| 1. |
- Ehlén, Åsa, et al.
(författare)
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Expression of the RNA-binding protein RBM3 is associated with a favourable prognosis and cisplatin sensitivity in epithelial ovarian cancer
- 2010
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Ingår i: Journal of Translational Medicine. - : Springer Science and Business Media LLC. - 1479-5876. ; 8, s. 78-
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Tidskriftsartikel (refereegranskat)abstract
- Background: We recently demonstrated that increased expression of the RNA-binding protein RBM3 is associated with a favourable prognosis in breast cancer. The aim of this study was to examine the prognostic value of RBM3 mRNA and protein expression in epithelial ovarian cancer (EOC) and the cisplatin response upon RBM3 depletion in a cisplatin-sensitive ovarian cancer cell line. Methods: RBM3 mRNA expression was analysed in tumors from a cohort of 267 EOC cases (Cohort I) and RBM3 protein expression was analysed using immunohistochemistry (IHC) in an independent cohort of 154 prospectively collected EOC cases (Cohort II). Kaplan Meier analysis and Cox proportional hazards modelling were applied to assess the relationship between RBM3 and recurrence free survival (RFS) and overall survival (OS). Immunoblotting and IHC were used to examine the expression of RBM3 in a cisplatin-resistant ovarian cancer cell line A2780-Cp70 and its cisplatin-responsive parental cell line A2780. The impact of RBM3 on cisplatin response in EOC was assessed using siRNA-mediated silencing of RBM3 in A2780 cells followed by cell viability assay and cell cycle analysis. Results: Increased RBM3 mRNA expression was associated with a prolonged RFS (HR = 0.64, 95% CI = 0.47-0.86, p = 0.003) and OS (HR = 0.64, 95% CI = 0.44-0.95, p = 0.024) in Cohort I. Multivariate analysis confirmed that RBM3 mRNA expression was an independent predictor of a prolonged RFS, (HR = 0.61, 95% CI = 0.44-0.84, p = 0.003) and OS (HR = 0.62, 95% CI = 0.41-0.95; p = 0.028) in Cohort I. In Cohort II, RBM3 protein expression was associated with a prolonged OS (HR = 0.53, 95% CI = 0.35-0.79, p = 0.002) confirmed by multivariate analysis (HR = 0.61, 95% CI = 0.40-0.92, p = 0.017). RBM3 mRNA and protein expression levels were significantly higher in the cisplatin sensitive A2780 cell line compared to the cisplatin resistant A2780-Cp70 derivative. siRNA-mediated silencing of RBM3 expression in the A2780 cells resulted in a decreased sensitivity to cisplatin as demonstrated by increased cell viability and reduced proportion of cells arrested in the G2/M-phase. Conclusions: These data demonstrate that RBM3 expression is associated with cisplatin sensitivity in vitro and with a good prognosis in EOC. Taken together these findings suggest that RBM3 may be a useful prognostic and treatment predictive marker in EOC.
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| 2. |
- Ehlén, Å., et al.
(författare)
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RBM3-regulated genes promote DNA integrity and affect clinical outcome in epithelial ovarian cancer
- 2011
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Ingår i: Translational Oncology. - : Elsevier BV. - 1936-5233 .- 1944-7124. ; 4:4, s. 202-211
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Tidskriftsartikel (refereegranskat)abstract
- The RNA-binding motif protein 3 (RBM3) was initially discovered as a putative cancer biomarker based on its differential expression in various cancer forms in the Human Protein Atlas (HPA). We previously reported an association between high expression of RBM3 and prolonged survival in breast and epithelial ovarian cancer (EOC). Because the function of RBM3 has not been fully elucidated, the aim of this study was to use gene set enrichment analysis to identify the underlying biologic processes associated with RBM3 expression in a previously analyzed EOC cohort (cohort 1, n = 267). This revealed an association between RBM3 expression and several cellular processes involved in the maintenance of DNA integrity. RBM3-regulated genes were subsequently screened in the HPA to select for putative prognostic markers, and candidate proteins were analyzed in the ovarian cancer cell line A2780, whereby an up-regulation of Chk1, Chk2, and MCM3 was demonstrated in siRBM3-treated cells compared to controls. The prognostic value of these markers was assessed at the messenger RNA level in cohort 1 and the protein level in an independent EOC cohort (cohort 2, n = 154). High expression levels of Chk1, Chk2, and MCM3 were associated with a significantly shorter survival in both cohorts, and phosphorylated Chk2 was an adverse prognostic marker in cohort 2. These results uncover a putative role for RBM3 in DNA damage response, which might, in part, explain its cisplatin-sensitizing properties and good prognostic value in EOC. Furthermore, it is demonstrated that Chk1, Chk2, and MCM3 are poor prognostic markers in EOC.
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| 3. |
- Ehlén, Åsa, et al.
(författare)
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Tumors with non-functional RB1 are killed by reduced gamma-tubulin levels.
- 2012
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 287:21, s. 17241-17247
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Tidskriftsartikel (refereegranskat)abstract
- In various tumors inactivation of growth control is achieved by interfering with the RB1 signaling pathway. Here, we describe that RB1 and γ tubulin proteins moderate each other's expression by binding to their respective gene promoters. Simultaneous reduction of RB1 and γ tubulin protein levels result in an E2F1-dependent upregulation of apoptotic genes such as caspase 3. We report that in various tumors types, there is an inverse correlation between the expression levels of γ tubulin and RB1 and that in tumor cell lines with a non-functioning RB1, reduction of γ tubulin protein levels leads to induction of apoptosis. Thus, the RB1/γ tubulin signal network can be considered as a new target for cancer treatment.
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| 4. |
- Eklund, Greta, et al.
(författare)
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Nuclear localization of {gamma}-tubulin affects E2F transcriptional activity and S-phase progression.
- 2011
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Ingår i: FASEB Journal. - : Wiley. - 1530-6860 .- 0892-6638. ; 25:11, s. 3815-3827
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Tidskriftsartikel (refereegranskat)abstract
- We show that the centrosome- and microtubule-regulating protein γ-tubulin interacts with E2 promoter binding factors (E2Fs) to modulate E2F transcriptional activity and thereby control cell cycle progression. γ-Tubulin contains a C-terminal signal that results in its translocation to the nucleus during late G(1) to early S phase. γ-Tubulin mutants showed that the C terminus interacts with the transcription factor E2F1 and that the E2F1-γ-tubulin complex is formed during the G(1)/S transition, when E2F1 is transcriptionally active. Furthermore, E2F transcriptional activity is altered by reduced expression of γ-tubulin or by complex formation between γ-tubulin and E2F1, E2F2, or E2F3, but not E2F6. In addition, the γ-tubulin C terminus encodes a DNA-binding domain that interacts with E2F-regulated promoters, resulting in γ-tubulin-mediated transient activation of E2Fs. Thus, we report a novel mechanism regulating the activity of E2Fs, which can help explain how these proteins affect cell cycle progression in mammalian cells.-Höög, G., Zarrizi, R., von Stedingk, K., Jonsson, K., Alvarado-Kristensson, M. Nuclear localization of γ-tubulin affects E2F transcriptional activity and S-phase progression.
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| 5. |
- Eklund, Greta, et al.
(författare)
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The nuclear localization of γ-tubulin is regulated by SadB-mediated phosphorylation.
- 2014
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 289:31, s. 21360-21373
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Tidskriftsartikel (refereegranskat)abstract
- γ-tubulin is an important cell division regulator that arranges microtubule assembly and mitotic spindle formation. Cytosolic γ-tubulin nucleates α- and β-tubulin in a growing microtubule by forming the ring-shaped protein complex γTuRC. Nuclear γ-tubulin also regulates S-phase progression by moderating the activities of E2Fs. The mechanism that regulates localization of γ-tubulin is currently unknown. Here, we describe that the human Ser/Thr kinase SadB short localizes to chromatin and centrosomes. We found that SadB-mediated phosphorylation of γ-tubulin on Ser 385 triggered formation of chromatin associated γ-tubulin complexes that moderates gene expression. In this way, the C terminal region of γ-tubulin regulates S-phase progression. In addition, chromatin levels of γ-tubulin were decreased by reduction of SadB levels or expression of a non-phosphorylatable Ala-385-γ-tubulin, but were enhanced by expression of SadB, wild-type γ-tubulin, or a phosphomimetic Asp-385-γ-tubulin mutant. Our results demonstrate that SadB kinases regulate the cellular localization of γ-tubulin and thereby control S-phase progression.
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