The World Health Organization Reporting System for Lung Cytopathology-A Review of the First Edition.

The World Health Organization Reporting System for Lung Cytopathology is the first international system that was developed to standardize the reporting of lung cytopathology specimens across all settings of cytopathology practice. The system is composed of five diagnostic categories, which apply to all lung cytopathology specimen types. Each category contains cytomorphologic criteria, an estimated risk of malignancy, and clinical management recommendations. International uniformity in the reporting of lung cytopathology will refine the communication between cytopathologists and clinicians and ultimately improve patient care. Furthermore, standardizing the cytomorphologic criteria for each lesion will improve reproducibility among cytopathologists and highlight areas in lung cytopathology that require further research. The system also provides best practice recommendations for the selection of ancillary tests to aid in the diagnosis of each lesion, or group of lesions, keeping in mind that resources will vary across different practice settings. The goal of this review is to summarize the cytomorphologic criteria, potential diagnostic pitfalls, ancillary testing, estimated risk of malignancy, and clinical management recommendations for each diagnostic category.

Breast Carcinoma With Tubulopapillary Features Has a Distinct Immunophenotypic and Molecular Signature: A Report of Two Tumors and Literature Review.

Breast carcinoma with tubulopapillary features is a newly described entity associated with poor prognosis with only 14 tumors reported in the literature. We report 2 additional tumors and identify novel immunohistochemical and molecular features of the tumor. The first tumor was from a 72-year-old woman with nonmetastatic breast carcinoma and the second was from a 32-year-old woman with metastatic breast carcinoma who received neoadjuvant therapy. Both tumors had high-grade nuclear features with a distinctive morphology characterized by infiltrating open glands with intratubular papillary and micropapillary projections in >90% of the invasive carcinoma. In addition to the usual predictors of aggressive behavior, both tumors showed a high expression of p16 and SOX10, which has not been previously described. Targeted tumor sequencing revealed pathogenic variants of TP53 in both tumors, in agreement with previous reports. Prior studies have shown a correlation between p16 and SOX10 expression with high-grade features and worse prognosis; typically seen in triple-negative carcinomas as demonstrated in both of our tumors. However, not all reported tumors of breast carcinoma with tubulopapillary features have demonstrated a triple-negative profile as there are a few reports of tumors with estrogen receptor and/or human epidermal growth factor 2 expression. Due to their distinct morphologic and molecular characteristics, breast carcinoma with tubulopapillary features may represent a new breast cancer histologic subtype.

Increased Expression of LEF1 and ß-Catenin in Invasive Micropapillary Carcinoma of the Breast is Associated With Lymphovascular Invasion and Lymph Node Metastasis.

Invasive micropapillary breast carcinoma (IMPC) is a rare breast cancer subtype characterized by small tumor cell clusters with loss of stromal attachment, an inside-out growth appearance, and lymphotropism. IMPC is associated with high incidence of lymphovascular invasion (LVI) and lymph node metastasis. Activated Wnt signaling has been implicated in the metastasis of other aggressive breast tumors, including triple-negative and basal-like carcinomas. In this study, we tested whether activated Wnt signaling could be detected in IMPC. Upon ligand binding, the central mediator of the Wnt pathway, ß-catenin, accumulates in the cytosol and translocates to the nucleus where it forms a complex with lymphoid enhancer-binding factor 1 (LEF1) to regulate transcription. We performed immunostaining for ß-catenin and LEF1 on a well-annotated cohort of 40 breast tumors and nodal metastases displaying micropapillary histopathology. Strong nuclear accumulation of ß-catenin was not observed, however a dim cytosolic and/or nuclear accumulation of ß-catenin was sometimes seen in IMPC and this expression pattern was significantly associated with nodal metastasis. ß-catenin expression correlated with the upregulation of LEF1 in IMPC. LEF1 expression was detected in 26 of 40 (65%) cases and was specifically enriched at the invasive front of the tumor and in tumor clusters undergoing LVI. Detection of LEF1 expression in the primary tumor was associated with an increased rate of LVI, lymph node metastasis, and disease relapse. LEF1 and ß-catenin expression levels were significantly higher in metastases compared with primary tumors. In summary, this study demonstrates an association between the upregulation of ß-catenin/LEF1 and the metastasis of IMPC.

Drosophila ML-DmD17-c3 cells respond robustly to Dpp and exhibit complex transcriptional feedback on BMP signaling components.

BACKGROUND: BMP signaling is involved in myriad metazoan developmental processes, and study of this pathway in Drosophila has contributed greatly to our understanding of its molecular and genetic mechanisms. These studies have benefited not only from Drosophila's advanced genetic tools, but from complimentary in vitro culture systems. However, the commonly-used S2 cell line is not intrinsically sensitive to the major BMP ligand Dpp and must therefore be augmented with exogenous pathway components for most experiments. RESULTS: Herein we identify and characterize the responses of Drosophila ML-DmD17-c3 cells, which are sensitive to Dpp stimulation and exhibit characteristic regulation of BMP target genes including Dad and brk. Dpp signaling in ML-DmD17-c3 cells is primarily mediated by the receptors Put and Tkv, with additional contributions from Wit and Sax. Furthermore, we report complex regulatory feedback on core pathway genes in this system. CONCLUSIONS: Native ML-DmD17-c3 cells exhibit robust transcriptional responses to BMP pathway induction. We propose that ML-DmD17-c3 cells are well-suited for future BMP pathway analyses.

Fly LMBR1/LIMR-type protein Lilipod promotes germ-line stem cell self-renewal by enhancing BMP signaling.

Limb development membrane protein-1 (LMBR1)/lipocalin-interacting membrane receptor (LIMR)-type proteins are putative nine-transmembrane receptors that are evolutionarily conserved across metazoans. However, their biological function is unknown. Here, we show that the fly family member Lilipod (Lili) is required for germ-line stem cell (GSC) self-renewal in the Drosophila ovary where it enhances bone morphogenetic protein (BMP) signaling. lili mutant GSCs are lost through differentiation, and display reduced levels of the Dpp transducer pMad and precocious activation of the master differentiation factor bam. Conversely, overexpressed Lili induces supernumerary pMad-positive bamP-GFP-negative GSCs. Interestingly, differentiation of lili mutant GSCs is bam-dependent; however, its effect on pMad is not. Thus, although it promotes stem cell self-renewal by repressing a bam-dependent process, Lilipod enhances transduction of the Dpp signal independently of its suppression of differentiation. In addition, because Lili is still required by a ligand-independent BMP receptor, its function likely occurs between receptor activation and pMad phosphorylation within the signaling cascade. This first, to our knowledge, in vivo characterization of a LMBR1/LIMR-type protein in a genetic model reveals an important role in modulating BMP signaling during the asymmetric division of an adult stem cell population and in other BMP signaling contexts.

Mutational analysis of the T4 gp59 helicase loader reveals its sites for interaction with helicase, single-stranded binding protein, and DNA.

Efficient DNA replication involves coordinated interactions among DNA polymerase, multiple factors, and the DNA. From bacteriophage T4 to eukaryotes, these factors include a helicase to unwind the DNA ahead of the replication fork, a single-stranded binding protein (SSB) to bind to the ssDNA on the lagging strand, and a helicase loader that associates with the fork, helicase, and SSB. The previously reported structure of the helicase loader in the T4 system, gene product (gp)59, has revealed an N-terminal domain, which shares structural homology with the high mobility group (HMG) proteins from eukaryotic organisms. Modeling of this structure with fork DNA has suggested that the HMG-like domain could bind to the duplex DNA ahead of the fork, whereas the C-terminal portion of gp59 would provide the docking sites for helicase (T4 gp41), SSB (T4 gp32), and the ssDNA fork arms. To test this model, we have used random and targeted mutagenesis to generate mutations throughout gp59. We have assayed the ability of the mutant proteins to bind to fork, primed fork, and ssDNAs, to interact with SSB, to stimulate helicase activity, and to function in leading and lagging strand DNA synthesis. Our results provide strong biochemical support for the role of the N-terminal gp59 HMG motif in fork binding and the interaction of the C-terminal portion of gp59 with helicase and SSB. Our results also suggest that processive replication may involve the switching of gp59 between its interactions with helicase and SSB.