TY - JOUR
T1 - Downregulation of Muc1 in MMTV-c-Neu tumors
AU - Adriance, Melissa C.
AU - Gendler, Sandra J.
N1 - Funding Information:
We thank Christopher J Sterner for excellent technical assistance in the breeding and palpation of the c-Neu/ Muc1+/+ and c-Neu/Muc1−/− mice. We also thank Dr Yosef Yarden and Dr Nancy Hynes for ErbB2 constructs, Dr Yaacov Barak for Muc1 deletion constructs, Dr William Muller for the c-Neu transgenic mice, Dr David Lee for the c-Neu probe, Dr Robert Oshima for the keratin 18 cDNA probe, Jim Tarara and Linda Murphy for technical support, and Dr Patrick Roche for providing human breast tumor sections. We also thank Suresh Savarirayan, and animal care attendants for animal care, Marvin Ruona for computer graphics, and Carol Williams for manuscript preparation and submission. This work was supported by NIH CA064389 (SJG), NIH predoctoral fellowship CA090205 (MCA), and the Mayo Foundation.
PY - 2004/1/22
Y1 - 2004/1/22
N2 - MUC1 is a tumor antigen, overexpressed in approximately 90% of human breast cancers. In normal glandular epithelia, MUC1 is expressed at the apical surface; however, in carcinomas an aberrantly glycosylated form of MUC1 is upregulated and expressed around the entire surface of the cell. Previously, we have shown that a lack of Muc1 significantly delays tumor progression and/or onset in MMTV-PyV-mT and MMTV-Wnt-1 transgenic mice. Here we show that, unlike the models mentioned above, a loss of Muc1 in MMTV-c-Neu mice (MMTV-c-Neu/Muc1-/-) altered neither mammary tumor onset nor progression. Moreover, characterization of MMTV-c-Neu/Muc1+/+ tumors revealed that Muc1 expression was repressed at the level of transcription. In contrast, normal mammary gland tissue adjacent to tumor tissue expressed Muc1 and pregnant mammary glands from c-Neu transgenic animals expressed high levels of Muc1. We found that transient transfection of activated ErbB2 into human embryonic kidney 293/MUC1 cells resulted in the repression of MUC1 expression. Further, transient transfection of activated ErbB2 resulted in the inhibition of Muc1 transcriptional activation in luciferase reporter assays. These data suggest that the activation of ErbB2, which only occurs in c-Neu tumors, selectively inhibits Muc1 expression.
AB - MUC1 is a tumor antigen, overexpressed in approximately 90% of human breast cancers. In normal glandular epithelia, MUC1 is expressed at the apical surface; however, in carcinomas an aberrantly glycosylated form of MUC1 is upregulated and expressed around the entire surface of the cell. Previously, we have shown that a lack of Muc1 significantly delays tumor progression and/or onset in MMTV-PyV-mT and MMTV-Wnt-1 transgenic mice. Here we show that, unlike the models mentioned above, a loss of Muc1 in MMTV-c-Neu mice (MMTV-c-Neu/Muc1-/-) altered neither mammary tumor onset nor progression. Moreover, characterization of MMTV-c-Neu/Muc1+/+ tumors revealed that Muc1 expression was repressed at the level of transcription. In contrast, normal mammary gland tissue adjacent to tumor tissue expressed Muc1 and pregnant mammary glands from c-Neu transgenic animals expressed high levels of Muc1. We found that transient transfection of activated ErbB2 into human embryonic kidney 293/MUC1 cells resulted in the repression of MUC1 expression. Further, transient transfection of activated ErbB2 resulted in the inhibition of Muc1 transcriptional activation in luciferase reporter assays. These data suggest that the activation of ErbB2, which only occurs in c-Neu tumors, selectively inhibits Muc1 expression.
KW - ErbB2
KW - MUC1
KW - Transmembrane mucin
KW - erbB receptors
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U2 - 10.1038/sj.onc.1207165
DO - 10.1038/sj.onc.1207165
M3 - Article
C2 - 14737104
AN - SCOPUS:1242318509
SN - 0950-9232
VL - 23
SP - 697
EP - 705
JO - Oncogene
JF - Oncogene
IS - 3
ER -