bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Functional Loss of ATRX and TERC Activates Alternative Lengthening of Telomeres (ALT) in LAPC4 Prostate Cancer Cells
Authors: Graham Mindy K. , Kim Jiyoung , Da Joseph , Brosnan-Cashman Jacqueline A. , Rizzo Anthony , Baena Del Valle Javier A. , Chia Lionel , Rubenstein Michael , Davis Christine , Zheng Qizhi , Cope Leslie , Considine Michael , Haffner Michael C. , De Marzo Angelo M. , Meeker Alan K. , Heaphy Christopher M.
Published: March 2024

Abstract
A key hallmark of cancer, unlimited replication, requires cancer cells to evade both replicative senescence and potentially lethal chromosomal instability induced by telomere dysfunction. The majority of cancers overcome these critical barriers by upregulating telomerase, a telomere-specific reverse transcriptase. However, a subset of cancers maintains telomere lengths by the telomerase-independent Alternative Lengthening of Telomeres (ALT) pathway. The presence of ALT is strongly associated with recurrent cancer-specific somatic inactivating mutations in the ATRX-DAXX chromatin-remodeling complex. Here, we generate an ALT-positive adenocarcinoma cell line following functional inactivation of ATRX and telomerase in a telomerase-positive adenocarcinoma cell line. Inactivating mutations in ATRX were introduced using CRISPR-cas9 nickase into two prostate cancer cell lines, LAPC-4 (derived from a lymph node metastasis) and CWR22Rv1 (sourced from a xenograft established from a primary prostate cancer). In LAPC-4, but not CWR22Rv1, abolishing ATRX was sufficient to induce multiple ALT-associated hallmarks, including the presence of ALT-associated promyelocytic leukemia bodies (APB), extrachromosomal telomere C-circles, and dramatic telomere length heterogeneity. However, telomerase activity was still present in these ATRXKO cells. Telomerase activity was subsequently crippled in these LAPC-4 ATRXKO cells by introducing mutations in the TERC locus, the essential RNA component of telomerase. These LAPC-4 ATRXKO TERCmut cells continued to proliferate long-term and retained ALT-associated hallmarks, thereby demonstrating their reliance on the ALT mechanism for telomere maintenance.
Implications:
These prostate cancer cell line models provide a unique system to explore the distinct molecular alterations that occur upon induction of ALT, and may be useful tools to screen for ALT-specific therapies.
Data from MCL1 and DEDD Promote Urothelial Carcinoma Progression
Authors: Hong Andrew L. , Guerriero Jennifer L. , Doshi Mihir B. , Kynnap Bryan D. , Kim Won Jun , Schinzel Anna C. , Modiste Rebecca , Schlauch Amy J. , Adam Rosalyn M. , Kwiatkowski David J. , Beroukhim Rameen , Letai Anthony , Rosenberg Jonathan E. , Hahn William C.
Published: March 2024

Abstract
Focal amplification of chromosome 1q23.3 in patients with advanced primary or relapsed urothelial carcinomas is associated with poor survival. We interrogated chromosome 1q23.3 and the nearby focal amplicon 1q21.3, as both are associated with increased lymph node disease in patients with urothelial carcinoma. Specifically, we assessed whether the oncogene MCL1 that resides in 1q21.3 and the genes that reside in the 1q23.3 amplicon were required for the proliferation or survival of urothelial carcinoma. We observed that suppressing MCL1 or the death effector domain–containing protein (DEDD) in the cells that harbor amplifications of 1q21.3 or 1q23.3, respectively, inhibited cell proliferation. We also found that overexpression of MCL1 or DEDD increased anchorage independence growth in vitro and increased experimental metastasis in vivo in the nonamplified urothelial carcinoma cell line, RT112. The expression of MCL1 confers resistance to a range of apoptosis inducers, while the expression of DEDD led to resistance to TNFα-induced apoptosis. These observations identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinoma.
Implications:
These studies identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinomas.
Data from Stemness Is Enhanced in Gastric Cancer by a SET/PP2A/E2F1 Axis
Authors: Enjoji Shuhei , Yabe Ryotaro , Tsuji Shunya , Yoshimura Kazuhiro , Kawasaki Hideyoshi , Sakurai Masashi , Sakai Yusuke , Takenouchi Hiroko , Yoshino Shigefumi , Hazama Shoichi , Nagano Hiroaki , Oshima Hiroko , Oshima Masanobu , Vitek Michael P. , Matsuura Tetsuya , Hippo Yoshitaka , Usui Tatsuya , Ohama Takashi , Sato Koichi
Published: March 2024

Abstract
Gastric cancer is the fifth most common malignancy and the third leading cause of cancer-related deaths worldwide. Chemotherapies against gastric cancer often fail, with cancer recurrence due potentially to the persistence of cancer stem cells. This unique subpopulation of cells in tumors possesses the ability to self-renew and dedifferentiate. These cancer stem cells are critical for initiation, maintenance, metastasis, and relapse of cancers; however, the molecular mechanisms supporting cancer stemness remain largely unknown. Increased kinase and decreased phosphatase activity are hallmarks of oncogenic signaling. Protein phosphatase 2A (PP2A) functions as a tumor-suppressor enzyme, and elevated levels of SET/I2PP2A, an endogenous PP2A protein inhibitor, are correlated with poor prognosis of several human cancers. Here, it was determined that SET expression was elevated in tumor tissue in a gastric cancer mouse model system, and SET expression was positively correlated with poor survival of human gastric cancer patients. Mechanistically, SET knockdown decreased E2F1 levels and suppressed the stemness of cancer cell lines. Immunoprecipitations show SET associated with the PP2A–B56 complex, and the B56 subunit interacted with the E2F1 transcription factor. Treatment of gastric cancer cells with the SET-targeting drug OP449 increased PP2A activity, decreased E2F1 protein levels, and suppressed stemness of cancer cells. These data indicate that a SET/PP2A/E2F1 axis regulates cancer cell stemness and is a potential target for gastric cancer therapy.

Implications: This study highlights the oncogenic role of SET/I2PP2A in gastric cancer and suggests that SET maintains cancer cell stemness by suppressing PP2A activity and stabilizing E2F1. Mol Cancer Res; 16(3); 554–63. ©2018 AACR.
Data from SREBF1 Activity Is Regulated by an AR/mTOR Nuclear Axis in Prostate Cancer
Authors: Audet-Walsh Étienne , Vernier Mathieu , Yee Tracey , Laflamme Chloé , Li Susan , Chen Yonghong , Giguère Vincent
Published: March 2024

Abstract
Reprogramming of cellular metabolism is an important feature of prostate cancer, including altered lipid metabolism. Recently, it was observed that the nuclear fraction of mTOR is essential for the androgen-mediated metabolic reprogramming of prostate cancer cells. Herein, it is demonstrated that the androgen receptor (AR) and mTOR bind to regulatory regions of sterol regulatory element-binding transcription factor 1 (SREBF1) to control its expression, whereas dual activation of these signaling pathways also promotes SREBF1 cleavage and its translocation to the nucleus. Consequently, SREBF1 recruitment to regulatory regions of its target genes is induced upon treatment with the synthetic androgen R1881, an effect abrogated upon inhibition of the mTOR signaling pathway. In turn, pharmacologic and genetic inhibition of SREBF1 activity impairs the androgen-mediated induction of the key lipogenic genes fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD1). Consistent with these observations, the expression of the SREBF1, FASN, and SCD1 genes is significantly correlated in human prostate cancer tumor clinical specimens. Functionally, blockade of SREBF1 activity reduces the androgen-driven lipid accumulation. Interestingly, decreased triglyceride accumulation observed upon SREBF1 inhibition is paralleled by an increase in mitochondrial respiration, indicating a potential rewiring of citrate metabolism in prostate cancer cells. Altogether, these data define an AR/mTOR nuclear axis, in the context of prostate cancer, as a novel pathway regulating SREBF1 activity and citrate metabolism.

Implications: The finding that an AR/mTOR complex promotes SREBF1 expression and activity enhances our understanding of the metabolic adaptation necessary for prostate cancer cell growth and suggests novel therapeutic approaches to target metabolic vulnerabilities in tumors. Mol Cancer Res; 16(9); 1396–405. ©2018 AACR.
Data from Interactions with Muscle Cells Boost Fusion, Stemness, and Drug Resistance of Prostate Cancer Cells
Authors: Uygur Berna , Leikina Evgenia , Melikov Kamran , Villasmil Rafael , Verma Santosh K. , Vary Calvin P.H. , Chernomordik Leonid V.
Published: March 2024

Abstract
Poorly understood interactions with nonmalignant cells within the tumor microenvironment play an important role in cancer progression. Here, we explored interactions between prostate cancer and muscle cells that surround the prostate. We found that coculturing of prostate cancer cells with skeletal or smooth muscle cells expands the subpopulations of cancer cells with features characteristic of cancer stem-like cells, including anchorage-independent growth, elevated CD133 expression, and drug resistance. These changes in the properties of cancer cells depend on: (i) the muscle cell–induced increases in the concentrations of interleukins 4 and 13; (ii) the cytokine-induced upregulation of the expression of syncytin 1 and annexin A5; and (iii) cancer cell fusion. In human prostate cancer tissues, expression of syncytin 1 and annexin A5, proteins that we found to be required for the cell fusion, positively correlated with the cancer development suggesting that these proteins can be used as biomarkers to evaluate cancer progression and potential therapeutic targets.
Implications:
The discovered effects of muscle cells on prostate cancer cells reveal a novel and specific pathway by which muscle cells in the microenvironment of prostate cancer cells promote cell fusion and cancer progression.
Data from β8 Integrin Mediates Pancreatic Cancer Cell Radiochemoresistance
Authors: Jin Sha , Lee Wei-Chun , Aust Daniela , Pilarsky Christian , Cordes Nils
Published: March 2024

Abstract
Pancreatic ductal adenocarcinoma (PDAC) stroma, composed of extracellular matrix (ECM) proteins, promotes therapy resistance and poor survival rate. Integrin-mediated cell/ECM interactions are well known to control cancer cell survival, proliferation, and therapy resistance. Here, we identified β8 integrin in a high-throughput knockdown screen in three-dimensional (3D), ECM-based cell cultures for novel focal adhesion protein targets as a critical determinant of PDAC cell radiochemoresistance. Intriguingly, β8 integrin localizes with the golgi apparatus perinuclearly in PDAC cells and resection specimen from PDAC patients. Upon radiogenic genotoxic injury, β8 integrin shows a microtubule-dependent perinuclear-to-cytoplasmic shift as well as strong changes in its proteomic interactome regarding the cell functions transport, catalysis, and binding. Parts of this interactome link β8 integrin to autophagy, which is diminished in the absence of β8 integrin. Collectively, our data reveal β8 integrin to critically coregulate PDAC cell radiochemoresistance, intracellular vesicle trafficking, and autophagy upon irradiation.
Implications:
This study identified β8 integrin as an essential determinant of PDAC cell radiochemosensitivity and as a novel potential cancer target.
Data from Cigarette Smoke Induces Metabolic Reprogramming of the Tumor Stroma in Head and Neck Squamous Cell Carcinoma
Authors: Domingo-Vidal Marina , Whitaker-Menezes Diana , Martos-Rus Cristina , Tassone Patrick , Snyder Christopher M. , Tuluc Madalina , Philp Nancy , Curry Joseph , Martinez-Outschoorn Ubaldo
Published: March 2024

Abstract
Head and neck squamous cell carcinoma (HNSCC) is comprised of metabolically linked distinct compartments. Cancer-associated fibroblasts (CAF) and nonproliferative carcinoma cells display a glycolytic metabolism, while proliferative carcinoma cells rely on mitochondrial oxidative metabolism fueled by the catabolites provided by the adjacent CAFs. Metabolic coupling between these reprogrammed compartments contributes to HNSCC aggressiveness. In this study, we examined the effects of cigarette smoke–exposed CAFs on metabolic coupling and tumor aggressiveness of HNSCC. Cigarette smoke (CS) extract was generated by dissolving cigarette smoke in growth media. Fibroblasts were cultured in CS or control media. HNSCC cells were cocultured in vitro and coinjected in vivo with CS or control fibroblasts. We found that CS induced oxidative stress, glycolytic flux and MCT4 expression, and senescence in fibroblasts. MCT4 upregulation was critical for fibroblast viability under CS conditions. The effects of CS on fibroblasts were abrogated by antioxidant treatment. Coculture of carcinoma cells with CS fibroblasts induced metabolic coupling with upregulation of the marker of glycolysis MCT4 in fibroblasts and markers of mitochondrial metabolism MCT1 and TOMM20 in carcinoma cells. CS fibroblasts increased CCL2 expression and macrophage migration. Coculture with CS fibroblasts also increased two features of carcinoma cell aggressiveness: resistance to cell death and enhanced cell migration. Coinjection of carcinoma cells with CS fibroblasts generated larger tumors with reduced apoptosis than control coinjections, and upregulation of MCT4 by CS exposure was a driver of these effects. We demonstrate that a tumor microenvironment exposed to CS is sufficient to modulate metabolism and cancer aggressiveness in HNSCC.
Implications:
CS shifts cancer stroma toward glycolysis and induces head and neck cancer aggressiveness with a mitochondrial profile linked by catabolite transporters and oxidative stress.
Visual Overview:
http://mcr.aacrjournals.org/content/molcanres/17/9/1893/F1.large.jpg.
Data from Genotoxic Damage Activates the AMPK-α1 Isoform in the Nucleus via Ca2+/CaMKK2 Signaling to Enhance Tumor Cell Survival
Authors: Vara-Ciruelos Diana , Dandapani Madhumita , Gray Alexander , Egbani Ejaife O. , Evans A. Mark , Hardie D. Grahame
Published: March 2024

Abstract
Many genotoxic cancer treatments activate AMP-activated protein kinase (AMPK), but the mechanisms of AMPK activation in response to DNA damage, and its downstream consequences, have been unclear. In this study, etoposide activates the α1 but not the α2 isoform of AMPK, primarily within the nucleus. AMPK activation is independent of ataxia-telangiectasia mutated (ATM), a DNA damage-activated kinase, and the principal upstream kinase for AMPK, LKB1, but correlates with increased nuclear Ca2+ and requires the Ca2+/calmodulin-dependent kinase, CaMKK2. Intriguingly, Ca2+-dependent activation of AMPK in two different LKB1-null cancer cell lines caused G1-phase cell-cycle arrest, and enhanced cell viability/survival after etoposide treatment, with both effects being abolished by knockout of AMPK-α1 and α2. The CDK4/6 inhibitor palbociclib also caused G1 arrest in G361 but not HeLa cells and, consistent with this, enhanced cell survival after etoposide treatment only in G361 cells. These results suggest that AMPK activation protects cells against etoposide by limiting entry into S-phase, where cells would be more vulnerable to genotoxic stress.

Implications: These results reveal that the α1 isoform of AMPK promotes tumorigenesis by protecting cells against genotoxic stress, which may explain findings that the gene encoding AMPK-α1 (but not -α2) is amplified in some human cancers. Furthermore, α1-selective inhibitors might enhance the anticancer effects of genotoxic-based therapies. Mol Cancer Res; 16(2); 345–57. ©2017 AACR.
Data from BRCA1 through Its E3 Ligase Activity Regulates the Transcription Factor Oct1 and Carbohydrate Metabolism
Authors: Vázquez-Arreguín Karina , Maddox Jessica , Kang Jinsuk , Park Dongju , Cano Reuben R. , Factor Rachel E. , Ludwig Thomas , Tantin Dean
Published: March 2024

Abstract
The tumor suppressor BRCA1 regulates the DNA damage response (DDR) and other processes that remain incompletely defined. Among these, BRCA1 heterodimerizes with BARD1 to ubiquitylate targets via its N-terminal E3 ligase activity. Here, it is demonstrated that BRCA1 promotes oxidative metabolism by degrading Oct1 (POU2F1), a transcription factor with proglycolytic and tumorigenic effects. BRCA1 E3 ubiquitin ligase mutation skews cells toward a glycolytic metabolic profile while elevating Oct1 protein. CRISPR-mediated Oct1 deletion reverts the glycolytic phenotype. RNA sequencing (RNAseq) confirms deregulation of metabolic genes downstream of Oct1. BRCA1 mediates Oct1 ubiquitylation and degradation, and mutation of two ubiquitylated Oct1 lysines insulates the protein against BRCA1-mediated destabilization. Oct1 deletion in MCF-7 breast cancer cells does not perturb growth in standard culture, but inhibits growth in soft agar and xenograft assays. In primary breast cancer clinical specimens, Oct1 protein levels correlate positively with tumor aggressiveness and inversely with BRCA1. These results identify BRCA1 as an Oct1 ubiquitin ligase that catalyzes Oct1 degradation to promote oxidative metabolism and restrict tumorigenicity. Mol Cancer Res; 16(3); 439–52. ©2018 AACR.
Data from EGFRvIII–Stat5 Signaling Enhances Glioblastoma Cell Migration and Survival
Authors: Roos Alison , Dhruv Harshil D. , Peng Sen , Inge Landon J. , Tuncali Serdar , Pineda Michael , Millard Nghia , Mayo Zachary , Eschbacher Jennifer M. , Loftus Joseph C. , Winkles Jeffrey A. , Tran Nhan L.
Published: March 2024

Abstract
Glioblastoma multiforme (GBM) is the most common brain malignancies in adults. Most GBM patients succumb to the disease less than 1 year after diagnosis due to the highly invasive nature of the tumor, which prevents complete surgical resection and gives rise to tumor recurrence. The invasive phenotype also confers radioresistant and chemoresistant properties to the tumor cells; therefore, there is a critical need to develop new therapeutics that target drivers of GBM invasion. Amplification of EGFR is observed in over 50% of GBM tumors, of which half concurrently overexpress the variant EGFRvIII, and expression of both receptors confers a worse prognosis. EGFR and EGFRvIII cooperate to promote tumor progression and invasion, in part, through activation of the Stat signaling pathway. Here, it is reported that EGFRvIII activates Stat5 and GBM invasion by inducing the expression of a previously established mediator of glioma cell invasion and survival: fibroblast growth factor-inducible 14 (Fn14). EGFRvIII-mediated induction of Fn14 expression is Stat5 dependent and requires activation of Src, whereas EGFR regulation of Fn14 is dependent upon Src–MEK/ERK–Stat3 activation. Notably, treatment of EGFRvIII-expressing GBM cells with the FDA-approved Stat5 inhibitor pimozide blocked Stat5 phosphorylation, Fn14 expression, and cell migration and survival. Because EGFR inhibitors display limited therapeutic efficacy in GBM patients, the EGFRvIII–Stat5–Fn14 signaling pathway represents a node of vulnerability in the invasive GBM cell populations.

Implications: Targeting critical effectors in the EGFRvIII–Stat5–Fn14 pathway may limit GBM tumor dispersion, mitigate therapeutic resistance, and increase survival. Mol Cancer Res; 16(7); 1185–95. ©2018 AACR.
Data from Notch Signaling Activation Is Associated with Patient Mortality and Increased FGF1-Mediated Invasion in Squamous Cell Carcinoma of the Oral Cavity
Authors: Weaver Alice N. , Burch M. Benjamin , Cooper Tiffiny S. , Della Manna Deborah L. , Wei Shi , Ojesina Akinyemi I. , Rosenthal Eben L. , Yang Eddy S.
Published: March 2024

Abstract
Oral squamous cell carcinoma (OSCC) is a cancer subtype that lacks validated prognostic and therapeutic biomarkers, and human papillomavirus status has not proven beneficial in predicting patient outcomes. A gene expression pathway analysis was conducted using OSCC patient specimens to identify molecular targets that may improve management of this disease. RNA was isolated from 19 OSCCs treated surgically at the University of Alabama at Birmingham (UAB; Birmingham, AL) and evaluated using the NanoString nCounter system. Results were confirmed using the oral cavity subdivision of the Head and Neck Squamous Cell Carcinoma Cancer (HNSCC) study generated by The Cancer Genome Atlas (TCGA) Research Network. Further characterization of the in vitro phenotype produced by Notch pathway activation in HNSCC cell lines included gene expression, proliferation, cell cycle, migration, invasion, and radiosensitivity. In both UAB and TCGA samples, Notch pathway upregulation was significantly correlated with patient mortality status and with expression of the proinvasive gene FGF1. In vitro Notch activation in HNSCC cells increased transcription of FGF1 and induced a marked increase in cell migration and invasion, which was fully abrogated by FGF1 knockdown. These results reveal that increased Notch pathway signaling plays a role in cancer progression and patient outcomes in OSCC. Accordingly, the Notch–FGF interaction should be further studied as a prognostic biomarker and potential therapeutic target for OSCC.

Implications: Patients with squamous cell carcinoma of the oral cavity who succumb to their disease are more likely to have upregulated Notch signaling, which may mediate a more invasive phenotype through increased FGF1 transcription. Mol Cancer Res; 14(9); 883–91. ©2016 AACR.
Data from Snail Cooperates with KrasG12D In Vivo to Increase Stem Cell Factor and Enhance Mast Cell Infiltration
Authors: Knab Lawrence M. , Ebine Kazumi , Chow Christina R. , Raza Sania S. , Sahai Vaibhav , Patel Akash P. , Kumar Krishan , Bentrem David J. , Grippo Paul J. , Munshi Hidayatullah G.
Published: March 2024

Abstract
Pancreatic ductal adenocarcinoma (PDAC) is associated with a pronounced fibro-inflammatory stromal reaction that contributes to tumor progression. A critical step in invasion and metastasis is the epithelial-to-mesenchymal transition (EMT), which can be regulated by the Snail family of transcription factors. Overexpression of Snail (Snai1) and mutant KrasG12D in the pancreas of transgenic mice, using an elastase (EL) promoter, resulted in fibrosis. To identify how Snail modulates inflammation in the pancreas, we examined the effect of expressing Snail in EL-KrasG12D mice (KrasG12D/Snail) on mast cell infiltration, which has been linked to PDAC progression. Using this animal model system, it was demonstrated that there are increased numbers of mast cells in the pancreas of KrasG12D/Snail mice compared with control KrasG12D mice. In addition, it was revealed that human primary PDAC tumors with increased Snail expression are associated with increased mast cell infiltration, and that Snail expression in these clinical specimens positively correlated with the expression of stem cell factor (SCF/KITLG), a cytokine known to regulate mast cell migration. Concomitantly, SCF levels are increased in the KrasG12D/Snail mice than in control mice. Moreover, overexpression of Snail in PDAC cells increased SCF levels, and the media conditioned by Snail-expressing PDAC cells promoted mast cell migration. Finally, inhibition of SCF using a neutralizing antibody significantly attenuated Snail-induced migration of mast cells.

Implications: Together, these results elucidate how the EMT regulator Snail contributes to inflammation associated with PDAC tumors. Mol Cancer Res; 12(10); 1440–8. ©2014 AACR.
Data from The Activation of MEK/ERK Signaling Pathway by Bone Morphogenetic Protein 4 to Increase Hepatocellular Carcinoma Cell Proliferation and Migration
Authors: Chiu Chiang-Yen , Kuo Kung-Kai , Kuo Tzu-Lei , Lee King-The , Cheng Kuang-Hung
Published: March 2024

Abstract
Hepatocellular carcinoma (HCC) is one of the most common visceral malignancies worldwide, with a very high incidence and poor prognosis. Bone morphogenesis protein 4 (BMP4), which belongs to the TGF-β superfamily of proteins, is a multifunctional cytokine, which exerts its biologic effects through SMAD- and non-SMAD-dependent pathways, and is also known to be involved in human carcinogenesis. However, the effects of the BMP4 signaling in liver carcinogenesis are not yet clearly defined. Here, we first show that BMP4 and its receptor, BMPR1A, are overexpressed in a majority of primary HCCs and that it promotes the growth and migration of HCC cell lines in vitro. We also establish that BMP4 can induce HCC cyclin-dependent kinase (CDK)1 and cyclin B1 upregulation to accelerate cell-cycle progression. Our study indicates that the induction of HCC cell proliferation is independent of the SMAD signaling pathway, as Smad4 knockdown of HCC cell lines still leads to the upregulation of CDK1 and cyclin B1 expression after BMP4 treatment. Using mitogen-activated protein/extracellular signal-regulated kinase (MEK) selective inhibitors, the induction of CDK1, cyclin B1 mRNA and protein were shown to be dependent on the activation of MEK/extracellular signal-regulated kinase (ERK) signaling. In vivo xenograft studies confirmed that the BMPR1A-knockdown cells were significantly less tumorigenic than the control groups. Our findings show that the upregulation of BMP4 and BMPR1A in HCC promotes the proliferation and metastasis of HCC cells and that CDK1 and cyclin B1 are important SMAD-independent molecular targets in BMP4 signaling pathways, during the HCC tumorigenesis. It is proposed that BMP4 signaling pathways may have potential as new therapeutic targets in HCC treatment. Mol Cancer Res; 10(3); 415–27. ©2012 AACR.
Data from Establishment of the First Well-differentiated Human Pancreatic Neuroendocrine Tumor Model
Authors: Benten Daniel , Behrang Yasmin , Unrau Ludmilla , Weissmann Victoria , Wolters-Eisfeld Gerrit , Burdak-Rothkamm Susanne , Stahl Felix R. , Anlauf Martin , Grabowski Patricia , Möbs Markus , Dieckhoff Jan , Sipos Bence , Fahl Martina , Eggers Corinna , Perez Daniel , Bockhorn Maximillian , Izbicki Jakob R. , Lohse Ansgar W. , Schrader Jörg
Published: March 2024

Abstract
Clinical options for systemic therapy of neuroendocrine tumors (NET) are limited. Development of new drugs requires suitable representative in vitro and in vivo model systems. So far, the unavailability of a human model with a well-differentiated phenotype and typical growth characteristics has impaired preclinical research in NET. Herein, we establish and characterize a lymph node–derived cell line (NT-3) from a male patient with well-differentiated pancreatic NET. Neuroendocrine differentiation and tumor biology was compared with existing NET cell lines BON and QGP-1. In vivo growth was assessed in a xenograft mouse model. The neuroendocrine identity of NT-3 was verified by expression of multiple NET-specific markers, which were highly expressed in NT-3 compared with BON and QGP-1. In addition, NT-3 expressed and secreted insulin. Until now, this well-differentiated phenotype is stable since 58 passages. The proliferative labeling index, measured by Ki-67, of 14.6% ± 1.0% in NT-3 is akin to the original tumor (15%–20%), and was lower than in BON (80.6% ± 3.3%) and QGP-1 (82.6% ± 1.0%). NT-3 highly expressed somatostatin receptors (SSTRs: 1, 2, 3, and 5). Upon subcutaneous transplantation of NT-3 cells, recipient mice developed tumors with an efficient tumor take rate (94%) and growth rate (139% ± 13%) by 4 weeks. Importantly, morphology and neuroendocrine marker expression of xenograft tumors resembled the original human tumor.

Implications: High expression of somatostatin receptors and a well-differentiated phenotype as well as a slow growth rate qualify the new cell line as a relevant model to study neuroendocrine tumor biology and to develop new tumor treatments. Mol Cancer Res; 16(3); 496–507. ©2018 AACR.
Data from IGF2 Autocrine-Mediated IGF1R Activation Is a Clinically Relevant Mechanism of Osimertinib Resistance in Lung Cancer
Authors: Manabe Tadashi , Yasuda Hiroyuki , Terai Hideki , Kagiwada Harumi , Hamamoto Junko , Ebisudani Toshiki , Kobayashi Keigo , Masuzawa Keita , Ikemura Shinnosuke , Kawada Ichiro , Hayashi Yuichiro , Fukui Kazuhiko , Horimoto Katsuhisa , Fukunaga Koichi , Soejima Kenzo
Published: March 2024

Abstract
EGFR-mutated lung cancer accounts for a significant proportion of lung cancer cases worldwide. For these cases, osimertinib, a third-generation EGFR tyrosine kinase inhibitor, is extensively used as a first-line or second-line treatment. However, lung cancer cells acquire resistance to osimertinib in 1 to 2 years. Thus, a thorough clarification of resistance mechanisms to osimertinib is highly anticipated. Recent next-generation sequencing (NGS) of lung cancer samples identified several genetically defined resistance mechanisms to osimertinib, such as EGFR C797S or MET amplification. However, nongenetically defined mechanisms are not well evaluated. For a thorough clarification of osimertinib resistance, both genetic and nongenetic mechanisms are essential. By using our comprehensive protein phosphorylation array, we detected IGF1R bypass pathway activation after EGFR abolishment. Both of our established lung cancer cells and patient-derived lung cancer cells demonstrated IGF2 autocrine-mediated IGF1R pathway activation as a mechanism of osimertinib resistance. Notably, this resistance mechanism was not detected by a previously performed NGS, highlighting the essential roles of living cancer cells for a thorough clarification of resistance mechanisms. Interestingly, the immunohistochemical analysis confirmed the increased IGF2 expression in lung cancer patients who were treated with osimertinib and met the established clinical definition of acquired resistance. The findings highlight the crucial roles of cell-autonomous ligand expression in osimertinib resistance. Here, we report for the first time the IGF2 autocrine-mediated IGF1R activation as a nongenetic mechanism of osimertinib resistance in lung cancer at a clinically relevant level.
Implications:
Using comprehensive protein phosphorylation array and patient-derived lung cancer cells, we found that IGF2 autocrine-mediated IGF1R pathway activation is a clinically relevant and common mechanism of acquired resistance to osimertinib.
Data from Ligand Binding Promotes CDK-Dependent Phosphorylation of ER-Alpha on Hinge Serine 294 but Inhibits Ligand-Independent Phosphorylation of Serine 305
Authors: Held Jason M. , Britton David J. , Scott Gary K. , Lee Elbert L. , Schilling Birgit , Baldwin Michael A. , Gibson Bradford W. , Benz Christopher C.
Published: March 2024

Abstract
Phosphorylation of estrogen receptor-α (ERα) is critical for its transcription factor activity and may determine its predictive and therapeutic value as a biomarker for ERα-positive breast cancers. Recent attention has turned to the poorly understood ERα hinge domain, as phosphorylation at serine 305 (Ser305) associates with poor clinical outcome and endocrine resistance. We show that phosphorylation of a neighboring hinge domain site, Ser294, analyzed by multiple reaction monitoring mass spectrometry of ERα immunoprecipitates from human breast cancer cells is robustly phosphorylated exclusively by ligand (estradiol and tamoxifen) activation of ERα and not by growth factor stimulation (EGF, insulin, heregulin-β). In a reciprocal fashion, Ser305 phosphorylation is induced by growth factors but not ligand activation of ERα. Phosphorylation at Ser294 and Ser305 is suppressed upon co-stimulation by EGF and ligand, respectively, unlike the N-terminal (AF-1) domain Ser118 and Ser167 sites of ERα where phosphorylation is enhanced by ligand and growth factor co-stimulation. Inhibition of cyclin-dependent kinases (CDK) by roscovitine or SNS-032 suppresses ligand-activated Ser294 phosphorylation without affecting Ser118 or Ser104/Ser106 phosphorylation. Likewise, cell-free studies using recombinant ERα and specific cyclin–CDK complexes suggest that Ser294 phosphorylation is primarily induced by the transcription-regulating and cell-cycle–independent kinase CDK7. Thus, CDK-dependent phosphorylation at Ser294 differentiates ligand-dependent from ligand-independent activation of Ser305 phosphorylation, showing that hinge domain phosphorylation patterns uniquely inform on the various ERα activation mechanisms thought to underlie the biologic and clinical diversity of hormone-dependent breast cancers. Mol Cancer Res; 10(8); 1120–32. ©2012 AACR.
Data from Fibroblast Growth Factor-2 Is an Important Factor that Maintains Cellular Immaturity and Contributes to Aggressiveness of Osteosarcoma
Authors: Shimizu Takatsune , Ishikawa Tomoki , Iwai Sayaka , Ueki Arisa , Sugihara Eiji , Onishi Nobuyuki , Kuninaka Shinji , Miyamoto Takeshi , Toyama Yoshiaki , Ijiri Hiroshi , Mori Hajime , Matsuzaki Yumi , Yaguchi Tomonori , Nishio Hiroshi , Kawakami Yutaka , Ikeda Yasuo , Saya Hideyuki
Published: March 2024

Abstract
Osteosarcoma is the most frequent, nonhematopoietic, primary malignant tumor of bone. Histopathologically, osteosarcoma is characterized by complex mixtures of different cell types with bone formation. The role of environmental factors in the formation of such a complicated tissue structure as osteosarcoma remains to be elucidated. Here, a newly established murine osteosarcoma model was used to clarify the roles of environmental factors such as fibroblast growth factor-2 (Fgf2) or leukemia-inhibitory factor (Lif) in the maintenance of osteosarcoma cells in an immature state. These factors were highly expressed in tumor environmental stromal cells, rather than in osteosarcoma cells, and they potently suppressed osteogenic differentiation of osteosarcoma cells in vitro and in vivo. Further investigation revealed that the hyperactivation of extracellular signal–regulated kinase (Erk)1/2 induced by these factors affected in the process of osteosarcoma differentiation. In addition, Fgf2 enhanced both proliferation and migratory activity of osteosarcoma cells and modulated the sensitivity of cells to an anticancer drug. The results of the present study suggest that the histology of osteosarcoma tumors which consist of immature tumor cells and pathologic bone formations could be generated dependent on the distribution of such environmental factors. The combined blockade of the signaling pathways of several growth factors, including Fgf2, might be useful in controlling the aggressiveness of osteosarcoma. Mol Cancer Res; 10(3); 454–68. ©2012 AACR.
Data from Enhanced Tumorigenic Potential of Colorectal Cancer Cells by Extracellular Sulfatases
Authors: Vicente Carolina M. , Lima Marcelo A. , Yates Edwin A. , Nader Helena B. , Toma Leny
Published: March 2024

Abstract
Heparan sulfate endosulfatase-1 and -2 (SULF1 and SULF2) are two important extracellular 6-O-endosulfatases that remove 6-O sulfate groups of N-glucosamine along heparan sulfate (HS) proteoglycan chains often found in the extracellular matrix. The HS sulfation pattern influences signaling events at the cell surface, which are critical for interactions with growth factors and their receptors. SULFs are overexpressed in several types of human tumors, but their role in cancer is still unclear because their molecular mechanism has not been fully explored and understood. To further investigate the functions of these sulfatases in tumorigenesis, stable overexpression models of these genes were generated in the colorectal cancer cells, Caco-2 and HCT-116. Importantly, mimicking overexpression of these sulfatases resulted in increased viability and proliferation, and augmented cell migration. These effects were reverted by shRNA-mediated knockdown of SULF1 or SULF2 and by the addition of unfractionated heparin. Detailed structural analysis of HS from cells overexpressing SULFs showed reduction in the trisulfated disaccharide UA(2S)-GlcNS(6S) and corresponding increase in UA(2S)-GlcNS disaccharide, as well as an unexpected rise in less common disaccharides containing GlcNAc(6S) residues. Moreover, cancer cells transfected with SULFs demonstrated increased Wnt signaling. In summary, SULF1 or SULF2 overexpression contributes to colorectal cancer cell proliferation, migration, and invasion.

Implications: This study reveals that sulfatases have oncogenic effects in colon cancer cells, suggesting an important role for these enzymes in cancer progression. Mol Cancer Res; 13(3); 510–23. ©2014 AACR.
Data from Regulation of Inflammatory Breast Cancer Cell Invasion through Akt1/PKBα Phosphorylation of RhoC GTPase
Authors: Lehman Heather L. , Van Laere Steven J. , van Golen Cynthia M. , Vermeulen Peter B. , Dirix Luc Y. , van Golen Kenneth L.
Published: March 2024

Abstract
With a 42% and 18% 5- and 10-year respective disease-free survival rate, inflammatory breast cancer (IBC) is arguably the deadliest form of breast cancer. IBC invades the dermal lymphatic vessels of the skin overlying the breast and as a consequence nearly all women have lymph node involvement and ∼1/3 have gross distant metastases at the time of diagnosis. One year after diagnosis ∼90% of patients have detectable metastases, making IBC a paradigm for lymphovascular invasion. Understanding the underlying mechanisms of the IBC metastatic phenotype is essential for new therapies. Work from our laboratory and others show distinct molecular differences between IBC and non-IBCs (nIBCs). Previously we showed that RhoC GTPase is a metastatic switch responsible for the invasive phenotype of IBC. In this study we integrate observations made in IBC patients with in vitro analysis. We show that the PI3K/Akt signaling pathway is crucial in IBC invasion. Key molecules involved in cytoskeletal control and cell motility are specifically upregulated in IBC patients compared with stage and cell-type-of-origin matched nIBCs patients. Distinctively, RhoC GTPase is a substrate for Akt1 and its phosphorylation is absolutely essential for IBC cell invasion. Further our data show that Akt3, not Akt1 has a role in IBC cell survival. Together our data show a unique and targetable pathway for IBC invasion and survival. Mol Cancer Res; 10(10); 1306–18. ©2012 AACR.
Data from Chk1-Dependent Constitutive Phosphorylation of BLM Helicase at Serine 646 Decreases after DNA Damage
Authors: Kaur Sarabpreet , Modi Priyanka , Srivastava Vivek , Mudgal Richa , Tikoo Shweta , Arora Prateek , Mohanty Debasisa , Sengupta Sagar
Published: March 2024

Abstract
BLM helicase, the protein mutated in Bloom syndrome, is involved in signal transduction cascades after DNA damage. BLM is phosphorylated on multiple residues by different kinases either after stress induction or during mitosis. Here, we have provided evidence that both Chk1 and Chk2 phosphorylated the NH2-terminal 660 amino acids of BLM. An internal region within the DExH motif of BLM negatively regulated the Chk1/Chk2-dependent NH2-terminal phosphorylation event. Using in silico analysis involving the Chk1 structure and its known substrate specificity, we predicted that Chk1 should preferentially phosphorylate BLM on serine 646 (Ser646). The prediction was validated in vitro by phosphopeptide analysis on BLM mutants and in vivo by usage of a newly generated phosphospecific polyclonal antibody. We showed that the phosphorylation at Ser646 on BLM was constitutive and decreased rapidly after exposure to DNA damage. This resulted in the diminished interaction of BLM with nucleolin and PML isoforms, and consequently decreased BLM accumulation in the nucleolus and PML nuclear bodies. Instead, BLM relocalized to the sites of DNA damage and bound with the damage sensor protein, Nbs1. Mutant analysis confirmed that the binding to nucleolin and PML isoforms required Ser646 phosphorylation. These results indicated that Chk1-mediated phosphorylation on BLM at Ser646 might be a determinant for regulating subnuclear localization and could act as a marker for the activation status of BLM in response to DNA damage. Mol Cancer Res; 8(9); 1234–47. ©2010 AACR.
Data from The Retinoblastoma Protein Tumor Suppressor Is Important for Appropriate Osteoblast Differentiation and Bone Development
Authors: Berman Seth D. , Yuan Tina L. , Miller Emily S. , Lee Eunice Y. , Caron Alicia , Lees Jacqueline A.
Published: March 2024

Abstract
Mutation of the retinoblastoma (RB) tumor suppressor gene is strongly linked to osteosarcoma formation. This observation and the documented interaction between the retinoblastoma protein (pRb) and Runx2 suggests that pRb is important in bone development. To assess this hypothesis, we used a conditional knockout strategy to generate pRb-deficient embryos that survive to birth. Analysis of these embryos shows that Rb inactivation causes the abnormal development and impaired ossification of several bones, correlating with an impairment in osteoblast differentiation. We further show that Rb inactivation acts to promote osteoblast differentiation in vitro and, through conditional analysis, establish that this occurs in a cell-intrinsic manner. Although these in vivo and in vitro differentiation phenotypes seem paradoxical, we find that Rb-deficient osteoblasts have an impaired ability to exit the cell cycle both in vivo and in vitro that can explain the observed differentiation defects. Consistent with this observation, we show that the cell cycle and the bone defects in Rb-deficient embryos can be suppressed by deletion of E2f1, a known proliferation inducer that acts downstream of Rb. Thus, we conclude that pRb plays a key role in regulating osteoblast differentiation by mediating the inhibition of E2F and consequently promoting cell cycle exit. (Mol Cancer Res 2008;6(9):1440–51)
Data from Targeting Epidermal Growth Factor Receptor–Associated Signaling Pathways in Non–Small Cell Lung Cancer Cells: Implication in Radiation Response
Authors: Choi Eun Jung , Ryu Yun Kyeong , Kim So Yeon , Wu Hong Gyun , Kim Jae Sung , Kim Il Han , Kim In Ah
Published: March 2024

Abstract
Several studies have shown solid evidence for the potential value of targeting epidermal growth factor receptor (EGFR) signaling to enhance the antitumor activity of radiation. However, therapeutic resistance has emerged as an important clinical issue. Here, we investigated whether strategies for targeting EGFR-associated downstream signaling would radiosensitize a panel of non–small cell lung cancer cell lines. Inhibition of K-RAS using RNA interference attenuated downstream signaling and increased radiosensitivity of A549 and H460 cells, whereas inhibition of EGFR did not. A549 cells harboring a K-RAS mutation at codon V12 were radiosensitized by small interfering RNA (siRNA) targeting this codon. H460 cells having mutation at codon V61 was radiosensitized by siRNA targeting of this mutation. K-RAS siRNA did not radiosensitize H1299 cells possessing wild-type K-RAS. Inhibition of the phosphoinositide 3-kinase (PI3K)-AKT-mammalian target of rapamycin pathway led to significant radiosensitization of the two cell lines, whereas selective inhibition of extracellular signal-regulated kinase signaling did not. Inhibitors targeting the PI3K-AKT-mTOR pathway also abrogated G2 arrest following irradiation and induced γH2AX foci formation. A dual inhibitor of class I PI3K and mammalian target of rapamycin effectively increased the radiosensitivity of A549 and H460 cells. Inhibition of PI3K-AKT signaling was associated with the downregulation of DNA-PKs. Although apoptosis was the primary mode of cell death when cells were pretreated with LY294002 or AKT inhibitor VIII, cells pretreated with rapamycin or PI-103 showed mixed modes of cell death, including apoptosis and autophagy. Our results suggest possible mechanisms for counteracting EGFR prosurvival signaling implicated in radioresistance and offer an alternative strategy for overcoming resistance to EGFR inhibitors used in combination with irradiation. Mol Cancer Res; 8(7); 1027–36. ©2010 AACR.
Data from Relaxin Enhances S100A4 and Promotes Growth of Human Thyroid Carcinoma Cell Xenografts
Authors: Radestock Yvonne , Willing Cornelia , Kehlen Astrid , Hoang-Vu Cuong , Hombach-Klonisch Sabine
Published: March 2024

Abstract
Relaxin increases cell motility and in vitro invasiveness in human thyroid carcinoma cells but the underlying molecular mechanisms of this action are largely unknown. In the present study, we show that relaxin transcriptionally upregulates the calcium-binding protein S100A4 (metastasin) and increases the cytosolic 10-kDa monomer and the 20-kDa dimer form of S100A4 in human thyroid carcinoma cells. The relaxin-induced increase in cell motility was blocked completely when S100A4 expression was diminished using an S100A4 small interfering RNA knockdown approach. We have shown previously the expression of the insulin-like family member relaxin in human thyroid carcinoma tissues but not in benign thyroid tissues. Human thyroid carcinoma tissues expressing relaxin also stained positive for S100A4. In nude mouse experiments, human thyroid carcinoma cell transfectants with constitutive expression of relaxin generated large and fast-growing tumors with significantly increased numbers of proliferating cells. We provide evidence in our cell model that the relaxin target protein S100A4 secreted by the thyroid carcinoma transfectants may not only enhance tumor cell motility but also promote xenograft angiogenesis as determined by the higher density of tumor microvessels and the angiogenic potential of S100A4 in in vitro tube formation assays. In conclusion, we have identified S100A4 as a major mediator of the actions of relaxin in thyroid carcinoma cell motility and in vivo thyroid tumor angiogenesis. Mol Cancer Res; 8(4); 494–506. ©2010 AACR.
Data from The Identification of MicroRNAs in a Genomically Unstable Region of Human Chromosome 8q24
Authors: Huppi Konrad , Volfovsky Natalia , Runfola Timothy , Jones Tamara L. , Mackiewicz Mark , Martin Scott E. , Mushinski J. Frederic , Stephens Robert , Caplen Natasha J.
Published: March 2024

Abstract
The PVT1 locus is identified as a cluster of T(2;8) and T(8;22) “variant” MYC-activating chromosomal translocation breakpoints extending 400 kb downstream of MYC in a subset (≈20%) of Burkitt's lymphoma (vBL). Recent reports that microRNAs (miRNA) may be associated with fragile sites and cancer-associated genomic regions prompted us to investigate whether the PVT1 region on chromosome 8q24 may contain miRNAs. Computational analysis of the genomic sequence covering the PVT1 locus and experimental verification identified seven miRNAs. One miRNA, hsa-miR-1204, resides within a previously described PVT1 exon (1b) that is often fused to the immunoglobulin light chain constant region in vBLs and is present in high copy number in MYC/PVT1–amplified tumors. Like its human counterpart, mouse mmu-miR-1204 represents the closest miRNA to Myc (∼50 kb) and is found only 1 to 2 kb downstream of a cluster of retroviral integration sites. Another miRNA, mmu-miR-1206, is close to a cluster of variant translocation breakpoints associated with mouse plasmacytoma and exon 1 of mouse Pvt1. Virtually all the miRNA precursor transcripts are expressed at higher levels in late-stage B cells (including plasmacytoma and vBL cell lines) compared with immature B cells, suggesting possible roles in lymphoid development and/or lymphoma. In addition, lentiviral vector-mediated overexpression of the miR-1204 precursor (human and mouse) in a mouse pre–B-cell line increased expression of Myc. High levels of expression of the hsa-miR-1204 precursor is also seen in several epithelial cancer cell lines with MYC/PVT1 coamplification, suggesting a potentially broad role for these miRNAs in tumorigenesis. (Mol Cancer Res 2008;6(2):212–21)