bims-lymeca 2022-05-08 papers

bims-lymeca

Biomed News

on Lysosome metabolism in cancer

Issue of 2022–05–08
twelve papers selected by
Harilaos Filippakis, Harvard University

The V-ATPases in cancer and cell death.
Proteotoxic stress disrupts epithelial integrity by inducing MTOR sequestration and autophagy overactivation.
VAMP8 phosphorylation regulates lysosome dynamics during autophagy.
No Back-up Plan: Loss of Isozyme Diversity as a Promising Therapeutic Strategy for Cancer.
De Novo Labeling and Trafficking of Individual Lipid Species in Live Cells.
MITF deficiency accelerates GNAQ-driven uveal melanoma.
Cardiac glycosides stimulate endocytosis of GLUT1 via intracellular Na+ ,K+ -ATPase α3-isoform in human cancer cells.
Rab33b-exocyst interaction mediates localized secretion for focal adhesion turnover and cell migration.
The AMPK-related kinase NUAK2 suppresses glutathione peroxidase 4 expression and promotes ferroptotic cell death in breast cancer cells.
Inhibition of TFEB promotes tumor-educated dendritic cells activation to enhance antitumor immune responses.
Glycosylated Cathepsin V Serves as a Prognostic Marker in Lung Cancer.
p53 alters intracellular Ca2+ signaling through regulation of TRPM4.

Cancer Gene Ther. 2022 May 03.

The V-ATPases in cancer and cell death.

Fangquan Chen, Rui Kang, Jiao Liu, Daolin Tang.

Transmembrane ATPases are membrane-bound enzyme complexes and ion transporters that can be divided into F-, V-, and A-ATPases according to their structure. The V-ATPases, also known as H+-ATPases, are large multi-subunit protein complexes composed of a peripheral domain (V1) responsible for the hydrolysis of ATP and a membrane-integrated domain (V0) that transports protons across plasma membrane or organelle membrane. V-ATPases play a fundamental role in maintaining pH homeostasis through lysosomal acidification and are involved in modulating various physiological and pathological processes, such as macropinocytosis, autophagy, cell invasion, and cell death (e.g., apoptosis, anoikis, alkaliptosis, ferroptosis, and lysosome-dependent cell death). In addition to participating in embryonic development, V-ATPase pathways, when dysfunctional, are implicated in human diseases, such as neurodegenerative diseases, osteopetrosis, distal renal tubular acidosis, and cancer. In this review, we summarize the structure and regulation of isoforms of V-ATPase subunits and discuss their context-dependent roles in cancer biology and cell death. Updated knowledge about V-ATPases may enable us to design new anticancer drugs or strategies.

DOI: https://doi.org/10.1038/s41417-022-00477-y
Autophagy. 2022 May 06. 1-15

Proteotoxic stress disrupts epithelial integrity by inducing MTOR sequestration and autophagy overactivation.

Xiaoxiang Cheng, Pei Zhang, Hongyu Zhao, Hui Zheng, Kai Zheng, Hong Zhang, Hongjie Zhang.

  Macroautophagy/autophagy, an evolutionarily conserved degradation system, serves to clear intracellular components through the lysosomal pathway. Mounting evidence has revealed cytoprotective roles of autophagy; however, the intracellular causes of overactivated autophagy, which has cytotoxic effects, remain elusive. Here we show that sustained proteotoxic stress induced by loss of the RING and Kelch repeat-containing protein C53A5.6/RIKE-1 induces sequestration of LET-363/MTOR complex and overactivation of autophagy, and consequently impairs epithelial integrity in C. elegans. In C53A5.6/RIKE-1-deficient animals, blocking autophagosome formation effectively prevents excessive endosomal degradation, mitigates mislocalization of intestinal membrane components and restores intestinal lumen morphology. However, autophagy inhibition does not affect LET-363/MTOR aggregation in animals with compromised C53A5.6/RIKE-1 function. Improving proteostasis capacity by reducing DAF-2 insulin/IGF1 signaling markedly relieves the aggregation of LET-363/MTOR and alleviates autophagy overactivation, which in turn reverses derailed endosomal trafficking and rescues epithelial morphogenesis defects in C53A5.6/RIKE-1-deficient animals. Hence, our studies reveal that C53A5.6/RIKE-1-mediated proteostasis is critical for maintaining the basal level of autophagy and epithelial integrity.Abbreviations: ACT-5: actin 5; ACTB: actin beta; ALs: autolysosomes; APs: autophagosomes; AJM-1: apical junction molecule; ATG: autophagy related; C. elegans: Caenorhabditis elegans; CPL-1: cathepsin L family; DAF: abnormal dauer formation; DLG-1: Drosophila discs large homolog; ERM-1: ezrin/radixin/moesin; EPG: ectopic P granule; GFP: freen fluorescent protein; HLH-30: helix loop helix; HSP: heat shock protein; LAAT-1: lysosome associated amino acid transporter; LET: lethal; LGG-1: LC3, GABARAP and GATE-16 family; LMP-1: LAMP (lysosome-associated membrane protein) homolog; MTOR: mechanistic target of rapamycin kinase; NUC-1: abnormal nuclease; PEPT-1/OPT-2: Peptide transporter family; PGP-1: P-glycoprotein related; RAB: RAB family; RIKE-1: RING and Kelch repeat-containing protein; SLCF-1: solute carrier family; SQST-1: sequestosome related; SPTL-1: serine palmitoyl transferase family.

Keywords:  Autophagy; C. elegans; LET-363/MTOR; endosomal degradation; epithelial morphogenesis; proteostasis

DOI:  https://doi.org/10.1080/15548627.2022.2071381
Autophagy Rep. 2022 ;1(1): 79-82

VAMP8 phosphorylation regulates lysosome dynamics during autophagy.

Lei Wang, Jiajie Diao.

  In the final critical step for autophagic degradation, lysosomes fuse with autophagosomes to form autolysosomes. Although recent research has suggested that soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are important for lysosome-autophagosome fusion, neither the architecture of the prefusion state nor the regulatory mechanisms have been identified. In our study, using structured illumination microscopy, we observed that lysosomes formed clusters around individual autophagosomes, thereby setting the stage for membrane fusion. Moreover, VAMP8 (vesicle-associated membrane protein 8) assists in forming the prefusion state of these clusters. We also found that VAMP8 phosphorylation reduces spontaneous lysosome-autophagosome fusion, whereas its dephosphorylation promotes fusion events between lysosomes and autophagosomes in both normal and autophagy-induced conditions. Our data thus suggest a key role of VAMP8 phosphorylation in the regulation of lysosome-autophagosome fusion.

Keywords:  Autophagy; VAMP8; fusion; lysosomes; phosphorylation

DOI:  https://doi.org/10.1080/27694127.2022.2031378
Cancer Res. 2022 May 03. 82(9): 1695-1697

No Back-up Plan: Loss of Isozyme Diversity as a Promising Therapeutic Strategy for Cancer.

Abisola Z Kehinde, Seth J Parker.

Metabolic rewiring in cancer cells supports many aspects of tumor growth. Understanding the mechanisms that result in metabolic rewiring, such as altered enzyme expression, is key to identifying therapeutic vulnerabilities that selectively target cancer cells. In this issue of Cancer Research, Marczyk and colleagues analyze matched tumor-normal enzyme expression across 14 different cancer types and report that cancer cells exhibit a general loss of isozyme diversity (LID) relative to corresponding normal tissue. The authors hypothesized that the presence of a cancer dominant isozyme may reduce metabolic plasticity and uniquely sensitize cancer cells to isozyme-specific inhibitors. Several LID targets were identified, including acetyl-CoA carboxylase 1 (ACC1), which the authors validated using a clinically available inhibitor of ACC1/2. This study is the first to systematically evaluate isozymes affected by LID, which represents a promising strategy to target the unique metabolic demands of cancer. See related article by Marczyk et al., p. 1698.

DOI: https://doi.org/10.1158/0008-5472.CAN-22-0855
Mol Metab. 2022 Apr 30. pii: S2212-8778(22)00080-1. [Epub ahead of print] 101511

De Novo Labeling and Trafficking of Individual Lipid Species in Live Cells.

Jun Zhang, Jia Nie, Haoran Sun, Jie Li, John-Paul Andersen, Yuguang Shi.

  Lipids exert dynamic biological functions which are determined both by their fatty acyl compositions and spatiotemporal distributions inside the cell. However, it remains a daunting task to investigate any of these features for each of the more than 1000 lipid species due to a lack of a universal labeling method for individual lipid moieties in live cells. Here we report a de novo lipid labeling method for individual lipid species with precise acyl compositions in live cells. The method is based on the principle of de novo lipid remodeling of exogenously added lysolipids with fluorescent acyl-CoA, leading to the re-synthesis of fluorescence-labeled lipids which can be imaged by confocal microscopy. In contrast to exogenously labeled lipids, the de novo labeled lipids retained full biological properties of their endogenous counterparts, including subcellular localization, trafficking, and recognition by lipid transporters. This method afforded us the opportunity to uncover some unexpected features of newly remodeled lipids and their transporters that were previously missed by conventional methods. Together, this method not only provides a powerful tool for functional analysis of individual lipid species and lipid transporters, but also calls for re-evaluation of previously published results using exogenously labeled lipids.

Keywords:  Lipid remodeling; Lipid trafficking; NBD; Phospholipid Transporters

DOI:  https://doi.org/10.1016/j.molmet.2022.101511
Proc Natl Acad Sci U S A. 2022 May 10. 119(19): e2107006119

MITF deficiency accelerates GNAQ-driven uveal melanoma.

Grace B Phelps, Hannah R Hagen, Adam Amsterdam, Jacqueline A Lees.

  SignificanceUveal melanoma (UM) is a cancer of eye melanocytes. Although relatively rare, UM is extremely deadly, as approximately half of all patients develop liver metastases for which there are no approved therapies. Even therapies that succeed in cutaneous melanoma (CM) treatment have proven ineffectual for UM, highlighting both the distinct nature of these two melanomas and the need to understand the differences between them. Here, we show that autochthonous UM tumors are rapidly induced by activated YAP and can lack hyperactive ERK, highlighting YAP as a promising therapeutic target. We further show that MITF functions as a tumor suppressor in UM in contrast to its essential role in CM, establishing that MITF inhibition should not be entertained for UM treatment.

Keywords:  melanoma; mitf; uveal; zebrafish

DOI:  https://doi.org/10.1073/pnas.2107006119
J Cell Physiol. 2022 May 05.

Cardiac glycosides stimulate endocytosis of GLUT1 via intracellular Na+ ,K+ -ATPase α3-isoform in human cancer cells.

Takuto Fujii, Mizuki Katoh, Manami Ootsubo, Oanh T T Nguyen, Mayumi Iguchi, Takahiro Shimizu, Yoshiaki Tabuchi, Yasuharu Shimizu, Hiroshi Takeshima, Hideki Sakai.

  Glucose transporter GLUT1 plays a primary role in the glucose metabolism of cancer cells. Here, we found that cardiac glycosides (CGs) such as ouabain, oleandrin, and digoxin, which are Na+ ,K+ -ATPase inhibitors, decreased the GLUT1 expression in the plasma membrane of human cancer cells (liver cancer HepG2, colon cancer HT-29, gastric cancer MKN45, and oral cancer KB cells). The effective concentration of ouabain was lower than that for inhibiting the activity of Na+ ,K+ -ATPase α1-isoform (α1NaK) in the plasma membrane. The CGs also inhibited [3 H]2-deoxy- d-glucose uptake, lactate secretion, and proliferation of the cancer cells. In intracellular vesicles of human cancer cells, Na+ ,K+ -ATPase α3-isoform (α3NaK) is abnormally expressed. Here, a low concentration of ouabain inhibited the activity of α3NaK. Knockdown of α3NaK significantly inhibited the ouabain-decreased GLUT1 expression in HepG2 cells, while the α1NaK knockdown did not. Consistent with the results in human cancer cells, CGs had no effect on GLUT1 expression in rat liver cancer dRLh-84 cells where α3NaK was not endogenously expressed. Interestingly, CGs decreased GLUT expression in the dRLh-84 cells exogenously expressing α3NaK. In HepG2 cells, α3NaK was found to be colocalized with TPC1, a Ca2+ -releasing channel activated by nicotinic acid adenine dinucleotide phosphate (NAADP). The CGs-decreased GLUT1 expression was significantly inhibited by a Ca2+ chelator, a Ca2+ -ATPase inhibitor, and a NAADP antagonist. The GLUT1 decrease was also attenuated by inhibitors of dynamin and phosphatidylinositol-3 kinases (PI3Ks). In conclusion, the binding of CGs to intracellular α3NaK elicits the NAADP-mediated Ca2+ mobilization followed by the dynamin-dependent GLUT1 endocytosis in human cancer cells.

Keywords:  Na+,K+-ATPase; cancer; cardiac glycosides; endocytosis; glucose transporter; glycolysis

DOI:  https://doi.org/10.1002/jcp.30762
iScience. 2022 May 20. 25(5): 104250

Rab33b-exocyst interaction mediates localized secretion for focal adhesion turnover and cell migration.

Synne Arstad Bjørnestad, Noemi Antonella Guadagno, Ingrid Kjos, Cinzia Progida.

  Rab proteins are well known regulators of intracellular trafficking; however, more and more studies point to their function also in other cellular processes, including cell migration. In this work, we have performed an siRNA screen to identify Rab proteins that influence cell migration. The screen revealed Rab33b as the strongest candidate that affected cell motility. Rab33b has been previously reported to localize at the Golgi apparatus to regulate Golgi-to-ER retrograde trafficking and Golgi homeostasis. We revealed that Rab33b also mediates post-Golgi transport to the plasma membrane. We further identified Exoc6, a subunit of the exocyst complex, as an interactor of Rab33b. Moreover, our data indicate that Rab33b regulates focal adhesion dynamics by modulating the delivery of cargo such as integrins to focal adhesions. Altogether, our results demonstrate a role for Rab33b in cell migration by regulating the delivery of integrins to focal adhesions through the interaction with Exoc6.

Keywords:  Cell biology; Functional aspects of cell biology; Organizational aspects of cell biology

DOI:  https://doi.org/10.1016/j.isci.2022.104250
Cell Death Discov. 2022 May 06. 8(1): 253

The AMPK-related kinase NUAK2 suppresses glutathione peroxidase 4 expression and promotes ferroptotic cell death in breast cancer cells.

Tanu Singh, Alexander Beatty, Jeffrey R Peterson.

Ferroptosis is a caspase-independent form of regulated cell death strongly linked to the accumulation of reactive lipid hydroperoxides. Lipid hydroperoxides are neutralized in cells by glutathione peroxidase 4 (GPX4) and inhibitors of GPX4 are potent ferroptosis inducers with therapeutic potential in cancer. Here we report that siRNA-mediated silencing of the AMPK-related kinase NUAK2 suppresses cell death by small-molecule inducers of ferroptosis but not apoptosis. Mechanistically we find that NUAK2 suppresses the expression of GPX4 at the RNA level and enhances ferroptosis triggered by GPX4 inhibitors in a manner independent of its kinase activity. NUAK2 is amplified along with MDM4 in a subset of breast cancers, particularly the claudin-low subset, suggesting that this may predict vulnerability to GPX4 inhibitors. These findings identify a novel pathway regulating GPX4 expression as well as ferroptotic sensitivity with potential as a biomarker of breast cancer patients that might respond to GPX4 inhibition as a therapeutic strategy.

DOI: https://doi.org/10.1038/s41420-022-01044-y
Mol Immunol. 2022 Apr 30. pii: S0161-5890(22)00197-3. [Epub ahead of print]147 30-39

Inhibition of TFEB promotes tumor-educated dendritic cells activation to enhance antitumor immune responses.

Jun Ding, Yewen Xie, Xiao Sun, Fang Shao, Jie Pan, Jie Chen, Zhichao Zhu, Chunjian Qi.

  Tumors can induce the generation and accumulation of immunosuppressive cells in -the tumor microenvironment (TME). Among them, tumor-educated dendritic cells (TEDCs) involved in tolerance induction contribute greatly to the progression of tumors. However, the mechanisms governing the immunosuppressive function of dendritic cells in the TME are unclear. In this study, we found that the expression of transcription factor EB (TFEB) was significantly increased in TEDCs induced by cancer cell supernatant. TFEB knockdown signiﬁcantly promoted the differentiation and maturation of TEDCs, with upregulated expression of CD11c and costimulatory molecules (CD86 and MHC-II) but reduced expression of the inhibitory molecule PD-L1, and enhanced their ability to induce Th1 proliferation and differentiation. Moreover, TEDCs with TFEB knockdown signiﬁcantly reduced tumor growth with increased inﬁltration of CD11c+MHC-II+ dendritic cells and effector T cells in tumor masses, thus leading to a delay in tumor progression. These findings demonstrate a critical role of TFEB in regulating the immunosuppression of TEDCs, with potential implications as an antitumor immune therapeutic approach.

Keywords:  Dendritic cells; Immune response; TFEB; Tumor microenvironment

DOI:  https://doi.org/10.1016/j.molimm.2022.04.011
Front Oncol. 2022 ;12 876245

Glycosylated Cathepsin V Serves as a Prognostic Marker in Lung Cancer.

Lewei Yang, Qi Zeng, Yun Deng, Yeqing Qiu, Wei Yao, Yifeng Liao.

  Dysregulation of cysteine cathepsin protease activity is pivotal in tumorigenic transformation. However, the role of cathepsin protease in lung cancer remains unknown. Here, we analyzed GEO database and found that lung cancer presented high expression of cathepsin V (CTSV). We then performed immunohistochemistry assay in 73 paired lung cancer tissues and normal lung tissues and confirmed that CTSV is overexpressed in lung cancer and correlates with poor prognosis. The mass spectrometry experiment showed that the N-glycosylation locus of CTSV are N221 and N292, glycosylated CTSV (band 43 kDa) was particularly expressed in lung cancer samples and correlated with lymph node metastasis. Mechanistic studies showed that only glycosylated CTSV (43-kDa band) are secreted to extracellular matrix (ECM) and promoted the metastasis of lung cancer. Importantly, the Elisa detection in serum of 12 lung cancer patients and 12 healthy donors showed that the level of CTSV in serum distinguished lung cancer patients from healthy donors. Together, our findings reveal the clinical relevance of CTSV glycosylation and CTSV drives the metastasis of lung cancer, suggesting that the glycosylated CTSV in serum is a promising biomarker for lung cancer.

Keywords:  CTSV; glycosylation; lung cancer; metastasis; prognosis

DOI:  https://doi.org/10.3389/fonc.2022.876245
Cell Calcium. 2022 Apr 19. pii: S0143-4160(22)00065-3. [Epub ahead of print]104 102591

p53 alters intracellular Ca2+ signaling through regulation of TRPM4.

Sven Kappel, Daniela Ross-Kaschitza, Barbara Hauert, Karen Rother, Christine Peinelt.

  Altered expression of transient receptor potential channel melastatin 4 (TRPM4) contributes to several diseases, including cardiac conduction disorders, immune diseases, and cancer. Yet the underlying mechanisms of TRPM4 expression changes remain elusive. In this study, we report that loss of tumor suppressor protein p53 or p63γ function or mutation of a putative p53 response element in the TRPM4 promoter region increase TRPM4 promoter activity in the colorectal cancer cell line HCT 116. In cells that lack p53 expression, we observed increased TRPM4 mRNA and protein levels and TRPM4-mediated Na+ currents. This phenotype can be reversed by transient overexpression of p53. In the prostate cancer cell line LNCaP, which expresses p53 endogenously, p53 overexpression decreases TRPM4-mediated currents. As in other cancer cells, CRISPR-Cas9 mediated knockout of TRPM4 in p53 deficient HCT 116 cells results in increased store-operated Ca2+entry. The effect of the TRPM4 knockout is mimicked by p53 mediated suppression of TRPM4 in the parental cell line expressing TRPM4. In addition, a TRPM4 knockout-mediated shift in cell cycle is abolished upon loss of p53. Taken together, these findings indicate that p53 represses TRPM4 expression, thereby altering cellular Ca2+ signaling and that TRPM4 adds to cell cycle shift dependent on p53 signaling. One sentence summary: TRPM4 is repressed in the p53 pathway leading to reduced currents and increased calcium signaling.

Keywords:  Cell cycle; Colorectal cancer; Store-operated calcium entry; TRPM4; Tumor suppressor p53

DOI:  https://doi.org/10.1016/j.ceca.2022.102591