Abstract
BackgroundSpontaneous 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.MethodsWe 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.ResultsAn 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.ConclusionsThe 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.
Highlights
Spontaneous cessation of growth is a frequent finding in uterine fibroids
We have used tissue explants taken from leiomyomas and matching myometrium to analyze the effects of an MDM2 antagonist and possible different sensitivities of the fibroids and their matching tissue of origin
To see if the increased expression of the senescence and apoptotic markers that was noted after treatment of the explants with nutlin-3 was due to an elevated level of p53 explants of case 0700-1 treated with 30 μM and 50 μM nutlin-3, respectively, for 72 h were used for immunoblot analyses
Summary
Spontaneous cessation of growth is a frequent finding in uterine fibroids. Increasing evidence suggests an important role of cellular senescence in this growth control. 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. Compared to matching myometrial tissue the myomas display a significantly higher expression of one of the genes of the senescence associated Ink4a/Arf locus i.e. p14Arf [7] It is not clear yet if this elevated expression solely results from an enhanced proliferative activity of the fibroid compared to its tissue of origin or if the same oncogenic stimuli triggering the leiomyoma growth do simultaneously stimulate p14Arf as an oncogene-induced senescence-like mechanism. We have used tissue explants taken from leiomyomas and matching myometrium to analyze the effects of an MDM2 antagonist and possible different sensitivities of the fibroids and their matching tissue of origin
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
