miR-33a promotes glioma-initiating cell self-renewal via PKA and NOTCH pathways

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Abstract

Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Glioma-initiating cells (GICs) are stem-like cells that have been implicated in glioblastoma progression and recurrence; however, the distinct properties of GICs and non-GICs within GBM tumors are largely uncharacterized. Here, we evaluated stem cell–associated microRNA (miR) expression in GICs from GBM patients and GICs derived from xenografted human glioma cell lines and determined that miR-33a promotes GIC growth and self-renewal. Moreover, evaluation of a GBM tissue array revealed that higher miR-33a expression was associated with poor prognosis of GBM patients. Antagonizing miR-33a function in GICs reduced self-renewal and tumor progression in immune-compromised mice, whereas overexpression of miR-33a in non-GICs promoted the display of features associated with GICs. We identified the mRNAs encoding phosphodiesterase 8A (PDE8A) and UV radiation resistance–associated gene (UVRAG) as direct miR-33a targets. PDE8A and UVRAG negatively regulated the cAMP/PKA and NOTCH pathways, respectively; therefore, miR-33a–dependent reduction of these proteins promoted growth and self-renewal of GICs by enhancing PKA and NOTCH activity. Furthermore, in GBM specimens, there was an inverse correlation between the expression levels of miR-33a and PDE8A and UVRAG expression. These findings reveal a miR-33a–centered signaling network that promotes GIC maintenance and has potential as a therapeutic target for GBM treatment.

Authors

Hui Wang, Tao Sun, Jing Hu, Rui Zhang, Yanhua Rao, Shuai Wang, Rui Chen, Roger E. McLendon, Allan H. Friedman, Stephen T. Keir, Darell D. Bigner, Qi-Jing Li, Huibo Wang, Xiao-Fan Wang

Development and translational imaging of a TP53 porcine tumorigenesis model

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Abstract

Cancer is the second deadliest disease in the United States, necessitating improvements in tumor diagnosis and treatment. Current model systems of cancer are informative, but translating promising imaging approaches and therapies to clinical practice has been challenging. In particular, the lack of a large-animal model that accurately mimics human cancer has been a major barrier to the development of effective diagnostic tools along with surgical and therapeutic interventions. Here, we developed a genetically modified porcine model of cancer in which animals express a mutation in TP53 (which encodes p53) that is orthologous to one commonly found in humans (R175H in people, R167H in pigs). TP53^R167H/R167H mutant pigs primarily developed lymphomas and osteogenic tumors, recapitulating the tumor types observed in mice and humans expressing orthologous TP53 mutant alleles. CT and MRI imaging data effectively detected developing tumors, which were validated by histopathological evaluation after necropsy. Molecular genetic analyses confirmed that these animals expressed the R167H mutant p53, and evaluation of tumors revealed characteristic chromosomal instability. Together, these results demonstrated that TP53^R167H/R167H pigs represent a large-animal tumor model that replicates the human condition. Our data further suggest that this model will be uniquely suited for developing clinically relevant, noninvasive imaging approaches to facilitate earlier detection, diagnosis, and treatment of human cancers.

Authors

Jessica C. Sieren, David K. Meyerholz, Xiao-Jun Wang, Bryan T. Davis, John D. Newell Jr., Emily Hammond, Judy A. Rohret, Frank A. Rohret, Jason T. Struzynski, J. Adam Goeken, Paul W. Naumann, Mariah R. Leidinger, Agshin Taghiyev, Richard Van Rheeden, Jussara Hagen, Benjamin W. Darbro, Dawn E. Quelle, Christopher S. Rogers

Arachidonate 15-lipoxygenase is required for chronic myeloid leukemia stem cell survival

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Abstract

Cancer stem cells (CSCs) are responsible for the initiation and maintenance of some types of cancer, suggesting that inhibition of these cells may limit disease progression and relapse. Unfortunately, few CSC-specific genes have been identified. Here, we determined that the gene encoding arachidonate 15-lipoxygenase (Alox15/15-LO) is essential for the survival of leukemia stem cells (LSCs) in a murine model of BCR-ABL–induced chronic myeloid leukemia (CML). In the absence of Alox15, BCR-ABL was unable to induce CML in mice. Furthermore, Alox15 deletion impaired LSC function by affecting cell division and apoptosis, leading to an eventual depletion of LSCs. Moreover, chemical inhibition of 15-LO function impaired LSC function and attenuated CML in mice. The defective CML phenotype in Alox15-deficient animals was rescued by depleting the gene encoding P-selectin, which is upregulated in Alox15-deficient animals. Both deletion and overexpression of P-selectin affected the survival of LSCs. In human CML cell lines and CD34⁺ cells, knockdown of Alox15 or inhibition of 15-LO dramatically reduced survival. Loss of Alox15 altered expression of PTEN, PI3K/AKT, and the transcription factor ICSBP, which are known mediators of cancer pathogenesis. These results suggest that ALOX15 has potential as a therapeutic target for eradicating LSCs in CML.

Authors

Yaoyu Chen, Cong Peng, Sheela A. Abraham, Yi Shan, Zhiru Guo, Ngoc Desouza, Giulia Cheloni, Dongguang Li, Tessa L. Holyoake, Shaoguang Li

Sexually dimorphic RB inactivation underlies mesenchymal glioblastoma prevalence in males

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Abstract

The prevalence of brain tumors in males is common but unexplained. While sex differences in disease are typically mediated through acute sex hormone actions, sex-specific differences in brain tumor rates are comparable at all ages, suggesting that factors other than sex hormones underlie this discrepancy. We found that mesenchymal glioblastoma (Mes-GBM) affects more males as the result of cell-intrinsic sexual dimorphism in astrocyte transformation. We used astrocytes from neurofibromin-deficient (Nf1^–/–) mice expressing a dominant-negative form of the tumor suppressor p53 (DNp53) and treated them with EGF as a Mes-GBM model. Male Mes-GBM astrocytes exhibited greater growth and colony formation compared with female Mes-GBM astrocytes. Moreover, male Mes-GBM astrocytes underwent greater tumorigenesis in vivo, regardless of recipient mouse sex. Male Mes-GBM astrocytes exhibited greater inactivation of the tumor suppressor RB, higher proliferation rates, and greater induction of a clonogenic, stem-like cell population compared with female Mes-GBM astrocytes. Furthermore, complete inactivation of RB and p53 in Mes-GBM astrocytes resulted in equivalent male and female tumorigenic transformation, indicating that intrinsic differences in RB activation are responsible for the predominance of tumorigenic transformation in male astrocytes. Together, these results indicate that cell-intrinsic sex differences in RB regulation and stem-like cell function may underlie the predominance of GBM in males.

Authors

Tao Sun, Nicole M. Warrington, Jingqin Luo, Michael D. Brooks, Sonika Dahiya, Steven C. Snyder, Rajarshi Sengupta, Joshua B. Rubin

Ion channel TRPV1-dependent activation of PTP1B suppresses EGFR-associated intestinal tumorigenesis

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Abstract

The intestinal epithelium has a high rate of turnover, and dysregulation of pathways that regulate regeneration can lead to tumor development; however, the negative regulators of oncogenic events in the intestinal epithelium are not fully understood. Here we identified a feedback loop between the epidermal growth factor receptor (EGFR), a known mediator of proliferation, and the transient receptor potential cation channel, subfamily V, member 1 (TRPV1), in intestinal epithelial cells (IECs). We found that TRPV1 was expressed by IECs and was intrinsically activated upon EGFR stimulation. Subsequently, TRPV1 activation inhibited EGFR-induced epithelial cell proliferation via activation of Ca²⁺/calpain and resulting activation of protein tyrosine phosphatase 1B (PTP1B). In a murine model of multiple intestinal neoplasia (Apc^Min/+ mice), TRPV1 deficiency increased adenoma formation, and treatment of these animals with an EGFR kinase inhibitor reversed protumorigenic phenotypes, supporting a functional association between TRPV1 and EGFR signaling in IECs. Administration of a TRPV1 agonist suppressed intestinal tumorigenesis in Apc^Min/+ mice, similar to — as well as in conjunction with — a cyclooxygenase-2 (COX-2) inhibitor, which suggests that targeting both TRPV1 and COX-2 has potential as a therapeutic approach for tumor prevention. Our findings implicate TRPV1 as a regulator of growth factor signaling in the intestinal epithelium through activation of PTP1B and subsequent suppression of intestinal tumorigenesis.

Authors

Petrus R. de Jong, Naoki Takahashi, Alexandra R. Harris, Jihyung Lee, Samuel Bertin, James Jeffries, Michael Jung, Jen Duong, Amy I. Triano, Jongdae Lee, Yaron Niv, David S. Herdman, Koji Taniguchi, Chang-Whan Kim, Hui Dong, Lars Eckmann, Stephanie M. Stanford, Nunzio Bottini, Maripat Corr, Eyal Raz

DEAD-box helicase DP103 defines metastatic potential of human breast cancers

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Abstract

Despite advancement in breast cancer treatment, 30% of patients with early breast cancers experience relapse with distant metastasis. It is a challenge to identify patients at risk for relapse; therefore, the identification of markers and therapeutic targets for metastatic breast cancers is imperative. Here, we identified DP103 as a biomarker and metastasis-driving oncogene in human breast cancers and determined that DP103 elevates matrix metallopeptidase 9 (MMP9) levels, which are associated with metastasis and invasion through activation of NF-κB. In turn, NF-κB signaling positively activated DP103 expression. Furthermore, DP103 enhanced TGF-β–activated kinase-1 (TAK1) phosphorylation of NF-κB–activating IκB kinase 2 (IKK2), leading to increased NF-κB activity. Reduction of DP103 expression in invasive breast cancer cells reduced phosphorylation of IKK2, abrogated NF-κB–mediated MMP9 expression, and impeded metastasis in a murine xenograft model. In breast cancer patient tissues, elevated levels of DP103 correlated with enhanced MMP9, reduced overall survival, and reduced survival after relapse. Together, these data indicate that a positive DP103/NF-κB feedback loop promotes constitutive NF-κB activation in invasive breast cancers and activation of this pathway is linked to cancer progression and the acquisition of chemotherapy resistance. Furthermore, our results suggest that DP103 has potential as a therapeutic target for breast cancer treatment.

Authors

Eun Myoung Shin, Hui Sin Hay, Moon Hee Lee, Jen Nee Goh, Tuan Zea Tan, Yin Ping Sen, See Wee Lim, Einas M. Yousef, Hooi Tin Ong, Aye Aye Thike, Xiangjun Kong, Zhengsheng Wu, Earnest Mendoz, Wei Sun, Manuel Salto-Tellez, Chwee Teck Lim, Peter E. Lobie, Yoon Pin Lim, Celestial T. Yap, Qi Zeng, Gautam Sethi, Martin B. Lee, Patrick Tan, Boon Cher Goh, Lance D. Miller, Jean Paul Thiery, Tao Zhu, Louis Gaboury, Puay Hoon Tan, Kam Man Hui, George Wai-Cheong Yip, Shigeki Miyamoto, Alan Prem Kumar, Vinay Tergaonkar

Targeted p16^Ink4a epimutation causes tumorigenesis and reduces survival in mice

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Abstract

Cancer has long been viewed as a genetic disease; however, epigenetic silencing as the result of aberrant promoter DNA methylation is frequently associated with cancer development, suggesting an epigenetic component to the disease. Nonetheless, it has remained unclear whether an epimutation (an aberrant change in epigenetic regulation) can induce tumorigenesis. Here, we exploited a functionally validated cis-acting regulatory element and devised a strategy to induce developmentally regulated genomic targeting of DNA methylation. We used this system to target DNA methylation within the p16^Ink4a promoter in mice in vivo. Engineered p16^Ink4a promoter hypermethylation led to transcriptional suppression in somatic tissues during aging and increased the incidence of spontaneous cancers in these mice. Further, mice carrying a germline p16^Ink4a mutation in one allele and a somatic epimutation in the other had accelerated tumor onset and substantially shortened tumor-free survival. Taken together, these results provide direct functional evidence that p16^Ink4a epimutation drives tumor formation and malignant progression and validate a targeted methylation approach to epigenetic engineering.

Authors

Da-Hai Yu, Robert A. Waterland, Pumin Zhang, Deborah Schady, Miao-Hsueh Chen, Yongtao Guan, Manasi Gadkari, Lanlan Shen

EGFR phosphorylation of DCBLD2 recruits TRAF6 and stimulates AKT-promoted tumorigenesis

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Abstract

Aberrant activation of EGFR in human cancers promotes tumorigenesis through stimulation of AKT signaling. Here, we determined that the discoidina neuropilin-like membrane protein DCBLD2 is upregulated in clinical specimens of glioblastomas and head and neck cancers (HNCs) and is required for EGFR-stimulated tumorigenesis. In multiple cancer cell lines, EGFR activated phosphorylation of tyrosine 750 (Y750) of DCBLD2, which is located within a recently identified binding motif for TNF receptor-associated factor 6 (TRAF6). Consequently, phosphorylation of DCBLD2 Y750 recruited TRAF6, leading to increased TRAF6 E3 ubiquitin ligase activity and subsequent activation of AKT, thereby enhancing EGFR-driven tumorigenesis. Moreover, evaluation of patient samples of gliomas and HNCs revealed an association among EGFR activation, DCBLD2 phosphorylation, and poor prognoses. Together, our findings uncover a pathway in which DCBLD2 functions as a signal relay for oncogenic EGFR signaling to promote tumorigenesis and suggest DCBLD2 and TRAF6 as potential therapeutic targets for human cancers that are associated with EGFR activation.

Authors

Haizhong Feng, Giselle Y. Lopez, Chung Kwon Kim, Angel Alvarez, Christopher G. Duncan, Ryo Nishikawa, Motoo Nagane, An-Jey A. Su, Philip E. Auron, Matthew L. Hedberg, Lin Wang, Jeffery J. Raizer, John A. Kessler, Andrew T. Parsa, Wei-Qiang Gao, Sung-Hak Kim, Mutsuko Minata, Ichiro Nakano, Jennifer R. Grandis, Roger E. McLendon, Darell D. Bigner, Hui-Kuan Lin, Frank B. Furnari, Webster K. Cavenee, Bo Hu, Hai Yan, Shi-Yuan Cheng

RAS interaction with PI3K p110α is required for tumor-induced angiogenesis

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Abstract

Direct interaction of RAS with the PI3K p110α subunit mediates RAS-driven tumor development: however, it is not clear how p110α/RAS-dependant signaling mediates interactions between tumors and host tissues. Here, using a murine tumor cell transfer model, we demonstrated that disruption of the interaction between RAS and p110α within host tissue reduced tumor growth and tumor-induced angiogenesis, leading to improved survival of tumor-bearing mice, even when this interaction was intact in the transferred tumor. Furthermore, functional interaction of RAS with p110α in host tissue was required for efficient establishment and growth of metastatic tumors. Inhibition of RAS and p110α interaction prevented proper VEGF-A and FGF-2 signaling, which are required for efficient angiogenesis. Additionally, disruption of the RAS and p110α interaction altered the nature of tumor-associated macrophages, inducing expression of markers typical for macrophage populations with reduced tumor-promoting capacity. Together, these results indicate that a functional RAS interaction with PI3K p110α in host tissue is required for the establishment of a growth-permissive environment for the tumor, particularly for tumor-induced angiogenesis. Targeting the interaction of RAS with PI3K has the potential to impair tumor formation by altering the tumor-host relationship, in addition to previously described tumor cell–autonomous effects.

Authors

Miguel Manuel Murillo, Santiago Zelenay, Emma Nye, Esther Castellano, Francois Lassailly, Gordon Stamp, Julian Downward

The deubiquitinase USP28 controls intestinal homeostasis and promotes colorectal cancer

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Abstract

Colorectal cancer is the third most common cancer worldwide. Although the transcription factor c-MYC is misregulated in the majority of colorectal tumors, it is difficult to target directly. The deubiquitinase USP28 stabilizes oncogenic factors, including c-MYC; however, the contribution of USP28 in tumorigenesis, particularly in the intestine, is unknown. Here, using murine genetic models, we determined that USP28 antagonizes the ubiquitin-dependent degradation of c-MYC, a known USP28 substrate, as well as 2 additional oncogenic factors, c-JUN and NOTCH1, in the intestine. Mice lacking Usp28 had no apparent adverse phenotypes, but exhibited reduced intestinal proliferation and impaired differentiation of secretory lineage cells. In a murine model of colorectal cancer, Usp28 deletion resulted in fewer intestinal tumors, and importantly, in established tumors, Usp28 deletion reduced tumor size and dramatically increased lifespan. Moreover, we identified Usp28 as a c-MYC target gene highly expressed in murine and human intestinal cancers, which indicates that USP28 and c-MYC form a positive feedback loop that maintains high c-MYC protein levels in tumors. Usp28 deficiency promoted tumor cell differentiation accompanied by decreased proliferation, which suggests that USP28 acts similarly in intestinal homeostasis and colorectal cancer models. Hence, inhibition of the enzymatic activity of USP28 may be a potential target for cancer therapy.

Authors

Markus E. Diefenbacher, Nikita Popov, Sophia M. Blake, Christina Schülein-Völk, Emma Nye, Bradley Spencer-Dene, Laura A. Jaenicke, Martin Eilers, Axel Behrens