The potential role of mTOR inhibitors in non-small cell lung cancer

Impact of genetic variants in the solute carrier (SLC) genes encoding drug uptake transporters on the response to anticancer chemotherapy

Cancer drug resistance constitutes a severe limitation for the satisfactory outcome of these patients. This is a complex problem due to the co-existence in cancer cells of multiple and synergistic mechanisms of chemoresistance (MOC). These mechanisms are accounted for by the expression of a set of genes included in the so-called resistome, whose effectiveness often leads to a lack of response to pharmacological treatment. Additionally, genetic variants affecting these genes further increase the complexity of the question. This review focuses on a set of genes encoding members of the transportome involved in drug uptake, which have been classified into the MOC-1A subgroup of the resistome. These proteins belong to the solute carrier (SLC) superfamily. More precisely, we have considered here several members of families SLC2, SLC7, SLC19, SLC22, SLCO, SLC28, SLC29, SLC31, SLC46, and SLC47 due to the impact of their expression and genetic variants in anticancer drug uptake by tumor cells or, in some cases, general bioavailability. Changes in their expression levels and the appearance of genetic variants can contribute to the Darwinian selection of more resistant clones and, hence, to the development of a more malignant phenotype. Accordingly, to address this issue in future personalized medicine, it is necessary to characterize both changes in resistome genes that can affect their function. It is also essential to consider the time-dependent dimension of these features, as the genetic expression and the appearance of genetic variants can change during tumor progression and in response to treatment.

Pseudolaric acid B suppresses NSCLC progression through the ROS/AMPK/mTOR/autophagy signalling pathway

Pseudolaric acid B (PAB), an acid isolated from the roots of Pseudolarix kaempferi gorden, has shown antitumour effects through multiple mechanisms of action. The objective of this study was to investigate the anticancer effect of PAB on non-small cell lung cancer (NSCLC) and its underlying mechanism. In our experiments, we observed that PAB decreased cell viability, inhibited colony formation, induced cell cycle arrest, impeded scratch healing, and increased apoptosis in H1975 and H1650 cells. Additionally, PAB treatment enhanced the fluorescence intensity of MDC staining in NSCLC cells, upregulated the protein expression of microtubule-associated protein light chain 3 II (LC3 II), and downregulated the expression of sequestosome 1 (SQSTM1/P62). Combined treatment with PAB and chloroquine (CQ) increased the protein expression levels of LC3 II and P62 while decreasing the apoptosis of H1975 and H1650 cells. Moreover, treatment with PAB led to significant mTOR inhibition and AMPK activation. PAB combined with compound C (CC) inhibited autophagy and apoptosis. Furthermore, PAB treatment increased intracellular reactive oxygen species (ROS) levels in NSCLC cells, which correlated with the modulation of the AMPK/mTOR signalling pathway and was associated with autophagy and apoptosis. Finally, we validated the antitumour growth activity and mechanism of PAB in vivo using athymic nude mice bearing H1975 tumour cells. In conclusion, our findings suggest that PAB can induce apoptosis and autophagic cell death in NSCLC through the ROS-triggered AMPK/mTOR signalling pathway, making it a promising candidate for future NSCLC treatment.

Bioactive PI3-kinase/Akt/mTOR Inhibitors in Targeted Lung Cancer Therapy

One of the central signaling pathways with a regulatory effect on cell proliferation and survival is Akt/mTOR. In many human cancer types, for instance, lung cancer, the overexpression of Akt/mTOR has been reported. For this reason, either targeting cancer cells by synthetic or natural products affecting the Akt/mTOR pathway down-regulation is a useful strategy in cancer therapy. Direct inhibition of the signaling pathway or modulation of each related molecule could have significant feedback on the growth and proliferation of cancer cells. A variety of secondary metabolites has been identified to directly inhibit the AKT/mTOR signaling, which is important in the field of drug discovery. Naturally occurring nitrogenous and phenolic compounds can emerge as two pivotal classes of natural products possessing anticancer abilities. Herein, we have summarized the alkaloids and flavonoids for lung cancer treatment together with all the possible mechanisms of action relying on the Akt/mTOR pathway down-regulation. This review suggested that in search of new drugs, phytochemicals could be considered as promising scaffolds to be developed into efficient drugs for the treatment of cancer. In this review, the terms "Akt/mTOR", "Alkaloid", "flavonoid", and "lung cancer" were searched without any limitation in search criteria in Scopus, PubMed, Web of Science, and Google scholar engines.

KRAS-Mutant Non-Small Cell Lung Cancer: An Emerging Promisingly Treatable Subgroup

Lung cancer, the leading cause of cancer-related deaths worldwide, can be classified into small cell lung cancer and non-small cell lung cancer (NSCLC). NSCLC is the most common histological type, accounting for 85% of all lung cancers. Kirsten rat sarcoma viral oncogene (KRAS) mutations, common in NSCLC, are associated with poor prognosis, likely due to poor responses to most systemic therapies and lack of targeted drugs. The latest published clinical trial data on new small-molecule KRAS G12C inhibitors, AMG510 and MRTX849, indicate that these molecules may potentially help treat KRAS-mutant NSCLC. Simultaneously, within the immuno-therapeutic process, immune efficacy has been observed in those patients who have KRAS mutations. In this article, the pathogenesis, treatment status, progress of immunotherapy, and targeted therapy of KRAS-mutant NSCLC are reviewed.

High in vitro and in vivo synergistic activity between mTORC1 and PLK1 inhibition in adenocarcinoma NSCLC

Significant rational is available for specific targeting of PI3K/AKT/mTOR pathway in the treatment of non-small cell lung cancer (NSCLC). However, almost all clinical trials that have evaluated Pi3K pathway-based monotherapies/combinations did not observe an improvement of patient’s outcome. The aim of our study was therefore to define combination of treatment based on the determination of predictive markers of resistance to the mTORC1 inhibitor RAD001/Everolimus. An in vivo study showed high efficacy of RAD001 in NSCLC Patient-Derived Xenografts (PDXs). When looking at biomarkers of resistance by RT-PCR study, three genes were found to be highly expressed in resistant tumors, i.e., PLK1, CXCR4, and AXL. We have then focused our study on the combination of RAD001 + Volasertib, a PLK1 inhibitor, and observed a high antitumor activity of the combination in comparison to each monotherapy; similarly, a clear synergistic effect between the two compounds was found in an in vitro study. Pharmacodynamics study demonstrated that this synergy was due to (1) tumor vascularization decrease, increase of the HIF1 protein expression and decrease of the intracellular pH, and (2) decrease of the Carbonic Anhydrase 9 (CAIX) protein that could not correct intracellular acidosis. In conclusion, all these preclinical data strongly suggest that the inhibition of mTORC1 and PLK1 proteins may be a promising therapeutic approach for NSCLC patients.

Marine-Derived Natural Products as ATP-Competitive mTOR Kinase Inhibitors for Cancer Therapeutics

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase portraying a quintessential role in cellular proliferation and survival. Aberrations in the mTOR signaling pathway have been reported in numerous cancers including thyroid, lung, gastric and ovarian cancer, thus making it a therapeutic target. To attain this objective, an in silico investigation was designed, employing a pharmacophore modeling approach. A structure-based pharmacophore (SBP) model exploiting the key features of a selective mTOR inhibitor, Torkinib directed at the ATP-binding pocket was generated. A Marine Natural Products (MNP) library was screened using SBP model as a query. The retrieved compounds after consequent drug-likeness filtration were subjected to molecular docking with mTOR, thus revealing four MNPs with better scores than Torkinib. Successive refinement via molecular dynamics simulations demonstrated that the hits formed crucial interactions with key residues of the pocket. Furthermore, the four identified hits exhibited good binding free energy scores through MM-PBSA calculations and the subsequent in silico toxicity assessments displayed three hits deemed essentially non-carcinogenic and non-mutagenic. The hits presented in this investigation could act as potent ATP-competitive mTOR inhibitors, representing a platform for the future discovery of drugs from marine natural origin.

Role of crosstalk between STAT3 and mTOR signaling in driving sensitivity to chemotherapy in osteosarcoma cell lines

Osteosarcoma (OS) is a malignant bone neoplasm, mostly occurring in pediatric patients. OS is characterized by a highly aggressive and metastatically active tumor. Chemotherapy followed by surgical excision is the treatment of choice but is often associated with both chemoresistance and relapse. Hence, it is important to develop further understanding of OS pathogenesis and identify potential therapeutic targets. Both the signal transducer and activator of transcription 3 (STAT3) and mammalian target of rapamycin (mTOR) have been implicated in OS pathogenesis. Crosstalk between mTOR and STAT3 signaling has been shown to regulate hypoxia-induced angiogenesis in other diseases. In this study, we determined using OS cell lines if there is a crosstalk between these two pathways and how that impacts sensitivity to treatment with Rapamycin. OS cell lines exhibited differential sensitivity to mTOR inhibitor Rapamycin. Evaluation of phosphorylated STAT3 showed that in Rapamycin-sensitive 143B cells, the inhibitor decreased phosphorylation of STAT3 at Y705, but not at S727 whereas, in Rapamycin-resistant U2OS cells, the inhibitor decreased S727 phosphorylation but not Y705. However, knockdown of STAT3 in U2OS cells made them sensitive to Rapamycin. Immunofluorescence (IF) analysis showed that mTOR is constitutively activated in the 143B cells but is suppressed in the U2OS cells, indicating that this might be their reason for being resistant to Rapamycin. Both cell lines were sensitive to treatment with the STAT3 inhibitor Napabucasin (NP). Treatment with NP inhibited STAT3 activation at Y705 and additionally inhibited mTOR activation, indicating crosstalk between STAT3 and mTOR signaling pathways. Rapamycin could effectively prevent lung metastasis in an orthotropic OS mice model using 143B cells. However, Rapamycin could not inhibit lung metastasis in mice injected with U2OS cells. The STAT3 inhibitor NP attenuated lung metastasis with the U2OS cells. Our results thus established yet undefined crosstalk of STAT3 and mTOR signaling pathways in OS and highlight the possibility of using mTOR inhibitors for treatment in patients with OS.

Emerging role of phytochemicals in targeting predictive, prognostic, and diagnostic biomarkers of lung cancer

Lung-cancer is the foremost cause of cancer in humans worldwide, of which 80-85% cases are composed of non-small cell lung carcinoma. All treatment decisions depend on the pattern of biomarkers selection to enhance the response to the targeted therapies. Although advanced treatments are available for lung-cancer, the disease treatment remains not adequate. There are several synthetic chemotherapeutic agents available for the treatment of lung cancer. However, due to their toxic effect, survival rate is still 15-18%. Besides, medicinal plants are a huge reservoir of natural products that provide protective effects against lung cancer. Likewise, successful studies of potential phytochemicals in targeting lung-cancer biomarkers have created a novel paradigm for the discovery of potent drugs against lung-cancer. Hence, to defeat severe toxicity and resistance towards the synthetic drugs, detailed studies are required regarding the available phytochemicals and targets responsible for the treatment of lung-cancer. The present review provides a comprehensive information about the lung-cancer biomarkers under the classification of predictive, prognostic, and diagnostic type. Moreover, it discusses and enlists the phytochemicals with mode of action against different biomarkers, effective doses in in vitro, in vivo, and clinical studies, the limitations associated with usage of phytochemicals as a drug to prevent/cure lung-cancer and the latest techniques employed to overcome such issues.

PaccMann: a web service for interpretable anticancer compound sensitivity prediction

The identification of new targeted and personalized therapies for cancer requires the fast and accurate assessment of the drug efficacy of potential compounds against a particular biomolecular sample. It has been suggested that the integration of complementary sources of information might strengthen the accuracy of a drug efficacy prediction model. Here, we present a web-based platform for the Prediction of AntiCancer Compound sensitivity with Multimodal Attention-based Neural Networks (PaccMann). PaccMann is trained on public transcriptomic cell line profiles, compound structure information and drug sensitivity screenings, and outperforms state-of-the-art methods on anticancer drug sensitivity prediction. On the open-access web service (https://ibm.biz/paccmann-aas), users can select a known drug compound or design their own compound structure in an interactive editor, perform in-silico drug testing and investigate compound efficacy on publicly available or user-provided transcriptomic profiles. PaccMann leverages methods for model interpretability and outputs confidence scores as well as attention heatmaps that highlight the genes and chemical sub-structures that were more important to make a prediction, hence facilitating the understanding of the model's decision making and the involved biochemical processes. We hope to serve the community with a toolbox for fast and efficient validation in drug repositioning or lead compound identification regimes.

MiRNA therapeutics based on logic circuits of biological pathways

BACKGROUND

In silico experiments, with the aid of computer simulation, speed up the process of in vitro or in vivo experiments. Cancer therapy design is often based on signalling pathway. MicroRNAs (miRNA) are small non-coding RNA molecules. In several kinds of diseases, including cancer, hepatitis and cardiovascular diseases, they are often deregulated, acting as oncogenes or tumor suppressors. miRNA therapeutics is based on two main kinds of molecules injection: miRNA mimics, which consists of injection of molecules that mimic the targeted miRNA, and antagomiR, which consists of injection of molecules inhibiting the targeted miRNA. Nowadays, the research is focused on miRNA therapeutics. This paper addresses cancer related signalling pathways to investigate miRNA therapeutics.

RESULTS

In order to prove our approach, we present two different case studies: non-small cell lung cancer and melanoma. KEGG signalling pathways are modelled by a digital circuit. A logic value of 1 is linked to the expression of the corresponding gene. A logic value of 0 is linked to the absence (not expressed) gene. All possible relationships provided by a signalling pathway are modelled by logic gates. Mutations, derived according to the literature, are introduced and modelled as well. The modelling approach and analysis are widely discussed within the paper. MiRNA therapeutics is investigated by the digital circuit analysis. The most effective miRNA and combination of miRNAs, in terms of reduction of pathogenic conditions, are obtained. A discussion of obtained results in comparison with literature data is provided. Results are confirmed by existing data.

CONCLUSIONS

The proposed study is based on drug discovery and miRNA therapeutics and uses a digital circuit simulation of a cancer pathway. Using this simulation, the most effective combination of drugs and miRNAs for mutated cancer therapy design are obtained and these results were validated by the literature. The proposed modelling and analysis approach can be applied to each human disease, starting from the corresponding signalling pathway.

hsa_circ_0006168 sponges miR-100 and regulates mTOR to promote the proliferation, migration and invasion of esophageal squamous cell carcinoma

Circle RNAs (circRNAs) are the novel noncoding RNAs with the covalent closed-loop structure, which play a crucial role in a variety of pathological processes, including cancer. Nevertheless, the expression profiles and functions of circRNAs in esophageal squamous cell cancer (ESCC) remain largely unknown. In this paper, 10 pairs of ESCC tissues were utilized to screen the circRNA expression profiles by means of microarray assay; further, a novel circular RNA named hsa_circ_0006168 was investigated. Meanwhile, the expression of hsa_circ_0006168 was measured in 52 ESCC tissues and in cell lines. Our results suggested that, hsa_circ_0006168 was remarkably increased not only in ESCC tissues but also in cell lines compared with those in normal cases. Besides, high hsa_circ_0006168 expression was positively connected with lymph node metastasis and TNM stage of ESCC patients. In vitro, the proliferation, invasion and migration capacities of ESCC cells were suppressed through down-regulating hsa_circ_0006168 expression. Besides, RNase R digestion assay confirmed that hsa_circ_0006168 was more stable than its linear CNOT6L mRNA form. Moreover, nuclear and cytoplasmic fraction assay indicated that hsa_circ_0006168 was mainly distributed in the cytoplasm of Kyse450 and TE13 cells. Mechanically, it was discovered in this study that hsa_circ_0006168 might regulate the expression of Mammalian Target of Rapamycin (mTOR) by sponging microRNA-100 (miR-100). Taken together, hsa_circ_0006168 can promote ESCC proliferation, migration and invasion through the competing endogenous RNA (ceRNA) mechanism, which has been first confirmed in our results. In ESCC, hsa_circ_0006168 can serve as a potential diagnostic biomarker and therapeutic target.

MiR-3188 Inhibits Non-small Cell Lung Cancer Cell Proliferation Through FOXO1-Mediated mTOR-p-PI3K/AKT-c-JUN Signaling Pathway

This study investigated the role of miR-3188 on the proliferation of non-small cell lung cancer cells and its relationship to FOXO1-modulated feedback loop. Two non-small cell lung cancer (NSCLC) cell lines A549 and H1299 were used. RNA silencing was achieved by lentiviral transfection. Cell proliferation was assessed by immunohistochemical staining of Ki67 and PCNA, Edu incorporation, and colony formation assay. Western blotting was used to examine expression of FOXO1, mTOR, p-mTOR, CCND1, p21, c-JUN, AKT, pAKT, PI3K, p-PI3K, and p27 proteins. It was found that miR-3188 reduced cell proliferation in NSCLC cells. Molecular analyses indicated that the effect of mammalian target of rapamycin (mTOR) was directly mediated by miR-3188, leading to p-PI3K/p-AKT/c-JUN inactivation. The inhibition of this signaling pathway further caused cell-cycle suppression. Moreover, FOXO1 was found to be involved in regulating the interaction of miR-3188 and mTOR through p-PI3K/p-AKT/c-JUN signaling pathway. Taken together, our study demonstrated that miR-3188 interacts with mTOR and FOXO1 to inhibit NSCLC cell proliferation through a mTOR-p-PI3K/AKT-c-JUN signaling pathway. Therefore, miR-3188 might be a potential target for the treatment of NSCLC.

A novel computational approach for drug repurposing using systems biology

Motivation

Identification of novel therapeutic effects for existing US Food and Drug Administration (FDA)-approved drugs, drug repurposing, is an approach aimed to dramatically shorten the drug discovery process, which is costly, slow and risky. Several computational approaches use transcriptional data to find potential repurposing candidates. The main hypothesis of such approaches is that if gene expression signature of a particular drug is opposite to the gene expression signature of a disease, that drug may have a potential therapeutic effect on the disease. However, this may not be optimal since it fails to consider the different roles of genes and their dependencies at the system level.

Results

We propose a systems biology approach to discover novel therapeutic roles for established drugs that addresses some of the issues in the current approaches. To do so, we use publicly available drug and disease data to build a drug-disease network by considering all interactions between drug targets and disease-related genes in the context of all known signaling pathways. This network is integrated with gene-expression measurements to identify drugs with new desired therapeutic effects based on a system-level analysis method. We compare the proposed approach with the drug repurposing approach proposed by Sirota et al. on four human diseases: idiopathic pulmonary fibrosis, non-small cell lung cancer, prostate cancer and breast cancer. We evaluate the proposed approach based on its ability to re-discover drugs that are already FDA-approved for a given disease.

Availability and implementation

The R package DrugDiseaseNet is under review for publication in Bioconductor and is available at https://github.com/azampvd/DrugDiseaseNet.

Supplementary information

Supplementary data are available at Bioinformatics online.

Bioreducible Poly(Amino Ethers) Based mTOR siRNA Delivery for Lung Cancer

PURPOSE

Lung cancer is one of the leading causes of deaths in the United States, but currently available therapies for lung cancer are associated with reduced efficacy and adverse side effects. Small interfering RNA (siRNA) can knock down the expression of specific genes and result in therapeutic efficacy in lung cancer. Recently, mTOR siRNA has been shown to induce apoptosis in NSCLC cell lines but its use is limited due to poor stability in biological conditions.

METHODS

In this study, we modified an aminoglyocisde-derived cationic poly (amino-ether) by introducing a thiol group using Traut's reagent to generate a bio-reducible modified-poly (amino-ether) (mPAE). The mPAE polymer was used to encapsulate mTOR siRNA by nanoprecipitation method, resulting in the formation of stable and bio-reducible nanoparticles (NPs) which possessed an average diameter of 114 nm and a surface charge of approximately +27 mV.

RESULTS

The mTOR siRNA showed increased release from the mTS-mPAE NPs in the presence of 10 mM glutathione (GSH). The polymeric mTS-mPAE-NPs were also capable of efficient gene knockdown (60 and 64%) in A549 and H460 lung cancer cells, respectively without significant cytotoxicity at 30 μg/ml concentrations. The NPs also showed time-dependent cellular uptake for up to 24 h as determined using flow cytometry. Delivery of the siRNA using these NPs also resulted in significant inhibition of A549 and H460 cell proliferation in vitro, respectively.

CONCLUSIONS

The results demonstrate that the mPAE polymer based NPs show strong potential for siRNA delivery to lung cancer cells. It is anticipated that future modification can help improve the efficacy of nucleic acid delivery, leading to higher inhibition of lung cancer growth in vitro and in vivo.

mTOR: An attractive therapeutic target for osteosarcoma?

Osteosarcoma (OS) is a common primary malignant bone tumor with high morbidity and mortality in children and young adults. How to improve poor prognosis of OS due to resistance to chemotherapy remains a challenge. Recently, growing findings show activation of mammalian target of rapamycin (mTOR), is associated with OS cell growth, proliferation, metastasis. Targeting mTOR may be a promising therapeutic approach for treating OS. This review summarizes the roles of mTOR pathway in OS and present research status of mTOR inhibitors in the context of OS. In addition, we have attempted to discuss how to design a better treatment project for OS by combining mTOR inhibitor with other drugs.

mTOR regulates proteasomal degradation and Dp1/E2F1- mediated transcription of KPNA2 in lung cancer cells

Karyopherin subunit alpha-2 (KPNA2) is overexpressed in various human cancers and is associated with cancer invasiveness and poor prognosis in patient. Nevertheless, the regulation of KPNA2 expression in cancers remains unclear. We herein applied epidermal growth factor (EGF) and five EGF receptor (EGFR)-related kinase inhibitors to investigate the role of EGFR signaling in KPNA2 expression in non-small cell lung cancer (NSCLC) cells. We found that EGFR signaling, particularly the mammalian target of rapamycin (mTOR) activity was positively correlated with KPNA2 protein levels in NSCLC cells. The mTOR inhibitors and mTOR knockdown reduced the protein and mRNA levels of KPNA2 in NSCLC and breast cancer cells. Specifically, rapamycin treatment induced proteasome-mediated KPNA2 protein decay and attenuated the transcriptional activation of KPNA2 by decreasing Dp1/E2F1 level in vivo. Immunoprecipitation assay further revealed that KPNA2 physically associated with the phospho-mTOR/mTOR and this association was abolished by rapamycin treatment. Collectively, our results show for the first time that KPNA2 is transcriptionally and post-translationally regulated by the mTOR pathway and provide new insights into targeted therapy for NSCLC.

Portal branch ligation does not counteract the inhibiting effect of temsirolimus on extrahepatic colorectal metastatic growth

The mTor-inhibitor temsirolimus (TEM) has potent anti-tumor activities on extrahepatic colorectal metastases. Treatment of patients with advanced disease may require portal branch ligation (PBL). While PBL can induce intrahepatic tumor growth, the effect of PBL on extrahepatic metastases under TEM treatment is unknown. Therefore, we analyzed the effects of TEM treatment on extrahepatic metastases during PBL-associated liver regeneration. GFP-transfected CT26.WT colorectal cancer cells were implanted into the dorsal skinfold chamber of BALB/c-mice. Mice were randomized to four groups (n = 8). One was treated daily with TEM (1.5 mg/kg), PBS-treated animals served as controls. Another group underwent PBL of the left liver lobe and received daily TEM treatment. Animals with PBL and PBS treatment served as controls. Tumor vascularization and growth as well as tumor cell migration, proliferation and apoptosis were studied over 14 days. In non-PBL animals TEM treatment inhibited tumor cell proliferation as well as vascularization and growth of the extrahepatic metastases. PBL did not influence tumor cell engraftment, vascularization and metastatic growth. Of interest, TEM treatment significantly reduced tumor cell engraftment, neovascularization and metastatic groth also after PBL. PBL does not counteract the inhibiting effect of TEM on extrahepatic colorectal metastatic growth.

A phase Ib trial of continuous once-daily oral afatinib plus sirolimus in patients with epidermal growth factor receptor mutation-positive non-small cell lung cancer and/or disease progression following prior erlotinib or gefitinib

OBJECTIVES

Dysregulation of the downstream PI3K/AKT/mTOR signaling pathway is a proposed mechanism of resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). We investigated safety and antitumor activity of afatinib plus sirolimus as a potential combination to reverse acquired resistance to EGFR-TKIs in a phase IB trial in patients with EGFR mutation-positive non-small-cell lung cancer (EGFR mut NSCLC) and/or disease progression following prior erlotinib/gefitinib.

MATERIALS AND METHODS

Patients with EGFR mut NSCLC and/or disease progression following at least prior erlotinib/gefitinib were included in the trial. The primary endpoint was incidence of dose-limiting toxicities (DLT) to determine the maximum tolerated dose (MTD). Four initial dose cohorts were proposed to evaluate DLTs. Other endpoints included tumor response, safety, progression-free survival (PFS) and pharmacokinetics.

RESULTS

Thirty-nine patients received afatinib and sirolimus. Additional dose cohorts were added since the second cohort (afatinib 40mg/day and sirolimus 5mg/day) was considered to have excessive toxicity. All patients experienced adverse events (AE) [grade 3: 66.7%; serious AE: 56.4%]. The most frequent AEs were diarrhea (94.9%), mucosal inflammation (64.1%), asthenia (53.8%) and rash (53.8%). Discontinuations and dose reduction due to AEs occurred in 23.1% and 25.6% of patients. MTD was determined as afatinib 30mg and sirolimus 1mg. Responses were observed in 5 patients (12.8%) [2 (5.1%) with confirmed partial response (PR); 3 (7.7%) with unconfirmed PR], and stable disease in 18 patients (46.2%). Four of the 5 responses were at doses above MTD. PFS at 6 months was estimated in 33.3% (median PFS 3.4 months). Pharmacokinetic parameters of afatinib and sirolimus were similar after single administration or in combination.

CONCLUSION

The combination of afatinib and sirolimus showed lower responses than expected. Together with increased AEs and poor tolerability, this precludes clinical use and further clinical development of this combination. No pharmacokinetic interactions were observed. CLINICALTRIALS.

GOV IDENTIFIER

NCT00993499.

Expression of mTORC1/2-related proteins in primary and brain metastatic lung adenocarcinoma

Brain metastases (BMs) are common complications of adenocarcinomas (ADCs) of the lung and are associated with a poor prognosis. Although an increasing amount of data indicates that dysregulated activity of mammalian target of rapamycin (mTOR) can influence the metastatic potential of various tumors, the role of mTOR complexes in the development of BMs from ADCs of the lung is largely unknown. To estimate mTOR activity, we studied the expression of mTOR-related proteins (mTORC1: p-mTOR, p-S6; mTORC2: p-mTOR, Rictor) in primary (n=67) and brain metastatic (n=67) lung ADCs, including 15 paired tissue samples, using immunohistochemistry and tissue microarrays. Correlation with clinicopathological parameters was also analyzed. Increased p-mTOR, p-S6, and Rictor expressions were observed in 34%, 33%, and 37% of primary ADCs and in 79%, 70%, and 66% of BMs, respectively. Expression of these markers was significantly higher in BMs as compared with primary carcinomas (P<.0001, P<.0001, P<.001). Rictor expression was significantly higher in primary ADCs of the paired cases with BMs as compared with primary ADCs without BMs (67% versus 28%; P<.01). No other statistically significant correlations were found between mTOR activity and clinicopathological parameters. The increased mTORC1/C2 activity in a subset of pulmonary ADCs and the higher incidence of increased mTORC1/C2 activity in BMs suggest that the immunohistochemistry panel for characterizing mTOR activity and its potential predictive and prognostic role warrants further investigations.

Targeting the KRAS Pathway in Non-Small Cell Lung Cancer

: Lung cancer remains the leading cause of cancer-related deaths worldwide. However, significant progress has been made individualizing therapy based on molecular aberrations (e.g., EGFR, ALK) and pathologic subtype. KRAS is one of the most frequently mutated genes in non-small cell lung cancer (NSCLC), found in approximately 30% of lung adenocarcinomas, and is thus an appealing target for new therapies. Although no targeted therapy has yet been approved for the treatment of KRAS-mutant NSCLC, there are multiple potential therapeutic approaches. These may include direct inhibition of KRAS protein, inhibition of KRAS regulators, alteration of KRAS membrane localization, and inhibition of effector molecules downstream of mutant KRAS. This article provides an overview of the KRAS pathway in lung cancer and related therapeutic strategies under investigation.

IMPLICATIONS FOR PRACTICE

The identification of oncogene-addicted cancers and specific inhibitors has revolutionized non-small cell lung cancer (NSCLC) treatment and outcomes. One of the most commonly mutated genes in adenocarcinoma is KRAS, found in approximately 30% of lung adenocarcinomas, and thus it is an appealing target for new therapies. This review provides an overview of the KRAS pathway and related targeted therapies under investigation in NSCLC. Some of these agents may play a key role in KRAS-mutant NSCLC treatment in the future.

MicroRNA-224 aggrevates tumor growth and progression by targeting mTOR in gastric cancer

Growing evidence suggests that microRNA plays an essential role in the development and metastasis of many tumors, including gastric cancer. Aberrant miR-224 expression has been indicated in tumor growth, the mechanism of miR-224 promoting the proliferation and metastatic ability for gastric cancer remains unclear. Accumulating evidence reports that mTOR signal pathway plays an important role in the cellular process, such as apoptosis, cell growth and proliferation. The goal of the present study was to identify whether miR-224 could inhibit the growth, migration, invasion, proliferation and metastasis of gastric cancer through targeting mTOR expression. Real-time PCR (RT-PCR) was used to quantify miR-224 expression in vitro and in vivo experiments. Luciferase reporter assays were performed to confirm the activity of mTOR pathway, and immunofluorescence staining assay was conducted to observe apoptosis and cell proliferation ability. Bioinformatics as well as cell luciferase function studies distinguished the direct modulation of miR-224 on the 3'-UTR of the mTOR, which leads to the inactivation of apoptosis signaling and the activation of cell proliferation. In addition, inhibition of miR-224 significantly reduced the expression of mTOR and improved caspase-9/3 expression while decreased cyclin D1/2 levels, attenuating gastric cancer cell proliferation. Therefore, the present study revealed the mechanistic links between miR-224 and mTOR in the pathogenesis of gastric cancer through modulation of caspase-9/3 and cyclin D1/2. In addition, targeting miR-224 could serve as a novel strategy for future gastric cancer therapy.

KRAS-Mutant Lung Cancers in the Era of Targeted Therapy

KRAS-mutant lung cancers account for approximately 25% of non-small cell lung carcinomas, thus representing an enormous burden of cancer worldwide. KRAS mutations are clear drivers of tumor growth and are characterized by a complex biology involving the interaction between mutant KRAS, various growth factor pathways, and tumor suppressor genes. While KRAS mutations are classically associated with a significant smoking history, they are also identified in a substantial proportion of never-smokers. These mutations are found largely in lung adenocarcinomas with solid growth patterns and tumor-infiltrating lymphocytes. A variety of tools are available for diagnosis including Sanger sequencing, multiplex mutational hotspot profiling, and next-generation sequencing. The prognostic and predictive roles of KRAS status remain controversial. It has become increasingly clear, however, that KRAS mutations drive primary resistance to EGFR tyrosine kinase inhibition. Until recently, mutant KRAS was not thought of as a clinically-targetable driver in lung cancers. With the expansion of our knowledge regarding the biology of KRAS-mutant lung cancers and the role of MEK and PI3K/mTOR inhibition, the face of targeted therapeutics for this genomic subset of patients is slowly beginning to change.

Galectin-1 is overexpressed in CD133+ human lung adenocarcinoma cells and promotes their growth and invasiveness

Previous studies demonstrated that a subpopulation of cancer cells, which are CD133 positive (CD133+) feature higher invasive and metastatic abilities, are called cancer stem cells (CSCs). By using tumor cells derived from patients with lung adenocarcinoma, we found that galectin-1 is highly overexpressed in the CD133+ cancer cells as compared to the normal cancer cells (CD133-) from the same patients. We overexpressed galectin-1 in CD133- cancer cells and downregulated it in CSCs. We found that overexpression of galectin-1 promoted invasiveness of CD133- cells, while knockdown of galectin-1 suppressed proliferation, colony formation and invasiveness of CSCs. Furthermore, tumor growth was significantly inhibited in CSCs xenografts with knockdown of galectin-1 as compared to CSCs treated with scramble siRNAs. Biochemical studies revealed that galectin-1 knockdown led to the suppression of COX-2/PGE2 and AKT/mTOR pathways, indicating galectin-1 might control the phenotypes of CSCs by regulating these signaling pathways. Finally, a retrospective study revealed that galectin-1 levels in blood circulation negatively correlates with overall survival and positively correlates with lymph node metastasis of the patients. Taken together, these findings suggested that galectin-1 plays a major role on the tumorigenesis and invasiveness of CD133+ cancer cells and might serve as a potential therapeutic target for treatment of human patients with lung adenocarcinoma.

Radiation-induced miR-208a increases the proliferation and radioresistance by targeting p21 in human lung cancer cells

BACKGROUND

Lung cancer has long been the most dangerous malignant tumor among males in both well developed and poorly developed countries. Radiotherapy plays a critical role in the curative management of inoperable non-small cell lung cancer (NSCLC) and is also used as a post-surgical treatment in lung cancer patients. Radioresistance is an important factor that limits the efficacy of radiotherapy for NSCLC patients. Increasing evidence suggests that microRNAs (miRNAs) possess diverse cellular regulatory roles in radiation responses.

METHODS

In this study, we used miRNA microarray technology to identify serum miRNAs that were differentially expressed before and after radiotherapy in lung cancer patients. We further examined the biological function of miR-208a on cell viability, apoptotic death and cell cycle distribution in human lung cancer cells and explored the probable mechanism.

RESULTS

Nine miRNAs, including miR-29b-3p, miR-200a-3p, and miR-126-3p were significantly down-regulated, whereas miR-208a was the only miRNA that was up-regulated in the serum of the patients after radiation treatment (P < 0.05). The expression of miR-208a could be induced by X-ray irradiation in lung cancer cells. Forced expression of miR-208a promoted cell proliferation and induced radioresistance via targeting p21 with a corresponding activation of the AKT/mTOR pathway in lung cancer cells, whereas down-regulation of miR-208a resulted in the opposite effects. In addition, down-regulation of miR-208a increased the percentage of cells undergoing apoptosis and inhibited the G1 phase arrest in NSCLC cells. Moreover, miR-208a from the serum exosome fraction of lung cancer patients could shuttle to A549 cells in a time-dependent manner, which was likely to contribute to the subsequent biological effects.

CONCLUSIONS

The present study provides evidence that miR-208a can affect the proliferation and radiosensitivity of human lung cancer cells by targeting p21 and can be transported by exosomes. Thus, miR-208a may serve as a potential therapeutic target for lung cancer patients.

Apoptosis and antitumor effects induced by the combination of an mTOR inhibitor and an autophagy inhibitor in human osteosarcoma MG63 cells

The inhibition of the mammalian target of rapamycin (mTOR) signaling pathway promotes the initiation of autophagy. Although it remains under debate whether chemotherapy-induced autophagy in tumor cells is a protective response or is invoked to promote cell death, recent studies indicate that autophagy is a self-defense mechanism of cancer cells that are subjected to antitumor agents and that blocking autophagy can trigger apoptosis. The aim of this study was to examine the effects of rapamycin, an mTOR inhibitor, on MG63 osteosarcoma cells. We further examined whether the combination of rapamycin and the small molecule inhibitor of autophagy Spautin-1 (specific and potent autophagy inhibitor-1) enhanced the rapamycin-induced apoptosis in MG63 cells. We examined the effects of rapamycin treatment on cell proliferation, phosphorylation of mTOR pathway components, and autophagy by western blot analysis. Furthermore, we examined the effects of rapamycin with or without Spautin-1 on the induction of apoptosis by western blot analysis and immunohistochemical staining. We found that rapamycin inhibited cell proliferation and decreased the phosphorylation of mTOR pathway components in MG63 cells. Rapamycin induced the apoptosis of MG63 cells, and this apoptosis was enhanced by Spautin-1. It was considered that Spautin-1 suppressed the protective mechanism induced by rapamycin in tumor cells and induced apoptosis. Therefore, the combination of an mTOR inhibitor and an autophagy inhibitor may be effective in the treatment of osteosarcoma because it effectively induces the apoptotic pathway.

Mechanism of Resistance and Novel Targets Mediating Resistance to EGFR and c-Met Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer

Tyrosine kinase inhibitors (TKIs) against EGFR and c-Met are initially effective when administered individually or in combination to non-small cell lung cancer (NSCLC) patients. However, the overall efficacies of TKIs are limited due to the development of drug resistance. Therefore, it is important to elucidate mechanisms of EGFR and c-Met TKI resistance in order to develop more effective therapies. Model NSCLC cell lines H1975 and H2170 were used to study the similarities and differences in mechanisms of EGFR/c-Met TKI resistance. H1975 cells are positive for the T790M EGFR mutation, which confers resistance to current EGFR TKI therapies, while H2170 cells are EGFR wild-type. Previously, H2170 cells were made resistant to the EGFR TKI erlotinib and the c-Met TKI SU11274 by exposure to progressively increasing concentrations of TKIs. In H2170 and H1975 TKI-resistant cells, key Wnt and mTOR proteins were found to be differentially modulated. Wnt signaling transducer, active β-catenin was upregulated in TKI-resistant H2170 cells when compared to parental cells. GATA-6, a transcriptional activator of Wnt, was also found to be upregulated in resistant H2170 cells. In H2170 erlotinib resistant cells, upregulation of inactive GSK3β (p-GSK3β) was observed, indicating activation of Wnt and mTOR pathways which are otherwise inhibited by its active form. However, in H1975 cells, Wnt modulators such as active β-catenin, GATA-6 and p-GSK3β were downregulated. Additional results from MTT cell viability assays demonstrated that H1975 cell proliferation was not significantly decreased after Wnt inhibition by XAV939, but combination treatment with everolimus (mTOR inhibitor) and erlotinib resulted in synergistic cell growth inhibition. Thus, in H2170 cells and H1975 cells, simultaneous inhibition of key Wnt or mTOR pathway proteins in addition to EGFR and c-Met may be a promising strategy for overcoming EGFR and c-Met TKI resistance in NSCLC patients.

Synergistic Effects between mTOR Complex 1/2 and Glycolysis Inhibitors in Non-Small-Cell Lung Carcinoma Cells

Cancer metabolism has greatly interested researchers. Mammalian target of rapamycin (mTOR) is dysregulated in a variety of cancers and considered to be an appealing therapeutic target. It has been proven that growth factor signal, mediated by mTOR complex 1 (mTORC1), drives cancer metabolism by regulating key enzymes in metabolic pathways. However, the role of mTORC2 in cancer metabolism has not been thoroughly investigated. In this study, by employing automated spectrophotometry, we found the level of glucose uptake was decreased in non-small-cell lung carcinoma (NSCLC) A549, PC-9 and SK-MES-1 cells treated with rapamycin or siRNA against Raptor, indicating that the inhibition of mTORC1 attenuated glycolytic metabolism in NSCLC cells. Moreover, the inhibition of AKT reduced glucose uptake in the cells as well, suggesting the involvement of AKT pathway in mTORC1 mediated glycolytic metabolism. Furthermore, our results showed a significant decrease in glucose uptake in rictor down-regulated NSCLC cells, implying a critical role of mTORC2 in NSCLC cell glycolysis. In addition, the experiments for MTT, ATP, and clonogenic assays demonstrated a reduction in cell proliferation, cell viability, and colony forming ability in mTOR inhibiting NSCLC cells. Interestingly, the combined application of mTORC1/2 inhibitors and glycolysis inhibitor not only suppressed the cell proliferation and colony formation, but also induced cell apoptosis, and such an effect of the combined application was stronger than that caused by mTORC1/2 inhibitors alone. In conclusion, this study reports a novel effect of mTORC2 on NSCLC cell metabolism, and reveals the synergistic effects between mTOR complex 1/2 and glycolysis inhibitors, suggesting that the combined application of mTORC1/2 and glycolysis inhibitors may be a new promising approach to treat NSCLC.

Rapamycin Enhances the Anti-Cancer Effect of Dasatinib by Suppressing Src/PI3K/mTOR Pathway in NSCLC Cells

Src and the mammalian target of rapamycin (mTOR) signaling are commonly activated in non-small cell lung cancer (NSCLC) and hence potential targets for chemotherapy. Although the combined use of Src inhibitor Dasatinib with other chemotherapeutic agents has shown superior efficacy for cancer treatment, the mechanisms that lead to enhanced sensitivity of Dasatinib are not completely understood. In this study, we found that Rapamycin dramatically enhanced Dasatinib-induced cell growth inhibition and cell cycle G1 arrest in human lung adenocarcinoma A549 cells without affecting apoptosis. The synergistic effects were consistently correlated with the up-regulation of cyclin-dependent kinases inhibitor proteins, including p16, p19, p21, and p27, as well as the repression of Cdk4 expression and nuclear translocation. Mechanistic investigations demonstrated that FoxO1/FoxO3a and p70S6K/4E-BP1, the molecules at downstream of Src-PI3K-Akt and mTOR signaling, were significantly suppressed by the combined use of Dasatinib and Rapamycin. Restraining Src and mTOR with small interfering RNA in A549 cells further confirmed that the Src/PI3K/mTOR Pathway played a crucial role in enhancing the anticancer effect of Dasatinib. In addition, this finding was also validated by a series of assays using another two NSCLC cell lines, NCI-H1706 and NCI-H460. Conclusively, our results suggested that the combinatory application of Src and mTOR inhibitors might be a promising therapeutic strategy for NSCLC treatment.

In vitro study on blocking mTOR signaling pathway in EGFR-TKI resistance NSCLC

OBJECTIVE

To investigate the effect and mechanism of inhibitor everolimus on EGFR-TKI resistance NSCLC.

METHODS

MTT assay was used to detect proliferation of human non-small cell lung cancer cell line A549. Flow cytometry was used to detect the changes of apoptosis and cycle distribution in each group after 24 h and 48 h. RT-PCR was used to detect the changes of PTEN and 4EBP1 expression levels after 48 h of monotherapy and combination therapy.

RESULTS

MTT assay showed that everolimus had dose-dependent inhibition against growth of A549 cells. Flow cytometry showed when everolimus could induce apoptosis and induce G0/G1 phase cell cycle arrest, which was time-dependent (P<0.05). RT-PCR showed everolimus could increase PTEN and 4EBP1 expression.

CONCLUSIONS

mTOR inhibitor everolimus has an inhibitory effect on EGFR-TKI resistant NSCLC, which cannot reverse the resistance effect of EGFR-TKI resistant cell line A549. The relationship between EGFR/AKT signaling pathway and the mTOR signaling pathway and the mechanism in non-small cell lung cancer need further study.

Enhanced antitumor activity of 3-bromopyruvate in combination with rapamycin in vivo and in vitro

3-Bromopyruvate (3-BrPA) is an alkylating agent and a well-known inhibitor of energy metabolism. Rapamycin is an inhibitor of the serine/threonine protein kinase mTOR. Both 3-BrPA and rapamycin show chemopreventive efficacy in mouse models of lung cancer. Aerosol delivery of therapeutic drugs for lung cancer has been reported to be an effective route of delivery with little systemic distribution in humans. In this study, 3-BrPA and rapamycin were evaluated in combination for their preventive effects against lung cancer in mice by aerosol treatment, revealing a synergistic ability as measured by tumor multiplicity and tumor load compared treatment with either single-agent alone. No evidence of liver toxicity was detected by monitoring serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes. To understand the mechanism in vitro experiments were performed using human non-small cell lung cancer (NSCLC) cell lines. 3-BrPA and rapamycin also synergistically inhibited cell proliferation. Rapamycin alone blocked the mTOR signaling pathway, whereas 3-BrPA did not potentiate this effect. Given the known role of 3-BrPA as an inhibitor of glycolysis, we investigated mitochondrial bioenergetics changes in vitro in 3-BrPA-treated NSCLC cells. 3-BrPA significantly decreased glycolytic activity, which may be due to adenosine triphosphate (ATP) depletion and decreased expression of GAPDH. Our results demonstrate that rapamycin enhanced the antitumor efficacy of 3-BrPA, and that dual inhibition of mTOR signaling and glycolysis may be an effective therapeutic strategy for lung cancer chemoprevention.

A coding single-nucleotide polymorphism in lysine demethylase KDM4A associates with increased sensitivity to mTOR inhibitors

SNPs occur within chromatin-modulating factors; however, little is known about how these variants within the coding sequence affect cancer progression or treatment. Therefore, there is a need to establish their biochemical and/or molecular contribution, their use in subclassifying patients, and their impact on therapeutic response. In this report, we demonstrate that coding SNP-A482 within the lysine tridemethylase gene KDM4A/JMJD2A has different allelic frequencies across ethnic populations, associates with differential outcome in patients with non-small cell lung cancer (NSCLC), and promotes KDM4A protein turnover. Using an unbiased drug screen against 87 preclinical and clinical compounds, we demonstrate that homozygous SNP-A482 cells have increased mTOR inhibitor sensitivity. mTOR inhibitors significantly reduce SNP-A482 protein levels, which parallels the increased drug sensitivity observed with KDM4A depletion. Our data emphasize the importance of using variant status as candidate biomarkers and highlight the importance of studying SNPs in chromatin modifiers to achieve better targeted therapy.

SIGNIFICANCE

This report documents the first coding SNP within a lysine demethylase that associates with worse outcome in patients with NSCLC. We demonstrate that this coding SNP alters the protein turnover and associates with increased mTOR inhibitor sensitivity, which identifies a candidate biomarker for mTOR inhibitor therapy and a therapeutic target for combination therapy.

mTOR pathway: A current, up-to-date mini-review (Review)

Mammalian target of rapamycin (mTOR) is a protein serine/threonine kinase that was initially identified as the cellular target of rapamycin. This kinase regulates cell growth, proliferation, motility and survival, as well as the gene transcription and protein synthesis that are activated in response to hormones, growth factors and nutrients. Results from preclinical studies have indicated that factors antagonizing the mTOR pathway exert an antitumor effect on lung cancer. Furthermore, primary clinical trials of mTOR inhibitors have demonstrated that the inhibitors may be effective against lung carcinoma. The present study explores the association between mTOR and lung carcinogenesis and describes the clinical trials of mTOR inhibitors.

mTOR inhibitors radiosensitize PTEN-deficient non-small-cell lung cancer cells harboring an EGFR activating mutation by inducing autophagy

Clinical resistance to gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), in patients with lung cancer has been linked to acquisition of the T790M resistance mutation in activated EGFR or amplification of MET. Phosphatase and tensin homolog (PTEN) loss has been recently reported as a gefitinib resistance mechanism in lung cancer. The aim of this study was to evaluate the efficacy of radiotherapy in non-small-cell lung cancer (NSCLC) with acquired gefitinib resistance caused by PTEN deficiency to suggest radiotherapy as an alternative to EGFR TKIs. PTEN deficient-mediated gefitinib resistance was generated in HCC827 cells, an EGFR TKI sensitive NSCLC cell line, by PTEN knockdown with a lentiviral vector expressing short hairpin RNA-targeting PTEN. The impact of PTEN knockdown on sensitivity to radiation in the presence or absence of PTEN downstream signaling inhibitors was investigated. PTEN knockdown conferred acquired resistance not only to gefitinib but also to radiation on HCC827 cells. mTOR inhibitors alone failed to reduce HCC827 cell viability, regardless of PTEN expression, but ameliorated PTEN knockdown-induced radioresistance. PTEN knockdown-mediated radioresistance was accompanied by repression of radiation-induced cytotoxic autophagy, and treatment with mTOR inhibitors released the repression of cytotoxic autophagy to overcome PTEN knockdown-induced radioresistance in HCC827 cells. These results suggest that inhibiting mTOR signaling could be an effective strategy to radiosensitize NSCLC harboring the EGFR activating mutation that acquires resistance to both TKIs and radiotherapy due to PTEN loss or inactivation mutations.

Everolimus and zoledronic acid--a potential synergistic treatment for lung adenocarcinoma bone metastasis

Non-small-cell lung cancer (NSCLC) frequently metastasizes to bone. It is known that zoledronic acid is cytostatic to tumors, and everolimus, the inhibitor for mammalian target of the rapamycin, could inhibit many types of cancer. Herein, we evaluated the effect of zoledronic acid alone and in combination with everolimus on treating lung adenocarcinoma bone metastasis in vitro and in vivo. Mice treated with zoledronic acid in combination with everolimus had more apoptotic lung cancer cells and more cells were arrested in the G1/G0 phase. The phosphorylation of p70S6K was inhibited in the combination treatment group. Lung cancer cell invasion was also significantly inhibited in the group with combination treatment in vitro. Bone nuclear scans revealed more metastatic lesions in controls compared with those in the combination treatment group. Bone scans and radiographic images indicated that combination therapy significantly reduced bone metastasis. The moderate survival rate suggested that the drug combination was synergistic, which can delay NSCLC bone metastasis and prolong survival in vivo.

Ampelopsin suppresses breast carcinogenesis by inhibiting the mTOR signalling pathway

The mammalian target of rapamycin (mTOR), which is a master regulator of cellular catabolism and anabolism, plays an important role in tumourigenesis and progression. In this study, we report the chemopreventive effect of the dietary compound ampelopsin (AMP) on breast carcinogenesis in vivo and in vitro, which acts by inhibiting the mTOR signalling pathway. Our study indicates that AMP treatment effectively suppresses 1-methyl-1-nitrosourea (MNU)-induced breast carcinogenesis in rats and inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P)-induced cellular carcinogenesis. Additionally, AMP inhibits the growth of breast cancer cells in vitro and in vivo. The activity of mTOR kinase was found to be significantly increased in a time-dependent manner during chronic breast carcinogenesis, and this increase can be suppressed by AMP co-treatment. AMP also effectively suppresses mTOR activity in breast cancer MDA-MB-231 cells. We also demonstrated that AMP is an effective mTOR inhibitor that binds to one site on the mTOR target in two ways. Further studies confirmed that AMP inhibits the activation of Akt, suppresses the formation of mTOR complexes (mTORC)1/2 by dissociating regulatory-associated protein of mTOR and rapamycin-insensitive companion of mTOR and, consequently, decreases the activation of the downstream targets of mTOR, including ribosomal p70-S6 kinase, ribosomal protein S6, eukaryotic translation initiation factor 4B and eukaryotic translation initiation factor 4E-binding protein 1. These finding suggest that AMP is a bioactive natural chemopreventive agent against breast carcinogenesis and is an effective mTOR inhibitor that may be developed as a useful chemotherapeutic agent in the treatment of breast cancer.

Everolimus prolonged survival in transgenic mice with EGFR-driven lung tumors

Everolimus is an orally administered mTOR inhibitor. The effect, and mechanism of action, of everolimus on lung cancers with an epidermal growth factor receptor (EGFR) mutation remain unclear. Four gefitinib-sensitive and -resistant cell lines were used in the present work. Growth inhibition was determined using the MTT assay. Transgenic mice carrying the EGFR L858R mutation were treated with everolimus (10 mg/kg/day), or vehicle alone, from 5 to 20 weeks of age, and were then sacrificed. To evaluate the efficacy of everolimus in prolonging survival, everolimus (10 mg/kg/day) or vehicle was administered from 5 weeks of age. The four cell lines were similarly sensitive to everolimus. Expression of phosphorylated (p) mTOR and pS6 were suppressed upon treatment with everolimus in vitro, whereas the pAKT level increased. The numbers of lung tumors with a long axis exceeding 1mm in the everolimus-treated and control groups were 1.9 ± 0.9 and 9.4 ± 3.2 (t-test, p<0.001), respectively. pS6 was suppressed during eve r olimus treatment. Although apoptosis and autophagy were not induced in everolimus-treated EGFR transgenic mice, angiogenesis was suppressed. The median survival time in the everolimus-treated group (58.0 weeks) was significantly longer than that in the control group (31.2 weeks) (logrank test, p<0.001). These findings suggest that everolimus had an indirect effect on tumor formation by inhibiting angiogenesis and might be effective to treat lung tumors induced by an activating EGFR gene mutation.

The combination of rapamycin and MAPK inhibitors enhances the growth inhibitory effect on Nara-H cells

The inhibition of the mammalian target of rapamycin (mTOR) signaling pathway promotes the initiation of autophagy, and the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) is well known to induce autophagy. Autophagy is a self-defense mechanism of cancer cells that are subjected to antitumor agents, and blocking autophagy can trigger apoptosis. In the present study, we demonstrate that an mTOR inhibitor, rapamycin, induces autophagy in the Nara-H malignant fibrous histiocytoma (MFH) cell line through the activation of ERK1/2. Rapamycin-induced apoptosis was enhanced following the inhibition of the MEK/ERK pathway. In the Nara-H cells, we examined the effects of rapamycin treatment on cell proliferation and on the phosphorylation of the mTOR pathway components and autophagy by western blot analysis. Furthermore, we examined the effects of rapamycin with or without the MEK inhibitor, U0126, on the induction of apoptosis by using fluorescence microscopy. Rapamycin inhibited Nara-H cell proliferation and decreased the phosphorylation of the mTOR pathway in the Nara-H cells. Rapamycin induced the apoptosis of Nara-H cells, and this apoptosis was enhanced by U0126. Simultaneously, phospho-ERK1/2 was activated by rapamycin. The present study demonstrates that rapamycin induces autophagy in Nara-H cells by activating the MEK/ERK signaling pathway, and the rapamycin-induced apoptosis can be enhanced by the MEK inhibitor, U0126. These results suggest that self-protective mechanisms involving mTOR inhibitors in Nara-H cells are prevented by the inhibition of the MEK/ERK pathway. The combination of an mTOR inhibitor (e.g., rapamycin) and an MEK inhibitor (e.g., U0126) may offer effective treatment for MFH, as this combination effectively activates apoptotic pathways.

Temsirolimus and pegylated liposomal doxorubicin (PLD) combination therapy in breast, endometrial, and ovarian cancer: phase Ib results and prediction of clinical outcome with FDG-PET/CT

Pegylated liposomal doxorubicin (PLD) is active in breast, endometrial, and ovarian cancer. Preclinical data suggest that the combination of PLD with a mammalian target of rapamycin (mTOR) inhibitor has an additive effect. The safety and recommended phase two dose (RPTD) of temsirolimus in combination with PLD were assessed. (18) F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed for early response monitoring. Nineteen patients with advanced breast, endometrial, and ovarian cancer were treated with increasing doses of temsirolimus (10, 15, or 20 mg once weekly) and PLD (30 or 40 mg/m(2) once every 4 weeks). PLD was initiated 2 weeks after start of temsirolimus. FDG-PET/CT was performed at baseline, after 2 and 6 weeks. Standardized uptake values (SUV), metabolic volume, and total lesion glycolysis (TLG, SUV × metabolic volume) were calculated. The RPTD was 15 mg temsirolimus and 40 mg/m(2) PLD. Dose-limiting toxicities (DLT) were thrombocytopenia grade 3 with nose bleeding and skin toxicity grade 3. Most frequent treatment-related toxicities were nausea, fatigue, mucositis, and skin toxicity. Changes in TLG after 2 weeks predicted partial response (PR) after 10 weeks (p = 0.037). A rise in SUV between the second and sixth week predicted progression (PD) (p = 0.034) and was associated with worse progression free survival (PFS) (HR 1.068; p = 0.013). The RPTD was established at 15 mg temsirolimus weekly and PLD 40 mg/m(2) once every 4 weeks and the combination was safe. Early response evaluation with FDG-PET/CT may predict subsequent radiological PR and PD. This trial is registered under number NCT0098263.

KRAS mutations as prognostic and predictive markers in non-small cell lung cancer

A greater understanding of non-small-cell lung cancer at a molecular level has led to the identification of an increasing number of driver mutations. Extensive research of the KRAS gene as well as specific mutations has established its role in tumorigenesis. Nevertheless, the role of KRAS oncogene in non-small-cell lung cancer remains unclear. Recent studies indicated that mutant KRAS could be predictive of lack of response to chemotherapy, but large pooled analysis failed to confirm this result. The predictive value of KRAS mutation and EGFR-TKI treatment is more ambiguous with some recent evidence suggesting that it may be a negative predictive biomarker. This review provides an overview of RAS biology, assesses the utility of KRAS as a prognostic marker, and evaluates its role as a predictive marker for response to chemotherapy and EGFR-TKIs. In addition, we review some current studies that are targeting the KRAS pathway.

New treatment options for lung adenocarcinoma--in view of molecular background

Lung cancer is the leading cause of cancer related mortality all over the world, and a number of developments have indicated future clinical benefit recently. The development of molecular pathology methods has become increasingly important in the prediction of chemotherapy sensitivity and mutation analysis to identify driver mutations as important targets of new therapeutic agents. The most significant changes in the treatment of NSCLC revealed in new pathologic classification and in the introduction of molecularly targeted therapies, which include monoclonal antibodies and small molecule tyrosine kinase inhibitors. The side effects of these agents are generally better tolerated than those of conventional chemotherapy and show higher efficacy. The most important factor follows: histology subtypes, gene mutation status, patients' selection, drug toxicities and occurence of drug resistance. In the advanced disease, the hope of cure is less than 3%, but improvements in survival have been clearly achieved. Some years ago the median lung cancer survival rate was 10-12 months, now in case of available specific molecular targets, a significant increase in median survival rates to 24-36 months has been achieved. These agents give an opportunity to provide a new standard of care. Therefore testing EGFR mutations and ALK rearrangements in patients with advanced lung adenocarcinoma should be incorporated into routine clinical practice. This review focuses on the rationale for targeted agents and new treatment possibilities in case of advanced lung adenocarcinoma.

Molecular Targeted Drugs and Biomarkers in NSCLC, the Evolving Role of Individualized Therapy

Lung cancer first line treatment has been directed from the non-specific cytotoxic doublet chemotherapy to the molecular targeted. The major limitation of the targeted therapies still remains the small number of patients positive to gene mutations. Furthermore, the differentiation between second line and maintenance therapy has not been fully clarified and differs in the clinical practice between cancer centers. The authors present a segregation between maintenance treatment and second line and present a possible definition for the term “maintenance” treatment. In addition, cancer cell evolution induces mutations and therefore either targeted therapies or non-specific chemotherapy drugs in many patients become ineffective. In the present work pathways such as epidermal growth factor, anaplastic lymphoma kinase, met proto-oncogene and PI3K are extensively presented and correlated with current chemotherapy treatment. Future, perspectives for targeted treatment are presented based on the current publications and ongoing clinical trials.

Mechanistic target of rapamycin small interfering RNA and rapamycin synergistically inhibit tumour growth in a mouse xenograft model of human oesophageal carcinoma

OBJECTIVES

To investigate the effect of mechanistic target of rapamycin (mTOR)-specific small interfering RNA (siRNA) and rapamycin on tumour size and levels of hypoxia inducible factor 1α(HIF-1α), vascular endothelial growth factor (VEGF) and mTOR proteins, and mTOR mRNA, in a mouse xenograft model of human oesophageal carcinoma.

METHODS

Tumours were induced in BALB/c nude mice using the human oesophageal squamous cell carcinoma cell line, EC1, injected subcutaneously. Animals were divided into four treatment groups (n = 5 per group) after 7 days: control (phosphate buffered saline, daily intraperitoneal [i.p.] injection); 50 μg/kg rapamycin, daily i.p. injection; 3 μg/kg mTOR siRNA, daily i.p. injection; combined mTOR siRNA and rapamycin, daily i.p. injections. Tumour volume was measured 21 days after xenograft. Levels of mTOR, VEGF and HIF-1α were assessed via immunohistochemistry and in situ hybridization.

RESULTS

mTOR siRNA and/or rapamycin significantly decreased tumour volume and levels of HIF-1α, VEGF and mTOR protein, and mTOR mRNA. Combination treatment was significantly more effective than either treatment alone.

CONCLUSIONS

mTOR siRNA and/or rapamycin inhibited the growth of oesophageal carcinoma in vivo. This may represent a novel and effective treatment strategy for oesophageal carcinoma.

miR-205 targets PTEN and PHLPP2 to augment AKT signaling and drive malignant phenotypes in non-small cell lung cancer

AKT signaling is constitutively activated in various cancers, due in large part to loss-of-function in the PTEN and PHLPP phosphatases that act as tumor suppressor genes. However, AKT signaling is activated widely in non-small cell lung cancers (NSCLC) where genetic alterations in PTEN or PHLPP genes are rare, suggesting an undefined mechanism(s) for their suppression. In this study, we report upregulation of the oncomir microRNA (miR)-205 in multiple subtypes of NSCLC, which directly represses PTEN and PHLPP2 expression and activates both the AKT/FOXO3a and AKT/mTOR signaling pathways. miR-205 overexpression in NSCLC cells accelerated tumor cell proliferation and promoted blood vessel formation in vitro and in vivo. Conversely, RNA interference-mediated silencing of endogenous miR-205 abrogated these effects. The malignant properties induced by miR-205 in NSCLC cells were reversed by AKT inhibitors, FOXO3a overexpression, rapamycin treatment, or restoring PHLPP2 or PTEN expression. Mechanistic investigations revealed that miR-205 overexpression was a result of NF-κB-mediated transactivation of the miR-205 gene. Taken together, our results define a major epigenetic mechanism for suppression of PTEN and PHLPP2 in NSCLC, identifying a pivotal role for miR-205 in development and progression of this widespread disease.

A phase I trial of sunitinib and rapamycin in patients with advanced non-small cell lung cancer

BACKGROUND

Sunitinib is an oral multitargeted tyrosine kinase inhibitor, with single-agent activity in non-small cell lung cancer (NSCLC). Resistance to tyrosine kinase inhibitor therapy is mediated by the mammalian target of rapamycin (mTOR) pathway, and may be reversed by using mTOR inhibitors.

METHODS

We performed a phase I study evaluating the combination of sunitinib and rapamycin in patients with advanced NSCLC.

RESULTS

Nineteen patients were enrolled in the study. The dose-limiting toxicities included infection, pneumonia, diarrhea/dehydration and treatment delay due to thrombocytopenia in 1 patient each. Sunitinib 25 mg orally daily and rapamycin 2 mg orally daily with 4 weeks on and 2 weeks off therapy were determined to be the maximum tolerated dose. No objective responses were noted, and 6 patients had stable disease as a best response.

CONCLUSION

The combination of sunitinib and rapamycin is well-tolerated and warrants further investigation in the phase II setting.

Aerosol delivery of lentivirus-mediated O-glycosylation mutant osteopontin suppresses lung tumorigenesis in K-ras (LA1) mice

BACKGROUND

Osteopontin (OPN) is a secreted glycophosphoprotein that has been implicated in the regulation of cancer development. The function of OPN is primarily regulated through post-translational modification such as glycosylation. As yet, however, the relationship between OPN glycosylation and lung cancer development has not been investigated. In this study, we addressed this issue by studying the effect of a triple mutant (TM) of OPN, which is mutated at three O-glycosylation sites, on lung cancer development in K-ras (LA1) mice, a murine model for human non-small cell lung cancer.

METHODS

Aerosolized lentivirus-based OPN TM was delivered into the lungs of K-ras (LA1) mice using a nose-only-inhalation chamber 3 times/wk for 4 wks. Subsequently, the effects of repeated delivery of OPN TM on lung tumorigenesis and its concomitant OPN-mediated signaling pathways were investigated.

RESULTS

Aerosol-delivered OPN TM inhibited lung tumorigenesis. In addition, the OPN-mediated Akt signaling pathway was inhibited. OPN TM also decreased NF-κB activity and the phosphorylation of 4E-BP1, while facilitating apoptosis in the lungs of K-ras (LA1) mice.

CONCLUSIONS

Our results show that aerosol delivery of OPN TM successfully suppresses lung cancer development in the K-ras (LA1) mouse model and, therefore, warrant its further investigation as a possible therapeutic strategy for non-small cell lung cancer.