Genome-wide identification and characterization of long non-coding RNAs involved in acquired resistance to gefitinib in non-small-cell lung cancer

LINC00467 mediates the 5-fluorouracil resistance in breast cancer cells

Breast cancer is a prevalent global disease that requires the development of effective therapeutic approaches. The occurrence of 5-fluorouracil (5-FU) resistance in breast cancer is emerging, which urgently needs new way to overcome the obstacle. In this study, we validated that the expression of LINC00467 is up-regulated in the breast cancer patients and breast cancer cells. In addition, the high expression of LINC00467 is associated with the 5-FU resistance of breast cancer cells. Interestingly, LINC00467 induced the homologous recombination (HR) repair via promoting the expression of NBS1 in 5-FU resistant breast cancer cells. Furthermore, miR-205 was validated as a common target of LINC00467 and NBS1, indicating that LINC00467 may induce NBS1 via the miRNA-mRNA target. Importantly, we identified that XBP1, as a transcription factor, induced the expression of LINC00467, which resulted in the enhanced HR efficiency and 5-FU resistance. Silencing XBP1 sensitized the 5-FU resistant breast cancer cells to the 5-FU treatment, whereas the ectopic expression of LINC00467 abrogated the effect of XBP1 silencing. In conclusion, LINC00467 enhances the 5-FU resistance by inducing NBS1-mediated DNA repair. LINC00467 also mediates the function of XBP1 in 5-FU resistance in breast cancer cells.

Long non-coding RNAs in non-small cell lung cancer: implications for EGFR-TKI resistance

Non-small cell lung cancer (NSCLC) is one of the most common types of malignant tumors as well as the leading cause of cancer-related deaths in the world. The application of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has dramatically improved the prognosis of NSCLC patients who harbor EGFR mutations. However, despite an excellent initial response, NSCLC inevitably becomes resistant to EGFR-TKIs, leading to irreversible disease progression. Hence, it is of great significance to shed light on the molecular mechanisms underlying the EGFR-TKI resistance in NSCLC. Long non-coding RNAs (lncRNAs) are critical gene modulators that are able to act as oncogenes or tumor suppressors that modulate tumorigenesis, invasion, and metastasis. Recently, extensive evidence demonstrates that lncRNAs also have a significant function in modulating EGFR-TKI resistance in NSCLC. In this review, we present a comprehensive summary of the lncRNAs involved in EGFR-TKI resistance in NSCLC and focus on their detailed mechanisms of action, including activation of alternative bypass signaling pathways, phenotypic transformation, intercellular communication in the tumor microenvironment, competing endogenous RNAs (ceRNAs) networks, and epigenetic modifications. In addition, we briefly discuss the limitations and the clinical implications of current lncRNAs research in this field.

Lnc-TMEM132D-AS1 as a potential therapeutic target for acquired resistance to osimertinib in non-small-cell lung cancer

Acquired resistance is a major obstacle to the therapeutic efficacy of osimertinib in non-small-cell lung cancer (NSCLC). Current knowledge about the role of long non-coding RNAs (lncRNAs) in this phenomenon is insufficient. In this study, we screened the differentially expressed lncRNAs between osimertinib-sensitive and -resistant NSCLC cell lines, and determined that lnc-TMEM132D-AS1 was significantly upregulated in osimertinib-resistant NSCLC cells, as well as in the plasma of osimertinib-resistant NSCLC patients. Lnc-TMEM132D-AS1 markedly decreased the osimertinib sensitivity of NSCLC cells. After osimertinib exposure, it increased the cell proliferation and colony formation, decreased the cell apoptosis, and induced M2/G-phase cell cycle arrest. After identifying its cytoplasmic localization, a functional lnc-TMEM132D-AS1-miRNA-mRNA interaction network and a protein-protein interaction (PPI) network were constructed to analyze its putative target genes and biological functions. Lnc-TMEM132D-AS1 could directly bind to miR-766-5p and lead to the upregulation of ectonucleoside triphosphate diphosphohydrolase-1 (ENTPD1), resulting in an increase in cell proliferation. Moreover, upregulated ENTPD1 was also associated with enhanced tumor infiltration of immunosuppressive cells and poor prognosis in NSCLC patients. In summary, lnc-TMEM132D-AS1 plays a crucial role in osimertinib resistance. It may serve as a prognostic biomarker and a potential therapeutic target for acquired resistance to osimertinib in NSCLC.

CircSETD3 mediates acquired resistance to gefitinib in non-small lung cancer cells by FXR1/ECT2 pathway

BACKGROUND

Gefitinib is the first-line treatment for non-small cell lung cancer (NSCLC) harboring EGFR sensitive mutation. However, acquired resistance significantly limits its therapeutic efficacy. CircSETD3 has been reported to promote gefitinib resistance in NSCLC cells, however, its underlying mechanisms have not been fully clarified.

METHODS

The expression of circSETD3 were detected in NSCLC patients who received gefitinib as first-line treatment, including 20 gefitinib-sensitive patients and 20 acquired gefitinib-resistant patients. Cell viability were examined by CCK8 assay. The mRNA and protein levels were detected by qRT-PCR and western blot. Using RNA pull-down assay followed by mass spectrometry to identified proteins that interact with circSETD3. The interaction between circSETD3 and fragile X-related protein-1 (FXR1) were further validated by RNA immunoprecipitation (RIP) and pull-down analysis. Fuorescence in situ hybridization (FISH) and immunofluorescence (IF) assays was used for the identification of sub-location of circSETD3 and FXR1 in cells. The effect of circSETD3 overexpression and knockdown on NSCLC tumor growth to gefitinib sensitivity was detected using the mouse xenograft model.

RESULTS

CircSETD3 was significantly upregulated in gefitinib-resistant NSCLC cells, and decreased the gefitinib sensitivity in vitro and in vivo. Mechanically, circSETD3 facilitated FXR1 binding to its downstream mRNA target, epithelial cell-transforming sequence 2 (ECT2), promoting ECT2 mRNA decay, which further inhibited cellular apoptosis.

CONCLUSION

CircSETD3/FXR1/ECT2 axis plays a critical role in the acquired resistance to gefitinib in NSCLC. Our results highlight the potential of circSETD3 as a biomarker and therapeutic target for NSCLC patients with acquired gefitinib resistance.

Lnc-ABCA12-8 confers acquired resistance to gefitinib in non-small cell lung cancer by regulating the alternative splicing of fibronectin 1 in the IIICS region

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib, has dramatically impaired the clinical outcomes in non-small cell lung cancer (NSCLC) patients, but the mechanisms are still unclear in substantial cases. In our previous study, we demonstrated that a novel long non-coding RNA (lncRNA), lnc-ABCA12-8, was overexpressed in gefitinib-resistant NSCLC cells, but the exact function is unknown. In this study, we confirmed that lnc-ABCA12-8 was significantly upregulated both in NSCLC cell lines and the plasma samples of NSCLC patients with acquired resistance to gefitinib. Downregulation of lnc-ABCA12-8 could reverse gefitinib resistance both in vitro and in vivo. Mechanistically, lnc-ABCA12-8 interacted with alternative splicing factor/splicing factor 2 (ASF/SF2), promoted the binding of ASF/SF2 to the IIICS exon of fibronectin 1 (FN1) gene and enhanced the IIICS region inclusion during fibronectin 1 (FN1) alternative splicing, resulting in the upregulation of entire IIICS region, and enhanced cell proliferation, migration, invasion, and adhesion. Taken together, our study suggest that lnc-ABCA12-8 is involved in the acquired resistance to gefitinib, and may be a novel biomarker and therapeutic target for monitoring and overcoming gefitinib resistance in NSCLC.

circSETD3 Contributes to Acquired Resistance to Gefitinib in Non-Small-Cell Lung Cancer by Targeting the miR-520h/ABCG2 Pathway

Gefitinib is a first-line treatment for patients with non-small-cell lung cancer (NSCLC), but acquired resistance is a major obstacle to its therapeutic efficacy, and the underlying mechanisms are not fully elucidated. Recent studies have indicated that circular RNAs play a crucial role in chemoresistance, but their expression and function in NSCLC cells with acquired resistance to gefitinib are largely unknown. In this study, we determined that circSETD3 was significantly upregulated in gefitinib-resistant NSCLC cell lines and the plasma of gefitinib-resistant NSCLC patients. circSETD3 markedly decreased the gefitinib sensitivity of NSCLC cells both in vitro and in nude mice xenografts. It could directly bind to miR-520h and lead to the upregulation of ATP-binding cassette subfamily G member 2 (ABCG2), an efflux transporter of gefitinib, resulting in a reduced intracellular gefitinib concentration. Moreover, we reported that the downregulation of serine/arginine splicing factor 1 (SRSF1) contributed to, at least in part, the increased expression of circSETD3 in NSCLC cells with acquired resistance to gefitinib. Taken together, our findings indicated that circSETD3 may serve as a prognostic biomarker and a potential therapeutic target for acquired resistance to gefitinib in NSCLC.