Juana García Pedrero

Frequent genetic and biochemical alterations of the PI 3-K/AKT/PTEN pathway in head and neck squamous cell carcinoma.

We investigated the status of the PI 3‐kinase/AKT/PTEN signaling pathway in a series of 117 head and neck squamous cell carcinomas (HNSCC) in a search for molecular alterations in genes/proteins with potential prognostic value. For this purpose, PIK3CA and AKT2 gene amplification was assessed by multiplex and Quantitative Real‐Time PCR. Protein expression of AKT, p‐AKT, p110α and PTEN was determined by Western blot. PTEN allelic loss was evaluated by microsatellite analysis. PTEN‐exon 5 was screened for point mutations by PCR‐SSCP. Homozygous deletions were determined by multiplex PCR. PIK3CA gene was amplified in 43/117 (37%) fresh tumor samples, a frequency that did not differ from that found in archival premalignant tissues: 15/38 (39%); 12/40 (30%) fresh tumors harbored AKT2 gene amplification. AKT was found activated in 6/36 (17%) fresh tumor samples, when compared to their normal tissue counterparts. Of these 6 cases, 1 showed p110α overexpression and 5 displayed PTEN protein downregulation. Neither allelic loss (found in 11/77 informative cases) nor point mutations or homozygous deletions accounted for the reduced PTEN protein expression observed in our tumor series. The histologically normal mucosa of 4 patients displayed some of the molecular alterations analyzed. Dysregulation of the PI 3‐K/AKT/PTEN pathway might contribute to early HNSCC tumorigenesis and might constitute a potential clinical target. Overall, 17/36 (47%) cases showed at least 1 of the molecular alterations studied here, which makes the PI 3‐kinase‐initiated signaling pathway one of the most frequently altered in HNSCC.

Annexin A1 Down-Regulation in Head and Neck Cancer Is Associated with Epithelial Differentiation Status

Annexin A1 (ANXA1) protein expression was evaluated by Western blot in a series of 32 head and neck squamous cell carcinomas (HNSCCs) in a search for molecular alterations that could serve as useful diagnostic/prognostic markers. ANXA1 down-regulation was observed in 24 cases (75%) compared with patient-matched normal epithelium. In relation to clinicopathological variables, ANXA1 down-regulation was significantly associated with advanced T stages (P = 0.029), locoregional lymph node metastases (P = 0.038), advanced disease stage (P = 0.006), hypopharyngeal localization (P = 0.038), and poor histological differentiation (P = 0.005). ANXA1 expression was also analyzed by immunohistochemistry in paraffin-embedded sections from 22 of 32 HNSCCs and 8 premalignant lesions. All dysplastic tissues showed significantly reduced ANXA1 expression compared to a strong positive signal observed in adjacent normal epithelia (except basal and suprabasal cells). A close association was observed between ANXA1 expression and the histological grade in HNSCC. Well-differentiated tumors presented a positive ANXA1 signal in highly keratinized areas whereas moderately and poorly differentiated tumors exhibited very weak or negative staining. Our findings clearly identify ANXA1 as an effective differentiation marker for the histopathological grading of HNSCCs and for the detection of epithelial dysplasia.

Melatonin blocks the activation of estrogen receptor for DNA binding

The present study shows that melatonin prevents, within the first cell cycle, the estradiol‐induced growth of synchronized MCF7 breast cancer cells. By using nuclear extracts of these cells, we first examined the binding of estradiol–estrogen receptor complexes to estrogen‐responsive elements and found that the addition of estradiol to whole cells activates the binding of the estrogen receptor to DNA whereas melatonin blocks this interaction. By contrast, melatonin neither affects the binding of estradiol to its receptor nor the receptor nuclear localization. Moreover, we also show that addition of estradiol to nuclear extracts stimulates the binding of estrogen receptor to DNA, but this activation is also prevented by melatonin. The inhibitory effect caused by melatonin is saturable at nanomolar concentrations and does not appear to be mediated by RZR nuclear receptors. The effect is also specific, since indol derivatives do not cause significant inhibition. Furthermore, we provide evidence that melatonin does not interact with the estrogen receptor in the absence of estradiol. Together, these results demonstrate that melatonin interferes with the activation of estrogen receptor by estradiol. The effect of melatonin suggests the presence of a receptor that, upon melatonin addition, destabilizes the binding of the estradiol–estrogen receptor complex to the estrogen responsive element.—Rato, A. G., Pedrero, J. G., Martínez, M. A., del Rio, B., Lazo, P. S., Ramos, S. Melatonin blocks the activation of estrogen receptor for DNA binding. FASEB J. 13, 857–868 (1999)

Annexin A2 localizes to the basal epithelial layer and is down-regulated in dysplasia and head and neck squamous cell carcinoma☆

Annexin A2 is a highly expressed gene with important roles in cell membrane physiology and is frequently dysregulated in cancer. The objective of this study was to determine the pattern of expression and prognostic significance of annexin A2 protein in head and neck squamous cell carcinoma. We assessed both quantitative changes and qualitative distribution of annexin A2 mRNA and protein expression in normal and diseased tissues by immunohistochemistry, immunofluorescence and in situ hybridization. Annexin A2 expression was confined to the basal and suprabasal cells of normal epithelium and the protein cellular location was consistently observed at the cell membrane. Expression levels correlated with histopathological grade, showing significant suppression in moderately and poorly differentiated tumours. We conclude that annexin A2 exhibits a characteristic pattern of expression, distinct from other annexins and suggestive of a cell-specific functional role. The marked reduction of annexin A2 in poorly differentiated tumours and dysplastic tissue is expected to result in a loss of function aimed at the coordination of membrane signalling enzyme complexes, actin polymerization and extracellular matrix proteolysis. The phenotypic consequences may become manifest in an alteration of epithelial tissue growth and remodelling with secondary influence on tumour development, progression and metastasis.

Clinical significance of annexin A2 downregulation in oral squamous cell carcinoma.

The purpose of this study was to determine the expression of Annexin A2 (ANXA2) in normal oral epithelium and in oral carcinomas to correlate these findings with prognostically relevant variables.

Alteraciones moleculares en las metástasis ganglionares y sus tumores primarios en los carcinomas epidermoides de laringe

Introduccion y objetivos Presentar alteraciones moleculares sucesivas determina la progresion tumoral. Durante esta progresion, el desarrollo de metastasis ganglionares es uno de los determinantes mas importantes del pronostico de los carcinomas de laringe. En este estudio se analizara si en estos carcinomas las alteraciones moleculares en las metastasis ganglionares difieren de las de su correspondiente tumor primario. Material y metodo Se estudian muestras apareadas de tumor y metastasis ganglionares de 51 pacientes con carcinoma epidermoide supraglotico. Se determina, mediante inmunohistoquimica, la expresion de las proteinas p53, E-cadherina, anexina A2, FAK, y HIF-1α, y ademas la actividad apoptotica (mediante la expresion de caspasa-3 activada) y el grado de vascularizacion (identificando los vasos por la expresion del antigeno CD34). Resultados Se aprecio una marcada correlacion en la expression de las proteinas estudiadas en las metastasis y su correspondiente tumor primario, con la excepcion de la expression de HIF-1α y el grado de vascularizacion tumoral. Conclusiones La mayoria de las alteraciones moleculares en las metastasis ganglionares ya estan presentes en el tumor primario, lo que indica que estas alteraciones suceden de forma temprana en la carcinogenesis.

Molecular alterations in nodal metastases and its primary tumors in squamous cell carcinomas of the larynx

INTRODUCTION AND OBJECTIVES The successive acquisition of molecular alterations determines tumour progression. During this progression, the development of nodal metastases is one of the most important prognostic factors in laryngeal squamous cell carcinomas. The aim of this study is to analyze if, in these carcinomas, the molecular alterations in the nodal metastases are different from those present in the primary tumour. MATERIAL AND METHOD Paired samples of primary tumour and nodal metastases from 51 patients with squamous cell carcinoma of the supraglottic larynx were studied. Using immunohistochemistry, we analyzed the expression of p53, E-cadherin, FAK, annexin A2 and HIF-1a proteins. In addition, the apoptotic index (measuring activated caspase-3) and the degree of vascularization (identified by CD34 antigen expression) were also studied. RESULTS A close correlation in the expression of the proteins studied was observed in the nodal metastases and the corresponding primary tumour, with the exception of HIF-1a expression and the degree of vascularization. CONCLUSIONS Most of the molecular alterations in the nodal metastases are already present in the primary tumour, suggesting that these alterations are early events in carcinogenesis.