Project description:To investigate the effects of ginsenosides-CNTs conjugtaes on total expression profile of MCF-7 breast cancer cells, we conjugated ginsenoides Rb1 and Rg1 with multi-walled carbon nanotubes in a 5:1 ratio. Objectives for this study included the identification of genes that were up or down-regulated at the transcriptional level in MCF-7 cells treated with ginsenoside-CNTs conjugates and compare it to the ginsenosides alone (Rb1 and Rg1)
Project description:The retinoblastoma tumor suppressor (RB1) plays a critical role in coordinating multiple pathways that impact on tumor initiation, disease progression, and therapeutic responses. Here we interrogated the effect of CDK4/6 inhibitor in combination with mTOR inhibtor. Also, we interrogtaed the efffect of AURK and WEE1 inhibition in ER+ breast cacner models While the RB-pathway has been purported to exhibit multiple mutually exclusive events, only RB1 is mutually exclusive with multiple genetic events that deregulate CDK4/6 activity. Using an isogenic ER+ breast cancer model with targeted RB1 deletion, we identified gene expression features that link CDK4/6 activity and RB-dependency (CDK4/6-RB integrated signature). We also investigated the role of RB on apoptotic pathway. Single copy loss on chromosome 13q encompassing the RB1 locus is prevalent in many cancers, and is associated with reduced expression of multiple genes on 13q including RB1, and inversely related to the CDK4/6-RB integrated signature supporting a genetic cause/effect relationship. To probe the broader implications on tumor biology, we investigated genes that are positively and inversely correlated with the CDK4/6-RB integrated signature. This approach defined tumor-specific pathways that could represent new therapeutic vulnerabilities associated with RB-pathway activity.
Project description:The retinoblastoma tumor suppressor (RB1) plays a critical role in coordinating multiple pathways that impact on tumor initiation, disease progression, and therapeutic responses. Here we interrogated the TCGA pan-cancer data collection to probe fundamental molecular features associated with the RB-pathway across 31 tumor-types. While the RB-pathway has been purported to exhibit multiple mutually exclusive events, only RB1 is mutually exclusive with multiple genetic events that deregulate CDK4/6 activity. Using an isogenic ER+ breast cancer model with targeted RB1 deletion, we identified gene expression features that link CDK4/6 activity and RB-dependency (CDK4/6-RB integrated signature). This gene expression signature is associated with prognosis across a spectrum of tumors that exhibit average lower signature value indicative of more indolent diseases. Single copy loss on chromosome 13q encompassing the RB1 locus is prevalent in many cancers, and is associated with reduced expression of multiple genes on 13q including RB1, and inversely related to the CDK4/6-RB integrated signature supporting a genetic cause/effect relationship. To probe the broader implications on tumor biology, we investigated genes that are positively and inversely correlated with the CDK4/6-RB integrated signature. This approach defined tumor-specific pathways that could represent new therapeutic vulnerabilities associated with RB-pathway activity.
Project description:CDK4/6 inhibitors (CDK4/6i) have improved survival of patients with estrogen receptor-positive (ER+) breast cancer. However, patients treated with CDK4/6i eventually develop drug resistance and progress. RB1 loss-of-function alterations confer resistance to CDK4/6i, but the optimal therapy for these patients is unclear. Through a genome-wide CRISPR screen, we identified protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in ER+/RB1-knockout (RBKO) breast cancer cells. Inhibition of PRMT5 blocked the G1-to-S transition in the cell cycle independent of RB, leading to growth arrest in RBKO cells. Proteomics analysis uncovered fused in sarcoma (FUS) as a downstream effector of PRMT5. Inhibition of PRMT5 resulted in dissociation of FUS from RNA polymerase II (Pol II), which led to Ser2 Pol II hyperphosphorylation, intron retention, and subsequent downregulation of proteins involved in DNA synthesis. Furthermore, treatment with the PRMT5 inhibitor pemrametostat and a selective ER degrader fulvestrant synergistically inhibited growth of ER+/RB-deficient cell-derived and patient-derived xenografts. These findings highlight the potential of dual ER and PRMT5 blockade as a novel therapeutic strategy to overcome resistance to CDK4/6i in ER+/RB-deficient breast cancer.
Project description:CDK4/6 inhibitors (CDK4/6i) have improved survival of patients with estrogen receptor-positive (ER+) breast cancer. However, patients treated with CDK4/6i eventually develop drug resistance and progress. RB1 loss-of-function alterations confer resistance to CDK4/6i, but the optimal therapy for these patients is unclear. Through a genome-wide CRISPR screen, we identified protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in ER+/RB1-knockout (RBKO) breast cancer cells. Inhibition of PRMT5 blocked the G1-to-S transition in the cell cycle independent of RB, leading to growth arrest in RBKO cells. Proteomics analysis uncovered fused in sarcoma (FUS) as a downstream effector of PRMT5. Inhibition of PRMT5 resulted in dissociation of FUS from RNA polymerase II (Pol II), which led to Ser2 Pol II hyperphosphorylation, intron retention, and subsequent downregulation of proteins involved in DNA synthesis. Furthermore, treatment with the PRMT5 inhibitor pemrametostat and a selective ER degrader fulvestrant synergistically inhibited growth of ER+/RB-deficient cell-derived and patient-derived xenografts. These findings highlight the potential of dual ER and PRMT5 blockade as a novel therapeutic strategy to overcome resistance to CDK4/6i in ER+/RB-deficient breast cancer.
Project description:CDK4/6 inhibitors (CDK4/6i) have improved survival of patients with estrogen receptor-positive (ER+) breast cancer. However, patients treated with CDK4/6i eventually develop drug resistance and progress. RB1 loss-of-function alterations confer resistance to CDK4/6i, but the optimal therapy for these patients is unclear. Through a genome-wide CRISPR screen, we identified protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in ER+/RB1-knockout (RBKO) breast cancer cells. Inhibition of PRMT5 blocked the G1-to-S transition in the cell cycle independent of RB, leading to growth arrest in RBKO cells. Proteomics analysis uncovered fused in sarcoma (FUS) as a downstream effector of PRMT5. Inhibition of PRMT5 resulted in dissociation of FUS from RNA polymerase II (Pol II), which led to Ser2 Pol II hyperphosphorylation, intron retention, and subsequent downregulation of proteins involved in DNA synthesis. Furthermore, treatment with the PRMT5 inhibitor pemrametostat and a selective ER degrader fulvestrant synergistically inhibited growth of ER+/RB-deficient cell-derived and patient-derived xenografts. These findings highlight the potential of dual ER and PRMT5 blockade as a novel therapeutic strategy to overcome resistance to CDK4/6i in ER+/RB-deficient breast cancer.
Project description:CDK4/6 inhibitors (CDK4/6i) have improved survival of patients with estrogen receptor-positive (ER+) breast cancer. However, patients treated with CDK4/6i eventually develop drug resistance and progress. RB1 loss-of-function alterations confer resistance to CDK4/6i, but the optimal therapy for these patients is unclear. Through a genome-wide CRISPR screen, we identified protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in ER+/RB1-knockout (RBKO) breast cancer cells. Inhibition of PRMT5 blocked the G1-to-S transition in the cell cycle independent of RB, leading to growth arrest in RBKO cells. Proteomics analysis uncovered fused in sarcoma (FUS) as a downstream effector of PRMT5. Inhibition of PRMT5 resulted in dissociation of FUS from RNA polymerase II (Pol II), which led to Ser2 Pol II hyperphosphorylation, intron retention, and subsequent downregulation of proteins involved in DNA synthesis. Furthermore, treatment with the PRMT5 inhibitor pemrametostat and a selective ER degrader fulvestrant synergistically inhibited growth of ER+/RB-deficient cell-derived and patient-derived xenografts. These findings highlight the potential of dual ER and PRMT5 blockade as a novel therapeutic strategy to overcome resistance to CDK4/6i in ER+/RB-deficient breast cancer.
Project description:Genomic loss of RB1 is a common alteration in castration-resistant prostate cancer (CRPC) and is associated with poor patient outcomes. RB1-loss is also a driver event that promotes the neuroendocrine transdifferentiation of prostate cancer (PCa). The loss of Rb protein disrupts the Rb-E2F repressor complex and thus hyperactivates E2F transcription activators. While the impact of RB1-loss on PCa progression and linage plasticity has been previously studied, the underline mechanisms remain unclear. Using an integrated cistromic and transcriptomic analysis, we have characterized Rb activities in multiple CRPC models by identifying Rb directly regulated genes and revealed that Rb has distinct binding sites and targets in TP53-mutated CRPC. Significantly, we show that RB1-loss promotes the noncanonical activator function of LSD1/KDM1A, which stabilizes chromatin binding of E2F1, and hence sensitizes CRPC tumor to the LSD1 inhibitor treatment. These results provide new molecular insights of Rb activity in PCa progression and suggest LSD1 as a potential therapeutic target in CRPC with RB1-loss.
Project description:Genomic loss of RB1 is a common alteration in castration-resistant prostate cancer (CRPC) and is associated with poor patient outcomes. RB1-loss is also a driver event that promotes the neuroendocrine transdifferentiation of prostate cancer (PCa). The loss of Rb protein disrupts the Rb-E2F repressor complex and thus hyperactivates E2F transcription activators. While the impact of RB1-loss on PCa progression and linage plasticity has been previously studied, the underline mechanisms remain unclear. Using an integrated cistromic and transcriptomic analysis, we have characterized Rb activities in multiple CRPC models by identifying Rb directly regulated genes and revealed that Rb has distinct binding sites and targets in TP53-mutated CRPC. Significantly, we show that RB1-loss promotes the noncanonical activator function of LSD1/KDM1A, which stabilizes chromatin binding of E2F1, and hence sensitizes CRPC tumor to the LSD1 inhibitor treatment. These results provide new molecular insights of Rb activity in PCa progression and suggest LSD1 as a potential therapeutic target in CRPC with RB1-loss.
Project description:The retinoblastoma tumor suppressor (RB1) plays a critical role in coordinating multiple pathways that impact on tumor initiation, disease progression, and therapeutic responses. Here we interrogated the effect of cIAP inhibitor, birinapant in two different isogenic ER+ breast cancer models. Using MCF7-WT and MCF7-RB-del cell lines we investigated the differential gene expression pattern that link the effect of CIAP inhibition and RB dependency .