bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Prognostic Relevance of Tumor Purity and Interaction with MGMT Methylation in Glioblastoma
Authors: Schulze Heuling Eva , Knab Felix , Radke Josefine , Eskilsson Eskil , Martinez-Ledesma Emmanuel , Koch Arend , Czabanka Marcus , Dieterich Christoph , Verhaak Roel G. , Harms Christoph , Euskirchen Philipp
Published: April 2023

Abstract
Promoter methylation status of O-6-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme, is a critical biomarker in glioblastoma (GBM), as treatment decisions and clinical trial inclusion rely on its accurate assessment. However, interpretation of results is complicated by poor interassay reproducibility as well as a weak correlation between methylation status and expression levels of MGMT. This study systematically investigates the influence of tumor purity on tissue subjected to MGMT analysis. A quantitative, allele-specific real-time PCR (qAS-PCR) assay was developed to determine genotype and mutant allele frequency of telomerase promoter (pTERT) mutations as a direct measure of tumor purity. We studied tumor purity, pTERT mutation by Sanger sequencing, MGMT methylation by pyrosequencing, IDH1 mutation status, and clinical parameters in a cohort of high-grade gliomas (n = 97). The qAS-PCR reliably predicted pTERT genotype and tumor purity compared with independent methods. Tumor purity positively and significantly correlated with the extent of methylation in MGMT methylated GBMs. Extent of MGMT methylation differed significantly with respect to pTERT mutation hotspot (C228T vs. C250T). Interestingly, frontal lobe tumors showed greater tumor purity than those in other locations. Above all, tumor purity was identified as an independent prognostic factor in GBM. In conclusion, we determined mutual associations of tumor purity with MGMT methylation and pTERT mutations and found that the extent of MGMT methylation reflects tumor purity. In turn, tumor purity is prognostic in IDH1 wild-type GBM.

Implications: Tumor purity is an independent prognostic marker in glioblastoma and is associated with the extent of MGMT methylation. Mol Cancer Res; 15(5); 532–40. ©2017 AACR.
Data from FOXD3 Modulates Migration through Direct Transcriptional Repression of TWIST1 in Melanoma
Authors: Weiss Michele B. , Abel Ethan V. , Dadpey Neda , Aplin Andrew E.
Published: April 2023

Abstract
The neural crest is a multipotent, highly migratory cell population that gives rise to diverse cell types, including melanocytes. Factors regulating the development of the neural crest and emigration of its cells are likely to influence melanoma metastasis. The transcription factor FOXD3 plays an essential role in premigratory neural crest development and has been implicated in melanoma cell dormancy and response to therapeutics. FOXD3 is downregulated during the migration of the melanocyte lineage from the neural crest, and our previous work supports a role for FOXD3 in suppressing melanoma cell migration and invasion. Alternatively, TWIST1 is known to have promigratory and proinvasive roles in a number of cancers, including melanoma. Using ChIP-seq analysis, TWIST1 was identified as a potential transcriptional target of FOXD3. Mechanistically, FOXD3 directly binds to regions of the TWIST1 gene locus, leading to transcriptional repression of TWIST1 in human mutant BRAF melanoma cells. In addition, depletion of endogenous FOXD3 promotes upregulation of TWIST1 transcripts and protein. Finally, FOXD3 expression leads to a significant decrease in cell migration that can be efficiently reversed by the overexpression of TWIST1. These findings uncover the novel interplay between FOXD3 and TWIST1, which is likely to be important in the melanoma metastatic cascade.

Implications: FOXD3 and TWIST1 define distinct subgroups of cells within a heterogeneous tumor. Mol Cancer Res; 12(9); 1314–23. ©2014 AACR.
Data from Novel Potent and Selective Inhibitors of p90 Ribosomal S6 Kinase Reveal the Heterogeneity of RSK Function in MAPK-Driven Cancers
Authors: Aronchik Ida , Appleton Brent A. , Basham Stephen E. , Crawford Kenneth , Del Rosario Mercedita , Doyle Laura V. , Estacio William F. , Lan Jiong , Lindvall Mika K. , Luu Catherine A. , Ornelas Elizabeth , Venetsanakos Eleni , Shafer Cynthia M. , Jefferson Anne B.
Published: April 2023

Abstract
The p90 ribosomal S6 kinase (RSK) family of serine/threonine kinases is expressed in a variety of cancers and its substrate phosphorylation has been implicated in direct regulation of cell survival, proliferation, and cell polarity. This study characterizes and presents the most selective and potent RSK inhibitors known to date, LJH685 and LJI308. Structural analysis confirms binding of LJH685 to the RSK2 N-terminal kinase ATP-binding site and reveals that the inhibitor adopts an unusual nonplanar conformation that explains its excellent selectivity for RSK family kinases. LJH685 and LJI308 efficiently inhibit RSK activity in vitro and in cells. Furthermore, cellular inhibition of RSK and its phosphorylation of YB1 on Ser102 correlate closely with inhibition of cell growth, but only in an anchorage-independent growth setting, and in a subset of examined cell lines. Thus, RSK inhibition reveals dynamic functional responses among the inhibitor-sensitive cell lines, underscoring the heterogeneous nature of RSK dependence in cancer.

Implications: Two novel potent and selective RSK inhibitors will now allow a full assessment of the potential of RSK as a therapeutic target for oncology. Mol Cancer Res; 12(5); 803–12. ©2014 AACR.
Data from PAI-1 Leads to G1-Phase Cell-Cycle Progression through Cyclin D3/cdk4/6 Upregulation
Authors: Giacoia Evan Gomes , Miyake Makito , Lawton Adrienne , Goodison Steve , Rosser Charles J.
Published: April 2023

Abstract
The canonical function of plasminogen activator inhibitor-1 (PAI-1/SERPINE1) is as an inhibitor of urokinase-type plasminogen activator for blood clot maintenance, but it is now also considered a pleiotropic factor that can exert diverse cellular and tumorigenic effects. However, the mechanism controlling its pleiotropic effects is far from being understood. To elucidate the tumorigenic role of PAI-1, we tested the effects of PAI-1 after manipulation of its expression or through the use of a small-molecule inhibitor, tiplaxtinin. Downregulation of PAI-1 significantly reduced cellular proliferation through an inability to progress from the G0–G1 phase of the cell cycle. Accordingly, overexpression of PAI-1 augmented proliferation by encouraging S-phase entry. Biochemically, cell-cycle arrest was associated with the depletion of the G1-phase transition complexes, cyclin D3/cdk4/6 and cyclin E/cdk2, in parallel with the upregulation of the cell-cycle inhibitors p53, p21Cip1/Waf1, and p27Kip1. PAI-1 depletion significantly decreased the tumor size of urothelial T24 and UM-UC-14 xenografts, and overexpression of PAI-1 substantially increased the tumor size of HeLa xenografts. Finally, immunohistochemical analysis of human bladder and cervical tumor tissue microarrays revealed increased expression of PAI-1 in cancerous tissue, specifically in aggressive tumors, supporting the relevance of this molecule in human tumor biology.

Implications: Targeting PAI-1 has beneficial antitumoral effects and should be further investigated clinically. Mol Cancer Res; 12(3); 322–34. ©2014 AACR.
Data from AKT-Induced Tamoxifen Resistance Is Overturned by RRM2 Inhibition
Authors: Shah Khyati N. , Mehta Kshama R. , Peterson David , Evangelista Marie , Livesey John C. , Faridi Jesika S.
Published: April 2023

Abstract
Acquired tamoxifen resistance develops in the majority of hormone-responsive breast cancers and frequently involves overexpression of the PI3K/AKT axis. Here, breast cancer cells with elevated endogenous AKT or overexpression of activated AKT exhibited tamoxifen-stimulated cell proliferation and enhanced cell motility. To gain mechanistic insight on AKT-induced endocrine resistance, gene expression profiling was performed to determine the transcripts that are differentially expressed post-tamoxifen therapy under conditions of AKT overexpression. Consistent with the biologic outcome, many of these transcripts function in cell proliferation and cell motility networks and were quantitatively validated in a larger panel of breast cancer cells. Moreover, ribonucleotide reductase M2 (RRM2) was revealed as a key contributor to AKT-induced tamoxifen resistance. Inhibition of RRM2 by RNA interference (RNAi)–mediated approaches significantly reversed the tamoxifen-resistant cell growth, inhibited cell motility, and activated DNA damage and proapoptotic pathways. In addition, treatment of tamoxifen-resistant breast cancer cells with the small molecule RRM inhibitor didox significantly reduced in vitro and in vivo growth. Thus, AKT-expressing breast cancer cells upregulate RRM2 expression, leading to increased DNA repair and protection from tamoxifen-induced apoptosis.

Implications: These findings identify RRM2 as an AKT-regulated gene, which plays a role in tamoxifen resistance and may prove to be a novel target for effective diagnostic and preventative strategies. Mol Cancer Res; 12(3); 394–407. ©2013 AACR.
Data from SGEF Is Regulated via TWEAK/Fn14/NF-κB Signaling and Promotes Survival by Modulation of the DNA Repair Response to Temozolomide
Authors: Ensign Shannon P. Fortin , Roos Alison , Mathews Ian T. , Dhruv Harshil D. , Tuncali Serdar , Sarkaria Jann N. , Symons Marc H. , Loftus Joseph C. , Berens Michael E. , Tran Nhan L.
Published: April 2023

Abstract
Glioblastoma (GB) is the highest grade and most common form of primary adult brain tumors. Despite surgical removal followed by concomitant radiation and chemotherapy with the alkylating agent temozolomide, GB tumors develop treatment resistance and ultimately recur. Impaired response to treatment occurs rapidly, conferring a median survival of just fifteen months. Thus, it is necessary to identify the genetic and signaling mechanisms that promote tumor resistance to develop targeted therapies to combat this refractory disease. Previous observations indicated that SGEF (ARHGEF26), a RhoG-specific guanine nucleotide exchange factor (GEF), is overexpressed in GB tumors and plays a role in promoting TWEAK-Fn14–mediated glioma invasion. Here, further investigation revealed an important role for SGEF in glioma cell survival. SGEF expression is upregulated by TWEAK-Fn14 signaling via NF-κB activity while shRNA-mediated reduction of SGEF expression sensitizes glioma cells to temozolomide-induced apoptosis and suppresses colony formation following temozolomide treatment. Nuclear SGEF is activated following temozolomide exposure and complexes with the DNA damage repair (DDR) protein BRCA1. Moreover, BRCA1 phosphorylation in response to temozolomide treatment is hindered by SGEF knockdown. The role of SGEF in promoting chemotherapeutic resistance highlights a heretofore unappreciated driver, and suggests its candidacy for development of novel targeted therapeutics for temozolomide-refractory, invasive GB cells.

Implication: SGEF, as a dual process modulator of cell survival and invasion, represents a novel target for treatment refractory glioblastoma. Mol Cancer Res; 14(3); 302–12. ©2016 AACR.
Data from A Monotonic and Prognostic Genomic Signature from Fibroblasts for Colorectal Cancer Initiation, Progression, and Metastasis
Authors: Berdiel-Acer Mireia , Cuadras Daniel , Díaz-Maroto Natalia Guillén , Sanjuan Xavier , Serrano Teresa , Berenguer Antoni , Moreno Victor , Gonçalves-Ribeiro Samuel , Salazar Ramon , Villanueva Alberto , Molleví David G.
Published: April 2023

Abstract
The differential gene expression patterns between normal colonic fibroblasts (NCF), carcinoma-associated fibroblasts from primary tumors (CAF-PT), and CAFs from hepatic metastasis (CAF-LM) are hypothesized to be useful for predicting relapse in primary tumors. A transcriptomic profile of NCF (n = 9), CAF-PT (n = 14), and CAF-LM (n = 11) was derived. Prediction Analysis of Microarrays (PAM) was used to obtain molecular details for each fibroblast class, and differentially expressed transcripts were used to classify patients according to recurrence status. A number of transcripts (n = 277) were common to all three types of fibroblasts and whose expression level was sequentially deregulated according to the transition: NCF→CAF-PT→CAF-LM. Importantly, the gene signature was able to accurately classify patients with primary tumors according to their prognosis. This capacity was exploited to obtain a refined 19-gene classifier that predicted recurrence with high accuracy in two independent datasets of patients with colorectal cancer and correlates with fibroblast migratory potential. The prognostic power of this genomic signature is strong evidence of the link between the tumor-stroma microenvironment and cancer progression. Furthermore, the 19-gene classifier was able to identify low-risk patients very accurately, which is of particular importance for stage II patients, who would benefit from the omission of chemotherapy, especially T4N0 patients, who are clinically classified as being at high risk.

Implications: A defined stromal gene expression signature predicts relapse in patients with colorectal cancer. Mol Cancer Res; 12(9); 1254–66. ©2014 AACR.
Data from Patient Mutation Directed shRNA Screen Uncovers Novel Bladder Tumor Growth Suppressors
Authors: Hensel Jonathan , Duex Jason E. , Owens Charles , Dancik Garrett M. , Edwards Michael G. , Frierson Henry F. , Theodorescu Dan
Published: April 2023

Abstract
Next-generation sequencing (NGS) of human bladder cancer has revealed many gene alterations compared with normal tissue, with most being predicted to be “loss of function.” However, given the high number of alterations, evaluating the functional impact of each is impractical. Here, we develop and use a high-throughput, in vivo strategy to determine which alterations are loss of function in tumor growth suppressors. Genes reported as altered by NGS in bladder cancer patients were bioinformatically processed by MutationTaster and MutationAssessor, with 283 predicted as loss of function. An shRNA lentiviral library targeting these genes was transduced into T24 cells, a nontumorigenic human bladder cancer cell line, followed by injection into mice. Tumors that arose were sequenced and the dominant shRNA constructs were found to target IQGAP1, SAMD9L, PCIF1, MED1, and KATNAL1 genes. In vitro validation experiments revealed that shRNA molecules directed at IQGAP1 showed the most profound increase in anchorage-independent growth of T24 cells. The clinical relevance of IQGAP1 as a tumor growth suppressor is supported by the finding that its expression is lower in bladder cancer compared with benign patient urothelium in multiple independent datasets. Lower IQGAP1 protein expression associated with higher tumor grade and decreased patient survival. Finally, depletion of IQGAP1 leads to increased TGFBR2 with TGFβ signaling, explaining in part how reduced IQGAP1 promotes tumor growth. These findings suggest IQGAP1 is a bladder tumor growth suppressor that works via modulating TGFβ signaling and is a potentially clinically useful biomarker.

Implications: This study used gene mutation information from patient-derived bladder tumor specimens to inform the development of a screen used to identify novel tumor growth suppressors. This included identification of the protein IQGAP1 as a potent bladder cancer growth suppressor. Mol Cancer Res; 13(9); 1306–15. ©2015 AACR.
Data from DNA Polymerase Beta Germline Variant Confers Cellular Response to Cisplatin Therapy
Authors: Nemec Antonia A. , Abriola Laura , Merkel Jane S. , de Stanchina Elisa , DeVeaux Michelle , Zelterman Daniel , Glazer Peter M. , Sweasy Joann B.
Published: April 2023

Abstract
Resistance to cancer chemotherapies leads to deadly consequences, yet current research focuses only on the roles of somatically acquired mutations in this resistance. The mutational status of the germline is also likely to play a role in the way cells respond to chemotherapy. The carrier status for the POLB rs3136797 germline mutation encoding P242R DNA polymerase beta (Pol β) is associated with poor prognosis for lung cancer, specifically in response to treatment with cisplatin. Here, it is revealed that the P242R mutation is sufficient to promote resistance to cisplatin in human cells and in mouse xenografts. Mechanistically, P242R Pol β acts as a translesion polymerase and prefers to insert the correct nucleotide opposite cisplatin intrastrand cross-links, leading to the activation of the nucleotide excision repair (NER) pathway, removal of crosslinks, and resistance to cisplatin. In contrast, wild-type (WT) Pol β preferentially inserts the incorrect nucleotide initiating mismatch repair and cell death. Importantly, in a mouse xenograft model, tumors derived from lung cancer cells expressing WT Pol β displayed a slower rate of growth when treated with cisplatin, whereas tumors expressing P242R Pol β had no response to cisplatin. Pol β is critical for mediating crosstalk in response to cisplatin. The current data strongly suggest that the status of Pol β influences cellular responses to crosslinking agents and that Pol β is a promising biomarker to predict responses to specific chemotherapies. Finally, these results highlight that the genetic status of the germline is a critical factor in the response to cancer treatment.

Implications: Pol β has prognostic biomarker potential in the treatment of cancer with cisplatin and perhaps other intrastrand crosslinking agents. Mol Cancer Res; 15(3); 269–80. ©2017 AACR.
Data from Novel Assay to Detect RNA Polymerase I Activity In Vivo
Authors: Guner Gunes , Sirajuddin Paul , Zheng Qizhi , Bai Baoyan , Brodie Alexandra , Liu Hester , af Hällström Taija , Kulac Ibrahim , Laiho Marikki , De Marzo Angelo M.
Published: April 2023

Abstract
This report develops an analytically validated chromogenic in situ hybridization (CISH) assay using branched DNA signal amplification (RNAscope) for detecting the expression of the 5′ external transcribed spacer (ETS) of the 45S ribosomal (r) RNA precursor in formalin-fixed and paraffin-embedded (FFPE) human tissues. 5′ETS/45S CISH was performed on standard clinical specimens and tissue microarrays (TMA) from untreated prostate carcinomas, high-grade prostatic intraepithelial neoplasia (PIN), and matched benign prostatic tissues. Signals were quantified using image analysis software. The 5′ETS rRNA signal was restricted to the nucleolus. The signal was markedly attenuated in cell lines and in prostate tissue slices after pharmacologic inhibition of RNA polymerase I (Pol I) using BMH-21 or actinomycin D, and by RNAi depletion of Pol I, demonstrating validity as a measure of Pol I activity. Clinical human prostate FFPE tissue sections and TMAs showed a marked increase in the signal in the presumptive precursor lesion (high-grade PIN) and invasive adenocarcinoma lesions (P = 0.0001 and P = 0.0001, respectively) compared with non-neoplastic luminal epithelium. The increase in 5′ETS rRNA signal was present throughout all Gleason scores and pathologic stages at radical prostatectomy, with no marked difference among these. This precursor rRNA assay has potential utility for detection of increased rRNA production in various tumor types and as a novel companion diagnostic for clinical trials involving Pol I inhibition.

Implications: Increased rRNA production, a possible therapeutic target for multiple cancers, can be detected with a new, validated assay that also serves as a pharmacodynamic marker for Pol I inhibitors. Mol Cancer Res; 15(5); 577–84. ©2017 AACR.
Data from Long-term Tumor Adaptation after Radiotherapy: Therapeutic Implications for Targeting Integrins in Prostate Cancer
Authors: Eke Iris , Makinde Adeola Y. , Aryankalayil Molykutty J. , Reedy Jessica L. , Citrin Deborah E. , Chopra Sunita , Ahmed Mansoor M. , Coleman C. Norman
Published: April 2023

Abstract
Adaptation of tumor cells to radiotherapy induces changes that are actionable by molecular targeted agents and immunotherapy. This report demonstrates that radiation-induced changes in integrin expression can be targeted 2 months later. Integrins are transmembrane cell adhesion molecules that are essential for cancer cell survival and proliferation. To analyze the short- and long-term effects of radiation on the integrin expression, prostate cancer cells (DU145, PC3, and LNCaP) were cultured in a 3D extracellular matrix and irradiated with either a single dose of radiation (2–10 Gy) or a multifractionated regimen (2–10 fractions of 1 Gy). Whole human genome microarrays, immunoblotting, immunoprecipitation assays, and immunofluorescence staining of integrins were performed. The results were confirmed in a prostate cancer xenograft model system. Interestingly, β1 and β4 integrins (ITGB1 and ITGB4) were upregulated after radiation in vitro and in vivo. This overexpression lasted for more than 2 months and was dose dependent. Moreover, radiation-induced upregulation of β1 and β4 integrin resulted in significantly increased tumor cell death after treatment with inhibitory antibodies. Combined, these findings indicate that long-term tumor adaptation to radiation can result in an increased susceptibility of surviving cancer cells to molecular targeted therapy due to a radiation-induced overexpression of the target.
Implications:
Radiation induces dose- and schedule-dependent adaptive changes that are targetable for an extended time; thus suggesting radiotherapy as a unique strategy to orchestrate molecular processes, thereby providing new radiation-drug treatment options within precision cancer medicine.
Data from Bioactive Lipids, LPC and LPA, Are Novel Prometastatic Factors and Their Tissue Levels Increase in Response to Radio/Chemotherapy
Authors: Schneider Gabriela , Sellers Zachariah Payne , Abdel-Latif Ahmed , Morris Andrew J. , Ratajczak Mariusz Z.
Published: April 2023

Abstract
Bioactive lipids are fundamental mediators of a number of critical biologic processes such as inflammation, proliferation, and apoptosis. Rhabdomyosarcoma (RMS) is common in adolescence with histologic subtypes that favor metastasis. However, the factors that influence metastasis are not well appreciated. Here, it is shown that lysophosphatidylcholine (LPC) and its derivative, lysophosphatidic acid (LPA), strongly enhance motility and adhesion of human RMS cells. Importantly, these metastatic-associated phenotypes were observed at physiologic concentrations of these lipids, which naturally occur in biologic fluids. Moreover, the effects of these bioactive lipids were much stronger as compared with known peptide-based prometastatic factors in RMS, such as stromal-derived factor-1 or hepatocyte growth factor/scatter factor. Finally, both LPC and LPA levels were increased in several organs after γ-irradiation or chemotherapy, supporting the hypothesis that radio/chemotherapy induces an unwanted prometastatic environment in these organs.

Implications: LPC and LPA play a previously underappreciated role in dissemination of RMS and suggest that antimetastatic treatment with specific molecules blocking LPC/LPA activity should be part of standard radio/chemotherapy arsenal. Mol Cancer Res; 12(11); 1560–73. ©2014 AACR.
Data from Autotaxin and LPA1 and LPA5 Receptors Exert Disparate Functions in Tumor Cells versus the Host Tissue Microenvironment in Melanoma Invasion and Metastasis
Authors: Lee Sue-Chin , Fujiwara Yuko , Liu Jianxiong , Yue Junming , Shimizu Yoshibumi , Norman Derek D. , Wang Yaohong , Tsukahara Ryoko , Szabo Erzsebet , Patil Renukadevi , Banerjee Souvik , Miller Duane D. , Balazs Louisa , Ghosh Manik C. , Waters Christopher M. , Oravecz Tamas , Tigyi Gabor J.
Published: April 2023

Abstract
Autotaxin (ENPP2/ATX) and lysophosphatidic acid (LPA) receptors represent two key players in regulating cancer progression. The present study sought to understand the mechanistic role of LPA G protein–coupled receptors (GPCR), not only in the tumor cells but also in stromal cells of the tumor microenvironment. B16F10 melanoma cells predominantly express LPA5 and LPA2 receptors but lack LPA1. LPA dose dependently inhibited invasion of cells across a Matrigel layer. RNAi-mediated knockdown of LPA5 relieved the inhibitory effect of LPA on invasion without affecting basal invasion. This suggests that LPA5 exerts an anti-invasive action in melanoma cells in response to LPA. In addition, both siRNA-mediated knockdown and pharmacologic inhibition of LPA2 reduced the basal rate invasion. Unexpectedly, when probing the role of this GPCR in host tissues, it was found that the incidence of melanoma-derived lung metastasis was greatly reduced in LPA5 knockout (KO) mice compared with wild-type (WT) mice. LPA1-KO but not LPA2-KO mice also showed diminished melanoma-derived lung metastasis, suggesting that host LPA1 and LPA5 receptors play critical roles in the seeding of metastasis. The decrease in tumor cell residence in the lungs of LPA1-KO and LPA5-KO animals was apparent 24 hours after injection. However, KO of LPA1, LPA2, or LPA5 did not affect the subcutaneous growth of melanoma tumors.

Implications: These findings suggest that tumor and stromal LPA receptors, in particular LPA1 and LPA5, play different roles in invasion and the seeding of metastasis. Mol Cancer Res; 13(1); 174–85. ©2014 AACR.
Data from EZH2: Not EZHY (Easy) to Deal
Authors: Deb Gauri , Singh Anup Kumar , Gupta Sanjay
Published: April 2023

Abstract
Seminal discoveries have established that epigenetic modifications are important for driving tumor progression. Polycomb group (PcG) proteins are highly conserved epigenetic effectors that maintain, by posttranslational modification of histones, the silenced state of genes involved in critical biologic processes, including cellular development, stem cell plasticity, and tumor progression. PcG proteins are found in two multimeric protein complexes called Polycomb repressive complexes: PRC1 and PRC2. Enhancer of zeste homolog 2 (EZH2), catalytic core subunit of PRC2, epigenetically silences several tumor-suppressor genes by catalyzing the trimethylation of histone H3 at lysine 27, which serves as a docking site for DNA methyltransferases and histone deacetylases. Evidence suggests that overexpression of EZH2 is strongly associated with cancer progression and poor outcome in disparate cancers, including hematologic and epithelial malignancies. The regulatory circuit and molecular cues causing EZH2 deregulation vary in different cancer types. Therefore, this review provides a comprehensive overview on the oncogenic role of EZH2 during tumorigenesis and highlights the multifaceted role of EZH2, as either a transcriptional activator or repressor depending on the cellular context. Additional insight is provided on the recent understanding of the causes and consequences of EZH2 overexpression in specific cancer types. Finally, evidence is discussed on how EZH2 has emerged as a promising target in anticancer therapy and the prospects for targeting EZH2 without affecting global methylation status. Thus, a better understanding of the complex epigenetic regulatory network controlling EZH2 expression and target genes facilitates the design of novel therapeutic interventions. Mol Cancer Res; 12(5); 639–53. ©2014 AACR.
Data from Therapeutic Targeting of Nuclear γ-Tubulin in RB1-Negative Tumors
Authors: Lindström Lisa , Villoutreix Bruno O. , Lehn Sophie , Hellsten Rebecka , Nilsson Elise , Crneta Enisa , Olsson Roger , Alvarado-Kristensson Maria
Published: April 2023

Abstract
In addition to its cytosolic function, γ-tubulin is a chromatin-associated protein. Reduced levels of nuclear γ-tubulin increase the activity of E2 promoter-binding factors (E2F) and raise the levels of retinoblastoma (RB1) tumor suppressor protein. In tumor cells lacking RB1 expression, decreased γ-tubulin levels induce cell death. Consequently, impairment of the nuclear activity of γ-tubulin has been suggested as a strategy for targeted chemotherapy of RB1-deficient tumors; thus, tubulin inhibitors were tested to identify compounds that interfere with γ-tubulin. Interestingly, citral increased E2F activity but impaired microtubule dynamics while citral analogues, such citral dimethyl acetal (CDA), increased E2F activity without affecting microtubules. The cytotoxic effect of CDA on tumor cells was attenuated by increased expression of either RB1 or γ-tubulin, and increased by reduced levels of either RB1 or γ-tubulin. Mechanistic study, in silico and in vitro, demonstrated that CDA prevents GTP binding to γ-tubulin and suggested that the FDA-approved drug dimethyl fumarate is also a γ-tubulin inhibitor. Finally, in vivo growth of xenograft tumors carrying defects in the RB1 signaling pathway were inhibited by CDA treatment. These results demonstrate that inhibition of γ-tubulin has the potential to specifically target tumor cells and may aid in the design of safer and more efficient chemotherapeutic regimes.

Implications: The in vivo antitumorigenic activity of γ-tubulin inhibitors paves the way for the development of a novel broad range targeted anticancer therapy that causes fewer side effects. Mol Cancer Res; 13(7); 1073–82. ©2015 AACR.
Data from The Cytoskeletal Adapter Protein Spinophilin Regulates Invadopodia Dynamics and Tumor Cell Invasion in Glioblastoma
Authors: Cheerathodi Mujeeburahiman , Avci Naze G. , Guerrero Paola A. , Tang Leung K. , Popp Julia , Morales John E. , Chen Zhihua , Carnero Amancio , Lang Frederick F. , Ballif Bryan A. , Rivera Gonzalo M. , McCarty Joseph H.
Published: April 2023

Abstract
Glioblastoma is a primary brain cancer that is resistant to all treatment modalities. This resistance is due, in large part, to invasive cancer cells that disperse from the main tumor site, escape surgical resection, and contribute to recurrent secondary lesions. The adhesion and signaling mechanisms that drive glioblastoma cell invasion remain enigmatic, and as a result there are no effective anti-invasive clinical therapies. Here we have characterized a novel adhesion and signaling pathway comprised of the integrin αvβ8 and its intracellular binding partner, Spinophilin (Spn), which regulates glioblastoma cell invasion in the brain microenvironment. We show for the first time that Spn binds directly to the cytoplasmic domain of β8 integrin in glioblastoma cells. Genetically targeting Spn leads to enhanced invasive cell growth in preclinical models of glioblastoma. Spn regulates glioblastoma cell invasion by modulating the formation and dissolution of invadopodia. Spn-regulated invadopodia dynamics are dependent, in part, on proper spatiotemporal activation of the Rac1 GTPase. Glioblastoma cells that lack Spn showed diminished Rac1 activities, increased numbers of invadopodia, and enhanced extracellular matrix degradation. Collectively, these data identify Spn as a critical adhesion and signaling protein that is essential for modulating glioblastoma cell invasion in the brain microenvironment.

Implications: Tumor cell invasion is a major clinical obstacle in glioblastoma and this study identifies a new signaling pathway regulated by Spinophilin in invasive glioblastoma. Mol Cancer Res; 14(12); 1277–87. ©2016 AACR.
Data from Differential Response of Glioma Stem Cells to Arsenic Trioxide Therapy Is Regulated by MNK1 and mRNA Translation
Authors: Bell Jonathan B. , Eckerdt Frank , Dhruv Harshil D. , Finlay Darren , Peng Sen , Kim Seungchan , Kroczynska Barbara , Beauchamp Elspeth M. , Alley Kristen , Clymer Jessica , Goldman Stewart , Cheng Shi-Yuan , James C. David , Nakano Ichiro , Horbinski Craig , Mazar Andrew P. , Vuori Kristiina , Kumthekar Priya , Raizer Jeffrey , Berens Michael E. , Platanias Leonidas C.
Published: April 2023

Abstract
Mesenchymal (MES) and proneural (PN) are two distinct glioma stem cell (GSC) populations that drive therapeutic resistance in glioblastoma (GBM). We screened a panel of 650 small molecules against patient-derived GBM cells to discover compounds targeting specific GBM subtypes. Arsenic trioxide (ATO), an FDA-approved drug that crosses the blood–brain barrier, was identified as a potent PN-specific compound in the initial screen and follow-up validation studies. Furthermore, MES and PN GSCs exhibited differential sensitivity to ATO. As ATO has been shown to activate the MAPK-interacting kinase 1 (MNK1)-eukaryotic translation initiation factor 4E (eIF4E) pathway and subsequent mRNA translation in a negative regulatory feedback manner, the mechanistic role of ATO resistance in MES GBM was explored. In GBM cells, ATO-activated translation initiation cellular events via the MNK1–eIF4E signaling axis. Furthermore, resistance to ATO in intracranial PDX tumors correlated with high eIF4E phosphorylation. Polysomal fractionation and microarray analysis of GBM cells were performed to identify ATO's effect on mRNA translation and enrichment of anti-apoptotic mRNAs in the ATO-induced translatome was found. Additionally, it was determined that MNK inhibition sensitized MES GSCs to ATO in neurosphere and apoptosis assays. Finally, examination of the effect of ATO on patients from a phase I/II clinical trial of ATO revealed that PN GBM patients responded better to ATO than other subtypes as demonstrated by longer overall and progression-free survival.

Implications: These findings raise the possibility of a unique therapeutic approach for GBM, involving MNK1 targeting to sensitize MES GSCs to drugs like arsenic trioxide. Mol Cancer Res; 16(1); 32–46. ©2017 AACR.
Data from mTOR Inhibition Potentiates HSP90 Inhibitor Activity via Cessation of HSP Synthesis
Authors: Acquaviva Jaime , He Suqin , Sang Jim , Smith Donald L. , Sequeira Manuel , Zhang Chaohua , Bates Richard C. , Proia David A.
Published: April 2023

Abstract
Because of their pleiotropic effects on critical oncoproteins, inhibitors of HSP90 represent a promising new class of therapeutic agents for the treatment of human cancer. However, pharmacologic inactivation of HSP90 subsequently triggers a heat shock response that may mitigate the full therapeutic benefit of these compounds. To overcome this limitation, a clinically feasible method was sought to block HSP synthesis induced by the potent HSP90 inhibitor ganetespib. An immunoassay screen of 322 late-stage or clinically approved drugs was performed to uncover compounds that could block upregulation of the stress-inducible HSP70 that results as a consequence of HSP90 blockade. Interestingly, inhibitors of the phosphoinositide 3-kinase (PI3K)/mTOR class counteracted ganetespib-induced HSP70 upregulation at both the gene and protein level by suppressing nuclear translocation of heat shock factor 1 (HSF1), the dominant transcription factor controlling cellular stress responses. This effect was conserved across multiple tumor types and was found to be regulated, in part, by mTOR-dependent translational activity. Pretreatment with cycloheximide, PI3K/mTOR inhibitor, or an inhibitor of eIF4E (a translation initiation factor and downstream effector of mTOR) all reduced ganetespib-mediated nuclear HSF1 accumulation, indicating that mTOR blockade confers a negative regulatory effect on HSF1 activity. Moreover, combined therapy regimens with mTOR or dual PI3K/mTOR inhibitors potentiated the antitumor efficacy of ganetespib in multiple in vivo models.

Implications: Collectively these data identify a novel strategy to optimize the therapeutic potential of HSP90 inhibitors. Mol Cancer Res; 12(5); 703–13. ©2014 AACR.
Data from Depleting Tumor-NQO1 Potentiates Anoikis and Inhibits Growth of NSCLC
Authors: Madajewski Brian , Boatman Michael A. , Chakrabarti Gaurab , Boothman David A. , Bey Erik A.
Published: April 2023

Abstract
The fundamental role that NAD(P)H/quinone oxidoreductase 1 (NQO1) plays, in normal cells, as a cytoprotective enzyme guarding against stress induced by reactive oxygen species (ROS) is well documented. However, what is not known is whether the observed overexpression of NQO1 in neoplastic cells contributes to their survival. The current study discovered that depleting NQO1 expression in A549 and H292 lung adenocarcinoma cells caused an increase in ROS formation, inhibited anchorage-independent growth, increased anoikis sensitization, and decreased three-dimensional tumor spheroid invasion. These in vivo data further implicate tumor-NQO1 expression in a protumor survival role, because its depletion suppressed cell proliferation and decreased lung tumor xenograft growth. Finally, these data reveal an exploitable link between tumor-NQO1 expression and the survival of lung tumors because NQO1 depletion significantly decreased the percentage of ALDH(high) cancer cells within the tumor population.

Implications: Loss of tumor-NQO1 expression inhibits tumor growth and suggests that novel therapeutics directed at tumor-NQO1 may have clinical benefit. Mol Cancer Res; 14(1); 14–25. ©2015 AACR.
Data from Dual Promoter Usage as Regulatory Mechanism of let-7c Expression in Leukemic and Solid Tumors
Authors: Pelosi Andrea , Careccia Silvia , Sagrestani Giulia , Nanni Simona , Manni Isabella , Schinzari Valeria , Martens Joost H.A. , Farsetti Antonella , Stunnenberg Hendrik G. , Gentileschi Maria Pia , Del Bufalo Donatella , De Maria Ruggero , Piaggio Giulia , Rizzo Maria Giulia
Published: April 2023

Abstract
Let-7c, an intronic microRNA (miRNA) embedded in the long non-coding gene LINC00478, can act as a tumor suppressor by targeting oncogenes. Previous studies indicated that in acute promyelocytic leukemia (APL), a subtype of acute myelogenous leukemia (AML) bearing the leukemia promoting PML/RARα fusion protein, let-7c expression seems to be controlled by the host gene promoter, in which canonical Retinoic Acid Responsive Elements (RAREs) are bound by PML/RARα in an all transretinoic acid (ATRA)–sensitive manner. Here, let-7c transcriptional regulation was further investigated and a novel intronic promoter upstream of the pre-miRNA was identified. This new promoter has transcriptional activity strongly indicating that at least two promoters need to be considered for let-7c transcription: the distal host gene and the proximal intronic promoter. Therefore, epigenetic modifying enzymes and histone acetylation and methylation status were analyzed on both let-7c promoters. It was demonstrated that ATRA treatment leads to let-7c upregulation inducing a more open chromatin conformation of the host gene promoter, with an enrichment of epigenetic marks that correlate with a more active transcriptional state. Conversely, the epigenetic marks on the intronic promoter are not significantly affected by ATRA treatment. Interestingly, in solid tumors such as prostate and lung adenocarcinoma it was found that both host and intronic promoters are functional. These data suggest that while the host gene promoter may control let-7c expression in AML, in a nonleukemic tumor context instead the intronic promoter contributes or preferentially regulates let-7c transcription.

Implications: Alternative promoter usage represents a regulatory mechanism of let-7c expression in different tissues. Mol Cancer Res; 12(6); 878–89. ©2014 AACR.
Data from PTEN Deficiency Mediates a Reciprocal Response to IGFI and mTOR Inhibition
Authors: Patel Mukund , Gomez Nicholas C. , McFadden Andrew W. , Moats-Staats Billie M. , Wu Sam , Rojas Andres , Sapp Travis , Simon Jeremy M. , Smith Scott V. , Kaiser-Rogers Kathleen , Davis Ian J.
Published: April 2023

Abstract
Recent evidence implicates the insulin-like growth factor (IGF) pathway in development of Ewing sarcoma, a highly malignant bone and soft-tissue tumor that primarily affects children and young adults. Despite promising results from preclinical studies of therapies that target this pathway, early-phase clinical trials have shown that a significant fraction of patients do not benefit, suggesting that cellular factors determine tumor sensitivity. Using FAIRE-seq, a chromosomal deletion of the PTEN locus in a Ewing sarcoma cell line was identified. In primary tumors, PTEN deficiency was observed in a large subset of cases, although not mediated by large chromosomal deletions. PTEN loss resulted in hyperactivation of the AKT signaling pathway. PTEN rescue led to decreased proliferation, inhibition of colony formation, and increased apoptosis. Strikingly, PTEN loss decreased sensitivity to IGF1R inhibitors but increased responsiveness to temsirolimus, a potent mTOR inhibitor, as marked by induction of autophagy. These results suggest that PTEN is lost in a significant fraction of primary tumors, and this deficiency may have therapeutic consequences by concurrently attenuating responsiveness to IGF1R inhibition while increasing activity of mTOR inhibitors. The identification of PTEN status in the tumors of patients with recurrent disease could help guide the selection of therapies.

Implications: PTEN status in Ewing sarcoma affects cellular responses to IGFI and mTOR-directed therapy, thus justifying its consideration as a biomarker in future clinical trials. Mol Cancer Res; 12(11); 1610–20. ©2014 AACR.
Data from SMAD4 Suppresses AURKA-Induced Metastatic Phenotypes via Degradation of AURKA in a TGFβ-Independent Manner
Authors: Jia Lina , Lee Hun Seok , Wu Chun Fu , Kundu Juthika , Park Sang Gyu , Kim Ryong Nam , Wang Li-Hui , Erkin Özgür Cem , Choi Jong-Sun , Chae Seoung Wan , Yang Ho Bin , Choi Yoon-La , Shin Young Kee
Published: April 2023

Abstract
SMAD4 has been suggested to inhibit the activity of the WNT/β-catenin signaling pathway in cancer. However, the mechanism by which SMAD4 antagonizes WNT/β-catenin signaling in cancer remains largely unknown. Aurora A kinase (AURKA), which is frequently overexpressed in cancer, increases the transcriptional activity of β-catenin/T-cell factor (TCF) complex by stabilizing β-catenin through the inhibition of GSK-3β. Here, SMAD4 modulated AURKA in a TGFβ-independent manner. Overexpression of SMAD4 significantly suppressed AURKA function, including colony formation, migration, and invasion of cell lines. In addition, SMAD4 bound to AURKA induced degradation of AURKA by the proteasome. A luciferase activity assay revealed that the transcriptional activity of the β-catenin/TCF complex was elevated by AURKA, but decreased by SMAD4 overexpression. Moreover, target gene analysis showed that SMAD4 abrogated the AURKA-mediated increase of β-catenin target genes. However, this inhibitory effect of SMAD4 was abolished by overexpression of AURKA or silencing of AURKA in SMAD4-overexpressed cells. Meanwhile, the SMAD4-mediated repression of AURKA and β-catenin was independent of TGFβ signaling because blockage of TGFβR1 or restoration of TGFβ signaling did not prevent suppression of AURKA and β-catenin signaling by SMAD4. These results indicate that the tumor-suppressive function of SMAD4 is mediated by downregulation of β-catenin transcriptional activity via AURKA degradation in a TGFβ-independent manner.

Implications: SMAD4 interacts with AURKA and antagonizes its tumor-promoting potential, thus demonstrating a novel mechanism of tumor suppression. Mol Cancer Res; 12(12); 1779–95. ©2014 AACR.
Data from Loss of Keratinocytic RXRα Combined with Activated CDK4 or Oncogenic NRAS Generates UVB-Induced Melanomas via Loss of p53 and PTEN in the Tumor Microenvironment
Authors: Coleman Daniel J. , Chagani Sharmeen , Hyter Stephen , Sherman Anna M. , Löhr Christiane V. , Liang Xiaobo , Ganguli-Indra Gitali , Indra Arup K.
Published: April 2023

Abstract
Understanding the molecular mechanisms behind formation of melanoma, the deadliest form of skin cancer, is crucial for improved diagnosis and treatment. One key is to better understand the cross-talk between epidermal keratinocytes and pigment-producing melanocytes. Here, using a bigenic mouse model system combining mutant oncogenic NRASQ61K (constitutively active RAS) or mutant activated CDK4R24C/R24C (prevents binding of CDK4 by kinase inhibitor p16INK4A) with an epidermis-specific knockout of the nuclear retinoid X receptor alpha (RXRαep−/−) results in increased melanoma formation after chronic ultraviolet-B (UVB) irradiation compared with control mice with functional RXRα. Melanomas from both groups of bigenic RXRαep−/− mice are larger in size with higher proliferative capacity, and exhibit enhanced angiogenic properties and increased expression of malignant melanoma markers. Analysis of tumor adjacent normal skin from these mice revealed altered expression of several biomarkers indicative of enhanced melanoma susceptibility, including reduced expression of tumor suppressor p53 and loss of PTEN, with concomitant increase in activated AKT. Loss of epidermal RXRα in combination with UVB significantly enhances invasion of melanocytic cells to draining lymph nodes in bigenic mice expressing oncogenic NRASQ61K compared with controls with functional RXRα. These results suggest a crucial role of keratinocytic RXRα to suppress formation of UVB-induced melanomas and their progression to malignant cancers in the context of driver mutations such as activated CDK4R24C/R24C or oncogenic NRASQ61K.

Implications: These findings suggest that RXRα may serve as a clinical diagnostic marker and therapeutic target in melanoma progression and metastasis. Mol Cancer Res; 13(1); 186–96. ©2014 AACR.
Data from Novel Insights into Gastric Cancer: Methylation of R-spondins and Regulation of LGR5 by SP1
Authors: Wilhelm Franziska , Simon Eva , Böger Christine , Behrens Hans-Michael , Krüger Sandra , Röcken Christoph
Published: April 2023

Abstract
Recently, it was shown that leucine-rich repeat-containing receptor 5 (LGR5)–expressing stem cells are the cellular origin of intestinal-type gastric cancer. The aim of our study was to uncover regulatory mechanisms of LGR5 expression in gastric mucosa and their implications for cancer development. Reporter assays identified an LGR5 promoter fragment, which is highly relevant for active LGR5 expression. Chromatin immunoprecipitation verified that SP1 is bound within this region, and reporter activity increased in SP1 transfected cells. Subsequently, the expression of R-spondins (RSPO1 and RSPO2), ligands of LGR5, was explored in neoplastic and nonneoplastic gastric tissue and gastric cancer cell lines. Using IHC, distinct spatial expression patterns of LGR5, RSPO1, and RSPO2 were found in nonneoplastic stomach mucosa and gastric cancer. RSPO expression was lower in gastric cancer compared with nonneoplastic mucosa on both the transcriptional (P = 0.003 for RSPO1 and P = 0.000 for RSPO2; n = 50) and the translational level. Methylation-specific PCR showed higher methylation levels of RSPO1/2 and reexpression of RSPOs in the gastric cancer cell lines MKN45 and MKN74 were induced by demethylating 5-aza-C treatment. Finally, expression patterns of LGR5 and RSPO were similar in gastric cancer.

Implications: This report identifies a regulatory mechanism of LGR5 expression in gastric carcinogenesis, with SP1 as an important component of the transcriptional complex and LGR5 activity, which is modulated by its ligands RSPO1 and RSPO2, whose expression is modulated by methylation.

Visual Overview: http://mcr.aacrjournals.org/content/15/6/776/F1.large.jpg. Mol Cancer Res; 15(6); 776–85. ©2017 AACR.