METTL3-mediated the m6A modification of SF3B4 facilitates the development of non-small cell lung cancer by enhancing LSM4 expression

BACKGROUND

Splicing factor B subunit 4 (SF3B4) has been confirmed to participate in the progression of many cancers and is considered to be a potential target for non-small cell lung cancer (NSCLC). Thus, the role and molecular mechanism of SF3B4 in NSCLC progression deserves further study.

METHODS

Quantitative real-time PCR and western blot were employed to detect the mRNA and protein levels of SF3B4, Sm-like protein 4 (LSM4) and methyltransferase-like 3 (METTL3). Cell proliferation, apoptosis, invasion, migration and stemness were tested by cell counting kit-8, colony formation, flow cytometry, transwell, wound healing, and sphere formation assays. The interaction between SF3B4 and METTL3 or LSM4 was confirmed by MeRIP, RIP and Co-IP assays. Mice xenograft models were constructed to assess the effects of METTL3 and SF3B4 on NSCLC tumorigenesis.

RESULTS

SF3B4 had high expression in NSCLC tissues and was associated with the shorter overall survival of NSCLC patients. Knockdown of SF3B4 suppressed NSCLC cell proliferation, invasion, migration and stemness, while inducing apoptosis. METTL3 promoted SF3B4 mRNA stability by m6A modification, and its knockdown inhibited NSCLC cell growth, metastasis and stemness by downregulating SF3B4. SF3B4 could interact with LSM4, and sh-SF3B4-mediated the inhibition on NSCLC cell functions could be reversed by LSM4 overexpression. In addition, reduced METTL3 expression restrained NSCLC tumor growth, and this effect was reversed by SF3B4 overexpression.

CONCLUSION

METTL3-stablized SF3B4 promoted NSCLC cell growth, metastasis and stemness via positively regulating LSM4.

Yeast Lsm Pro-Apoptotic Mutants Show Defects in Autophagy

LSM4 is an essential yeast gene encoding a component of different LSM complexes involved in the regulation of mRNA splicing, stability, and translation. In previous papers, we reported that the expression in S. cerevisiae of the K. lactis LSM4 gene lacking the C-terminal Q/N-rich domain in an Lsm4 null strain S. cerevisiae (Sclsm4Δ1) restored cell viability. Nevertheless, in this transformed strain, we observed some phenotypes that are typical markers of regulated cell death, reactive oxygen species (ROS), and oxidated RNA accumulation. In this paper, we report that a similar truncation operated in the S. cerevisiae LSM4 gene confers on cells the same phenotypes observed with the K. lactis lsm4Δ1 gene. Up until now, there was no evidence of the direct involvement of LSM4 in autophagy. Here we found that the Sclsm4Δ1 mutant showed a block in the autophagic process and was very sensitive to nitrogen starvation or treatment with low doses of rapamycin, an inducer of autophagy. Moreover, both during nitrogen starvation and aging, the Sclsm4Δ1 mutant accumulated cytoplasmic autophagy-related structures, suggesting a role of Lsm4 in a later step of the autophagy process.

Long noncoding RNA LINC01419 promotes hepatocellular carcinoma malignancy by mediating miR-485-5p/LSM4 axis

To investigate the effect of long noncoding RNA (LINC01419)/miR-485-5p/LSM4 on the malignant behavior of hepatocellular carcinoma (HCC) cells. The expressions of LINC01419, miR-485-5p, and LSM4 were determined in HCC at the cellular and clinical levels, and cell biological behavior was evaluated. The relationships between LINC01419, miR-485-5p, and LSM4 were predicted and verified. Additionally, the subcellular localization of LINC01419 in HCC cells was analyzed. Finally, an animal experiment was conducted to confirm the effect of LINC01419 silencing on tumor growth. in HCC tissues and cells, LINC01419 and LSM4 were increasingly expressed, but miR-485-5p was decreasingly expressed. LINC01419 negatively regulated miR-485-5p- and miR-485-5p-targeted LSM4. LINC01419 was localized in the cytoplasm of HCC cells. Downregulation of miR-485-5p or upregulation of LSM4 reversed the inhibition of HCC cell malignant behavior by LINC01419 interference. LINC01419 sponges miR-485-5p to upregulate LSM4 expression, thereby facilitating the biological behavior of HCC cells.

Clinical Significance and Potential Role of LSM4 Overexpression in Hepatocellular Carcinoma: An Integrated Analysis Based on Multiple Databases

Background: Hepatocellular carcinoma (HCC) is a solid tumor with high recurrence rate and high mortality. It is crucial to discover available biomarkers to achieve early diagnosis and improve the prognosis. The effect of LSM4 in HCC still remains unrevealed. Our study is dedicated to exploring the expression of LSM4 in HCC, demonstrating its clinical significance and potential molecular mechanisms.

Methods: Clinical information and LSM4 expression values of HCC were obtained from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. Survival analysis and receiver operating characteristic (ROC) curve analysis were applied to evaluate the prognostic and diagnostic significance of LSM4. Calculating pooled standardized mean difference (SMD) and performing summary receiver operating characteristic (sROC) curve analysis to further determine its expression status and diagnostic significance. LSM4-related co-expressed genes (CEGs) were obtained and explored their clinical significance in HCC. LSM4-associated pathways were identified through Gene set enrichment analysis (GSEA).

Results: Up-regulated LSM4 was detected in HCC tissues (SMD = 1.56, 95% CI: 1.29–1.84) and overexpressed LSM4 had excellent distinguishing ability (AUC = 0.91, 95% CI: 0.88–0.93). LSM4 was associated with clinical stage, tumor grade, and lymph node metastasis status (p < 0.05). Survival analysis showed that high LSM4 expression was related to poor overall survival (OS) of HCC patients. Cox regression analysis suggested that high LSM4 expression may be an independent risk factor for HCC. We obtained nine up-regulated CEGs of LSM4 in HCC tissues, and six CEGs had good prognostic and diagnostic significance. GSEA analysis showed that up-regulated LSM4 was closely related to the cell cycle, cell replication, focal adhesion, and several metabolism-associated pathways, including fatty acid metabolism.

Conclusion: Overexpressed LSM4 may serve as a promising diagnostic and prognostic biomarker of HCC. Besides, LSM4 may play a synergistic effect with CEGs in promoting the growth and metastasis of HCC cells via regulating crucial pathways such as cell cycle, focal adhesion, and metabolism-associated pathways.

AtMC1 Associates With LSM4 to Regulate Plant Immunity Through Modulating Pre-mRNA Splicing

Alternative splicing of pre-mRNAs is an important gene regulatory mechanism shaping the transcriptome. AtMC1 is an Arabidopsis thaliana type I metacaspase that positively regulates the hypersensitive response. Here, we found that AtMC1 is involved in the regulation of plant immunity to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 and is physically associated with Sm-like4 (LSM4), which is involved in pre-mRNA splicing. AtMC1 and LSM4 protein levels both increased with their coexpression as compared with their separate expression in vivo. Like AtMC1, LSM4 negatively regulates plant immunity to P. syringae pv. tomato DC3000 infection. By RNA sequencing, AtMC1 was shown to modulate the splicing of many pre-mRNAs, including 4CL3, which is a negative regulator of plant immunity. Thus, AtMC1 plays a regulatory role in pre-mRNA splicing, which might contribute to AtMC1-mediated plant immunity.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Potential Therapeutic and Prognostic Values of LSM Family Genes in Breast Cancer

In recent decades, breast cancer (BRCA) has become one of the most common diseases worldwide. Understanding crucial genes and their signaling pathways remain an enormous challenge in evaluating the prognosis and possible therapeutics. The "Like-Smith" (LSM) family is known as protein-coding genes, and its member play pivotal roles in the progression of several malignancies, although their roles in BRCA are less clear. To discover biological processes associated with LSM family genes in BRCA development, high-throughput techniques were applied to clarify expression levels of LSMs in The Cancer Genome Atlas (TCGA)-BRCA dataset, which was integrated with the cBioPortal database. Furthermore, we investigated prognostic values of LSM family genes in BCRA patients using the Kaplan-Meier database. Among genes of this family, LSM4 expression levels were highly associated with poor prognostic outcomes with a hazard ratio of 1.35 (95% confidence interval 1.21-1.51, p for trend = 3.4 × 10-7). MetaCore and GlueGo analyses were also conducted to examine transcript expression signatures of LSM family members and their coexpressed genes, together with their associated signaling pathways, such as "Cell cycle role of APC in cell cycle regulation" and "Immune response IL-15 signaling via MAPK and PI3K cascade" in BRCA. Results showed that LSM family members, specifically LSM4, were significantly correlated with oncogenesis in BRCA patients. In summary, our results suggested that LSM4 could be a prospective prognosticator of BRCA.

Circ_0025033 promotes the progression of ovarian cancer by activating the expression of LSM4 via targeting miR-184

BACKGROUND

Ovarian cancer (OC) is the leading disorder to threaten women's lives. Numerous circular RNAs (circRNAs) were identified in cancers with dysregulation and involved in the pathogenesis of cancer. This study investigated the function and regulatory mechanism of circ_0025033 in OC development, aiming to provide a potential strategy for OC treatment.

METHODS

For expression analysis, the expression levels of circ_0025033, LSM4 mRNA and miR-184 were detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the protein level of LSM4 expression was detected by western blot. For functional analysis, the capacities of colony formation, migration/invasion and glycolysis metabolism were assessed by colony formation assay, transwell assay and the levels of glucose consumption and lactate production. The interaction between miR-184 and circ_0025033 or LSM4 was predicted by the bioinformatics tool and validated by dual-luciferase reporter assay. Xenograft models were established to determine the role of circ_0025033 in vivo.

RESULTS

The expression of circ_0025033 and LSM4 was promoted in OC tissues and cells. Circ_0025033 knockdown or LSM4 knockdown blocked the ability of colony formation, migration/invasion and glycolysis metabolism in OC cells. In mechanism, circ_0025033 functioned as a "competing endogenous RNA (ceRNA)" to modulate LSM4 expression by targeting miR-184. LSM4 overexpression recovered the inhibitory effects on colony formation, migration/invasion and glycolysis metabolism caused by circ_0025033 knockdown. Moreover, circ_0025033 knockdown also inhibited tumor growth in vivo by regulating LSM4 and targeting miR-184.

CONCLUSION

Circ_0025033 promotes the progression of OC by regulating LSM4 expression via targeting miR-184, which provided a new strategy to treat OC.