STEM-12. THE SMALL MOLECULE DRUG CBL0137 INCREASES THE LEVEL OF DNA DAMAGE AND THE EFFICACY OF RADIOTHERAPY FOR GLIOBLASTOMA

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi23-vi23
Author(s):  
Miranda Tallman ◽  
Abby Zalenski ◽  
Amanda Deighen ◽  
Treg Grubb ◽  
Morgan Schrock ◽  
...  
Keyword(s):  
Dna Damage ◽  
Small Molecule ◽  
Small Population ◽  
Orthotopic Model ◽  
Average Life Expectancy ◽  
Small Molecule Drug ◽  
Specific Cytotoxicity ◽  
Treatment Paradigm ◽  
New Treatment

Abstract Glioblastoma (GBM) is a fatal and incurable brain tumor, with an average life expectancy after diagnosis of only 12-15 months. A main reason for the lethality of GBM is inevitable recurrence, caused by a small population of the tumor cells, called cancer stem cells (CSCs). These cells are aggressive, infiltrative, and resistant to current GBM treatments of chemotherapy and radiotherapy. We use a small molecule drug, CBL0137, which inhibits the FACT (facilitates chromatin transcription) complex leading to cancer cell specific cytotoxicity. Here, we show that CBL0137 sensitized GBM CSCs to radiotherapy and hence lead to increased CSC death and prolonged survival in preclinical models. Clonogenic assays were used to show that CSCs were radiosensitized after CBL0137 treatment. We saw increased DNA damage when GBM CSCs were treated with CBL0137, as well as a decrease in foci resolution over time, when CBL0137 was combined with irradiation. In order to elucidate if the increase in DNA damage was directly due to the inhibition of the FACT complex, we depleted the level of FACT in our GBM CSCs. FACT depletion also led to increased DNA damage, and even more so when combined with irradiation. To validate whether combination therapy sensitized CSCs to radiotherapy in vivo, we used a subcutaneous mouse model and showed combination treatment decreased CSCs frequency in these tumors as well as decreased tumor volume. With an orthotopic model of GBM, we showed that CBL0137 treatment followed by radiotherapy significantly increased survival of mice bearing tumors over either treatment alone. Together, this work establishes a new treatment paradigm for GBM, which sensitizes radio-resistant GBM CSCs to irradiation, a critical component of patient care. Radio-sensitizing agents, including CBL0137, pose an exciting new therapeutic capable of increasing the efficacy of irradiation, by inclusively targeting CSCs.

scholarly journals STEM-26. SMALL MOLECULE DRUG CBL0137 INHIBITS THE FACT COMPLEX AND SENSITIZES GLIOBLASTOMA CANCER STEM CELLS TO RADIOTHERAPY

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii201-ii202
Author(s):  
Miranda Tallman ◽  
Abigail Zalenski ◽  
Amanda Deighen ◽  
Morgan Schrock ◽  
Sherry Mortach ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
High Rate ◽  
Orthotopic Model ◽  
In Vivo Models ◽  
Specific Cytotoxicity ◽  
Treatment Paradigm ◽  
Cancer Agent

Abstract Glioblastoma (GBM) is a malignant brain tumor with nearly universal recurrence. GBM cancer stem cells (CSCs), a subpopulation of radio- and chemo-resistant cancer cells capable of self-renewal, contribute to the high rate of recurrence. The anti-cancer agent, CBL0137, inhibits the FACT (facilitates chromatin transcription) complex leading to cancer cell specific cytotoxicity. Here, we show that CBL0137 sensitized GBM CSCs to radiotherapy using both in vitro and in vivo models. Treatment of CBL0137 combined with radiotherapy led to increased DNA damage in GBM patient specimens and failure to resolve the damage led to decreased cell viability. Using clonogenic assays, we confirmed that CBL0137 radiosensitized the CSCs. To validate that combination therapy impacted CSCs, we used an in vivo subcutaneous model and showed a decrease in the frequency of cancer stem cells present in tumors as well as decreased tumor volume. Using an orthotopic model of GBM, we confirmed that treatment with CBL0137 followed by radiotherapy led to significantly increased survival compared to either treatment alone. Radiotherapy remains a critical component of patient care for GBM, even though there exists a resistant subpopulation. Radio-sensitizing agents, including CBL0137, pose an exciting treatment paradigm to increase the efficacy of irradiation, especially by inclusively targeting CSCs.

scholarly journals STEM-20. RADIO-SENSITIZING GLIOBLASTOMA CANCER STEM CELLS BY INHIBITION OF FACT

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi237-vi238
Author(s):  
Miranda Montgomery ◽  
Abigail Zalenski ◽  
Amanda Deighen ◽  
Sherry Mortach ◽  
Treg Grubb ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Cancer Stem Cells ◽  
Combination Therapy ◽  
High Rate ◽  
Primary Role ◽  
Cancer Cell Growth ◽  
Treatment Paradigm

Abstract Glioblastoma (GBM) has a particularly high rate of recurrence with a 5-year overall survival rate of approximately 5%. This is in part due to a sub-population of cancer stem cells (CSC), which are both radioresistant and chemotherapeutically resistant to conventional treatments. Here we investigated CBL0137, a small molecule form of curaxin, in combination with radiotherapy as a means to radiosensitize CSCs. CBL0137 sequesters FACT (facilitates chromatin transcription) complex to chromatin, which leads to activation of p53 and inhibition of NF-κB. This sequestering of FACT results in cytotoxicity especially within tumor cells and prevents FACT from performing its primary role as a histone chaperone, as well as inhibits its part in the DNA damage response pathway. We show that when combined with radiotherapy, CBL0137 administration limited the ability of CSCs to identify and repair damaged DNA. CSCs treated in vitro with CBL0137 and irradiation showed an increased inhibition of cancer cell growth and decreased viability compared to irradiation or drug alone. Combination therapy also showed more DNA damage in the CSCs than with either agent alone. Based on our in vitro evidence for the efficacy of combination therapy to target CSCs, we moved forward to test the treatment in vivo. Using a subcutaneous model, we show that the amount of CD133+ cells (a marker for GMB CSCs) was reduced in irradiation plus CBL0137 compared to either treatment alone. Survival studies demonstrated that irradiation plus CBL0137 compared to irradiation alone or CBL0137 alone increase lifespan. Here we show the ability of CBL0137, in combination with irradiation, to target patient GBM CSCs both in vitro and in vivo. This work establishes a new treatment paradigm for GBM that inclusively targets CSCs and may ultimately reduce tumor recurrence.

scholarly journals The small molecule drug CBL0137 increases the level of DNA damage and the efficacy of radiotherapy for glioblastoma

2021 ◽  
Vol 499 ◽  
pp. 232-242
Author(s):  
Miranda M. Tallman ◽  
Abigail A. Zalenski ◽  
Amanda M. Deighen ◽  
Morgan S. Schrock ◽  
Sherry Mortach ◽  
...  
Keyword(s):  
Dna Damage ◽  
Small Molecule ◽  
Small Molecule Drug

scholarly journals Targeting Homologous Recombination in Lymphoid Malignancies: Evaluation of Four Small Molecule Inhibitors of RAD51

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2080-2080
Author(s):  
Melinda Day ◽  
Tyler Maclay ◽  
Amber Cyr ◽  
Muneer G Hasham ◽  
Kin-hoe Chow ◽  
...  
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Cell Line ◽  
Genomic Instability ◽  
Small Molecule ◽  
Small Molecule Inhibitors ◽  
Burkitt’S Lymphoma ◽  
Lymphoid Malignancies ◽  
Anti Tumor Activity

Genomic instability is recognized as a driver of tumorigenesis and cancer progression. Loss of tumor suppressors or activation of oncogenes can induce DNA damage stress, promoting genomic instability and creating dependencies upon key DNA repair pathways. These dependencies can be targeted therapeutically to induce synthetic lethality. The homologous recombination (HR) repair pathway is an attractive target. HR deficient cancers are hypersensitive to numerous anticancer drugs, and tumors will often induce expression of HR genes to promote drug resistance. RAD51 is a key component of the HR pathway. RAD51 forms nucleoprotein filaments at sites of DNA damage and replication fork stalls, mediating homologous DNA strand exchange to promote recombinational repair of breaks and damaged replication forks. We utilized four small molecule inhibitors of RAD51-mediated HR for evaluation of RAD51 as a potential therapeutic target. Compounds CYT-0851, CYT-0853, CYT-1027, and CYT-1127 were evaluated for anti-cancer activity in vitro and in vivo. To determine the impact of the small molecules on RAD51 and HR, all four were tested for effects on RAD51 focus formation and sister chromatid exchange (SCE) activity. All the compounds showed a reduction in SCE activity, however only CYT-0851 and CYT-0853 produced a measurable reduction in RAD51 foci. We have previously shown that that RAD51 inhibition leads to accumulation of DNA breaks, and ultimately cell death, in cells expressing the DNA mutator protein Activation Induced Cytidine deaminase (AICDA/AID). Cytotoxicity assays were performed in an AID+ (Daudi, Burkitt's Lymphoma) and AID- (WI-38, fibroblast) cell lines. All four compounds were preferentially active in AID+ cells with little to no cytotoxicity observed in the AID-negative WI-38 cell line. CYT-0853 was the most potent in the Daudi cell line with an EC50 of 8nM. All four compounds were orally bioavailable in all preclinical species tested but showed differences in pharmacokinetics. Preclinical cell line derived xenograft models of AID-high Burkitt's lymphoma (Daudi) and B-cell acute lymphoblastic leukemia (CCRF-SB) were used to determine the in vivo anti-tumor activity of the compounds in lymphoid cancer models. CYT-0851 and CYT-0853 both showed significant anti-tumor activity with tumor growth inhibition of greater than 50% in both models. Further analysis showed drug exposure with CYT-0851 was more consistent in the CDX models than CYT-0853. Overall, these data indicate that RAD51 and HR are attractive therapeutic targets for the treatment of lymphoid malignancies and that CYT-0851 is a viable clinical development candidate. Disclosures Day: Cyteir Therapeutics: Employment. Maclay:Cyteir Therapeutics: Employment. Cyr:Cyteir Therapeutics: Employment. Mills:Cyteir Therapeutics: Employment, Equity Ownership.

scholarly journals CBMT-19. THE ALTERNATIVE LENGTHENING OF TELOMERE (ALT) MECHANISM PROVIDES COLLATERAL SENSITIVITY TO LETHAL TELOMERIC FUSION INDUCED BY TRAPPING PARP INHIBITORS

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi37-vi37
Author(s):  
Joydeep Mukherjee ◽  
Cecelia Dalle-Ore ◽  
Tor-Christian Johanessen ◽  
Ajay Pandita ◽  
Shigeo Ohba ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genomic Dna ◽  
Parp Inhibitors ◽  
Parp Inhibition ◽  
Collateral Sensitivity ◽  
Astrocytoma Cells ◽  
Alternative Lengthening ◽  
New Treatment

Abstract A subset of human tumors, including all IDH1-mutant astrocytomas, use a homologous recombination-based alternative lengthening of telomere (ALT) pathway to resolve telomeric dysfunction in the absence of TERT. Because ALT is not used by normal cells, targeting of the process may provide new therapeutic options for patients with ALT-dependent tumors. We here report that reliance on the ALT mechanism makes tumors collaterally hypersensitive to clinically-available trapping PARPi (t-PARPi). Specifically we noted that astrocytoma cells dependent on the ALT-mechanism (IDH1-mutant and ATRX-deficient genetically-modified human astrocytes and MGG119 PDX) were significantly more sensitive to trapping PARPi than matched ALT-independent isogenic ATRXWT astrocytes and MGG152 PDX cells, respectively) both in vitro and in vivo. Surprisingly this hypersensitivity was not associated with BRCA-ness, the extent of PARP inhibition, or with t-PARPi-created genomic DNA damage as is the case in most PARPi-sensitive populations. Rather the enhanced activity of t-PARPi in ALT-dependent cells was associated with a novel t-PARPi-induced, lethal telomere fusion. Furthermore, the extent of chromosomal fusion was proportional to the PARP-trapping ability of the five PARP inhibitors tested, and could be prevented by exogenous expression of TERT, which eliminated reliance on ALT but did not alter levels of PARPi-induced genomic DNA damage. The extent of tPARPi-induced telomeric fusion in ALT-dependent cells, which could be directly measured in small amounts of DNA using a q-PCR approach, was also directly proportional to tPARPi-induced cell death in vitro and to prolonged survival of tumor-bearing mice in vivo. These results therefore identify clinically available tPARPi as a new treatment modality for a select and easily genetically definable group of ALT tumors, and also define telomeric fusion as a biomarker of drug action in these tumors.

scholarly journals Study on the mechanism of multi-AGC kinase AT13148 on Notch signaling pathway in glioblastoma

2021 ◽  
Author(s):  
Yanan Li ◽  
Guosheng Han ◽  
Weijie Min ◽  
Mengmeng Li ◽  
Maomao Wang ◽  
...  
Keyword(s):  
Western Blot ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Small Molecule ◽  
Notch Signaling Pathway ◽  
Small Molecule Drug ◽  
Mrna And Protein Expression ◽  
U87 Cells ◽  
Proliferation And Invasion

IntroductionGlioblastoma is the most malignant astrocytoma, and its therapeutic effect is not ideal. Notch signaling pathway plays an important role in tumor proliferation and invasion. Whether small molecule drug AT13148 can affect glioblastoma by regulating Notch signaling pathway is the focus of this study.Material and methodsIn vitro, glioblastoma U87 cell line transfected with sh-ITGB1 (U87sh-ITGB1), U87 cell line transfected with oe-ITGB1 (U87oe-ITGB1) and control group were treated with a small molecular drug AT13148. RT-qPCR, western-blot and clone formation ability assays were used to detect the mRNA and protein expression of the ITGB1 and the key gene NOTCH1, as well as the proliferation of cancer cells. Therapeutic effects of AT13148 were examined in vivo using a nude mice model of U87 cells. After treatment with AT13148, volume of tumors were calculated, and RT-qPCR and western-blot were used to evaluate the mRNA and protein expression of the ITGB1 and NOTCH1.ResultsAT13148 inhibits the activity of U87 cells. Lentiviral transfection of sh-ITGB1 and oe-ITGB1 can interfere with the expression of ITGB1 in U87 cells. AT13148 could down-regulate both the expression of ITGB1 and NOTCH1. Moreover, AT13148 affects the cloning ability of U87 cells. AT13148 can also inhibit the proliferation of U87 cells. Furthermore, AT13148 inhibited the proliferation and invasion of transplanted tumors in vivo.ConclusionsThis study indicated that AT13148 could affect the expression of ITGB1 and NOTCH1, which also could be a potential potential anti-glioblastoma small molecule drug candidate in clinic medicine.

Sign in / Sign up

Export Citation Format

Share Document