Identification of potential microRNAs and their targets in promoting gefitinib resistance by integrative network analysis

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

A novel circ_MACF1/miR-942-5p/TGFBR2 axis regulates the functional behaviors and drug sensitivity in gefitinib-resistant non-small cell lung cancer cells

BACKGROUND

Resistance to gefitinib remains a major obstacle for the successful treatment of non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations. In this paper, we studied the precise actions of circular RNA (circRNA) microtubule actin crosslinking factor 1 (circ_MACF1) in gefitinib resistance.

METHODS

We established gefitinib-resistant NSCLC cells (PC9/GR and A549/GR). The levels of circ_MACF1, microRNA (miR)-942-5p, and transforming growth factor beta receptor 2 (TGFBR2) were gauged by quantitative real-time PCR (qRT-PCR) or western blot. Subcellular fractionation and Ribonuclease R (RNase R) assays were done to characterize circ_MACF1. Cell survival, proliferation, colony formation, apoptosis, migration, and invasion were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-Ethynyl-2'-Deoxyuridine (EdU), colony formation, flow cytometry, and transwell assays, respectively. Dual-luciferase reporter assays were used to verify the direct relationship between miR-942-5p and circ_MACF1 or TGFBR2. The xenograft assays were used to assess the role of circ_MACF1 in vivo.

RESULTS

Circ_MACF1 was down-regulated in A549/GR and PC9/GR cells. Overexpression of circ_MACF1 repressed proliferation, migration, invasion, and promoted apoptosis and gefitinib sensitivity of A549/GR and PC9/GR cells in vitro, as well as inhibited tumor growth under gefitinib in vivo. Circ_MACF1 directly targeted miR-942-5p, and miR-942-5p mediated the regulatory effects of circ_MACF1. TGFBR2 was identified as a direct and functional target of miR-942-5p. Circ_MACF1 modulated TGFBR2 expression through miR-942-5p.

CONCLUSION

Our findings demonstrated that circ_MACF1 regulated cell functional behaviors and gefitinib sensitivity of A549/GR and PC9/GR cells at least partially by targeting miR-942-5p to induce TGFBR2 expression.

Novel Liquid Biomarker Panels for A Very Early Response Capturing of NSCLC Therapies in Advanced Stages

Computed tomography (CT) scans are the gold standard to measure treatment success of non-small cell lung cancer (NSCLC) therapies. Here, we investigated the very early tumor response of patients receiving chemotherapy or targeted therapies using a panel of already established and explorative liquid biomarkers. Blood samples from 50 patients were taken at baseline and at three early time points after therapy initiation. DNA mutations, a panel of 17 microRNAs, glycodelin, glutathione disulfide, glutathione, soluble caspase-cleaved cytokeratin 18 (M30 antigen), and soluble cytokeratin 18 (M65 antigen) were measured in serum and plasma samples. Baseline and first follow-up CT scans were evaluated and correlated with biomarker data. The detection rate of the individual biomarkers was between 56% and 100%. While only keratin 18 correlated with the tumor load at baseline, we found several individual markers correlating with the tumor response to treatment for each of the three time points of blood draws. A combination of the five best markers at each time point resulted in highly significant marker panels indicating therapeutic response (R² = 0.78, R² = 0.71, and R² = 0.71). Our study demonstrates that an early measurement of biomarkers immediately after therapy start can assess tumor response to treatment and might support an adaptation of treatment to improve patients’ outcome.