Skip to Main content Skip to Navigation
Theses

Epissage alternatif des phosphatases CDC25 dans le cancer du sein : expression des différents variants dans des modèles cellulaires et tissulaires de cancer mammaire et régulation en conditions de stress génotoxique

Abstract : CDC25 phosphatases play an important role in cell cycle progression. Moreover, an overexpression of CDC25 was reported in numerous cancers, particularly in breast cancer, and is often correlated with a poor prognosis. CDC25 are represented by three isoforms: A, B and C encoded by distinct genes, all three submitted to an alternative splicing mechanism. Few studies suggested that some CDC25 splicing variants could be more involved in cancers than others, but no such study has so far been conducted in breast cancer.The first aspect of this study, referred to clinic, consists in the evaluation of different CDC25 splicing variants proportion in breast cancer, from the perspective of developing a new prognostic tool. This study was performed on two models. On the one hand, several mammary cancerous cell lines were characterized concerning CDC25 variants expression thanks to the development of a novel quantitative RT-PCR method. Interestingly, we observed an overexpression of A2 and B2 transcripts and an increase of C5/C1 ratio in multidrug resistant cell lines, suggesting a link between the expression of these variants and the resistance phenotype. On the other hand, this study was extended to the determination of CDC25 variants expression in mammary tumoral tissues in comparison to that of matched peritumoral tissues. Quantitative PCR results obtained for the 75 pairs of tissues tested showed an overexpression of CDC25A in 64% of tumors, mainly due to A1 variant (69%); of CDC25B in 55% of tumors, partially linked to B1 and B2 variants expression (47% and 21% respectively); and of CDC25C in 75% of tumors, the C5 variant being clearly more involved than C1 (overexpression in 86% and 43% respectively). We have finally established correlations between CDC25 transcripts expression and some tumor characteristics, as the tumor grade and a lack of estrogens receptors for CDC25A and CDC25B and the tumor size for CDC25C.The second part of this project consists in a mechanistic study regarding the regulation of CDC25 splicing in DNA damage conditions. The treatment of several breast cancer cell lines with different genotoxic agents (doxorubicin, camptothecin, etoposide, cisplatin and tert-butyl hydroperoxide) induces a modification of CDC25C splicing profile, consisting in a large increase in C5 variant proportion compared to that of C1 (both at mRNA and protein levels). This regulation occurs during the early response to DNA damage, before the onset of apoptosis and is associated with a cell cycle arrest. We have also shown that this modulation of CDC25C splicing is dependent of ATM/ATR kinases and independent of p53. Finally, these results allowed to highlight an additional regulation pathway in the cellular response to genotoxic stress in breast cancer cells.
Complete list of metadata

https://hal.univ-lorraine.fr/tel-01749060
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 11:59:57 AM
Last modification on : Wednesday, June 17, 2020 - 4:22:06 PM
Long-term archiving on: : Friday, September 14, 2018 - 9:13:05 AM

File

Albert.Helene.SMZ1125.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01749060, version 1

Collections

Citation

Hélène Albert. Epissage alternatif des phosphatases CDC25 dans le cancer du sein : expression des différents variants dans des modèles cellulaires et tissulaires de cancer mammaire et régulation en conditions de stress génotoxique. Médecine humaine et pathologie. Université Paul Verlaine - Metz, 2011. Français. ⟨NNT : 2011METZ025S⟩. ⟨tel-01749060⟩

Share

Metrics

Record views

95

Files downloads

140