Preclinical rationale for PI3K/Akt/mTOR pathway inhibitors as therapy for epidermal growth factor receptor inhibitor-resistant non-small-cell lung cancer

Unraveling the chemotherapeutic potential of taxifolin ruthenium-p-cymene complex in breast carcinoma: Insights into AhR signaling pathway in vitro and in vivo

BACKGROUND

Mammary carcinoma is the most frequently diagnosed form of carcinoma in women worldwide. The organometallic compounds showed a prospective anticancer activity. This research explored the anticancer efficacy of taxifolin ruthenium-p-cymene counter to breast cancer.

METHODS

The anticancer efficacy of the novel organometallic compound was investigated via various in vitro and in vivo techniques using breast cancer cell lines and breast cancer model of rat.

RESULTS

Target proteins were identified via pharmacophore analysis, which revealed a high binding affinity towards AhR, EGFR, and β-catenin. The compound induced apoptotic events and prevented cancer cell colony formation. Furthermore, decreased expression of AhR, EGFR, and N-cadherin inhibited cancer cell growth, migration, and proliferation. The compound provoked the cell cycle arrest at sub G0/G1 phase, S phase and G2/M phase and inaugurated the caspase-3 dependent apoptotic events. The in-vivo experimentation displayed the fruitful restoration of breast tissue since the complex treatment in DMBA persuaded breast carcinoma in rat. Moreover, the upstream of p53 and caspase-3 expression along with substantially downstream of vimentin, β-catenin, m-TOR and Akt expression.

CONCLUSIONS

In conclusion, the compound repressed the cancerous cellular viability, migration, and EMT via modulating the AhR/EGFR/ PI3K transduction pathway and the expression of EMT biomarkers such as N-cadherin, E-cadherin, thus eventually revoked the EMT facilitated metastasis of malignant cells.

Design, synthesis and bioevaluation of dual EGFR-PI3Kα inhibitors for potential treatment of NSCLC

Aberrant activation or mutation of the EGFR-PI3K-Akt-mTOR signaling pathway has been implicated in a wide range of human cancers, especially non-small-cell lung cancer (NSCLC). Thus, dual inhibition of EGFR and PI3K has been investigated as a promising strategy to address acquired drug resistance resulting from the use of tyrosine kinase inhibitors. A series of dual EGFR/PI3Kα inhibitors was synthesized using pharmacophore hybridization of the third-generation EGFR inhibitor olmutinib and the PI3Kα selective inhibitor TAK-117. The optimal compound 30k showed potent kinase inhibitory activities with IC50 values of 3.6 and 30.0 nM against EGFRL858R/T790M and PI3Kα, respectively. Compound 30k exhibited a significant antiproliferative effect in NCI-H1975 cells with a higher selectivity profile than olmutinib. The potential antitumor mechanism, molecular binding modes, and in vitro metabolic stability of compound 30k were also clarified.

PABPC1 silencing inhibits pancreatic cancer cell proliferation and EMT, and induces apoptosis via PI3K/AKT pathway

Pancreatic cancer is difficult to manage owing to the challenges involved in its treatment and nursing. This study aimed to clarify the roles and mechanisms of action of Poly (A)-binding protein cytoplasmic 1 (PABPC1) on pancreatic cancer. The expression of PABPC1 in pancreatic cancer tissues and cell lines was detected using RT-qPCR and western blotting. The effects of PABPC1 on proliferation, apoptosis, epithelial-mesenchymal transition (EMT), and the PI3K/AKT signaling pathway in pancreatic cancer cells were further investigated using MTT assays, flow cytometry, and western blotting. The expression of PABPC1 was significantly upregulated in pancreatic cancer tissues and cells, whereas PABPC1 downregulation inhibited pancreatic cancer cell proliferation, induced apoptosis, decreased the expression of EMT-associated proteins, and exerted a regulatory effect by inhibiting the PI3K/AKT signaling pathway. In addition, the findings indicated that PABPC1 over-expression significantly promoted pancreatic cancer cell proliferation, inhibited apoptosis, decreased the expression of E-cadherin, enhanced N-cadherin expression, and activating the PI3K/AKT signaling pathway. PABPC1 silencing significantly inhibited proliferation and EMT and induced apoptosis in pancreatic cancer cells. These findings provide novel insights into the role of PABPC1 in the development of pancreatic cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00626-1.

Successful treatment of severe lung cancer caused by third-generation EGFR-TKI resistance due to EGFR genotype conversion with afatinib plus anlotinib

Third-generation EGFR-TKIs can be used to treat advanced non-small cell lung cancer patients with T790M resistance mutation induced by first- or second-generation EGFR-TKIs. However, it will also result in drug resistance, and the resistance mechanisms of third-generation EGFR-TKIs are complex. Here we reported a patient diagnosed with advanced lung adenocarcinoma and EGFR positive in September 2016. Following first-line targeted therapy with gefitinib, genetic testing showed EGFR T790M positive, which resulted in a change to osimertinib targeted therapy. In May 2021, troponin and creatinine levels were elevated, and the tumor hyperprogressed to severe lung cancer. Repeated genetic testing revealed that EGFR genotype converted to a non-classical mutation and EGFR T790M turned negative, which caused third-generation EGFR-TKI resistance. As a result, afatinib combined with anlotinib was selected to stabilize the patient's condition. We were inspired by the case that it reflects the significance and necessity of exploring the resistance mechanism and dynamically detecting genetic status throughout the course of treatment, which may help realize individualized precision therapy, and maximize the potential of patient.

Everolimus in combination with vandetanib in children, adolescents, and young adults: a phase I study

BACKGROUND

Combined use of inhibitors of mammalian target of rapamycin (mTOR) and vascular endothelial growth factor (VEGF-2) receptors is a potential strategy to overcome resistance to either class of drugs when used alone.

PATIENTS AND METHODS

We designed a phase 1 trial to test the drug combination of a multikinase VEGF receptor 2 inhibitor, vandetanib, and an mTOR inhibitor, everolimus, in a pediatric and young adult patient cohort with advanced cancers. Exceptional responders were probed for tumor mutational profile to explore possible molecular mechanisms of response.

RESULTS

Among 21 enrolled patients, clinical benefit was observed in 38% (one patient with partial response and eight patients with stable disease) with a median progression-free survival of 3.3 months. The most common treatment-related adverse event was rash (n = 13). Other treatment-related toxicities included diarrhea, fatigue, hypertension, QT prolongation, hypertriglyceridemia/hypercholesterolemia, transaminitis, thrombocytopenia, and weight loss. None of the patients experienced dose-limiting toxicities. Three exceptional responders were analyzed and were found to harbor genetic alterations including kinase insert domain receptor (KDR) Q472H mutation, EWSR1-CREB3L1, CDKN2A/B loss, and ASPL/ASPSCR1-TFE3 fusion.

CONCLUSIONS

The combination of vandetanib and everolimus showed early activity and tolerable toxicity profile in pediatric patients with advanced cancers.

A Functional Genomics Review of Non-Small-Cell Lung Cancer in Never Smokers

There is currently a dearth of information regarding lung cancer in never smokers (LCINS). Additionally, there is a difference in somatic mutations, tumour mutational burden, and chromosomal aberrations between smokers and never smokers (NS), insinuating a different disease entity in LCINS. A better understanding of actionable driver alterations prevalent in LCINS and the genomic landscape will contribute to identifying new molecular targets of relevance for NS that will drastically improve outcomes. Differences in treatment outcomes between NS and smokers, as well as sexes, with NSCLC suggest unique tumour characteristics. Epidermal growth factor receptor (EGFR) tyrosine kinase mutations and echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) gene rearrangements are more common in NS and have been associated with chemotherapy resistance. Moreover, NS are less likely to benefit from immune mediators including PD-L1. Unravelling the genomic and epigenomic underpinnings of LCINS will aid in the development of not only novel targeted therapies but also more refined approaches. This review encompasses driver genes and pathways involved in the pathogenesis of LCINS and a deeper exploration of the genomic landscape and tumour microenvironment. We highlight the dire need to define the genetic and environmental aspects entailing the development of lung cancer in NS.

Identification of the structural features of quinazoline derivatives as EGFR inhibitors using 3D-QSAR modeling, molecular docking, molecular dynamics simulations and free energy calculations

Epidermal growth factor receptor (EGFR) is a promising target for the treatment of different types of malignant tumors. Therefore, a combined molecular modeling study was performed on a series of quinazoline derivatives as EGFR inhibitors. The optimum ligand-based CoMFA and CoMSIA models showed reliable and satisfactory predictability (with R²_cv=0.681, R²_ncv=0.844, R²_pred=0.8702 and R²_cv=0.643, R²_ncv=0.874, R²_pred=0.6423). The derived contour maps provide structural features to improve inhibitory activity. Furthermore, the contour maps, molecular docking, and molecular dynamics (MD) simulations have good consistency, illustrating that the derived models are reliable. In addition, MD simulations and binding free energy calculations were also carried out to understand the conformational fluctuations at the binding pocket of the receptor. The results indicate that hydrogen bond, hydrophobic and electrostatic interactions play significant roles on activity and selectivity. Furthermore, amino acids Val31, Lys50, Thr95, Leu149 and Asp160 are considered as essential residues to participate in the ligand-receptor interactions. Overall, this work would offer reliable theoretical basis for future structural modification, design and synthesis of novel EGFR inhibitors with good potency.Communicated by Ramaswamy H. Sarma.

Neoadjuvant afatinib with paclitaxel for triple-negative breast cancer and the molecular characteristics in responders and non-responders

BACKGROUND

The prognosis of triple-negative breast cancer (TNBC) is worse and a major proportion of TNBC expresses epidermal growth factor receptor (EGFR). Afatinib can inhibit EGFR signal pathway; however, its treatment effect for TNBC is unknown. Thus, we aimed to assess the efficacy and biomarkers of afatinib in combination with paclitaxel in a neoadjuvant setting.

METHODS

Patients with stage II to III TNBC were enrolled. They received 40 mg of afatinib daily for 14 days, followed by daily afatinib and weekly paclitaxel (80 mg/m²) every 21 days for four to six cycles. To explore the mechanisms of responsiveness and non-responsiveness, 409 cancer-associated genes were sequenced.

RESULTS

Twenty-one patients were enrolled and one patient achieved a complete clinical response; however, a 2 mm residual tumor was noted in the surgical specimen. Overall, 33.0% patients were responders. Fifteen patients received molecular testing. No activated mutation of EGFR or Her2 were found. Activated PI3K or JAK2 pathway were trended to associate with non-responder (p = 0.057). Mutation of homologous recombination (HR) genes were correlated with non-responsiveness (p = 0.005). Seven patients did not have altered PI3K, JAK2 or HR pathway; six (85.7%) of them were responder. Patients with the amplified DAXX gene was associated with a favorable trend of response (p = 0.109).

CONCLUSIONS

Adding afatinib to neoadjuvant paclitaxel generated a modest effect in TNBC. Exploratory molecular analysis suggested that activated PI3K, JAK2 pathways and mutation of HR genes were associated with therapeutic non-responsiveness, and amplification of DAXX genes was associated with responsiveness to afatinib in combination with paclitaxel.

Systematic Analysis of Stress Granule Regulators-Associated Molecular Subtypes Predicts Drug Response, Immune Response, and Prognosis in Non-Small Cell Lung Cancer

Lung cancer has the world’s second highest cancer incidence and second highest cancer-related mortality rate. However, the mechanism underlying non-small cell lung cancer (NSCLC) remained to be unclear. Overall, this study for the first time revealed Stress Granule Regulators were mutated and dysregulated in NSCLC samples by analyzing TCGA database. Moreover, three subtypes of NSCLC were identified based on the expression levels of Stress Granule Regulators. Patients in cluster 2 showed a higher survival rate than those in clusters 1 and 3. Bioinformatics analysis indicated the cell cycle, mTOR signaling pathway, EGFR signaling, PI3K/Akt signaling and DNA damage repair signaling were significantly related to molecular subtypes. Moreover, we performed a prediction analysis of the response to the inhibitors against the aforementioned signaling. Our results showed patients in C2 NSCLC had the highest sensitivity to MK.2206 (AKT.inhibitor) and Rapamycin (mTOR inhibitor). Patients in C3 NSCLC had the highest sensitivity for Temsirolimus (PI3K/mTOR signaling), BIBW2992 (EGFR signaling), Erlotinib (EGFR signaling), PD.0332991 (CDK4/6 inhibitor), CGP.60474 (CDK inhibitor), and Gefitinib (EGFR signaling). Moreover, our results showed patients in C1 NSCLC had the highest sensitivity to AKT.inhibitor, AZD6482 (PI3K inhibitor). To evaluate the response to immune therapy of different subtypes, we analyzed the tumor immune inflation, immune regulators expression, and TIDE score in different SG related subtypes. These results showed that C2 and C3 may be more sensitive to immune therapy. To better predict the prognosis of NSCLC, we analyzed the correlation between stress granule regulator expression and overall survival time in NSCLC and constructed a Stress Granule Score including EIF2S1, CTSG, EIF4G1, IGF2BP1, PABPC1 to predict the prognosis of NSCLC. Overall, this study for the first time uncovers the effect of stress particles on drug response, immune response, and prognosis, laying a new theoretical foundation for the NSCLC prognosis and treatment.

FGFC1 Selectively Inhibits Erlotinib-Resistant Non-Small Cell Lung Cancer via Elevation of ROS Mediated by the EGFR/PI3K/Akt/mTOR Pathway

Non-small cell lung cancer (NSCLC) is one of the most common malignancies in the world. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been used as a first-line treatment for patients harboring with EGFR mutations in advanced NSCLC. Nevertheless, the drug resistance after continuous and long-term chemotherapies considerably limits its clinical efficacy. Therefore, it is of great importance to develop new chemotherapeutic agents and treatment strategies to conquer the drug resistance. FGFC1 (Fungi fibrinolytic compound 1), a type of bisindole alkaloid from a metabolite of the rare marine fungi Starchbotrys longispora. FG216, has exhibited excellent fibrinolytic and anti-inflammatory activity. However, the potent efficacy of FGFC1 in human cancer therapy requires further study. Herein, we demonstrated that FGFC1 selectively suppressed the growth of NSCLC cells with EGFR mutation. Mechanistically, FGFC1 treatment significantly induced the apoptosis of erlotinib-resistant NSCLC cells H1975 in a dose-dependent manner, which was proved to be mediated by mitochondrial dysfunction and elevated accumulation of intracellular reactive oxygen species (ROS). Scavenging ROS not only alleviated FGFC1-induced apoptosis but also relieved the decrease of phospho-Akt. We further confirmed that FGFC1 significantly decreased the phosphorylation of protein EGFR, phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR) in H1975 cells. Notably, PI3K inhibitor (LY294002) could promote the accumulation of ROS and the expression levels of apoptosis-related proteins induced by FGFC1. Molecular dynamics simulations indicated that FGFC1 can inhibit EGFR and its downstream PI3K/Akt/mTOR pathway through directly binding to EGFR, which displayed a much higher binding affinity to EGFRT790M/L858R than EGFRWT. Additionally, FGFC1 treatment also inhibited the migration and invasion of H1975 cells. Finally, FGFC1 effectively inhibited tumor growth in the nude mice xenograft model of NSCLC. Taken together, our results indicate that FGFC1 may be a potential candidate for erlotinib-resistant NSCLC therapy.

Signaling Pathway Inhibitors, miRNA, and Nanocarrier-Based Pharmacotherapeutics for the Treatment of Lung Cancer: A Review

Lung cancer is one of the most commonly diagnosed cancers and is responsible for a large number of deaths worldwide. The pathogenic mechanism of lung cancer is complex and multifactorial in origin. Thus, various signaling pathways as targets for therapy are being examined, and many new drugs are in the pipeline. However, both conventional and target-based drugs have been reported to present significant adverse effects, and both types of drugs can affect the clinical outcome in addition to patient quality of life. Recently, miRNA has been identified as a promising target for lung cancer treatment. Therefore, miRNA mimics, oncomiRs, or miRNA suppressors have been developed and studied for possible anticancer effects. However, these miRNAs also suffer from the limitations of low stability, biodegradation, thermal instability, and other issues. Thus, nanocarrier-based drug delivery for the chemotherapeutic drug delivery in addition to miRNA-based systems have been developed so that existing limitations can be resolved, and enhanced therapeutic outcomes can be achieved. Thus, this review discusses lung cancer's molecular mechanism, currently approved drugs, and their adverse effects. We also discuss miRNA biosynthesis and pathogenetic role, highlight pre-clinical and clinical evidence for use of miRNA in cancer therapy, and discussed limitations of this therapy. Furthermore, nanocarrier-based drug delivery systems to deliver chemotherapeutic drugs and miRNAs are described in detail. In brief, the present review describes the mechanism and up-to-date possible therapeutic approaches for lung cancer treatment and emphasizes future prospects to bring these novel approaches from bench to bedside.

Highlights on selected growth factors and their receptors as promising anticancer drug targets

Growth factor receptors (GFRs) and receptor tyrosine kinases (RTK) are groups of proteins mediating a plethora of physiological processes, including cell growth, proliferation, survival, differentiation and migration. Under certain circumstances, expression of GFRs and subsequently their downstream kinase signaling are deregulated by genetic, epigenetic, and somatic changes leading to uncontrolled cell division in many human diseases, most notably cancer. Cancer cells rely on growth factors to sustain the increasing need to cell division and metabolic reprogramming through cancer-associated activating mutations of their receptors (i.e., GFRs). In this review, we highlight the recent advances of selected GFRs and their ligands (growth factors) in cancer with emphasis on structural and functional differences. We also interrogate how overexpression and/or hyperactivation of GFRs contribute to cancer initiation, development, progression, and resistance to conventional chemo- and radiotherapies. Novel approaches are being developed as anticancer agents to target growth factor receptors and their signaling pathways in different cancers. Here, we illustrate how the current knowledge of GFRs biology, and their ligands lead to development of targeted therapies to inhibit and/or block the activity of growth factors, GFRs and downstream kinases to treat diseases such as cancer.

RNF8-mediated regulation of Akt promotes lung cancer cell survival and resistance to DNA damage

Despite the tremendous success of targeted and conventional therapies for lung cancer, therapeutic resistance is a common and major clinical challenge. RNF8 is a ubiquitin E3 ligase that plays essential roles in the DNA damage response; however, its role in the pathogenesis of lung cancer is unclear. Here, we report that RNF8 is overexpressed in lung cancer and positively correlates with the expression of p-Akt and poor survival of patients with non-small-cell lung cancer. In addition, we identify RNF8 as the E3 ligase for regulating the activation of Akt by K63-linked ubiquitination under physiological and genotoxic conditions, which leads to lung cancer cell proliferation and resistance to chemotherapy. Together, our study suggests that RNF8 could be a very promising target in precision medicine for lung cancer.

Computational Analysis of Drug Resistance Network in Lung Adenocarcinoma

BACKGROUND

Lung cancer is a significant health problem and accounts for one-third of the deaths worldwide. A great majority of these deaths are caused by non-small cell lung cancer (NSCLC). Chemotherapy is the leading treatment method for NSCLC, but resistance to chemotherapeutics is an important limiting factor that reduces the treatment success of patients with NSCLC.

OBJECTIVE

In this study, the relationship between differentially expressed genes affecting the survival of the patients, according to the bioinformatics analyses, and the mechanism of drug resistance is investigated for non-small cell lung adenocarcinoma patients.

METHODS

Five hundred thirteen patient samples were compared with fifty-nine control samples. The employed dataset was downloaded from The Cancer Genome Atlas (TCGA) database. The information on how the drug activity altered against the expressional diversification of the genes was extracted from the NCI-60 database. Four hundred thirty-three drugs with known mechanism of action (MoA) were analyzed. Diversifications of the activity of these drugs related to genes were considered based on nine lung cancer cell lines virtually. The analyses were performed using R programming language, GDCRNATools, rcellminer, and Cytoscape.

RESULTS

This work analyzed the common signaling pathways and expressional alterations of the proteins in these pathways associated with survival and drug resistance in lung adenocarcinoma. Deduced computational data demonstrated that proteins of EGFR, JNK/MAPK, NF-κB, PI3K /AKT/mTOR, JAK/STAT, and Wnt signaling pathways were associated with molecular mechanism of resistance to anticancer drugs in NSCLC cells.

CONCLUSION

To understand the relationships between resistance to anticancer drugs and EGFR, JNK/MAPK, NF-κB, PI3K /AKT/mTOR, JAK/STAT, and Wnt signaling pathways is an important approach to design effective therapeutics for individuals with NSCLC adenocarcinoma.

Molecular mechanism and pharmacokinetics of flavonoids in the treatment of resistant EGF receptor-mutated non-small-cell lung cancer: A narrative review

Here, we review the molecular mechanism and pharmacokinetics of flavonoids in the treatment of resistant EGF receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC) and particularly the possible mechanism(s) of delicaflavone, a biflavonoid extracted from Selaginella doederleinii Hieron. EGFR TK inhibitors (EGFR-TKI) are ubiquitously used in the treatment of NSCLC bearing EGFR mutations. However, patients treated with EGFR-TKI inevitably and continuously develop resistance. In laboratory studies, flavonoids, as potential adjuvants for cancer chemotherapy, exhibited anti-cancer properties such as inhibition of chemoresistance by interference with ABC transporters-induced drug efflux, curbing of c-MET amplification, or reversal of T790M mutation-mediated resistance. The current review aims at summarizing the association between the anti-cancer potentials of flavonoids and their possible regulatory roles in certain types of mutation that could trigger EGFR-TKI resistance in NSCLC. Potential practical applications of these phytochemicals, as well as the relevant pharmacokinetics, are also discussed.

Type 2 Diabetes, Obesity, and Cancer Share Some Common and Critical Pathways

Diabetes and cancer are among the most frequent and complex diseases. Epidemiological evidence showed that the patients suffering from diabetes are significantly at higher risk for a number of cancer types. There are a number of evidence that support the hypothesis that these diseases are interlinked, and obesity may aggravate the risk(s) of type 2 diabetes and cancer. Multi-level unwanted alterations such as (epi-)genetic alterations, changes at the transcriptional level, and altered signaling pathways (receptor, cytoplasmic, and nuclear level) are the major source which promotes a number of complex diseases and such heterogeneous level of complexities are considered as the major barrier in the development of therapeutic agents. With so many known challenges, it is critical to understand the relationships and the commonly shared causes between type 2 diabetes and cancer, which is difficult to unravel and understand. Furthermore, the real complexity arises from contended corroborations that specific drug(s) (individually or in combination) during the treatment of type 2 diabetes may increase or decrease the cancer risk or affect cancer prognosis. In this review article, we have presented the recent and most updated evidence from the studies where the origin, biological background, the correlation between them have been presented or proved. Furthermore, we have summarized the methodological challenges and tasks that are frequently encountered. We have also outlined the physiological links between type 2 diabetes and cancers. Finally, we have presented and summarized the outline of the hallmarks for both these diseases, diabetes and cancer.

ATG7-dependent and independent autophagy determine the type of treatment in lung cancer

Based on the role of ATG7 in the initiation of autophagy, autophagy can be divided into ATG7-dependent selective autophagy and ATG7-independent alternative autophagy. However, the detailed roles of two different types of autophagy in antitumor therapy have not been fully elucidated so far. Here, we for the first time demonstrated an investigational inducer, w09, could induce both selective autophagy and alternative autophagy in NSCLC, but the phenotypes of these two kinds of autophagy are different：(1) w09-induced selective autophagy mainly promoted cell apoptosis, while w09-triggered alternative autophagy markedly induced autophagic cell death in NSCLC；(2) w09-induced ATG7 dependent autophagy mainly promoted the accumulation of SQSTM1/p62, while w09-triggered ATG7 independent autophagy markedly accelerated the degradation of SQSTM1/p62. These above results were further confirmed by knockout ATG7 gene in A549 cells or restoration of ATG7 function in H1650 cells. Deletion of ATG7 gene markedly attenuated the effect of w09-induced autophagy or apoptosis on A549 cells, while restoration of functional ATG7 markedly enhanced the effect of w09-induced autophagy and apoptosis on H1650 cells. Mechanistically, we further revealed that w09 induced two different types of autophagy through inhibiting PI3K/AKT/mTOR signaling pathway. Notably, compared with A549WT xenograft model, the in vivo antitumor effect of w09 or Taxel on the ATG7-deficient A549 xenograft model was significantly attenuated. Therefore, a special attention must be paid to distinguish which kinds of autophagy have been induced by autophagy inducers with antitumor agents by targeting PI3K/AKT/mTOR signaling pathway.

Effects of hyperinsulinemia on acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitor via the PI3K/AKT pathway in non-small cell lung cancer cells in vitro

Patients with lung cancer harboring activating epidermal growth factor (EGFR) mutations and pre-existing diabetes have been demonstrated to exhibit poor responses to first-line EGFR-tyrosine kinase inhibitor (TKI) therapy. Strategies for the management of acquired resistance to EGFR-TKIs in patients with advanced non-small cell lung cancer (NSCLC) are urgently required. Only a limited number of studies have been published to date on the effects of insulin on EGFR-TKI resistance in NSCLC. Hence, the aim of the present study was to investigate the roles of hyperinsulinemia and hyperglycemia in mediating gefitinib resistance in NSCLC cells with activating EGFR mutations. In the present study, the HCC4006 cell line, which harbors EGFR mutations, was co-treated with gefitinib and long-acting insulin glargine. Whether hyperinsulinemia is able to mediate EGFR-TKI resistance in the NSCLC cell line harboring activating EGFR mutations was also investigated, and the possible underlying mechanisms responsible for these actions were explored. The inhibition of cell proliferation, and the potential mechanism of gefitinib resistance, were examined using an MTS proliferation assay and western blot analysis, and through the transfection of siRNAs. Whether the inhibition of AKT is able to overcome EGFR-TKI resistance induced by long-acting insulin was also investigated. The results obtained suggested that hyperinsulinemia induced by glargine upregulated NSCLC cell proliferation and survival, and induced gefitinib resistance. By contrast, the morphology and proliferation of the cells in a medium containing a 2-fold concentration of glucose were not significantly affected. Gefitinib resistance induced by hyperinsulinemia may have been mediated via the phosphoinositide 3-kinase (PI3K)/AKT pathway rather than the mitogen-activated protein kinase extracellular signal regulated kinase (MAPK/ERK) pathway. AKT serine/threonine kinase 1 knockdown by siRNA rescued the gefitinib resistance that was induced by hyperinsulinemia. In conclusion, hyperinsulinemia, but not hyperglycemia, was identified to cause the development of gefitinib resistance in NSCLC cells with activating EGFR mutations. However, additional studies are required to investigate strategies, such as co targeting hyperinsulinemia and the PI3K/AKT pathway, for overcoming EGFR-TKI resistance in patients with NSCLC.

Natural tyrosine kinase inhibitors acting on the epidermal growth factor receptor: Their relevance for cancer therapy

Epidermal growth factor receptor (EGFR), also known as ErbB-1/HER-1, plays a key role in the regulation of the cell proliferation, migration, differentiation, and survival. Since the constitutive activation or overexpression of EGFR is nearly found in various cancers, the applications focused on EGFR are the most widely used in the clinical level, including the therapeutic drugs of targeting EGFR, monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs).Over the past decades, the compounds from natural sources have been a productive source of novel drugs, especially in both discovery and development of anti-tumor drugs by targeting the EGFR pathways as the TKIs. This work presents a review of the compounds from natural sources as potential EGFR-TKIs involved in the regulation of cancer. Moreover, high-throughput drug screening of EGFR-TKIs from the natural compounds has also been summarized.

Torin2 inhibits the EGFR-TKI resistant Non-Small Lung Cancer cell proliferation through negative feedback regulation of Akt/mTOR signaling

It is known that mammalian target of rapamycin (mTOR) signaling plays an important role in NSCLC cells proliferation. Torin2 is a second-generation ATP-competitive inhibitor which is selective for mTOR activity. In this study, we investigated whether torin2 was effective against lung cancer cells, especially EGFR-TKIs resistant NSCLC cells. We found that torin2 dramatically inhibited EGFR-TKI resistant cells viability in vitro. In xenograft model, torin2 treatment significantly reduced the volume and weight of xenograft tumor in the erlotinib resistant PC9/E cells. Additionally, autophagy protein of phosphatidylethanolamine-modified microtubule-associated protein light-chain 3II/I (LC3II/I) increased in PC9/E after torin2 treatment. Torin2 blocked the level of phosphorylated S6 and the phosphorylation of Akt at both T308 and S473 sites compared with erlotinib treatment. Furthermore, TUNEL assay showed that apoptosis of tumor tissue increased significantly in the torin2 treatment group. Immunohistochemical analysis demonstrated that tumor angiogenesis was obviously inhibited by torin2 treatment in EGFR-TKI resistant group. Collectively, our results suggested that torin2 could inhibit the NSCLC cells proliferation by negative feedback regulation of Akt/mTOR signaling and inducing autophagy. This suggests that torin2 could be a novel therapeutic approach for EGFR-TKI resistant NSCLC.

Loss of Mitochondrial DNA by Gemcitabine Triggers Mitophagy and Cell Death

Gemcitabine (2,2-difluorodeoxycytidine nucleic acid), an anticancer drug exhibiting a potent ability to kill cancer cells, is a frontline chemotherapy drug. Although some chemotherapeutic medicines are known to induce nuclear DNA damage, no investigation into mitochondrial DNA (mtDNA) damage currently exists. When we treated insulinoma pancreatic β-cells (line INS-1) with high mitochondrial activity with gemcitabine for 24 h, the mtDNA contents were decreased. Gemcitabine induced a decrease in the number of mitochondria and the average potential of mitochondrial membrane in the cell but increased the superoxide anion radical levels. We observed that treatment with gemcitabine to induce cell death accompanied by autophagy-related protein markers, Atg5 and Atg7; these were significantly prevented by the autophagy inhibitors. The localization of Atg5 co-occurred with the location of mitochondria with membranes having high potential and mitophagy in cells treated with gemcitabine. The occurrence of mitophagy was inhibited by the inhibitors of the phosphatidylinositol 3-kinase/Akt pathway. Our results led us to the conclusion that gemcitabine induced cell death through mitophagy with the loss of mtDNA. These findings may provide a rationale for the combination of mtDNA damage with mitophagy in future clinical applications for cancer cells.

Metformin Prolongs Survival in Type 2 Diabetes Lung Cancer Patients With EGFR-TKIs

Background: Metformin use reportedly reduces cancer risk and improves survival in lung cancer patients. This study aimed to investigate the effect of metformin use in patients with diabetes mellitus (DM) and lung cancer receiving epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) therapy. Methods: A nationwide, population-based cohort study was conducted using the Taiwan National Health Insurance Research Database. From January 1, 2004, to December 31, 2012, a total of 373 metformin and 1260 non-metformin lung cancer cohorts with type 2 DM and EGFR-TKI treatment were studied. Results: Metformin use was significantly associated with a reduced risk of death (hazard ratio: 0.73, 95% confidence interval [CI]: 0.62-0.85, P < .001), as well as a significantly longer median progression-free survival (9.2 months, 95% CI: 8.6-11.7, vs 6.4 months, 95% CI: 5.9-7.2 months, P < .001) and median overall survival (33.4 months, 95% CI: 29.4-40.2, vs 25.4 months, 95% CI: 23.7-27.2 months, P < 0.001). Conclusions: In conclusion, metformin may potentially enhance the therapeutic effect and increase survival in type 2 DM patients with lung cancer receiving EGFR-TKI therapy.

The Molecular Mechanism of Metabolic Remodeling in Lung Cancer

Metabolic remodeling is a key phenomenon in the occurrence and development of tumors. It not only offers materials and energy for the survival and proliferation of tumor cells, but also protects tumor cells so that they may survive, proliferate and transfer in the harsh microenvironment. This paper attempts to reveal the role of abnormal metabolism in the development of lung cancer by considering the processes of glycolysis and lipid metabolism, Identification of the molecules that are specifically used in the processes of glycolysis and lipid metabolism, and their underlying molecular mechanisms, is of great clinical and theoretical significance. We will focus on the recent progress in elucidating the molecular mechanism of metabolic remodeling in lung cancer.

Gefitinib-coated balloon inhibits the excessive hyperplasia of intima after vascular injuries through PI3K/AKT pathway

OBJECTIVE

To explore the effect of gefitinib-coated balloon suppressive action on the excessive hyperplasia of intima after balloon injury of common carotid artery in rats and on the PI3K/AKT signal pathway.

METHODS

MTT method and the expression of Bcl-2 and Caspase-3 proteins were detected in vitro; Adult SD rats were randomly split into 5 groups, namely sham group, model group, low-dosage gefitinib-coated balloon group, high-dosage gefitinib-coated balloon group, and paclitaxel-coated balloon group. The intimal proliferation of arteries, PCNA, P-AKT and PI3K protein expression, the cell apoptosis, expression of MMP9, TGFβ and IL6 mRNA were measured by hematoxylin and eosin (H&E) staining, immunohistochemistry, TUNEL staining, and RT-qPCR.

RESULTS

At the same time and concentration, Gefitinib suppressed the proliferation of smooth muscle cell more significantly than paclitaxel. Bcl-2 and Caspase-3 in vascular smooth muscle and endothelial cells (VSMC, EC) were significantly down-regulated and up-regulated after the cells were treated with gefitinib and paclitaxel. In gefitinib- and paclitaxel-coated balloon groups, significant up-regulations were found in the area of lumen. Furthermore, the expression of PCNA suggested that all coated balloons could suppress the excessive proliferation of smooth muscle cells in the hyperplastic intima compared with the control group. In gefitinib- and paclitaxel-coated balloon group, the expression of PI3K/AKT was significantly down-regulated. The use of drug-coated balloons mitigated the cell apoptosis in TUNEL. The expressions of MMP9, TGFβ and IL6 mRNA in the model group were obviously up-regulated; and they were obviously down-regulated in the high-dose gefitinib-coated balloon group compared with the model group.

CONCLUSIONS

Gefitinib-coated balloons were able to suppress the excessive proliferation in the common carotid arterial intima of rats more effectively than the paclitaxel-coated ones. The underlying mechanism may cover the PI3K/AKT signal pathway.

The emergence of drug resistance to targeted cancer therapies: Clinical evidence

For many decades classical anti-tumor therapies included chemotherapy, radiation and surgery; however, in the last two decades, following the identification of the genomic drivers and main hallmarks of cancer, the introduction of therapies that target specific tumor-promoting oncogenic or non-oncogenic pathways, has revolutionized cancer therapeutics. Despite the significant progress in cancer therapy, clinical oncologists are often facing the primary impediment of anticancer drug resistance, as many cancer patients display either intrinsic chemoresistance from the very beginning of the therapy or after initial responses and upon repeated drug treatment cycles, acquired drug resistance develops and thus relapse emerges, resulting in increased mortality. Our attempts to understand the molecular basis underlying these drug resistance phenotypes in pre-clinical models and patient specimens revealed the extreme plasticity and adaptive pathways employed by tumor cells, being under sustained stress and extensive genomic/proteomic instability due to the applied therapeutic regimens. Subsequent efforts have yielded more effective inhibitors and combinatorial approaches (e.g. the use of specific pharmacologic inhibitors with immunotherapy) that exhibit synergistic effects against tumor cells, hence enhancing therapeutic indices. Furthermore, new advanced methodologies that allow for the early detection of genetic/epigenetic alterations that lead to drug chemoresistance and prospective validation of biomarkers which identify patients that will benefit from certain drug classes, have started to improve the clinical outcome. This review discusses emerging principles of drug resistance to cancer therapies targeting a wide array of oncogenic kinases, along with hedgehog pathway and the proteasome and apoptotic inducers, as well as epigenetic and metabolic modulators. We further discuss mechanisms of resistance to monoclonal antibodies, immunomodulators and immune checkpoint inhibitors, potential biomarkers of drug response/drug resistance, along with possible new therapeutic avenues for the clinicians to combat devastating drug resistant malignancies. It is foreseen that these topics will be major areas of focused multidisciplinary translational research in the years to come.

The antipsychotic agent flupentixol is a new PI3K inhibitor and potential anticancer drug for lung cancer

Background: The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is hyperactivated in lung cancer and regulates a broad range of cellular processes, including proliferation, survival, angiogenesis, and metastasis. Thus PI3K is considered a promising target for therapy. To date, PI3K inhibitors have not been approved for lung cancer. Recent studies showed that the antipsychotic agent flupentixol induced apoptosis of lung cancer cell, however the anti-tumor mechanism of flupentixol remains unclear.

Methods: (1) The idock software simulated the molecular docking between the PI3Kα protein and flupentixol. (2) Inhibition of PI3Kα by the flupentixol was examined by in vitro kinase assays. (3) The cytotoxicity of flupentixol on the NSCLC cell lines was tested by MTT assays. (4) We treated A549 and H661 cells with flupentixol and then measured the percentage of apoptotic cells by the Annexin V/PI analysis. (5) We investigated the effect of flupentixol on the expression of critical PI3K/AKT signaling pathway proteins, further analyzed on the cleavage of PARP and caspase-3 by Western blotting. (6) BALB/C nude mice were subcutaneously injected with A549 cells to evaluate the effect of flupentixol on the growth of lung carcinoma.

Results: Structural analysis of the predicted binding conformation suggested that flupentixol docks to the ATP binding pocket of PI3Kα. Kinase assays demonstrate that flupentixol indeed inhibited the PI3Kα kinase activity. Flupentixol exhibited cytotoxicity in lung cancer cell lines A549 and H661 in a dose- and time-dependent manner. Furthermore, flupentixol more strongly inhibited the phosphorylation of AKT (T308 and S473) and the expression of its downstream target gene Bcl-2 than two known PI3K inhibitors (BYL719 and BKM120). Flupentixol induced apoptosis as measured by PARP and caspase-3 cleavage. Finally, flupentixol significantly suppressed A549 xenograft growth in BALB/C nude mice.

Conclusions: Flupentixol could be docked to the PI3Kα protein and specifically inhibit the PI3K/AKT pathway and survival of lung cancer cells in vitro and in vivo. As an old drug, flupentixol is a new PI3K inhibitor that may be used for the treatment of lung cancers.

Blocking ROR1 enhances the roles of erlotinib in lung adenocarcinoma cell lines

Treatment strategies involving tyrosine kinase inhibitors (TKIs) for patients with non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations have advanced significantly; however, challenges still remain regarding the development of resistance. It has been reported that receptor tyrosine kinase-like orphan receptor 1 (ROR1) acts as a hepatocyte growth factor receptor (MET) and c-Src substrate, and that the extracellular domain of ROR1 is associated with EGFR to sustain EGFR-ERBB3-PI3K signaling. Our previous study reported that blocking ROR1 significantly decreased the activity of key signal molecules in the AKT/mammalian target of rapamycin (mTOR) signaling pathway, which was associated with a significant increase of apoptosis and significant decrease of proliferation of lung adenocarcinoma cells. The present study hypothesized that inhibiting ROR1 could potentially prevent erlotinib resistance in NSCLC cell lines. Investigations were performed with two erlotinib-resistant cell lines XLA-07 and NCI-H1975, and an erlotinib-acquired-resistant cell line PC-9erlo, which was developed from its parental cell line PC-9. It was identified that the inhibition of ROR1 via small interfering RNA treatment significantly improved the anti-proliferation and apoptosis-inducing roles of erlotinib in TKI-resistant tumor cells. This was in accordance with the activity of key molecules of the AKT/mTOR signaling pathway, including glycogen synthase kinase-3α/β (GSK-3α/β), phosphatase and tensin homolog (PTEN), AKT, mTOR and ribosomal protein S6 kinase β-1 (p70S6K). The current data suggest that targeting ROR1 is a potential novel treatment strategy for patients with ROR1-positive NSCLC, particularly those with acquired resistance to EGFR-TKI.

Tumor-associated macrophages affect the biological behavior of lung adenocarcinoma A549 cells through the PI3K/AKT signaling pathway

Tumor associated macrophages (TAMs) are a major type of inflammatory cell in a tumor microenvironment. Previous evidence has suggested that TAMs promote tumorigenesis, growth, invasion and metastasis, thereby affecting tumor metabolism. The mechanisms through which they affect the invasion and metastasis of lung cancer cells remain unclear. The present study investigated the effects and molecular mechanisms of TAMs on the proliferation, invasion and migration of lung adenocarcinoma A549 cells. Human mononuclear leukemia THP-1 cells were induced into TAMs. The morphological changes that occurred during the induction of the THP-1 cells were examined with a light microscope. Successful TAM formation was confirmed via flow cytometry. Proliferation, invasion and migration of the lung adenocarcinoma A549 cells were detected by EDU proliferation, scratch wound and Transwell invasion and migration assays, respectively. The expression levels of key proteins involved in the PI3K/AKT signaling pathway were detected by western blot analysis. It was identified that treatment with interleukin (IL)-4, IL-13 and Phorbol-12-myristate-13-acetate successfully induced THP-1 to form TAMs. The indirect coculture model of TAMs was established by Transwell chamber detection, and the proliferation, invasion and migration ability of lung adenocarcinoma A549 cells were enhanced. Western blot analysis indicated that the expression levels of phosphorylated (p)-PI3K and p-AKT proteins were significantly upregulated in the TAMs coculture group compared with that of the blank control group. In summary, the present study demonstrated that TAMs may promote the proliferation, invasion and migration of lung adenocarcinoma A549 cells in vitro, perhaps through the activation of the PI3K/AKT signaling pathway.

The novel PI3K inhibitor S1 synergizes with sorafenib in non-small cell lung cancer cells involving the Akt-S6 signaling

Non-small cell lung cancer (NSCLC) has been the major cause of cancer-related deaths worldwide. Targeted therapy has been available as an additive strategy for NSCLC patients, but the inevitable resistance to mono-targeted agents has largely hampered its usage in the clinic. We have previously designed and synthesized a novel small molecule compound S1, 2-methoxy-3-phenylsulfonamino-5-(quinazolin-6-yl) benzamides and demonstrated its inhibition of PI3K and mTOR as well as the anti-tumor potential. In the present study, we have identified that S1 alone or combined with the multi-kinase inhibitor sorafenib can inhibit the in vitro cell proliferation of NSCLC cells (A549, NCI-H157 and 95D cells) and tumor growth in the A549 xenograft model. S1 alone produced inhibitory effects on the colony formation, cell migration and invasion and angiogenesis, with more pronounced inhibition when used with sorafenib. We further revealed that S1 mainly inhibited the Akt/S6 phosphorylation while sorafenib mostly decreased the phosphorylation of ERK. Together, the novel PI3K/mTOR inhibitor S1 per se exhibits strong anti-tumor effects in NSCLC cells and A549 xenograft, effects possibly via its inhibition of cell proliferation, invasion and migration and angiogenesis. The combination of S1 and sorafenib exerts potentiated anti-tumor effects, in which the underlying mechanisms may involve their differential modulation of the phosphorylation of Akt and S6 in the PI3K/Akt/mTOR cascades and ERK phosphorylation in the Raf/MEK/ERK pathways. The combination of S1 and sorafenib could be used as an additive approach in treating NSCLC in the clinic.

Anticancer activity of 2'-hydroxyflavanone towards lung cancer

In previous studies, we found that 2'-hydroxyflavonone (2HF), a citrus flavonoid, inhibits the growth of renal cell carcinoma in a VHL-dependent manner. This was associated with the inhibition of glutathione S-transferases (GSTs), the first step enzyme of the mercapturic acid pathway that catalyzes formation of glutathione-electrophile conjugates (GS-E). We studied 2HF in small cell (SCLC) and non-small cell (NSCLC) lung cancer cell lines for sensitivity to 2HF antineoplastic activity and to determine the role of the GS-E transporter Rlip (Ral-interacting protein; RLIP76; RALBP1) in the mechanism of action of 2HF. Our results show that 2HF induced apoptosis in both histological types of lung cancer and inhibited proliferation and growth through suppression of CDK4, CCNB1, PIK3CA, AKT and RPS6KB1 (P70S6K) signaling. Increased E-cadherin and reduced fibronectin and vimentin indicated inhibition of epithelial-mesenchymal transition. Additionally, 2HF inhibited efflux of doxorubicin and increased its accumulation in the cells, but did not add to the transport inhibitory effect of anti-Rlip antibodies alone. Binding of Rlip to 2HF was evident from successful purification of Rlip by 2HF affinity chromatography. Consistent with increased drug accumulation, combined treatment with 1-chloro-2, 4-dinitrobenzene, reduced the GI50 of 2HF by an order of magnitude. Results of in-vivo nude mouse xenograft studies of SCLC and NSCLC, which showed that orally administered 2HF inhibited growth of both histological types of lung cancer, confirmed in-vitro study results. Our result suggest that Rlip inhibition is likely a mechanism of action. Our findings are basis of proposing 2HF as therapeutic or preventative drug for lung cancer.

Research progress on the impact of radiation on TKI resistance mechanisms in NSCLC

Resistance to tyrosine kinase inhibitor (TKI) therapy is often accompanied by various genetic alterations, and radiation is an important weapon for changing the DNA of tumor cells. In radiotherapy combined with TKI therapy for non-small cell lung cancer (NSCLC), the two treatment strategies affect and interact with each other, resulting in complex tumor resistance mechanisms. Accordingly, tumor progression management after radiotherapy combined with TKI therapy should be different from that after TKI therapy alone. However, current clinical practice is entirely based on the resistance mechanisms of simple TKI therapy. Therefore, it is imperative to investigate the impact of radiation on the mechanism of TKI resistance. However, due to the complexity of the resistance mechanisms under the combined effect of both therapies, such studies remain extremely challenging and time-consuming.

BENC-511, a novel PI3K inhibitor, suppresses metastasis of non-small cell lung cancer cells by modulating β-catenin/ZEB1 regulatory loop

Non-small cell lung cancer (NSCLC) is known as highly metastatic disease because it is difficult to diagnose at early stage. More than 60% of NSCLC patients' overexpress receptor tyrosine kinase (RTK) such as EGFR that has been proved to display resistance to receptor tyrosine kinase inhibitor (TKI) through PI3K signaling, while single PI3K inhibitors increase RTK expression as feedback. So, to select the proper targeted agent or target an assortment of molecular subsets, such as EGFR mutations for different subgroups of patients with NSCLC is urgent. Compound BENC-511, a potent PI3K inhibitor, had effects on inhibiting cancer cell survival and delaying tumor growth, but the effects and mechanisms on cancer metastasis are not clear. Methods of Scratch assay, Transwell system, experimental metastasis mice models, plasmid transfection, quantitative real-time PCR and Western blot were used. Results showed that BENC-511 could significantly inhibit lung cancer cells invasion and metastasis both in vitro and in vivo. And it not only inhibited PI3K/Akt signal pathway, but also directly suppressed phosphorylation of EGFR and nuclear translocation of β-catenin. Moreover, our study firstly reported BENC-511 seemed more sensitive to NSCLC cells that highly expressed Zinc-finger E-box binding protein 1 (ZEB1), one of the epithelial-mesenchymal transition (EMT) inducer, and knockdown of ZEB1 could improve the effects of this compound. These findings suggested that BENC-511 should be a promising lead molecule for anti-metastasis therapy by targeting β-catenin/ZEB1 regulatory loop and serve as a therapeutic agent to inhibit metastasis of NSCLC.

MiR-199a-3p enhances cisplatin sensitivity of cholangiocarcinoma cells by inhibiting mTOR signaling pathway and expression of MDR1

Several studies have reported reduced miRNA-199a-3p (miR-199a-3p) in different human malignancies, however, little is known about miR-199a-3p in cholangiocarcinoma cells. In this study, we demonstrate the essential role and mechanism of miR-199a-3p in regulating cisplatin sensitivity in cholangiocarcinoma cell lines. Using a CCK-8 cell counting assay we found that expression of miR-199a-3p was positively correlated with cisplatin sensitivity in cholangiocarcinoma cell lines. MiR-199a-3p overexpression could decrease the proliferation rate and increase apoptosis of cholangiocarcinoma cells in the presence of cisplatin, while miR-199a-3p inhibition had the opposite effect. Further study demonstrated that mTOR was the target gene of miR-199a-3p, and that miR-199a-3p mimics could inhibit expression of mTOR, which consequently reduced the phosphorylation of its downstream proteins 4EBP1 and p70s6k. Rescue experiments proved that miR-199a-3p could increase the cisplatin sensitivity of cholangiocarcinoma cell lines by regulating mTOR expression. Moreover, we also found that miR-199a-3p overexpression could reduce cisplatin induced MDR1 expression by decreasing the synthesis and increasing the degradation of MDR1, thus enhancing the effectiveness of cisplatin in cholangiocarcinoma. In conclusion, miR-199a-3p could increase cisplatin sensitivity of cholangiocarcinoma cell lines by inhibiting the activity of the mTOR signaling pathway and decreasing the expression of MDR1.

Heterogeneity of resistance mutations detectable by nextgeneration sequencing in TKI-treated lung adenocarcinoma

EGFR-mutated lung adenocarcinomas routinely develop resistance to tyrosine kinase inhibitors (TKI). To better characterize the relative frequencies of the resistance mechanisms, we analyzed 48 EGFR-mutated TKI-resistant specimens from 41 patients. Next-generation sequencing of post-treatment specimens detected EGFR p.T790M in 31 (79%) of 39 patients, PIK3CA mutations in 10 (26%), EGFR p.S768_V769delinsIL in one, and KRAS p.G12C in one. Five PIK3CA mutations were outside of codons 542, 545, and 1047. Three of four pre-treatment specimens did not carry the PIK3CA mutation found in the post-treatment sample. Small cell carcinoma transformation was identified in four patients; none had p.T790M, including two where p.T790M was identified in the co-existing adenocarcinoma. In p.T790M-mutated specimens, the allele frequency was less than 5% in 24% of cases. p.T790M allele frequency was usually lower than that of the sensitizing mutation indicating that the resistance mutation was present either in a subset of cells or, if the sensitizing mutation was amplified, in a subset of the sensitizing alleles of a dominant clone. Eight patients had multiple resistance mutations, suggesting either multiple separate resistant clones or a single clone harboring multiple resistance mechanisms. PIK3CA mutations appear to be a more significant resistance mechanism than previously recognized.

CGP57380 enhances efficacy of RAD001 in non-small cell lung cancer through abrogating mTOR inhibition-induced phosphorylation of eIF4E and activating mitochondrial apoptotic pathway

The mammalian target of rapamycin (mTOR) is a potentially important therapeutic target in a broad range of cancer types. mTOR inhibitors such as rapamycin and its analogs (rapalogs) have been proven effective as anticancer agents in non-small cell lung cancer (NSCLC), whereas they strongly enhance phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) and activation of Akt, which cause resistance to mTOR-targeted therapy after an initial response. Rapamycin induces eIF4E phosphorylation by activating MAPK-interacting kinases (Mnks), and therefore targeting Mnk/eIF4E pathway represents a potential therapeutic strategy for the treatment of NSCLC. Here, our results showed that over-expression of p-Mnk1 and p-eIF4E was significantly associated with poor overall survival of NSCLC patients and high expression of p-Mnk1 might act as an independent prognostic biomarker for these patients. Meanwhile, inhibiting Mnk1 expression by Mnk inhibitor (CGP57380) could abrogate rapalogs (RAD001)-induced eIF4E phosphorylation and Akt activation. Furthermore, combination of CGP57380 and RAD001 could induce NSCLC cells apoptosis via activating intrinsic mitochondrial pathway, and exert synergistic antitumor efficacy both in vitro and in vivo. In conclusion, combination of targeting both mTOR and Mnk/eIF4E signaling pathways to enhance effectiveness of mTOR-targeted cancer therapy might be significant innovation for the personalized treatment of NSCLC.

Resensitization of Akt Induced Docetaxel Resistance in Breast Cancer by 'Iturin A' a Lipopeptide Molecule from Marine Bacteria Bacillus megaterium

Development of the resistance is the major problem in cancer therapy. Docetaxel is a taxol alkaloid that is frequently used in metastatic breast cancer. However, resistance often limits the usefulness of this drug in many breast cancer patients. Manipulation of resistant cells to re-sensitize to the therapeutic effect of docetaxel is current strategy to overcome this problem. Here, we have introduced ‘Iturin A’ as a potent chemosensitizer in docetaxel resistant breast cancer cells. Combination of Iturin A and docetaxel treatment significantly hampered the proliferation of docetaxel resistant MDA-MB-231 and MDA-MB-468 breast cancer cells. Cell cycle analysis also showed massive amount of apoptotic population (Sub G0/G1) in combination therapy. A number of apoptotic and anti-apoptotic proteins were significantly altered in dual drug treated groups. Caspase 3 dependent cell death was observed in dual treatment. Molecular mechanism study showed that over-expression of Akt and its downstream signaling pathway was associated with docetaxel resistance. Iturin A significantly reduced Akt signaling pathway in resistant cells. This mechanistic action might be the reason behind the chemo-sensitization effect of Iturin A in docetaxel resistant breast cancer cells. In conclusion, Iturin A resensitized the resistant breast cancer cells to docetaxel therapy by inhibiting Akt activity.

Mechanisms of resistance to irreversible epidermal growth factor receptor tyrosine kinase inhibitors and therapeutic strategies in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) T790M mutation is the most frequent mechanism which accounts for about 60% of acquired resistance to first-generation EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) patients harboring EGFR activating mutations. Irreversible EGFR-TKIs which include the second-generation and third-generation EGFR-TKIs are developed to overcome T790M mediated resistance. The second-generation EGFR-TKIs inhibit the wide type (WT) EGFR combined with dose-limiting toxicity which limits its application in clinics, while the development of third-generation EGFR-TKIs brings inspiring efficacy either in vitro or in vivo. The acquired resistance, however, will also occur and limit their response. Understanding the mechanisms of resistance to irreversible EGFR-TKIs plays an important role in the choice of subsequent treatment. In this review, we show the currently known mechanisms of resistance which can be summarized as EGFR dependent and independent mechanisms and potential therapeutic strategies to irreversible EGFR-TKIs.

Inhibition of miR-23a increases the sensitivity of lung cancer stem cells to erlotinib through PTEN/PI3K/Akt pathway

Epidermal growth factor receptor-targeted tyrosine kinase inhibitors (EGFR-TKIs) have become first-line drugs used for non-small cell lung cancer (NSCLC) treatment. However, drug resistance to EGFR-TKIs will be developed inevitably due to the repeated use of these drugs. In the present study, we isolated cancer stem cells (CSCs) from the PC9 NSCLC cell line. We then observed that the PC9 CSCs showed significant resistance to erlotinib compared with the PC9 non-CSCs. Erlotinib failed to suppress the phosphorylation of PI3K and AKT in PC9 CSCs, although the EGFR was inhibited sufficiently. Mechanically, we observed aberrant upregulation of microRNA-23a (miR-23a) and downregulation of PTEN in PC9 CSCs compared to PC9 non-CSCs. Luciferase reporter assays proved that PTEN was the target of miR-23a in PC9 CSCs. Furthermore, knockdown of miR-23a enhanced the antitumor effect of erlotinib by increasing the expression of PTEN. In addition, transfection with miR-23a inhibitors promoted the erlotinib-dependent inhibition of PI3K/AKT pathway, thus, suppressing the proliferation and inducing apoptosis in PC9 CSCs. These results propose that upregulation of miR-23a is a potential mechanism associated with resistance to EGFR-TKIs in lung cancer stem cells. Inhibition of miR-23a serves as a novel therapeutic strategy to eliminate the EGFR-TKIs resistance of lung cancer stem cells.

miRNA-125b regulates apoptosis of human non-small cell lung cancer via the PI3K/Akt/GSK3β signaling pathway

The present investigation demonstrated that regulation of microRNA (miR)-125b affected the apoptosis of human non-small cell lung cancer (NSCLC) through targeting of the PI3K/Akt and Wnt/β-catenin signaling pathways. The expression of miR-125b was assessed in patients with NSCLC, which demonstrated that miR-125b expression in NSCLC tissue was higher than that in para-carcinoma tissue. Furthermore, survival analysis of patients with NSCLC over 3 years indicated that the overall survival (OS) and disease-free survival (DFS) rates of patients with low miR-125b expression were higher than those of patients with high miR-125b expression. Proliferation and apoptosis assays were subsequently conducted in the human NSCLC cell line A549 using MTT assay and Annexin V-FITC/PI kits, respectively. Caspase-3 activity ELISA and western blot analysis were also used to assess caspase-3 activity and the protein expression of Bax, Akt, phosphorylated (p)-Akt, p-GSK3β, Wnt and β-catenin. It was observed that downregulation of miR-125b inhibited the proliferation and induced the apoptosis of A549 cells. Downregulation of miR-125b also suppressed the protein expression of p-Akt, Wnt and β-catenin, and increased caspase-3 activity and Bax protein expression in A549 cells. In addition, downregulation of miR-125b combined with the PI3K inhibitor LY294002 enhanced cell growth inhibition, suppression of p-GSK3β, Wnt and β-catenin protein expression and promotion of caspase-3 activity in A549 cells. These results revealed that the downregulation of miR-125b regulates apoptosis in human NSCLC through the suppression of the PI3K/Akt/GSK3β and Wnt/β-catenin signaling pathways.

Inhibition of Human Lung Cancer Cell Proliferation and Survival by Post-Exercise Serum Is Associated with the Inhibition of Akt, mTOR, p70 S6K, and Erk1/2

Non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer cases, and for the most cancer-related deaths. The survival pathway of Akt, its downstream effectors, the mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70 S6K), and the Ras-extracellular signal-regulated kinase (Erk1/2) pathways are activated in cancer leading to cell survival and growth. Thus, approaches that inhibit these signaling molecules may prove useful in the fight against lung cancer. Exercise is associated with health benefits and a limited number of studies indicate that serum from physically active individuals inhibit mammary and prostate cancer cell growth. In this study, we examined the effects of post exercise serum on proliferation, survival, and signaling cascades of human NSCLC cells. Blood was collected from male subjects prior to, 5 min, 1 h, and 24 h after a single bout of high intensity interval exercise on a cycle ergometer. Exposure of NSCLC cells to post exercise serum resulted in the inhibition of cell proliferation and survival, as well as significant reduction of phosphorylated/activated Akt, mTOR, p70 S6K, and Erk1/2 levels compared to cells treated with serum taken pre-exercise. Our data suggest that post exercise serum has anti-cancer properties in lung cancer and deserves further systematic investigation in animal models.

Capilliposide from Lysimachia capillipes inhibits AKT activation and restores gefitinib sensitivity in human non-small cell lung cancer cells with acquired gefitinib resistance

Most gefitinib-treated patients with non-small cell lung cancer (NSCLC) would eventually develop resistance. Lysimachia capillipes (LC) capilliposide extracts from LC Hemsl. show both in vitro and in vivo anti-cancer effects. In this study we investigated whether LC capilliposide in combination with gefitinib could overcome the resistance of NSCLC cells to gefitinib and identified the signaling pathways involved. Treatment with LC capilliposide alone inhibited the growth of a panel of NSCLC cell lines (PC-9, H460, H1975, H1299 and PC-9-GR) sensitive or resistant to gefitinib with IC₅₀ values in the range of μg/mL. In the gefitinib-resistant PC-9-GR cells (which have a T790M EGFR mutation), LC capilliposide (at the IC30, i.e.1.2 μg/mL) markedly enhanced the inhibitory effects of gefitinib with its IC50 value being decreased from 6.80±1.00 to 0.77±0.12 μmol/L. By using the median effect analysis we showed that combination treatment of LC capilliposide and gefitinib could restore gefitinib sensitivity in PC-9-GR cells. Furthermore, LC capilliposide (1.2 μg/mL) significantly increased the apoptotic responses to gefitinib (0.77 μmol/L) in PC-9-GR cells, but did not affect gefitinib-induced G₀/G₁ arrest. Moreover, LC capilliposide (1.2 μg/mL) in combination with gefitinib (0.77, 1.0 μmol/L) markedly decreased the phosphorylation of the EGFR downstream signaling molecule AKT, which neither LC capilliposide nor gefitinib alone affected. In PC-9-GR cells with siRNA knockdown of AKT, addition of LC capilliposide was unable to increase gefitinib sensitivity. In a PC-9-GR xenograft mouse model, combination treatment with LC capilliposide (15 mg·kg^-1·d^-1, ip) and gefitinib (50 mg·kg^-1·d^-1, ip) dramatically enhanced tumor growth suppression (with a TGI of 109.3%), compared with TGIs of 22.6% and 56.6%, respectively, in mice were treated with LC capilliposide or gefitinib alone. LC capilliposide can restore the cells' sensitivity to gefitinib through modulation of pAKT levels, suggesting that a combination of LC capilliposide and gefitinib may be a promising therapeutic strategy to overcome gefitinib resistance in NSCLCs with a T790M mutation.

Phase Ib Study of Safety and Pharmacokinetics of the PI3K Inhibitor SAR245408 with the HER3-Neutralizing Human Antibody SAR256212 in Patients with Solid Tumors

Purpose: This phase Ib study was designed to determine the MTD, safety, preliminary efficacy, and pharmacokinetics of the HER3 (ErbB3) mAb SAR256212 in combination with the oral PI3K inhibitor SAR245408 for patients with metastatic or locally advanced solid tumors.Experimental Design: Patients received the combination of intravenous SAR256212 and oral SAR245408 in a 3 + 3 dose-escalation design until occurrence of disease progression or dose-limiting toxicity. Objective response rate, pharmacokinetics, pharmacodynamics, and PIK3CA mutational status were also evaluated.Results: Twenty-seven patients were enrolled. Thirteen of 20 patients tested (65%) had a hotspot-activating mutation in PIK3CA in their tumor. The MTD was determined to be SAR256212 at 40 mg/kg loading dose followed by 20 mg/kg weekly, plus SAR245408 200 mg daily. Dose-limiting toxicities included rash and hypotension; the most frequent treatment-related side effect was diarrhea (66.7%). Twenty-three patients were evaluable for efficacy, of which 12 patients (52.2%) had stable disease and 11 patients (47.8%) had progression of disease as best response. In this study with a limited sample size, there was no difference in best response between patients with PI3KCA-mutant versus PIK3CA wild-type tumors (P = 0.07). The concurrent administration of SAR245408 and SAR256212 did not appear to have an effect on the pharmacokinetics of either drug.Conclusions: The combination of SAR256212 and SAR245408 resulted in stable disease as the best response. Side effects seen in combination were similar to the profiles of each individual drug. Patient outcome was the same regardless of tumor PI3KCA mutation status. Clin Cancer Res; 23(14); 3520-8. ©2016 AACR.

Allosteric therapies for lung cancer

Allostery is a regulation at a distance by conveying information from one site to another and an intrinsic property of dynamic proteins. Allostery plays an essential role in receptor trafficking, signal transmission, controlled catalysis, gene turn on/off, or cell apoptosis. Allosteric mutations are considered as one of causes responsible for cancer development, leading to "allosteric diseases" by stabilizing an active or inactive conformation or changing the dynamic distribution of preexisting propagation pathways. The present article mainly focuses on the potential of allosteric therapies for lung cancer. Allosteric drugs may have several advantages over traditional drugs. The epidermal growth factor receptor mutations and signaling pathways downstream (such as PI3K/AKT/mTOR and RAS/RAF/MEK/ERK pathways) were suggested to play a key role in lung cancer and considered as targets of allosteric therapy. Some allosteric inhibitors for lung cancer-specific targets and a series of preclinical trials of allosteric inhibitors for lung cancer have been developed and reported. We expect that allosteric therapies will gain more attentions to develop combinatorial strategies for lung cancer and metastasis.

Gamma-synuclein binds to AKT and promotes cancer cell survival and proliferation

Hyperactivation of AKT plays a critical role in the survival and proliferation of cancer cells. However, the molecular mechanisms underlying AKT activation remain elusive. Here, we tested the effect of γ-synuclein, a member of the synuclein family of proteins, on the activation of AKT. We show that the expression level of γ-synuclein is increased in non-small cell lung cancer (NSCLC) tissues. γ-Synuclein binds to the protein kinase domain of AKT and promotes its phosphorylation. Overexpression of γ-synuclein in H157 cells enhances cell proliferation and protects the cells from staurosporine-induced cytotoxicity. Knockdown of γ-synuclein attenuates AKT activation and cell proliferation induced by epidermal growth factor. The effect of γ-synuclein is abolished when AKT is depleted. Thus, γ-synuclein promotes cell survival and proliferation via activating AKT and may play a causal role in the pathogenesis of NSCLC.

Non-Invasive Methods to Monitor Mechanisms of Resistance to Tyrosine Kinase Inhibitors in Non-Small-Cell Lung Cancer: Where Do We Stand?

The induction of resistance mechanisms represents an important problem for the targeted therapy of patients with non-small-cell lung cancer (NSCLC). The best-known resistance mechanism induced during treatment with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) is EGFR T790M mutation for which specific drugs are have been developed. However, other molecular alterations have also been reported as induced resistance mechanisms to EGFR-TKIs. Similarly, there is growing evidence of acquired resistance mechanisms to anaplastic lymphoma kinase (ALK)-TKI treatment. A better understanding of these acquired resistance mechanisms is essential in clinical practice as patients could be treated with specific drugs that are active against the induced alterations. The use of free circulating tumor nucleic acids or circulating tumor cells (CTCs) enables resistance mechanisms to be characterized in a non-invasive manner and reduces the need for tumor re-biopsy. This review discusses the main resistance mechanisms to TKIs and provides a comprehensive overview of innovative strategies to evaluate known resistance mechanisms in free circulating nucleic acids or CTCs and potential future orientations for these non-invasive approaches.