TY - JOUR
T1 - Overexpression of the tumor suppressor gene phosphatase and tensin homologue partially inhibits Wnt-1-induced mammary tumorigenesis
AU - Zhao, Hong
AU - Cui, Yongzhi
AU - Dupont, Joelle
AU - Sun, Hui
AU - Hennighausen, Lothar
AU - Yakar, Shoshana
PY - 2005/8/1
Y1 - 2005/8/1
N2 - The tumor suppressor phosphatase and tensin homologue (PTEN) is involved in cell proliferation, adhesion, and apoptosis. PTEN overexpression in mammary epithelium leads to reduced cell number and impaired differentiation and secretion. In contrast, overexpression of the proto-oncogene Wnt-1 in mammary epithelium leads to mammary hyperplasia and subsequently focal mammary tumors. To explore the possibility that PTEN intersects with Wnt-induced tumorigenesis, mice that ectopically express PTEN and Wnt-1 in mammary epithelium were generated. PTEN overexpression resulted in an 11% reduction of Wnt-1-induced tumors within a 12-month period and the onset of tumors was delayed from an average of 5.9 to 7.7 months. The rate of tumor growth, measured from 0.5 cm diameter until the tumors reached 1.0 cm diameter, was increased from 8.4 days in Wnt-1 mice to 17.7 days in Wnt-1 mice overexpressing PTEN. Here we show for the first time in vivo that overexpression of PTEN in the Wnt-1 transgenic mice resulted in a marked decrease in the insulin-like growth factor (IGF)-I receptor levels leading to a reduced IGF-I-mediated mitogenesis. Moreover, the percentage of BrdUrd-positive epithelial nuclei was decreased by 48%. β-Catenin immunoreactivity was significantly decreased and the percentage of signal transducer and activator of transcription 5a (stat5a)-positive mammary epithelial cells was increased by 2-fold in Wnt-1 mice overexpressing PTEN. The present study shows that PTEN can partially inhibit the Wnt-1-induced mammary tumorigenesis in early neoplastic stages by blocking the AKT pathway and by reducing the IGF-I receptor levels in mammary gland. This study identifies the PTEN as a therapeutic target for the treatment of mammary cancer and presumably other types of cancer.
AB - The tumor suppressor phosphatase and tensin homologue (PTEN) is involved in cell proliferation, adhesion, and apoptosis. PTEN overexpression in mammary epithelium leads to reduced cell number and impaired differentiation and secretion. In contrast, overexpression of the proto-oncogene Wnt-1 in mammary epithelium leads to mammary hyperplasia and subsequently focal mammary tumors. To explore the possibility that PTEN intersects with Wnt-induced tumorigenesis, mice that ectopically express PTEN and Wnt-1 in mammary epithelium were generated. PTEN overexpression resulted in an 11% reduction of Wnt-1-induced tumors within a 12-month period and the onset of tumors was delayed from an average of 5.9 to 7.7 months. The rate of tumor growth, measured from 0.5 cm diameter until the tumors reached 1.0 cm diameter, was increased from 8.4 days in Wnt-1 mice to 17.7 days in Wnt-1 mice overexpressing PTEN. Here we show for the first time in vivo that overexpression of PTEN in the Wnt-1 transgenic mice resulted in a marked decrease in the insulin-like growth factor (IGF)-I receptor levels leading to a reduced IGF-I-mediated mitogenesis. Moreover, the percentage of BrdUrd-positive epithelial nuclei was decreased by 48%. β-Catenin immunoreactivity was significantly decreased and the percentage of signal transducer and activator of transcription 5a (stat5a)-positive mammary epithelial cells was increased by 2-fold in Wnt-1 mice overexpressing PTEN. The present study shows that PTEN can partially inhibit the Wnt-1-induced mammary tumorigenesis in early neoplastic stages by blocking the AKT pathway and by reducing the IGF-I receptor levels in mammary gland. This study identifies the PTEN as a therapeutic target for the treatment of mammary cancer and presumably other types of cancer.
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U2 - 10.1158/0008-5472.CAN-05-0181
DO - 10.1158/0008-5472.CAN-05-0181
M3 - Article
C2 - 16061670
AN - SCOPUS:23044480599
SN - 0008-5472
VL - 65
SP - 6864
EP - 6873
JO - Cancer Research
JF - Cancer Research
IS - 15
ER -