Project description:Heat shock protein 90 (Hsp90) is an essential evolutionarily conserved molecular chaperone in eukaryotes. Cancer cells rely on Hsp90 to chaperone activated oncoproteins, and its involvement in numerous signaling pathways makes it an attractive target for drug development. Surprisingly, however, the impact of Hsp90 inhibitors on cancer cells is most commonly cytostatic, and efforts to enhance the anti-tumor activity of Hsp90 inhibitors in the clinic remain a significant challenge. In this study, we show that dual inhibition of Wee1 tyrosine kinase and Hsp90 causes prostate cancer cells to undergo apoptosis. Gene-expression profiling revealed that induction of the intrinsic apoptotic pathway by this drug combination coincided with transcriptional down-regulation of Survivin and Wee1, an outcome not seen in cells treated separately with either agent. At the translational level, expression of these two proteins as well as activated Akt was completely abrogated. Similar results were obtained in prostate cancer xenografts. These data establish a novel therapeutic strategy to enhance the efficacy of Hsp90 inhibitors in prostate cancer, and they provide a mechanistic rationale for stimulating the pro-apoptotic activity of Hsp90 inhibitors. In order to explore the mechanism underlying the enhanced cell death caused by Wee1 inhibitorII and 17-AAG combination, we performed microarray analysis using PC3 cells treated with Wee1 inhibitorII alone, 17-AAG alone, or the two drugs in combination. There are 12 samples in total. There are three experimental replicate. Samples 1, 5 and 9 are control (C) (untreated PC3- prostate cancer cells). Samples 2, 6, and 10 are cells treated with Wee1 inhibitor II (W). Samples 3, 7, and 11 are treated with 17-AAG (A), (an Hsp90 inhibitor). Samples 4, 8, and 12 are treated with both Wee1 inhibitorII and 17-AAG (WA). Samples 5 was removed from our analysis due to weak signal.
Project description:Heat shock protein 90 (Hsp90) is an essential evolutionarily conserved molecular chaperone in eukaryotes. Cancer cells rely on Hsp90 to chaperone activated oncoproteins, and its involvement in numerous signaling pathways makes it an attractive target for drug development. Surprisingly, however, the impact of Hsp90 inhibitors on cancer cells is most commonly cytostatic, and efforts to enhance the anti-tumor activity of Hsp90 inhibitors in the clinic remain a significant challenge. In this study, we show that dual inhibition of Wee1 tyrosine kinase and Hsp90 causes prostate cancer cells to undergo apoptosis. Gene-expression profiling revealed that induction of the intrinsic apoptotic pathway by this drug combination coincided with transcriptional down-regulation of Survivin and Wee1, an outcome not seen in cells treated separately with either agent. At the translational level, expression of these two proteins as well as activated Akt was completely abrogated. Similar results were obtained in prostate cancer xenografts. These data establish a novel therapeutic strategy to enhance the efficacy of Hsp90 inhibitors in prostate cancer, and they provide a mechanistic rationale for stimulating the pro-apoptotic activity of Hsp90 inhibitors. In order to explore the mechanism underlying the enhanced cell death caused by Wee1 inhibitorII and 17-AAG combination, we performed microarray analysis using PC3 cells treated with Wee1 inhibitorII alone, 17-AAG alone, or the two drugs in combination.
Project description:we demonstrate that the WEE1 inhibitor AZD1775 triggers endoplasmic reticulum (ER) stress and activates the PERK and IRE1α branches of the unfolded protein response (UPR) in TP53 mutant HGSOC cells. Upon AZD1775 treatment, PERK facilitates apoptotic signaling in these cells via activating CHOP, whereas IRE1α-induced spliced XBP1 (XBP1s) confers survival in response to WEE1 inhibition. Our data uncover an important dual role of UPR in TP53 mutant HGSOC cells in response to AZD1775, where additional inhibition of IRE1α-XBP1s signaling may offer synergistic efficacy.
Project description:Non-small cell lung cancer (NSCLC) with activating mutations in the epidermal growth factor receptor (EGFR) responds to EGFR tyrosine kinase inhibitors such as erlotinib. However, secondary somatic EGFR mutations (e.g. T790M) confer resistance to erlotinib. BMS-690514, a novel panHER/VEGFR inhibitor described here, exerted antiproliferative and pro-apoptotic effects on NSCLC cell lines, with prominent efficacy on H1975 cells expressing the T790M mutation. In this model, BMS-690514 induced a G1 cell cycle arrest, as well as ultrastructural hallmarks of apoptosis, mitochondrial release of cytochrome c, and activation of caspases involved in the intrinsic (e.g. caspase -2, -3, -7 and -9), but not in the extrinsic (e.g. caspase-8) pathway. Caspase inhibition conferred partial protection against BMS-690514 cytotoxicity, pointing to the involvement of both caspase-dependent and -independent effector mechanisms. Transcriptome analyses revealed the upregulation of pro-apoptotic (e.g. Bim, Puma) and cell cycle inhibitory (e.g. p27Kip1, p57Kip2) factors, as well as the downregulation of anti-apoptotic (e.g. Mcl1), heat shock (e.g. HSP40, HSP70, HSP90) and cell cycle promoting (e.g. cyclins B1, D1 and D3, CDK1, MCM family proteins, PCNA) proteins. BMS-690514-induced death of H1975 cells was modified in a unique fashion by a panel of siRNAs targeting apoptosis modulators. Downregulation of components of the NF-kappaB survival pathway (e.g. p65, Nemo/IKK, TAB2) sensitized cells to BMS-690514, whereas knockdown of pro-apoptotic factors (e.g. Puma, Bax, Bak, caspase-2, etc) and DNA damage-related proteins (e.g. ERCC1, hTERT) exerted cytoprotective effects. BMS-690514 is a new pan-HER/VEGFR inhibitor that may become an alternative to erlotinib for the treatment of NSCLC.
Project description:Clusterin (CLU) is a stress-activated molecular chaperone that confers treatment resistance to taxanes when highly expressed. While CLU inhibition potentiates activity of taxanes and other anti-cancer therapies in preclinical models, progression to treatment resistant disease still occurs implicating additional compensatory survival mechanisms. Taxanes are believed to selectively target cells in mitosis, a complex mechanism controlled in part by balancing antagonistic roles of Cdc25C and Wee1 in mitosis progression. Our data indicate that CLU silencing induces a constitutive activation of Cdc25C, which delays mitotic exit and hence sensitizes cancer cells to mitotic-targeting agents such taxanes. Unchecked Cdc25C activation leads to mitotic catastrophe and cell death unless cells upregulate protective mechanisms mediated through the cell cycle regulators Wee1 and Cdc2. In this study we show that CLU silencing induces a constitutive activation of Cdc25C via the phosphatase PP2A but leads to relief of negative feedback inhibition and activation of Wee1-Cdc2 to promote survival and limit therapeutic efficacy. Simultaneous inhibition of CLU-regulated cell cycle effectors, like PP2A and Wee1, may improve synergistic responses of biologically rational combinatorial regimens using taxanes and CLU inhibitors Biological triplicate of PC3 treated with siClusterin were compared to biological trplicate of PC3 treated with siScramblein
Project description:Although inhibitors of the kinases CHK1, ATR and WEE1 are undergoing clinical testing, it remains unclear how these three classes of agents kill susceptible cells and whether they utilize the same cytotoxic mechanism. Here we observed that CHK1 inhibition induces apoptosis in a subset of acute leukemia cell lines, including TP53 null acute myeloid leukemia (AML) and BCR/ABL-positive acute lymphoid leukemia (ALL), in vitro and inhibits leukemic colony formation in clinical AML samples ex vivo. In further studies, CHK1 downregulation or CHK1 inhibitor treatment triggered signaling in sensitive human acute leukemia cell lines that involved CDK2 activation followed by AP1-dependent TNF transactivation, TNF production and engagement of a TNFR1- and BID-dependent apoptotic pathway. AML lines that were intrinsically CHK1 inhibitor resistant exhibited high CHK1 expression and were sensitized by CHK1 downregulation. Signaling through this same CDK2 AP1 TNF cytotoxic pathway was also initiated by ATR or WEE1 inhibitors in vitro and during CHK1 inhibitor treatment of AML xenografts in vivo. Collectively, these observations not only identify new contributors to antileukemic cell action of CHK1, ATR and WEE1 inhibitors, but also delineate a previously undescribed pathway leading from aberrant CDK2 activation to death ligand-induced killing that can potentially be exploited for acute leukemia treatment.
Project description:Purpose: Proficient DNA repair by homologous recombination (HR) facilitates resistance to chemo-radiation in glioma stem cells (GSCs). We evaluated whether compromising HR by targeting HSP90, a molecular chaperone required for the function of key HR proteins, using onalespib, a long-acting, brain-penetrant HSP90 inhibitor, would sensitize high-grade gliomas to chemo-radiation in vitro and in vivoExperimental Design: The ability of onalespib to deplete HR client proteins, impair HR repair capacity, and sensitize GBM to chemo-radiation was evaluated in vitro in GSCs, and in vivo using zebrafish and mouse intracranial glioma xenograft models. The effects of HSP90 inhibition on the transcriptome and cytoplasmic proteins was assessed in GSCs and in ex vivo organotypic human glioma slice cultures.Results: Treatment with onalespib depleted CHK1 and RAD51, two key proteins of the HR pathway, and attenuated HR repair, sensitizing GSCs to the combination of radiation and temozolomide (TMZ). HSP90 inhibition reprogrammed the transcriptome of GSCs and broadly altered expression of cytoplasmic proteins including known and novel client proteins relevant to GSCs. The combination of onalespib with radiation and TMZ extended survival in a zebra fish and a mouse xenograft model of GBM compared to the standard of care (radiation and TMZ) or onalespib with radiation.Conclusions: The results of this study demonstrate that targeting HR by HSP90 inhibition sensitizes GSCs to radiation and chemotherapy and extends survival in zebrafish and mouse intracranial models of GBM. These results provide a preclinical rationale for assessment of HSP90 inhibitors in combination with chemoradiation in GBM patients.
Project description:Current screening modalities for prostate cancer rely on serologic testing for PSA and transrectal biopsy; however, many prostate cancers behave indolently.Because aggressively growing tumors depend on oncogenic drivers, we hypothesized that we could identify early, but aggressive prostate cancer,by an imaging modality targeting Hsp90, a chaperone for many molecules involved in oncogenic signaling. Previously we observedgreater avidity ofa probe,consisting of a near infrared dye tethered to an Hsp90 inhibitor,for cancers with greatermetastatic potential. We now report that an Hsp90 inhibitor-linked near infrared dye with greater tissue penetration could detect prostate cancers in preclinical models and in a phase I human clinical trial. These data, demonstrating specific uptake into aggressive tumors, in conjunction with our prior observations on photodynamic therapy guided by Hsp90 expression support a theranostic approach todetect and treatearly aggressive prostatecancers.
Project description:Patients with small-cell lung cancer (SCLC) are in dire need of more effective therapeutic options. Frequent disruption of the G1 checkpoint in SCLC cells creates a greater dependency of these cells on the G2/M checkpoint to maintain genomic integrity. Indeed, in pre-clinical models, inhibiting the G2/M kinase WEE1 shows promise in inhibiting SCLC growth. However, toxicity and acquired resistance limit the clinical effectiveness of this strategy. Here we conducted CRISPR/Cas9 knockout screens to identify genes influencing the response of SCLC cells to WEE1 kinase inhibition. These screens uncovered a role for the GCN2 amino acid-sensing pathway in modulating the response of SCLC cells to WEE1 inhibition. Rapid activation of GCN2 upon WEE1 inhibition triggers a stress response. Pharmacological activation of the GCN2 pathway synergizes with WEE1 inhibition. Thus, activation of the GCN2 amino acid-sensing pathway represents a novel approach for augmenting the efficacy of WEE1 inhibitors in SCLC.
Project description:Oncogenic KRAS drives cancer growth by activating diverse signaling networks, not all of which have been fully delineated. We set out to establish a system-wide profile of the KRAS-regulated kinase signaling network (kinome) in KRAS-mutant pancreatic ductal adenocarcinoma (PDAC). We knocked down KRAS expression in a panel of six cell lines, and then applied Multiplexed Inhibitor Bead/Mass Spectrometry (MIB/MS) chemical proteomics to monitor changes in kinase activity and/or expression. We hypothesized that depletion of KRAS would result in downregulation of kinases required for KRAS-mediated transforming activities, and in upregulation of other kinases that could potentially compensate for the deleterious consequences of the loss of KRAS. We identified 15 upregulated and 13 downregulated kinases in common across the panel. In agreement with our hypothesis, all 15 of the upregulated kinases have established roles as cancer drivers (e.g., SRC, TGFBR1, ILK), and pharmacologic inhibition of the upregulated kinase, DDR1, suppressed PDAC growth. Interestingly, 11 of the 13 downregulated kinases have established driver roles in cell cycle progression, particularly in mitosis (e.g., WEE1, Aurora A, PLK1). Consistent with a crucial role for the downregulated kinases in promoting KRAS-driven proliferation, we found that pharmacologic inhibition of WEE1 also suppressed PDAC growth. The unexpected paradoxical activation of ERK upon WEE1 inhibition led us to inhibit both WEE1 and ERK concurrently, which caused further potent growth suppression and enhanced apoptotic death than WEE1 inhibition alone. We conclude that system-wide delineation of the KRAS-regulated kinome can identify potential therapeutic targets for KRAS-mutant pancreatic cancer.