Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer
Targeting PI3Kδ has emerged as a promising therapy for hematologic and non-hematologic malignancies. Previously, we identified an oncogenic splice variant, <i>PIK3CD-S</i>, conferring Idelalisib resistance in African American (AA) prostate cancer (PCa). In the current study, we employed...
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| Format: | Article |
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MDPI AG
2023-02-01
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| Series: | Cancers |
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| Online Access: | https://www.mdpi.com/2072-6694/15/4/1337 |
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| author | Siyoung Ha Bi-Dar Wang |
| author_facet | Siyoung Ha Bi-Dar Wang |
| author_sort | Siyoung Ha |
| collection | DOAJ |
| description | Targeting PI3Kδ has emerged as a promising therapy for hematologic and non-hematologic malignancies. Previously, we identified an oncogenic splice variant, <i>PIK3CD-S</i>, conferring Idelalisib resistance in African American (AA) prostate cancer (PCa). In the current study, we employed a comprehensive analysis combining molecular biology, biochemistry, histology, in silico simulation, and in vitro functional assays to investigate the <i>PIK3CD-S</i> expression profiles in PCa samples and to elucidate the drug resistance mechanism mediated by PI3Kδ-S (encoded by <i>PIK3CD-S</i>). The immunohistochemistry, RT-PCR, and Western blot assays first confirmed that PI3Kδ-S is highly expressed in AA PCa. Compared with PCa expressing the full-length PI3Kδ-L, PCa expressing PI3Kδ-S exhibits enhanced drug resistance properties, including a higher cell viability, more antiapoptotic and invasive capacities, and constitutively activated PI3K/AKT signaling, in the presence of PI3Kδ/PI3K inhibitors (Idelalisib, Seletalisib, Wortmannin, and Dactolisib). Molecular docking, ATP-competitive assays, and PI3 kinase assays have further indicated a drastically reduced affinity of PI3Kδ inhibitors with PI3Kδ-S vs. PI3Kδ-L, attributed to the lack of core binding residues in the PI3Kδ-S catalytic domain. Additionally, SRSF2 has been identified as a critical splicing factor mediating exon 20 skipping in <i>PIK3CD</i> pre-mRNA. The inhibition of the SRSF2 activity by SRPIN340 successfully sensitizes AA PCa cells to PI3Kδ inhibitors, suggesting a novel therapeutic option for Idelalisib-resistant tumors. |
| first_indexed | 2024-03-11T09:02:08Z |
| format | Article |
| id | doaj.art-9809b1d23efa48f5bb8136e038c031c4 |
| institution | Directory Open Access Journal |
| issn | 2072-6694 |
| language | English |
| last_indexed | 2024-03-11T09:02:08Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Cancers |
| spelling | doaj.art-9809b1d23efa48f5bb8136e038c031c42023-11-16T19:39:36ZengMDPI AGCancers2072-66942023-02-01154133710.3390/cancers15041337Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate CancerSiyoung Ha0Bi-Dar Wang1Department of Pharmaceutical Sciences, University of Maryland Eastern Shore School of Pharmacy and Health Professions, Princess Anne, MD 21853, USADepartment of Pharmaceutical Sciences, University of Maryland Eastern Shore School of Pharmacy and Health Professions, Princess Anne, MD 21853, USATargeting PI3Kδ has emerged as a promising therapy for hematologic and non-hematologic malignancies. Previously, we identified an oncogenic splice variant, <i>PIK3CD-S</i>, conferring Idelalisib resistance in African American (AA) prostate cancer (PCa). In the current study, we employed a comprehensive analysis combining molecular biology, biochemistry, histology, in silico simulation, and in vitro functional assays to investigate the <i>PIK3CD-S</i> expression profiles in PCa samples and to elucidate the drug resistance mechanism mediated by PI3Kδ-S (encoded by <i>PIK3CD-S</i>). The immunohistochemistry, RT-PCR, and Western blot assays first confirmed that PI3Kδ-S is highly expressed in AA PCa. Compared with PCa expressing the full-length PI3Kδ-L, PCa expressing PI3Kδ-S exhibits enhanced drug resistance properties, including a higher cell viability, more antiapoptotic and invasive capacities, and constitutively activated PI3K/AKT signaling, in the presence of PI3Kδ/PI3K inhibitors (Idelalisib, Seletalisib, Wortmannin, and Dactolisib). Molecular docking, ATP-competitive assays, and PI3 kinase assays have further indicated a drastically reduced affinity of PI3Kδ inhibitors with PI3Kδ-S vs. PI3Kδ-L, attributed to the lack of core binding residues in the PI3Kδ-S catalytic domain. Additionally, SRSF2 has been identified as a critical splicing factor mediating exon 20 skipping in <i>PIK3CD</i> pre-mRNA. The inhibition of the SRSF2 activity by SRPIN340 successfully sensitizes AA PCa cells to PI3Kδ inhibitors, suggesting a novel therapeutic option for Idelalisib-resistant tumors.https://www.mdpi.com/2072-6694/15/4/1337aberrant <i>PIK3CD</i> splice variantprostate cancer disparitiesIdelalisib resistancemolecular dockingSRSF2-mediated splicingsynergistic drug therapy |
| spellingShingle | Siyoung Ha Bi-Dar Wang Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer Cancers aberrant <i>PIK3CD</i> splice variant prostate cancer disparities Idelalisib resistance molecular docking SRSF2-mediated splicing synergistic drug therapy |
| title | Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer |
| title_full | Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer |
| title_fullStr | Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer |
| title_full_unstemmed | Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer |
| title_short | Molecular Insight into Drug Resistance Mechanism Conferred by Aberrant <i>PIK3CD</i> Splice Variant in African American Prostate Cancer |
| title_sort | molecular insight into drug resistance mechanism conferred by aberrant i pik3cd i splice variant in african american prostate cancer |
| topic | aberrant <i>PIK3CD</i> splice variant prostate cancer disparities Idelalisib resistance molecular docking SRSF2-mediated splicing synergistic drug therapy |
| url | https://www.mdpi.com/2072-6694/15/4/1337 |
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