bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Inhibition of Melanoma Cell–Intrinsic Tim-3 Stimulates MAPK-Dependent Tumorigenesis
Authors: Schatton Tobias , Itoh Yuta , Martins Christina , Rasbach Erik , Singh Praveen , Silva Mariana , Mucciarone Kyla , Heppt Markus V. , Geddes-Sweeney Jenna , Stewart Kate , Brandenburg Anne , Liang Jennifer , Dimitroff Charles J. , Mihm Martin C. , Landsberg Jennifer , Schlapbach Christoph , Lian Christine G. , Murphy George F. , Kupper Thomas S. , Ramsey Matthew R. , Barthel Steven R.
Published: March 2024

Abstract
T-cell immunoglobulin mucin family member 3 (Tim-3) is an immune checkpoint receptor that dampens effector functions and causes terminal exhaustion of cytotoxic T cells. Tim-3 inhibitors are under investigation in immuno-oncology (IO) trials, because blockade of T-cell-Tim-3 enhances antitumor immunity. Here, we identify an additional role for Tim-3 as a growth-suppressive receptor intrinsic to melanoma cells. Inhibition of melanoma cell-Tim-3 promoted tumor growth in both immunocompetent and immunocompromised mice, while melanoma-specific Tim-3 overexpression attenuated tumorigenesis. Ab-mediated Tim-3 blockade inhibited growth of immunogenic murine melanomas in T-cell–competent hosts, consistent with established antitumor effects of T-cell-Tim-3 inhibition. In contrast, Tim-3 Ab administration stimulated tumorigenesis of both highly and lesser immunogenic murine and human melanomas in T-cell–deficient mice, confirming growth-promoting effects of melanoma-Tim-3 antagonism. Melanoma-Tim-3 activation suppressed, while its blockade enhanced, phosphorylation of pro-proliferative downstream MAPK signaling mediators. Finally, pharmacologic MAPK inhibition reversed unwanted Tim-3 Ab-mediated tumorigenesis in T-cell–deficient mice and enhanced desired antitumor activity of Tim-3 interference in T-cell–competent hosts. These results identify melanoma-Tim-3 blockade as a mechanism that antagonizes T-cell-Tim-3–directed IO therapeutic efficacy. They further reveal MAPK targeting as a combination strategy for circumventing adverse consequences of unintended melanoma-Tim-3 inhibition.
Significance:
Tim-3 is a growth-suppressive receptor intrinsic to melanoma cells, the blockade of which promotes MAPK-dependent tumorigenesis and thus counteracts antitumor activity of T-cell–directed Tim-3 inhibition.
Data from Disruption of the Gut Microbiota Confers Cisplatin Resistance in Epithelial Ovarian Cancer
Authors: Chambers Laura M. , Esakov Rhoades Emily L. , Bharti Rashmi , Braley Chad , Tewari Surabhi , Trestan Lexie , Alali Zahraa , Bayik Defne , Lathia Justin D. , Sangwan Naseer , Bazeley Peter , Joehlin-Price Amy S. , Wang Zeneng , Dutta Sumita , Dwidar Mohammed , Hajjar Adeline , Ahern Philip P. , Claesen Jan , Rose Peter , Vargas Roberto , Brown J. Mark , Michener Chad M. , Reizes Ofer
Published: March 2024

Abstract
Epithelial ovarian cancer (EOC) is the leading cause of gynecologic cancer death. Despite initial responses to intervention, up to 80% of patient tumors recur and require additional treatment. Retrospective clinical analysis of patients with ovarian cancer indicates antibiotic use during chemotherapy treatment is associated with poor overall survival. Here, we assessed whether antibiotic (ABX) treatment would impact growth of EOC and sensitivity to cisplatin. Immunocompetent or immunocompromised mice were given untreated control or ABX-containing (metronidazole, ampicillin, vancomycin, and neomycin) water prior to intraperitoneal injection with EOC cells, and cisplatin therapy was administered biweekly until endpoint. Tumor-bearing ABX-treated mice exhibited accelerated tumor growth and resistance to cisplatin therapy compared with control treatment. ABX treatment led to reduced apoptosis, increased DNA damage repair, and enhanced angiogenesis in cisplatin-treated tumors, and tumors from ABX-treated mice contained a higher frequency of cisplatin-augmented cancer stem cells than control mice. Stool analysis indicated nonresistant gut microbial species were disrupted by ABX treatment. Cecal transplants of microbiota derived from control-treated mice was sufficient to ameliorate chemoresistance and prolong survival of ABX-treated mice, indicative of a gut-derived tumor suppressor. Metabolomics analyses identified circulating gut-derived metabolites that were altered by ABX treatment and restored by recolonization, providing candidate metabolites that mediate the cross-talk between the gut microbiome and ovarian cancer. Collectively, these findings indicate that an intact microbiome functions as a tumor suppressor in EOC, and perturbation of the gut microbiota with ABX treatment promotes tumor growth and suppresses cisplatin sensitivity.
Significance:
Restoration of the gut microbiome, which is disrupted following antibiotic treatment, may help overcome platinum resistance in patients with epithelial ovarian cancer.

See related commentary by Hawkins and Nephew, p. 4511
Data from SMG8/SMG9 Heterodimer Loss Modulates SMG1 Kinase to Drive ATR Inhibitor Resistance
Authors: Llorca-Cardenosa Marta J. , Aronson Lauren I. , Krastev Dragomir B. , Nieminuszczy Jadwiga , Alexander John , Song Feifei , Dylewska Malgorzata , Broderick Ronan , Brough Rachel , Zimmermann Astrid , Zenke Frank T. , Gurel Bora , Riisnaes Ruth , Ferreira Ana , Roumeliotis Theodoros , Choudhary Jyoti , Pettitt Stephen J. , de Bono Johann , Cervantes Andres , Haider Syed , Niedzwiedz Wojciech , Lord Christopher J. , Chong Irene Y.
Published: March 2024

Abstract
Gastric cancer represents the third leading cause of global cancer mortality and an area of unmet clinical need. Drugs that target the DNA damage response, including ATR inhibitors (ATRi), have been proposed as novel targeted agents in gastric cancer. Here, we sought to evaluate the efficacy of ATRi in preclinical models of gastric cancer and to understand how ATRi resistance might emerge as a means to identify predictors of ATRi response. A positive selection genome-wide CRISPR-Cas9 screen identified candidate regulators of ATRi resistance in gastric cancer. Loss-of-function mutations in either SMG8 or SMG9 caused ATRi resistance by an SMG1-mediated mechanism. Although ATRi still impaired ATR/CHK1 signaling in SMG8/9-defective cells, other characteristic responses to ATRi exposure were not seen, such as changes in ATM/CHK2, γH2AX, phospho-RPA, or 53BP1 status or changes in the proportions of cells in S- or G2–M-phases of the cell cycle. Transcription/replication conflicts (TRC) elicited by ATRi exposure are a likely cause of ATRi sensitivity, and SMG8/9-defective cells exhibited a reduced level of ATRi-induced TRCs, which could contribute to ATRi resistance. These observations suggest ATRi elicits antitumor efficacy in gastric cancer but that drug resistance could emerge via alterations in the SMG8/9/1 pathway.
Significance:
These findings reveal how cancer cells acquire resistance to ATRi and identify pathways that could be targeted to enhance the overall effectiveness of these inhibitors.
Data from Doxorubicin-Loaded Polymeric Meshes Prevent Local Recurrence after Sarcoma Resection While Avoiding Cardiotoxicity
Authors: Bressler Eric M. , Chu Ngoc-Quynh , Sabatelle Robert C. , Mahvi David A. , Korunes-Miller Jenny T. , Nagashima Fumiaki , Ichinose Fumito , Liu Rong , Grinstaff Mark W. , Colson Yolonda L. , Raut Chandrajit P.
Published: March 2024

Abstract
Surgery is the only potentially curative treatment for localized soft-tissue sarcomas. However, for sarcomas arising in the retroperitoneum, locoregional recurrence rates are 35% to 59% despite resection. Doxorubicin (DOX) is the standard first-line systemic chemotherapy for advanced soft-tissue sarcoma, yet its intravenous administration yields limited clinical efficacy and results in dose-limiting cardiotoxicity. We report the fabrication and optimization of a novel electrospun poly(caprolactone) (PCL) surgical mesh coated with layers of a hydrophobic polymer (poly(glycerol monostearate-co-caprolactone), PGC-C18), which delivers DOX directly to the operative bed following sarcoma resection. In xenograft models of liposarcoma and chondrosarcoma, DOX-loaded meshes (DoM) increased overall survival 4-fold compared with systemically administered DOX and prevented local recurrence in all but one animal. Importantly, mice implanted with DoMs exhibited preserved cardiac function, whereas mice receiving an equivalent dose systemically displayed a 23% decrease from baseline in both cardiac output and ejection fraction 20 days after administration. Collectively, this work demonstrates a feasible therapeutic approach to simultaneously prevent post-surgical tumor recurrence and minimize cardiotoxicity in soft-tissue sarcoma.
Significance:
A proof-of-principle study in animal models shows that a novel local drug delivery approach can prevent tumor recurrence as well as drug-related adverse events following surgical resection of soft-tissue sarcomas.
Data from KDM6A Loss Recruits Tumor-Associated Neutrophils and Promotes Neutrophil Extracellular Trap Formation in Pancreatic Cancer
Authors: Yang Jing , Jin Lin , Kim Hong Sun , Tian Feng , Yi Zhujun , Bedi Karan , Ljungman Mats , Pasca di Magliano Marina , Crawford Howard , Shi Jiaqi
Published: March 2024

Abstract
Lysine (K)-specific demethylase 6A (KDM6A) is a frequently mutated tumor suppressor gene in pancreatic ductal adenocarcinoma (PDAC). However, the impact of KDM6A loss on the PDAC tumor immune microenvironment is not known. This study used a genetically engineered, pancreas-specific Kdm6a knockout (KO) PDAC mouse model and human PDAC tissue samples to demonstrate that KDM6A loss correlates with increased tumor-associated neutrophils and neutrophil extracellular traps (NET) formation, which are known to contribute to PDAC progression. Genome-wide bromouridine sequencing analysis to evaluate nascent RNA synthesis showed that the expression of many chemotactic cytokines, especially CXC motif chemokine ligand 1 (CXCL1), was upregulated in KDM6A KO PDAC cells. KDM6A-deficient PDAC cells secreted higher levels of CXCL1 protein, which in turn recruited neutrophils. Furthermore, in a syngeneic orthotopic mouse model, treatment with a CXCL1 neutralizing antibody blocked the chemotactic and NET-promoting properties of KDM6A-deficient PDAC cells and suppressed tumor growth, confirming CXCL1 as a key mediator of chemotaxis and PDAC growth driven by KDM6A loss. These findings shed light on how KDM6A regulates the tumor immune microenvironment and PDAC progression and suggests that the CXCL1–CXCR2 axis may be a candidate target in PDAC with KDM6A loss.
Significance:
KDM6A loss in pancreatic cancer cells alters the immune microenvironment by increasing CXCL1 secretion and neutrophil recruitment, providing a rationale for targeting the CXCL1–CXCR2 signaling axis in tumors with low KDM6A.
Data from Antisense RNAs Influence Promoter Usage of Their Counterpart Sense Genes in Cancer
Authors: Bellido Molias Fernando , Sim Andre , Leong Ka Wai , An Omer , Song Yangyang , Ng Vanessa Hui En , Lim Max Wei Jie , Ying Chen , Teo Jasmin Xin Jia , Göke Jonathan , Chen Leilei
Published: March 2024

Abstract
Multiple noncoding natural antisense transcripts (ncNAT) are known to modulate key biological events such as cell growth or differentiation. However, the actual impact of ncNATs on cancer progression remains largely unknown. In this study, we identified a complete list of differentially expressed ncNATs in hepatocellular carcinoma. Among them, a previously undescribed ncNAT HNF4A-AS1L suppressed cancer cell growth by regulating its sense gene HNF4A, a well-known cancer driver, through a promoter-specific mechanism. HNF4A-AS1L selectively activated the HNF4A P1 promoter via HNF1A, which upregulated expression of tumor suppressor P1-driven isoforms, while having no effect on the oncogenic P2 promoter. RNA-seq data from 23 tissue and cancer types identified approximately 100 ncNATs whose expression correlated specifically with the activity of one promoter of their associated sense gene. Silencing of two of these ncNATs ENSG00000259357 and ENSG00000255031 (antisense to CERS2 and CHKA, respectively) altered the promoter usage of CERS2 and CHKA. Altogether, these results demonstrate that promoter-specific regulation is a mechanism used by ncNATs for context-specific control of alternative isoform expression of their counterpart sense genes.
Significance:
This study characterizes a previously unexplored role of ncNATs in regulation of isoform expression of associated sense genes, highlighting a mechanism of alternative promoter usage in cancer.
Data from Targeted Nanogels: A Versatile Platform for Drug Delivery to Tumors
Authors: Murphy Eric A. , Majeti Bharat K. , Mukthavaram Rajesh , Acevedo Lisette M. , Barnes Leo A. , Cheresh David A.
Published: March 2024

Abstract
Although nanoparticle-based drug delivery formulations can improve the effectiveness and safety of certain anticancer drugs, many drugs, due to their chemical composition, are unsuitable for nanoparticle loading. Here, we describe a targeted nanogel drug delivery platform that can (i) encapsulate a wide range of drug chemotypes, including biological, small molecule, and cytotoxic agents; (ii) display targeting ligands and polymeric coatings on the surface; (iii) enhance drug retention within the nanogel core after photo-cross-linking; and (iv) retain therapeutic activity after lyophilization allowing for long-term storage. For therapeutic studies, we used integrin αvβ3–targeted lipid-coated nanogels with cross-linked human serum albumin in the core for carrying therapeutic cargoes. These particles exhibited potent activity in tumor cell viability assays with drugs of distinct chemotype, including paclitaxel, docetaxel, bortezomib, 17-AAG, sorafenib, sunitinib, bosutinib, and dasatinib. Treatment of orthotopic breast and pancreas tumors in mice with taxane-loaded nanogels produced a 15-fold improvement in antitumor activity relative to Abraxane by blocking both primary tumor growth and spontaneous metastasis. With a modifiable surface and core, the lipid-coated nanogel represents a platform technology that can be easily adapted for specific drug delivery applications to treat a wide range of malignant diseases. Mol Cancer Ther; 10(6); 972–82. ©2011 AACR.
Data from ATM and p53 Regulate FOXM1 Expression via E2F in Breast Cancer Epirubicin Treatment and Resistance
Authors: Millour Julie , de Olano Natalia , Horimoto Yoshiya , Monteiro Lara J. , Langer Julia K. , Aligue Rosa , Hajji Nabil , Lam Eric W.-F.
Published: March 2024

Abstract
In this report, we investigated the role and regulation of forkhead box M1 (FOXM1) in breast cancer and epirubicin resistance. We generated epirubicin-resistant MCF-7 breast carcinoma (MCF-7-EPIR) cells and found FOXM1 protein levels to be higher in MCF-7-EPIR than in MCF-7 cells and that FOXM1 expression is downregulated by epirubicin in MCF-7 but not in MCF-7-EPIR cells. We also established that there is a loss of p53 function in MCF-7-EPIR cells and that epirubicin represses FOXM1 expression at transcription and gene promoter levels through activation of p53 and repression of E2F activity in MCF-7 cells. Using p53−/− mouse embryo fibroblasts, we showed that p53 is important for epirubicin sensitivity. Moreover, transient promoter transfection assays showed that epirubicin and its cellular effectors p53 and E2F1 modulate FOXM1 transcription through an E2F-binding site located within the proximal promoter region. Chromatin immunoprecipitation analysis also revealed that epirubicin treatment increases pRB (retinoblastoma protein) and decreases E2F1 recruitment to the FOXM1 promoter region containing the E2F site. We also found ataxia-telangiectasia mutated (ATM) protein and mRNA to be overexpressed in the resistant MCF-7-EPIR cells compared with MCF-7 cells and that epirubicin could activate ATM to promote E2F activity and FOXM1 expression. Furthermore, inhibition of ATM in U2OS cells with caffeine or depletion of ATM in MCF-7-EPIR with short interfering RNAs can resensitize these resistant cells to epirubicin, resulting in downregulation of E2F1 and FOXM1 expression and cell death. In summary, our data show that ATM and p53 coordinately regulate FOXM1 via E2F to modulate epirubicin response and resistance in breast cancer. Mol Cancer Ther; 10(6); 1046–58. ©2011 AACR.
Data from Predominance of mTORC1 over mTORC2 in the Regulation of Proliferation of Ovarian Cancer Cells: Therapeutic Implications
Authors: Montero Juan Carlos , Chen Xi , Ocaña Alberto , Pandiella Atanasio
Published: March 2024

Abstract
mTOR is a serine/threonine kinase that acts by binding different sets of proteins forming two complexes, termed mTORC1 and mTORC2. mTOR is deregulated in a substantial proportion of ovarian tumors. Despite the use of drugs directed to mTOR in ongoing clinical trials, the functional relevance of the individual mTORC branches in ovarian cancer is not known. Here, we show that mTORC1 and mTORC2 were constitutively active in ovarian cancer cell lines. Knockdown of raptor or rictor, proteins required for the function of mTORC1 or mTORC2, respectively, resulted in profound inhibition of ovarian cancer cell proliferation. The knockdown of raptor had a more important inhibitory effect than the knockdown of rictor, indicating mTORC1 had a predominant role over mTORC2 in the control of ovarian cancer cell proliferation. Rapamycin decreased the proliferation of ovarian cancer cells, and this was accompanied by inhibition of the phosphorylation of S6, a protein used as readout of mTORC1 function. However, rapamycin had only a marginal effect on the phosphorylation status of 4E-BP1, another mTORC1 substrate. Therefore, mTORC1 probably controls p4E-BP1 along two distinct pathways, one of them sensitive to rapamycin and another insensitive. The dual PI3K/mTOR inhibitor BEZ235 was more efficient than rapamycin in its inhibitory action on ovarian cancer cell proliferation. Biochemically, BEZ235 completely inhibited pS6, p4E-BP1, and pAkt. Our results suggest that broad-spectrum mTOR inhibitors that block mTORC1 and mTORC2 are more desirable for their clinical development in ovarian cancer than agents exclusively targeting one of the mTOR branches. Mol Cancer Ther; 11(6); 1342–52. ©2012 AACR.
Data from Human Monoclonal Antibodies Targeting Nonoverlapping Epitopes on Insulin-like Growth Factor II as a Novel Type of Candidate Cancer Therapeutics
Authors: Chen Weizao , Feng Yang , Zhao Qi , Zhu Zhongyu , Dimitrov Dimiter S.
Published: March 2024

Abstract
Soluble ligands are important targets for therapy of cancers and other diseases. Therapeutic monoclonal antibodies (mAb) against such ligands block their interactions with corresponding receptors but do not enhance their removal from the circulation and can increase their half-lives because of the long half-lives of the antibodies. We have hypothesized that mAbs targeting two or more nonoverlapping epitopes on the same ligand could form oligomeric antibody–ligand complexes that can bind to cells expressing Fc gamma receptors (FcγRs) with high avidity leading to their fast and irreversible removal from the circulation. Insulin-like growth factor II (IGF-II) is an example of such ligands and an important target for human cancer therapy. We identified two mAbs, m610.27 and m630.3, which bound to nonoverlapping epitopes on IGF-II with nanomolar affinity, and generated a bispecific antibody, m660. m660 inhibited the interaction of human IGF-II (hIGF-II) with the human breast cancer cell line MCF-7, hIGF-II–mediated IGF receptor type I and insulin receptor phosphorylation, and cell growth. In the presence of hIGF-II, large complexes of m660 were formed that bound to FcγRII-expressing BJAB cells much more efficiently than the monospecific antibody–hIGF-II complexes and were presumably phagocytosed by phorbol 12-myristate 13-acetate–stimulated macrophage-like U937 cells. A mixture of m610.27 and m630.3 exhibited similar properties. To our knowledge, these mAbs are the first reported to target nonoverlapping epitopes on a cancer-related ligand and could represent a novel class of candidate therapeutics against cancers. This approach could also be used to irreversibly eliminate other disease-related soluble ligands. Mol Cancer Ther; 11(7); 1400–10. ©2012 AACR.
Data from Targeting Sarcoplasmic/Endoplasmic Reticulum Ca2+-ATPase 2 by Curcumin Induces ER Stress-Associated Apoptosis for Treating Human Liposarcoma
Authors: Wang Lu , Wang Lingxian , Song Ran , Shen Yan , Sun Yang , Gu Yanhong , Shu Yongqian , Xu Qiang
Published: March 2024

Abstract
Human liposarcoma is the most common soft tissue sarcoma. There is no effective therapy so far except for surgery. In this study, we report for the first time that curcumin induces endoplasmic reticulum (ER) stress in human liposarcoma cells via interacting with sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2 (SERCA2). Curcumin dose-dependently inhibited the cell survival of human liposarcoma cell line SW872 cells, but did not affect that of human normal adipose-derived cells. Curcumin-mediated ER stress via inhibiting the activity of SERCA2 caused increasing expressions of CHOP and its transcription target death receptor 5 (TRAIL-R2), leading to a caspase-3 and caspase-8 cascade-dependent apoptosis in SW872 cells in vitro and in vivo. Moreover, 70% of human liposarcoma tissues showed an elevated SERCA2 expression compared with normal adipose tissues. Curcumin dose-dependently inhibited the activity of SERCA2, and the interaction of molecular docking and colocalization in ER of curcumin with SERCA2 were further observed. These findings suggest that curcumin may serve as a potent agent for curing human liposarcoma via targeting SERCA2. Mol Cancer Ther; 10(3); 461–71. ©2011 AACR.
Data from Identification of a Natural Compound by Cell-Based Screening That Enhances Interferon Regulatory Factor-1 Activity and Causes Tumor Suppression
Authors: Gao Jinbo , Wang Yujun , Xing Quanhua , Yan Jin , Senthil Maheswari , Akmal Yasir , Kowolik Claudia M. , Kang Julia , Lu David M. , Zhao Ming , Lin Zhixiu , Cheng Christopher H.K. , Yip M.L. Richard , Yim John H.
Published: March 2024

Abstract
The transcription factor interferon regulatory factor-1 (IRF-1) is induced by many tumor-suppressive stimuli and can mediate antiproliferative and proapoptotic effects in cancer cells. Thus, identifying agents that enhance IRF-1 activity may be an effective approach to cancer therapy. A cell-based screening assay was developed to identify extracts and compounds that could enhance IRF-1 activity, using an IRF-1–dependent luciferase reporter cell line. Through this approach, we identified a natural product extract and a known active component of this extract, baicalein, which causes a marked increase in IRF-1–dependent reporter gene expression and IRF-1 protein, with modulation of known IRF-1 targets PUMA and cyclin D1. Baicalein causes suppression of growth in vitro in multiple cancer cell lines in the low micromolar range. IRF-1 plays a role in this growth suppression as shown by significant resistance to growth suppression in a breast cancer cell line stably transfected with short hairpin RNA against IRF-1. Finally, intraperitoneal administration of baicalein by repeated injection causes inhibition of growth in both xenogeneic and syngeneic mouse models of cancer without toxicity to the animals. These findings indicate that identifying enhancers of IRF-1 activity may have utility in anticancer therapies and that cell-based screening for activation of transcription factors can be a useful approach for drug discovery. Mol Cancer Ther; 10(10); 1774–83. ©2011 AACR.
Data from Levels of p27 Sensitize to Dual PI3K/mTOR Inhibition
Authors: Lee Misu , Theodoropoulou Marily , Graw Jochen , Roncaroli Federico , Zatelli Maria Chiara , Pellegata Natalia S.
Published: March 2024

Abstract
Constitutive activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling cascade occurs in a variety of human malignancies, where it sustains tumor cell proliferation and survival. Pharmacologic blockade of this pathway exerts antineoplastic activity by triggering apoptosis and/or cell-cycle arrest. Pituitary adenomas show activation of the PI3K/AKT/mTOR pathway, but only a fraction of them respond in vitro to the antiproliferative action of rapamycin and RAD001 (mTOR inhibitors), possibly because of the described negative feedback loop on AKT which reactivates the signaling cascade. Rats affected by the multiple endocrine neoplasia-like syndrome (MENX) develop pituitary adenomas showing increased activated AKT. In this study, we comparatively investigated the antitumor potential of the novel dual PI3K/mTOR inhibitor NVP-BEZ235 and the single mTOR inhibitor RAD001 on rat pituitary adenoma cells in primary culture. NVP-BEZ235 inhibits the PI3K pathway both upstream and downstream of AKT, thereby preventing the negative feedback loop. NVP-BEZ235 was more effective than RAD001 in reducing cell viability of pituitary adenomas. Consistently, NVP-BEZ235 treatment decreased Akt and S6 phosphorylation and triggered apoptosis. Because MENX is caused by a germline loss-of-function mutation in the cell-cycle inhibitor p27Kip1, we investigated the relationship between this defect and response to NVP-BEZ235 treatment. The levels of p27Kip1 positively correlate with the response to NVP-BEZ235 treatment. Combined treatment with NVP-BEZ235 and the proteasome inhibitor bortezomib, which increases p27Kip1 amount, shows synergistic antiproliferative effects on pituitary adenoma cells. Our data suggest that NVP-BEZ235 may represent an effective therapeutic modality for pituitary adenomas and that p27Kip1 levels represent a potential predictor of response to dual PI3K/mTOR inhibition. Mol Cancer Ther; 10(8); 1450–9. ©2011 AACR.
Data from Hsp90 Inhibitor–Mediated Disruption of Chaperone Association of ATR with Hsp90 Sensitizes Cancer Cells to DNA Damage
Authors: Ha Kyungsoo , Fiskus Warren , Rao Rekha , Balusu Ramesh , Venkannagari Sreedhar , Nalabothula Narasimha Rao , Bhalla Kapil N.
Published: March 2024

Abstract
Following DNA damage that results in stalled replication fork, activation of ATR-CHK1 signaling induces the DNA damage response (DDR) in transformed cells. In the present studies on human cervical and breast cancer cells, we determined the effects of hsp90 inhibition on the levels and accumulation of DNA damage/repair–associated proteins following exposure to γ-ionizing radiation (IR; 4 Gy). We show that hsp90 inhibition with 17-allylamino-demehoxygeldanamycin or the novel, nongeldanamycin analogue AUY922 (resorcinylic isoxazole amide; Novartis Pharma) dose-dependently reduced the levels of ATR and CHK1 without affecting ATM levels. AUY922-mediated depletion of ATR and CHK1 was associated with an increase in their polyubiquitylation and decreased binding to hsp90. Cotreatment with bortezomib partially restored AUY922-mediated depletion of ATR and CHK1 levels. Additionally, treatment with AUY922 reduced the accumulation of ATR, p53BP1, and CHK1 but not γ-H2AX to the sites of DNA damage. Following exposure to IR, AUY922 treatment abrogated IR-induced phospho (p)-ATR and p-CHK1 levels, but significantly enhanced γ-H2AX levels. AUY922 treatment also increased IR-induced accumulation of the cells in G2–M phase of the cell cycle, inhibited the repair of IR-induced DNA damage, and augmented IR-mediated loss of clonogenic survival. Short hairpin RNA–mediated depletion of ATR also inhibited IR-induced p-ATR and p-CHK1, but increased γ-H2AX levels, sensitizing cancer cells to IR-induced apoptosis and loss of clonogenic survival. These findings indicate that ATR is a bona fide hsp90 client protein and post-IR administration of AUY922, by inhibiting ATR-CHK1–mediated DDR, sensitizes cancer cells to IR. Mol Cancer Ther; 10(7); 1194–206. ©2011 AACR.
Data from Overexpression of Mitotic Centromere–Associated Kinesin Stimulates Microtubule Detachment and Confers Resistance to Paclitaxel
Authors: Ganguly Anutosh , Yang Hailing , Cabral Fernando
Published: March 2024

Abstract
Numerous studies have implicated mutations in tubulin or the overexpression of specific tubulin genes in resistance to microtubule-targeted drugs. Much less is known about the role of accessory proteins that modulate microtubule behavior in the genesis of drug resistance. Here, we examine mitotic centromere–associated kinesin (MCAK), a member of the kinesin family of microtubule motor proteins that has the ability to stimulate microtubule depolymerization, and show that overexpressing the protein confers resistance to paclitaxel and epothilone A, but increases sensitivity to colcemid. Cells transfected with FLAG-tagged MCAK cDNA using a tet-off–regulated expression system had a disrupted microtubule cytoskeleton and were able to survive a toxic concentration of paclitaxel in the absence, but not in the presence of tetracycline, showing that drug resistance was caused by ectopic MCAK production. Moreover, a population that was heterogeneous with respect to FLAG-MCAK expression became enriched with cells that produced the ectopic protein when it was placed under paclitaxel selection. Similar to previously isolated mutants with altered tubulin, paclitaxel resistant cells resulting from MCAK overexpression were found to have decreased microtubule polymer and a seven-fold increase in the frequency of microtubule detachment from centrosomes. These data are consistent with a model for paclitaxel resistance that is based on stability of the attachment of microtubules to their nucleating centers, and they implicate MCAK in the mechanism of microtubule detachment. Mol Cancer Ther; 10(6); 929–37. ©2011 AACR.
Data from Dual-Fluorescence Isogenic High-Content Screening for MUC16/CA125 Selective Agents
Authors: Rao Thapi D. , Rosales Nestor , Spriggs David R.
Published: March 2024

Abstract
Most of the currently used cancer chemotherapies are based on compounds that inhibit general cellular mechanisms, such as DNA replication or tubulin function, and lack specificity in relation to features of the cancer cell. Recent advances in genomic studies have increased our knowledge of tumor cell biology, and a panoply of new targets have been postulated. This has provided an opportunity to develop and validate drugs that specifically target cancer cells through their unique genetic characteristics. Identification of MUC16/CA125 both as a marker and a driver of transformation led us to design a target-based high-content screen to identify and classify compounds that exhibit differential effect on MUC16-expressing cells. We developed a coculture assay in 384-well plate containing isogenic ovarian cancer cells that are positive or negative for the MUC16 protein. High-throughput screening of our small molecule pilot library led to the identification of compounds preferentially cytotoxic to MUC16+ or MUC16− cells, using a Preferential Score analysis. We compared screening results in both A2780 and SK-OV-3 ovarian cancer cells in single and coculture settings. We also identified compounds that were cytotoxic for both types of ovarian cancer cells regardless of the MUC16 status. Compounds that were preferentially targeting MUC16 cells were subsequently confirmed by caspase-induction assays. The isogenic, dual-color fluorescence strategy is an innovative approach that can effectively identify novel drug candidates, selectively targeting cancer cells that have unique molecular properties. Mol Cancer Ther; 10(10); 1939–48. ©2011 AACR.
Data from Enhanced Chemotherapy of Cancer Using pH-Sensitive Mesoporous Silica Nanoparticles to Antagonize P-Glycoprotein–Mediated Drug Resistance
Authors: Huang I-Ping , Sun Shu-Pin , Cheng Shih-Hsun , Lee Chia-Hung , Wu Chia-Yan , Yang Chung-Shi , Lo Leu-Wei , Lai Yiu-Kay
Published: March 2024

Abstract
Multidrug resistance (MDR) is the major clinical obstacle in the management of cancer by chemotherapy. Overexpression of ATP-dependent efflux transporter P-glycoprotein (PGP) is a key factor contributing to multidrug resistance of cancer cells. The purpose of the present study was to use the endosomal pH-sensitive MSN (mesoporous silica nanoparticles; MSN-Hydrazone-Dox) for controlled release of doxorubicin (Dox) in an attempt to overcome the PGP-mediated MDR. In vitro cell culture studies indicate that uptake of MSN-Hydrazone-Dox by the human uterine sarcoma MES-SA/Dox-resistant tumor (MES-SA/Dx-5) cell occurs through endocytosis, thus bypassing the efflux pump resistance. This improves the efficacy of the drug and leads to significant cytotoxicity and DNA fragmentation evidenced by terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling and DNA laddering assays. In vivo studies show that the intratumor injection of MSN-Hydrazone-Dox induces significant apoptosis of MES-SA/Dox-resistant cancer cells. This is validated by active caspase-3 immunohistochemical analysis. However, MSN-Hydrazone, without doxorubicin conjugation, cannot induce apoptosis in vitro and in vivo. In conclusion, both in vitro and in vivo studies show that MSN could serve as an efficient nanocarrier entering cell avidly via endocytosis, thus bypassing the PGP efflux pump to compromise the PGP-mediated MDR. MSN-Hydrazone-Dox could further respond to endosomal acidic pH to release doxorubicin in a sustained manner. Besides the cell study, this is the first report that successfully shows the therapeutic efficacy of using MSN against MDR cancer in vivo. Mol Cancer Ther; 10(5); 761–9. ©2011 AACR.
Data from Interactions of Tyrosine Kinase Inhibitors with Organic Cation Transporters and Multidrug and Toxic Compound Extrusion Proteins
Authors: Minematsu Tsuyoshi , Giacomini Kathleen M.
Published: March 2024

Abstract
The drug–drug interaction (DDI) potential of tyrosine kinase inhibitors (TKI) as interacting drugs via transporter inhibition has not been fully assessed. Here, we estimated the half maximal inhibitory concentration (IC50) values for 8 small-molecule TKIs (imatinib, dasatinib, nilotinib, gefitinib, erlotinib, sunitinib, lapatinib, and sorafenib) on [14C]metformin transport by human organic cation transporters (OCT), OCT1, OCT2, and OCT3, and multidrug and toxic compound extrusion (MATE) proteins, MATE1 and MATE2-K, using human embryonic kidney cells stably expressing these transporters. We then compared the estimated IC50 values to the maximum clinical concentrations of unbound TKIs in plasma (unbound Cmax,sys,p). Results showed that imatinib, nilotinib, gefitinib, and erlotinib exerted selectively potent inhibitory effects, with unbound Cmax,sys,p/IC50 values ≥0.1, on MATE1, OCT3, MATE2-K, and OCT1, respectively. In comparison to the common form of OCT1, the OCT1 polymorphism, M420del, was more sensitive to drug inhibition by erlotinib. Major metabolites of several TKIs showed IC50 values similar to those for unchanged TKIs. Taken together, these findings suggest the potential of clinical transporter-mediated DDIs between specific TKIs and OCTs and MATEs, which may affect the disposition, efficacy, and toxicity of metformin and other drugs that are substrates of these transporters. The study provides the basis for further clinical DDI studies with TKIs. Mol Cancer Ther; 10(3); 531–9. ©2011 AACR.
Data from A Simplified Synthesis of Novel Dictyostatin Analogues with In Vitro Activity against Epothilone B–Resistant Cells and Antiangiogenic Activity in Zebrafish Embryos
Authors: Vollmer Laura L. , Jiménez Maria , Camarco Daniel P. , Zhu Wei , Daghestani Hikmat N. , Balachandran Raghavan , Reese Celeste E. , Lazo John S. , Hukriede Neil A. , Curran Dennis P. , Day Billy W. , Vogt Andreas
Published: March 2024

Abstract
The natural product (−)-dictyostatin is a microtubule-stabilizing agent that potently inhibits the growth of human cancer cells, including paclitaxel-resistant clones. Extensive structure–activity relationship studies have revealed several regions of the molecule that can be altered without loss of activity. The most potent synthetic dictyostatin analogue described to date, 6-epi-dictyostatin, has superior in vivo antitumor activity against human breast cancer xenografts compared with paclitaxel. In spite of their encouraging activities in preclinical studies, the complex chemical structure of the dictyostatins presents a major obstacle for their development into novel antineoplastic therapies. We recently reported a streamlined synthesis of 16-desmethyl-25,26-dihydrodictyostatins and found several agents that, when compared with 6-epi-dictyostatin, retained nanomolar activity in cellular microtubule-bundling assays but had lost activity against paclitaxel-resistant cells with mutations in β-tubulin. Extending these studies, we applied the new, highly convergent synthesis to generate 25,26-dihydrodictyostatin and 6-epi-25,26-dihydrodictyostatin. Both compounds were potent microtubule-perturbing agents that induced mitotic arrest and microtubule assembly in vitro and in intact cells. In vitro radioligand binding studies showed that 25,26-dihydrodictyostatin and its C6-epimer were capable of displacing [3H]paclitaxel and [14C]epothilone B from microtubules with potencies comparable to (−)-dictyostatin and discodermolide. Both compounds inhibited the growth of paclitaxel- and epothilone B–resistant cell lines at low nanomolar concentrations, synergized with paclitaxel in MDA-MB-231 human breast cancer cells, and had antiangiogenic activity in transgenic zebrafish larvae. These data identify 25,26-dihydrodictyostatin and 6-epi-25,26-dihydrodictyostatin as candidates for scale-up synthesis and further preclinical development. Mol Cancer Ther; 10(6); 994–1006. ©2011 AACR.
Data from A Combined Preclinical Therapy of Cannabinoids and Temozolomide against Glioma
Authors: Torres Sofía , Lorente Mar , Rodríguez-Fornés Fátima , Hernández-Tiedra Sonia , Salazar María , García-Taboada Elena , Barcia Juan , Guzmán Manuel , Velasco Guillermo
Published: March 2024

Abstract
Glioblastoma multiforme (GBM) is highly resistant to current anticancer treatments, which makes it crucial to find new therapeutic strategies aimed at improving the poor prognosis of patients suffering from this disease. Δ9-Tetrahydrocannabinol (THC), the major active ingredient of marijuana, and other cannabinoid receptor agonists inhibit tumor growth in animal models of cancer, including glioma, an effect that relies, at least in part, on the stimulation of autophagy-mediated apoptosis in tumor cells. Here, we show that the combined administration of THC and temozolomide (TMZ; the benchmark agent for the management of GBM) exerts a strong antitumoral action in glioma xenografts, an effect that is also observed in tumors that are resistant to TMZ treatment. Combined administration of THC and TMZ enhanced autophagy, whereas pharmacologic or genetic inhibition of this process prevented TMZ + THC-induced cell death, supporting that activation of autophagy plays a crucial role on the mechanism of action of this drug combination. Administration of submaximal doses of THC and cannabidiol (CBD; another plant-derived cannabinoid that also induces glioma cell death through a mechanism of action different from that of THC) remarkably reduces the growth of glioma xenografts. Moreover, treatment with TMZ and submaximal doses of THC and CBD produced a strong antitumoral action in both TMZ-sensitive and TMZ-resistant tumors. Altogether, our findings support that the combined administration of TMZ and cannabinoids could be therapeutically exploited for the management of GBM. Mol Cancer Ther; 10(1); 90–103. ©2011 AACR.
Data from Inhibition of the Acetyltransferases p300 and CBP Reveals a Targetable Function for p300 in the Survival and Invasion Pathways of Prostate Cancer Cell Lines
Authors: Santer Frédéric R. , Höschele Philipp P.S. , Oh Su Jung , Erb Holger H.H. , Bouchal Jan , Cavarretta Ilaria T. , Parson Walther , Meyers David J. , Cole Philip A. , Culig Zoran
Published: March 2024

Abstract
Inhibitors of histone deacetylases have been approved for clinical application in cancer treatment. On the other hand, histone acetyltransferase (HAT) inhibitors have been less extensively investigated for their potential use in cancer therapy. In prostate cancer, the HATs and coactivators p300 and CBP are upregulated and may induce transcription of androgen receptor (AR)-responsive genes, even in the absence or presence of low levels of AR. To discover a potential anticancer effect of p300/CBP inhibition, we used two different approaches: (i) downregulation of p300 and CBP by specific short interfering RNA (siRNA) and (ii) chemical inhibition of the acetyltransferase activity by a newly developed small molecule, C646. Knockdown of p300 by specific siRNA, but surprisingly not of CBP, led to an increase of caspase-dependent apoptosis involving both extrinsic and intrinsic cell death pathways in androgen-dependent and castration-resistant prostate cancer cells. Induction of apoptosis was mediated by several pathways including inhibition of AR function and decrease of the nuclear factor kappa B (NF-κB) subunit p65. Furthermore, cell invasion was decreased upon p300, but not CBP, depletion and was accompanied by lower matrix metalloproteinase (MMP)-2 and MMP-9 transcriptions. Thus, p300 and CBP have differential roles in the processes of survival and invasion of prostate cancer cells. Induction of apoptosis in prostate cancer cells was confirmed by the use of C646. This was substantiated by a decrease of AR function and downregulation of p65 impairing several NF-κB target genes. Taken together, these results suggest that p300 inhibition may be a promising approach for the development of new anticancer therapies. Mol Cancer Ther; 10(9); 1644–55. ©2011 AACR.
Data from High-Throughput Screen Identifies Novel Inhibitors of Cancer Biomarker α-Methylacyl Coenzyme A Racemase (AMACR/P504S)
Authors: Wilson Brice A.P. , Wang Haofan , Nacev Benjamin A. , Mease Ronnie C. , Liu Jun O. , Pomper Martin G. , Isaacs William B.
Published: March 2024

Abstract
α-methylacyl coenzyme A racemase (AMACR) is a metabolic enzyme whose overexpression has been shown to be a diagnostic indicator of prostatic adenocarcinoma and other solid tumors. Here, we confirm that attenuation of AMACR expression diminishes the growth of prostate cancer cell lines by using stably expressed short-hairpin RNA constructs. This observation strongly suggests that the AMACR enzyme may be a target for therapeutic inhibition in prostate cancer. To this end, we report here a novel assay capable of screening libraries of diverse small molecules for inhibitors of AMACR activity. This assay facilitated the screening of approximately 5,000 unique compounds and the discovery of 7 distinct chemical entities capable of inhibiting AMACR at low micromolar concentrations. The most potent inhibitor discovered is the seleno-organic compound ebselen oxide [inhibitory concentration (IC50): 0.80 μmol/L]. The parent compound, ebselen (IC50: 2.79 μmol/L), is a covalent inactivator of AMACR (KI(inact): 24 μmol/L). Two of the AMACR inhibitors are selectively toxic to prostate cancer cell lines (LAPC4/LNCaP/PC3) that express AMACR compared to a normal prostate fibroblast cell line (WPMY1) that does not express the protein. This report shows the first high-throughput screen for the discovery of novel AMACR inhibitors, characterizes the first nonsubstrate-based inhibitors, and validates that AMACR is a viable chemotherapeutic target in vitro. Mol Cancer Ther; 10(5); 825–38. ©2011 AACR.
Data from Expression Signatures of the Lipid-Based Akt Inhibitors Phosphatidylinositol Ether Lipid Analogues in NSCLC Cells
Authors: Zhang Chunyu , Elkahloun Abdel G. , Liao Hongling , Delaney Shannon , Saber Barbara , Morrow Betsy , Prendergast George C. , Hollander M. Christine , Gills Joell J. , Dennis Phillip A.
Published: March 2024

Abstract
Activation of the serine/threonine kinase Akt contributes to the formation, maintenance, and therapeutic resistance of cancer, which is driving development of compounds that inhibit Akt. Phosphatidylinositol ether lipid analogues (PIA) are analogues of the products of phosphoinositide-3-kinase (PI3K) that inhibit Akt activation, translocation, and the proliferation of a broad spectrum of cancer cell types. To gain insight into the mechanism of PIAs, time-dependent transcriptional profiling of five active PIAs and the PI3K inhibitor LY294002 (LY) was conducted in non–small cell lung carcinoma cells using high-density oligonucleotide arrays. Gene ontology analysis revealed that genes involved in apoptosis, wounding response, and angiogenesis were upregulated by PIAs, whereas genes involved in DNA replication, repair, and mitosis were suppressed. Genes that exhibited early differential expression were partitioned into three groups; those induced by PIAs only (DUSP1, KLF6, CENTD2, BHLHB2, and PREX1), those commonly induced by PIAs and LY (TRIB1, KLF2, RHOB, and CDKN1A), and those commonly suppressed by PIAs and LY (IGFBP3, PCNA, PRIM1, MCM3, and HSPA1B). Increased expression of the tumor suppressors RHOB (RhoB), KLF6 (COPEB), and CDKN1A (p21Cip1/Waf1) was validated as an Akt-independent effect that contributed to PIA-induced cytotoxicity. Despite some overlap with LY, active PIAs have a distinct expression signature that contributes to their enhanced cytotoxicity. Mol Cancer Ther; 10(7); 1137–48. ©2011 AACR.
Data from The NEDD8-Activating Enzyme Inhibitor, MLN4924, Cooperates with TRAIL to Augment Apoptosis through Facilitating c-FLIP Degradation in Head and Neck Cancer Cells
Authors: Zhao Liqun , Yue Ping , Lonial Sagar , Khuri Fadlo R. , Sun Shi-Yong
Published: March 2024

Abstract
TNF-related apoptosis-inducing ligand (TRAIL) is a tumor-selective cytokine with potential anticancer activity and is currently under clinical testing. Head and neck squamous cell carcinoma (HNSCC), like other cancer types, exhibits varied sensitivity to TRAIL. MLN4924 is a newly developed investigational small molecule inhibitor of NEDD8-activating enzyme with potent anticancer activity. This study reveals a novel function of MLN4924 in synergizing with TRAIL to induce apoptosis in HNSCC cells. MLN4924 alone effectively inhibited the growth of HNSCC cells and induced apoptosis. When combined with TRAIL, synergistic effects on decreasing the survival and inducing apoptosis of HNSCC cells occurred. MLN4924 decreased c-FLIP levels without modulating death receptor 4 and death receptor 5 expression. Enforced expression of c-FLIP substantially attenuated MLN4924/TRAIL–induced apoptosis. Thus c-FLIP reduction plays an important role in mediating MLN4924/TRAIL–induced apoptosis. Moreover, MLN4924 decreased c-FLIP stability, increased c-FLIP ubiquitination, and facilitated c-FLIP degradation, suggesting that MLN4924 decreases c-FLIP levels through promoting its degradation. MLN4924 activated c-jun-NH2-kinase (JNK) signaling, evidenced by increased levels of phospho-c-Jun in MLN4924-treated cells. Chemical inhibition of JNK activation not only prevented MLN4924-induced c-FLIP reduction, but also inhibited MLN4924/TRAIL–induced apoptosis, suggesting that JNK activation mediates c-FLIP downregulation and subsequent enhancement of TRAIL-induced apoptosis by MLN4924. Because knockdown of NEDD8 failed to activate JNK signaling and downregulate c-FLIP, it is likely that MLN4924 reduces c-FLIP levels and enhances TRAIL-induced apoptosis independent of NEDD8 inhibition. Mol Cancer Ther; 10(12); 2415–25. ©2011 AACR.