BAP1 Tumor Predisposition Syndrome Presenting as a Recurrent Ovarian Sex Cord-Stromal Tumor.

The BRCA1-associated protein 1 ( BAP1 ) gene encodes a tumor suppressor that functions as a ubiquitin hydrolase involved in DNA damage repair. BAP1 germline mutations are associated with increased risk of multiple solid malignancies, including mesothelioma, uveal melanoma, renal cell carcinoma, and high-grade rhabdoid meningiomas. Here, we describe the case of a 52-yr-old woman who experienced multiple abdominal recurrences of an ovarian sex cord-stromal tumor that was originally diagnosed at age 25 and who was found to have a germline mutation in BAP1 and a family history consistent with BAP1 tumor predisposition syndrome. Recurrence of the sex cord-stromal tumor demonstrated loss of BAP1 expression by immunohistochemistry. Although ovarian sex cord-stromal tumors have been described in mouse models of BAP1 tumor predisposition syndrome, this relationship has not been previously described in humans and warrants further investigation. The case presentation, tumor morphology, and immunohistochemical findings have overlapping characteristics with peritoneal mesotheliomas, and this case represents a potential pitfall for surgical pathologists.

Giant Pancreatic Myoepithelial Hamartoma in a Patient With Familial Insulin-Dependent Diabetes Mellitus.

ABSTRACT: Pancreatic myoepithelial hamartoma is a rare, benign solid and cystic lesion of the pancreas. We present the first case of an adult with a giant myoepithelial hamartoma extending throughout the pancreas in a patient with diabetes in 4 immediate family members. The patient is a 46-year-old man presented with recurrent acute pancreatitis. Computed tomographic imaging showed that the head and body of the pancreas were replaced by a solid-cystic mass with focal calcification. Medical history includes insulin-dependent diabetes mellitus (IDDM) diagnosed at age 30. Endoscopic ultrasound-guided fine-needle aspiration showed pancreatic acinar tissue and smooth muscle without evidence of malignancy. Total pancreatectomy was performed because of the diffuse nature of the cystic disease and preexisting IDDM. The histopathologic diagnosis was consistent with myoepithelial hamartoma. In addition, there was a family history of IDDM and hamartomatous cyst resection in the paternal grandmother. We report the first case of diffuse pancreatic myoepithelial hamartoma with near total replacement of the entire pancreatic parenchyma, and the first reported case associated with a family history of heritable IDDM. Improved knowledge of the genetics, development, and malignant potential of such rare diseases is critical to determine appropriate management for patients.

Identification and targeting of a HES1-YAP1-CDKN1C functional interaction in fusion-negative rhabdomyosarcoma.

Rhabdomyosarcoma (RMS), a cancer characterized by features of skeletal muscle, is the most common soft-tissue sarcoma of childhood. With 5-year survival rates among high-risk groups at < 30%, new therapeutics are desperately needed. Previously, using a myoblast-based model of fusion-negative RMS (FN-RMS), we found that expression of the Hippo pathway effector transcriptional coactivator YAP1 (YAP1) permitted senescence bypass and subsequent transformation to malignant cells, mimicking FN-RMS. We also found that YAP1 engages in a positive feedback loop with Notch signaling to promote FN-RMS tumorigenesis. However, we could not identify an immediate downstream impact of this Hippo-Notch relationship. Here, we identify a HES1-YAP1-CDKN1C functional interaction, and show that knockdown of the Notch effector HES1 (Hes family BHLH transcription factor 1) impairs growth of multiple FN-RMS cell lines, with knockdown resulting in decreased YAP1 and increased CDKN1C expression. In silico mining of published proteomic and transcriptomic profiles of human RMS patient-derived xenografts revealed the same pattern of HES1-YAP1-CDKN1C expression. Treatment of FN-RMS cells in vitro with the recently described HES1 small-molecule inhibitor, JI130, limited FN-RMS cell growth. Inhibition of HES1 in vivo via conditional expression of a HES1-directed shRNA or JI130 dosing impaired FN-RMS tumor xenograft growth. Lastly, targeted transcriptomic profiling of FN-RMS xenografts in the context of HES1 suppression identified associations between HES1 and RAS-MAPK signaling. In summary, these in vitro and in vivo preclinical studies support the further investigation of HES1 as a therapeutic target in FN-RMS.

Extended Human Papillomavirus Genotyping to Predict Progression to High-Grade Cervical Precancer: A Prospective Cohort Study in the Southeastern United States.

BACKGROUND: High-risk human papillomavirus (hrHPV) testing is utilized in primary cervical cancer screening, generally along with cytology, to triage abnormalities to colposcopy. Most screening-based hrHPV testing involves pooled detection of any hrHPV or of HPV16/18. Cervical neoplasia progression risks based on extended hrHPV genotyping-particularly non-16/18 hrHPV types-are not well characterized. HPV genotype-specific incidence of high-grade cervical intraepithelial neoplasia or more severe (CIN2+) following an abnormal screening result was examined. METHODS: We assessed a US-based prospective, multiracial, clinical cohort of 343 colposcopy patients with normal histology (n = 226) or CIN1 (n = 117). Baseline cervical samples underwent HPV DNA genotyping, and participants were followed up to 5 years. Genotype-specific CIN2+ incidence rates (IR) were estimated with accelerated failure time models. Five-year CIN2+ risks were estimated nonparametrically for hierarchical hrHPV risk groups (HPV16; else HPV18/45; else HPV31/33/35/52/58; else HPV39/51/56/59/68). RESULTS: At enrollment, median participant age was 30.1 years; most (63%) were hrHPV-positive. Over follow-up, 24 participants progressed to CIN2+ (7.0%). CIN2+ IR among hrHPV-positive participants was 3.4/1,000 person-months. CIN2+ IRs were highest for HPV16 (8.3), HPV33 (7.8), and HPV58 (4.9). Five-year CIN2+ risk was higher for HPV16 (0.34) compared with HPV18/45 (0.12), HPV31/33/35/52/58 (0.12), and HPV39/51/56/59/68 (0.16) (P = 0.05). CONCLUSIONS: Non-16/18 hrHPV types are associated with differential CIN2+ progression rates. HPV16, 33, and 58 exhibited the highest rates over 5 years. HPV risk groups warrant further investigation in diverse US populations. IMPACT: These novel data assessing extended HPV genotyping in a diverse clinical cohort can inform future directions to improve screening practices in the general population.

Communicating Certainty in Pathology Reports.

CONTEXT.­: Pathology reports are the main modality in which results are communicated to other physicians. For various reasons, the diagnosis may be qualified on a spectrum of uncertainty. OBJECTIVE.­: To examine how communication of uncertainty is an unexamined source of possible medical error. No study to our knowledge has examined pathology reports across multiple institutions. This study seeks to identify commonly used phrases of diagnostic uncertainty and their interpreted meanings by surgical pathologists and clinicians. DESIGN.­: Anonymous surveys were completed at 3 major US academic institutions by 18 practicing staff pathologists, 12 pathology residents, 53 staff clinicians, and 50 resident/allied health professional clinicians at 5 standard tumor boards. All participants rated percentage certainty associated with 7 diagnostic terms. Pathologists answered 2 questions related to the ability to clarify a diagnosis using a comment and comfort wording pathology reports. Clinicians answered questions on how often they read a pathology report comment, if they found the comment helpful, and how comfortable they were in reading pathology reports. RESULTS.­: A wide range in percentage certainty was found for each of the 7 diagnostic phrases. Both staff and resident clinicians and residents showed wide variability in interpreting the phrases. Twenty-five of 50 staff clinicians (52%) were very comfortable reading a pathology report, whereas only 4 of 53 resident clinicians (8%) were very comfortable reading a pathology report. Twenty-four of 53 staff clinicians (63%) reported always reading the comment, yet only 20 of 53 (27%) always found the comment helpful. The phrases "diagnostic of" and "consistent with" had the strongest agreement in meaning. The weakest agreement was between "suspicious for" and "compatible with." CONCLUSIONS.­: Efforts to standardize diagnostic terms may improve communication.

Limited Reporting of Histopathologic Details in a Multi-Institutional Academic Cohort of Phyllodes Tumors: Time for Standardization.

BACKGROUND: Phyllodes tumors are rare fibroepithelial neoplasms that are classified by tiered histopathologic features. While there are protocols for the reporting of cancer specimens, no standardized reporting protocol exists for phyllodes. METHODS: We performed an 11-institution contemporary review of phyllodes tumors. Granular histopathologic details were recorded, including the features specifically considered for phyllodes grade classification. RESULTS: Of 550 patients, median tumor size was 3.0 cm, 68.9% (n = 379) of tumors were benign, 19.6% (n = 108) were borderline, and 10.5% (n = 58) were malignant. All cases reported the final tumor size and grade classification. Complete pathologic reporting of all histopathologic features was present in 15.3% (n = 84) of cases, while an additional 35.6% (n = 196) were missing only one or two features in the report. Individual details regarding the degree of stromal cellularity was not reported in 53.5% (n = 294) of cases, degree of stromal atypia in 58.0% (n = 319) of cases, presence of stromal overgrowth in 56.2% (n = 309) of cases, stromal cell mitoses in 37.5% (n = 206) of cases, and tumor border in 54.2% (n = 298) of cases. The final margin status (negative vs. positive) was omitted in only 0.9% of cases, and the final negative margin width was specifically reported in 73.8% of cases. Reporting of details was similar across all sites. CONCLUSION: In this academic cohort of phyllodes tumors, one or more histopathologic features were frequently omitted from the pathology report. While all features were considered by the pathologist for grading, this limited reporting reflects a lack of reporting consensus. We recommend that standardized reporting in the form of a synoptic-style cancer protocol be implemented for phyllodes tumors, similar to other rare tumors.

Endometrial Adenocarcinomas With No Specific Molecular Profile: Morphologic Features and Molecular Alterations of "Copy-number Low" Tumors.

The study evaluated morphologic patterns, mutational profiles, and ß-catenin immunohistochemistry (IHC) in copy-number low (CNL) endometrial adenocarcinomas (EAs). CNL EAs (n=19) with next-generation or whole genome sequencing results and available tissue for IHC were identified from our institutional database. Clinical data and histologic slides were reviewed. IHC for ß-catenin was performed and correlated with mutation status. Images of digital slides of CNL EAs from The Cancer Genome Atlas (TCGA) database (n=90) were blindly reviewed by 4 pathologists, and morphology was correlated with mutation status. Categorical variables were analyzed using the Fisher exact test, and agreement was assessed using Fleiss κ. CTNNB1 mutations were present in 63% (12/19) of CNL EAs. ß-catenin nuclear localization was present in 83% of CTNNB1-mutated tumors (10/12) and in 0% (0/7) of CTNNB1-wildtype tumors (sensitivity 0.83, specificity 1.00). Squamous differentiation (SD) was present in 47% (9/19) and was more often observed in CTNNB1-mutated tumors (P=0.02). Mucinous differentiation (MD) was associated with KRAS mutations (P<0.01). Digital image review of TCGA CNL EAs revealed that pathologist agreement on SD was strong (κ=0.82), whereas agreement on MD was weak (κ=0.48). Pathologists identified SD in 22% (20/90), which was significantly associated with the presence of CTNNB1 mutations (P<0.01). CNL EAs demonstrate several morphologies with divergent molecular profiles. SD was significantly associated with CTNNB1 mutations and nuclear localization of ß-catenin in these tumors. Nuclear expression of ß-catenin is a sensitive and specific IHC marker for CTNNB1 mutations in CNL EAs. CNL EAs with KRAS mutations often displayed MD.

More Than Meets the Eye? A Cautionary Tale of Malignant Ectomesenchymoma Treated as Low-risk Orbital Rhabdomyosarcoma.

Malignant ectomesenchymoma (MEM) is a rare multiphenotypic tumor comprised of mesenchymal and neuroectodermal components. MEM is typically diagnosed in infants and younger children and outcomes are variable. The current approach for treating MEM includes targeting the more aggressive mesenchymal component of the tumor, which is often rhabdomyosarcoma. Here, we describe a case of an orbital tumor initially diagnosed and treated as low-risk rhabdomyosarcoma. Local failure prompting a second biopsy revealed neuronal differentiation consistent with a diagnosis of MEM. Intensifying therapy and local radiotherapy led to a long-term cure. This case offers a cautionary tale that while outcomes for MEM were similar to matched rhabdomyosarcoma cohorts when treated on conventional Intergroup Rhabdomyosarcoma Study Group (IRSG) III/IV protocols, treating MEM using a decreased intensity low-risk rhabdomyosarcoma regimen may not be sufficient.

Epithelioid Hyalinizing Sarcoma With MGA-NUTM1 Fusion.

OBJECTIVES: Soft tissue sarcomas are a group of tumors derived from the mesenchymal origin. Historically, they have been classified according to morphologic and immunohistochemical characteristics. The advent of multiplexed next-generation sequencing (NGS), specifically RNA sequencing, has modified the classification of such tumors and others by determining categorization based on molecular alterations. The NUTM1 rearrangement, previously thought to be present only in carcinomas, has recently been reported in poorly differentiated high-grade sarcomas of the soft tissue. We present the first reported case of an epithelioid hyalinizing sarcoma harboring the MGA-NUTM1 fusion in an acral site. METHODS: Histopathologic, immunohistochemical, and molecular testing were performed on resection tissue. RESULTS: Histologically, the tumor showed an epithelioid morphology with prominent background hyalinization. Immunohistochemically, the tumor expressed CD99 and nuclear NUT-1. By NGS the tumor harbors MGA-NUTM1 fusion. CONCLUSIONS: Our findings support more extensive use of NGS for accurate sarcoma classification and identification of potential therapeutic targets. Furthermore, they corroborate the fact that NUTM1-rearranged soft tissue tumors represent a spectrum of heterogeneous morphologic entities. This case also highlights the utility of NUT-1 immunohistochemical study as a possible screening tool for NUTM1-fused sarcomas.

Development and Validation of the Gene Expression Predictor of High-grade Serous Ovarian Carcinoma Molecular SubTYPE (PrOTYPE).

PURPOSE: Gene expression-based molecular subtypes of high-grade serous tubo-ovarian cancer (HGSOC), demonstrated across multiple studies, may provide improved stratification for molecularly targeted trials. However, evaluation of clinical utility has been hindered by nonstandardized methods, which are not applicable in a clinical setting. We sought to generate a clinical grade minimal gene set assay for classification of individual tumor specimens into HGSOC subtypes and confirm previously reported subtype-associated features. EXPERIMENTAL DESIGN: Adopting two independent approaches, we derived and internally validated algorithms for subtype prediction using published gene expression data from 1,650 tumors. We applied resulting models to NanoString data on 3,829 HGSOCs from the Ovarian Tumor Tissue Analysis consortium. We further developed, confirmed, and validated a reduced, minimal gene set predictor, with methods suitable for a single-patient setting. RESULTS: Gene expression data were used to derive the predictor of high-grade serous ovarian carcinoma molecular subtype (PrOTYPE) assay. We established a de facto standard as a consensus of two parallel approaches. PrOTYPE subtypes are significantly associated with age, stage, residual disease, tumor-infiltrating lymphocytes, and outcome. The locked-down clinical grade PrOTYPE test includes a model with 55 genes that predicted gene expression subtype with >95% accuracy that was maintained in all analytic and biological validations. CONCLUSIONS: We validated the PrOTYPE assay following the Institute of Medicine guidelines for the development of omics-based tests. This fully defined and locked-down clinical grade assay will enable trial design with molecular subtype stratification and allow for objective assessment of the predictive value of HGSOC molecular subtypes in precision medicine applications.See related commentary by McMullen et al., p. 5271.

Loss of MST/Hippo Signaling in a Genetically Engineered Mouse Model of Fusion-Positive Rhabdomyosarcoma Accelerates Tumorigenesis.

A hallmark of fusion-positive alveolar rhabdomyosarcoma (aRMS) is the presence of a chromosomal translocation encoding the PAX3-FOXO1 fusion oncogene. Primary cell-based modeling experiments have shown that PAX3-FOXO1 is necessary, but not sufficient for aRMS tumorigenesis, indicating additional molecular alterations are required to initiate and sustain tumor growth. Previously, we showed that PAX3-FOXO1-positive aRMS is promoted by dysregulated Hippo pathway signaling, as demonstrated by increased YAP1 expression and decreased MST activity. We hypothesized that ablating MST/Hippo signaling in a genetically engineered mouse model (GEMM) of aRMS would accelerate tumorigenesis. To this end, MST1/2-floxed (Stk3F/F;Stk4F/F ) mice were crossed with a previously established aRMS GEMM driven by conditional expression of Pax3:Foxo1 from the endogenous Pax3 locus and conditional loss of Cdkn2a in Myf6 (myogenic factor 6)-expressing cells. Compared with Pax3PF/PF;Cdkn2aF/F;Myf6ICN/+ controls, Stk3F/F;Stk4F/F;Pax3PF/PF;Cdkn2aF/F;Myf6ICN/+ animals displayed accelerated tumorigenesis (P < 0.0001) and increased tumor penetrance (88% vs. 27%). GEMM tumors were histologically consistent with aRMS. GEMM tumor-derived cell lines showed increased proliferation and invasion and decreased senescence and myogenic differentiation. These data suggest that loss of MST/Hippo signaling acts with Pax3:Foxo1 expression and Cdkn2a loss to promote tumorigenesis. The rapid onset and increased penetrance of tumorigenesis in this model provide a powerful tool for interrogating aRMS biology and screening novel therapeutics.Significance: A novel mouse model sheds light on the critical role of Hippo/MST downregulation in PAX3-FOXO1-positive rhabdomyosarcoma tumorigenesis. Cancer Res; 78(19); 5513-20. ©2018 AACR.

Concordant, non-atypical breast papillomas do not require surgical excision: A 10-year multi-institution study and review of the literature.

PURPOSE: Non-atypical papillomas (NAPs) diagnosed on core needle biopsy (CNB) frequently undergo surgical excision due to highly variable upstaging rates. The purpose of this study is to document our dual-institution upgrade rates of NAPs diagnosed on core needle biopsy and review the upgrade rates reported in the literature. MATERIALS AND METHODS: Following IRB approval, CNB results from Duke University (7/1/2004-6/30/2014) and the University of North Carolina Chapel Hill (1/1/04-6/30/2013) were reviewed to identify non-atypical papillomas. All cases with surgical excision or 2 years of imaging follow up were included. In addition, a literature review identified 60 published studies on upgrades of NAPs diagnosed at CNB. Cases in our cohort and the published literature were reviewed for confounding factors: [1] missing radiologic-pathologic concordance and/or discordance, [2] papillomas included with high-risk lesions, [3] high risk lesions counted as upgrades, [4] review by a nonspecialized breast pathologist, and [5] cancer incidentally detected. RESULTS: Of the 388 CNBs in our dual-institution cohort, 136 (35%) patients underwent surgical excision and 252 (65%) patients had imaging follow up. After controlling for confounders, no cancers (0/388) were found at surgical excision or during follow up imaging. The literature review upstaging rate was 4.0% (166/4157) but 1.8% (4/227) after excluding studies with confounders. The combined upstaging rate from the literature and this study was 0.6% (4/615). CONCLUSION: The upstaging rate for CNB diagnosed NAPs was 0% in our cohort and 0.6% overall after adjusting for confounders. This low rate does not warrant reflexive surgical excision and diagnostic imaging follow up should be discretionary.

The Transcriptional Coactivator TAZ Is a Potent Mediator of Alveolar Rhabdomyosarcoma Tumorigenesis.

Purpose: Alveolar rhabdomyosarcoma (aRMS) is a childhood soft tissue sarcoma driven by the signature PAX3-FOXO1 (P3F) fusion gene. Five-year survival for aRMS is <50%, with no improvement in over 4 decades. Although the transcriptional coactivator TAZ is oncogenic in carcinomas, the role of TAZ in sarcomas is poorly understood. The aim of this study was to investigate the role of TAZ in P3F-aRMS tumorigenesis.Experimental Design: After determining from publicly available datasets that TAZ is upregulated in human aRMS transcriptomes, we evaluated whether TAZ is also upregulated in our myoblast-based model of P3F-initiated tumorigenesis, and performed IHC staining of 63 human aRMS samples from tissue microarrays. Using constitutive and inducible RNAi, we examined the impact of TAZ loss of function on aRMS oncogenic phenotypes in vitro and tumorigenesis in vivo Finally, we performed pharmacologic studies in aRMS cell lines using porphyrin compounds, which interfere with TAZ-TEAD transcriptional activity.Results: TAZ is upregulated in our P3F-initiated aRMS model, and aRMS cells and tumors have high nuclear TAZ expression. In vitro, TAZ suppression inhibits aRMS cell proliferation, induces apoptosis, supports myogenic differentiation, and reduces aRMS cell stemness. TAZ-deficient aRMS cells are enriched in G2-M phase of the cell cycle. In vivo, TAZ suppression attenuates aRMS xenograft tumor growth. Preclinical studies show decreased aRMS xenograft tumor growth with porphyrin compounds alone and in combination with vincristine.Conclusions: TAZ is oncogenic in aRMS sarcomagenesis. While P3F is currently not therapeutically tractable, targeting TAZ could be a promising novel approach in aRMS. Clin Cancer Res; 24(11); 2616-30. ©2018 AACR.

DNA methylation of imprinted gene control regions in the regression of low-grade cervical lesions.

The role of host epigenetic mechanisms in the natural history of low-grade cervical intraepithelial neoplasia (CIN1) is not well characterized. We explored differential methylation of imprinted gene regulatory regions as predictors of the risk of CIN1 regression. A total of 164 patients with CIN1 were recruited from 10 Duke University clinics for the CIN Cohort Study. Participants had colposcopies at enrollment and up to five follow-up visits over 3 years. DNA was extracted from exfoliated cervical cells for methylation quantitation at CpG (cytosine-phosphate-guanine) sites and human papillomavirus (HPV) genotyping. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression to quantify the effect of methylation on CIN1 regression over two consecutive visits, compared to non-regression (persistent CIN1; progression to CIN2+; or CIN1 regression at a single time-point), adjusting for age, race, high-risk HPV (hrHPV), parity, oral contraceptive and smoking status. Median participant age was 26.6 years (range: 21.0-64.4 years), 39% were African-American, and 11% were current smokers. Most participants were hrHPV-positive at enrollment (80.5%). Over one-third of cases regressed (n = 53, 35.1%). Median time-to-regression was 12.6 months (range: 4.5-24.0 months). Probability of CIN1 regression was negatively correlated with methylation at IGF2AS CpG 5 (HR = 0.41; 95% CI = 0.23-0.77) and PEG10 DMR (HR = 0.80; 95% CI = 0.65-0.98). Altered methylation of imprinted IGF2AS and PEG10 DMRs may play a role in the natural history of CIN1. If confirmed in larger studies, further research on imprinted gene DMR methylation is warranted to determine its efficacy as a biomarker for cervical cancer screening.

A Therapeutic Antibody for Cancer, Derived from Single Human B Cells.

Some patients with cancer never develop metastasis, and their host response might provide cues for innovative treatment strategies. We previously reported an association between autoantibodies against complement factor H (CFH) and early-stage lung cancer. CFH prevents complement-mediated cytotoxicity (CDC) by inhibiting formation of cell-lytic membrane attack complexes on self-surfaces. In an effort to translate these findings into a biologic therapy for cancer, we isolated and expressed DNA sequences encoding high-affinity human CFH antibodies directly from single, sorted B cells obtained from patients with the antibody. The co-crystal structure of a CFH antibody-target complex shows a conformational change in the target relative to the native structure. This recombinant CFH antibody causes complement activation and release of anaphylatoxins, promotes CDC of tumor cell lines, and inhibits tumor growth in vivo. The isolation of anti-tumor antibodies derived from single human B cells represents an alternative paradigm in antibody drug discovery.

The Actin-Binding Protein Drebrin Inhibits Neointimal Hyperplasia.

OBJECTIVE: Vascular smooth muscle cell (SMC) migration is regulated by cytoskeletal remodeling as well as by certain transient receptor potential (TRP) channels, nonselective cation channels that modulate calcium influx. Proper function of multiple subfamily C TRP (TRPC) channels requires the scaffolding protein Homer 1, which associates with the actin-binding protein Drebrin. We found that SMC Drebrin expression is upregulated in atherosclerosis and in response to injury and investigated whether Drebrin inhibits SMC activation, either through regulation of TRP channel function via Homer or through a direct effect on the actin cytoskeleton. APPROACH AND RESULTS: Wild-type (WT) and congenic Dbn(-/+) mice were subjected to wire-mediated carotid endothelial denudation. Subsequent neointimal hyperplasia was 2.4±0.3-fold greater in Dbn(-/+) than in WT mice. Levels of globular actin were equivalent in Dbn(-/+) and WT SMCs, but there was a 2.4±0.5-fold decrease in filamentous actin in Dbn(-/+) SMCs compared with WT. Filamentous actin was restored to WT levels in Dbn(-/+) SMCs by adenoviral-mediated rescue expression of Drebrin. Compared with WT SMCs, Dbn(-/+) SMCs exhibited increased TRP channel activity in response to platelet-derived growth factor, increased migration assessed in Boyden chambers, and increased proliferation. Enhanced TRP channel activity and migration in Dbn(-/+) SMCs were normalized to WT levels by rescue expression of not only WT Drebrin but also a mutant Drebrin isoform that binds actin but fails to bind Homer. CONCLUSIONS: Drebrin reduces SMC activation through its interaction with the actin cytoskeleton but independently of its interaction with Homer scaffolds.

Role of the YAP Oncoprotein in Priming Ras-Driven Rhabdomyosarcoma.

Rhabdomyosarcoma (RMS), a cancer characterized by features of skeletal muscle histogenesis, is the most common soft tissue sarcoma of childhood and adolescence. Survival for high-risk groups is less than 30% at 5 years. RMS also occurs during adulthood, with a lower incidence but higher mortality. Recently, mutational profiling has revealed a correlation between activating Ras mutations in the embryonal (eRMS) and pleomorphic (pRMS) histologic variants of RMS, and a poorer outcome for those patients. Independently, the YAP transcriptional coactivator, an oncoprotein kept in check by the Hippo tumor suppressor pathway, is upregulated in eRMS. Here we show that YAP promotes cell proliferation and antagonizes apoptosis and myogenic differentiation of human RMS cells bearing oncogenic Ras mutations in cell culture studies in vitro and in murine xenografts in vivo. Pharmacologic inhibition of YAP by the benzoporphyrin derivative verteporfin decreased cell proliferation and tumor growth in vivo. To interrogate the temporal contribution of YAP in eRMS tumorigenesis, we used a primary human cell-based genetic model of Ras-driven RMS. Constitutively active YAP functioned as an early genetic lesion, permitting bypass of senescence and priming myoblasts to tolerate subsequent expression of hTERT and oncogenic Ras, which were necessary and sufficient to generate murine xenograft tumors mimicking RMS in vivo. This work provides evidence for cooperation between YAP and oncogenic Ras in RMS tumorigenesis, laying the foundation for preclinical co-targeting of these pathways.

Evaluation of hybrid algorithm for analysis of scattered light using ex vivo nuclear morphology measurements of cervical epithelium.

We evaluate a new hybrid algorithm for determining nuclear morphology using angle-resolved low coherence interferometry (a/LCI) measurements in ex vivo cervical tissue. The algorithm combines Mie theory based and continuous wavelet transform inverse light scattering analysis. The hybrid algorithm was validated and compared to traditional Mie theory based analysis using an ex vivo tissue data set. The hybrid algorithm achieved 100% agreement with pathology in distinguishing dysplastic and non-dysplastic biopsy sites in the pilot study. Significantly, the new algorithm performed over four times faster than traditional Mie theory based analysis.

Secreted Frizzled-Related Protein 3 (SFRP3) Is Required for Tumorigenesis of PAX3-FOXO1-Positive Alveolar Rhabdomyosarcoma.

PURPOSE: Rhabdomyosarcoma (RMS) is a soft tissue sarcoma associated with the skeletal muscle lineage. Of the two predominant subtypes, known as embryonal (eRMS) and alveolar (aRMS), aRMS has the poorer prognosis, with a five-year survival rate of <50%. The majority of aRMS tumors express the fusion protein PAX3-FOXO1. As PAX3-FOXO1 has proven chemically intractable, this study aims to identify targetable proteins that are downstream from or cooperate with PAX3-FOXO1 to support tumorigenesis. EXPERIMENTAL DESIGN: Microarray analysis of the transcriptomes of human skeletal muscle myoblasts expressing PAX3-FOXO1 revealed alteration of several Wnt pathway gene members, including secreted frizzled related protein 3 (SFRP3), a secreted Wnt pathway inhibitor. Loss-of-function using shRNAs against SFRP3 was used to interrogate the role of SFRP3 in human aRMS cell lines in vitro and conditional murine xenograft systems in vivo. The combination of SFRP3 genetic suppression and the chemotherapeutic agent vincristine was also examined. RESULTS: In vitro, suppression of SFRP3 inhibited aRMS cell growth, reduced proliferation accompanied by a G1 arrest and induction of p21, and induced apoptosis. In vivo, doxycycline-inducible suppression of SFRP3 reduced aRMS tumor growth and weight by more than three-fold, in addition to increasing myogenic differentiation and ß-catenin signaling. The combination of SFRP3 suppression and vincristine was more effective at reducing aRMS cell growth in vitro than either treatment alone, and ablated tumorigenesis in vivo. CONCLUSIONS: SFRP3 is necessary for the growth of human aRMS cells both in vitro and in vivo and is a promising new target for investigation in aRMS.