The origin of breast cancer, whether primary or recurrent, is unknown. Here, we show that invasive breast cancer cells exposed to hypoxia release small extracellular vesicles (sEV) that disrupt the differentiation of normal mammary epithelia, expand stem and luminal progenitor cells, and induce atypical ductal hyperplasia and intraepithelial neoplasia. This was accompanied by systemic immunosuppression with increased myeloid cell release of the “alarmin”, S100A9, and oncogenic traits of EMT, angiogenesis, and local and disseminated luminal cell invasion, in vivo. In the presence of a mammary gland driver oncogene (MMTV-PyMT), hypoxic sEV accelerated bilateral breast cancer onset and progression. Mechanistically, genetic or pharmacologic targeting of hypoxia-inducible factor-1α (HIF1α) packaged in hypoxic sEV, or homozygous deletion of S100A9 normalized mammary gland differentiation, restored T cell function and prevented atypical hyperplasia. The transcriptome of sEV-induced mammary gland lesions resembled luminal breast cancer, and detection of HIF1α in plasma circulating sEV from luminal breast cancer patients correlated with disease recurrence. Therefore, sEV-HIF1α signaling drives both local and systemic mechanisms of mammary gland transformation at high risk for evolution to multifocal breast cancer. This pathway may provide a readily accessible biomarker of luminal breast cancer progression.
Irene Bertolini, Michela Perego, Yulia Nefedova, Cindy Lin, Andrew T. Milcarek, Peter Vogel, Jagadish C. Ghosh, Andrew V. Kossenkov, Dario C. Altieri
Defects in primary or motile cilia result in a variety of human pathologies, and retinal degeneration is frequently associated with these so-called ciliopathies. We found that homozygosity for a truncating variant in CEP162, a centrosome and microtubule-associated protein required for transition zone assembly during ciliogenesis and neuronal differentiation in the retina, caused late-onset retinitis pigmentosa in 2 unrelated families. The mutant CEP162-E646R*5 protein was expressed and properly localized to the mitotic spindle, but was missing from the basal body in primary and photoreceptor cilia. This impaired recruitment of transition zone components to the basal body and corresponded to complete loss of CEP162 function at the ciliary compartment, reflected by delayed formation of dysmorphic cilia. In contrast, shRNA knockdown of Cep162 in the developing mouse retina increased cell death, which was rescued by expression of CEP162-E646R*5, indicating that the mutant retains its role for retinal neurogenesis. Human retinal degeneration thus resulted from specific loss of the ciliary function of CEP162.
Nafisa Nuzhat, Kristof Van Schil, Sandra Liakopoulos, Miriam Bauwens, Alfredo Dueñas Rey, Stephan Käseberg, Melanie Jäger, Jason R. Willer, Jennifer Winter, Hanh M. Truong, Nuria Gruartmoner, Mattias Van Heetvelde, Joachim C. Wolf, Robert Merget, Sabine Grasshoff-Derr, Jo Van Dorpe, Anne Hoorens, Heidi Stöhr, Luke Mansard, Anne-Françoise Roux, Thomas Langmann, Katharina Dannhausen, David Rosenkranz, Karl M. Wissing, Michel Van Lint, Heidi Rossmann, Friederike Häuser, Peter Nürnberg, Holger Thiele, Ulrich Zechner, Jillian N. Pearring, Elfride De Baere, Hanno J. Bolz
Calmodulin (CaM) plays critical roles in cardiomyocytes, regulating Na+ (NaV) and L-type Ca2+ channels (LTCC). LTCC dysregulation by mutant CaMs has been implicated in action potential duration (APD) prolongation and arrhythmogenic long QT (LQT) syndrome. Intriguingly, D96V-CaM prolongs APD more than other LQT-associated CaMs despite inducing comparable levels of LTCC dysfunction, suggesting dysregulation of other depolarizing channels. Here, we provide evidence implicating NaV dysregulation within transverse (T)-tubules in D96V-CaM-associated arrhythmias. D96V-CaM induces pro-arrhythmic late Na+ current (INa) by impairing inactivation of NaV1.6, but not the predominant cardiac NaV isoform, NaV1.5. We investigated arrhythmia mechanisms using mice with cardiac-specific expression of D96V-CaM (cD96V). Super-resolution microscopy revealed close proximity of NaV1.6 and RyR2 within T-tubules. NaV1.6 density within these regions increased in cD96V relative to WT. Consistent with NaV1.6 dysregulation by D96V-CaM in these regions, we observed increased late NaV activity in T-tubules. The resulting late INa promoted aberrant Ca2+ release and prolonged APD in myocytes, leading to LQT and ventricular tachycardia (VT) in vivo. Cardiac-specific NaV1.6 knockout protected cD96V mice from increased T-tubular late NaV activity, and its arrhythmogenic consequences. In summary, we demonstrate that D96V-CaM promotes arrhythmias by dysregulating LTCC and NaV1.6 within T-tubules and thereby, facilitating aberrant Ca2+ release.
Mikhail Tarasov, Heather L. Struckman, Yusuf Olgar, Alec Miller, Mustafa Demirtas, Vladimir Bogdanov, Radmila Terentyeva, Andrew M. Soltisz, Xiaolei Meng, Dennison Min, Galina Sakuta, Izabella Dunlap, Antonia D. Duran, Mark P. Foster, Jonathan P. Davis, Dmitry Terentyev, Sándor Györke, Rengasayee Veeraraghavan, Przemysław B. Radwański
Although protein hydroxylation is a relatively poorly characterized post-translational modification, it has received significant recent attention following seminal work uncovering its role in oxygen sensing and hypoxia biology. Although the fundamental importance of protein hydroxylases in biology is becoming clear, the biochemical targets and cellular functions often remain enigmatic. JMJD5 is a ‘JmjC-only’ protein hydroxylase that is essential for murine embryonic development and viability. However, no germline variants in JmjC-only hydroxylases, including JMJD5, have yet been described that are associated with any human pathology. Here we demonstrate that biallelic germline JMJD5 pathogenic variants are deleterious to JMJD5 mRNA splicing, protein stability, and hydroxylase activity, resulting in a human developmental disorder characterised by severe failure to thrive, intellectual disability, and facial dysmorphism. We show that the underlying cellular phenotype is associated with increased DNA replication stress and that this is critically dependent on the protein hydroxylase activity of JMJD5. This work contributes to our growing understanding of the role and importance of protein hydroxylases in human development and disease.
Sally C. Fletcher, Charlotte L. Hall, Tristan J. Kennedy, Sander Pajusalu, Monica H. Wojcik, Uncaar Boora, Chan Li, Kaisa Teele Oja, Eline Hendrix, Christian A.E. Westrip, Regina Andrijes, Sonia K. Piasecka, Mansi Singh, Mohammed E. El-Asrag, Anetta Ptasinska, Vallo Tillmann, Martin R. Higgs, Deanna Alexis Carere, Andrew D. Beggs, John Pappas, Rachel Rabin, Stephen J. Smerdon, Grant S. Stewart, Katrin Õunap, Mathew L. Coleman
Hypersecretory malignant cells underlie therapeutic resistance, metastasis, and poor clinical outcomes. However, the molecular basis for malignant hypersecretion remains obscure. Here, we showed that epithelial-to-mesenchymal transition (EMT) initiates exocytic and endocytic vesicular trafficking programs in lung cancer. The EMT-activating transcription factor ZEB1 executed a PI4KIIIβ-to-PI4KIIα (PI4K2A)-dependency switch that drove PI4P synthesis in Golgi and endosomes. EMT enhanced the vulnerability of lung cancer cells to PI4K2A small molecule antagonists. PI4K2A formed a MYOIIA-containing protein complex that facilitated secretory vesicle biogenesis in the Golgi, thereby establishing a hypersecretory state involving osteopontin (SPP1) and other pro-metastatic ligands. In the endosomal compartment, PI4K2A accelerated recycling of SPP1 receptors to complete an SPP1-dependent autocrine loop and interacted with HSP90 to prevent lysosomal degradation of AXL receptor tyrosine kinase, a driver of cell migration. These results show that EMT coordinates exocytic and endocytic vesicular trafficking to establish a therapeutically actionable hypersecretory state that drives lung cancer progression.
Xiaochao Tan, Guan-Yu Xiao, Shike Wang, Lei Shi, Yanbin Zhao, Xin Liu, Jiang Yu, William K. Russell, Chad J. Creighton, Jonathan M. Kurie
Tumor suppressor TP53 is the most frequently mutated gene in human cancers. Mutant p53 (mutp53) proteins often accumulate to very high levels in human cancers to promote cancer progression through the gain-of-function (GOF) mechanism. Currently, the mechanism underlying mutp53 accumulation and GOF is incompletely understood. Here, we identified TRIM21 as a critical E3 ubiquitin ligase of mutp53 by screening for specific mutp53-interacting proteins. TRIM21 directly interacted with mutp53 but not wild-type p53, resulting in ubiquitination and degradation of mutp53 to suppress mutp53 GOF in tumorigenesis. TRIM21 deficiency in cancer cells promoted mutp53 accumulation and GOF in tumorigenesis. Compared with p53R172H knock-in mice, which displayed mutp53 accumulation specifically in tumors but not normal tissues, TRIM21 deletion in p53R172H knock-in mice resulted in mutp53 accumulation in normal tissues, an earlier tumor onset, and a shortened lifespan of mice. Furthermore, TRIM21 was frequently downregulated in some human cancers, including colorectal and breast cancers, and low TRIM21 expression was associated with poor prognosis in patients with cancers carrying mutp53. Our results revealed a critical mechanism underlying mutp53 accumulation in cancers, and also uncovered an important tumor-suppressive function of TRIM21 and its mechanism in cancers carrying mutp53.
Juan Liu, Cen Zhang, Dandan Xu, Tianliang Zhang, Chun-Yuan Chang, Jianming Wang, Jie Liu, Lanjing Zhang, Bruce G. Haffty, Wei-Xing Zong, Wenwei Hu, Zhaohui Feng
Programmed death-ligand 1 (PD-L1), a critical immune checkpoint ligand, is a transmembrane protein synthesized in the endoplasmic reticulum of tumor cells and transported to the plasma membrane to interact with programmed death 1 (PD-1) expressed on T cell surface. This interaction delivers coinhibitory signals to T cells, thereby suppressing their function and allowing evasion of antitumor immunity. Most companion or complementary diagnostic devices for assessing PD-L1 expression levels in tumor cells used in the clinic or in clinical trials require membranous staining. However, the mechanism driving PD-L1 translocation to the plasma membrane after de novo synthesis is poorly understood. Herein, we showed that mind bomb homolog 2 (MIB2) is required for PD-L1 transportation from the trans-Golgi network (TGN) to the plasma membrane of cancer cells. MIB2 deficiency led to fewer PD-L1 proteins on the tumor cell surface and promoted antitumor immunity in mice. Mechanistically, MIB2 catalyzed nonproteolytic K63-linked ubiquitination of PD-L1, facilitating PD-L1 trafficking through Ras-associated binding 8–mediated (RAB8-mediated) exocytosis from the TGN to the plasma membrane, where it bound PD-1 extrinsically to prevent tumor cell killing by T cells. Our findings demonstrate that nonproteolytic ubiquitination of PD-L1 by MIB2 is required for its transportation to the plasma membrane and tumor cell immune evasion.
Xinfang Yu, Wei Li, Haidan Liu, Xu Wang, Cristian Coarfa, Chao Cheng, Xinlian Yu, Zhaoyang Zeng, Ya Cao, Ken H. Young, Yong Li
SIPRα on macrophages binds with CD47 to resist pro-engulfment signals, but how the downstream signal of SIPRα controls tumor-infiltrating macrophages (TIMs) is still poorly clarified. Here we reported that the CD47/SIRPα axis requires the deneddylation of tyrosine phosphatase SHP2. Mechanistically, SHP2 is constitutively neddylated on K358 and K364 sites, thus its auto-inhibited conformation is maintained. In response to CD47-liganded SIRPα, SHP2 is deneddylated by SENP8, which leads to the dephosphorylation of relevant substrates at the phagocytic cup and subsequent inhibition of macrophage phagocytosis. Furthermore, neddylation inactivated myeloid-SHP2 and greatly boosted the efficacy of colorectal cancer (CRC) immunotherapy. Importantly, we observed that the supplementation with SHP2 allosteric inhibitors sensitized the immune treatment-resistant CRC to immunotherapy. Our results emphasized that the CRC subtype which is unresponsive to immunotherapy relies on SIRPαhiSHP2hiNEDD8lo TIMs, and highlighted the need to further combine the strategy of SHP2 targeting in colorectal cancer therapy.
Yiqing Li, Hui Zhou, Pan Liu, Dandan Lv, Yichun Shi, Bufu Tang, Jiaqi Xu, Tingting Zhong, Wangting Xu, Jie Zhang, Jianying Zhou, Kejing Ying, Yongchao Zhao, YI Sun, Zhinong Jiang, Hongqiang Cheng, Xue Zhang, Yue-Hai Ke
Ubiquitin-conjugating enzyme E2C (UBE2C) mediates the ubiquitylation chain formation via the K11 linkage. While previous in vitro studies showed that UBE2C plays a growth-promoting role in cancer cell lines, the underlying mechanism remains elusive. Still unknown is whether and how UBE2C plays a promoting role in vivo. Here we reported that UBE2C is indeed essential for growth and survival of lung cancer cells harboring Kras mutations, and UBE2C is required for KrasG12D-induced lung tumorigenesis, since Ube2c deletion significantly inhibits tumor formation and extends the life-span of mice. Mechanistically, KrasG12D induces expression of UBE2C, which couples with APC/CCDH1 E3 ligase to promote ubiquitylation and degradation of DEPTOR, leading to activation of the mTORC signals. Importantly, DEPTOR levels are fluctuated during cell cycle progression in a manner dependent of UBE2C and CDH1, indicating their physiological connection. Finally, Deptor deletion fully rescues the tumor inhibitory effect of Ube2c deletion in the KrasG12D lung tumor model, indicating a causal role of Deptor. Taken together, our study shows that the UBE2C/CDH1/DEPTOR axis forms an oncogene-tumor suppressor cascade that regulates cell cycle progression and autophagy and validates that UBE2C is an attractive target for lung cancer associated with Kras mutations.
Shizhen Zhang, Xiahong You, Yawen Zheng, Yanwen Shen, Xiufang Xiong, Yi Sun
Leptin exerts its biological actions by activating LepRb. LepRb signaling impairment and leptin resistance are believed to cause obesity. Transcription factor Slug (also known as Snai2) recruits epigenetic modifiers and regulates gene expression by an epigenetic mechanism; however, its epigenetic action has not been explored in leptin resistance. Here, we uncover a pro-obesity function of neuronal Slug. Hypothalamic Slug was upregulated in obese mice. LepRb cell-specific Slug knockout (SlugΔLepRb) mice were resistant to diet-induced obesity, type 2 diabetes, and liver steatosis, accompanied by decreased food intake and increased fat thermogenesis. Leptin stimulated hypothalamic Stat3 phosphorylation and weight loss to a significantly higher level in SlugΔLepRb than in Slugf/f mice even before their body weight divergence. Conversely, hypothalamic LepRb neuron-specific overexpression of Slug, mediated by AAV-DIO-Slug transduction, induced leptin resistance, obesity, and metabolic disorders in mice on a chow diet. At the genomic level, Slug bound to and repressed the LepRb promoter, thereby inhibiting LepRb transcription. Consistently, Slug deficiency decreased LepRb promoter histone 3 lysine-27 methylations, repressive epigenetic marks, and increased LepRb mRNA levels in the hypothalamus. Collectively, these results unravel a previously-unrecognized hypothalamic neuronal Slug/epigenetic reprogramming/leptin resistance axis that promotes energy imbalance, obesity, and metabolic disease.
Min-Hyun Kim, Yuan Li, Qiantao Zheng, Lin Jiang, Martin G. Myers, Wen-Shu Wu, Liangyou Rui
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