Downregulation of TRIB3 enhances the sensitivity of lung cancer cells to amino acid deprivation by suppressing AKT activation.

Tribbles pseudokinase 3 (TRIB3), a member of the mammalian Tribbles family, is implicated in multiple biological processes. This study aimed to investigate the biological functions of TRIB3 in lung cancer and its effect on amino acid-deprived lung cancer cells. TRIB3 mRNA expression was elevated in lung cancer tissues and cell lines compared to normal lung tissues and cells. TRIB3 knockdown markedly reduced the viability and proliferation of H1299 lung cancer cells. Deprivation of amino acids, particularly arginine, glutamine, lysine, or methionine, strongly increased TRIB3 expression via ATF4 activation in H1299 lung cancer cells. Knockdown of TRIB3 led to transcriptional downregulation of ATF4 and reduced AKT activation induced by amino acid deprivation, ultimately increasing the sensitivity of H1299 lung cancer cells to amino acid deprivation. Additionally, TRIB3 knockdown enhanced the sensitivity of H1299 cells to V-9302, a competitive antagonist of transmembrane glutamine flux. These results suggest that TRIB3 is a pro-survival regulator of cell viability in amino acid-deficient tumor microenvironments and a promising therapeutic target for lung cancer treatment.

The combination of osimertinib with Raf inhibitor overcomes osimertinib resistance induced by KRAS amplification in EGFR-mutated lung cancer cells.

Osimertinib is a third-generation epidermal growth factor receptor (EGFR)1 tyrosine kinase inhibitor (TKI) approved for the treatment of EGFR-positive patients exhibiting a T790 M resistance mutation after treatment with an earlier generation of EGFR TKIs. However, resistance to osimertinib inevitably develops despite its efficacy, and the resistance mechanisms are complex and not fully understood. We established cell lines with acquired resistance to osimertinib from gefitinib- or erlotinib-resistant NSCLC cells using a dose-escalation method, and found that they had upregulated levels of phosphorylated ERK1/2. Targeted next-generation sequencing of 143 genes was performed, and interestingly, amplification of KRAS was observed in osimertinib-resistant cells. Transfection of siRNA against the KRAS gene notably reduced the activation of ERK1/2 and AKT and significantly enhanced the induction of apoptosis by osimertinib treatment in osimertinib-resistant cells. LY3009120, a RAF inhibitor, showed a significant synergistic effect with osimertinib on apoptotic cell death in osimertinib-resistant cells. Combined treatment with osimertinib and LY3009120 also demonstrated remarkable synergistic anti-tumor activity in mouse xenografts of these cells. This could be a potential new treatment option for KRAS amplification-induced osimertinib failure.

The Combination of Trametinib, a MEK Inhibitor, and Temsirolimus, an mTOR Inhibitor, Radiosensitizes Lung Cancer Cells.

BACKGROUND/AIM: We evaluated the radiosensitizing effect of the combination treatment of trametinib, a MEK inhibitor, and temsirolimus, an mTOR inhibitor, on non-small-cell lung carcinoma (NSCLC) cells. MATERIALS AND METHODS: The effects of combining trametinib and temsirolimus with radiation in NSCLC cell lines were evaluated using clonogenic survival and apoptosis assays. DNA double-strand breaks and cell cycle distribution were analyzed using flow cytometry. Tumor volume was measured to determine the radiosensitivity in lung cancer xenograft models. RESULTS: Exposure of lung cancer cells to a combination of trametinib and temsirolimus reduced clonogenic survival and promoted radiation-induced apoptosis. Combined inhibition of MEK and mTOR induced prolonged expression of γH2AX after irradiation and resulted in prolonged G2/M cell cycle arrest after irradiation in A549 cells. In vivo studies revealed that co-administration of the drugs sensitizes lung cancer xenografts to radiotherapy. CONCLUSION: The combination of trametinib and temsirolimus can enhance lung cancer radiosensitivity in vitro and in vivo.

Real-world outcomes of anti-PD1 antibodies in platinum-refractory, PD-L1-positive recurrent and/or metastatic non-small cell lung cancer, and its potential practical predictors: first report from Korean Cancer Study Group LU19-05.

PURPOSE: Although immune-checkpoint inhibitors have become a new therapeutic option for recurrent/metastatic non-small cell lung cancers (R/M-NSCLC), its clinical benefit in the real-world is still unclear. METHODS: We investigated 1181 Korean patients with programmed death-1 ligand 1 (PD-L1)-positive [tumor proportion score (TPS) ≥ 10% by the SP263 assay or ≥ 50% by the 22C3 assay] R/M-NSCLC treated with pembrolizumab or nivolumab after failure of platinum-based chemotherapy. RESULTS: The median age was 67 years, 13% of patients had ECOG-PS ≥ 2, and 27% were never-smokers. Adenocarcinoma was predominant (61%) and 18.1% harbored an EGFR activating mutation or ALK rearrangement. Pembrolizumab and nivolumab were administered to 51.3% and 48.7, respectively, and 42% received them beyond the third-line chemotherapy. Objective response rate (ORR) was 28.6%. Pembrolizumab group showed numerically higher ORR (30.7%) than the nivolumab group (26.4%), but it was comparable with that of the nivolumab group having PD-L1 TPS ≥ 50% (32.4%). Median progression-free survival (PFS) and overall survival (OS) were 2.9 (95% CI 0-27.9) and 10.7 months (95% CI 0-28.2), respectively. In multivariable analysis, concordance of TPS ≥ 50% in both PD-L1 assays and the development of immune-related adverse events (irAEs) were two significant predictors of better ORR, PFS, and OS. EGFR mutation could also predict significantly worse OS outcomes. CONCLUSION: The real-world benefit of later-line anti-PD1 antibodies was comparable to clinical trials in patients with R/M-NSCLC, although patients generally were more heavily pretreated and had poorer ECOG-PS. Concordantly high PD-L1 TPS ≥ 50% and development of irAE could independently predict better treatment outcomes, while EGFR mutation negatively affected OS.

Association of EGFR mutations in second primary lung cancer and HER2 expression in breast cancer survivors.

BACKGROUND: The incidence of second primary lung cancer (SPLC) is increasing with longer survival rates from breast cancer. Despite of studies to suggest the mutual exclusivity of epidermal growth factor receptor (EGFR) and human epidermal growth receptor 2 (HER2) in several cancers, the effect of HER2 expression in breast cancer on EGFR mutations in SPLC is unclear. Therefore, this study aimed to determine the association between HER2 expression and EGFR mutations. METHODS: We conducted a retrospective cohort study of breast cancer survivors diagnosed with SPLC after breast cancer treatment between 1997 and 2018. We investigated the association between HER2 expression in breast cancer and EGFR mutations in SPLC, specifically focusing on negative correlations by using logistic regression analysis. RESULTS: EGFR mutations in SPLC were detected in 19 of 38 patients. Analysis for HER2 revealed a statistically significant difference in the proportion of EGFR mutations between patients with SPLC and previous HER2 positive breast cancer (43.5%) and those with SPLC and previous HER2 negative breast cancer (90.0%; P=0.021). The ratio of EGFR mutations decreased with the degree of HER2 expression in patients with previous breast cancer (90.0%: for no HER2 expression, 62.5% for HER2 1+, 0.0% for HER2 2+, and 41.7% for HER2 3+; P=0.018). Multivariate logistic analyses revealed that EGFR mutations in SPLC were significantly associated with age [odds ratio (OR): 1.11, 95% confidence interval (CI): 1.01-0.23, P=0.039] and HER2 positive status (OR: 0.04, 95% CI: 0.01-0.56, P=0.017). CONCLUSIONS: This study suggests that the frequency of EGFR mutations in SPLC may be associated with low HER2 expression in previous breast cancer.

Radiation Induces Autophagy via Histone H4 Lysine 20 Trimethylation in Non-small Cell Lung Cancer Cells.

BACKGROUND/AIM: Radiotherapy-induced autophagy affects radiation-sensitivity and radiotherapy efficacy. Histone modifications also occur during radiotherapy. This study assessed radiotherapy effects on histone modification and autophagy in non-small cell lung cancer (NSCLC) cells. MATERIALS AND METHODS: NSCLC cells were subjected to γ-irradiation. Autophagy was detected using western blotting and acridine orange staining. Radiation effect on cell growth was evaluated by clonogenic assay. Histone modifications were assessed by western blotting. Next generation sequencings (NGSs) were conducted to identify histone modification target genes. RESULTS: Radio-protective autophagy and histone H4 lysine 20 trimethylation (H4K20me3) were up-regulated after irradiation. By NGSs, genes that are differentially expressed upon irradiation were identified, including the candidate H4K20me3 target gene GABARAPL1. Furthermore, we showed that GABARAPL1 is essential for the radiation-induced autophagy. CONCLUSION: Our findings revealed the regulatory axis of radiation-induced H4K20me3-GABARAPL1 in radio-protective autophagy. Modulation of this axis may be a new strategy to enhance radiotherapy efficacy in NSCLC.

Real-world use of osimertinib in non-small cell lung cancer: ASTRIS study Korean subgroup analysis.

Objective: ASTRIS is a large real-world, open-label, multinational clinical study of osimertinib in patients with epidermal growth factor receptor (EGFR) T790M mutation-positive advanced non-small cell lung cancer (NSCLC) who have previously received a tyrosine kinase inhibitor (TKI). We report data from the Korean ASTRIS subgroup.Methods: Adult patients with locally advanced or metastatic NSCLC with a confirmed T790M mutation, WHO performance status of 0-2 and prior EGFR-TKI therapy, received osimertinib 80 mg once daily. Efficacy outcomes were overall survival (OS), investigator-assessed response rate (RR) and progression-free survival (PFS), and time to treatment discontinuation (TTD).Results: At data cut-off (20 October 2017), 466 Korean patients were enrolled. Baseline EGFR molecular testing was mainly performed on biopsied tissue (75.1%). Baseline mutations co-occurring with T790M included exon 19 deletions (60.7%) and L858R (32.8%). 1-year OS was 82.7% (OS data not matured at data cut-off). Overall, RR was 71.0%, median PFS was 12.4 months and median TTD was 15.0 months. In patients with/without CNS metastases, RR was 68.0% and 79.6%, respectively; median PFS, 10.8 and 11.0 months, respectively; and median TTD, 11.2 and 14.7 months, respectively. Overall, 31.1% of patients experienced ≥1 adverse event (AE), leading to dose modification (12.0%), discontinuation (5.2%) or death (2.8%). Serious AEs (24.9%) included pulmonary embolism (1.7%), pleural effusion (1.7%), and pneumonia (1.5%).Conclusion: In this real-world subgroup analysis of Korean patients in the ASTRIS study, osimertinib demonstrated comparable clinical efficacy to that attained in the global ASTRIS study and other clinical trials, with no new safety concerns.

Factors that Predict Clinical Benefit of EGFR TKI Therapy in Patients with EGFR Wild-Type Lung Adenocarcinoma.

BACKGROUND: Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancers have emerged as key predictive biomarkers in EGFR tyrosine kinase inhibitor (TKI) treatment. However, a few patients with wild-type EGFR also respond to EGFR TKIs. This study investigated the factors predicting successful EGFR TKI treatment in lung adenocarcinoma patients with wild-type EGFR. METHODS: We examined 66 patients diagnosed with lung adenocarcinoma carrying wide-type EGFR who were treated with EGFR TKIs. The EGFR gene copy number was assessed by silver in situ hybridization (SISH). We evaluated the clinical factors and EGFR gene copy numbers that are associated with a favorable clinical response to EGFR TKIs. RESULTS: The objective response rate was 12.1%, while the disease control rate was 40.9%. EGFR SISH analysis was feasible in 23 cases. Twelve patients tested EGFR SISH-positive, and 11 were EGFR SISH-negative, with no significant difference in tumor response and survival between EGFR SISH-positive and -negative patients. The overall median progression-free survival (PFS) and overall survival (OS) of 66 patients were 2.1 months and 9.7 months, respectively. Female sex and Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-1 were independent predictors of PFS. ECOG PS 0-1 and a low tumor burden of extrathoracic metastasis were independent predictors of good OS. CONCLUSION: Factors such as good PS, female sex, and low tumor burden may predict favorable outcomes following EGFR TKI therapy in patients with EGFR wild-type lung adenocarcinoma. However, EGFR gene copy number was not predictive of survival.

Anti-tumor effect of CDK inhibitors on CDKN2A-defective squamous cell lung cancer cells.

BACKGROUND: Squamous cell lung cancer (SqCLC) is a distinct histologic subtype of non-small cell lung cancer (NSCLC). Although the discovery of driver mutations and their targeted drugs has remarkably improved the treatment outcomes for lung adenocarcinoma, currently no such molecular target is clinically available for SqCLC. The CDKN2A locus at 9p21 encodes two alternatively spliced proteins, p16INK4a (p16) and p14ARF (p14), which function as cell cycle inhibitors. The Cancer Genome Atlas (TCGA) project revealed that CDKN2A is inactivated in 72% of SqCLC cases. In addition, it was found that CDKN2A mutations are significantly more common in SqCLC than in adenocarcinoma. Down-regulation of p16 and p14 by CDKN2A gene inactivation leads to activation of cyclin-dependent kinases (CDKs), thereby permitting constitutive phosphorylation of Rb and subsequent cell cycle progression. Here, we hypothesized that CDK inhibition may serve as an attractive strategy for the treatment of CDKN2A-defective SqCLC. METHODS: We investigated whether the CDK inhibitors flavopiridol and dinaciclib may exhibit antitumor activity in CDKN2A-defective SqCLC cells compared to control cells. The cytotoxic effect of the CDK inhibitors was evaluated using cell viability assays, and the induction of apoptosis was assessed using TUNEL assays and Western blot analyses. Finally, anti-tumor effects of the CDK inhibitors on xenografted cells were investigated in vivo. RESULTS: We found that flavopiridol and dinaciclib induced cytotoxicity by enhancing apoptosis in CDKN2A-defective SqCLC cells, and that epithelial to mesenchymal transition (EMT) decreased and autophagy increased during this process. In addition, we found that autophagy had a cytoprotective role. CONCLUSION: Our data suggest a potential role of CDK inhibitors in managing CDKN2A-defective SqCLC.

Altered expression of cellular proliferation, apoptosis and the cell cycle-related genes in lung cancer cells with acquired resistance to EGFR tyrosine kinase inhibitors.

Non-small cell lung cancers harboring somatic gain-of-function mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain respond well to treatment with EGFR tyrosine kinase inhibitors (TKIs) including gefitinib and erlotinib. However, all patients who experience a marked improvement with these drugs eventually develop disease progression due to the acquisition of drug resistance. Approximately half of the cases with acquired resistance to EGFR TKIs can be accounted for by a second-site mutation in exon 20 of the EGFR kinase domain (T790M). However, the changes of gene expression involved in EGFR TKI resistance due to the T790M mutation remain poorly defined. The present study established lung cancer cell lines that were resistant to gefitinib or erlotinib, and these cell lines were verified to contain the EGFR T790M mutation. The differential expression of genes associated with acquired resistance was verified in the present study by mRNA microarray analysis. Among the genes whose expression was significantly altered, genes whose expression was altered in gefitinib- and erlotinib-resistant cells were focused on. Notably, a total of 1,617 genes were identified as being differentially expressed in gefitinib- and erlotinib-resistant cells. Indeed, Gene ontology analysis revealed altered expression of genes involved in the regulation of cellular proliferation, apoptosis, and the cell cycle in EGFR TKI-resistant cells. The present results demonstrate distinctive gene expression patterns of EGFR TKI-resistant lung cancer cells with the EGFR T790M mutation. The present study can provide key insights into gene expression profiles involved in conferring resistance to EGFR TKI therapy in lung cancer cells.

Sex-specific incidence of EGFR mutation and its association with age and obesity in lung adenocarcinomas: a retrospective analysis.

PURPOSE: Age and obesity are well-known risk factors for various cancers, but the potential roles of age and obesity in lung cancer, especially in those with activating EGFR mutations, have not been thoroughly evaluated. The aim of this retrospective study is to evaluate the associations between the sex-specific incidence of EGFR mutations and age and obesity. METHODS: We conducted a retrospective study based on the data from 1378 lung adenocarcinoma cases. The degree of obesity was categorized by body mass index (BMI). The associations between EGFR mutational status and clinical factors, including stage, smoking history, age group (≤45 years, 46-55, 56-65 and >65), and BMI group (<18.5 kg/m2, 18.5-22.9, 23.0-24.9 and ≥25.0) were analyzed using logistic regression models for each sex. RESULTS: In men, the incidence of EGFR mutation was inversely associated with age (adjusted odds ratio [OR] for age group = 0.76, p-trend = 0.003) and positively associated with obesity (adjusted OR for BMI group = 1.23, p-trend = 0.04). In contrast, in women, the incidence of EGFR mutation was positively associated with age (adjusted OR for age group = 1.19, p-trend = 0.02). However, the incidence of EGFR mutation was not statistically associated with obesity (adjusted OR for BMI group = 1.03, p-trend = 0.76). CONCLUSIONS: Our data suggests that age and obesity may contribute to the sex-specific incidence of EGFR mutation in lung adenocarcinoma in different manners.

Fhit, a tumor suppressor protein, induces autophagy via 14-3-3τ in non-small cell lung cancer cells.

Inactivation of the fragile histidine triad (Fhit) gene has been reported in the majority of human cancers, particularly in lung cancer. The role of Fhit as a tumor suppressor gene has been well documented, and restoration of Fhit expression suppresses tumorigenicity in tumor cell lines and in mouse models by inducing apoptosis and inhibiting proliferation of tumor cells. Autophagy is a catabolic pathway, whereby cytoplasmic proteins and organelles are sequestered in vacuoles and delivered to lysosomes for degradation and recycling. Although autophagy is necessary for cell survival under stress conditions, recent studies have shown that autophagy can also promote cell death. Due to the fact that both autophagy induction and Fhit expression are commonly associated with nutrient starvation, we hypothesized that Fhit expression may be related to autophagy induction. In the present study, we assessed whether Fhit overexpression by gene transfer induces autophagy in Fhit-deficient non-small cell lung cancer (NSCLC) cells. The results of our study indicate that Fhit protein induces autophagy in NSCLC cells, and that this autophagy prevents apoptotic cell death in vivo and in vitro in a 14-3-3τ protein-dependent manner. To the best of our knowledge, this is the first report to describe Fhit-induced autophagy. Suppressing autophagy might be a promising therapeutic option to enhance the efficacy of Fhit gene therapy in NSCLC.

Generation of lung cancer cell lines harboring EGFR T790M mutation by CRISPR/Cas9-mediated genome editing.

Tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib are effective against lung adenocarcinomas harboring epidermal growth factor receptor (EGFR) mutations. However, cancer cells can develop resistance to these agents with prolonged exposure; in over 50% of cases, this is attributable to the EGFR T790M mutation. Moreover, additional resistance mutations can arise with the use of new drugs. Cancer cell lines with specific mutations can enable the study of resistance mechanisms. In this study, we introduced the EGFR T790M mutation into the PC9 human lung cancer cell line-which has a deletion in exon 19 of the EGFR gene-by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas)9-mediated genome editing. EGFR pyrosequencing and peptide nucleic acid clamping revealed that PC9 cells with EGFR T790M generated by CRISPR/Cas 9 had a higher T790M mutation rate than those with the same mutation generated by long-term exposure to gefitinib (PC9-G); moreover, resistance to gefitinib in these clones was higher than that in PC9-G cells. The clones were also highly sensitive to the 3rd-generation EGFR TKI AZD9291, which is cytotoxic to lung cancer cells with EGFR T790M. The CRISPR/Cas9 programmable nuclease system can be used to generate various cancer cell lines with specific mutations that can facilitate studies on resistance mechanisms and drug efficacy.

Association between thyroid cancer and epidermal growth factor receptor mutation in female with nonsmall cell lung cancer.

BACKGROUND: The aim of this study was to investigate the association between epidermal growth factor receptor (EGFR) mutation and thyroid cancer in female patients with nonsmall-cell lung cancer (NSCLC). METHODS: In a retrospective study, we examined 835 female patients who were diagnosed with NSCLC and underwent an EGFR mutation test between June 2003 and August 2013. The associations of EGFR mutation with thyroid cancer and a family history of thyroid cancer were evaluated using logistic regression models. RESULTS: EGFR mutation was found in 378 of 835 patients. In addition to adenocarcinoma (P < 0.001), EGFR mutations were positively associated with a personal history of thyroid cancer (5.8% versus 2.6%; P = 0.020), while showing a trend toward inverse association with a personal history of nonthyroid cancer (5.8% vs. 9.0%; P = 0.086). Likewise, the incidence of EGFR mutations was associated with a family history of thyroid cancer (2.9% vs. 0.9%; P = 0.028), while showing a trend toward inverse association with a family history of nonthyroid cancer (27.8% vs. 33.7%; P = 0.066). Multivariate logistic regression showed that the incidence of EGFR mutations was different in women with thyroid or nonthyroid cancer (P = 0.035) and in women with a family history of thyroid or nonthyroid cancer (P = 0.023). CONCLUSIONS: Our data suggest that thyroid cancer and a family history of thyroid cancer are associated with EGFR-mutated NSCLC in female patients. The differences in the incidence of thyroid cancer and a family history of thyroid cancer by EGFR mutational status provide new insight into pathogenesis of this genetic change.

Superior Efficacy and Selectivity of Novel Small-Molecule Kinase Inhibitors of T790M-Mutant EGFR in Preclinical Models of Lung Cancer.

The clinical utility of approved EGFR small-molecule kinase inhibitors is plagued both by toxicity against wild-type EGFR and by metastatic progression in the central nervous system, a disease sanctuary site. Here, we report the discovery and preclinical efficacy of GNS-1486 and GNS-1481, two novel small-molecule EGFR kinase inhibitors that are selective for T790M-mutant isoforms of EGFR. Both agents were effective in multiple mouse xenograft models of human lung adenocarcinoma (T790M-positive or -negative), exhibiting less activity against wild-type EGFR than existing approved EGFR kinase inhibitors (including osimertinib). In addition, GNS-1486 showed superior potency against intracranial metastasis of EGFR-mutant lung adenocarcinoma. Our results offer a preclinical proof of concept for new EGFR kinase inhibitors with the potential to improve therapeutic index and efficacy against brain metastases in patients. Cancer Res; 77(5); 1200-11. ©2017 AACR.

Epidermal growth factor receptor mutations and brain metastasis in patients with nonadenocarcinoma of the lung.

OBJECTIVE: This study explored the potential association between epidermal growth.factor receptor. (EGFR) mutation status and brain metastasis in patients with nonadenocarcinoma nonsmall cell lung cancer. (NSCLC). PATIENTS AND METHODS: We analyzed clinical data from 286 patients with nonadenocarcinoma NSCLC, who were tested for EGFR mutations and underwent brain magnetic resonance imaging at diagnosis. We examined the relationship between EGFR mutation and brain metastasis at initial presentation. RESULTS: Of the 286 patients, 20 patients (7.0%) had EGFR mutations. EGFR mutations were more frequent in younger patients (11.1% in patients =64 years vs. 3.3% in patients >64 years: P = 0.01), females (21.4% vs. 3.5% in males: P <0.001), never-smokers (25.0% vs. 3.4% in smokers: P < 0.001), and tumors with nonsquamous histology (25.0% vs. 4.1% in squamous histology: P < 0.001). At diagnosis, the frequency of EGFR mutations was significantly different in patients with metastasis to different sites (4.0% [no metastases] vs. 10.4% [extracranial metastases] vs. 40.0% [brain metastases], P < 0.001). The strong association between EGFR mutation and brain metastasis remained significant in multivariate analysis (adjusted odds ratio [OR] = 9.68, 95% confidence interval [CI] =2.32-40.45; P = 0.002). Associations were also found for EGFR mutation status with nonsquamous histology (adjusted OR = 4.46, 95% CI = 1.46-13.56; P = 0.008). CONCLUSION: This study indicates that the likelihood of nonadenocarcinoma patients having EGFR mutant tumors may differ according to brain metastasis and squamous cell histology.

Development of a minipig model for lung injury induced by a single high-dose radiation exposure and evaluation with thoracic computed tomography.

Radiation-induced lung injury (RILI) due to nuclear or radiological exposure remains difficult to treat because of insufficient clinical data. The goal of this study was to establish an appropriate and efficient minipig model and introduce a thoracic computed tomography (CT)-based method to measure the progression of RILI. Göttingen minipigs were allocated to control and irradiation groups. The most obvious changes in the CT images after irradiation were peribronchial opacification, interlobular septal thickening, and lung volume loss. Hounsfield units (HU) in the irradiation group reached a maximum level at 6 weeks and decreased thereafter, but remained higher than those of the control group. Both lung area and cardiac right lateral shift showed significant changes at 22 weeks post irradiation. The white blood cell (WBC) count, a marker of pneumonitis, increased and reached a maximum at 6 weeks in both peripheral blood and bronchial alveolar lavage fluid. Microscopic findings at 22 weeks post irradiation were characterized by widening of the interlobular septum, with dense fibrosis and an increase in the radiation dose-dependent fibrotic score. Our results also showed that WBC counts and microscopic findings were positively correlated with the three CT parameters. In conclusion, the minipig model can provide useful clinical data regarding RILI caused by the adverse effects of high-dose radiotherapy. Peribronchial opacification, interlobular septal thickening, and lung volume loss are three quantifiable CT parameters that can be used as a simple method for monitoring the progression of RILI.

The combination of irreversible EGFR TKIs and SAHA induces apoptosis and autophagy-mediated cell death to overcome acquired resistance in EGFR T790M-mutated lung cancer.

To overcome T790M-mediated acquired resistance of lung cancer cells to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs), second generation TKIs such as BIBW2992 (afatinib) and third generation TKIs including WZ4002 have been developed. However, clinical data on their efficacy in treating T790M mutant tumors are lacking. Histone deacetylase (HDAC) inhibitors have been reported to arrest cell growth and to lead to differentiation and apoptosis of various cancer cells, both in vitro and in vivo. In the present study, we assessed whether the combination of suberoylanilide hydroxamic acid (SAHA, vorinostat), a potent HDAC inhibitor, and BIBW2992 or WZ4002 could overcome EGFR TKI resistance associated with T790M mutation in lung cancer cells. While treatment with BIBW2992 or WZ4002 alone slightly reduced the viability of PC-9G and H1975 cells, which possess T790M mutation, combining them with SAHA resulted in significantly decreased cell viability through the activation of the apoptotic pathway. This combination also enhanced autophagy occurrence and inhibition of autophagy significantly reduced the apoptosis induced by the combination treatment, showing that autophagy is required for the enhanced apoptosis. Caspase-independent autophagic cell death was also induced by the combination treatment with SAHA and either BIBW2992 or WZ4002. Finally, the combined treatment with SAHA and either BIBW2992 or WZ4002 showed an enhanced anti-tumor effect on xenografts of H1975 cells in vivo. In conclusion, the combination of new generation EGFR TKIs and SAHA may be a new strategy to overcome the acquired resistance to EGFR TKIs in T790M mutant lung cancer.

Autophagosome-mediated EGFR down-regulation induced by the CK2 inhibitor enhances the efficacy of EGFR-TKI on EGFR-mutant lung cancer cells with resistance by T790M.

Protein kinase CK2 has diverse functions promoting and maintaining cancer phenotypes. We investigated the effect of CK2 inhibition in lung cancer cells with T790M-mediated resistance to the EGFR-TK inhibitor. Resistant sublines of PC-9 to gefitinib (PC-9/GR) and erlotinib (PC-9/ER) were established by previous study, and T790M secondary mutation was found in both resistant sublines. A decrease of EGFR by siRNA treatment effectively controlled the growth of resistant cells, thus suggesting that they still have EGFR-dependency. CX-4945, a potent and selective CK2 inhibitor, induced autophagy in PC-9/GR and PC-9/ER, and which was supported by the induction of autophagic vacuoles and microtubule-associated protein 1 light chain 3 (LC3) expression, and the increase of punctate fluorescent signals in resistant cells pre-transfected with green fluorescent protein (GFP)-tagged LC3. However, the withdrawal of CX-4945 led to the recovery of cancer cells with autophagy. We found that the induction of autophagy by CX-4945 in both resistant cells was CK2 dependent by using small interfering RNA against CK2. The treatment with CX-4945 alone induced a minimal growth inhibition in resistant cells. However, combined treatment of CX-4945 and EGFR-TKI effectively inhibited cancer-cell proliferation and induced apoptosis. CX-4945 increased the translocation of EGFR from the cell surface into the autophagosome, subsequently leading to the decrease of EGFR while inhibition of autophagy by 3MA or Atg7-targeted siRNA pretreatment reduced the decrease of EGFR by CX-4945. Accordingly, apoptosis by a combination of CX-4945 and EGFR-TKI was suppressed by 3MA or Atg7-targeted siRNA pretreatment, thus suggesting that autophagosome-mediated EGFR down-regulation would have an important role regarding apoptotic cell death by EGFR-TKI. Combined treatment of the CK2 inhibitor and EGFR-TKI may be a promising strategy for overcoming T790M-mediated resistance.

Heat shock protein 70 as a predictive marker for platinum-based adjuvant chemotherapy in patients with resected non-small cell lung cancer.

OBJECTIVES: Although adjuvant platinum-based chemotherapy improves survival in completely resected non-small cell lung cancer (NSCLC), its effect is limited. We evaluated whether the expression of heat shock protein 70 (Hsp70) is associated with clinical outcomes in patients with completely resected NSCLC who were treated with or without adjuvant platinum-based chemotherapy. PATIENTS AND METHODS: Patients who underwent curative resection for NSCLC and diagnosed as stage IIA through IIIA were included. Immunohistochemical staining for Hsp70 was performed on surgical specimens and survival rates were compared by Hsp70 expression and adjuvant platinum-based chemotherapy. RESULTS: Of 327 enrolled patients, Hsp70 expression was positive in 220 (67.3%). For patients who did not receive adjuvant chemotherapy, Hsp70 expression did not significantly affect survival. However, for patients who received adjuvant chemotherapy, those with Hsp70-positive tumors had a longer disease-free survival outcome than cases with Hsp70-negative tumors (not reached vs. 27.3 months; P=0.002), although there was no significant difference in overall survival (97.0 vs. 58.9 months, P=0.080). In the adjuvant chemotherapy group, multivariate modeling showed that patients with Hsp70-postitive tumors had a lower risk of recurrence and death after adjusting for age, sex, performance status, pathologic stage, and histological type (disease-free survival: adjusted hazard ratio, 0.537; 95% CI, 0.362-0.796; P=0.002; overall survival: adjusted hazard ratio, 0.663; 95% CI, 0.419-1.051; P=0.080). CONCLUSION: Hsp70 is a positive predictive factor in completely resected NSCLC with received platinum-based adjuvant chemotherapy.