Targeting AKT with the allosteric AKT inhibitor MK-2206 in non-small cell lung cancer cells with acquired resistance to cetuximab

Celecoxib and sulindac sulfide elicit anticancer effects on PIK3CA-mutated head and neck cancer cells through endoplasmic reticulum stress, reactive oxygen species, and mitochondrial dysfunction

Gain-of-function mutation in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) catalytic subunit alpha gene (PIK3CA) is a significant factor in head and neck cancer (HNC). Patients with HNC harboring PIK3CA mutations receive therapeutic benefits from the use of non-steroidal anti-inflammatory drugs (NSAIDs). However, the molecular mechanisms underlying these effects remain unknown. Here, we examined the Detroit562 and FaDu cell lines as HNC models with and without a hyperactive PIK3CA mutation (H1047R), respectively, regarding their possible distinct responses to the NSAIDs celecoxib and sulindac sulfide (SUS). Detroit562 cells exhibited relatively high PI3K/Akt pathway-dependent cyclooxygenase-2 (COX-2) expression, associated with cell proliferation. Celecoxib treatment restricted cell proliferation and upregulated endoplasmic reticulum (ER) stress-related markers, including GRP78, C/EBP-homologous protein, activating transcription factor 4, death receptor 5, and reactive oxygen species (ROS). These effects were much stronger in Detroit562 cells than in FaDu cells and were largely COX-2-independent. SUS treatment yielded similar results. Salubrinal (an ER stress inhibitor) and N-acetyl-L-cysteine (a ROS scavenger) prevented NSAID-induced ROS generation and ER stress, respectively, indicating crosstalk between ER and oxidative stress. In addition, celecoxib and/or SUS elevated cleaved caspase-3 levels, Bcl-2-associated X protein/Bcl-2-interacting mediator of cell death expression, and mitochondrial damage, which was more pronounced in Detroit562 than in FaDu cells. Salubrinal and N-acetyl-L-cysteine attenuated celecoxib-induced mitochondrial dysfunction. Collectively, our results suggest that celecoxib and SUS efficiently suppress activating PIK3CA mutation-harboring HNC progression by inducing ER and oxidative stress and mitochondrial dysfunction, leading to apoptotic cell death, further supporting NSAID treatment as a useful strategy for oncogenic PIK3CA-mutated HNC therapy.

Identifying the Multitarget Pharmacological Mechanism of Action of Genistein on Lung Cancer by Integrating Network Pharmacology and Molecular Dynamic Simulation

Food supplements have become beneficial as adjuvant therapies for many chronic disorders, including cancer. Genistein, a natural isoflavone enriched in soybeans, has gained potential interest as an anticancer agent for various cancers, primarily by modulating apoptosis, the cell cycle, and angiogenesis and inhibiting metastasis. However, in lung cancer, the exact impact and mechanism of action of genistein still require clarification. To provide more insight into the mechanism of action of genistein, network pharmacology was employed to identify the key targets and their roles in lung cancer pathogenesis. Based on the degree score, the hub genes AKT1, CASP3, EGFR, STAT3, ESR1, SRC, PTGS2, MMP9, PRAG, and AR were significantly correlated with genistein treatment. AKT1, EGFR, and STAT3 were enriched in the non-small cell lung cancer (NSCLC) pathway according to Kyoto Encyclopedia of Genes and Genomes analysis, indicating a significant connection to lung cancer development. Moreover, the binding affinity of genistein to NSCLC target proteins was further verified by molecular docking and molecular dynamics simulations. Genistein exhibited potential binding to AKT1, which is involved in apoptosis, cell migration, and metastasis, thus holding promise for modulating AKT1 function. Therefore, this study aimed to investigate the mechanism of action of genistein and its therapeutic potential for the treatment of NSCLC.

mTORC2-AKT signaling to PFKFB2 activates glycolysis that enhances stemness and tumorigenicity of intestinal epithelial cells

Although elevated glycolysis has been widely recognized as a hallmark for highly proliferating cells like stem cells and cancer, its regulatory mechanisms are still being updated. Here, we found a previously unappreciated mechanism of mammalian target of rapamycin complex 2 (mTORC2) in regulating glycolysis in intestinal stem cell maintenance and cancer progression. mTORC2 key subunits expression levels and its kinase activity were specifically upregulated in intestinal stem cells, mouse intestinal tumors, and human colorectal cancer (CRC) tissues. Genetic ablation of its key scaffolding protein Rictor in both mouse models and cell lines revealed that mTORC2 played an important role in promoting intestinal stem cell proliferation and self-renewal. Moreover, utilizing mouse models and organoid culture, mTORC2 loss of function was shown to impair growth of gut adenoma and tumor organoids. Based on these findings, we performed RNA-seq and noticed significant metabolic reprogramming in Rictor conditional knockout mice. Among all the pathways, carbohydrate metabolism was most profoundly altered, and further studies demonstrated that mTORC2 promoted glycolysis in intestinal epithelial cells. Most importantly, we showed that a rate-limiting enzyme in regulating glycolysis, 6-phosphofructo-2-kinase (PFKFB2), was a direct target for the mTORC2-AKT signaling. PFKFB2 was phosphorylated upon mTORC2 activation, but not mTORC1, and this process was AKT-dependent. Together, this study has identified a novel mechanism underlying mTORC2 activated glycolysis, offering potential therapeutic targets for treating CRC.

Akt Inhibition Promotes Autophagy and Clearance of Group B Streptococcus from the Alveolar Epithelium

Group B Streptococcus (GBS) is a gram-positive bacterium that is harmless for healthy individuals but may provoke invasive disease in young infants and immunocompromised hosts. GBS invades the epithelial barriers to enter the bloodstream, and thus strategies that enhance epithelial cell responses may hamper GBS invasion. In the present study, we sought to investigate whether the inhibition of Akt, a kinase that regulates host inflammatory responses and autophagy via suppression of mTOR, can enhance the response of non-phagocytic alveolar epithelial cells against GBS. Treatment of the alveolar epithelial cell line A549 with the Akt inhibitor MK-2206 resulted in the enhanced production of reactive oxygen species and inflammatory mediators in response to GBS. Additionally, Akt inhibition via MK-2206 resulted in elevated LC3II/I ratios and increased autophagic flux in alveolar epithelial cells. Importantly, the inhibition of Akt promoted GBS clearance both in alveolar epithelial cells in vitro and in lung tissue in vivo in a murine model of GBS pneumonia. The induction of autophagy was essential for GBS clearance in MK-2206 treated cells, as knockdown of ATG5, a critical component of autophagy, abrogated the effect of Akt inhibition on GBS clearance. Our findings highlight the role of Akt kinase inhibition in promoting autophagy and GBS clearance in the alveolar epithelium. The inhibition of Akt may serve as a promising measure to strengthen epithelial barriers and prevent GBS invasion in susceptible hosts.

The CX3CL1 intracellular domain exhibits neuroprotection via insulin receptor/ insulin like growth factor receptor signaling

CX3CL1, also known as fractalkine, is best known for its signaling activity through interactions with its cognate receptor CX3CR1. However, its intrinsic function that is independent of interaction with CX3CR1 remains to be fully understood. We demonstrate that the intracellular domain of CX3CL1 (CX3CL1-ICD), generated upon sequential cleavages by α-/β-secretase and γ-secretase, initiates a back signaling activity, which mediates direct signal transmission to gene expression in the nucleus. To study this, we fused a synthetic peptide derived from CX3CL1-ICD, named Tet34, with a 13-amino acid tetanus sequence at the N-terminus to facilitate translocation into neuronal cells. We show that treatment of mouse neuroblastoma Neuro-2A cells with Tet34, but not its scrambled control (Tet34s), induced cell proliferation, as manifested by changes in protein levels of transcription factors and pro-growth molecules Foxo-1, -3, cyclin D1, PCNA, Sox5, and cdk2. Further biochemical assays reveal elevation of phosphorylated insulin receptor β subunit, insulin-like growth factor-1 (IGF-1) receptor β subunit and insulin receptor substrates as well as activation of proliferation-linked kinase AKT. In addition, transgenic mice overexpressing membrane-anchored C-terminal CX3CL1 (CX3CL1- ct) also exhibited activation of insulin/IGF-1 receptor signaling. Remarkably, we found this Tet34 peptide, but not Tet34s, protected against endoplasmic reticulum stress and cellular apoptosis when Neuro-2A cells were challenged with toxic oligomers of β-amyloid peptide or hydrogen peroxide. Taken together, our results suggest CX3CL1-ICD may have translational potential for neuroprotection in Alzheimer's disease and for disorders resulting from insulin resistance.

PEBP4 Directs the Malignant Behavior of Hepatocellular Carcinoma Cells via Regulating mTORC1 and mTORC2

Phosphatidylethanolamine binding protein 4 (PEBP4) is an understudied multifunctional small protein. Previous studies have shown that the expression of PEBP4 is increased in many cancer specimens, which correlates to cancer progression. The present study explored the mechanism by which PEBP4 regulates the growth and progression of hepatocellular carcinoma cells. Thus, we showed that knockdown of PEBP4 in MHCC97H cells, where its expression was relatively high, diminished activities of serine/threonine protein kinase B (PKB, also known as Akt), mammalian target of rapamycin complex 1(mTORC1), and mTORC2, events that were not restored by insulin-like growth factor 1 (IGF-1). Conversely, overexpression of PEBP4 in MHCC97L cells with the low endogenous level yielded opposite effects. Furthermore, physical association of PEBP4 with Akt, mTORC1, and mTORC2 was observed. Interestingly, introduction of AktS473D mutant, bypassing phosphorylation by mTORC2, rescued mTORC1 activity, but without effects on mTORC2 signaling. In contrast, the effect of PEBP4 overexpression on the activity of mTORC1 but not that of mTORC2 was suppressed by MK2206, a specific inhibitor of Akt. In conjunction, PEBP4 knockdown-engendered reduction of cell proliferation, migration and invasion was partially rescued by Akt S473D while increases in these parameters induced by overexpression of PEBP4 were completely abolished by MK2206, although the expression of epithelial mesenchymal transition (EMT) markers appeared to be fully regulated by the active mutant of Akt. Finally, knockdown of PEBP4 diminished the growth of tumor and metastasis, whereas they were enhanced by overexpression of PEBP4. Altogether, our study suggests that increased expression of PEBP4 exacerbates malignant behaviors of hepatocellular cancer cells through cooperative participation of mTORC1 and mTORC2.

A Phase I Study of Dinaciclib in Combination With MK-2206 in Patients With Advanced Pancreatic Cancer

The combination of drugs targeting Ral and PI3K/AKT signaling has antitumor efficacy in preclinical models of pancreatic cancer. We combined dinaciclib (small molecule cyclin dependent kinase inhibitor with MK-2206 (Akt inhibitor) in patients with previously treated/metastatic pancreatic cancer. Patients were treated with dinaciclib (6-12 mg/m² i.v.) and MK-2206 (60-135 mg p.o.) weekly. Tumor biopsies were performed to measure pAKT, pERK, and Ki67 at baseline and after one completed cycle (dose level 2 and beyond). Thirty-nine patients participated in the study. The maximum tolerated doses were dinaciclib 9 mg/m² and MK-2206 135 mg. Treatment-related grade 3 and 4 toxicities included neutropenia, lymphopenia, anemia, hyperglycemia, hyponatremia, and leukopenia. No objectives responses were observed. Four patients (10%) had stable disease as their best response. At the recommended dose, median survival was 2.2 months. Survival rates at 6 and 12 months were 11% and 5%, respectively. There was a nonsignificant reduction in pAKT composite scores between pretreatment and post-treatment biopsies (mean 0.76 vs. 0.63; P = 0.635). The combination of dinaciclib and MK-2206 was a safe regimen in patients with metastatic pancreatic cancer, although without clinical benefit, possibly due to not attaining biologically effective doses. Given the strong preclinical evidence of Ral and AKT inhibition, further studies with better tolerated agents should be considered.

The Relevance of Transcription Factors in Gastric and Colorectal Cancer Stem Cells Identification and Eradication

Gastric and colorectal cancers have a high incidence and mortality worldwide. The presence of cancer stem cells (CSCs) within the tumor mass has been indicated as the main reason for tumor relapse, metastasis and therapy resistance, leading to poor overall survival. Thus, the elimination of CSCs became a crucial goal for cancer treatment. The identification of these cells has been performed by using cell-surface markers, a reliable approach, however it lacks specificity and usually differs among tumor type and in some cases even within the same type. In theory, the ideal CSC markers are those that are required to maintain their stemness features. The knowledge that CSCs exhibit characteristics comparable to normal stem cells that could be associated with the expression of similar transcription factors (TFs) including SOX2, OCT4, NANOG, KLF4 and c-Myc, and signaling pathways such as the Wnt/β-catenin, Hedgehog (Hh), Notch and PI3K/AKT/mTOR directed the attention to the use of these similarities to identify and target CSCs in different tumor types. Several studies have demonstrated that the abnormal expression of some TFs and the dysregulation of signaling pathways are associated with tumorigenesis and CSC phenotype. The disclosure of common and appropriate biomarkers for CSCs will provide an incredible tool for cancer prognosis and treatment. Therefore, this review aims to gather the new insights in gastric and colorectal CSC identification specially by using TFs as biomarkers and divulge promising drugs that have been found and tested for targeting these cells.

Targeting AKT/PKB to improve treatment outcomes for solid tumors

The serine/threonine kinase AKT, also known as protein kinase B (PKB), is the major substrate to phosphoinositide 3-kinase (PI3K) and consists of three paralogs: AKT1 (PKBα), AKT2 (PKBβ) and AKT3 (PKBγ). The PI3K/AKT pathway is normally activated by binding of ligands to membrane-bound receptor tyrosine kinases (RTKs) as well as downstream to G-protein coupled receptors and integrin-linked kinase. Through multiple downstream substrates, activated AKT controls a wide variety of cellular functions including cell proliferation, survival, metabolism, and angiogenesis in both normal and malignant cells. In human cancers, the PI3K/AKT pathway is most frequently hyperactivated due to mutations and/or overexpression of upstream components. Aberrant expression of RTKs, gain of function mutations in PIK3CA, RAS, PDPK1, and AKT itself, as well as loss of function mutation in AKT phosphatases are genetic lesions that confer hyperactivation of AKT. Activated AKT stimulates DNA repair, e.g. double strand break repair after radiotherapy. Likewise, AKT attenuates chemotherapy-induced apoptosis. These observations suggest that a crucial link exists between AKT and DNA damage. Thus, AKT could be a major predictive marker of conventional cancer therapy, molecularly targeted therapy, and immunotherapy for solid tumors. In this review, we summarize the current understanding by which activated AKT mediates resistance to cancer treatment modalities, i.e. radiotherapy, chemotherapy, and RTK targeted therapy. Next, the effect of AKT on response of tumor cells to RTK targeted strategies will be discussed. Finally, we will provide a brief summary on the clinical trials of AKT inhibitors in combination with radiochemotherapy, RTK targeted therapy, and immunotherapy.

FOXO3 Transcription Factor Regulates IL-10 Expression in Mycobacteria-Infected Macrophages, Tuning Their Polarization and the Subsequent Adaptive Immune Response

Alveolar Macrophages play a key role in the development of a robust adaptive immune response against the agent of Tuberculosis (TB), Mycobacterium tuberculosis (M.tb). However, macrophage response is often hampered by the production of IL-10, a potent suppressor of the host immune response. The secretion of IL-10 correlates with TB pathogenesis and persistence in host tissues. Concordantly, inhibition of IL-10 signaling, during BCG vaccination, confers higher protection against M.tb through a sustained Th1 and Th17 responses. Therefore, uncovering host effectors, underlying mycobacteria-induced expression of IL-10, may be beneficial toward the development of IL-10-blocking tools to be used either as adjuvants in preventive vaccination or as adjunct during standard treatment of TB. Here, we investigated the role of FOXO3 transcription factor in mycobacteria-induced secretion of IL-10. We observed that PI3K/Akt/FOXO3 axis regulates IL-10 expression in human macrophages. Knocking down of FOXO3 expression resulted in an increase of IL-10 production in BCG-infected macrophages. The gene reporter assay further confirmed the transcriptional regulation of IL-10 by FOXO3. In silico analysis identified four Forkhead binding motifs on the human IL-10 promoter, from which the typical FOXO3 one at position -203 was the major target as assessed by mutagenesis and CHIP binding assays. Further, we also observed a decrease in gene expression levels of the M1 typical markers (i.e., CD80 and CD86) in SiFOXO3-transfected macrophages while activation of FOXO3 led to the increase in the expression of CD86, MHCI, and MHCII. Finally, co-culture of human lymphocytes with siFOXO3-transfected macrophages, loaded with mycobacterial antigens, showed decreased expression of Th1/Th17 specific markers and a simultaneous increase in expression of IL-4 and IL-10. Taken together, we report for the first time that FOXO3 modulates IL-10 secretion in mycobacteria-infected macrophage, driving their polarization and the subsequent adaptive immune response. This work proposes FOXO3 as a potential target for the development of host-directed strategies for better treatment or prevention of TB.

A-674563, a putative AKT1 inhibitor that also suppresses CDK2 activity, inhibits human NSCLC cell growth more effectively than the pan-AKT inhibitor, MK-2206

AKT is a serine-threonine kinase implicated in tumorigenesis as a central regulator of cellular growth, proliferation, survival, and metabolism. Activated AKT is commonly overexpressed in non-small cell lung cancer (NSCLC) and accordingly AKT inhibitors are under clinical investigation for NSCLC treatment. Thus far, the AKT inhibitors being evaluated broadly target all three (1–3) AKT isoforms but recent evidence suggests opposing roles in lung tumorigenesis where loss of Akt1 inhibits while the loss of Akt2 enhances lung tumor development. Based on these findings, we hypothesized that selective inhibition of AKT-1 would be a more effective therapeutic strategy than pan-AKT inhibition for NSCLC treatment. Using six NSCLC cell lines, we found that the AKT-1 inhibitor, A-674563, was significantly more effective at reducing NSCLC cell survival relative to the pan-AKT inhibitor MK-2206. Comparison of the downstream effects of the inhibitors suggests that altered cell cycle progression and off-target CDK2 inhibition are likely vital to the improved efficacy of A-674563 over MK-2206.

Targeting RAS-driven human cancer cells with antibodies to upregulated and essential cell-surface proteins

While there have been tremendous efforts to target oncogenic RAS signaling from inside the cell, little effort has focused on the cell-surface. Here, we used quantitative surface proteomics to reveal a signature of proteins that are upregulated on cells transformed with KRAS^G12V, and driven by MAPK pathway signaling. We next generated a toolkit of recombinant antibodies to seven of these RAS-induced proteins. We found that five of these proteins are broadly distributed on cancer cell lines harboring RAS mutations. In parallel, a cell-surface CRISPRi screen identified integrin and Wnt signaling proteins as critical to RAS-transformed cells. We show that antibodies targeting CDCP1, a protein common to our proteomics and CRISPRi datasets, can be leveraged to deliver cytotoxic and immunotherapeutic payloads to RAS-transformed cancer cells and report for RAS signaling status in vivo. Taken together, this work presents a technological platform for attacking RAS from outside the cell.

Overcoming Resistance to Cetuximab with Honokiol, A Small-Molecule Polyphenol

Overexpression and activation of the EGFR have been linked to poor prognosis in several human cancers. Cetuximab is a mAb against EGFR that is used for the treatment in head and neck squamous cell carcinoma (HNSCC) and metastatic colorectal cancer. Unfortunately, most tumors have intrinsic or will acquire resistance to cetuximab during the course of therapy. Honokiol is a natural compound found in the bark and leaves of the Chinese Magnolia tree and is established to have several anticancer properties without appreciable toxicity. In this study, we hypothesized that combining cetuximab and honokiol treatments could overcome acquired resistance to cetuximab. We previously developed a model of acquired resistance to cetuximab in non-small cell lung cancer H226 cell line. Treatment of cetuximab-resistant clones with honokiol and cetuximab resulted in a robust antiproliferative response. Immunoblot analysis revealed the HER family and their signaling pathways were downregulated after combination treatment, most notably the proliferation (MAPK) and survival (AKT) pathways. In addition, we found a decrease in phosphorylation of DRP1 and reactive oxygen species after combination treatment in cetuximab-resistant clones, which may signify a change in mitochondrial function. Furthermore, we utilized cetuximab-resistant HNSCC patient-derived xenografts (PDX) to test the benefit of combinatorial treatment in vivo There was significant growth delay in PDX tumors after combination treatment with a subsequent downregulation of active MAPK, AKT, and DRP1 signaling as seen in vitro Collectively, these data suggest that honokiol is a promising natural compound in overcoming acquired resistance to cetuximab. Mol Cancer Ther; 17(1); 204-14. ©2017 AACR.

PPAR-γ and Akt regulate GLUT1 and GLUT3 surface localization during Mycobacterium tuberculosis infection

The success of Mycobacterium tuberculosis (Mtb) as a pathogen stems from its ability to manipulate the host macrophage towards increased lipid biogenesis and lipolysis inhibition. Inhibition of lipolysis requires augmented uptake of glucose into the host cell causing an upregulation of the glucose transporters GLUT1 and GLUT3 on the cell surface. Mechanism behind this upregulation of the GLUT proteins during Mtb infection is hitherto unknown and demands intensive investigation in order to understand the pathways linked with governing them. Our endeavor to investigate some of the key proteins that have been found to be affected during Mtb infection led us to investigate host molecular pathways such as Akt and PPAR-γ that remain closely associated with the survival of the bacilli by modulating the localization of glucose transporters GLUT1 and GLUT3.

Litchi seed extract inhibits epidermal growth factor receptor signaling and growth of Two Non-small cell lung carcinoma cells

BACKGROUND

Litchi seeds possess rich amounts of phenolics and have been shown to inhibit proliferation of several types of cancer cells. However, the suppression of EGFR signaling in non-small cell lung cancer (NSCLC) by litchi seed extract (LCSE) has not been fully understood.

METHODS

In this study, the effects of LCSE on EGFR signaling, cell proliferation, the cell cycle and apoptosis in A549 adenocarcinoma cells and NCI- H661 large-cell carcinoma cells were examined.

RESULTS

The results demonstrated that LCSE potently reduced the number of cancer cells and induced growth inhibition, cell-cycle arrest in the G1 or G2/M phase, and apoptotic death in the cellular experiment. Only low cytotoxicity effect was noted in normal lung MRC-5 cells. LCSE also suppressed cyclins and Bcl-2 and elevated Kip1/p27, Bax and caspase 8, 9 and 3 activities, which are closely associated with the downregulation of EGFR and its downstream Akt and Erk-1/-2 signaling.

CONCLUSION

The results implied that LCSE suppressed EGFR signaling and inhibited NSCLC cell growth. This study provided in vitro evidence that LCSE could serve as a potential agent for the adjuvant treatment of NSCLC.

The CRISPR/Cas9 system targeting EGFR exon 17 abrogates NF-κB activation via epigenetic modulation of UBXN1 in EGFRwt/vIII glioma cells

Worldwide, glioblastoma (GBM) is the most lethal and frequent intracranial tumor. Despite decades of study, the overall survival of GBM patients remains unchanged. epidermal growth factor receptor (EGFR) amplification and gene mutation are thought to be negatively correlated with prognosis. In this study, we used proteomics to determine that UBXN1 is a negative downstream regulator of the EGFR mutation vIII (EGFRvIII). Via bioinformatics analysis, we found that UBXN1 is a factor that can improve glioma patients' overall survival time. We also determined that the down-regulation of UBXN1 is mediated by the upregulation of H3K27me3 in the presence of EGFRvIII. Because NF-κB can be negatively regulated by UBXN1, we believe that EGFRwt/vIII activates NF-κB by suppressing UBXN1 expression. Importantly, we used the latest genomic editing tool, CRISPR/Cas9, to knockout EGFRwt/vIII on exon 17 and further proved that UBXN1 is negatively regulated by EGFRwt/vIII. Furthermore, knockout of EGFR/EGFRvIII could benefit GBM in vitro and in vivo, indicating that CRISPR/Cas9 is a promising therapeutic strategy for both EGFR amplification and EGFR mutation-bearing patients.

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.

5-lipoxygenase mediates docosahexaenoyl ethanolamide and N-arachidonoyl-L-alanine-induced reactive oxygen species production and inhibition of proliferation of head and neck squamous cell carcinoma cells

Background

Endocannabinoids have recently drawn attention as promising anti-cancer agents. We previously observed that anandamide (AEA), one of the representative endocannabinoids, effectively inhibited the proliferation of head and neck squamous cell carcinoma (HNSCC) cell lines in a receptor-independent manner. In this study, using HNSCC cell lines, we examined the anti-cancer effects and the mechanisms of action of docosahexaenoyl ethanolamide (DHEA) and N-arachidonoyl-L-alanine (NALA), which are polyunsaturated fatty acid (PUFA)-based ethanolamides like AEA.

Methods and Results

DHEA and NALA were found to effectively inhibit HNSCC cell proliferation. These anti-proliferative effects seemed to be mediated in a cannabinoid receptor-independent manner, since the antagonist of cannabinoid receptor-1 (CB1) and vanilloid receptor-1 (VR1), two endocannabinoid receptors, did not reverse the ability of DHEA and NALA to induce cell death. Instead, we observed an increase in reactive oxygen species (ROS) production and a decrease of phosphorylated Akt as a result of DHEA and NALA treatment. Antioxidants efficiently reversed the inhibition of cell proliferation and the decrease of phosphorylated Akt induced by DHEA and NALA; inhibition of 5-lipoxygenase (5-LO), which is expected to be involved in DHEA- and NALA-degradation pathway, also partially blocked the ability of DHEA and NALA to inhibit cell proliferation and phosphorylated Akt. Interestingly, ROS production as a result of DHEA and NALA treatment was decreased by inhibition of 5-LO.

Conclusions

From these findings, we suggest that ROS production induced by the 5-LO pathway mediates the anti-cancer effects of DHEA and NALA on HNSCC cells. Finally, our findings suggest the possibility of a new cancer-specific therapeutic strategy, which utilizes 5-LO activity rather than inhibiting it.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2499-3) contains supplementary material, which is available to authorized users.

Squamous Cell Cancers: A Unified Perspective on Biology and Genetics

Squamous cell carcinomas (SCCs) represent the most frequent human solid tumors and are a major cause of cancer mortality. These highly heterogeneous tumors arise from closely interconnected epithelial cell populations with intrinsic self-renewal potential inversely related to the stratified differentiation program. SCCs can also originate from simple or pseudo-stratified epithelia through activation of quiescent cells and/or a switch in cell-fate determination. Here, we focus on specific determinants implicated in the development of SCCs by recent large-scale genomic, genetic, and epigenetic studies, and complementary functional analysis. The evidence indicates that SCCs from various body sites, while clinically treated as separate entities, have common determinants, pointing to a unified perspective of the disease and potential new avenues for prevention and treatment.

Critical involvement of the α(1,2)-fucosyltransferase in multidrug resistance of human chronic myeloid leukemia

The fucosyltransferases are key enzymes in cell surface antigen synthesis during multidrug resistance (MDR) development. The aim of the present study was to analyze the alteration of α(1,2)-fucosyltransferase involved in MDR development in human chronic myeloid leukemia (CML). FUT1 was overexpressed in three CML/MDR cell lines and peripheral blood mononuclear cells (PBMC) of CML patients. However, no significant changes of FUT2 were observed. The altered levels of FUT1 had a significant impact on the phenotypic variation of MDR of K562 and K562/ADR cells, the activity of EGFR/MAPK pathway and P-glycoprotein (P-gp) expression. Blocking the EGFR/MAPK pathway by its specific inhibitor PD153035 or EGFR small interfering RNA (siRNA) resulted in the reduced MDR of K562/ADR cells. This study indicated that α(1,2)-fucosyltransferase involved in the development of MDR of CML cells probably through FUT1 regulated the activity of EGFR/MAPK signaling pathway and the expression of P-gp.

Selective AKT Inhibition by MK-2206 Represses Colorectal Cancer-Initiating Stem Cells

Background

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. Growing evidence indicates that tumor-initiating cells (TICs) are responsible for tumor growth and progression. Conventional chemotherapeutics do not sufficiently eliminate TICs, leading to tumor relapse. We aimed to gain insight into TIC biology by comparing the transcriptome of primary TIC cultures and their normal stem cell counterparts to uncover expression differences.

Methods

We established colonosphere cultures derived from the resection of paired specimens of primary tumor and normal mucosa in patients with CRC. These colonospheres, enriched for TICs, were used for differential transcriptome analyses to detect new targets for a TIC-directed therapy. Effects of target inhibition on CRC cells were studied in vitro and in vivo.

Results

Pathway analysis of the regulated genes showed enrichment of genes central to PI3K/AKT and Wnt-signaling. We identified CD133 as a marker for a more aggressive CRC subpopulation enriched with TICs in SW480 CRC cells in an in vivo cancer model. Treatment of CRC cells with the selective AKT inhibitor MK-2206 caused a decrease in cell proliferation, particularly in the TIC fraction, resulting in a significant reduction of the stemness capacity to form colonospheres in vitro and to initiate tumor formation in vivo. Consequently, MK-2206 treatment of mice with established xenograft tumors exhibited a significant deceleration of tumor progression. Primary patient-derived tumorsphere growth was significantly inhibited by MK-2206.

Conclusion

This study reveals that AKT signaling is critical for TIC proliferation and can be efficiently targeted by MK-2206 representing a preclinical therapeutic strategy to repress colorectal TICs.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-016-5218-z) contains supplementary material, which is available to authorized users.

Phase II Study of the AKT Inhibitor MK-2206 plus Erlotinib in Patients with Advanced Non-Small Cell Lung Cancer Who Previously Progressed on Erlotinib

PURPOSE

Preclinical modeling in non-small cell lung cancer (NSCLC) showed that stimulation with hepatocyte growth factor (HGF), the ligand for MET, could reverse the cytostatic and cytotoxic effects of the EGFR inhibitor erlotinib in erlotinib-sensitive cell lines. Inhibitors of AKT signaling mitigated this HGF-mediated resistance, partially restoring erlotinib activity. We conducted a phase II trial of erlotinib plus MK-2206, a highly selective inhibitor of AKT, in NSCLC patients.

EXPERIMENTAL DESIGN

Eligible patients must have progressed following prior benefit from erlotinib, defined as response or stable disease > 12 weeks. Treatment consisted of erlotinib 150 mg orally every day + MK-2206 45 mg orally every alternate day on a 28-day cycle. Primary endpoints were RECIST response rate > 30% (stratum 1: EGFR mutant) and disease control rate (DCR) > 20% at 12 weeks (stratum 2: EGFR wild-type).

RESULTS

Eighty patients were enrolled, 45 and 35 in stratum 1 and 2, respectively. Most common attributable adverse events (all grade 3) were rash, diarrhea, fatigue, and mucositis. Response and DCR were, respectively, 9% and 40% in stratum 1; 3% and 47% in stratum 2. Median progression-free survival was 4.4 months in stratum 1 and 4.6 months in stratum 2.

CONCLUSIONS

Combination MK-2206 and erlotinib met its primary endpoint in erlotinib-pretreated patients with EGFR wild-type NSCLC. Although activity was seen in EGFR-mutated NSCLC, this did not exceed a priori estimates. AKT pathway inhibition merits further clinical evaluation in EGFR wild-type NSCLC.

Combining three antibodies nullifies feedback-mediated resistance to erlotinib in lung cancer

Despite initial responses to targeted kinase inhibitors, lung cancer patients presenting with primary epidermal growth factor receptor (EGFR) mutations acquire resistance, often due to a second-site mutation (T790M). However, clinical trials found no survival benefits in patients treated with a monoclonal antibody (mAb) to EGFR that should block activation of the mutated receptor and thus bypass resistance to molecules that target the catalytic or ATP-binding site. Using cell lines with the T790M mutation, we discovered that prolonged exposure to mAbs against only the EGFR triggered network rewiring by (i) stimulating the extracellular signal-regulated kinase (ERK) pathway; (ii) inducing the transcription of HER2 (human epidermal growth factor receptor 2) and HER3, which encode other members of the EGFR family, and the gene encoding HGF, which is the ligand for the receptor tyrosine kinase MET; and (iii) stimulating the interaction between MET and HER3, which promoted MET activity. Supplementing the EGFR-specific mAb with those targeting HER2 and HER3 suppressed these compensatory feedback loops in cultured lung cancer cells. The triple mAb combination targeting all three receptors prevented the activation of ERK, accelerated the degradation of the receptors, inhibited the proliferation of tumor cells but not of normal cells, and markedly reduced the growth of tumors in mice xenografted with cells that were resistant to combined treatment with erlotinib and the single function-blocking EGFR mAb. These findings uncovered feedback loops that enable resistance to treatment paradigms that use a single antibody and indicate a new strategy for the treatment of lung cancer patients.

Diverse involvement of isoforms and gene aberrations of Akt in human lung carcinomas

Emerging evidence confirms a central role of Akt in cancer. To evaluate the relative contribution of deregulated Akt and their clinicopathological significance in lung carcinomas, overexpression, activation of Akt and AKT gene increases were investigated. Immunohistochemical staining for 108 cases revealed overexpression of total Akt, Akt1, Akt2 and Akt3 in 61.1, 47.2, 40.7 and 23.1%, respectively, and phosphorylated Akt in 42.6% of cases. Expression of total Akt, Akt2 and Akt3 were frequently observed in small cell carcinoma, but phosphorylated Akt and Akt1 were more frequently observed in squamous cell carcinoma. FISH analysis to evaluate gene increases of AKT1-3 revealed amplification of AKT1 in 4.2% and AKT1 increase by polysomy of chromosome 14 in 27.3% of cases. For AKT2, amplification was observed in 3.2% and polysomy of chromosome 19 in 26.3% of cases. AKT3 increase was observed in 40.0% of cases only by polysomy of chromosome 1. Although “FISH-positive” AKT1 and AKT2 gene increases (amplification/high-level polysomy) were found exclusively in the cases overexpressing total Akt, Akt1 or Akt2, respectively, AKT3 increase was irrelevant of Akt3 expression. Statistically, expressions of Akt2, p-Akt and cytoplasmic-p-Akt were correlated with lymph node metastasis (P = 0.0479, P = 0.0371 and P = 0.0310, respectively). Although AKT1 and AKT2 gene increase showed positive correlation with, or trend towards a positive correlation with tumor size (P = 0.0430, P = 0.0590, respectively), AKT3 did not. In conclusion, Akt isoforms are differentially involved in the pathological phenotype of lung carcinoma in a diverse manner. Because abnormality of Akt1/AKT1 and Akt2/AKT2 correlated with clinicopathological profiles, Akt1/2-specific targeting may open a novel therapeutic window for the group showing Akt deregulation.

New development of inhibitors targeting the PI3K/AKT/mTOR pathway in personalized treatment of non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related death worldwide. Non-small-cell lung cancer (NSCLC) is the most common pathological type of lung cancer, divided into squamous cell carcinoma and adenocarcinoma. Despite better techniques of surgery and improvement in adjuvant and neoadjuvant therapy, the median survival of advanced NSCLC is only 8-10 months. With increased understanding of molecular alternations in NSCLC, considerable efforts have focused on the development of personalized molecular-targeted therapies. The PI3K/AKT/mTOR pathway regulates tumor development, growth, and proliferation of NSCLC. Various novel inhibitors targeting this pathway have been identified in preclinical studies or clinical trials. Some genetic alternations may be considered sensitive or resistant biomarkers to these inhibitors. Sometimes, upregulation of RTK and the downstream PI3K pathway or upregulation of the ERK pathway by compensatory feedback reactivation in response to these inhibitors also lead to drug resistance. Therefore, combination therapy of these inhibitors and other targeted inhibitors such as EGFR-TKI or MEK inhibitors according to genetic status and categories of inhibitors is required to enhance the efficacy of these inhibitors. Here, we reviewed the genetic status of the PI3K/AKT/mTOR pathway in NSCLC and the novel inhibitors targeting this pathway in preclinical or clinical studies, exploring the possible genetic alternations related to different inhibitors and the means to enhance the antitumor effect in NSCLC.

RNA interference targeting enhancer of polycomb1 exerts anti-tumor effects in lung cancer

BACKGROUND AND AIM

Lung cancer is one of leading malignant tumor worldwide with a high mortality rate. A new therapy target, enhancer of polycomb1 (EPC1) knocked down by short hairpin RNA (shRNA) interference technology, for lung cancer was established to investigate its effects on lung cancer in present study.

METHODS

RNA interference technology was applied to down-regulate the expression of EPC1 by specific-shRNA with lentivirus vector in neoplastic human alveolar basal epithelial cells (A549 cells). The survival rate and apoptosis were respectively measured by MTT and Flow Cytometry to evaluate the effects of shRNA EPC1 on cells. Mice xenografts of HCT116 cells with shRNA EPC1 were also established to assess the effect on tumor growth. The levels of AKT and p65 were detected by western blotting.

RESULTS

The down-regulation of EPC1 by specific-shRNA with lentivirus vector was significantly decreased the survival rate and apoptosis of A549 cells, and the tumors in EPC1 shRNA transfection group had a significant lower size and weight compared with the ones with control shRNA. The protein expression of p-AKT and p65 was reduced by EPC1 shRNA in both in vitro and in vivo experiments.

CONCLUSION

Silencing EPC1 by shRNA technology had the inhibition effects on cell proliferation and tumor growth in lung cancer, which provided a new potential target for treatment of cancers.

Effects of AKT inhibition on HGF-mediated erlotinib resistance in non-small cell lung cancer cell lines

PURPOSE

Acquired resistance to erlotinib in patients with EGFR-mutant non-small cell lung cancer can result from aberrant activation of alternative receptor tyrosine kinases, such as the HGF-driven c-MET receptor. We sought to determine whether inhibition of AKT signaling could augment erlotinib activity and abrogate HGF-mediated resistance.

METHODS

The effects of MK-2206, a selective AKT inhibitor, were evaluated in combination with erlotinib on a large panel of 13 lung cancer cell lines containing different EGFR or KRAS abnormalities. The activity of the combination was assessed using proliferation assays, flow cytometry and immunoblotting. The MEK inhibitor PD0325901 was used to determine the role of the MAP kinase pathway in erlotinib resistance.

RESULTS

The combination of MK-2206 and erlotinib resulted in synergistic growth inhibition independent of EGFR mutation status. In cell lines where HGF blocked the anti-proliferative and cytotoxic effects of erlotinib, MK-2206 could restore cell cycle arrest, but MEK inhibition was required for erlotinib-dependent apoptosis. Both AKT and MEK inhibition contributed to cell death independent of erlotinib in the T790M-containing H1975 and the EGFR-WT cell lines tested.

CONCLUSIONS

These findings illustrate the potential advantages and challenges of combined signal transduction inhibition as a generalized strategy to circumvent acquired erlotinib resistance.

Downregulation of ribosomal protein S6 inhibits the growth of non-small cell lung cancer by inducing cell cycle arrest, rather than apoptosis

Ribosomal protein S6 (rpS6), a component of the small 40S ribosomal subunit, has been found to be associated with multiple physiological and pathophysiological functions. However, its effects and mechanisms in non-small cell lung cancer (NSCLC) still remain unknown. Here, we showed that expressions of total rpS6 and phosphorylation rpS6 (p-rpS6) were both significantly overexpressed in NSCLC. Further survival analysis revealed the shortened overall survival (OS) and relapse-free survival (RFS) in p-rpS6 overexpressed patients and confirmed it as an independent adverse predictor. Stable downregulation of rpS6 in lung adenocarcinoma A549 and squamous cell carcinoma H520 cell lines was then achieved by two specific small hairpin RNA (shRNA) lentiviruses separately. Subsequent experiments showed that downregulation of rpS6 dramatically inhibited cell proliferation in vitro and tumorigenicity in vivo. Moreover, loss of rpS6 promoted cells arrested in G0-G1 phase and reduced in G2-M phase, along with the expression alterations of relative proteins. However, no notable change in apoptosis was observed. Collectively, these results suggested that rpS6 is overactivated in NSCLC and its downregulation suppresses the growth of NSCLC mainly by inducing G0-G1 cell cycle arrest rather than apoptosis.

Non-Small Cell Lung Carcinoma Biomarker Testing: The Pathologist's Perspective

Biomarker testing has become standard of care for patients diagnosed with non-small cell lung carcinoma (NSCLC). Although, it can be successfully performed in circulating tumor cells, at present, the vast majority of investigations are carried out using direct tumor sampling, either through aspiration methods, which render most often isolated cells, or tissue sampling, that could range from minute biopsies to large resections. Consequently, pathologists play a central role in this process. Recent evidence suggests that refining NSCLC diagnosis might be clinically significant, particularly in cases of lung adenocarcinomas (ADC), which in turn, has prompted a new proposal for the histologic classification of such pulmonary neoplasms. These changes, in conjunction with the mandatory incorporation of biomarker testing in routine NSCLC tissue processing, have directly affected the pathologist’s role in lung cancer work-up. This new role pathologists must play is complex and demanding, and requires a close interaction with surgeons, oncologists, radiologists, and molecular pathologists. Pathologists often find themselves as the central figure in the coordination of a process, that involves assuring that the tumor samples are properly fixed, but without disruption of the DNA structure, obtaining the proper diagnosis with a minimum of tissue waste, providing pre-analytical evaluation of tumor samples selected for biomarker testing, which includes assessment of the proportion of tumor to normal tissues, as well as cell viability, and assuring that this entire process happens in a timely fashion. Therefore, it is part of the pathologist’s responsibilities to assure that the samples received in their laboratories, be processed in a manner that allows for optimal biomarker testing. This article goal is to discuss the essential role pathologists must play in NSCLC biomarker testing, as well as to provide a summarized review of the main NSCLC biomarkers of clinical interest.

Type III or allosteric kinase inhibitors for the treatment of non-small cell lung cancer

INTRODUCTION

In recent times, there has been much interest in the development of pharmacological kinase inhibitors that treat NSCLC. Furthermore, treatment options have been guided by the development of a wide panel of synthetic small molecule kinase inhibitors. Most of the molecules developed belong to the type I class of inhibitors that target the ATP-binding site in its active conformation. The high sequence similarity in the ATP-binding site among members of the kinase families often results in low selectivity and additional toxicities. Also, second mutations in the ATP-binding site, such as threonine to methionine at position 790, have been described as a mechanism of resistance to ATP-competitive kinase inhibitors. For these reasons, alternative drug development approaches targeting sites other than the ATP cleft are being pursued. The class III or allosteric inhibitors, which bind outside the ATP-binding site, have been shown to negatively modulate kinase activity.

AREAS COVERED

In this review, the authors discuss the most well-characterised allosteric inhibitors that have reached clinical development in NSCLC.

EXPERT OPINION

Great progress has made in developing inhibitors with entirely new modes of action. That being said, it is important to highlight that despite their apparent simplicity, biochemical assays will remain at the core of drug discovery activities to better explore these new opportunities.

Synthetic lethal screening reveals FGFR as one of the combinatorial targets to overcome resistance to Met-targeted therapy

Met is a receptor tyrosine kinase that promotes cancer progression. In addition, Met has been implicated in resistance of tumors to various targeted therapies such as epidermal growth factor receptor inhibitors in lung cancers, and has been prioritized as a key molecular target for cancer therapy. However, the underlying mechanism of resistance to Met-targeting drugs is poorly understood. Here, we describe screening of 1310 genes to search for key regulators related to drug resistance to an anti-Met therapeutic antibody (SAIT301) by using a small interfering RNA-based synthetic lethal screening method. We found that knockdown of 69 genes in Met-amplified MKN45 cells sensitized the antitumor activity of SAIT301. Pathway analysis of these 69 genes implicated fibroblast growth factor receptor (FGFR) as a key regulator for antiproliferative effects of Met-targeting drugs. Inhibition of FGFR3 increased target cell apoptosis through the suppression of Bcl-xL expression, followed by reduced cancer cell growth in the presence of Met-targeting drugs. Treatment of cells with the FGFR inhibitors substantially restored the efficacy of SAIT301 in SAIT301-resistant cells and enhanced the efficacy in SAIT301-sensitive cells. In addition to FGFR3, integrin β3 is another potential target for combination treatment with SAIT301. Suppression of integrin β3 decreased AKT phosphorylation in SAIT301-resistant cells and restored SAIT301 responsiveness in HCC1954 cells, which are resistant to SAIT301. Gene expression analysis using CCLE database shows that cancer cells with high levels of FGFR and integrin β3 are resistant to crizotinib treatment, suggesting that FGFR and integrin β3 could be used as predictive markers for Met-targeted therapy and provide a potential therapeutic option to overcome acquired and innate resistance for the Met-targeting drugs.

Proteogenomic analysis of human chromosome 9-encoded genes from human samples and lung cancer tissues

The Chromosome-centric Human Proteome Project (C-HPP) was recently initiated as an international collaborative effort. Our team adopted chromosome 9 (Chr 9) and performed a bioinformatics and proteogenomic analysis to catalog Chr 9-encoded proteins from normal tissues, lung cancer cell lines, and lung cancer tissues. Approximately 74.7% of the Chr 9 genes of the human genome were identified, which included approximately 28% of missing proteins (46 of 162) on Chr 9 compared with the list of missing proteins from the neXtProt Master Table (2013-09). In addition, we performed a comparative proteomics analysis between normal lung and lung cancer tissues. On the basis of the data analysis, 15 proteins from Chr 9 were detected only in lung cancer tissues. Finally, we conducted a proteogenomic analysis to discover Chr 9-residing single nucleotide polymorphisms (SNP) and mutations described in the COSMIC cancer mutation database. We identified 21 SNPs and four mutations containing peptides on Chr 9 from normal human cells/tissues and lung cancer cell lines, respectively. In summary, this study provides valuable information of the human proteome for the scientific community as part of C-HPP. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD000603.