levels of expression (P < 0.05). The expression levels of CK7 were not related to patients' survival. Multivariate analysis showed that the expression levels of Napsin A and TTF-1/Napsin A are independent prognostic factors for survival. The IHC detection of TTF-1 and Napsin A in specimens should be routinely performed in postoperative early-stage lung ADC patients. Its significance lies not only in the differential diagnosis, but also in determining the prognosis.

Utility of five commonly used immunohistochemical markers TTF-1, Napsin A, CK7, CK5/6 and P63 in primary and metastatic adenocarcinoma and squamous cell carcinoma of the lung: a retrospective study of 246 fine needle aspiration cases

BACKGROUND

Fine needle aspiration (FNA) biopsy plays a critical role in the diagnosis and staging of lung primary and metastatic lung carcinoma. Accurate subclassification of adenocarcinoma (ADC) and/or squamous cell carcinoma (SqCC) is crucial for the targeted therapy. However, the distinction between ADC and SqCC may be difficult in small FNA specimens. Here, we have retrospectively evaluated the utility of TTF-1, Napsin A, CK7, P63 and CK5/6 immunohistochemical (IHC) markers in the distinguishing and subclassification of ADC and SqCC.

METHODS

A total of 246 FNA cases were identified by a computer search over a two-year period, including 102 primary NSCLC and 144 primary NSCLC which had metastasized to other sites. The immunostaining patterns of TTF-1, Napsin A, CK7, P63 and CK5/6 were correlated with the histological diagnosis of the tumor.

RESULTS

In 72 primary ADCs, TTF-1, Napsin A and CK7 showed a sensitivity and specificity of 84.5%/96.4%, 92.0%/100%, and 93.8%/50.0%. In 30 primary SqCCs, CK5/6 and P63 showed a sensitivity and specificity of 100%/77.8% and 91.7%/78.3%. In 131 metastatic ADCs, Napsin A showed the highest specificity (100%), versus TTF-1 (87.5%) and CK7 (25%) but decreased sensitivity (67.8% versus 86.9% and 100%); whereas in 13 metastatic SqCCs, CK5/6 and P63 showed a sensitivity/specificity of 100%/84.6% and 100%/68.4%. Bootstrap analysis showed that the combination of TTF-1/CK7, TTF-1/Napsin A and TTF-1/CK7/Napsin A had a sensitivity/specificity of 0.960/0.732, 0.858/0.934, 0.972/0.733 for primary lung ADCs and 0.992/0.642, 0.878/0.881, 0.993/0.618 for metastatic lung ADCs.

CONCLUSIONS

Our study demonstrated that IHC markers had variable sensitivity and specificity in the subclassification of primary and metastatic ADC and SqCC. Based on morphological findings, an algorithm with the combination use of markers aided in the subclassification of NSCLCs in difficult cases.

Napsin A is a specific marker for ovarian clear cell adenocarcinoma

Ovarian clear cell adenocarcinoma has a relatively poor prognosis among the ovarian cancer subtypes because of its high chemoresistance. Differential diagnosis of clear cell adenocarcinoma from other ovarian surface epithelial tumors is important for its treatment. Napsin A is a known diagnostic marker for lung adenocarcinoma, and expression of napsin A is reported in a certain portion of thyroid and renal carcinomas. However, napsin A expression in ovarian surface epithelial tumors has not previously been examined. In this study, immunohistochemical analysis revealed that in 71 of 86 ovarian clear cell adenocarcinoma patients (83%) and all of the 13 patients with ovarian clear cell adenofibroma, positive napsin A staining was evident. No expression was observed in 30 serous adenocarcinomas, 11 serous adenomas or borderline tumors, 19 endometrioid adenocarcinomas, 22 mucinous adenomas or borderline tumors, 10 mucinous adenocarcinomas, or 3 yolk sac tumors of the ovary. Furthermore, expression of napsin A was not observed in the normal surface epithelium of the ovary, epithelia of the fallopian tubes, squamous epithelium, endocervical epithelium, or the endometrium of the uterus. Therefore, we propose that napsin A is another sensitive and specific marker for distinguishing ovarian clear cell tumors (especially adenocarcinomas) from other ovarian tumors.

Structure-function relationships in pulmonary surfactant membranes: from biophysics to therapy

Pulmonary surfactant is an essential lipid-protein complex to maintain an operative respiratory surface at the mammalian lungs. It reduces surface tension at the alveolar air-liquid interface to stabilise the lungs against physical forces operating along the compression-expansion breathing cycles. At the same time, surfactant integrates elements establishing a primary barrier against the entry of pathogens. Lack or deficiencies of the surfactant system are associated with respiratory pathologies, which treatment often includes supplementation with exogenous materials. The present review summarises current models on the molecular mechanisms of surfactant function, with particular emphasis in its biophysical properties to stabilise the lungs and the molecular alterations connecting impaired surfactant with diseased organs. It also provides a perspective on the current surfactant-based strategies to treat respiratory pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Immunohistochemical study of 36 cases of pulmonary sarcomatoid carcinoma--sensitivity of TTF-1 is superior to napsin

Immunohistochemistry is often used to distinguish pulmonary sarcomatoid carcinoma from morphologic mimics. Napsin-A is a pulmonary adenocarcinoma marker, but literature on expression in sarcomatoid carcinoma is limited. Thirty-six cases of sarcomatoid carcinoma were stained for napsin, TTF-1, Oscar, CAM5.2, AE1/AE3, desmin, SMA, S-100, CK5/6, calretinin, D2-40, and WT1. Patients were 24 men and 12 women (mean, 70 years; range, 46-93). There were 27 pleomorphic carcinomas, 5 spindle cell carcinomas, 3 carcinosarcomas, and 1 giant cell carcinoma. Cases were positive for at least 1 keratin: AE1/3 was positive in all 36 cases; Oscar, in 34 cases (94%); and CAM5.2, in 32 cases (89%, weaker/more focal). Napsin was positive in 14 cases (39%): 8 diffuse, 3 focal, and 3 rare cells. TTF-1 was positive in 22 cases (61%): 15 diffuse, 3 focal, and 4 rare cells. No cases were napsin positive and negative for TTF-1. Variable staining for mesothelial markers was observed, including positivity for calretinin (12 cases, 33%), WT1 (6 cases, 17%), D2-40 (5 cases, 14%), and CK5/6 (9 cases, 25%). Mesenchymal markers were also sometimes positive (usually focal), including S-100 (4 cases, 11%), desmin (4 cases, 11%), and SMA (7 cases, 19%, 1 diffuse). In conclusion, TTF-1 is more sensitive than napsin for detection of sarcomatoid carcinoma, and no cases were positive for napsin but negative for TTF-1. CAM5.2 is less sensitive than AE1/AE3 and Oscar. Use of a thoughtful immunohistochemical panel is important in the evaluation of sarcomatoid carcinoma because mesothelial and mesenchymal markers can be expressed.

Napsin A expression in primary mucin-producing adenocarcinomas of the lung: an immunohistochemical study

Immunohistochemical expression of napsin A in primary pulmonary mucinous tumors is not well established. Napsin A immunoreactivity was evaluated in 43 mucin-producing adenocarcinomas of the lung consisting of 18 tumors formerly classified as mucinous bronchioloalveolar carcinoma, 15 colloid adenocarcinomas, 5 solid predominant adenocarcinomas with mucin production, and 5 adenocarcinomas with signet ring cell features, as well as in 25 extrapulmonary mucinous adenocarcinomas of different anatomic sites. Immunohistochemical expression of thyroid transcription factor 1 (TTF-1) was also compared. Thirty-three percent of mucinous lung tumors exhibited positive immunoreactivity for napsin A, whereas 42% expressed TTF-1. All 25 extrapulmonary mucinous adenocarcinomas lacked expression of napsin A and TTF-1. Mucin-producing neoplasms of the lung infrequently express napsin A, suggesting that immunohistochemical assessment of napsin A may have limited diagnostic usefulness for distinguishing primary and metastatic mucinous adenocarcinomas involving the lung.

Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update

A large number of immunohistochemical markers that can assist in the differential diagnosis of epithelioid mesotheliomas are currently available. Because these markers are expressed differently in the various types of carcinomas that can metastasize to the serosal membranes and can potentially be confused with epithelioid mesothelioma, their selection for inclusion in a diagnostic panel largely depends on the differential diagnosis, as well as on which ones work the best in a given laboratory. Traditionally, the panels used in the differential diagnosis of epithelioid mesothelioma have consisted of a combination of positive mesothelioma markers and broad-spectrum carcinoma markers. At present, a wide variety of organ-associated carcinoma markers such as thyroid transcription factor-1 and napsin A for the lung, PAX 8 and PAX 2 for the kidney, and Müllerian-derived tumors; gross cystic disease fluid protein-15 and mammaglobin for the breast; and CDX2 for intestinal differentiation are available, which can assist in establishing the site of origin of an adenocarcinoma when included in a diagnostic panel. This article provides updated information on the composition of the panels of markers recommended in the various differential diagnoses.

Napsin A, a new marker for lung adenocarcinoma, is complementary and more sensitive and specific than thyroid transcription factor 1 in the differential diagnosis of primary pulmonary carcinoma: evaluation of 1674 cases by tissue microarray

CONTEXT

Differentiation of non-small cell carcinoma into histologic types is important because of new, successful therapies that target lung adenocarcinoma (ACA). TTF-1 is a favored marker for lung ACA but has limited sensitivity and specificity. Napsin A (Nap-A) is a functional aspartic proteinase that may be an alternative marker for primary lung ACA.

OBJECTIVES

To compare Nap-A versus TTF-1 in the typing of primary lung carcinoma and the differentiation of primary lung ACA from carcinomas of other sites.

DESIGN

Immunohistochemistry for Nap-A and TTF-1 was performed on tissue microarrays of 1674 cases of carcinoma: 303 primary lung ACAs (18.1%), 200 primary squamous cell lung carcinomas (11.9%), 52 primary small cell carcinomas of the lung (3.1%), and carcinomas of the kidney (n  =  320; 19.1%), thyroid (n  =  96; 5.7%), biliary (n  =  89; 5.3%), bladder (n  =  47; 2.8%), breast (n  =  93; 5.6%), colon (n  =  95; 5.7%), liver (n  =  96; 5.7%), ovaries (n  =  45; 2.7%), pancreas (n  =  48; 2.9%), prostate (n  =  49; 2.9%), stomach (n  =  93; 5.6%), and uterus (n  =  48; 2.9%). Cases were evaluated against a negative control as negative, weak positive, and strong positive.

RESULTS

Nap-A was more sensitive than TTF-1 for primary lung ACA (87% versus 64%; P < .001). Nap-A was more specific than TTF-1 for primary lung ACA versus all tumors, excluding kidney, independent of tumor type (P < .001).

CONCLUSIONS

Nap-A is superior to TTF-1 in distinguishing primary lung ACA from other carcinomas (except kidney), particularly primary lung small cell carcinoma, and primary thyroid carcinoma. A combination of Nap-A and TTF-1 is useful in the distinction of primary lung ACA (Nap-A(+), TTF-1(+)) from primary lung squamous cell carcinoma (Nap-A(-), TTF-1(-)) and primary lung small cell carcinoma (Nap-A(-), TTF-1(+)).

Multi-tier regulation of the streptomycete morphogenetic peptide SapB

Streptomyces coelicolor is a morphologically complex bacterium requiring the secretion of surface-active proteins to progress through its life cycle. SapB represents an important class of these biosurfactants, as illustrated by its ability to restore aerial hyphae formation when applied exogenously to developmental mutants. However, such aerial hyphae fail to sporulate, exemplifying the need to co-ordinate the timing of SapB production with other developmental events. SapB has an unusual lantibiotic structure. Its structural gene, ramS, is only 38 nucleotides downstream of the gene encoding its putative modification enzyme, RamC. Transient, co-ordinated expression of the operon was thought to be controlled by the response regulator RamR. However, we show that ramS is transcribed throughout the cell cycle with a dual expression profile dissimilar to the tightly controlled ramC expression. Surprisingly, post-translational modification relies on prior membrane localization of the precursor peptide, RamS, as demonstrated by the absence of RamS modification in S. coelicolor hyphae treated with the Bacillus subtilis lipoprotein surfactin. Our results demonstrate that interspecies interaction can also be mediated by interference of post-translational events. Further, temporal and spatial regulation of irreversible post-translational modification of a surface-active morphogenetic peptide suggests a new model for the control of key developmental events.

Napsin A is an independent prognostic factor in surgically resected adenocarcinoma of the lung

INTRODUCTION

Napsin A is regarded as a marker of lung adenocarcinoma. However, no comprehensive analyses of napsin A-positive lung ADCs or the prognostic significance of napsin A expression have been reported to date.

METHODS

110 primary lung adenocarcinoma cases were analyzed for clinicopathologic parameters, including overall survival, stage, histology, napsin A and TTF-1 expression, EGFR mutation, and ALK rearrangement.

RESULTS

Napsin A-positive adenocarcinomas were significantly more prevalent among tumors characterized as relatively small (p = 0.023), non-solid predominant (p < 0.001), non-mucinous/enteric (p < 0.001), positive for TTF-1 expression (p < 0.001), and positive for EGFR mutation (p = 0.001). Multivariate analysis of overall survival demonstrated that the absence of napsin A was an independent prognostic factor for reduced survival time (p = 0.002).

CONCLUSION

Clinicopathologic characteristics associated with napsin A-positive lung ADC are similar to and overlap with those of TTF-1-positive ADCs. The absence of napsin A is an independent poor prognostic factor in surgically resected adenocarcinoma. Further studies are necessary to determine the role of napsin A in the progression of lung adenocarcinoma.

Napsin A expression in lung and kidney neoplasia: a review and update

Napsin A is an aspartic protease present in the epithelial cells of the lung and kidney. Recent studies have shown that, in lung tumors, napsin A expression is restricted to lung adenocarcinomas, whereas among renal tumors, it is frequently expressed in renal cell carcinomas, especially the papillary and clear cell subtypes. Owing to its restricted expression, napsin A is a useful marker that can assist in the diagnosis of both lung adenocarcinomas and renal cell carcinomas.

Indispensable role of factor for adipocyte differentiation 104 (fad104) in lung maturation

Factor for adipocyte differentiation 104 (fad104) is a regulator of adipogenesis and osteogenesis. Our previous study showed that fad104-deficient mice died immediately after birth, suggesting fad104 to be essential for neonatal survival. However, the cause of this rapid death is unclear. Here, we demonstrate the role of fad104 in neonatal survival. Phenotypic and morphological analyses showed that fad104-deficient mice died due to cyanosis-associated lung dysplasia including atelectasis. Furthermore, immunohistochemistry revealed that FAD104 was strongly expressed in ATII cells in the developing lung. Most importantly, the ATII cells in lungs were immature, and impaired the expression of surfactant-associated proteins. Collectively, these results indicate that fad104 has an indispensable role in lung maturation, especially the maturation and differentiation of ATII cells.

Generation and evaluation of a monoclonal antibody, designated MAdL, as a new specific marker for adenocarcinomas of the lung

Background:

Different therapy regimens in non-small-cell lung cancer (NSCLC) are of rising clinical importance, and therefore a clear-cut subdifferentiation is mandatory. The common immunohistochemical markers available today are well applicable for subdifferentiation, but a fraction of indistinct cases still remains, demanding upgrades of the panel by new markers.

Methods:

We report here the generation and evaluation of a new monoclonal antibody carrying the MAdL designation, which was raised against primary isolated human alveolar epithelial cells type 2.

Results:

Upon screening, one clone (MAdL) was identified as a marker for alveolar epithelial cell type II, alveolar macrophages and adenocarcinomas of the lung. In a large-scale study, this antibody, with an optimised staining procedure for formalin-fixed tissues, was then evaluated together with the established markers thyroid transcription factor-1, surfactant protein-A, pro-surfactant protein-B and napsin A in a series of 362 lung cancer specimens. The MAdL displays a high specificity (>99%) for adenocarcinomas of the lung, together with a sensitivity of 76.5%, and is capable of delivering independent additional diagnostic information to the established markers.

Conclusion:

We conclude that MAdL is a new specific marker for adenocarcinomas of the lung, which helps to clarify subdifferentiation in a considerable portion of NSCLCs.

The surfactant lipid transporter ABCA3 is N-terminally cleaved inside LAMP3-positive vesicles

ABCA3 mutations cause fatal surfactant deficiency and interstitial lung disease. ABCA3 protein is a lipid transporter indispensible for surfactant biogenesis and storage in lamellar bodies (LB). The protein folds in endoplasmic reticulum and is glycosylated in Golgi en route to the membrane of mature LB and their precursor multivesicular bodies (MVB). In immunoblots, C-terminally labeled ABCA3 appears as two protein bands of 150 and 190 kDa. Using N- and C-terminal protein tags and hindering ABCA3 processing we show that the 150 kDa protein represents the mature ABCA3 whose N-terminus is cleaved by a cysteine protease inside MVB/LB.

Pulmonary surfactant pathophysiology: current models and open questions

Pulmonary surfactant is an essential lipid-protein complex that stabilizes the respiratory units (alveoli) involved in gas exchange. Quantitative or qualitative derangements in surfactant are associated with severe respiratory pathologies. The integrated regulation of surfactant synthesis, secretion, and metabolism is critical for air breathing and, ultimately, survival. The goal of this review is to summarize our current understanding and highlight important knowledge gaps in surfactant homeostatic mechanisms.

Value of napsin A and thyroid transcription factor-1 in the identification of primary lung adenocarcinoma

Napsin A is a newly discovered functional aspartic proteinase that is expressed in normal lung parenchyma in type II pneumocytes and is thought to be associated with primary lung adenocarcinoma. Thyroid transcription factor-1 (TTF-1) is a widely used relatively restricted marker for lung adenocarcinoma. The present study aimed to compare the usefulness of napsin A with TTF-1 for the identification of primary lung adenocarcinoma. Immunohistochemical expression of napsin A and TTF-1 was analyzed in 351 lung cancer tissues, including 27 metastases. Napsin A was expressed in 180 of 212 (84.9%) primary lung adenocarcinomas, while no expression was noted in all 27 metastatic lung cancer specimens, including 19 metastatic adenocarcinomas. In contrast, TTF-1 expression was not only noted in 179 of 212 (84.4%) primary lung adenocarcinomas, but also in 12 of 18 (66.7%) small-cell carcinomas and some of the squamous carcinomas, as well as in one metastatic adenocarcinoma from the thyroid. The sensitivity and specificity of napsin A for primary lung adenocarcinoma (84.9 and 93.8%, respectively) were higher than the sensitivity and specificity of TTF-1 (84.4 and 83.9%, respectively). By combining napsin A and TTF-1, sensitivity increased to 91.0%. Furthermore, the sensitivity and specificity expression was associated with gender, smoking history, performance status, pathological type, primary tumor size and nodal metastasis. Therefore, napsin A is a useful novel marker in the differential diagnosis of primary lung adenocarcinoma.