RESUMO
AIM: To investigate the expression of SNC73, a trans-cript of the immunoglobulin alpha-1 gene (IgA1-H chain), in human epithelia-derived tumor cells. METHODS: Total RNAs and cell lysates were prepared from five different human epithelial cell lines derived from lung, stomach, liver, skin, and breast, respectively. RT-PCR and immunoblot analysis of these five cell lines were done. Both RT-PCR and immunochemistry were used to detect the expression of SNC73 in these cell lines. We also examined the expression of SNC73 in normal epithelial cells of colon mucosa by in situ hybridization. RT-PCR and immunoblot analysis were used to determine whether the recombination activating gene1/2 (RAG1 and RAG2) is present. The expression of three immunoglobulin transcription factors, EBF, E2A and Pax5, and the heavy chain of IgA1 and two types of light chains of immunoglobulin (kappa and lambda) in the aforementioned cell lines were analyzed by RT-PCR and immunochemistry, respectively. All the RT-PCR products were analyzed by sequencing. RESULTS: The results of RT-PCR and immunochemistry showed that both mRNA and protein of SNC73 were expressed in five human epithelia-derived cancer cell lines. These data were further confirmed in the normal epithelial cells of colon mucosa by in situ hybridization. Also, the heavy chain of IgA1 and kappa light chain were detected in these cells, but no lambda light chain was obse-rved. Both RAG1 and RAG2 were expressed in these human epithelia-derived cancer cell lines and the sequence was identical to that expressed in pre-B and pre-T cells. In addition to RAG1 and RAG2, the mRNA in one of the immunoglobulin transcription factors, EBF, was also detected in these cell lines, and Pax5 was only expressed in SW480 cells, but no expression of E2A was observed in all the five cell lines. CONCLUSION: Immunoglobulin A1 is originally expressed and V(D)J recombination machine is also present in non-lymphoid cells, suggesting that V(D)J recombination machine mediates the assembly of immunoglobulin A1 in non-lymphoid cells as in pre-lymphocytes.
Assuntos
Neoplasias da Mama/metabolismo , Neoplasias Colorretais/metabolismo , Imunoglobulinas/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias do Colo do Útero/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Colo/metabolismo , Colo/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Células Epiteliais/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Células HeLa , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Imunoglobulinas/genética , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Transativadores/genética , Transativadores/metabolismo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia , Éxons VDJ/genéticaRESUMO
OBJECTIVE: To study if the gene SNC73 (IgHalpha1) is expressed in human epithelial cancer cell line and to interpret the recombination mechanism. METHODS: Human epithelial cancer cells of SW480 line were cultured. RT-PCR and Western blotting were used to examine the expression of SNC73, recombination activating gene 1 (RAG1), and RAG2. The RT-PCR products were confirmed by sequencing. Immunohistochemistry was used to detect the expression of IgHalpha1, Igkappa, and Iglambda in these epithelial cancer cells. RESULTS: The human epithelial cancer cell line (SW480) positively expressed SNC73, RAG1, and RAG2. IgHalpha1 and Igkappa was strongly expressed in SW480 cells, but Iglambda was undetectable. The sequence of the constant region of SNC73 in SW480 cells is identical to that of IgA1. Both sequencing and Western blotting showed that the RAG1 and RAG2 expressed in SW480 cells were identical to that expressed in pre-B lymphocytes. CONCLUSION: Immunoglobulin alpha-1 gene is expressed in non-lymphoid cells, which may be a potential genetic marker for the development of colorectal cancer. Recombination signal sequence (RSS)-mediated recombination may take part in the rearrangement of immunoglobulin alpha-1 gene in human epithelial cancer cell line.