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Fibroid explants reveal a higher sensitivity against MDM2-inhibitor nutlin-3 than matching myometrium
Dominique N Markowski1, Burkhard M Helmke, Arlo Radtke
1Center of Human Genetics, University of Bremen, Leobener Strasse ZHG, D-28359 Bremen, Germany.
Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
Insights
Uterine fibroids show higher p14Arf expression and increased sensitivity to MDM2 inhibition, indicating cellular senescence. Targeting the p53 network offers potential new treatments for fibroids.
Area of Science:
- Gynecology
- Oncology
- Cell Biology
Background:
- Spontaneous growth cessation is common in uterine fibroids.
- Cellular senescence plays a key role in uterine fibroid growth control.
- Understanding fibroid growth mechanisms can reveal therapeutic targets.
Purpose of the Study:
- To investigate the role of p14Arf and MDM2 in uterine fibroid growth.
- To explore the potential of MDM2 inhibition for fibroid treatment.
- To analyze fibroid sensitivity to MDM2 inhibition.
Main Methods:
- Analysis of p14Arf expression in uterine fibroids and myometrium.
- Treatment of tissue explants with nutlin-3 (MDM2 inhibitor).
- Quantitative real-time RT-PCR, Western blots, and immunohistochemistry were employed.
Main Results:
- Uterine fibroids exhibited higher p14Arf expression than matching myometrium.
- Nutlin-3 treatment induced apoptosis and senescence, decreasing proliferation marker Ki-67.
- Fibroids showed increased sensitivity to nutlin-3, with elevated p53 activity.
Conclusions:
- Uterine fibroids represent cells of advanced cellular age compared to myometrium.
- The p53 network is a promising target for uterine fibroid therapy.
- MDM2 inhibition demonstrates therapeutic potential for uterine fibroids.
