Construction of a circRNA-miRNA-mRNA Regulated Pathway Involved in EGFR-TKI Lung Adenocarcinoma Resistance

Biological role and regulation of circular RNA as an emerging biomarker and potential therapeutic target for cancer

Circular RNAs (circRNAs) are a unique family of endogenous RNAs devoid of 3' poly-A tails and 5' end caps. These single-stranded circRNAs, found in the cytoplasm, are synthesized via back-splicing mechanisms, merging introns, exons, or both, resulting in covalently closed circular loops. They are profusely expressed across the eukaryotic transcriptome and offer heightened stability against exonuclease RNase R compared to linear RNA counterparts. This review endeavors to provide a comprehensive overview of circRNAs' characteristics, biogenesis, and mechanisms of action. Furthermore, aimed to shed light on the potential of circRNAs as significant biomarkers in various cancer types. It has been performed an exhaustive literature review, drawing on recent studies and findings related to circRNA characteristics, synthesis, function, evaluation techniques, and their associations with oncogenesis. CircRNAs are intricately associated with tumor progression and development. Their multifaceted roles encompass gene regulation through the sponging of proteins and microRNAs, controlling transcription and splicing, interacting with RNA binding proteins (RBPs), and facilitating gene translation. Due to these varied roles, circRNAs have become a focal point in tumor pathology investigations, given their promising potential as both biomarkers and therapeutic agents. CircRNAs, due to their unique biogenesis and multifunctionality, hold immense promise in the realm of oncology. Their stability, widespread expression, and intricate involvement in gene regulation underscore their prospective utility as reliable biomarkers and therapeutic targets in cancer. As our understanding of circRNAs deepens, advanced techniques for their detection, evaluation, and manipulation will likely emerge. These advancements might catalyze the translation of circRNA-based diagnostics and therapeutics into clinical practice, potentially revolutionizing cancer care and prognosis.

Non-coding RNAs as potential therapeutic targets for receptor tyrosine kinase signaling in solid tumors: current status and future directions

This review article presents an in-depth analysis of the current state of research on receptor tyrosine kinase regulatory non-coding RNAs (RTK-RNAs) in solid tumors. RTK-RNAs belong to a class of non-coding RNAs (nc-RNAs) responsible for regulating the expression and activity of receptor tyrosine kinases (RTKs), which play a critical role in cancer development and progression. The article explores the molecular mechanisms through which RTK-RNAs modulate RTK signaling pathways and highlights recent advancements in the field. This include the identification of potential new RTK-RNAs and development of therapeutic strategies targeting RTK-RNAs. While the review discusses promising results from a variety of studies, encompassing in vitro, in vivo, and clinical investigations, it is important to acknowledge the challenges and limitations associated with targeting RTK-RNAs for therapeutic applications. Further studies involving various cancer cell lines, animal models, and ultimately, patients are necessary to validate the efficacy of targeting RTK-RNAs. The specificity of ncRNAs in targeting cellular pathways grants them tremendous potential, but careful consideration is required to minimize off-target effects, the article additionally discusses the potential clinical applications of RTK-RNAs as biomarkers for cancer diagnosis, prognosis, and treatment. In essence, by providing a comprehensive overview of the current understanding of RTK-RNAs in solid tumors, this review emphasizes their potential as therapeutic targets for cancer while acknowledging the associated challenges and limitations.

Circ_0091537 promotes gefitinib chemoresistance in non-small cell lung cancer by mediating the miR-520h/YAP1 network

Chemoresistance is the leading cause of poor outcomes of non-small cell lung cancer (NSCLC). Circular RNA (circRNA) plays a vital role in NSCLC resistance progression. Our study aimed to uncover the role of circRNA PDZ domain containing 8 (circ_0091537) in NSCLC with gefitinib resistance. The expression of circ_0091537, microRNA-520h (miR-520h), and Yes-associated protein 1 (YAP1) mRNA were detected using quantitative real-time PCR. Cell viability and cell proliferation were assessed by MTT assay and colony formation assay. Colony formation ability was detected by colony formation assay. Cell cycle distribution and cell apoptosis were determined by flow cytometry assay. Cell migration and cell invasion were detected by transwell assay. The potential relationship between miR-520h and circ_0091537 or YAP1 was verified by dual-luciferase reporter assay. Tumor formation assay in nude mice was performed to test the role of circ_0091537 in vivo . Circ_0091537 and YAP1 were upregulated, while miR-520h was downregulated in gefitinib-resistant NSCLC cells. Circ_0091537 knockdown inhibited gefitinib resistance in NSCLC cells and then inhibited NSCLC cell growth, migration, and invasion. MiR-520h was a target of circ_0091537, and miR-520h inhibition reversed the effects of circ_0091537 knockdown. Moreover, YAP1 was a target of miR-520h, and circ_0091537 competitively combined with miR-520h to enrich YAP1 expression. MiR-520h restoration impaired gefitinib resistance and suppressed NSCLC cell proliferation, migration, and invasion by repressing YAP1. Circ_0091537 overexpression weakened gefitinib sensitivity in vivo to promote tumor growth. Circ_0091537 strengthens gefitinib chemoresistance to promote NSCLC progression by mediating the miR-520h/YAP1 network, suggesting that circ_0091537 may be a key indicator in resistance to treatment of NSCLC.

Protein tyrosine kinase inhibitor resistance in malignant tumors: molecular mechanisms and future perspective

Protein tyrosine kinases (PTKs) are a class of proteins with tyrosine kinase activity that phosphorylate tyrosine residues of critical molecules in signaling pathways. Their basal function is essential for maintaining normal cell growth and differentiation. However, aberrant activation of PTKs caused by various factors can deviate cell function from the expected trajectory to an abnormal growth state, leading to carcinogenesis. Inhibiting the aberrant PTK function could inhibit tumor growth. Therefore, tyrosine kinase inhibitors (TKIs), target-specific inhibitors of PTKs, have been used in treating malignant tumors and play a significant role in targeted therapy of cancer. Currently, drug resistance is the main reason for limiting TKIs efficacy of cancer. The increasing studies indicated that tumor microenvironment, cell death resistance, tumor metabolism, epigenetic modification and abnormal metabolism of TKIs were deeply involved in tumor development and TKI resistance, besides the abnormal activation of PTK-related signaling pathways involved in gene mutations. Accordingly, it is of great significance to study the underlying mechanisms of TKIs resistance and find solutions to reverse TKIs resistance for improving TKIs efficacy of cancer. Herein, we reviewed the drug resistance mechanisms of TKIs and the potential approaches to overcome TKI resistance, aiming to provide a theoretical basis for improving the efficacy of TKIs.

Hsa_circ_0007312 Promotes Third-Generation Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Resistance through Pyroptosis and Apoptosis via the MiR-764/MAPK1 Axis in Lung Adenocarcinoma Cells

Purposes: Osimertinib is a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) used for patients with gefitinib (first-generation EGFR-TKI) resistance, but osimertinib resistance inevitably occurs. Therefore, it is necessary to explore the mechanisms of osimertinib resistance. Materials and Methods: We performed quantitative real-time polymerase chain reaction to detect hsa_circ_0007312 (circ7312), miR-764, and MAPK1 expressions in tissues and cells. Western blotting was used to detect protein levels in cells. Cell Counting Kit-8, apoptotic, and Transwell assays were used to explore biological functions. Luciferase assays were used to identify the interactions between circ7312 and miR-764, MAPK1 and miR-764. A xenograft experiment was performed to clarify the role of circ7312 in vivo. Public datasets were used to identify the relation between circ7312 expression and the cell half maximal inhibitory concentration value of osimertinib in 41 lung adenocarcinoma cell lines. The Student t-test, Kaplan-Meier analysis, and Pearson correlation analysis were used in data analysis. Results: We found that circ7312 knockdown increased miR-764 expression and decreased MAPK1 expression, and circ7312 regulated MAPK1 by sponging miR-764. In addition, high circ7312 expression has significant positive correlation with osimertinib IC50 values, circ7312 knockdown decreased the cell half maximal inhibitory concentration value of osimertinib and increased pyroptosis and apoptosis by sponging the miR-764/MAPK1 axis. We also found that circ7312 and MAPK1 were highly expressed in tumor tissues and related to poor prognosis. Xenograft experiments revealed that circ7312 knockdown decreased osimertinib resistance in vivo. Conclusion: We demonstrated that the inhibition of circ7312 decreased osimertinib resistance by promoting pyroptosis and apoptosis via the miR-764/MAPK1 axis, providing a novel target for osimertinib resistance therapy.