Peroxisomes perform essential functions in lipid metabolism, including fatty acid oxidation and plasmalogen synthesis. Here, we describe a role for peroxisomal lipid metabolism in mitochondrial dynamics in brown and beige adipocytes. Adipose tissue peroxisomal biogenesis was induced in response to cold exposure through activation of the thermogenic coregulator PRDM16. Adipose-specific knockout of the peroxisomal biogenesis factor Pex16 (Pex16-AKO) in mice impaired cold tolerance, decreased energy expenditure, and increased diet-induced obesity. Pex16 deficiency blocked cold-induced mitochondrial fission, decreased mitochondrial copy number, and caused mitochondrial dysfunction. Adipose-specific knockout of the peroxisomal β-oxidation enzyme acyl-CoA oxidase 1 (Acox1-AKO) was not sufficient to affect adiposity, thermogenesis, or mitochondrial copy number, but knockdown of the plasmalogen synthetic enzyme glyceronephosphate O-acyltransferase (GNPAT) recapitulated the effects of Pex16 inactivation on mitochondrial morphology and function. Plasmalogens are present in mitochondria and decreased with Pex16 inactivation. Dietary supplementation with plasmalogens increased mitochondrial copy number, improved mitochondrial function, and rescued thermogenesis in Pex16-AKO mice. These findings support a surprising interaction between peroxisomes and mitochondria regulating mitochondrial dynamics and thermogenesis.
Hongsuk Park, Anyuan He, Min Tan, Jordan M. Johnson, John M. Dean, Terri A. Pietka, Yali Chen, Xiangyu Zhang, Fong-Fu Hsu, Babak Razani, Katsuhiko Funai, Irfan J. Lodhi
Tumor cure with conventional fractionated radiotherapy is 65%, dependent on tumor cell–autonomous gradual buildup of DNA double-strand break (DSB) misrepair. Here we report that single-dose radiotherapy (SDRT), a disruptive technique that ablates more than 90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase–mediated (ASMase-mediated) microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction after SDRT conferred an ischemic stress response within parenchymal tumor cells, with ROS triggering the evolutionarily conserved SUMO stress response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensable for homology-directed repair (HDR) of DSBs, HDR loss of function after SDRT yielded DSB unrepair, chromosomal aberrations, and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging after SDRT using peroxiredoxin-6 overexpression or the SOD mimetic tempol, prevented chromatin SUMO3 depletion, HDR loss of function, and SDRT tumor ablation. We also provide evidence of mouse-to-human translation of this biology in a randomized clinical trial, showing that 24 Gy SDRT, but not 3×9 Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing of SDRT/ASMase signaling, as current studies indicate that this pathway is tractable to pharmacologic intervention.
Sahra Bodo, Cécile Campagne, Tin Htwe Thin, Daniel S. Higginson, H. Alberto Vargas, Guoqiang Hua, John D. Fuller, Ellen Ackerstaff, James Russell, Zhigang Zhang, Stefan Klingler, HyungJoon Cho, Matthew G. Kaag, Yousef Mazaheri, Andreas Rimner, Katia Manova-Todorova, Boris Epel, Joan Zatcky, Cristian R. Cleary, Shyam S. Rao, Yoshiya Yamada, Michael J. Zelefsky, Howard J. Halpern, Jason A. Koutcher, Carlos Cordon-Cardo, Carlo Greco, Adriana Haimovitz-Friedman, Evis Sala, Simon N. Powell, Richard Kolesnick, Zvi Fuks
Abnormal alternative splicing (AS) caused by alterations to splicing factors contributes to tumor progression. Serine/arginine splicing factor 1 (SRSF1) has emerged as a key oncodriver in numerous solid tumors, leaving its roles and mechanisms largely obscure in glioma. Here, we demonstrate that SRSF1 is increased in glioma tissues and cell lines. Moreover, its expression was correlated positively with tumor grade and Ki-67 index, but inversely with patient survival. Using RNA-Seq, we comprehensively screened and identified multiple SRSF1-affected AS events. Motif analysis revealed a position-dependent modulation of AS by SRSF1 in glioma. Functionally, we verified that SRSF1 promoted cell proliferation, survival, and invasion by specifically switching the AS of the myosin IB (MYO1B) gene and facilitating the expression of the oncogenic and membrane-localized isoform, MYO1B-fl. Strikingly, MYO1B splicing was dysregulated in parallel with SRSF1 expression in gliomas and predicted the poor prognosis of the patients. Further investigation revealed that SRSF1-guided AS of the MYO1B gene increased the tumorigenic potential of glioma cells through the PDK1/AKT and PAK/LIMK pathways. Taken together, we identify SRSF1 as an important oncodriver that integrates AS control of MYO1B into promotion of gliomagenesis and represents a potential prognostic biomarker and target for glioma therapy.
Xuexia Zhou, Run Wang, Xuebing Li, Lin Yu, Dan Hua, Cuiyun Sun, Cuijuan Shi, Wenjun Luo, Chun Rao, Zhendong Jiang, Ying Feng, Qian Wang, Shizhu Yu
Loss of phosphatase and tensin homolog (PTEN) represents one hallmark of prostate cancer (PCa). However, restoration of PTEN or inhibition of the activated PI3K/AKT pathway has shown limited success, prompting us to identify obligate targets for disease intervention. We hypothesized that PTEN loss might expose cells to unique epigenetic vulnerabilities. Here, we identified a synthetic lethal relationship between PTEN and Brahma-related gene 1 (BRG1), an ATPase subunit of the SWI/SNF chromatin remodeling complex. Higher BRG1 expression in tumors with low PTEN expression was associated with a worse clinical outcome. Genetically engineered mice (GEMs) and organoid assays confirmed that ablation of PTEN sensitized the cells to BRG1 depletion. Mechanistically, PTEN loss stabilized BRG1 protein through the inhibition of the AKT/GSK3β/FBXW7 axis. Increased BRG1 expression in PTEN-deficient PCa cells led to chromatin remodeling into configurations that drove a protumorigenic transcriptome, causing cells to become further addicted to BRG1. Furthermore, we showed in preclinical models that BRG1 antagonist selectively inhibited the progression of PTEN-deficient prostate tumors. Together, our results highlight the synthetic lethal relationship between PTEN and BRG1 and support targeting BRG1 as an effective approach to the treatment of PTEN-deficient PCa.
Yufeng Ding, Ni Li, Baijun Dong, Wangxin Guo, Hui Wei, Qilong Chen, Huairui Yuan, Ying Han, Hanwen Chang, Shan Kan, Xuege Wang, Qiang Pan, Ping Wu, Chao Peng, Tong Qiu, Qintong Li, Dong Gao, Wei Xue, Jun Qin
The adenomatous polyposis coli (APC) gene plays a pivotal role in the pathogenesis of colorectal carcinoma (CRC) but remains a challenge for drug development. Long noncoding RNAs (lncRNAs) are invaluable in identifying cancer pathologies and providing therapeutic options for patients with cancer. Here, we identified a lncRNA (lncRNA-APC1) activated by APC through lncRNA microarray screening and examined its expression in a large cohort of CRC tissues. A decrease in lncRNA-APC1 expression was positively associated with lymph node and/or distant metastasis, a more advanced clinical stage, as well as a poor prognosis for patients with CRC. Additionally, APC could enhance lncRNA-APC1 expression by suppressing the enrichment of PPARα on the lncRNA-APC1 promoter. Furthermore, enforced lncRNA-APC1 expression was sufficient to inhibit CRC cell growth, metastasis, and tumor angiogenesis by suppressing exosome production through the direct binding of Rab5b mRNA and a reduction of its stability. Importantly, exosomes derived from lncRNA-APC1–silenced CRC cells promoted angiogenesis by activating the MAPK pathway in endothelial cells, and, moreover, exosomal Wnt1 largely enhanced CRC cell proliferation and migration through noncanonicial Wnt signaling. Collectively, lncRNA-APC1 is a critical lncRNA regulated by APC in the pathogenesis of CRC. Our findings suggest that an APC-regulated lncRNA-APC1 program is an exploitable therapeutic approach for the treatment of patients with CRC.
Feng-Wei Wang, Chen-Hui Cao, Kai Han, Yong-Xiang Zhao, Mu-Yan Cai, Zhi-Cheng Xiang, Jia-Xing Zhang, Jie-Wei Chen, Li-Ping Zhong, Yong Huang, Su-Fang Zhou, Xiao-Han Jin, Xin-Yuan Guan, Rui-Hua Xu, Dan Xie
Goblet cell metaplasia, a disabling hallmark of chronic lung disease, lacks curative treatments at present. To identify novel therapeutic targets for goblet cell metaplasia, we studied the transcriptional response profile of IL-13–exposed primary human airway epithelia in vitro and asthmatic airway epithelia in vivo. A perturbation-response profile connectivity approach identified geldanamycin, an inhibitor of heat shock protein 90 (HSP90) as a candidate therapeutic target. Our experiments confirmed that geldanamycin and other HSP90 inhibitors prevented IL-13–induced goblet cell metaplasia in vitro and in vivo. Geldanamycin also reverted established goblet cell metaplasia. Geldanamycin did not induce goblet cell death, nor did it solely block mucin synthesis or IL-13 receptor–proximal signaling. Geldanamycin affected the transcriptome of airway cells when exposed to IL-13, but not when exposed to vehicle. We hypothesized that the mechanism of action probably involves TGF-β, ERBB, or EHF, which would predict that geldanamycin would also revert IL-17–induced goblet cell metaplasia, a prediction confirmed by our experiments. Our findings suggest that persistent airway goblet cell metaplasia requires HSP90 activity and that HSP90 inhibitors will revert goblet cell metaplasia, despite active upstream inflammatory signaling. Moreover, HSP90 inhibitors may be a therapeutic option for airway diseases with goblet cell metaplasia of an unknown mechanism of action.
Alejandro A. Pezzulo, Rosarie A. Tudas, Carley G. Stewart, Luis G. Vargas Buonfiglio, Brian D. Lindsay, Peter J. Taft, Nicholas D. Gansemer, Joseph Zabner
The most frequent subtype of acute myeloid leukemia (AML) is defined by mutations in the nucleophosmin 1 (NPM1) gene. Mutated NPM1 (ΔNPM1) is an attractive target for immunotherapy, since it is an essential driver gene and 4 bp frameshift insertions occur in the same hotspot in 30%–35% of AMLs, resulting in a C-terminal alternative reading frame of 11 aa. By searching the HLA class I ligandome of primary AMLs, we identified multiple ΔNPM1-derived peptides. For one of these peptides, HLA-A*02:01–binding CLAVEEVSL, we searched for specific T cells in healthy individuals using peptide-HLA tetramers. Tetramer-positive CD8+ T cells were isolated and analyzed for reactivity against primary AMLs. From one clone with superior antitumor reactivity, we isolated the T cell receptor (TCR) and demonstrated specific recognition and lysis of HLA-A*02:01–positive ΔNPM1 AML after retroviral transfer to CD8+ and CD4+ T cells. Antitumor efficacy of TCR-transduced T cells was confirmed in immunodeficient mice engrafted with a human AML cell line expressing ΔNPM1. In conclusion, the data show that ΔNPM1-derived peptides are presented on AML and that CLAVEEVSL is a neoantigen that can be efficiently targeted on AML by ΔNPM1 TCR gene transfer. Immunotherapy targeting ΔNPM1 may therefore contribute to treatment of AML.
Dyantha I. van der Lee, Rogier M. Reijmers, Maria W. Honders, Renate S. Hagedoorn, Rob C.M. de Jong, Michel G.D. Kester, Dirk M. van der Steen, Arnoud H. de Ru, Christiaan Kweekel, Helena M. Bijen, Inge Jedema, Hendrik Veelken, Peter A. van Veelen, Mirjam H.M. Heemskerk, J.H. Frederik Falkenburg, Marieke Griffioen
Neutrophil (PMN) infiltration of the intestinal mucosa is a hallmark of tissue injury associated with inflammatory bowel diseases (IBDs). The pathological effects of PMNs are largely attributed to the release of soluble mediators and reactive oxygen species (ROS). We identified what we believe is a new, ROS-independent mechanism whereby activated tissue-infiltrating PMNs release microparticles armed with proinflammatory microRNAs (miR-23a and miR-155). Using IBD clinical samples, and in vitro and in vivo injury models, we show that PMN-derived miR-23a and miR-155 promote accumulation of double-strand breaks (DSBs) by inducing lamin B1–dependent replication fork collapse and inhibition of homologous recombination (HR) by targeting HR-regulator RAD51. DSB accumulation in injured epithelium led to impaired colonic healing and genomic instability. Targeted inhibition of miR-23a and miR-155 in cultured intestinal epithelial cells and in acutely injured mucosa decreased the detrimental effects of PMNs and enhanced tissue healing responses, suggesting that this approach can be used in therapies aimed at resolution of inflammation, in wound healing, and potentially to prevent neoplasia.
Veronika Butin-Israeli, Triet M. Bui, Hannah L. Wiesolek, Lorraine Mascarenhas, Joseph J. Lee, Lindsey C. Mehl, Kaitlyn R. Knutson, Stephen A. Adam, Robert D. Goldman, Arthur Beyder, Lisa Wiesmuller, Stephen B. Hanauer, Ronen Sumagin
Macrophages perform key functions in tissue homeostasis that are influenced by the local tissue environment. Within the tumor microenvironment, tumor-associated macrophages can be altered to acquire properties that enhance tumor growth. Here, we found that lactate, a metabolite found in high concentration within the anaerobic tumor environment, activated mTORC1 that subsequently suppressed TFEB-mediated expression of the macrophage-specific vacuolar ATPase subunit ATP6V0d2. Atp6v0d2–/– mice were more susceptible to tumor growth, with enhanced HIF-2α–mediated VEGF production in macrophages that display a more protumoral phenotype. We found that ATP6V0d2 targeted HIF-2α but not HIF-1α for lysosome-mediated degradation. Blockade of HIF-2α transcriptional activity reversed the susceptibility of Atp6v0d2–/– mice to tumor development. Furthermore, in a cohort of patients with lung adenocarcinoma, expression of ATP6V0d2 and HIF-2α was positively and negatively correlated with survival, respectively, suggesting a critical role of the macrophage lactate/ATP6V0d2/HIF-2α axis in maintaining tumor growth in human patients. Together, our results highlight the ability of tumor cells to modify the function of tumor-infiltrating macrophages to optimize the microenvironment for tumor growth.
Na Liu, Jing Luo, Dong Kuang, Sanpeng Xu, Yaqi Duan, Yu Xia, Zhengping Wei, Xiuxiu Xie, Bingjiao Yin, Fang Chen, Shunqun Luo, Huicheng Liu, Jing Wang, Kan Jiang, Feili Gong, Zhao-hui Tang, Xiang Cheng, Huabin Li, Zhuoya Li, Arian Laurence, Guoping Wang, Xiang-Ping Yang
Immune checkpoint therapies have shown tremendous promise in cancer therapy. However, tools to assess their target engagement, and hence the ability to predict their efficacy, have been lacking. Here, we show that target engagement and tumor-residence kinetics of antibody therapeutics targeting programmed death ligand-1 (PD-L1) can be quantified noninvasively. In computational docking studies, we observed that PD-L1–targeted monoclonal antibodies (atezolizumab, avelumab, and durvalumab) and a high-affinity PD-L1–binding peptide, WL12, have common interaction sites on PD-L1. Using the peptide radiotracer [64Cu]WL12 in vivo, we employed positron emission tomography (PET) imaging and biodistribution studies in multiple xenograft models and demonstrated that variable PD-L1 expression and its saturation by atezolizumab, avelumab, and durvalumab can be quantified independently of biophysical properties and pharmacokinetics of antibodies. Next, we used [64Cu]WL12 to evaluate the impact of time and dose on the unoccupied fraction of tumor PD-L1 during treatment. These quantitative measures enabled, by mathematical modeling, prediction of antibody doses needed to achieve therapeutically effective occupancy (defined as >90%). Thus, we show that peptide-based PET is a promising tool for optimizing dose and therapeutic regimens employing PD-L1 checkpoint antibodies, and can be used for improving therapeutic efficacy.
Dhiraj Kumar, Ala Lisok, Elyes Dahmane, Matthew McCoy, Sagar Shelake, Samit Chatterjee, Viola Allaj, Polina Sysa-Shah, Bryan Wharram, Wojciech G. Lesniak, Ellen Tully, Edward Gabrielson, Elizabeth M. Jaffee, John T. Poirier, Charles M. Rudin, Jogarao V.S. Gobburu, Martin G. Pomper, Sridhar Nimmagadda