Expression of X-linked inhibitor of apoptosis protein in neoplastic thyroid disorder

X-linked inhibitor of apoptosis protein (XIAP) is associated with tumor genesis, growth, progression and metastasis, and acts by blocking caspase-mediated apoptosis. In the present study, we sought to evaluate the expression patterns of XIAP in various neoplastic thyroid disorders and determine the association between XIAP expression and clinicopathologic factors. Expression of XIAP was evaluated with immunohistochemical staining using monoclonal anti-XIAP in 164 specimens of conventional papillary thyroid carcinoma (PTC) and 53 specimens of other malignant or benign thyroid tumors. XIAP positivity was observed in 128 (78%) of the 164 conventional PTC specimens. Positive rates of XIAP expression in follicular variant PTC, follicular, medullary, poorly differentiated, and anaplastic thyroid carcinoma specimens were 20%, 25%, 38%, 67%, and 38%, respectively. Six nodular hyperplasia specimens were negative and 1 of 7 follicular adenomas (8%) was positive for XIAP. Lateral neck lymph node metastases were more frequent in patients negative for XIAP expression (P = 0.01). Immunohistochemical staining for XIAP as a novel molecular marker may thus be helpful in the differential diagnosis of thyroid cancer. Moreover, high XIAP expression in conventional PTC is strongly associated with reduced risk of lateral neck lymph node metastasis.     

Immunohistochemical detection of X-linked inhibitor of apoptosis in head and neck squamous cell carcinoma

The X-linked inhibitor of apoptosis (XIAP) is the most potent member of the IAP group of structurally related caspase inhibitors. Experimental and clinical evidence implicates XIAP in resistance to cancer therapy and in clinical aggressiveness of certain tumors. We examined the expression of XIAP in head and neck squamous cell carcinoma (SCC). Four-micrometer sections from 59 routinely processed specimens of head and neck SCC were subjected to citrate-based antigen retrieval, followed by incubation with monoclonal anti-XIAP antibody (BD Biosciences, San Jose, Calif) and EnVision Plus reagents (Dako, Carpinteria, Calif). Granular cytoplasmic staining was considered positive; the extent and intensity of staining were recorded. Normal squamous epithelium was either nonstaining (n=22), displayed generally weak basal staining (n=9), or moderate basal staining (n=1). Squamous dysplasia or carcinoma in situ was either nonstaining (10 of 18 cases) or displayed generally weak staining (8 of 18 cases). Varying degrees of XIAP positivity were found in 41 (69.5%) of 59 carcinomas. Most of the nonstaining and weakly staining carcinomas were well or moderately differentiated. In contrast, intense and extensive staining was most frequently found in poorly differentiated carcinomas. In keratinized tumor nests, staining was strongest peripherally and became diminished in central keratinized zones. New parameters of tumor aggressiveness are needed for more effective triaging of patients to appropriately aggressive therapies. The present findings suggest that the potent apoptotic inhibitor XIAP may be such a biomarker in head and neck SCCs, of resistance to apoptosis-inducing therapies, and, possibly, of responsiveness to a new class of XIAP-suppressive drugs presently in clinical trials for other malignancies or in preclinical development.     

The association of well-differentiated thyroid carcinoma with insular or anaplastic thyroid carcinoma; evidence for dedifferentiation in tumor progression

The sequence of tumorigenesis in the thyroid is unclear. It has been proposed that anaplastic carcinomas of the thyroid develop by dedifferentiation in pre-existing differentiated carcinomas. We reviewed all anaplastic and insular (poorly differentiated) thyroid carcinomas in a consultation practice of thyroid pathology that included more than 400 thyroid cancers. Sixteen tumors (4%) were classified as anaplastic or insular (poorly differentiated) thyroid carcinomas. We examined these cases to determine whether these carcinomas were associated with well-differentiated neoplasms of follicular cell derivation. Ten patients were women and 6 were men, and ages ranged from 29 to 85 years; 10 patients with anaplastic carcinomas and 2 with insular carcinomas were 56 years or older, whereas 3 of the 6 patients with insular carcinomas were 31 years or younger. Four tumors were composed exclusively of anaplastic carcinoma; all were represented only by incisional biopsies. One insular carcinoma infiltrated and destroyed all underlying thyroid tissue. In the remaining total, subtotal, or hemithyroidectomy specimens, areas of well-differentiated papillary or follicular carcinoma were found. Some differentiated papillary lesions had a wide spectrum of morphologies, including Hurthle cell, tall cell, and columnar cell features. In the literature, simultaneous or previous occurrence of well-differentiated thyroid carcinomas with anaplastic carcinomas is extremely variable, ranging from 7–89% of cases. in experimental animals, serial transplantation of differentiated thyroid tumors has been shown to lead to anaplastic transformation. Our findings suggest that the majority of anaplastic thyroid carcinomas in humans arise from well-differentiated tumors. However, only a very small number of differentiated carcinomas progress to anaplastic lesions; the factors underlying this phenomenon remain to be identified.     

Immunohistochemical detection of antiapoptotic protein X-linked inhibitor of apoptosis in mammary carcinoma

An immunohistochemical survey of X-linked inhibitor of apoptosis (XIAP) expression in mammary carcinoma was performed. XIAP, the most potent of the inhibitor of apoptosis family of caspase inhibitors, has been linked to tumor aggressiveness and therapeutic resistance in several malignancies and is considered an attractive target for cancer drug discovery. Routinely processed sections from 94 ductal carcinomas, 9 lobular carcinomas, and 10 ductal carcinomas with lobular components or features were subjected to citrate-based antigen retrieval, immunostained with anti-XIAP (BD Biosciences, Franklin Lakes, NJ), Envision+ reagents (Dako, Carpinteria, CA), and diaminobenzidine. Positive staining was found in 22.7% of grade 1, 44% of grade 2, and 89.5% of grade 3 ductal carcinomas. Strong staining occurred in no cases of grade 1, 13% of grade 2, and 55.2% of grade 3 ductal carcinomas. XIAP staining increased overall with grade of ductal carcinoma in situ as well. The staining intensity of invasive carcinoma correlated with that of the corresponding ductal carcinoma in situ in 70% of cases. Ductal carcinomas overall showed more staining than lobular carcinomas. XIAP is most strongly and commonly detected in grade 3 ductal carcinoma. The degree of XIAP expression appears frequently to be determined in the preinvasive intraductal phase of tumorigenesis. These findings suggest a possible role of XIAP in the more aggressive clinical behavior of grade 3, compared with lower-grade ductal carcinomas.     

Overexpression of X-linked inhibitor of apoptosis in human hepatocellular carcinoma

The X-linked inhibitor of apoptosis (XIAP) is a member of a novel family of inhibitors of apoptosis. Since suppression of apoptosis is fundamentally important for carcinogenesis and tumor growth, we investigated the expression and function of XIAP in human hepatocellular carcinomas (HCCs). XIAP was expressed constitutively in HCC cell lines. Fourteen out of 20 (70%) HCC tissues demonstrated moderate or strong cytoplasmic staining for XIAP, whereas non-tumor parts showed negative or weak staining for XIAP by immunohistochemistry. In addition, XIAP expression was inversely correlated with apoptosis, but not with proliferation in HCC tissues. These results indicated that XIAP is a principal inhibitor of apoptosis overexpressed in human HCCs and that XIAP may be a potential target for gene therapy of human HCCs.     

Psammomatous calcifications in thyroid oncocytic (Hürthle cell) follicular tumors

Concentric calcifications, also known as psammoma bodies, are a relatively frequent finding in certain types of tumors, particularly papillary thyroid carcinoma (PTC). In the thyroid, they have been assigned a significant role in the diagnosis of PTC and in distinguishing between these tumors and other types of thyroid neoplasms. Concentric calcifications have also less commonly been noted in other processes in the thyroid, such as in tumors characterized by cells containing abundant oxyphilic cytoplasm (i.e., Hürthle cells). We have studied 12 patients with oncocytic thyroid follicular tumors that contained scattered psammomatous calcifications that led to difficulties in diagnosis. The patients were 9 women and 3 men, aged 34 to 63 years. 10 cases corresponded to benign, non-invasive oncocytic tumors and 2 cases were minimally invasive follicular carcinomas of oncocytic (so called Hürthle cell) type. The psammomatous calcifications were randomly scattered throughout the lesions and were present as a focal, incidental finding in 8 cases and were diffuse in 4 cases. They were composed of concentrically laminated deposits of dense basophilic material closely resembling psammoma bodies, often associated with more homogeneous deposits of lightly eosinophilic material without concentric lamination that were interpreted as precipitated thyroglobulin. Seven patients with clinical follow-up, including one with minimally invasive carcinoma, were alive and well between 5 and 12 years after diagnosis. Concentric laminated calcifications may be encountered in oncocytic (Hürthle cell) follicular tumors and should not be interpreted as indicative of PTC in the context of oncocytic neoplasms of the thyroid.     

Expression of p63 in papillary thyroid carcinoma and in Hashimoto's thyroiditis: a pathobiologic link?

p63 proteins are p53 homologs that are postulated to regulate squamous stem cell commitment. An immunohistochemical survey of p63 expression in normal thyroid and in reactive, neoplastic, and inflammatory thyroid disorders was performed. Sections from routinely fixed and processed archival thyroidectomy specimens were pretreated with citric acid, pH 6.0, for antigen retrieval, then incubated overnight with anti-p63 monoclonal antibody 4A4. Slides were stained using a streptavidin-biotin kit and diaminobenzidine as a chromagen, and then were counterstained with hematoxylin. The results showed that p63 expression was negative in normal thyroid tissue, nodular goiters, and oncocytic follicular adenomas. Positivity was rare and weak in follicular adenomas. p63-positive foci were commonly found in Hashimoto's thyroiditis (1 or more foci in 78.8% of cases), but rare in Graves' disease. Twenty-seven of 33 papillary thyroid carcinomas (81.8%) displayed p63-positive foci. Staining was uncommon in follicular carcinomas and rare in medullary carcinomas. One case of insular carcinoma was p63-positive. All squamoid structures were p63-positive; p63-positive structures morphologically consistent with solid cell nests were also identified. Based on the results of this study, we conclude that p63 is commonly expressed in papillary thyroid carcinoma and in Hashimoto's thyroiditis. Given the debated association of papillary thyroid carcinoma with Hashimoto's thyroiditis, it is possible that p63 expression may be a potential pathobiologic link between the two disorders. The finding of p63 in benign squamoid nests supports a possible interrelationship between these structures and both Hashimoto's thyroiditis and papillary carcinoma. The high percentage of papillary carcinomas with p63-positive foci appears to distinguish papillary carcinoma from other neoplasms originating in the thyroid.     

Expression of S100A2 and S100A6 in thyroid carcinomas

AIMS: S100 calcium-binding proteins are known to play multiple roles in carcinoma development. In this study, we focused on two kinds of these proteins, S100A2 and S100A6, and investigated their expression in thyroid neoplasms. METHODS AND RESULTS: We investigated S100A2 and S100A6 expression in 141 thyroid neoplasms by immunohistochemistry. S100A2 was not expressed in normal follicles or follicular tumours, with one exception. Although 89.5% of papillary carcinoma were positive for S100A2, the expression was heterogeneous except in two cases. In anaplastic carcinoma, 78.5% of cases expressed S100A2 diffusely, while the remaining cases were negative. In normal follicles, S100A6 expression was always low, while 8.3% of follicular adenomas and 39.5% of follicular carcinomas showed increased expression. In papillary carcinomas, S100A6 expression was increased in 75% of cases, but in anaplastic carcinomas it was decreased, with only 14.3% showing high expression. CONCLUSIONS: The expression patterns of S100A2 and S100A6 in thyroid neoplasms are unique compared with those of other carcinomas, suggesting that: (i) S100A2 and S100A6 contribute to certain events in papillary carcinoma progression, and (ii) S100A2 expression is one of the biological characteristics of anaplastic carcinoma.     

Cytokeratin 19 and galectin-3 immunohistochemistry in the differential diagnosis of solitary thyroid nodules

AIMS: The immunohistochemical expression of cytokeratin 19 (CK 19) and galectin-3 was evaluated in 69 thyroid lesions to assess their potential as markers in the diagnosis and classification of thyroid malignancy. The following were studied: 26 cases of papillary carcinoma, 12 of follicular carcinoma, 20 follicular adenomas, two medullary carcinomas, one anaplastic carcinoma and eight multinodular goitres. METHODS AND RESULTS: Formalin-fixed paraffin-embedded thyroid tissues were stained immunohistochemically for both CK 19 and galectin-3. CK 19 expression was found in all 26 papillary carcinomas, five of 12 follicular carcinomas, two of two medullary carcinomas and one case of anaplastic carcinoma. Only five of 20 follicular adenomas were positive for CK 19, and this was in a focal distribution. Two of eight multinodular goitres stained focally positive. Galectin-3 expression was found in 22 of 26 papillary carcinomas, 12 of 12 follicular carcinomas and one of two cases of medullary carcinoma. Only two of 20 follicular adenomas were positive. Three of eight multinodular goitres showed focal galectin-3 expression. CONCLUSIONS: Our findings suggest that the immunohistochemical localization of CK 19 and of galectin-3 is a useful adjunct to the histopathological diagnosis of a solitary thyroid lesion. The expression of CK 19 favours a diagnosis of papillary carcinoma in all its variant patterns. Galectin-3 may serve as a marker for the recognition of follicular carcinoma, particularly the minimally invasive form.     

Immunohistochemical expression of galectin-3 in benign and malignant thyroid lesions

CONTEXT: The expression of galectin-3, a human lectin, has been shown to be highly associated with malignant behavior of thyroid lesions. DESIGN: We studied the immunohistochemical expression pattern of galectin-3 in a variety of follicular-derived thyroid lesions (13 benign and 62 malignant), including Hürthle cell and follicular carcinoma, papillary carcinomas and variants, and anaplastic and poorly differentiated carcinomas. RESULTS: Immunoreactivity was strongest in papillary thyroid carcinomas, whereas staining was less intense in Hürthle cell and anaplastic carcinomas, and even weaker in the follicular variant of papillary thyroid carcinoma. Staining was absent or weak in the 3 follicular thyroid carcinomas and was negative in both insular carcinomas. In several tumors, staining was stronger at the advancing invasive edge of the lesion than in the central portion of the tumor. Galectin-3 was also expressed focally and weakly in reactive follicular epithelium and entrapped follicles in chronic lymphocytic thyroiditis. A variety of thyroid lesions showed prominent endogenous, biotin-like activity, which could cause flaws in interpretation if a biotin-detection system were used. CONCLUSION: We conclude that galectin-3 immunostaining, when used in biotin-free detection systems, may be useful as an adjunct to distinguish benign from malignant thyroid lesions.     

TROP‐2 expression in papillary thyroid carcinoma

TROP‐2 is a type I transmembrane glycoprotein which is over‐expressed in various malignancies, and is related to epithelial cell adhesion molecule (EpCAM), also called TROP‐1, gp40, and KSA. In this study, we evaluated TROP‐2 expression in papillary thyroid carcinoma (PTC) and compared it to other thyroid neoplastic and non‐neoplastic lesions. Immunohistochemical (IHC) evaluation for TROP‐2 was performed on 137 thyroid fine needle aspiration (FNA) cell blocks (CB) which included classic PTC (64), follicular variant PTC (FVPTC) (10), anaplastic thyroid carcinoma (AC) (2), medullary carcinoma (MC) (8), follicular neoplasms (FN) (8), Hurthle cell neoplasms (HCN) (9), follicular lesion of uncertain significance (FLUS) (12), and benign thyroid nodule (BTN) (24). IHC for TROP‐2 expression was also performed on 331 BTN and malignant tumor tissue sections in tissue microarray (TMA). Membranous staining in >5% of tumor cells was considered positive. TROP‐2 stained 61 of 64 PTC CB, 7 of 10 FVPTC CB, and 9 of 12 FLUS CB. All other cases were negative for TROP‐2. TROP‐2 showed a sensitivity of 95.31% and specificity of 89% for classic PTC in FNA CB. In TMA samples, TROP‐2 stained 54 of 60 classic PTC cases and hence showed a high sensitivity and specificity. All BTN in CB and TMA were negative. We conclude that TROP‐2 is a highly sensitive and specific IHC marker for identifying classic PTC. TROP‐2 may play an important role in diagnosing classic PTC, especially in equivocal cases. This study also identifies a strong role for TROP‐2 in separating PTC from BTN. Diagn. Cytopathol. 2016;44:26–31. © 2015 Wiley Periodicals, Inc.     

Immunohistochemical detection of the X-linked inhibitor of apoptosis protein (XIAP) in cervical squamous intraepithelial neoplasia and squamous carcinoma

Premalignant and invasive squamous lesions of the uterine cervix were surveyed for the immunohistochemical detectability of the X-linked inhibitor of apoptosis protein (XIAP), believed to be the most potent of a novel group of proteins designated inhibitor of apoptosis proteins (IAPs). IAPs bind and prevent the activation of apoptosis-mediating caspases. Recent cancer biologic studies have implicated IAPs in therapeutic resistance and tumor aggressiveness. XIAP in particular is considered a highly promising target for drug discovery. Forty-four formalin-fixed and paraffin-embedded archival tissue sections were deparaffinized; subjected to citrate-based antigen retrieval; and immunostained with anti-XIAP monoclonal antibody (clone 48, BD Biosciences, San Jose, Calif) diluted 1:250, 4 degrees C x 72 hours; and developed using EnVision-Plus (Dako, Carpinteria, Calif) and diaminobenzidine as chromagen. Particulate or heterogeneous cytoplasmic staining was considered positive. Normal squamous epithelium was XIAP-positive in 7 of 34 cases (20.6%). Preinvasive intraepithelial lesions were positively stained in 54.5% of cases. Nineteen of 22 invasive squamous carcinomas were positive (86.4%). The intensity and extensiveness of XIAP immunostaining varied among individual cases, but trended upward with loss of tumor differentiation: 8 of 9 cases with strong staining were poorly differentiated carcinomas. The present study suggests the characteristic link between poor tumor differentiation and more aggressive clinical behavior could in some malignancies be based upon the concomitant induction of XIAP. Induction of XIAP appears to occur in a subset of intraepithelial lesions; in others, XIAP is detected only upon progression to invasive carcinoma. Detection of enhanced XIAP expression may also pinpoint those lesions that might benefit from pharmacologic disruption of XIAP's actions.     

Raf-1 Kinase Inhibitory Protein Expression in Thyroid Carcinomas

Raf-1 kinase inhibitory protein (RKIP) has been implicated in several fundamental signal transduction pathways that control cellular growth, differentiation, apoptosis and migration. RKIP is reduced in a variety of human carcinomas, but RKIP expression in thyroid carcinomas has not been analyzed at the protein level. In this study, we examined the immunohistochemical expression of RKIP in various subtypes of thyroid carcinoma. Immunostaining for RKIP was performed on 104 cases of primary thyroid carcinoma (40 papillary, 29 follicular, 11 medullary, 11 poorly differentiated, and 13 anaplastic carcinomas) and 26 cases of nodal metastatic tumor (17 papillary, 4 medullary, and 5 anaplastic carcinomas). Normal thyroid tissue and all cases of follicular, papillary, and medullary carcinomas showed uniform, strong cytoplasmic immunoreactivity for RKIP. With the exception of one case, poorly differentiated carcinomas also revealed strong RKIP expression. In contrast, RKIP expression was completely absent in all anaplastic carcinomas. The transition zone from the differentiated carcinoma component (strong RKIP expression) to the anaplastic carcinoma component (no RKIP expression) demonstrated a completely opposite pattern of RKIP immunoreactivity. This reduction of RKIP expression in anaplastic carcinoma was statistically significant (P?<?0.0001). Additionally, RKIP expression of nodal metastatic tumors corresponded with that of primary tumors: metastatic papillary and medullary carcinomas showed uniform, strong cytoplasmic RKIP immunoreactivity, in contrast, in metastatic anaplastic carcinomas, RKIP expression was completely absent. RKIP expression is significantly reduced in anaplastic thyroid carcinoma as compared to other subtypes of thyroid carcinoma. Further studies are necessary to elucidate the precise mechanism of RKIP action in anaplastic thyroid carcinoma.     

High level of tumour protein p53-induced nuclear protein 1 (TP53INP1) expression in anaplastic carcinoma of the thyroid

AIMS: Tumour protein p53-induced nuclear protein 1 (TP531NP1) is a stress-induced protein and plays a role in cell cycle arrest and p53-mediated apoptosis. In this study, we investigated TP531NP1 expression in human thyroid neoplasms. METHODS: We immunohistochemically investigated TP531NP1 in 197 cases of various thyroid neoplasms. RESULTS: Normal follicles did not express TP531NP1. All 39 (20 minimally invasive and 19 widely invasive) follicular carcinomas and 20 adenomas were negative for or expressed only low levels of TP531NP1 except for one widely invasive follicular carcinoma. Of 100 papillary carcinomas, only four (4%) expressed high levels of TP531NP1, and the remaining 96 (96%) were classified into the low group. There were no significant relationships between TP531NP1 expression and clinicopathological features of papillary carcinoma. However, 36 of the 38 (94.7%) anaplastic carcinomas expressed high levels of TP531NP1 and the incidence was significantly higher (p<0.0001) than that in other neoplasms. CONCLUSIONS: These findings suggest that TP531NP1 plays a significant role in the progression of anaplastic carcinoma or contributes to anaplastic transformation from papillary or follicular carcinoma, which is in sharp contrast to findings in previous in vitro and in vivo studies.     

Epithelial markers in thyroid carcinoma: an immunoperoxidase study

Ten cases each of papillary, follicular, anaplastic and medullary carcinoma of the thyroid were stained for thyroglobulin, calcitonin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and cytokeratin (CAM 5.2). Monoclonal or affinity purified polyclonal antibodies, and an indirect immunoperoxidase technique were used. All the papillary and follicular tumours, 5/10 anaplastic and 3/10 medullary carcinomas contained thyroglobulin. Only the 10 medullary carcinomas stained positively for calcitonin. Three out of 10 papillary, 1/10 follicular, 0/10 anaplastic and 10/10 medullary carcinomas were positive for CEA. Nine out of ten papillary, 7/10 follicular, 2/10 anaplastic and 3/10 medullary carcinomas were positive for EMA. Ten out of 10 papillary, 10/10 follicular, 5/10 anaplastic and 10/10 medullary carcinomas were positive for cytokeratin. The presence of calcitonin and CEA is of value in the diagnosis of medullary carcinoma, and enable its distinction from anaplastic thyroid carcinoma. Thyroglobulin is a useful marker in thyroid carcinomas.     

Immunoreactivity of p53, Ki-67, and Bcl-2 in oncocytic adenomas and carcinomas of the thyroid gland.

To analyze relevant factors of neoplastic transformation in oncocytic neoplasms of the thyroid, expression of p53, Ki-67, and bcl-2 has been studied in oncocytic carcinomas (n = 17) and compared with results obtained in oncocytic adenomas (n = 20). P53 protein accumulation was found immunohistochemically in 75% of the oncocytic adenomas (15 of 20) and 88% of the oncocytic carcinomas (15 of 17). Eight of 17 of the carcinomas (47%), but only 3 of the 20 adenomas (15%), showed nuclear p53 accumulation in more than 10% of the cells, mostly in a focal pattern. Ki-67 expression also differed significantly between adenomas and carcinomas. The median of Ki-67-positive cells was 12/10 high-power fields (HPF) for adenomas and 76/10 HPF for carcinomas (P < .001). Furthermore, metastatic carcinomas had a significantly higher Ki-67 positivity than nonmetastasized carcinomas (164/10 HPF v 42/10 HPF, P < .05). Bcl-2 immunohistochemistry showed a constantly positive reaction in normal thyroid tissue. In contrast, bcl-2 protein was not detected in most of the adenomas (70%) and carcinomas (76%). In conclusion, p53 protein and Ki-67 is more prevalent in oncocytic carcinomas than in oncocytic adenomas of the thyroid, indicating that these factors may be involved in the progression of oncocytic neoplasms in the thyroid. In contrast, loss of bcl-2 appears to be an early event in the formation of oncocytic neoplasms of the thyroid. Its importance for malignant transformation is, however, unclear.     

Loss of p53 promotes anaplasia and local invasion in ret/PTC1-induced thyroid carcinomas

Papillary thyroid carcinomas in humans are associated with the ret/PTC oncogene and, following loss of p53 function, may progress to anaplastic carcinomas. Mice with thyroid-targeted expression of ret/PTC1 developed papillary thyroid carcinomas that were minimally invasive and did not metastasize. These mice were crossed with p53-/- mice to investigate whether loss of p53 would promote anaplasia and metastasis of ret/PTC1-induced thyroid tumors. The majority of p53-/- mice died or were euthanized by 17 weeks of age due to the development of thymic lymphomas, soft tissue sarcomas, and testicular teratomas. All ret/PTC1 mice developed thyroid carcinomas, but tumors in p53-/- mice were more anaplastic, larger in diameter, more invasive, and had a higher mitotic index than tumors in p53+/+ and p53+/- mice. Thyroid tumors did not metastasize in any of the experimental p53+/+ and p53+/- mice 相似文献   

Possible Relation of p53 and mdm-2 Oncoprotein Expression in Thyroid Carcinoma: A Molecular-Pathological and Immunohistochemical Study on Paraffin-Embedded Tissue

Routinely processed tissues from a series of benign and malignant thyroid lesions were immunohistochemically investigated with antibodies against p53 and mdm-2. p53 was immunolocalized in <10% of nuclei in 2/80 nodular goiters, 2/60 follicular adenomas, 26/68 follicular carcinomas, 7/40 papillary carcinomas, 3/10 “insular” carcinomas, and 10/31 anaplastic carcinomas. More than 10% positively stained nuclei were found in 2 widely invasive follicular, 2 insular, and 15 anaplastic carcinomas. All p53-positive cases showed a concomitant immunohistochemical mdm-2 expression; an immunohistochemical colocalization on serial section was demonstrated in 12 anaplastic carcinomas. Screening by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis of these 12 cases revealed no relevant mutations in the coding regions of exons 2–11 of the p53 gene. Additionally, 1 follicular adenoma, 6 follicular carcinomas (4 minimally and 2 widely invasive), 1 papillary, and 2 poorly differentiated insular carcinomas were mdm-2 positive without immunohistochemically detectable p53 expression. These results provide evidence that wild-type p53 expression in thyroid carcinomas may be associated with mdm-2 induced formation of stable complexes. However, the role of p53 mutations and p53 protein inactivation owing to other factors (e.g., mdm-2) in the progression of thyroid carcinomas is still poorly understood.