Two antisense RNAs-AFAP1-AS1 and MLK7-AS1-promote colorectal cancer progression by sponging miR-149-5p and miR-485-5p

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths. Antisense RNAs (asRNAs) are closely associated with cancer malignancy. This study aimed to identify the action mechanism of asRNAs in controlling CRC malignancy. Analysis of the RNA sequencing data revealed that AFAP1-AS1 and MLK7-AS1 were upregulated in CRC patients and cell lines. High levels of both asRNAs were associated with poor prognosis in patients with CRC. Both in vitro and in vivo experiments revealed that the knockdown of the two asRNAs decreased the proliferative and metastatic abilities of CRC cells. Mechanistically, AFAP1-AS1 and MLK7-AS1 decreased the levels of miR-149-5p and miR-485-5p by functioning as ceRNAs. Overexpression of miRNAs by introducing miRNA mimics suppressed the expression of SHMT2 and IGFBP5 by directly binding to the 3' UTR of their mRNA. Knockdown of both asRNAs decreased the expression of SHMT2 and IGFBP5, which was reversed by inhibition of both miRNAs by miRNA inhibitors. In vivo pharmacological targeting of both asRNAs by small interfering RNA-loaded nanoparticles showed that knockdown of asRNAs significantly reduced tumor growth and metastasis. Our findings demonstrate that AFAP1-AS1 and MLK7-AS1 promote CRC progression by sponging the tumor-suppressing miRNAs miR-149-5p and miR-485-5p, thus upregulating SHMT2 and IGFBP5.

Long Noncoding RNA MLK7-AS1 Promotes Non-Small-Cell Lung Cancer Migration and Invasion via the miR-375-3p/YWHAZ Axis

Long noncoding RNAs act essential regulators in lung cancer tumorigenesis. Our research aimed to investigate the potential function and molecular mechanisms of MLK7-AS1 in NSCLC (non-small-cell lung cancer). QRT-PCR results indicated that the MLK7-AS1 expression level was upregulated in NSCLC cells and tissues. MLK7-AS1 strengthened cell migration and invasion in H1299 and A549 cells. Luciferase reporter assay found that MLK7-AS1 functioned as an endogenous sponge for miR-375-3p. Transwell assay results showed that miR-375-3p suppressed cell migration and invasion in H1299 and A549 cells. YWHAZ was confirmed as a target gene of miR-375-3p by Targetscan. YWHAZ overexpression promoted the invasion of H1299 and A549 cells. MLK7-AS1 upregulated YWHAZ expression and enhanced H1299 and A549 cell invasion by sponging miR-375-3p. MLK7-AS1 improved the metastasis ability of A549 in vivo. In conclusion, MLK7-AS1 was identified as a novel oncogenic RNA in NSCLC and can function as a potential therapeutic target for NSCLC treatment.

Long noncoding RNA MLK7-AS1 promotes ovarian cancer cells progression by modulating miR-375/YAP1 axis

Background

Long noncoding RNAs (LncRNAs) have been reported to be abnormally expressed in human ovarian cancer and associated with the proliferation and metastasis of cancer cells. The objective of this study was to investigate the role and the underlying mechanisms of LncRNA MAP3K20 antisense RNA 1 (MLK7-AS1) in ovarian cancer.

Methods

The expression level of MLK7-AS1 was investigated in human ovarian cancer tissues and cell lines. The effects of MLK7-AS1 knockdown on ovarian cancer cell proliferation, migration, invasion and apoptosis were evaluated in vitro using MTT, colony formation assays, wound healing assays, transwell assays and flow cytometry. Furthermore, the in vivo effects were determined using the immunodeficient NSG female mice. Luciferase reporter assays were employed to identify interactions among MLK7-AS1 and its target genes.

Results

In the current study, MLK7-AS1 was specifically upregulated in ovarian cancer tissues and cell lines. Knockdown of MLK7-AS1 inhibited the ability of cell migration, invasion, proliferation, colony formation and wound healing, whereas promoted cell apoptosis in vitro. By using online tools and mechanistic analysis, we demonstrated that MLK7-AS1 could directly bind to miR-375 and downregulate its expression. Besides, MLK7-AS1 reversed the inhibitory effect of miR-375 on the growth of ovarian cancer cells, which might be involved in the upregulation of Yes-associated protein 1 (YAP1) expression. Moreover, knockdown MLK7-AS1 expression inhibited primary tumor growth in ovary and metastatic tumors in multiple peritoneal organs including liver and spleen in vivo, which were partly abolished by miR-375 inhibition. Mechanically, we found that MLK7-AS1 modulated the epithelial-mesenchymal transition (EMT) process by interacting with miR-375/YAP1 both in vivo and vitro, which promoted the expression of Slug.

Conclusions

Taken together, our study showed for the first time that MLK7-AS1 interacted with miR-375 to promote proliferation, metastasis, and EMT process in ovarian cancer cells through upregulating YAP1.

Knockdown of long non-coding RNA MAP3K20 antisense RNA 1 inhibits gastric cancer growth through epigenetically regulating miR-375

Emerging evidence has demonstrated that long noncoding RNAs (lncRNAs) play a critical role in tumorigenesis of gastric cancer. LncRNA MAP3K20 antisense RNA 1 (MLK7-AS1) has been identified as one of gastric cancer-specific lncRNAs. However, its precise role in gastric cancer remains unknown. In this study, we found that lncRNA MLK7-AS1 was significantly increased in gastric cancer tissues compared with in adjacent tissues. Gastric cancer patients with high MLK7-AS1 expression had a shorter survival and poorer prognosis. By loss-function assay, we demonstrated that knockdown of MLK7-AS1 inhibited cell proliferation and induced apoptosis in HGC27and MKN-45 cells. Furthermore, we identified miR-375 as a target of MLK7-AS1. MLK7-AS1 interacted with Dnmt1 and recruited it to miR-375 promotor, hyper-methylating miR-375 promotor and repressing miR-375 expression. Taken together, our findings demonstrate that knockdown of MLK7-AS1 by siRNA inhibits gastric cancer growth by epigenetically regulating miR-375. Thus, MLK7-AS1 may be a useful prognostic marker and therapeutic target for gastric cancer patients.