LncRNA MITA1 promotes gefitinib resistance by inducing autophagy in lung cancer cells.

Lung cancer is a major health challenge worldwide. Gefitinib, a tyrosine kinase inhibitor (TKI), is the common therapeutic drug used in advanced non-small-cell lung cancer (NSCLC). However, it is eventually bound to face the problem of acquired drug resistance. In this work, we investigated the role of lncRNA MITA1 in the acquisition of gefitinib resistance in NSCLC and uncovered the possible underlying molecular mechanism of the same. Experiments were carried out using the HCC827 and HCC827GR cells. These were transfected with pcDNA-MITA1 or si-MITA1 and treated with gefitinib. Subsequently, lncRNA MITA1 mediated effect on cell viability and apoptosis were studied using the MTT and flow cytometry assays. Furthermore, using qRT-PCR, Western blotting, and immunofluorescence assays, the regulatory association between lncRNA MITA1 and markers of autophagy (LC3, Beclin-1, and p62) were examined by estimating their cellular protein levels. Also, these results were verified in the presence of an autophagy inhibitor bafilomycin A1. We found that MITA1 was highly upregulated in the gefitinib-resistant NSCLC cells, indicating the regulatory role of MITA1 in gefitinib resistance. Mechanistically, upregulated MITA1 led to gefitinib resistance by suppressing apoptosis, increasing cell viability, and inducing autophagy. Furthermore, these results were true when tested in the presence of bafilomycin A1. Our results suggest that MITA1 by inducing autophagy could be a key regulator of gefitinib resistance in NSCLC.

DEPDC1 up-regulates RAS expression to inhibit autophagy in lung adenocarcinoma cells.

DEP domain containing 1(DEPDC1) is involved in the tumorigenesis of a variety of cancers. But its role in tumorigenesis of lung adenocarcinoma (LUAD) is not fully understood. Here, we investigated the role and the underlying mechanisms of DEPDC1 in the development of LUAD. The expression and prognostic values of DEPDC1 in LUAD were analysed by using the data from public databases. Gene enrichment in TCGA LUAD was analysed using GSEA software with the pre-defined gene sets. Cell proliferation, migration and invasion of A549 cells were examined with colony formation, Transwell and wound healing assays. The function of DEPDC1 in autophagy and RAS-ERK1/2 signalling was determined with Western blot assay upon DEPDC1 knockdown and/or overexpression in A549, HCC827 and H1993 cells. The results demonstrated that DEPDC1 expression was up-regulated in LUAD tissues, and its high expression was correlated with unfavourable prognosis. The data also showed that DEPDC1 knockdown impaired proliferation, migration and invasion of A549 cells. Most notably, the results showed that DEPDC1 up-regulated RAS expression and thus enhanced ERK1/2 activity, through which DEPDC1 could inhibit autophagy. In conclusion, our study revealed that DEPDC1 is up-regulated in LUAD tissues and plays an oncogenic role in LUAD, and that DEPDC1 inhibits autophagy through the RAS-ERK1/2 signalling in A549, HCC827 and H1993 cells.

Molecular profiling of afatinib-resistant non-small cell lung cancer cells in vivo derived from mice.

Non-small-cell lung cancer (NSCLC) is a leading cause of cancer-related death worldwide. NSCLC patients with overexpressed or mutated epidermal growth factor receptor (EGFR) related to disease progression are treated with EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Acquired drug resistance after TKI treatments has been a major focus for development of NSCLC therapies. This study aimed to establish afatinib-resistant cell lines from which afatinib resistance-associated genes are identified and the underlying mechanisms of multiple-TKI resistance in NSCLC can be further investigated. Nude mice bearing subcutaneous NSCLC HCC827 tumors were administered with afatinib at different dose intensities (5-100 mg/kg). We established three HCC827 sublines resistant to afatinib (IC50 > 1 µM) with cross-resistance to gefitinib (IC50 > 5 µM). cDNA microarray revealed several of these sublines shared 27 up- and 13 down-regulated genes. The mRNA expression of selective novel genes - such as transmembrane 4 L six family member 19 (TM4SF19), suppressor of cytokine signaling 2 (SOCS2), and quinolinate phosphoribosyltransferase (QPRT) - are responsive to afatinib treatments only at high concentrations. Furthermore, c-MET amplification and activations of a subset of tyrosine kinase receptors were observed in all three resistant cells. PHA665752, a c-MET inhibitor, remarkably increased the sensitivity of these resistant cells to afatinib (IC50 = 12-123 nM). We established afatinib-resistant lung cancer cell lines and here report genes associated with afatinib resistance in human NSCLC. These cell lines and the identified genes serve as useful investigational tools, prognostic biomarkers of TKI therapies, and promising molecule targets for development of human NSCLC therapeutics.

Synthesis and biological evaluation of Oblongifolin C derivatives as c-Met inhibitors.

Oblongifolin C, one of the polyprenylated benzoylphloroglucinol natural products (PPAPs) isolated from the fruits of Garcinia yunnanensis Hu, was recently discovered to be a potent anti-tumor agent. A collection of 12 derivatives with modifications on the benzophenone moieties were synthesized and tested for c-Met kinase inhibition and cytotoxicity against the HepG2, Miapaca-2, HCC827, Hela, A549, AGS, and HT-29 cell lines in vitro. An oxidized derivative, 10, was found to possess strong inhibition and anti-migration properties in the HCC827 cell line and serves as a potential lead compound for the development of new anticancer drugs. In addition, structure-activity relationships (SAR) were also evaluated to provide key information for future anticancer drug development.

Chronopharmacodynamics and mechanisms of antitumor effect induced by erlotinib in xenograft-bearing nude mice.

Receptor tyrosine kinases, mediators of a variety of critical cellular functions, contribute to tumor progression and metastasis. The epidermal growth factor receptor (EGFR), a member of the receptor tyrosine kinase family, is ubiquitously expressed on the surface of mammalian cells. Erlotinib hydrochloride (Tarceva) can inhibit the intracellular phosphorylation of tyrosine kinases. To investigate the influence of dosing time on the ability of erlotinib to inhibit tumor growth and the underlying molecular mechanisms via the PI3K/AKT and ERK/MAPK pathway, we established nude mice HCC827 tumor xenografts models. The tumor-bearing mice were housed 3-4 per cage under standardized light/dark cycle conditions (lights on at 07:00 h, off at 19:00 h) with food and water ad libitum. The mice were randomly divided into erlotinib treated groups and control groups, gavaged with erlotinib and vehicle respectively at 6 different time points for 21 days. To draw tumor growth curves, the tumor volume was measured every three days. After the mice were sacrificed, the tumor masses of each group were removed and weighed. The relative protein expression levels of p-EGFR, p-AKT and p-MAPK were assayed at 4 h after erlotinib or vehicle gavage by Western blot analysis. The antitumor effect of erlotinib presented diurnal rhythmicity. The growth of HCC827 xenograft was more potently inhibited by erlotinib in the early light phase than in the early dark phase (p < 0.05). The inhibitory effect of erlotinib on phosphorylation of EGFR, AKT and MAPK varied with its administration time. The results indicate that the antitumor effect of erlotinib is more potent when the drug was administered when the activities of EGFR and its downstream factors increased. Our findings may provide a clue to optimize the dosing schedule of erlotinib.

TPD7 inhibits the non-small cell lung cancer HCC827 cell growth by regulating EGFR signalling pathway.

Non-small cell lung cancer (NSCLC) accounts for 85% of lung cancer cases, and is characterized by more insensitivity to chemotherapy and poor prognosis. Epidermal growth factor receptor (EGFR) has been confirmed as a tumorigenic driving factor of NSCLC. Taspine has been proved effective in the inhibition of malignant tumours. Here, we found TPD7, a novel taspine derivative, exerted most inhibitory effect on EGFR-dependent HCC827 cells and investigated the underling mechanism. In addition, TPD7 could block cell cycle at G0/G1 phase of HCC827 cells by regulating the expression of cyclin D1 and cyclin E. Furthermore, TPD7 induced HCC827 cell apoptosis by regulating the expression of BCL-2 family proteins. Further study revealed that TPD7 could down-regulate the phosphorylation of EGFR and downstream members. TPD7 might present a potential EGFR inhibitor in the treatment of NSCLC.

Tumor-Derived Exosomes Regulate Apoptosis of CD45+EpCAM+ Cells in Lung Cancer.

Lung cancer has the highest mortality rate among human cancers, and the majority of deaths result from metastatic spread. The tumor microenvironment plays an important role in suppressing the immune surveillance and elimination of tumor cells. A few studies have reported the presence of CD45+EpCAM+ double-positive cells in cancer, but the underlying mechanism remains unclear with respect to how these cells originate and their function in cancer biology. In this study, we analyzed 25 lung tumor samples. We confirmed the presence of CD45+EpCAM+ cells in lung cancer, and these cells exhibited higher apoptosis than CD45+EpCAM- cells. Using co-culture of lung cancer cell-derived exosomes with healthy donor peripheral blood mononuclear cells, we recapitulated CD45+EpCAM+ cell formation and increased apoptosis that occurs in patients with primary lung cancer. Further analysis suggested that microRNAs in lung cancer cell-derived exosomes may alter the gene expression profile of CD45+EpCAM+ cells, resulting in elevated TP53 expression and increased apoptosis. To our knowledge, this is the first report of cancer cell-derived exosomes that can inhibit the immune system by promoting immune cell apoptosis.

C1orf74 positively regulates the EGFR/AKT/mTORC1 signaling in lung adenocarcinoma cells.

Background: Lung adenocarcinoma (LUAD) is a major type of lung cancer with poor prognosis and low 5-year survival rate, which urgently needs further investigation in order to elucidate its mechanisms completely and discover novel therapeutic targets. C1orf74 is a novel protein with unknown function either in normal cells or cancer cells. The aim of this study is to investigate the expression and function of C1orf74 in LUAD cells. Methods: The expression of C1orf74 in LUAD was analyzed using the LUAD datasets from public databases. The prognostic value of C1orf74 in LUAD was analyzed using Kaplan-Meier Plotter. C1orf74 expression in LUAD cell line A549, H1993 and HCC827 was silenced using small interfering RNA, and then the effects of C1orf74 knockdown on proliferation, migration and invasion of LUAD cells were detected by colony formation assay and Transwell assay, the role of C1orf74 in EGFR/AKT/mTORC1 signaling pathway was examined by Western blot, and the function of C1orf74 in cell cycle was detected by flow cytometry. Results: The results of LUAD clinical data showed that C1orf74 was upregulated in LUAD tissues, and its high expression was associated with poor prognosis. The results from cultured LUAD cells demonstrated that C1orf74 knockdown inhibited cell proliferation, migration and invasion, but induced cell cycle arrest and autophagy. Moreover, C1orf74 knockdown suppressed EGFR/AKT/mTORC1 signaling in LUAD cells. In conclusion, the present study revealed that C1orf74 is upregulated in LUAD tissues and plays an oncogenic role in LUAD, and that C1orf74 positively regulates cell proliferation and mobility through the EGFR/AKT/mTORC1 signaling pathway in LUAD cells.

Synergistic Effect of HAD-B1 and Afatinib Against Gefitinib Resistance of Non-Small Cell Lung Cancer.

In epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC), acquired resistance to EGFR tyrosine kinase inhibitors (TKI) leads to disease progression. Strategies to overcome the resistance are required in treatment for advanced lung cancer. In this study, we investigated the therapeutic effect of afatinib and HangAmDan-B1 (HAD-B1) co-administration in gefitinib-resistant NSCLC using HCC827-GR, NSCLC cell line with gefitinib resistance, and the HCC827-GR cell implanted mouse model. HAD-B1 consists of 4 herbs, Panax notoginseng Radix, Cordyceps militaris, Panax ginseng C. A. Mey, and Boswellia carteri Birdwood, and has been reported to be effective in patients with advanced lung cancer in clinical practice. Our findings demonstrated that HAD-B1 combined with afatinib markedly inhibited cell proliferation and induced apoptosis compared to afatinib monotherapy and HAD-B1 monotherapy. Inhibition of HCC827-GR cell proliferation by HAD-B1 occurred through MET amplification and reduced phosphorylation, and the synergistic effect of afatinib and HAD-B1 induced cell cycle arrest and apoptosis in HCC827-GR cells via the downregulation of ERK and mTOR signaling pathways. In hematology and biochemistry tests, HAD-B1 alleviated the toxicity of tumor. In conclusion, HAD-B1 combined with afatinib would be a promising therapeutic strategy for NSCLC with EGFR-TKI resistance.

[Down-regulation of HOTAIR Reverses the Resistance of Gefitinib in HCC827 Cells by Increasing the Expression of PTEN].

BACKGROUND: Lung cancer is the most common cancer worldwide with the highest morbidity and mortality, in which the non-small cell lung cancer accounts for 80% of all cases. The expression of (HOX transcript antisense RNA) HOTAIR were abnormal in a variety of tumor tissues and is involved in the regulation of the occurrence and development of lung cancer. The purpose of this study is to investigate the effect and mechanism of down-regulation of HOTAIR on gefitinib resistance of lung adenocarcinoma HCC827 cells by targeting PTEN. METHODS: The HOTAIR downstream target gene was predicted by bioinformatics database. The small interfering RNAs (siRNA) which is corresponding to HOTAIR was transfected using Lipofectamine™ 2000. Quantitative real-time PCR (RT-qPCR) and Western blot were used to detect the expression of HOTAIR, PTEN, PI3K and AKT in HCC827 and HCC827GR cells. MTT assay was used to detect the changes in drug resistance of HCC827GR cells. Flow cytometry analysis were used to test the cell proliferation and the rate of apoptosis. RESULTS: The expression of HOTAIR increased in HCC827GR and the serum of NSCLC patients with gefitinib resistance (P<0.05). Transfection of HOTAIR siRNA decreased the expression of HOTAIR (P<0.05), and increased the expressions of PTEN (P<0.05), while the expression of PI3K and AKT were decreased (P<0.05). Compared with the blank control group, down-regulation of HOTAIR increased the sensitivity of HCC827GR cells to gefitinib. The cell proliferation ability was decreased and the apoptosis was promoted apparently (P<0.05). CONCLUSIONS: Down-regulation of HOTAIR can suppress the cell growth and promote the apoptosis, and it can reverse the resistance of HCC827GR cells to gefitinib. Its potential mechanism may be related with the targeting of PTEN/PI3K/AKT pathway.

[Expression of Acetaldehyde Dehydrogenase in Gefitinib-resistant Human Lung Adenocarcinoma HCC-827/GR Cells].

BACKGROUND: Tumor recurrence and drug resistance are the main causes of death in tumor patients. The family of acetaldehyde dehydrogenase (ALDH) is closely related to the proliferation, migration, invasion and resistance of tumor cells, and different ALDH subtypes are expressed in different tumor cells. The aim of this study is to elucidate the ALDH subtype in human lung adenocarcinoma HCC-827/GR cells, which resistant to the gefitinib. METHODS: The human lung adenocarcinoma HCC-827 cells were used to generate the gefitinib-resistant HCC-827/GR cells; the expression of ALDH subtype in either HCC-827 or HCC-827/GR was detected by flow cytometry; The proliferative capacity and sensitivity to gefitinib of hcc-827/GR cells were analyzed by MTT assay before and after treatment with 100 µmol/L diethyllaminaldehyde (DEAB); Real-time quantitative PCR was used to detect the expression of ALDH subtypes at mRNA levels in hcc-827 cells and hcc-827/GR cells. RESULTS: Compared with HCC-827 cells, the positive rate of ALDH in HCC-827/GR cells increased. The proliferation ability of HCC-827/GR cells decreased after treatment with 100 µmol/L DEAB. Compared with HCC-827 cells, the expression of ALDH1A1 and ALDH1L1 mRNA was increased in hcc-827/GR cells, but the ALDH3B2 expression was decreased. CONCLUSIONS: ALDH might be used as a molecular biomarker to test the gefitinib-resistant to lung adenocarcinoma cancer cells, and the ALDH1A1 may play a role in gefitinib resistance in lung cancer.

Reduced expression levels of PTEN are associated with decreased sensitivity of HCC827 cells to icotinib.

The clinical resistance of non-small cell lung cancer (NSCLC) to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has been linked to EGFR T790M resistance mutations or MET amplifications. Additional mechanisms underlying EGFR-TKI drug resistance remain unclear. The present study demonstrated that icotinib significantly inhibited the proliferation and increased the apoptosis rate of HCC827 cells; the cellular mRNA and protein expression levels of phosphatase and tensin homolog (PTEN) were also significantly downregulated. To investigate the effect of PTEN expression levels on the sensitivity of HCC827 cells to icotinib, PTEN expression was silenced using a PTEN-specific small interfering RNA. The current study identified that the downregulation of PTEN expression levels may promote cellular proliferation in addition to decreasing the apoptosis of HCC827 cells, and may reduce the sensitivity of HCC827 cells to icotinib. These results suggested that reduced PTEN expression levels were associated with the decreased sensitivity of HCC827 cells to icotinib. Furthermore, PTEN expression levels may be a useful marker for predicting icotinib resistance and elucidating the resistance mechanisms underlying EGFR-mutated NSCLC.

Structure-activity study of quinazoline derivatives leading to the discovery of potent EGFR-T790M inhibitors.

We have developed a series of 6, 7-disubstituted-4-(arylamino) quinazoline derivatives that functioned as irreversible EGFR inhibitors, and these compounds exhibited excellent enzyme inhibition potency. As compared with afatinib, some of them showed significantly enhanced activities towards H1975 cells (EGFR-T790M). Furthermore, the optimized compounds 7q and 8f also demonstrated good pharmacokinetic profiles, oral bioavailability as well as excellent in vivo efficacy in H1975 and HCC827 xenografts at a non-toxic dose. Based on the improved safety and efficacy against EGFR-T790M resistance, 7q and 8f are promising candidates for further studies.

SOX2 expression is an early event in a murine model of EGFR mutant lung cancer and promotes proliferation of a subset of EGFR mutant lung adenocarcinoma cell lines.

OBJECTIVES: Primary and acquired resistance to EGFR TKIs in EGFR mutant lung cancer occurs primarily through secondary mutations in EGFR or Met amplification. Drug resistance can also be mediated by expression of pluripotency transcription factors, such as OCT4, SOX2 and NANOG that decrease terminal differentiation. In this study, we investigated the expression and role of SOX2 in model systems of EGFR mutant tumors. MATERIALS AND METHODS: Immunoblotting or immunohistochemistry was used to assess expression of pluripotency transcription factors in lungs of transgenic mice or in human NSCLC cell lines. Expression of SOX2 was reduced by shRNA knockdown, and response to erlotinib and cellular proliferation were assessed. RESULTS AND CONCLUSION: Induction of mutant EGFR in transgenic CCSP-rtTA/TetO-EGFR(L858R/T790M) mice correlated with increased OCT4 and SOX2 expression in lung tissue prior to tumor development. Established lung tumors retained SOX2 expression. To assess a role for SOX2 in tumorigenesis, a panel of NSCLC cell lines with activating EGFR mutations was assessed for SOX2 expression. Two of six cell lines with mutant EGFR showed detectable SOX2 levels, suggesting SOX2 expression did not correlate with EGFR mutation status. To assess the role of SOX2 in these cell lines, HCC827 and H1975 cells were infected with lentivirus containing SOX2 shRNA. Knockdown of SOX2 decreased proliferation in both cell lines and increased sensitivity to erlotinib in HCC827 cells. Because constitutive activation of the PI3K/Akt pathway is associated with EGFR TKI resistance, cells were treated with PI3K/AKT inhibitors and expression of SOX2 was examined. PI3K/Akt inhibitors decreased SOX2 expression in a time-dependent manner. These data suggest targeting SOX2 may provide therapeutic benefit in the subset of EGFR-mutant tumors with high constitutive levels of SOX2, and that until more direct means of inhibiting SOX2 are developed, PI3K/Akt inhibitors might be useful to inhibit SOX2 in EGFR TKI resistant tumors.