TFAP2C increases cell proliferation by downregulating GADD45B and PMAIP1 in non-small cell lung cancer cells.

BACKGROUND: Non-small cell lung cancer (NSCLC) is one of the leading causes of death in the world. NSCLC diagnosed at an early stage can be highly curable with a positive prognosis, but biomarker limitations make it difficult to diagnose lung cancer at an early stage. To identify biomarkers for lung cancer development, we previously focused on the oncogenic roles of transcription factor TFAP2C in lung cancers and revealed the molecular mechanism of several oncogenes in lung tumorigenesis based on TFAP2C-related microarray analysis. RESULTS: In this study, we analyzed microarray data to identify tumor suppressor genes and nine genes downregulated by TFAP2C were screened. Among the nine genes, we focused on growth arrest and DNA-damage-inducible beta (GADD45B) and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1) as representative TFAP2C-regulated tumor suppressor genes. It was observed that overexpressed TFAP2C resulted in inhibition of GADD45B and PMAIP1 expressions at both the mRNA and protein levels in NSCLC cells. In addition, downregulation of GADD45B and PMAIP1 by TFAP2C promoted cell proliferation and cell motility, which are closely associated with NSCLC tumorigenesis. CONCLUSION: This study indicates that GADD45B and PMAIP1 could be promising tumor suppressors for NSCLC and might be useful as prognostic markers for use in NSCLC therapy.

TFAP2C increases cell proliferation by downregulating GADD45B and PMAIP1 in non-small cell lung cancer cells

BACKGROUND: Non-small cell lung cancer (NSCLC) is one of the leading causes of death in the world. NSCLC diagnosed at an early stage can be highly curable with a positive prognosis, but biomarker limitations make it difficult to diagnose lung cancer at an early stage. To identify biomarkers for lung cancer development, we previously focused on the oncogenic roles of transcription factor TFAP2C in lung cancers and revealed the molecular mechanism of several oncogenes in lung tumorigenesis based on TFAP2C-related microarray analysis. RESULTS: In this study, we analyzed microarray data to identify tumor suppressor genes and nine genes downregulated by TFAP2C were screened. Among the nine genes, we focused on growth arrest and DNA-damage-inducible beta (GADD45B) and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1) as representative TFAP2C-regulated tumor suppressor genes. It was observed that overexpressed TFAP2C resulted in inhibition of GADD45B and PMAIP1 expressions at both the mRNA and protein levels in NSCLC cells. In addition, downregulation of GADD45B and PMAIP1 by TFAP2C promoted cell proliferation and cell motility, which are closely associated with NSCLC tumorigenesis. CONCLUSION: This study indicates that GADD45B and PMAIP1 could be promising tumor suppressors for NSCLC and might be useful as prognostic markers for use in NSCLC therapy.

Foreign Bodies in the Ear, Nose and Throat: An Experience in a Tertiary Care Hospital in Central Nepal

Introduction A foreign body (FB) is an object or substance foreign to the location where it is found. FBs in the ear, nose, and throat are a common problem frequently encountered in both children and adults. Objective To analyze FBs in terms of type, site, age, and gender distribution and method of removal. Methods A retrospective study was performed in a tertiary care hospital in the central part of Nepal. The study period was from June 2013 to May 2014. The information was obtained from hospital record books. Results A total of 134 patients had FBs in the ear, nose, or throat; 94 were males and 40 were females. Of the 134 patients, 70 (52.23% ) had FB in the ear, 28 (20.89% ) in the nose, and 36 (26.86% ) in the throat. The FB was animate (living) in 28 (40% ) patients with FB in the ear and 1 (3.5% ) patient with FB in the nose, but the FB was inanimate (nonliving) in any patient with FB in the throat, in 42 (60% ) patients with FB in the ear FB, and in 27 (96.4% ) patients with FB of the nose. The FB was removed with or without local anaesthesia (LA) in 98 (73.13% ) patients, and only 36 patients (26.86% ) required general anaesthesia (GA). The most common age group affected was <10 years. Conclusion FBs in the ear and nose were found more frequently in children, and the throat was the most common site of FB in adults and elderly people. Most of the FBs can be easily removed in emergency room or outpatient department. .

RSUME inhibits VHL and regulates its tumor suppressor function.

Somatic mutations or loss of von Hippel-Lindau (pVHL) happen in the majority of VHL disease tumors, which present a constitutively active Hypoxia Inducible Factor (HIF), essential for tumor growth. Recently described mechanisms for pVHL modulation shed light on the open question of the HIF/pVHL pathway regulation. The aim of the present study was to determine the molecular mechanism by which RSUME stabilizes HIFs, by studying RSUME effect on pVHL function and to determine the role of RSUME on pVHL-related tumor progression. We determined that RSUME sumoylates and physically interacts with pVHL and negatively regulates the assembly of the complex between pVHL, Elongins and Cullins (ECV), inhibiting HIF-1 and 2α ubiquitination and degradation. We found that RSUME is expressed in human VHL tumors (renal clear-cell carcinoma (RCC), pheochromocytoma and hemangioblastoma) and by overexpressing or silencing RSUME in a pVHL-HIF-oxygen-dependent degradation stability reporter assay, we determined that RSUME is necessary for the loss of function of type 2 pVHL mutants. The functional RSUME/pVHL interaction in VHL-related tumor progression was further confirmed using a xenograft assay in nude mice. RCC clones, in which RSUME was knocked down and express either pVHL wt or type 2 mutation, have an impaired tumor growth, as well as HIF-2α, vascular endothelial growth factor A and tumor vascularization diminution. This work shows a novel mechanism for VHL tumor progression and presents a new mechanism and factor for targeting tumor-related pathologies with pVHL/HIF altered function.

Sheep gastrointestinal helminthiasis in the Sertão region of Paraíba State, Northeastern Brazil: prevalence and risk factors / Helmintoses gastrintestinais de ovinos no Sertão do Estado da Paraíba, Nordeste do Brasil: prevalência e fatores de riscos

In this study, we aimed to establish the prevalence and risk factors relating to gastrointestinal helminthiasis, and to characterize the sanitary management practiced among sheep herds in the Sertão region of the state of Paraíba, northeastern Brazil, based on factors that condition the ways of controlling these parasites in these herds. The research was carried out between April and July 2012. We visited 54 farms, where fecal and blood samples were individually collected from 465 animals. On each farm, a questionnaire was applied to gather information on variables relating to potential risk factors. The prevalence of sheep gastrointestinal helminthiasis in the region was 75.9%. At least one animal tested positive for this helminthiasis on 53 (98.1%) of the 54 farms evaluated. The eggs per gram of feces (EPG) analysis showed the following infection burdens: 51.8% with mild infection, 27.1% moderate infection, 9.9% heavy infection and 11.2% fatal infection. Among the sheep farms visited, anthelmintics were used on 81.5% (p <0.05). The most relevant risk factor in this study was the farm area, because it defines the area available for grazing animals. Properties with many animals and little pasture area, which are the most abundant type in the Sertão region of Paraíba, tend to have high prevalence of gastrointestinal helminthiasis, because the animals are more prone to reinfection. The Sertão region of Paraíba presents high prevalence of gastrointestinal helminthiasis among sheep, and the farm area is the most relevant risk factor for the development of these parasites.

Objetivou-se determinar a prevalência e os fatores de risco para as helmintoses gastrintestinais, caracterizando o manejo sanitário sob fatores condicionantes das formas de controle dessas parasitoses em rebanhos de ovinos da região do Sertão da Paraíba. A pesquisa foi desenvolvida no período de abril a julho de 2012. Foram visitadas propriedades, utilizando-se 465 animais, sendo coletadas individualmente amostras de fezes e sangue durante as visitas. Em cada propriedade, foi aplicado questionário para a coleta de informações acerca de variáveis que atuariam como possíveis fatores de risco. Observou-se que a prevalência das helmintoses gastrintestinais de ovinos na região do Sertão da Paraíba foi de 75,9%. Pelo menos um animal foi positivo para essas helmintoses, em 53 (98,1%) das 54 propriedades avaliadas. A análise de OPG (Ovos Por Gramas de Fezes) demonstrou que 51,8% dos animais apresentaram infecção leve, 27,1% infecção moderada, 9,9% infecção pesada e 11,2% infecção fatal. A utilização de anti-helmínticos ocorreu em 81,5% das propriedades (p <0,05). O fator de risco mais relevante neste estudo foi a área da propriedade, porque delimita a área de pastejo do animal. Propriedades com muitos animais e pouca área de pastejo, que são as mais abundantes no Sertão da Paraíba, tendem a apresentar alta prevalência de helmintoses gastrintestinais, pois os animais estão mais propensos à reinfecção. A região do Sertão da Paraíba apresenta uma elevada prevalência de helmintoses gastrintestinais em ovinos, e a área das propriedades é o fator de risco mais relevante para o desenvolvimento dessas parasitoses.

CMTM3 is frequently reduced in clear cell renal cell carcinoma and exhibits tumor suppressor activities.

PURPOSE: CKLF-like MARVEL transmembrane domain containing member 3 (CMTM3) is silenced in many kinds of cancers and inhibits tumor cells growth. We investigated the expression and role of CMTM3 in clear cell renal cell carcinoma (ccRCC). METHODS: The expression of CMTM3 was detected in ccRCC tissue microarray, specimens, and cell lines by immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. After transfected with CMTM3 plasmid or vector, the proliferation and migration of ccRCC 786-0 cells were determined by MTT assay and transwell assay, respectively. Furthermore, the anchorage-independent growth of transfected cells was assessed using soft agar colony formation assay. RESULTS: CMTM3 was down-regulated in 84 % (63/75) of ccRCC tissues and its expression had no correlation with the gender, age, clinical staging and histologic grade. CMTM3 protein was undetectable by western blot in most detected ccRCC specimens and two RCC cell lines (786-0 and ACHN). qRT-PCR analysis showed that CMTM3 mRNA was dramatically down-regulated in 40 ccRCC cancer tissues as compared with the paired adjacent normal ones. Restoration of CMTM3 significantly suppressed the anchorage-independent growth, proliferation and migration of 786-0 cells. CONCLUSION: These results indicate that CMTM3 is significantly down-regulated in ccRCC and exerts remarkable tumor-suppressive functions in 786-0 cells. Reduction of CMTM3 expression may contribute to the pathogenesis of ccRCC and CMTM3 may be a potentially target for therapeutic strategy.

Hypomethylation of tumor suppressor genes in odontogenic myxoma.

Odontogenic myxoma (OM) is an ectomesenchymal benign odontogenic tumor characterized by spindle or stellate-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. DNA methylation is characterized by the addition of methyl groups in cytosines within CpG islands in the promoter gene. DNA methylation can decrease the expression of tumor suppressor genes and contribute to the development of neoplastic lesions. The aim of study was to evaluate the methylation pattern of the tumor suppressor genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53) and RB1 in OM and dental pulp. Methylation was evaluated using methylation-specific polymerase chain reaction (PCR). The transcription was studied in some cases by using reverse transcription quantitative PCR. A higher frequency of unmethylated P27, P53, and RB1 samples was observed in the OM when compared with the dental pulp. OM expressed mRNA of all the genes evaluated. Considering all the samples together, the expression of Rb was higher in the unmethylated samples compared with the partially methylated samples. This investigation revealed hypomethylation of the genes P27, P53, and RB1 in OM. In addition, methylation of tumor suppressor genes was found to be an usual event in normal dental pulp.

Perfil de metilación de genes supresores de tumores como factor pronóstico en pacientes con leucemia mieloide aguda / Promoter methylation profile in tumor suppressor genes as prognosis factor in patients with acute myeloid leukemia

Existe creciente evidencia que apoya la presencia de un perfil de metilación específico para Leucemia Mieloide Aguda (LMA). La metilación de los islotes CpG en las regiones promotoras de los genes supresores de tumores es un importante mecanismo de control epigenético y participa en el silenciamiento transcripcional. Esto puede contribuir a un nuevo entendimiento de la biología de la enfermedad y vislumbrar nuevas oportunidades terapéuticas. Identificar el perfil de metilación de las áreas promotoras de un grupo de genes supresores de tumores; (p15, p16, ESR1, IGSF4, SOCS1, RARB y DAPK), y relacionar el estatus de metilación gen especifica o combinada con diferentes parámetros clínico patológicos. Se utilizaron muestras de sangre o médula ósea obtenidas al momento del diagnóstico de 33 pacientes con LMA, infantil y del adulto, recolectadas entre los años 1997 y 2008 en el Hospital Hernán Henríquez de Temuco. Se evaluó la presencia de hipermetilación mediante una Reacción de Polimerasa en Cadena Metilación Específica (MSP), previa modificación con bisulfito de sodio. La frecuencia de metilación de los pacientes estudiados fue de 88 por ciento, 27 por ciento, 27 por ciento, 21 por ciento, 15 por ciento, 3 por ciento y 0 por ciento para ESR1, RARb, IGSF4, p15, SOCS1, DAPK, y P16, respectivamente. La hipermetilación de P15 y RARb presentó una asociación significativa para una menor supervivencia en forma individual (p=0,03 y p=0,02), y combinada (p=0,002). No se encontraron diferencias significativas entre metilación y los otros parámetros clínicos analizados. Los pacientes con LMA presentan hipermetilación de la región promotora en algunos genes supresores de tumores, afectando negativamente la supervivencia. Esto pudiese eventualmente contribuir al establecimiento de un patrón de metilación determinado con utilidad clínica.

There is growing evidence than acute myeloid leukemia presents a specific methylation profile. The Methylation of CpG islands within gene promoters is a major epigenetic transcriptional control mechanism and plays a critical role in the transcriptional silencing of tumor suppressor genes. This provides new insights into the biology of the disease and it may offer novel therapeutic opportunities. To identify the promoter methylation profile of tumor suppressor genes (p15, p16, ESR1, IGSF4, SOCS1, RARB y DAPK), and to relate the percentage of methylation with clinicopathological features, as age, gender, white cell count, disease classification and survival rates. Bone marrow and peripheral blood samples were collected at diagnosis from 33 patients with acute myeloid leukemia, infants and adult, between 1997 and 2008 from Hernán Henríquez Aravena Hospital, Temuco, Chile. Methylation in the promoter areas of each tumor suppressor gene was analyzed using the mehylation specific polymerase chain reaction (MSP) technique using sodium bisulfite modification. The frequency of hypermethylation among the patient samples was 88 percent, 27 percent, 27 percent, 21 percent, 15 percent, 3 percent and 0 percent for ESR1, RARb, IGSF4, p15, SOCS1, DAPK, and P16 for each one. Methylation was significantly associated with an inferior overall survival (p=0.03 and p=0.02). When both genes are used, inferior survival is even more significant (p=0.002). There is no significant correlation between methylation and clinicopathological features.Patients with AML have hipermetilation at the promoter region of some tumor supressor genes, with a negative effect in the overall survival. This could eventually become part of establishing a characteristical methilation pattern with clinical utility.

Hypomethylation of tumor suppressor genes in odontogenic myxoma

Odontogenic myxoma (OM) is an ectomesenchymal benign odontogenic tumor characterized by spindle or stellate-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. DNA methylation is characterized by the addition of methyl groups in cytosines within CpG islands in the promoter gene. DNA methylation can decrease the expression of tumor suppressor genes and contribute to the development of neoplastic lesions. The aim of study was to evaluate the methylation pattern of the tumor suppressor genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53) and RB1 in OM and dental pulp. Methylation was evaluated using methylation-specific polymerase chain reaction (PCR). The transcription was studied in some cases by using reverse transcription quantitative PCR. A higher frequency of unmethylated P27, P53, and RB1 samples was observed in the OM when compared with the dental pulp. OM expressed mRNA of all the genes evaluated. Considering all the samples together, the expression of Rb was higher in the unmethylated samples compared with the partially methylated samples. This investigation revealed hypomethylation of the genes P27, P53, and RB1 in OM. In addition, methylation of tumor suppressor genes was found to be an usual event in normal dental pulp.

O mixoma odontogênico (MO) é um tumor odontogênico benigno de origem mesenquimal caracterizado pela presença de células fusiformes ou estreladas dispostas em abundante matriz extracelular mucóide. A metilação do DNA é caracterizada pela adição de grupos metil em citosinas constituintes de ilhas CpG na região promotora do gene. A metilação pode diminuir a expressão de genes supressores de tumor e contribuir para o desenvolvimento de lesões neoplásicas. O objetivo deste trabalho foi avaliar o padrão de metilação nos genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53), RB1 nos MO e na polpa dental. A metilação foi avaliada pela reação em cadeia da polimerase específica para a metilação. A transcrição dos genes foi estudada em alguns casos pela reação da transcriptase reversa (PCR quantitativa). Uma maior frequência de amostras não metiladas para os genes P27, P53 e RB1 foi observada nos MO quando comparados à polpa dental. Os MO expressaram RNAm de todos os genes avaliados. Considerando todas as amostras juntas, a expressão de Rb foi maior em amostras não metiladas comparadas as amostras parcialmente metiladas. Esta investigação mostrou a hipometilação dos genes P27, P53 e RB1 nos MO. Adicionalmente, a metilação nos genes supressores de tumor é um evento frequente em polpa dental normal.

Biology of Krüppel-like factor 6 transcriptional regulator in cell life and death.

An essential role for the Krüppel-like transcription factor family has been determined in the regulation of remarkable processes including cell proliferation, differentiation, signal transduction, oncogenesis, and cell death. A member of this group, Krüppel-like factor 6 (KLF6), identified on the basis of its ability to regulate a group of genes belonging to the carcinoembryonic antigen gene family, has been involved in human carcinogenesis. Early studies proposed a tumor suppressor function for KLF6 because of its ability to reduce cell proliferation through several biochemical mechanisms including regulation of cell cycle components, oncogene products, and apoptosis. Mutations within the klf6 gene, decreased expression and/or loss-of-heterozygosity were associated with the development of different human malignancies, and, hence, further supporting the tumor suppressor function of KLF6. This view has been challenged by other studies in distinct types of human cancers describing infrequent genetic alterations of klf6 gene or even enhanced expression in some tumors. The scenario about KLF6 function became still more complex as the description of oncogenic KLF6 splice variant 1 (SV1) with dominant negative activity against the wild type KLF6 (wtKLF6) protein. Additionally, increased evidence is suggesting that KLF6 is a bonafide target of several signaling cascades, which ultimate regulatory effect on this protein could drive decisions of cell life and death, facing the dilemma about how wtKLF6 could be involved in both processes. These apparently conflicting situations, emerged by apparently opposite effects mediated by wtKLF6, may be related, at least in part, to the biological cross-talk with the c-Jun oncoprotein. Depending on the stimulus received by the cell, wtKLF6 interaction with c-Jun determines different cell outcomes such as proliferation control or apoptosis. Thus, KLF6 responsiveness represents a kind of cell warning signal on receiving different stimuli, including oncogenic activation and microbial infections, orchestrating the implementation of proliferation and apoptotic programs.

Review article: Current concepts of ameloblastoma pathogenesis.

Ameloblastoma is a locally destructive and invasive tumour that can recur despite adequate surgical removal. Molecular studies have offered interesting findings regarding ameloblastoma pathogenesis. In the present review, the following topics are discussed regarding its molecular nature: clonality, cell cycle proliferation, apoptosis, tumour suppressor genes, ameloblastin and other enamel matrix proteins, osteoclastic mechanism and matrix metalloproteinases and other signalling molecules. It is clear from the literature reviewed that translational studies are necessary to identify prognostic markers of ameloblastoma behaviour and to establish new diagnostic tools to the differential diagnosis of unicystic from multicystic ameloblastoma. Finally, molecular biology studies are also important to develop more effective alternative approaches to the treatment of this aggressive odontogenic tumour.

Methylation status of nine tumor suppressor genes in multiple myeloma.

Aberrant methylation in promoter-associated CpG islands has been recognized as a major mechanism for tumor suppressor gene silencing in several malignancies. We determined the methylation status of nine tumor suppressor genes in 68 newly diagnosed MM patients by methylation-specific PCR. The frequency of promoter hypermethylation for individual genes was: CDH1, 50%; p16 INK4a, 42.8%; p15 INK4b, 16.2%; SHP1, 14.7%; ER and BNIP3, 13.2%; RAR beta, 11.8%; DAPK 5.9%; and MGMT 0%. Overall, 79% of patients presented at least one hypermethylated gene. By univariate analysis, hypermethylation of DAPK (P < 0.001) and RAR beta (P = 0.01) genes were identified as adverse prognostic features. Median OS of patients with hypermethylation in DAPK (4 months) and RAR beta (34 months) was significantly lower than in patients without hypermethylation (median survival not reached), with values of P < 0.001 and P = 0.01, respectively. Our data suggest that DAPK and RAR beta hypermethylation are adverse prognostic factors in MM. The relevance of these findings as poor prognosis indicators requires confirmation in a larger sample with longer follow-ups.

Imbalance of tumor suppression genes expression following rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide.

This study was undertaken to investigate, by immunohistochemistry, the expression of some tumor suppressor genes such as p16, p21 and Retinoblastoma (Rb) during 4-Nitroquinoline 1-oxide induced rat tongue carcinogenesis. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12 or 20 weeks. Ten animals were used as negative control. Neither histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure, nor statistically significant differences (p>0.05) in expression of all the tumor suppressor genes were found when compared to the negative control. However, the levels of Rb were increased (p<0.05) in pre-neoplastic lesions at 12 weeks following carcinogen exposure. In well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO, p16 and Rb were expressed in some tumor cells. Taken together, the results support the belief that the expression of Rb is closely event-related to malignant transformation and conversion of the oral mucosa, being a reliable biomarker linked to oral cancer pathogenesis.

[Molecular aspects of pituitary tumorigenesis]. / Aspectos moleculares da tumorigênese hipofisária.

Pituitary tumors, almost invariably adenomas, are of frequent occurrence, accounting for 10% to 15% of all the intracranial neoplasm. They are classified as microadenomas (< 10 mm) or macroadenomas (> 10 mm) and as secreting or clinically non-secreting (or not functioning) adenomas. These tumors are autonomously capable to release pituitary hormones such as the growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The occurrence of metastases, characterizing a pituitary carcinoma, is exceedingly rare. However tumors with aggressive behavior, leading to local invasion, are relatively common. Although the pathogenesis of pituitary tumors is fully characterized, many molecular mechanisms of pituitary tumorigenesis had already been revealed. This review intends to describe advances in the understanding of the involved advances that have been made in the last decade concerning pituitary tumors progression, including the participation of oncogenes, tumor suppressor genes and growth factors.

Aspectos moleculares da tumorigênese hipofisária: [revisão] / Molecular aspects of pituitary tumorigenesis: [review]

Os tumores hipofisários, adenomas em sua quase totalidade, são de ocorrência freqüente, representando 10 por cento a 15 por cento de todas as neoplasias intracranianas. Estas lesões são classificadas em microadenomas (< 10 mm) ou macroadenomas (> 10 mm) e como secretoras ou quiescentes (não-funcionantes). Estes tumores são capazes de secretar, de maneira autônoma, os hormônios adenohipofisários, como o hormônio de crescimento (GH), a prolactina (PRL), o hormônio adrenocorticotrófico (ACTH), o hormônio tireotrófico (TSH), o hormônio folículo estimulante (FSH) e o hormônio luteinizante (LH). A ocorrência de metástase, caracterizando um carcinoma hipofisário, é bastante rara, mas são relativamente comuns tumores de comportamento agressivo que exibem sinais de invasão local. Embora a sua patogênese ainda não seja plenamente caracterizada, muitos mecanismos moleculares envolvidos na tumorigênese hipofisária já foram desvendados. Nesta revisão, serão descritos avanços consideráveis realizados na última década relativos à compreensão dos fatores envolvidos na progressão tumoral, incluindo a participação de oncogenes, supressores tumorais e fatores de crescimento.

Pituitary tumors, almost invariably adenomas, are of frequent occurrence, accounting for 10 percent to 15 percent of all the intracranial neoplasm. They are classified as microadenomas (< 10 mm) or macroadenomas (> 10 mm) and as secreting or clinically non-secreting (or not functioning) adenomas. These tumors are autonomously capable to release pituitary hormones such as the growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The occurrence of metastases, characterizing a pituitary carcinoma, is exceedingly rare. However tumors with aggressive behavior, leading to local invasion, are relatively common. Although the pathogenesis of pituitary tumors is fully characterized, many molecular mechanisms of pituitary tumorigenesis had already been revealed. This review intents to describe advances in the understanding of the involved advances that have been made in the last decade concerning pituitary tumors progression, including the participation of oncogenes, tumor suppressor genes and growth factors.

Hypoxia-inducible factors and cancer.

Decreased oxygen availability is a common feature during embryonic development as well of malignant tumours. Hypoxia regulates many transcription factors, and one of the most studied is the hypoxia-inducible factor (HIF). As a consequence of HIF stabilisation, the cell constitutively upregulates the hypoxic programme resulting in the expression of genes responsible for global changes in cell proliferation, angiogenesis, metastasis, invasion, de-differentiation and energy metabolism. Of the three known alpha subunits of HIF transcription factors, HIF-1alpha and HIF-2alpha have been the most studied. Their differential expression and function have been widely discussed, however no clear picture has been drawn on how these two transcription factors differently regulate common and unique target genes. Their role as oncogenes has also been suggested in several studies. In this review we provide an overview of the current knowledge on some of the most important aspects of HIFalpha regulation, its role in tumour angiogenesis and energetic metabolism. We also give an overview of how the modulation of HIF regulating pathways is a potential therapeutic target that may have benefits in the treatment of cancer.

Genética, biologia molecular e carcinogênese mamária / Genetics, molecular biology and mammary carcinogenesis

Neste artigo são apresentados conceitos atuais sobre a carcinogênese mamária, enfocando aspectos de genética e de biologia molecular. Sabe-se que a carcinogênese pode ser subdividida em três fases: iniciação, promoção e progressão. A iniciação decorre de lesão genética em uma única célula-tronco, quase sempre localizada em lóbulo indiferenciado (tipo I). A alteração genética fundamental é a inativação de genes supressores (esporádica ou hereditária) ou a ativação de proto-oncogenes. A promoção é basicamente hormonal, destacando-se o papel dos esteróides sexuais, que atuam mediante interação com proteínas receptoras intranucleares. Na fase de progressão, ocorre a invasão da membrana basal e do estroma e embolização linfática, após perda no processo de adesão entre as células em conseqüência de ação de enzimas proteolíticas.

Current concepts on mammary carcinogenesis focusing genetics and molecular biology are presented. The carcinogenic process can be divided in 3 phases: initiation, promotion and progression. Initiation occurs in only one stem cell located in undifferentiated lobules (type I) and is caused by a genetic damage. The main genetic alteration is suppressor gene inactivation (sporadic or hereditary) or proto-oncogene activation. Promotion is basically due to steroid hormones action which interacts with intra-nuclear receptor proteins. After loosing adhesion malignant cells produce proteolytic enzymes, invade basal membrane and stroma and can embolyze through lymphatic channels.

CDH1 promoter hypermethylation and E-cadherin protein expression in infiltrating breast cancer.

BACKGROUND: The E-cadherin gene (CDH1) maps, at chromosome 16q22.1, a region often associated with loss of heterozygosity (LOH) in human breast cancer. LOH at this site is thought to lead to loss of function of this tumor suppressor gene and was correlated with decreased disease-free survival, poor prognosis, and metastasis. Differential CpG island methylation in the promoter region of the CDH1 gene might be an alternative way for the loss of expression and function of E-cadherin, leading to loss of tissue integrity, an essential step in tumor progression. METHODS: The aim of our study was to assess, by Methylation-Specific Polymerase Chain Reaction (MSP), the methylation pattern of the CDH1 gene and its possible correlation with the expression of E-cadherin and other standard immunohistochemical parameters (Her-2, ER, PgR, p53, and K-67) in a series of 79 primary breast cancers (71 infiltrating ductal, 5 infiltrating lobular, 1 metaplastic, 1 apocrine, and 1 papillary carcinoma). RESULTS: CDH1 hypermethylation was observed in 72% of the cases including 52/71 ductal, 4/5 lobular carcinomas and 1 apocrine carcinoma. Reduced levels of E-cadherin protein were observed in 85% of our samples. Although not statistically significant, the levels of E-cadherin expression tended to diminish with the CDH1 promoter region methylation. In the group of 71 ductal cancinomas, most of the cases of showing CDH1 hypermethylation also presented reduced levels of expression of ER and PgR proteins, and a possible association was observed between CDH1 methylation and ER expression (p = 0.0301, Fisher's exact test). However, this finding was not considered significant after Bonferroni correction of p-value. CONCLUSION: Our preliminary findings suggested that abnormal CDH1 methylation occurs in high frequencies in infiltrating breast cancers associated with a decrease in E-cadherin expression in a subgroup of cases characterized by loss of expression of other important genes to the mammary carcinogenesis process, probably due to the disruption of the mechanism of maintenance of DNA methylation in tumoral cells.

Assessment of p63 expression in oral squamous cell carcinomas and dysplasias.

OBJECTIVES: p63, a p53 homologue, may be associated with tumorigenesis in epithelial tissues through its inhibition of p53 transactivation functions. We sought to determine the pattern and levels of p63 expression in oral dysplasias and carcinomas using standard immunohistochemical staining. We also assessed and compared expression of p53 and a cell proliferation marker in these lesions. STUDY DESIGN: This retrospective cross-sectional survey (n=67) included hyperkeratosis (10), mild dysplasia (9), moderate dysplasia (11), severe dysplasia/in situ carcinoma (10), squamous cell carcinoma (SCC) (22 [9 well differentiated, 7 moderately differentiated, 6 poor differentiated]), and normal mucosa (5). Serial sections were stained immunohistochemically with antibodies to p63 (4A4 recognizing all p63 isotypes), p53 (DO-7), and Ki-67 (MIB-1) proteins. In preinvasive lesions, both the percentage of positive cells and staining patterns (negative, basal, suprabasal) were assessed. In oral SCCs, the percentage of positive cells was assessed. Statistical analysis was done using the Tukey-Kramer multiple comparisons test. RESULTS: A suprabasal p63 staining pattern was evident in keratinocyte nuclei in the entire range of noninvasive lesions studied, including normal mucosa. Most nuclei in invasive SCCs stained positive. When all grades of dysplasia were combined, the percent of p63 positive cells was significantly greater than hyperkeratosis (P < .01), and well-differentiated SCC (P < .001). Moderately differentiated SCC had statistically significant more positive cells than well-differentiated SSC (P < .01). Comparison of serial sections showed different p63 staining patterns compared to p53 or Ki-67 staining patterns. CONCLUSIONS: We conclude that p63 is expressed in oral carcinomas and dysplasias, as determined by immunohistochemical staining with a primary antibody to all isotypes. Neither staining pattern nor percentage of stained cells could be used to differentiate the lesions studied. The statistically significant differences found between some groups are not likely to be of diagnostic value. p63 is not coexpressed with p53 expression or Ki-67 suggesting functional independence. When antibodies to the p63 isotypes become available, oral dysplasias and carcinomas should be reassessed.

Bases moleculares dos adenomas hipofisários com ênfase nos somatotropinomas / Molecular basis of pituitary adenomas with emphasis on somatotropinomas

Esta revisão descreve as bases moleculares dos adenomas hipofisários com ênfase nos tumores secretores de GH (somatotropinomas). São discutidos os papéis de genes de supressão tumoral (como RB1, MEN-1) e de oncogenes (como gsp, PTTG) na iniciação e progressão destes tumores. A caracterização destes marcadores moleculares pode ajudar na compreensão do comportamento tumoral, auxiliando a conduta terapêutica. Entretanto, apesar dos recentes avanços, ainda não é totalmente conhecida a seqüência de alterações genéticas envolvidas na patogênese destes adenomas.