Study of apoptosis-related interactions in colorectal cancer

LncRNA FGF7-5 and lncRNA GLRX3 together inhibits the formation of carotid plaque via regulating the miR-2681-5p/ERCC4 axis in atherosclerosis

Atherosclerotic plaques belong to the common vascular disease in the aged, which rupture will lead to acute thromboembolic diseases, the leading cause of fatal cardiovascular events. Accumulating evidence indicates that the lncRNAs-miRNAs-mRNA regulatory network plays a critical role in atherosclerosis. Based on RNA sequencing (GSE207252), we constructed expression profiles of lncRNAs, microRNAs, and mRNA in the carotid plaque of atherosclerosis patients and analyzed differentially expressed genes (DEGs). We identified three candidate lncRNAs using two algorithms (LASSO and SVM-RFE): lnc_GLRX3, lnc_FGF7-5, and DISC1FP1). LNCipedia, TargetScan, and miRDB databases were used to predict target miRNAs of lncRNAs and target genes of miRNAs. Gene ontology (GO) functional annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and Gene Set Enrichment Analysis (GSEA) analysis of DEGs was carried out using the R package clusterProfiler. A PPI network was constructed using the STRING website and visualized by Cytoscape. According to the "MCC" method of the plug-in cytoHubba in Cytoscape, ERCC4 was the top hub gene of the PPI network. We constructed a lncRNA_FGF7-5/lncRNA_GLRX3-miR-2681-5p-ERCC4 regulatory network for carotid plaque using lncRNA-miRNA and miRNA-mRNA pairs. Next, lncRNA_FGF7-5 and lncRNA_GLRX3 targeted miR-2681-5p directly to upregulate ERCC4 expression. Silencing of lncRNA_FGF7-5 and lncRNA_GLRX3 promoted apoptosis and TP53 expression in HUVECs treated with ox-LDL; however, these effects were reversed by ERCC4-overexpression. Taken together, these findings indicated that lncRNA_FGF7-5 and lncRNA_GLRX3 together reduced atherosclerosis-induced apoptosis of HUVECs via targeting miR-2681-5p to increase ERCC4 expression, thereby preventing the formation of carotid plaque and finally inhibiting atherosclerosis progression.

Effects of Huaier Extract on Ameliorating Colitis-Associated Colorectal Tumorigenesis in Mice

Background

Huaier extract has been a part of traditional Chinese medicine (TCM) for roughly 1600 years and may serve as a potential anti-cancer drug as it is associated with good efficacy and low toxicity. Individuals with inflammatory bowel disease (IBD) are at a higher chance of being diagnosed with colorectal cancer (CRC) and as Huaier extract may potentially influence tumorigenesis, we set out to determine the effect of Huaier extract on colitis-associated CRC.

Methods

The CRC mouse model, established through azoxymethane (AOM) and dextran sulfate sodium (DSS), was administered Huaier extract. Weight loss, colon length, tumor number and tumor size were evaluated macroscopically. Pro-inflammatory cytokine expression and STAT3 phosphorylation were assessed in the colon using ELISA, Western blot and/or immunohistochemistry.

Results

Huaier extract improved the severity of colitis-associated tumorigenesis compared with control group, with attenuated weight loss and longer colons. Tumor number, size and load were drastically decreased in mice treated with Huaier. Histological assessment suggested that Huaier could decrease histological injury of the colon tissue. Additionally, Huaier extract treatment led to reduced pro-inflammatory cytokine levels (TNF-α, IL-6, IFN-γ and IL-1β) and a decrease of STAT3 phosphorylation in colon tissue. Additionally, present findings demonstrated that Huaier extract inhibited cell proliferation and induced apoptosis in CRC cells HCT116 and HCT8. The migration and invasion of CRC cells were markedly inhibited upon exposure to Huaier treatment. The apoptosis-associated protein levels (P53, Bax, Bcl-2, pro-caspase-3 and cleavage caspase-3) showed significant differences after the administration of Huaier extract in HCT116 and HCT8 cells. In vivo, the administration of Huaier extract to mice inhibited tumor growth and yielded a similar profile of apoptotic proteins expression p53, Bcl-2, pro-caspase-3 and cleaved caspase-3 while no significant differences in Bax were observed. Moreover, the ratio of TUNEL-positive/apoptotic cells was markedly increased in the Huaier-treated mice.

Conclusion

Huaier extract may reduce the IBD-associated tumor development by suppressing pro-inflammatory cytokine levels and STAT3 stimulation.

lncRNA DSCAM-AS1 downregulates miR-216b to promote the migration and invasion of colorectal adenocarcinoma cells

Background

It has been reported that lncRNA DSCAM-AS1 plays an oncogenic role in breast cancer. In the present study we explored the role of DSCAM-AS1 in colorectal adenocarcinoma (CRA).

Methods: Gene expression was analyzed by qPCR and Western blot. Overexpression experiments were performed to analyze gene interactions. Transwell assays were performed to analyze cell invasion and migration. Methylation-specific PCR (MSP) was performed to analyze DNA methylation.

Results

It was observed that DSCAM-AS1 was upregulated in the primary tumor tissues than in paired non-tumor tissues (within 2 cm around tumors) and was further increased with tumor metastasis. miR-216b was downregulated in primary tumor and further downregulated with tumor metastasis. miR-216b was inversely correlated with DSCAM-AS1 in tumor tissues, but not in non-tumor tissues. In cells of CRA cell lines, DSCAM-AS1 overexpression resulted in the downregulation of miR-216b, while miR-216b overexpression did not significantly affect DSCAM-AS1. DSCAM-AS1 overexpression did not significantly affect cancer cell proliferation but promoted cell migration and invasion. miR-216b inhibited cancer cell migration and invasion and significantly reduced the effects of DSCAM-AS1 overexpression. Methylation-specific PCR showed that DSCAM-AS1 overexpression promoted the methylation of miR-216b gene.

Conclusion

DSCAM-AS1 may downregulate miR-216b to promote the migration and invasion of CRA cells.

Critical Roles of microRNAs in the Pathogenesis of Fatty Liver: New Advances, Challenges, and Potential Directions

In this review, we summarize the current understanding of microRNA (miRNA)-mediated modulation of the gene expression in the fatty liver as well as related signaling pathways. Because of the breadth and diversity of miRNAs, miRNAs may have a very wide variety of biological functions, and much evidence has confirmed that miRNAs are involved in the pathogenesis of fatty liver. In the pathophysiological mechanism of fatty liver, miRNAs may be regulated by upstream regulators, and have their own regulatory targets. miRNAs display important roles in the pathological mechanisms of alcoholic liver disease and non-alcoholic fatty liver disease. At present, most of the miRNA studies are focused on cell and tissue levels, and in vivo studies will help us elucidate the regulation of miRNAs and help us evaluate the potential of miRNAs as diagnostic markers and therapeutic targets. Furthermore, there is evidence that miRNAs are involved in the mechanism of natural medicine treatment in fatty liver. Given the important roles of miRNAs in the pathogenesis of fatty liver, we predict that studies of miRNAs in the pathogenesis of fatty liver will contribute to the elucidation of fatty liver pathology and the treatment of fatty liver patients.

Mitotic and apoptotic activity in colorectal neoplasia

Background

Colorectal cancer (CRC) is third most commonly diagnosed cancer worldwide. The aim of the prospective study was to evaluate mitosis and apoptosis of epithelial cells at each stage of colorectal neoplasia.

Methods

A total of 61 persons were enrolled into the study: 18 patients with non-advanced colorectal adenoma (non-a-A), 13 patients with advanced colorectal adenoma (a-A), 13 patients with CRC and 17 controls: individuals with normal findings on colonoscopy. Biopsy samples were taken from pathology (patients) and healthy mucosa (patients and healthy controls). Samples were formalin-fixed paraffin-embedded and stained with haematoxylin-eosin. Mitotic and apoptotic activity were evaluated in lower and upper part of the crypts and in the superficial compartment. Apoptotic activity was also assessed using detection of activated caspase-3.

Results

In controls, mitotic activity was present in lower part of crypts, accompanied with low apoptotic activity. Mitotic and apoptotic activity decreased (to almost zero) in upper part of crypts. In superficial compartment, increase in apoptotic activity was observed. Transformation of healthy mucosa into non-a-A was associated with significant increase of mitotic activity in lower and upper part of the crypts and with significant increase of apoptotic activity in all three compartments; p < 0.05. Transformation of non-a-A into a-A did not lead to any further significant increase in apoptotic activity, but was related to significant increase in mitotic activity in upper part of crypts and superficial compartment. A significant decrease in apoptotic activity was detected in all three comparments of CRC samples compared to a-A; p < 0.05. No differences in mitotic and apoptotic activity between biopsies in healthy controls and biopsy samples from healthy mucosa in patients with colorectal neoplasia were observed. Detection of activated caspase-3 confirmed the above findings in apoptotic activity.

Conclusions

Significant dysregulation of mitosis and apoptosis during the progression of colorectal neoplasia, corresponding with histology, was confirmed. In patients with sporadic colorectal neoplasia, healthy mucosa does not display different mitotic and apoptotic activity compared to mucosa in healthy controls and therefore adequate endoscopic/surgical removal of colorectal neoplasia is sufficient.

RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer

Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. The present study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6‐knockdown cells. Transfection with RBBP6 shRNA improved the levels of G2‐M phase arrest, which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, the tumor growth rate of nude mice in the RBBP6‐knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.

Silencing Lin28 promotes apoptosis in colorectal cancer cells by upregulating let‑7c targeting of antiapoptotic BCL2L1

Colorectal cancer (CRC) remains a primary contributor to cancer-associated mortality. The Lin28/let-7 axis has previously been verified to participate in numerous pathophysiological processes involved in CRC. However, the potential roles and underlying mechanisms of this axis in apoptosis during CRC remain to be fully elucidated. The present study aimed to evaluate the role and reveal the molecular mechanisms of the Lin28/let-7 axis in the apoptosis of CRC cells. An MTT assay was conducted to assess the cell viability of HCT116 and HT29 CRC cells, and caspase-3 activity was analyzed to measure the apoptosis of CRC cells. Western blotting and reverse transcription-quantitative polymerase chain reaction were performed to examine the expression of Lin28, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein, Bcl-2-like 1 (BCL2L1) and let-7c. The present study demonstrated that Lin28 was upregulated whereas let-7c was downregulated in CRC tissues and cell lines compared with normal tissues and NCM460 normal colon epithelial cells, respectively. Forced overexpression of let-7c promoted apoptosis in CRC cells, which was at least partially mediated via the targeting of BCL2L1. Furthermore, knockdown of Lin28 decreased viability and promoted apoptosis in CRC cells, whereas this effect was attenuated by let-7c inhibition. The findings of the present study suggest the involvement of the Lin28/let-7c axis in apoptosis during CRC, and indicate the potential role of this pathway as a novel therapeutic target in CRC.

Current and future biomarkers in colorectal cancer

Colorectal cancer (CRC), one of the leading causes of death among cancer patients, is a heterogeneous disease and is characterized by diversions in multiple molecular pathways throughout its evolutionary process. To date, specific mutations in RAS and RAF genes are tested in everyday clinical practice along with mismatch repair gene deficiency, serving either as prognostic or predictive biomarkers, providing information for patient risk stratification and the choice of appropriate therapy. However, ongoing studies are focusing on the potential role of recently discovered genetic and epigenetic alterations in the management of CRC patients and their potential prognostic or predictive value. To overcome the problem of tumor heterogeneity as well as the practical obstacles of access to tumor tissue, and to achieve real-time monitoring of disease and therapy efficacy, liquid biopsies constitute a novel technology worth exploring. CRC screening and management is entering a new era where molecular testing will be applied to genomic material extracted from easily accessible bodily fluids.

Identification of a RNA-Seq based prognostic signature with five lncRNAs for lung squamous cell carcinoma

Long non-coding RNAs (lncRNAs) expression profile signature for survival assessment in lung squamous cell carcinoma (LUSC) are largely inconsistent due to distinct detecting approaches and small sample size. Systematic and integrative investigation of RNA-Seq based data from The Cancer Genome Atlas (TCGA) herein was performed to determine candidate lncRNAs for prognosis evaluation of LUSC. A total of 60483 genes, including 7589 lncRNAs were assessed in a cohort including 478 LUSC cases with follow-up data. Firstly, 4225 differentially expressed lncRNAs were obtained via R packages. Next, univariate and multivariate Cox proportional hazards regression revealed that 41 lncRNAs were closely related to the survival of LUSC. Finally, lncRNA based prognosis index (PI) could predict overall survival of LUSC with high accuracy (AUC = 0.652, CI: 0.598, 0.705), PI = expCYP4F26P*βCYP4F26P+expRP11-108M12.3*βRP11-108M12.3+expRP11-38M8.1*βRP11-38M8.1+expRP11-54H7.4*βRP11-54H7.4+expZNF503-AS1*βZNF503-AS1. Furthermore, it was confirmed that the five-lncRNA signature could act as an independent prognostic indicator for LUSC (HR = 2.068, p < 0.001 with univariate analysis, HR = 1.928, p = 0.038 with multivariate). Besides, we constructed a weighted gene co-expression network analysis (WGCNA) of key lncRNA RP11-54H7.4 according to the p-value of related genes' weight. This study provides a RNA-Seq based prognostic signature with five lncRNAs for further clinical application to LUSC patients.

Novel miRNA-mRNA interactions conserved in essential cancer pathways

Cancer is a complex disease in which unrestrained cell proliferation results in tumour development. Extensive research into the molecular mechanisms underlying tumorigenesis has led to the characterization of oncogenes and tumour suppressors that are key elements in cancer growth and progression, as well as that of other important elements like microRNAs. These genes and miRNAs appear to be constitutively deregulated in cancer. To identify signatures of miRNA-mRNA interactions potentially conserved in essential cancer pathways, we have conducted an integrative analysis of transcriptomic data, also taking into account methylation and copy number alterations. We analysed 18,605 raw transcriptome samples from The Cancer Genome Atlas covering 15 of the most common types of human tumours. From this global transcriptome study, we recovered known cancer-associated miRNA-targets and importantly, we identified new potential targets from miRNA families, also analysing the phenotypic outcomes of these genes/mRNAs in terms of survival. Further analyses could lead to novel approaches in cancer therapy.

Comprehensive investigation of a novel differentially expressed lncRNA expression profile signature to assess the survival of patients with colorectal adenocarcinoma

Growing evidence has shown that long non-coding RNAs (lncRNAs) can serve as prospective markers for survival in patients with colorectal adenocarcinoma. However, most studies have explored a limited number of lncRNAs in a small number of cases. The objective of this study is to identify a panel of lncRNA signature that could evaluate the prognosis in colorectal adenocarcinoma based on the data from The Cancer Genome Atlas (TCGA). Altogether, 371 colon adenocarcinoma (COAD) patients with complete clinical data were included in our study as the test cohort. A total of 578 differentially expressed lncRNAs (DELs) were observed, among which 20 lncRNAs closely related to overall survival (OS) in COAD patients were identified using a Cox proportional regression model. A risk score formula was developed to assess the prognostic value of the lncRNA signature in COAD with four lncRNAs (LINC01555, RP11-610P16.1, RP11-108K3.1 and LINC01207), which were identified to possess the most remarkable correlation with OS in COAD patients. COAD patients with a high-risk score had poorer OS than those with a low-risk score. The multivariate Cox regression analyses confirmed that the four-lncRNA signature could function as an independent prognostic indicator for COAD patients, which was largely mirrored in the validating cohort with rectal adenocarcinoma (READ) containing 158 cases. In addition, the correlative genes of LINC01555 and LINC01207 were enriched in the cAMP signaling and mucin type O-Glycan biosynthesis pathways. With further validation in the future, our study indicates that the four-lncRNA signature could serve as an independent biomarker for survival of colorectal adenocarcinoma.