USP26 promotes colorectal cancer tumorigenesis by restraining PRKN-mediated mitophagy.

Deubiquitinating enzymes (DUBs) are promising targets for cancer therapy because of their pivotal roles in various physiological and pathological processes. Among these, ubiquitin-specific peptidase 26 (USP26) is a protease with crucial regulatory functions. Our study sheds light on the upregulation of USP26 in colorectal cancer (CRC), in which its increased expression correlates with an unfavorable prognosis. Herein, we evidenced the role of USP26 in promoting CRC tumorigenesis in a parkin RBR E3 ubiquitin-protein ligase (PRKN) protein-dependent manner. Our investigation revealed that USP26 directly interacted with PRKN protein, facilitating its deubiquitination, and subsequently reducing its activity. Additionally, we identified the K129 site on PRKN as a specific target for USP26-mediated deubiquitination. Our research highlights that a K-to-R mutation at the site on PRKN diminishes its potential for activation and ability to mediate mitophagy. In summary, our findings underscore the significance of USP26-mediated deubiquitination in restraining the activation of the PRKN-mediated mitophagy pathway, ultimately driving CRC tumorigenesis. This study not only elucidated the multifaceted role of USP26 in CRC but also introduced a promising avenue for therapeutic exploration through the development of small molecule inhibitors targeting USP26. This strategy holds promise as a novel therapeutic approach for CRC.

SOD1-high fibroblasts derived exosomal miR-3960 promotes cisplatin resistance in triple-negative breast cancer by suppressing BRSK2-mediated phosphorylation of PIMREG.

Platinum-based neoadjuvant therapy represented by cisplatin is widely employed in treating Triple-Negative Breast Cancer (TNBC), a particularly aggressive subtype of breast cancer. Nevertheless, the emergence of cisplatin resistance presents a formidable challenge to clinical chemotherapy efficacy. Herein, we revealed the critical role of tumor microenvironment (TME) derived exosomal miR-3960 and phosphorylation at the S16 site of PIMREG in activating NF-κB signaling pathway and promoting cisplatin resistance of TNBC. Detailed regulatory mechanisms revealed that SOD1-upregulated fibroblasts secrete miR-3960 and are then transported into TNBC cells via exosomes. Within TNBC cells, miR-3960 targets and inhibits the expression of BRSK2, an AMPK protein kinase family member. Furthermore, we emphasized that BRSK2 contributes to ubiquitination degradation of PIMREG and modulates subsequent activation of the NF-κB signaling pathway by mediating PIMREG phosphorylation at the S16 site, ultimately affects the cisplatin resistance of TNBC. In conclusion, our research demonstrated the crucial role of SOD1high fibroblast, exosomal miR-3960 and S16 site phosphorylated PIMREG in regulating the NF-κB signaling pathway and cisplatin resistance of TNBC. These findings provided significant potential as biomarkers for accurately diagnosing cisplatin-resistant TNBC patients and guiding chemotherapy strategy selection.

Tiam1 methylation by NSD2 promotes Rac1 signaling activation and colon cancer metastasis.

Metastasis is a major cause of cancer therapy failure and mortality. However, targeting metastatic seeding and colonization remains a significant challenge. In this study, we identified NSD2, a histone methyltransferase responsible for dimethylating histone 3 at lysine 36, as being overexpressed in metastatic tumors. Our findings suggest that NSD2 overexpression enhances tumor metastasis both in vitro and in vivo. Further analysis revealed that NSD2 promotes tumor metastasis by activating Rac1 signaling. Mechanistically, NSD2 combines with and activates Tiam1 (T lymphoma invasion and metastasis 1) and promotes Rac1 signaling by methylating Tiam1 at K724. In vivo and in vitro studies revealed that Tiam1 K724 methylation could be a predictive factor for cancer prognosis and a potential target for metastasis inhibition. Furthermore, we have developed inhibitory peptide which was proved to inhibit tumor metastasis through blocking the interaction between NSD2 and Tiam1. Our results demonstrate that NSD2-methylated Tiam1 promotes Rac1 signaling and cancer metastasis. These results provide insights into the inhibition of tumor metastasis.

NSD2 methylates AROS to promote SIRT1 activation and regulates fatty acid metabolism-mediated cancer radiotherapy.

Fatty acid metabolism plays a critical role in both tumorigenesis and cancer radiotherapy. However, the regulatory mechanism of fatty acid metabolism has not been fully elucidated. NSD2, a histone methyltransferase that catalyzes di-methylation of histone H3 at lysine 36, has been shown to play an essential role in tumorigenesis and cancer progression. Here, we show that NSD2 promotes fatty acid oxidation (FAO) by methylating AROS (active regulator of SIRT1) at lysine 27, facilitating the physical interaction between AROS and SIRT1. The mutation of lysine 27 to arginine weakens the interaction between AROS and SIRT1 and impairs AROS-SIRT1-mediated FAO. Additionally, we examine the effect of NSD2 inhibition on radiotherapy efficacy and find an enhanced effectiveness of radiotherapy. Together, our findings identify a NSD2-dependent methylation regulation pattern of the AROS-SIRT1 axis, suggesting that NSD2 inhibition may be a potential adjunct for tumor radiotherapy.

SETDB1 Methylates MCT1 Promoting Tumor Progression by Enhancing the Lactate Shuttle.

MCT1 is a critical protein found in monocarboxylate transporters that plays a significant role in regulating the lactate shuttle. However, the post-transcriptional modifications that regulate MCT1 are not clearly identified. In this study, it is reported that SETDB1 interacts with MCT1, leading to its stabilization. These findings reveal a novel post-translational modification of MCT1, in which SETDB1 methylation occurs at K473 in vitro and in vivo. This methylation inhibits the interaction between MCT1 and Tollip, which blocks Tollip-mediated autophagic degradation of MCT1. Furthermore, MCT1 K473 tri-methylation promotes tumor glycolysis and M2-like polarization of tumor-associated macrophages in colorectal cancer (CRC), which enhances the lactate shuttle. In clinical studies, MCT1 K473 tri-methylation is found to be upregulated and positively correlated with tumor progression and overall survival in CRC. This discovery suggests that SETDB1-mediated tri-methylation at K473 is a vital regulatory mechanism for lactate shuttle and tumor progression. Additionally, MCT1 K473 methylation may be a potential prognostic biomarker and promising therapeutic target for CRC.

PD-L1 methylation restricts PD-L1/PD-1 interactions to control cancer immune surveillance.

Immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) or programmed cell death 1 ligand 1 (PD-L1) have enabled some patients with cancer to experience durable, complete treatment responses; however, reliable anti-PD-(L)1 treatment response biomarkers are lacking. Our research found that PD-L1 K162 was methylated by SETD7 and demethylated by LSD2. Furthermore, PD-L1 K162 methylation controlled the PD-1/PD-L1 interaction and obviously enhanced the suppression of T cell activity controlling cancer immune surveillance. We demonstrated that PD-L1 hypermethylation was the key mechanism for anti-PD-L1 therapy resistance, investigated that PD-L1 K162 methylation was a negative predictive marker for anti-PD-1 treatment in patients with non-small cell lung cancer, and showed that the PD-L1 K162 methylation:PD-L1 ratio was a more accurate biomarker for predicting anti-PD-(L)1 therapy sensitivity. These findings provide insights into the regulation of the PD-1/PD-L1 pathway, identify a modification of this critical immune checkpoint, and highlight a predictive biomarker of the response to PD-1/PD-L1 blockade therapy.

PRMT5 methylating SMAD4 activates TGF-ß signaling and promotes colorectal cancer metastasis.

Perturbations in transforming growth factor-ß (TGF-ß) signaling can lead to a plethora of diseases, including cancer. Mutations and posttranslational modifications (PTMs) of the partner of SMAD complexes contribute to the dysregulation of TGF-ß signaling. Here, we reported a PTM of SMAD4, R361 methylation, that was critical for SMAD complexes formation and TGF-ß signaling activation. Through mass spectrometric, co-immunoprecipitation (Co-IP) and immunofluorescent (IF) assays, we found that oncogene protein arginine methyltransferase 5 (PRMT5) interacted with SMAD4 under TGF-ß1 treatment. Mechanically, PRMT5 triggered SMAD4 methylation at R361 and induced SMAD complexes formation and nuclear import. Furthermore, we emphasized that PRMT5 interacting and methylating SMAD4 was required for TGF-ß1-induced epithelial-mesenchymal transition (EMT) and colorectal cancer (CRC) metastasis, and SMAD4 R361 mutation diminished PRMT5 and TGF-ß1-induced metastasis. In addition, highly expressed PRMT5 or high level of SMAD4 R361 methylation indicated worse outcomes in clinical specimens analysis. Collectively, our study highlights the critical interaction of PRMT5 and SMAD4 and the roles of SMAD4 R361 methylation for controlling TGF-ß signaling during metastasis. We provided a new insight for SMAD4 activation. And this study indicated that blocking PRMT5-SMAD4 signaling might be an effective targeting strategy in SMAD4 wild-type CRC.

Chemodivergent Synthesis of Indeno[1,2-b]indoles and Isoindolo[2,1-a]indoles via Mn(III)-Mediated or Electrochemical Intramolecular Radical Cross-Dehydrogenative Coupling.

Chemodivergent synthesis of indeno[1,2-b]indoles and isoindolo[2,1-a]indoles from the same starting materials involving radical cross-dehydrogenative couplings have been developed. Mn(OAc)3·2H2O selectively promoted an intramolecular radical C-H/C-H dehydrogenative coupling reaction to provide indeno[1,2-b]indoles, while an intramolecular radical C-H/N-H dehydrogenative coupling reaction could proceed via electrochemistry to deliver isoindolo[2,1-a]indoles. Plausible mechanisms of the chemodivergent reactions were proposed.

EZH2-triggered methylation of SMAD3 promotes its activation and tumor metastasis.

SMAD3 plays a central role in cancer metastasis, and its hyperactivation is linked to poor cancer outcomes. Thus, it is critical to understand the upstream signaling pathways that govern SMAD3 activation. Here, we report that SMAD3 underwent methylation at K53 and K333 (K53/K333) by EZH2, a process crucial for cell membrane recruitment, phosphorylation, and activation of SMAD3 upon TGFB1 stimulation. Mechanistically, EZH2-triggered SMAD3 methylation facilitated SMAD3 interaction with its cellular membrane localization molecule (SARA), which in turn sustained SMAD3 phosphorylation by the TGFB receptor. Pathologically, increased expression of EZH2 expression resulted in the accumulation of SMAD3 methylation to facilitate SMAD3 activation. EZH2-mediated SMAD3 K53/K333 methylation was upregulated and correlated with SMAD3 hyperactivation in breast cancer, promoted tumor metastasis, and was predictive of poor survival outcomes. We used 2 TAT peptides to abrogate SMAD3 methylation and therapeutically inhibit cancer metastasis. Collectively, these findings reveal the complicated layers involved in the regulation of SMAD3 activation coordinated by EZH2-mediated SMAD3 K53/K333 methylation to drive cancer metastasis.

Irregular distribution of grid cell firing fields in rats exploring a 3D volumetric space.

We investigated how entorhinal grid cells encode volumetric space. On a horizontal surface, grid cells usually produce multiple, spatially focal, approximately circular firing fields that are evenly sized and spaced to form a regular, close-packed, hexagonal array. This spatial regularity has been suggested to underlie navigational computations. In three dimensions, theoretically the equivalent firing pattern would be a regular, hexagonal close packing of evenly sized spherical fields. In the present study, we report that, in rats foraging in a cubic lattice, grid cells maintained normal temporal firing characteristics and produced spatially stable firing fields. However, although most grid fields were ellipsoid, they were sparser, larger, more variably sized and irregularly arranged, even when only fields abutting the lower surface (equivalent to the floor) were considered. Thus, grid self-organization is shaped by the environment's structure and/or movement affordances, and grids may not need to be regular to support spatial computations.

IL-6 regulates autophagy and chemotherapy resistance by promoting BECN1 phosphorylation.

Extracellular cytokines are enriched in the tumor microenvironment and regulate various important properties of cancers, including autophagy. However, the precise molecular mechanisms underlying the link between autophagy and extracellular cytokines remain to be elucidated. In the present study, we demonstrate that IL-6 activates autophagy through the IL-6/JAK2/BECN1 pathway and promotes chemotherapy resistance in colorectal cancer (CRC). Mechanistically, IL-6 triggers the interaction between JAK2 and BECN1, where JAK2 phosphorylates BECN1 at Y333. We demonstrate that BECN1 Y333 phosphorylation is crucial for BECN1 activation and IL-6-induced autophagy by regulating PI3KC3 complex formation. Furthermore, we investigate BECN1 Y333 phosphorylation as a predictive marker for poor CRC prognosis and chemotherapy resistance. Combination treatment with autophagy inhibitors or pharmacological agents targeting the IL-6/JAK2/BECN1 signaling pathway may represent a potential strategy for CRC cancer therapy.

NSD2 promotes tumor angiogenesis through methylating and activating STAT3 protein.

Tumor angiogenesis plays vital roles in tumorigenesis and development; regulatory mechanism of angiogenesis is still not been fully elucidated. NSD2, a histone methyltransferase catalyzing di-methylation of histone H3 at lysine 36, has been proved a critical molecule in proliferation, metastasis, and tumorigenesis. But its role in tumor angiogenesis remains unknown. Here we demonstrated that NSD2 promoted tumor angiogenesis in vitro and in vivo. Furthermore, we confirmed that the angiogenic function of NSD2 was mediated by STAT3. Momentously, we found that NSD2 promoted the methylation and activation of STAT3. In addition, mass spectrometry and site-directed mutagenesis assays revealed that NSD2 methylated STAT3 at lysine 163 (K163). Meanwhile, K to R mutant at K163 of STAT3 attenuated the activation and angiogenic function of STAT3. Taken together, we conclude that methylation of STAT3 catalyzed by NSD2 promotes the activation of STAT3 pathway and enhances the ability of tumor angiogenesis. Our findings investigate a NSD2-dependent methylation-phosphorylation regulation pattern of STAT3 and reveal that NSD2/STAT3/VEGFA axis might be a potential target for tumor therapy.

Hippocampal place cells encode global location but not connectivity in a complex space.

Flexible navigation relies on a cognitive map of space, thought to be implemented by hippocampal place cells: neurons that exhibit location-specific firing. In connected environments, optimal navigation requires keeping track of one's location and of the available connections between subspaces. We examined whether the dorsal CA1 place cells of rats encode environmental connectivity in four geometrically identical boxes arranged in a square. Rats moved between boxes by pushing saloon-type doors that could be locked in one or both directions. Although rats demonstrated knowledge of environmental connectivity, their place cells did not respond to connectivity changes, nor did they represent doorways differently from other locations. Place cells coded location in a global reference frame, with a different map for each box and minimal repetitive fields despite the repetitive geometry. These results suggest that CA1 place cells provide a spatial map that does not explicitly include connectivity.

Volumetric spatial behaviour in rats reveals the anisotropic organisation of navigation.

We investigated how access to the vertical dimension influences the natural exploratory and foraging behaviour of rats. Using high-accuracy three-dimensional tracking of position in two- and three-dimensional environments, we sought to determine (i) how rats navigated through the environments with respect to gravity, (ii) where rats chose to form their home bases in volumetric space, and (iii) how they navigated to and from these home bases. To evaluate how horizontal biases may affect these behaviours, we compared a 3D maze where animals preferred to move horizontally to a different 3D configuration where all axes were equally energetically costly to traverse. Additionally, we compared home base formation in two-dimensional arenas with and without walls to the three-dimensional climbing mazes. We report that many behaviours exhibited by rats in horizontal spaces naturally extend to fully volumetric ones, such as home base formation and foraging excursions. We also provide further evidence for the strong differentiation of the horizontal and vertical axes: rats showed a horizontal movement bias, they formed home bases mainly in the bottom layers of both mazes and they generally solved the vertical component of return trajectories before and faster than the horizontal component. We explain the bias towards horizontal movements in terms of energy conservation, while the locations of home bases are explained from an information gathering view as a method for correcting self-localisation.

The place-cell representation of volumetric space in rats.

Place cells are spatially modulated neurons found in the hippocampus that underlie spatial memory and navigation: how these neurons represent 3D space is crucial for a full understanding of spatial cognition. We wirelessly recorded place cells in rats as they explored a cubic lattice climbing frame which could be aligned or tilted with respect to gravity. Place cells represented the entire volume of the mazes: their activity tended to be aligned with the maze axes, and when it was more difficult for the animals to move vertically the cells represented space less accurately and less stably. These results demonstrate that even surface-dwelling animals represent 3D space and suggests there is a fundamental relationship between environment structure, gravity, movement and spatial memory.

Transition-Metal-Controlled Synthesis of 11H-Benzo[a]carbazoles and 6-Alkylidene-6H-isoindo[2,1-a]indoles via Sequential Intermolecular/Intramolecular Cross-Dehydrogenative Coupling from 2-Phenylindoles.

A catalyst-controlled synthesis of 11H-benzo[a]carbazoles and 6-alkylidene-6H-isoindo[2,1-a]indoles is described. Pd(OAc)2 favored 6-alkylidene-6H-isoindo[2,1-a]indoles via intramolecular C-H/N-H CDC reaction, while [Cp*RhCl2]2 led to 11H-benzo[a]carbazoles through intramolecular C-H/C-H CDC reaction. Moreover, the synthesis of 11H-benzo[a]carbazoles via sequential intermolecular ortho C-H/olefin coupling and intramolecular C3-H/olefin coupling from 2-phenylindoles and alkenes can be operated in one pot.