Background: Noncoding RNAs such as circular RNAs (circRNAs) are abundant in the human body and influence the occurrence and development of various diseases. Non-small cell lung cancer (NSCLC) is one of the most common malignant cancers. Information on the functions and mechanism of circRNAs in lung cancer is limited; thus, the topic needs more exploration. The purpose of this study was to identify aberrantly expressed circRNAs in lung cancer, unravel their roles in NSCLC progression, and provide new targets for lung cancer diagnosis and therapy. Methods: High-throughput sequencing was used to analyze differential circRNA expression in patients with lung cancer. qRT‒PCR was used to determine the level of circHERC1 in lung cancer tissues and plasma samples. Gain- and loss-of-function experiments were implemented to observe the impacts of circHERC1 on the growth, invasion, and metastasis of lung cancer cells in vitro and in vivo. Mechanistically, dual luciferase reporter assays, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP) and RNA pull-down experiments were performed to confirm the underlying mechanisms of circHERC1. Nucleocytoplasmic localization of FOXO1 was determined by nucleocytoplasmic isolation and immunofluorescence. The interaction of circHERC1 with FOXO1 was verified by RNA pull-down, RNA immunoprecipitation (RIP) and western blot assays. The proliferation and migration of circHERC1 in vivo were verified by subcutaneous and tail vein injection in nude mice. Results: CircHERC1 was significantly upregulated in lung cancer tissues and cells, ectopic expression of circHERC1 strikingly facilitated the proliferation, invasion and metastasis, and inhibited the apoptosis of lung cancer cells in vitro and in vivo. However, knockdown of circHERC1 exerted the opposite effects. CircHERC1 was mainly distributed in the cytoplasm. Further mechanistic research indicated that circHERC1 acted as a competing endogenous RNA of miR-142-3p to relieve the repressive effect of miR-142-3p on its target HMGB1, activating the MAPK/ERK and NF-κB pathways and promoting cell migration and invasion. More importantly, we found that circHERC1 could bind FOXO1 and sequester it in the cytoplasm, adjusting the feedback AKT pathway. The accumulation of FOXO1 in the cytosol and nuclear exclusion promoted cell proliferation and inhibited apoptosis. CircHERC1 is a new circRNA that promotes tumor function in NSCLC and may serve as a potential prognostic biomarker and therapeutic target for NSCLC. Conclusions: CircHERC1 is a new circRNA that promotes tumor function in NSCLC and may serve as a potential diagnosis biomarker and therapeutic target for NSCLC. Our findings indicate that circHERC1 facilitates the invasion and metastasis of NSCLC cells by regulating the miR-142-3p/HMGB1 axis and activating the MAPK/ERK and NF-κB pathways. In addition, circHERC1 can promote cell proliferation and inhibit apoptosis by sequestering FOXO1 in the cytoplasm to regulate AKT activity and BIM transcription.

We propose to systematically identify a non-coding RNA (ncRNA) profile of exfoliated bronchial epitheliums of sputum from lung cancer patients. Bronchial epithelial cells enriched from sputum of 32 lung cancer patients and 33 cancer-free smokers were analyzed by next-generation sequencing to comprehensively characterize the ncRNA profiles. In addition, 108 miRNAs, 88 small nucleolar RNAs, 13 piwi-interacting RNAs, 6 transfer RNAs, 4 ribosomal RNAs, 19 small nuclear RNAs, and 25 long-noncoding (lnc) RNAs displayed a significantly different level in bronchial epitheliums of sputum of lung cancer patients versus cancer-free smokers (all <0.001). PCR analysis confirmed their different expression levels in the sputum specimens. A high expression of SNHG9, an lncRNA, was validated in 78 lung tumor tissues, and the expression was inversely associated with overall survival of lung cancer patients (p = 0.002). Knockdown of SNHG9 in cancer cells reduced the cell growth, proliferation, and invasion in vitro and tumorigenesis in vivo. The multiple differentially expressed ncRNAs in bronchial epitheliums may contribute to the development and progression of lung cancer and provide potential biomarkers and therapeutic targets for the disease.

Lung cancer is the most common cancer worldwide. Epigenetic modifications like DNA methylation play fundamental roles in the dynamic process of lung cancer. The objective of this study was to use methyl-CpG binding domain protein-enriched genome sequencing (MBD-Seq) to identify novel and high-confidence DNA methylation in lung tumor. We first compared the whole-genome DNA methylation of three lung cancer cell lines, including A549, H1299, and SK-MES-1, against BEAS-2B, a lung/bronchial normal epithelial cell line. We then used pyrosequencing and OneStep qMethyl kit methods to verify the results in the cell line specimens. MBD-Seq identified 279, 8046, and 22 887 differentially methylated regions (DMRs), respectively, with 120 common DMRs among three comparison groups. Three DMRs were consistent with the MBD-Seq results by both pyrosequencing and OneStep qMethyl validations. Furthermore, OneStep qMethyl kit was also performed for functional validation of these three potential DMRs in sputum DNA from clinical participants. We successfully identified one new DMR adjacent to ATG16L2. The novel DMR might have an important function in lung carcinogenesis. Further validation of the finding in clinical specimens of lung cancer patients and functional analysis of this novel DMR in the development of lung cancer through transcriptional silencing of ATG16L2 are warranted.

This study aims to explore the molecules that affect the survival of Human Umbilical Vein Endothelial Cells (HUVECs) under hypoxia and their mechanisms of action. In hypoxia, plasmolipin (PLLP) was identified through the screening of CRISPR/Cas9 and small guide RNA (sgRNA) library. Functionally, PLLP knockout led to increase cell proliferation, cellular metabolism, tight junction formation, angiogenesis ability, migration and invasion in hypoxic HUVECs. Furthermore, PLLP knockout countered the inhibitory effects of bevacizumab on HUVECs angiogenesis and cell survival in hypoxic conditions. PLLP knockout was found to modulate the survival of HUVECs in hypoxia by enhancing the phosphorylation of AKT and ERK1/2 proteins. In conclusion, inhibiting the expression of PLLP in HUVECs promotes cell survival and maintenance of cellular functions under hypoxic condition. PLLP plays a crucial role in regulating cell survival in hypoxia through the activation of AKT and ERK1/2 pathways. This study identifies novel molecules that affect HUVECs survival under hypoxic conditions and provides a new possibility for future studies on cell survival under hypoxic conditions.