Aberrant RNA m6A modification in gastrointestinal malignancies: versatile regulators of cancer hallmarks and novel therapeutic opportunities.

Gastrointestinal (GI) cancer is one of the most common malignancies, and a leading cause of cancer-related death worldwide. However, molecular targeted therapies are still lacking, leading to poor treatment efficacies. As an important layer of epigenetic regulation, RNA N6-Methyladenosine (m6A) modification is recently linked to various biological hallmarks of cancer by orchestrating RNA metabolism, including RNA splicing, export, translation, and decay, which is partially involved in a novel biological process termed phase separation. Through these regulatory mechanisms, m6A dictates gene expression in a dynamic and reversible manner and may play oncogenic, tumor suppressive or context-dependent roles in GI tumorigenesis. Therefore, regulators and effectors of m6A, as well as their modified substrates, represent a novel class of molecular targets for cancer treatments. In this review, we comprehensively summarize recent advances in this field and highlight research findings that documented key roles of RNA m6A modification in governing hallmarks of GI cancers. From a historical perspective, milestone findings in m6A machinery are integrated with a timeline of developing m6A targeting compounds. These available chemical compounds, as well as other approaches that target core components of the RNA m6A pathway hold promises for clinical translational to treat human GI cancers. Further investigation on several outstanding issues, e.g. how oncogenic insults may disrupt m6A homeostasis, and how m6A modification impacts on the tumor microenvironment, may dissect novel mechanisms underlying human tumorigenesis and identifies next-generation anti-cancer therapeutics. In this review, we discuss advances in our understanding of m6A RNA modification since its discovery in the 1970s to the latest progress in defining its potential clinic relevance. We summarize the molecular basis and roles of m6A regulators in the hallmarks of GI cancer and discuss their context-dependent functions. Furthermore, the identification and characterization of inhibitors or activators of m6A regulators and their potential anti-cancer effects are discussed. With the rapid growth in this field there is significant potential for developing m6A targeted therapy in GI cancers.

Repellency and insecticidal activity of seven Mugwort (Artemisia argyi) essential oils against the malaria vector Anopheles sinensis.

Anopheles sinensis is the main vector of malaria with a wide distribution in China and its adjacent countries. The smoke from burning dried mugwort leaves has been commonly used to repel and kill mosquito adults especially in southern Chinese provinces. In this study, the essential oils of mugwort leaves collected from seven provinces in China were extracted by steam distillation and their chemical compositions were analyzed. Among a total of 56-87 chemical constituents confirmed by GC-MS analyses, four compounds, eucalyptol, ß-caryophyllene, phytol and caryophyllene oxide, were identified with appearances from all seven distilled essential oils. The effectiveness varied in larvicidal, fumigant and repellent activities against An. sinensis from these seven essential oils with different geographic origins. The essential oil from Hubei province showed the highest larvicidal activity against the 4th instar larvae of An. sinensis, with a median lethal concentration at 40.23 µg/mL. For fumigation toxicity, essential oils from 4 provinces (Gansu, Shandong, Sichuan and Henan) were observed with less than 10 min in knockdown time. The essential oil distilled from Gansu province displayed the highest repellent activity against Anopheles mosquitoes and provided similar level of protection as observed from DEET. Eucalyptol was the most toxic fumigant compound and phytol showed the strongest larvicidal activity among all tested mugwort essential oil constituents.

Pericytes augment glioblastoma cell resistance to temozolomide through CCL5-CCR5 paracrine signaling.

Glioblastoma (GBM) is a prevalent and highly lethal form of glioma, with rapid tumor progression and frequent recurrence. Excessive outgrowth of pericytes in GBM governs the ecology of the perivascular niche, but their function in mediating chemoresistance has not been fully explored. Herein, we uncovered that pericytes potentiate DNA damage repair (DDR) in GBM cells residing in the perivascular niche, which induces temozolomide (TMZ) chemoresistance. We found that increased pericyte proportion correlates with accelerated tumor recurrence and worse prognosis. Genetic depletion of pericytes in GBM xenografts enhances TMZ-induced cytotoxicity and prolongs survival of tumor-bearing mice. Mechanistically, C-C motif chemokine ligand 5 (CCL5) secreted by pericytes activates C-C motif chemokine receptor 5 (CCR5) on GBM cells to enable DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-mediated DDR upon TMZ treatment. Disrupting CCL5-CCR5 paracrine signaling through the brain-penetrable CCR5 antagonist maraviroc (MVC) potently inhibits pericyte-promoted DDR and effectively improves the chemotherapeutic efficacy of TMZ. GBM patient-derived xenografts with high CCL5 expression benefit from combined treatment with TMZ and MVC. Our study reveals the role of pericytes as an extrinsic stimulator potentiating DDR signaling in GBM cells and suggests that targeting CCL5-CCR5 signaling could be an effective therapeutic strategy to improve chemotherapeutic efficacy against GBM.

Electroporation-mediated nucleic acid delivery during non-embryonic stages for gene-function analysis in Anopheles sinensis.

The delivery of exogenous nucleic acids to eggs or non-embryonic individuals by microinjection is a vital reverse genetics technique used to determine gene function in mosquitoes. However, DNA delivery to eggs is complex and time-consuming, and conventional, non-embryonic-injection techniques may result in unobvious phenotypes caused by insufficient absorption of nucleic acid fragments by cells at target body parts or tissues. In this study, we developed a set of electroporation-mediated non-embryonic microinjections for the delivery of exogenous nucleic acids in Anopheles sinensis. Gene silencing using this method led to down-regulation of target gene expression (AsCPR128) by 77% in targeted body parts, compared with only 10% in non-targeted body parts, thus increasing the defect-phenotype rate in the target area by 5.3-fold, compared with non-shock injected controls. Electroporation-mediated somatic transgenesis resulted in stable phenotypic characteristics of the reporter gene at the shocked body parts during the pupal-adult stages in about 69% of individuals. Furthermore, injecting plasmid DNA near the ovaries of female mosquitoes after a blood meal followed by electric shock produced three germline G1 transgenic lines, with a transformation rate of about 11.1% (calculated from ovulatory G0 females). Among the positive G1 lines, 42%, 40%, and 31% of individuals emitted red fluorescence in the larval stage. When the red fluorescent larvae developed into adults, green fluorescence was emitted from the ovaries of the females upon feeding. These results suggest that electroporation-mediated non-embryonic microinjection can be an efficient, rapid, and simple technique for analyzing gene function in non-model mosquitoes or other small insects.

SHARPIN stabilizes ß-catenin through a linear ubiquitination-independent manner to support gastric tumorigenesis.

BACKGROUND: Aberrant activation of Wnt/ß-catenin signaling by dysregulated post-translational protein modifications, especially ubiquitination is causally linked to cancer development and progression. Although Lys48-linked ubiquitination is known to regulate Wnt/ß-catenin signaling, it remains largely obscure how other types of ubiquitination, such as linear ubiquitination governs its signaling activity. METHODS: The expression and regulatory mechanism of linear ubiquitin chain assembly complex (LUBAC) on Wnt/ß-catenin signaling was examined by immunoprecipitation, western blot and immunohistochemical staining. The ubiquitination status of ß-catenin was detected by ubiquitination assay. The impacts of SHARPIN, a core component of LUBAC on malignant behaviors of gastric cancer cells were determined by various functional assays in vitro and in vivo. RESULTS: Unlike a canonical role in promoting linear ubiquitination, SHARPIN specifically interacts with ß-catenin to maintain its protein stability. Mechanistically, SHARPIN competes with the E3 ubiquitin ligase ß-Trcp1 for ß-catenin binding, thereby decreasing ß-catenin ubiquitination levels to abolish its proteasomal degradation. Importantly, SHARPIN is required for invasiveness and malignant growth of gastric cancer cells in vitro and in vivo, a function that is largely dependent on its binding partner ß-catenin. In line with these findings, elevated expression of SHARPIN in gastric cancer tissues is associated with disease malignancy and correlates with ß-catenin expression levels. CONCLUSIONS: Our findings reveal a novel molecular link connecting linear ubiquitination machinery and Wnt/ß-catenin signaling via SHARPIN-mediated stabilization of ß-catenin. Targeting the linear ubiquitination-independent function of SHARPIN could be exploited to inhibit the hyperactive ß-catenin signaling in a subset of human gastric cancers.

Excess melanin precursors rescue defective cuticular traits in stony mutant silkworms probably by upregulating four genes encoding RR1-type larval cuticular proteins.

Melanin and cuticular proteins are vital cuticle components in insects. Cuticular defects caused by mutations in cuticular protein-encoding genes can obstruct melanin deposition. The effects of changes in melanin on the expression of cuticular protein-encoding genes, the cuticular and morphological traits, and the origins of these effects are unknown. We found that the cuticular physical characteristics and the expression patterns of larval cuticular protein-encoding genes markedly differed between the melanic and non-melanic integument regions. By using four p multiple-allele color pattern mutants with increasing degrees of melanism (+p, pM, pS, and pB), we found that the degree of melanism and the expression of four RR1-type larval cuticular protein-encoding genes (BmCPR2, BmLcp18, BmLcp22, and BmLcp30) were positively correlated. By modulating the content of melanin precursors and the expression of cuticular protein-encoding genes in cells in tissues and in vivo, we showed that this positive correlation was due to the induction of melanin precursors. More importantly, the melanism trait introduced into the BmCPR2 deletion strain Dazao-stony induced up-regulation of three other similar chitin-binding characteristic larval cuticular protein-encoding genes, thus rescuing the cuticular, morphological and adaptability defects of the Dazao-stony strain. This rescue ability increased with increasing melanism levels. This is the first study reporting the induction of cuticular protein-encoding genes by melanin and the biological importance of this induction in affecting the physiological characteristics of the cuticle.