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Updated: Oct 3, 2025
Engineering Artificial Factors to Specifically Manipulate Alternative Splicing in Human Cells
Published on: April 26, 2017
Splicing factor arginine/serine-rich 8 promotes multiple myeloma malignancy and bone lesion through alternative
Yuanjiao Zhang1,2, Xichao Yu2, Rongze Sun3
1Nanjing Hospital of Chinese Medicine, Nanjing University of Chinese Medicine, Nanjing, China.
Background:
Multiple myeloma (MM) is a distinctive malignancy of plasma cell within the bone marrow (BM), of which alternative splicing factors play vital roles in the progression. Splicing factor arginine/serine-rich 8 (SFRS8) is the exclusive factor associated with MM prognosis, however its role in MM remains undefined.
Methods:
The analyses of 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide (MTT) assay, immunohistochemistry, flow cytometry and xenograft model were performed to examine cell proliferation, cell cycle and apoptosis in SFRS8 overexpression or knockdown MM cells in vitro and in vivo. The SFRS8-regulated alternative splicing events were identified by RNA immunoprecipitation sequencing (RIP-seq) and validated by RIP-qPCR and Co-IP methods. Exosomes were extracted from the supernatant of myeloma cells by ultracentrifugation. Bone lesion was evaluated by TRAP staining in vitro and SCID/NOD-TIBIA mouse model. A neon electroporation system was utilised to deliver siRNA through exosomes. The effect of siRNA-loaded exosomes in vivo was evaluated by using a patient-derived tumor xenograft (PDX) model and SCID/NOD-TIBIA mouse model.
Results:
SFRS8 was significantly upregulated in MM samples and positively associated with poor overall survival (OS) in MM patients. SFRS8 promoted MM cell proliferation in vitro and in vivo. Furthermore, calcyclin binding protein (CACYBP) was identified as the downstream target of SFRS8. Particularly, SFRS8 could reduce CACYBP isoform1 (NM_014412.3) and increase CACYBP isoform2 (NM_001007214.1) by mediating the alternative splicing of CACYBP, thereby altering the ubiquitination degradation of β-catenin to promote MM progression. In addition, SFRS8 promoted osteoclast differentiation through exosomes in vitro and in vivo. More importantly, exosomal siRNA targeting CACYBP isoform2 inhibited tumour growth in PDX and SCID/NOD-TIBIA mouse models.
Conclusion:
Our findings demonstrate that targeting the SFRS8/CACYBP/β-catenin axis may be a promising strategy for MM diagnosis and treatment.
Insights
Splicing factor SFRS8 drives multiple myeloma progression by altering CACYBP splicing and promoting cell growth. Targeting the SFRS8/CACYBP/β-catenin pathway offers a potential therapeutic strategy for this plasma cell malignancy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Multiple myeloma (MM) is a bone marrow malignancy driven by plasma cell dysregulation.
- Alternative splicing factors are implicated in MM progression, with SFRS8 identified as a key prognostic factor.
- The precise role of SFRS8 in MM pathogenesis remained largely undefined prior to this study.
Purpose of the Study:
- To elucidate the functional role of splicing factor SFRS8 (SFRS8) in the progression of multiple myeloma (MM).
- To identify downstream targets and molecular mechanisms regulated by SFRS8 in MM.
- To evaluate the therapeutic potential of targeting the SFRS8 pathway in MM models.
Main Methods:
- Utilized MTT assays, immunohistochemistry, flow cytometry, and xenograft models to assess MM cell proliferation and apoptosis in vitro and in vivo.
- Employed RNA immunoprecipitation sequencing (RIP-seq), RIP-qPCR, and Co-immunoprecipitation (Co-IP) to identify and validate SFRS8-regulated alternative splicing events.
- Investigated the role of exosomes in MM progression and developed exosome-mediated siRNA delivery for therapeutic targeting.
Main Results:
- SFRS8 expression is significantly upregulated in MM patient samples and correlates with poor overall survival.
- SFRS8 promotes MM cell proliferation and osteoclast differentiation, partly through exosome-mediated mechanisms.
- SFRS8 regulates the alternative splicing of calcyclin binding protein (CACYBP), specifically increasing CACYBP isoform2, which impacts β-catenin degradation and MM progression.
- Exosomal siRNA targeting CACYBP isoform2 demonstrated significant tumor growth inhibition in patient-derived xenograft models.
Conclusions:
- The SFRS8/CACYBP/β-catenin signaling axis is a critical driver of multiple myeloma progression.
- Targeting SFRS8 or its downstream effectors, such as CACYBP isoform2, represents a promising therapeutic strategy for MM.
- Exosome-mediated delivery of siRNA offers a viable approach for targeted MM therapy.
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