scholarly journals circSMARCA5-SRSF1 interaction is functionally involved in GBM pathogenesis

2021 ◽  
Vol 54 (384) ◽  
pp. MISC3-MISC4
Author(s):  
Angela Caponnetto
Keyword(s):  
Alternative Splicing ◽  
Survival Rates ◽  
Progression Free Survival ◽  
Splicing Factor ◽  
Circular Rnas ◽  
Physical Interaction ◽  
Human Brain Tumor ◽  
Molecular Features ◽  
Upstream Regulator ◽  
Grade Malignancy

Glioblastoma multiforme (GBM) is the most aggressive human brain tumor with a median survival of 15 months. The standard treatments of GBM and the total medical resection are unable to contrast this mortal cancer. For these reason new diagnostic approaches and therapies are needed. The identification of molecular features of this cancer may allow to create a personalized therapy. Circular RNAs (circRNAs) are a new class of non-coding RNAs (ncRNAs) highly enriched in brain, stable within the cells, detectable in body fluids and having a potential role and biological importance still object of debate. This thesis investigated the putative involvement of circRNAs in GBM pathogenesis. It has been demonstrated that circSMARCA5 is downregulated in GBM biopsies, its expression is associated to the glioma grade malignancy and it negatively regulates migration of U87MG cells. Moreover, it has been proved the physical interaction between circSMARCA5 and one of its predicted interactor Serine/arginine-rich splicing factor 1 (SRSF1). Interesting splicing targets of SRSF1 are the serine and arginine rich splicing factor 3 (SRSF3) and the vascular endothelial growth factor A (VEGFA). It has been proposed that circSMARCA5 may regulate the alternative splicing of SRSF3 in favor of the formation of a stable oncoprotein in GBM. It also regulates the alternative splicing of VEGFA mRNA through the binding to SRSF1. In addition, blood vascular microvessel density evaluated in GBM negatively correlates with the expression of circSMARCA5, while positively correlates with that of SRSF1 and pro-to-anti-angiogenic VEGFA isoform ratio. GBM patients with low circSMARCA5 expression have lower overall and progression free survival rates. Based on these findings, CircSMARCA5 could be considered a promising druggable tumor suppressor in GBM. Moreover, its interaction with SRSF1 makes circSMARCA5 an upstream regulator of pro- to anti-angiogenic VEGFA isoforms ratio within GBM cells and a highly promising GBM prospective anti-angiogenic molecule.

scholarly journals CircSMARCA5 Regulates VEGFA mRNA Splicing and Angiogenesis in Glioblastoma Multiforme Through the Binding of SRSF1

Cancers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 194 ◽  
Author(s):  
Davide Barbagallo ◽  
Angela Caponnetto ◽  
Duilia Brex ◽  
Federica Mirabella ◽  
Cristina Barbagallo ◽  
...  
Keyword(s):  
Glioblastoma Multiforme ◽  
Survival Rates ◽  
Progression Free Survival ◽  
Negative Control ◽  
Splicing Factor ◽  
Circular Rnas ◽  
P Value ◽  
Physical Interaction ◽  
Mrna Isoforms ◽  
R Value

Circular RNAs are a large group of RNAs whose cellular functions are still being investigated. We recently proposed that circSMARCA5 acts as sponge for the splicing factor Serine and Arginine Rich Splicing Factor 1 (SRSF1) in glioblastoma multiforme (GBM). After demonstrating by RNA immunoprecipitation a physical interaction between SRFS1 and circSMARCA5, we assayed by real-time PCR in a cohort of 31 GBM biopsies and 20 unaffected brain parenchyma controls (UC) the expression of total, pro-angiogenic (Iso8a) and anti-angiogenic (Iso8b) mRNA isoforms of Vascular Endothelial Growth Factor A (VEGFA), a known splicing target of SRSF1. The Iso8a to Iso8b ratio: (i) increased in GBM biopsies with respect to UC (p-value < 0.00001); (ii) negatively correlated with the expression of circSMARCA5 (r-value = −0.46, p-value = 0.006); (iii) decreased in U87-MG overexpressing circSMARCA5 with respect to negative control (p-value = 0.0055). Blood vascular microvessel density, estimated within the same biopsies, negatively correlated with the expression of circSMARCA5 (r-value = −0.59, p-value = 0.00001), while positively correlated with that of SRSF1 (r-value = 0.38, p-value = 0.00663) and the Iso8a to Iso8b ratio (r-value = 0.41, p-value = 0.0259). Kaplan-Meier survival analysis showed that GBM patients with low circSMARCA5 expression had lower overall and progression free survival rates than those with higher circSMARCA5 expression (p-values = 0.033, 0.012, respectively). Our data convincingly suggest that circSMARCA5 is an upstream regulator of pro- to anti-angiogenic VEGFA isoforms ratio within GBM cells and a highly promising GBM prognostic and prospective anti-angiogenic molecule.

scholarly journals Isoform-specific characterization implicates alternative splicing in APOBEC3B as a mechanism restricting APOBEC-mediated mutagenesis

2020 ◽  
Author(s):  
A. Rouf Banday ◽  
Olusegun O. Onabajo ◽  
Seraph Han-Yin Lin ◽  
Adeola Obajemu ◽  
Joselin M. Vargas ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Alternative Splicing ◽  
Mutagenic Activity ◽  
Progression Free Survival ◽  
Splicing Factor ◽  
Free Survival ◽  
Alternatively Spliced ◽  
Intron 4 ◽  
Weak Branch

ABSTRACTAPOBEC3A (A3A) and APOBEC3B (A3B) enzymes drive APOBEC-mediated mutagenesis, but the understanding of the regulation of their mutagenic activity remains limited. Here, we showed that mutagenic and non-mutagenic A3A and A3B enzymes are produced by canonical and alternatively spliced A3A and A3B isoforms, respectively. Notably, increased expression of the canonical A3B isoform, which encodes the mutagenic A3B enzyme, predicted shorter progression-free survival of bladder cancer patients. Expression of the mutagenic A3B isoform was reduced by exon 5 skipping, generating a non-mutagenic A3B isoform. The exon 5 skipping, which was dependent on the interaction between SF3B1 splicing factor and weak branch point sites in intron 4, could be enhanced by an SF3B1 inhibitor, decreasing the production of the mutagenic A3B enzyme. Thus, our results underscore the role of A3B, especially in bladder cancer, and implicate alternative splicing of A3B as a mechanism and therapeutic target to restrict APOBEC-mediated mutagenesis.

scholarly journals Structural evolution of the tissue-specific U2AF2 paralog and alternative splicing factor LS2

2020 ◽  
Author(s):  
Ashish Ashok Kawale ◽  
J. Matthew Taliaferro ◽  
Hyun-Seo Kang ◽  
Christoph Hartmüller ◽  
Arie Geerlof ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Rna Binding ◽  
Mutational Analysis ◽  
Splicing Factor ◽  
Rna Recognition Motif ◽  
Sequencing Data ◽  
Tissue Specific ◽  
Molecular Features ◽  
G Quadruplex

AbstractThe Drosophila melanogaster LS2 protein is a tissue-specific paralog of U2AF2 that mediates testis-specific alternative splicing. In order to understand the structural mechanisms underlying the distinct RNA binding specificity we determined the solution structures of the LS2 RNA recognition motif (RRM) domains and characterized their interaction with cis-regulatory guanosine-rich RNA motifs found in intron regions upstream of alternatively spliced exons. We show that the guanosine-rich RNA adopts a G quadruplex (G4) fold in vitro. The LS2 tandem RRMs adopt canonical RRM folds that are connected by a 38-residue linker that harbors a small helical motif α0. The LS2 RRM2 domain and the α0 helix in the interdomain linker mediate interactions with the G4 RNA. The functional importance of these unique molecular features in LS2 is validated by mutational analysis in vitro and RNA splicing assays in vivo. RNA sequencing data confirm the enrichment of G4-forming LS2 target motifs near LS2-affected exons. Our data indicate a role of G quadruplex structures as cis-regulatory motifs in introns for the regulation of alternative splicing, that engage non-canonical interactions with a tandem RRM protein. These results highlight the intriguing molecular evolution of a tissue-specific splicing factor from its conserved U2AF2 paralog as a result of (retro-) gene duplication in D. melanogaster.

scholarly journals Radiotherapy in nodal oligorecurrent prostate cancer

2021 ◽  
Author(s):  
Michael Pinkawa ◽  
Daniel M. Aebersold ◽  
Dirk Böhmer ◽  
Michael Flentje ◽  
Pirus Ghadjar ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Literature Review ◽  
Survival Rates ◽  
Local Treatment ◽  
Progression Free Survival ◽  
Nodal Metastasis ◽  
Stereotactic Ablative Radiotherapy ◽  
Current Standard ◽  
Free Survival ◽  
Systemic Treatments

Abstract Objective The current article encompasses a literature review and recommendations for radiotherapy in nodal oligorecurrent prostate cancer. Materials and methods A literature review focused on studies comparing metastasis-directed stereotactic ablative radiotherapy (SABR) vs. external elective nodal radiotherapy (ENRT) and studies analyzing recurrence patterns after local nodal treatment was performed. The DEGRO Prostate Cancer Expert Panel discussed the results and developed treatment recommendations. Results Metastasis-directed radiotherapy results in high local control (often > 90% within a follow-up of 1–2 years) and can be used to improve progression-free survival or defer androgen deprivation therapy (ADT) according to prospective randomized phase II data. Distant progression after involved-node SABR only occurs within a few months in the majority of patients. ENRT improves metastases-free survival rates with increased toxicity in comparison to SABR according to retrospective comparative studies. The majority of nodal recurrences after initial local treatment of pelvic nodal metastasis are detected within the true pelvis and common iliac vessels. Conclusion ENRT with or without a boost should be preferred to SABR in pelvic nodal recurrences. In oligometastatic prostate cancer with distant (extrapelvic) nodal recurrences, SABR alone can be performed in selected cases. Application of additional systemic treatments should be based on current guidelines, with ADT as first-line treatment for hormone-sensitive prostate cancer. Only in carefully selected patients can radiotherapy be initially used without additional ADT outside of the current standard recommendations. Results of (randomized) prospective studies are needed for definitive recommendations.

scholarly journals FEN1 Blockade for Platinum Chemo-Sensitization and Synthetic Lethality in Epithelial Ovarian Cancers

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1866
Author(s):  
Katia A. Mesquita ◽  
Reem Ali ◽  
Rachel Doherty ◽  
Michael S. Toss ◽  
Islam Miligy ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
High Throughput Screening ◽  
Nuclear Translocation ◽  
Synthetic Lethality ◽  
Excision Repair ◽  
Progression Free Survival ◽  
Ovarian Cancer Cells ◽  
Physical Interaction ◽  
Base Excision

FEN1 plays critical roles in long patch base excision repair (LP-BER), Okazaki fragment maturation, and rescue of stalled replication forks. In a clinical cohort, FEN1 overexpression is associated with aggressive phenotype and poor progression-free survival after platinum chemotherapy. Pre-clinically, FEN1 is induced upon cisplatin treatment, and nuclear translocation of FEN1 is dependent on physical interaction with importin β. FEN1 depletion, gene inactivation, or inhibition re-sensitizes platinum-resistant ovarian cancer cells to cisplatin. BRCA2 deficient cells exhibited synthetic lethality upon treatment with a FEN1 inhibitor. FEN1 inhibitor-resistant PEO1R cells were generated, and these reactivated BRCA2 and overexpressed the key repair proteins, POLβ and XRCC1. FEN1i treatment was selectively toxic to POLβ deficient but not XRCC1 deficient ovarian cancer cells. High throughput screening of 391,275 compounds identified several FEN1 inhibitor hits that are suitable for further drug development. We conclude that FEN1 is a valid target for ovarian cancer therapy.

scholarly journals Lorlatinib in pretreated ALK- or ROS1-positive lung cancer and impact of TP53 co-mutations: results from the German early access program

2021 ◽  
Vol 13 ◽  
pp. 175883592098055 ◽  
Author(s):  
Nikolaj Frost ◽  
Petros Christopoulos ◽  
Diego Kauffmann-Guerrero ◽  
Jan Stratmann ◽  
Richard Riedel ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Survival Rates ◽  
Real Life ◽  
Progression Free Survival ◽  
Leptomeningeal Carcinomatosis ◽  
Resistance Mutations ◽  
Duration Of Treatment ◽  
Tp53 Mutations ◽  
Early Access ◽  
Access Program

Introduction: We report on the results of the German early access program (EAP) with the third-generation ALK- and ROS1-inhibitor lorlatinib. Patients and Methods: Patients with documented treatment failure of all approved ALK/ROS1-specific therapies or with resistance mutations not covered by approved inhibitors or leptomeningeal carcinomatosis were enrolled and analyzed. Results: In total, 52 patients were included [median age 57 years (range 32–81), 54% female, 62% never smokers, 98% adenocarcinoma]; 71% and 29% were ALK- and ROS1-positive, respectively. G1202R and G2032R resistance mutations prior to treatment with lorlatinib were observed in 10 of 26 evaluable patients (39%), 11 of 39 patients showed TP53 mutations (28%). Thirty-six patients (69%) had active brain metastases (BM) and nine (17%) leptomeningeal carcinomatosis when entering the EAP. Median number of prior specific TKIs was 3 (range 1–4). Median duration of treatment, progression-free survival (PFS), response rate and time to treatment failure were 10.4 months, 8.0 months, 54% and 13.0 months. Calculated 12-, 18- and 24-months survival rates were 65, 54 and 47%, overall survival since primary diagnosis (OS2) reached 79.6 months. TP53 mutations were associated with a substantially reduced PFS (3.7 versus 10.8 month, HR 3.3, p = 0.003) and were also identified as a strong prognostic biomarker (HR for OS2 3.0 p = 0.02). Neither prior treatments with second-generation TKIs nor BM had a significant influence on PFS and OS. Conclusions: Our data from real-life practice demonstrate the efficacy of lorlatinib in mostly heavily pretreated patients, providing a clinically meaningful option for patients with resistance mutations not covered by other targeted therapies and those with BM or leptomeningeal carcinomatosis.

Evolution of Surgical Approaches in the Treatment of Petroclival Meningiomas: A Retrospective Review

2007 ◽  
Vol 61 (suppl_5) ◽  
pp. ONS202-ONS211 ◽  
Author(s):  
Nicholas C. Bambakidis ◽  
U. Kumar Kakarla ◽  
Louis J. Kim ◽  
Peter Nakaji ◽  
Randall W. Porter ◽  
...  
Keyword(s):  
Survival Rates ◽  
Progression Free Survival ◽  
Surgical Approaches ◽  
Single Institution ◽  
Short Term ◽  
Total Resection ◽  
Free Survival ◽  
Petroclival Meningioma ◽  
Petroclival Meningiomas

Abstract Objective: We examined the surgical approaches used at a single institution to treat petroclival meningioma and evaluated changes in method utilization over time. Methods: Craniotomies performed to treat petroclival meningioma between September of 1994 and July of 2005 were examined retrospectively. We reviewed 46 patients (mean follow-up, 3.6 yr). Techniques included combined petrosal or transcochlear approaches (15% of patients), retrosigmoid craniotomies with or without some degree of petrosectomy (59% of patients), orbitozygomatic craniotomies (7% of patients), and combined orbitozygomatic-retrosigmoid approaches (19% of patients). In 18 patients, the tumor extended supratentorially. Overall, the rate of gross total resection was 43%. Seven patients demonstrated progression over a mean of 5.9 years. No patients died. At 36 months, the progression-free survival rate for patients treated without petrosal approaches was 96%. Of 14 patients treated with stereotactic radiosurgery, none developed progression. Conclusion: Over the study period, a diminishing proportion of patients with petroclival meningioma were treated using petrosal approaches. Utilization of the orbitozygomatic and retrosigmoid approaches alone or in combination provided a viable alternative to petrosal approaches for treatment of petroclival meningioma. Regardless of approach, progression-free survival rates were excellent over short-term follow-up period.

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