Breast cancer cells with stem cell properties are key contributors to metastatic disease, and there remains a need to better understand and target these cells in human cancers. Here, we identified rare stem-like cells in patients’ tumors characterized by low levels of the proapoptotic molecule p53-upregulated modulator of apoptosis (PUMA) and showed that these cells play a critical role in tumor progression that is independent of clinical subtype. A signaling axis consisting of the integrin αvβ3, Src kinase, and the transcription factor Slug suppresses PUMA in these cells, promoting tumor stemness. We showed that genetic or pharmacological disruption of αvβ3/Src signaling drives PUMA expression, specifically depleting these stem-like tumor cells; increases their sensitivity to apoptosis; and reduces pulmonary metastasis, with no effect on primary tumor growth. Taken together, these findings point to PUMA as a key vulnerability of stem-like cells and suggest that pharmacological upregulation of PUMA via Src inhibition may represent a strategy to selectively target these cells in a wide spectrum of aggressive breast cancers.
Qi Sun, Jacqueline Lesperance, Hiromi Wettersten, Elaine Luterstein, Yoko S. DeRose, Alana Welm, David A. Cheresh, Jay S. Desgrosellier
DNA double-strand breaks (DSBs) are mainly repaired either by homologous recombination (HR) or by nonhomologous end-joining (NHEJ) pathways. Here, we showed that myeloid cell leukemia sequence 1 (Mcl-1) acts as a functional switch in selecting between HR and NHEJ pathways. Mcl-1 was cell cycle–regulated during HR, with its expression peaking in S/G2 phase. While endogenous Mcl-1 depletion reduced HR and enhanced NHEJ, Mcl-1 overexpression resulted in a net increase in HR over NHEJ. Mcl-1 directly interacted with the dimeric Ku protein complex via its Bcl-2 homology 1 and 3 (BH1 and BH3) domains, which are required for Mcl-1 to inhibit Ku-mediated NHEJ. Mcl-1 also promoted DNA resection mediated by the Mre11 complex and HR-dependent DSB repair. Using the Mcl-1 BH1 domain as a docking site, we identified a small molecule, MI-223, that directly bound to BH1 and blocked Mcl-1–stimulated HR DNA repair, leading to sensitization of cancer cells to hydroxyurea- or olaparib-induced DNA replication stress. Combined treatment with MI-223 and hydroxyurea or olaparib exhibited a strong synergy against lung cancer in vivo. This mechanism-driven combination of agents provides a highly attractive therapeutic strategy to improve lung cancer outcomes.
Guo Chen, Andrew T. Magis, Ke Xu, Dongkyoo Park, David S. Yu, Taofeek K. Owonikoko, Gabriel L. Sica, Sarah W. Satola, Suresh S. Ramalingam, Walter J. Curran, Paul W. Doetsch, Xingming Deng
Oncogenic addiction to the Fms-like tyrosine kinase 3 (FLT3) is a hallmark of acute myeloid leukemia (AML) that harbors the FLT3–internal tandem duplication (FLT3-ITD) mutation. While FLT3 inhibitors like sorafenib show initial therapeutic efficacy, resistance rapidly develops through mechanisms that are incompletely understood. Here, we used RNA-Seq–based analysis of patient leukemic cells and found that upregulation of the Tec family kinase BMX occurs during sorafenib resistance. This upregulation was recapitulated in an in vivo murine FLT3-ITD–positive (FLT3-ITD+) model of sorafenib resistance. Mechanistically, the antiangiogenic effects of sorafenib led to increased bone marrow hypoxia, which contributed to HIF-dependent BMX upregulation. In in vitro experiments, hypoxia-dependent BMX upregulation was observed in both AML and non-AML cell lines. Functional studies in human FLT3-ITD+ cell lines showed that BMX is part of a compensatory signaling mechanism that promotes AML cell survival during FLT3 inhibition. Taken together, our results demonstrate that hypoxia-dependent upregulation of BMX contributes to therapeutic resistance through a compensatory prosurvival signaling mechanism. These results also reveal the role of off-target drug effects on tumor microenvironment and development of acquired drug resistance. We propose that the bone marrow niche can be altered by anticancer therapeutics, resulting in drug resistance through cell-nonautonomous microenvironment-dependent effects.
Jolieke G. van Oosterwijk, Daelynn R. Buelow, Christina D. Drenberg, Aksana Vasilyeva, Lie Li, Lei Shi, Yong-Dong Wang, David Finkelstein, Sheila A. Shurtleff, Laura J. Janke, Stanley Pounds, Jeffrey E. Rubnitz, Hiroto Inaba, Navjotsingh Pabla, Sharyn D. Baker
SHARPIN, an adaptor for the linear ubiquitin chain assembly complex (LUBAC), plays important roles in NF-κB signaling and inflammation. Here, we have demonstrated a LUBAC-independent role for SHARPIN in regulating melanoma growth. We observed that SHARPIN interacted with PRMT5, a type II protein arginine methyltransferase, and increased its multiprotein complex and methyltransferase activity. Activated PRMT5 controlled the expression of the transcription factors SOX10 and MITF by SHARPIN-dependent arginine dimethylation and inhibition of the transcriptional corepressor SKI. Activation of PRMT5 by SHARPIN counteracted PRMT5 inhibition by methylthioadenosine, a substrate of methylthioadenosine phosphorylase, which is codeleted with cyclin-dependent kinase inhibitor 2A (CDKN2A) in approximately 15% of human cancers. Collectively, we identified a LUBAC-independent role for SHARPIN in enhancing PRMT5 activity that contributes to melanomagenesis through the SKI/SOX10 regulatory axis.
Hironari Tamiya, Hyungsoo Kim, Oleksiy Klymenko, Heejung Kim, Yongmei Feng, Tongwu Zhang, Ji Yun Han, Ayako Murao, Scott J. Snipas, Lucia Jilaveanu, Kevin Brown, Harriet Kluger, Hao Zhang, Kazuhiro Iwai, Ze’ev A. Ronai
Transplantation of neural progenitor cells (NPCs) is a potential therapy for treating neurodegenerative disorders, but this approach has faced many challenges and limited success, primarily because of inhospitable host brain environments that interfere with enriched neuron engraftment and function. Astrocytes play neurotrophic roles in the developing and adult brain, making them potential candidates for helping with modification of hostile brain environments. In this study, we examined whether astrocytic function could be utilized to overcome the current limitations of cell-based therapies in a murine model of Parkinson’s disease (PD) that is characterized by dopamine (DA) neuron degeneration in the midbrain. We show here that cografting astrocytes, especially those derived from the midbrain, remarkably enhanced NPC-based cell therapeutic outcomes along with robust DA neuron engraftment in PD rats for at least 6 months after transplantation. We further show that engineering of donor astrocytes with Nurr1 and Foxa2, transcription factors that were recently reported to polarize harmful immunogenic glia into the neuroprotective form, further promoted the neurotrophic actions of grafted astrocytes in the cell therapeutic approach. Collectively, these findings suggest that cografting astrocytes could be a potential strategy for successful cell therapeutic outcomes in neurodegenerative disorders.
Jae-Jin Song, Sang-Min Oh, Oh-Chan Kwon, Noviana Wulnansari, Hyun-Seob Lee, Mi-Yoon Chang, Eunsoo Lee, Woong Sun, Sang-Eun Lee, Sunghoe Chang, Heeyoung An, C. Justin Lee, Sang-Hun Lee
Histone protein modifications control fate determination during normal development and dedifferentiation during disease. Here, we set out to determine the extent to which dynamic changes to histones affect the differentiated phenotype of ordinarily quiescent adult glomerular podocytes. To do this, we examined the consequences of shifting the balance of the repressive histone H3 lysine 27 trimethylation (H3K27me3) mark in podocytes. Adriamycin nephrotoxicity and subtotal nephrectomy (SNx) studies indicated that deletion of the histone methylating enzyme EZH2 from podocytes decreased H3K27me3 levels and sensitized mice to glomerular disease. H3K27me3 was enriched at the promoter region of the Notch ligand Jag1 in podocytes, and derepression of Jag1 by EZH2 inhibition or knockdown facilitated podocyte dedifferentiation. Conversely, inhibition of the Jumonji C domain–containing demethylases Jmjd3 and UTX increased the H3K27me3 content of podocytes and attenuated glomerular disease in adriamycin nephrotoxicity, SNx, and diabetes. Podocytes in glomeruli from humans with focal segmental glomerulosclerosis or diabetic nephropathy exhibited diminished H3K27me3 and heightened UTX content. Analogous to human disease, inhibition of Jmjd3 and UTX abated nephropathy progression in mice with established glomerular injury and reduced H3K27me3 levels. Together, these findings indicate that ostensibly stable chromatin modifications can be dynamically regulated in quiescent cells and that epigenetic reprogramming can improve outcomes in glomerular disease by repressing the reactivation of developmental pathways.
Syamantak Majumder, Karina Thieme, Sri N. Batchu, Tamadher A. Alghamdi, Bridgit B. Bowskill, M. Golam Kabir, Youan Liu, Suzanne L. Advani, Kathryn E. White, Laurette Geldenhuys, Karthik K. Tennankore, Penelope Poyah, Ferhan S. Siddiqi, Andrew Advani
As new generations of targeted therapies emerge and tumor genome sequencing discovers increasingly comprehensive mutation repertoires, the functional relationships of mutations to tumor phenotypes remain largely unknown. Here, we measured ex vivo sensitivity of 246 blood cancers to 63 drugs alongside genome, transcriptome, and DNA methylome analysis to understand determinants of drug response. We assembled a primary blood cancer cell encyclopedia data set that revealed disease-specific sensitivities for each cancer. Within chronic lymphocytic leukemia (CLL), responses to 62% of drugs were associated with 2 or more mutations, and linked the B cell receptor (BCR) pathway to trisomy 12, an important driver of CLL. Based on drug responses, the disease could be organized into phenotypic subgroups characterized by exploitable dependencies on BCR, mTOR, or MEK signaling and associated with mutations, gene expression, and DNA methylation. Fourteen percent of CLLs were driven by mTOR signaling in a non–BCR-dependent manner. Multivariate modeling revealed immunoglobulin heavy chain variable gene (IGHV) mutation status and trisomy 12 as the most important modulators of response to kinase inhibitors in CLL. Ex vivo drug responses were associated with outcome. This study overcomes the perception that most mutations do not influence drug response of cancer, and points to an updated approach to understanding tumor biology, with implications for biomarker discovery and cancer care.
Sascha Dietrich, Małgorzata Oleś, Junyan Lu, Leopold Sellner, Simon Anders, Britta Velten, Bian Wu, Jennifer Hüllein, Michelle da Silva Liberio, Tatjana Walther, Lena Wagner, Sophie Rabe, Sonja Ghidelli-Disse, Marcus Bantscheff, Andrzej K. Oleś, Mikołaj Słabicki, Andreas Mock, Christopher C. Oakes, Shihui Wang, Sina Oppermann, Marina Lukas, Vladislav Kim, Martin Sill, Axel Benner, Anna Jauch, Lesley Ann Sutton, Emma Young, Richard Rosenquist, Xiyang Liu, Alexander Jethwa, Kwang Seok Lee, Joe Lewis, Kerstin Putzker, Christoph Lutz, Davide Rossi, Andriy Mokhir, Thomas Oellerich, Katja Zirlik, Marco Herling, Florence Nguyen-Khac, Christoph Plass, Emma Andersson, Satu Mustjoki, Christof von Kalle, Anthony D. Ho, Manfred Hensel, Jan Dürig, Ingo Ringshausen, Marc Zapatka, Wolfgang Huber, Thorsten Zenz
Germline mutations in the gene encoding tumor suppressor kinase LKB1 lead to gastrointestinal tumorigenesis in Peutz-Jeghers syndrome (PJS) patients and mouse models; however, the cell types and signaling pathways underlying tumor formation are unknown. Here, we demonstrated that mesenchymal progenitor- or stromal fibroblast–specific deletion of Lkb1 results in fully penetrant polyposis in mice. Lineage tracing and immunohistochemical analyses revealed clonal expansion of Lkb1-deficient myofibroblast-like cell foci in the tumor stroma. Loss of Lkb1 in stromal cells was associated with induction of an inflammatory program including IL-11 production and activation of the JAK/STAT3 pathway in tumor epithelia concomitant with proliferation. Importantly, treatment of LKB1-defcient mice with the JAK1/2 inhibitor ruxolitinib dramatically decreased polyposis. These data indicate that IL-11–mediated induction of JAK/STAT3 is critical in gastrointestinal tumorigenesis following Lkb1 mutations and suggest that targeting this pathway has therapeutic potential in Peutz-Jeghers syndrome.
Saara Ollila, Eva Domènech-Moreno, Kaisa Laajanen, Iris P.L. Wong, Sushil Tripathi, Nalle Pentinmikko, Yajing Gao, Yan Yan, Elina H. Niemelä, Timothy C. Wang, Benoit Viollet, Gustavo Leone, Pekka Katajisto, Kari Vaahtomeri, Tomi P. Mäkelä
Pharmacologically difficult targets, such as MYC transcription factors, represent a major challenge in cancer therapy. For the childhood cancer neuroblastoma, amplification of the oncogene MYCN is associated with high-risk disease and poor prognosis. Here, we deployed genome-scale CRISPR-Cas9 screening of MYCN-amplified neuroblastoma and found a preferential dependency on genes encoding the polycomb repressive complex 2 (PRC2) components EZH2, EED, and SUZ12. Genetic and pharmacological suppression of EZH2 inhibited neuroblastoma growth in vitro and in vivo. Moreover, compared with neuroblastomas without MYCN amplification, MYCN-amplified neuroblastomas expressed higher levels of EZH2. ChIP analysis showed that MYCN binds at the EZH2 promoter, thereby directly driving expression. Transcriptomic and epigenetic analysis, as well as genetic rescue experiments, revealed that EZH2 represses neuronal differentiation in neuroblastoma in a PRC2-dependent manner. Moreover, MYCN-amplified and high-risk primary tumors from patients with neuroblastoma exhibited strong repression of EZH2-regulated genes. Additionally, overexpression of IGFBP3, a direct EZH2 target, suppressed neuroblastoma growth in vitro and in vivo. We further observed strong synergy between histone deacetylase inhibitors and EZH2 inhibitors. Together, these observations demonstrate that MYCN upregulates EZH2, leading to inactivation of a tumor suppressor program in neuroblastoma, and support testing EZH2 inhibitors in patients with MYCN-amplified neuroblastoma.
Liying Chen, Gabriela Alexe, Neekesh V. Dharia, Linda Ross, Amanda Balboni Iniguez, Amy Saur Conway, Emily Jue Wang, Veronica Veschi, Norris Lam, Jun Qi, W. Clay Gustafson, Nicole Nasholm, Francisca Vazquez, Barbara A. Weir, Glenn S. Cowley, Levi D. Ali, Sasha Pantel, Guozhi Jiang, William F. Harrington, Yenarae Lee, Amy Goodale, Rakela Lubonja, John M. Krill-Burger, Robin M. Meyers, Aviad Tsherniak, David E. Root, James E. Bradner, Todd R. Golub, Charles W.M. Roberts, William C. Hahn, William A. Weiss, Carol J. Thiele, Kimberly Stegmaier
γδT cells produce inflammatory cytokines and have been implicated in the pathogenesis of cancer, infectious diseases, and autoimmunity. The T cell receptor (TCR) signal transduction that specifically regulates the development of IL-17–producing γδT (γδT17) cells largely remains unclear. Here, we showed that the receptor proximal tyrosine kinase Syk is essential for γδTCR signal transduction and development of γδT17 in the mouse thymus. Zap70, another tyrosine kinase essential for the development of αβT cells, failed to functionally substitute for Syk in the development of γδT17. Syk induced the activation of the PI3K/Akt pathway upon γδTCR stimulation. Mice deficient in PI3K signaling exhibited a complete loss of γδT17, without impaired development of IFN-γ–producing γδT cells. Moreover, γδT17-dependent skin inflammation was ameliorated in mice deficient in RhoH, an adaptor known to recruit Syk. Thus, we deciphered lineage-specific TCR signaling and identified the Syk/PI3K pathway as a critical determinant of proinflammatory γδT cell differentiation.
Ryunosuke Muro, Takeshi Nitta, Kenta Nakano, Tadashi Okamura, Hiroshi Takayanagi, Harumi Suzuki