Methylation-mediated loss of SFRP2 enhances invasiveness of non-small cell lung cancer cells

Concentration of Secreted Frizzled-Related Proteins (SFRPs) in Non-Small Cell Lung Carcinoma Subtypes-A Preliminary Study

Non-small cell lung carcinoma (NSCLC) is the most common lung cancer worldwide. Secreted frizzled-related proteins (SFRPs) are important tumour suppressors and antagonists of the Wnt signalling pathway, which is linked with cancer development. The aim of this study was to evaluate the concentrations of SFRP1, SFRP2, and SFRP5 proteins in tumour and non-tumour (NT) samples obtained from 65 patients with primary NSCLC. An enzyme-linked immunosorbent assay (ELISA) was used to measure the concentrations of SFRPs in the tissue homogenates. A significantly lower SFRP2 protein concentration was found in the total NSCLC tumour samples and the following NSCLC subtypes: squamous cell carcinoma (SCC) and adenocarcinoma (AC) (p > 0.05, p = 0.028 and p = 0.001, respectively). AC tumour samples had a higher SFRP1 level than NT samples (p = 0.022), while the highest SFRP1 concentration was found in NSCLC samples from patients with clinical stage T4 cancer. Increased concentrations of SFRP1 and SFRP5 were present in stage III NSCLC samples, while the tumour samples with high pleural invasion (PL2) had an increased level of SFRP2. The results from this study suggest that the tumour suppressor or oncogenic roles of SFRPs could be connected with the NSCLC subtype. The levels of SFRPs varied according to the clinicopathological parameters of NSCLC.

Secreted frizzled-related proteins: A promising therapeutic target for cancer therapy through Wnt signaling inhibition

The Wnt signaling system is a critical pathway that regulates embryonic development and adult homeostasis. Secreted frizzled-related proteins (SFRPs) are extracellular inhibitors of Wnt signaling that act by binding directly to Wnt ligands or Frizzled receptors. SFRPs can act as anti-Wnt agents and suppress cancer growth by blocking the action of Wnt ligands. However, SFRPs are often silenced by promoter methylation in cancer cells, resulting in hyperactivation of the Wnt pathway. Epigenetic modifiers can reverse this silencing and restore SFRPs expression. Despite the potential of SFRPs as a therapeutic target, the effects of SFRPs on tumor development remain unclear. Therefore, a review of the expression of various members of the SFRPs family in different cancers and their potential as therapeutic targets is warranted. This review aims to summarize the current knowledge of SFRPs in cancer, focusing on their expression patterns and their potential as novel therapeutic targets.

METTL3 promotes the malignancy of non-small cell lung cancer by N6-methyladenosine modifying SFRP2

This study aimed to investigate the roles of METTL3, a regulator of m6A, in NSCLC. RT-qPCR was applied to determine mRNA of m6A-associated genes and SFRP2, and western blot were used for ZEB1 and MMP9 protein expression. Total m6A level was measured using methylated RNA immunoprecipitation (MeRIP) assay, and RIP was used to access m6A level of SFRP2. Cellular behaviors were detected using CCK-8 and tranwell assays. Xenograft assays were conducted to further verify the roles of METTL3 and SFRP2 in NSCLC. The expression level of METTL3 was higher in NSCLC than normal controls. However, downregulation of METTL3 restrained the proliferation, migration and invasion of NSCLC cells. Enhanced expression of METTL3 caused the inverse consequences. Moreover, SFRP2 was found to be negatively regulated by METTL3. Intriguingly, the anti-tumor functions of METTL3 knockdown in the phenotype of NSCLC cells and xenograft mice were overturned by inhibition of SFRP2. Silencing METTL3 resulted in the enhanced stability of SFRP2. Finally, downregulation of SFRP2 induced by METTL3 activated the Wnt/β-catenin signaling pathway in NSCLC. METTL3 acted as an oncogene in the pathogenesis of NSCLC via suppressing SFRP2 to activate Wnt/β-catenin signaling pathway, indicating that METTL3 might be a promising predictor in NSCLC.

A Systematic Review of Progress toward Unlocking the Power of Epigenetics in NSCLC: Latest Updates and Perspectives

Epigenetic research has the potential to improve our understanding of the pathogenesis of cancer, specifically non-small-cell lung cancer, and support our efforts to personalize the management of the disease. Epigenetic alterations are expected to have relevance for early detection, diagnosis, outcome prediction, and tumor response to therapy. Additionally, epi-drugs as therapeutic modalities may lead to the recovery of genes delaying tumor growth, thus increasing survival rates, and may be effective against tumors without druggable mutations. Epigenetic changes involve DNA methylation, histone modifications, and the activity of non-coding RNAs, causing gene expression changes and their mutual interactions. This systematic review, based on 110 studies, gives a comprehensive overview of new perspectives on diagnostic (28 studies) and prognostic (25 studies) epigenetic biomarkers, as well as epigenetic treatment options (57 studies) for non-small-cell lung cancer. This paper outlines the crosstalk between epigenetic and genetic factors as well as elucidates clinical contexts including epigenetic treatments, such as dietary supplements and food additives, which serve as anti-carcinogenic compounds and regulators of cellular epigenetics and which are used to reduce toxicity. Furthermore, a future-oriented exploration of epigenetic studies in NSCLC is presented. The findings suggest that additional studies are necessary to comprehend the mechanisms of epigenetic changes and investigate biomarkers, response rates, and tailored combinations of treatments. In the future, epigenetics could have the potential to become an integral part of diagnostics, prognostics, and personalized treatment in NSCLC.

SFRP2 is a Novel Diagnostic Biomarker and Suppresses the Proliferation of Pituitary Adenoma

Pituitary adenoma (PA) constitutes one of the most common intracranial tumors. The present study was designed to identify potential diagnostic markers for PA. We used gene expression profiles (GEO: GSE26966 and GEO: GSE63357 datasets) derived from human PA and nontumor samples that were made freely accessible by the gene expression omnibus (GEO) datasets. Differentially expressed genes (DEGs) were screened between 14 normal specimens and 34 PA specimens by the use of the limma package of the R. The diagnostic genes were determined using a LASSO regression model and SVM-RFE analysis. SFRP2 expression in PA cells was analyzed using RT-PCR, and the effect of SFRP2 dysregulation on PA cell proliferation was measured using CCK-8 analysis. In this study, 361 DEGs were identified: 309 genes were downregulated and 52 genes were upregulated. The results of KEGG assays revealed that the 361 DEGs were mainly enriched in the PI3K-Akt signaling pathway, MAPK signaling pathway, growth hormone synthesis, secretion and action, and AGE-RAGE signaling pathway in diabetic complications. Results from the LASSO regression model and the SVM-RFE analysis indicated that LOC101060391 and SFRP2 were diagnostic genes. In contrast to normal tissue, the expressions of LOC101060391 and SFRP2 were much lower in PA samples. According to the ROC assays, high LOC101060391 and SFRP2 expression had an AUC value >0.9 for PA. Upregulation of SFRP2 distinctly inhibited the proliferative capacity of PA cells, as shown by CCK-8 analysis. Furthermore, knockdown of SFRP2 had an influence on cell growth in both the AtT-20 and HP75 cell lines. Taken together, our findings indicate that LOC101060391 and SFRP2 have diagnostic potential for PA. Furthermore, SFRP2 may be an antioncogene and a therapeutic target for PA.

Location, function and role of stromal cell‑derived factors and possible implications in cancer (Review)

Despite improvements in therapy and management, cancer represents and remains a major cause of mortality and morbidity worldwide. Although genetics serve an important role in tumorigenesis and tumour progression, the tumour microenvironment (TME) in solid tumours is also important and has been indicated to contribute to these processes. Stromal cell‑derived factors (SDFs) represent an important family within the TME. The family includes SDF‑1, SDF‑2, SDF2‑like 1 (SDF2L1), SDF‑3, SDF‑4 and SDF‑5. SDF‑1 has been demonstrated to act as a positive regulator in a number of types of tumour, such as oesophago‑gastric, pancreatic, lung, breast, colorectal and ovarian cancer, while the biology and functions of other members of the SDF family, including SDF‑2, SDF2L1, SDF‑4 and SDF‑5, in cancer are different, complex and controversial, and remain mainly unknown. Full identification and understanding of the SDFs across multiple types of cancer is required to elucidate their function and establish potential key targets in cancer.

MicroRNA-522-3p plays an oncogenic role in glioblastoma through activating Wnt/β-catenin signaling pathway via targeting SFRP2

BACKGROUND

Increasing studies have suggested that microRNAs (miRNAs) contribute to the occurrence and development of glioblastoma. MiR-522-3p is a novel miRNA, which has been found to modulate tumorigenesis and tumor progression. However, its pathological role and functional mechanism in glioblastoma remain elusive at present.

METHOD

The miR-522-3p expression in glioblastoma and adjacent normal tissues, human fetal astrocyte HA1800, and glioblastoma cell lines was detected by reverse transcription-PCR. The proliferation, migration, and invasion were detected through Cell Counting Kit-8 (CCK8) and Transwell assay, and apoptosis was calculated through flow cytometry. The downstream target of miR-522-3p was analyzed through bioinformatics, and the correlation between miR-522-3p and secreted frizzled-related protein 2 (SFRP2) was verified through dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment. Besides, western blot was conducted to test the level of SFRP2 and the Wnt/β-catenin pathway.

RESULTS

MiR-522-3p was overexpressed in glioblastoma tissues compared with that in normal tissues, and the inhibition of miR-522-3p reduced cell proliferation, migration, and invasion and promoted apoptosis in glioblastoma. Bioinformatics revealed that SFRP2 was an essential downstream target of miR-522-3p, and it inhibited the malignant biological behaviors induced by miR-522-3p and inactivated the Wnt/β-catenin pathway.

CONCLUSION

MiR-522-3p is an oncogene in glioblastoma by targeting SFRP2 through the Wnt/β-catenin pathway.

ROS‑mediated hypomethylation of PRDX5 promotes STAT3 binding and activates the Nrf2 signaling pathway in NSCLC

Deoxyribonucleic acid (DNA) epigenetic modification has been linked to specific sequences of CpG islands and plays roles in the progression of lung cancer. In this study, it was found that peroxiredoxin‑5 (PRDX5) was highly expressed in non‑small cell lung cancer (NSCLC) tissues; however, its specific regulatory mechanisms and functions in NSCLC remain unknown. The present study therefore explored the regulatory mechanism of PRDX5 under conditions of oxidative stress (OS) in NSCLC. The results revealed that 79 of 121 NSCLC patients exhibited demethylation in the PRDX5 promoter region, which was related to the tumor, node and metastasis (TNM) stage (P=0.027). PRDX5 messenger ribonucleic acid (mRNA) expression positively correlated with the demethylation status of the promoter region. The results of bisulfite sequencing polymerase chain reaction (BSP) revealed lower demethylation frequencies in H1299 cells treated with 0 µM H2O2, but maximum demethylation following treatment with 100 µM H2O2. Using chromatin immunoprecipitation (ChIP) and luciferase detection assays, the effective binding of STAT3 to the transcriptional binding sites of the PRDX5 promoter region was confirmed (2 sites confirmed: Site 1, ‑444 to ‑434 bp; and site 4, ‑1,417 to ‑1,407 bp). STAT3 knockdown significantly decreased the protein expression of PRDX5, while the overexpression of STAT3 significantly increased the protein levels of PRDX5. When PRDX5 was overexpressed in lung cancer cells under conditions of OS, the levels of the epithelial‑mesenchymal transition (EMT) biomarkers, E‑cadherin and vimentin, were significantly decreased and increased, respectively. By contrast, PRDX5 knockdown resulted in significantly increased E‑cadherin and decreased vimentin protein expression levels. Ultimately, when PRDX5‑small interfering RNA (siRNA) or pcDNA3.1‑PRDX5 expression vector were constructed and transfected into H1299 cells pre‑treated with 100 µM H2O2, the nuclear factor (erythroid‑derived 2)‑like 2 (Nrf2) signaling pathway was inhibited or activated. All these results suggested that the reactive oxygen species (ROS)‑mediated hypomethylation of PRDX5 enhanced STAT3 binding affinity with the promoter region, and resulted in the promotion of cell migration and invasion, as well as in the activation of the Nrf2 signaling pathway in NSCLC. The demethylation status of the PRDX5 promoter may thus be used as an epigenetic biomarker in NSCLC. STAT3/PRDX5 signaling may also prove to be a potential strategy for the treatment of this type of cancer.

SFRP2 modulates non‑small cell lung cancer A549 cell apoptosis and metastasis by regulating mitochondrial fission via Wnt pathways

The secreted frizzled‑related protein 2 (SFRP2) has been reported to inhibit non‑small cell lung cancer (NSCLC) cell survival and metastasis; however, the underlying mechanisms are yet to be fully determined. The present study focused on mitochondrial fission and the Wnt signaling pathway. The results demonstrated that SFRP2 was downregulated in the NSCLC cell line A549 compared with in a normal pulmonary epithelial cell line using western blotting, reverse transcription‑quantitative PCR and immunofluorescence. Subsequently, it was demonstrated that SFRP2 overexpression promoted the apoptosis, and inhibited the proliferation and metastasis of A549 cells using MTT assays, TUNEL staining and 5‑ethynyl‑2'‑deoxyuridine labeling. At the molecular level, the overexpression of SFRP2 in A549 cells led to the activation of mitochondrial fission by inhibiting the Wnt signal pathway. Excessive mitochondrial fission induced low ATP generation, impaired mitochondrial respiratory function, induced mitochondrial potential depolarization, and increased mitochondrial permeability transition pore opening, and imbalances in pro‑ and antiapoptotic protein expression. Furthermore, mitochondrial fission was involved in the inhibition of A549 cell proliferation and metastasis. Thus, SFRP2 may inhibit the survival and metastasis of NSCLC cells via the Wnt/mitochondrial fission pathway.