Renu K. Virk

Epigenetic Silencing of the Candidate Tumor Suppressor Gene Per1 in Non–Small Cell Lung Cancer

Purpose: Epigenetic events are a critical factor contributing to cancer development. The purpose of this study was to identify tumor suppressor genes silenced by DNA methylation and histone deacetylation in non–small cell lung cancer (NSCLC). Experimental Design: We used microarray analysis to screen for tumor suppressor genes. Results: We identified Per1, a core circadian gene, as a candidate tumor suppressor in lung cancer. Although Per1 levels were high in normal lung, its expression was low in a large panel of NSCLC patient samples and cell lines. Forced expression of Per1 in NSCLC cell lines led to significant growth reduction and loss of clonogenic survival. Recent studies showed that epigenetic regulation, particularly histone H3 acetylation, is essential for circadian function. Using bisulfite sequencing and chromatin immunoprecipitation, we found that DNA hypermethylation and histone H3 acetylation are potential mechanisms for silencing Per1 expression NSCLC. Conclusions: These results support the hypothesis that disruption of circadian rhythms plays an important role in lung tumorigenesis. Moreover, our findings suggest a novel link between circadian epigenetic regulation and cancer development.

BRAFV600E mutation in papillary thyroid microcarcinoma: a genotype-phenotype correlation.

BRAFV600E mutation has emerged as a marker of aggressive behavior in papillary thyroid carcinoma but its significance in microcarcinoma is not entirely clear. One-hundred and twenty-nine papillary thyroid microcarcinomas were tested for BRAFV600E mutation by single-strand conformation polymorphism, and their clinicopathologic features (age, sex, tumor size, multifocality, nodal metastases, histologic subtype, tumor cell morphology, architecture, tumor-associated stromal reaction, tumor interface to non-neoplastic thyroid (well circumscribed vs infiltrative), extrathyroidal extension, lymphovascular invasion, intratumoral multinucleated giant cells, and adjacent non-neoplastic thyroid pathology) were examined. Compared with tumors without the mutation (39/129, 30%), the mutated microcarcinomas (90/129, 70%) showed significantly higher prevalence of infiltrative tumor borders (78/90 vs 23/39, P=0.001), tumor-associated stromal desmoplasia/fibrosis and/or sclerosis (80/90 vs 25/39, P=0.002), classic nuclear features of papillary thyroid carcinoma (90/90 vs 35/39, P=0.008) and cystic change (43/90 vs 11/39, P=0.05). BRAFV600E mutation was more frequent in classic (75%), tall cell (91%), and other variants (>70%) than in follicular variant (21%) of papillary thyroid microcarcinoma. Tumors without the mutation were significantly more likely to be solid, well circumscribed, and lacked desmoplasia/fibrosis or sclerosis. However, on multivariate analysis, only the follicular variant of papillary microcarcinoma was significantly associated with the absence of mutation (odds ratio (95% confidence interval): 0.09 (0.01–0.54)). Lymph node metastases (n=24) were more frequent in microcarcinomas with mutation than without (21/24 vs 3/24, P=0.02). All patients with lateral cervical node metastasis (n=9), and all but one tumor with extrathyroidal extension (n=17/18) showed BRAFV600E mutation. No significant differences were noted in age, sex, tumor size, multifocality, lymphovascular invasion, psammoma bodies, stromal calcification, intratumoral multinucleated osteoclastic-type giant cells, and lymphocytic infiltration between the two groups of tumors. BRAFV600E mutation is an early event in thyroid carcinogenesis, and is associated with distinctive morphology and aggressive features even in papillary thyroid microcarcinomas.

Pseudoangiomatous stromal hyperplasia: an overview.

Pseudoangiomatous stromal hyperplasia (PASH) of the breast is a benign, proliferative mesenchymal lesion with possible hormonal etiology. It typically affects women in the reproductive age group. Pseudoangiomatous stromal hyperplasia is frequently an incidental histologic finding in breast biopsies performed for other benign or malignant lesions. Rarely, it can present as a firm, painless breast mass, which has been referred to as nodular or tumorous PASH. Grossly, tumorous PASH is a well-circumscribed, firm, rubbery mass with solid, homogenous, gray-white cut surface. On histologic examination, it is characterized by the presence of open slitlike spaces in dense collagenous stroma. The spaces are lined by a discontinuous layer of flat, spindle-shaped myofibroblasts with bland nuclei. The spindle cells express progesterone receptors and are positive for vimentin, actin, and CD34. The most important differential diagnosis on histopathology is angiosarcoma. Pseudoangiomatous stromal hyperplasia discovered incidentally does not require any additional specific treatment. Tumorous PASH is treated by local surgical excision with clear margins and the prognosis is excellent, with minimal risk of recurrence after adequate surgical excision.

NTRK fusion oncogenes in pediatric papillary thyroid carcinoma in northeast United States

An increase in thyroid cancers, predominantly papillary thyroid carcinoma (PTC), has been recently reported in children.

Papillary thyroid carcinomas with and without BRAF V600E mutations are morphologically distinct.

Finkelstein A, Levy G H, Hui P, Prasad A, Virk R, Chhieng D C, Carling T, Roman S A, Sosa J A, Udelsman R, Theoharis C G & Prasad M L 
(2012) Histopathology 60, 1052–1059

Tall Cell Variant of Papillary Thyroid Microcarcinoma: Clinicopathologic Features with BRAFV600E Mutational Analysis

BACKGROUND The tall cell variant of papillary thyroid carcinoma is an aggressive subtype that generally presents as a large tumor in the advanced stage; however, little is known about the tall cell variant of microcarcinoma (tumors measuring <1 cm). In this study, we compare the tall cell variant of microcarcinoma (microTCV) with classic papillary microcarcinomas to examine the hypothesis that, despite the small size, the microTCV may be more aggressive than the classic papillary microcarcinoma. METHODS We identified 27 microTCV patients and compared their clinicopathologic features and BRAF(V600E) mutational status with classic papillary microcarcinomas matched by age and size. The patients with microTCV included 22 women and 5 men aged 33 to 74 years (median age, 56 years). All patients underwent total thyroidectomy; 20 patients had lymph node dissection. RESULTS Tumor size in microTCV patients ranged from 2 mm to 10 mm (median, 7 mm). Extrathyroidal extension and lymphovascular invasion were seen in 9 (33%) and 4 (15%) tumors, respectively. Thirteen patients (48%) harbored multifocal papillary carcinomas. Metastasis to central compartment lymph nodes was seen in 8 patients and to lateral cervical nodes in 3 patients. Nine of the 25 patients (36%) presented at an advanced stage (stage III/IVA). The BRAF(V600E) mutation was detected in 25 of 27 tumors (92.6%). In contrast, age- and size-matched classic papillary microcarcinomas (n=26) showed no extrathyroidal extension (p=0.002), lymphovascular invasion in 1, central compartment lymph node metastasis in 2, lateral cervical node metastasis in 1, multifocal tumors in 10 (38.5%), the BRAF(V600E) mutation in 20 (76.9%), and it infrequently presented in stage III/IVA (7.7%, p=0.02). CONCLUSIONS The microTCV form is associated with aggressive features at presentation, and it should be differentiated from other papillary thyroid microcarcinomas.

NOTCH1 and SOX10 are Essential for Proliferation and Radiation Resistance of Cancer Stem–Like Cells in Adenoid Cystic Carcinoma

Purpose: Although the existence of cancer stem cells (CSC) in adenoid cystic carcinoma (ACC) has been proposed, lack of assays for their propagation and uncertainty about molecular markers prevented their characterization. Our objective was to isolate CSC from ACC and provide insight into signaling pathways that support their propagation. Experimental Design: To isolate CSC from ACC and characterize them, we used ROCK inhibitor-supplemented cell culture, immunomagnetic cell sorting, and in vitro/in vivo assays for CSC viability and tumorigenicity. Results: We identified in ACC CD133-positive CSC that expressed NOTCH1 and SOX10, formed spheroids, and initiated tumors in nude mice. CD133+ ACC cells produced activated NOTCH1 (N1ICD) and generated CD133− cells that expressed JAG1 as well as neural differentiation factors NR2F1, NR2F2, and p27Kip1. Knockdowns of NOTCH1, SOX10, and their common effector FABP7 had negative effects on each other, inhibited spheroidogenesis, and induced cell death pointing at their essential roles in CSC maintenance. Downstream effects of FABP7 knockdown included suppression of a broad spectrum of genes involved in proliferation, ribosome biogenesis, and metabolism. Among proliferation-linked NOTCH1/FABP7 targets, we identified SKP2 and its substrate p27Kip1. A γ-secretase inhibitor, DAPT, selectively depleted CD133+ cells, suppressed N1ICD and SKP2, induced p27Kip1, inhibited ACC growth in vivo, and sensitized CD133+ cells to radiation. Conclusions: These results establish in the majority of ACC the presence of a previously uncharacterized population of CD133+ cells with neural stem properties, which are driven by SOX10, NOTCH1, and FABP7. Sensitivity of these cells to Notch inhibition and their dependence on SKP2 offer new opportunities for targeted ACC therapies. Clin Cancer Res; 22(8); 2083–95. ©2016 AACR.

Vanishing Thyroid Tumors: A Diagnostic Dilemma After Ultrasonography-Guided Fine-Needle Aspiration

BACKGROUND Fine-needle aspiration (FNA) is the most accurate and cost-effective method for evaluating thyroid nodules. However, FNA-induced secondary changes completely replacing thyroid tumors (vanishing tumors) may create a novel problem. In this study, we highlight the diagnostic and management issues associated with the unintended consequences of ultrasonography (US)-guided FNA. METHODS Fourteen thyroid glands (11 women and 3 men, ages 33-64 years) with vanishing tumors were prospectively identified between 2009 and 2012 upon surgical resection. Cytology and histopathology slides were reviewed, and second opinions were obtained when necessary. RESULTS The cytology of the 14 vanishing tumors was suspicious/positive for papillary thyroid carcinoma (PTC) in 5, indeterminate (atypia of unknown significance) in 5, benign in 2, follicular neoplasm in 1, and nondiagnostic in 1 nodule. Upon thyroidectomy, the vanishing tumors ranged in size from 0.4 to 3.5 cm (median 0.7 cm). Microscopically, the nodules showed cystic degeneration, organizing hemorrhage, granulation tissue, fibrosis, and microcalcifications. In seven tumors, a few residual malignant cells (PTC in five) or residual benign follicles (hemorrhagic cyst in two) at the periphery of the vanishing tumors helped with the final diagnosis. The remaining seven tumors were completely replaced by FNA-induced secondary changes, and had the cytology diagnosis of benign in one, follicular neoplasm in one, and suspicious/positive for PTC in five. Of the latter five, two showed additional separate foci of PTC, while three vanishing tumors (0.5, 1.2, and 1.6 cm) had no residual malignant cells and no additional carcinoma leading to a final diagnosis of negative for malignancy. CONCLUSIONS US-guided FNA may lead to complete obliteration of thyroid nodules, rendering final diagnosis upon thyroidectomy difficult or impossible. In these unusual circumstances, the possibility that the surgical pathology may be nonrepresentative should be considered if the cytologic features on FNA are sufficient by themselves to support a definitive diagnosis of PTC.

Loss of LZAP inactivates p53 and regulates sensitivity of cells to DNA damage in a p53-dependent manner

Chemotherapy and radiation, the two most common cancer therapies, exert their anticancer effects by causing damage to cellular DNA. However, systemic treatment damages DNA not only in cancer, but also in healthy cells, resulting in the progression of serious side effects and limiting efficacy of the treatment. Interestingly, in response to DNA damage, p53 seems to play an opposite role in normal and in the majority of cancer cells—wild-type p53 mediates apoptosis in healthy tissues, attributing to the side effects, whereas mutant p53 often is responsible for acquired cancer resistance to the treatment. Here, we show that leucine zipper-containing ARF-binding protein (LZAP) binds and stabilizes p53. LZAP depletion eliminates p53 protein independently of its mutation status, subsequently protecting wild-type p53 cells from DNA damage-induced cell death, while rendering cells expressing mutant p53 more sensitive to the treatment. In human non-small-cell lung cancer, LZAP levels correlated with p53 levels, suggesting that loss of LZAP may represent a novel mechanism of p53 inactivation in human cancer. Our studies establish LZAP as a p53 regulator and p53-dependent determinative of cell fate in response to DNA damaging treatment.

Five Top Stories in Thyroid Pathology.

CONTEXT Thyroid carcinoma is the most common malignant tumor of endocrine organs, yet it only accounts for approximately 1% of all cancers in the United States with more than 35,000 new cases diagnosed each year and more than 450,000 people living with this disease. While most tumors can be diagnosed without much difficulty, a few tumor types, especially tumors with follicular pattern, sometimes pose a diagnostic challenge. OBJECTIVE To discuss morphologic, immunohistochemical, and molecular features of thyroid tumors. We also explore the clinicopathologic features of papillary microcarcinoma and medullary microcarcinoma and how the latter is related and differentiated from C-cell hyperplasia. Finally with the ever-growing list of organ systems involved in immunoglobulin (Ig) G4-related diseases, we discuss the still not completely explored IgG-4-related thyroid disease. DATA SOURCES Data were obtained from review of the pertinent peer-reviewed literature and institutional experience. CONCLUSIONS Histomorphologic evaluation still remains the gold standard for diagnosis in most cases of thyroid diseases. The application of ancillary studies such as immunohistochemistry and molecular diagnosis, including next-generation sequencing, is becoming more common.