nutlin-3a and Uterine-Neoplasms

Spontaneous cessation of growth is a frequent finding in uterine fibroids. Increasing evidence suggests an important role of cellular senescence in this growth control. Deciphering the underlying mechanisms of growth control that can be expected not only to shed light on the biology of the tumors but also to identify novel therapeutic targets.. We have analyzed uterine leiomyomas and matching normal tissue for the expression of p14Arf and used explants to see if reducing the MDM2 activity using the small-molecule inhibitor nutlin-3 can induce p53 and activate genes involved in senescence and/or apoptosis. For these studies quantitative real-time RT-PCR, Western blots, and immunohistochemistry were used. Statistical analyses were performed using the student's t test.. An in depth analysis of 52 fibroids along with matching myometrium from 31 patients revealed in almost all cases a higher expression of p14Arf in the tumors than in the matching normal tissue. In tissue explants, treatment with the MDM2 inhibitor nutlin-3 induced apoptosis as well as senescence as revealed by a dose-dependent increase of the expression of BAX as well as of p21, respectively. Simultaneously, the expression of the proliferation marker Ki-67 drastically decreased. Western-blot analysis identified an increase of the p53 level as the most likely reason for the increased activity of its downstream markers BAX and p21. Because as a rule fibroids express much higher levels of p14Arf, a major negative regulator of MDM2, than matching myometrium it was then analyzed if fibroids are more sensitive against nutlin-3 treatment than matching myometrium. We were able to show that in most fibroids analyzed a higher sensibility than that of matching myometrium was noted with a corresponding increase of the p53 immunopositivity of the fibroid samples compared to those from myometrium.. The results show that uterine fibroids represent a cell population of advanced cellular age compared to matching myometrium. Moreover, the data point to members of the p53-network as to potential novel therapeutic targets for the treatment of uterine fibroids.

Topics: Adult; Aged; Apoptosis; Cellular Senescence; Female; Humans; Imidazoles; Leiomyoma; Middle Aged; Myometrium; Piperazines; Proto-Oncogene Proteins c-mdm2; Tumor Suppressor Protein p14ARF; Tumor Suppressor Protein p53; Uterine Neoplasms

To address the influence of genes involved in stem cell self-renewal and senescence on the growth of leiomyoma cells in vitro and to explore possible therapeutic implications of a targeted disruption of the p53-murine double minute 2 (MDM2) interaction.. Gene expression studies (qRT-PCR) of fibroid tissue and cells; β-galactosidase stain and qRT-PCR after antagonizing MDM2.. In fibroid cells, expression of HMGA2 decreased with passaging while that of p14(Arf) increased. Expression of these markers significantly positively, and negatively, respectively, influenced proliferation. Administration of nutlin-3, an MDM2 antagonist, induced cellular senescence and increased the expression of BAX. This, along with a significant correlation between p14(Arf) and BAX expression in native fibroids, suggests that p14(Arf) triggers senescence as well as apoptosis.. p14(Arf) and HMGA2 seem to play a pivotal role in controlling the growth of fibroid cells. Antagonizing MDM2 induces senescence, as well as apoptosis, and may offer a chance to treat fibroids.

Topics: Apoptosis; beta-Galactosidase; Biomarkers, Tumor; Cell Line, Transformed; Cell Proliferation; Cellular Senescence; Female; Gene Expression Regulation, Neoplastic; HMGA2 Protein; Humans; Imidazoles; Leiomyoma; Piperazines; Proto-Oncogene Proteins c-mdm2; RNA, Small Interfering; Tumor Suppressor Protein p14ARF; Uterine Neoplasms