Molecularly targeted therapies in non-small cell lung cancer: The evolving role of tyrosine kinase inhibitors

UBE2T regulates FANCI monoubiquitination to promote NSCLC progression by activating EMT

Fanconi anemia complementation group I (FANCI) is a critical protein for maintaining DNA stability. However, the exact role of FANCI in tumors remains to be elucidated. The present study aimed to explore the role and potential mechanism of action of FANCI in non-small cell lung cancer (NSCLC). To quantify the expression levels of FANCI and ubiquitin-conjugating enzyme E2T (UBE2T) in NSCLC tissues, reverse-transcription quantitative PCR and western blotting were employed. Cell Counting Kit-8, wound healing and Transwell assays along with flow cytometry analysis and tumor xenograft were used to investigate the biological effects of FANCI in NSCLC in vitro and in vivo. The binding of FANCI with UBE2T was confirmed using a co-immunoprecipitation assay. Epithelial-to-mesenchymal transition (EMT) protein markers were quantified via western blotting. The results showed that FANCI expression level was higher in NSCLC tumor tissues, compared with adjacent tissues. In A549 and H1299 cells, knockdown of FANCI inhibited cell proliferation, migration, invasion, cell cycle and EMT in vitro. Tumor growth was repressed in vitro, upon downregulation of FANCI expression. UBE2T was observed to directly bind to FANCI and regulate its monoubiquitination. Overexpression of UBE2T reversed the effects induced by FANCI knockdown in NSCLC cells. Furthermore, it was noted that FANCI interacted with WD repeat domain 48 (WDR48). Overexpression of WDR48 reversed the effects of FANCI on cell proliferation, migration and EMT. In conclusion, FANCI was identified to be a putative oncogene in NSCLC, wherein FANCI was monouniubiquitinated by UBE2T to regulate cell growth, migration and EMT through WDR48. The findings suggested that FANCI could be used as a prognostic biomarker and therapeutic target for NSCLC.

Exosomal miR-136-5p Derived from Anlotinib-Resistant NSCLC Cells Confers Anlotinib Resistance in Non-Small Cell Lung Cancer Through Targeting PPP2R2A

Background

Anlotinib resistance is a challenge for advanced non-small cell lung cancer (NSCLC). Understanding the underlying mechanisms against anlotinib resistance is of great importance to improve prognosis and treatment of patients with advanced NSCLC.

Methods

RT-qPCR assay was used to assess the level of miR-136-5p in anlotinib-resistant NSCLC cells and exosomes derived from anlotinib-resistant NSCLC cells. In addition, miR-136-5p level in tumor tissues from patients who exhibited a poor response to anlotinib therapy and patients who were therapy naïve or patients who exhibited a positive response to anlotinib therapy was detected by RT-qPCR assay.

Results

In this study, we found that high levels of plasma exosomal miR-136-5p is correlated with clinically poor anlotinib response. In addition, anlotinib-resistant NSCLC cells promoted parental NSCLC cell proliferation via transferring functional miR-136-5p from anlotinib-resistant NSCLC cells to parental NSCLC cells via exosomes. Moreover, exosomal miR-136-5p could endow NSCLC cells with anlotinib resistance by targeting PPP2R2A, leading to the activation of Akt pathway. Furthermore, miR-136-5p antagomir packaging into anlotinib-resistant NSCLC cell-derived exosomes functionally restored NSCLC cell anlotinib sensitivity in vitro. Animal studies showed that A549/anlotinib cell-derived exosomal miR-136-5p agomir promoted A549 cell anlotinib resistance in vivo.

Conclusion

Collectively, these findings indicated that anlotinib-resistant NSCLC cell-derived exosomal miR-136-5p confers anlotinib resistance in NSCLC cells by targeting PPP2R2A, indicating miR-136-5p may act as a potential biomarker for anlotinib response in NSCLC.

Perspectives and controversies regarding the use of natural products for the treatment of lung cancer

Lung cancer is the leading cause of cancer‐related mortality both in men and women and accounts for 18.4% of all cancer‐related deaths. Although advanced therapy methods have been developed, the prognosis of lung cancer patients remains extremely poor. Over the past few decades, clinicians and researchers have found that chemical compounds extracted from natural products may be useful for treating lung cancer. Drug formulations derived from natural compounds, such as paclitaxel, doxorubicin, and camptothecin, have been successfully used as chemotherapeutics for lung cancer. In recent years, hundreds of new natural compounds that can be used to treat lung cancer have been found through basic and sub‐clinical research. However, there has not been a corresponding increase in the number of drugs that have been used in a clinical setting. The probable reasons may include low solubility, limited absorption, unfavorable metabolism, and severe side effects. In this review, we present a summary of the natural compounds that have been proven to be effective for the treatment of lung cancer, as well as an understanding of the mechanisms underlying their pharmacological effects. We have also highlighted current controversies and have attempted to provide solutions for the clinical translation of these compounds.

Advances in targeting EGFR allosteric site as anti-NSCLC therapy to overcome the drug resistance

BACKGROUND

The epidermal growth factor receptor (EGFR) inhibitors represent the first-line therapy regimen for non-small cell lung cancer (NSCLC). Most of these inhibitors target the ATP-site to stop the aggressive development of NSCLC. Stabilization of the ATP-binding on EGFR is difficult due to autophosphorylation of the EGFR domain. This leads to activation of nonintrinsic influence of the tumor microenvironment and expression of anti-apoptotic pathways and drug resistance.

METHODS

The NSCLC related literature search was carried out using online databases such as Scopus, Web of Sciences, PubMed, Protein Data Bank and UniPort for the last ten years and selected articles are referred for discussion in this review.

RESULTS

To overcome the problem of mutations in NSCLC, the allosteric site of EGFR was targeted, which shows significant therapeutic outcome without causing resistance. Compounds like EAI001, EAI045 JBJ-04-125-02, DDC4002 and a series of small molecules with an affinity towards the EGFR allosteric site are reported and are under the investigational stage. These compounds are categorized under fourth-generation anti-NSCLC agents.

CONCLUSION

Composition of this review highlights the advantage of inhibiting allosteric site in the EGFRTK receptor domains and presents a comparative analysis of the new fourth-generation anti-NSCLC agents to overcome the drug resistance.

Value of circular RNA 0007385 in disease monitoring and prognosis estimation in non-small-cell lung cancer patients

Objective

This study aimed to assess the circular RNA_0007385 (hsa_circ_0007385) expression in tumor/adjacent non‐tumor tissues, and the correlation of its tumor expression with clinicopathological features as well as survival in non–small‐cell lung cancer (NSCLC) patients.

Methods

210 NSCLC patients who underwent tumor resection were reviewed in this retrospective study. 210 tumor specimens and 81 paired adjacent specimens were collected, in which the hsa_circ_0007385 expression was detected by reverse transcription‐quantitative polymerase chain reaction assay. Disease‐free survival (DFS) and overall survival (OS) were recorded, and the last follow‐up date was June 30, 2019.

Results

Hsa_circ_0007385 was upregulated in tumor tissue compared with adjacent non‐tumor tissue (P < .001), and ROC curve analysis revealed that hsa_circ_0007385 expression had an excellent value in distinguishing tumor tissue from adjacent non‐tumor tissue with an area under curve of 0.922 (95% CI: 0.890‐0.953). Tumor hsa_circ_0007385 high expression correlated with lymph node metastasis (P = .007) and higher TNM stage (P = .004). In addition, DFS (P = .028) and OS (P = .008) were both less favorable in patients with tumor hsa_circ_0007385 high expression compared to patients with tumor hsa_circ_0007385 low expression. Besides, the DFS (P = .008) and OS (P = .012) were also the worst in patients with tumor hsa_circ_0007385 high+++ expression, followed by patients with tumor hsa_circ_0007385 high++ expression and patients with tumor hsa_circ_0007385 high + expression, and the best in patients with tumor hsa_circ_0007385 low expression. Multivariate regression analysis elucidated that tumor hsa_circ_0007385 high expression independently predicted worse OS (P = .033).

Conclusion

Tumor hsa_circ_0007385 could be a novel biomarker for disease monitoring and prognosis prediction in NSCLC patients.

Spred-3 mutation and Ras/Raf/MAPK activation confer acquired resistance to EGFR tyrosine kinase inhibitor in an EGFR mutated NSCLC cell line

Background

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are standard treatment for advanced non-small cell lung cancer (NSCLC). However, the emergence of EGFR-TKIs resistance poses a big challenge to the treatment. Although several resistant mutations have been identified, our understanding of the mechanisms underlying acquired EGFR-TKIs resistance remains incomplete. This study aimed to identify novel mutations and mechanisms that could contribute to acquired EGFR-TKIs resistance in EGFR mutated NSCLC cells.

Methods

Erlotinib resistant cells (HCC827/ER cells) were generated from the EGFR mutated NSCLC cell line HCC827, and whole-exome sequencing was performed to identify gene mutations in HCC827/ER cells. The Spred-3 expression was determined using quantitative real-time PCR (qPCR) and Western blotting assays, and the p-p44/42, p44/42, p-Akt and Akt expression was determined using Western blotting. The half maximal inhibitory concentration (IC₅₀ value) was measured using the MTS assay, and cell migration was detected with a Transwell migration assay.

Results

Whole-exome sequencing identified deletion mutation c.120delG at exon 1 of the Spred-3 gene, resulting in a p.E40fs change in amino acid, in HCC827/ER cells. The Spred-3 expression was much reduced in HCC827/ER cells as compared to the HCC827 cells at both mRNA and protein levels. Knocking out Spred-3 in HCC827 cells using CRISPR/Cas9 increased erlotinib resistance and cell migration, while overexpressing Spred-3 in HCC827/ER cells using a cDNA construct reduced erlotinib resistance and cell migration. We also showed the Ras/Raf/MAPK pathway was activated in HCC827/ER cells, and inhibiting ERK1/2 in HCC827/Spred-3-sgRNA cells resulted in reduced erlotinib resistance and cell migration.

Conclusions

The results of this study indicate that a loss-of-function mutation in Spred-3 resulted in activation of the Ras/Raf/MAPK pathway that confers resistance to EGFR-TKIs in NSCLC cells harboring an EGFR mutation.