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Mechanisms of PTEN loss in cancer: It's all about diversity
Virginia Álvarez-Garcia1, Yasmine Tawil1, Helen M Wise1
1Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
Abstract:
PTEN is a phosphatase which metabolises PIP3, the lipid product of PI 3-Kinase, directly opposing the activation of the oncogenic PI3K/AKT/mTOR signalling network. Accordingly, loss of function of the PTEN tumour suppressor is one of the most common events observed in many types of cancer. Although the mechanisms by which PTEN function is disrupted are diverse, the most frequently observed events are deletion of a single gene copy of PTEN and gene silencing, usually observed in tumours with little or no PTEN protein detectable by immunohistochemistry. Accordingly, with the exceptions of glioblastoma and endometrial cancer, mutations of the PTEN coding sequence are uncommon (<10%) in most types of cancer. Here we review the data relating to PTEN loss in seven common tumour types and discuss mechanisms of PTEN regulation, some of which appear to contribute to reduced PTEN protein levels in cancers.
Insights
Loss of the PTEN tumor suppressor gene is common in many cancers, often due to gene deletion or silencing rather than mutation. This review examines PTEN loss mechanisms across seven common tumor types.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- PTEN (phosphatase and tensin homolog) is a crucial tumor suppressor.
- It counteracts the PI3K/AKT/mTOR pathway, a key driver in oncogenesis.
- Loss of PTEN function is a frequent event in various cancers.
Purpose of the Study:
- To review PTEN loss mechanisms in seven common cancer types.
- To discuss regulatory mechanisms contributing to reduced PTEN protein levels in cancer.
Main Methods:
- Literature review of PTEN alterations in common cancers.
- Analysis of PTEN gene deletion, silencing, and mutation frequencies.
- Examination of PTEN protein expression via immunohistochemistry.
Main Results:
- PTEN loss is prevalent, primarily through single-copy deletion or gene silencing.
- Mutations in the PTEN coding sequence are infrequent (<10%) in most cancers, except glioblastoma and endometrial cancer.
- Reduced PTEN protein levels are observed in tumors with little to no detectable PTEN.
Conclusions:
- PTEN loss is a significant oncogenic event driven by genetic and epigenetic alterations.
- Understanding PTEN regulation is key to explaining its reduced levels in cancer.
- Further research into PTEN's role can inform cancer therapy development.