Negative transcriptional control of ERBB2 gene by MBP-1 and HDAC1: diagnostic implications in breast cancer

作者：Contino Flavia; Mazzarella Claudia; Ferro Arianna; Lo Presti Mariavera; Roz Elena; Lupo Carmelo; Perconti Giovanni; Giallongo Agata^*; Feo Salvatore

来源：BMC Cancer, 2013, 13(1): 81.

DOI：10.1186/1471-2407-13-81

• MBP-1
• ERBB2
• Transcriptional regulation
• Histone Deacetylase
• Breast cancer

Background: The human ERBB2 gene is frequently amplified in breast tumors, and its high expression is associated with poor prognosis. We previously reported a significant inverse correlation between Myc promoter-binding protein-1 (MBP-1) and ERBB2 expression in primary breast invasive ductal carcinoma (IDC). MBP-1 is a transcriptional repressor of the c-MYC gene that acts by binding to the P2 promoter; only one other direct target of MBP-1, the COX2 gene, has been identified so far. %26lt;br%26gt;Methods: To gain new insights into the functional relationship linking MBP-1 and ERBB2 in breast cancer, we have investigated the effects of MBP-1 expression on endogenous ERBB2 transcript and protein levels, as well as on transcription promoter activity, by transient-transfection of SKBr3 cells. Reporter gene and chromatin immunoprecipitation assays were used to dissect the ERBB2 promoter and identify functional MBP-1 target sequences. We also investigated the relative expression of MBP-1 and HDAC1 in IDC and normal breast tissues by immunoblot analysis and immunohistochemistry. %26lt;br%26gt;Results: Transfection experiments and chromatin immunoprecipitation assays in SKBr3 cells indicated that MBP-1 negatively regulates the ERBB2 gene by binding to a genomic region between nucleotide -514 and -262 of the proximal promoter; consistent with this, a concomitant recruitment of HDAC1 and loss of acetylated histone H4 was observed. In addition, we found high expression of MBP-1 and HDAC1 in normal tissues and a statistically significant inverse correlation with ErbB2 expression in the paired tumor samples. %26lt;br%26gt;Conclusions: Altogether, our in vitro and in vivo data indicate that the ERBB2 gene is a novel MBP-1 target, and immunohistochemistry analysis of primary tumors suggests that the concomitant high expression of MBP-1 and HDAC1 may be considered a diagnostic marker of cancer progression for breast IDC.

• 出版日期2013-2-19