The circular RNA circ_GRHPR promotes NSCLC cell proliferation and invasion via interactions with the RNA-binding protein PCBP2

Circular RNA in Non-small Cell Lung Carcinoma: Identification of Targets and New Treatment Modalities

Despite availability of several treatment options for non-small cell lung cancer (NSCLC), such as surgery, chemotherapy, radiation, targeted therapy and immunotherapy, the survival rate of patients for five years is in the range of 22%. Therefore, identification of new targets and treatment modalities for this disease is an important issue. In this context, we screened the PubMed database for up-regulated circular RNAs (circRNAs) which promote growth of NSCLC in preclinical models in vitro as well as in vivo xenograft models in immuno-compromised mice. This approach led to potential targets for further validation and inhibition with small molecules or antibody-derived entities. In case of preclinical validation, the corresponding circRNAs can be inhibited with small interfering RNAs (siRNA) or short hairpin RNAs (shRNA). The identified circRNAs act by sponging microRNAs (miRs) preventing cleavage of the mRNA of the corresponding targets. We identified nine circRNAs up-regulating transmembrane receptors, five circRNAs increasing expression of secreted proteins, nine circRNAs promoting expression of components of signaling pathways, six circRNAs involved in regulation of splicing and RNA processing, six circRNAs up-regulating actin-related and RNA processing components, seven circRNAs increasing the steady-state levels of transcription factors, two circRNAs increasing high-mobility group proteins, four circRNAs increasing components of the epigenetic modification system and three circRNAs up-regulating protein components of additional systems.

Propofol synergizes with circAPBB2 to protect against hypoxia/reoxygenation-induced oxidative stress, inflammation, and apoptosis of human cardiomyocytes

BACKGROUND

Myocardial injury is the main manifestation of cardiovascular diseases, and previous studies have shown that propofol (PPF) regulates myocardial injury. However, the mechanism of PPF in regulating myocardial injury remains to be further explored. This work aims to analyze the effects of PPF on human cardiomyocyte injury and the underlying mechanism.

METHODS

The regulatory and functional role of PPF and circAPBB2 in human cardiomyocyte injury were analyzed using an in vitro hypoxia/reoxygenation (H/R) cell model, which was established by treating human cardiomyocytes (AC16 cells) with H/R. The study evaluated AC16 cell injury by analyzing cytotoxicity, oxidative stress, inflammation and apoptosis of H/R-induced AC16 cells. Quantitative real-time polymerase chain reaction was performed to detect circAPBB2, miR-18a-5p and dual specificity phosphatase 14 (DUSP14) expression. Protein expression was analyzed by Western blot analysis assay. Dual-luciferase reporter assay, RNA pull-down assay and RNA immunoprecipitation assay were performed to identify the associations among circAPBB2, miR-18a-5p and DUSP14. Cytotoxicity was investigated by cell counting kit-8 assay and lactate dehydrogenase activity detection kit. Oxidative stress was evaluated by cellular reactive oxygen species assay kit and superoxide dismutase activity assay kit. The production of tumor necrosis factor-α and interleukin-1β was evaluated by enzyme-linked immunosorbent assays.

RESULTS

The expression of circAPBB2 and DUSP14 was significantly decreased, while miR-18a-5p was increased in H/R-induced AC16 cells when compared with controls. H/R treatment-induced cytotoxicity, oxidative stress, inflammation and cell apoptosis were attenuated after circAPBB2 overexpression or PPF treatment, whereas these effects were restored by increasing miR-18a-5p expression. PPF treatment improved the inhibitory effect of ectopic circAPBB2 expression on H/R-induced cell injury. MiR-18a-5p silencing ameliorated H/R-induced AC16 damage by interacting with DUSP14. Mechanically, circAPBB2 acted as a miR-18a-5p sponge, and miR-18a-5p targeted DUSP14 in AC16 cells.

CONCLUSION

PPF synergized with circAPBB2 to protect AC16 cells against H/R-induced oxidative stress, inflammation and apoptosis through the miR-18a-5p/DUSP14 pathway.

Comprehensive Analyses and Immunophenotyping of LIM Domain Family Genes in Patients with Non-Small-Cell Lung Cancer

The LIM domain family genes play a crucial role in various tumors, including non-small-cell lung cancer (NSCLC). Immunotherapy is one of the most significant treatments for NSCLC, and its effectiveness largely depends on the tumor microenvironment (TME). Currently, the potential roles of LIM domain family genes in the TME of NSCLC remain elusive. We comprehensively evaluated the expression and mutation patterns of 47 LIM domain family genes in 1089 NSCLC samples. Using unsupervised clustering analysis, we classified patients with NSCLC into two distinct gene clusters, i.e., the LIM-high group and the LIM-low group. We further investigated the prognosis, TME cell infiltration characteristics, and immunotherapy in the two groups. The LIM-high and LIM-low groups had different biological processes and prognoses. Moreover, there were significant differences in TME characteristics between the LIM-high and LIM-low groups. Specifically, enhanced survival, immune cell activation, and high tumor purity were demonstrated in patients of the LIM-low group, implying an immune-inflamed phenotype. Moreover, the LIM-low group had higher immune cell proportion scores than the LIM-high group and was more responsive to immunotherapy than the LIM-low group. Additionally, we screened out LIM and senescent cell antigen-like domain 1 (LIMS1) as a hub gene of the LIM domain family via five different algorithms of plug-in cytoHubba and the weighted gene co-expression network analysis. Subsequently, proliferation, migration, and invasion assays demonstrated that LIMS1 acts as a pro-tumor gene that promotes the invasion and progression of NSCLC cell lines. This is the first study to reveal a novel LIM domain family gene-related molecular pattern associated with the TME phenotype, which would increase our understanding of the heterogeneity and plasticity of the TME in NSCLC. LIMS1 may serve as a potential therapeutic target for NSCLC.

The emerging role of circular RNAs in drug resistance of non-small cell lung cancer

Due to the characteristics of aggressiveness and high risk of postoperative recurrence, non-small cell lung cancer (NSCLC) is a serious hazard to human health, accounting for 85% of all lung cancer cases. Drug therapies, including chemotherapy, targeted therapy and immunotherapy, are effective treatments for NSCLC in clinics. However, most patients ultimately develop drug resistance, which is also the leading cause of treatment failure in cancer. To date, the mechanisms of drug resistance have yet to be fully elucidated, thus original strategies are developed to overcome this issue. Emerging studies have illustrated that circular RNAs (circRNAs) participate in the generation of therapeutic resistance in NSCLC. CircRNAs mediate the modulations of immune cells, cytokines, autophagy, ferroptosis and metabolism in the tumor microenvironment (TME), which play essential roles in the generation of drug resistance of NSCLC. More importantly, circRNAs function as miRNAs sponges to affect specific signaling pathways, directly leading to the generation of drug resistance. Consequently, this review highlights the mechanisms underlying the relationship between circRNAs and drug resistance in NSCLC. Additionally, several therapeutic drugs associated with circRNAs are summarized, aiming to provide references for circRNAs serving as potential therapeutic targets in overcoming drug resistance in NSCLC.

The Roles of FHL3 in Cancer

The four and a half LIM domain protein 3, also named the LIM-protein FHL3, belongs to the LIM-only family. Based on the special structure of LIM-only proteins, FHL3 can perform significant functions in muscle proliferation and cardiovascular diseases by regulating cell growth and signal transduction. In recent years, there has been increasing evidence of a relation between FHLs and tumor biology, since FHL3 is often overexpressed or downregulated in different cancers. On the one hand, FHL3 can function as a tumor suppressor and influence the expression of downstream genes. On the other hand, FHL3 can also play a role as an oncoprotein in some cancers to promote tumor progression via phosphorylation. Thus, FHL3 is proposed to have a dual effect on cancer progression, reflecting its complex roles in cancer. This review focuses on the roles of FHL3 in cancer progression and discusses the interaction of FHL3 with other proteins and transcription factors. Finally, the clinical significance of FHL3 for the treatment of cancers is discussed.

Circ_0006006 facilitates non-small cell lung cancer progression by modulating miR-924/SRSF7 axis

BACKGROUND

Non-small cell lung cancer (NSCLC) is an aggressive tumor with high mortality. Circular RNAs (CircRNAs) played crucial roles in the development of cancers, including NSCLC. In this study, the action of circ_0006006 in NSCLC was investigated.

METHODS

Using real-time quantitative PCR (RT-qPCR), the relative gene expression was detected. The structure of circ_0006006 was identified using RNase R digestion and Actinomycin D treatment. The functional role of circ_0006006 in cell proliferation, migration, invasion, apoptosis and angiogenesis was explored using Cell Counting Kit-8 (CCK-8), EdU, colony formation, wound healing, transwell, flow cytometry, and tube formation assays, respectively. Using western blot, the relative proteins expression was measured. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to verify the correlation between microRNA-924 (miR-924) and circ_0006006 or serine/arginine-rich splicing factor 7 (SRSF7). Xenograft tumor experiment was used to investigate the effect of circ_0006006 on tumor growth in vivo. Immunohistochemistry (IHC) assay was performed to detect Ki-67, Bax, Bcl-2 and SRSF7 expression in tissues of mice.

RESULTS

Circ_0006006 was increased in NSCLC tissues and cells. Loss-of-function assays demonstrated that circ_0006006 silencing repressed the proliferative ability, cell migration and invasion, angiogenesis, and promoted cell apoptosis in A549 and H1299 cells. Follow-up mechanism experiments depicted that circ_0006006 sponged miR-924 and miR-924 inhibitor rescued circ_0006006 knockdown-mediated inhibition effect on the progression of NSCLC. Additionally, the inhibition effect of circ_0006006 knockdown on SRSF7 expression was reversed by miR-924 inhibitor. Moreover, the suppressive effect of miR-924 on NSCLC progression was reversed by SRSF7 overexpression. Xenograft tumor experiment unveiled that circ_0006006 knockdown inhibited tumor growth in vivo.

CONCLUSION

Circ_0006006 stimulated NSCLC progression by targeting miR-924 to regulate SRSF7 expression.