bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Establishment of Human Colon Cancer Cell Lines from Fresh Tumors versus Xenografts: Comparison of Success Rate and Cell Line Features
Authors: Dangles-Marie Virginie , Pocard Marc , Richon Sophie , Weiswald Louis-Bastien , Assayag Franck , Saulnier Patrick , Judde Jean-Gabriel , Janneau Jean-Louis , Auger Nathalie , Validire Pierre , Dutrillaux Bernard , Praz Françoise , Bellet Dominique , Poupon Marie-France
Published: March 2023

Abstract
Obtaining representative human colon cancer cell lines from fresh tumors is technically difficult. Using 32 tumor fragments from patients with colon cancer, the present study shows that prior xenograft leads to more efficient cell line establishment compared with direct establishment from fresh tumors (P < 0.05). From 26 tumor specimens, we successfully established 20 tumor xenografts in nude mice (77%); among 19 of these xenografts, 9 (47%) led to cell lines, including four from liver metastases. Only 3 of 31 tumor specimens (9.7%) grew immediately in vitro, and all were derived from primary tumors. To compare major phenotypic and genotypic characteristics of human colon cancer cell lines derived from the same tumor fragment using two protocols, the two pairs of cell lines obtained from 2 of 32 tumor fragments were extensively studied. They displayed similar morphology and were able to form compact spheroids. Chemosensitivity to 5-fluorouracil, CPT11, and L-OHP differed between cell lines obtained from patient tumors and those derived from xenografts. Matched cell lines shared a common core of karyotype alterations and distinctive additional chromosomal aberrations. Expression levels of genes selected for their role in oncogenesis evaluated by real-time quantitative PCR were found to be statistically correlated whatever the in vitro culture model used. In conclusion, xenotransplantation in mice of tumor fragments before establishment of cell lines enables generation of more novel human cancer cell lines for investigation of colon cancer cell biology, opening up the opportunity of reproducing the diversity of this disease. [Cancer Res 2007;67(1):398–407]
Data from A Novel BH3 Mimetic Reveals a Mitogen-Activated Protein Kinase–Dependent Mechanism of Melanoma Cell Death Controlled by p53 and Reactive Oxygen Species
Authors: Verhaegen Monique , Bauer Joshua A. , Martín de la Vega Cristina , Wang Guoping , Wolter Keith G. , Brenner J. Chadwick , Nikolovska-Coleska Zaneta , Bengtson Audrey , Nair Rajan , Elder James T. , Van Brocklin Matt , Carey Thomas E. , Bradford Carol R. , Wang Shaomeng , Soengas María S.
Published: March 2023

Abstract
The RAS/BRAF/MEK/ERK mitogen-activated protein kinase (MAPK) pathway is emerging as a key modulator of melanoma initiation and progression. However, a variety of clinical studies indicate that inhibiting the MAPK pathway is insufficient per se to effectively kill melanoma cells. Here, we report on a genetic and pharmacologic approach to identify survival factors responsible for the resistance of melanoma cells to MEK/ERK antagonists. In addition, we describe a new tumor cell–selective means to bypass this resistance in vitro and in vivo. By generating a panel of isogenic cell lines with specific defects in the apoptotic machinery, we found that the ability of melanoma cells to survive in the absence of functional MEK relies on an ERK-independent expression of the antiapoptotic factor Mcl-1 (and to a lesser extent, Bcl-xL and Bcl-2). Using computer-based modeling, we developed a novel Bcl-2 homology domain 3 (BH3) mimetic. This compound, named TW-37, is the first rationally designed small molecule with high affinity for Mcl-1, Bcl-xL, and Bcl-2. Mechanistic analyses of the mode of action of TW-37 showed a synergistic tumor cell killing in the presence of MEK inhibitors. Importantly, TW-37 unveiled an unexpected role of the MAPK pathway in the control of reactive oxygen species (ROS). This function was critical to prevent the activation of proapoptotic functions of p53 in melanoma cells, but surprisingly, it was dispensable for normal melanocytes. Our results suggest that this MAPK-dependent ROS/p53 feedback loop is a point of vulnerability of melanoma cells that can be exploited for rational drug design. (Cancer Res 2006; 66(23): 11348-59)
Data from Hierarchical Organization of Prostate Cancer Cells in Xenograft Tumors: The CD44+α2β1+ Cell Population Is Enriched in Tumor-Initiating Cells
Authors: Patrawala Lubna , Calhoun-Davis Tammy , Schneider-Broussard Robin , Tang Dean G.
Published: March 2023

Abstract
Prostate cancer cells are heterogeneous in their tumorigenicity. For example, the side population cells isolated from LAPC9 xenografts are 100 to 1,000 times more tumorigenic than the corresponding non–side population cells. Highly purified CD44+ prostate cancer cells from several xenografts are also enriched in prostate cancer stem/progenitor cells. Because the CD44+ prostate cancer cell population is still heterogeneous, we wonder whether we could further enrich for tumorigenic prostate cancer cells in this population using other markers. Integrin α2β1 has been proposed to mark a population of normal human prostate stem cells. Therefore, we first asked whether the α2β1+/hi cells in prostate tumors might also represent prostate cancer stem cells. Highly purified (≥98%) α2β1+/hi cells from three human xenograft tumors, Du145, LAPC4, and LAPC9, show higher clonal and clonogenic potential than the α2β1−/lo cells in vitro. However, when injected into the nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse prostate or s.c., the α2β1+/hi prostate cancer cells are no more tumorigenic than the α2β1−/lo cells. Immunofluorescence studies reveal that CD44 and α2β1 identify an overlapping and inclusive population of prostate cancer cells in that ∼70% of α2β1+/hi cells are CD44+ and 20% to 30% of CD44+ cells are distributed in the α2β1−/lo cell population. Subsequently, we sorted out CD44+α2β1+/hi, CD44+α2β1−/lo, CD44−α2β1+/hi, and CD44−α2β1−/lo cells from LAPC9 tumors and carried out tumorigenicity experiments. The results revealed a hierarchy in tumorigenic potential in the order of CD44+α2β1+/hi ≈ CD44+α2β1−/lo > CD44−α2β1+/hi ≫ CD44−α2β1−/lo. These observations together suggest that prostate cancer cells are organized as a hierarchy. [Cancer Res 2007;67(14):6796–805]
Data from Identification of an Aberrantly Spliced Form of HDMX in Human Tumors: A New Mechanism for HDM2 Stabilization
Authors: Giglio Simona , Mancini Francesca , Gentiletti Francesca , Sparaco Giorgia , Felicioni Lara , Barassi Fabio , Martella Carla , Prodosmo Andrea , Iacovelli Stefano , Buttitta Fiamma , Farsetti Antonella , Soddu Silvia , Marchetti Antonio , Sacchi Ada , Pontecorvi Alfredo , Moretti Fabiola
Published: March 2023

Abstract
The HDMX protein is closely related to HDM2 with which it shares different structural domains, particularly the p53 binding domain and the ring finger domain, where the two HDM proteins interact. Several oncogenic forms derived from splicing of HDM2 have been described in cancer. This work aimed at investigating whether analogous forms of HDMX exist in human tumors. Here, we report the characterization of an aberrantly spliced form of HDMX, HDMX211, isolated from the thyroid tumor cell line, ARO. HDMX211 binds and stabilizes the HDM2 protein. Although it lacks the p53 binding domain, HDMX211 also stabilizes p53 by counteracting its degradation by HDM2. However, the resulting p53 is transcriptionally inactive and increasingly associated to its inhibitor HDM2. Expression of HDMX211 strongly enhances the colony-forming ability of human cells in the presence or absence of wild-type p53. Conversely, depletion of HDMX211 by small interfering RNA significantly reduces the growth of ARO cells and increases their sensitivity to chemotherapy. Screening of lung cancer biopsies shows the presence of HDMX211 in samples that overexpress HDM2 protein, supporting a pathologic role for this new protein. This is the first evidence of a variant form of HDMX that has oncogenic potential independently of p53. HDMX211 reveals a new mechanism for overexpression of the oncoprotein HDM2. Most interestingly, it outlines a possible molecular explanation for a yet unclarified tumor phenotype, characterized by simultaneous overexpression of HDM2 and wild-type p53.
Data from Involvement of Disulfide Bond Formation in the Activation of Heparanase
Authors: Simizu Siro , Suzuki Takehiro , Muroi Makoto , Lai Ngit Shin , Takagi Satoshi , Dohmae Naoshi , Osada Hiroyuki
Published: March 2023

Abstract
Heparanase is overexpressed in many solid tumor cells and is capable of specifically cleaving heparan sulfate, and this activity is associated with the metastatic potential of tumor cells; however, the activation mechanism of heparanase has remained unknown. In this study, we investigated the link between disulfide bond formation and the activation of heparanase in human tumor cells. Mass spectrometry analysis of heparanase purified from a conditioned medium of human fibrosarcoma cells revealed two disulfide bonds, Cys127-Cys179 and Cys437-Cys542, and one S-cysteinylation at the Cys211 residue. It was shown that, although the formation of the Cys127-Cys179 bond and S-cysteinylation at Cys211 have little effect on heparanase function, the disulfide bond between Cys437 and Cys542 is necessary for the secretion and activation of heparanase. Thus, the present findings will provide a basis for the further refinement of heparanase structural studies and for the development of novel heparanase inhibitors. [Cancer Res 2007;67(16):7841–9]
Data from Cooperative Interactions between Androgen Receptor (AR) and Heat-Shock Protein 27 Facilitate AR Transcriptional Activity
Authors: Zoubeidi Amina , Zardan Anousheh , Beraldi Eliana , Fazli Ladan , Sowery Richard , Rennie Paul , Nelson Colleen , Gleave Martin
Published: March 2023

Abstract
Androgen receptor (AR) transactivation is known to enhance prostate cancer cell survival. However, the precise effectors by which the prosurvival effects of androgen and AR drive prostate cancer progression are poorly defined. Here, we identify a novel feed-forward loop involving cooperative interactions between ligand-activated AR and heat-shock protein 27 (Hsp27) phospho-activation that enhance AR stability, shuttling, and transcriptional activity, thereby increasing prostate cancer cell survival. Androgen-bound AR induces rapid Hsp27 phosphorylation on Ser78 and Ser82 residues in an AR- and p38 kinase–dependent manner. After this androgen-induced, non-nuclear phospho-activation, Hsp27 displaces Hsp90 from a complex with AR to chaperone AR into the nucleus and interact with its response elements to enhance its genomic activity. Inhibition of Hsp27 phosphorylation, or knockdown using the antisense drug OGX-427, shifted the association of AR with Hsp90 to MDM2, increased proteasome-mediated AR degradation, decreased AR transcriptional activity, and increased prostate cancer LNCaP cell apoptotic rates. OGX-427 treatment of mice bearing LNCaP xenografts transfected with an androgen-regulated, probasin-luciferase reporter construct resulted in decreased bioluminescence and serum PSA levels as pharmacodynamic readouts of AR activity, as well as AR, Hsp27, and Hsp90 protein levels in LNCaP tumor tissue. These data identify novel nongenomic mechanisms involving androgen, AR, and Hsp27 activation that cooperatively interact to regulate the genomic activity of AR and justify further investigation of Hsp27 knockdown as an AR disrupting therapeutic strategy in prostate cancer. [Cancer Res 2007;67(21):10455–65]
Data from Systemic Stromal Effects of Estrogen Promote the Growth of Estrogen Receptor–Negative Cancers
Authors: Gupta Piyush B. , Proia David , Cingoz Oya , Weremowicz Janusz , Naber Stephen P. , Weinberg Robert A. , Kuperwasser Charlotte
Published: March 2023

Abstract
Numerous hormonal factors contribute to the lifetime risk of breast cancer development. These include inherited genetic mutations, age of menarche, age of menopause, and parity. Inexplicably, there is evidence indicating that ovariectomy prevents the formation of both estrogen receptor (ER)–positive and ER-negative breast cancers, suggesting that ER-negative breast cancers are dependent on ovarian hormones for their formation. To examine the mechanism(s) by which this may be occurring, we investigated the hypothesis that steroid hormones promote the outgrowth of ER-negative cancers by influencing host cell types distinct from the mammary epithelial cells. We used a novel xenograft mouse model of parturition-induced breast carcinoma formation, in which the tumors that arise following pregnancy lack the expression of nuclear hormone receptors, thereby recapitulating many clinical cases of this disease. Despite lacking ER expression, the tumors arising following pregnancy in this model require circulating estrogens for their formation. Moreover, increasing the levels of circulating estrogens sufficed to promote the formation and progression of ER-negative cancers, which was accompanied by a systemic increase in host angiogenesis and was attendant with the recruitment of bone marrow–derived stromal cells. Furthermore, bone marrow cells from estrogen-treated mice were sufficient to promote tumor growth. These results reveal a novel mechanism by which estrogens promote the growth of ER-negative cancers. [Cancer Res 2007;67(5):2062–71]
Data from Sanguinarine-Dependent Induction of Apoptosis in Primary Effusion Lymphoma Cells
Authors: Hussain Azhar R. , Al-Jomah Naif A. , Siraj Abdul K. , Manogaran Pulicat , Al-Hussein Khalid , Abubaker Jehad , Platanias Leonidas C. , Al-Kuraya Khawla S. , Uddin Shahab
Published: March 2023

Abstract
Primary effusion lymphoma (PEL) is an incurable, aggressive B-cell malignancy that develops rapid resistance to conventional chemotherapy. In efforts to identify novel approaches to block proliferation of PEL cells, we found that sanguinarine, a natural compound isolated from the root plant Sanguinaria canadendid, inhibits cell proliferation and induces apoptosis in a dose-dependent manner in several PEL cell lines. Our data show that sanguinarine treatment of PEL cells results in up-regulation of death receptor 5 (DR5) expression via generation of reactive oxygen species (ROS) and causes activation of caspase-8 and truncation of Bid (tBid). Subsequently, tBid translocates to the mitochondria causing conformational changes in Bax, leading to loss of mitochondrial membrane potential and release of cytochrome c to the cytosol. Sanguinarine-induced release of cytochrome c results in activation of caspase-9 and caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage, leading to induction of caspase-dependent apoptosis. In addition, we show that pretreatment of PEL cells with carbobenzoxy-Val-Ala-Asp-fluoromethylketone, a universal inhibitor of caspases, abrogates caspase and PARP activation and prevents cell death induced by sanguinarine. Moreover, treatment of PEL cells with sanguinarine down-regulates expression of inhibitor of apoptosis proteins (IAP). Finally, N-acetylcysteine, an inhibitor of ROS, inhibits sanguinarine-induced generation of ROS, up-regulation of DR5, Bax conformational changes, activation of caspase-3, and down-regulation of IAPs. Taken together, our findings suggest that sanguinarine is a potent inducer of apoptosis of PEL cells via up-regulation of DR5 and raise the possibility that this agent may be of value in the development of novel therapeutic approaches for the treatment of PEL. [Cancer Res 2007;67(8):3888–97]
Data from Cks1 Regulates cdk1 Expression: A Novel Role during Mitotic Entry in Breast Cancer Cells
Authors: Westbrook Louise , Manuvakhova Marina , Kern Francis G. , Estes Norman R. , Ramanathan Harish N. , Thottassery Jaideep V.
Published: March 2023

Abstract
Cks1, a small protein whose expression is strongly associated with aggressive breast tumors, is a component of cyclin-cdk complexes, as well as the SCFSkp2 ubiquitin ligase. In these studies, we explored its roles in estrogen receptor–positive breast tumor cells. When exposed to the antiestrogen ICI 182780, these cells accumulate in G1 by reducing the expression of Cks1, and increasing the levels of p130/Rb2, a cdk2 inhibitor and SCFSkp2 target. Heregulin β1 or estradiol abrogate antiestrogen effects by increasing Cks1 expression, down-regulating p130/Rb2 and inducing S phase entry. Depletion of Cks1 in these cells by RNA interference concomitantly decreased Skp2 and up-regulated p130/Rb2 and another SCFSkp2 target, p27Kip1. Remarkably, however, Cks1-depleted cells not only exhibit slowed G1 progression, but also accumulate in G2-M due to blocked mitotic entry. Notably, we show that cdk1 expression, which is crucial for M phase entry, is drastically diminished by Cks1 depletion, and that restoration of cdk1 reduces G2-M accumulation in Cks1-depleted cells. cdk1 reduction in Cks1-depleted cells is a consequence of a marked decrease in its mRNA and not due to alteration in its proteolytic turnover. Both heregulin β1 and estradiol could neither restore cdk1 nor sustain cycling in Cks1-depleted cells, although classical estrogen receptor function remained unaltered. Cks1 depletion also decreased Skp2 in human mammary epithelial cells without altering cell cycle progression. Thus, the indispensability of Cks1 to the breast cancer cell cycle, versus its redundancy in normal cells, suggests that Cks1 abrogation could be an effective interventional strategy in breast cancer. [Cancer Res 2007;67(23):11393–401]
Data from Interaction of the Tumor Metastasis Suppressor Nonmetastatic Protein 23 Homologue H1 and Estrogen Receptor α Alters Estrogen-Responsive Gene Expression
Authors: Curtis Carol D. , Likhite Varsha S. , McLeod Ian X. , Yates John R. , Nardulli Ann M.
Published: March 2023

Abstract
Metastasis of cancer cells from the primary tumor is associated with poor prognosis and decreased overall survival. One protein implicated in inhibiting metastasis is the tumor metastasis suppressor nonmetastatic protein 23 homologue 1 (NM23-H1). NM23-H1 is a multifunctional protein, which, in addition to limiting metastasis, has DNase and histidine protein kinase activities. We have identified new functions for NM23-H1 in influencing estrogen receptor α (ERα)–mediated gene expression. Using a battery of molecular and biochemical techniques, we show that NM23-H1 interacts with ERα and increases the ERα–estrogen response element (ERE) interaction. When NM23-H1 expression is increased in U2 osteosarcoma and MDA-MB-231 breast cancer cells, transcription of a transiently transfected, estrogen-responsive reporter plasmid is decreased. More importantly, when endogenous NM23-H1 expression is knocked down in MCF-7 human breast cancer cells using small interfering RNA, estrogen responsiveness of the progesterone receptor (PR), Bcl-2, cathepsin D, and cyclin D1 genes, but not the pS2 gene, is enhanced. Furthermore, NM23-H1 associates with the region of the PR gene containing the +90 activator protein 1 site, but not with the ERE-containing region of the pS2 gene, indicating that NM23-H1 mediates gene-specific effects by association with endogenous chromatin. Our studies suggest that the capacity of NM23-H1 to limit the expression of estrogen-responsive genes such as cathepsin D and Bcl-2, which are involved in cell migration, apoptosis, and angiogenesis, may help to explain the metastasis-suppressive effects of this protein. The complementary abilities of ERα and NM23-H1 together to influence gene expression, cell migration, and apoptosis could be key factors in helping to determine tumor cell fate. [Cancer Res 2007;67(21):10600–7]
Data from Smad7 Sensitizes Tumor Necrosis Factor–Induced Apoptosis through the Inhibition of Antiapoptotic Gene Expression by Suppressing Activation of the Nuclear Factor-κB Pathway
Authors: Hong Suntaek , Lee Chan , Kim Seong-Jin
Published: March 2023

Abstract
Although tumor necrosis factor (TNF) induces apoptosis and cell death in many tumor cells, some cancer cells are still resistant to the TNF-induced death signal. In this report, we showed that Smad7, an inhibitory Smad of transforming growth factor-β (TGF-β) signaling, can overcome the TNF resistance in human breast and gastric cancer cells. Overexpression of Smad7 induces the degradation of poly(ADP-ribose) polymerase and the activation of caspase cascade. Although c-Jun NH2-terminal kinase (JNK) signaling is involved in TNF-induced cell death, the expression of Smad7 does not synergize the activation of JNK. However, the activation of nuclear factor-κB (NF-κB), the cell survival factor, is markedly decreased in Smad7-stable cells. Furthermore, the expression of antiapoptotic target genes of NF-κB is significantly reduced in accordance with the level of Smad7. In addition, Smad7 mediates the inhibitory activity of TGF-β on TNF-induced NF-κB activation and the synergistic activity of TGF-β on TNF-induced apoptosis. These findings suggest that Smad7 sensitizes the tumor cells to TNF-induced apoptosis through the inhibition of expression of antiapoptotic NF-κB target genes. [Cancer Res 2007;67(19):9577–83]
Data from BCL-2 and Mutant NRAS Interact Physically and Functionally in a Mouse Model of Progressive Myelodysplasia
Authors: Omidvar Nader , Kogan Scott , Beurlet Stephanie , le Pogam Carole , Janin Anne , West Robert , Noguera Maria-Elena , Reboul Murielle , Soulie Annie , Leboeuf Christophe , Setterblad Niclas , Felsher Dean , Lagasse Eric , Mohamedali Azim , Thomas N. Shaun B. , Fenaux Pierre , Fontenay Michaela , Pla Marika , Mufti Ghulam J. , Weissman Irving , Chomienne Christine , Padua Rose Ann
Published: March 2023

Abstract
Myelodysplastic syndromes (MDS) are clonal stem cell hematologic disorders that evolve to acute myeloid leukemia (AML) and thus model multistep leukemogenesis. Activating RAS mutations and overexpression of BCL-2 are prognostic features of MDS/AML transformation. Using NRASD12 and BCL-2, we created two distinct models of MDS and AML, where human (h)BCL-2 is conditionally or constitutively expressed. Our novel transplantable in vivo models show that expression of hBCL-2 in a primitive compartment by mouse mammary tumor virus–long terminal repeat results in a disease resembling human MDS, whereas the myeloid MRP8 promoter induces a disease with characteristics of human AML. Expanded leukemic stem cell (Lin−/Sca-1+/c-Kit+) populations and hBCL-2 in the increased RAS-GTP complex within the expanded Sca-1+ compartment are described in both MDS/AML–like diseases. Furthermore, the oncogenic compartmentalizations provide the proapoptotic versus antiapoptotic mechanisms, by activating extracellular signal-regulated kinase and AKT signaling, in determination of the neoplastic phenotype. When hBCL-2 is switched off with doxycycline in the MDS mice, partial reversal of the phenotype was observed with persistence of bone marrow blasts and tissue infiltration as RAS recruits endogenous mouse (m)BCL-2 to remain active, thus demonstrating the role of the complex in the disease. This represents the first in vivo progression model of MDS/AML dependent on the formation of a BCL-2:RAS-GTP complex. The colocalization of BCL-2 and RAS in the bone marrow of MDS/AML patients offers targeting either oncogene as a therapeutic strategy. [Cancer Res 2007;67(24):11657–67]
Data from Targeting Protein Translation in Human Non–Small Cell Lung Cancer via Combined MEK and Mammalian Target of Rapamycin Suppression
Authors: Legrier Marie-Emmanuelle , Yang Chia-Ping Huang , Yan Han-Guang , Lopez-Barcons Lluis , Keller Steven M. , Pérez-Soler Roman , Horwitz Susan Band , McDaid Hayley M.
Published: March 2023

Abstract
Lung cancer is a genetically heterogeneous disease characterized by the acquisition of somatic mutations in numerous protein kinases, including components of the rat sarcoma viral oncogene homolog (RAS) and AKT signaling cascades. These pathways intersect at various points, rendering this network highly redundant and suggesting that combined mitogen-activated protein/extracellular signal-regulated kinase (MEK) and mammalian target of rapamycin (mTOR) inhibition may be a promising drug combination that can overcome its intrinsic plasticity. The MEK inhibitors, CI-1040 or PD0325901, in combination with the mTOR inhibitor, rapamycin, or its analogue AP23573, exhibited dose-dependent synergism in human lung cancer cell lines that was associated with suppression of proliferation rather than enhancement of cell death. Concurrent suppression of MEK and mTOR inhibited ribosomal biogenesis by 40% within 24 h and was associated with a decreased polysome/monosome ratio that is indicative of reduced protein translation efficiency. Furthermore, the combination of PD0325901 and rapamycin was significantly superior to either drug alone or PD0325901 at the maximum tolerated dose in nude mice bearing human lung tumor xenografts or heterotransplants. Except for a PTEN mutant, all tumor models had sustained tumor regressions and minimal toxicity. These data (a) provide evidence that both pathways converge on factors that regulate translation initiation and (b) support therapeutic strategies in lung cancer that simultaneously suppress the RAS and AKT signaling network. [Cancer Res 2007;67(23):11300–8]
Data from Targeted Knockout of BRG1 Potentiates Lung Cancer Development
Authors: Glaros Selina , Cirrincione Georgina M. , Palanca Ariel , Metzger Daniel , Reisman David
Published: March 2023

Abstract
Brahma-related gene 1 (BRG1) is a catalytic subunit of the switch in mating type/sucrose nonfermentation complex and plays an important role in cancer development. Mouse homozygous knockout experiments testing the role of BRG1 in tumorigenesis have been hampered because BRG1 inactivation is embryonic lethal. To bypass this constraint, we developed a lung-specific conditional knockout of BRG1 and examined the effect of BRG1 inactivation in an ethyl carbamate lung carcinogenesis mouse model. We found that the heterozygous loss of BRG1 resulted in increases in both the number and size of tumors when compared with controls. In contrast, when both BRG1 alleles were inactivated, neither the number nor the size of tumors increased compared with controls. In mouse lung tissue where BRG1 was homozygously inactivated, immunostaining for apoptotic markers showed significant increase in Apo-BrdUrd and cleaved caspase-3. These data indicate that a loss of cell viability underlies why biallelic inactivation of BRG1 does not increase tumorigenesis. We also examined mice when exposed to the carcinogen ethyl carbamate and then subjected to BRG1 inactivation. In these cells, loss of BRG1 after carcinogen exposure potentiated tumor development. A subset of tumors retained BRG1 expression, whereas others showed either partial or complete loss of BRG1 expression. Tumors completely devoid of BRG1 expression were significantly larger and expressed higher levels of two markers of proliferation, proliferating cell nuclear antigen and Ki67. Although biallelic inactivation of BRG1 could not initiate tumor development in untransformed cells, our results indicate that transformation and tumor progression are greatly affected by loss of BRG1. [Cancer Res 2008;68(10):3689–96]
Data from Dietary Feeding of Silibinin Inhibits Prostate Tumor Growth and Progression in Transgenic Adenocarcinoma of the Mouse Prostate Model
Authors: Raina Komal , Blouin Marie-José , Singh Rana P. , Majeed Noreen , Deep Gagan , Varghese Leyon , Glodé L. Michael , Greenberg Norman M. , Hwang David , Cohen Pinchas , Pollak Michael N. , Agarwal Rajesh
Published: March 2023

Abstract
Herein, for the first time, we evaluated the chemopreventive efficacy of dietary silibinin against prostate cancer (PCa) growth and progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice from two different genetic backgrounds [C57BL/6 (TRAMP) × FVB; C57BL/6 (TRAMP) × C57BL/6]. At 4 weeks of age, mice were fed control or 0.1% to 1% silibinin–supplemented diets until 23 to 24 weeks of age. Silibinin-fed groups had a lower tumor grade and higher incidence of prostatic intraepithelial neoplasia (PIN) at the expense of a strong decrease in adenocarcinoma incidence. Prostate tissue showed a 47% (P < 0.001) decrease in proliferating cell nuclear antigen (PCNA)–positive cells and an ∼7-fold (P < 0.001) increase in apoptotic cells at the highest silibinin dose. As potential mechanisms of silibinin efficacy, an ∼50% (P < 0.05) decrease in insulin-like growth factor (IGF) receptor type Iβ and an ∼13-fold (P < 0.001) increase in IGF-binding protein 3 (IGFBP-3) protein levels were also observed. These changes were specific to tumors as they were not reflected in circulating IGF-IGFBP-3 system. Additionally, silibinin decreased protein expression of cyclin-dependent kinases (Cdk) by more than 90% (P < 0.001) with a concomitant increase in Cdk inhibitors, Cip1/p21 and Kip1/p27 (P < 0.05, for both). A dose-dependent decrease was also observed in cyclin B1, cyclin E, and cyclin A protein levels by silibinin. Together, these findings suggest that oral silibinin blocks PCa growth and progression at PIN stage in TRAMP mice via modulation of tumor IGF-IGFBP-3 axis and cell cycle regulation, and therefore it has practical and translational potential in suppressing growth and neoplastic conversion of PIN to PCa in humans. [Cancer Res 2007;67(22):11083–91]
Data from The Role of S100P in the Invasion of Pancreatic Cancer Cells Is Mediated through Cytoskeletal Changes and Regulation of Cathepsin D
Authors: Whiteman Hannah J. , Weeks Mark E. , Dowen Sally E. , Barry Sayka , Timms John F. , Lemoine Nicholas R. , Crnogorac-Jurcevic Tatjana
Published: March 2023

Abstract
Up-regulation of S100P, a member of the S100 calcium-binding protein family, is an early molecular event in the development of pancreatic cancer and it is expressed at high levels in both precursor lesions and invasive cancer. To gain more insight into the molecular mechanisms underlying the functional roles of this protein, we stably overexpressed S100P in the Panc1 pancreatic cancer cell line and identified the consequent changes in global protein expression by two-dimensional difference in-gel electrophoresis. The observed changes in target proteins were confirmed by Western blot analysis and immunofluorescence, whereas their functional effect was investigated using motility and invasion assays. In this study, we have shown that overexpression of S100P led to changes in the expression levels of several cytoskeletal proteins, including cytokeratins 8, 18, and 19. We have also shown disorganization of the actin cytoskeleton network and changes in the phosphorylation status of the actin regulatory protein cofilin. Additionally, we have shown that overexpression of S100P leads to increased expression of another early pancreatic cancer marker, S100A6, as well as the aspartic protease cathepsin D, both of which are involved in cellular invasion. Functional studies showed that the increased invasive potential of S100P-overexpressing cells was at least partially due to the increase in cathepsin D expression. In summary, our data suggest that these changes could contribute to the metastatic spread of pancreatic cancer and may explain the devastating prognosis of this disease. [Cancer Res 2007;67(18):8633–42]
Data from MCF7 Side Population Cells with Characteristics of Cancer Stem/Progenitor Cells Express the Tumor Antigen MUC1
Authors: Engelmann Katja , Shen Hongmei , Finn Olivera J.
Published: March 2023

Abstract
Chemotherapy, radiation, and growth inhibitory drugs preferentially eliminate actively growing cancer cells. Cancer recurrence is currently thought to be due to nondividing cancer stem/progenitor cells that are resistant to these therapies. Different therapeutic approaches need to be considered for the elimination of the cancer stem cell population. Immunotherapy is one such approach. In addition to specificity and lack of toxicity, immunotherapy targets cancer cells irrespective of their state of proliferation, as long as they express particular tumor antigens. For that reason, it is important to examine if the tumor antigens that are currently being tested as immunotherapeutic agents are also present on cancer stem cells. This study aimed to determine if one well-known tumor antigen, MUC1, which is being tested as an immunotherapy target on tumor cells, is also expressed on the quiescent cancer stem/progenitor cells. We used the so-called side population (SP) cells found in the MCF7 breast cancer cell line, which we first confirmed by cell surface markers and gene profiling to be highly enriched in cells that fulfill specific functional, phenotypic, and molecular criteria for being tumor stem/progenitor cells. We show that these cells express MUC1 and give rise to MUC1+ tumors in vivo, which maintain the MUC1+ SP population. MUC1 on SP cells is hypoglycosylated and heavily sialylated; the characteristics of the tumor-specific form were expressed on mature cancer cells and recognized by tumor-specific T cells and antibodies. This suggests that stem/progenitor cells, like mature tumor cells, would be targets of MUC1-directed immunotherapy. [Cancer Res 2008;68(7):2419–26]
Data from Constitutive Activation of Signal Transducers and Activators of Transcription Predicts Vorinostat Resistance in Cutaneous T-Cell Lymphoma
Authors: Fantin Valeria R. , Loboda Andrey , Paweletz Cloud P. , Hendrickson Ronald C. , Pierce Jacqueline W. , Roth Jennifer A. , Li Lixia , Gooden Frank , Korenchuk Susan , Hou Xiaoli S. , Harrington Elizabeth A. , Randolph Sophia , Reilly John F. , Ware Christopher M. , Kadin Marshall E. , Frankel Stanley R. , Richon Victoria M.
Published: March 2023

Abstract
Vorinostat is a histone deacetylase inhibitor that induces differentiation, growth arrest, and/or apoptosis of malignant cells both in vitro and in vivo and has shown clinical responses in ∼30% of patients with advanced mycosis fungoides and Sézary syndrome cutaneous T-cell lymphoma (CTCL). The purpose of this study was to identify biomarkers predictive of vorinostat response in CTCL using preclinical model systems and to assess these biomarkers in clinical samples. The signal transducer and activator of transcription (STAT) signaling pathway was evaluated. The data indicate that persistent activation of STAT1, STAT3, and STAT5 correlate with resistance to vorinostat in lymphoma cell lines. Simultaneous treatment with a pan-Janus-activated kinase inhibitor resulted in synergistic antiproliferative effect and down-regulation of the expression of several antiapoptotic genes. Immunohistochemical analysis of STAT1 and phosphorylated tyrosine STAT3 (pSTAT3) in skin biopsies obtained from CTCL patients enrolled in the vorinostat phase IIb trial showed that nuclear accumulation of STAT1 and high levels of nuclear pSTAT3 in malignant T cells correlate with a lack of clinical response. These results suggest that deregulation of STAT activity plays a role in vorinostat resistance in CTCL, and strategies that block this pathway may improve vorinostat response. Furthermore, these findings may be of prognostic value in predicting the response of CTCL patients to vorinostat. [Cancer Res 2008;68(10):3785–94]
Data from Androgen Induction of the Androgen Receptor Coactivator Four and a Half LIM Domain Protein-2: Evidence for a Role for Serum Response Factor in Prostate Cancer
Authors: Heemers Hannelore V. , Regan Kevin M. , Dehm Scott M. , Tindall Donald J.
Published: March 2023

Abstract
Androgen receptor (AR) activity is critical for prostate cancer progression. Overexpression of several AR-associated coactivators has been shown to be essential for AR activation during disease progression. The stimuli and signaling pathways leading to overexpression of these coregulators, however, remain largely elusive. Here, we investigated whether androgen signaling, which demarcates critical transitions during prostate cancer disease progression, can affect coregulator expression. We found that expression of four and a half LIM domain protein-2 (FHL2), a key AR coactivator that is overexpressed in prostate cancer and associates with a poor prognosis, is induced strongly by androgens. Androgen induction of this coactivator established a feed-forward mechanism that robustly activated the AR. Stimulation of FHL2 after androgen exposure was time- and dose-dependent and relied on the presence of a functional AR. Androgen induction of FHL2 depended on active transcription of the FHL2 gene, mediated by action of serum response factor (SRF) on its proximal promoter. Loss of SRF, a transcription factor that preferentially regulates the expression of genes involved in mitogenic response and cytoskeletal organization, hampered prostate cancer cell proliferation. These results suggest a novel indirect mechanism of androgen action on FHL2 expression and provide evidence that SRF is an important determinant of AR action in prostate cancer cells. [Cancer Res 2007;67(21):10592–9]
Data from Characterization of TMPRSS2:ETV5 and SLC45A3:ETV5 Gene Fusions in Prostate Cancer
Authors: Helgeson Beth E. , Tomlins Scott A. , Shah Nameeta , Laxman Bharathi , Cao Qi , Prensner John R. , Cao Xuhong , Singla Nirmish , Montie James E. , Varambally Sooryanarayana , Mehra Rohit , Chinnaiyan Arul M.
Published: March 2023

Abstract
Recurrent gene fusions involving oncogenic ETS transcription factors (including ERG, ETV1, and ETV4) have been identified in a large fraction of prostate cancers. The most common fusions contain the 5′ untranslated region of TMPRSS2 fused to ERG. Recently, we identified additional 5′ partners in ETV1 fusions, including TMPRSS2, SLC45A3, HERV-K_22q11.23, C15ORF21, and HNRPA2B1. Here, we identify ETV5 as the fourth ETS family member involved in recurrent gene rearrangements in prostate cancer. Characterization of two cases with ETV5 outlier expression by RNA ligase–mediated rapid amplification of cDNA ends identified one case with a TMPRSS2:ETV5 fusion and one case with a SLC45A3:ETV5 fusion. We confirmed the presence of these fusions by quantitative PCR and fluorescence in situ hybridization. In vitro recapitulation of ETV5 overexpression induced invasion in RWPE cells, a benign immortalized prostatic epithelial cell line. Expression profiling and an integrative molecular concepts analysis of RWPE-ETV5 cells also revealed the induction of an invasive transcriptional program, consistent with ERG and ETV1 overexpression in RWPE cells, emphasizing the functional redundancy of ETS rearrangements. Together, our results suggest that the family of 5′ partners previously identified in ETV1 gene fusions can fuse with other ETS family members, suggesting numerous rare gene fusion permutations in prostate cancer. [Cancer Res 2008;68(1):73–80]
Data from Nm23-H1 Suppresses Metastasis by Inhibiting Expression of the Lysophosphatidic Acid Receptor EDG2
Authors: Horak Christine E. , Mendoza Arnulfo , Vega-Valle Eleazar , Albaugh Mary , Graff-Cherry Cari , McDermott William G. , Hua Emily , Merino Maria J. , Steinberg Seth M. , Khanna Chand , Steeg Patricia S.
Published: March 2023

Abstract
Nm23-H1 transcriptionally down-regulates expression of the lysophosphatidic acid receptor EDG2 and this down-regulation is critical for Nm23-H1–mediated motility suppression in vitro. We investigated the effect of altered EDG2 expression on Nm23-H1–mediated metastasis suppression in vivo. Clonal MDA-MB-435–derived tumor cell lines transfected with Nm23-H1 together with either a vector control or EDG2 had similar anchorage-dependent and anchorage-independent growth rates in vitro. However, a 45- and 300-fold inhibition of motility and invasion (P < 0.0001), respectively, was observed in Nm23-H1/vector lines, whereas coexpression of EDG2 restored activity to levels observed in the parental line. Using fluorescently labeled cells and ex vivo microscopy, the capacity of these cells to adhere, arrest, extravasate, and survive in the murine lung over a 24-h time course was measured. Only 5% of Nm23-H1/vector–transfected cells were retained in the murine lung 6 h following tail vein injection; coexpression of EDG2 enhanced retention 8- to 13-fold (P < 0.01). In a spontaneous metastasis assay, the primary tumor size of Nm23-H1/vector and Nm23-H1/EDG2 clones was not significantly different. However, restoration of EDG2 expression augmented the incidence of pulmonary metastasis from 51.9% to 90.4% (P = 2.4 × 10−5), comparable with parental MDA-MB-435 cells. To determine the relevance of this model system to human breast cancer, a cohort of breast carcinomas was stained for Nm23-H1 and EDG2 and a statistically significant inverse correlation between these two proteins was revealed (r = −0.73; P = 0.004). The data indicate that Nm23-H1 down-regulation of EDG2 is functionally important to suppression of tumor metastasis. [Cancer Res 2007;67(24):11751–9]
Data from Inhibitors of Ubiquitin-Activating Enzyme (E1), a New Class of Potential Cancer Therapeutics
Authors: Yang Yili , Kitagaki Jirouta , Dai Ren-Ming , Tsai Yien Che , Lorick Kevin L. , Ludwig Robert L. , Pierre Shervon A. , Jensen Jane P. , Davydov Ilia V. , Oberoi Pankaj , Li Chou-Chi H. , Kenten John H. , Beutler John A. , Vousden Karen H. , Weissman Allan M.
Published: March 2023

Abstract
The conjugation of proteins with ubiquitin plays numerous regulatory roles through both proteasomal-dependent and nonproteasomal-dependent functions. Alterations in ubiquitylation are observed in a wide range of pathologic conditions, including numerous malignancies. For this reason, there is great interest in targeting the ubiquitin-proteasome system in cancer. Several classes of proteasome inhibitors, which block degradation of ubiquitylated proteins, are widely used in research, and one, Bortezomib, is now in clinical use. Despite the well-defined and central role of the ubiquitin-activating enzyme (E1), no cell permeable inhibitors of E1 have been identified. Such inhibitors should, in principle, block all functions of ubiquitylation. We now report 4[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoic acid ethyl ester (PYR-41) as the first such inhibitor. Unexpectedly, in addition to blocking ubiquitylation, PYR-41 increased total sumoylation in cells. The molecular basis for this is unknown; however, increased sumoylation was also observed in cells harboring temperature-sensitive E1. Functionally, PYR-41 attenuates cytokine-mediated nuclear factor-κB activation. This correlates with inhibition of nonproteasomal (Lys-63) ubiquitylation of TRAF6, which is essential to IκB kinase activation. PYR-41 also prevents the downstream ubiquitylation and proteasomal degradation of IκBα. Furthermore, PYR-41 inhibits degradation of p53 and activates the transcriptional activity of this tumor suppressor. Consistent with this, it differentially kills transformed p53-expressing cells. Thus, PYR-41 and related pyrazones provide proof of principle for the capacity to differentially kill transformed cells, suggesting the potential for E1 inhibitors as therapeutics in cancer. These inhibitors can also be valuable tools for studying ubiquitylation. [Cancer Res 2007;67(19):9472–81]
Data from Protein Phosphatase 2A and Rapamycin Regulate the Nuclear Localization and Activity of the Transcription Factor GLI3
Authors: Krauß Sybille , Foerster John , Schneider Rainer , Schweiger Susann
Published: March 2023

Abstract
Gain-of-function alterations to the sonic hedgehog (SHH) signaling cascade have been found in a wide range of tumors. Three SHH effectors, GLI1, GLI2, and GLI3, regulate transcription of diverse genes involved in cell growth and cell proliferation. Here, we show that protein phosphatase 2A (PP2A), its regulatory subunit, α4, and rapamycin, an inhibitor of the mammalian target of rapamycin kinase complex 1 (mTORC1), regulate the nuclear localization and transcriptional activity of GLI3. An increase in PP2A activity or treatment with rapamycin leads to cytosolic retention of GLI3 and, consequently, reduced transcription of the GLI3 target gene and cell cycle regulator, cyclin D1. Conversely, inhibition of PP2A results in increased expression of cyclin D1. In summary, our findings reveal the existence of a hitherto unrecognized molecular cross-talk between the oncogenic SHH pathway and the tumor suppressor PP2A and suggest a novel mechanism underlying the anticancerogenic effects of rapamycin. [Cancer Res 2008;68(12):4658–65]
Data from Association of CYP1B1 Germ Line Mutations with Hepatocyte Nuclear Factor 1α–Mutated Hepatocellular Adenoma
Authors: Jeannot Emmanuelle , Poussin Karine , Chiche Laurence , Bacq Yannick , Sturm Nathalie , Scoazec Jean-Yves , Buffet Catherine , Nhieu Jeanne Tran Van , Bellanné-Chantelot Christine , de Toma Claudia , Laurent-Puig Pierre , Bioulac-Sage Paulette , Zucman-Rossi Jessica
Published: March 2023

Abstract
Biallelic somatic mutations of TCF1 coding for hepatocyte nuclear factor 1α (HNF1α) are found in 50% of the hepatocellular adenoma (HCA) cases usually associated with oral contraception. In rare cases, HNF1α germ line mutations could also predispose to familial adenomatosis. In order to identify new genetic factors predisposing to HNF1α-mutated HCA, we searched for mutations in genes involved in the metabolism of estrogen. For 10 genes (CYP1A1, CYP1A2, CYP3A4, CYP3A5, COMT, UGT2B7, NQO1, GSTM1, GSTP1, and GSTT1), we did not find mutations nor differences in the allele distribution among 32 women presenting HNF1α-mutated adenomas compared with 58 controls. In contrast, we identified a CYP1B1 germ line heterozygous mutation in 4 of 32 women presenting HNF1α-mutated adenomas compared with none in 58 controls. We confirmed these results with the identification of four additional CYP1B1 mutations in a second series of 26 cases. No mutations were found in the control group, which was extended to 98 individuals, and only a known rare genetic variant was observed in two controls (P = 0.0003). We did an ethoxyresorufin O-deethylase assay to evaluate the functional consequence of the CYP1B1 mutations. We found reduced enzymatic activity in each CYP1B1 variant. In addition, an E229K CYP1B1 mutation was found in a woman with a germ line HNF1α mutation in a familial adenomatosis context. In this large family, all three patients with adenomatosis bore both HNF1 and CYP1B1 germ line mutations. In conclusion, our data suggested that CYP1B1 germ line–inactivating mutations might increase the incidence of HCA in women with HNF1α mutations. [Cancer Res 2007;67(6):2611–6]
Data from MicroRNAs as Potential Agents to Alter Resistance to Cytotoxic Anticancer Therapy
Authors: Weidhaas Joanne B. , Babar Imran , Nallur Sunitha M. , Trang Phong , Roush Sarah , Boehm Michelle , Gillespie Erin , Slack Frank J.
Published: March 2023

Abstract
Tumor cells use preexisting prosurvival signaling pathways to evade the damaging and cytotoxic effects of anticancer agents. Radiation therapy is a primary form of cytotoxic anticancer treatment, but agents that successfully modify the radiation response in vivo are lacking. MicroRNAs (miRNA) are global gene regulators that play critical roles in oncogenesis and have been found to regulate prosurvival pathways. However, there is little understanding of how cellular miRNA expression affects the response of a cancer to cytotoxic therapy and ultimately outcome. The let-7 family of miRNAs regulates expression of oncogenes, such as RAS, and is specifically down-regulated in many cancer subtypes. In fact, low levels of let-7 predict a poor outcome in lung cancer. Here, we report that the let-7 family of miRNAs is overrepresented in a class of miRNAs exhibiting altered expression in response to radiation. More strikingly, we also can create a radiosensitive state when the select let-7 family of miRNAs is overexpressed in vitro in lung cancer cells and in vivo in a Caenorhabditis elegans model of radiation-induced cell death, whereas decreasing their levels causes radioresistance. In C. elegans, we show that this is partly through control of the proto-oncogene homologue let-60/RAS and genes in the DNA damage response pathway. These findings are the first direct evidence that miRNAs can suppress resistance to anticancer cytotoxic therapy, a common feature of cancer cells, and suggest that miRNAs may be a viable tool to augment current cancer therapies. [Cancer Res 2007;67(23):11111–6]