bims-lymeca 2023-01-15 papers

bims-lymeca

Biomed News

on Lysosome metabolism in cancer

Issue of 2023–01–15
nine papers selected by
Harilaos Filippakis, University of New England

GATOR2 rings GATOR1 to speak to mTORC1.
Consecutive functions of small GTPases guide HOPS-mediated tethering of late endosomes and lysosomes.
A central role for regulated protein stability in the control of TFE3 and MITF by nutrients.
Glutamine Produces Ammonium to Tune Lysosomal pH and Regulate Lysosomal Function.
ATP6V0D1 promotes alkaliptosis by blocking STAT3-mediated lysosomal pH homeostasis.
Mass Spectrometry Reveals High Levels of Hydrogen Peroxide in Pancreatic Cancer Cells.
Targeting Lysosomes in Colorectal Cancer: Exploring the Anticancer Activity of a New Benzo[a]phenoxazine Derivative.
LYSET/TMEM251/GCAF is critical for autophagy and lysosomal function by regulating the mannose-6-phosphate (M6P) pathway.
Cancer-Associated Fibroblast Diversity Shapes Tumor Metabolism in Pancreatic Cancer.

Mol Cell. 2023 Jan 05. pii: S1097-2765(22)01168-6. [Epub ahead of print]83(1): 6-8

GATOR2 rings GATOR1 to speak to mTORC1.

Umakant Sahu, Issam Ben-Sahra.

The mechanistic target of rapamycin complex 1 (mTORC1) senses cellular leucine levels through the GATOR1/2-Rag axis. Jiang et al. show that the Ring domains of GATOR2 subunits maintain the integrity of the complex and promote ubiquitination and inhibition of GATOR1, thereby leading to mTORC1 activation.

DOI: https://doi.org/10.1016/j.molcel.2022.12.011
Cell Rep. 2023 Jan 04. pii: S2211-1247(22)01873-3. [Epub ahead of print]42(1): 111969

Consecutive functions of small GTPases guide HOPS-mediated tethering of late endosomes and lysosomes.

Ariane Schleinitz, Lara-Alina Pöttgen, Tal Keren-Kaplan, Jing Pu, Paul Saftig, Juan S Bonifacino, Albert Haas, Andreas Jeschke.

  The transfer of endocytosed cargoes to lysosomes (LYSs) requires HOPS, a multiprotein complex that tethers late endosomes (LEs) to LYSs before fusion. Many proteins interact with HOPS on LEs/LYSs. However, it is not clear whether these HOPS interactors localize to LEs or LYSs or how they participate in tethering. Here, we biochemically characterized endosomes purified from untreated or experimentally manipulated cells to put HOPS and interacting proteins in order and to establish their functional interdependence. Our results assign Rab2a and Rab7 to LEs and Arl8 and BORC to LYSs and show that HOPS drives LE-LYS fusion by bridging late endosomal Rab2a with lysosomal BORC-anchored Arl8. We further show that Rab7 is absent from sites of HOPS-dependent tethering but promotes fusion by moving LEs toward LYSs via dynein. Thus, our study identifies the topology of the machinery for LE-LYS tethering and elucidates the role of different small GTPases in the process.

Keywords:  CP: Cell biology; autophagosome; autophagy; dynein; endolysosome; lysosome reformation; membrane fusion; membrane tethering; phagocytosis; phosphoinositides; protein trafficking

DOI:  https://doi.org/10.1016/j.celrep.2022.111969
Mol Cell. 2023 Jan 05. pii: S1097-2765(22)01170-4. [Epub ahead of print]83(1): 57-73.e9

A central role for regulated protein stability in the control of TFE3 and MITF by nutrients.

Christopher Nardone, Brad A Palanski, Daniel C Scott, Richard T Timms, Karl W Barber, Xin Gu, Aoyue Mao, Yumei Leng, Emma V Watson, Brenda A Schulman, Philip A Cole, Stephen J Elledge.

  The TFE3 and MITF master transcription factors maintain metabolic homeostasis by regulating lysosomal, melanocytic, and autophagy genes. Previous studies posited that their cytosolic retention by 14-3-3, mediated by the Rag GTPases-mTORC1, was key for suppressing transcriptional activity in the presence of nutrients. Here, we demonstrate using mammalian cells that regulated protein stability plays a fundamental role in their control. Amino acids promote the recruitment of TFE3 and MITF to the lysosomal surface via the Rag GTPases, activating an evolutionarily conserved phospho-degron and leading to ubiquitination by CUL1β-TrCP and degradation. Elucidation of the minimal functional degron revealed a conserved alpha-helix required for interaction with RagA, illuminating the molecular basis for a severe neurodevelopmental syndrome caused by missense mutations in TFE3 within the RagA-TFE3 interface. Additionally, the phospho-degron is recurrently lost in TFE3 genomic translocations that cause kidney cancer. Therefore, two divergent pathologies converge on the loss of protein stability regulation by nutrients.

Keywords:  MITF; Rag GTPases; TFE3; kidney cancer; lysosomes; mTORC1; neurodevelopment; nutrient-sensing; phospho-degron; ubiquitin; β-TrCP

DOI:  https://doi.org/10.1016/j.molcel.2022.12.013
Cells. 2022 Dec 24. pii: 80. [Epub ahead of print]12(1):

Glutamine Produces Ammonium to Tune Lysosomal pH and Regulate Lysosomal Function.

Jian Xiong, Thi Thu Trang Luu, Kartik Venkatachalam, Guangwei Du, Michael X Zhu.

  Glutamine is one of the most abundant amino acids in the cell. In mitochondria, glutaminases 1 and 2 (GLS1/2) hydrolyze glutamine to glutamate, which serves as the precursor of multiple metabolites. Here, we show that ammonium generated during GLS1/2-mediated glutaminolysis regulates lysosomal pH and in turn lysosomal degradation. In primary human skin fibroblasts BJ cells and mouse embryonic fibroblasts, deprivation of total amino acids for 1 h increased lysosomal degradation capacity as shown by the increased turnover of lipidated microtubule-associated proteins 1A/1B light chain 3B (LC3-II), several autophagic receptors, and endocytosed DQ-BSA. Removal of glutamine but not any other amino acids from the culture medium enhanced lysosomal degradation similarly as total amino acid starvation. The presence of glutamine in regular culture media increased lysosomal pH by >0.5 pH unit and the removal of glutamine caused lysosomal acidification. GLS1/2 knockdown, GLS1 antagonist, or ammonium scavengers reduced lysosomal pH in the presence of glutamine. The addition of glutamine or NH4Cl prevented the increase in lysosomal degradation and curtailed the extension of mTORC1 function during the early time period of amino acid starvation. Our findings suggest that glutamine tunes lysosomal pH by producing ammonium, which regulates lysosomal degradation to meet the demands of cellular activities. During the early stage of amino acid starvation, the glutamine-dependent mechanism allows more efficient use of internal reserves and endocytosed proteins to extend mTORC1 activation such that the normal anabolism is not easily interrupted by a brief disruption of the amino acid supply.

Keywords:  amino acid starvation; autophagosome; autophagy; glutaminase; glutamine; lysosomal pH; mTORC1 activation

DOI:  https://doi.org/10.3390/cells12010080
Cell Rep. 2022 Dec 29. pii: S2211-1247(22)01810-1. [Epub ahead of print]42(1): 111911

ATP6V0D1 promotes alkaliptosis by blocking STAT3-mediated lysosomal pH homeostasis.

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

  Alkaliptosis, a type of regulated cell death driven by intracellular alkalization, was first described in pancreatic ductal adenocarcinoma (PDAC) cells after treatment with the opioid analgesic drug JTC801. Here, we used mass-spectrometry-based drug target identification, cellular thermal shift assay, and point mutation technologies to reveal ATP6V0D1 as a direct JTC801 target that drives alkaliptosis in human PDAC cells. Functionally, the protein stability of ATP6V0D1, when mediated by JTC801, increases the interaction between ATP6V0D1 and STAT3, resulting in increased expression and activity of STAT3 for sustaining lysosome homeostasis. Consequently, the pharmacological or genetic inhibition of STAT3 restores the sensitivity of ATP6V0D1-deficient cells to alkaliptosis in vitro or in suitable mouse models. Clinically, a high expression of ATP6V0D1 correlates with prolonged survival of patients with PDAC. Together, these results illustrate a link between ATP6V0D1 and PDAC and advance our understanding of alkaliptosis in targeted therapy.

Keywords:  ATP6V0D1; CP: Cancer; STAT3; alkaliptosis; lysosome; pancreatic cancer

DOI:  https://doi.org/10.1016/j.celrep.2022.111911
Angew Chem Int Ed Engl. 2023 Jan 08.

Mass Spectrometry Reveals High Levels of Hydrogen Peroxide in Pancreatic Cancer Cells.

Qinlei Liu, Wenjie Ge, Sandra Martínez-Jarquín, Yuliang He, Ri Wu, Markus Stoffel, Renato Zenobi.

  Reactive oxygen species (ROS) are critical for many cellular functions, and dysregulation of ROS involves the development of multiple types of tumors, including pancreatic cancer. However, ROS have been grouped into a single biochemical entity for a long time, and the specific roles of certain types of ROS in tumor cells (e.g., pancreatic ductal adenocarcinoma (PDAC)) have not been systematically investigated. In this work, a highly sensitive and accurate mass spectrometry-based method was applied to study PDAC cells of humans and of genetically modified animals. The results show that the oncogenic KRAS mutation promotes the accumulation of hydrogen peroxide (H2O2) rather than superoxide or hydroxyl radicals in pancreatic cancer cells. We further identified that the enriched H2O2 modifies cellular metabolites and promotes the survival of pancreatic cancer cells. These findings highlight the specific roles of H2O2 in pancreatic cancer development, which may provide new directions for pancreatic cancer therapy.

Keywords:  ESI-MS; Reactive oxygen species; hydrogen peroxide; metabolic changes; pancreatic cancer

DOI:  https://doi.org/10.1002/anie.202213703
Int J Mol Sci. 2022 Dec 29. pii: 614. [Epub ahead of print]24(1):

Targeting Lysosomes in Colorectal Cancer: Exploring the Anticancer Activity of a New Benzo[a]phenoxazine Derivative.

João C C Ferreira, Sara Granja, Ana F Almeida, Fátima Baltazar, M Sameiro T Gonçalves, Ana Preto, Maria João Sousa.

  Colorectal cancer (CRC) has been ranked as one of the cancer types with a higher incidence and one of the most mortal. There are limited therapies available for CRC, which urges the finding of intracellular targets and the discovery of new drugs for innovative therapeutic approaches. In addition to the limited number of effective anticancer agents approved for use in humans, CRC resistance and secondary effects stemming from classical chemotherapy remain a major clinical problem, reinforcing the need for the development of novel drugs. In the recent years, the phenoxazines derivatives, Nile Blue analogues, have been shown to possess anticancer activity, which has created interest in exploring the potential of these compounds as anticancer drugs. In this context, we have synthetized and evaluated the anticancer activity of different benzo[a]phenoxazine derivatives for CRC therapy. Our results revealed that one particular compound, BaP1, displayed promising anticancer activity against CRC cells. We found that BaP1 is selective for CRC cells and reduces cell proliferation, cell survival, and cell migration. We observed that the compound is associated with reactive oxygen species (ROS) generation, accumulates in the lysosomes, and leads to lysosomal membrane permeabilization, cytosolic acidification, and apoptotic cell death. In vivo results using a chicken embryo choriollantoic membrane (CAM) assay showed that BaP1 inhibits tumor growth, angiogenesis, and tumor proliferation. These observations highlight that BaP1 as a very interesting agent to disturb and counteract the important roles of lysosomes in cancer and suggests BaP1 as a promising candidate to be exploited as new anticancer lysosomal-targeted agent, which uses lysosome membrane permeabilization (LMP) as a therapeutic approach in CRC.

Keywords:  Nile Blue analogue; anticancer drug; benzo[a]phenoxazine; colorectal cancer; lysosome membrane permeabilization

DOI:  https://doi.org/10.3390/ijms24010614
Autophagy. 2023 Jan 12.

LYSET/TMEM251/GCAF is critical for autophagy and lysosomal function by regulating the mannose-6-phosphate (M6P) pathway.

Bokai Zhang, Xi Yang, Ming Li.

  Vertebrate cells rely on mannose-6-phosphate (M6P) modifications to deliver most lumenal hydrolases to the lysosome. As a critical trafficking signal for lysosomal enzymes, the M6P biosynthetic pathway has been thoroughly investigated. However, its regulatory mechanism is largely unknown. Here, we summarize three recent studies that independently discovered LYSET/TMEM251/GCAF as a key regulator of the M6P pathway. LYSET/TMEM251 directly interacts with GNPT, the enzyme that catalyzes the transfer of M6P, and is critical for its activity and stability. Deleting LYSET/TMEM251 impairs the GNPT function and M6P modifications. Consequently, lysosomal enzymes are mistargeted for secretion. Defective lysosomes fail to degrade cargoes such as endocytic vesicles and autophagosomes, leading to a newly identified lysosomal storage disease in humans. These discoveries open up a new direction in the regulation of the M6P biosynthetic pathway.

Keywords:  Autophagy; GNPT; M6P; TMEM251; lysosomal enzymes; lysosomal storage disease

DOI:  https://doi.org/10.1080/15548627.2023.2167375
Cancers (Basel). 2022 Dec 22. pii: 61. [Epub ahead of print]15(1):

Cancer-Associated Fibroblast Diversity Shapes Tumor Metabolism in Pancreatic Cancer.

Raphaël Peiffer, Yasmine Boumahd, Charlotte Gullo, Rebekah Crake, Elisabeth Letellier, Akeila Bellahcène, Olivier Peulen.

  Despite extensive research, the 5-year survival rate of pancreatic cancer (PDAC) patients remains at only 9%. Patients often show poor treatment response, due partly to a highly complex tumor microenvironment (TME). Cancer-associated fibroblast (CAF) heterogeneity is characteristic of the pancreatic TME, where several CAF subpopulations have been identified, such as myofibroblastic CAFs (myCAFs), inflammatory CAFs (iCAFs), and antigen presenting CAFs (apCAFs). In PDAC, cancer cells continuously adapt their metabolism (metabolic switch) to environmental changes in pH, oxygenation, and nutrient availability. Recent advances show that these environmental alterations are all heavily driven by stromal CAFs. CAFs and cancer cells exchange cytokines and metabolites, engaging in a tight bidirectional crosstalk, which promotes tumor aggressiveness and allows constant adaptation to external stress, such as chemotherapy. In this review, we summarize CAF diversity and CAF-mediated metabolic rewiring, in a PDAC-specific context. First, we recapitulate the most recently identified CAF subtypes, focusing on the cell of origin, activation mechanism, species-dependent markers, and functions. Next, we describe in detail the metabolic crosstalk between CAFs and tumor cells. Additionally, we elucidate how CAF-driven paracrine signaling, desmoplasia, and acidosis orchestrate cancer cell metabolism. Finally, we highlight how the CAF/cancer cell crosstalk could pave the way for new therapeutic strategies.

Keywords:  CAF; PDAC; acidosis; cancer-associated fibroblast; desmoplasia; hypoxia; metabolism; pancreatic cancer; paracrine signaling

DOI:  https://doi.org/10.3390/cancers15010061