Non-small Cell Lung Carcinoma H1299 Research Articles

Evaluation of antitumor potential of an anti-glypican-1 monoclonal antibody in preclinical lung cancer models reveals a distinct mechanism of action.

The main objective of this study was to investigate the antitumor effect of a mouse anti-human glypican-1 (GPC1) monoclonal antibody (mAb) on non-small cell lung carcinoma (NSCLC) and associated molecular mechanisms. The anti-proliferative and anti-migratory activities of anti-GPC1 mAb were examined in A549 and H460 NSCLC cells and LL97A lung fibroblasts. The inhibitory effect of anti-GPC1 mAb on tumor growth was evaluated in an orthotopic lung tumor model. The in vitro study showed that anti-GPC1 mAb profoundly inhibited the anchorage-independent growth of A549 and H460 NSCLC cells and exhibited relatively high cytotoxic activities towards LL97A lung fibroblasts, A549/LL97A and H460/LL97A coculture spheroids. Moreover, anti-GPC1 mAb significantly decreased the expression of phospho-Src (p-Src; Tyr416), p-Akt (Ser473) and β-catenin in the co-cultured LL97A lung fibroblasts, and the expression of phospho-mitogen-activated protein kinase kinase (p-MEK; Ser217/221) and phospho-90 kDa ribosomal s6 kinase (p-p90RSK; Ser380) in co-cultured A549 cells. When anti-GPC1 mAb was administered to tumor-bearing mice, the inhibitory effect of anti-GPC1 mAb on the orthotopic lung tumor growth was not statistically significant. Nonetheless, results of Western blot analysis showed significant decrease in the phosphorylation of fibroblast growth factor receptor 1 (FGFR1) at Tyr766, Src at Tyr416, extracellular signal-regulated kinase (ERK) at Thr202/Tyr204, 90 kDa ribosomal S6 kinase (RSK) at Ser380, glycogen synthase kinases 3α (GSK3α) at Ser21 and GSK3β at Ser9 in tumor tissues. These data implicate that anti-GPC1 mAb treatment impairs the interaction between tumor cells and tumor associated fibroblasts by attenuating the paracrine FGFR signal transduction. The relatively potent cytotoxicity of anti-GPC1 mAb in lung fibroblasts and its potential inhibitory effect on the paracrine FGFR signal transduction warrant further studies on the combined use of this mAb with targeted therapeutics to improve therapeutic outcomes in lung cancer.

Abstract 2030: N-cadherin-mediated activation of PI3K/Akt pathway following application of tumor treating fields (TTFields)

Abstract Introduction: Tumor Treating Fields (TTFields) therapy is FDA-approved for the treatment of glioblastoma and unresectable pleural mesothelioma, and has recently demonstrated benefit (together with an immune checkpoint inhibitor) for the treatment of metastatic non-small cell lung carcinoma (NSCLC) progressing on or after platinum-based therapy. The current study aimed to uncover cellular response mechanisms to TTFields. Methods: A2780 ovarian cancer cells and H1299 NSCLC cells were treated with TTFields for 72 h (200 and 150 kHz, respectively; 1.7 V/cm RMS). Changes in signaling pathways were analyzed using the Luminex multiplex assay and validated by protein expression. Fluorescence microscopy, calcium switch assay, antibody neutralization assay, and immunoprecipitation were employed to investigate the mechanism of action. The efficacy of concomitant treatment with TTFields and a potential inhibitor was tested in cell lines (cytotoxic and clonogenic effects) and two orthotopic mouse models: MOSE-L-FFL ovarian cancer and LL/2 lung cancer. Immunohistochemistry was performed on tumor sections from both models. Results: Increased AKT phosphorylation was observed in the cancer cells treated with TTFields. N-cadherin, known to be involved in the activation of the PI3K/AKT pathway, was elevated in the membranes of cells treated with TTFields. Elimination of calcium ions required for N-cadherin homophilic ligation abrogated TTFields-induced AKT phosphorylation, whereas calcium supplementation restored AKT phosphorylation. Inhibition of N-cadherin-mediated cell-cell contacts by neutralizing antibody resulted in a significant reduction in TTFields-induced AKT phosphorylation. Pull-down assays with an anti-N-cadherin antibody demonstrated increased recruitment of the p85 regulatory subunit of PI3K to N-cadherin complexes following TTFields application. TTFields-induced activation of AKT could be mitigated in cell cultures as well as in animal models by application of the PI3K inhibitor alpelisib. Co-treatment with alpelisib also enhanced the effectiveness of TTFields in vitro and in vivo. Conclusions: The PI3K/AKT signaling pathway, activated via cell-cell N-cadherin interactions, plays a role in the cancer cell response to TTFields treatment. Inhibiting the PI3K/AKT pathway may potentially sensitize tumors to TTFields. Citation Format: Anat Klein-Goldberg, Tali Voloshin, Efrat Zemer-Tov, Rom Paz, Lilach Koren, Kerem Wainer-Katsir, Alexandra Volodin, Bella Koltun, Boris Brant, Yiftah Barsheshet, Tal Kan, Cfir David, Tharwat Haj Khalil, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. N-cadherin-mediated activation of PI3K/Akt pathway following application of tumor treating fields (TTFields) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2030.

P10.08.B PI3K INHIBITION FOR SENSITIZING CANCER CELLS TO TUMOR TREATING FIELDS (TTFIELDS)

Abstract BACKGROUND Tumor Treating Fields (TTFields) are electric fields that disrupt cellular processes critical for cancer cell viability and tumor progression, ultimately leading to cell death. TTFields therapy is approved for treatment of adult patients with glioblastoma (GBM) or unresectable pleural mesothelioma. Clinical trials are underway in other solid tumors, including ovarian cancer and non-small cell lung carcinoma (NSCLC). The objective of this study is to identify possible mechanisms involved in reduced sensitivity of cancer cell to TTFields, and explore strategies to circumvent them. MATERIAL AND METHODS GBM U-87 MG, ovarian cancer A2780, and NSCLC H1299 cells were treated with continuous long-term application of TTFields (1.7 V/cm RMS, 200 or 150 kHz, 6 or 13 days, specific conditions depending on cell line). Changes in signaling pathways were examined for cells following 3 days of treatment with Luminex multiplex assay, followed by Western blot validation for specific pathway markers. In vivo validation was performed in ovarian cancer (MOSE-L), hepatocellular carcinoma (N1-S1), and NSCLC (LL/2) tumor sections from animals treated with TTFields utilizing immunohistochemistry. Next, efficacy of TTFields concomitant with relevant inhibitors was evaluated in vitro and in mice inoculated orthotopically with ovarian cancer cells (MOSE-L). Tumor volume was measured at study end by luciferin signal detection using the In Vivo Imaging System (IVIS). RESULTS TTFields inflicted a cytotoxic effect on the cancer cells that increased over time, though with moderately reduced sensitivity following prolonged treatment application. PI3K/AKT signaling pathway was shown to be activated in treated cells, with the amplitude of AKT phosphorylation increasing over time. AKT phosphorylation was also demonstrated in tumor sections of animals treated with TTFields. Experiments performed with concomitant PI3K/AKT pathway inhibitors sensitized the cells to TTFields, enhancing cytotoxicity in vitro and treatment efficacy in vivo. CONCLUSION PI3K/AKT signaling pathway is involved in cancer cell reduced sensitivity to TTFields, and inhibition of this pathway sensitizes cancer cells to TTFields.

Betulinic acid, a major therapeutic triterpene of Celastrus orbiculatus Thunb., acts as a chemosensitizer of gemcitabine by promoting Chk1 degradation.

Celastrus orbiculatus Thunb., also called as oriental bittersweet vine or climbing spindle berry, a traditional Chinese herbal medicine has been used to treat a spectrum of painful and inflammatory diseases for centuries. Explored for their unique medicinal properties, C.orbiculatus offers additional therapeutic effects on cancerous diseases. The effect of single-agent gemcitabine on survival has not long been encouraging, combination therapies provide patients multiple chances of benefit for improved clinical response. This study aims at expounding the chemopotentiating effects and underlying mechanisms of betulinic acid, a primary therapeutic triterpene of C. orbiculatus in combination with gemcitabine chemotherapy. The preparation of betulinic acid was optimized using ultrasonic-assisted extraction method. Gemcitabine-resistant cell model was established by induction of the cytidine deaminase. MTT, colony formation, EdU incorporation and Annexin V/PI staining assays were used to evaluate cytotoxicity, cell proliferation and apoptosis in BxPC-3 pancreatic cancer cell line and H1299 non-small cell lung carcinoma cell line. Comet assay, metaphase chromosome spread and γH2AX immunostaining were applied for DNA damage assessment. Western blot and co-immunoprecipitation was used to detect the phosphorylation and ubiquitination of Chk1. Mode of action of gemcitabine in combination with betulinic acid was further captured in BxPC-3-derived mouse xenograft model. We noticed that the extraction method had an impact on the thermal stability of C. orbiculatus. Ultrasound-assisted extraction at room temperature in shorter processing time could maximize the overall yields and biological activities of C. orbiculatus. The major constituent was identified as betulinic acid, and the pentacyclic triterpene represented the prominent anticancer activity of C. orbiculatus. Forced expression of cytidine deaminase conferred acquired resistance to gemcitabine, while betulinic acid displayed equivalent cytotoxicity toward gemcitabine-resistant and sensitive cells. A combination therapy of gemcitabine with betulinic acid produced synergistic pharmacologic interaction on cell viability, apoptosis and DNA double-strand breaks. Moreover, betulinic acid abrogated gemcitabine-triggered Chk1 activation by destabilizing Chk1 loading via proteasomal degradation. The combination of gemcitabine and betulinic acid significantly retarded BxPC-3 tumor growth in vivo compared to single-agent gemcitabine treatment alone, accompanied with reduced Chk1 expression. These data provide evidence that betulinic acid is a potential candidate for chemosensitization as a naturally occurring Chk1 inhibitor and warrants further preclinical evaluation.

CSIG-41. SENSITIZING CANCER CELLS TO TUMOR TREATING FIELDS (TTFIELDS) BY INHIBITION OF PI3K

Abstract Tumor Treating Fields (TTFields) are alternating electric fields, which disrupt cellular process critical for cancer cell survival and tumor progression. TTFields therapy is approved for the treatment of glioblastoma (GBM) and unresectable malignant pleural mesothelioma, and is being tested in clinical studies for the treatment of other solid tumors, including ovarian cancer, non-small cell lung carcinoma (NSCLC), and hepatocellular carcinoma (HCC). The current study aimed to detect potential mechanisms that may reduce cellular sensitivity to TTFields, and target these pathways in order to re-sensitize the cells to TTFields. Cancer cells (Ovarian A2780, GBM U-87 MG, and NSCLC H1299) that display reduced sensitivity to TTFields were generated by continuous long-term TTFields application (7 or 13 days, depending on the cell line). A Luminex multiplex assay revealed activation of the PI3K/AKT/mTOR signaling pathway in these cells, with significant increases in phosphorylation levels of AKT and RPS6. This elevation was also observed by immunohistochemistry in tumor sections from N1S1 HCC tumor-bearing rats treated with TTFields relative to sham. Treatment of cells with PI3K inhibitors re-sensitized them to TTFields and downregulated the phosphorylation of AKT. Concomitant application of TTFields with the PI3K inhibitor alpelisib in mice orthotopically implanted with MOSE-L firefly luciferase (FFL) ovarian cancer cells resulted in enhanced efficacy, as determined by In Vivo Imaging System (IVIS) measurements of tumor volume. Overall, this study demonstrated that the PI3K/AKT/mTOR signaling pathway is involved in reduced cancer cell sensitivity to long-term application of TTFields, and that re-sensitization may be achieved with relevant inhibitors. The results provide a rationale for further examining the potential benefit of TTFields concomitant with PI3K inhibitors.

PI3K Inhibition Sensitized Cancerous Cells to Tumor Treating Fields (TTFields)

<h3>Purpose/Objective(s)</h3> Tumor Treating Fields (TTFields) are alternating electric fields, approved for treatment of patients with newly diagnosed glioblastoma (GBM), recurrent GBM, or unresectable malignant pleural mesothelioma. Additional clinical trials are underway in other tumor types, including ovarian cancer, non-small cell lung carcinoma (NSCLC), and hepatocellular carcinoma (HCC). While TTFields therapy has been demonstrated to extend life, tumor progression eventually occurs in most patients. The current research aimed to identify molecular mechanisms involved in reduced cancer cellular sensitivity to TTFields, and targeting these potential pathways in order to re-sensitize the cells to TTFields. <h3>Materials/Methods</h3> Ovarian A2780, GBM U-87 MG, and NSCLC H1299 cells with reduced sensitivity to TTFields were generated by continuous long-term application of TTFields (7 or 13 days, depending on the cell line). Changes in signaling pathways in these cells were examined by Luminex multiplex assay, and specific pathway markers were validated by Western blot of the cell lysates as well as by immunohistochemistry in tumor sections from N1S1 HCC tumor-bearing rats treated with sham or TTFields. Next, TTFields were applied in conjunction with relevant inhibitors, followed by cell count measurements and western blot examinations. Finally, the concomitant application of TTFields with a relevant inhibitor was evaluated in mice orthotopically implanted with MOSE-L firefly luciferase (FFL) ovarian cancer cells. Tumor volume was measured at study end using the In Vivo Imaging System (IVIS) to detect the luciferin signal. <h3>Results</h3> Sensitivity of cancer cells to TTFields was decreased following continuous long-term application of TTFields. PI3K/AKT/mTOR signaling pathway was activated in these cells, with significant increases in phosphorylation levels of AKT and RPS6. This elevation was also observed in tumor sections from rats treated with TTFields. Treatment with PI3K inhibitors re-sensitized the cells to TTFields and downregulated the phosphorylation of AKT. In vivo, concomitant application of TTFields with the PI3K inhibitor alpelisib resulted in enhanced efficacy. <h3>Conclusion</h3> The current study demonstrated that the PI3K/AKT/mTOR signaling pathway is involved in reduced cancer cell sensitivity to long-term application of TTFields. Furthermore, re-sensitization to TTFields could be achieved with PI3K inhibitors, providing a rationale for further examining the potential benefit of TTFields concomitant with PI3K inhibitors.

P10.11.B Re-sensitizing cancer cells to Tumor Treating Fields (TTFields) through PI3K/AKT/mTOR pathway inhibition

Abstract Background Tumor Treating Fields (TTFields) are alternating electric fields disrupting cellular processes critical for cancer cell replication and tumor progression. TTFields therapy is approved for treatment of newly diagnosed glioblastoma (GBM), recurrent GBM, and unresectable malignant pleural mesothelioma, and is currently under clinical investigation for treating other solid tumors, such as ovarian cancer, non-small cell lung carcinoma (NSCLC), and hepatocellular carcinoma (HCC). The research herein aimed to identify potential treatment escape mechanisms and explore the possibility of targeted inhibition of these pathways for re-sensitizing the cells to TTFields. Material and Methods GBM U-87 MG, ovarian A2780, and NSCLC H1299 cells were treated with TTFields (1.7 V/cm RMS, 200 or 150 kHz) for continuous long-term application (7 or 13 days, specific conditions depending on the cell line). Changes in signaling pathways in these cells relative to cells exposed to short term TTFields application (3 or 7 days, depending on cell line) were examined by Luminex multiplex assay. Specific pathway markers were examined by immunohistochemistry of tumor sections from sham or TTFields-treated rats bearing N1S1 HCC tumors. TTFields were then co-applied with relevant pathway inhibitors, followed by cell count measurements and western blot examinations for specific pathway markers. The concomitant application of TTFields with a selected inhibitor was tested in mice inoculated orthotopically with MOSE-L firefly luciferase (FFL) ovarian cancer cells. Tumor volume was measured at study end by luciferin signal detection using the In Vivo Imaging System (IVIS). Results Cancer cells exposed to long-term application of TTFields displayed decreased sensitivity to TTFields. The PI3K/AKT/mTOR pathway was activated in these cells, with significant increases in AKT and RPS6 phosphorylation levels also observed in HCC tumors from rats treated with TTFields. PI3K inhibitors re-sensitized the cells to TTFields cytotoxicity, with associated down regulation of AKT phosphorylation. Application of TTFields concomitant with the PI3K inhibitor alpelisib resulted in enhanced efficacy in the ovarian cancer mouse model. Conclusions The current research demonstrated that PI3K/AKT/mTOR signaling pathway activation was involved in the response to long-term application of TTFields, with increased phosphorylation of key proteins observed both in vitro and in vivo. Concomitant treatment with PI3K inhibitors and TTFields re-sensitized the cells to TTFields, as it alleviated TTFields-induced AKT activation.

Nano-Targeting of Thyrointegrin αvβ3 Receptor in Solid Tumors and Impact on Radiosensitization.

Tetraiodothyroacetic acid is a ligand of thyrointegrin αvβ3, a protein that is highly expressed in various solid tumors and surrounding neovascular regions. Its nano derivative, Nano-diamino-tetrac (NDAT), has anticancer properties in preclinical models, enhances radiosensitivity, and inhibits cancer cell growth in vitro after X-ray irradiation. Using a novel experimental system developed to deliver accurate radiation dose to tumors under sterile conditions, this study establishes NDAT's radiosensitizing effect in SUIT-2 pancreatic cancer and H1299 non-small cell lung carcinoma xenografts in athymic mice for tumor-targeted radiation. In this work, low-melting-point Lipowitz alloy was used to shield normal organs and allow accurate tumor-targeted irradiation. Over a three-week period, mice with SUIT-2 xenografts received daily NDAT treatment at different doses (0, 1, 3, or 10 mg/kg body weight) and tumor-targeted irradiation (1 or 5 Gy). Validation was performed with a test dose of 30 Gy to mice bearing SUIT-2 xenografts and resulted in more than 80% reduction in tumor weight, compared to nonirradiated tumor weight. The results of this work showed that NDAT had a radiosensitizing effect in a dose-dependent manner in decreasing tumor growth and viability. An enhanced anticancer effect of NDAT (1 mg/kg body weight) was observed in mice with H1299 xenografts receiving 5 Gy tumor-targeted irradiation, indicated by decreased tumor weight and increased necrosis, compared to nonirradiated tumors. This technique demonstrated accurate tumor-targeted irradiation with new shielding methodology, and combined with thyrointegrin antagonist NDAT treatment, showed anticancer efficacy in pancreatic cancer and non-small cell lung carcinoma.

Radiation enhances the delivery of antisense oligonucleotides and improves chemo-radiation efficacy in brain tumor xenografts

Overexpression of O6-methylguanine DNA methyltransferase (MGMT) contributes to resistance to chemo-radiation therapy (CRT) in brain tumors. We previously demonstrated that non-ablative radiation improved delivery of anti-MGMT morpholino oligonucleotides (AMONs) to reduce MGMT levels in subcutaneous tumor xenografts. We evaluate this approach to enhance CRT efficacy in rat brain tumor xenograft models. The impact of radiation on targeted delivery was evaluated using fluorescent oligonucleotides (f-ON). In vitro, f-ON was localized to clathrin-coated vesicles, endosomes, and lysosomes using confocal microscopy in T98G glioma cells. In vivo, fluorescence was detected in pre-radiated, but not non-radiated Long Evans (non-tumor bearing) rat brains. Cranial radiation (2 Gy) followed by AMONs (intravenous, 10.5 mg/kg) reduced MGMT expression by 50% in both orthotopic cerebellar D283 medulloblastoma and intracerebral H460 non-small cell lung carcinoma (NSCLC) xenograft models. To evaluate the efficacy, AMONs concurrent with CRT (2 Gy radiation plus oral 20 mg/kg temozolomide ×4 days) reduced tumor volumes in the medulloblastoma model (p = 0.012), and a similar trend was found in the NSCLC brain metastasis model. We provide proof of concept for the use of non-ablative radiation to guide and enhance the delivery of morpholino oligonucleotides into brain tumor xenograft models to reduce MGMT levels and improve CRT efficacy.

MicroRNA-25-3p promotes cisplatin resistance in Non-small-cell lung carcinoma (NSCLC) through adjusting PTEN/PI3K/AKT route

ABSTRACT MicroRNAs exert crucial effects in the drug resistance. The purpose of this research was to investigate the miR-25-3p effects on DDP resistance in NSCLC. We used RT-qPCR to evaluate the expression of miR-25-3p. Cell growth was determined using MTS assay. Cellular bio-activity was analyzed via Colony formation, Annexin V/PI, and Transwell assay. Luciferase reporter assay was used to determine miR-25-3p and PTEN binding. Western blot was used to determine PTEN, PI3K, p-AKT/AKT expression. In-vivo study was used to determine the effects of miR-25-3p on the tumor growth. Expression of miR-25-3p is increased in NSCLC cisplatin resistant A549 and H1299 cells. Furthermore, miR-25-3p mimic enhanced drug resistance, and accelerated cell invasion and metastasis. Moreover, miR-25-3p mimic resulted in the activation of PTEN/PI3K/AKT pathway. However, miR-25-3p inhibitors exhibited the opposite trend. We further identified PTEN as a potential target of miR-25-3p. PTEN knockout promoted cisplatin resistance, while PTEN mimic displayed opposite effects. Interestingly, miR-25-3p further boosted cisplatin resistance cells in vivo, and miR-25-3p inhibitors reduced the in-vivo tumor volume. MiR-25-3p/PTEN/PI3K/AKT axis might accelerate DDP tolerance in NSCLC, which may serve as a potential target for chemotherapy resistance in NSCLC.

EXTH-05. NON-CYTOTOXIC RADIATION ENHANCES DELIVERY OF ANTISENSE OLIGONUCLEOTIDES AND IMPROVES CHEMO-RADIATION EFFICACY IN BRAIN TUMOR XENOGRAFTS

Abstract Overexpression of O6-methylguanine DNA methyltransferase (MGMT) contributes to brain tumor chemo-resistance. Previously we found that non-cytotoxic radiation improved anti-MGMT Morpholino Oligonucleotides (AMONs) delivery to reduce MGMT levels in subcutaneous tumor xenografts. Here we evaluated if radiation enhanced the delivery of intravenous (IV) AMONs to rat brain and improved chemo-radiation therapy (CRT) efficacy using rat models of human brain tumors. Athymic nude rats bearing orthotopic cerebellar D283 medulloblastoma or intracerebral H460 non-small cell lung carcinoma (NSCLC) brain metastasis xenografts were used. The impact of cranial radiation on delivery of IV 3’-carboxyfluorescein labeled oligonucleotides across the neurovascular unit was evaluated using confocal microscopy. We found that high brain parencymal fluorescence in radiated compared to non-radiated rats. MGMT protein silencing was assessed by immunoblot in tumor-bearing rats 3 d after 2 Gy cranial radiation alone or followed in 1 d by IV AMONs (10.5 mg/kg). Radiation followed by AMONs reduced MGMT expression by 50% in both xenograft models. To evaluate efficacy, tumor-bearing rats received one dose of 2 Gy radiation plus oral temozolomide (20 mg/kg x 4d) with or without IV AMONs. AMONs concurrent with CRT reduced tumor volumes in the medulloblastoma model (p=0.012), and a similar trend was found in the NSCLC brain metastasis model. In conclusion, we demonstrate the use of a single clinically relevant radiation dose fraction to guide and enhance the delivery of oligonucleotides into brain tumor xenograft models to reduce MGMT levels and improve CRT efficacy.

Discovery of Isoplumbagin as a Novel NQO1 Substrate and Anti-Cancer Quinone.

Isoplumbagin (5-hydroxy-3-methyl-1,4-naphthoquinone), a naturally occurring quinone from Lawsonia inermis and Plumbago europaea, has been reported to have anti-inflammatory and antimicrobial activity. Inflammation has long been implicated in cancer progression. In this study, we examined the anticancer effect of chemically synthesized isoplumbagin. Our results revealed that isoplumbagin treatment suppressed cell viability and invasion of highly invasive oral squamous cell carcinoma (OSCC) OC3-IV2 cells, glioblastoma U87 cells, non-small cell lung carcinoma H1299 cells, prostate cancer PC3 cells, and cervical cancer HeLa cells by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Boyden chamber assays. In vivo studies demonstrate the inhibitory effect of 2 mg/kg isoplumbagin on the growth of orthotopic xenograft tumors derived from OSCC cells. Mechanistically, isoplumbagin exerts its cytotoxic effect through acting as a substrate of reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] dehydrogenase quinone 1 (NQO1) to generate hydroquinone, which reverses mitochondrial fission phenotype, reduces mitochondrial complex IV activity, and thus compromises mitochondrial function. Collectively, this work reveals an anticancer activity of isoplumbagin mainly through modulating mitochondrial dynamics and function.

Abstract A87: Acetaminophen pretreatment stimulated interferon γ-induced PD-L1 protein expression in vitro and CD68 positive macrophage infiltration in tumor xenograft

Abstract Immunotherapy targeting the programmed cell death ligand 1/programmed cell death protein 1 (PD-L1/PD-1) pathway using antibodies is clinically effective in treating a spectrum of cancers. Acetaminophen (AAP) has shown antitumor and/or chemo-enhancing effects in human cancer cells in vitro and in vivo. We investigated the effects of AAP exposure on cancer cells’ immune checkpoint PD-L1 expression in vitro and their in vivo tumorigenic ability. Acetaminophen (10 mM) alone for 2 hr has no effect on cell viability and no effect on PD-L1 level of A2058 melanoma and H460 non-small cell lung carcinoma in vitro. However, AAP treatment for 2 hr followed by interferon-γ (20 ng/ml) stimulated PD-L1 protein expression. The stimulatory effect of AAP pretreatment was not replicated with other glutathione-depleting reagents, including hydrogen peroxide (100 μM; 2hr) or buthionine sulfoximine (50 μM; 24hr). For the in vivo tumorigenesis study, cancer cells (2.5x107) pretreated with AAP developed significantly (p=0.0028 in A2058 and p=0.002 in H460) smaller tumor size after being subcutaneously implanted into athymic rats. Compared to vehicle control, AAP also showed more tumor CD68+ macrophage infiltration by immunohistochemistry. Our results demonstrate for the first time the short-time exposure of AAP inhibited tumor growth by enhancing CD68+ macrophage infiltration. We conclude that high-dose AAP may be immune modulatory, a cell marker regulator and it could be potentially used as a single agent or in combination with other immunotherapy drugs to facilitate therapeutic efficacy. Citation Format: Jeffrey Wu, Alexander J. Neuwelt, Leslie L. Muldoon, Edward A. Neuwelt. Acetaminophen pretreatment stimulated interferon γ-induced PD-L1 protein expression in vitro and CD68 positive macrophage infiltration in tumor xenograft [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A87.

GLUL Ablation Can Confer Drug Resistance to Cancer Cells via a Malate-Aspartate Shuttle-Mediated Mechanism.

Glutamate-ammonia ligase (GLUL) is important for acid-base homeostasis, ammonia detoxification, cell signaling, and proliferation. Here, we reported that GLUL ablation conferred resistance to several anticancer drugs in specific cancer cell lines while leaving other cell lines non-resistant to the same drugs. To understand the biochemical mechanics supporting this drug resistance, we compared drug-resistant GLUL knockout (KO) A549 non-small-cell lung carcinoma (NSCLC) cells with non-resistant GLUL KO H1299 NSCLC cells and found that the resistant A549 cells, to a larger extent, depended on exogenous glucose for proliferation. As GLUL activity is linked to the tricarboxylic acid (TCA) cycle via reversed glutaminolysis, we probed carbon flux through both glycolysis and TCA pathways by means of 13C5 glutamine, 13C5 glutamate, and 13C6 glucose tracing. We observed increased labeling of malate and aspartate in A549 GLUL KO cells, whereas the non-resistant GLUL KO H1299 cells displayed decreased 13C-labeling. The malate and aspartate shuttle supported cellular NADH production and was associated with cellular metabolic fitness. Inhibition of the malate-aspartate shuttle with aminooxyacetic acid significantly impacted upon cell viability with an IC50 of 11.5 μM in resistant GLUL KO A549 cells compared to 28 μM in control A549 cells, linking resistance to the malate-aspartate shuttle. Additionally, rescuing GLUL expression in A549 KO cells increased drug sensitivity. We proposed a novel metabolic mechanism in cancer drug resistance where the increased capacity of the malate-aspartate shuttle increased metabolic fitness, thereby facilitating cancer cells to escape drug pressure.

MEAK-7 Forms an Alternative mTOR Complex with DNA-PKcs in Human Cancer

SummaryMTOR associated protein, eak-7 homolog (mEAK-7), activates mechanistic target of rapamycin (mTOR) signaling in human cells through an alternative mTOR complex to regulate S6K2 and 4E-BP1. However, the role of mEAK-7 in human cancer has not yet been identified. We demonstrate that mEAK-7 and mTOR signaling are strongly elevated in tumor and metastatic lymph nodes of patients with non-small-cell lung carcinoma compared with those of patients with normal lung or lymph tissue. Cancer stem cells, CD44+/CD90+ cells, yield elevated mEAK-7 and activated mTOR signaling. mEAK-7 is required for clonogenic potential and spheroid formation. mEAK-7 associates with DNA-dependent protein kinase catalytic subunit isoform 1 (DNA-PKcs), and this interaction is increased in response to X-ray irradiation to regulate S6K2 signaling. DNA-PKcs pharmacologic inhibition or genetic knockout reduced S6K2, mEAK-7, and mTOR binding with DNA-PKcs, resulting in loss of S6K2 activity and mTOR signaling. Therefore, mEAK-7 forms an alternative mTOR complex with DNA-PKcs to regulate S6K2 in human cancer cells.

Tumor growth suppression using a combination of taxol-based therapy and GSK3 inhibition in non-small cell lung cancer.

Glycogen synthase kinase-3 (GSK3) is over-expressed and hyperactivated in non-small cell lung carcinoma (NSCLC) and plays a role in ensuring the correct alignment of chromosomes on the metaphase plate during mitosis through regulation of microtubule stability. This makes the enzyme an attractive target for cancer therapy. We examined the effects of a selective cell-permeant GSK3 inhibitor (CHIR99021), used alone or in combination with paclitaxel, using an in vitro cell growth assay, a quantitative chromosome alignment assay, and a tumor xenograft model. CHIR99021 inhibits the growth of human H1975 and H1299 NSCLC cell lines in a synergistic manner with paclitaxel. CHIR99021 and paclitaxel promoted a synergistic defect in chromosomal alignment when compared to each compound administered as monotherapy. Furthermore, we corroborated our in vitro findings in a mouse tumor xenograft model. Our results demonstrate that a GSK3 inhibitor and paclitaxel act synergistically to inhibit the growth of NSCLC cells in vitro and in vivo via a mechanism that may involve converging modes of action on microtubule spindle stability and thus chromosomal alignment during metaphase. Our findings provide novel support for the use of the GSK3 inhibitor, CHIR99021, alongside taxol-based chemotherapy in the treatment of human lung cancer.

Targeting of BRM Sensitizes BRG1-Mutant Lung Cancer Cell Lines to Radiotherapy.

Targeting of epigenetic regulators as the chromatin remodeler SWI/SNF is proving to be a promising therapeutic strategy for individualized treatment of cancer patients. Here, we tested whether targeting one of the two mutually exclusive subdomains of the SWI/SNF complex BRM/SMARCA2 can sensitize specifically non-small cell lung carcinoma (NSCLC) cells with mutations in the other subunit BRG1/SMARCA4 toward ionizing radiation (IR). Knockdown of BRM with siRNA or shRNA and its consequences for radiation sensitivity as measured by clonogenic survival and plaque-monolayer control was studied in different NSCLC lines with or without BRG1 mutations and in primary fibroblasts. Furthermore, the effect on double-strand break (DSB) repair markers measured by immunofluorescence staining of 53BP1-, γ-H2AX-, and Rad51-foci was investigated. BRG1-mutated cell lines showed an increased surviving fraction compared with BRG1 proficient cells. Depletion of BRM (i) leads to a decreased proliferation rate and plating efficiency specifically in BRG1-mutated cells, (ii) specifically sensitized BRG1-mutant NSCLC cells toward IR as characterized by a survival reducing factor of 0.63 [95% confidence interval (CI), 0.57-0.69] in the dose range between 2 and 6 Gy, and (iii) decreased the tumor control doses after daily fractionation at 4 Gy in BRG1-mutant NSCLC cell lines A549 and H1299 in minimonolayers by 9.9% ± 1.3% and 13.6% ± 1.8%, respectively. In addition, an increase of residual Rad51-foci at 24 hours after irradiation in BRG1-mutant cells was demonstrated. Therefore, targeting of BRM in combination with radiotherapy is supposed to improve the therapeutic outcome of lung cancer patients harboring BRG1 mutations.The present study shows that the moderate radioresponsiveness of NSCLC cells with BRG1 mutations can be increased upon BRM depletion that is associated with a prolonged Rad51-foci prevalence at DNA DSBs.

HIF-1α and HIF-2α Differently Regulate the Radiation Sensitivity of NSCLC Cells.

The hypoxia-inducible transcription factors (HIF)-1/2α are the main oxygen sensors which regulate the adaptation to intratumoral hypoxia. The aim of this study was to assess the role of the HIF proteins in regulating the radiation response of a non-small cell lung cancer (NSCLC) in vitro model. To directly assess the unique and overlapping functions of HIF-1α and HIF-2α, we use CRISPR gene-editing to generate isogenic H1299 non-small cell lung carcinoma cells lacking HIF-1α, HIF-2α or both. We found that in HIF1 knockout cells, HIF-2α was strongly induced by hypoxia compared to wild type but the reverse was not seen in HIF2 knockout cells. Cells lacking HIF-1α were more radiation resistant than HIF2 knockout and wildtype cells upon hypoxia, which was associated with a reduced recruitment of γH2AX foci directly after irradiation and not due to differences in proliferation. Conversely, double-HIF1/2 knockout cells were most radiation sensitive and had increased γH2AX recruitment and cell cycle delay. Compensatory HIF-2α activity in HIF1 knockout cells is the main cause of this radioprotective effect. Under hypoxia, HIF1 knockout cells uniquely had a strong increase in lactate production and decrease in extracellular pH. Using genetically identical HIF-α isoform-deficient cells we identified a strong radiosensitizing of HIF1, but not of HIF2, which was associated with a reduced extracellular pH and reduced glycolysis.

The p53/miR-193a/EGFR feedback loop function as a driving force for non-small cell lung carcinoma tumorigenesis.

Background:Non-small cell lung carcinoma (NSCLC) is a major worldwide health threat due to its low cure rate and high lethality. Emerging evidence suggests that epidermal growth factor receptor (EGFR) plays vital roles in cancer initiation and progression, and is considered an important cancer-driving protein. However, how EGFR expression is regulated during NSCLC development remains to be fully elucidated.Methods:In NSCLC clinical samples, EGFR protein levels were measured by western blotting and qRT-PCR, respectively. Combining microRNA (miRNA) target prediction software and the pulldown assay, we predicted microRNAs (miRNAs) that targeted EGFR. Next, three NSCLC cell lines, A549 (p53 WT), H322 (p53 mutant), and H1299 (p53 null), were used to demonstrate the direct targeting of EGFR by miR-193a. In addition, we investigated the biological effects of EGFR inhibition by miR-193a in vitro using Cell Counting Kit-8, 5-Ethynyl-2′-deoxyuridine (EdU), transwell, and apoptosis assays. Then, using ChIP and luciferase assays, we demonstrated that miR-193a was directly activated by p53 at the transcriptional level and that p53-induced-miR-193a and EGFR form a double-negative feedback loop.Results:We found that EGFR mRNA and protein were upregulated in NSCLC. We predicted that EGFR was a target of miR-193a and validated that miR-193a bound directly to the 3′-UTR of the EGFR mRNA. Moreover, miR-193a inhibited NSCLC proliferation and invasion, and promotes NSCLC apoptosis by directly downregulating EGFR. Then, we demonstrated that p53 directly activated miR-193a transcription, whereas EGFR functioned as a transcriptional repressor to negatively control miR-193a expression, forming a feedback loop. The loop promoted NSCLC cell proliferation and migration and accelerated tumor growth in xenograft mice.Conclusions:This study highlights a double-negative feedback loop in NSCLC. The feedback loop is crucial because overexpressing EGFR strongly accelerated tumor growth, while miR-193a restoration blocked tumor growth in vivo. Our findings are in line with the emerging opinion that miRNAs and protein regulators form regulatory networks in critical biological processes and that their dysregulation can lead to cellular dysfunction. In conclusion, this study provides important insights into the molecular mechanisms of NSCLC progression and may help inform the development of new therapeutics for managing NSCLC.

Astragalus polysaccharide combined with 10-hydroxycamptothecin inhibits metastasis in non-small cell lung carcinoma cell lines via the MAP4K3/mTOR signaling pathway.

Non-small cell lung carcinoma (NSCLC) is a life-threatening malignancy. The level of the cell growth regulator mitogen-activated protein kinase kinase kinase kinase 3 (MAP4K3) has been shown to be correlated with a high risk of NSCLC recurrence and poor recurrence-free survival rate. The present study examined the effects of Astragalus polysaccharide (APS) and 10-hydroxycamptothecin (HCPT), which are associated with marked suppression and dephosphorylation of the MAP4K3/mammalian target of rapamycin (mTOR) signaling pathway, in the H1299 NSCLC cell line. APS and HCPT decreased H1299 cell viability, induced apoptosis and altered the cell cycle stages, as evaluated using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometric analysis. Furthermore, APS increased the expression of apoptosis-associated genes B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX), of proteases cysteine-aspartic acid protease (caspase)-3 and -9, and of cytochrome c. HCPT promoted autophagy in H1299 cells, with concomitant suppression of the expression of MAP4K3 and downregulation of mTOR signaling. Notably, combination treatment with the two agents reduced the migration and invasion of H1299 cells compared with the single treatments. It was also demonstrated that the overexpression of MAP4K3 promoted the migration and invasion of H1299 cells, and that the kinase activity was essential to this. These findings suggested that MAP4K3 may be an attractive target for the treatment of NSCLC