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Updated: Apr 23, 2026
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
A p53/ARF-dependent anticancer barrier activates senescence and blocks tumorigenesis without impacting apoptosis
Vidya C Sinha1, Lan Qin2, Yi Li3
1Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas. Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas.
Unlabelled:
In response to oncogene activation and oncogene-induced aberrant proliferation, mammalian cells activate apoptosis and senescence, usually via the p53-ARF tumor-suppressor pathway. Apoptosis is a known barrier to cancer and is usually downregulated before full malignancy, but senescence as an anticancer barrier is controversial due to its presence in the tumor environment. In addition, senescence may aid cancer progression via releasing senescence-associated factors that instigate neighboring tumor cells. Here, it is demonstrated that apoptosis unexpectedly remains robust in ErbB2 (ERBB2/HER2)-initiated mammary early lesions arising in adult mice null for either p53 or ARF. These early lesions, however, downregulate senescence significantly. This diminished senescence response is associated with accelerated progression to cancer in ARF-null mice compared with ARF-wild-type mice. Thus, the ARF-p53 pathway is dispensable for the apoptosis anticancer barrier in the initiation of ErbB2 breast cancer, the apoptosis barrier alone cannot halt mammary tumorigenesis, and senescence is a key barrier against carcinogenesis.
Implications:
Findings in this relevant mouse model of HER2-driven breast cancer suggest that effective prevention relies upon preserving both ARF/p53-independent apoptosis and ARF/p53-dependent senescence.
Insights
Apoptosis remains strong in early HER2-driven breast cancer, even without the ARF-p53 pathway. However, reduced senescence accelerates cancer progression, highlighting senescence as a crucial barrier against carcinogenesis.
Area of Science:
- Oncology
- Cellular Biology
- Cancer Research
Background:
- Mammalian cells activate apoptosis and senescence via the p53-ARF tumor-suppressor pathway in response to oncogene activation.
- While apoptosis is a known cancer barrier, its role alongside senescence in early-stage cancer, particularly HER2-driven breast cancer, remains under investigation.
- Senescence's role is debated, as it can act as a barrier but also potentially promote cancer progression through senescence-associated secretory phenotypes.
Purpose of the Study:
- To investigate the roles of apoptosis and senescence as anticancer barriers in early-stage, ErbB2 (ERBB2/HER2)-initiated mammary lesions in mice.
- To determine if the p53-ARF pathway is essential for apoptosis and senescence to function as barriers in this model.
- To assess the impact of diminished senescence on cancer progression in the context of HER2-driven mammary tumors.
Main Methods:
- Utilized a mouse model of ErbB2-initiated mammary lesions.
- Compared apoptosis and senescence responses in mice with and without p53 or ARF.
- Assessed the rate of cancer progression in relation to senescence levels.
Main Results:
- Apoptosis was robust in early ErbB2-initiated mammary lesions, irrespective of p53 or ARF status.
- Senescence was significantly downregulated in these early lesions.
- Diminished senescence correlated with accelerated cancer progression, particularly in ARF-null mice.
Conclusions:
- The p53-ARF pathway is dispensable for maintaining apoptosis as an early anticancer barrier in ErbB2-driven breast cancer initiation.
- Apoptosis alone is insufficient to halt mammary tumorigenesis.
- Senescence functions as a critical barrier against carcinogenesis, and its preservation is vital for effective cancer prevention.
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