Mediator kinases CDK19 and CDK8, pleiotropic regulators of transcriptional reprogramming, are differentially regulated by androgen signaling but both kinases are upregulated in castration-resistant prostate cancer (CRPC). Genetic or pharmacological inhibition of CDK8 and CDK19 reverses the castration-resistant phenotype and restores the sensitivity of CRPC xenografts to androgen deprivation in vivo. Prolonged CDK8/19 inhibitor treatment combined with castration not only suppresses the growth of CRPC xenografts but also induces tumor regression and cures. Transcriptomic analysis revealed that Mediator kinase inhibition amplifies and modulates the effects of castration on gene expression, disrupting CRPC adaptation to androgen deprivation. Mediator kinase inactivation in tumor cells also affects stromal gene expression, indicating that Mediator kinase activity in CRPC molds the tumor microenvironment. The combination of castration and Mediator kinase inhibition downregulates the MYC pathway, and Mediator kinase inhibition suppresses a MYC-driven CRPC tumor model even without castration. CDK8/19 inhibitors show efficacy in patient-derived xenograft models of CRPC, and a gene signature of Mediator kinase activity correlates with tumor progression and overall survival in clinical samples of metastatic CRPC. These results indicate that Mediator kinases mediate androgen-independent in vivo growth of CRPC, supporting the development of CDK8/19 inhibitors for the treatment of this presently incurable disease.
Jing Li, Thomas A. Hilimire, Liu Yueying, Lili Wang, Jiaxin Liang, Balázs Győrffy, Vitali Sikirzhytski, Hao Ji, Li Zhang, Chen Cheng, Xiaokai Ding, Kendall R. Kerr, Charles E. Dowling, Alexander A. Chumanevich, Zachary T. Mack, Gary P. Schools, Chang-uk Lim, Leigh Ellis, Xiaolin Zi, Donald C. Porter, Eugenia V. Broude, Campbell McInnes, George Wilding, Michael B. Lilly, Igor B. Roninson, Mengqian Chen
The mammalian SUMO-targeted E3 Ubiquitin Ligase, Rnf4, has been reported to act as a regulator of DNA repair, but the importance of RNF4 as a tumor suppressor has not been tested. Using a conditional-knockout mouse model, we deleted Rnf4 in the B cell lineage to test the importance of RNF4 for growth of somatic cells. Although Rnf4 conditional-knockout B cells exhibited substantial genomic instability, Rnf4 deletion caused no increase in tumor susceptibility. In contrast, Rnf4 deletion extended the healthy lifespan of mice expressing an oncogenic c-myc transgene. Rnf4 activity is essential for normal DNA replication, and in its absence, there was a failure in ATR-CHK1 signaling of replication stress. Factors that normally mediate replication fork stability, including members of the Fanconi Anemia gene family and the helicases, PIF1 and RECQL5, showed reduced accumulation at replication forks in the absence of RNF4. RNF4 deficiency also resulted in an accumulation of hyper-SUMOylated proteins in chromatin, including members of the SMC5/6 complex, which contributes to replication failure by a mechanism dependent on RAD51. These findings indicate that RNF4, which shows increased expression in multiple human tumor types, is a potential target for anti-cancer therapy, especially in tumors expressing c-myc.
Joonyoung Her, Haiyan Zheng, Samuel F. Bunting
Despite widespread utilization of immunotherapy, challenge to treat immune-cold tumors needs to be resolved. Multiomic analyses and experimental validation identified the OTUD4-CD73 proteolytic axis as a promising target in treating immune-suppressive triple negative breast cancer (TNBC). Mechanistically, deubiquitylation of CD73 by OTUD4 counteracted its ubiquitylation by TRIM21, resulting in CD73 stabilization that inhibits tumor immune responses. We further demonstrated the importance of TGF-β signaling for orchestrating the OTUD4-CD73 proteolytic axis within tumor cells. Spatial transcriptomics profiling discovered spatially resolved features of interacting malignant and immune cells pertaining to expression levels of OTUD4 and CD73. In addition, ST80, a newly developed inhibitor, specifically disrupted proteolytic interaction between CD73 and OTUD4, leading to reinvigoration of cytotoxic CD8+ T cell activities. In preclinical models of TNBC, ST80 treatment sensitized refractory tumors to anti-PD-L1 therapy. Collectively, our findings uncover a novel strategy for targeting immunosuppressive OTUD4-CD73 proteolytic axis in treating immune-suppressive breast cancers with the inhibitor ST80.
Yueming Zhu, Anupam Banerjee, Ping Xie, Andrey A. Ivanov, Amad Uddin, Qiao Jiao, Junlong J. Chi, Lidan Zeng, Ji Young Lee, Yifan Xue, Xinghua Lu, Massimo Cristofanilli, William J. Gradishar, Curtis J. Henry, Theresa W. Gillespie, Manali Ajay Bhave, Kevin Kalinsky, Haian Fu, Ivet Bahar, Bin Zhang, Yong Wan
Neurofibromatosis Type 1 (NF1) is caused by mutations in the NF1 gene that encodes neurofibromin, a RAS GTPase-Activating Protein. Inactivating NF1 mutations cause hyperactivation of RAS-mediated signaling, resulting in development of multiple neoplasms, including Malignant Peripheral Nerve Sheath Tumors (MPNSTs). MPNSTs are an aggressive tumor and the main cause of mortality in NF1 patients. MPNSTs are difficult to resect and refractory to chemo- and radiotherapy, and no molecular therapies currently exist. Immune Checkpoint Blockade (ICB) is an approach to treat inoperable, undruggable cancers like MPNST, but successful outcomes require an immune cell-rich tumor microenvironment (TME). While MPNSTs are non-inflamed “cold” tumors, here, we turned MPNSTs into T cell-inflamed “hot” tumors by activating “stimulator of interferon genes” (STING) signaling. Mouse genetic and human xenograft MPNST models treated with STING agonist plus ICB exhibited growth delay via increased apoptotic cell death. This strategy offers a potential treatment regimen for MPNST.
Bandarigoda N. Somatilaka, Laasya Madana, Ali Sadek, Zhiguo Chen, Sanjay Chandrasekaran, Renee M. McKay, Lu Q. Le
Macrophage immune checkpoint inhibitors, such as anti-CD47 antibodies, show promise in clinical trials for solid and hematologic malignancies. However, the best strategies to use these therapies remain unknown, and ongoing studies suggest they may be most effective when used in combination with other anticancer agents. Here, we developed a novel screening platform to identify drugs that render lung cancer cells more vulnerable to macrophage attack, and we identified therapeutic synergy exists between genotype-directed therapies and anti-CD47 antibodies. In validation studies, we found the combination of genotype-directed therapies and CD47 blockade elicited robust phagocytosis and eliminated persister cells in vitro and maximized anti-tumor responses in vivo. Importantly, these findings broadly applied to lung cancers with various RTK/MAPK pathway alterations—including EGFR mutations, ALK fusions, or KRASG12C mutations. We observed downregulation of β2-microglobulin and CD73 as molecular mechanisms contributing to enhanced sensitivity to macrophage attack. Our findings demonstrate that dual inhibition of the RTK/MAPK pathway and the CD47/SIRPa axis is a promising immunotherapeutic strategy. Our study provides strong rationale for testing this therapeutic combination in patients with lung cancers bearing driver mutations.
Kyle Vaccaro, Juliet Allen, Troy W. Whitfield, Asaf Maoz, Sarah Reeves, José Velarde, Dian Yang, Anna Meglan, Juliano Ribeiro, Jasmine Blandin, Nicole Phan, George W. Bell, Aaron Hata, Kipp Weiskopf
Development of effective strategies to manage the inevitable acquired resistance to osimertinib, an approved 3rd generation EGFR inhibitor for the treatment of EGFR mutant (EGFRm) non-small cell lung cancer (NSCLC), is urgently needed. This study reported that the DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide (VP-16) synergistically decreased cell survival with enhanced induction of DNA damage and apoptosis in osimertinib-resistant cells, suppressed the growth of osimertinib-resistant tumors, and delayed the emergence of osimertinib acquired resistance. Mechanistically, osimertinib decreased Topo IIα levels in EGFRm NSCLC cells by facilitating FBXW7-mediated proteasomal degradation, resulting in induction of DNA damage; these effects were lost in osimertinib-resistant cell lines possessing elevated levels of Topo IIα. Topo IIα elevation was also detected in the majority of EGFRm NSCLC tissues relapsed from EGFR-TKI treatment. Enforced expression of an ectopic TOP2A gene in sensitive EGFRm NSCLC cells conferred resistance to osimertinib, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their response to undergo osimertinib-induced DNA damage and apoptosis. Together, these results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of osimertinib against EGFRm NSCLC, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib.
Zhen Chen, Karin A. Vallega, Dongsheng Wang, Zihan Quan, Songqing Fan, Qiming Wang, Ticiana Leal, Suresh S. Ramalingam, Shi-Yong Sun
RAD54 and BLM helicase play pivotal roles during homologous recombination repair (HRR) ensuring genome maintenance. BLM amino acids (181-212) interacts with RAD54 and enhances its chromatin remodelling activity. Functionally, this interaction heightens HRR, leading to a decrease in residual DNA damage in colon cancer cells. This contributes to chemoresistance in colon cancer cells against cisplatin, camptothecin and oxaliplatin, eventually promoting tumorigenesis in preclinical colon cancer mouse models. ChIP-seq analysis and validation revealed increased BLM/RAD54 co-recruitment on MRP2 promoter in camptothecin resistant colon cancer cells, leading to BLM-dependent enhancement of RAD54-mediated chromatin remodelling. We screened Prestwick small molecule library intending to revert camptothecin and oxaliplatin induced chemoresistance by disrupting BLM-RAD54 interaction. Three FDA/EMA approved candidates were identified which could disrupt this interaction. These drugs bind to RAD54, alter its conformation and abrogate BLM-RAD54 dependent chromatin remodeling on G5E4 and MRP2 arrays. Notably, the small molecules also reduced HRR repair efficiency in resistant lines, diminished anchorage independent growth, hampered the proliferation of tumors generated using camptothecin and oxaliplatin resistant colon cancer cells in both xenograft and syngeneic mouse models in BLM dependent manner. Hence the three identified small molecules can serve as possible viable candidates for adjunct therapy in colon cancer treatment.
Ekjot Kaur, Ritu Agrawal, Rimpy Arun, Vinoth Madhavan, Vivek Srivastava, Dilip Kumar, Pragyan Parimita Rath, Nitin Kumar, Sreekanth Vedagopuram, Nishant Pandey, Swati Priya, Patrick Legembre, Samudrala Gourinath, Avinash Bajaj, Sagar Sengupta
Translocation Renal Cell Carcinoma (tRCC) most commonly involves an ASPSCR1-TFE3 fusion, but molecular mechanisms remain elusive and animal models are lacking. Here, we show that human ASPSCR1-TFE3 driven by Pax8-Cre (a credentialed ccRCC driver) disrupted nephrogenesis and glomerular development causing neonatal death, whilst the ccRCC failed driver, Sglt2-Cre, induced aggressive tRCC (as well as ASPS) with complete penetrance and short latency. However, in both contexts, ASPSCR1-TFE3 led to characteristic morphological cellular changes, loss of epithelial markers, and an EMT program. Electron microscopy of tRCC tumors showed lysosome expansion and functional studies revealed simultaneous activation of autophagy and mTORC1 pathways. Comparative genomic analyses encompassing an institutional human tRCC cohort (including a hitherto unreported SFPQ-TFEB fusion) and a variety of tumorgraft models (ASPSCR1-TFE3, PRCC-TFE3, SFPQ-TFE3, RBM10-TFE3, and MALAT1-TFEB) disclosed significant convergence in canonical (cell cycle, lysosome and mTORC1) and less established pathways such as Myc, E2F and inflammation (IL6/JAK/STAT3, interferon-γ, TLR signaling, systemic lupus, etc). Therapeutic trials (adjusted for human drug exposures) showed anti-tumor activity of cabozantinib. Overall, this study provides insight into MiT/TFE-driven tumorigenesis including the cell of origin and characterizes diverse mouse models available for research.
Gopinath Prakasam, Akhilesh Mishra, Alana Christie, Jeffrey Miyata, Deyssy Carrillo, Vanina T. Tcheuyap, Hui Ye, Quyen N. Do, Yunguan Wang, Oscar Reig Torras, Ramesh Butti, Hua Zhong, Jeffrey Gagan, Kevin B. Jones, Thomas J. Carroll, Zora Modrusan, Steffen Durinck, Mai-Carmen Requena-Komuro, Noelle S. Williams, Ivan Pedrosa, Tao Wang, Dinesh Rakheja, Payal Kapur, James Brugarolas
While therapies targeting CD19 by antibodies, CAR-T cells and T cell engagers have improved the response rates in B-cell malignancies; the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19-immunotoxin. Single-cell (sc) RNAseq showed increase in transcriptionally distinct CD19low populations in resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19low resistant cells. ATAC-seq showed decreased chromatin accessibility at promoters of both CD19 and CD22 during development of resistance. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with ALL that relapsed after CD19 CAR-T targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19low resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both BTK and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.
Sarah Aminov, Orsi Giricz, David T. Melnekoff, R. Alejandro Sica, Veronika Polishchuk, Cristian Papazoglu, Bonnie Yates, Hao-Wei Wang, Srabani Sahu, Yanhua Wang, Shanisha Gordon-Mitchell, Violetta V. Leshchenko, Carolina Schinke, Kith Pradhan, Srinivas Aluri, Moah Sohn, Stefan K. Barta, Beamon Agarwal, Mendel Goldfinger, Ioannis Mantzaris, Aditi Shastri, William Matsui, Ulrich Steidl, Joshua D. Brody, Nirali N. Shah, Samir Parekh, Amit Verma
Shashwat Tripathi, Hinda Najem, Corey Dussold, Sebastian Pacheco, Jason Miska, Kathleen McCortney, Alicia Steffens, Jordain Walshon, Daniel Winkowski, Michael Cloney, Matthew Ordon, William Gibson, Hanna Kemeny, Mark Youngblood, Rebecca Du, James Mossner, Pavlos Texakalidis, Annelise Sprau, Matthew Tate, Charles David James, Craig M. Horbinski, Nitin R. Wadhwani, Maciej S. Lesniak, Sandi Lam, Ankita Sati, Manish Aghi, Michael DeCuypere, Amy B. Heimberger