Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC

Abstract Background Dysregulation of alternative splicing plays a pivotal role in tumorigenesis and metastasis in triple-negative breast cancer (TNBC). Serine/arginine-rich (SR) proteins, essential components of the spliceosome, undergo phosphorylation by Cdc2-like kinase (CLK). Here we explored the...

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Main Authors: Nasi Liu, Jurjun J. S. van der Velde, Sherien Ramdjielal, Esmee Koedoot, Nila K. van Overbeek, Daisy Batenburg, Alfred C. O. Vertegaal, Bob van de Water, Sylvia E. Le Dévédec
Format: Article
Language:English
Published: BMC 2025-07-01
Series:Breast Cancer Research
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Online Access:https://doi.org/10.1186/s13058-025-02091-w
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author Nasi Liu
Jurjun J. S. van der Velde
Sherien Ramdjielal
Esmee Koedoot
Nila K. van Overbeek
Daisy Batenburg
Alfred C. O. Vertegaal
Bob van de Water
Sylvia E. Le Dévédec
author_facet Nasi Liu
Jurjun J. S. van der Velde
Sherien Ramdjielal
Esmee Koedoot
Nila K. van Overbeek
Daisy Batenburg
Alfred C. O. Vertegaal
Bob van de Water
Sylvia E. Le Dévédec
author_sort Nasi Liu
collection DOAJ
description Abstract Background Dysregulation of alternative splicing plays a pivotal role in tumorigenesis and metastasis in triple-negative breast cancer (TNBC). Serine/arginine-rich (SR) proteins, essential components of the spliceosome, undergo phosphorylation by Cdc2-like kinase (CLK). Here we explored the impact of pharmacological inhibition of CLK using a novel inhibitor, T-025, on the spliceosome complex and transcriptional responses in relation to cell proliferation and migration in TNBC. Methods We evaluated the anti-proliferative and anti-migratory efficacy of T-025 in a spectrum of TNBC cell lines. Fluorescent reporter cell lines and flowcytometry were used to determine the effect of T-025 on cell cycle. Deep RNA sequencing was performed to unravel the differentially expressed genes (DEGs) and alternatively spliced genes (ASGs) upon T-025 treatment. Pulldown/MS was used to uncover the impact of T-025 on SRSF7 interactome. Live-cell imaging and photobleaching experiments were conducted to determine the subnuclear localization of SRSF7-GFP and its dynamic mobility. Results T-025 exhibited a potent anti-proliferative effect in a spectrum of TNBC cell lines, particularly in highly proliferative cell lines. Treatment with T-025 induced cell cycle arrest in the G1-S phase, resulting in an increased proportion of aneuploidy cells and cells with 4 N DNA. T-025 significantly inhibited cell migration in highly migratory TNBC cell lines. Deep RNA sequencing uncovered numerous DEGs and ASGs upon T-025 treatment, which were significantly enriched in pathways related to cell division, RNA splicing and cell migration. Pulldown/MS showed that SRSF7 interacted more with nuclear-speckle-residing proteins, while less with RNA helicases and polymerases upon T-025 treatment. Enhanced interactions between SRSF7 and other phosphorylated SR proteins localized at nuclear speckles were also observed. Live-cell imaging indicated that T-025 treatment induced the accumulation of SRSF7-GFP at nuclear speckles and nuclear speckles’ enlargement, restricting its protein dynamic mobility. Conclusions CLK inhibition using T-025 leads to the accumulation of splicing factors at nuclear speckles and stalls their release to splicing sites, resulting in the RNA splicing reprogramming of a large number of genes involved in cell division, migration and RNA splicing. Our findings provide evidence that T-025 could be a promising therapeutic drug for TNBC patients.
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spelling doaj-art-d9fac136ab0d4996959bdadef28cb48d2025-08-24T11:58:46ZengBMCBreast Cancer Research1465-542X2025-07-0127112310.1186/s13058-025-02091-wPharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBCNasi Liu0Jurjun J. S. van der Velde1Sherien Ramdjielal2Esmee Koedoot3Nila K. van Overbeek4Daisy Batenburg5Alfred C. O. Vertegaal6Bob van de Water7Sylvia E. Le Dévédec8Division of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDepartment of Cell and Chemical Biology, Leiden University Medical CenterDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDepartment of Cell and Chemical Biology, Leiden University Medical CenterDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityDivision of Cell Systems and Drug Safety, Leiden Academic Centre for Drug Research, Leiden UniversityAbstract Background Dysregulation of alternative splicing plays a pivotal role in tumorigenesis and metastasis in triple-negative breast cancer (TNBC). Serine/arginine-rich (SR) proteins, essential components of the spliceosome, undergo phosphorylation by Cdc2-like kinase (CLK). Here we explored the impact of pharmacological inhibition of CLK using a novel inhibitor, T-025, on the spliceosome complex and transcriptional responses in relation to cell proliferation and migration in TNBC. Methods We evaluated the anti-proliferative and anti-migratory efficacy of T-025 in a spectrum of TNBC cell lines. Fluorescent reporter cell lines and flowcytometry were used to determine the effect of T-025 on cell cycle. Deep RNA sequencing was performed to unravel the differentially expressed genes (DEGs) and alternatively spliced genes (ASGs) upon T-025 treatment. Pulldown/MS was used to uncover the impact of T-025 on SRSF7 interactome. Live-cell imaging and photobleaching experiments were conducted to determine the subnuclear localization of SRSF7-GFP and its dynamic mobility. Results T-025 exhibited a potent anti-proliferative effect in a spectrum of TNBC cell lines, particularly in highly proliferative cell lines. Treatment with T-025 induced cell cycle arrest in the G1-S phase, resulting in an increased proportion of aneuploidy cells and cells with 4 N DNA. T-025 significantly inhibited cell migration in highly migratory TNBC cell lines. Deep RNA sequencing uncovered numerous DEGs and ASGs upon T-025 treatment, which were significantly enriched in pathways related to cell division, RNA splicing and cell migration. Pulldown/MS showed that SRSF7 interacted more with nuclear-speckle-residing proteins, while less with RNA helicases and polymerases upon T-025 treatment. Enhanced interactions between SRSF7 and other phosphorylated SR proteins localized at nuclear speckles were also observed. Live-cell imaging indicated that T-025 treatment induced the accumulation of SRSF7-GFP at nuclear speckles and nuclear speckles’ enlargement, restricting its protein dynamic mobility. Conclusions CLK inhibition using T-025 leads to the accumulation of splicing factors at nuclear speckles and stalls their release to splicing sites, resulting in the RNA splicing reprogramming of a large number of genes involved in cell division, migration and RNA splicing. Our findings provide evidence that T-025 could be a promising therapeutic drug for TNBC patients.https://doi.org/10.1186/s13058-025-02091-wTriple-negative breast cancerAlternative splicingCdc2-like kinaseSerine/arginine-rich proteins
spellingShingle Nasi Liu
Jurjun J. S. van der Velde
Sherien Ramdjielal
Esmee Koedoot
Nila K. van Overbeek
Daisy Batenburg
Alfred C. O. Vertegaal
Bob van de Water
Sylvia E. Le Dévédec
Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
Breast Cancer Research
Triple-negative breast cancer
Alternative splicing
Cdc2-like kinase
Serine/arginine-rich proteins
title Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
title_full Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
title_fullStr Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
title_full_unstemmed Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
title_short Pharmacological CLK inhibition disrupts SR protein function and RNA splicing blocking cell growth and migration in TNBC
title_sort pharmacological clk inhibition disrupts sr protein function and rna splicing blocking cell growth and migration in tnbc
topic Triple-negative breast cancer
Alternative splicing
Cdc2-like kinase
Serine/arginine-rich proteins
url https://doi.org/10.1186/s13058-025-02091-w
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