Project description:To identify whether the expression of DDX5 was linked to circular RNAs splicing processes, we transfected AGS cell with FLAG-DDX5 or FLAG-tagged empty vector (negative control, NC), and analyzed the differentially expressed circRNAs
Project description:The small heat shock protein Hsp27 has been long demonstrated as a major driver of Castration Resistant Prostate Cancer (CRPC) progression via an androgen receptor-independent pathway. In the light of identification of its molecular mechanisms, we found that the RNA helicase protein DDX5 was an interactor of Hsp27 and DDX5 expression was regulated by Hsp27 through its cytoprotective function. We showed that DDX5 was overexpressed in a large collection of human samples in aggressive PCs, especially CRPC. Here, we described the protein-protein interaction network of DDX5 which were identified in four human prostate cell lines (PNT1A, LNCaP, DU-145 and PC-3) representing different disease stages using immunoaffinity purification and quantitative mass spectrometry. The DDX5 interactome in CRPC cells was enriched in several functions (DNA damage response, translation, transcription, RNA stability, and DNA conformation changes) involved in disease progression. Furthermore, we found a new critical function of DDX5 in DNA damage repair in CRPC and validated the interaction of DDX5 with the DNA repair complex Ku70/Ku86 which plays a pivotal role in the NHEJ process. We also showed that DDX5 overexpression conferred resistance to DNA damage poisoners (such as irradiation and cisplatin) in CRPC, a feature that could lead to genome maintenance, tumor progression and treatment resistance.
Project description:The BRCA2 tumor suppressor is a DNA double-strand break repair factor essential to maintain genome integrity. BRCA2-deficient cells spontaneously accumulate DNA-RNA hybrids, a known source of genome instability. However, the specific role of BRCA2 on these structures remains poorly understood. Here we identified the DEAD-box RNA helicase DDX5 as a BRCA2 interacting partner. We show that DDX5 associates with DNA-RNA hybrids that form in the vicinity of DSBs and this association is enhanced by BRCA2. Notably, BRCA2 stimulates the DNA-RNA hybrid helicase activity of DDX5. Impaired BRCA2-DDX5 interaction, as observed in cells bearing the breast cancer variant BRCA2-T207A, reduces DDX5 association with DSBs, decreases the number of RPA foci upon irradiation and impairs RAD51 repair foci formation. Our findings are consistent with DNA-RNA hybrids being an impediment for the repair of DSBs by homologous recombination and reveal BRCA2 and DDX5 as active players in their removal.
Project description:DDX5 is a founding member of the DEAD-box RNA helicase family, which are a group of enzymes that regulate ribonucleoprotein (RNP) formation and function in every aspect of RNA metabolism. Our lab previously found that DDX5 is involved in energy homeostasis, a process altered in many cancers. Small cell lung cancer (SCLC) is an understudied cancer type that lacks effective treatment. Therefore, we investigated the roles of DDX5 in SCLC. We show here that DDX5 is overexpressed in SCLC cell lines. Depletion of DDX5 results in reduced growth and mitochondrial dysfunction in the chemoresistant SCLC cell line H69AR. The latter is evidenced by downregulation of genes involved in oxidative phosphorylation and impaired oxygen consumption,. Interestingly, depletion of DDX5 specifically leads to reduction of intracellular succinate, a TCA intermediate that serves as a direct electron donor to mitochondrial complex II. Taken together, we propose that the oncogenic role of DDX5 is at least in part manifested through upregulation of respiration to support the energy demands of cancer cells. This also suggests that defects in RNP remodeling are connected to energy metabolism and carcinogenesis.
Project description:Alternative splicing profiling of apopotosis related genes in human HeLa cells (cervical cancer cell line) transfected with a plasmid expressing shRNAs targetting p68 helicase (DDX5, DEAD (Asp-Glu-Ala-Asp) box polypeptide 5) cloned into the pSuper expression vector compared to empty vector. Keywords: treated vs. untreated comparison; alternative splicing Two-condition experiment, where the p68 DDX5 gene product levels was inhibited by siRNA transfection and compared to transfection with the negative control (scrambled siRNA). Biological replicates: 2, all independently grown and harvested. A dye swapping technical duplicate was performed for each biological replicate. Samples were hybridized onto a 44290 feature array designed by ExonHit to detect splicing events in apopotosis related genes and manufactured by Agilent using in situ synthesis of oligonucleotides by SurePrint technology.
Project description:Background: The lack of obvious symptoms of early gastric cancer (GC) as well as the absence of sensitive and specific biomarkers results in poor clinical outcomes. Tubulin is currently emerging as important regulators of the microtubule cytoskeleton and thus have a strong potential to be implicated in a number of disorders, however, its mechanism of action in gastric cancer is still unclear. Tubulin alpha-1C(TUBA1C) is a subtype of α-tubulin, high TUBA1C expression has been shown to be closely related to a poor prognosis in in various cancers,this study, for the first time, revealed the mechanism of TUBA1C promotes malignant progression of gastric cancer in vitro and in vivo. Methods: The expression of lncRNA EGFR-AS1 was detected in human GC cell lines by qRT–PCR. Mass spectrometry experiments following RNA pulldown assays found that EGFR-AS1 directly binds to TUBA1C, the CCK8, EdU, transwell, wound-healing, cell cycle assays and animal experiments were conducted to investigate the function of TUBA1C in GC. Combined with bioinformatics analyses, reveal interaction between Ki-67, E2F1, PCNA and TUBA1C by western blot. Rescue experiments furtherly demonstrated the relationship of EGFR-AS1and TUBA1C. Results: TUBA1C was proved to be a direct target of EGFR-AS1, TUBA1C promotes gastric cancer proliferation, migration and invasion by accelerating the progression of the cell cycle from the G1 phase to the S phase and activating the expression of oncogenes: Ki-67,E2F1 and PCNA. Conclusions: TUBA1C is a new potential target of LncRNA EGFR-AS1 promotes gastric cancer progression and could be a novel biomarker and therapeutic target for GC.