bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Overexpression of Eg5 Causes Genomic Instability and Tumor Formation in Mice
Authors: Castillo Andrew , Morse Herbert C. , Godfrey Virginia L. , Naeem Rizwan , Justice Monica J.
Published: March 2024

Abstract
Proper chromosome segregation in eukaryotes is driven by a complex superstructure called the mitotic spindle. Assembly, maintenance, and function of the spindle depend on centrosome migration, organization of microtubule arrays, and force generation by microtubule motors. Spindle pole migration and elongation are controlled by the unique balance of forces generated by antagonistic molecular motors that act upon microtubules of the mitotic spindle. Defects in components of this complex structure have been shown to lead to chromosome missegregation and genomic instability. Here, we show that overexpression of Eg5, a member of the Bim-C class of kinesin-related proteins, leads to disruption of normal spindle development, as we observe both monopolar and multipolar spindles in Eg5 transgenic mice. Our findings show that perturbation of the mitotic spindle leads to chromosomal missegregation and the accumulation of tetraploid cells. Aging of these mice revealed a higher incidence of tumor formation with a mixed array of tumor types appearing in mice ages 3 to 30 months with the mean age of 20 months. Analysis of the tumors revealed widespread aneuploidy and genetic instability, both hallmarks of nearly all solid tumors. Together with previous findings, our results indicate that Eg5 overexpression disrupts the unique balance of forces associated with normal spindle assembly and function, and thereby leads to the development of spindle defects, genetic instability, and tumors. [Cancer Res 2007;67(21):1–10] [Cancer Res 2007;67(21):10138–47]
Data from Mechanism of All-Trans Retinoic Acid Effect on Tumor-Associated Myeloid-Derived Suppressor Cells
Authors: Nefedova Yulia , Fishman Mayer , Sherman Simon , Wang Xingyu , Beg Amer A. , Gabrilovich Dmitry I.
Published: March 2024

Abstract
Myeloid-derived suppressor cells (MDSC) play an important role in tumor escape by suppressing T-cell responses. MDSC represent a group of cells of myeloid lineage at different stages of differentiation. Increased arginase activity and production of reactive oxygen species (ROS) are among the main functional characteristics of these cells. Recent studies have shown that all-trans retinoic acid (ATRA) had a potent activity in eliminating MDSC in cancer patients and in tumor-bearing mice. ATRA differentiates these cells into mature myeloid cells. However, the mechanism of this effect is unclear. Here, we have shown that ATRA dramatically and specifically up-regulated gene expression and protein level of glutathione synthase (GSS) in MDSC. This resulted in accumulation of glutathione (GSH) in these cells, observed in both mice and cancer patients. Blockade of GSH synthesis cancelled the effect of ATRA on MDSC. Accumulation of GSH in these cells using N-acetyl-l-cysteine mimicked the effect of ATRA on MDSC differentiation. Analysis of potential mechanisms of ATRA effect on GSS revealed that ATRA regulates its expression not by directly binding to the promoter but primarily via activation of extracellular signal–regulated kinase 1/2. Thus, ATRA induced differentiation of MDSC primarily via neutralization of high ROS production in these cells. This novel mechanism involves specific up-regulation of GSS and accumulation of GSH and could be used in developing and monitoring therapeutic application of ATRA. [Cancer Res 2007;67(22):11021–8]
Data from Prolonged Exposure to Reduced Levels of Androgen Accelerates Prostate Cancer Progression in Nkx3.1; Pten Mutant Mice
Authors: Banach-Petrosky Whitney , Jessen Walter J. , Ouyang Xuesong , Gao Hui , Rao Jayashree , Quinn John , Aronow Bruce J. , Abate-Shen Cory
Published: March 2024

Abstract
In this report, we have investigated the relationship between androgen levels and prostate tumorigenesis in Nkx3.1; Pten mutant mice, a genetically engineered mouse model of human prostate cancer. By experimentally manipulating serum levels of testosterone in these mice for an extended period (i.e., 7 months), we have found that prolonged exposure of Nkx3.1; Pten mutant mice to androgen levels that are 10-fold lower than normal (the “Low-T” group) resulted in a marked acceleration of prostate tumorigenesis compared with those exposed to androgen levels within the reference range (the “Normal-T” group). We found that prostate tumors from the Low-T mutant mice share a similar gene expression profile as androgen-independent prostate tumors from these mutant mice, which includes the deregulated expression of several genes that are up-regulated in human hormone-refractory prostate cancer, such as Vav3 and Runx1. We propose that exposure to reduced androgens may promote prostate tumorigenesis by selecting for molecular events that promote more aggressive, hormone-refractory tumors. [Cancer Res 2007;67(19):9089–96]
Data from Loss of MLL PHD Finger 3 Is Necessary for MLL-ENL–Induced Hematopoietic Stem Cell Immortalization
Authors: Chen Jing , Santillan Donna A. , Koonce Mark , Wei Wei , Luo Roger , Thirman Michael J. , Zeleznik-Le Nancy J. , Diaz Manuel O.
Published: March 2024

Abstract
Reciprocal chromosomal translocations at the MLL gene locus result in expression of novel fusion proteins, such as MLL-ENL, associated with leukemia. The three PHD finger cassette, one of the highly conserved domains in MLL, is absent in all fusion proteins. This domain has been shown to interact with Cyp33, a cyclophilin which enhances the recruitment of histone deacetylases (HDAC) to the MLL repression domain and mediates HOX gene repression. Insertion of the third PHD finger of MLL into MLL-ENL allows the recruitment of Cyp33 and, subsequently, HDAC1 to the fusion protein. Furthermore, expression of the fusion protein with the PHD finger insertion mediates the down-regulation of the HOXC8 gene expression in a Cyp33-dependent manner. Finally, the addition of the PHD finger domain or the third PHD finger alone into MLL-ENL blocks the hematopoietic stem cell immortalization potential of the fusion protein in serial plating colony assays. Insertion of only the first and second PHD fingers has no such effect. These data support the hypothesis that the binding of Cyp33 to the MLL third PHD finger switches the MLL function from transactivation to repression. In the immortalizing MLL fusion protein, the loss of the PHD fingers, in combination with the gain of the activation domain of ENL or of other partner proteins, makes the fusion protein a constitutive transactivator. This leads to constitutive overexpression of MLL target genes that block stem cell commitment and promote stem cell renewal, probably the first step in MLL-related leukemogenesis. [Cancer Res 2008;68(15):6199–207]
Data from Transforming Growth Factor β1 Promotes Chromosomal Instability in Human Papillomavirus 16 E6E7–Infected Cervical Epithelial Cells
Authors: Deng Wen , Tsao Sai Wah , Kwok Yvonne K. , Wong Esther , Huang Xiao Ru , Liu Si , Tsang Chi M. , Ngan Hextan Y.S. , Cheung Annie N.Y. , Lan Hui Yao , Guan Xin-Yuan , Cheung Annie L.M.
Published: March 2024

Abstract
Uterine cervical cancer, the second most frequently occurring cancer in women worldwide, is tightly associated with the expression of high-risk human papillomavirus [mainly human papillomavirus (HPV)-16 and HPV18] oncogenes E6 and E7 and characteristically exhibits chromosomal instability. However, the mechanisms underlying chromosomal instability in cervical cancer are still not fully understood. In this study, we observed that two of three human cervical epithelial cell lines expressing HPV16 E6E7 became immortalized without extensive chromosomal instability and crisis. The introduction of transforming growth factor (TGF)-β1, a multiple functional cytokine/growth factor, in the culture medium induced crisis, which was associated with massive chromosomal end-to-end fusions and other structural aberrations. The distributions of structural aberrations on individual chromosomes were significantly correlated with the profiles of telomere signal–free ends. The immortalized cells that emerged from the TGF-β1–induced crisis showed multiple clonal structural aberrations that were not observed in cells without TGF-β1 treatment. Overexpression of the catalytic subunit of telomerase (hTERT) abolished the effects of TGF-β1 on chromosomal instability. Interestingly, another HPV16 E6E7–expressing cervical cell line that experienced crisis and telomere dysfunction under ordinary culture condition had a higher level of autocrine TGF-β1 production than the other two crisis-free immortalized cell lines. Blocking the TGF-β1 pathway by an inhibitor of TGF-β1 receptor type I prevented the crisis and telomere-mediated chromosomal instability. In addition, more dramatic telomere shortening was observed in cervical intraepithelial neoplasias having higher expression of TGF-β1 in vivo. These results together suggest an important role of TGF-β1 in the early process of cervical carcinogenesis. [Cancer Res 2008;68(17):7200–9]
Data from Degradation of Lung Adenoma Susceptibility 1, a Major Candidate Mouse Lung Tumor Modifier, Is Required for Cell Cycle Progression
Authors: Liu Yan , Vikis Haris G. , Yi Yijun , Futamura Manabu , Wang Yian , You Ming
Published: March 2024

Abstract
We have previously identified murine lung adenoma susceptibility 1 (Las1) as the pulmonary adenoma susceptibility 1 candidate gene. Las1 has two natural alleles, Las1-A/J and Las1-B6. Las1 encodes an 85-kDa protein with uncharacterized biological function. In the present study, we report that Las1 is an unstable protein and the rapid destruction of Las1 depends on the ubiquitin-proteasome pathway. Las1 is a new microtubule-binding protein and Las1 associated with tubulin is not ubiquitinated. We further show that Las1-A/J is a more stable protein than Las1-B6. Las1 is expressed in the G2 phase of the cell cycle and that ubiquitin-proteasome–mediated Las1 destruction occurs in mitosis. Overexpression of Las1-A/J inhibits normal E10 cell proliferation and induces a defective cytokinesis. The differential degradation of Las1-A/J and Las-B6 has important implications for its intracellular function and may eventually explain Las1-A/J in lung tumorigenesis. [Cancer Res 2007;67(21):10207–13]
Data from Elevated CRAF as a Potential Mechanism of Acquired Resistance to BRAF Inhibition in Melanoma
Authors: Montagut Clara , Sharma Sreenath V. , Shioda Toshi , McDermott Ultan , Ulman Matthew , Ulkus Lindsey E. , Dias-Santagata Dora , Stubbs Hannah , Lee Diana Y. , Singh Anurag , Drew Lisa , Haber Daniel A. , Settleman Jeffrey
Published: March 2024

Abstract
Activating BRAF kinase mutations arise in ∼7% of all human tumors, and preclinical studies have validated the RAF–mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase–ERK signaling cascade as a potentially important therapeutic target in this setting. Selective RAF kinase inhibitors are currently undergoing clinical development, and based on the experience with other kinase-targeted therapeutics, it is expected that clinical responses to these agents, if observed, will lead to the eventual emergence of drug resistance in most cases. Thus, it is important to establish molecular mechanisms underlying such resistance to develop effective therapeutic strategies to overcome or prevent drug resistance. To anticipate potential mechanisms of acquired resistance to RAF inhibitors during the course of treatment, we established drug-resistant clones from a human melanoma-derived cell line harboring the recurrent V600E activating BRAF mutation, which exhibits exquisite sensitivity to AZ628, a selective RAF kinase inhibitor. We determined that elevated CRAF protein levels account for the acquisition of resistance to AZ628 in these cells, associated with a switch from BRAF to CRAF dependency in tumor cells. We also found that elevated CRAF protein levels may similarly contribute to primary insensitivity to RAF inhibition in a subset of BRAF mutant tumor cells. Interestingly, AZ628-resistant cells demonstrating either primary drug insensitivity or acquired drug resistance exhibit exquisite sensitivity to the HSP90 inhibitor geldanamycin. Geldanamycin effectively promotes the degradation of CRAF, thereby revealing a potential therapeutic strategy to overcome resistance to RAF inhibition in a subset of BRAF mutant tumors. [Cancer Res 2008;68(12):4853–61]
Data from MicroRNA Signatures in Human Ovarian Cancer
Authors: Iorio Marilena V. , Visone Rosa , Di Leva Gianpiero , Donati Valentina , Petrocca Fabio , Casalini Patrizia , Taccioli Cristian , Volinia Stefano , Liu Chang-Gong , Alder Hansjuerg , Calin George A. , Ménard Sylvie , Croce Carlo M.
Published: March 2024

Abstract
Epithelial ovarian cancer (EOC) is the sixth most common cancer in women worldwide and, despite advances in detection and therapies, it still represents the most lethal gynecologic malignancy in the industrialized countries. Unfortunately, still relatively little is known about the molecular events that lead to the development of this highly aggressive disease. The relatively recent discovery of microRNAs (miRNA), a class of small noncoding RNAs targeting multiple mRNAs and triggering translation repression and/or RNA degradation, has revealed the existence of a new level of gene expression regulation. Multiple studies involving various types of human cancers proved that miRNAs have a causal role in tumorigenesis. Here we show that, in comparison to normal ovary, miRNAs are aberrantly expressed in human ovarian cancer. The overall miRNA expression could clearly separate normal versus cancer tissues. The most significantly overexpressed miRNAs were miR-200a, miR-141, miR-200c, and miR-200b, whereas miR-199a, miR-140, miR-145, and miR-125b1 were among the most down-modulated miRNAs. We could also identify miRNAs whose expression was correlated with specific ovarian cancer biopathologic features, such as histotype, lymphovascular and organ invasion, and involvement of ovarian surface. Moreover, the levels of miR-21, miR-203, and miR-205, up-modulated in ovarian carcinomas compared with normal tissues, were significantly increased after 5-aza-2′-deoxycytidine demethylating treatment of OVCAR3 cells, suggesting that the DNA hypomethylation could be the mechanism responsible for their overexpression. Our results indicate that miRNAs might play a role in the pathogenesis of human EOC and identify altered miRNA gene methylation as a possible epigenetic mechanism involved in their aberrant expression. [Cancer Res 2007;67(18):8699–707]
Data from The Activity of Zoledronic Acid on Neuroblastoma Bone Metastasis Involves Inhibition of Osteoclasts and Tumor Cell Survival and Proliferation
Authors: Peng Hongjun , Sohara Yasuyoshi , Moats Rex A. , Nelson Marvin D. , Groshen Susan G. , Ye Wei , Reynolds C. Patrick , DeClerck Yves A.
Published: March 2024

Abstract
Metastasis to the bone is seen in 56% of patients with neuroblastoma and contributes to morbidity and mortality. Using a murine model of bone invasion, we have reported previously that neuroblastoma cells invade the bone by activating osteoclasts. Here, we investigated the antitumoral and antiosteolytic activities of zoledronic acid, a bisphosphonate inhibitor of osteoclasts, in combination with cytotoxic chemotherapy in our model. We first show that zoledronic acid given at the same time (early prevention) or 2 weeks after tumor cell injection (late prevention) significantly prevented the formation of severe osteolytic lesions. It also prevented formation of these lesions when given 4 weeks after tumor cell injection (intervention) when combined with chemotherapy including cyclophosphamide and topotecan. The combination of zoledronic acid + cyclophosphamide/topotecan also significantly improved survival (P < 0.001). In mice treated with zoledronic acid, we observed a marked inhibition of osteoclasts inside the bone associated with a decrease in tumor cell proliferation and increase in tumor cell apoptosis. In vitro, zoledronic acid inhibited neuroblastoma cell proliferation and induced apoptosis, and these effects were significantly enhanced by the addition of 4-hydroxyperoxycyclophosphamide (4-HC). The proapoptotic effect of zoledronic acid and zoledronic acid in combination with 4-HC on tumor cells was associated with an increase in caspase-3 activity and a decrease in phosphorylated Bcl-2, Bcl-2, and Bcl-XL expression. Zoledronic acid inhibited the association of Ras with the plasma membrane and activation of c-Raf, Akt, and extracellular signal-regulated kinase 1/2. The data indicate that zoledronic acid, in addition to inhibiting osteoclasts, is active against tumor cells and suggest that zoledronic acid in combination with cytotoxic chemotherapy may be effective in children with neuroblastoma that has metastasized to the bone. [Cancer Res 2007;67(19):9346–55]
Data from Hoxb7 Inhibits Transgenic HER-2/neu–Induced Mouse Mammary Tumor Onset but Promotes Progression and Lung Metastasis
Authors: Chen Hexin , Lee Ji Shin , Liang Xiaohui , Zhang Huiping , Zhu Tao , Zhang Zhe , Taylor M. Evangeline , Zahnow Cynthia , Feigenbaum Lionel , Rein Alan , Sukumar Saraswati
Published: March 2024

Abstract
Our previous studies have shown that HOXB7 mRNA is overexpressed in ∼50% of invasive breast carcinomas and promotes tumor progression in breast cancer cells grown as xenografts in mice. In silico analysis of published microarray data showed that high levels of HOXB7 predict a poor outcome in HER-2–positive (P = 0.046), but not in HER-2–negative breast cancers (P = 0.94). To study the function of HOXB7 in vivo in the context of HER-2 overexpression, we generated mouse mammary tumor virus (MMTV)-Hoxb7 transgenic mice, and then crossed them with MMTV-HER-2/neu transgenic mice. In the mice carrying both Hoxb7 and HER-2/neu transgenes, Hoxb7 plays a dual role in mammary tumorigenesis. In double transgenic mice, overexpression of Hoxb7 delayed tumor onset and lowered tumor multiplicity. However, consistent with the clinical data, once the tumors appeared, their growth was faster and metastasis to the lungs occurred at a higher frequency. Our data show, for the first time, that deregulated expression of Hoxb7 in mammary tumor cells can significantly modulate HER-2/neu-oncogene induced tumorigenesis in vivo. [Cancer Res 2008;68(10):3637–44]
Data from Matrix Metalloproteinases-1 and -8 Improve the Distribution and Efficacy of an Oncolytic Virus
Authors: Mok Wilson , Boucher Yves , Jain Rakesh K.
Published: March 2024

Abstract
Oncolytic viral vectors show enormous potential for the treatment of many solid tumors. However, these vectors often suffer from insufficient delivery within tumors, which limits their efficacy in both preclinical and clinical settings. We have previously shown that tumor collagen can significantly hinder diffusion, and that its degradation can enhance the distribution and efficacy of an oncolytic herpes simplex virus (HSV) vector. Here, we identify two members of the matrix metalloproteinase (MMP) family of enzymes, MMP-1 and MMP-8, which can modulate the tumor matrix and enhance HSV delivery and efficacy. We show that overexpression of MMP-1 and MMP-8 in the human soft tissue sarcoma HSTS26T leads to a significant depletion of tumor-sulfated glycosaminoglycans. This increases the hydraulic conductivity of these tumors and enhances the flow of virus during injection. In control tumors, injected virus accumulates primarily in the periphery of the tumor. In contrast, we observed a more widespread distribution of virus around the injection site in MMP-1– and MMP-8–expressing tumors. Due to this enhanced vector delivery, MMP-expressing tumors respond significantly better to oncolytic HSV treatment than control tumors. Thus, these findings introduce a new approach to improve the delivery and efficacy of oncolytic viral vectors: modulation of tumor glycosaminoglycans to enhance convection. [Cancer Res 2007;67(22):10664–8]
Data from A Novel Bone Morphogenetic Protein Signaling in Heterotypic Cell Interactions in Prostate Cancer
Authors: Yang Shangxin , Pham Linda K. , Liao Chun-Peng , Frenkel Baruch , Reddi A. Hari , Roy-Burman Pradip
Published: March 2024

Abstract
We examined the effect of the extracellular bone morphogenetic protein (BMP) 2 and 7, which are up-regulated in the prostate adenocarcinomas of the conditional Pten deletion mouse model, on primary cultures of cancer-associated fibroblasts (CAF) derived from these tumors. In the CAF, we show that BMP2 or BMP7, but not transforming growth factor β-1, can strikingly stimulate secretion of stromal cell–derived factor-1 (SDF-1), also known as CXCL12. The CAF cells express type I and type II BMP receptors as well as the receptor for SDF-1, CXCR4. SDF-1 activation is associated with BMP-induced Smad phosphorylation, and the stimulatory effect is blocked by BMP antagonist, noggin. The findings that BMP treatment can increase SDF-1 pre-mRNA levels in a time-dependent manner and actinomycin D treatment can abolish stimulatory effect of BMP suggest a transcriptional modulation of SDF-1 by BMP signaling. Using a human microvascular endothelial cell line, we show that SDF-1 present in the conditioned medium from the stimulated CAF can significantly induce tube formation, an effect relating to angiogenic function. Furthermore, we found that BMP2 can also protect the CAF from serum starvation–induced apoptosis independent of SDF-1, implying that BMP may induce other factors to sustain the survival of these cells. In short, this report establishes a novel BMP-SDF-1 axis in the prostate tumor along with a new prosurvival effect of BMP that when considered together with our previously described oncogenic properties of BMP indicate a circuitry for heterotypic cell interactions potentially critical in prostate cancer. [Cancer Res 2008;68(1):198–205]
Data from Oncogenic BARD1 Isoforms Expressed in Gynecological Cancers
Authors: Li Lin , Ryser Stephan , Dizin Eva , Pils Dietmar , Krainer Michael , Jefford Charles Edward , Bertoni Francesco , Zeillinger Robert , Irminger-Finger Irmgard
Published: March 2024

Abstract
BARD1 is required for protein stability and tumor suppressor functions of BRCA1, which depend on the ubiquitin ligase activity of the BRCA1-BARD1 heterodimer. The NH2-terminal RING domains of both proteins act as interaction modules and form a ubiquitin ligase, which has functions in DNA repair, cell cycle checkpoint regulation, and mitosis. Interestingly, up-regulated expression of truncated BARD1 isoforms was found to be associated with poor prognosis in breast and ovarian cancers and, in a hormonally regulated fashion, in the human cytotrophoblast, a cell type with properties reminiscent of cancer cells. We therefore performed reverse transcription-PCR to determine the structure of BARD1 isoforms in cell lines derived from hormone-dependent and hormone-independent cancers. We found a specific combination of isoforms, generated by differential splicing and alternative transcription initiation, mostly lacking the BRCA1 interaction domain, in gynecologic but not hematologic cancer cell lines. To investigate the prevalence of BARD1 isoforms in tumors, we applied immunohistochemistry to ovarian cancers, using antibodies distinguishing full-length BARD1 and isoforms. Expression of NH2 terminally truncated BARD1 was correlated with advanced stage of cancer, and expression of spliced isoforms was typical for clear cell carcinoma, the ovarian cancer with worst prognosis, suggesting a role of BARD1 isoforms in cancer progression. To challenge this hypothesis, we silenced BARD1 isoforms in ovarian cancer cells that lacked wild-type BARD1 by siRNA interference, which led to a complete proliferation arrest. Thus, BARD1 isoform expression is required for cancer cell proliferation, which is compatible with the notion that BARD1 isoforms act as cancer maintenance genes. [Cancer Res 2007;67(24):11876–85]
Data from Histone Deacetylase Inhibitors Synergize p300 Autoacetylation that Regulates Its Transactivation Activity and Complex Formation
Authors: Stiehl Daniel P. , Fath Donna M. , Liang Dongming , Jiang Yubao , Sang Nianli
Published: March 2024

Abstract
p300/cyclic AMP–responsive element binding protein–binding protein (CBP) are general coactivators for multiple transcription factors involved in various cellular processes. Several highly conserved domains of p300/CBP serve as interacting sites for transcription factors and regulatory proteins. Particularly, the intrinsic histone acetyltransferase (HAT) activity and transactivation domains (TAD) play essential roles for their coactivating function. Autoacetylation of p300/CBP is commonly observed in cell-free HAT assays and has been implicated in the regulation of their HAT activity. Here, we show that six lysine-rich regions in several highly conserved functional domains of p300 are targeted by p300HAT for acetylation in cell-free systems. We show that p300 is susceptible to acetylation in cultured tumor cells and that its acetylation status is affected by histone deacetylase inhibitor trichostatin A. We further show that either treatment with deacetylase inhibitors or coexpression of Gal4-p300HAT, which alone has no transactivation activity, stimulates the activity of the COOH-terminal TAD of p300 (p300C-TAD). We have defined the minimal p300C-TAD and show that it is sufficient to respond to deacetylase inhibitors and is a substrate for p300HAT. Finally, we show that acetylated p300 possesses enhanced ability to interact with p53. Taken together, our data suggest that acetylation regulates p300C-TAD and that acetylation of p300/CBP may contribute to the dynamic regulation of their complex formation with various interacting partners. [Cancer Res 2007;67(5):2256–64]
Data from A Novel Bioluminescent Mouse Model and Effective Therapy for Adult T-Cell Leukemia/Lymphoma
Authors: Shu Sherry T. , Nadella Murali V.P. , Dirksen Wessel P. , Fernandez Soledad A. , Thudi Nanda K. , Werbeck Jillian L. , Lairmore Michael D. , Rosol Thomas J.
Published: March 2024

Abstract
Adult T-cell /lymphomaleukemia (ATLL) is caused by human T-cell lymphotropic virus type 1 (HTLV-1). Approximately 80% of ATLL patients develop humoral hypercalcemia of malignancy (HHM), a life-threatening complication leading to a poor prognosis. Parathyroid hormone–related protein (PTHrP) and macrophage inflammatory protein-1α (MIP-1α) are important factors in the pathogenesis of HHM in ATLL and the expression of PTHrP can be activated by nuclear factor κB (NF-κB). NF-κB is constitutively activated in ATLL cells and is essential for leukemogenesis including transformation of lymphocytes infected by HTLV-1. Our goal was to evaluate the effects of NF-κB disruption by a proteasomal inhibitor (PS-341) and osteoclastic inhibition by zoledronic acid (Zol) on the development of ATLL and HHM using a novel bioluminescent mouse model. We found that PS-341 decreased cell viability, increased apoptosis, and down-regulated PTHrP expression in ATLL cells in vitro. To investigate the in vivo efficacy, nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice were xenografted with ATLL cells and treated with vehicle control, PS-341, Zol, or a combination of PS-341 and Zol. Bioluminescent imaging and tumor cell count showed a significant reduction in tumor burden in mice from all treatment groups. All treatments also significantly reduced the plasma calcium concentrations. Zol treatment increased trabecular bone volume and decreased osteoclast parameters. PS-341 reduced PTHrP and MIP-1α expression in tumor cells in vivo. Our results indicate that both PS-341 and Zol are effective treatments for ATLL and HHM, which are refractory to conventional therapy. [Cancer Res 2007;67(24):11859–66]
Data from Centrosomal PKCβII and Pericentrin Are Critical for Human Prostate Cancer Growth and Angiogenesis
Authors: Kim Jeewon , Choi Yoon-La , Vallentin Alice , Hunrichs Ben S. , Hellerstein Marc K. , Peehl Donna M. , Mochly-Rosen Daria
Published: March 2024

Abstract
Angiogenesis is critical in the progression of prostate cancer. However, the interplay between the proliferation kinetics of tumor endothelial cells (angiogenesis) and tumor cells has not been investigated. Also, protein kinase C (PKC) regulates various aspects of tumor cell growth, but its role in prostate cancer has not been investigated in detail. Here, we found that the proliferation rates of endothelial and tumor cells oscillate asynchronously during the growth of human prostate cancer xenografts. Furthermore, our analyses suggest that PKCβII was activated during increased angiogenesis and that PKCβII plays a key role in the proliferation of endothelial cells and tumor cells in human prostate cancer; treatment with a PKCβII-selective inhibitor, βIIV5-3, reduced angiogenesis and tumor cell proliferation. We also find a unique effect of PKCβII inhibition on normalizing pericentrin (a protein regulating cytokinesis), especially in endothelial cells as well as in tumor cells. PKCβII inhibition reduced the level and mislocalization of pericentrin and normalized microtubule organization in the tumor endothelial cells. Although pericentrin has been known to be up-regulated in epithelial cells of prostate cancers, its level in tumor endothelium has not been studied in detail. We found that pericentrin is up-regulated in human tumor endothelium compared with endothelium adjacent to normal glands in tissues from prostate cancer patients. Our results suggest that a PKCβII inhibitor such as βIIV5-3 may be used to reduce prostate cancer growth by targeting both angiogenesis and tumor cell growth. [Cancer Res 2008;68(16):6831–9]
Data from Sustained Antigen-Specific Antitumor Recall Response Mediated by Gene-Modified CD4+ T Helper-1 and CD8+ T Cells
Authors: Moeller Maria , Kershaw Michael H. , Cameron Rachel , Westwood Jennifer A. , Trapani Joseph A. , Smyth Mark J. , Darcy Phillip K.
Published: March 2024

Abstract
Given that specific subsets of T helper 1 (Th1) and T helper 2 (Th2) CD4+ T cells have been shown to play key roles in tumor rejection models, we wanted to assess the contribution of either Th1 or Th2 CD4+ cell subtypes for redirected T-cell immunotherapy. In this study, we have developed a novel method involving retroviral transduction and in vitro T-cell polarization to generate gene-engineered mouse CD4+ Th1 and Th2 cells or T helper intermediate (Thi) cells expressing an anti–erbB2-CD28-ζ chimeric receptor. Gene-modified Th1 and Th2 polarized CD4+ cells were characterized by the preferential secretion of IFN-γ and interleukin-4, respectively, whereas Thi cells secreted both cytokines following receptor ligation. In adoptive transfer studies using an erbB2+ lung metastasis model, complete survival of mice was observed when transduced Th1, Th2, or Thi CD4+ cells were transferred in combination with an equivalent number of transduced CD8+ T cells. Tumor rejection was consistently associated with transduced T cells at the tumor site and interleukin-2 secretion. However, the surviving mice treated with gene-modified Th1 CD4+ cells were significantly more resistant to a subsequent challenge with a different erbB2+ tumor (4T1.2) implanted s.c. This result correlated with both increased expansion of Th1 CD4+ and CD8+ T cells in the blood and a greater number of these cells localizing to the tumor site following rechallenge. These data support the use of gene-modified CD4+ Th1 and CD8+ T cells for mediating a sustained antitumor response. [Cancer Res 2007;67(23):11428–37]
Data from Feedback Mechanisms Promote Cooperativity for Small Molecule Inhibitors of Epidermal and Insulin-Like Growth Factor Receptors
Authors: Buck Elizabeth , Eyzaguirre Alexandra , Rosenfeld-Franklin Maryland , Thomson Stuart , Mulvihill Mark , Barr Sharon , Brown Eric , O'Connor Mathew , Yao Yan , Pachter Jonathan , Miglarese Mark , Epstein David , Iwata Kenneth K. , Haley John D. , Gibson Neil W. , Ji Qun-Sheng
Published: March 2024

Abstract
Epidermal growth factor receptor (EGFR) and insulin-like growth factor-I receptor (IGF-IR) can cooperate to regulate tumor growth and survival, and synergistic growth inhibition has been reported for combined blockade of EGFR and IGF-IR. However, in preclinical models, only a subset of tumors exhibit high sensitivity to this combination, highlighting the potential need for patient selection to optimize clinical efficacy. Herein, we have characterized the molecular basis for cooperative growth inhibition upon dual EGFR and IGF-IR blockade and provide biomarkers that seem to differentiate response. We find for epithelial, but not for mesenchymal-like, tumor cells that Akt is controlled cooperatively by EGFR and IGF-IR. This correlates with synergistic apoptosis and growth inhibition in vitro and growth regression in vivo upon combined blockade of both receptors. We identified two molecular aspects contributing to synergy: (a) inhibition of EGFR or IGF-IR individually promotes activation of the reciprocal receptor; (b) inhibition of EGFR-directed mitogen-activated protein kinase (MAPK) shifts regulation of Akt from EGFR toward IGF-IR. Targeting the MAPK pathway through downstream MAPK/extracellular signal-regulated kinase kinase (MEK) antagonism similarly promoted IGF-driven pAkt and synergism with IGF-IR inhibition. Mechanistically, we find that inhibition of the MAPK pathway circumvents a negative feedback loop imposed on the IGF-IR– insulin receptor substrate 1 (IRS-1) signaling complex, a molecular scenario that parallels the negative feedback loop between mTOR-p70S6K and IRS-1 that mediates rapamycin-directed IGF-IR signaling. Collectively, these data show that resistance to inhibition of MEK, mTOR, and EGFR is associated with enhanced IGF-IR–directed Akt signaling, where all affect feedback loops converging at the level of IRS-1. [Cancer Res 2008;68(20):8322–32]
Data from Inactivation of gadd45a Sensitizes Epithelial Cancer Cells to Ionizing Radiation In vivo Resulting in Prolonged Survival
Authors: Lu Xiangdong , Yang Chunyu , Hill Reginald , Yin Chaoyin , Hollander M. Christine , Fornace Albert J. , Van Dyke Terry
Published: March 2024

Abstract
Ionizing radiation (IR) therapy is one of the most commonly used treatments for cancer patients. The responses of tumor cells to IR are often tissue specific and depend on pathway aberrations present in the tumor. Identifying molecules and mechanisms that sensitize tumor cells to IR provides new potential therapeutic strategies for cancer treatment. In this study, we used two genetically engineered mouse carcinoma models, brain choroid plexus carcinoma (CPC) and prostate, to test the effect of inactivating gadd45a, a DNA damage response p53 target gene, on tumor responses to IR. We show that gadd45a deficiency significantly increases tumor cell death after radiation. Effect on survival was assessed in the CPC model and was extended in IR-treated mice with gadd45a deficiency compared with those expressing wild-type gadd45a. These studies show a significant effect of gadd45a inactivation in sensitizing tumor cells to IR, implicating gadd45a as a potential drug target in radiotherapy management. [Cancer Res 2008;68(10):3579–83]
Data from Endogenous Interleukin-4 Promotes Tumor Development by Increasing Tumor Cell Resistance to Apoptosis
Authors: Li Zhiguang , Jiang Jing , Wang Zibing , Zhang Jinhua , Xiao Mingjie , Wang Chunhui , Lu Yu , Qin Zhihai
Published: March 2024

Abstract
The increase of interleukin-4 (IL-4) level in tumor environment and the up-regulation of IL-4 receptor (IL-4R) on tumor cells have been long observed. However, their significance for tumor development has not been investigated. Here, we found that endogenous IL-4 promotes tumor growth because neutralizing IL-4 by 11B11 monoclonal antibody (mAb) significantly delayed the growth of MCA205 fibrosarcoma. We also observed that tumor cells with higher IL-4R expression have more chances to survive in immunocompetent mice. To investigate how endogenous IL-4 influences tumor growth, we established a pair of tumor cells with or without IL-4R expression from the common parental cells. IL-4R–competent tumors exhibit increased growth compared with its IL-4R–deficient counterparts when inoculated into syngeneic mice. This growth advantage was still kept in IL-4R knockout mice but was abrogated in mice given i.p. with IL-4 neutralizing mAb. In vitro analyses indicate that IL-4 neither affects the proliferation of tumor cells nor changes the expression of several immune-related molecules, such as MHC-I, Fas, and B7-H3. Nonetheless, IL-4 up-regulates antiapoptotic gene expression in tumor cells and reduces apoptosis of tumor cells in vivo, as evidenced by real-time PCR, immunoblotting, and TUNEL staining. These findings were helpful to understand the long clinical observation and revealed that endogenous IL-4, the product of host immune response, can be used by tumor cells to facilitate their growth. [Cancer Res 2008;68(21):8687–94]
Data from Identification and Characterization of Ovarian Cancer-Initiating Cells from Primary Human Tumors
Authors: Zhang Shu , Balch Curt , Chan Michael W. , Lai Hung-Cheng , Matei Daniela , Schilder Jeanne M. , Yan Pearlly S. , Huang Tim H-M. , Nephew Kenneth P.
Published: March 2024

Abstract
The objective of this study was to identify and characterize a self-renewing subpopulation of human ovarian tumor cells (ovarian cancer-initiating cells, OCICs) fully capable of serial propagation of their original tumor phenotype in animals. Ovarian serous adenocarcinomas were disaggregated and subjected to growth conditions selective for self-renewing, nonadherent spheroids previously shown to derive from tissue stem cells. To affirm the existence of OCICs, xenoengraftment of as few as 100 dissociated spheroid cells allowed full recapitulation of the original tumor (grade 2/grade 3 serous adenocarcinoma), whereas >105 unselected cells remained nontumorigenic. Stemness properties of OCICs (under stem cell–selective conditions) were further established by cell proliferation assays and reverse transcription–PCR, demonstrating enhanced chemoresistance to the ovarian cancer chemotherapeutics cisplatin or paclitaxel and up-regulation of stem cell markers (Bmi-1, stem cell factor, Notch-1, Nanog, nestin, ABCG2, and Oct-4) compared with parental tumor cells or OCICs under differentiating conditions. To identify an OCIC cell surface phenotype, spheroid immunostaining showed significant up-regulation of the hyaluronate receptor CD44 and stem cell factor receptor CD117 (c-kit), a tyrosine kinase oncoprotein. Similar to sphere-forming OCICs, injection of only 100 CD44+CD117+ cells could also serially propagate their original tumors, whereas 105 CD44−CD117− cells remained nontumorigenic. Based on these findings, we assert that epithelial ovarian cancers derive from a subpopulation of CD44+CD117+ cells, thus representing a possible therapeutic target for this devastating disease. [Cancer Res 2008;68(11):4311–20]
Data from Cyclooxygenase-2–Derived Prostaglandin E2 Activates β-Catenin in Human Cholangiocarcinoma Cells: Evidence for Inhibition of These Signaling Pathways by ω3 Polyunsaturated Fatty Acids
Authors: Lim Kyu , Han Chang , Xu Lihong , Isse Kumiko , Demetris Anthony J. , Wu Tong
Published: March 2024

Abstract
Cholangiocarcinoma is a highly malignant neoplasm of the biliary tree. It has a high rate of mortality, and currently, there is no effective chemoprevention and treatment. This study was designed to investigate the potential effect of ω3 polyunsaturated fatty acids (ω3-PUFA) on human cholangiocarcinoma cell growth and to determine their mechanisms of actions. Treatment of three human cholangiocarcinoma cells (CCLP1, HuCCT1, SG231) with two ω3-PUFAs, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), for 12 to 72 h resulted in a dose- and time-dependent inhibition of cell growth; in contrast, arachidonic acid, a ω6-PUFA, had no significant effect. The ω3-PUFA effect is due to the induction of apoptosis, given that DHA induced the cleaved form of PARP, caspase-3, and caspase-9. DHA and EPA treatment caused dephosphorylation (and hence, the activation) of glycogen synthase kinase-3β (GSK-3β) with a decline of β-catenin protein. Accordingly, DHA treatment also decreased the β-catenin–mediated T cell factor/lymphoid enhancer factor (TCF/LEF) reporter activity, and inhibited the expression of c-Met, a β-catenin–controlled downstream gene implicated in cholangiocarcinogenesis. The GSK-3β inhibitor, SB216763, partially prevented DHA-induced reduction of β-catenin protein and TCF/LEF reporter activity, and restored cell growth, suggesting the involvement of GSK-3β dephosphorylation in ω3-PUFA–induced β-catenin degradation. In parallel, DHA treatment also induced the formation of the β-catenin/Axin/GSK-3β binding complex, further leading to β-catenin degradation. Moreover, DHA inhibited the expression of cyclooxygenase-2 (COX-2) and enhanced the expression of 15-hydroxyprostaglandin dehydrogenase, a physiologic COX-2 antagonist, in human cholangiocarcinoma cells. These findings suggest that ω3-PUFAs block cholangiocarcinoma cell growth at least in part through inhibition of Wnt/β-catenin and COX-2 signaling pathways. Thus, utilization of ω3-PUFAs may represent an effective and safe therapeutic approach for the chemoprevention and treatment of human cholangiocarcinoma. [Cancer Res 2008;68(2):553–60]
Data from Negative Feedback Regulation of IFN-γ Pathway by IFN Regulatory Factor 2 in Esophageal Cancers
Authors: Wang Yan , Liu Dongping , Chen Pingping , Koeffler H. Phillip , Tong Xiangjun , Xie Dong
Published: March 2024

Abstract
IFN-γ is an antitumor cytokine that inhibits cell proliferation and induces apoptosis after engagement with the IFN-γ receptors (IFNGR) expressed on target cells, whereas IFN regulatory factor 2 (IRF-2) is able to block the effects of IFN-γ by repressing transcription of IFN-γ–induced genes. Thus far, few studies have explored the influences of IFN-γ on human esophageal cancer cells. In the present study, therefore, we investigated in detail the functions of IFN-γ in esophageal cancer cells. The results in clinical samples of human esophageal cancers showed that the level of IFN-γ was increased in tumor tissues and positively correlated with tumor progression and IRF-2 expression, whereas the level of IFNGR1 was decreased and negatively correlated with tumor progression and IRF-2 expression. Consistently, in vitro experiments showed that low concentration of IFN-γ induced the expression of IRF-2 with potential promotion of cell growth, and moreover, IRF-2 was able to suppress IFNGR1 transcription in human esophageal cancer cells by binding a specific motif in IFNGR1 promoter, which lowered the sensitivity of esophageal cancer cells to IFN-γ. Taken together, our results disclosed a new IRF-2–mediated inhibitory mechanism for IFN-γ–induced pathway in esophageal cancer cells: IFN-γ induced IRF-2 up-regulation, then up-regulated IRF-2 decreased endogenous IFNGR1 level, and finally, the loss of IFNGR1 turned to enhance the resistance of esophageal cancer cells to IFN-γ. Accordingly, the results implied that IRF-2 might act as a mediator for the functions of IFN-γ and IFNGR1 in human esophageal cancers. [Cancer Res 2008;68(4):1136–43]
Data from Vascular Endothelial Growth Factor–Mediated Decrease in Plasma Soluble Vascular Endothelial Growth Factor Receptor-2 Levels as a Surrogate Biomarker for Tumor Growth
Authors: Ebos John M.L. , Lee Christina R. , Bogdanovic Elena , Alami Jennifer , Van Slyke Paul , Francia Giulio , Xu Ping , Mutsaers Anthony J. , Dumont Daniel J. , Kerbel Robert S.
Published: March 2024

Abstract
Vascular endothelial growth factor (VEGF) is a potent proangiogenic protein that activates VEGF receptor (VEGFR) tyrosine kinases expressed by vascular endothelial cells. We previously showed that one of these receptors, VEGFR-2, has a truncated soluble form (sVEGFR-2) that can be detected in mouse and human plasma. Because activation of VEGFR-2 plays an important role in tumor angiogenesis, clinical interest in monitoring plasma sVEGFR-2 levels in cancer patients has focused on its potential exploitation as a surrogate biomarker for disease progression as well as assessing efficacy/activity of antiangiogenic drugs, particularly those that target VEGF or VEGFR-2. However, no preclinical studies have been done to study sVEGFR-2 during tumor growth or the mechanisms involved in its modulation. Using spontaneously growing tumors and both localized and metastatic human tumor xenografts, we evaluated the relationship between sVEGFR-2 and tumor burden as well as underlying factors governing protein level modulation in vivo. Our results show an inverse relationship between the levels of sVEGFR-2 and tumor size. Furthermore, using various methods of VEGF overexpression in vivo, including cell transfection and adenoviral delivery, we found plasma sVEGFR-2 decreases to be mediated largely by tumor-derived VEGF. Finally, in vitro studies indicate VEGF-mediated sVEGFR-2 modulation is the result of ligand-induced down-regulation of the VEGFR-2 from the cell surface. Taken together, these findings may be pertinent to further clinical exploitation of plasma sVEGFR-2 levels as a surrogate biomarker of VEGF-dependent tumor growth as well as an activity indicator of antiangiogenic drugs that target the VEGFR system. [Cancer Res 2008;68(2):521–9]
Data from BAF180 Is a Critical Regulator of p21 Induction and a Tumor Suppressor Mutated in Breast Cancer
Authors: Xia Wei , Nagase Satoru , Montia Amy Gerstein , Kalachikov Sergey M. , Keniry Megan , Su Tao , Memeo Lorenzo , Hibshoosh Hanina , Parsons Ramon
Published: March 2024

Abstract
Screening for tumor suppressor genes in breast cancer revealed multiple truncating mutations of PB1, which encodes the BAF180 subunit of the PBAF chromatin remodeling complex. Mutation was associated with loss of heterozygosity of the wild-type allele. BAF180 complementation of BAF180-mutant tumor cells caused G1 arrest that was dependent on increased expression of the cyclin/cyclin-dependent kinase inhibitor p21/WAF1/CIP1. Endogenous wild-type BAF180 bound to the p21 promoter and was required for proper p21 expression and G1 arrest after transforming growth factor-β and γ-radiation treatment. BAF180 thus functions on two tumor suppressor signaling pathways as a physiologic mediator of p21 expression. We conclude that BAF180 suppresses tumorigenesis, at least in part, through its ability to regulate p21. [Cancer Res 2008;68(6):1667–74]