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 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 drive 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
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 single dose radiotherapy (SDRT), a disruptive technique that ablates >90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase (ASMase)-mediated microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction post-SDRT conferred an ischemic stress response within parenchymal tumor cells, with reactive oxygen species triggering the evolutionarily conserved SUMO Stress Response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensible for homology-directed repair (HDR) of DSBs, HDR loss-of-function post-SDRT yielded DSB unrepair, chromosomal aberrations and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging post-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 24Gy SDRT, but not 3x9Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing SDRT/ASMase signaling, as current studies indicate this pathway is tractable to pharmacologic intervention.
Sahra Bodo, Cecile 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 of 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. Herein we demonstrated that SRSF1 was increased in glioma tissues and cell lines. Moreover, its expression was correlated positively with tumor grade and Ki-67 index, but inversely with patients’ 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 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 MYO1B gene increased the tumorigenic potentials of glioma cells through the PDK1/AKT and PAK/LIMK pathways. Taken together, we identify SRSF1 as an important oncodriver, which integrates the AS controlling 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
Recurrent broad-scale heterozygous deletions are frequently observed in human cancer. Here we tested the hypothesis that compound haploinsufficiency of neighboring genes at chromosome 8p promotes tumorigenesis. By targeting the mouse orthologs of human DOK2 and DUSP4 genes, which were co-deleted in approximately half of human lung adenocarcinomas, we found that compound-heterozygous deletion of Dok2 and Dusp4 in mice resulted in lung tumorigenesis with short latency and high incidence, and that their co-deletion synergistically activated MAPK signaling and promoted cell proliferation. Conversely, restoration of DOK2 and DUSP4 in lung cancer cells suppressed MAPK activation and cell proliferation. Importantly, in contrast to downregulation of DOK2 or DUSP4 alone, concomitant downregulation of DOK2 and DUSP4 was associated with poor survival in human lung adenocarcinoma. Therefore, our findings lend in vivo experimental support to the notion that compound haploinsufficiency, due to broad-scale chromosome deletions, constitutes a driving force in tumorigenesis.
Ming Chen, Jiangwen Zhang, Alice H. Berger, Moussa S. Diolombi, Christopher Ng, Jacqueline Fung, Roderick T. Bronson, Mireia Castillo-Martin, Tin Htwe Thin, Carlos Cordon-Cardo, Robin Plevin, Pier Paolo Pandolfi
Immune checkpoint therapies have shown tremendous promise in cancer therapy. However, tools to assess their target engagement, and hence ability to predict their efficacy, have been lacking. Here, we show that target engagement and tumor residence kinetics of antibody therapeutics targeting the programmed death ligand-1 (PD-L1) can be quantified non-invasively. In computational docking studies, we observed that PD-L1-targeted antibodies (atezolizumab, avelumab, 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 independent of biophysical properties and pharmacokinetics of antibodies. Next, we used [64Cu]WL12 to evaluate the impact of time and dose on free fraction of tumor PD-L1 levels 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 D. 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
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 lactate, a metabolite found in high concentration within the anaerobic tumor environment, activated mTORC1 that subsequently suppressed TFEB-mediated expression of a 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
The aging-associated increase of cancer risk is linked with stromal fibroblast senescence and concomitant cancer-associated fibroblast (CAF) activation. Surprisingly little is known about the role of androgen receptor (AR) signaling in this context. We have found downmodulated AR expression in dermal fibroblasts underlying premalignant skin cancer lesions (actinic keratoses and dysplastic nevi) as well as in CAFs from the 3 major skin cancer types, squamous cell carcinomas (SCCs), basal cell carcinomas, and melanomas. Functionally, decreased AR expression in primary human dermal fibroblasts (HDFs) from multiple individuals induced early steps of CAF activation, and in an orthotopic skin cancer model, AR loss in HDFs enhanced tumorigenicity of SCC and melanoma cells. Forming a complex, AR converged with CSL/RBP-Jκ in transcriptional repression of key CAF effector genes. AR and CSL were positive determinants of each other’s expression, with BET inhibitors, which counteract the effects of decreased CSL, restoring AR expression and activity in CAFs. Increased AR expression in these cells overcame the consequences of CSL loss and was by itself sufficient to block the growth and tumor-enhancing effects of CAFs on neighboring cancer cells. As such, the findings establish AR as a target for stroma-focused cancer chemoprevention and treatment.
Andrea Clocchiatti, Soumitra Ghosh, Maria-Giuseppina Procopio, Luigi Mazzeo, Pino Bordignon, Paola Ostano, Sandro Goruppi, Giulia Bottoni, Atul Katarkar, Mitchell Levesque, Peter Kölblinger, Reinhard Dummer, Victor Neel, Berna C. Özdemir, G. Paolo Dotto
After the initial responsiveness of triple-negative breast cancers (TNBCs) to chemotherapy, they often recur as chemotherapy-resistant tumors, and this has been associated with upregulated homology-directed repair (HDR). Thus, inhibitors of HDR could be a useful adjunct to chemotherapy treatment of these cancers. We performed a high-throughput chemical screen for inhibitors of HDR from which we obtained a number of hits that disrupted microtubule dynamics. We postulated that high levels of the target molecules of our screen in tumors would correlate with poor chemotherapy response. We found that inhibition or knockdown of dynamin 2 (DNM2), known for its role in endocytic cell trafficking and microtubule dynamics, impaired HDR and improved response to chemotherapy of cells and of tumors in mice. In a retrospective analysis, levels of DNM2 at the time of treatment strongly predicted chemotherapy outcome for estrogen receptor–negative and especially for TNBC patients. We propose that DNM2-associated DNA repair enzyme trafficking is important for HDR efficiency and is a powerful predictor of sensitivity to breast cancer chemotherapy and an important target for therapy.
Sophia B. Chernikova, Rochelle B. Nguyen, Jessica T. Truong, Stephano S. Mello, Jason H. Stafford, Michael P. Hay, Andrew Olson, David E. Solow-Cordero, Douglas J. Wood, Solomon Henry, Rie von Eyben, Lei Deng, Melanie Hayden Gephart, Asaithamby Aroumougame, Claudia Wiese, John C. Game, Balázs Győrffy, J. Martin Brown
Replicative immortality is a hallmark of cancer governed by telomere maintenance. About 90% of human cancers maintain their telomeres by activating telomerase, driven by transcriptional upregulation of telomerase reverse transcriptase (TERT). Although TERT promoter mutations (TPMs) are a major cancer-associated genetic mechanism of TERT upregulation, many cancers exhibit TERT upregulation without TPMs. In this study, we described TERT Hypermethylated Oncological Region (THOR), a 433-bp genomic region encompassing 52 CpG sites located immediately upstream of the TERT core promoter, as a cancer-associated epigenetic mechanism of TERT upregulation. Unmethylated THOR repressed TERT promoter activity regardless of TPMs status, and hypermethylation of THOR counteracted this repressive function. THOR methylation analysis in 1,352 human tumors revealed frequent (>45%) cancer-associated DNA hypermethylation in 9 of 11 (82%) tumor types screened. Additionally, THOR hypermethylation — either independently or along with TPMs — accounted for how approximately 90% of human cancers can aberrantly activate telomerase. Thus, we propose THOR hypermethylation as a prevalent telomerase activating mechanism in cancer that can act independently or in conjunction with TPMs, further supporting the utility of THOR hypermethylation as a prognostic biomarker.
Donghyun D. Lee, Ricardo Leão, Martin Komosa, Marco Gallo, Cindy H. Zhang, Tatiana Lipman, Marc Remke, Abolfazl Heidari, Nuno Miguel Nunes, Joana D. Apolónio, Ramon Andrade De Mello, João Dias, David Huntsman, Thomas Hermanns, Peter J. Wild, Robert Vanner, Gelareh Zadeh, Jason Karamchandani, Sunit Das, Michael D. Taylor, Cynthia E. Hawkins, Jonathan D. Wasserman, Arnaldo Figueiredo, Robert J. Hamilton, Mark D. Minden, Khalida Wani, Bill Diplas, Hai Yan, Kenneth Aldape, Mohammad R. Akbari, Arnavaz Danesh, Trevor J. Pugh, Peter B. Dirks, Pedro Castelo-Branco, Uri Tabori
Tumor-associated myeloid cells maintain immunosuppressive microenvironments within tumors. Identification of myeloid-specific receptors to modulate tumor-associated macrophage and myeloid-derived suppressor cell (MDSC) functions remains challenging. The leukocyte immunoglobulin-like receptor B (LILRB) family members are negative regulators of myeloid cell activation. We investigated how LILRB targeting could modulate tumor-associated myeloid cell function. LILRB2 antagonism inhibited receptor-mediated activation of SHP1/2 and enhanced proinflammatory responses. LILRB2 antagonism also inhibited AKT and STAT6 activation in the presence of M-CSF and IL-4. Transcriptome analysis revealed that LILRB2 antagonism altered genes involved in cell cytoskeleton remodeling, lipid/cholesterol metabolism, and endosomal sorting pathways, as well as changed differentiation gene networks associated with inflammatory myeloid cells as opposed to their alternatively activated phenotype. LILRB2 blockade effectively suppressed granulocytic MDSC and Treg infiltration and significantly promoted in vivo antitumor effects of T cell immune checkpoint inhibitors. Furthermore, LILRB2 blockade polarized tumor-infiltrating myeloid cells from non–small cell lung carcinoma tumor tissues toward an inflammatory phenotype. Our studies suggest that LILRB2 can potentially act as a myeloid immune checkpoint by reprogramming tumor-associated myeloid cells and provoking antitumor immunity.
Hui-Ming Chen, William van der Touw, Yuan Shuo Wang, Kyeongah Kang, Sunny Mai, Jilu Zhang, Dayanira Alsina-Beauchamp, James A. Duty, Sathish Kumar Mungamuri, Bin Zhang, Thomas Moran, Richard Flavell, Stuart Aaronson, Hong-Ming Hu, Hisashi Arase, Suresh Ramanathan, Raja Flores, Ping-Ying Pan, Shu-Hsia Chen