RESUMEN
Pax-5, an essential transcription factor for B lymphocyte development, has been linked with the development and progression of lymphoid cancers and carcinoma. In contrast to B-cell cancer lesions, the specific expression signatures and roles of Pax-5 in breast cancer progression are relatively unknown. In the present study, we set out to profile Pax-5 expression in mammary tissues and elucidate the cellular and molecular roles of Pax-5 in breast cancer processes. Using immunohistology on mammary tissue arrays, Pax-5 was detected in a total of 298/306 (97.6%) samples tested. Interestingly, our studies reveal that Pax-5 inhibits aggressive features and confers anti-proliferative effects in breast carcinoma cells in contrast to its oncogenic properties in B cell cancers. More precisely, Pax-5 suppressed breast cancer cell migration, invasion and tumor spheroid formation while concomitantly promoting cell adhesion properties. We also observed that Pax-5 inhibited and reversed breast cancer epithelial to mesenchymal phenotypic transitioning. Mechanistically, we found that the Pax-5 transcription factor binds and induces gene expression of E-cadherin, a pivotal regulator of epithelialisation. Globally, we demonstrate that Pax-5 is predominant expressed factor in mammary epithelial cells. We also present an important role for Pax-5 in the phenotypic transitioning processes and aggressive features associated with breast cancer malignancy and disease progression.
Asunto(s)
Neoplasias de la Mama/genética , Cadherinas/genética , Regulación Neoplásica de la Expresión Génica , Factor de Transcripción PAX5/genética , Antígenos CD , Western Blotting , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Cadherinas/metabolismo , Adhesión Celular/genética , Línea Celular , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Progresión de la Enfermedad , Transición Epitelial-Mesenquimal/genética , Femenino , Células HEK293 , Humanos , Inmunohistoquímica , Células MCF-7 , Glándulas Mamarias Humanas/metabolismo , Factor de Transcripción PAX5/metabolismo , Interferencia de ARN , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The transcription factor Pax5 plays a critical role in B cell development. It has been shown that alternative splicing of its gene (PAX5) produces several distinct transcripts that modify the amino acid sequence of the putative Pax5 proteins. Subsequent studies have attempted to correlate the expression of PAX5 isoforms with certain B-cell lymphomas, the conclusions of which suggest that altered isoform expression is involved in lymphomagenesis. However, in the absence of definitive data for PAX5 isoform expression patterns in normal B cells it is difficult to confirm whether aberrant isoform expression can indeed be correlated with disease. Using a high-resolution method of analysis of reverse transcription polymerase chain reaction products, we sought to analyse the expression of the different PAX5 isoforms in normal B-cells as well as a number of B-cell lymphoma and chronic lymphocytic leukaemia cases. It was found that multiple PAX5 isoforms were expressed in both normal and malignant B cells. Immunodetection and polysomal RNA analyses also confirmed that the different PAX5 mRNAs were translated into their corresponding proteins. No consistent deregulation of PAX5 isoform expression was observed in B-cell lymphomas, but rather, complex isoform expression patterns were found in normal B cell as well as B-cell lymphoma and CLL cases.
Asunto(s)
Linfocitos B/metabolismo , Linfoma de Células B/metabolismo , Proteínas de Neoplasias/metabolismo , Factor de Transcripción PAX5/metabolismo , Empalme Alternativo , Secuencia de Bases , Western Blotting/métodos , Humanos , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfocítica Crónica de Células B/metabolismo , Linfoma de Células B/genética , Técnicas Analíticas Microfluídicas/métodos , Datos de Secuencia Molecular , Proteínas de Neoplasias/genética , Factor de Transcripción PAX5/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , ARN Mensajero/genética , ARN Neoplásico/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Células Tumorales CultivadasRESUMEN
In the present study, we examined the expression of the mammaglobin genes, MGB1 and MGB2, in the sentinel lymph nodes (SLNs) of patients with breast cancer and compared our results with the histologic status of the same SLNs. Compared with immunohistochemical staining for cytokeratin 8, which detected metastases in 17 of 42 patients, reverse transcription-polymerase chain reaction (RT-PCR) for MGB1 or MGB2 genes was positive in 22 patients. The concordance between the expression of any mammaglobin and histologic status was 79% (33/42), with a sensitivity of 88% and specificity of 72%. The detection of patients with metastases was more sensitive when testing for both MGB1 and MGB2 (P < .0001) rather than MGB2 (P < .0005) or MGB1 (P < .05) alone. The increased detection rate relative to histologic examination suggests that using RT-PCR for the mammaglobin genes might identify patients at higher risk compared with patients with negative RT-PCR results.