Research ArticleCancer Biology

PTEN Deficiency in Endometrioid Endometrial Adenocarcinomas Predicts Sensitivity to PARP Inhibitors

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Science Translational Medicine  13 Oct 2010:
Vol. 2, Issue 53, pp. 53ra75
DOI: 10.1126/scitranslmed.3001538

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Putting PARP Inhibitors on the Map

Targeted drug therapies that interfere with specific oncoproteins in certain cancers like lung cancer and chronic myeloid leukemia have shown great promise, but designing targeted therapies for tumors that have lost a tumor suppressor protein has proved challenging. Building on the idea of targeting a complementary gene or pathway in tumors with an inactive tumor suppressor protein, Dedes and colleagues set out to tackle endometrial cancer. This cancer is the fourth most common malignancy in women and is very difficult to treat particularly in the later stages of the disease. The authors demonstrate that endometrial cancer cell lines that lack the tumor suppressor protein PTEN show defects in the repair of DNA damage and are consequently very sensitive to drugs that block poly(ADP) ribose polymerase (PARP), an enzyme critical for DNA repair. Given that such PARP inhibitors are currently in late-stage clinical trials for treating breast and ovarian cancer, this study opens the door to using PARP inhibitors for treating endometrial cancer.

First the authors demonstrated that the majority of endometrial cancer cell lines that they analyzed indeed had lost the PTEN tumor suppressor protein. PTEN both regulates a major growth signaling pathway in cells (the PI3K-AKT-mTOR pathway) and has recently been shown to be important for maintaining genomic stability. Dedes and co-workers then showed that loss of PTEN rendered endometrial cancer cells unable to repair DNA double-strand breaks induced by ionizing radiation. Other types of tumors that cannot repair DNA damage, such as breast and ovarian cancer cells carrying mutations in the BRCA1 and BRCA2 genes, are acutely sensitive to PARP inhibitors. Dedes et al. reasoned that endometrial cancer cells lacking PTEN may also be sensitive to these drugs. This is exactly what they found when they treated their endometrial cancer cell lines with the potent PARP inhibitor, KU0058948. To demonstrate that it was loss of PTEN that rendered the cancer cells highly sensitive to the drug, they re-expressed PTEN in endometrial cancer cell lines lacking this tumor suppressor protein and demonstrated that these cancer cell lines were now able to repair DNA damage and thus were resistant to treatment with the PARP inhibitor. Given that 80% of endometrial cancers lack PTEN, treatment with PARP inhibitors may be an effective way to treat this disease.

Footnotes

  • Citation: K. J. Dedes, D. Wetterskog, A. M. Mendes-Pereira, R. Natrajan, M. B. Lambros, F. C. Geyer, R. Vatcheva, K. Savage, A. Mackay, C. J. Lord, A. Ashworth, J. S. Reis-Filho, PTEN deficiency in endometrioid endometrial adenocarcinomas predicts sensitivity to PARP inhibitors. Sci. Transl. Med. 2, 53ra75 (2010).

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