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Frequent downregulation of 14-3-3 sigma protein and hypermethylation of 14-3-3 sigma gene in salivary gland adenoid cystic carcinoma.

Uchida D, Begum NM, Almofti A, Kawamata H, Yoshida H, Sato M - Br. J. Cancer (2004)

Bottom Line: Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC.Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation.These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.

View Article: PubMed Central - PubMed

Affiliation: Second Department of Oral and Maxillofacial Surgery, Tokushima University School of Dentistry, 3-18-15 Kuramoto, Tokushima 770-8504, Japan. daisuke@dent.tokushima-u.ac.jp

ABSTRACT
14-3-3 sigma:, a target gene of the p53 tumour suppressor protein, has been shown to regulate the cell cycle at the G2/M checkpoint. Recent studies have demonstrated that 14-3-3 sigma is downregulated by hypermethylation of the CpG island in several types of cancer. In this study, we investigated the expression and methylation status of 14-3-3 sigma in human salivary gland adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Immunohistochemical analysis revealed that the positive expression rate of 14-3-3 sigma in ACC (one out of 14) was markedly lower than that in MEC (ten out of 10). Since most of the ACCs carried the wild-type p53 protein, downregulation of 14-3-3 sigma in ACC may not be due to the dysfunction of p53 pathway. Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC. In cultured-ACC cells, we confirmed the downregulation of 14-3-3 sigma via hemimethylation of the gene by sequencing analysis after sodium bisulphite treatment. Furthermore, re-expression of 14-3-3 sigma in the ACC cells was induced by the treatment with DNA demethylating agent, 5-aza-2'-deoxycytidine. Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation. These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.

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Cell cycle analysis of the SGC and normal cells after irradiation. (A) Cells were irradiated at 15 Gy, then harvested at 24, 48, and 72 h after irradiation. After staining with PI, cell cycles were analysed by flow cytometry. The populations of each phase are shown for the SG1 cells (left) and ACC cells (right). (B) Expression of the 14-3-3 σ protein after irradiation.
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fig5: Cell cycle analysis of the SGC and normal cells after irradiation. (A) Cells were irradiated at 15 Gy, then harvested at 24, 48, and 72 h after irradiation. After staining with PI, cell cycles were analysed by flow cytometry. The populations of each phase are shown for the SG1 cells (left) and ACC cells (right). (B) Expression of the 14-3-3 σ protein after irradiation.

Mentions: As shown in Figure 5A and BFigure 5


Frequent downregulation of 14-3-3 sigma protein and hypermethylation of 14-3-3 sigma gene in salivary gland adenoid cystic carcinoma.

Uchida D, Begum NM, Almofti A, Kawamata H, Yoshida H, Sato M - Br. J. Cancer (2004)

Cell cycle analysis of the SGC and normal cells after irradiation. (A) Cells were irradiated at 15 Gy, then harvested at 24, 48, and 72 h after irradiation. After staining with PI, cell cycles were analysed by flow cytometry. The populations of each phase are shown for the SG1 cells (left) and ACC cells (right). (B) Expression of the 14-3-3 σ protein after irradiation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2747720&req=5

fig5: Cell cycle analysis of the SGC and normal cells after irradiation. (A) Cells were irradiated at 15 Gy, then harvested at 24, 48, and 72 h after irradiation. After staining with PI, cell cycles were analysed by flow cytometry. The populations of each phase are shown for the SG1 cells (left) and ACC cells (right). (B) Expression of the 14-3-3 σ protein after irradiation.
Mentions: As shown in Figure 5A and BFigure 5

Bottom Line: Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC.Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation.These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.

View Article: PubMed Central - PubMed

Affiliation: Second Department of Oral and Maxillofacial Surgery, Tokushima University School of Dentistry, 3-18-15 Kuramoto, Tokushima 770-8504, Japan. daisuke@dent.tokushima-u.ac.jp

ABSTRACT
14-3-3 sigma:, a target gene of the p53 tumour suppressor protein, has been shown to regulate the cell cycle at the G2/M checkpoint. Recent studies have demonstrated that 14-3-3 sigma is downregulated by hypermethylation of the CpG island in several types of cancer. In this study, we investigated the expression and methylation status of 14-3-3 sigma in human salivary gland adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Immunohistochemical analysis revealed that the positive expression rate of 14-3-3 sigma in ACC (one out of 14) was markedly lower than that in MEC (ten out of 10). Since most of the ACCs carried the wild-type p53 protein, downregulation of 14-3-3 sigma in ACC may not be due to the dysfunction of p53 pathway. Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC. In cultured-ACC cells, we confirmed the downregulation of 14-3-3 sigma via hemimethylation of the gene by sequencing analysis after sodium bisulphite treatment. Furthermore, re-expression of 14-3-3 sigma in the ACC cells was induced by the treatment with DNA demethylating agent, 5-aza-2'-deoxycytidine. Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation. These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.

Show MeSH
Related in: MedlinePlus