Background: Exosomes are vesicles of endocytic origin released by various cell types and emerging as important mediators in tumor cells. Human metastases-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA known to promote cell proliferation, metastasis, and invasion in colorectal cancer (CRC).Methods: The expression of MALAT1 was analyzed in CRC using qRT-PCR. FUT4 and fucosylation levels were detected in CRC clinical samples and CRC cell lines by immunofluorescent staining, western blot and lectin blot analysis. CRC derived exosomes were isolated and used to examine their tumor-promoting effects in vitro and in vivo. Results:The invasive and metastatic abilities of primary CRC cells were enhanced after exposure to exosomes derived from highly metastatic CRC cells, which increased the fucosyltransferase 4 (FUT4) levels and fucosylation not by directly transmitting FUT4 mRNA. Exosomal MALAT1 increased FUT4 expresssion via sponging miR-26a/26b. Furthermore, MALAT1/miR-26a/26b/FUT4 axis played an important role in exosome-mediated CRC progression. Exosomal MALAT1 also mediated FUT4-associated fucosylation and activated the PI3K/AKT/mTOR pathway.Conclusions: These data indicated that exosomal MALAT1 promoted the malignant behavior of CRC cells by sponging miR-26a/26b via regulating FUT4 and activating PI3K/Akt/mTOR pathway.Keywords: CRC, Exosomal MALAT1, FUT4, miR-26a/26b, PI3K/Akt/mTOR pathway Background Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality [1,2]. More than 60% of CRC patients have initiated the metastatic process by the time of diagnosis [3]. Although there are multiple tests available for CRC screening, each method has its own limitations in terms of sensitivity and specificity. To the best of our knowledge, carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are well established tumor markers with low sensitivity and specificity for early detection of CRC [4]. Hence, ideal CRC-specific biomarkers are urgently required to improve the current CRC diagnostic strategies.Exosomes, membrane vesicles of endocytic origin ranging in size from 30 to 150 nm approximately, are emerging as key players in intercellular communication between cancer cells and their microenvironment [5]. A distinct feature of exosomes is that they efficiently carry and deliver molecular signatures (proteins, lipids, RNA

IntroductionThe development of drug resistance is the main obstacle for successful treatment in acute myeloid leukemia (AML). Noncoding RNAs have been implicated in biological function in AML drug resistance. Aberrant protein glycosylation is associated with AML progression. The aim of the study was to explore the potential regulatory mechanism of lncRNA MEG3/miR‐155/ALG9 axis in drug resistance of AML.MethodsQRT‐PCR and Western blot were used for comparison analyses of ALG9, MEG3, and miR‐155 levels. CCK‐8 and colony formation assays were determined for drug sensitivity and proliferative capability of AML cells. Luciferase reporter assay was used to confirm the targets of miR‐155.ResultsThe mannosyltransferase ALG9 and MEG3 was downregulated in peripheral blood mononuclear cells (PBMCs) of M5/multidrug resistance (MDR) AML patients and adriamycin (ADR)‐resistant AML cell lines, which determined a positive correlation in AML patients. Low expression of ALG9 and MEG3 predicted poor prognosis of AML patients. The altered level of ALG9 was found corresponding to the drug‐resistant phenotype and sphere formation of AML cells. MiR‐155 was overexpressed in M5/MDR patients and ADR‐resistant AML cells, as well as inversely correlated to ALG9 expression. MEG3 was a direct target of miR‐155 and could sponge miR‐155 in AML cells. MEG3 interacted with miR‐155 to regulate ALG9 expression, which reversed the effects of ALG9 regulation on proliferation and drug resistance in AML cells.ConclusionMEG3 sponged miR‐155 by competing endogenous RNA (ceRNA) mechanism, which further modulated ALG9 expression and AML procession, providing a novel therapeutic target for AML chemoresistance.

BackgroundThe regulatory non-coding RNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), emerge as pivotal markers during tumor progression. Abnormal sialylated glycoprotein often leads to the malignancy of colorectal cancer (CRC).MethodsDifferential levels of HOTAIR and ST6GAL1 are analyzed by qRT-PCR. Functionally, CRC cell proliferation, aggressiveness and apoptosis are measured through relevant experiments, including CCK8 assay, colony formation assay, transwell assay, western blot and flow cytometry. Dual-luciferase reporter gene assay and RIP assay confirm the direct interaction between HOTAIR and miR-214. The lung metastasis, liver metatstasis and xenografts nude mice models are established to show the in vivo effect of HOATIR.ResultsHere, differential levels of HOTAIR and ST6GAL1 are primarily observed in CRC samples and cells. Upregulated HOTAIR and ST6GAL1 are crucial predictors for poor CRC prognosis. Altered level of ST6GAL1 modulates CRC malignancy. Furthermore, ST6GAL1 and HOTAIR are confirmed as the direct targets of miR-214, and ST6GAL1 is regulated by HOTAIR via sponging miR-214. ST6GAL1 induces the elevated metabolic sialylation of c-Met, which is co-mediated by HOTAIR and miR-214. Sialylated c-Met affects the activity of JAK2/STAT3 pathway. The regulatory role of HOTAIR/miR-214/ST6GAL1 axis also impacts CRC procession. In addition, HOTAIR mediates lung metastasis, liver metastasis and tumorigenesis in vivo. ShHOTAIR and AMG-208 are combined to inhibit tumorigenesis for successful drug development.ConclusionThe HOTAIR/miR-214/ST6GAL1 axis commands the CRC malignancy by modifying c-Met with sialylation and activating JAK2/STAT3 pathway. Our study presents novel insights into CRC progression and provided prospective therapeutic target for CRC.

No abstract

Long noncoding RNAs (lncRNAs) have emerged as important regulators of cancer progression. Abnormal sialylation leads to renal cell carcinoma (RCC) malignancy. However, the mechanism by which the lncRNA maternally expressed gene 3 (MEG3) mediates RCC progression by regulating ST3Gal1 transcription and EGFR sialylation is still unrevealed. Here, we found that the expression of MEG3 was higher in adjacent tissues than in RCC tissues, as well as downregulated in RCC cell lines compared to expression in normal renal cells. The proliferation, migration and invasion of RCC cells transfected with MEG3 was decreased, whereas knockdown of MEG3 had the opposite effect. The proliferative and metastatic abilities of RCC cells in vivo were concordant with their behavior in vitro. ST3Gal1 expression was dysregulated in RCC and was positively correlated with MEG3. By applying bioinformatics, c-Jun (also known as JUN) was identified as a transcription factor predicted to bind the promoter of ST3Gal1, and altered MEG3 levels resulted in changes to c-Jun expression. Furthermore, ST3Gal1 modulated EGFR sialylation to inhibit EGFR phosphorylation, which affected activation of the phosphoinositide 3-kinase (PI3K)–AKT pathway. Taken together, our findings provide a novel mechanism to elucidate the role of the MEG3–ST3Gal1–EGFR axis in RCC progression.