bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Recapitulation of Pancreatic Neuroendocrine Tumors in Human Multiple Endocrine Neoplasia Type I Syndrome via Pdx1-Directed Inactivation of Men1
Authors: Shen H.-C. Jennifer , He Mei , Powell Anathea , Adem Asha , Lorang Dominique , Heller Charles , Grover Amelia C. , Ylaya Kris , Hewitt Stephen M. , Marx Stephen J. , Spiegel Allen M. , Libutti Steven K.
Published: March 2024

Abstract
Multiple endocrine neoplasia type 1 (MEN1) is an autosomal syndrome caused by mutations in the MEN1 tumor suppressor gene. Whereas the protein product of MEN1, menin, is ubiquitously expressed, somatic loss of the remaining wild-type MEN1 allele results in tumors primarily in parathyroid, pituitary, and endocrine pancreas. To understand the endocrine specificity of the MEN1 syndrome, we evaluated biallelic loss of Men1 by inactivating Men1 in pancreatic progenitor cells using the Cre-lox system. Men1 deletion in progenitor cells that differentiate into exocrine and endocrine pancreas did not affect normal pancreas morphogenesis and development. However, mice having homozygous inactivation of the Men1 in pancreas developed endocrine tumors with no exocrine tumor manifestation, recapitulating phenotypes seen in the MEN1 patients. In the absence of menin, the endocrine pancreas showed increase in cell proliferation, vascularity, and abnormal vascular structures; such changes were lacking in exocrine pancreas. Further analysis revealed that these endocrine manifestations were associated with up-regulation in vascular endothelial growth factor expression in both human and mouse MEN1 pancreatic endocrine tumors. Together, these data suggest the presence of cell-specific factors for menin and a permissive endocrine environment for MEN1 tumorigenesis in endocrine pancreas. Based on our analysis, we propose that menin's ability to maintain cellular and microenvironment integrity might explain the endocrine- restrictive nature of the MEN1 syndrome. [Cancer Res 2009;69(5):1858–66]
Data from Molecular Dosimetry of 1,2,3,4-Diepoxybutane–Induced DNA-DNA Cross-Links in B6C3F1 Mice and F344 Rats Exposed to 1,3-Butadiene by Inhalation
Authors: Goggin Melissa , Swenberg James A. , Walker Vernon E. , Tretyakova Natalia
Published: March 2024

Abstract
1,3-Butadiene (BD) is an important industrial and environmental chemical classified as a human carcinogen based on epidemiologic studies in occupationally exposed workers and animal studies in laboratory rats and mice. BD is metabolically activated to three epoxides that can react with nucleophilic sites in biomolecules. Among these, 1,2,3,4-diepoxybutane (DEB) is considered the ultimate carcinogen due to its high genotoxicity and mutagenicity attributed to its ability to form DNA-DNA cross-links. Our laboratory has developed quantitative high-performance liquid chromatography–μESI+–tandem mass spectrometry methods for two DEB-specific DNA-DNA cross-links, 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) and 1-(guan-7-yl)-4-(aden-1-yl)-2,3-butanediol (N7G-N1A-BD). This report describes molecular dosimetry analysis of these adducts in tissues of B6C3F1 mice and F344 rats exposed to a range of BD concentrations (0–625 ppm). Much higher (4- to 10-fold) levels of DEB-DNA cross-links were observed in mice compared with rats exposed to the same BD concentrations. In both species, bis-N7G-BD levels were 1.5- to 4-fold higher in the liver than in other tissues examined. Interestingly, tissues of female animals exposed to BD contained higher concentrations of bis-N7G-BD adducts than tissues of male animals, which is in accord with previously reported differences in tumor incidence. The molecular dosimetry data presented herein suggest that species and gender differences observed in BD-induced cancer are directly related to differences in the extent of BD metabolism to DEB. Furthermore, a rat model of sensitivity to BD may be more appropriate than a mouse model for assessing human risk associated with BD exposure, because rats and humans seem to be similar with respect to DEB formation. [Cancer Res 2009;69(6):2479–8]
Data from Hyaluronan, CD44, and Emmprin Regulate Lactate Efflux and Membrane Localization of Monocarboxylate Transporters in Human Breast Carcinoma Cells
Authors: Slomiany Mark G. , Grass G. Daniel , Robertson Angela D. , Yang Xiao Y. , Maria Bernard L. , Beeson Craig , Toole Bryan P.
Published: March 2024

Abstract
Interactions of hyaluronan with CD44 in tumor cells play important cooperative roles in various aspects of malignancy and drug resistance. Emmprin (CD147; basigin) is a cell surface glycoprotein of the immunoglobulin superfamily that is highly up-regulated in malignant cancer cells and stimulates hyaluronan production, as well as several downstream signaling pathways. Emmprin also interacts with various monocarboxylate transporters (MCT). Malignant cancer cells use the glycolytic pathway and require MCTs to efflux lactate that results from glycolysis. Glycolysis and lactate secretion contribute to malignant cell behaviors and drug resistance in tumor cells. In the present study, we find that perturbation of endogenous hyaluronan, using small hyaluronan oligosaccharides, rapidly inhibits lactate efflux from breast carcinoma cells; down-regulation of emmprin, using emmprin small interfering RNA, also results in decreased efflux. In addition, we find that CD44 coimmunoprecipitates with MCT1, MCT4, and emmprin and colocalizes with these proteins at the plasma membrane. Moreover, after treatment of the cells with hyaluronan oligosaccharides, CD44, MCT1, and MCT4 become localized intracellularly whereas emmprin remains at the cell membrane. Together, these data indicate that constitutive interactions among hyaluronan, CD44, and emmprin contribute to regulation of MCT localization and function in the plasma membrane of breast carcinoma cells. [Cancer Res 2009;69(4):1293–301]
Data from Aldehyde Dehydrogenase–Expressing Colon Stem Cells Contribute to Tumorigenesis in the Transition from Colitis to Cancer
Authors: Carpentino Joseph E. , Hynes Mark J. , Appelman Henry D. , Zheng Tong , Steindler Dennis A. , Scott Edward W. , Huang Emina H.
Published: March 2024

Abstract
Patients with chronic ulcerative colitis are at increased risk of developing colorectal cancer. Although current hypotheses suggest that sporadic colorectal cancer is due to inability to control cancer stem cells, the cancer stem cell hypothesis has not yet been validated in colitis-associated cancer. Furthermore, the identification of the colitis to cancer transition is challenging. We recently showed that epithelial cells with the increased expression of aldehyde dehydrogenase in sporadic colon cancer correlate closely with tumor-initiating ability. We sought to determine whether ALDH can be used as a marker to isolate tumor-initiating populations from patients with chronic ulcerative colitis. We used fluorescence-activated cell sorting to identify precursor colon cancer stem cells from colitis patients and report both their transition to cancerous stem cells in xenografting studies as well as their ability to generate spheres in vitro. Similar to sporadic colon cancer, these colitis-derived tumors were capable of propagation as sphere cultures. However, unlike the origins of sporadic colon cancer, the primary colitic tissues did not express any histologic evidence of dysplasia. To elucidate a potential mechanism for our findings, we compared the stroma of these different environments and determined that at least one paracrine factor is up-regulated in the inflammatory and malignant stroma compared with resting, normal stroma. These data link colitis and cancer identifying potential tumor-initiating cells from colitic patients, suggesting that sphere and/or xenograft formation will be useful to survey colitic patients at risk of developing cancer. [Cancer Res 2009;69(20):8208–15]
Data from Rat Umbilical Cord Stem Cells Completely Abolish Rat Mammary Carcinomas with No Evidence of Metastasis or Recurrence 100 Days Post–Tumor Cell Inoculation
Authors: Ganta Chanran , Chiyo Doi , Ayuzawa Rie , Rachakatla Rajashekar , Pyle Marla , Andrews Gordon , Weiss Mark , Tamura Masaaki , Troyer Deryl
Published: March 2024

Abstract
Genetically engineered stem cells efficiently deliver therapeutic proteins to cancer and other sites of inflammation. However, a major advantage would be realized if tumor-trafficking stem cells that have not been genetically modified exhibit an inherent antitumor effect, thus circumventing the necessity of the expression of exogenous genes by the cells. We transplanted Fisher 344 rat–derived mammary adenocarcinoma cells (Mat B III) orthotopically into syngeneic F344 rats with an intact immune system. Rat umbilical cord matrix stem (rUCMS) cells derived from Wharton's jelly were then administered intratumoral (i.t) or i.v. 4 days later. The tumor attenuation effect was significantly evident starting from day 14 in i.v. and i.t. rUCMS cell–transplanted rats compared with sham-transplanted rats. In addition, unmodified rUCMS cell–transplanted rats showed complete regression of tumors to undetectable levels by 34 to 38 days with no evidence of metastasis or recurrence 100 days post–tumor cell inoculation. Dye-loaded rUCMS cells were identified within tumors only 4 days after their i.v. transplantation. In vitro colony assays with rUCMS cells as feeder layers markedly reduced Mat B III colony size and number. Growth attenuation of Mat B III cells exposed to either rUCMS cells directly or to the conditioned medium derived from rUCMS cells was associated with apoptosis indicators, including increased activated caspase-3. In addition, rUCMS cells cocultured with Mat B III cells had a dose-dependent antiproliferative effect on Mat B III cells. These findings suggest that unmodified human UCMS cells could be used for targeted cytotherapy for breast cancer. [Cancer Res 2009;69(5):1815–20]
Data from Telomere Dysfunction and DNA-PKcs Deficiency: Characterization and Consequence
Authors: Williams Eli S. , Klingler Rebekah , Ponnaiya Brian , Hardt Tanja , Schrock Evelin , Lees-Miller Susan P. , Meek Katheryn , Ullrich Robert L. , Bailey Susan M.
Published: March 2024

Abstract
The mechanisms by which cells accurately distinguish between DNA double-strand break (DSB) ends and telomeric DNA ends remain poorly defined. Recent investigations have revealed intriguing interactions between DNA repair and telomeres. We were the first to report a requirement for the nonhomologous end-joining (NHEJ) protein DNA-dependent protein kinase (DNA-PK) in the effective end-capping of mammalian telomeres. Here, we report our continued characterization of uncapped (as opposed to shortened) dysfunctional telomeres in cells deficient for the catalytic subunit of DNA-PK (DNA-PKcs) and shed light on their consequence. We present evidence in support of our model that uncapped telomeres in this repair-deficient background are inappropriately detected and processed as DSBs and thus participate not only in spontaneous telomere-telomere fusion but, importantly, also in ionizing radiation–induced telomere-DSB fusion events. We show that phosphorylation of DNA-PKcs itself (Thr-2609 cluster) is a critical event for proper telomere end-processing and that ligase IV (NHEJ) is required for uncapped telomere fusion. We also find uncapped telomeres in cells from the BALB/c mouse, which harbors two single-nucleotide polymorphisms that result in reduced DNA-PKcs abundance and activity, most markedly in mammary tissue, and are both radiosensitive and susceptible to radiogenic mammary cancer. Our results suggest mechanistic links between uncapped/dysfunctional telomeres in DNA-PKcs–deficient backgrounds, radiation-induced instability, and breast cancer. These studies provide the first direct evidence of genetic susceptibility and environmental insult interactions leading to a unique and ongoing form of genomic instability capable of driving carcinogenesis. [Cancer Res 2009;69(5):2100–7]
Data from Relationship of Deregulated Signaling Converging onto mTOR with Prognosis and Classification of Lung Adenocarcinoma Shown by Two Independent In silico Analyses
Authors: Ebi Hiromichi , Tomida Shuta , Takeuchi Toshiyuki , Arima Chinatsu , Sato Takahiko , Mitsudomi Tetsuya , Yatabe Yasushi , Osada Hirotaka , Takahashi Takashi
Published: March 2024

Abstract
There is marked disparity with a slight overlap among prognosis-predictive signatures reported thus far for lung cancers. In this study, we aimed at linking poor prognosis with particular pathways and/or functions of the gene sets involved to better understand the underlying molecular characteristics associated with the prognosis of lung adenocarcinomas. Gene set enrichment analysis identified a gene set down-regulated by rapamycin as the most significant, whereas several others responsive to withdrawal of glucose or amino acids, which are related to signaling converging onto mammalian target of rapamycin (mTOR), were also shown to be significantly associated, in addition to those related to DNA damage response and cell cycle progression. We also used connectivity map (C-MAP) analysis, an independent bioinformatics approach, to search for Food and Drug Administration–approved drugs that potentially transform an unfavorable signature to a favorable one. Those results identified inhibitors of phosphatidylinositol 3-kinase (PI3K) and mTOR, as well as unexpected drugs such as phenothiazine antipsychotics and resveratrol as potential candidates. Experimental validation revealed that the latter unexpected agents also inhibited signaling converging onto mTOR and exhibited antitumor activities. In addition, deregulation of multiple signaling converging onto mTOR was shown to be significantly associated with sensitivity to PI-103, a dual specificity PI3K/mTOR inhibitor that is not contained in the C-MAP database, lending further support for the connection. Our results clearly show the existence of gene set–definable, intrinsic heterogeneities in lung adenocarcinomas, which seem to be related to both clinical behavior and sensitivity to agents affecting the identified pathways. [Cancer Res 2009;69(9):4027–35]
Data from In vivo Molecular Imaging of Cancer with a Quenching Near-Infrared Fluorescent Probe Using Conjugates of Monoclonal Antibodies and Indocyanine Green
Authors: Ogawa Mikako , Kosaka Nobuyuki , Choyke Peter L. , Kobayashi Hisataka
Published: March 2024

Abstract
Near-infrared (NIR) fluorophores have several advantages over visible fluorophores, including improved tissue penetration and lower autofluorescence; however, only indocyanine green (ICG) is clinically approved. Its use in molecular imaging probes is limited because it loses its fluorescence after protein binding. This property can be harnessed to create an activatable NIR probe. After cell binding and internalization, ICG dissociates from the targeting antibody, thus activating fluorescence. ICG was conjugated to the antibodies daclizumab (Dac), trastuzumab (Tra), or panitumumab (Pan). The conjugates had almost no fluorescence in PBS but became fluorescent after SDS and 2-mercaptoethanol, with a quenching capacity of 10-fold for 1:1 conjugates and 40- to 50-fold for 1:5 conjugates. In vitro microscopy showed activation within the endolysosomes in target cells. In vivo imaging in mice showed that CD25-expressing tumors were specifically visualized with Dac-ICG. Furthermore, tumors overexpressing HER1 and HER2 were successfully characterized in vivo by using Pan-ICG(1:5) and Tra-ICG(1:5), respectively. Thus, we have developed an activatable NIR optical probe that “switches on” only in target cells. Because both the antibody and the fluorophore are Food and Drug Administration approved, the likelihood of clinical translation is improved. [Cancer Res 2009;69(4):1268–72]
Data from ADP-Ribosylation Factor 6 Regulates Tumorigenic and Invasive Properties In vivo
Authors: Muralidharan-Chari Vandhana , Hoover Holly , Clancy James , Schweitzer Jill , Suckow Mark A. , Schroeder Valerie , Castellino Francis J. , Schorey Jeffrey S. , D'Souza-Schorey Crislyn
Published: March 2024

Abstract
This study shows that the small GTP-binding protein ADP-ribosylation factor 6 (ARF6) is an important regulator of tumor growth and metastasis. Using spontaneous melanoma tumor growth assays and experimental metastasis assays in nude mice, we show that sustained activation of ARF6 reduces tumor mass growth but significantly enhances the invasive capacity of tumor cells. In contrast, mice injected with tumor cells expressing a dominantly inhibitory ARF6 mutant exhibited a lower incidence and degree of invasion and lung metastasis compared with control animals. Effects on tumor growth correlate with reduced cell proliferation capacity and are linked at least in part to alterations in mitotic progression induced by defective ARF6 cycling. Furthermore, phospho-ERK levels in subcultured cells from ARF6(GTP) and ARF6(GDP) tumor explants correlate with invasive capacity. ARF6-induced extracellular signal-regulated kinase (ERK) signaling leads to Rac1 activation to promote invadopodia formation and cell invasion. These findings document an intricate role for ARF6 and the regulation of ERK activation in orchestrating mechanisms underlying melanoma growth, invasion, and metastases. [Cancer Res 2009;69(6):2201–9]
Data from Distinct Roles of BARD1 Isoforms in Mitosis: Full-Length BARD1 Mediates Aurora B Degradation, Cancer-Associated BARD1β Scaffolds Aurora B and BRCA2
Authors: Ryser Stephan , Dizin Eva , Jefford Charles Edward , Delaval Bénédicte , Gagos Sarantis , Christodoulidou Agni , Krause Karl-Heinz , Birnbaum Daniel , Irminger-Finger Irmgard
Published: March 2024

Abstract
The BRCA1-associated ring domain protein 1 (BARD1) interacts with BRCA1 via its RING finger domain. The BARD1-BRCA1 complex participates in DNA repair, cell cycle control, genomic stability, and mitotic spindle formation through its E3 ubiquitin ligase activity. Cancer cells express several BARD1 protein isoforms, including the RING finger–deficient variant BARD1β. Here, we show that BARD1 has BRCA1-dependent and BRCA1-independent functions in mitosis. BARD1, but not BRCA1, localizes to the midbody at telophase and cytokinesis, where it colocalizes with Aurora B. The 97-kDa full-length (FL) BARD1 coimmunoprecipates with BRCA1, but the 82-kDa BARD1β coimmunoprecipitates with Aurora B and BRCA2. We used selective small interfering RNAs to distinguish the functions of FL BARD1 and BARD1β. Depletion of FL BARD1 had only minor effects on cell growth and did not abolish midbody localization of BARD1 staining, but resulted in massive up-regulation of Aurora B. In contrast, suppression of FL BARD1 and BARD1β led to growth arrest and correlated with various mitotic defects and disappearance of midbody localization of BARD1 staining. Our data suggest a novel function of FL BARD1 in Aurora B ubiquitination and degradation, opposing a proproliferative function of BARD1β in scaffolding Aurora B and BRCA2. Thus, loss of FL BARD1 and up-regulation of Aurora B, as observed in cancer cells, can be explained by an imbalance of FL BARD1 and BARD1β. [Cancer Res 2009;69(3):1125–34]
Data from Lack of Muc1-Regulated β-Catenin Stability Results in Aberrant Expansion of CD11b+Gr1+ Myeloid-Derived Suppressor Cells from the Bone Marrow
Authors: Poh Tze Wei , Bradley Judy M. , Mukherjee Pinku , Gendler Sandra J.
Published: March 2024

Abstract
Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid cells that inhibit T-cell activity and contribute to the immune suppression characteristic of most tumors. We discovered that bone marrow (BM) progenitor cells from the Muc1 knockout (KO) mice differentiated into CD11b+Gr1+ MDSCs in vitro under granulocyte macrophage colony-stimulating factor and interleukin-4 signaling. MUC1 is a tumor-associated mucin and its cytoplasmic tail (MUC1-CT) can regulate β-catenin to promote oncogenesis. Given the importance of β-catenin in hematopoiesis, we hypothesized that the MUC1 regulation of β-catenin is important for MDSC development. Our current study shows that the aberrant development of BM progenitors into CD11b+Gr1+ MDSCs is dependent on the down-regulation of β-catenin levels that occurs in the absence of Muc1. In light of this, KO mice showed enhanced EL4 tumor growth and were able to better tolerate allogeneic BM185 tumor growth, with an accumulation of CD11b+Gr1+ cells in the blood and tumor-draining lymph nodes. WT mice were able to similarly tolerate allogeneic tumor growth when they were injected with CD11b+Gr1+ cells from tumor-bearing KO mice, suggesting that tolerance of allogeneic tumors is dependent on MDSC-mediated immune suppression. This further delineates the ability of Muc1 to control MDSC development, which could directly affect tumorigenesis. Knowledge of the biology by which Muc1 regulates the development of myeloid progenitors into MDSCs would also be very useful in enhancing the efficacy of cancer vaccines in the face of tumor immune suppression. [Cancer Res 2009;69(8):3554–62]
Data from Membrane Microvesicles as Actors in the Establishment of a Favorable Prostatic Tumoral Niche: A Role for Activated Fibroblasts and CX3CL1-CX3CR1 Axis
Authors: Castellana Donatello , Zobairi Fatiha , Martinez Maria Carmen , Panaro Maria Antonietta , Mitolo Vincenzo , Freyssinet Jean-Marie , Kunzelmann Corinne
Published: March 2024

Abstract
Tumor microenvironment is enriched in plasma membrane microvesicles (MV) shed from all cell types that constitute the tumor mass, reflecting the antigenic profile of the cells they originate from. Fibroblasts and tumor cells mutually communicate within tumor microenvironment. Recent evidences suggest that tumor-derived MVs (TMV) exert a broad array of biological functions in cell-to-cell communication. To elucidate their role in cancer-to-fibroblast cell communication, TMV obtained from two prostate carcinoma cell lines with high and weak metastatic potential (PC3 and LnCaP, respectively) have been characterized. TMV exhibit matrix metalloproteinases (MMP) and extracellular MMP inducer at their surface, suggesting a role in extracellular matrix degradation. Moreover, TMV not only induce the activation of fibroblasts assessed through extracellular signal-regulated kinase 1/2 phosphorylation and MMP-9 up-regulation, increase motility and resistance to apoptosis but also promote MV shedding from activated fibroblasts able in turn to increase migration and invasion of highly metastatic PC3 cells but not LnCaP cells. PC3 cell chemotaxis seems, at least partially, dependent on membrane-bound CX3CL1/fractalkine ligand for chemokine receptor CX3CR1. The present results highlight a mechanism of mutual communication attributable not only to soluble factors but also to determinants harbored by MV, possibly contributing to the constitution of a favorable niche for cancer development. [Cancer Res 2009;69(3):785–93]
Data from A Gonadotropin-Releasing Hormone-II Antagonist Induces Autophagy of Prostate Cancer Cells
Authors: Kim Dong-Ki , Yang Ji Sook , Maiti Kaushik , Hwang Jong-Ik , Kim Kyungjin , Seen Dongseung , Ahn Younghee , Lee Cheolju , Kang Byeong-Cheol , Kwon Hyuk Bang , Cheon Jun , Seong Jae Young
Published: March 2024

Abstract
Gonadotropin-releasing hormone-I (GnRH-I) is known to directly regulate prostate cancer cell proliferation. However, the role of GnRH-II in prostate cancer is unclear. Here, we investigated the effect of the GnRH-II antagonist trptorelix-1 (Trp-1) on growth of PC3 prostate cancer cells. Trp-1 induced growth inhibition of PC3 cells in vitro and inhibited growth of PC3 cells xenografted into nude mice. FITC-N3, an FITC-conjugated Trp-1 analogue, was largely present in the mitochondria of prostate cancer cells, but not in other cells that are not derived from the prostate. Trp-1–induced PC3 growth inhibition was associated with decreased mitochondrial membrane potential and increased levels of mitochondrial and cytosolic reactive oxygen species (ROS). Growth inhibition was partially prevented by cotreating cells with N-acetyl cysteine, an antioxidant. Cytochrome c release and caspase-3 activation were not detected in Trp-1–treated cells. However, Trp-1 induced autophagosome formation, as seen by increased LysoTracker staining and recruitment of microtubule-associated protein 1 light chain 3 to these new lysosomal compartments. Trp-1–induced autophagy was accompanied by decreased AKT phosphorylation and increased c-Jun NH2 terminal kinase phosphorylation, two events known to be linked to autophagy. Taken together, these data suggest that Trp-1 directly induces mitochondrial dysfunction and ROS increase, leading to autophagy of prostate cancer cells. GnRH-II antagonists may hold promise in the treatment of prostate cancer. [Cancer Res 2009;69(3):923–31]
Data from High Incidence of Protein-Truncating TP53 Mutations in BRCA1-Related Breast Cancer
Authors: Holstege Henne , Joosse Simon A. , van Oostrom Conny Th. M. , Nederlof Petra M. , de Vries Annemieke , Jonkers Jos
Published: March 2024

Abstract
Approximately half of all hereditary breast cancers are compromised in their DNA repair mechanisms due to loss of BRCA1 or BRCA2 function. Previous research has found a strong correlation between BRCA mutation and TP53 mutation. However, TP53 mutation status is often indirectly assessed by immunohistochemical staining of accumulated p53 protein. We sequenced TP53 exons 2 to 9 in 21 BRCA1-related breast cancers and 37 sporadic breast tumors. Strikingly, all BRCA1-related breast tumors contained TP53 mutations, whereas only half of these tumors stained positive for p53 accumulation. Positive p53 staining correlates with the presence of TP53 hotspot mutations in both BRCA1-related and sporadic breast tumors. However, whereas the majority of sporadic breast tumors that stained negative for p53 accumulation had wild-type TP53, the majority of BRCA1-associated breast tumors that stained negative for p53 accumulation had protein-truncating TP53 mutations (nonsense, frameshift, and splice mutations). Therefore, the strong selection for p53 loss in BRCA1-related tumors is achieved by an increase of protein-truncating TP53 mutations rather than hotspot mutations. Hence, immunohistochemical detection of TP53 mutation could lead to misdiagnosis in approximately half of all BRCA1-related tumors. The presence of deleterious TP53 mutations in most, if not all, BRCA1-related breast cancers suggests that p53 loss of function is essential for BRCA1-associated tumorigenesis. BRCA1-related tumors may therefore be treated not only with drugs that target BRCA1 deficiency [e.g., poly(ADP-ribose) polymerase inhibitors] but also with drugs that selectively target p53-deficient cells. This raises interesting possibilities for combination therapies against BRCA1-deficient breast cancers and BRCA1-like tumors with homologous recombination deficiency. [Cancer Res 2009;69(8):3625–33]
Data from Akt Phosphorylation of Merlin Enhances Its Binding to Phosphatidylinositols and Inhibits the Tumor-Suppressive Activities of Merlin
Authors: Okada Masashi , Wang Yanru , Jang Sung-Wuk , Tang Xiaoling , Neri Luca M. , Ye Keqiang
Published: March 2024

Abstract
The NF2 tumor suppressor gene encodes an intracellular membrane-associated protein, called merlin, which belongs to the band 4.1 family of cytoskeleton-associated proteins that link cell surface glycoproteins to the actin cytoskeleton. Merlin suppresses phosphatidylinositol 3-kinase (PI3K)/Akt signaling by directly binding and inhibiting the stimulatory activity of PIKE-L on PI3K. Akt feeds back and phosphorylates merlin and provokes its polyubiquitination and degradation. Here, we show that Akt phosphorylation and PI(3,4,5)P3 binding mediate the tumor-suppressive activity of merlin. The extreme NH2 terminus of merlin directly interacts with phosphatidylinositols, for which the unfolded conformation is required. Moreover, Akt phosphorylation enhances merlin binding affinity to phosphatidylinositols and inhibits its proapoptotic actions. Furthermore, Akt phosphorylation and phosphatidylinositols increase merlin binding to CD44. Epidermal growth factor treatment and Akt phosphorylation provoke merlin to aggregate in the ruffled plasma membrane and promote cell migration. Thus, these results suggest that PI3K signaling regulates the tumor-suppressive activity of merlin via both Akt phosphorylation and phosphatidylinositol lipids binding to merlin. [Cancer Res 2009;69(9):4043–51]
Data from Presence of the Carcinogen N′-Nitrosonornicotine in the Urine of Some Users of Oral Nicotine Replacement Therapy Products
Authors: Stepanov Irina , Carmella Steven G. , Briggs Anna , Hertsgaard Louise , Lindgren Bruce , Hatsukami Dorothy , Hecht Stephen S.
Published: March 2024

Abstract
N′-nitrosonornicotine (NNN) is a strong carcinogen present in unburned tobacco and cigarette smoke. We here analyze data obtained in two studies, in which a biomarker of exposure to NNN—the sum of NNN and its pyridine-N-glucuronide, called total NNN—was quantified in the urine of people who had stopped smoking and used various nicotine replacement therapy (NRT) products. In 13 of 34 nicotine gum or lozenge users from both studies, total NNN at one or more time points after biochemically confirmed smoking cessation was comparable with, or considerably higher than, the baseline levels. For most of the subjects who used the nicotine patch as a smoking cessation aid, urinary total NNN at all post–quit time points was <37% of their mean baseline levels. These results indicate that endogenous formation of significant amounts of NNN may occur sporadically in some users of oral NRT. Given the carcinogenicity of NNN and the frequent use of nicotine gum as a smoking cessation aid, further studies are needed so that preventive measures can be developed. [Cancer Res 2009;69(21):8236–40]
Data from DNA Cross-Links in Human Tumor Cells Exposed to the Prodrug PR-104A: Relationships to Hypoxia, Bioreductive Metabolism, and Cytotoxicity
Authors: Singleton Rachelle S. , Guise Christopher P. , Ferry Dianne M. , Pullen Susan M. , Dorie Mary J. , Brown J. Martin , Patterson Adam V. , Wilson William R.
Published: March 2024

Abstract
PR-104, currently in clinical trial, is converted systemically to the dinitrobenzamide nitrogen mustard prodrug PR-104A, which is reduced selectively in hypoxic cells to cytotoxic hydroxylamine (PR-104H) and amine (PR-104M) metabolites. Here, we evaluate the roles of this reductive metabolism, and DNA interstrand cross-links (ICL), in the hypoxic and aerobic cytotoxicity of PR-104. Using a panel of 9 human tumor cell lines, cytotoxicity was determined by clonogenic assay after a 2-hour aerobic or hypoxic exposure to PR-104A. PR-104H and PR-104M were determined by high performance liquid chromatography/mass spectrometry, and ICL with the alkaline comet assay. Under hypoxia, the relationship between ICL and cell killing was similar between cell lines. Under aerobic conditions, there was a similar relationship between ICL and cytotoxicity, except in lines with very low rates of aerobic reduction of PR-104A (A2780, C33A, H1299), which showed an ICL-independent mechanism of PR-104A cytotoxicity. Despite this, in xenografts from the same lines, the frequency of PR-104–induced ICL correlated with clonogenic cell killing (r2 = 0.747) with greatest activity in the fast aerobic metabolizers. In addition, changing levels of hypoxia in SiHa tumors modified both ICL frequency and tumor growth delay in parallel. We conclude that both aerobic and hypoxic nitroreduction of PR-104A contribute to the monotherapy antitumor activity of PR-104 in human tumor xenografts, and that ICL are responsible for its antitumor activity and represent a broadly applicable biomarker for tumor cell killing by this novel prodrug. [Cancer Res 2009;69(9):3884–91]
Data from Pivotal Roles of Snail Inhibition and RKIP Induction by the Proteasome Inhibitor NPI-0052 in Tumor Cell Chemoimmunosensitization
Authors: Baritaki Stavroula , Yeung Kam , Palladino Michael , Berenson James , Bonavida Benjamin
Published: March 2024

Abstract
The novel proteasome inhibitor NPI-0052 has been shown to sensitize tumor cells to apoptosis by various chemotherapeutic drugs and tumor necrosis factor–related apoptosis-inducing ligand (TRAIL), although the mechanisms involved are not clear. We hypothesized that NPI-0052–mediated sensitization may result from NF-κB inhibition and downstream modulation of the metastasis inducer Snail and the metastasis suppressor/immunosurveillance cancer gene product Raf-1 kinase inhibitory protein (RKIP). Human prostate cancer cell lines were used as models, as they express different levels of these proteins. We show that NPI-0052 inhibits both NF-κB and Snail and induces RKIP expression, thus resulting in cell sensitization to CDDP and TRAIL. The direct role of NF-κB inhibition in sensitization was corroborated with the NF-κB inhibitor DHMEQ, which mimicked NPI-0052 in sensitization and inhibition of Snail and induction of RKIP. The direct role of Snail inhibition by NPI-0052 in sensitization was shown with Snail small interfering RNA, which reversed resistance and induced RKIP. Likewise, the direct role of RKIP induction in sensitization was revealed by both overexpression of RKIP (mimicking NPI-0052) and RKIP small interfering RNA that inhibited NPI-0052–mediated sensitization. These findings show that NPI-0052 modifies the NF-κB-Snail-RKIP circuitry in tumor cells and results in downstream inhibition of antiapoptotic gene products and chemoimmunosensitization. The findings also identified Snail and RKIP as targets for reversal of resistance. [Cancer Res 2009;69(21):8376–85]
Data from Control of HIF-1α Expression by eIF2α Phosphorylation–Mediated Translational Repression
Authors: Zhu Keyi , Chan WaiKin , Heymach John , Wilkinson Miles , McConkey David J.
Published: March 2024

Abstract
Hypoxia inducible factor 1α (HIF-1α) plays a central role in regulating tumor angiogenesis via its effects on vascular endothelial growth factor (VEGF) transcription, and its expression is regulated through proteasome-mediated degradation. Paradoxically, previous studies have shown that proteasome inhibitors (PI) block tumor angiogensis by reducing VEGF expression, but the mechanisms have not been identified. Here, we report that PIs down-regulated HIF-1α protein levels and blocked HIF-1α transcriptional activity in human prostate cancer cells. PIs induced phosphorylation of the translation initiation factor 2α (eIF2α), which caused general translational repression to inhibit HIF-1α expression. Furthermore, PIs induced HIF-1α accumulation in LNCaP-Pro5 cells depleted of eIF2α via siRNA transfection and in MEFs expressing a phosphorylation-deficient mutant form of eIF2α. Finally, PIs failed to induce eIF2α phosphorylation or translational attenuation in DU145 or 253JB-V cells, and, in these cells, PIs promoted HIF-1α accumulation. Our data established that PIs down-regulated HIF-1α expression in cells that display activation of the unfolded protein response by stimulating phosphorylation of eIF2α and inhibiting HIF-1α translation. [Cancer Res 2009;69(5):1836–43]
Data from Persistence of Betapapillomavirus Infections as a Risk Factor for Actinic Keratoses, Precursor to Cutaneous Squamous Cell Carcinoma
Authors: Plasmeijer Elsemieke I. , Neale Rachel E. , de Koning Maurits N.C. , Quint Wim G.V. , McBride Penelope , Feltkamp Mariet C.W. , Green Adele C.
Published: March 2024

Abstract
Human papillomaviruses from the β genus (βPV) are a possible cause of cutaneous squamous cell carcinoma (SCC). We assessed the extent to which βPV infections persisted long-term in a subtropical Australian community and whether βPV persistence is positively associated with actinic keratoses, precursor for SCC. Eyebrow hairs were collected from 171 participants of the community-based Nambour Skin Cancer Study in 1996 and 2003. Hair samples were tested for the presence of DNA from 25 different βPV types and assessed in relation to actinic keratosis presence in 2007. In 1996, a total of 413 βPV infections were found in 73% of participants, increasing to 490 infections among 85% in 2003. Of the total βPV infections detected, 211 (30%) were found to persist. Age was significantly associated with βPV persistence: those ages >60 years had 1.5-fold (95% confidence interval, 1.1-1.9) increased risk of type-specific viral persistence than those ages <40 years. After accounting for actinic keratoses at baseline, persistence of βPV DNA resulted in a 1.4-fold (95% confidence interval, 1.0-1.9) increase in risk of having actinic keratoses on the face in 2007. In conclusion, persistent βPV infections in this population were associated with an increased occurrence of actinic keratosis. Additional studies are needed to determine the possible association of βPV persistence with SCC. [Cancer Res 2009;69(23):8926–31]
Data from Vasculostatin Inhibits Intracranial Glioma Growth and Negatively Regulates In vivo Angiogenesis through a CD36-Dependent Mechanism
Authors: Kaur Balveen , Cork Sarah M. , Sandberg Eric M. , Devi Narra S. , Zhang Zhaobin , Klenotic Philip A. , Febbraio Maria , Shim Hyunsuk , Mao Hui , Tucker-Burden Carol , Silverstein Roy L. , Brat Daniel J. , Olson Jeffrey J. , Van Meir Erwin G.
Published: March 2024

Abstract
Angiogenesis is a critical physiologic process that is appropriated during tumorigenesis. Little is known about how this process is specifically regulated in the brain. Brain angiogenesis inhibitor-1 (BAI1) is a brain-predominant seven-transmembrane protein that contains five antiangiogenic thrombospondin type-1 repeats (TSR). We recently showed that BAI1 is cleaved at a conserved proteolytic cleavage site releasing a soluble, 120 kDa antiangiogenic factor called vasculostatin (Vstat120). Vstat120 has been shown to inhibit in vitro angiogenesis and suppress subcutaneous tumor growth. Here, we examine its effect on the intracranial growth of malignant gliomas and further study its antitumor mechanism. First, we show that expression of Vstat120 strongly suppresses the intracranial growth of malignant gliomas, even in the presence of the strong proangiogenic stimulus mediated by the oncoprotein epidermal growth factor receptor variant III (EGFRvIII). This tumor-suppressive effect is accompanied by a decrease in tumor vascular density, suggesting a potent antiangiogenic effect in the brain. Second, and consistent with this interpretation, we find that treatment with Vstat120 reduces the migration of cultured microvascular endothelial cells in vitro and inhibits corneal angiogenesis in vivo. Third, we show that these antivascular effects critically depend on the presence of the cell surface receptor CD36 on endothelial cells in vitro and in vivo, supporting the role of Vstat120 TSRs in mediating these effects. These results advance the understanding of brain-specific angiogenic regulation, and suggest that Vstat120 has therapeutic potential in the treatment of brain tumors and other intracerebral vasculopathies. [Cancer Res 2009;69(3):1212–20]
Data from Thyroid Transcription Factor-1 Inhibits Transforming Growth Factor-β–Mediated Epithelial-to-Mesenchymal Transition in Lung Adenocarcinoma Cells
Authors: Saito Roy-Akira , Watabe Tetsuro , Horiguchi Kana , Kohyama Tadashi , Saitoh Masao , Nagase Takahide , Miyazono Kohei
Published: March 2024

Abstract
Thyroid transcription factor-1 (TTF-1) is expressed in lung cancer, but its functional roles remain unexplored. TTF-1 gene amplification has been discovered in a part of lung adenocarcinomas, and its action as a lineage-specific oncogene is highlighted. Epithelial-to-mesenchymal transition (EMT) is a crucial event for cancer cells to acquire invasive and metastatic phenotypes and can be elicited by transforming growth factor-β (TGF-β). Mesenchymal-to-epithelial transition (MET) is the inverse process of EMT; however, signals that induce MET are largely unknown. Here, we report a novel functional aspect of TTF-1 that inhibits TGF-β–mediated EMT and restores epithelial phenotype in lung adenocarcinoma cells. This effect was accompanied by down-regulation of TGF-β target genes, including presumed regulators of EMT, such as Snail and Slug. Moreover, silencing of TTF-1 enhanced TGF-β–mediated EMT. Thus, TTF-1 can exert a tumor-suppressive effect with abrogation of cellular response to TGF-β and attenuated invasive capacity. We further revealed that TTF-1 down-regulates TGF-β2 production in A549 cells and that TGF-β conversely decreases endogenous TTF-1 expression, suggesting that enhancement of autocrine TGF-β signaling accelerates the decrease of TTF-1 expression and vice versa. These findings delineate potential links between TTF-1 and TGF-β signaling in lung cancer progression through regulation of EMT and MET and suggest that modulation of TTF-1 expression can be a novel therapeutic strategy for treatment of lung adenocarcinoma. [Cancer Res 2009;69(7):2783–91]
Data from PIK3CA Mutations in In situ and Invasive Breast Carcinomas
Authors: Miron Alexander , Varadi Maria , Carrasco Daniel , Li Hailun , Luongo Lauren , Kim Hee Jung , Park So Yeon , Cho Eun Yoon , Lewis Gretchen , Kehoe Sarah , Iglehart J. Dirk , Dillon Deborah , Allred D. Craig , Macconaill Laura , Gelman Rebecca , Polyak Kornelia
Published: March 2024

Abstract
The PIK3 signaling pathway has been identified as one of the most important and most frequently mutated pathways in breast cancer. Somatic mutations in the catalytic subunit of PIK3CA have been found in a significant fraction of breast carcinomas, and it has been proposed that mutant PIK3CA plays a role in tumor initiation. However, the majority of primary human tumors analyzed for genetic alterations in PIK3CA have been invasive breast carcinomas and the frequency of PIK3CA mutations in preinvasive lesions has not been explored. To investigate this, we sequenced exons 9 and 20 of PIK3CA in pure ductal carcinoma in situ (DCIS), DCIS adjacent to invasive carcinoma, and invasive ductal breast carcinomas. In a subset of cases, both in situ and invasive areas were analyzed from the same tumor. We found that the frequency of PIK3CA mutations was essentially the same (∼30%) in all three histologic groups. In some cases, in situ and invasive areas of the same tumor were discordant for PIK3CA status, and in two cases in which multiple invasive and adjacent in situ areas within the same tumor were analyzed independently, we detected intratumor heterogeneity for PIK3CA mutations. Our results suggest that mutation of PIK3CA is an early event in breast cancer that is more likely to play a role in breast tumor initiation than in invasive progression, although a potential role for exon 9 mutations in the progression of a subset of DCIS cases cannot be excluded. Cancer Res; 70(14); 5674–8. ©2010 AACR.
Data from In vivo Imaging of Cutaneous T-Cell Lymphoma Migration to the Skin
Authors: Hoeller Christoph , Richardson Stephen K. , Ng Lai Guan , Valero Teresa , Wysocka Maria , Rook Alain H. , Weninger Wolfgang
Published: March 2024

Abstract
Cutaneous T-cell lymphoma (CTCL) is characterized by the accumulation of malignant CD4+ T cells in the skin. Although the expression of adhesion molecules and chemokine receptors on CTCL cells has been studied extensively on ex vivo isolated cells, very little is known about the dynamics and mechanisms of CTCL trafficking in vivo. However, detailed knowledge of the molecular cues mediating CTCL migration may be used to interfere with their homing to the skin. We made use of real-time intravital epifluorescence video and two-photon microscopy to visualize malignant T cells from Sezary syndrome (SS), a leukemic variant of CTCL, in dermal microvessels in mouse ear skin. We found that SS cells rolled along dermal venules in a P-selectin– and E-selectin–dependent manner at ratios similar to CD4+ memory T cells from normal donors. We furthermore show that the chemokine CCL17/TARC, but not CCL27/CTACK, was sufficient to induce the arrest of SS cells in the microvasculature. However, a combination of both chemokines was required to induce extravasation of SS cells. Together, our experiments delineate the molecular adhesion cascade operant in SS cell homing to the skin in vivo. [Cancer Res 2009;69(7):2704–8]
Data from A High Throughput, Whole Cell Screen for Small Molecule Inhibitors of the Mitotic Spindle Checkpoint Identifies OM137, a Novel Aurora Kinase Inhibitor
Authors: DeMoe Joanna H. , Santaguida Stefano , Daum John R. , Musacchio Andrea , Gorbsky Gary J.
Published: March 2024

Abstract
In mitosis, the kinetochores of chromosomes that lack full microtubule attachments and/or mechanical tension activate a signaling pathway called the mitotic spindle checkpoint that blocks progression into anaphase and prevents premature segregation of the chromatids until chromosomes become aligned at the metaphase plate. The spindle checkpoint is responsible for arresting cells in mitosis in response to chemotherapeutic spindle poisons such as paclitaxel or vinblastine. Some cancer cells show a weakened checkpoint signaling system that may contribute to chromosome instability in tumors. Because complete absence of the spindle checkpoint leads to catastrophic cell division, we reasoned that drugs targeting the checkpoint might provide a therapeutic window in which the checkpoint would be eliminated in cancer cells but sufficiently preserved in normal cells. We developed an assay to identify lead compounds that inhibit the spindle checkpoint. Most cells respond to microtubule drugs by activating the spindle checkpoint and arresting in mitosis with a rounded morphology. Our assay depended on the ability of checkpoint inhibitor compounds to drive mitotic exit and cause cells to flatten onto the substrate in the continuous presence of microtubule drugs. In this study, we characterize one of the compounds, OM137, as an inhibitor of Aurora kinases. We find that this compound is growth inhibitory to cultured cells when applied at high concentration and potentiates the growth inhibitory effects of subnanomolar concentrations of paclitaxel. [Cancer Res 2009;69(4):1509–16]
Data from Immune Rejection of Mouse Tumors Expressing Mutated Self
Authors: Duan Fei , Lin Yun , Liu Cailian , Engelhorn Manuel E. , Cohen Adam D. , Curran Michael , Sakaguchi Shimon , Merghoub Taha , Terzulli Stephanie , Wolchok Jedd D. , Houghton Alan N.
Published: March 2024

Abstract
How the immune system recognizes and responds to mutations expressed by cancer cells is a critical issue for cancer immunology. Mutated self-polypeptides are particularly strong tumor-specific rejection antigens for natural tumor immunity, but we know remarkably little about T-cell responses to mutated self during tumor growth in vivo, including levels of response, kinetics, and correlates that predict tumor rejection. To address these questions, a mutated self-antigen, designated tyrosinase-related protein 1 (Tyrp1)-WM, derived from Tyrp1 was expressed in the poorly immunogenic, spontaneously arising B16 melanoma and the immunogenic, chemically induced LiHa fibrosarcoma. Syngeneic mice challenged with LiHa fibrosarcoma cells expressing Tyrp1-WM, but not native Tyrp1, induced specific CD8+ and CD4+ T-cell responses against defined mutated epitopes in tumor-draining lymph nodes and in tumors. Subsequently, specific CD8+ T-cell responses contracted as a minority of tumors progressed. B16 melanomas expressing Tyrp1-WM induced minimal T-cell responses, and no tumor immunity was detected. Treatment with an agonist monoclonal antibody against glucocorticoid-induced tumor necrosis factor receptor family–related gene (GITR) increased the level of CD8+ T cells recognizing a peptide derived from the Tyrp1-WM sequence and the proportion of mice rejecting tumors. These results show that B16 tumors expressing mutations that generate strongly immunogenic epitopes naturally induce T-cell responses, which are insufficient to reject tumors. Immune modulation, such as inducing GITR signaling, is required to enhance CD8+ T-cell responses to specific mutations and to lead to tumor rejection. [Cancer Res 2009;69(8):3545–53]