BACKGROUND: Radiotherapy is one of main useful therapies in non-small cell lung cancer (NSCLC). Nevertheless, the underlying mechanism between NSCLC cell radiosensitivity and effective treatment remains unclear. OBJECTIVE: The aim is to explore the relationship between circular (circ) RNA and NSCLC cell radiosensitivity. METHODS: CircRNA plasmacytoma variant translocation 1 (PVT1) and microRNA (miR)-1208 expression in NSCLC cells were assessed using quantitative reverse transcriptase PCR (qRT-PCR). NSCLC cells were transfected with si-PVT1 or miR-1208 inhibitor and then exposed to irradiation. Cellular biology behaviors were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL), colony formation, invasion and western blot. Additionally, binding between circPVT1 and miR-1208 was testified by dual-luciferase reporter and RIP assay. RESULTS: CircPVT1 was upregulated in NSCLC cells after irradiation treatment. Silencing circPVT1 induced inhibition of NSCLC cell growth and invasion, accompanied by cell apoptosis and γ-H2AX expression. Moreover, NSCLC cell proliferation and invasion was further inhibited by irradiation treatment in circPVT1-silenced cells, indicating a strong radiosensitivity of NSCLC cells. CircPVT1 functions as a competing endogenous RNA towards miR-1208. Silencing miR-1208 reversed NSCLC cell sensitivity response to irradiation and activated PI3K/AKT/mTOR pathway in circPVT1-silenced cells. CONCLUSIONS: Silencing circPVT1 enhanced radiosensitivity of NSCLC cells by sponging miR-1208.

As the most common histological subtype of primary lung cancer, lung adenocarcinoma (LUAD) causes enormous cancer deaths worldwide. Radiotherapy has been frequently used in LUAD cases, and radiosensitivity is vital for LUAD therapy. This research sought to explore the genetic factors affecting radiosensitivity in LUAD and inner mechanisms. LINC00511, miR-497-5p, and SMAD3 expression in LUAD cells were detected via qRT-PCR and western blot. CCK-8 assays, colony formation, and flow cytometry assays were employed to explore the cell viability, apoptosis, and radiosensitivity in PC-9 and A549 cells. The targeting relationship between LINC00511, miR-497-5p, and SMAD3 was verified by dual luciferase reporter assay. Furthermore, xenograft experiments were performed for the in vivo verification. In conclusion, LINC00511 was overexpressed in LUAD cells, which downregulated downstream miR-497-5p expression and mediately led to SMAD3 activation. LINC00511 downregulation suppressed cell viability while enhanced apoptosis rate in LUAD cells. Also, LINC00511 and SMAD3 were overexpressed, while miR-497-5p was downregulated in LUAD cells exposed to 4Gy irradiation treatment. Moreover, LINC00511 inhibition could block SMAD3 expression and promoted the radiosensitivity both in vitro and in vivo. These findings uncover LINC00511 knockdown promoted miR-497-5p expression and subsequently led to lower SMAD3 level, which enhanced radiosensitivity in LUAD cells. LINC00511/miR-497-5p/SMAD3 axis could be of considerable potential to enhance radiosensitivity in LUAD.

Background: Amonafide (Amo), due to hematotoxicity and digestive tract symptoms, the clinical application of which is limited. Several studies have reported that chemotherapy side effects are closely related to cellular senescence accumulation. Our study aims to examine whether amonafide causes senescence in human umbilical vein endothelial cell (HUVEC) lines and investigate its mechanisms associated with senescence. Methods: The experiments of expression of genes and proteins associated with aging were carried out with HUVEC cell lines. The experiments were divided into a control group and an amonafide group with different days. The HUVEC senescence cells were detected by SA-β-Gal staining, Western blotting detected the protein levels of p16, p53, AMPK (Adenosine 5'-Monophosphate (AMP)-Activated Protein Kinase), mTOR (mechanistic Target of Rapamycin), p62, and LC3 (microtubule-associated protein1 light chain 3, MAP1LC3). Fluorescence detected the expression of mRFP (monomeric Red Fluorescent Protein)-GFP (Green Fluorescent Protein)-LC3 and LC3 puncta of HUVEC cells. RT-qPCR (Real-Time Quantitative Polymerase Chain Reaction) tested the expressions of p53, p21, IL (Interleukin)-1β, IL-6 (Interleukin-6), IL-8 (Interleukin-8), and MCP-1 (Monocyte Chemoattractant Protein-1). CCK-8 (Cell Counting Kit-8) assessed the HUVEC cell viability. Results: Here, we reported that amonafide resulted in an increased proportion of SA-β-Gal positive cells, high expression of aging-related proteins (p53 p < 0.05; p16 p < 0.05), and aging-related genes (p53 p < 0.05; p21 p < 0.05; IL-1β p < 0.05; IL-6 p < 0.05; IL-8 p < 0.05; MCP-1 p < 0.05) on the 3rd day. Mechanistically, amonafide could cause an increase in the levels of the mTOR (p < 0.05) on days 1 and 3, and p62 protein (p < 0.05) on day 1, and a decline in LC3II (microtubule-associated protein1 light chain 3Ⅱ)/LC3I levels (p < 0.05) on day 3, which is associated with the regulation of senescence. Additionally, the viability of HUVECs (human umbilical vein endothelial cells) was significantly inhibited by amonafide starting with a concentration of 0.8 µm (p < 0.05). Conclusions: We first discovered that amonafide caused normal cellular senescence in our experiments. Amonafide-induced cellular aging by inhibiting autophagy and activating the mTOR pathway. The findings may offer new strategies for managing adverse reactions to amonafide.