Comprehensive analysis of RNA-binding protein SRSF2-dependent alternative splicing signature in malignant proliferation of colorectal carcinoma.

Aberrant expression of serine/arginine-rich splicing factor 2 (SRSF2) can lead to tumorigenesis, but its molecular mechanism in colorectal cancer is currently unknown. Herein, we found SRSF2 to be highly expressed in human colorectal cancer (CRC) samples compared with normal tissues. Both in vitro and in vivo, SRSF2 significantly accelerated the proliferation of colon cancer cells. Using RNA-seq, we screened and identified 33 alternative splicing events regulated by SRSF2. Knockdown of SLMAP-L or CETN3-S splice isoform could suppress the growth of colon cancer cells, predicting their role in malignant proliferation of colon cancer cells. Mechanistically, the in vivo crosslinking immunoprecipitation assay demonstrated the direct binding of the RNA recognition motif of SRSF2 protein to SLMAP and CETN3 pre-mRNAs. SRSF2 activated the inclusion of SLMAP alternative exon 24 by binding to constitutive exon 25, while SRSF2 facilitated the exclusion of CETN3 alternative exon 5 by binding to neighboring exon 6. Knockdown of SRSF2, its splicing targets SLMAP-L, or CETN3-S caused colon cancer cells to arrest in G1 phase of the cell cycle. Rescue of SLMAP-L or CETN3-S splice isoform in SRSF2 knockdown colon cancer cells could effectively reverse the inhibition of cell proliferation by SRSF2 knockdown through mediating cell cycle progression. Importantly, the percentage of SLMAP exon 24 inclusion increased and CETN3 exon 5 inclusion decreased in CRC samples compared to paired normal samples. Collectively, our findings identify that SRSF2 dysregulates colorectal carcinoma proliferation at the molecular level of splicing regulation and reveal potential splicing targets in CRC patients.

Par3 promotes breast cancer invasion and migration through pull tension and protein nanoparticle-induced osmotic pressure.

Cancer cell invasion and metastasis are closely related to intracellular tension. The cell-polarity protein, Par3, is a mechanical transmitter that affects cytoskeletal forces and determines breast cancer aggressiveness. Increased Par3 tension caused by aPKC inactivation is involved in filopodia and lamellipodia formation. Blocking the connection between Par3 and aPKC increases breast cancer aggressiveness both in vitro and in vivo. Meanwhile, aPKC-induced Par3 cytoplasmic translocation results in JAM-A phase separation and microfilament depolymerization, which is associated with increased intracellular protein nanoparticle-induced osmotic pressure. This study demonstrated the effects of aPKC on Par3 tension and osmotic pressure in breast cancer metastasis, and introduced Par3-associated mechanical mechanisms as potential targets for breast cancer treatment.

Identification and validation of an autophagy-related gene signature for predicting prognosis in patients with esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the main subtype of esophageal cancer. Since autophagy-related genes (ARGs) play a key role in the pathogenesis of many tumors, including ESCC, the purpose of this study is to establish an autophagy-related prognostic risk signature based on ARGs expression profile, and to provide a new method for improving prediction of clinical outcomes. We obtained the expression profiles of ESCC from public data (GSE53625) and extracted the portion of ARGs. Differential expression analysis and enrichment analysis were performed to confirm abnormal autophagy-related biological functions. Univariate and multivariate Cox regression analyses were performed on RNA microarray data (GSE53625) to construct a prognostic risk signature associated with autophagy. The performance of the model was evaluated by receiver operating characteristic (ROC) analysis, survival analysis and Brier score. The model was subjected to bootstrap internal validation. The potential molecular mechanism of gene signature was explored by gene set enrichment analysis (GSEA). Spearman correlation coefficient examined the correlation between risk score and immune status and ferroptosis. The expression levels of genes and proteins were validated by qRT-PCR and immunohistochemistry in ESCC cell lines and ESCC tissues. We constructed and validated an autophagy-related prognostic risk signature in 179 patients with ESCC. The long-term survival of patients in high-risk group was lower than that in low-risk group (log-rank, P value < 0.001). ROC analysis and Brier score confirmed the reliability of the signature. GSEA results showed significant enrichment of cancer- and autophagy-related signaling pathways in the high-risk ESCC patients and immunoregulatory signaling pathways in the low-risk ESCC patients. Correlation analysis showed that the risk signature can effectively predict the effect of immunotherapy. About 33.97% (71/209) ferroptosis-related genes were significantly correlated with risk scores. Finally, the results of qRT-PCR and immunohistochemistry experiments were consistent with bioinformatics analysis. In brief, we constructed a novel autophagy-related gene signature (VIM, UFM1, TSC2, SRC, MEFV, CTTN, CFTR and CDKN1A), which could improve the prediction of clinical outcomes in patients with ESCC.

A Novel Autophagy-Related Long Non-Coding RNA Signature to Predict Prognosis and Therapeutic Response in Esophageal Squamous Cell Carcinoma.

BACKGROUND: Considering the significance of autophagy and long non-coding RNAs (lncRNAs) in the biology of esophageal squamous cell carcinoma (ESCC), the present study aimed to identify a new autophagy-related lncRNA signature to forecast the clinical outcomes of ESCC patients and to guide individualized treatment. METHODS: The expression profiles were obtained from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database. We extracted autophagy-related genes from the Human Autophagy Database and identified autophagy-related lncRNAs through Spearman correlation analysis. Univariate, least absolute shrinkage and selection operator and multivariate Cox regression analyses were performed on GSE53625 to construct an autophagy-related lncRNAs prognostic signature. The model was subjected to bootstrap internal validation, and the expression levels of lncRNAs were verified by TCGA database. The potential molecular mechanism of the model was explored by gene set enrichment analysis (GSEA). Spearman correlation coefficient examined the correlation between risk score and ferroptosis-associated genes as well as the response to immunotherapy and chemotherapy. RESULTS: We identified and validated an autophagy-related lncRNAs prognostic signature in 179 patients with ESCC. The prognosis of patients in the low-risk group was significantly better than that in the high-risk group (p-value <0.001). The reliability of the model was verified by Brier score and ROC. GSEA results showed significant enrichment of cancer- and autophagy-related signaling pathways in the high-risk group and metabolism-related pathways in the low-risk group. Correlation analysis indicated that the model can effectively forecast the effect of immunotherapy and chemotherapy. About 35.41% (74/209) ferroptosis-related genes were significantly correlated with risk scores. CONCLUSION: In brief, we constructed a novel autophagy-related lncRNAs signature (LINC02024, LINC01711, LINC01419, LCAL1, FENDRR, ADAMTS9-AS1, AC025244.1, AC015908.6 and AC011997.1), which could improve the prediction of clinical outcomes and guide individualized treatment of ESCC patients.

A Promising Esophageal Cancer Prognostic Signature of Ferroptosis-Related LncRNA to Predict Immune Scenery and Immunotherapy Response.

PURPOSE: Ferroptosis and long non-coding RNA (lncRNA) expression signatures have been associated with the clinical progression and immune-contexture of different solid tumors. The study aimed to identify a prognostic signature of ferroptosis-related lncRNAs (falncRNAs) to forecast the immune scenery and immunotherapy response in esophageal cancer (EC). PATIENTS AND METHODS: Gene expression profiles of EC were extracted from The Cancer Genome Atlas (TCGA) database, and ferroptosis-related genes were downloaded from the FerrDb database, which identified differentially expressed falncRNAs (DEfalncRNAs) via differential analysis. DEfalncRNA pairs associated with prognosis were identified by constructing a matrix, univariate and least absolute shrinkage and selection operator (LASSO) analysis. The prognostic signature was constructed by multivariate analysis. We appraised the forecasting capability of prognostic signature in survival, clinicopathological features, immune landscape, efficacy of immunotherapy, and drug sensitivity. The potential molecular mechanism of signature was investigated by gene set enrichment analysis (GSEA). RESULTS: We obtained 18 DEfalncRNA pairs to define a novel prognostic signature that was determined on a discovery cohort of 158 tumor samples and 11 adjacent normal tissues from TCGA and internally validated, with the definition of high- vs low-risk groups based on 3 years overall survival. We demonstrated that the high- vs low-risk groups differed for clinical parameters and computationally predicted drug sensitivity and tumor immune contexture, with the high-risk group having worse survival, more aggressive disease (node involvement, metastasis), reduced drug sensitivity, higher tumor mutation load, and gene signatures of infiltration of pro-tumoral immune cell subsets. The GSEA results revealed that ferroptosis and immunoregulatory pathways were significantly enriched in the high-risk group. CONCLUSION: The prognostic signature based on falncRNAs has the potential to forecast the survival, immune scenery, efficacy of immunotherapy, and drug sensitivity of EC, which is helpful for clinical prediction and individualized treatment.

Construction and verification of prognostic nomogram for early-onset esophageal cancer.

This study aimed to build up nomogram models to evaluate overall survival (OS) and cancer-specific survival (CSS) in early-onset esophageal cancer (EOEC). Patients diagnosed with esophageal cancer (EC) from 2004 to 2015 were extracted from the Surveillance Epidemiology and End Results (SEER) database. Clinicopathological characteristics of younger versus older patients were compared, and survival analysis was performed in both groups. Independent related factors influencing the prognosis of EOEC were identified by univariate and multivariate Cox analysis, which were incorporated to construct a nomogram. The predictive capability of the nomogram was estimated by the concordance index (C-index), calibration plot, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA). A total of 534 younger and 17,243 older patients were available from the SEER database. Younger patients were randomly segmented into a training set (n = 266) and a validation set (n = 268). In terms of the training set, the C-index of the OS nomogram was 0.740 (95% CI: 0.707-0.773), and that of the CSS nomogram was 0.752 (95% CI: 0.719-0.785). In view of the validation set, the C-index of OS and CSS were 0.706 (95% CI: 0.671-0.741) and 0.723 (95% CI: 0.690-0.756), respectively. Calibration curves demonstrated the consistent degree of fit between actual and predicted values in nomogram models. From the perspective of DCA, the nomogram models were more beneficial than the tumor-node-metastasis (TNM) and the SEER stage for EOEC. In brief, the nomogram model can be considered as an individualized quantitative tool to predict the prognosis of EOEC patients to assist clinicians in making treatment decisions.

Ligustrazine alleviates cyclophosphamide-induced hepatotoxicity via the inhibition of Txnip/Trx/NF-κB pathway.

AIMS: Cyclophosphamide (CP) is a common therapeutic drug for cancer, but exposure to CP can cause acute hepatotoxicity. This study aimed to elucidate the protective effects of Ligustrazine (2, 3, 5, 6-tetramethylpyrazine, TMP) on hepatotoxicity induced by CP or its active metabolite 4-hydroperoxycyclophosphamide (4-HC). MAIN METHODS: We presented a comprehensive investigation about the hepatoprotection of TMP on CP-induced mice and 4-HC-treated HSC-LX2 cells. Liver function was detected via enzyme-linked immunosorbent assay (ELISA). Hepatic histopathology analysis was performed via hematoxylin and eosin (H&E) and Masson staining. Survival of hepatocytes was detected by TUNEL assay. Related proteins in the thioredoxin (Trx)-interacting protein (Txnip)/Trx/Nuclear factor-kappa B (NF-κB) pathway were measured by western blotting. KEY FINDINGS: The results indicated that CP or 4-HC could increase the levels of alanine aminotransferase and aspartate aminotransferase, enhance inflammatory factors and oxidative indicators, and suppress the activity of oxidoreductases. Moreover, significant changes in liver histological structure, fibrosis, and cell death were observed through the activation of Txnip/Trx/NF-κB pathway. In contrast, administration of TMP significantly reversed these above changes. Furthermore, TMP intervention participated in the inhibition of NLRP3 inflammasome accompanied with pyroptosis, as well as upregulating Trx expression and downregulating p-NF-κB, while the protective effect of TMP was limited to the involvement of Txnip overexpression. SIGNIFICANCE: TMP treatment could significantly alleviate the hepatotoxicity process as evidenced by improving the structure and function of the liver, inhibiting oxidative stress and inflammation accompanied with pyroptosis, which was positively correlated with the inhibition of Txnip/Trx/NF-κB pathway.

Baicalein inhibits non-small-cell lung cancer invasion and metastasis by reducing ezrin tension in inflammation microenvironment.

Baicalein, a flavonoid phytochemical, has been shown to be effective as an anti-metastatic agent for various cancers, especially for non-small-cell lung cancer (NSCLC). However, the underlying mechanism of how baicalein targets cellular processes during NSCLC cell invasion and metastasis remains elusive. In this study, we found that non-cytotoxic concentrations of baicalein still retained anti-dissemination activity both in vitro and in vivo. Using a genetic encoding tension probe based on Förster resonance energy transfer (FRET) theory, baicalein was shown to significantly decrease ezrin tension by downregulating cellular ezrin S-nitrosylation (SNO) levels in NSCLC cells in the inflammatory microenvironment. Decreased ezrin tension inhibited the formation of an aggressive phenotype of NSCLC cell and leader cell in collective migration, and subsequently suppressed NSCLC dissemination. Baicalein restrained SNO-mediated ezrin tension by decreasing iNOS expression levels. Overall this study demonstrates the novel mechanism used by baicalein to suppress NSCLC invasion and metastasis from a mechanopharmacology perspective and illustrates a new direction for drug development.

Regulation of ezrin tension by S-nitrosylation mediates non-small cell lung cancer invasion and metastasis.

Cancer invasion and metastasis depend on accurate and rapid modulation of both chemical and mechanical activities. The S-nitrosylation (SNO) of membrane cytoskeletal cross-linker protein ezrin may regulate the malignant process in a tension-dependent manner. Methods: The level of nitrosylated ezrin in non-small cell lung cancer (NSCLC) tissues and A549 cell line were evaluated by biotin-switch assay. A few cysteine mutated plasmids of ezrin were used to identify active site for SNO. Newly designed ezrin or mutated-ezrin tension probes based on Förster resonance energy transfer (FRET) theory were applied to visually observe real-time tension changes. Cytoskeleton depolymerizing and motor molecular inhibiting experiments were performed to reveal the alternation of the mechanical property of ezrin after SNO. Transwell assays and xenograft mouse model were used to assess aggressiveness of A549 cells in different groups. Fluorescent staining was also applied to examine cellular location and structures. Results: High inducible nitric oxide synthase (iNOS) levels were observed to induce ezrin-SNO, and then promote malignant behaviors of NSCLC cells both in vitro and in vivo. Cys117 was identified as the only active site for ezrin-SNO. Meanwhile, an increased level of ezrin tension was observed after iNOS-induced SNO. Enhanced ezrin tension was positively correlated with aggressiveness of NSCLC. Moreover, Microfilament (MF) forces instead of microtubule (MT) forces played dominant roles in modulating ezrin tension, especially after ezrin nitrosylation. Conclusion: This study revealed a SNO-associated mechanism underlying the mechanical tension of ezrin. Ezrin-SNO promotes NSCLC cells invasion and metastasis through facilitating mechanical transduction from the cytoskeleton to the membrane. These studies implicate the therapeutic potential by targeting ezrin in the inhibition NSCLC invasion and metastasis.