Long Non-coding RNA ST8SIA6-AS1 Promotes Lung Adenocarcinoma Progression Through Sponging miR-125a-3p

When a negative (charge) is not a positive: sialylation and its role in cancer mechanics and progression

Sialic acids and sialoglycans are critical actors in cancer progression and metastasis. These terminal sugar residues on glycoproteins and glycolipids modulate key cellular processes such as immune evasion, cell adhesion, and migration. Aberrant sialylation is driven by overexpression of sialyltransferases, resulting in hypersialylation on cancer cell surfaces as well as enhancing tumor aggressiveness. Sialylated glycans alter the structure of the glycocalyx, a protective barrier that fosters cancer cell detachment, migration, and invasion. This bulky glycocalyx also increases membrane tension, promoting integrin clustering and downstream signaling pathways that drive cell proliferation and metastasis. They play a critical role in immune evasion by binding to Siglecs, inhibitory receptors on immune cells, which transmit signals that protect cancer cells from immune-mediated destruction. Targeting sialylation pathways presents a promising therapeutic opportunity to understand the complex roles of sialic acids and sialoglycans in cancer mechanics and progression, which is crucial for developing novel diagnostic and therapeutic strategies that can disrupt these processes and improve cancer treatment outcomes.

ST8SIA6-AS1, a novel lncRNA star in liver cancer

Liver cancer is one of the most lethal gastrointestinal malignancies. Emerging evidence has underscored the pivotal role of long non-coding RNAs (lncRNAs) in tumorigenesis, with ST8SIA6-AS1 identified as a novel oncogenic lncRNA contributing to liver cancer progression. ST8SIA6-AS1 is consistently upregulated in hepatic cancer tissues and is strongly associated with unfavorable prognosis. Moreover, it demonstrates high diagnostic efficacy in detecting HCC. ST8SIA6-AS1 is involved in various cellular processes including proliferation, migration, and invasion, primarily through its function as a competing endogenous RNA (ceRNA), thereby facilitating hepatocarcinogenesis and disease advancement. This review provides a detailed examination of the molecular functions and regulatory mechanisms of ST8SIA6-AS1 in hepatocellular carcinoma (HCC) and highlights its potential as a promising biomarker for liver cancer, aiming to propel the development of innovative therapeutic strategies for HCC management.

Targeting ST8SIA6-AS1 counteracts KRASG12C inhibitor resistance through abolishing the reciprocal activation of PLK1/c-Myc signaling

BACKGROUND

KRASG12C inhibitors (KRASG12Ci) AMG510 and MRTX849 have shown promising efficacy in clinical trials and been approved for the treatment of KRASG12C-mutant cancers. However, the emergence of therapy-related drug resistance limits their long-term potential. This study aimed to identify the critical mediators and develop overcoming strategies.

METHODS

By using RNA sequencing, RT-qPCR and immunoblotting, we identified and validated the upregulation of c-Myc activity and the amplification of the long noncoding RNA ST8SIA6-AS1 in KRASG12Ci-resistant cells. The regulatory axis ST8SIA6-AS1/Polo-like kinase 1 (PLK1)/c-Myc was investigated by bioinformatics, RNA fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and chromatin immunoprecipitation. Gain/loss-of-function assays, cell viability assay, xenograft models, and IHC staining were conducted to evaluate the anti-cancer effects of co-inhibition of ST8SIA6-AS1/PLK1 pathway and KRAS both in vitro and in vivo.

RESULTS

KRASG12Ci sustainably decreased c-Myc levels in responsive cell lines but not in cell lines with intrinsic or acquired resistance to KRASG12Ci. PLK1 activation contributed to this ERK-independent c-Myc stability, which in turn directly induced PLK1 transcription, forming a positive feedback loop and conferring resistance to KRASG12Ci. ST8SIA6-AS1 was found significantly upregulated in resistant cells and facilitated the proliferation of KRASG12C-mutant cancers. ST8SIA6-AS1 bound to Aurora kinase A (Aurora A)/PLK1 and promoted Aurora A-mediated PLK1 phosphorylation. Concurrent targeting of KRAS and ST8SIA6-AS1/PLK1 signaling suppressed both ERK-dependent and -independent c-Myc expression, synergistically led to cell death and tumor regression and overcame KRASG12Ci resistance.

CONCLUSIONS

Our study deciphers that the axis of ST8SIA6-AS1/PLK1/c-Myc confers both intrinsic and acquired resistance to KRASG12Ci and represents a promising therapeutic target for combination strategies with KRASG12Ci in the treatment of KRASG12C-mutant cancers.

LncRNA FENDRR Suppresses Melanoma Growth via Influencing c-Myc mRNA Level

Background

Long non-coding RNAs (lncRNAs) play an important role in the occurrence of melanoma. However, the specific molecular mechanisms that regulate its biological function are still poorly understood. Therefore, the main purpose of this study is to elucidate the internal mechanism of lncRNA-FENDRR as a biological marker for the occurrence of SKCM and its influence on its proliferation.

Results

FENDRR is low expressed in skin cutaneous melanoma (SKCM) tissues and appears to be at an even lower level as the tumor progresses. However, the high expression of FENDRR can affect the proliferation of SKCM cell line A375. The results of flow cytometry showed that after overexpression of FENDRR, the cell cycle was arrested in the G1/G0 phase. Bioinformatics analysis and RIP results showed that FENDRR could be combined with YTHDF1. Together, these complexes regulate c-Myc mRNA level and determine cell proliferation.

Conclusion

We found that overexpression of FENDRR can effectively inhibit SKCM, which provides a new theoretical basis for new therapeutic approaches and targeted RNA drugs.

Long noncoding RNA ST8SIA6-AS1 promotes cell proliferation and metastasis in triple-negative breast cancer by targeting miR-145-5p/CDCA3 to inactivate the p53/p21 signaling pathway

BACKGROUND

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer, always exhibits a poor prognosis due to high risk of early recurrence and distant metastasis. Long noncoding RNAs (lncRNAs) have been reported as crucial regulators in breast cancer. However, the functions and action mechanisms of lncRNA ST8SIA6-AS1 in TNBC are largely unknown.

METHODS

Quantitative real-time PCR and western blot assays were used to measure the expression levels of different genes and proteins. Cell proliferation ability was monitored by CCK-8, colony forming and flow cytometry assays. Wound healing and transwell assays were performed to evaluate cell migration and invasion. The regulatory mechanisms of ST8SIA6-AS1 in TNBC were confirmed by dual luciferase reporter and RIP assays. A mouse xenograft model was established to investigate the role of ST8SIA6-AS1 in TNBC tumor growth.

RESULTS

ST8SIA6-AS1 displayed a higher expression in TNBC cells. Silencing ST8SIA6-AS1 impaired cell proliferation, cell cycle progression, migration, and invasion in vitro, and slowed tumor growth in vivo. Mechanistically, ST8SIA6-AS1 could facilitate the expression of its target CDCA3 (cell division cycle associated protein 3) and inactivate the p53/p21 signaling by inhibiting miR-145-5p. Moreover, miR-145-5p exerted a tumor-suppressive activity by targeting CDCA3. The tumor-suppressive effects induced by ST8SIA6-AS1 knockdown were abated by the down-regulation of miR-145-5p or the up-regulation of CDCA3.

CONCLUSION

ST8SIA6-AS1 exerts an oncogenic role in TNBC by interacting with miR-145-5p to up-regulate CDCA3 expression and inactivate the p53/p21 signaling, highlighting ST8SIA6-AS1 as a promising molecular target to combat TNBC.

Identification of differentially distributed gene expression and distinct sets of cancer-related genes identified by changes in mean and variability

There is increasing evidence that changes in the variability or overall distribution of gene expression are important both in normal biology and in diseases, particularly cancer. Genes whose expression differs in variability or distribution without a difference in mean are ignored by traditional differential expression-based analyses. Using a Bayesian hierarchical model that provides tests for both differential variability and differential distribution for bulk RNA-seq data, we report here an investigation into differential variability and distribution in cancer. Analysis of eight paired tumour-normal datasets from The Cancer Genome Atlas confirms that differential variability and distribution analyses are able to identify cancer-related genes. We further demonstrate that differential variability identifies cancer-related genes that are missed by differential expression analysis, and that differential expression and differential variability identify functionally distinct sets of potentially cancer-related genes. These results suggest that differential variability analysis may provide insights into genetic aspects of cancer that would not be revealed by differential expression, and that differential distribution analysis may allow for more comprehensive identification of cancer-related genes than analyses based on changes in mean or variability alone.

The Distinct Roles of Sialyltransferases in Cancer Biology and Onco-Immunology

Aberrant glycosylation is a key feature of malignant transformation. Hypersialylation, the enhanced expression of sialic acid-terminated glycoconjugates on the cell surface, has been linked to immune evasion and metastatic spread, eventually by interaction with sialoglycan-binding lectins, including Siglecs and selectins. The biosynthesis of tumor-associated sialoglycans involves sialyltransferases, which are differentially expressed in cancer cells. In this review article, we provide an overview of the twenty human sialyltransferases and their roles in cancer biology and immunity. A better understanding of the individual contribution of select sialyltransferases to the tumor sialome may lead to more personalized strategies for the treatment of cancer.

KCNMB2-AS1 Promotes Bladder Cancer Progression Through Sponging miR-374a-3p to Upregulate S100A10

Long non-coding RNAs (lncRNAs) have been reported to play a crucial role in the pathogenesis of numerous cancers. However, the function of lncRNA KCNMB2-AS1 in bladder cancer (BC) remains unclear. In the present study, we aimed to explore the role and underlying mechanisms of KCNMB2-AS1 in bladder cancer progression. We found that lncRNA KCNMB2-AS1 was significantly upregulated both in BC tissues and cell lines, the expression level was highly correlated with pathological TNM stage. Functionally, knockdown of lncRNA KCNMB2-AS1 dramatically inhibited the proliferation, migration, and invasion and of BC cells in vitro, and suppressed tumor growth in vivo. Mechanistically, lncRNA KCNMB2-AS1 could function as a competitive endogenous RNA (ceRNA) through direct sponging miR-374a-3p, which regulated the expression of S100A10. In conclusion, our results demonstrated that lncRNA KCNMB2-AS1 can promote the progression of bladder cancer through regulation of miR-374a-3p/S100A10.

Aberrant Sialylation in Cancer: Biomarker and Potential Target for Therapeutic Intervention?

Simple Summary

Sialylation is a post-translational modification that consists in the addition of sialic acid to growing glycan chains on glycoproteins and glycolipids. Aberrant sialylation is an established hallmark of several types of cancer, including breast, ovarian, pancreatic, prostate, colorectal and lung cancers, melanoma and hepatocellular carcinoma. Hypersialylation can be the effect of increased activity of sialyltransferases and results in an excess of negatively charged sialic acid on the surface of cancer cells. Sialic acid accumulation contributes to tumor progression by several paths, including stimulation of tumor invasion and migration, and enhancing immune evasion and tumor cell survival. In this review we explore the mechanisms by which sialyltransferases promote cancer progression. In addition, we provide insights into the possible use of sialyltransferases as biomarkers for cancer and summarize findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

Abstract

Sialylation is an integral part of cellular function, governing many biological processes including cellular recognition, adhesion, molecular trafficking, signal transduction and endocytosis. Sialylation is controlled by the levels and the activities of sialyltransferases on glycoproteins and lipids. Altered gene expression of these enzymes in cancer yields to cancer-specific alterations of glycoprotein sialylation. Mounting evidence indicate that hypersialylation is closely associated with cancer progression and metastatic spread, and can be of prognostic significance in human cancer. Aberrant sialylation is not only a result of cancer, but also a driver of malignant phenotype, directly impacting key processes such as tumor cell dissociation and invasion, cell-cell and cell-matrix interactions, angiogenesis, resistance to apoptosis, and evasion of immune destruction. In this review we provide insights on the impact of sialylation in tumor progression, and outline the possible application of sialyltransferases as cancer biomarkers. We also summarize the most promising findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

MiR-125a-3p inhibits cell proliferation and inflammation responses in fibroblast-like synovial cells in rheumatoid arthritis by mediating the Wnt/β-catenin and NF-κB pathways via targeting MAST3

OBJECTIVES

To explore the role and mechanism of miR-125a-3p in rheumatoid arthritis (RA) progression.

METHODS

The RA-tissues and fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) were used in this study. qRT-PCR, western blot and ELISA assay were performed to detect the expression levels of IL-6, IL-β and ΤΝF-α. Dual-luciferase reporter gene assay was used to observe the binding effect of miR-125a-3p and MAST3, and CCK-8 was used to observe the effect of miR-125a-3p on the proliferation of RA-FLS.

RESULTS

miR-125a-3p was significantly downregulated in the RA-tissues and RA-FLS, and miR-125a-3p could inhibit the proliferation and reduce the inflammation response of RA-FLS. Besides, MAST3 was found as a target of miR-125a-3p, and increased MAST3 could reverse the effects of miR-125a-3p on RA-FLS including decreased proliferation, reduced inflammation level and the inactivation of Wnt/β-catenin and NF-κB pathways.

CONCLUSIONS

This study suggests that miR-125a-3p could inactivate the Wnt/β-catenin and NF-κB pathways to reduce the proliferation and inflammation response of RA-FLS via targeting MAST3.