Dmp1α inhibits HER2/neu-induced mammary tumorigenesis
Elizabeth A Fry1, Pankaj Taneja, Dejan Maglic
1Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America ; Department of Cancer Biology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America.
Abstract:
Our recent study shows a pivotal role of Dmp1 in quenching hyperproliferative signals from HER2 to the Arf-p53 pathway as a safety mechanism to prevent breast carcinogenesis. To directly demonstrate the role of Dmp1 in preventing HER2/neu-driven oncogenic transformation, we established Flag-Dmp1α transgenic mice (MDTG) under the control of the mouse mammary tumor virus (MMTV) promoter. The mice were viable but exhibited poorly developed mammary glands with markedly reduced milk production; thus more than half of parous females were unable to support the lives of new born pups. The mammary glands of the MDTG mice had very low Ki-67 expression but high levels of Arf, Ink4a, p53, and p21(Cip1), markers of senescence and accelerated aging. In all strains of generated MDTG;neu mice, tumor development was significantly delayed with decreased tumor weight. Tumors from MDTG;neu mice expressed Flag-Dmp1α and Ki-67 in a mutually exclusive fashion indicating that transgenic Dmp1α prevented tumor growth in vivo. Genomic DNA analyses showed that the Dmp1α transgene was partially lost in half of the MDTG;neu tumors, and Western blot analyses showed Dmp1α protein downregulation in 80% of the cases. Our data demonstrate critical roles of Dmp1 in preventing mammary tumorigenesis and raise the possibility of treating breast cancer by restoring Dmp1α expression.
Insights
Dmp1 plays a crucial role in preventing breast cancer by regulating the HER2 pathway. Restoring Dmp1α expression may offer a new therapeutic strategy for breast cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Dmp1 acts as a tumor suppressor by inhibiting hyperproliferative signals.
- The HER2 pathway is frequently activated in breast cancer, driving oncogenesis.
- Understanding Dmp1's role in HER2-driven cancer is crucial for developing new therapies.
Purpose of the Study:
- To investigate the role of Dmp1 in preventing HER2/neu-driven breast cancer.
- To establish and characterize transgenic mouse models expressing Dmp1α.
Main Methods:
- Generation of Flag-Dmp1α transgenic mice (MDTG) using the MMTV promoter.
- Analysis of mammary gland development, senescence markers (Arf, Ink4a, p53, p21), and proliferation marker (Ki-67).
- Evaluation of tumor development, weight, and transgene expression in MDTG;neu mice.
Main Results:
- MDTG mice showed impaired mammary gland development and reduced milk production.
- MDTG mice exhibited markers of senescence and aging, with low proliferation.
- MDTG;neu mice displayed significantly delayed tumor development and reduced tumor weight, with Dmp1α expression inversely correlated with Ki-67.
- Transgene loss and protein downregulation were observed in MDTG;neu tumors.
Conclusions:
- Dmp1 plays a critical role in preventing mammary tumorigenesis by quenching HER2-driven signals.
- Transgenic Dmp1α expression delays tumor growth in vivo.
- Restoring Dmp1α expression presents a potential therapeutic strategy for breast cancer.
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