p73 has significant homology to p53. However, tumor-associated up-regulation of p73 and genetic data from human tumors and p73-deficient mice exclude a classical Knudson-type tumor suppressor role. We report that the human TP73 gene generates an NH2 terminally truncated isoform. ΔNp73 derives from an alternative promoter in intron 3 and lacks the transactivation domain of full-length TAp73. ΔNp73 is frequently overexpressed in a variety of human cancers, but not in normal tissues. ΔNp73 acts as a potent transdominant inhibitor of wild-type p53 and transactivation-competent TAp73. ΔNp73 efficiently counteracts transactivation function, apoptosis, and growth suppression mediated by wild-type p53 and TAp73, and confers drug resistance to wild-type p53 harboring tumor cells. Conversely, down-regulation of endogenous ΔNp73 levels by antisense methods alleviates its suppressive action and enhances p53- and TAp73-mediated apoptosis. ΔNp73 is complexed with wild-type p53, as demonstrated by coimmunoprecipitation from cultured cells and primary tumors. Thus, ΔNp73 mediates a novel inactivation mechanism of p53 and TAp73 via a dominant-negative family network. Deregulated expression of ΔNp73 can bestow oncogenic activity upon the TP73 gene by functionally inactivating the suppressor action of p53 and TAp73. This trait might be selected for in human cancers.
Purpose There is a growing demand for BRCA1/ 2 mutation ( BRCAm) testing in patients with ovarian cancer; however, the limited number of genetic counselors presents a potential barrier. To facilitate more widespread BRCAm testing in ovarian cancer, pretest counseling by the oncology team could shorten testing turnaround times and ease the pressure on genetic counselors. Patients and Methods The prospective, observational Evaluating a Streamlined Onco-genetic BRCA Testing and Counseling Model Among Patients With Ovarian Cancer (ENGAGE) study evaluated a streamlined, oncologist-led BRCAm testing pathway. The analysis population comprised 700 patients with ovarian cancer at 26 sites in the United States, Italy, and Spain. The primary objectives were to assess turnaround time and, using questionnaires, to evaluate stakeholder satisfaction (patients, oncologists, and geneticists or genetic counselors) with the oncologist-led BRCAm testing pathway. Results The median overall turnaround time was 9.1 weeks (range, 0.9 to 37.1 weeks), with median turnaround times in the United States, Italy, and Spain of 4.1 weeks (range, 0.9 to 37.1 weeks), 20.4 weeks (range, 2.9 to 35.4 weeks), and 12.0 weeks (range, 2.0 to 36.7 weeks), respectively. Patient satisfaction with the oncologist-led BRCAm testing pathway was high, with > 99% of patients expressing satisfaction with pre- and post- BRCAm test counseling. Oncologist satisfaction with the BRCAm testing pathway was also high, with > 80% agreeing that the process for performing BRCAm testing worked well and that counseling patients on BRCAm testing was an efficient use of their time. Oncologists expressed higher levels of satisfaction with the BRCAm testing pathway than did geneticists or genetic counselors. Conclusion The results of the ENGAGE study demonstrate that an oncologist-led BRCAm testing process is feasible in ovarian cancer. Development of local BRCAm testing guidelines similar to the one used in this study could allow faster treatment decisions and better use of resources in the management of patients with ovarian cancer.
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