ADAM33 gene silencing by promoter hypermethylation as a molecular marker in breast invasive lobular carcinoma

<p>Abstract</p> <p>Background</p> <p>ADAM33 protein is a member of the family of transmembrane glycoproteins composed of multidomains. ADAM family members have different activities, such as proteolysis and adhesion, making them good candidates to mediate the extracellular matrix remodelling and changes in cellular adhesion that characterise certain pathologies and cancer development. It was reported that one family member, <it>ADAM23</it>, is down-regulated by promoter hypermethylation. This seems to correlate with tumour progression and metastasis in breast cancer. In this study, we explored the involvement of ADAM33, another ADAM family member, in breast cancer.</p> <p>Methods</p> <p>First, we analysed <it>ADAM33 </it>expression in breast tumour cell lines by RT-PCR and western blotting. We also used 5-aza-2'-deoxycytidine (5azadCR) treatment and DNA bisulphite sequencing to study the promoter methylation of ADAM33 in breast tumour cell lines. We evaluated ADAM33 methylation in primary tumour samples by methylation specific PCR (MSP). Finally, <it>ADAM33 </it>promoter hypermethylation was correlated with clinicopathological data using the chi-square test and Fisher's exact test.</p> <p>Results</p> <p>The expression analysis of <it>ADAM33 </it>in breast tumour cell lines by RT-PCR revealed gene silencing in 65% of tumour cell lines. The corresponding lack of ADAM33 protein was confirmed by western blotting. We also used 5-aza-2'-deoxycytidine (5-aza-dCR) demethylation and bisulphite sequencing methodologies to confirm that gene silencing is due to <it>ADAM33 </it>promoter hypermethylation. Using MSP, we detected <it>ADAM33 </it>promoter hypermethylation in 40% of primary breast tumour samples. The correlation between methylation pattern and patient's clinicopathological data was not significantly associated with histological grade; tumour stage (TNM); tumour size; ER, PR or ERBB2 status; lymph node status; metastasis or recurrence. Methylation frequency in invasive lobular carcinoma (ILC) was 76.2% compared with 25.5% in invasive ductal carcinoma (IDC), and this difference was statistically significant (p = 0.0002).</p> <p>Conclusion</p> <p><it>ADAM33 </it>gene silencing may be related to the discohesive histological appearance of ILCs. We suggest that <it>ADAM33 </it>promoter methylation may be a useful molecular marker for differentiating ILC and IDC.</p

Epigenetic Changes of CXCR4 and Its Ligand CXCL12 as Prognostic Factors for Sporadic Breast Cancer

Chemokines and their receptors are involved in the development and cancer progression. The chemokine CXCL12 interacts with its receptor, CXCR4, to promote cellular adhesion, survival, proliferation and migration. The CXCR4 gene is upregulated in several types of cancers, including skin, lung, pancreas, brain and breast tumors. In pancreatic cancer and melanoma, CXCR4 expression is regulated by DNA methylation within its promoter region. In this study we examined the role of cytosine methylation in the regulation of CXCR4 expression in breast cancer cell lines and also correlated the methylation pattern with the clinicopathological aspects of sixty-nine primary breast tumors from a cohort of Brazilian women. RT-PCR showed that the PMC-42, MCF7 and MDA-MB-436 breast tumor cell lines expressed high levels of CXCR4. Conversely, the MDA-MB-435 cell line only expressed CXCR4 after treatment with 5-Aza-CdR, which suggests that CXCR4 expression is regulated by DNA methylation. To confirm this hypothesis, a 184 bp fragment of the CXCR4 gene promoter region was cloned after sodium bisulfite DNA treatment. Sequencing data showed that cell lines that expressed CXCR4 had only 15% of methylated CpG dinucleotides, while the cell line that not have CXCR4 expression, had a high density of methylation (91%). Loss of DNA methylation in the CXCR4 promoter was detected in 67% of the breast cancer analyzed. The absence of CXCR4 methylation was associated with the tumor stage, size, histological grade, lymph node status, ESR1 methylation and CXCL12 methylation, metastasis and patient death. Kaplan-Meier curves demonstrated that patients with an unmethylated CXCR4 promoter had a poorer overall survival and disease-free survival. Furthermore, patients with both CXCL12 methylation and unmethylated CXCR4 had a shorter overall survival and disease-free survival. These findings suggest that the DNA methylation status of both CXCR4 and CXCL12 genes could be used as a biomarker for prognosis in breast cancer

Simultaneous CXCL12 and ESR1 CpG island hypermethylation correlates with poor prognosis in sporadic breast cancer

<p>Abstract</p> <p>Background</p> <p>CXCL12 is a chemokine that is constitutively expressed in many organs and tissues. <it>CXCL12 </it>promoter hypermethylation has been detected in primary breast tumours and contributes to their metastatic potential. It has been shown that the oestrogen receptor α (<it>ESR1</it>) gene can also be silenced by DNA methylation. In this study, we used methylation-specific PCR (MSP) to analyse the methylation status in two regions of the <it>CXCL12 </it>promoter and <it>ESR1 </it>in tumour cell lines and in primary breast tumour samples, and correlated our results with clinicopathological data.</p> <p>Methods</p> <p>First, we analysed <it>CXCL12 </it>expression in breast tumour cell lines by RT-PCR. We also used 5-aza-2'-deoxycytidine (5-aza-CdR) treatment and DNA bisulphite sequencing to study the promoter methylation for a specific region of <it>CXCL12 </it>in breast tumour cell lines. We evaluated <it>CXCL12 </it>and <it>ESR1 </it>methylation in primary tumour samples by methylation-specific PCR (MSP). Finally, promoter hypermethylation of these genes was analysed using Fisher's exact test and correlated with clinicopathological data using the Chi square test, Kaplan-Meier survival analysis and Cox regression analysis.</p> <p>Results</p> <p><it>CXCL12 </it>promoter hypermethylation in the first region (island 2) and second region (island 4) was correlated with lack of expression of the gene in tumour cell lines. In the primary tumours, island 2 was hypermethylated in 14.5% of the samples and island 4 was hypermethylated in 54% of the samples. The <it>ESR1 </it>promoter was hypermethylated in 41% of breast tumour samples. In addition, the levels of ERα protein expression diminished with increased frequency of <it>ESR1 </it>methylation (p < 0.0001). This study also demonstrated that <it>CXCL12 </it>island 4 and <it>ESR1 </it>methylation occur simultaneously at a high frequency (p = 0.0220).</p> <p>Conclusions</p> <p>This is the first study showing a simultaneous involvement of epigenetic regulation for both <it>CXCL12 </it>and <it>ESR1 </it>genes in Brazilian women. The methylation status of both genes was significantly correlated with histologically advanced disease, the presence of metastases and death. Therefore, the methylation pattern of these genes could be used as a molecular marker for the prediction of breast cancer outcome.</p

Análise genética e funcional dos genes nifENXorf1orf2, nifQmodABCfixXC de Herbaspirillum seropedicae

Orientadora: Prof.ª Dr.ª Liu Un RigoTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Curso de Pós-Graduação em Ciências-BioquímicaInclui referências: p. 104-14

Contribuição a fisiologia da fixação de nitrogênio em estirpes de Herbaspirillum seropedicae

Orientadora: Dra. Liu Un RigoDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Curso de Pós-Graduação em BioquímicaInclui referências: p. 94-114Resumo: Em Herbaspirillum seropedicae SMR1 a faixa de pH inicial ótima para crescimento foi entre 4,5 e 8,0, sendo que para atividade da nitrogenase a faixa ideal foi entre 4,5 e 6,5. A densidade de cultura ótima para expressão da nitrogenase para a estirpe SMR1 foi entre 1,5 e 1,8 em 550 nm. Todas as estirpes utilizadas (Z67, ZA69, ZA76, SMR1, ZA95 e Z152) apresentaram atividades da nitrogenase em meio líquido NFbHP com DL-malato e L-glutamato. As estirpes Z67, ZA69, ZA76, SMR1, ZA95 e Z152 crescem utilizando DL-malato, DL-lactato, Lrhamnose ou D-glucose como fontes únicas de carbono. A utilização de Drafinose, D-manose ou D-maltose é lenta e NH4 dependente. Estas estirpes crescem diazotroficamente em meio semi-sólido NFbHP isento de nitrogênio fixado utilizando DL-malato, DL-lactato, L-rhamnose ou D-glucose como fontes de carbono. A estirpe SMR1 foi capaz de fixar nitrogênio em meio líquido utilizando DL-malato ou DL-lactato como fontes de carbono, mas não com D-glucose, Lrhamnose, D-manose, D-rafinose, D-maltose ou L-glutamato. Não foi observado crescimento ou atividade da nitrogenase pela estirpe SMR1 em meio NFbHP contendo metilamina ou L-histidina como fontes de nitrogênio. A utilização de DLserina e L-cisteína foram deficientes. As estirpes SMR1, ZA95 e Z152 possuem temperatura ótima de crescimento a 30°C. Concentrações superiores a 5 mM de cloreto de amónio no meio de cultura reprimem a nitrogenase da estirpe SMR1 de forma irreversível. Amônia, L-glutamato, metilamina, DL-serina e L-cisteína produzem desligamento parcial da nitrogenase na estirpe SMR1 . Foram observados desrepressão após crescimento em cloreto de amónio 2 mM e desligamento da nitrogenase por amônia também para as estirpes Z67, ZA69, ZA76, ZA95 e Z152. Entre as estirpes utilizadas somente ZA95 apresentou um plasmídeo com aproximadamente 70 MDa, enquanto a estirpe Z152 apresentou dois plasmídeos com 60 e 70 MDa; as demais estirpes Z67, ZA69, ZA76 e SMR1 não apresentaram plasmídeos naturais

Nitrogenase Switch-Off by Ammonium Ions in Azospirillum brasilense Requires the GlnB Nitrogen Signal-Transducing Protein

Nitrogenase activity in several diazotrophs is switched off by ammonium and reactivated after consumption. The signaling pathway to this system in Azospirillum brasilense is not understood. We show that ammonium-dependent switch-off through ADP-ribosylation of Fe protein was partial in a glnB mutant of A. brasilense but absent in a glnB glnZ double mutant. Triggering of inactivation by anaerobic conditions was not affected in either mutant. The results suggest that glnB is necessary for full ammonium-dependent nitrogenase switch-off in A. brasilense