bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 3832: Apoptotic and cell cycle effects of triterpenes isolated from Phoradendron wattii on a chronic myelogenous leukemia cell line
Authors: Moo-Puc Rosa E. , Sauri Shirley A. Calderón , Villanueva-Toledo Jairo R. , Peraza-Sánchez Sergio R. , Chávez-González Antonieta 
Published: April 2023

Abstract
Introduction: Medicinal plants have been used in traditional medicine practices since ancient times. Mayan traditional medicine uses herbs as treatment to illness that can be related to cancer disease such as Phoradendron wattii. As part of the search for novel cancer treatment two triterpene compounds were isolated from P. wattii: 3-epi-betulinic acid and lupenone with preliminary activity on leukemias. We investigated the cancer treatment abilities of 3-epi-betulinic acid and lupenone on human chronic myelogenous leukemia (K562) cell line and monocytes isolated from peripheral blood using flow cytometry methods.
Results: Lupenone showed low effect on both cells with an IC50 of 177.60 ± 5.07 µg/mL and a selectivity index (SI) of 0.10 times more on K-562 cell line than on monocytes. Nevertheless, 3-epi-betulinic acid showed a moderate anti-CML activity with an IC50 of 38.74 ± 5.07 µg/mL, having a SI of 4.10 on K-562 cells when compared to monocytes. These results indicate that 3-epi-betulinic acid was 41 times more selective for K-562 cell line than lupenone and it also was 7.45 more selective than etoposide as positive control. Additionally, 3-epi-betulinic acid increased cell population in the G0/G1 phase of the cell cycle and apoptotic cells, and it inhibited cell proliferation in a dose-dependent manner. Furthermore, the relative expression of genes associated with apoptosis Bax and caspase 3 increased compared to control.
Conclusion: Combined, these results suggest that 3-epi-betulinic acid plays an important regulatory role of cell cycle and apoptosis. Finally, the 3-epi-betulinic acid investigated in this work is potentially a cheap, safe, and effective alternative to chemotherapy in cancer treatment.
Citation Format: Rosa E. Moo-Puc, Shirley A. Calderón Sauri, Jairo R. Villanueva-Toledo, Sergio R. Peraza-Sánchez, Antonieta Chávez-González. Apoptotic and cell cycle effects of triterpenes isolated from Phoradendron wattii on a chronic myelogenous leukemia cell line. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3832.
Abstract 3842: Berberine recognition of the dGMP-bound PDGFR-β promoter G-quadruplex: Structural insight into specific drug targeting
Authors: Wang Kai-Bo , Dickerhoff Jonathan , Han Yichen , Yang Danzhou 
Published: April 2023

Abstract
PDGFR-β (Platelet-Derived Growth Factor Receptor beta) is a receptor tyrosine kinase whose overexpression drives the progression and metastasis of many cancers. It is an established anticancer target and PDGFR-β inhibition via kinase inhibitors has been actively sought-after. However, PDGFR-β kinase inhibitors often lack specificity. The PDGFR-β gene promoter forms DNA G-quadruplexes that are transcription silencer whose stabilization by small molecules represses PDGFR-β expression. Therefore, targeting PDGFR-β promoter G-quadruplexes for transcriptional silencing is a promising alternative strategy for cancer therapy. G-quadruplex is an exciting family of non-canonical DNA secondary structures. DNA G-quadruplex within the PDGFR-β gene promoter forms novel vacancy pockets (vG4) that can be filled-in by guanine metabolites such as dGMP and cGMP. This presents an attractive target for small molecule targeting. Herein, we present the binding of the natural product berberine with the unique PDGFR-β dGMP-vG4 binary complex to form a novel ternary complex, the first case observed in DNA G-quadruplexes. Using circular dichroism, fluorescence, and nuclear magnetic resonance (NMR) spectroscopy, we demonstrated that berberine binds with high affinity and strongly stabilizes the dGMP-fill-in PDGFR-β vG4. Our determined high-resolution NMR structure of this ternary complex in K+-containing solution reveals a 2:1 binding stoichiometry of berberine to the dGMP-fill-in PDGFR-β vG4. Significantly, one berberine directly stacks upon and extensively covers the dGMP. This direct binding mode provides structural basis for targeting the unique PDGFR-β promoter G-quadruplex by small molecules and suggests an intriguing strategy of designing drug-like, guanine-conjugated molecules to selectively silence the PDGFR-β gene. Because vG4 formation and dGMP fill-in is a unique property of the PDGFR-β promoter G-quadruplex, our study provides a structural basis for rationally designing small molecule drugs to specifically target the PDGFR-β promoter G-quadruplex to inhibit oncogenic PDGFR-β for cancer therapeutics.
Citation Format: Kai-Bo Wang, Jonathan Dickerhoff, Yichen Han, Danzhou Yang. Berberine recognition of the dGMP-bound PDGFR-β promoter G-quadruplex: Structural insight into specific drug targeting. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3842.
Abstract 3843: Potent human ClpP protease agonists with anticancer properties bind the enzyme with improved structural complementarity and alter the mitochondrial N-terminome
Authors: Mabanglo Mark F. , Wong Keith S. , Barghash Marim M. , Graves Lee M. , Iwanowicz Edwin J. , Houry Walid A. 
Published: April 2023

Abstract
The mitochondrial ClpP protease is responsible for mitochondrial protein quality control through specific degradation of proteins involved in several metabolic processes. ClpP overexpression is also required in many cancer cells to eliminate ROS-damaged proteins and to sustain oncogenesis. Targeting ClpP to dysregulate its function using small molecule agonists is a novel strategy in cancer therapy. Here, we synthesized novel imipridone-derived compounds and related chemicals, which we characterized using biochemical, biophysical, and cellular studies. Using X-ray crystallography, we found that these compounds have enhanced binding affinities due to their greater shape and charge complementarity with the surface hydrophobic pockets of ClpP. N-terminome profiling of cancer cells upon treatment with one of these compounds revealed the global proteomic changes that arise and identified the structural motifs preferred for protein cleavage by compound-activated ClpP. Together, our studies provide the structural and molecular bases by which dysregulated ClpP affects cancer cell viability and proliferation.
Citation Format: Mark F. Mabanglo, Keith S. Wong, Marim M. Barghash, Lee M. Graves, Edwin J. Iwanowicz, Walid A. Houry. Potent human ClpP protease agonists with anticancer properties bind the enzyme with improved structural complementarity and alter the mitochondrial N-terminome. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3843.
Abstract 3851: Targeting RET solvent-front mutants with an alkynyl nicotinamide-based inhibitor
Authors: Khatri Ujjwol , Dayal Neetu , Hu Xueqing , Larocque Elizabeth , Naganna Nimishetti , Shen Tao , Liu Xuan , Holtsberg Frederick W. , Aman M. Javad , Sintim Herman O. , Wu Jie 
Published: April 2023

Abstract
Selpercatinib (LOXO-292, LY3527723) and pralsetinib (BLU-667) are first-in-class RET-targeted cancer therapy drugs. However, secondary RET mutations that confer selpercatinib/pralsetinib resistance have been identified, necessitating development of next-generation RET Tyrosine kinase inhibitors (TKIs). While the G810C/R/S/V mutations located at the RET kinase solvent-front site were detected in selpercatinib-treated patients, it was unclear whether all of these and other potential G810 mutants are resistant to selpercatinib and pralsetinib. We profiled selpercatinib and pralsetinib on all six possible G810 mutants derived from single nucleotide substitution. Surprisingly, the G810V mutant found in a clinical study was not resistant to selpercatinib or pralsetinib. Besides G810C/R/S, G810D also conferred selpercatinib/pralsetinib resistance. We found that alkynyl nicotinamide compounds such as HSN608 have better drug-like properties than alkynyl benzamides. HSN608 inhibited RET and RET V804M gatekeeper mutant, and all six G810 mutants with low nanomolar IC50s in the BaF3/KIF5B-RET mutant cell model. In cell derived xenograft (CDX) tumors driven by KIF5B-RET(G810C), HSN608 caused regression of the selpercatinib-resistant tumors. This study clarifies the sensitivities of different RET solvent-front mutants to selpercatinib and pralsetinib, and identifies an alkylnyl nicotinamide-based RET TKI for inhibiting selpercatinib/pralsetinib-resistant G810 mutants.
Citation Format: Ujjwol Khatri, Neetu Dayal, Xueqing Hu, Elizabeth Larocque, Nimishetti Naganna, Tao Shen, Xuan Liu, Frederick W. Holtsberg, M. Javad Aman, Herman O. Sintim, Jie Wu. Targeting RET solvent-front mutants with an alkynyl nicotinamide-based inhibitor. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3851.
Abstract 3933: RRM2 inhibition by COH29 is a potential therapeutic strategy for atypical teratoid rhabdoid tumors
Authors: Giang Le Hien , Wong Tai-Tong , Chang Che-Chang 
Published: April 2023

Abstract
Introduction: Atypical teratoid rhabdoid tumors (ATRT) are a rare but aggressive malignancy in central nervous system, commonly occurring in early childhood. ATRT patients face a dismal prognosis despite aggressive therapy. Development of both effective and protective targeted therapy is an emerging necessity. It has been reported that RRM2 is a master driver of aggressiveness and a poor prognosis biomarker in several cancers. However, little is known about RRM2 function in ATRT. The aim of this study is to assess the roles of RRM2 in ATRT and elucidate the therapeutic potential of RRM2 to cure the ATRT.
Methods: Expression of RRM2 was evaluated by molecular profiling analysis and was confirmed by IHC in both ATRT patients and PDX tissues. Follow-up in vitro studies used 3 different cell lines to elucidate the oncogenic role of RRM2 in ATRT cells. The efficacy of COH29, an RRM2 inhibitor, was assessed in vitro. ATRT model of SCID mice orthotopically injected with ATRT cells were used to test the efficiency of COH29 for in vivo. Western blot and RNA-sequencing were used to determine the mechanisms of RRM2 transcriptional activation in ATRT.
Results: Molecular profiling results revealed that RRM2 was relatively highly expressed in ATRT tissues and cell lines. Clinical relevance analysis results showed that the RRM2 expression level was associated with poor prognosis among ATRT patients. Knockdown of RRM2 by shRNAs significantly reduced ATRT cells colonies formation, proliferation and migration. A similar but more pronounced inhibitory effect was observed when COH29 was used to target RMM2. Inhibition of RRM2 by shRNAs or COH29 significantly induced cell death via DNA damage and/or apoptosis pathways. In vivo results demonstrated that COH29 could suppressed ATRT tumor growth and extend mice overall survival.
Conclusion: Our study identified RRM2 as a potential mediator of oncogenic cellular functions in ATRT cell lines. We propose that highly expressed RRM2 is associated with poor patient outcomes, and inhibition of RRM2 by COH29 may present a significant therapeutic value in ATRT.
Citation Format: Le Hien Giang, Tai-Tong Wong, Che-Chang Chang. RRM2 inhibition by COH29 is a potential therapeutic strategy for atypical teratoid rhabdoid tumors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3933.
Abstract 3939: Inhibition of USP7 upregulates USP22 through desuppression of transcriptional activity of Sp1 in human cancer cells
Authors: Zhang Keqiang , Sun Ting , Li Wendong , Wu Jun , Raz Dan 
Published: April 2023

Abstract
Deubiquitinases (DUBs) play important roles in various human cancers and targeting DUBs is considered as a novel anticancer therapeutic strategy. Overexpression of ubiquitin specific protease 7 and 22 (USP7 and USP22) are associated with malignancy, therapy resistance, and poor prognosis in many cancers. Although both DUBs are involved in the regulation of similar genes and signaling pathways, such as histone H2B monoubiquitination (H2Bub1), c-Myc, FOXP3, and P53, the interdependence of USP22 and USP7 expression has never been described. In the study, we found targeting USP7 via either siRNA-mediated knockdown or pharmaceutical inhibitors dramatically upregulates USP22 in cancer cells. Mechanistically, the elevated USP22 occurs through a transcriptional pathway, possibly due to desuppression of the transcriptional activity of SP1 via promoting its degradation upon USP7 inhibition. Importantly, the elevated USP22 leads to significant activation of downstream signal pathways including H2Bub1 and c-Myc, which may potentially enhance cancer malignancy and counteract the anticancer efficacy of USP7 inhibition. Importantly, targeting USP7 further suppresses the in vitro proliferation of USP22-knockout (USP22-Ko) A549 and H1299 lung cancer cells and induces a stronger activation of P53 tumor suppressor signaling pathway. In addition, USP22-Ko cancer cells are more sensitive to a combination of cisplatin and USP7. USP7 inhibitor treatment further suppresses the in vivo angiogenesis and growth and induced more apoptosis in USP22-Ko cancer xenografts. Taken together, our findings demonstrate that USP7 inhibition can dramatically upregulate USP22 in cancer cells; and targeting USP7 and USP22 may represent a more effective approach for targeted cancer therapy, which warrants further study.
Citation Format: Keqiang Zhang, Ting Sun, Wendong Li, Jun Wu, Dan Raz. Inhibition of USP7 upregulates USP22 through desuppression of transcriptional activity of Sp1 in human cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3939.
Abstract 3948: DDX5 helicase resolves G-quadruplex and transactivates MYC expression
Authors: Wu Guanhui , Xing Zheng , Chen Luying , Tran Elizabeth J. , Yang Danzhou 
Published: April 2023

Abstract
DDX5 (DEAD-box protein 5) plays an important role in cell proliferation, differentiation, and tumorigenesis. DDX5 is a founding member of the DEAD-box RNA helicase family and known as a non-processive RNA helicase. It acts as a transcriptional co-activator of many cancer-associated genes, such as MYC, however, the underlying molecular mechanism is unknown. MYC is one of the most critical oncogenes and has a DNA G-quadruplex in its proximal promoter region (MycG4) that functions as transcriptional silencer. Guanine-rich DNA and RNA sequences can form G-quadruplex, a non-canonical secondary structure. However, MycG4 is highly stable and its regulatory role in transcription requires active unfolding. Here, we report that DDX5 unfolds MycG4 with extreme efficiency, and thereby transactivates MYC expression. To understand the effects of DDX5 on MycG4, we characterized the unfolding of MycG4-DNA within the DDX5-MycG4 complex using DNA footprinting, FRET and CD spectroscopy. While DDX5 is known as a dsRNA helicase, our results showed that DDX5 is a highly active DNA G4-resolvase. Strikingly, MycG4 unfolding requires neither ATP hydrolysis nor extended loading of single-stranded flanking. Our protein-binding-ELISA experiments revealed specific and high-affinity binding of DDX5 to G4 structures regardless of whether the substrate is DNA or RNA. To elucidate the cellular functions of DDX5, we analyzed publicly available DDX5 ChIP-seq data and identified G-rich sequences in cancer cells as chromatin binding sites of DDX5. Moreover, our ChIP and Western Blot results showed that DDX5 is enriched at the MYC promoter and activates MYC transcription. Importantly, G-quadruplex interactive small molecules can inhibit the DDX5 interaction with the promoter MycG4 and DDX5-mediated transcriptional activation of the MYC gene. In addition, knock-down of DDX5 expression with DDX5-specific siRNA in cancer cells resulted in downregulation of MYC expression and sensitization to G4-interactive small molecules. In summary, we identified resolving DNA and RNA G-quadruplexes as novel function of DDX5. Our results establish that the MYC-transactivation by DDX5 is mediated through unfolding of the MYC promoter quadruplex and thereby establish a new molecular target to suppress MYC for cancer intervention.
Citation Format: Guanhui Wu, Zheng Xing, Luying Chen, Elizabeth J. Tran, Danzhou Yang. DDX5 helicase resolves G-quadruplex and transactivates MYC expression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3948.
Abstract 395: Resistance to tyrosine kinase inhibitor confers an immunosuppressive microenvironment and cross-resistance to immunotherapy through AXL/PDPK1 axis in liver cancer
Authors: Xie Yunong , Huang Bosheng , Yu Huajian , Loh Jia-Jian , Leung Rainbow Wing-Hei , Lee Terence , Ma Stephanie , Tong Man 
Published: April 2023

Abstract
Systemic therapy is the current standard of care for unresectable advanced hepatocellular carcinoma (HCC), the most malignant form of liver cancer. Clinical practice guideline for HCC includes the management of the second-line immunotherapies after patients become unresponsive to first-line targeted therapies using tyrosine kinase inhibitors (TKI), which is expected to generate optimal therapeutic effect due to the distinct mechanism of action between TKIs and immunotherapies. However, evidence from clinical trials suggests that the response to immunotherapy following TKI treatment is often compromised in TKI-resistant HCC as compared with treatment-naïve HCC, indicating a potential cross-resistance to immunotherapy, which impedes the optimal therapeutic effect of the second-line immunotherapies. In the present study, we first explored the therapeutic effect of anti-PD-1 immunotherapy in TKI-resistant HCC and successfully validated the putative cross-resistance to immunotherapy after TKI treatment. We further observed that TKI-resistant HCC exhibits an immune-evasive microenvironment, characterized by decreased CD8+ T cell and dendritic cell infiltration. This is potentially caused by the intratumoral activation of receptor tyrosine kinase AXL and its downstream target PDPK1 which protect TKI-resistant HCC cells from mitochondrial oxidative stress and the cytosolic leakage of mitochondrial DNA, which subsequently suppresses cGAS-STING together with its downstream interferon pathways and immunogenic cell death. Genetic manipulation of AXL and PDPK1 in TKI-resistant HCC cells abrogated the protective effect and thus activated the immunogenic responses. Blockade of AXL with a selective inhibitor BGB324 re-sensitized TKI-resistant HCC to anti-PD-1 treatment. The current findings suggest that targeting AXL/PDPK1 signaling axis might overcome cross-resistance to second-line immunotherapy for HCC patients who progress on TKI treatment.
Citation Format: Yunong Xie, Bosheng Huang, Huajian Yu, Jia-Jian Loh, Rainbow Wing-Hei Leung, Terence Lee, Stephanie Ma, Man Tong. Resistance to tyrosine kinase inhibitor confers an immunosuppressive microenvironment and cross-resistance to immunotherapy through AXL/PDPK1 axis in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 395.
Abstract 3967: CRISPR/Cas9 screening identified novel membrane targets sensitizing hepatocellular carcinoma cells to natural killer cell-mediated cytotoxicity
Authors: Li Shuo , Han Lin , Zhang Siyao , Geng Guangfeng , Huo Lei , Huang Dawei , He Zhaoren , Li Shuoran , Jiang Zhaoshi , Rong James X. 
Published: April 2023

Abstract
Natural killer cells (NK) play a central role in cancer immune surveillance by directly killing cancer cells and producing pro-inflammatory cytokines to stimulate and recruit other immune cells to elaborate long-lasting anti-tumor responses. However, little is known about the immune escape mechanisms and regulatory proteins, particularly those for NK, involved in hepatocellular carcinoma (HCC), one of the most common and lethal cancers. To identify the determinants of NK killing function, we performed an HCC cell line-based CRISPR/Cas9 loss-of-function genetic screen, using a human whole membrane protein library containing ~7000 genes curated from 3 public membrane protein datasets. The human SNU449 was chosen as a representative HCC cell line for CRISPR/Cas9 editing based on the genetic profile analysis, representing one HCC patient subpopulation (&gt; 30%) in the TCGA cohort. The cell line was incubated with NK92 cells at ratios of 2:1, 1:1, and 0.5:1. Bioinformatics methods for prioritizing genes (e.g., MAGeCK) were applied on 3 tested groups with different ratios. Single guide RNAs targeting genes in the antigen presentation machinery were depleted, including HLA-C, B2M, and TAP1/2, whereas components of the tumor-immune synapse, such as NCR3LG1 and ICAM1, were enriched, confirming the validity of the screen. SLC33A1 (an endosomal acetylCoA transporter) and SLC31A1 (the major copper influx transporter) were also depleted, previously unknown as NK regulators. The effects of SLC33A1 and SLC31A1 were validated in individual gene knockout cells generated respectively by lentiviral sgRNA expression. Furthermore, knockout of either transporter in SNU449 cells increased IFNγ secretion, confirming NK92 activation. Our results revealed that CRISPR/Cas9-based functional genomics screens in HCC cell lines could identify novel targets modulating NK-mediated killing. Further analysis of mechanisms of action, and particularly functional validation in in vivo systems, will potentially provide novel targets for the treatment of HCC.
Citation Format: Shuo Li, Lin Han, Siyao Zhang, Guangfeng Geng, Lei Huo, Dawei Huang, Zhaoren He, Shuoran Li, Zhaoshi Jiang, James X. Rong. CRISPR/Cas9 screening identified novel membrane targets sensitizing hepatocellular carcinoma cells to natural killer cell-mediated cytotoxicity. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3967.