Project description:Wilms tumor is the most common kidney cancer in children, and anaplastic Wilms tumor is the most chemoresistant histological subtype. Here we explore how anaplastic Wilms tumor cells evade the common chemotherapeutic drug actinomycin D, which inhibits ribosomal biogenesis. We found that, when ribosomal capacity is limited by actinomycin D treatment, anaplastic Wilms tumor cells preferentially translate proteasome components and upregulate proteasome activity. Accordingly, increased proteasome levels are associated with anaplastic histology and with worse prognosis in Wilms tumor. Lastly, we show that the proteasome inhibitor bortezomib sensitizes cells to actinomycin D treatment both in vitro and in vivo.
Project description:We have undertaken a functional genomics approach to uncover novel therapeutic strategies efficacious for those patients with anaplastic Wilms’ tumor. Genomic analysis, in vitro chemical screens and microfluidic experiments demonstrate that MYCN over-expression in Wilms’ tumor can be modulated via BRD4 inhibition resulting in a reduction in Wilms’ tumor cell growth.
Project description:Wilms tumor is the most common pediatric kidney cancer. The best predictor of clinical outcome for Wilms tumor patients is how their tumor looks under the microscope (histology). Usually, the resistant/anaplastic component of the tumor makes up only a fraction of the total number of cells in the cancer. A critical barrier to understanding therapeutic resistance in this disease is that studies performed to sequence the resistant component is diluted by the other components of the tumor.Therefore, the current proposal aims to using single-nuclear-RNA sequencing to isolate the gene expression patterns of individual cell types in Wilms tumor and to focus on the anaplastic/resistant cells.
Project description:The lack of model systems limits the preclinical testing of novel therapies to address Wilms tumor patient groups with poor outcomes. Therefore, we established 45 heterotopic Wilms tumor patient-derived xenografts (WTPDX) in CB17 scid-/- mice that capture the biological heterogeneity of Wilms tumor (WT). These WTPDX include six showing diffuse anaplasia, nine from patients who went on to experience disease relapse, and thirteen from patients with bilateral disease. WTPDX retained the genetic alterations and the global transcriptomic and methylation profile of corresponding primary WT. In addition, favorable histology WTPDX were chemosensitive, while unfavorable histology WTPDX were resistant to conventional chemotherapy with vincristine, actinomycin-D, and doxorubicin. This WTPDX library is a unique scientific resource that retains the spectrum of biological heterogeneity present in WT and provides an essential tool for the testing of novel targeted therapies in the era of precision medicine.
Project description:The lack of model systems limits the preclinical testing of novel therapies to address Wilms tumor patient groups with poor outcomes. Therefore, we established 45 heterotopic Wilms tumor patient-derived xenografts (WTPDX) in CB17 scid-/- mice that capture the biological heterogeneity of Wilms tumor (WT). These WTPDX include six showing diffuse anaplasia, nine from patients who went on to experience disease relapse, and thirteen from patients with bilateral disease. WTPDX retained the genetic alterations and the global transcriptomic and methylation profile of corresponding primary WT. In addition, favorable histology WTPDX were chemosensitive, while unfavorable histology WTPDX were resistant to conventional chemotherapy with vincristine, actinomycin-D, and doxorubicin. This WTPDX library is a unique scientific resource that retains the spectrum of biological heterogeneity present in WT and provides an essential tool for the testing of novel targeted therapies in the era of precision medicine.
Project description:Germline and somatic mutations in BRCA1predispose to breast cancer. We found that proteasome inhibitors can selectively kill BRCA1-depleted cells. The toxic response involves a deregulation of the G1/S cell cycle checkpoint via hyperphosphorylation of RB1, 53BP1-mediated arrest at G2/M checkpoint, and ERN1-mediated unfolded protein response, culminating in a TNF receptor-mediated apoptosis. The study new unexpected molecular functions for BRCA1 protein and opens a novel possibility for the treatment of BRCA1-deficient cancers. We used microarrays to detail the global programme of gene expression underlying the response of BRCA1-deficient cells to proteasome inhibitor bortezomib. We aimed to identify genes that are strongly up- or down-regulated with a combination of BRCA1 knockdown and proteasome inhibition, but none of these treatments alone before the onset of apoptosis. HeLa and U2OS cells were transfected either with a non-targeting or anti-BRCA1 siRNAs (siControl or siBRCA1, respectively), treated with bortezomib for 8 hours, after which RNA was extracted for hybridization on Affymetrix microarray. The following treatments have been performed: (T1) siControl; (T2) siControl + 20 nM bortezomib for 8h; (T3) siBRCA1; (T4) siBRCA1 + 20 nM bortezomib for 8h. All samples were used without replicas. However, all genes showing inconsistent expression pattern between the two cell lines were excluded from further consideration. Selected candidate genes were subject to validation by qRT-PCR.
Project description:The E3 SUMO ligase PIAS2 is expressed at high levels in differentiated papillary thyroid carcinomas but at low levels in anaplastic thyroid carcinomas (ATC), an undifferentiated cancer with very high mortality. Double-stranded RNA–directed RNA interference (dsRNAi) targeting the PIAS2 isoform beta (PIAS2b) inhibits growth of ATC cell lines and patient primary cultures in vitro and orthotopic patient-derived xenografts (oPDX) in vivo, but not of thyroid cell lines or non-anaplastic primary thyroid cultures (differentiated carcinoma, benign lesions, or normal). PIAS2b-dsRNAi also has an anti-cancer effect on other anaplastic human cancers (pancreas, lung, and gastric). Mechanistically, PIAS2b is required for proper mitotic spindle and centrosome assembly, and it is a dosage-sensitive protein in ATC. Strikingly, PIAS2b-dsRNAi induces mitotic catastrophe at prophase. High-throughput proteomics revealed the proteasome (PSMC5) and spindle cytoskeleton as direct targets of PIAS2b SUMOylation at mitotic initiation. PIAS2b-dsRNAi is a promising therapy for ATC and other aggressive anaplastic cancers.
Project description:Fusion of the EWS gene to FLI1 produces a fusion oncoprotein that drives an aberrant gene expression program responsible for the development of Ewing sarcoma. We used a homogenous proximity assay to screen for compounds that disrupt the binding of EWS-FLI1 to its cognate DNA targets. A number of DNA-binding chemotherapeutic agents were found to non-specifically disrupt protein binding to DNA. In contrast, actinomycin D was found to preferentially disrupt EWS-FLI1 binding by comparison to p53 binding to their respective cognate DNA targets in vitro. In cell-based assays, low concentrations of actinomycin preferentially blocked EWS-FLI1 binding to chromatin, and disrupted EWS-FLI1-mediated gene expression. Higher concentrations of actinomycin globally repressed transcription. These results demonstrate that actinomycin preferentially disrupts EWS-FLI1 binding to DNA at selected concentrations. Although the window between this preferential effect and global suppression is too narrow to exploit in a therapeutic manner, these results suggest that base-preferences may be exploited to find DNA-binding compounds that preferentially disrupt subclasses of transcription factors.