GPR176 Promotes Cancer Progression by Interacting with G Protein GNAS to Restrain Cell Mitophagy in Colorectal Cancer.

GPR176 belongs to the G protein-coupled receptor superfamily, which responds to external stimuli and regulates cancer progression, but its role in colorectal cancer (CRC) remains unclear. In the present study, expression analyses of GPR176 are performed in patients with colorectal cancer. Genetic mouse models of CRC coupled with Gpr176-deficiency are investigated, and in vivo and in vitro treatments are conducted. A positive correlation between GPR176 upregulation and the proliferation and poor overall survival of CRC is demonstrated. GPR176 is confirmed to activate the cAMP/PKA signaling pathway and modulate mitophagy, promoting CRC oncogenesis and development. Mechanistically, the G protein GNAS is recruited intracellularly to transduce and amplify extracellular signals from GPR176. A homolog model tool confirmed that GPR176 recruits GNAS intracellularly via its transmembrane helix 3-intracellular loop 2 domain. The GPR176/GNAS complex inhibits mitophagy via the cAMP/PKA/BNIP3L axis, thereby promoting the tumorigenesis and progression of CRC.

Analysis of lncRNA-Associated ceRNA Network Reveals Potential lncRNA Biomarkers in Human Colon Adenocarcinoma.

BACKGROUND/AIMS: Long non-coding RNAs (lncRNAs) acting as competing endogenous RNAs (ceRNAs) play significant roles in the development of tumors, but the functions of specific lncRNAs and lncRNA-related ceRNA networks have not been fully elucidated for colon adenocarcinoma (COAD). In this study, we aimed to clarify the lncRNA-microRNA (miRNA)-mRNA ceRNA network and potential lncRNA biomarkers in COAD. METHODS: We extracted data from The Cancer Genome Atlas (TCGA) and identified COAD-specific mRNAs, miRNAs, and lncRNAs. The biological processes in Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were analyzed for COAD-specific mRNAs. We then constructed a ceRNA network of COAD-specific mRNAs, miRNAs and lncRNAs and analyzed the correlation between expression patterns and clinical features of the lncRNAs involved. After identifying potential mRNA targets of 4 lncRNAs related to overall survival (OS), we conducted stepwise analysis of these targets through GO and KEGG. Using tissue samples from our own patients, we also verified certain analytical results using quantitative real-time PCR (qRT-PCR). RESULTS: Data from 521 samples (480 tumor tissue and 41 adjacent non-tumor tissue samples) were extracted from TCGA. A total of 258 specific lncRNAs, 206 specific miRNAs, and 1467 specific mRNAs were identified (absolute log2 [fold change] > 2, false discovery rate < 0.01). Analysis of KEGG revealed that specific mRNAs were enriched in cancer-related pathways. The ceRNA network was constructed with 64 lncRNAs, 18 miRNAs, and 42 mRNAs. Among these lncRNAs involved in the network, 3 lncRNAs (LINC00355, HULC, and IGF2-AS) were confirmed to be associated with certain clinical features and 4 lncRNAs (HOTAIR, LINC00355, KCNQ1OT1, and TSSC1-IT1) were found to be negatively linked to OS (log-rank p < 0.05). KEGG showed that the potential mRNA targets of these 4 lncRNAs may be concentrated in the MAPK pathway. Certain results were validated by qRT-PCR. CONCLUSION: This study providing novel insights into the lncRNA-miRNA-mRNA ceRNA network and reveals potential lncRNA biomarkers in COAD.

Upregulated miR-1258 regulates cell cycle and inhibits cell proliferation by directly targeting E2F8 in CRC.

OBJECTIVES: MicroRNAs (miRNAs) as small noncoding RNA molecules function by regulating their target genes negatively. MiR-1258 was widely researched in multicancers, but its role remains unclear in colorectal cancer (CRC). METHODS: The expression of miR-1258 and its specific target gene were detected in human CRC specimens and cell lines by miRNA RT-PCR, qRT-PCR and Western blot. The effects of miR-1258 on CRC proliferation were evaluated using CCK-8 assays, EdU incorporation, colony formation assays and cell-cycle assays; in vitro and the in vivo effects were investigated using a mouse tumorigenicity model. Luciferase reporter and RIP assays were employed to identify interactions between miR-1258 and its specific target gene. RESULTS: MiR-1258 was downregulated in CRC tissues and CRC cell lines, and upregulated miR-1258 was proved to inhibit proliferation and arrest cell cycle at G0/G1 in vitro and vivo. Luciferase reporter, RIP and western blot assays revealed E2F8 to be a direct target of miR-1258. The effects of miR-1258 in proliferation and cell cycle regulation can be abolished by E2F8 through rescue experiments. By directly targeting E2F8, miR-1258 influenced the expression of several cell-cycle factors, including cyclin D1 (CCND1) and cyclin dependent kinase inhibitor 1A (p21). CONCLUSION: MiR-1258 may function as a suppressive factor by negatively controlling E2F8, thus, highlighting the potential role of miR-1258 as a therapeutic target for human CRC.

Construction of a ceRNA network reveals potential lncRNA biomarkers in rectal adenocarcinoma.

Competing endogenous RNAs (ceRNAs) render the functions of long non­coding RNAs (lncRNAs) more complicated during cancer processes. Potential lncRNA biomarkers and their roles as ceRNAs have not been clearly described for rectal adenocarcinoma (READ). In the present study, we extracted data from The Cancer Genome Atlas (TCGA) including data from 167 tumor samples and 10 adjacent non­tumor samples. A total of 202 lncRNAs, 190 microRNAs (miRNAs) and 1,530 mRNAs were identified as READ­specific RNAs [log2(fold­change)>2, FDR<0.01]. The Gene Ontology (GO) biological processes and the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways were analysed for 1,530 specific mRNAs. Among 202 READ­specific lncRNAs, 7 lncRNAs were identified as being associated with overall survival of READ patients. Then, a ceRNA network was constructed with 34 key lncRNAs, 25 miRNAs and 65 mRNAs. A total of 7 lncRNAs from the network were revealed to be linked to clinical features. The results of qRT­PCR ascertained that our analysis was credible. Overall, this research provides a novel perspective from which to study the lncRNA­related ceRNA network in READ and assists in the identification of new potential biomarkers to be used for diagnostic and prognostic purposes.