Michaele J. Armstrong

MicroRNA Signature Distinguishes the Degree of Aggressiveness of Papillary Thyroid Carcinoma

BackgroundPapillary thyroid carcinoma (PTC) has relatively indolent behavior, although some tumors recur and disseminate to distant sites. The aggressive biological behavior of PTC is difficult to predict. MicroRNAs (miRNAs) are dysregulated in various tumors types, and some of them serve as markers of poor prognosis. In this study, we evaluated miRNA expression as a marker of more aggressive behavior in PTC.MethodsmiRNA array was used to identify a subset of differentially expressed miRNAs between aggressive and nonaggressive PTC. These miRNAs were further validated by real-time RT-PCR in a cohort of 17 PTC with local tumor recurrence or distant metastases and 15 PTC with no extrathyroidal dissemination and correlated with BRAF,RAS, and RET/PTC mutations and MET expression.ResultsThe miRNA array identified miR-146b, miR-221, miR-222, miR-155, miR-31 upregulation and miR-1, miR-34b, miR-130b, miR-138 downregulation in aggressive compared with nonaggressive PTC. Significant miRNA deregulation was confirmed in the validation cohort, with upregulation of miR-146b and miR-222 and downregulation of miR-34b and miR-130b seen in aggressive PTC. Among BRAF-positive tumors, miR-146b showed strong association with aggressive PTC. MET was identified as a potential target gene for 2 downregulated miRNAs (miR-34b and miR-1), and significantly higher level of MET expression was observed in aggressive PTC.ConclusionsWe demonstrate that miR-146b, miR-222, miR-34b, miR-130b are differentially expressed in aggressive compared with nonaggressive PTC. Among BRAF-positive tumors, overexpression of miR-146b was associated with aggressive behavior, suggesting that it may further refine the prognostic importance of BRAF.

RAS Mutations in Thyroid FNA Specimens Are Highly Predictive of Predominantly Low-Risk Follicular-Pattern Cancers

INTRODUCTION RAS mutations are common in thyroid tumors and confer a high risk of cancer when detected in fine-needle aspiration (FNA) specimens. Specific characteristics of RAS-positive thyroid cancers are not well described. METHODS From April 2007 to April 2009, 921 consecutive patients undergoing FNA were evaluated prospectively with a panel of molecular markers. Ultrasonographic, cytological, histological, and surgical outcomes were retrospectively assessed. RESULTS Sixty-eight aspirates from 66 patients were positive for RAS mutations including 63 cytologically indeterminate (93%), 3 malignant (4%), and 2 benign (3%) specimens. Cancer was histologically confirmed in 52 of 63 aspirates (83%) including the following: 46 papillary thyroid cancers, 4 follicular thyroid cancers, 1 medullary cancer, and 1 anaplastic cancer. All 46 RAS-positive papillary thyroid cancers, including 1 metastatic cancer, had follicular variant histology papillary thyroid cancer; only 11 tumors demonstrated vascular/capsular invasion and 4 had infiltrative growth. Of 48 patients with differentiated thyroid cancer, lymph node metastasis was uncommon and bilateral cancer was present in 48%. Only 33% of malignant nodules were suspicious by preoperative ultrasonography. At a mean follow-up of 22 months, 31 of 35 differentiated thyroid cancer patients (89%) have no evidence of recurrence, 4 patients (9%) have detectable thyroglobulin, 1 patient has bone metastases, and both patients with medullary and anaplastic cancer have died. CONCLUSION Most RAS-positive thyroid cancers have indeterminate cytology, lack suspicious ultrasound features, and are histologically low-grade follicular variant histology papillary thyroid cancer. Lymph node and distant metastases are uncommon but bilateral disease is frequent. Total thyroidectomy should be considered for initial surgical management of most patients with RAS-positive FNA results. The role of prophylactic lymphadenectomy remains unclear.

IRF-1 expression induces apoptosis and inhibits tumor growth in mouse mammary cancer cells in vitro and in vivo

Interferon regulatory factor-1 (IRF-1) is a nuclear transcription factor that mediates interferon and other cytokine effects and appears to have antitumor activity in vitro and in vivo in cancer cells. We have constructed a recombinant adenoviral vector (Ad-IRF-1) that infects mammary cells with high efficiency and results in high levels of functional IRF-1 protein in transfected cells. Overexpression of IRF-1 in two mouse breast cancer cell lines, C3-L5 and TS/A, resulted in apoptosis in these cell lines as assessed by Annexin V staining. The involvement of caspases was confirmed by significant inhibition of apoptosis by a caspase inhibitor, and by demonstration of caspase-3 activity, cleavage of caspase-3, and PARP cleavage. Interestingly, the growth of nonmalignant breast cell lines C127I and NMuMG did not appear to be inhibited by IRF-1 overexpression. Suppression of growth for breast cancer cell lines in vivo was demonstrated by both preinfection of breast cancer cells ex vivo and by intratumoral injection of Ad-IRF-1 into established tumors in their natural hosts. The mechanism of apoptosis may involve the transcriptional upregulation of bak, caspase-8, and caspase-7 expression. These data support the antitumor potential of IRF-1 and the use of agents that increase IRF-1 in breast cancer.

Ectopic Expression of Interferon Regulatory Factor-1 Promotes Human Breast Cancer Cell Death and Results in Reduced Expression of Survivin

The overexpression of the inhibitor of apoptosis protein, survivin, may provide tumor cells with a distinct survival advantage in situ; hence, therapeutic strategies have been designed to inhibit its expression. In this study, we ectopically expressed the interferon regulatory factor (IRF)-1 protein in the breast carcinoma cell lines MDA-MB-468 and SK-BR-3 using a recombinant adenovirus (Ad-IRF-1). By screening microarray analysis of cDNA from the human breast cancer cell line MDA-MB-468 infected with Ad-IRF-1, we observed a 15-fold down-regulation of the survivin gene when compared with uninfected cells. Consequently, we tested survivin expression in Ad-IRF-1-infected MDA-MB-468 and SK-BR-3 breast cancer cell lines. Immunoblotting analyses supported the contention that ectopic expression of the IRF-1 protein results in down-regulation of survivin protein expression that is independent of p53. In addition, Ad-IRF-1 infection of these human breast cancer cell lines induces the expression of p21. We also report that increased apoptosis is observed in tumor cells infected with Ad-IRF-1 compared with Ad-Ψ5 mock-infected cells and that cell death is further augmented when the IRF-1-infected cells are cultured with Adriamycin. Moreover, in a xenogeneic mouse model of breast carcinoma, in vivo treatment of tumor-bearing mice with intratumoral Ad-IRF-1 injections results in tumor growth inhibition. In resected tumors from mice that had been treated with Ad-IRF-1, tumor cells that express the IRF-1 transgene have a predominant IRF-1-positive, survivin-negative phenotype. Collectively, these observations suggest that therapies designed to enhance IRF-1 expression within tumor cells may represent novel treatment strategies for breast cancer.

A Clinical Algorithm for Fine-needle Aspiration Molecular Testing Effectively Guides the Appropriate Extent of Initial Thyroidectomy

Objective:To test whether a clinical algorithm using routine cytological molecular testing (MT) promotes initial total thyroidectomy (TT) for clinically significant thyroid cancer (sTC) and/or correctly limits surgery to lobectomy when appropriate. Background:Either TT or lobectomy is often needed to diagnose differentiated thyroid cancer. Determining the correct extent of initial thyroidectomy is challenging. Methods:After implementing an algorithm for prospective MT of in-house fine-needle aspiration biopsy specimens, we conducted a single-institution cohort study of all patients (N = 671) with nonmalignant cytology who had thyroidectomy between October 2010 and March 2012, cytological diagnosis using 2008 Bethesda criteria, and 1 or more indications for thyroidectomy by 2009 American Thyroid Association guidelines. sTC was defined by histological differentiated thyroid cancer of 1 cm or more and/or lymph node metastasis. Cohort 2 patients did not have MT or had unevaluable results. In cohort 1, MT for a multigene mutation panel was performed for nonbenign cytology, and positive MT results indicated initial TT. Results:MT guidance was associated with a higher incidence of sTC after TT (P = 0.006) and a lower rate of sTC after lobectomy (P = 0.03). Without MT results, patients with indeterminate (follicular lesion of undetermined significance/follicular or oncocytic neoplasm) cytology who received initial lobectomy were 2.5 times more likely to require 2-stage surgery for histological sTC (P < 0.001). In the 501 patients with non-sTC for whom lobectomy was the appropriate extent of surgery, lobectomy was correctly performed more often with routine preoperative MT (P = 0.001). Conclusions:Fine-needle aspiration biopsy MT for BRAF, RAS, PAX8-PPAR&ggr;, and RET-PTC expedites optimal initial surgery for differentiated thyroid cancer, facilitating succinct definitive management for patients with thyroid nodules.

Interferon regulatory factor-1-induced apoptosis mediated by a ligand-independent fas-associated death domain pathway in breast cancer cells

Interferon (IFN) regulatory factor-1 (IRF-1) is a transcription factor that has apoptotic anti-tumor activity. In breast cancer cell types, IRF-1 is implicated in mediating apoptosis by both novel and established anti-tumor agents, including the anti-estrogens tamoxifen and faslodex. Here we demonstrate that in MDA468 breast cancer cells, apoptosis by IFN-γ is mediated by IRF-1 and IFN-γ, and IRF-1-induced apoptosis is caspase-mediated. IRF-1 induction results in cleavage of caspase-8, -3 and -7, and application of caspase inhibitors attenuate activated cleavage products. IRF-1-induced apoptosis involves caspase-8 since apoptosis is significantly decreased by the caspase-8-specific inhibitor IETD, c-FLIP expression and in caspase-8-deficient cancer cells. Furthermore, we demonstrate that IRF-1-induced apoptosis requires fas-associated death domain (FADD) since dominant-negative FADD expressing cells resist IRF-1-induced apoptosis and activated downstream products. Immunofluorescent studies demonstrate perinuclear colocalization of FADD and caspase-8. Despite the known role of FADD in mediating death-ligand induced apoptosis, neutralizing antibodies against classical death receptors do not inhibit IRF-1 induced apoptosis, and no secreted ligand appears to be involved since MDA468 coincubated with IRF-1 transfected cells do not apoptose. Therefore, we demonstrate that IRF-1 induces a ligand-independent FADD/caspase-8-mediated apoptosis in breast cancer cells.

Tumor genotype determines phenotype and disease-related outcomes in thyroid cancer: a study of 1510 patients.

OBJECTIVES To correlate thyroid cancer genotype with histology and outcomes. BACKGROUND The prognostic significance of molecular signature in thyroid cancer (TC) is undefined but can potentially change surgical management. METHODS We reviewed a consecutive series of 1510 patients who had initial thyroidectomy for TC with routine testing for BRAF, RAS, RET/PTC, and PAX8/PPARG alterations. Histologic metastatic or recurrent TC was tracked for 6 or more months after oncologic thyroidectomy. RESULTS Papillary thyroid cancer (PTC) was diagnosed in 97% of patients and poorly differentiated/anaplastic TC in 1.1%. Genetic alterations were detected in 1039 (70%); the most common mutations were BRAFV600E (644/1039, 62%), and RAS isoforms (323/1039, 31%). BRAFV600E-positive PTC was often conventional or tall cell variant (58%), with frequent extrathyroidal extension (51%) and lymph node metastasis (46%). Conversely, RAS-positive PTC was commonly follicular variant (87%), with infrequent extrathyroidal extension (4.6%) and lymph node metastasis (5.6%). BRAFV600E and RET/PTC-positive PTCs were histologically similar. Analogously, RAS and PAX8/PPARG-positive PTCs were histologically similar. Compared with RAS or PAX8/PPARG-positive TCs, BRAFV600E or RET/PTC-positive TCs were more often associated with stage III/IV disease (40% vs 15%, P < 0.001) and recurrence (10% vs 0.7%, P < 0.001; mean follow-up 33 ± 21 mo). Distant metastasis was highest in patients with RET/PTC-positive TC (10.8%, P = 0.02). CONCLUSIONS In this large study of prospective mutation testing in unselected patients with TC, molecular signature was associated with distinctive phenotypes including cancers, with higher risks of both distant metastasis and early recurrence. Preoperative genotype provides valuable prognostic data to appropriately inform surgery.

Positional Dyspnea and Tracheal Compression as Indications for Goiter Resection

HYPOTHESES Goiter is a surgically reversible cause of positional dyspnea (PD). Substernal tracheal compression (TC) predicts PD relief after thyroidectomy (Tx). DESIGN Retrospective analysis of a prospective structured management algorithm. SETTING Endocrine surgery academic center. METHODS Before Tx, 1081 patients were queried about PD. Those patients with substernal goiter underwent computed tomography, and their degree of TC was estimated as greatest percent reduction of transverse tracheal diameter. For 197 patients with PD, TC, or both, surgical outcomes were examined with a mean follow- up of 12.6 months. After Tx, patients who carried the diagnosis of obstructive sleep apnea were referred for repeat sleep study evaluation. RESULTS Positional dyspnea was reported by 188 of 1081 patients, and after Tx the PD improved or resolved in 82.4%. In the 151 patients with substernal goiter, TC was present on imaging in 97.2%; the mean (range) TC was 34% (5%-90%). Patients with TC had a high likelihood of PD (93.5%). After substernal goiter resection, PD improved in stepwise association with total resected thyroid gland weight. Improvement in PD was strongly predicted by both gland weight of 100 g or more (P.001) and by TC of 35% or more (P.01). After Tx, 59 of 77 snorers (76.6%) reported improvement in snoring, 77.1% of patients with obstructive sleep apnea reported improved PD, and 2 of 3 retested patients with obstructive sleep apnea demonstrated objective improvement in sleep study apnea-hypopnea index. CONCLUSIONS Resection of bulky goiter frequently improves PD, which in substernal goiter is highly associated with TC. Either PD or TC of 35% or more prompt Tx. Goiter should be considered when obstructive sleep apnea is diagnosed.

Suspicious Ultrasound Characteristics Predict BRAFV600E-Positive Papillary Thyroid Carcinoma

BACKGROUND Current American Thyroid Association (ATA) guidelines recommend routine cervical ultrasound (US) in thyroid nodule evaluation. Specific US characteristics can help diagnose papillary thyroid carcinoma (PTC). The aim of this blinded cohort study was to determine whether these specific US characteristics can also reliably detect the more aggressive variants of PTC that are often associated with the BRAF(V600E) mutation. METHODS After Institutional Review Board approval, we identified a cohort of patients from January 2007 to December 2009 with histologic PTC≥1 cm who had cervical US, initial thyroid surgery, and molecular testing for BRAF(V600E) on fine-needle aspiration biopsy or histology. Preoperative US images were evaluated by a single radiologist, who was blinded to BRAF status, for nodule size and the presence or absence of the following suspicious US features: taller-than-wide shape, ill-defined margins, hypoechogenicity, calcifications, noncystic composition, and absent halo. RESULTS BRAF-positivity was associated with most known suspicious US findings, including taller-than-wide shape (47% vs. 7%, p<0.001), ill-defined margins (42% vs. 9%, p<0.001), hypoechogenicity (83% vs. 36%, p<0.001), micro/macrocalcifications (87% vs. 24%, p<0.001), and absent halo (85% vs. 27%, p<0.001) but was not associated with noncystic composition. When ≥3 suspicious US features were present, BRAF-positivity was predicted with a positive predictive value of 82%. The absence of suspicious US features together with negative BRAF testing predicted PTC without extrathyroidal extension or lymph node metastasis (negative predictive value 88%). CONCLUSIONS With routine preoperative cervical US and molecular testing, a trained radiologist or surgeon can improve the preoperative characterization of PTC, potentially impacting risk stratification and initial surgical management.

Interferon Regulatory Factor 1 (IRF-1) induces p21WAF1/CIP1 dependent cell cycle arrest and p21WAF1/CIP1 independent modulation of survivin in cancer cells

We have shown that the ectopic expression of Interferon Regulatory Factor 1 (IRF-1) results in human cancer cell death accompanied by the down-regulation of the Inhibitor of Apoptosis Protein (IAP) survivin and the induction of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1). In this report, we investigated the direct role of p21 in the suppression of survivin. We show that IRF-1 down-regulates cyclin B1, cdc-2, cyclin E, E2F1, Cdk2, Cdk4, and results in p21-mediated G1 cell cycle arrest. Interestingly, while p21 directly mediates G1 cell cycle arrest, IRF-1 or other IRF-1 signaling pathways may directly regulate survivin in human cancer cells.