Cyclin D1 overexpression induces global transcriptional downregulation in lymphoid neoplasms
Robert Albero, … , Elías Campo, Pedro Jares
Robert Albero, … , Elías Campo, Pedro Jares
Published July 10, 2018
Citation Information: J Clin Invest. 2018;128(9):4132-4147. https://doi.org/10.1172/JCI96520.
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Research Article Cell biology

Cyclin D1 overexpression induces global transcriptional downregulation in lymphoid neoplasms

Abstract

Cyclin D1 is an oncogene frequently overexpressed in human cancers that has a dual function as cell cycle and transcriptional regulator, although the latter is widely unexplored. Here, we investigated the transcriptional role of cyclin D1 in lymphoid tumor cells with cyclin D1 oncogenic overexpression. Cyclin D1 showed widespread binding to the promoters of most actively transcribed genes, and the promoter occupancy positively correlated with the transcriptional output of targeted genes. Despite this association, the overexpression of cyclin D1 in lymphoid cells led to a global transcriptional downmodulation that was proportional to cyclin D1 levels. This cyclin D1–dependent global transcriptional downregulation was associated with a reduced nascent transcription and an accumulation of promoter-proximal paused RNA polymerase II (Pol II) that colocalized with cyclin D1. Concordantly, cyclin D1 overexpression promoted an increase in the Poll II pausing index. This transcriptional impairment seems to be mediated by the interaction of cyclin D1 with the transcription machinery. In addition, cyclin D1 overexpression sensitized cells to transcription inhibitors, revealing a synthetic lethality interaction that was also observed in primary mantle cell lymphoma cases. This finding of global transcriptional dysregulation expands the known functions of oncogenic cyclin D1 and suggests the therapeutic potential of targeting the transcriptional machinery in cyclin D1–overexpressing tumors.

Authors

Robert Albero, Anna Enjuanes, Santiago Demajo, Giancarlo Castellano, Magda Pinyol, Noelia García, Cristina Capdevila, Guillem Clot, Helena Suárez-Cisneros, Mariko Shimada, Kennosuke Karube, Mónica López-Guerra, Dolors Colomer, Sílvia Beà, José Ignacio Martin-Subero, Elías Campo, Pedro Jares

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Figure 4

Cyclin D1 overexpression results in a reduction in the total RNA content in malignant lymphoid cells.

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Cyclin D1 overexpression results in a reduction in the total RNA content...
(A) Cyclin D1 protein in JVM13-control (JVM13-ctrl), JVM13-D1, and JVM13-D1T286A cells. α-Tubulin was used as loading control. (B) Total RNA content extracted from 106 cells. Results are shown relative to the control (mean ± SEM, n = 9). *P < 0.05, Student’s t test. (C) RNA quantification by pyronin Y staining in JVM13 inducible cell lines. Only cells in G1 phase were analyzed. Left panel: FACS profile of a representative experiment. Right panel: Bar graph displaying the pyronin Y mean signal. Results are shown relative to the control (mean ± SEM, n = 3). *P < 0.05, **P < 0.01, Student’s t test. (D) Cyclin D1 expression in control (shCtrl) and cyclin D1–depleted (shCycD1 #1 and #2) GRANTA-519 cells. α-Tubulin was used as loading control. (E) Total RNA content in cyclin D1–depleted GRANTA-519 cells as in A. Results are shown relative to the control (mean ± SEM, n = 8), **P < 0.01, ***P < 0.001, Student’s t test. (F) RNA quantification by pyronin Y staining in control and cyclin D1–depleted GRANTA-519 cells as in B. Left and right panels as in C. Results are shown relative to the control (mean ± SEM, n = 4), **P < 0.01, ***P < 0.001, Student’s t test. (G) Correlation between cyclin D1 protein levels and pyronin Y staining in MCL cell lines and cell models. Mean ± SEM, n = 4; P = 4.77 × 10–4, mixed-effects models. (H) Pyronin Y intensity of 7 MM cell lines. The cell lines are represented by squares shaded according cyclin D1 levels. (I and J) Quantification of nuclear EU intensity after 24 hours of cyclin D1 induction in JVM13 cell models (n = 2) (I) or following cyclin D1 silencing in the GRANTA-519 cell line (n = 2) (J). **P < 0.01, ***P < 0.001, Student’s t test. Holm-Bonferroni correction for multiple comparisons was applied to B, C, E, and F.