HIF‐2α activated lncRNA NEAT1 promotes hepatocellular carcinoma cell invasion and metastasis by affecting the epithelial‐mesenchymal transition

NEAT1 paraspeckle promotes human hepatocellular carcinoma progression by strengthening IL-6/STAT3 signaling

The formation of paraspeckle, a stress-induced nuclear body, increases in response to viral infection or proinflammatory stimuli. Paraspeckle consists of lncRNA (nuclear paraspeckle assembly transcript 1, NEAT1) and protein components including NONO, SFPQ, PSPC1, etc., which are shown to be involved in viral infection and cancer. Both NEAT1 and NONO expression increase in human hepatocellular carcinoma (HCC) samples according to TCGA data. However, the role of paraspeckle in HCC progression needs further identification. IL-6 signaling is well known to contribute to HCC progression. Here we reported that IL-6 signaling increased paraspeckle formation in HCC cells. Destruction of paraspeckle formation by silencing the paraspeckle essential components NEAT1_2 or NONO could suppress IL-6-induced STAT3 phosphorylation in HCC cells, and consequently repressed IL-6-promoted in vitro HCC cell invasion, cell cycle progression and survival. Mechanistically, paraspeckle promotes IL-6-induced STAT3 phosphorylation by binding and trapping peroxiredoxin-5 (PRDX5) mRNA in nucleus, decreasing protein level of PRDX5 which can directly interact with STAT3 and inhibit STAT3 phosphorylation. Besides, glutathione S-transferase P (GSTP1) protein, which inhibits DNA damage and apoptosis through its detoxification and anti-oxidation function, was also trapped within paraspeckles under IL-6 stimulation. Paraspeckle-trapping of both PRDX5 mRNA and GSTP1 protein contributes to IL-6-increased DNA damage in HCC cells. Our results demonstrate that paraspeckle can nuclear entrap the inhibitors of IL-6/STAT3 signaling as well as DNA damage, and then strengthen the promoting effect on HCC progression by IL-6. Therefore, paraspeckle contributes to the inflammation-related HCC progression and might be a potential therapeutic target for HCC.

Neat-en-ing up our understanding of p53 pathways in tumor suppression

Although the p53 transcription factor has a well-established role in tumor suppression, little is known about how the non-coding targets of p53 mediate its tumor suppression function. Analysis of ncRNAs regulated by p53 revealed Neat1 as a direct p53 target gene. Neat1 has physiological roles in the development and differentiation of the mammary gland and corpus luteum, but its roles in cancer have been conflicting. To unequivocally understand Neat1 function in cancer, we used Neat1 null mice. Interestingly, we found that Neat1 deficiency promotes transformation both in oncogene-expressing fibroblasts and in a mouse model for pancreatic cancer. Specifically, Neat1 loss in the pancreas results in the enhanced development of preneoplastic lesions associated with dampened expression of differentiation genes. While the exact mechanisms underlying tumor suppression are unknown, there are several described mechanisms that may be responsible for Neat1-mediated tumor suppression. Collectively, these findings suggest that Neat1 enforces differentiation to suppress pancreatic cancer.

Long non-coding RNA NEAT1 promoted ovarian cancer cells' metastasis through regulation of miR-382-3p/ROCK1 axial

Long non‐coding RNA (lncRNA) are extensively involved in various malignant tumors, including ovarian cancer (OC). In the present study, we focused on the expression and function of nuclear enriched abundant transcript 1 (NEAT1) in OC cells’ metastasis. We demonstrated that NEAT1 was upregulated in OC tissue specimens and cell lines. In addition, we revealed that depression of NEAT1 inhibited OC cells’ metastasis and the expression of Rho associated coiled‐coil containing protein kinase 1 (ROCK1), which is a metastasis‐related gene. Using online predictive software and a series of luciferase assays, we demonstrated that both NEAT1 and ROCK1 were the targets of microRNA‐382‐3p (miR‐382‐3p) and share similar microRNA responding elements (MRE). Furthermore, we illustrated that NEAT1 and miR‐382‐3p inhibited each other in a reciprocal manner. Finally, through antisense experiments we demonstrated that NEAT1 promoted ROCK1‐mediated metastasis by functioning as a ceRNA of miR‐382‐3p. In summary, the findings of this study revealed that NEAT1 promoted OC cells’ metastasis through regulating the miR‐382‐3p/ROCK1 axial. The present study might provide a new target for treating OC.

The Role of Long Non-Coding RNAs in Hepatocarcinogenesis

Whole-transcriptome analyses have revealed that a large proportion of the human genome is transcribed in non-protein-coding transcripts, designated as long non-coding RNAs (lncRNAs). Rather than being “transcriptional noise”, increasing evidence indicates that lncRNAs are key players in the regulation of many biological processes, including transcription, post-translational modification and inhibition and chromatin remodeling. Indeed, lncRNAs are widely dysregulated in human cancers, including hepatocellular carcinoma (HCC). Functional studies are beginning to provide insights into the role of oncogenic and tumor suppressive lncRNAs in the regulation of cell proliferation and motility, as well as oncogenic and metastatic potential in HCC. A better understanding of the molecular mechanisms and the complex network of interactions in which lncRNAs are involved could reveal novel diagnostic and prognostic biomarkers. Crucially, it may provide novel therapeutic opportunities to add to the currently limited number of therapeutic options for HCC patients. In this review, we summarize the current status of the field, with a focus on the best characterized dysregulated lncRNAs in HCC.