bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from c-Src-p38 Mitogen-Activated Protein Kinase Signaling Is Required for Akt Activation in Response to Ionizing Radiation
Authors: Kim Min-Jung , Byun Joo-Yun , Yun Chang-Hwan , Park In-Chul , Lee Kee-Ho , Lee Su-Jae
Published: March 2024

Abstract
The Akt and mitogen-activated protein kinase (MAPK) pathways have been implicated in tumor cell survival and contribute to radiation resistance. However, the molecular basis for link between MAPK and Akt in cell survival response to radiation is unclear. Here, we show that c-Src-Rac1-p38 MAPK pathway signals Akt activation and cell survival in response to radiation. Ionizing radiation triggered Thr308 and Ser473 phosphorylation of Akt. Exposure of cells to radiation also induced p38 MAPK and c-Jun NH2-terminal kinase activations. Inhibition of c-Jun NH2-terminal kinase suppressed radiation-induced cell death, whereas inhibition of p38 MAPK effectively increased sensitivity to radiation. Interestingly, inhibition of p38 MAPK completely attenuated radiation-induced Ser473 phosphorylation of Akt but did not affect Thr308 phosphorylation. Conversely, overexpression of p38 MAPK enhanced Ser473 phosphorylation of Akt in response to radiation. In addition, inhibition of p38 MAPK failed to alter phosphoinositide 3-kinase and phosphoinositide-dependent protein kinase activities. Ectopic expression of RacN17, dominant-negative form of Rac1, inhibited p38 MAPK activation and Ser473 phosphorylation of Akt. Following exposure to radiation, c-Src was selectively activated among Src family tyrosine kinases. Inhibition of c-Src attenuated Rac1 and p38 MAPK activations and Ser473 phosphorylation of Akt. Our results support the notion that the c-Src-Rac1-p38 MAPK pathway is required for activation of Akt in response to radiation and plays a cytoprotective role against radiation in human cancer cells. (Mol Cancer Res 2008;6(12):1872–80)
Data from Aberrant Induction of a Mesenchymal/Stem Cell Program Engages Senescence in Normal Mammary Epithelial Cells
Authors: Bryson Benjamin L. , Tamagno Ilaria , Taylor Sarah E. , Parameswaran Neetha , Chernosky Noah M. , Balasubramaniam Nikhila , Jackson Mark W.
Published: March 2024

Abstract
Although frequently associated with tumor progression, inflammatory cytokines initially restrain transformation by inducing senescence, a key tumor-suppressive barrier. Here, we demonstrate that the inflammatory cytokine, oncostatin M, activates a mesenchymal/stem cell (SC) program that engages cytokine-induced senescence (CIS) in normal human epithelial cells. CIS is driven by Snail induction and requires cooperation between STAT3 and the TGFβ effector, SMAD3. Importantly, as cells escape CIS, they retain the mesenchymal/SC program and are thereby bestowed with a set of cancer SC (CSC) traits. Of therapeutic importance, cells that escape CIS can be induced back into senescence by CDK4/6 inhibition, confirming that the mechanisms allowing cells to escape senescence are targetable and reversible. Moreover, by combining CDK4/6 inhibition with a senolytic therapy, mesenchymal/CSCs can be efficiently killed. Our studies provide insight into how the CIS barriers that prevent tumorigenesis can be exploited as potential therapies for highly aggressive cancers.
Implications:
These studies reveal how a normal cell's arduous escape from senescence can bestow aggressive features early in the transformation process, and how this persistent mesenchymal/SC program can create a novel potential targetability following tumor development.
Data from The mRNA Stability Factor HuR Inhibits MicroRNA-16 Targeting of COX-2
Authors: Young Lisa E. , Moore Ashleigh E. , Sokol Lena , Meisner-Kober Nicole , Dixon Dan A.
Published: March 2024

Abstract
Commonly observed in colorectal cancer is the elevated expression of the prostaglandin (PG) synthase COX-2. In normal intestinal epithelium, the COX-2 mRNA is targeted for rapid decay through the 3′-untranslated region (3′-UTR) adenylate- and uridylate (AU)-rich element (ARE), whereas in tumors ARE-mediated decay is compromised. Here we show that the COX-2 ARE can mediate degradation through microRNA (miRNA)-mediated regulation. We identified miR-16 to bind the COX-2 3′-UTR and inhibit COX-2 expression by promoting rapid mRNA decay. In colorectal cancer cells and tumors, miR-16 levels were decreased approximately twofold and miR-16 expression in cancer cells attenuated COX-2 expression and PG synthesis. The COX-2 ARE is also bound by the RNA-binding protein HuR. In colorectal cancer tumors, HuR is overexpressed and localized within the cytoplasm, where it promotes ARE-mRNA stabilization. Under conditions of HuR overexpression, miR-16 was unable to promote rapid mRNA decay through the COX-2 ARE. Ribonucleoprotein immunoprecipitation of HuR showed direct association with miR-16 that was reversed when cytoplasmic trafficking of HuR was inhibited. Furthermore, this interaction between HuR and miR-16 promoted the downregulation of miR-16. These new results identify miR-16 as a central posttranscriptional regulator of COX-2 and show the ability of elevated levels of HuR to antagonize miR-16 function. Along with insight into altered ARE-mediated mRNA decay observed in colorectal cancer, these findings provide a new explanation for tumor-derived loss of miR-16. Mol Cancer Res; 10(1); 167–80. ©2011 AACR.
Data from miRNA Profiling in Colorectal Cancer Highlights miR-1 Involvement in MET-Dependent Proliferation
Authors: Reid James F. , Sokolova Viktorija , Zoni Eugenio , Lampis Andrea , Pizzamiglio Sara , Bertan Claudia , Zanutto Susanna , Perrone Federica , Camerini Tiziana , Gallino Gianfrancesco , Verderio Paolo , Leo Ermanno , Pilotti Silvana , Gariboldi Manuela , Pierotti Marco A.
Published: March 2024

Abstract
Altered expression of miRNAs is associated with development and progression of various human cancers by regulating the translation of oncogenes and tumor suppressor genes. In colorectal cancer, these regulators complement the Vogelstein multistep model of pathogenesis and have the potential of becoming a novel class of tumor biomarkers and therapeutic targets. Using quantitative real-time PCR, we measured the expression of 621 mature miRNAs in 40 colorectal cancers and their paired normal tissues and identified 23 significantly deregulated miRNAs. We subsequently evaluated their association with clinical characteristics of the samples and presence of alterations in the molecular markers of colorectal cancer progression. Expression levels of miR-31 were correlated with CA19-9 and miR-18a, miR-21, and miR-31 were associated with mutations in APC gene. To investigate the downstream regulation of the differentially expressed miRNAs identified, we integrated putative mRNA target predictions with the results of a meta-analysis of seven public gene expression datasets of normal and tumor samples of colorectal cancer patients. Many of the colorectal cancer deregulated miRNAs computationally mapped to targets involved in pathways related to progression. Here one promising candidate pair (miR-1 and MET) was studied and functionally validated. We show that miR-1 can have a tumor suppressor function in colorectal cancer by directly downregulating MET oncogene both at RNA and protein level and that reexpression of miR-1 leads to MET-driven reduction of cell proliferation and motility, identifying the miR-1 downmodulation as one of the events that could enhance colorectal cancer progression. Mol Cancer Res; 10(4); 504–15. ©2012 AACR.
Data from Yes-Associated Protein 1 Is Activated and Functions as an Oncogene in Meningiomas
Authors: Baia Gilson S. , Caballero Otavia L. , Orr Brent A. , Lal Anita , Ho Janelle S. Y. , Cowdrey Cynthia , Tihan Tarik , Mawrin Christian , Riggins Gregory J.
Published: March 2024

Abstract
The Hippo signaling pathway is functionally conserved in Drosophila melanogaster and mammals, and its proposed function is to control tissue homeostasis by regulating cell proliferation and apoptosis. The core components are composed of a kinase cascade that culminates with the phosphorylation and inhibition of Yes-associated protein 1 (YAP1). Phospho-YAP1 is retained in the cytoplasm. In the absence of Hippo signaling, YAP1 translocates to the nucleus, associates with co-activators TEAD1-4, and functions as a transcriptional factor promoting the expression of key target genes. Components of the Hippo pathway are mutated in human cancers, and deregulation of this pathway plays a role in tumorigenesis. Loss of the NF2 tumor suppressor gene is the most common genetic alteration in meningiomas, and the NF2 gene product, Merlin, acts upstream of the Hippo pathway. Here, we show that primary meningioma tumors have high nuclear expression of YAP1. In meningioma cells, Merlin expression is associated with phosphorylation of YAP1. Using an siRNA transient knockdown of YAP1 in NF2-mutant meningioma cells, we show that suppression of YAP1 impaired cell proliferation and migration. Conversely, YAP1 overexpression led to a strong augment of cell proliferation and anchorage-independent growth and restriction of cisplatin-induced apoptosis. In addition, expression of YAP1 in nontransformed arachnoidal cells led to the development of tumors in nude mice. Together, these findings suggest that in meningiomas, deregulation of the Hippo pathway is largely observed in primary tumors and that YAP1 functions as an oncogene promoting meningioma tumorigenesis. Mol Cancer Res; 10(7); 904–13. ©2012 AACR.
Data from Targeting Abnormal DNA Repair in Therapy-Resistant Breast Cancers
Authors: Tobin Lisa A. , Robert Carine , Nagaria Pratik , Chumsri Saranya , Twaddell William , Ioffe Olga B. , Greco George E. , Brodie Angela H. , Tomkinson Alan E. , Rassool Feyruz V.
Published: March 2024

Abstract
Although hereditary breast cancers have defects in the DNA damage response that result in genomic instability, DNA repair abnormalities in sporadic breast cancers have not been extensively characterized. Recently, we showed that, relative to nontumorigenic breast epithelial MCF10A cells, estrogen receptor–positive (ER+) MCF7 breast cancer cells and progesterone receptor–positive (PR+) MCF7 breast cancer cells have reduced steady-state levels of DNA ligase IV, a component of the major DNA–protein kinase (PK)-dependent nonhomologous end joining (NHEJ) pathway, whereas the steady-state level of DNA ligase IIIα, a component of the highly error-prone alternative NHEJ (ALT NHEJ) pathway, is increased. Here, we show that tamoxifen- and aromatase-resistant derivatives of MCF7 cells and ER−/PR− cells have even higher steady-state levels of DNA ligase IIIα and increased levels of PARP1, another ALT NHEJ component. This results in increased dependence upon microhomology-mediated ALT NHEJ to repair DNA double-strand breaks (DSB) and the accumulation of chromosomal deletions. Notably, therapy-resistant derivatives of MCF7 cells and ER−/PR− cells exhibited significantly increased sensitivity to a combination of PARP and DNA ligase III inhibitors that increased the number of DSBs. Biopsies from ER−/PR− tumors had elevated levels of ALT NHEJ and reduced levels of DNA–PK-dependent NHEJ factors. Thus, our results show that ALT NHEJ is a novel therapeutic target in breast cancers that are resistant to frontline therapies and suggest that changes in NHEJ protein levels may serve as biomarkers to identify tumors that are candidates for this therapeutic approach. Mol Cancer Res; 10(1); 96–107. ©2011 AACR.
Data from PRSS3/Mesotrypsin Is a Therapeutic Target for Metastatic Prostate Cancer
Authors: Hockla Alexandra , Miller Erin , Salameh Moh'd A. , Copland John A. , Radisky Derek C. , Radisky Evette S.
Published: March 2024

Abstract
PRSS3/mesotrypsin is an atypical isoform of trypsin that has been associated with breast, lung, and pancreatic cancer cell malignancy. In analyses of open source transcriptional microarray data, we find that PRSS3 expression is upregulated in metastatic prostate cancer tissue, and that expression of PRSS3 in primary prostate tumors is prognostic of systemic progression following prostatectomy. Using a mouse orthotopic model with bioluminescent imaging, we show that PRSS3/mesotrypsin is critical for prostate cancer metastasis. Silencing of PRSS3 inhibits anchorage-independent growth of prostate cancer cells in soft agar assays, and suppresses invasiveness in Matrigel transwell assays and three-dimensional (3D) cell culture models. We further show that treatment with recombinant mesotrypsin directly promotes an invasive cellular phenotype in prostate cancer cells and find that these effects are specific and require the proteolytic activity of mesotrypsin, because neither cationic trypsin nor a mesotrypsin mutant lacking activity can drive the invasive phenotype. Finally, we show that a newly developed, potent inhibitor of mesotrypsin activity can suppress prostate cancer cell invasion to a similar extent as PRSS3 gene silencing. This study defines mesotrypsin as an important mediator of prostate cancer progression and metastasis, and suggests that inhibition of mesotrypsin activity may provide a novel modality for prostate cancer treatment. Mol Cancer Res; 10(12); 1555–66. ©2012 AACR.
Data from Active Ras Triggers Death in Glioblastoma Cells through Hyperstimulation of Macropinocytosis
Authors: Overmeyer Jean H. , Kaul Aparna , Johnson Erin E. , Maltese William A.
Published: March 2024

Abstract
Expression of activated Ras in glioblastoma cells induces accumulation of large phase-lucent cytoplasmic vacuoles, followed by cell death. This was previously described as autophagic cell death. However, unlike autophagosomes, the Ras-induced vacuoles are not bounded by a double membrane and do not sequester organelles or cytoplasm. Moreover, they are not acidic and do not contain the autophagosomal membrane protein LC3-II. Here we show that the vacuoles are enlarged macropinosomes. They rapidly incorporate extracellular fluid-phase tracers but do not sequester transferrin or the endosomal protein EEA1. Ultimately, the cells expressing activated Ras detach from the substratum and rupture, coincident with the displacement of cytoplasm with huge macropinosome-derived vacuoles. These changes are accompanied by caspase activation, but the broad-spectrum caspase inhibitor carbobenzoxy-Val-Ala-Asp-fluoromethylketone does not prevent cell death. Moreover, the majority of degenerating cells do not exhibit chromatin condensation typical of apoptosis. These observations provide evidence for a necrosis-like form of cell death initiated by dysregulation of macropinocytosis, which we have dubbed “methuosis.” An activated form of the Rac1 GTPase induces a similar form of cell death, suggesting that Ras acts through Rac-dependent signaling pathways to hyperstimulate macropinocytosis in glioblastoma. Further study of these signaling pathways may lead to the identification of other chemical and physiologic triggers for this unusual form of cell death. (Mol Cancer Res 2008;6(6):965–77)
Data from TCF21 Promotes Luminal-Like Differentiation and Suppresses Metastasis in Bladder Cancer
Authors: Mokkapati Sharada , Porten Sima P. , Narayan Vikram M. , Lim Amy H. , Jayaratna Isuru S. , Roth Beat , Cheng Tiewei , Navai Neema , Wszolek Matthew , Melquist Jonathan , Manyam Ganiraju , Choi Woonyoung , Broom Bradley , Pretzsch Shanna , Czerniak Bogdan , McConkey David J. , Dinney Colin P. N.
Published: March 2024

Abstract
Little is known regarding the subclone evolution process in advanced bladder cancer, particularly with respect to the genomic alterations that lead to the development of metastatic lesions. In this project, we identify gene expression signatures associated with metastatic bladder cancer through mRNA expression profiling of RNA isolated from 33 primary bladder cancer and corresponding lymph node (LN) metastasis samples. Gene expression profiling (GEP) was performed on RNA isolated using the Illumina DASL platform. We identified the developmental transcription factor TCF21 as being significantly higher in primary bladder cancer compared with LN metastasis samples. To elucidate its function in bladder cancer, loss- and gain-of-function experiments were conducted in bladder cancer cell lines with high and low expression of TCF21, respectively. We also performed GEP in bladder cancer cell lines following TCF21 overexpression. We identified 2,390 genes differentially expressed in primary bladder cancer and corresponding LN metastasis pairs at an FDR cutoff of 0.1 and a fold change of 1. Among those significantly altered, expression of TCF21 was higher in the primary tumor compared with LN metastasis. We validated this finding with qPCR and IHC on patient samples. Moreover, TCF21 expression was higher in luminal cell lines and knockdown of TCF21 increased invasion, tumor cell dissemination, and metastasis. In contrast, overexpression of TCF21 in highly metastatic basal bladder cancer cell lines decreased their invasive and metastatic potential.
Implications:
TCF21 is differentially overexpressed in primary bladder cancer compared with matched LN metastasis, with in vitro and in vivo studies demonstrating a metastasis suppressor function of this transcription factor.
Data from Environmental Estrogens Differentially Engage the Histone Methyltransferase EZH2 to Increase Risk of Uterine Tumorigenesis
Authors: Greathouse K. Leigh , Bredfeldt Tiffany , Everitt Jeffrey I. , Lin Kevin , Berry Tia , Kannan Kurunthachalam , Mittelstadt Megan L. , Ho Shuk-mei , Walker Cheryl L.
Published: March 2024

Abstract
Environmental exposures during sensitive windows of development can reprogram normal physiologic responses and alter disease susceptibility later in life in a process known as developmental reprogramming. For example, exposure to the xenoestrogen diethylstilbestrol during reproductive tract development can reprogram estrogen-responsive gene expression in the myometrium, resulting in hyperresponsiveness to hormone in the adult uterus and promotion of hormone-dependent uterine leiomyoma. We show here that the environmental estrogens genistein, a soy phytoestrogen, and the plasticizer bisphenol A, differ in their pattern of developmental reprogramming and promotion of tumorigenesis (leiomyomas) in the uterus. Whereas both genistein and bisphenol A induce genomic estrogen receptor (ER) signaling in the developing uterus, only genistein induced phosphoinositide 3-kinase (PI3K)/AKT nongenomic ER signaling to the histone methyltransferase enhancer of zeste homolog 2 (EZH2). As a result, this pregenomic signaling phosphorylates and represses EZH2 and reduces levels of H3K27me3 repressive mark in chromatin. Furthermore, only genistein caused estrogen-responsive genes in the adult myometrium to become hyperresponsive to hormone; estrogen-responsive genes were repressed in bisphenol A–exposed uteri. Importantly, this pattern of EZH2 engagement to decrease versus increase H3K27 methylation correlated with the effect of these xenoestrogens on tumorigenesis. Developmental reprogramming by genistein promoted development of uterine leiomyomas, increasing tumor incidence and multiplicity, whereas bisphenol A did not. These data show that environmental estrogens have distinct nongenomic effects in the developing uterus that determines their ability to engage the epigenetic regulator EZH2, decrease levels of the repressive epigenetic histone H3K27 methyl mark in chromatin during developmental reprogramming, and promote uterine tumorigenesis. Mol Cancer Res; 10(4); 546–57. ©2012 AACR.
Data from Expression of G Protein-Coupled Receptor 19 in Human Lung Cancer Cells Is Triggered by Entry into S-Phase and Supports G2–M Cell-Cycle Progression
Authors: Kastner Stefan , Voss Tilman , Keuerleber Simon , Glöckel Christina , Freissmuth Michael , Sommergruber Wolfgang
Published: March 2024

Abstract
It has long been known that G protein-coupled receptors (GPCR) are subject to illegitimate expression in tumor cells. Presumably, hijacking the normal physiologic functions of GPCRs contributes to all biologic capabilities acquired during tumorigenesis. Here, we searched for GPCRs that were expressed in lung cancer: the mRNA encoding orphan G protein-coupled receptor 19 (GPR19) was found frequently overexpressed in tissue samples obtained from patients with small cell lung cancer. Several observations indicate that overexpression of Gpr19 confers a specific advantage to lung cancer cells by accelerating transition through the cell-cycle. (i) Knockdown of Gpr19 mRNA by RNA interference reduced cell growth of human lung cancer cell lines. (ii) Cell-cycle progression through G2–M-phase was impaired in cells transfected with siRNAs directed against Gpr19 and this was associated with increased protein levels of cyclin B1 and phosphorylated histone H3. (iii) The expression levels of Gpr19 mRNA varied along the cell-cycle with a peak observed in S-phase. (iv) The putative control of Gpr19 expression by E2F transcription factors was verified by chromatin immunoprecipitation: antibodies directed against E2F-1 to -4 allowed for the recovery of the Gpr19 promoter. (v) Removal of E2F binding sites in the Gpr19 promoter diminished the expression of a luciferase reporter. (vi) E2f and Gpr19 expression correlated in lung cancer patient samples. To the best of knowledge, this is the first example of a GPCR showing cell-cycle-specific mRNA expression. Our data also validate GPR19 as a candidate target when overexpressed in lung cancer. Mol Cancer Res; 10(10); 1343–58. ©2012 AACR.
Data from Exosomal Annexin II Promotes Angiogenesis and Breast Cancer Metastasis
Authors: Maji Sayantan , Chaudhary Pankaj , Akopova Irina , Nguyen Phung M. , Hare Richard J. , Gryczynski Ignacy , Vishwanatha Jamboor K.
Published: March 2024

Abstract
Tumor-derived exosomes are emerging mediators of tumorigenesis and tissue-specific metastasis. Proteomic profiling has identified Annexin II as one of the most highly expressed proteins in exosomes; however, studies focused on the biological role of exosomal Annexin II (exo-Anx II) are still lacking. In this study, mechanistic insight was sought regarding exo-Anx II and its function in angiogenesis and breast cancer metastasis. Multiple in vitro and in vivo techniques were used to study the role of exo-Anx II in angiogenesis. Using atomic force microscopy and Western blotting, exo-Anx II expression was characterized in normal and breast cancer cells. In addition, organ-specific metastatic breast cancer cells and animal models were used to define the role exo-Anx II in breast cancer metastasis. Results revealed that exo-Anx II expression is significantly higher in malignant cells than normal and premetastatic breast cancer cells. In vitro and in vivo studies demonstrated that exo-Anx II promotes tPA-dependent angiogenesis. Furthermore, in vivo analysis indicated that metastatic exosomes create a favorable microenvironment for metastasis, and exo-Anx II plays an important role in this process, as priming with Anx II-depleted exosomes reduces brain (∼4-fold) and lung (∼2-fold) metastasis. Upon delineating the mechanism, it was discovered that exo-Anx II causes macrophage-mediated activation of the p38MAPK, NF-κB, and STAT3 pathways and increased secretion of IL6 and TNFα. These data demonstrate an important role for exo-Anx II in breast cancer pathogenesis.

Implications: Exosome-associated Annexin II plays an important role in angiogenesis and breast cancer metastasis, which can be exploited as a potential biomarker as well as a therapeutic target for diagnosis and treatment of metastatic breast cancer. Mol Cancer Res; 15(1); 93–105. ©2016 AACR.
Data from Sensitizing B- and T- cell Lymphoma Cells to Paclitaxel/Abraxane–Induced Death by AS101 via Inhibition of the VLA-4–IL10–Survivin Axis
Authors: Danoch Hila , Kalechman Yona , Albeck Michael , Longo Dan L. , Sredni Benjamin
Published: March 2024

Abstract
Cancer cell resistance to chemotherapy is a major concern in clinical oncology, resulting in increased tumor growth and decreased patient survival. Manipulation of apoptosis has emerged as a new therapeutic strategy to eliminate cancer cells. The focus of this study resides within a novel approach to target survivin, an integrator of both cell death and mitosis. This protein plays a pivotal role in the resistance of tumors to chemotherapy, especially to paclitaxel. The data herein demonstrate an indirect repression of survivin in both B- and T-cell lymphoma and human NHL by the nontoxic tellurium compound, AS101 [ammonium trichloro(dioxoethylene-o,o′)tellurate], via inhibition of tumor autocrine IL10–STAT3–Survivin signaling. As a result of survivin abrogation, sensitization of lymphomas to paclitaxel or to Abraxane, the new albumin-stabilized nanoparticle formulation of paclitaxel, occurs both in vitro and in vivo. Importantly, inhibition of lymphoma cell IL10 secretion is mediated by inactivation of the VLA-4 integrin, recently shown to be an important target of AS101. This activity is followed by inhibition of the PI3K–AKT axis that mediates IL10 suppression. Because a wide variety of lymphomas and other tumor types express VLA-4 and secrete IL10 in an autocrine manner, inhibition of survivin with a small nontoxic agent has vast clinical significance in modulating chemosensitivity in many tumor types.

Implications: Combination therapy with AS101 and paclitaxel has novel therapeutic potential targeting deregulated active pathways in lymphoma, overcoming endogenous resistance to apoptosis. Mol Cancer Res; 13(3); 411–22. ©2014 AACR.
Data from Gut-derived Endotoxin-TLR4 Signaling Drives MYC-Ig Translocation to Promote Lymphoproliferation through c-JUN and STAT3 Activation
Authors: Rokan Ahmed , Hernandez Juan Carlos , Nitiyanandan Rajeshwar , Lin Zi-Ying , Chen Chia-Lin , Machida Tatsuya , Li Meng , Khanuja Jasleen , Chen Mo Li , Tahara Stanley M. , Siddiqi Imran , Machida Keigo
Published: March 2024

Abstract
Synergism between obesity and virus infection promotes the development of B-cell lymphoma. In this study, we tested whether obesity-associated endotoxin release induced activation-induced cytidine deaminase (AID). TLR4 activation in turn caused c-JUN–dependent and STAT3-dependent translocations of MYC loci to suppress transactivation of CD95/FAS. We used viral nucleocapside Core transgenic (Tg) mice fed alcohol Western diet to determine whether oncogenesis arising from obesity and chronic virus infection occurred through TLR4-c-JUN-STAT3 pathways. Our results showed B cell–specific, c-Jun and/or Stat3 disruption reduced the incidence of splenomegaly in these mice. AID-dependent t(8;14) translocation was observed between the Ig promoter and MYC loci. Comparison with human B cells showed MYC-immunoglobulin (Ig) translocations after virus infection with lipopolysaccharide stimulation. Accordingly, human patients with lymphoma with virus infections and obesity showed a 40% incidence of MYC-Ig translocations. Thus, obesity and virus infection promote AID-mediated translocation between the Ig promoter and MYC through the TLR4-c-JUN axis, resulting in lymphoproliferation. Taken together, preventative treatment targeting either c-JUN and/or STAT3 may be effective strategies to prevent tumor development.
Implications:
Obesity increases gut-derived endotoxin which induces Toll-like receptor–mediated MYC-Ig translocation via c-JUN-STAT3, leading to lymphoproliferation.
Data from Heparanase-Induced GEF-H1 Signaling Regulates the Cytoskeletal Dynamics of Brain Metastatic Breast Cancer Cells
Authors: Ridgway Lon D. , Wetzel Michael D. , Ngo Jason A. , Erdreich-Epstein Anat , Marchetti Dario
Published: March 2024

Abstract
Heparanase is the only mammalian endoglycosidase which has been widely implicated in cancer because of its capability to degrade heparan sulfate chains of heparan sulfate proteoglycans (HSPG). Specifically, the cell surface HSPG syndecan-1 and -4 (SDC1 and SDC4) are modulators of growth factor action, and SDC4 is implicated in cell adhesion as a key member of focal adhesion complexes. We hypothesized that extracellular heparanase modulates brain metastatic breast cancer (BMBC) cell invasiveness by affecting cytoskeletal dynamics, SDC4 carboxy-terminal–associated proteins, and downstream targets. We used two independently derived human BMBC cell systems (MB-231BR and MB-231BR3), which possess distinct cellular morphologies and properties. Highly aggressive spindle-shaped 231BR3 cells changed to a round cell morphology associated with expression of the small GTPase guanine nucleotide exchange factor-H1 (GEF-H1). We showed that GEF-H1 is a new component of the SDC4 signaling complex in BMBC cells. Treatment with heparanase resulted in regulation of the SDC4/protein kinase C α axis while maintaining a constitutive GEF-H1 level. Third, GEF-H1 knockdown followed by cell exposure to heparanase caused a significant regulation of activities of Rac1 and RhoA, which are GEF-H1 targets and fundamental effectors in cell plasticity control. Fourth, L-heparanase augmented expression of β1 integrin in BMBC cells and of vascular cell adhesion molecule 1 (VCAM1; the major β1 integrin receptor) in human brain microvascular endothelial cells. Finally, using a newly developed blood–brain barrier in vitro model, we show that BMBC cell transmigration was significantly reduced in GEF-H1 knockdown cells. These findings implicate heparanase in mechanisms of cytoskeletal dynamics and in the cross-talk between tumor cells and vascular brain endothelium. They are of relevance because they elucidate molecular events in the initial steps leading to BMBC onset and capturing distinct roles of latent and active heparanase in the brain microenvironment. Mol Cancer Res; 10(6); 689–702. ©2012 AACR.
Data from MUC1 Drives c-Met–Dependent Migration and Scattering
Authors: Horm Teresa M. , Bitler Benjamin G. , Broka Derrick M. , Louderbough Jeanne M. , Schroeder Joyce A.
Published: March 2024

Abstract
The transmembrane mucin MUC1 is overexpressed in most ductal carcinomas, and its overexpression is frequently associated with metastatic progression. MUC1 can drive tumor initiation and progression via interactions with many oncogenic partners, including β-catenin, the EGF receptor (EGFR) and Src. The decoy peptide protein transduction domain MUC1 inhibitory peptide (PMIP) has been shown to inhibit the tumor promoting activities of MUC1 in breast and lung cancer, including cell growth and invasion, and its usage suppresses metastatic progression in mouse models of breast cancer. To further characterize the reduced metastasis observed upon PMIP treatment, we conducted motility assays and observed that PMIP inhibits cell motility of breast cancer cells. To determine the mechanism by which PMIP inhibits motility, we evaluated changes in global gene transcription upon PMIP treatment, and identified a number of genes with altered expression in response to PMIP. Among these genes is the metastatic mediator, c-Met, a transmembrane tyrosine kinase that can promote cell scattering, migration, and invasion. To further investigate the role of c-Met in MUC1-dependent metastatic events, we evaluated the effects of MUC1 expression and EGFR activation on breast cancer cell scattering, branching, and migration. We found that MUC1 strongly promoted all of these events and this effect was further amplified by EGF treatment. Importantly, the effect of MUC1 and EGF on these phenotypes was dependent upon c-Met activity. Overall, these results indicate that PMIP can block the expression of a key metastatic mediator, further advancing its potential use as a clinical therapeutic. Mol Cancer Res; 10(12); 1544–54. ©2012 AACR.
Data from The NF-κB Pathway Promotes Tamoxifen Tolerance and Disease Recurrence in Estrogen Receptor–Positive Breast Cancers
Authors: Kastrati Irida , Joosten Stacey E. P. , Semina Svetlana E. , Alejo Luis H. , Brovkovych Svitlana D. , Stender Joshua D. , Horlings Hugo M. , Kok Marleen , Alarid Elaine T. , Greene Geoffrey L. , Linn Sabine C. , Zwart Wilbert , Frasor Jonna
Published: March 2024

Abstract
The purpose of this study was to identify critical pathways promoting survival of tamoxifen-tolerant, estrogen receptor α positive (ER+) breast cancer cells, which contribute to therapy resistance and disease recurrence. Gene expression profiling and pathway analysis were performed in ER+ breast tumors of patients before and after neoadjuvant tamoxifen treatment and demonstrated activation of the NF-κB pathway and an enrichment of epithelial-to mesenchymal transition (EMT)/stemness features. Exposure of ER+ breast cancer cell lines to tamoxifen, in vitro and in vivo, gives rise to a tamoxifen-tolerant population with similar NF-κB activity and EMT/stemness characteristics. Small-molecule inhibitors and CRISPR/Cas9 knockout were used to assess the role of the NF-κB pathway and demonstrated that survival of tamoxifen-tolerant cells requires NF-κB activity. Moreover, this pathway was essential for tumor recurrence following tamoxifen withdrawal. These findings establish that elevated NF-κB activity is observed in breast cancer cell lines under selective pressure with tamoxifen in vitro and in vivo, as well as in patient tumors treated with neoadjuvant tamoxifen therapy. This pathway is essential for survival and regrowth of tamoxifen-tolerant cells, and, as such, NF-κB inhibition offers a promising approach to prevent recurrence of ER+ tumors following tamoxifen exposure.
Implications:
Understanding initial changes that enable survival of tamoxifen-tolerant cells, as mediated by NF-κB pathway, may translate into therapeutic interventions to prevent resistance and relapse, which remain major causes of breast cancer lethality.
Data from The NSD2 p.E1099K Mutation Is Enriched at Relapse and Confers Drug Resistance in a Cell Context–Dependent Manner in Pediatric Acute Lymphoblastic Leukemia
Authors: Pierro Joanna , Saliba Jason , Narang Sonali , Sethia Gunjan , Saint Fleur-Lominy Shella , Chowdhury Ashfiyah , Qualls Anita , Fay Hannah , Kilberg Harrison L. , Moriyama Takaya , Fuller Tori J. , Teachey David T. , Schmiegelow Kjeld , Yang Jun J. , Loh Mignon L. , Brown Patrick A. , Zhang Jinghui , Ma Xiaotu , Tsirigos Aristotelis , Evensen Nikki A. , Carroll William L.
Published: March 2024

Abstract
The NSD2 p.E1099K (EK) mutation is observed in 10% of acute lymphoblastic leukemia (ALL) samples with enrichment at relapse indicating a role in clonal evolution and drug resistance. To discover mechanisms that mediate clonal expansion, we engineered B-precursor ALL (B-ALL) cell lines (Reh, 697) to overexpress wildtype (WT) and EK NSD2, but observed no differences in proliferation, clonal growth, or chemosensitivity. To address whether NSD2 EK acts collaboratively with other pathways, we used short hairpin RNAs to knockdown expression of NSD2 in B-ALL cell lines heterozygous for NSD2 EK (RS4;11, RCH-ACV, SEM). Knockdown resulted in decreased proliferation in all lines, decreased clonal growth in RCH-ACV, and increased sensitivity to cytotoxic chemotherapeutic agents, although the pattern of drug sensitivity varied among cell lines implying that the oncogenic properties of NSD2 mutations are likely cell context specific and rely on cooperative pathways. Knockdown of both Type II and REIIBP EK isoforms had a greater impact than knockdown of Type II alone, suggesting that both SET containing EK isoforms contribute to phenotypic changes driving relapse. Furthermore, in vivo models using both cell lines and patient samples revealed dramatically enhanced proliferation of NSD2 EK compared with WT and reduced sensitivity to 6-mercaptopurine in the relapse sample relative to diagnosis. Finally, EK-mediated changes in chromatin state and transcriptional output differed dramatically among cell lines further supporting a cell context–specific role of NSD2 EK. These results demonstrate a unique role of NSD2 EK in mediating clonal fitness through pleiotropic mechanisms dependent on the genetic and epigenetic landscape.
Implications:
NSD2 EK mutation leads to drug resistance and a clonal advantage in childhood B-ALL.
Data from Differential Tumorigenic Potential and Matriptase Activation between PDGF B versus PDGF D in Prostate Cancer
Authors: Najy Abdo J. , Won Joshua J. , Movilla Lisa S. , Kim Hyeong-Reh C.
Published: March 2024

Abstract
The platelet-derived growth factors (PDGF A, B, C, and D) and their receptors (α-PDGFR and β-PDGFR) play an indispensible role in physiologic and pathologic conditions, including tumorigenesis. The transformative β-PDGFR is overexpressed and activated during prostate cancer progression, but the identification and functional significance of its complementary ligand have not been elucidated. This study examined potential oncogenic functions of β-PDGFR ligands PDGF B and PDGF D, using nonmalignant prostate epithelial cells engineered to overexpress these ligands. In our models, PDGF D induced cell migration and invasion more effectively than PDGF B in vitro. Importantly, PDGF D supported prostate epithelial cell tumorigenesis in vivo and showed increased tumor angiogenesis compared with PDGF B. Autocrine signaling analysis of the mitogen-activated protein kinase and phosphoinositide 3-kinase pathways found PDGF D–specific activation of the c-jun-NH2-kinase (JNK) signaling cascade. Using short hairpin RNA and pharmacologic inhibitors, we showed that PDGFD-mediated phenotypic transformation is β-PDGFR and JNK dependent. Importantly, we made a novel finding of PDGF D–specific increase in the shedding and activation of the serine protease matriptase in prostate epithelial cells. Our study, for the first time to our knowledge, showed ligand-specific β-PDGFR signaling as well as PDGF D–specific regulation of matriptase activity and its spatial distribution through shedding. Taken together with our previous finding that matriptase is a proteolytic activator of PDGF D, this study provides a molecular insight into signal amplification of the proteolytic network and PDGF signaling loop during cancer progression. Mol Cancer Res; 10(8); 1087–97. ©2012 AACR.
Data from Ah Receptor Antagonism Represses Head and Neck Tumor Cell Aggressive Phenotype
Authors: DiNatale Brett C. , Smith Kayla , John Kaarthik , Krishnegowda Gowdahalli , Amin Shantu G. , Perdew Gary H.
Published: March 2024

Abstract
The aryl hydrocarbon receptor (AhR) has been shown to play a role in an increasing number of cellular processes. Recent reports have linked the AhR to cell proliferation, cytoskeletal arrangement, and tumor invasiveness in various tumor cell types. The AhR plays a role in the de-repression of the interleukin (IL)6 promoter in certain tumor cell lines, allowing for increased transcriptional activation by cytokines. Here, we show that there is a significant level of constitutive activation of the AhR in cells isolated from patients with head and neck squamous cell carcinoma (HNSCC). Constitutive activation of the AhR in HNSCCs was blocked by antagonist treatment, leading to a reduction in IL6 expression. In addition, the AhR exhibits a high level of expression in HNSCCs than in normal keratinocytes. These findings led to the hypothesis that the basal AhR activity in HNSCCs plays a role in the aggressive phenotype of these tumors and that antagonist treatment could mitigate this phenotype. This study provides evidence that antagonism of the AhR in HNSCC tumor cells, in the absence of exogenous receptor ligands, has a significant effect on tumor cell phenotype. Treatment of these cell lines with the AhR antagonists 6, 2′, 4′-trimethoxyflavone, or the more potent GNF351, decreased migration and invasion of HNSCC cells and prevented benzo[a]pyrene-mediated induction of the chemotherapy efflux protein ABCG2. Thus, an AhR antagonist treatment has been shown to have therapeutic potential in HNSCCs through a reduction in aggressive cell phenotype. Mol Cancer Res; 10(10); 1369–79. ©2012 AACR.
Data from Long-term Stability of Demethylation after Transient Exposure to 5-Aza-2′-Deoxycytidine Correlates with Sustained RNA Polymerase II Occupancy
Authors: Kagey Jacob D. , Kapoor-Vazirani Priya , McCabe Michael T. , Powell Doris R. , Vertino Paula M.
Published: March 2024

Abstract
DNA methyltransferase inhibitors are currently the standard of care for myelodysplastic syndrome and are in clinical trials for leukemias and solid tumors. However, the molecular basis underlying their activity remains poorly understood. Here, we studied the induction and long-term stability of gene reactivation at three methylated tumor suppressor loci in response to the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (5-azaCdR) in human breast cancer cells. At the TMS1/ASC locus, treatment with 5-azaCdR resulted in partial DNA demethylation, the reengagement of RNA polymerase II (Pol II), and a shift from a repressive chromatin profile marked with H3K9me2 and H4K20me3 to an active profile enriched in H3ac and H3K4me2. Using a single-molecule approach coupling chromatin immunoprecipitation with bisulfite sequencing, we show that H3ac, H3K4me2, and Pol II selectively associated with the demethylated alleles, whereas H3K9me2 preferentially marked alleles resistant to demethylation. H4K20me3 was unaffected by DNA demethylation and associated with both unmethylated and methylated alleles. After drug removal, TMS1 underwent partial remethylation, yet a subset of alleles remained stably demethylated for over 3 months. These alleles remained selectively associated with H3K4me2, H3ac, and Pol II and correlated with a sustained low level of gene expression. TMS1 alleles reacquired H3K9me2 over time, and those alleles that became remethylated retained H3ac. In contrast, CDH1 and ESR1 were remethylated and completely silenced within ∼1 week of drug removal, and failed to maintain stably unmethylated alleles. Our data suggest that the ability to maintain Pol II occupancy is a critical factor in the long-term stability of drug-induced CpG island demethylation. Mol Cancer Res; 8(7); 1048–59. ©2010 AACR.
Data from Loss-of-Function Fibroblast Growth Factor Receptor-2 Mutations in Melanoma
Authors: Gartside Michael G. , Chen Huaibin , Ibrahimi Omar A. , Byron Sara A. , Curtis Amy V. , Wellens Candice L. , Bengston Ana , Yudt Laura M. , Eliseenkova Anna V. , Ma Jinghong , Curtin John A. , Hyder Pilar , Harper Ursula L. , Riedesel Erica , Mann Graham J. , Trent Jeffrey M. , Bastian Boris C. , Meltzer Paul S. , Mohammadi Moosa , Pollock Pamela M.
Published: March 2024

Abstract
We report that 10% of melanoma tumors and cell lines harbor mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. These novel mutations include three truncating mutations and 20 missense mutations occurring at evolutionary conserved residues in FGFR2 as well as among all four FGFRs. The mutation spectrum is characteristic of those induced by UV radiation. Mapping of these mutations onto the known crystal structures of FGFR2 followed by in vitro and in vivo studies show that these mutations result in receptor loss of function through several distinct mechanisms, including loss of ligand binding affinity, impaired receptor dimerization, destabilization of the extracellular domains, and reduced kinase activity. To our knowledge, this is the first demonstration of loss-of-function mutations in a class IV receptor tyrosine kinase in cancer. Taken into account with our recent discovery of activating FGFR2 mutations in endometrial cancer, we suggest that FGFR2 may join the list of genes that play context-dependent opposing roles in cancer. (Mol Cancer Res 2009;7(1):41–54)
Data from Protein Sialylation by Sialyltransferase Involves Radiation Resistance
Authors: Lee Minyoung , Lee Hae-June , Bae Sangwoo , Lee Yun-Sil
Published: March 2024

Abstract
Previously, we identified β-galactoside α(2,6)-sialyltransferase (ST6Gal I) as a candidate biomarker for ionizing radiation. The expression of ST6Gal I and the level of protein sialylation increased following radiation exposure in a dose-dependent manner. Radiation induced ST6Gal I cleavage and the cleaved form of ST6Gal I was soluble and secreted. Sialylation of integrin β1, a glycosylated cell surface protein, was stimulated by radiation exposure and this increased its stability. Overexpression of ST6Gal I in SW480 colon cancer cells that initially showed a low level of ST6Gal I expression increased the sialylation of integrin β1 and also increased the stability of the protein. Inhibition of sialylation by transfection with neuraminidase 2 or neuraminidase 3 or by treatment with short interfering RNA targeting ST6Gal I reversed the effects of ST6Gal I overexpression. In addition, ST6Gal I overexpression increased clonogenic survival following radiation exposure and reduced radiation-induced cell death and caspase 3 activation. However, removal of sialic acids by neuraminidase 2 or knockdown of expression by short interfering RNA targeting ST6Gal I restored radiation-induced cell death phenotypes. In conclusion, radiation exposure was found to increase the sialylation of glycoproteins such as integrin β1 by inducing the expression of ST6Gal I, and increased protein sialylation contributed to cellular radiation resistance. (Mol Cancer Res 2008;6(8):1316–25)
Data from Atypical Protein Kinase C ζ Exhibits a Proapoptotic Function in Ovarian Cancer
Authors: Nazarenko Irina , Jenny Marcel , Keil Jana , Gieseler Cornelia , Weisshaupt Karen , Sehouli Jalid , Legewie Stefan , Herbst Lena , Weichert Wilko , Darb-Esfahani Silvia , Dietel Manfred , Schäfer Reinhold , Ueberall Florian , Sers Christine
Published: March 2024

Abstract
Intracellular signaling governed by serine/threonine kinases comprises the molecular interface between cell surface receptors and the nuclear transcriptional machinery. The protein kinase C (PKC) family members are involved in the control of many signaling processes directing cell proliferation, motility, and survival. Here, we examined a role of different PKC isoenzymes in protein phosphatase 2A (PP2A) and HRSL3 tumor suppressor–dependent cell death induction in the ovarian carcinoma cell line OVCAR-3. Phosphorylation and activity of PKC isoenzymes were measured in response to PP2A or phosphoinositide 3-kinase inhibition or HRSL3 overexpression. These experiments indicated a regulation of PKCθ, ϵ, ζ, and ι through PP2A and/or HRSL3, but not of PKCα and β. Using isoform-specific peptide inhibitors and overexpression approaches, we verified a contribution to PP2A- and HRLS3-dependent apoptosis only for PKCζ, suggesting a proapoptotic function of this kinase. We observed a significant proportion of human ovarian carcinomas expressing high levels of PKCζ, which correlated with poor prognosis. Primary ovarian carcinoma cells isolated from patients also responded to okadaic acid treatment with increased phosphorylation of PKCζ and apoptosis induction. Thus, our data indicate a contribution of PKCζ in survival control in ovarian carcinoma cells and suggest that upregulation or activation of tyrosine kinase receptors in this tumor might impinge onto apoptosis control through the negative regulation of the atypical PKCζ. Mol Cancer Res; 8(6); 919–34. ©2010 AACR.