Project description:Cdk4/6 inhibitors have shown to increase overall survival in hormone-positive breast tumors, but whether other solid tumors could respond to these inhibitors has not yet defined. Here we show that Palbociclib (a Cdk4/6 specific inhibitor in clinic use) treatment exerts antiproliferative effects in vivo using a bladder cancer cell lines.
Project description:Cdk4/6 inhibitors have shown to increase overall survival in hormone-positive breast tumors, but whether other solid tumors could respond to these inhibitors has not yet defined. Here we show that Palbociclib (a Cdk4/6 specific inhibitor in clinic use) + cisplatin (CDDP, a chemotherapeutic agent most active in locally or advanced bladder cancer patients) treatment exerts antiproliferative effects in vivo using a bladder cancer mouse model.
Project description:Cell size and the cell cycle are intrinsically coupled and abnormal increases in cell size are associated with senescence and permanent cell cycle arrest. The mechanism by which overgrowth primes cells to withdraw from the cell cycle remains unknown. We investigate this here using CDK4/6 inhibitors that arrest cell cycle progression during G0/G1 and are used in the clinic to treat ER+/HER2- metastatic breast cancer. We demonstrate that CDK4/6 inhibition promotes cellular overgrowth during G0/G1, causing p38MAPK-p53-p21-dependent cell cycle withdrawal. We find that cell cycle withdrawal is triggered by two waves of p21 induction. First, overgrowth during a long-term G0/G1 arrest induces an osmotic stress response. This stress response produces the first wave of p21 induction. Second, when CDK4/6 inhibitors are removed, a fraction of cells escape long term G0/G1 arrest and enter S-phase where overgrowth-driven replication stress results in a second wave of p21 induction that causes cell cycle withdrawal from G2, or the subsequent G1. We propose a model whereby both waves of p21 induction contribute to promote permanent cell cycle arrest. This model could explain why cellular hypertrophy is associated with senescence and why CDK4/6 inhibitors have long-lasting effects in patients.
Project description:PURPOSE: Despite over 70,000 new cases of bladder cancer in the United States annually, patients with advanced disease have a poor prognosis due to limited treatment modalities. We evaluate the role of Aurora A, identified as an upregulated candidate molecule in bladder cancer, in regulating bladder tumor growth. EXPERIMENTAL DESIGN: Gene expression in human bladder cancer samples was evaluated using RNA microarray and reverse-transcriptase PCR. The specific Aurora kinase A inhibitor MLN8237 (Millennium) was used to determine effects on bladder cancer cell growth using in vitro and in vivo models using malignant T24 and UM-UC-3 and papilloma-derived RT4 bladder cells. RESULTS: Urothelial carcinoma upregulates a set of 13 mitotic spindle associated transcripts, as compared to normal urothelium, including MAD2L1 (7.6-fold), BUB1B (8.8-fold), Aurora kinases A (5.6-fold) and Aurora kinase B (6.2-fold). Application of MLN8237 (10nM-1µM) to the human bladder tumor cell lines T24 and UM-UC-3 induced dose-dependent G2 cell cycle arrest, aneuploidy, mitotic spindle abnormalities, and apoptosis. MLN8237 arrested tumor growth when administered orally over 4 weeks in a mouse bladder cancer xenograft model (p<0.05). Finally, in vitro combination of MLN8237 with either paclitaxel or gemcitabine produced schedule-dependent synergistic antiproliferative effects in T24 cells when administered sequentially. CONCLUSIONS: Mitotic spindle checkpoint dysfunction is a common characteristic of human urothelial carcinoma, and can be exploited with pharmacologic Aurora A inhibition. Future studies that explore the mechanisms of spindle checkpoint failure in bladder cancer and evaluate the therapeutic role of Aurora kinases for bladder cancer patients would be of value. Tissue samples with urothelial cell carcinoma from bladder as well as normal references were collected and the gene expression profiles were compared. No technical replicates.
Project description:CDK4/6 kinase inhibitors have shown great promise in clinical trials in various cancer types and have recently entered clinical trial for advanced prostate cancer. Although patients are expected to respond well to this class of drugs, development of resistance in some patients is anticipated. To pre-empt this and study how prostate cancer may evade CDK4/6 inhibition, new resistance models were generated from LNCaP and LAPC4 prostate cancer cells cells by prolonged culturing in presence of 0.5uM palbociclib. A shotgun phosphoproteomics approach was utilized and integrated with RNA sequencing data to unravel the molecular underpinnings of acquired resistance to palbociclib and resultant broad CDK4/6 inhibitor resistance.
Project description:CDK4/6 kinase inhibitors have shown great promise in clinical trials in various cancer types and have recently entered clinical trial for advanced prostate cancer. Although patients are expected to respond well to this class of drugs, development of resistance in some patients is anticipated. To pre-empt this and study how prostate cancer may evade CDK4/6 inhibition, new resistance models were generated from LNCaP and LAPC4 prostate cancer cells cells by prolonged culturing in presence of 0.5uM palbociclib. RNA sequencing data was integrated with phospho-proteomics to unravel the molecular underpinnings of acquired resistance to palbociclib and resultant broad CDK4/6 inhibitor resistance.
Project description:PURPOSE: Despite over 70,000 new cases of bladder cancer in the United States annually, patients with advanced disease have a poor prognosis due to limited treatment modalities. We evaluate the role of Aurora A, identified as an upregulated candidate molecule in bladder cancer, in regulating bladder tumor growth. EXPERIMENTAL DESIGN: Gene expression in human bladder cancer samples was evaluated using RNA microarray and reverse-transcriptase PCR. The specific Aurora kinase A inhibitor MLN8237 (Millennium) was used to determine effects on bladder cancer cell growth using in vitro and in vivo models using malignant T24 and UM-UC-3 and papilloma-derived RT4 bladder cells. RESULTS: Urothelial carcinoma upregulates a set of 13 mitotic spindle associated transcripts, as compared to normal urothelium, including MAD2L1 (7.6-fold), BUB1B (8.8-fold), Aurora kinases A (5.6-fold) and Aurora kinase B (6.2-fold). Application of MLN8237 (10nM-1µM) to the human bladder tumor cell lines T24 and UM-UC-3 induced dose-dependent G2 cell cycle arrest, aneuploidy, mitotic spindle abnormalities, and apoptosis. MLN8237 arrested tumor growth when administered orally over 4 weeks in a mouse bladder cancer xenograft model (p<0.05). Finally, in vitro combination of MLN8237 with either paclitaxel or gemcitabine produced schedule-dependent synergistic antiproliferative effects in T24 cells when administered sequentially. CONCLUSIONS: Mitotic spindle checkpoint dysfunction is a common characteristic of human urothelial carcinoma, and can be exploited with pharmacologic Aurora A inhibition. Future studies that explore the mechanisms of spindle checkpoint failure in bladder cancer and evaluate the therapeutic role of Aurora kinases for bladder cancer patients would be of value.
Project description:We evaluated the tumor efficacy of the CDK4/6 inhibitor palbociclib in two chordoma Patient’s Derived Xenograft (PDX) models to validate and identify novel therapeutic approaches.