Targeting DNA-PK overcomes acquired resistance to third-generation EGFR-TKI osimertinib in non-small-cell lung cancer

ITGB1 and DDR activation as novel mediators in acquired resistance to osimertinib and MEK inhibitors in EGFR-mutant NSCLC

Osimertinib is a third-generation tyrosine kinase inhibitor clinically approved for first-line treatment of EGFR-mutant non-small cell lung cancer (NSCLC) patients. Although an impressive drug response is initially observed, in most of tumors, resistance occurs after different time and an alternative therapeutic strategy to induce regression disease is currently lacking. The hyperactivation of MEK/MAPKs, is one the most common event identified in osimertinib-resistant (OR) NSCLC cells. However, in response to selective drug pressure, the occurrence of multiple mechanisms of resistance may contribute to treatment failure. In particular, the epithelial-to-mesenchymal transition (EMT) and the impaired DNA damage repair (DDR) pathways are recognized as additional cause of resistance in NSCLC thus promoting tumor progression. Here we showed that concurrent upregulation of ITGB1 and DDR family proteins may be associated with an increase of EMT pathways and linked to both osimertinib and MEK inhibitor resistance to cell death. Furthermore, this study demonstrated the existence of an interplay between ITGB1 and DDR and highlighted, for the first time, that combined treatment of MEK inhibitor with DDRi may be relevant to downregulate ITGB1 levels and increase cell death in OR NSCLC cells.

CRISPR/dCas9-Mediated Specific Molecular Assembly Facilitates Genotyping of Mutant Circulating Tumor DNA

Breakthroughs in circulating tumor DNA (ctDNA) analysis are critical in tumor liquid biopsies but remain a technical challenge due to the double-stranded structure, extremely low abundance, and short half-life of ctDNA. Here, we report an electrochemical CRISPR/dCas9 sensor (E-dCas9) for sensitive and specific detection of ctDNA at a single-nucleotide resolution. The E-dCas9 design harnesses the specific capture and unzipping of target ctDNA by dCas9 to introduce a complementary reporter probe for specific molecular assembly and signal amplification. By efficient homogeneous assembly and interfacial click reaction, the assay demonstrates superior sensitivity (up to 2.86 fM) in detecting single-base mutant ctDNA and a broad dynamic range spanning 6 orders of magnitude. The sensor is also capable of measuring 10 fg/μL of a mutated target in excess of wild-type ones (1 ng/μL), equivalent to probing 0.001% of the mutation relative to the wild type. In addition, our sensor can monitor the dynamic expression of cellular genomic DNA and allows accurate analysis of blood samples from patients with nonsmall cell lung cancer, suggesting the potential of E-dCas9 as a promising tool in ctDNA-based cancer diagnosis.

Experimental study of EGFR-TKI aumolertinib combined with ionizing radiation in EGFR mutated NSCLC brain metastases tumor

Aumolertinib is an irreversible third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), although it has been administered for the treatment of epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). However, it is unclear whether aumolertinib combined with ionizing radiation (IR) has potential therapeutic effects in treating brain metastases (BM) tumors from NSCLC. This study explored the anti-tumor effects of aumolertinib combined with IR in epidermal growth factor receptor mutated (EGFRm) NSCLC BM tumors. First, we established a xenograft model of NSCLC BM tumors in BALB/c nude mice and assessed the anti-tumor effects of this combination. Furthermore, we examined the concentrations of aumolertinib in brain tissue and blood using liquid chromatography-mass spectrometry (LC-MS); after that, we used CCK-8, colony formation, flow cytometry assay, and immunofluorescence staining to detect the effects of aumolertinib combined with IR upon PC-9 and NCI-H1975 cells, such as cell proliferation, survival, apoptosis, cycle distribution, the situation of DNA damage, and the expression levels of relevant proteins which were detected via western blotting; finally, we chose a clinical case with which to explore the clinical benefits to the EGFRm NSCLC BM patient after the treatment of the aforementioned combination. The experiments of NSCLC BM tumor animal models demonstrated that the combination enhanced the therapeutic effects and increased the intracranial accumulation of aumolertinib; the combination can inhibit cell proliferation and survival, delay the repair of DNA damage, and increase the rates of cell apoptosis and aumolertinib abrogated G2/M phase arrest, which the IR induced; the clinical study verified that the combination demonstrated better patient benefits. In conclusion, our study demonstrated that combining aumolertinib and IR has promising anti-tumor effects in EGFR-mutant NSCLC and that this combined treatment modality may be employed as a potential therapeutic strategy for EGFR-mutant NSCLC BM patients clinically.

Galectin-9 blockade synergizes with ATM inhibition to induce potent anti-tumor immunity

Although current cancer immunotherapies that target PD-1/PD-L1 immune checkpoint to reinvigorate exhausted T cells have achieved impressive clinical outcomes, only a small proportion of patients respond. New therapeutic targets are therefore needed to be identified to further unleash the anti-tumor potential of T cells and benefit more patients. Galectin-9 (Gal-9), initially identified as a ligand for TIM-3 to induce T cell death, acts as an immunosuppressive regulator in the tumor microenvironment (TME) but its potential as a therapeutic target remains largely elusive. Here we show that antibody neutralization of Gal-9, in combination with inhibition of Ataxia telangiectasia mutated (ATM), a kinase essential for DNA damage response (DDR), is a promising modality for cancer immunotherapy. Genetic depletion of ATM in tumors markedly potentiated anti-Gal-9 therapy in a syngeneic mouse model. Mechanistically, ATM inhibition greatly upregulated Gal-9 expression and secretion in a variety of human and murine tumor cells via the cGAS-STING-interferon β (IFNβ) innate immune pathway. Combination of Gal-9 inhibition with AZD1390, a selective ATM inhibitor currently evaluated in clinical trials, significantly suppressed tumor growth and prolonged survival in multiple syngeneic mouse models, including the poorly-immunogenic LLC lung tumors that do not respond to PD-1/PD-L1 blockade, concomitant with increased T cell infiltration. These results reveal Gal-9 induction via STING/IFNβ signaling as an important mechanism mediating tumor immune escape that could be targeted for cancer immunotherapies, and unveil a novel anti-Gal-9-based combination strategy for cancer immunotherapies in a wide variety of malignancies, including those resistant to PD-1/PD-L1 blockade.

Dual-responsive nanoparticles loading bevacizumab and gefitinib for molecular targeted therapy against non-small cell lung cancer

The combination of vascular endothelial growth factor (VEGF) inhibitors and tyrosine kinase inhibitors (TKIs) is newly available for molecular targeted therapy against non-small cell lung cancer (NSCLC) in clinic. However, the therapeutic benefits remain unsatisfying due to the poor drug delivery to targets of interest. In this study, we developed bevacizumab-coated gefitinib-loaded nanoparticles (BCGN) with dual-responsive drug release for inhibiting tumor angiogenesis and phosphorylation of epidermal growth factor receptor (EGFR). Through an exogenous corona strategy, bevacizumab is easily coated on gefitinib-loaded nanoparticles via electrostatic interaction. After intravenous injection, BCGN are efficiently accumulated in NSCLC tumors as confirmed by dual-model imaging. Bevacizumab is released from BCGN upon oxidation in tumor microenvironment, whereas gefitinib is released after being internalized by tumor cells and disassembled in reduction cytoplasm. The dual-responsive release of bevacizumab and gefitinib significantly inhibits tumor growth in both A549 and HCC827 human NSCLC models. Our approach provides a promising strategy to improve combinational molecular targeted therapy of NSCLC with precisely controlled drug release.

Targeting the DNA Damage Response Machinery for Lung Cancer Treatment

Lung cancer is considered the most commonly diagnosed cancer and one of the leading causes of death globally. Despite the responses from small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) patients to conventional chemo- and radiotherapies, the current outcomes are not satisfactory. Recently, novel advances in DNA sequencing technologies have started to take off which have provided promising tools for studying different tumors for systematic mutation discovery. To date, a limited number of DDR inhibition trials have been conducted for the treatment of SCLC and NSCLC patients. However, strategies to test different DDR inhibitor combinations or to target multiple pathways are yet to be explored. With the various biomarkers that have either been recently discovered or are the subject of ongoing investigations, it is hoped that future trials would be designed to allow for studying targeted treatments in a biomarker-enriched population, which is defensible for the improvement of prognosis for SCLC and NSCLC patients. This review article sheds light on the different DNA repair pathways and some of the inhibitors targeting the proteins involved in the DNA damage response (DDR) machinery, such as ataxia telangiectasia and Rad3-related protein (ATR), DNA-dependent protein kinase (DNA-PK), and poly-ADP-ribose polymerase (PARP). In addition, the current status of DDR inhibitors in clinical settings and future perspectives are discussed.

DNA Damage Response in Cancer Therapy and Resistance: Challenges and Opportunities

Resistance to chemo- and radiotherapy is a common event among cancer patients and a reason why new cancer therapies and therapeutic strategies need to be in continuous investigation and development. DNA damage response (DDR) comprises several pathways that eliminate DNA damage to maintain genomic stability and integrity, but different types of cancers are associated with DDR machinery defects. Many improvements have been made in recent years, providing several drugs and therapeutic strategies for cancer patients, including those targeting the DDR pathways. Currently, poly (ADP-ribose) polymerase inhibitors (PARP inhibitors) are the DDR inhibitors (DDRi) approved for several cancers, including breast, ovarian, pancreatic, and prostate cancer. However, PARPi resistance is a growing issue in clinical settings that increases disease relapse and aggravate patients' prognosis. Additionally, resistance to other DDRi is also being found and investigated. The resistance mechanisms to DDRi include reversion mutations, epigenetic modification, stabilization of the replication fork, and increased drug efflux. This review highlights the DDR pathways in cancer therapy, its role in the resistance to conventional treatments, and its exploitation for anticancer treatment. Biomarkers of treatment response, combination strategies with other anticancer agents, resistance mechanisms, and liabilities of treatment with DDR inhibitors are also discussed.

An mTOR and DNA-PK dual inhibitor CC-115 hinders non-small cell lung cancer cell growth

Molecularly-targeted agents are still urgently needed for better non-small cell lung cancer (NSCLC) therapy. CC-115 is a potent DNA-dependent protein kinase (DNA-PK) and mammalian target of rapamycin (mTOR) dual blocker. We evaluated its activity in different human NSCLC cells. In various primary human NSCLC cells and A549 cells, CC-115 potently inhibited viability, cell proliferation, cell cycle progression, and hindered cell migration/invasion. Apoptosis was provoked in CC-115-stimulated NSCLC cells. The dual inhibitor, however, was unable to induce significant cytotoxic and pro-apoptotic activity in the lung epithelial cells. In primary NSCLC cells, CC-115 blocked activation of mTORC1/2 and DNA-PK. Yet, CC-115-induced primary NSCLC cell death was more potent than combined inhibition of DNA-PK plus mTOR. Further studies found that CC-115 provoked robust oxidative injury in primary NSCLC cells, which appeared independent of mTOR-DNA-PK dual blockage. In vivo studies showed that CC-115 oral administration in nude mice remarkably suppressed primary NSCLC cell xenograft growth. In CC-115-treated NSCLC xenograft tissues, mTOR-DNA-PK dual inhibition and oxidative injury were detected. Together, CC-115 potently inhibits NSCLC cell growth.

Targeted and systemic insights into the crosstalk between DNA-dependent protein kinase catalytic subunit and receptors of estrogen, progesterone and epidermal growth factor in the context of cancer

DNA-dependent protein kinase catalytic subunit (DNA-PKcs) has emerged as a regulator of carcinogenesis. Increased expression of DNA-PKcs correlates with metastatic cancers. Here we review recently reported crosstalk of DNA-PKcs with estrogen (ER), progesterone (PR) and epidermal growth factor (EGFR) receptors. The reports show an extensive network of functional and direct interactions. Targeted studies focused on specific molecular mechanisms, and a systems biology network analysis shows unbiasedly engagement of various cellular functions. Feedforward regulation between expression and activities of DNA-PKcs and ER, DNA-PKcs-dependent phosphorylation of PR and an impact on PR-dependent transcription, and DNA-PKcs-promoted EGFR-dependent aggressiveness and metastases are examples of the results of targeted studies. Systems biology approach extracted many more genes and proteins engaged by DNA-PKcs in interaction with ER, PR, and EGFR. Examples are such regulators and predictors of breast tumorigenesis as BRCA1, TP53, and 18 genes of the MammaPrint signature. Reviewed here data suggest that the diagnostic value of DNA-PKcs in the context of ER, PR and EGFR signaling is defined by a network signature rather than by single markers. This review summarizes mechanisms of DNA-PKcs interaction with ER, PR, and EGFR, highlights tumor suppressors and oncogenes engaged by DNA-PKcs, and emphasizes the importance of diagnostic network-based signatures.