Epithelial versus mesenchymal phenotype determines in vitro sensitivity and predicts clinical activity of erlotinib in lung cancer patients

[Phenotypical plasticity and targeted therapies in non-small cell lung carcinomas]

Lung cancer is the most diagnosed and deathly type of cancer worldwide. It has a poor prognosis because of a late diagnosis, high metastatic potential and resistance to conventional therapies. Since the 2000s, the emergence of targeted therapies has improved patients' outcomes. However, these therapies concern only a small proportion of patients, selected by the presence of molecular biomarkers that indicate the targeting relevance. Here, we discuss the possibility that new phenotypical biomarkers could be predictive factors for targeted therapies in lung cancer.

Impact of EMT in stage IIIB/IV NSCLC treated with erlotinib and bevacizumab when compared with cisplatin, gemcitabine and bevacizumab

The aim of the present study was to assess the expression of epithelial-mesenchymal transition biomarkers (E-cadherin and vimentin) and their potential significance as prognostic markers in patients with stage IIIB/IV non-squamous non-small cell lung cancer (NSCLC) enrolled in the INNOVATIONS trial, receiving treatment with either erlotinib/bevacizumab (EB) or cisplatin/gemcitabine/bevacizumab (PGB). The tumor tissues of 104 patients were retrospectively analyzed using immunohistochemistry to assess the expression of E-cadherin and vimentin. The distribution between the treatment arms was 46 patients in the EB-arm and 58 in the PGB-arm. Comparing the treatment arms according to E-cadherin and vimentin expression, the analysis revealed that progression-free survival (PFS) was increased in the PGB treatment group when compared with EB treatment in patients with low expression of E-cadherin [hazard ratio (HR)=0.353; 95% confidence interval (CI) 0.189- 0.658; log-rank P=0.0007] and in those with high expression of vimentin [HR=0.276 (95% CI, 0.115- 0.659), log-rank P=0.0021]. In patients that exhibited high E-cadherin and were negative for vimentin, there was no difference in the PFS between the PGB and EB treatment groups. In conclusion, in non-squamous NSCLC with downregulated E-cadherin and upregulated vimentin, the efficacy of chemotherapy with PGB was superior compared with EB; but the same effect was not observed in patients with high E-cadherin and low vimentin. Although increased PFS was observed in patients with PGB treatment compared with EB treatment in the whole analysis populations, in the subgroup of patients with the mesenchymal phenotype, no prognostic or predictive value of either biomarker could be identified. The potential role of bevacizumab in overcoming chemotherapy resistance in the population with the mesenchymal phenotype has to be further explored.

TAS-121, A Selective Mutant EGFR Inhibitor, Shows Activity Against Tumors Expressing Various EGFR Mutations Including T790M and Uncommon Mutations G719X

TAS-121 is a novel orally active selective covalent inhibitor of the mutant EGFR. We performed preclinical characterization of TAS-121 and compared its efficacy and selectivity for common EGFR mutations (Ex19del and L858R), first- and second- generation EGFR-tyrosine kinase inhibitor (EGFR-TKI) resistance mutation (T790M), and uncommon mutations (G719X and L861Q) with those of other EGFR-TKIs. We also commenced investigation of the clinical benefits of TAS-121. The IC₅₀ for intracellular EGFR phosphorylation was determined by using Jump-In GripTite HEK293 cells transiently transfected with EGFR expression vectors. Mouse xenograft models were used to evaluate the antitumor activity of TAS-121. TAS-121 potently inhibited common activating and resistance EGFR mutations to the same extent as another third-generation EGFR-TKI (osimertinib). In addition, TAS-121 showed equivalent inhibitory activity against some uncommon mutations such as G719X and L861Q. Furthermore, TAS-121 demonstrated greater selectivity for mutant EGFRs versus the wild-type EGFR compared with other EGFR-TKIs. Moreover, TAS-121 displayed antitumor activity in SW48 (EGFR G719S) and NCI-H1975 (EGFR L858R/T790M) xenograft models, and achieved an objective response in patients with NSCLC with EGFR mutations including G719A mutation. In conclusion, TAS-121 is a novel third-generation EGFR-TKI and demonstrates antitumor activities in patients with NSCLC expressing either common or uncommon EGFR mutations.

EGFR/Notch Antagonists Enhance the Response to Inhibitors of the PI3K-Akt Pathway by Decreasing Tumor-Initiating Cell Frequency

PURPOSE

Both EGFR and PI3K-Akt signaling pathways have been used as therapeutically actionable targets, but resistance is frequently reported. In this report, we show that enrichment of the cancer stem cell (CSC) subsets and dysregulation of Notch signaling underlie the challenges to therapy and describe the development of bispecific antibodies targeting both HER and Notch signaling.

EXPERIMENTAL DESIGN

We utilized cell-based models to study Notch signaling in drug-induced CSC expansion. Both cancer cell line models and patient-derived xenograft tumors were used to evaluate the antitumor effects of bispecific antibodies. Cell assays, flow cytometry, qPCR, and in vivo serial transplantation assays were employed to investigate the mechanisms of action and pharmacodynamic readouts.

RESULTS

We found that EGFR/Notch targeting bispecific antibodies exhibited a notable antistem cell effect in both in vitro and in vivo assays. Bispecific antibodies delayed the occurrence of acquired resistance to EGFR inhibitors in triple-negative breast cancer cell line-based models and showed efficacy in patient-derived xenografts. Moreover, the EGFR/Notch bispecific antibody PTG12 in combination with GDC-0941 exerted a stronger antitumor effect than the combined therapy of PI3K inhibitor with EGFR inhibitors or tarextumab in a broad spectrum of epithelial tumors. Mechanistically, bispecific antibody treatment inhibits the stem cell-like subpopulation, reduces tumor-initiating cell frequency, and downregulates the mesenchymal gene expression.

CONCLUSIONS

These findings suggest that the coblockade of EGFR and Notch signaling has the potential to increase the response to PI3K inhibition, and PTG12 may gain clinical efficacy when combined with PI3K blockage in cancer treatment.

Resistance to molecularly targeted therapy in non-small-cell lung cancer

The discovery of oncogenic driver gene mutations, including epidermal growth factor receptor (EGFR) mutation, anaplastic lymphoma kinase (ALK) fusion, ROS proto-oncogene 1 (ROS1) fusion, and ret proto-oncogene (RET) fusion, has led to the development of molecularly targeted therapy for non-small-cell lung cancer (NSCLC). This therapy has changed the standard of care for NSCLC. Despite the dramatic response to molecularly targeted therapy, almost all patients ultimately develop resistance to the drugs. To understand the mechanisms of resistance to molecularly targeted agents, it is essential to understand the molecular pathways of NSCLC. Here, we review the mechanisms of resistance to molecularly targeted therapy and discuss strategies to overcome drug resistance.

EMT: A mechanism for escape from EGFR-targeted therapy in lung cancer

Epithelial mesenchymal transition (EMT) is a reversible developmental genetic programme of transdifferentiation of polarised epithelial cells to mesenchymal cells. In cancer, EMT is an important factor of tumour cell plasticity and has received increasing attention for its role in the resistance to conventional and targeted therapies. In this paper we provide an overview of EMT in human malignancies, and discuss contribution of EMT to the development of the resistance to Epidermal Growth Factor Receptor (EGFR)-targeted therapies in non-small cell lung cancer (NSCLC). Patients with the tumours bearing specific mutations in EGFR have a good clinical response to selective EGFR inhibitors, but the resistance inevitably develops. Several mechanisms responsible for the resistance include secondary mutations in the EGFR gene, genetic or non-mutational activation of alternative survival pathways, transdifferentiation of NSCLC to the small cell lung cancer histotype, or formation of resistant tumours with mesenchymal characteristics. Mechanistically, application of an EGFR inhibitor does not kill all cancer cells; some cells survive the exposure to a drug, and undergo genetic evolution towards resistance. Here, we present a theory that these quiescent or slow-proliferating drug-tolerant cell populations, or so-called "persisters", are generated via EMT pathways. We review the EMT-activated mechanisms of cell survival in NSCLC, which include activation of ABC transporters and EMT-associated receptor tyrosine kinase AXL, immune evasion, and epigenetic reprogramming. We propose that therapeutic inhibition of these pathways would eliminate pools of persister cells and prevent or delay cancer recurrence when applied in combination with the agents targeting EGFR.

Hybrid epithelial/mesenchymal phenotypes promote metastasis and therapy resistance across carcinomas

Cancer metastasis and therapy resistance are the major unsolved clinical challenges, and account for nearly all cancer-related deaths. Both metastasis and therapy resistance are fueled by epithelial plasticity, the reversible phenotypic transitions between epithelial and mesenchymal phenotypes, including epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). EMT and MET have been largely considered as binary processes, where cells detach from the primary tumor as individual units with many, if not all, traits of a mesenchymal cell (EMT) and then convert back to being epithelial (MET). However, recent studies have demonstrated that cells can metastasize in ways alternative to traditional EMT paradigm; for example, they can detach as clusters, and/or occupy one or more stable hybrid epithelial/mesenchymal (E/M) phenotypes that can be the end point of a transition. Such hybrid E/M cells can integrate various epithelial and mesenchymal traits and markers, facilitating collective cell migration. Furthermore, these hybrid E/M cells may possess higher tumor-initiation and metastatic potential as compared to cells on either end of the EMT spectrum. Here, we review in silico, in vitro, in vivo and clinical evidence for the existence of one or more hybrid E/M phenotype(s) in multiple carcinomas, and discuss their implications in tumor-initiation, tumor relapse, therapy resistance, and metastasis. Together, these studies drive the emerging notion that cells in a hybrid E/M phenotype may occupy 'metastatic sweet spot' in multiple subtypes of carcinomas, and pathways linked to this (these) hybrid E/M state(s) may be relevant as prognostic biomarkers as well as a promising therapeutic targets.

Emerging multitarget tyrosine kinase inhibitors in the treatment of neuroendocrine neoplasms

In the last few years, the therapeutic approach for neuroendocrine neoplasms (NENs) has changed dramatically following the approval of several novel targeted treatments. The multitarget tyrosine kinase inhibitor (MTKI), sunitinib malate, has been approved by Regulatory Agencies in pancreatic NENs. The MTKI class, however, includes several other molecules (approved for other conditions), which are currently being studied in NENs. An in-depth review on the studies published on the MTKIs in neuroendocrine tumors such as axitinib, cabozantinib, famitinib, lenvatinib, nintedanib, pazopanib, sorafenib and sulfatinib was performed. Furthermore, we extensively searched on the Clinical Trial Registries databases worldwide, in order to collect information on the ongoing clinical trials related to this topic. Our systematic analysis on emerging MTKIs in the treatment of gastroenteropancreatic and lung NENs identifies in vitro and in vivo studies, which demonstrate anti-tumor activity of diverse MTKIs on neuroendocrine cells and tumors. Moreover, for the first time in the literature, we report an updated view concerning the upcoming clinical trials in this field: presently, phase I, II and III clinical trials are ongoing and will include, overall, a staggering 1667 patients. This fervid activity underlines the increasing interest of the scientific community in the use of emerging MTKIs in NEN treatment.

TGF-β Signaling in Lung Health and Disease

Transforming growth factor (TGF)-β is an evolutionarily conserved pleiotropic factor that regulates a myriad of biological processes including development, tissue regeneration, immune responses, and tumorigenesis. TGF-β is necessary for lung organogenesis and homeostasis as evidenced by genetically engineered mouse models. TGF-β is crucial for epithelial-mesenchymal interactions during lung branching morphogenesis and alveolarization. Expression and activation of the three TGF-β ligand isoforms in the lungs are temporally and spatially regulated by multiple mechanisms. The lungs are structurally exposed to extrinsic stimuli and pathogens, and are susceptible to inflammation, allergic reactions, and carcinogenesis. Upregulation of TGF-β ligands is observed in major pulmonary diseases, including pulmonary fibrosis, emphysema, bronchial asthma, and lung cancer. TGF-β regulates multiple cellular processes such as growth suppression of epithelial cells, alveolar epithelial cell differentiation, fibroblast activation, and extracellular matrix organization. These effects are closely associated with tissue remodeling in pulmonary fibrosis and emphysema. TGF-β is also central to T cell homeostasis and is deeply involved in asthmatic airway inflammation. TGF-β is the most potent inducer of epithelial-mesenchymal transition in non-small cell lung cancer cells and is pivotal to the development of tumor-promoting microenvironment in the lung cancer tissue. This review summarizes and integrates the current knowledge of TGF-β signaling relevant to lung health and disease.

Upregulation of EphB3 in gastric cancer with acquired resistance to a FGFR inhibitor

Amplification of fibroblast growth factor receptor2 (FGFR2) has been regarded as a druggable target in gastric cancer (GC). Despite known potential of AZD4547, a selective inhibitor of FGFR 1-3, to suppress tumorigenic effects of activated FGFR2, resistance to the targeted agent has been an unresolved issue. This study was performed to elucidate the mechanism of AZD4547 resistance in GC cells. SNU-16 cells were used to establish an AZD4547-resistant GC cell line, SNU-16R. Elevated phosphorylation of EphB3 was confirmed using the Human Phospho-Receptor Tyrosine Kinase Array kit. A tyrosine kinase inhibitor (TKI) of EphB3 was used to investigate the effects of suppressed EphB3 activity in the SNU-16R cell line. SNU-16R cells exhibited upregulated phosphorylation of EphB3. Treatment of SNU-16R cells with the EphB3 TKI resulted in induction of apoptosis, decreased cellular viability, and cell cycle arrest at sub-G1 phase. SNU-16R cells expressed upregulated levels of N-cadherin, vimentin, Snail, matrix metalloproteinase 2 (MMP-2), and MMP-9, and reduced levels of E-cadherin, characteristic of epithelial to mesenchymal transition (EMT). Matrigel invasion assay also demonstrated the increased invasiveness of SNU-16R cells. EphB3 TKI treatment inhibited EMT of SNU-16R cells. Activation of mammalian target of rapamycin (mTOR) through the Ras-ERK1/2 pathway was suggested as the signal transduction mechanism downstream EphB3 by showing enhanced phosphorylation of Raf-1, MEK1/2, ERK1/2, mTOR and its downstream substrates in SNU-16R cells. As expected, EphB3 TKI decreased phosphorylation of these proteins. Our data suggest phosphorylation of mTOR through signaling by EphB3 is a potential mechanism of AZD4547 resistance in GC cells.

Role of long non-coding RNA in drug resistance in non-small cell lung cancer

Lung cancer is the leading cause of cancer-associated death, and non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer cases. Many drugs have been used to treat NSCLC in order to improve patient prognosis. Platinum-based chemotherapy is the first-line treatment for locally advanced or metastatic patients. For patients with activating EGFR mutations, tyrosine kinase inhibitors are the best treatment choice. NSCLC initially exhibits an excellent response to treatment; however, acquired resistance has been observed in many patients, leading to ineffective treatment. Clinical resistance is an impediment in the treatment of patients with advanced NSCLC. Many sequencing technologies have shown that long non-coding RNA (lncRNA) is expressed differently between drug-resistant and drug-sensitive lung cancer cells. We review the literature on lncRNA in drug resistance of NSCLC. The aim of this review is to gain insight into the molecular mechanisms of drug resistance, mainly focusing on the role of lncRNA in NSCLC.

Synergistic antitumor activity of aspirin and erlotinib: Inhibition of p38 enhanced aspirin plus erlotinib-induced suppression of metastasis and promoted cancer cell apoptosis

High-dose erlotinib is effective for non-small cell lung cancer patients with brain metastases. The aim of the present study was to investigate whether aspirin could increase the anti-proliferative and anti-metastatic effects of regular erlotinib treatment. The data demonstrated that combining aspirin with erlotinib significantly induced apoptosis and inhibited tumor cell proliferation in several human cancer types. Furthermore, aspirin plus erlotinib significantly induced the activation of E-cadherin and suppression of p38. The data also indicated that the p38/E-cadherin pathway may be involved in the apoptosis caused by the combination of aspirin and erlotinib. As p38 and E-cadherin also serve a key role in epithelial-to-mesenchymal transition (EMT) and cancer metastasis, we hypothesized that the combination of aspirin and erlotinib may significantly inhibit tumor metastasis. First, aspirin plus erlotinib achieved potent inhibition of cancer cell migration and invasion, which are crucial for cancer metastasis. Next, the results demonstrated that aspirin plus erlotinib inhibited angiogenesis by suppressing endothelial cell migration and invasion. Moreover, it was confirmed that aspirin plus erlotinib exerted synergistic anti-angiogenic effects. Finally, the synergistic anti-proliferative and anti-metastatic effects of the combination of aspirin with erlotinib were further validated in an A549 xenograft model in vivo. In conclusion, aspirin plus erlotinib may be an effective combination regimen for patients with metastatic cancer.

Multiregion gene expression profiling reveals heterogeneity in molecular subtypes and immunotherapy response signatures in lung cancer

Intra-tumor heterogeneity may be present at all molecular levels. Genomic intra-tumor heterogeneity at the exome level has been reported in many cancer types, but comprehensive gene expression intra-tumor heterogeneity has not been well studied. Here, we delineated the gene expression intra-tumor heterogeneity by exploring gene expression profiles of 35 tumor regions from 10 non-small cell lung cancer tumors (three or four regions/tumor), including adenocarcinoma, squamous cell carcinoma, large-cell carcinoma, and pleomorphic carcinoma of the lung. Using Affymetrix Gene 1.0 ST arrays, we generated the gene expression data for every sample. Inter-tumor heterogeneity was generally higher than intra-tumor heterogeneity, but some tumors showed a substantial level of intra-tumor heterogeneity. The analysis of various clinically relevant gene expression signatures including molecular subtype, epithelial-to-mesenchymal transition, and anti-PD-1 resistance signatures also revealed heterogeneity between different regions of the same tumor. The gene expression intra-tumor heterogeneity we observed was associated with heterogeneous tumor microenvironments represented by stromal and immune cells infiltrated. Our data suggest that RNA-based prognostic or predictive molecular tests should be carefully conducted in consideration of the gene expression intra-tumor heterogeneity.

A Convergence-Based Framework for Cancer Drug Resistance

Despite advances in cancer biology and therapeutics, drug resistance remains problematic. Resistance is often multifactorial, heterogeneous, and prone to undersampling. Nonetheless, many individual mechanisms of targeted therapy resistance may coalesce into a smaller number of convergences, including pathway reactivation (downstream re-engagement of original effectors), pathway bypass (recruitment of a parallel pathway converging on the same downstream output), and pathway indifference (development of a cellular state independent of the initial therapeutic target). Similar convergences may also underpin immunotherapy resistance. Such parsimonious, convergence-based frameworks may help explain resistance across tumor types and therapeutic categories and may also suggest strategies to overcome it.

Mechanisms of resistance to anti-EGFR therapy in colorectal cancer

Targeting the epidermal growth factor receptor (EGFR) either alone or in combination with chemotherapy is effective for patients with RAS wild type metastatic colorectal cancer (mCRC). However, only a small percentage of mCRC patients are sensitive to anti-EGFR therapy and even the best cases finally become refractory to this therapy. It has become apparent that the RAS mutations correlate with resistance to anti-EGFR therapy. However, these resistance mechanisms only account for nearly 35% to 50% of nonresponsive patients, suggesting that there might be additional mechanisms. In fact, several novel pathways leading to escape from anti-EGFR therapy have been reported in recent years. In this review, we provide an overview of known and novel mechanisms that contribute to both primary and acquired anti-EGFR therapy resistance, and enlist possible treatment strategies to overcome or reverse this resistance.

The T790M resistance mutation in EGFR is only found in cfDNA from erlotinib-treated NSCLC patients that harbored an activating EGFR mutation before treatment

Background

Lung cancer patients with an activating mutation in the EGFR (epidermal growth factor receptor) can develop resistance to erlotinib treatment, which is often mediated by the T790M resistance mutation in EGFR. The difficulties in obtaining biopsies at progression make it challenging to investigate the appearance of the T790M mutation at progression in large patient cohorts. We have used cell free DNA (cfDNA) from patients treated with erlotinib to investigate if the development of a T790M mutation coincides with the presence of an activating EGFR mutation in the pre-treatment blood sample.

Methods

A cohort of 227 NSCLC (non-small cell lung cancer) adenocarcinoma patients was treated with erlotinib irrespective of EGFR-mutational status. Blood samples were drawn immediately before erlotinib treatment was initiated and again at progression. The cobas® EGFR Mutation Test v2 designed for cfDNA was used to identify 42 EGFR mutations.

Results

Of the 227 NSCLC patients, blood samples were available from 144 patients both before erlotinib treatment and at progression (within 1 month before or after clinical progression). One hundred and twenty-eight of the 144 were wild-type EGFR before treatment, and we demonstrate that the T790M mutation was not present at progression in any of these. In contrast, in the 16 patients with an activating EGFR mutation in the pre-treatment blood sample six patients (38%) were identified with a T790M mutation in the progression blood sample.

Conclusion

The T790M resistance mutation is only found in the cfDNA of erlotinib-treated NSCLC patients if they have an activating EGFR mutation before treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4108-0) contains supplementary material, which is available to authorized users.

PHD3 Controls Lung Cancer Metastasis and Resistance to EGFR Inhibitors through TGFα

Lung cancer is the leading cause of cancer-related death worldwide, in large part due to its high propensity to metastasize and to develop therapy resistance. Adaptive responses to hypoxia and epithelial-mesenchymal transition (EMT) are linked to tumor metastasis and drug resistance, but little is known about how oxygen sensing and EMT intersect to control these hallmarks of cancer. Here, we show that the oxygen sensor PHD3 links hypoxic signaling and EMT regulation in the lung tumor microenvironment. PHD3 was repressed by signals that induce EMT and acted as a negative regulator of EMT, metastasis, and therapeutic resistance. PHD3 depletion in tumors, which can be caused by the EMT inducer TGFβ or by promoter methylation, enhanced EMT and spontaneous metastasis via HIF-dependent upregulation of the EGFR ligand TGFα. In turn, TGFα stimulated EGFR, which potentiated SMAD signaling, reinforcing EMT and metastasis. In clinical specimens of lung cancer, reduced PHD3 expression was linked to poor prognosis and to therapeutic resistance against EGFR inhibitors such as erlotinib. Reexpression of PHD3 in lung cancer cells suppressed EMT and metastasis and restored sensitivity to erlotinib. Taken together, our results establish a key function for PHD3 in metastasis and drug resistance and suggest opportunities to improve patient treatment by interfering with the feedforward signaling mechanisms activated by PHD3 silencing.Significance: This study links the oxygen sensor PHD3 to metastasis and drug resistance in cancer, with implications for therapeutic improvement by targeting this system. Cancer Res; 78(7); 1805-19. ©2018 AACR.

Circulating Tumor Cells and Implications of the Epithelial-to-Mesenchymal Transition

The majority of cancer-related deaths result from metastasis, the process by which cancer cells escape the primary tumor site and enter into the blood circulation in order to disseminate to secondary locations throughout the body. Tumor cells found within the circulation are referred to as circulating tumor cells (CTCs), and their detection and enumeration correlate with poor prognosis. The epithelial-to-mesenchymal transition (EMT) is a dynamic process that imparts epithelial cells with mesenchymal-like properties, thus facilitating tumor cell dissemination and contributing to metastasis. However, EMT also results in the downregulation of various epithelial proteins typically utilized by CTC technologies for enrichment and detection of these rare cells, resulting in reduced detection of some CTCs, potentially those with a more metastatic phenotype. In addition to the current clinical role of CTCs as a prognostic biomarker, they also have potential as a predictive biomarker via CTC characterization. However, CTC characterization is complicated by the unknown biological significance of CTCs possessing an EMT-like phenotype, and the ability to capture and understand this CTC subpopulation is an essential step in the utilization of CTCs for patient management. This chapter will review the process of EMT and its contribution to metastasis; discusses current and future clinical applications of CTCs; and describes both traditional and novel methods for CTC enrichment, detection, and characterization with a specific focus on CTCs with an EMT phenotype.

Cancer-associated fibroblasts promote epithelial-mesenchymal transition and EGFR-TKI resistance of non-small cell lung cancers via HGF/IGF-1/ANXA2 signaling

The involvement of the tumor stromal cells in acquired resistance of non-small cell lung cancers (NSCLCs) to tyrosine kinase inhibitors (TKIs) has previously been reported, but the precise mechanism remains unclear. In the present study, we investigated the role and mechanism underlying Cancer-associated fibroblasts (CAFs) in TKI resistance of NSCLCs. In vitro and in vivo experiments showed that HCC827 and PC9 cells, non-small cell lung cancer cells with EGFR-activating mutations, became resistant to the EGFR-TKI gefitinib when cultured with CAFs isolated from NSCLC tissues. Moreover, we showed that CAFs could induce epithelial-mesenchymal transition (EMT) phenotype of HCC827 and PC9 cells, with an associated change in the expression of epithelial to mesenchymal transition markers. Using proteomics-based method, we identified that CAFs significantly increased the expression of the Annexin A2 (ANXA2). More importantly, knockdown of ANXA2 completely reversed EMT phenotype and gefitinib resistance induced by CAFs. Furthermore, we found that CAFs increased the expression and phosphorylation of ANXA2 by secretion of growth factors HGF and IGF-1 and by activation of the corresponding receptors c-met and IGF-1R. Dual inhibition of HGF/c-met and IGF-1/IGF-1R pathways could significantly suppress ANXA2, and markedly reduced CAFs-induced EMT and gefitinib resistance. Taken together, these findings indicate that CAFs promote EGFR-TKIs resistance through HGF/IGF-1/ANXA2/EMT signaling and may be an ideal therapeutic target in NSCLCs with EGFR-activating mutations.

High cripto-1 and low miR-205 expression levels as prognostic markers in early stage non-small cell lung cancer

OBJECTIVES

Cripto-1 (CR-1) plays a critical role in the activation of SMAD, SRC, and epithelial-to-mesenchymal transition (EMT) pathways and has been shown to be prognostic in several cancer types. In addition, we showed that CR-1 renders EGFR-mutated NSCLC cells resistant to EGFR-TKI through the activation of SRC and EMT via miR-205 downregulation. This study aimed to investigate the correlation between expression of CR-1 and miR-205 and prognosis of NSCLC patients with or without EGFR mutations.

MATERIALS AND METHODS

A total of 265 patients with stage I (AJCC 6th edition) radically resected NSCLC were tested for CR-1 expression and EGFR mutations by immunohistochemistry and miR-205 expression via qPCR assay.

RESULTS

CR-1 expression was evaluated with immunohistochemistry using a tissue microarray on 265 T1-2N0 surgical NSCLC samples. Of the 265 tumors, 250 (94%) expressed various levels of CR-1. A significant inverse correlation was identified between expression of miR-205 and CR-1. NSCLC patients (T1N0, n = 106) with high CR-1 expression had worse prognosis (shorter recurrence-free survival, p = .045) than those with low CR-1 expression. A similar trend was observed in NSCLC patients with normal preoperative carcinoembryonic antigen (CEA) levels (serum CEA levels <5 ng/ml; n = 179; p = .085); however, no significant correlation was found between CR-1 expression and survival rate in the T2N0 or high CEA groups. In addition, NSCLC patients with low miR-205 expression (n = 126) had poorer prognosis in terms of recurrence than those with high miR-205 expression (n = 127; p = .001).

CONCLUSION

High CR-1 expression is correlated with poor prognosis in NSCLC with low tumor burden and may be used to select high-risk patients for adjuvant chemotherapy in early NSCLC. Moreover, low miR-205 expression likely related to high CR-1 expression could be a prognostic marker for patients with NSCLC.

Epithelial contribution to the profibrotic stiff microenvironment and myofibroblast population in lung fibrosis

The contribution of epithelial-to-mesenchymal transition (EMT) to the profibrotic stiff microenvironment and myofibroblast accumulation in pulmonary fibrosis remains unclear. We examined EMT-competent lung epithelial cells and lung fibroblasts from control (fibrosis-free) donors or patients with idiopathic pulmonary fibrosis (IPF), which is a very aggressive fibrotic disorder. Cells were cultured on profibrotic conditions including stiff substrata and TGF-β1, and analyzed in terms of morphology, stiffness, and expression of EMT/myofibroblast markers and fibrillar collagens. All fibroblasts acquired a robust myofibroblast phenotype on TGF-β1 stimulation. Yet IPF myofibroblasts exhibited higher stiffness and expression of fibrillar collagens than control fibroblasts, concomitantly with enhanced FAKY397 activity. FAK inhibition was sufficient to decrease fibroblast stiffness and collagen expression, supporting that FAKY397 hyperactivation may underlie the aberrant mechanobiology of IPF fibroblasts. In contrast, cells undergoing EMT failed to reach the values exhibited by IPF myofibroblasts in all parameters examined. Likewise, EMT could be distinguished from nonactivated control fibroblasts, suggesting that EMT does not elicit myofibroblast precursors either. Our data suggest that EMT does not contribute directly to the myofibroblast population, and may contribute to the stiff fibrotic microenvironment through their own stiffness but not their collagen expression. Our results also support that targeting FAKY397 may rescue normal mechanobiology in IPF.

SUV420H2 is an epigenetic regulator of epithelial/mesenchymal states in pancreatic cancer

Epithelial-to-mesenchymal transition is implicated in metastasis. Viotti et al. show that the histone methyltransferase SUV420H2 favors the mesenchymal identity in pancreatic tumor cells by silencing key drivers of the epithelial state. High levels of SUV420H2 also correlate with a loss of epithelial characteristics in invasive cancer.

Epithelial-to-mesenchymal transition is implicated in metastasis, where carcinoma cells lose sessile epithelial traits and acquire mesenchymal migratory potential. The mesenchymal state is also associated with cancer stem cells and resistance to chemotherapy. It might therefore be therapeutically beneficial to promote epithelial identity in cancer. Because large-scale cell identity shifts are often orchestrated on an epigenetic level, we screened for candidate epigenetic factors and identified the histone methyltransferase SUV420H2 (KMT5C) as favoring the mesenchymal identity in pancreatic cancer cell lines. Through its repressive mark H4K20me3, SUV420H2 silences several key drivers of the epithelial state. Its knockdown elicited mesenchymal-to-epithelial transition on a molecular and functional level, and cells displayed decreased stemness and increased drug sensitivity. An analysis of human pancreatic cancer biopsies was concordant with these findings, because high levels of SUV420H2 correlated with a loss of epithelial characteristics in progressively invasive cancer. Together, these data indicate that SUV420H2 is an upstream epigenetic regulator of epithelial/mesenchymal state control.

Comparative gene co-expression network analysis of epithelial to mesenchymal transition reveals lung cancer progression stages

BACKGROUND

The epithelial to mesenchymal transition (EMT) plays a key role in lung cancer progression and drug resistance. The dynamics and stability of gene expression patterns as cancer cells transition from E to M at a systems level and relevance to patient outcomes are unknown.

METHODS

Using comparative network and clustering analysis, we systematically analyzed time-series gene expression data from lung cancer cell lines H358 and A549 that were induced to undergo EMT. We also predicted the putative regulatory networks controlling EMT expression dynamics, especially for the EMT-dynamic genes and related these patterns to patient outcomes using data from TCGA. Example EMT hub regulatory genes were validated using RNAi.

RESULTS

We identified several novel genes distinct from the static states of E or M that exhibited temporal expression patterns or 'periods' during the EMT process that were shared in different lung cancer cell lines. For example, cell cycle and metabolic genes were found to be similarly down-regulated where immune-associated genes were up-regulated after middle EMT stages. The presence of EMT-dynamic gene expression patterns supports the presence of differential activation and repression timings at the transcriptional level for various pathways and functions during EMT that are not detected in pure E or M cells. Importantly, the cell line identified EMT-dynamic genes were found to be present in lung cancer patient tissues and associated with patient outcomes.

CONCLUSIONS

Our study suggests that in vitro identified EMT-dynamic genes capture elements of gene EMT expression dynamics at the patient level. Measurement of EMT dynamic genes, as opposed to E or M only, is potentially useful in future efforts aimed at classifying patient's responses to treatments based on the EMT dynamics in the tissue.

Molecular-Targeted Therapies for Epidermal Growth Factor Receptor and Its Resistance Mechanisms

Cancer therapies targeting epidermal growth factor receptor (EGFR), such as small-molecule kinase inhibitors and monoclonal antibodies, have been developed as standard therapies for several cancers, such as non-small cell lung cancer, colorectal cancer, pancreatic cancer, breast cancer, and squamous cell carcinoma of the head and neck. Although these therapies can significantly prolong progression-free survival, curative effects are not often achieved because of intrinsic and/or acquired resistance. The resistance mechanisms to EGFR-targeted therapies can be categorized as resistant gene mutations, activation of alternative pathways, phenotypic transformation, and resistance to apoptotic cell death. Analysis of the processes that modulate EGFR signal transduction by EGFR-targeted inhibitors, such as tyrosine kinase inhibitors and monoclonal antibodies, has revealed new therapeutic opportunities and has elucidated novel mechanisms contributing to the discovery of more effective anticancer treatments. In this review, we discuss the roles of EGFR in cancer development, therapeutic strategies for targeting EGFR, and resistance mechanisms to EGFR-targeted therapies, with a focus on cancer therapies for individual patients.

Novel Molecular Challenges in Targeting Anaplastic Lymphoma Kinase in ALK-Expressing Human Cancers

Targeting anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase receptor initially identified as a potent oncogenic driver in anaplastic large-cell lymphoma (ALCL) in the form of nucleophosmin (NPM)-ALK fusion protein, using tyrosine kinase inhibitors has shown to be a promising therapeutic approach for ALK-expressing tumors. However, clinical resistance to ALK inhibitors invariably occurs, and the molecular mechanisms are incompletely understood. Recent studies have clearly shown that clinical resistance to ALK inhibitors is a multifactorial and complex mechanism. While few of the mechanisms of clinical resistance to ALK inhibitors such as gene mutation are well known, there are others that are not well covered. In this review, the molecular mechanisms of cancer stem cells in mediating resistance to ALK inhibitors as well as the current understanding of the molecular challenges in targeting ALK in ALK-expressing human cancers will be discussed.

Multi-omics analysis reveals that ornithine decarboxylase contributes to erlotinib resistance in pancreatic cancer cells

Molecular and metabolic alterations in cancer cells are one of the leading causes of acquired resistance to chemotherapeutics. In this study, we explored an experimental strategy to identify which of these alterations can induce erlotinib resistance in human pancreatic cancer. Using genetically matched erlotinib-sensitive (BxPC-3) and erlotinib-resistant (BxPC-3ER) pancreatic cancer cells, we conducted a multi-omics analysis of metabolomes and transcriptomes in these cells. Untargeted and targeted metabolomic analyses revealed significant changes in metabolic pathways involved in the regulation of polyamines, amino acids, and fatty acids. Further transcriptomic analysis identified that ornithine decarboxylase (ODC) and its major metabolite, putrescine, contribute to the acquisition of erlotinib resistance in BxPC-3ER cells. Notably, either pharmacological or genetic blockage of ODC was able to restore erlotinib sensitivity, and this could be rescued by treatment with exogenous putrescine in erlotinib-resistant BxPC-3ER cells. Moreover, using a panel of cancer cells we demonstrated that ODC expression levels in cancer cells are inversely correlated with sensitivity to chemotherapeutics. Taken together, our findings will begin to uncover mechanisms of acquired drug resistance and ultimately help to identify potential therapeutic markers in cancer.

Targeting epithelial-mesenchymal plasticity in cancer: clinical and preclinical advances in therapy and monitoring

The concept of epithelial-mesenchymal plasticity (EMP), which describes the dynamic flux within the spectrum of phenotypic states that invasive carcinoma cells may reside, is being increasingly recognised for its role in cancer progression and therapy resistance. The myriad of events that are able to induce EMP, as well as the more recently characterised control loops, results in dynamic transitions of cancerous epithelial cells to more mesenchymal-like phenotypes through an epithelial-mesenchymal transition (EMT), as well as the reverse transition from mesenchymal phenotypes to an epithelial one. The significance of EMP, in its ability to drive local invasion, generate cancer stem cells and facilitate metastasis by the dissemination of circulating tumour cells (CTCs), highlights its importance as a targetable programme to combat cancer morbidity and mortality. The focus of this review is to consolidate the existing knowledge on the strategies currently in development to combat cancer progression via inhibition of specific facets of EMP. The prevalence of relapse due to therapy resistance and metastatic propensity that EMP endows should be considered when designing therapy regimes, and such therapies should synergise with existing chemotherapeutics to benefit efficacy. To further improve upon EMP-targeted therapies, it is imperative to devise monitoring strategies to assess the impact of such treatments on EMP-related phenomenon such as CTC burden, chemosensitivity/-resistance and micrometastasis in patients.

Neuromedin U alters bioenergetics and expands the cancer stem cell phenotype in HER2-positive breast cancer

Neuromedin U (NmU) is a neuropeptide belonging to the neuromedin family. Recently, we reported a significant association between NmU and breast cancer, particularly correlating with increased aggressiveness, resistance to HER2-targeted therapies and overall significantly poorer outcome for patients, although the mechanism through which it exerts this effect remained unexplained. Investigating this, here we found that ectopic over-expression of NmU in HER2-positive breast cancer cells induced aberrant metabolism, with increased glycolysis, likely due to enhanced pyruvate dehydrogenase kinase activity. Similar results were observed in HER2-targeted drug-resistant cell variants, which we had previously shown to display increased levels of NmU. Overexpression of NmU also resulted in upregulation of epithelial-mesenchymal transition markers and increased IL-6 secretion which, together with aberrant metabolism, have all been associated with the cancer stem cell (CSC) phenotype. Flow cytometry experiments confirmed that NmU-overexpressing and HER2-targeted drug-resistant cells showed an increased proportion of cells with CSC phenotype (CD44⁺ /CD24^- ). Taken together, our results report a new mechanism of action for NmU in HER2-overexpressing breast cancer that enhances resistance to HER2-targeted drugs through conferring CSC characteristics and expansion of the CSC phenotype.

Lung cancer-associated brain metastasis: Molecular mechanisms and therapeutic options

BACKGROUND

Lung cancer is the most common cause of cancer-related mortality in humans. There are several reasons for this high rate of mortality, including metastasis to several organs, especially the brain. In fact, lung cancer is responsible for approximately 50% of all brain metastases, which are very difficult to manage. Understanding the cellular and molecular mechanisms underlying lung cancer-associated brain metastasis brings up novel therapeutic promises with the hope to ameliorate the severity of the disease. Here, we provide an overview of the molecular mechanisms underlying the pathogenesis of lung cancer dissemination and metastasis to the brain, as well as promising horizons for impeding lung cancer brain metastasis, including the role of cancer stem cells, the blood-brain barrier, interactions of lung cancer cells with the brain microenvironment and lung cancer-driven systemic processes, as well as the role of growth factor/receptor tyrosine kinases, cell adhesion molecules and non-coding RNAs. In addition, we provide an overview of current and novel therapeutic approaches, including radiotherapy, surgery and stereotactic radiosurgery, chemotherapy, as also targeted cancer stem cell and epithelial-mesenchymal transition (EMT)-based therapies, micro-RNA-based therapies and other small molecule or antibody-based therapies. We will also discuss the daunting potential of some combined therapies.

CONCLUSIONS

The identification of molecular mechanisms underlying lung cancer metastasis has opened up new avenues towards their eradication and provides interesting opportunities for future research aimed at the development of novel targeted therapies.

Stem Cell-Like Properties of CK2β-down Regulated Mammary Cells

The ubiquitous protein kinase CK2 has been demonstrated to be overexpressed in a number of human tumours. This enzyme is composed of two catalytic α or α’ subunits and a dimer of β regulatory subunits whose expression levels are probably implicated in CK2 regulation. Several recent papers reported that unbalanced expression of CK2 subunits is sufficient to drive epithelial to mesenchymal transition, a process involved in cancer invasion and metastasis. Herein, through transcriptomic and miRNA analysis together with comparison of cellular properties between wild type and CK2β-knock-down MCF10A cells, we show that down-regulation of CK2β subunit in mammary epithelial cells induces the acquisition of stem cell-like properties associated with perturbed polarity, CD44^high/CD24^low antigenic phenotype and the ability to grow under anchorage-independent conditions. These data demonstrate that a CK2β level establishes a critical cell fate threshold in the control of epithelial cell plasticity. Thus, this regulatory subunit functions as a nodal protein to maintain an epithelial phenotype and its depletion drives breast cell stemness.

Epithelial-to-Mesenchymal Transition and MicroRNAs in Lung Cancer

Despite major advances, non-small cell lung cancer (NSCLC) remains the major cause of cancer-related death in developed countries. Metastasis and drug resistance are the main factors contributing to relapse and death. Epithelial-to-mesenchymal transition (EMT) is a complex molecular and cellular process involved in tissue remodelling that was extensively studied as an actor of tumour progression, metastasis and drug resistance in many cancer types and in lung cancers. Here we described with an emphasis on NSCLC how the changes in signalling pathways, transcription factors expression or microRNAs that occur in cancer promote EMT. Understanding the biology of EMT will help to define reversing process and treatment strategies. We will see that this complex mechanism is related to inflammation, cell mobility and stem cell features and that it is a dynamic process. The existence of intermediate phenotypes and tumour heterogeneity may be debated in the literature concerning EMT markers, EMT signatures and clinical consequences in NSCLC. However, given the role of EMT in metastasis and in drug resistance the development of EMT inhibitors is an interesting approach to counteract tumour progression and drug resistance. This review describes EMT involvement in cancer with an emphasis on NSCLC and microRNA regulation.

Distinct effects of EGFR inhibitors on epithelial- and mesenchymal-like esophageal squamous cell carcinoma cells

Background

Epidermal growth factor receptor (EGFR) plays a pivotal role in the pathophysiology of esophageal squamous cell carcinoma (ESCC). However, the clinical effects of EGFR inhibitors on ESCC are controversial. This study sought to identify the factors determining the therapeutic efficacy of EGFR inhibitors in ESCC cells.

Methods

Immortalized-human esophageal epithelial cells (EPC2-hTERT), transformed-human esophageal epithelial cells (T-Epi and T-Mes), and ESCC cells (TE-1, TE-5, TE-8, TE-11, TE-11R, and HCE4) were treated with the EGFR inhibitors erlotinib or cetuximab. Inhibitory effects on cell growth were assessed by cell counting or cell-cycle analysis. The expression levels of genes and proteins such as involucrin and cytokeratin13 (a squamous differentiation marker), E-cadherin, and vimentin were evaluated by real-time polymerase chain reaction or western blotting. To examine whether mesenchymal phenotype influenced the effects of EGFR inhibitors, we treated T-Epi cells with TGF-β1 to establish a mesenchymal phenotype (mesenchymal T-Epi cells). We then compared the effects of EGFR inhibitors on parental T-Epi cells and mesenchymal T-Epi cells. TE-8 (mesenchymal-like ESCC cells)- or TE-11R (epithelial-like ESCC cells)-derived xenograft tumors in mice were treated with cetuximab, and the antitumor effects of EGFR inhibitors were evaluated.

Results

Cells were classified as epithelial-like or mesenchymal-like phenotypes, determined by the expression levels of E-cadherin and vimentin. Both erlotinib and cetuximab reduced cell growth and the ratio of cells in cell-cycle S phase in epithelial-like but not mesenchymal-like cells. Additionally, EGFR inhibitors induced squamous cell differentiation (defined as increased expression of involucrin and cytokeratin13) in epithelial-like but not mesenchymal-like cells. We found that EGFR inhibitors did not suppress the phosphorylation of EGFR in mesenchymal-like cells, while EGFR dephosphorylation was observed after treatment with EGFR inhibitors in epithelial-like cells. Furthermore, mesenchymal T-Epi cells showed resistance to EGFR inhibitors by circumventing the dephosphorylation of EGFR signaling. Cetuximab consistently showed antitumor effects, and increased involucrin expression in TE-11R (epithelial-like)-derived xenograft tumors but not TE-8 (mesenchymal-like)-derived xenograft tumors.

Conclusions

The factor determining the therapeutic effects of EGFR inhibitors in ESCC cells is the phenotype representing the epithelial-like or mesenchymal-like cells. Mesenchymal-like ESCC cells are resistant to EGFR inhibitors because EGFR signaling is not blocked. EGFR inhibitors show antitumor effects on epithelial-like ESCC cells accompanied by promotion of squamous cell differentiation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0572-7) contains supplementary material, which is available to authorized users.

MicroRNA-200c increases radiosensitivity of human cancer cells with activated EGFR-associated signaling

MicroRNA-200c (miR-200c) recently was found to have tumor-suppressive properties by inhibiting the epithelial-mesenchymal transition (EMT) in several cancers. miR-200c also interacts with various cellular signaling molecules and regulates many important signaling pathways. In this study, we investigated the radiosensitizing effect of miR-200c and its mechanism in a panel of human cancer cell lines. Malignant glioma (U251, T98G), breast cancer (MDA-MB-468), and lung carcinoma (A549) cells were transfected with control pre-microRNA, pre-miR-200c, or anti-miR-200c. Then, RT-PCR, clonogenic assays, immunoblotting, and immunocytochemisty were performed. To predict the potential targets of miR-200c, microRNA databases were used for bioinformatics analysis. Ectopic overexpression of miR-200c downregulated p-EGFR and p-AKT and increased the radiosensitivity of U251, T98G, A549, and MDA-MB-468 cells. In contrast, miR-200c inhibition upregulated p-EGFR and p-AKT, and decreased radiation-induced cell killing. miR-200c led to persistent γH2AX focus formation and downregulated pDNA-PKc expression. Autophagy and apoptosis were major modes of cell death. Bioinformatics analysis predicted that miR-200c may be associated with EGFR, AKT2, MAPK1, VEGFA, and HIF1AN. We also confirmed that miR-200c downregulated the expression of VEGF, HIF-1α, and MMP2 in U251 and A549 cells. In these cells, overexpressing miR-200c inhibited invasion, migration, and vascular tube formation. These phenotypic changes were associated with E-cadherin and EphA2 downregulation and N-cadherin upregulation. miR-200c showed no observable cytotoxic effect on normal human fibroblasts and astrocytes. Taken together, our data suggest that miR-200c is an attractive target for improving the efficacy of radiotherapy via a unique modulation of the complex regulatory network controlling cancer pro-survival signaling and EMT.

EMT: Present and future in clinical oncology

Epithelial/mesenchymal transition (EMT) has emerged as a key regulator of metastasis by facilitating tumor cell invasion and dissemination to distant organs. Recent evidences support that the reverse mesenchymal/epithelial transition (MET) is required for metastatic outgrowth; moreover, the existence of hybrid epithelial/mesenchymal (E/M) phenotypes is increasingly being reported in different tumor contexts. The accumulated data strongly support that plasticity between epithelial and mesenchymal states underlies the dissemination and metastatic potential of carcinoma cells. However, the translation into the clinics of EMT and epithelial plasticity processes presents enormous challenges and still remains a controversial issue. In this review, we will evaluate current evidences for translational applicability of EMT and depict an overview of the most recent EMT in vivo models, EMT marker analyses in human samples as well as potential EMT therapeutic approaches and ongoing clinical trials. We foresee that standardized analyses of EMT markers in solid and liquid tumor biopsies in addition to innovative tools targeting the E/M states will become promising strategies for future translation to the clinical setting.

Epithelial-mesenchymal plasticity and circulating tumor cells: Travel companions to metastases

Epithelial-mesenchymal transitions (EMTs) associated with metastatic progression may contribute to the generation of hybrid phenotypes capable of plasticity. This cellular plasticity would provide tumor cells with an increased potential to adapt to the different microenvironments encountered during metastatic spread. Understanding how EMT may functionally equip circulating tumor cells (CTCs) with an enhanced competence to survive in the bloodstream and niche in the colonized organs has thus become a major cancer research axis. We summarize here clinical data with CTC endpoints involving EMT. We then review the work functionally linking EMT programs to CTC biology and deciphering molecular EMT-driven mechanisms supporting their metastatic competence. Developmental Dynamics 247:432-450, 2018. © 2017 Wiley Periodicals, Inc.

Polyphyllin I Overcomes EMT-Associated Resistance to Erlotinib in Lung Cancer Cells via IL-6/STAT3 Pathway Inhibition

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is the most important limiting factor for treatment efficiency in EGFR-mutant non-small cell lung cancer (NSCLC). Much work has linked the epithelial-mesenchymal transition (EMT) to the emergence of drug resistance, consequently, ongoing research has been focused on exploring the therapeutic options to reverse EMT for delaying or preventing drug resistance. Polyphyllin I (PPI) is a natural compound isolated from Paris polyphylla rhizomes and displayed anti-cancer properties. In the current work, we aimed to testify whether PPI could reverse EMT and overcome acquired EGFR-TKI resistance. We exposed HCC827 lung adenocarcinoma cells to erlotinib which resulted in acquired resistance with strong features of EMT. PPI effectively restored drug sensitivity of cells that obtained acquired resistance. PPI reversed EMT and decreased interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway activation in erlotinib-resistant cells. Moreover, addition of IL-6 partially abolished the sensitization response of PPI. Furthermore, co-treatment of erlotinib and PPI completed abrogation of tumor growth in xenografts, which was associated with EMT reversal. In conclusion, PPI serves as a novel solution to conquer the EGFR-TKI resistance of NSCLC via reversing EMT by modulating IL-6/STAT3 signaling pathway. Combined PPI and erlotinib treatment provides a promising future for lung cancer patients to strengthen drug response and prolong survival.

SMAD4 Loss Is Associated with Cetuximab Resistance and Induction of MAPK/JNK Activation in Head and Neck Cancer Cells

Purpose: We previously demonstrated an association between decreased SMAD4 expression and cetuximab resistance in head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to further elucidate the clinical relevance of SMAD4 loss in HNSCC.Experimental Design: SMAD4 expression was assessed by IHC in 130 newly diagnosed and 43 patients with recurrent HNSCC. Correlative statistical analysis with clinicopathologic data was also performed. OncoFinder, a bioinformatics tool, was used to analyze molecular signaling in TCGA tumors with low or high SMAD4 mRNA levels. The role of SMAD4 was investigated by shRNA knockdown and gene reconstitution of HPV-negative HNSCC cell lines in vitro and in vivoResults: Our analysis revealed that SMAD4 loss was associated with an aggressive, HPV-negative, cetuximab-resistant phenotype. We found a signature of prosurvival and antiapoptotic pathways that were commonly dysregulated in SMAD4-low cases derived from TCGA-HNSCC dataset and an independent oral cavity squamous cell carcinoma (OSCC) cohort obtained from GEO. We show that SMAD4 depletion in an HNSCC cell line induces cetuximab resistance and results in worse survival in an orthotopic mouse model in vivo We implicate JNK and MAPK activation as mediators of cetuximab resistance and provide the foundation for the concomitant EGFR and JNK/MAPK inhibition as a potential strategy for overcoming cetuximab resistance in HNSCCs with SMAD4 loss.Conclusions: Our study demonstrates that loss of SMAD4 expression is a signature characterizing the cetuximab-resistant phenotype and suggests that SMAD4 expression may be a determinant of sensitivity/resistance to EGFR/MAPK or EGFR/JNK inhibition in HPV-negative HNSCC tumors. Clin Cancer Res; 23(17); 5162-75. ©2017 AACR.

Epidermal Growth Factor Receptor Cell Proliferation Signaling Pathways

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.

Epidermal Growth Factor Receptor Cell Proliferation Signaling Pathways

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer. Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation. These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways. These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle. Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression. We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways. We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors.

Differential expression of circulating biomarkers of tumor phenotype and outcomes in previously treated non-small cell lung cancer patients receiving erlotinib vs. cytotoxic chemotherapy

Background

The objective of this study was to identify serum biomarkers capable of predicting clinical outcomes in previously-treated NSCLC patients with wild-type for EGFR activating mutations or insufficient tissue for mutation status determination.

Methods

Sixty-six Luminex immunoassays representative of biological themes that emerged from a re-analysis of transcriptome data from the Cancer Genome Atlas (TCGA) were evaluate against pretreatment serum specimens from previously-treated advanced NSCLC patients received either cytotoxic chemotherapy (n=32) or erlotinib (n=79). Known EGFR mutation positive cases were excluded from analysis. Associations of biomarkers with outcome parameters and their differential interaction with treatment for survival outcomes were assessed using multivariate Cox PH analyses.

Results

Our EMT-based transcriptomic analysis revealed a range of biological processes associated with angiogenesis, apoptosis, cachexia, inflammation, and metabolism emerging as those most highly associated with patient outcome. These processes were evaluated via surrogate serum biomarkers. A treatment-biomarker interaction analysis revealed that higher pretreatment levels of c-Met signaling biomarkers (i.e. HGF levels), pro-inflammatory/ pro-cachexia (e.g. IL-8, sIL-2Rα, FGF-2) processes and a pro-angiogenic (e.g. TGF-α, IL-8, VEGF) milieu were associated with inferior survival (HR=0.35, 0.29, 0.58, 0.50, 0.61, 0.45, respectively; all p<0.05) for patients receiving chemotherapy, relative to erlotinib. In contrast, high levels of decoy receptor for IL-1, sIL-1RII, and a high tissue vimentin/E-cadherin ratio were associated with a poor OS (HR=3.78; p=0.00055) in the erlotinib cohort.

Conclusions

Contemporary precision medicine initiatives that pair patient tumor characteristics with the optimal therapy type may maximize the use of agents targeting EGFR in the treatment of NSCLC.

Long Non-Coding RNAs: Key Regulators of Epithelial-Mesenchymal Transition, Tumour Drug Resistance and Cancer Stem Cells

Epithelial mesenchymal transition (EMT), the adoption by epithelial cells of a mesenchymal-like phenotype, is a process co-opted by carcinoma cells in order to initiate invasion and metastasis. In addition, it is becoming clear that is instrumental to both the development of drug resistance by tumour cells and in the generation and maintenance of cancer stem cells. EMT is thus a pivotal process during tumour progression and poses a major barrier to the successful treatment of cancer. Non-coding RNAs (ncRNA) often utilize epigenetic programs to regulate both gene expression and chromatin structure. One type of ncRNA, called long non-coding RNAs (lncRNAs), has become increasingly recognized as being both highly dysregulated in cancer and to play a variety of different roles in tumourigenesis. Indeed, over the last few years, lncRNAs have rapidly emerged as key regulators of EMT in cancer. In this review, we discuss the lncRNAs that have been associated with the EMT process in cancer and the variety of molecular mechanisms and signalling pathways through which they regulate EMT, and finally discuss how these EMT-regulating lncRNAs impact on both anti-cancer drug resistance and the cancer stem cell phenotype.

Induction of Mesenchymal-Epithelial Transitions in Sarcoma Cells

Phenotypic plasticity refers to a phenomenon in which cells transiently gain traits of another lineage. During carcinoma progression, phenotypic plasticity drives invasion, dissemination and metastasis. Indeed, while most of the studies of phenotypic plasticity have been in the context of epithelial-derived carcinomas, it turns out sarcomas, which are mesenchymal in origin, also exhibit phenotypic plasticity, with a subset of sarcomas undergoing a phenomenon that resembles a mesenchymal-epithelial transition (MET). Here, we developed a method comprising the miR-200 family and grainyhead-like 2 (GRHL2) to mimic this MET-like phenomenon observed in sarcoma patient samples.We sequentially express GRHL2 and the miR-200 family using cell transduction and transfection, respectively, to better understand the molecular underpinnings of these phenotypic transitions in sarcoma cells. Sarcoma cells expressing miR-200s and GRHL2 demonstrated enhanced epithelial characteristics in cell morphology and alteration of epithelial and mesenchymal biomarkers. Future studies using these methods can be used to better understand the phenotypic consequences of MET-like processes on sarcoma cells, such as migration, invasion, metastatic propensity, and therapy resistance.

Expression of Neuroendocrine Factor VGF in Lung Cancer Cells Confers Resistance to EGFR Kinase Inhibitors and Triggers Epithelial-to-Mesenchymal Transition

Mutations in EGFR drive tumor growth but render tumor cells sensitive to treatment with EGFR tyrosine kinase inhibitors (TKI). Phenotypic alteration in epithelial-to-mesenchymal transition (EMT) has been linked to the TKI resistance in lung adenocarcinoma. However, the mechanism underlying this resistance remains unclear. Here we report that high expression of a neuroendocrine factor termed VGF induces the transcription factor TWIST1 to facilitate TKI resistance, EMT, and cancer dissemination in a subset of lung adenocarcinoma cells. VGF silencing resensitized EGFR-mutated lung adenocarcinoma cells to TKI. Conversely, overexpression of VGF in sensitive cells conferred resistance to TKIs and induced EMT, increasing migratory and invasive behaviors. Correlation analysis revealed a significant association of VGF expression with advanced tumor grade and poor survival in patients with lung adenocarcinoma. In a mouse xenograft model of lung adenocarcinoma, suppressing VGF expression was sufficient to attenuate tumor growth. Overall, our findings show how VGF can confer TKI resistance and trigger EMT, suggesting its potential utility as a biomarker and therapeutic target in lung adenocarcinoma. Cancer Res; 77(11); 3013-26. ©2017 AACR.

Early clinical development of epidermal growth factor receptor targeted therapy in breast cancer

INTRODUCTION

Epidermal growth factor receptor (EGFR) targeted treatment has been evaluated but has not shown a clear clinical benefit for breast cancer. This review article aims to consider the knowledge of the biological background of EGFR pathways in dissecting clinical studies of EGFR targeted treatment in breast cancer. Areas covered: This review focuses on the role of the EGFR pathway and the investigational drugs that target EGFR for breast cancer. Expert opinion: Recent studies have indicated that EGFR targeted therapy for breast cancer has some promising effects for patients with triple-negative breast cancer, basal-like breast cancer, and inflammatory breast cancer. However, predictive and prognostic biomarkers for EGFR targeted therapy have not been identified. The overexpression or amplification of EGFR itself may not be the true factor of induction of the canonical pathway as an oncogenic driver of breast cancer. Instead, downstream, non-canonical pathways related to EGFR may contribute to some aspects of the biological behavior of breast cancer; therefore, the blockade of the receptor could result in sufficient suppression of downstream pathways to inhibit the aggressive behavior of breast cancer. Mechanistic studies to investigate the dynamic interaction between the EGFR pathway and non-canonical pathways are warranted.

Molecular mechanisms of therapy resistance in solid tumors: chasing "moving" targets

The goal of personalized cancer therapy is to treat tumors based on genomic aberrations that drive their survival and progression. Most patients who receive targeted therapies typically develop resistance and disease progression within a year's time. This review focuses on the heterogeneous mechanisms of therapy resistance to tyrosine kinase inhibitors, endocrine/hormone therapy and checkpoint blockade using non-small cell lung cancer, breast and castration-resistant prostate cancer, and melanoma as classical examples, respectively. In addition, testing for resistance mechanisms and therapeutic approaches to overcoming resistance is addressed.

Antagonism of EGFR and Notch limits resistance to EGFR inhibitors and radiation by decreasing tumor-initiating cell frequency

Epidermal growth factor receptor (EGFR) blockade and radiation are efficacious in the treatment of cancer, but resistance is commonly reported. Studies have suggested that dysregulation of Notch signaling and enrichment of the cancer stem cell population underlie these treatment challenges. Our data show that dual targeting of EGFR and Notch2/3 receptors with antibody CT16 not only inhibited signaling mediated by these receptors but also showed a strong anti-stem cell effect both in vitro and in vivo. Treatment with CT16 prevented acquired resistance to EGFR inhibitors and radiation in non-small cell lung cancer (NSCLC) cell line models and patient-derived xenograft tumors. CT16 also had a superior radiosensitizing impact compared with EGFR inhibitors. CT16 in combination with radiation had a larger antitumor effect than the combination of radiation with EGFR inhibitors or tarextumab. Mechanistically, CT16 treatment inhibits the stem cell-like subpopulation, which has a high mesenchymal gene expression and DNA repair activity, and reduces tumor-initiating cell frequency. This finding highlights the capacity of a combined blockade of EGFR and Notch signaling to augment the response to radiation and suggests that CT16 may achieve clinical efficacy when combined with radiation in NSCLC treatment.