EPHA2 Interacts with DNA-PKcs in Cell Nucleus and Controls Ionizing Radiation Responses in Non-Small Cell Lung Cancer Cells

Targeting EphA2: a promising strategy to overcome chemoresistance and drug resistance in cancer

Erythropoietin-producing hepatocellular A2 (EphA2) is a vital member of the Eph tyrosine kinase receptor family and has been associated with developmental processes. However, it is often overexpressed in tumors and correlates with cancer progression and worse prognosis due to the activation of its noncanonical signaling pathway. Throughout cancer treatment, the emergence of drug-resistant tumor cells is relatively common. Since the early 2000s, researchers have focused on understanding the role of EphA2 in promoting drug resistance in different types of cancer, as well as finding efficient and secure EphA2 inhibitors. In this review, the current knowledge regarding induced resistance by EphA2 in cancer treatment is summarized, and the types of cancer that lead to the most cancer-related deaths are highlighted. Some EphA2 inhibitors were also investigated. Regardless of whether the cancer treatment has reached a drug-resistance stage in EphA2-overexpressing tumors, once EphA2 is involved in cancer progression and aggressiveness, targeting EphA2 is a promising therapeutic strategy, especially in combination with other target-drugs for synergistic effect. For that reason, monoclonal antibodies against EphA2 and inhibitors of this receptor should be investigated for efficacy and drug toxicity.

Eph receptors and ephrins in cancer progression

Evidence implicating Eph receptor tyrosine kinases and their ephrin ligands (that together make up the 'Eph system') in cancer development and progression has been accumulating since the discovery of the first Eph receptor approximately 35 years ago. Advances in the past decade and a half have considerably increased the understanding of Eph receptor-ephrin signalling mechanisms in cancer and have uncovered intriguing new roles in cancer progression and drug resistance. This Review focuses mainly on these more recent developments. I provide an update on the different mechanisms of Eph receptor-ephrin-mediated cell-cell communication and cell autonomous signalling, as well as on the interplay of the Eph system with other signalling systems. I further discuss recent advances in elucidating how the Eph system controls tumour expansion, invasiveness and metastasis, supports cancer stem cells, and drives therapy resistance. In addition to functioning within cancer cells, the Eph system also mediates the reciprocal communication between cancer cells and cells of the tumour microenvironment. The involvement of the Eph system in tumour angiogenesis is well established, but recent findings also demonstrate roles in immune cells, cancer-associated fibroblasts and the extracellular matrix. Lastly, I discuss strategies under evaluation for therapeutic targeting of Eph receptors-ephrins in cancer and conclude with an outlook on promising future research directions.

Immunogenic cell death after combined treatment with radiation and ATR inhibitors is dually regulated by apoptotic caspases

Introduction

Inhibitors of the ATR kinase act as radiosensitizers through abrogating the G2 checkpoint and reducing DNA repair. Recent studies suggest that ATR inhibitors can also increase radiation-induced antitumor immunity, but the underlying immunomodulating mechanisms remain poorly understood. Moreover, it is poorly known how such immune effects relate to different death pathways such as caspase-dependent apoptosis. Here we address whether ATR inhibition in combination with irradiation may increase the presentation of hallmark factors of immunogenic cell death (ICD), and to what extent caspase activation regulates this response.

Methods

Human lung cancer and osteosarcoma cell lines (SW900, H1975, H460, U2OS) were treated with X-rays and ATR inhibitors (VE822; AZD6738) in the absence and presence of a pan-caspase inhibitor. The ICD hallmarks HMGB1 release, ATP secretion and calreticulin surface-presentation were assessed by immunoblotting of growth medium, the CellTiter-Glo assay and an optimized live-cell flow cytometry assay, respectively. To obtain accurate measurement of small differences in the calreticulin signal by flow cytometry, we included normalization to a barcoded control sample.

Results

Extracellular release of HMGB1 was increased in all the cell lines at 72 hours after the combined treatment with radiation and ATR inhibitors, relative to mock treatment or cells treated with radiation alone. The HMGB1 release correlated largely - but not strictly - with loss of plasma membrane integrity, and was suppressed by addition of the caspase inhibitor. However, one cell line showed HMGB1 release despite caspase inhibition, and in this cell line caspase inhibition induced pMLKL, a marker for necroptosis. ATP secretion occurred already at 48 hours after the co-treatment and did clearly not correlate with loss of plasma membrane integrity. Addition of pan-caspase inhibition further increased the ATP secretion. Surface-presentation of calreticulin was increased at 24-72 hours after irradiation, but not further increased by either ATR or caspase inhibition.

Conclusion

These results show that ATR inhibition can increase the presentation of two out of three ICD hallmark factors from irradiated human cancer cells. Moreover, caspase activation distinctly affects each of the hallmark factors, and therefore likely plays a dual role in tumor immunogenicity by promoting both immunostimulatory and -suppressive effects.

RSK inhibitors as potential anticancer agents: Discovery, optimization, and challenges

Ribosomal S6 kinase (RSK) family is a group of serine/threonine kinases, including four isoforms (RSK1/2/3/4). As a downstream effector of the Ras-mitogen-activated protein kinase (Ras-MAPK) pathway, RSK participates in many physiological activities such as cell growth, proliferation, and migration, and is intimately involved in tumor occurrence and development. As a result, it is recognized as a potential target for anti-cancer and anti-resistance therapies. There have been several RSK inhibitors discovered or designed in recent decades, but only two have entered clinical trials. Low specificity, low selectivity, and poor pharmacokinetic properties in vivo limit their clinical translation. Published studies performed structure optimization by increasing interaction with RSK, avoiding hydrolysis of pharmacophores, eliminating chirality, adapting to binding site shape, and becoming prodrugs. Besides enhancing efficacy, the focus of further design will move towards selectivity since there are functional differences among RSK isoforms. This review summarized the types of cancers associated with RSK, along with the structural characteristics and optimization process of the reported RSK inhibitors. Furthermore, we addressed the importance of RSK inhibitors' selectivity and discussed future drug development directions. This review is expected to shed light on the emergence of RSK inhibitors with high potency, specificity, and selectivity.

Review: Mechanisms and perspective treatment of radioresistance in non-small cell lung cancer

Radiotherapy is the major treatment of non-small cell lung cancer (NSCLC). The radioresistance and toxicity are the main obstacles that leading to therapeutic failure and poor prognosis. Oncogenic mutation, cancer stem cells (CSCs), tumor hypoxia, DNA damage repair, epithelial-mesenchymal transition (EMT), and tumor microenvironment (TME) may dominate the occurrence of radioresistance at different stages of radiotherapy. Chemotherapy drugs, targeted drugs, and immune checkpoint inhibitors are combined with radiotherapy to treat NSCLC to improve the efficacy. This article reviews the potential mechanism of radioresistance in NSCLC, and discusses the current drug research to overcome radioresistance and the advantages of Traditional Chinese medicine (TCM) in improving the efficacy and reducing the toxicity of radiotherapy.

P-Y/G@NHs sensitizes non-small cell lung cancer cells to radiotherapy via blockage of the PI3K/AKT signaling pathway

Radioresistance represents a common phenomenon found in cancer treatment. Herein, the current study sought to evaluate the effects of a nanodrug delivery system of YSAYPDSVPMMS (YSA) peptide-modified gold nanoparticles-dextran-based hydrogel loaded with paclitaxel-succinic anhydride (P-Y/G@NHs) on non-small cell lung cancer (NSCLC) cell radiosensitivity. Firstly, utilizing the coupling reaction and layer-by-layer assembly technique, P-Y/G@NHs was prepared. The therapeutic effects of the P-Y/G@NHs in NSCLC cells in relation to the PI3K/AKT signaling pathway were examined by assessing the colony formation, apoptosis, and reactive oxygen species (ROS) generation of A549 cells under 10 Gy X-rays irradiation. Moreover, A549 tumor-bearing mice were generated to further validate the therapeutic effect in vivo. We confirmed the successful conjugation of the nanocomposite. Under 10 Gy X-rays irradiation, P-Y/G@NHs reduced the number of colonies of A549 cells, while inducing both cell apoptosis and ROS production. Moreover, P-Y/G@NHs enhanced the radiosensitivity of A549 cells by inhibiting the PI3K/AKT signaling pathway. In vivo fluorescence experiments validated that P-Y/G@NHs effectively-targeted and accumulated at the tumor site in nude mice, thus augmenting the radiosensitivity of tumors without significant immune toxicity or side effects. Conclusively, our findings highlighted that P-Y/G@NHs significantly enhanced the radiosensitivity of NSCLC cells by repressing the PI3K/AKT signaling pathway.

May EPH/Ephrin Targeting Revolutionize Lung Cancer Treatment?

Lung cancer (LC) is the leading cause of cancer death in the United States. Erythropoietin-producing hepatocellular receptors (EPHs) comprise the largest receptor tyrosine kinases (RTKs) family in mammals. EPHs along with their ligands, EPH-family receptor-interacting proteins (ephrins), have been found to be either up- or downregulated in LC cells, hence exhibiting a defining role in LC carcinogenesis and tumor progression. In their capacity as membrane-bound molecules, EPHs/ephrins may represent feasible targets in the context of precision cancer treatment. In order to investigate available therapeutics targeting the EPH/ephrin system in LC, a literature review was conducted, using the MEDLINE, LIVIVO, and Google Scholar databases. EPHA2 is the most well-studied EPH/ephrin target in LC treatment. The targeting of EPHA2, EPHA3, EPHA5, EPHA7, EPHB4, EPHB6, ephrin-A1, ephrin-A2, ephrin-B2, and ephrin-B3 in LC cells or xenograft models not only directly correlates with a profound LC suppression but also enriches the effects of well-established therapeutic regimens. However, the sole clinical trial incorporating a NSCLC patient could not describe objective anti-cancer effects after anti-EPHA2 antibody administration. Collectively, EPHs/ephrins seem to represent promising treatment targets in LC. However, large clinical trials still need to be performed, with a view to examining the effects of EPH/ephrin targeting in the clinical setting.

Investigation on the incidence and risk factors of lung cancer among Chinese hospital employees

Objective

In recent years, the lung cancer incidence has grown and the population is younger. We intend to find out the true detection rate of pulmonary nodules and the incidence of lung cancer in the population and search for the risk factors.

Method

Hospital employees ≥40 years old who underwent low‐dose computed tomography (CT) lung cancer screening from January 2019 to March 2022 were selected to record CT‐imaging characteristics, pathology, staging, and questionnaires to investigate past history, smoking history, diet, mental health, etc. PM2.5 and radiation intake in radiation‐related occupation received monitoring in hospital.

Result

The detection rate of suspicious pulmonary nodules was 9.1% (233/2552), and the incidence rate of lung cancer (including adenocarcinoma in situ) was 4.0% (103/2552). Morbidity among doctors, nurses, technicians, administers, and logistics was no difference (p = 0.184), but higher in women than in men (4.7% vs 2.4% p = 0.002). The invasiveness increased with age and CT density of nodules (p = 0.018). The relationship between lung cancer morbidity and PM2.5 was not clear (p = 0.543); and no lung cancer has been found in employees related ionizing radiation.

Conclusion

The high screening rate has brought about a high incidence of lung cancer. At present, the risk factor analysis of lung cancer based on small samples cannot find the direct cause. Most of the ground glass opacity (GGO)s detected by LDCT screening are indolent, but there are also rapidly progressive lung cancer. A predictive model to identify active and indolent GGO is necessary.