SRPK Inhibitors Reduce the Phosphorylation and Translocation of SR Protein Splicing Factors, thereby Correcting BIN1, MCL-1 and BCL2 Splicing Errors and Enabling Apoptosis of Cholangiocarcinoma Cells
Issued Date
2024-09-29
Resource Type
eISSN
19450524
Scopus ID
2-s2.0-85205336525
Pubmed ID
39344395
Journal Title
Frontiers in bioscience (Scholar edition)
Volume
16
Issue
3
Rights Holder(s)
SCOPUS
Bibliographic Citation
Frontiers in bioscience (Scholar edition) Vol.16 No.3 (2024) , 17
Suggested Citation
Changphasuk P., Inpad C., Horpaopan S., Khunchai S., Phimsen S., Surangkul D., Janvilisri T., Silsirivanit A., Kaewkong W. SRPK Inhibitors Reduce the Phosphorylation and Translocation of SR Protein Splicing Factors, thereby Correcting BIN1, MCL-1 and BCL2 Splicing Errors and Enabling Apoptosis of Cholangiocarcinoma Cells. Frontiers in bioscience (Scholar edition) Vol.16 No.3 (2024) , 17. doi:10.31083/j.fbs1603017 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/101526
Title
SRPK Inhibitors Reduce the Phosphorylation and Translocation of SR Protein Splicing Factors, thereby Correcting BIN1, MCL-1 and BCL2 Splicing Errors and Enabling Apoptosis of Cholangiocarcinoma Cells
Corresponding Author(s)
Other Contributor(s)
Abstract
BACKGROUND: Cholangiocarcinoma (CCA) is a malignancy of the bile duct epithelium that is commonly found in the Thai population. CCA has poor prognosis and a low survival rate due to the lack of early diagnosis methods and the limited effectiveness of current treatments. A number of oncogenic spliced-transcripts resulting from mRNA splicing errors have been reported in CCA, and aberrant mRNA splicing is suspected to be a key driver of this cancer type. The hyperphosphorylation of serine/arginine rich-splicing factors (SRSFs) by serine/arginine protein kinases (SRPKs) causes them to translocate to the nucleus where they facilitate gene splicing errors that generate cancer-related mRNA/protein isoforms. METHODS: The correlation between SRPK expression and the survival of CCA patients was analyzed using data from The Cancer Genome Atlas (TCGA) dataset. The effect of SRPK inhibitors (SRPIN340 and SPHINX31) on two CCA cell lines (KKU-213A and TFK-1) was also investigated. The induction of cell death was studied by Calcein-AM/PI staining, AnnexinV/7AAD staining, immunofluorescence (IF), and Western blotting (WB). The phosphorylation and nuclear translocation of SRSFs was tracked by WB and IF, and the repair of splicing errors was examined by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). RESULTS: High levels of SRPK1 and SRPK2 transcripts, and in particular SRPK1, correlated with shorter survival in CCA patients. SRPIN340 and SPHINX31 increased the number of dead and apoptotic cells in a dose-dependent manner. CCA also showed diffuse expression of cytoplasmic cytochrome C and upregulation of cleaved caspase-3. Moreover, SRSFs showed low levels of phosphorylation, resulting in the accumulation of cytoplasmic SRSF1. To link these phenotypes with aberrant gene splicing, the apoptosis-associated genes Bridging Integrator 1 (BIN1), Myeloid cell leukemia factor 1 (MCL-1) and B-cell lymphoma 2 (BCL2) were selected for further investigation. Treatment with SRPIN340 and SPHINX31 decreased anti-apoptotic BIN1+12A and increased pro-apoptotic MCL-1S and BCL-xS. CONCLUSIONS: The SRPK inhibitors SRPIN340 and SPHINX31 can suppress the phosphorylation of SRSFs and their nuclear translocation, thereby producing BIN1, MCL-1 and BCL2 isoforms that favor apoptosis and facilitate CCA cell death.