Martina Rossi

Role of Ultrasonographic/Clinical Profile, Cytology, and BRAF V600E Mutation Evaluation in Thyroid Nodule Screening for Malignancy: A Prospective Study

CONTEXT Ultrasound (US)-guided fine-needle aspiration biopsy (FNAB) is the most reliable nonsurgical test for distinguishing benign from malignant thyroid nodules. However, there is no consensus on which nodules should undergo FNAB. AIMS The aims of this study were to evaluate the utility of US-guided FNAB in the diagnostic assessment of nodules with or without clinical/US features suggestive for malignancy and to investigate the additional contribution of BRAF V600E mutation analysis in the detection of differentiated thyroid cancer. DESIGN AND METHODS Thyroid cytoaspirates from 2421 nodules at least 4 mm in diameter were performed in 1856 patients who underwent cytological evaluation and biomolecular analysis. RESULTS Cytology showed high positive predictive value and specificity for the diagnosis of malignant lesions. BRAF V600E mutation was found in 115 samples, 80 of which were also cytologically diagnosed as papillary thyroid cancer. BRAF mutation analysis significantly enhanced the diagnostic value of cytology, increasing FNAB diagnostic sensitivity for malignant nodules by approximately 28%. Micro PTC (63% of diagnosed papillary thyroid carcinoma) showed a high prevalence of multifocality, extrathyroidal extension, and lymph node metastases, underlining the malignant potential of thyroid microcarcinomas. Each investigated US/clinical characteristic of suspected malignancy correlated with the presence of a thyroid cancer in thyroid nodules with diameter of at least 4 mm. CONCLUSIONS These data indicate that nodules of at least 4 mm may underlie a thyroid cancer independently of US/clinical characteristics of suspected malignancy, suggesting the need to perform FNAB. The diagnostic sensitivity for thyroid cancer is significantly increased by BRAF V600E mutation analysis, indicating that the screening for BRAF mutation in FNAB samples has a relevant diagnostic potential.

Growth hormone receptor blockade inhibits growth hormone-induced chemoresistance by restoring cytotoxic-induced apoptosis in breast cancer cells independently of estrogen receptor expression.

CONTEXT GH and IGF-I play a role in breast cancer (BC) development. We previously demonstrated that GH protects the estrogen receptor (ER) positive BC-derived MCF7 cell line toward the cytotoxic effects of doxorubicin (D), independently of IGF-I. This issue may be important in ER negative BC cells that are more aggressive and more likely to develop chemoresistance. AIM OF THE STUDY The aim of this study was to evaluate whether GH may impact chemoresistance phenotype of ER-negative BC-derived MDA-MB-231 cell line and investigate the possible mechanisms implicated in the protective action of GH toward the cytotoxic effects of D in both ER-positive and ER-negative BC-derived cell lines. RESULTS GH protects ER-negative MDA-MB-231 cells from the cytotoxic effects of D and GH receptor antagonist pegvisomant reduces GH-induced DNA synthesis also in these cells. In both MDA-MB-231 and MCF7 cells, GH does not revert D-induced G2/M accumulation but significantly reduces basal and D-induced apoptosis, an effect blocked by pegvisomant. Glutathione S-transferase activity is not implicated in the protective effects of GH, whereas D-induced apoptosis depends on c-Jun N terminal kinase (JNK) activation. GH reduces both basal and D-stimulated JNK transcriptional activity and phosphorylation. CONCLUSIONS In human BC cell lines, GH directly promotes resistance to apoptosis induced by chemotherapeutic drugs independently of ER expression by modulating JNK, further broadening the concept that GH excess may hamper cytotoxic BC treatment. These findings support the hypothesis that blocking GH receptor may be viewed as a potential new therapeutic approach to overcome chemoresistance, especially in ER-negative BC.

Protein Kinase C: A Putative New Target for the Control of Human Medullary Thyroid Carcinoma Cell Proliferation in Vitro

We investigate the role of protein kinase C (PKC) in the control of medullary thyroid carcinoma (MTC) cell proliferation by a PKC inhibitor, Enzastaurin, in human MTC primary cultures and in the TT cell line. We found that PKC inhibition reduces cell proliferation by inducing caspase-mediated apoptosis and blocks the stimulatory effect of IGF-I on calcitonin secretion. Enzastaurin reduces PKCβII (Thr500) phosphorylation, indicating a direct involvement of this isoform as well as the phosphorylated levels of Akt (Ser 473) and glycogen synthase kinase (Ser9), PKC pathway downstream targets and pharmacodynamic markers for PKC inhibition. PKCβII and PKCδ enzyme isoforms expression and localization were investigated. These data indicate that in vitro PKC is involved in the control of human MTC proliferation and survival by modulating apoptosis, with a mechanism that implicates PKCβII inhibition and translocation in different subcellular compartments. Targeting PKC may represent a useful therapeutic approach for controlling MTC proliferation.

Identification of a c-myc oncogene lacking the exon 1 in the normal cells of a patient carrying a thyroid carcinoma

In this paper we describe an alteration of the c‐myc oncogene present in the white blood cells and normal as well as neoplastic thyroid cells of a subject carrying a thyroid carcinoma. Restriction enzyme mapping and hybridization to human c‐myc probes specific for different regions of this gene demonstrate that this subject carries, in addition to the normal one, a c‐myc oncogene lacking the first exon and part of the first intron. The levels of the c‐myc mRNA in thyroid cells of this subject do not show differences with respect to thyroid cells from other subjects. Taken together, these findings indicate that the deletion of the first exon of the c‐myc oncogene, in itself, does not produce overtranscription of this oncogene nor hematopoietic malignancies.

IGF-I Influences Everolimus Activity in Medullary Thyroid Carcinoma

Context Medullary thyroid carcinoma (MTC) is a rare tumor originating from thyroid parafollicular C cells. It has been previously demonstrated that insulin-like growth factor I (IGF-I) protects MTC from the effects of antiproliferative drugs. Everolimus, an mTOR inhibitor, has shown potent antiproliferative effects in a human MTC cell line, TT, and in two human MTC primary cultures. Objective To verify whether IGF-I may influence the effects of everolimus in a group of human MTC primary cultures. Design We collected 18 MTCs that were dispersed in primary cultures, treated without or with 10 nM–1 μM everolimus and/or 50 nM IGF-I. Cell viability was evaluated after 48 h, and calcitonin (CT) secretion was assessed after a 6 h incubation. IGF-I receptor downstream signaling protein expression profile was also investigated. Results Everolimus significantly reduced cell viability in eight MTC [by ~20%; P < 0.01 vs. control; everolimus-responders (E-R) MTCs], while cell viability did not change in 10 MTCs [everolimus-non-responders (E-NR) MTCs]. In E-R MTCs, IGF-I blocked the antiproliferative effects of everolimus that did not affect CT secretion, but blocked the stimulatory effects of IGF-I on this parameter. IGF-I receptor downstream signaling proteins were expressed at higher levels in E-NR MTC as compared to E-R MTCs. Conclusion IGF-I protects a subset of MTC primary cultures from the antiproliferative effects of everolimus and stimulates CT secretion by an mTOR mediated pathway that, in turn, may represent a therapeutic target in the treatment of aggressive MTCs.