Disordered lysosomal/autophagy pathways initiate and drive pancreatitis, but the underlying mechanisms and links to disease pathology are poorly understood. Here, we show that mannose-6-phosphate (M6P) pathway of hydrolase delivery to lysosomes critically regulates pancreatic acinar cell cholesterol metabolism. Ablation of the Gnptab gene coding for a key enzyme in M6P pathway disrupted acinar cell cholesterol turnover, causing accumulation of non-esterified cholesterol in lysosomes/autolysosomes, its’ depletion in the plasma membrane, and upregulation of cholesterol synthesis and uptake. We found similar dysregulation of acinar cell cholesterol, and a decrease in GNPTAB levels, in both WT experimental pancreatitis and human disease. The mechanisms mediating pancreatic cholesterol dyshomeostasis in Gnptab-/- and experimental models involve disordered endolysosomal system, resulting in impaired cholesterol transport through lysosomes and blockage of autophagic flux. By contrast, in Gnptab-/- liver the endolysosomal system and cholesterol homeostasis were largely unaffected. Gnptab-/- mice developed spontaneous pancreatitis. Normalization of cholesterol metabolism by pharmacologic means alleviated responses of experimental pancreatitis, particularly trypsinogen activation, the disease hallmark. The results reveal the essential role of M6P pathway in maintaining exocrine pancreas homeostasis and function, and implicate cholesterol disordering in the pathogenesis of pancreatitis.
Olga A. Mareninova, Eszter T. Vegh, Natalia Shalbueva, Carli J.M. Wightman, Dustin L. Dillon, Sudarshan Malla, Yan Xie, Toshimasa Takahashi, Zoltan Rakonczay Jr, Samuel W. French, Herbert Y. Gaisano, Frederick Sanford Gorelick, Stephen J. Pandol, Steven J. Bensinger, Nicholas O. Davidson, David W. Dawson, Ilya Gukovsky, Anna S. Gukovskaya
Androgen receptor (AR)-positive prostate cancers (PCa) and estrogen receptor (ER)-positive luminal breast cancers (BCa) are generally less responsive to immunotherapy compared to certain tumor types such as melanoma. However, the underlying mechanisms are not fully elucidated. Here we found that FOXA1 overexpression inversely correlated with interferon (IFN) signature and antigen presentation gene expression in PCa and BCa patients. FOXA1 bound STAT2 DNA binding domain and suppressed STAT2 DNA binding activity, IFN signaling gene expression and cancer immune response independently of the transactivation activity of FOXA1 and its mutations detected in prostate and breast cancers. Increased FOXA1 expression promoted cancer immuno- and chemotherapy resistance in mice and PCa and BCa patients. These findings were also validated in bladder cancer expressing high level FOXA1. FOXA1 overexpression could be a prognostic factor to predict therapy resistance and a viable target to sensitize luminal prostate, breast and bladder cancer to immuno- and chemotherapy.
Yundong He, Liguo Wang, Ting Wei, Yu-Tian Xiao, Haoyue Sheng, Hengchuan Su, Daniel P. Hollern, Xiaoling Zhang, Jian Ma, Simeng Wen, Hongyan Xie, Yuqian Yan, Yunqian Pan, Xiaonan Hou, Xiaojia Tang, Vera J. Suman, Jodi M. Carter, Richard Weinshilboum, Liewei Wang, Krishna R. Kalari, Saravut J. Weroha, Alan H. Bryce, Judy C. Boughey, Haidong Dong, Charles M. Perou, Dingwei Ye, Matthew P. Goetz, Shancheng Ren, Haojie Huang
Phoebe Carter, Ulrike Schnell, Christopher Chaney, Betty Tong, Xinchao Pan, Jianhua Ye, Glenda Mernaugh, Jennifer L. Cotton, Vitaly Margulis, Junhao Mao, Roy Zent, Bret M. Evers, Payal Kapur, Thomas J. Carroll
Hypoxia, a hallmark feature of the tumor microenvironment, causes resistance to conventional chemotherapy, but was recently reported to synergize with poly(ADP-ribose) polymerase inhibitors (PARPis) in homologous recombination–proficient (HR-proficient) cells through suppression of HR. While this synergistic killing occurs under severe hypoxia (<0.5% oxygen), our study shows that moderate hypoxia (2% oxygen) instead promotes PARPi resistance in both HR-proficient and -deficient cancer cells. Mechanistically, we identify reduced ROS-induced DNA damage as the cause for the observed resistance. To determine the contribution of hypoxia to PARPi resistance in tumors, we used the hypoxic cytotoxin tirapazamine to selectively kill hypoxic tumor cells. We found that the selective elimination of hypoxic tumor cells led to a substantial antitumor response when used with PARPi compared with that in tumors treated with PARPi alone, without enhancing normal tissue toxicity. Since human breast cancers with BRAC1/2 mutations have an increased hypoxia signature and hypoxia reduces the efficacy of PARPi, then eliminating hypoxic tumor cells should enhance the efficacy of PARPi therapy.
Manal Mehibel, Yu Xu, Caiyun G. Li, Eui Jung Moon, Kaushik N. Thakkar, Anh N. Diep, Ryan K. Kim, Joshua D. Bloomstein, Yiren Xiao, Julien Bacal, Joshua C. Saldivar, Quynh-Thu Le, Karlene A. Cimprich, Erinn B. Rankin, Amato J. Giaccia
Cerebral cavernous malformations (CCMs) are common neurovascular lesions caused by loss-of-function mutations in one of three genes, including KRIT1 (CCM1), CCM2, and PDCD10 (CCM3), and generally regarded as an endothelial cell-autonomous disease. Here we reported that proliferative astrocytes played a critical role in CCM pathogenesis by serving as a major source of VEGF during CCM lesion formation. An increase in astrocyte VEGF synthesis is driven by endothelial nitric oxide (NO) generated as a consequence of KLF2 and KLF4-dependent elevation of eNOS in CCM endothelium. The increased brain endothelial production of NO stabilized HIF-1a in astrocytes, resulting in increased VEGF production and expression of a “hypoxic” program under normoxic conditions. We showed that the upregulation of cyclooxygenase-2 (COX-2), a direct HIF-1a target gene and a known component of the hypoxic program, contributed to the development of CCM lesions because the administration of a COX-2 inhibitor significantly prevented the progression of CCM lesions. Thus, non-cell-autonomous crosstalk between CCM endothelium and astrocytes propels vascular lesion development, and components of the hypoxic program represent potential therapeutic targets for CCMs.
Miguel Alejandro Lopez-Ramirez, Catherine Chinhchu Lai, Shady Ibrahim Soliman, Preston Hale, Angela Pham, Esau J. Estrada, Sara McCurdy, Romuald Girard, Riya Verma, Thomas Moore, Rhonda Lightle, Nicholas Hobson, Robert Shenkar, Orit Poulsen, Gabriel G. Haddad, Richard Daneman, Brendan Gongol, Hao Sun, Frederic Lagarrigue, Issam A. Awad, Mark H. Ginsberg
Cutaneous melanoma remains the most lethal skin cancer, and ranks third among all malignancies in terms of years of life lost. Despite the advent of immune checkpoint and targeted therapies, only roughly half of patients with advanced melanoma achieves a durable remission. SIRT5 is a member of the sirtuin family of protein deacylases that regulate metabolism and other biological processes. Germline Sirt5 deficiency is associated with mild phenotypes in mice. Here we show that SIRT5 is required for proliferation and survival across all cutaneous melanoma genotypes tested, as well as uveal melanoma, a genetically distinct melanoma subtype that arises in the eye and is incurable once metastatic. Likewise, SIRT5 is required for efficient tumor formation by melanoma xenografts and in an autochthonous mouse Braf;Pten-driven melanoma model. Via metabolite and transcriptomic analyses, we find that SIRT5 is required to maintain histone acetylation and methylation levels in melanoma cells, thereby promoting proper gene expression. SIRT5-dependent genes notably include MITF, a key lineage-specific survival oncogene in melanoma, and the c-MYC proto-oncogene. SIRT5 may represent a novel, druggable genotype-independent addiction in melanoma.
William Giblin, Lauren Bringman-Rodenbarger, Angela H. Guo, Surinder Kumar, Alexander C. Monovich, Ahmed M. Mostafa, Mary E. Skinner, Michelle Azar, Ahmed S.A. Mady, Carolina H. Chung, Namrata Kadambi, Keith-Allen Melong, Ho-Joon Lee, Li Zhang, Peter Sajjakulnukit, Sophie Trefely, Erika L. Varner, Sowmya Iyer, Min Wang, James S. Wilmott, H. Peter Soyer, Richard A. Sturm, Antonia L. Pritchard, Aleodor A. Andea, Richard A. Scolyer, Mitchell S. Stark, David A. Scott, Douglas R. Fullen, Marcus W. Bosenberg, Sriram Chandrasekaran, Zaneta Nikolovska-Coleska, Monique E. Verhaegen, Nathaniel W. Snyder, Miguel N. Rivera, Andrei Osterman, Costas A. Lyssiotis, David B. Lombard
Immune checkpoint blockade therapy has demonstrated promising clinical outcomes for multiple cancer types. However, the emergence of resistance as well as inadequate biomarkers for patient stratification have largely limited the clinical benefits. Here, we showed that tumors with high TYRO3 expression exhibited anti–programmed cell death protein 1/programmed death ligand 1 (anti–PD-1/PD-L1) resistance in a syngeneic mouse model and in patients who received anti–PD-1/PD-L1 therapy. Mechanistically, TYRO3 inhibited tumor cell ferroptosis triggered by anti–PD-1/PD-L1 and facilitated the development of a protumor microenvironment by reducing the M1/M2 macrophage ratio, resulting in resistance to anti–PD-1/PD-L1 therapy. Inhibition of TYRO3 promoted tumor ferroptosis and sensitized resistant tumors to anti–PD-1 therapy. Collectively, our findings suggest that TYRO3 could serve as a predictive biomarker for patient selection and a promising therapeutic target to overcome anti–PD-1/PD-L1 resistance.
Zhou Jiang, Seung-Oe Lim, Meisi Yan, Jennifer L. Hsu, Jun Yao, Yongkun Wei, Shih-Shin Chang, Hirohito Yamaguchi, Heng-Huan Lee, Baozhen Ke, Jung-Mao Hsu, Li-Chuan Chan, Gabriel N. Hortobagyi, Liuqing Yang, Chunru Lin, Dihua Yu, Mien-Chie Hung
SUMOylation emerged as the inducer for the sorting of bioactive molecules into extracellular vesicles (EVs) triggering lymphangiogenesis, further driving tumor lymph node (LN) metastasis, but the precise mechanisms remain largely unclear. Herein, we identified that bladder cancer (BCa) cell-secreted EVs mediated the intercellular communication with human lymphatic endothelial cells (HLECs) through the transmission of a long noncoding RNA ELNAT1, and promoted lymphangiogenesis and LN metastasis in a SUMOylation-dependent manner in both cultured BCa cell lines and mouse models. Mechanistically, ELNAT1 induced UBC9 overexpression to catalyze the SUMOylation of hnRNPA1 at lysine-113 residue, which mediated the recognition of ELNAT1 by endosomal sorting complex required for transport (ESCRT) and facilitated their packaging into EVs. EV-mediated ELNAT1 was specifically transmitted into HLECs and epigenetically activated SOX18 transcription to induce lymphangiogenesis. Importantly, blocking the SUMOylation of tumor by downregulating UBC9 expression markedly reduced lymphatic metastasis in EV-mediated ELNAT1-treated BCa in vivo. Clinically, EV-mediated ELNAT1 was correlated with LN metastasis and poor prognosis of patients with BCa. These findings highlight a molecular mechanism that EV-mediated ELNAT1/UBC9/SOX18 regulatory axis promotes the lymphangiogenesis and LN metastasis of BCa in a SUMOylation-dependent manner, and implicate ELNAT1 as an attractive therapeutic target for LN metastatic BCa.
Changhao Chen, Hanhao Zheng, Yuming Luo, Yao Kong, Mingjie An, Yuting Li, Wang He, Bowen Gao, Yue Zhao, Hao Huang, Jian Huang, Tianxin Lin
Efferocytosis, the process through which apoptotic cells (ACs) are cleared through actin-mediated engulfment by macrophages, prevents secondary necrosis, suppresses inflammation, and promotes resolution. Impaired efferocytosis drives the formation of clinically dangerous necrotic atherosclerotic plaques, the underlying etiology of coronary artery disease (CAD). An intron of the gene encoding PHACTR1 contains a common variant rs9349379 (A > G) associated with CAD. As PHACTR1 is an actin-binding protein, we reasoned that if the rs9349379 risk allele G causes lower PHACTR1 expression in macrophages, it might link the risk-allele to CAD via impaired efferocytosis. We show here that rs9349379-G/G was associated with lower levels of PHACTR1 and impaired efferocytosis in human monocyte-derived macrophages and human atherosclerotic lesional macrophages compared with rs9349379-A/A. Silencing PHACTR1 in human and mouse macrophages compromised AC engulfment, and mice in which hematopoietic Phactr1 was genetically targeted in Western diet-fed Ldlr-/- mice showed impaired lesional efferocytosis, increased plaque necrosis, and thinner fibrous caps—all signs of vulnerable plaques in humans. Mechanistically, PHACTR1 prevented dephosphorylation of myosin light chain (MLC), which was necessary for AC engulfment. In summary, rs9349379-G lowers PHACTR1, which, by lowering phospho-MLC, compromised efferocytosis. Thus, rs9349379-G may contribute to CAD risk, at least in part, by impairing atherosclerotic lesional macrophage efferocytosis.
Canan Kasikara, Maaike Schilperoort, Brennan D. Gerlach, Chenyi Xue, Xiaobo Wang, Ze Zheng, George Kuriakose, Bernhard Dorweiler, Hanrui Zhang, Gabrielle Fredman, Danish Saleheen, Muredach P Reilly, Ira Tabas
Cx43, a major cardiac connexin, forms precursor hemichannels that accrue at the intercalated disc to assemble as gap junctions. While gap junctions are crucial for electrical conduction in the heart, little is known on potential roles of hemichannels. Recent evidence suggests that inhibiting Cx43 hemichannel opening with Gap19 has antiarrhythmic effects. Here, we used multiple electrophysiology, imaging and super-resolution techniques to understand and define the conditions underlying Cx43 hemichannel activation in ventricular cardiomyocytes, their contribution to diastolic Ca2+ release from the sarcoplasmic reticulum, and their impact on electrical stability. We showed that Cx43 hemichannels are activated during diastolic Ca2+ release in single ventricular cardiomyocytes and cardiomyocyte cell pairs from mouse and pig. This activation involved Cx43 hemichannel Ca2+ entry and coupling to Ca2+ release microdomains at the intercalated disc resulting in enhanced Ca2+ dynamics. Hemichannel opening furthermore contributed to delayed afterdepolarizations and triggered action potentials. In single cardiomyocytes, cardiomyocyte cell pairs and arterially perfused tissue wedges from failing human hearts, increased hemichannel activity contributed to electrical instability as compared to non-failing rejected donor hearts. We conclude that microdomain coupling between Cx43 hemichannels and Ca2+ release is a novel, targetable, mechanism of cardiac arrhythmogenesis in heart failure.
Maarten A.J. De Smet, Alessio Lissoni, Timur Nezlobinsky, Nan Wang, Eef Dries, Marta Pérez-Hernández, Xianming Lin, Matthew Amoni, Tim Vervliet, Katja Witschas, Eli Rothenberg, Geert Bultynck, Rainer Schulz, Alexander V. Panfilov, Mario Delmar, Karin R. Sipido, Luc Leybaert
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