Christine Wong

A Mutant-p53/Smad Complex Opposes p63 to Empower TGFβ-Induced Metastasis

TGFbeta ligands act as tumor suppressors in early stage tumors but are paradoxically diverted into potent prometastatic factors in advanced cancers. The molecular nature of this switch remains enigmatic. Here, we show that TGFbeta-dependent cell migration, invasion and metastasis are empowered by mutant-p53 and opposed by p63. Mechanistically, TGFbeta acts in concert with oncogenic Ras and mutant-p53 to induce the assembly of a mutant-p53/p63 protein complex in which Smads serve as essential platforms. Within this ternary complex, p63 functions are antagonized. Downstream of p63, we identified two candidate metastasis suppressor genes associated with metastasis risk in a large cohort of breast cancer patients. Thus, two common oncogenic lesions, mutant-p53 and Ras, selected in early neoplasms to promote growth and survival, also prefigure a cellular set-up with particular metastasis proclivity by TGFbeta-dependent inhibition of p63 function.

Kras regulatory elements and exon 4A determine mutation specificity in lung cancer

Kras is the most frequently mutated ras family member in lung carcinomas, whereas Hras mutations are common in tumors from stratified epithelia such as the skin. Using a Hras knock-in mouse model, we demonstrate that specificity for Kras mutations in lung and Hras mutations in skin tumors is determined by local regulatory elements in the target ras genes. Although the Kras 4A isoform is dispensable for mouse development, it is the most important isoform for lung carcinogenesis in vivo and for the inhibitory effect of wild-type (WT) Kras on the mutant allele. Kras 4A expression is detected in a subpopulation of normal lung epithelial cells, but at very low levels in lung tumors, suggesting that it may not be required for tumor progression. The two Kras isoforms undergo different post-translational modifications; therefore, these findings can have implications for the design of therapeutic strategies for inhibiting oncogenic Kras activity in human cancers.

Application of the ABCD2 Score to Identify Cerebrovascular Causes of Dizziness in the Emergency Department

Background and Purpose— Dizziness can herald a cerebrovascular event. The ABCD2 score predicts the risk of stroke after transient ischemic attack partly by distinguishing transient ischemic attack from mimics. We evaluated whether this score would also identify cerebrovascular events among emergency department patients with dizziness. Methods— We retrospectively identified consecutive adults presenting to a university emergency department with a primary symptom of dizziness, vertigo, or imbalance. Two neurologists independently reviewed medical records to determine whether the presenting symptom was caused by a cerebrovascular event (ischemic stroke, transient ischemic attack, or intracranial hemorrhage). ABCD2 scores were then assigned using clinical information from the medical record. The ability of the score to discriminate between patients with cerebrovascular events and those with other diagnoses was quantified using the c statistic. Results— Among 907 dizzy patients (mean age, 59 years; 58% female), 37 (4.1%) had a cerebrovascular cause, the majority of which were ischemic strokes (n=24). The median ABCD2 score was 3 (interquartile range, 3–4). The ABCD2 score predicted ultimate diagnosis of a cerebrovascular event (c statistic, 0.79; 95% CI, 0.73–0.85). Only 5 of 512 (1.0%) patients with a score of ⩽3 had a cerebrovascular event compared to 25 of 369 patients (6.8%) with a score of 4 or 5 and 7 of 26 patients (27.0%) with a score of 6 or 7. Conclusions— The ABCD2 score may provide useful information on dizzy emergency department patients at low-risk for having a cerebrovascular diagnosis and may aid frontline providers in acute management if validated prospectively.

Rate and Predictors of Serious Neurologic Causes of Dizziness in the Emergency Department

OBJECTIVE To describe the rate and predictors of central nervous system (CNS) disease in emergency department (ED) patients with dizziness in the modern era of neuroimaging. PATIENTS AND METHODS We retrospectively reviewed the medical records of all adults presenting between January 1, 2007, and December 31, 2009, to an academic ED for a primary triage complaint of dizziness, vertigo, or imbalance. The final diagnosis for the cause of dizziness was independently assigned by 2 neurologists, with a third neurologist resolving any disagreements. The primary outcome was a composite of ischemic stroke, intracranial hemorrhage, transient ischemic attack, seizure, brain tumor, demyelinating disease, and CNS infection. Univariate and multivariate logistic regression were used to assess the association between clinical variables and serious CNS causes of dizziness. RESULTS Of 907 patients experiencing dizziness (mean age, 59 years; 58% women [n=529]), 49 (5%) had a serious neurologic diagnosis, including 37 cerebrovascular events. Dizziness was often caused by benign conditions, such as peripheral vertigo (294 patients [32%]) or orthostatic hypotension (121 patients [13%]). Age 60 years or older (odds ratio [OR], 5.7; 95% confidence interval [CI], 2.5-11.2), a chief complaint of imbalance (OR, 5.9; 95% CI, 2.3-15.2), and any focal examination abnormality (OR, 5.9; 95% CI, 3.1-11.2) were independently associated with serious neurologic diagnoses, whereas isolated dizziness symptoms were inversely associated (OR, 0.2; 95% CI, 0.0-0.7). CONCLUSION Dizziness in the ED is generally benign, although a substantial fraction of patients harbor serious neurologic disease. Clinical suspicion should be heightened for patients with advanced age, imbalance, or focal deficits.

Inflammation and Hras signaling control epithelial–mesenchymal transition during skin tumor progression

Epithelial-mesenchymal transition (EMT) is thought to be an important, possibly essential, component of the process of tumor dissemination and metastasis. About 20%-30% of Hras mutant mouse skin carcinomas induced by chemical initiation/promotion protocols have undergone EMT. Reduced exposure to TPA-induced chronic inflammation causes a dramatic reduction in classical papillomas and squamous cell carcinomas (SCCs), but the mice still develop highly invasive carcinomas with EMT properties, reduced levels of Hras and Egfr signaling, and frequent Ink4/Arf deletions. Deletion of Hras from the mouse germline also leads to a strong reduction in squamous tumor development, but tumors now acquire activating Kras mutations and exhibit more aggressive metastatic properties. We propose that invasive carcinomas can arise by different genetic and biological routes dependent on exposure to chronic inflammation and possibly from different target cell populations within the skin. Our data have implications for the use of inhibitors of inflammation or of Ras/Egfr pathway signaling for prevention or treatment of invasive cancers.

Accuracy of Neurovascular Fellows' Prognostication of Outcome After Subarachnoid Hemorrhage

Background and Purpose— The purpose of this study was to determine the accuracy and optimal timing of physician prognostication in patients with subarachnoid hemorrhage, a prototypical neurological disease characterized by variable outcomes and frequent disability. Methods— From October 2009 to April 2010, treating neurologists at a tertiary care academic medical center made daily predictions of the modified Rankin Scale at 6 months for consecutive patients with subarachnoid hemorrhage. Actual functional outcomes at 6 months were determined by phone interview and dichotomized into good (modified Rankin Scale 0–2) and poor (modified Rankin Scale 3–6) outcomes. Descriptive statistics were used to assess the accuracy of prognostications. Multiple logistic regression and generalized estimating equations were used to assess changes in prognostication accuracy over time and the relationship between prognostication accuracy and clinical factors. Results— Physicians made 648 prognostications for 66 patients. Overall accuracy ranged from 78% to 88%. Among patients predicted to have a good outcome, 81% (95% CI, 71%–92%) actually had a good outcome, whereas 88% (95% CI, 77%–99%) of patients predicted to do poorly had poor outcomes. No significant trends were seen in prognostication accuracy over time during the hospital course (P=0.72). Increasing age, infection, mechanical ventilation, hydrocephalus, and seizures all significantly worsened physician accuracy. Conclusions— Neurologists were generally but not perfectly accurate in their prognostications of functional outcomes. The accuracy of prognoses did not correlate with the hospital day on which they were made but was affected by clinical factors that can cloud the neurological examination.

Cytology smears as excellent starting material for next-generation sequencing-based molecular testing of patients with adenocarcinoma of the lung

Molecular testing of lung adenocarcinomas (ADCs) is crucial for therapy stratification of patients. Because of the often limited diagnostic material, the authors aimed to explore the suitability of cytology smears for next‐generation sequencing (NGS) and compared the results with concurrent histological specimens or cell blocks.

KPNA2 is overexpressed in human and mouse endometrial cancers and promotes cellular proliferation

Endometrial cancer is the most frequently occurring malignancy of the female genital tract in Western countries. Although in many cases surgically curable, about 30% of the tumours represent an aggressive and untreatable disease. In an attempt to establish a reliable prognostic marker for endometrial carcinomas disregarding their histological diversity, we investigated the expression of KPNA2, a mediator of nucleocytoplasmic transport, and other cell proliferation‐associated proteins and their correlation with cancer progression. We analysed patient tissue microarrays (TMAs) assembled from 527 endometrial cancer tissue specimens and uterus samples from a Trp53 knockout mouse model of endometrial cancer. Our data show that KPNA2 expression was significantly up‐regulated in human endometrial carcinomas and associated with higher tumour grade (p = 0.026), higher FIGO stage (p = 0.027), p53 overexpression (p < 0.001), activation of the PI3K/AKT pathway, and epithelial–mesenchymal transition. Increased nuclear KPNA2 immunoreactivity was identified as a novel predictor of overall survival, independent of well‐established prognostic factors in Cox regression analyses (hazard ratio 1.7, 95% CI 1.13–2.56, p = 0.01). No significant association between KPNA2 expression and endometrial cancer subtype was detected. In the mouse model, KPNA2 showed increased expression levels from precancerous (EmgD, EIC) to far‐advanced invasive lesions. We further investigated the cell proliferation capacity after siRNA‐mediated KPNA2 knockdown in the human endometrial cancer cell line MFE‐296. KPNA2 silencing led to decreased proliferation of the cancer cells, suggesting interplay of the protein with the cell cycle. Taken together, increased expression of KPNA2 is an independent prognostic marker for poor survival. The mechanism of enhanced nucleocytoplasmic transport by KPNA2 overexpression seems a common event in aggressive cancers since we have shown a significant correlation of KPNA2 expression and tumour aggressiveness in a large variety of other solid tumour entities. Introducing KPNA2 immunohistochemistry in routine diagnostics may allow for the identification of patients who need more aggressive treatment regimens. Copyright

The Use of Neuroimaging Studies and Neurological Consultation to Evaluate Dizzy Patients in the Emergency Department

Background and Purpose: Dizziness is a frequent reason for neuroimaging and neurological consultation, but little is known about the utility of either practice. We sought to characterize the patterns and yield of neuroimaging and neurological consultation for dizziness in the emergency department (ED). Methods: We retrospectively identified consecutive adults presenting to an academic ED from 2007 to 2009, with a primary complaint of dizziness, vertigo, or imbalance. Neurologists reviewed medical records to determine clinical characteristics, whether a neuroimaging study (head computed tomography [CT] or brain magnetic resonance imaging [MRI]) or neurology consultation was obtained in the ED, and to identify relevant findings on neuroimaging studies. Two neurologists assigned a final diagnosis for the cause of dizziness. Logistic regression was used to evaluate bivariate and multivariate predictors of neuroimaging and consultation. Results: Of 907 dizzy patients (mean age 59 years; 58% women), 321 (35%) had a neuroimaging study (28% CT, 11% MRI, and 4% both) and 180 (20%) had neurological consultation. Serious neurological disease was ultimately diagnosed in 13% of patients with neuroimaging and 21% of patients with neurological consultation, compared to 5% of the overall cohort. Headache and focal neurological deficits were associated with both neuroimaging and neurological consultation, while age ≥60 years and prior stroke predicted neuroimaging but not consultation, and positional symptoms predicted consultation but not neuroimaging. Conclusion: In a tertiary care ED, neuroimaging and neurological consultation were frequently utilized to evaluate dizzy patients, and their diagnostic yield was substantial.

Lgr6 is a stem cell marker in mouse skin squamous cell carcinoma

The G-protein-coupled receptors LGR4, LGR5 and LGR6 are Wnt signaling mediators, but their functions in squamous cell carcinoma (SCC) are unclear. Using lineage tracing in Lgr5-EGFP-CreERT2/Rosa26-Tomato and Lgr6-EGFP-CreERT2/Rosa26-Tomato reporter mice, we demonstrate that Lgr6, but not Lgr5, acts as an epithelial stem cell marker in SCCs in vivo. We identify, by single-molecule in situ hybridization and cell sorting, rare cells positive for Lgr6 expression in immortalized keratinocytes and show that their frequency increases in advanced SCCs. Lgr6 expression is enriched in cells with stem cell characteristics, and Lgr6 downregulation in vivo causes increased epidermal proliferation with expanded lineage tracing from epidermal stem cells positive for Lgr6 expression. Surprisingly, mice with germline knockout of Lgr6 are predisposed to SCC development, through a mechanism that includes compensatory upregulation of Lgr5. These data provide a model for human patients with germline loss-of-function mutations in Wnt pathway genes, including RSPO1 or LGR4, who show increased susceptibility to squamous tumor development.