CircUGGT2 downregulation by METTL14-dependent m6A modification suppresses gastric cancer progression and cisplatin resistance through interaction with miR-186-3p/MAP3K9 axis.

Chemoresistance is a major therapeutic challenge in advanced gastric cancer (GC). N6-methyladenosine (m6A) RNA modification has been shown to play fundamental roles in cancer progression. However, the underlying mechanisms by which m6A modification of circRNAs contributes to GC and chemoresistance remain unknown. We found that hsa_circ_0030632 (circUGGT2) was a predominant m6A target of METTL14, and METTL14 knockdown (KD) reduced circUGGT2 m6A levels but increased its mRNA levels. The expression of circUGGT2 was markedly increased in cisplatin (DDP)-resistant GC cells. CircUGGT2 KD impaired cell growth, metastasis and DDP-resistance in vitro and in vivo, but circUGGT2 overexpression prompted these effects. Furthermore, circUGGT2 was validated to sponge miR-186-3p and upregulate MAP3K9 and could abolish METTL14-caused miR-186-3p upregulation and MAP3K9 downregulation in GC cells. circUGGT2 negatively correlated with miR-186-3p expression and harbored a poor prognosis in patients with GC. Our findings unveil that METTL14-dependent m6A modification of circUGGT2 inhibits GC progression and DDP resistance by regulating miR-186-3p/MAP3K9 axis.

MiR-186-3p attenuates tumorigenesis of cervical cancer by targeting IGF1.

BACKGROUND: Mounting evidence in the cancer literature suggests that microRNAs (miRNAs) influence the progression of human cancer cells by targeting protein-coding genes. How insulin-like growth factor 1(IGF1) and miR-186-3p contribute to the development of cervical cancer (CC) remains unclear. This study examined the regulatory roles of miR-186-3p and IGF1 in CC development. METHODS: Gene expression levels were determined by qRT-PCR. Proliferation, migration, and apoptosis of CC and normal cells were determined by MTT, Transwell, and caspase-3 activity assays, respectively. Dual-luciferase reporter activity and RNA pull-down assays were performed to identify the target gene of miR-186-3p. RESULTS: IGF1 was the target of miR-186-3p. The expression of miR-186-3p inhibited cell proliferation and migration abilities of CC cell lines, but induced the apoptosis rate of CC cells. IGF1 could restore the inhibitory effects of miR-186-3p on the proliferation, migration, and apoptosis abilities of CC cells. Experimental results revealed that miR-186-3p could inhibit IGF1 expression, thereby reducing the viability of CC cells. CONCLUSIONS: The data suggest that targeting of IGF1 by miR-186-3p could be crucial in regulating the progression of CC.

LINC00460/miR-186-3p/MYC feedback loop facilitates colorectal cancer immune escape by enhancing CD47 and PD-L1 expressions.

BACKGROUND: Long non-coding RNAs (LncRNAs) have been implicated as critical regulators of cancer tumorigenesis and progression. However, their functions and molecular mechanisms in colorectal cancer (CRC) still remain to be further elucidated. METHODS: LINC00460 was identified by differential analysis between human CRC and normal tissues and verified by in situ hybridization (ISH) and qRT-PCR. We investigated the biological functions of LINC00460 in CRC by in vitro and in vivo experiments. We predicted the mechanism and downstream functional molecules of LINC00460 by bioinformatics analysis, and confirmed them by dual luciferase reporter gene assay, RNA immunoprecipitation (RIP), RNA pull-down, etc. RESULTS: LINC00460 was found to be significantly overexpressed in CRC and associated with poor prognosis. Overexpression of LINC00460 promoted CRC cell immune escape and remodeled a suppressive tumor immune microenvironment, thereby promoting CRC proliferation and metastasis. Mechanistic studies showed that LINC00460 served as a molecular sponge for miR-186-3p, and then promoted the expressions of MYC, CD47 and PD-L1 to facilitate CRC cell immune escape. We also demonstrated that MYC upregulated LINC00460 expression at the transcriptional level and formed a positive feedback loop. CONCLUSIONS: The LINC00460/miR-186-3p/MYC feedback loop promotes CRC cell immune escape and subsequently facilitates CRC proliferation and metastasis. Our findings provide novel insight into LINC00460 as a CRC immune regulator, and provide a potential therapeutic target for CRC patients.

Hsa-miR-186-3p suppresses colon cancer progression by inhibiting KRT18/MAPK signaling pathway.

This study aimed to determine the effect of miR-186-3p and KRT18 interaction on the biological behavior of colon cancer cells. A biotin-microRNA pull-down assay was performed to identify potential miRNAs. qRT-PCR was used to verify the KRT18 and miR-186-3p levels. In addition, Western blotting was used to detect the KRT18 protein levels. The functional connection between KRT18 and miR-186-3p was confirmed using a dual luciferase reporter assay. BrdU incorporation, MTT assay, and flow cytometry were performed to verify the biological function coupled with in vivo assays. A significant decrease in miR-186-3p expression was observed in colon carcinoma tissues and cells. Functionally, overexpression of miR-186-3p displayed an obvious suppressive action on cell proliferation and viability, and a stimulatory action on the apoptotic ability of SW620 and SW480 cells. Conversely, reduced miR-186-3p had a marked stimulatory effect on proliferation and viability, and a suppressive apoptotic effect. Inhibition of tumorigenesis was observed in mice treated with the miR-186-3p agomir. Furthermore, we identified that miR-186-3p regulated KRT18 levels in colon carcinoma, where silenced KRT18 suppressed proliferation and viability and promoted apoptosis. However, the addition of a miR-186-3p inhibitor weakened the effects of si-KRT18. Additionally, the activation of MAPK signaling pathway upon miR-186-3p silencing was antagonized by the combined transfection of si-KRT18 and miR-186-3p inhibitor. miR-186-3p suppresses proliferation and viability, but facilitates apoptosis in colon cancer cells by targeting KRT18 and negatively regulating the MAPK signaling pathway, indicating that the miR-186-3p/KRT18 axis may be a promising therapeutic target for colon carcinoma.Abbreviations: KRT18: keratin 18; NC: negative control; si­: small interfering RNA; inhibitor: miR-186-3p inhibitor; OD: optical density; PI: propidium iodide; FITC: fluorescein isothiocyanate; 3'UTR: 3'untranslated region; WT: wild-type; MUT: mutant-type; miR: microRNA.

Kinesin family member 3C (KIF3C) is a novel non-small cell lung cancer (NSCLC) oncogene whose expression is modulated by microRNA-150-5p (miR-150-5p) and microRNA-186-3p (miR-186-3p).

This study is aimed at investigating the biological function of kinesin family member 3 C (KIF3C) in non-small cell lung cancer (NSCLC) progression and its upstream regulatory mechanism. Quantitative real-time PCR, Western blot and immunohistochemistry were adopted to examine microRNA-150-5p (miR-150-5p), microRNA-186-3p (miR-186-3p) and kinesin family member 3 C (KIF3C) expression levels. NSCLC cell proliferation, migration, and invasion were detected through cell counting kit-8 (CCK-8) assay, EdU assay, and Transwell assay. The metastasis of NSCLC cells was evaluated utilizing a pulmonary metastasis model in nude mice in vivo. The targeted relationship among KIF3C 3'UTR, miR-186-3p, and miR-150-5p were verified by dual-luciferase reporter gene assays. It was confirmed that in NSCLC tissues and cells, KIF3C expression level was increased and KIF3C overexpression promoted NSCLC cell proliferation and metastasis. Additionally, miR-150-5p and miR-186-3p directly targeted KIF3C to repress its expression. Our data suggest that KIF3C, which is negatively regulated by miR-150-5p and miR-186-3p, is an oncogenic factor in NSCLC progression.

miR-186-3p attenuates the tumorigenesis of cervical cancer via targeting insulin-like growth factor 1 to suppress PI3K-Akt signaling pathway.

miR-186-3p acts as a tumor suppressor in various cancers. This study aimed to explore the expression levels of miR-186-3p and its role in cervical cancer. We analyzed the effects of miR-186-3p and insulin-like growth factor 1 (IGF1) on the proliferation, invasion, and apoptosis of cervical cancer cells in vitro by regulating the PI3K/Akt signaling pathway. In cervical cancer tissues and cells, miR-186-3p was downregulated, and IGF1 was upregulated. In addition, miR-186-3p inhibited cell proliferation and invasion and enhanced apoptosis of cervical cancer cells. Moreover, our results showed that miR-186-3p inversely regulated the mRNA expression of IGF1 through direct contact. Knockdown of IGF1 reversed the results of miR-186-3p inhibitor in cervical cancer cells. In addition, the PI3K/Akt signaling pathway was activated by the miR-186-3p inhibitor, although partially arrested by IGF1 knockdown. The PI3K/Akt signaling pathway inhibitor suppressed miR-186-3p inhibitor-stimulated cell proliferation in cervical cancer. In conclusion, miR-186-3p inhibits tumorigenesis of cervical cancer by repressing IGF1, which inactivates the PI3K/Akt signaling pathway, implicating miR-186-3p as a potential new target for the treatment of cervical cancer.