RAC1-mediated integrin alpha-6 expression in E-cadherin-deficient gastric cancer cells promotes interactions with the stroma and peritoneal dissemination.

Diffuse-type gastric cancer (DGC) is a subtype of gastric cancer that is prone to peritoneal dissemination, with poor patient prognosis. Although intercellular adhesion loss between cancer cells is a major characteristic of DGCs, the mechanism underlying the alteration in cell-to-extracellular matrix (ECM) adhesion is unclear. We investigated how DGCs progress and cause peritoneal dissemination through interactions between DGC cells and the tumour microenvironment (TME). P53 knockout and KRASG12V-expressing (GAN-KP) cells and Cdh1-deleted GAN-KP (GAN-KPC) cells were orthotopically transplanted into the gastric wall to mimic peritoneal dissemination. The GAN-KPC tumour morphology was similar to that of human DGCs containing abundant stroma. RNA sequencing revealed that pathways related to Rho GTPases and integrin-ECM interactions were specifically increased in GAN-KPC cells compared with GAN-KP cells. Notably, we found that Rac Family Small GTPase 1 (RAC1) induces Integrin Subunit Alpha 6 (ITGA6) trafficking, leading to its enrichment on the GC cell membrane. Fibroblasts activate the FAK/AKT pathway in GC cells by mediating extracellular matrix (ECM)-Itga6 interactions, exacerbating the malignant phenotype. In turn, GC cells induce abnormal expression of fibroblast collagen and its transformation into cancer-associated fibroblasts (CAFs), resulting in DGC-like subtypes. These findings indicate that Cdh1 gene loss leads to abnormal expression and changes in the subcellular localization of ITGA6 through RAC1 signalling. The latter, through interactions with CAFs, allows for peritoneal dissemination.

FOXO1 stimulates tip cell-enriched gene expression in endothelial cells.

Forkhead box O (FOXO) family proteins are expressed in various cells, and play crucial roles in cellular metabolism, apoptosis, and aging. FOXO1-null mice exhibit embryonic lethality due to impaired endothelial cell (EC) maturation and vascular remodeling. However, FOXO1-mediated genome-wide regulation in ECs remains unclear. Here, we demonstrate that VEGF dynamically regulates FOXO1 cytosol-nucleus translocation. FOXO1 re-localizes to the nucleus via PP2A phosphatase. RNA-seq combined with FOXO1 overexpression/knockdown in ECs demonstrated that FOXO1 governs the VEGF-responsive tip cell-enriched genes, and further inhibits DLL4-NOTCH signaling. Endogenous FOXO1 ChIP-seq revealed that FOXO1 binds to the EC-unique tip-enriched genes with co-enrichment of EC master regulators, and the condensed chromatin region as a pioneer factor. We identified new promoter/enhancer regions of the VEGF-responsive tip cell genes regulated by FOXO1: ESM1 and ANGPT2. This is the first study to identify cell type-specific FOXO1 functions, including VEGF-mediated tip cell definition in primary cultured ECs.

YAP/BRD4-controlled ROR1 promotes tumor-initiating cells and hyperproliferation in pancreatic cancer.

Tumor-initiating cells are major drivers of chemoresistance and attractive targets for cancer therapy, however, their identity in human pancreatic ductal adenocarcinoma (PDAC) and the key molecules underlying their traits remain poorly understood. Here, we show that a cellular subpopulation with partial epithelial-mesenchymal transition (EMT)-like signature marked by high expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) is the origin of heterogeneous tumor cells in PDAC. We demonstrate that ROR1 depletion suppresses tumor growth, recurrence after chemotherapy, and metastasis. Mechanistically, ROR1 induces the expression of Aurora kinase B (AURKB) by activating E2F through c-Myc to enhance PDAC proliferation. Furthermore, epigenomic analyses reveal that ROR1 is transcriptionally dependent on YAP/BRD4 binding at the enhancer region, and targeting this pathway reduces ROR1 expression and prevents PDAC growth. Collectively, our findings reveal a critical role for ROR1high cells as tumor-initiating cells and the functional importance of ROR1 in PDAC progression, thereby highlighting its therapeutic targetability.

Heterogeneous expression and role of receptor tyrosine kinase-like orphan receptor 2 (ROR2) in small cell lung cancer.

The present study investigated the expression and role of ROR2 in small cell lung cancer (SCLC). To examine the expression of ROR2, 27 surgically resected SCLC tissue samples were immunostained for ROR2. Sixteen tissue samples were positive and some showed intratumor heterogeneity in staining intensity. The heterogeneity of ROR2 expression was also observed in tumor tissues from a PDX model of SCLC, in which there were cells with high ROR2 expression (ROR2high cells) and without its expression (ROR2low cells). These cells were subjected to a RNA sequence analysis. GSEA was performed and the results obtained revealed the enrichment of molecules such as G2M checkpoint, mitotic spindle, and E2F targets in ROR2high cells. The rate of EdU incorporation was significantly higher in ROR2high cells than ROR2low cells from the PDX model and the SCLC cell lines. Cell proliferation was suppressed in ROR2 KO SBC3 cells in vitro and in vivo. Comparisons of down-regulated differentially expressed genes in ROR2 KO SBC3 cells with up-regulated DEG in ROR2high cells from the PDX model revealed 135 common genes. After a Metascape analysis of these genes, we focused on Aurora kinases. In SCLC cell lines, the knockdown of ROR2 suppressed Aurora kinases. Therefore, ROR2 appears to regulate the cell cycle through Aurora kinases. The present results reveal a role for ROR2 in SCLC and afford a candidate system (ROR2-Aurora kinase) accompanying tumor heterogeneity in SCLC.

SIRT7 suppresses energy expenditure and thermogenesis by regulating brown adipose tissue functions in mice.

Brown adipose tissue plays a central role in the regulation of the energy balance by expending energy to produce heat. NAD+-dependent deacylase sirtuins have widely been recognized as positive regulators of brown adipose tissue thermogenesis. However, here we reveal that SIRT7, one of seven mammalian sirtuins, suppresses energy expenditure and thermogenesis by regulating brown adipose tissue functions. Whole-body and brown adipose tissue-specific Sirt7 knockout mice have higher body temperature and energy expenditure. SIRT7 deficiency increases the protein level of UCP1, a key regulator of brown adipose tissue thermogenesis. Mechanistically, we found that SIRT7 deacetylates insulin-like growth factor 2 mRNA-binding protein 2, an RNA-binding protein that inhibits the translation of Ucp1 mRNA, thereby enhancing its inhibitory action on Ucp1. Furthermore, SIRT7 attenuates the expression of batokine genes, such as fibroblast growth factor 21. In conclusion, we propose that SIRT7 serves as an energy-saving factor by suppressing brown adipose tissue functions.

Genome editing using a versatile vector-based CRISPR/Cas9 system in Fusarium species.

Fusarium species include important filamentous fungal pathogens that can infect plants, animals, and humans. Meanwhile, some nonpathogenic Fusarium species are promising biocontrol agents against plant pathogens. Here, we developed a genome editing technology using a vector-based CRISPR/Cas9 system for Fusarium oxysporum f. sp. lycopersici (Fol). This optimized CRISPR/Cas9 system, harboring an endogenous U6 small nuclear RNA promoter for the expression of single-guide RNA and an endogenous H2B nuclear localization signal for the localization of Cas9, enabled efficient targeted gene knock-out, including in the accessory chromosomal regions in Fol. We further demonstrated single crossover-mediated targeted base editing and endogenous gene tagging. This system was also applicable for genome editing in F. oxysporum f. sp. spinaciae and F. commune without any modifications, suggesting that this CRISPR/Cas9 vector has a potential application for a broad range of researches on other Fusarium species.

SIRT7 Deficiency Protects against Aß42-Induced Apoptosis through the Regulation of NOX4-Derived Reactive Oxygen Species Production in SH-SY5Y Cells.

Alzheimer's disease (AD) is an age-related neurodegenerative disease that is characterized by irreversible memory loss and cognitive decline. The deposition of amyloid-ß (Aß), especially aggregation-prone Aß42, is considered to be an early event preceding neurodegeneration in AD. Sirtuins (SIRT1-7 in mammals) are nicotinamide adenine dinucleotide-dependent lysine deacetylases/deacylases, and several sirtuins play important roles in AD. However, the involvement of SIRT7 in AD pathogenesis is not known. Here, we demonstrate that SIRT7 mRNA expression is increased in the cortex, entorhinal cortex, and prefrontal cortex of AD patients. We also found that Aß42 treatment rapidly increased NADPH oxidase 4 (NOX4) expression at the post-transcriptional level, and induced reactive oxygen species (ROS) production and apoptosis in neuronal SH-SY5Y cells. In contrast, SIRT7 knockdown inhibited Aß42-induced ROS production and apoptosis by suppressing the upregulation of NOX4. Collectively, these findings suggest that the inhibition of SIRT7 may play a beneficial role in AD pathogenesis through the regulation of ROS production.

Development of a DELFIA method to detect oncofetal antigen ROR1-positive exosomes.

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is highly expressed in a wide variety of hematological and solid cancers, but is low or absent in adult tissues. Here, we show that ROR1 is released with exosomes from ROR1-positive cancer cells. We also developed a simple dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA) to detect cancer-derived ROR1-positive exosomes, which are captured by two anti-ROR1 antibodies and detected by the fluorescence of free chelating europium. This new DELFIA method can detect cancer-derived ROR1-positive exosomes in the cell supernatant and serum with a wide range and rapidly compared with the conventional Western blot assay. This method may be useful as a companion diagnostics for ROR1-positive cancers.

Three-dimensional culture models mimic colon cancer heterogeneity induced by different microenvironments.

Colorectal cancer demonstrates intra-tumour heterogeneity formed by a hierarchical structure comprised of cancer stem cells (CSCs) and their differentiated progenies. The mechanism by which CSCs are maintained and differentiated needs to be further elucidated, and there is evidence that the tumour microenvironment governs cancer stemness. Using PLR123, a colon cancer cell line with CSC properties, we determined the culture conditions necessary to establish a pair of three-dimensional (3D) culture models grown in Matrigel, designated stemCO and diffCO. The conditions were determined by comparing the phenotypes in the models with PLR123 mouse xenografts colonising lung and liver. StemCO resembled LGR5-positive undifferentiated tumours in the lung, and diffCO had lumen structures composed of polarised cells that were similar to the ductal structures found in differentiated tumours in the liver. In a case using the models for biomedical research, treatment with JAG-1 peptide or a γ-secretase inhibitor modified the Notch signaling and induced changes indicating that the signal participates in lumen formation in the models. Our results demonstrate that culture conditions affect the stemness of 3D culture models generated from CSCs and show that comparing models with different phenotypes is useful for studying how the tumour environment regulates cancer.

ROR1-CAVIN3 interaction required for caveolae-dependent endocytosis and pro-survival signaling in lung adenocarcinoma.

The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a transcriptional target of the lineage-survival oncogene NKX2-1/TTF-1 in lung adenocarcinomas. In addition to its kinase-dependent role, ROR1 functions as a scaffold protein to facilitate interaction between caveolin-1 (CAV1) and CAVIN1, and consequently maintains caveolae formation, which in turn sustains pro-survival signaling toward AKT from multiple receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR), MET (proto-oncogene, receptor tyrosine kinase), and IGF-IR (insulin-like growth factor receptor 1). Therefore, ROR1 is an attractive target for overcoming EGFR-TKI resistance due to various mechanisms such as EGFR T790M double mutation and bypass signaling from other RTKs. Here, we report that ROR1 possesses a novel scaffold function indispensable for efficient caveolae-dependent endocytosis. CAVIN3 was found to bind with ROR1 at a site distinct from sites for CAV1 and CAVIN1, a novel function required for proper CAVIN3 subcellular localization and caveolae-dependent endocytosis, but not caveolae formation itself. Furthermore, evidence of a mechanistic link between ROR1-CAVIN3 interaction and consequential caveolae trafficking, which was found to utilize a binding site distinct from those for ROR1 interactions with CAV1 and CAVIN1, with RTK-mediated pro-survival signaling towards AKT in early endosomes in lung adenocarcinoma cells was also obtained. The present findings warrant future study to enable development of novel therapeutic strategies for inhibiting the multifaceted scaffold functions of ROR1 in order to reduce the intolerable death toll from this devastating cancer.