Spheres derived from lung adenocarcinoma pleural effusions: molecular characterization and tumor engraftment

Identification of a set of genes potentially responsible for resistance to ferroptosis in lung adenocarcinoma cancer stem cells

Scientific literature supports the evidence that cancer stem cells (CSCs) retain inside low reactive oxygen species (ROS) levels and are, therefore, less susceptible to cell death, including ferroptosis, a type of cell death dependent on iron-driven lipid peroxidation. A collection of lung adenocarcinoma (LUAD) primary cell lines derived from malignant pleural effusions (MPEs) of patients was used to obtain 3D spheroids enriched for stem-like properties. We observed that the ferroptosis inducer RSL3 triggered lipid peroxidation and cell death in LUAD cells when grown in 2D conditions; however, when grown in 3D conditions, all cell lines underwent a phenotypic switch, exhibiting substantial resistance to RSL3 and, therefore, protection against ferroptotic cell death. Interestingly, this phenomenon was reversed by disrupting 3D cells and growing them back in adherence, supporting the idea of CSCs plasticity, which holds that cancer cells have the dynamic ability to transition between a CSC state and a non-CSC state. Molecular analyses showed that ferroptosis resistance in 3D spheroids correlated with an increased expression of antioxidant genes and high levels of proteins involved in iron storage and export, indicating protection against oxidative stress and low availability of iron for the initiation of ferroptosis. Moreover, transcriptomic analyses highlighted a novel subset of genes commonly modulated in 3D spheroids and potentially capable of driving ferroptosis protection in LUAD-CSCs, thus allowing to better understand the mechanisms of CSC-mediated drug resistance in tumors.

Heterogeneity of cancer stem cell-related marker expression is associated with three-dimensional structures in malignant pleural effusion produced by lung adenocarcinoma

INTRODUCTION

Cancer stem cells have been described in lung adenocarcinoma-associated malignant pleural effusion. They show clinically important features, including the ability to initiate new tumours and resistance to treatments. However, their correlation with the three-dimensional tumour structures in the effusion is not well understood.

METHODS

Cell blocks produced from lung adenocarcinoma patients' pleural effusion were examined for cancer stem cell-related markers Nanog and CD133 using immunocytochemistry. The three-dimensional cancer cell structures and CD133 expression patterns were visualized with tissue-clearing technology. The expression patterns were correlated with tumour cell structures, genetic variants and clinical outcomes.

RESULTS

Thirty-nine patients were analysed. Moderate-to-strong Nanog expression was detected in 27 cases (69%), while CD133 was expressed by more than 1% of cancer cells in 11 cases (28%). Nanog expression was more homogenous within individual specimens, while CD133 expression was detected in single tumour cells or cells within small clusters instead of larger structures in 8 of the 11 positive cases (73%). Although no statistically significant correlation between the markers and tumour genetic variants or patient survival was observed, we recorded seven cases with follow-up specimens after cancer treatment, and four (57%) showed a change in stem cell-related marker expression corresponding to treatment response.

CONCLUSIONS

Lung adenocarcinoma cells in the pleural effusion show variable expression of cancer stem cell-related markers, some showing a correlation with the size of cell clusters. Their expression level is potentially correlated with cancer treatment effects.

An Update on Potential Molecular Biomarkers of Dietary Phytochemicals Targeting Lung Cancer Interception and Prevention

Since ancient times, dietary phytochemicals are known for their medicinal properties. They are broadly classified into polyphenols, terpenoids, alkaloids, phytosterols, and organosulfur compounds. Currently, there is considerable interest in their potential health effects against various diseases, including lung cancer. Lung cancer is the leading cause of cancer deaths with an average of five-year survival rate of lung cancer patients limited to just 14%. Identifying potential early molecular biomarkers of pre-malignant lung cancer cells may provide a strong basis to develop early cancer detection and interception methods. In this review, we will discuss molecular changes, including genetic alterations, inflammation, signal transduction pathways, redox imbalance, epigenetic and proteomic signatures associated with initiation and progression of lung carcinoma. We will also highlight molecular targets of phytochemicals during lung cancer development. These targets mainly consist of cellular signaling pathways, epigenetic regulators and metabolic reprogramming. With growing interest in natural products research, translation of these compounds into new cancer prevention approaches to medical care will be urgently needed. In this context, we will also discuss the overall pharmacokinetic challenges of phytochemicals in translating to humans. Lastly, we will discuss clinical trials of phytochemicals in lung cancer patients.

Clinical importance of serum and pleural fluid prominin-1 and hypoxia-inducible factor-1α concentration in the evaluation of lymph node involvement in patients with malignant pleural effusion

Introduction

Malignant pleural effusion (MPE) and lymph node metastasis (LNM) presence are poor prognostic factors that have importance for cancer patients. The study objective was to determine whether hypoxia-inducible factor-1α (HIF-1α) and prominin-1 (CD133) in pleural fluid (P) and serum (S) could be used as biomarkers for diagnosis of lymph node involvement in patients with MPE.

Materials and methods

Fifty-six patients with MPE and 30 healthy control subjects were included. Computerized tomography (CT) and positron emission tomography (PET) were used to diagnose pleural effusion. Patients with malignant cells in pleural fluid cytological examination were included in the MPE group. Thirty-five patients with lymph node metastases on CT were included in the LNM-positive MPE group. Serum and pleural fluid HIF-1α and CD-133 concentrations were measured manually via enzyme-linked immunosorbent assay (ELISA).

Results

Serum concentrations of HIF-1α and CD133 were higher in MPE patients. It was found that CD133/HIF-1α (S) ratio was higher in the malignant patient group with positive lymph node involvement than in the negative group, while concentrations of HIF-1α (P) were lower. Pleural fluid HIF-1α and CD133/HIF-1α (S) ratio had sufficient performance in diagnosing lymphatic metastases in patients with MPE (AUC = 0.90 and 0.83, respectively).

Conclusions

In conclusion, serum HIF-1α and CD133 concentrations were higher in patients with MPE, consistent with our hypothesis. Concentrations of HIF-1α (P) and CD133/HIF-1α (S) ratio can be used as biomarkers in diagnosing lymph node involvement in MPE patients, according to this experiment.

Patient-derived organoids of lung cancer based on organoids-on-a-chip: enhancing clinical and translational applications

Lung cancer is one of the most common malignant tumors worldwide, with high morbidity and mortality due to significant individual characteristics and genetic heterogeneity. Personalized treatment is necessary to improve the overall survival rate of the patients. In recent years, the development of patient-derived organoids (PDOs) enables lung cancer diseases to be simulated in the real world, and closely reflects the pathophysiological characteristics of natural tumor occurrence and metastasis, highlighting their great potential in biomedical applications, translational medicine, and personalized treatment. However, the inherent defects of traditional organoids, such as poor stability, the tumor microenvironment with simple components and low throughput, limit their further clinical transformation and applications. In this review, we summarized the developments and applications of lung cancer PDOs and discussed the limitations of traditional PDOs in clinical transformation. Herein, we looked into the future and proposed that organoids-on-a-chip based on microfluidic technology are advantageous for personalized drug screening. In addition, combined with recent advances in lung cancer research, we explored the translational value and future development direction of organoids-on-a-chip in the precision treatment of lung cancer.

Genomic and Transcriptomic Analyses of Malignant Pleural Mesothelioma (MPM) Samples Reveal Crucial Insights for Preclinical Testing

Cell lines are extensively used to study cancer biology. However, the use of highly passaged commercial cell lines has to be questioned, as they do not closely resemble the originating tumor. To understand the reliability of preclinical models for Malignant pleural mesothelioma (MPM) studies, we have performed whole transcriptome and whole exome analyses of fresh frozen MPM tumors and compared them to cell lines generated from these tumors, as well as commercial cell lines and a preclinical MPM mouse model. Patient-derived cell lines were generated from digested fresh tumors and whole exome sequencing was performed on DNA isolated from formalin-fixed, paraffin-embedded (FFPE) tumor samples, corresponding patient-derived cell lines, and normal tissue. RNA sequencing libraries were prepared from 10 fresh frozen tumor samples, the 10 corresponding patient-derived cell lines, and 7 commercial cell lines. Our results identified alterations in tumor suppressor genes such as FBXW7, CDKN2A, CDKN2B, and MTAP, all known to drive MPM tumorigenesis. Patient-derived cell lines correlate to a high degree with their originating tumor. Gene expressions involved in multiple pathways such as EMT, apoptosis, myogenesis, and angiogenesis are upregulated in tumor samples when compared to patient-derived cell lines; however, they are downregulated in commercial cell lines compared to patient-derived cell lines, indicating significant differences between the two model systems. Our results show that the genome and transcriptome of tumors correlate to a higher degree with patient-derived cell lines rather than commercial cell lines. These results are of major relevance for the scientific community in regard to using cell lines as an appropriate model, resembling the pathway of interest to avoid misleading results for clinical applications.

Establishment and Characterization of Patient-Derived Xenograft Model of Non-Small-Cell Lung Cancer Derived from Malignant Pleural Effusions

Purpose

Non-small-cell lung cancer (NSCLC) comprises approximately 80% of all lung malignancies. The 5-year survival rate of patients with advanced lung cancer who lost their chances of surgery is approximately 15%. Suitable animal models are important in screening individualized treatment plans for patients with lung cancer, evaluating the pre-clinical efficacy of new drugs, and conducting basic research.

Patients and Methods

In this study, we collected malignant pleural effusion (MPE) samples from 31 patients with NSCLC, successfully constructed 11 NSCLC patient-derived xenografts (PDXs), and analyzed the factors affecting their successful establishment. Primary PDX tumors were characterized using histological analysis, immunohistochemistry, short tandem repeat (STR) profiling, and cytogenetic analysis.

Results

The PDXs preserved the histopathology and protein expression pattern of parental tumors. STR analysis revealed the PDX tissue and a tumor tissue of the same individual origin. Statistical analysis showed that the survival time of patients reflected the malignant degree of MPEs to a certain extent, thus affecting the establishment of PDXs. However, the age, gender, and clinical and biochemical indicators of the patients did not affect the establishment of PDX models.

Conclusion

These data suggest that the established NSCLC PDXs preserved the molecular characteristics of primary lung cancer and can serve as a new tool to elucidate the pathogenesis of tumors, explore new treatment methods, and conduct the research and development of new drugs for tumors.

Long Noncoding RNAs and Circular RNAs in the Metabolic Reprogramming of Lung Cancer: Functions, Mechanisms, and Clinical Potential

As key regulators of gene function, long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are generally accepted to be involved in lung cancer pathogenesis and progression. Recent research has clarified the phenomenon of metabolic reprogramming in lung cancer because of its significant role in tumor proliferation, migration, invasion, metastasis, and other malignant biological behaviors. Emerging evidence has also shown a relationship between the aberrant expression of lncRNAs and circRNAs and metabolic reprogramming in lung cancer tumorigenesis. This review provides insight regarding the roles of different lncRNAs and circRNAs in lung cancer metabolic reprogramming, by how they target transporter proteins and key enzymes in glucose, lipid, and glutamine metabolic signaling pathways. The clinical potential of lncRNAs and circRNAs as early diagnostic biomarkers and components of therapeutic strategies in lung cancer is further discussed, including current challenges in their utilization from the bench to the bedside and how to adopt a proper delivery system for their therapeutic use.

Deconvolution of malignant pleural effusions immune landscape unravels a novel macrophage signature associated with worse clinical outcome in lung adenocarcinoma patients

Background

Immune checkpoint inhibitors are still unable to provide clinical benefit to the large majority of non-small cell lung cancer (NSCLC) patients. A deeper characterization of the tumor immune microenvironment (TIME) is expected to shed light on the mechanisms of cancer immune evasion and resistance to immunotherapy. Here, we exploited malignant pleural effusions (MPEs) from lung adenocarcinoma (LUAD) patients as a model system to decipher TIME in metastatic NSCLC.

Methods

Mononuclear cells from MPEs (PEMC) and peripheral blood (PBMC), cell free pleural fluid and/or plasma were collected from a total of 24 LUAD patients and 12 healthy donors. Bulk-RNA sequencing was performed on total RNA extracted from PEMC and matched PBMC. The DEseq2 Bioconductor package was used to perform differential expression analysis and CIBERSORTx for the regression-based immune deconvolution of bulk gene expression data. Cytokinome analysis of cell-free pleural fluid and plasma samples was performed using a 48-Plex Assay panel. THP-1 monocytic cells were used to assess macrophage polarization. Survival analyses on NSCLC patients were performed using KM Plotter (LUAD, N=672; lung squamous cell carcinoma, N=271).

Results

Transcriptomic analysis of immune cells and cytokinome analysis of soluble factors in the pleural fluid depicted MPEs as a metastatic niche in which all the components required for an effective antitumor response are present, but conscripted in a wound-healing, proinflammatory and tumor-supportive mode. The bioinformatic deconvolution analysis revealed an immune landscape dominated by myeloid subsets with the prevalence of monocytes, protumoral macrophages and activated mast cells. Focusing on macrophages we identified an MPEs-distinctive signature associated with worse clinical outcome in LUAD patients.

Conclusions

Our study reports for the first time a wide characterization of MPEs LUAD microenvironment, highlighting the importance of specific components of the myeloid compartment and opens new perspectives for the rational design of new therapies for metastatic NSCLC.

The Fight against Cancer by Microgravity: The Multicellular Spheroid as a Metastasis Model

Cancer is a disease exhibiting uncontrollable cell growth and spreading to other parts of the organism. It is a heavy, worldwide burden for mankind with high morbidity and mortality. Therefore, groundbreaking research and innovations are necessary. Research in space under microgravity (µg) conditions is a novel approach with the potential to fight cancer and develop future cancer therapies. Space travel is accompanied by adverse effects on our health, and there is a need to counteract these health problems. On the cellular level, studies have shown that real (r-) and simulated (s-) µg impact survival, apoptosis, proliferation, migration, and adhesion as well as the cytoskeleton, the extracellular matrix, focal adhesion, and growth factors in cancer cells. Moreover, the µg-environment induces in vitro 3D tumor models (multicellular spheroids and organoids) with a high potential for preclinical drug targeting, cancer drug development, and studying the processes of cancer progression and metastasis on a molecular level. This review focuses on the effects of r- and s-µg on different types of cells deriving from thyroid, breast, lung, skin, and prostate cancer, as well as tumors of the gastrointestinal tract. In addition, we summarize the current knowledge of the impact of µg on cancerous stem cells. The information demonstrates that µg has become an important new technology for increasing current knowledge of cancer biology.

BRD4 REGULATES TRANSCRIPTION FACTOR ∆Np63αTO DRIVE A CANCER STEM CELL PHENOTYPE IN SQUAMOUS CELL CARCINOMAS

Bromodomain containing protein 4 (BRD4) plays a critical role in controlling the expression of genes involved in development and cancer. Inactivation of BRD4 inhibits cancer growth, making it a promising anticancer drug target. The cancer stem cell population is a key driver of recurrence and metastasis in cancer patients. Here we show that cancer stem-like cells can be enriched from squamous cell carcinomas, and that these cells display an aggressive phenotype with enhanced stem cell marker expression, migration, invasion, and tumor growth. BRD4 was highly elevated in this aggressive subpopulation of cells, and its function is critical for these cancer stem cell-like properties. Moreover, BRD4 regulated ∆Np63α, a key transcription factor that is essential for epithelial stem cell function that is often overexpressed in cancers. BRD4 regulated an EZH2/STAT3 complex that led to increased ∆Np63α-mediated transcription. Targeting BRD4 in human squamous cell carcinoma reduces ∆Np63α, leading to inhibition of spheroid formation, migration, invasion and tumor growth. These studies identify a novel BRD4-regulated signaling network in a subpopulation of cancer stem-like cells elucidating a possible avenue for effective therapeutic intervention.

ALDH1 and SALL4 Expression in Cell Block Samples from Patients with Lung Adenocarcinoma and Malignant Pleural Effusion

Malignant pleural effusion (MPE) can accompany advanced lung adenocarcinoma. Recent studies suggest that MPE could contain a heterogeneous subpopulation of cells with stem-like properties, such as tumorigenicity and self-renewal, indicating that they could be the source of metastasis. Although previous studies analyzed the correlation between cancer stem cell (CSC) marker expression and clinical outcomes using lung cancer tissues, investigations regarding the association of MPE with CSC marker expression are limited. We performed immunohistochemistry to examine the expression of aldehyde dehydrogenase 1 (ALDH1) and Sal-like 4 (SALL4) in 46 cell block samples of MPE from patients with lung adenocarcinoma. ALDH1-positive and SALL4-positive cancer cells in MPE were detected in 30 (65.2%) and 21 samples (45.7%), respectively. Cluster formation was detected in 26 samples (56.5%). The number of clusters was significantly higher in ALDH1-positive/SALL4-negative samples. SALL4 expression was inversely correlated with the cluster ratio (r = −0.356) and positively associated with the Ki-67 index (r = 0.326), suggesting that MPE cells with high SALL4 expression comprised the proliferative subpopulation. In conclusion, we demonstrated that MPE contains an ALDH1-positive/SALL4-negative subpopulation exhibiting cluster formation and a SALL4-positive proliferative subpopulation.

Cancer Stem Cells and the Slow Cycling Phenotype: How to Cut the Gordian Knot Driving Resistance to Therapy in Melanoma

Simple Summary

Cancer stem cells play a central role in the development of cancer and are poorly sensitive to standard chemotherapy and radiotherapy. Furthermore, they are also responsible for the onset of drug resistance. This also occurs in malignant melanoma, the deadliest form of skin cancer. Hence, cancer stem cells eradication is one of the main challenges for medical oncology. Here, we conducted a bioinformatics approach aimed to identify the main circuits and proteins underpinning cancer stem cell fitness in melanoma. Several lessons emerged from our work and may help to conceptualize future therapeutic approaches to prolong the efficacy of current therapies.

Abstract

Cancer stem cells (CSCs) have historically been defined as slow cycling elements that are able to differentiate into mature cells but without dedifferentiation in the opposite direction. Thanks to advances in genomic and non-genomic technologies, the CSC theory has more recently been reconsidered in a dynamic manner according to a “phenotype switching” plastic model. Transcriptional reprogramming rewires this plasticity and enables heterogeneous tumors to influence cancer progression and to adapt themselves to drug exposure by selecting a subpopulation of slow cycling cells, similar in nature to the originally defined CSCs. This model has been conceptualized for malignant melanoma tailored to explain resistance to target therapies. Here, we conducted a bioinformatics analysis of available data directed to the identification of the molecular pathways sustaining slow cycling melanoma stem cells. Using this approach, we identified a signature of 25 genes that were assigned to four major clusters, namely (1) kinases and metabolic changes, (2) melanoma-associated proteins, (3) Hippo pathway and (4) slow cycling/CSCs factors. Furthermore, we show how a protein−protein interaction network may be the main driver of these melanoma cell subpopulations. Finally, mining The Cancer Genome Atlas (TCGA) data we evaluated the expression levels of this signature in the four melanoma mutational subtypes. The concomitant alteration of these genes correlates with the worst overall survival (OS) for melanoma patients harboring BRAF-mutations. All together these results underscore the potentiality to target this signature to selectively kill CSCs and to achieve disease control in melanoma.

Spheroid-Based Approach to Assess the Tissue Relevance of Analysis of Dispersed-Settled Tissue Cells by Cytometry of the Reaction Rate Constant

Cytometry of Reaction Rate Constant (CRRC) uses time-lapse fluorescence microscopy to measure a rate constant of a catalytic reaction in individual cells and, thus, facilitate accurate size determination for cell subpopulations with distinct efficiencies of this reaction. Reliable CRRC requires uniform exposure of cells to the reaction substrate followed by their uniform imaging, which in turn, requires that a tissue sample be disintegrated into a suspension of dispersed cells, and these cells settle on the support surface before being analyzed by CRRC. We call such cells "dispersed-settled" to distinguish them from cells cultured as a monolayer. Studies of the dispersed-settled cells can be tissue-relevant only if the cells maintain their 3D tissue state during the multi-hour CRRC procedure. Here, we propose an approach for assessing tissue relevance of the CRRC-based analysis of the dispersed-settled cells. Our approach utilizes cultured multicellular spheroids as a 3D cell model and cultured cell monolayers as a 2D cell model. The CRRC results of the dispersed-settled cells derived from spheroids are compared to those of spheroids and monolayers in order to find if the dispersed-settled cells are representative of the spheroids. To demonstrate its practical use, we applied this approach to a cellular reaction of multidrug resistance (MDR) transport, which was followed by extrusion of a fluorescent substrate from the cells. The approach proved to be reliable and revealed long-term maintenance of MDR transport in the dispersed-settled cells obtained from cultured ovarian cancer spheroids. Accordingly, CRRC can be used to determine accurately the size of a cell subpopulation with an elevated level of MDR transport in tumor samples, which makes CRRC a suitable method for the development of MDR-based predictors of chemoresistance. The proposed spheroid-based approach for validation of CRRC is applicable to other types of cellular reactions and, thus, will be an indispensable tool for transforming CRRC from an experimental technique into a practical analytical tool.

Establishment of Peritoneal and Hepatic Metastasis Mouse Xenograft Models Using Gastric Cancer Cell Lines

BACKGROUND/AIM

Establishment of mouse xenograft models is necessary for oncological research and depends on the characteristics of the cell lines and the immune system of the host. In this study, we describe the development of mouse xenograft models using human gastric cancer (GC) cell lines.

MATERIALS AND METHODS

MKN1 stably-expressing luciferase (MKN1-Luc), N87, KATO III, MKN45 stably-expressing luciferase (MKN45-Luc), NUGC4, and OCUM-1 human GC cell lines were injected intraperitoneally into mice to establish peritoneal metastasis models. MKN45-Luc were injected into subcutaneously implanted spleen, and MKN1-Luc and MKN45-Luc were injected directly into the portal veins of mice for the establishment of hepatic metastasis models.

RESULTS

Peritoneal metastasis was formed after implantation of MKN1-Luc, N87, KATO III, MKN45-Luc, and NUGC4 in nude mice, but not formed in OCUM-1 even in NOD/SCID mice. After intrasplenic injection of MKN45-Luc, we found no hepatic metastasis formation. We identified hepatic metastasis formation after direct injection of MKN45-Luc and MKN1-Luc into the portal veins of NOD/SCID mice.

CONCLUSION

Peritoneal and hepatic metastasis mouse xenograft models were successfully established using several human GC cell lines.

Patient-Derived Cells to Guide Targeted Therapy for Advanced Lung Adenocarcinoma

Adequate preclinical model and model establishment procedure are required to accelerate translational research in lung cancer. We streamlined a protocol for establishing patient-derived cells (PDC) and identified effective targeted therapies and novel resistance mechanisms using PDCs. We generated 23 PDCs from 96 malignant effusions of 77 patients with advanced lung adenocarcinoma. Clinical and experimental factors were reviewed to identify determinants for PDC establishment. PDCs were characterized by driver mutations and in vitro sensitivity to targeted therapies. Seven PDCs were analyzed by whole-exome sequencing. PDCs were established at a success rate of 24.0%. Utilizing cytological diagnosis and tumor colony formation can improve the success rate upto 48.8%. In vitro response to a tyrosine kinase inhibitor (TKI) in PDC reflected patient treatment response and contributed to identifying effective therapies. Combination of dabrafenib and trametinib was potent against a rare BRAF K601E mutation. Afatinib was the most potent EGFR-TKI against uncommon EGFR mutations including L861Q, G719C/S768I, and D770_N771insG. Aurora kinase A (AURKA) was identified as a novel resistance mechanism to olmutinib, a mutant-selective, third-generation EGFR-TKI, and inhibition of AURKA overcame the resistance. We presented an efficient protocol for establishing PDCs. PDCs empowered precision medicine with promising translational values.

B4GALT1 Is a New Candidate to Maintain the Stemness of Lung Cancer Stem Cells

BACKGROUND

According to the cancer stem cells (CSCs) hypothesis, a population of cancer cells with stem cell properties is responsible for tumor propagation, drug resistance, and disease recurrence. Study of the mechanisms responsible for lung CSCs propagation is expected to provide better understanding of cancer biology and new opportunities for therapy.

METHODS

The Lung Adenocarcinoma (LUAD) NCI-H460 cell line was grown either as 2D or as 3D cultures. Transcriptomic and genome-wide chromatin accessibility studies of 2D vs. 3D cultures were carried out using RNA-sequencing and Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq), respectively. Reverse transcription polymerase chain reaction (RT-PCR) was also carried out on RNA extracted from primary cultures derived from malignant pleural effusions to validate RNA-seq results.

RESULTS

RNA-seq and ATAC-seq data disentangled transcriptional and genome accessibility variability of 3D vs. 2D cultures in NCI-H460 cells. The examination of genomic landscape of genes upregulated in 3D vs. 2D cultures led to the identification of 2D cultures led to the identification of Beta-1,4-galactosyltranferase 1 (B4GALT1) as the top candidate. B4GALT1 as the top candidate. B4GALT1 was validated as a stemness factor, since its silencing caused strong inhibition of 3D spheroid formation.

CONCLUSION

Combined transcriptomic and chromatin accessibility study of 3D vs. 2D LUAD cultures led to the identification of B4GALT1 as a new factor involved in the propagation and maintenance of LUAD CSCs.

Stearoyl CoA Desaturase Regulates Ferroptosis in Ovarian Cancer Offering New Therapeutic Perspectives

Better therapies are urgently needed for ovarian cancer, which is associated with an overall median survival of less than 5 years from diagnosis. In this issue of Cancer Research, Tesfay and colleagues show that stearoyl CoA desaturase (SCD1) is expressed at high levels in different isotypes of ovarian cancer and that SCD1 protects ovarian cancer cells from cell death. Pharmaceutical inhibition of SCD1 induces apoptosis and ferroptosis in vitro and in vivo Combination therapies of SCD1 inhibitors and ferroptosis inducers significantly decrease ovarian tumor masses in mice. This novel therapy may prove useful to treat women with ovarian cancer.See related article by Tesfay et al., p. 5355.

CytoMatrix for a reliable and simple characterization of lung cancer stem cells from malignant pleural effusions

Cancer stem cells (CSCs) are a subpopulation with the properties of extensive self‐renewal, capability to generate differentiated cancer cells and resistance to therapies. We have previously shown that malignant pleural effusions (MPEs) from patients with non‐small‐cell lung cancer (NSCLC) represent a valuable source of cancer cells that can be grown as three‐dimensional (3D) spheroids enriched for stem‐like features, which depend on the activation of the Yes‐associated protein‐transcriptional coactivator with PDZ‐binding motif (YAP‐TAZ)/Wnt‐βcatenin/stearoyl‐CoA desaturase 1 (SCD1) axis. Here, we describe a novel support, called CytoMatrix, for the characterization of limited amounts of cancer cells isolated from MPEs of patients with NSCLC. Our results show that this synthetic matrix allows an easy and fast characterization of several epithelial cellular markers. The use of CytoMatrix to study CSCs subpopulation confirms that SCD1 protein expression is enhanced in 3D spheroids when compared with 2D adherent cell cultures. YAP/TAZ nuclear‐cytoplasmic distribution analysed by CytoMatrix in 3D spheroids is highly heterogeneous and faithfully reproduces what is observed in tumour biopsies. Our results confirm and extend the robustness of our workflow for the isolation and phenotypic characterization of primary cancer cells derived from the lung MPEs and underscore the role of SCD1.

Inhibition of Stearoyl-CoA desaturase 1 reverts BRAF and MEK inhibition-induced selection of cancer stem cells in BRAF-mutated melanoma

BACKGROUND

Combination therapy with BRAF and MEK inhibitors significantly improves survival in BRAF mutated melanoma patients but is unable to prevent disease recurrence due to the emergence of drug resistance. Cancer stem cells (CSCs) have been involved in these long-term treatment failures. We previously reported in lung cancer that CSCs maintenance is due to altered lipid metabolism and dependent upon Stearoyl-CoA-desaturase (SCD1)-mediated upregulation of YAP and TAZ. On this ground, we investigated the role of SCD1 in melanoma CSCs.

METHODS

SCD1 gene expression data of melanoma patients were downloaded from TCGA and correlated with disease progression by bioinformatics analysis and confirmed on patient's tissues by qRT-PCR and IHC analyses. The effects of combination of BRAF/MEKi and the SCD1 inhibitor MF-438 were monitored by spheroid-forming and proliferation assays on a panel of BRAF-mutated melanoma cell lines grown in 3D and 2D conditions, respectively. SCD1, YAP/TAZ and stemness markers were evaluated in melanoma cells and tissues by qRT-PCR, WB and Immunofluorescence.

RESULTS

We first observed that SCD1 expression increases during melanoma progression. BRAF-mutated melanoma 3D cultures enriched for CSCs overexpressed SCD1 and were more resistant than 2D differentiated cultures to BRAF and MEK inhibitors. We next showed that exposure of BRAF-mutated melanoma cells to MAPK pathway inhibitors enhanced stemness features by upregulating the expression of YAP/TAZ and downstream genes but surprisingly not SCD1. However, SCD1 pharmacological inhibition was able to downregulate YAP/TAZ and to revert at the same time CSC enrichment and resistance to MAPK inhibitors.

CONCLUSIONS

Our data underscore the role of SCD1 as prognostic marker in melanoma and promote the use of SCD1 inhibitors in combination with MAPK inhibitors for the control of drug resistance.

Lung Cancers: Molecular Characterization, Clonal Heterogeneity and Evolution, and Cancer Stem Cells

Lung cancer causes the largest number of cancer-related deaths in the world. Most (85%) of lung cancers are classified as non-small-cell lung cancer (NSCLC) and small-cell lung cancer (15%) (SCLC). The 5-year survival rate for NSCLC patients remains very low (about 16% at 5 years). The two predominant NSCLC histological phenotypes are adenocarcinoma (ADC) and squamous cell carcinoma (LSQCC). ADCs display several recurrent genetic alterations, including: KRAS, BRAF and EGFR mutations; recurrent mutations and amplifications of several oncogenes, including ERBB2, MET, FGFR1 and FGFR2; fusion oncogenes involving ALK, ROS1, Neuregulin1 (NRG1) and RET. In LSQCC recurrent mutations of TP53, FGFR1, FGFR2, FGFR3, DDR2 and genes of the PI3K pathway have been detected, quantitative gene abnormalities of PTEN and CDKN2A. Developments in the characterization of lung cancer molecular abnormalities provided a strong rationale for new therapeutic options and for understanding the mechanisms of drug resistance. However, the complexity of lung cancer genomes is particularly high, as shown by deep-sequencing studies supporting the heterogeneity of lung tumors at cellular level, with sub-clones exhibiting different combinations of mutations. Molecular studies performed on lung tumors during treatment have shown the phenomenon of clonal evolution, thus supporting the occurrence of a temporal tumor heterogeneity.

Tumor suppressive microRNA-124a inhibits stemness and enhances gefitinib sensitivity of non-small cell lung cancer cells by targeting ubiquitin-specific protease 14

Increasing evidence has shown that microRNAs (miRNAs) play a significant functional role by directly regulating respective targets in cancer stem cell (CSC)-induced non-small cell lung cancer (NSCLC) progression and resistance to therapy. In this study, we found that hsa-miR-124a was downregulated during spheroid formation of the NSCLC cell lines SPC-A1 and NCI-H1650 and NSCLC tissues compared with normal lung cells and tissues. Patients with lower hsa-miR-124a expression had shorter overall survival (OS) and progression free survival (PFS). Moreover, ubiquitin-specific protease 14 (USP14) was confirmed to be a direct target of hsa-miR-124a. Furthermore, concomitant low hsa-miR-124a expression and high USP14 expression were correlated with a shorter median OS and PFS in NSCLC patients. Cellular functional analysis verified that the tumor suppressor hsa-miR-124a negatively regulated cell growth and self-renewal, and promoted apoptosis and gefitinib sensitivity of lung cancer stem cells by suppressing its target gene USP14. Our results provide the first evidence that USP14 is a direct target of hsa-miR-124a, and that hsa-miR-124a inhibits stemness and enhances the gefitinib sensitivity of NSCLC cells by targeting USP14. Thus, hsa-miR-124a and USP14 may be useful as tumor biomarkers for the diagnosis and treatment of NSCLC.

Ferritin heavy chain is a negative regulator of ovarian cancer stem cell expansion and epithelial to mesenchymal transition

Objectives

Ferritin is the major intracellular iron storage protein essential for maintaining the cellular redox status. In recent years ferritin heavy chain (FHC) has been shown to be involved also in the control of cancer cell growth. Analysis of public microarray databases in ovarian cancer revealed a correlation between low FHC expression levels and shorter survival. To better understand the role of FHC in cancer, we have silenced the FHC gene in SKOV3 cells.

Results

FHC-KO significantly enhanced cell viability and induced a more aggressive behaviour. FHC-silenced cells showed increased ability to form 3D spheroids and enhanced expression of NANOG, OCT4, ALDH and Vimentin. These features were accompanied by augmented expression of SCD1, a major lipid metabolism enzyme. FHC apparently orchestrates part of these changes by regulating a network of miRNAs.

Methods

FHC-silenced and control shScr SKOV3 cells were monitored for changes in proliferation, migration, ability to propagate as 3D spheroids and for the expression of stem cell and epithelial-to-mesenchymal-transition (EMT) markers. The expression of three miRNAs relevant to spheroid formation or EMT was assessed by q-PCR.

Conclusions

In this paper we uncover a new function of FHC in the control of cancer stem cells.

Establishing and Maintaining an Extensive Library of Patient-Derived Xenograft Models

Patient-derived xenograft (PDX) models have recently emerged as a highly desirable platform in oncology and are expected to substantially broaden the way in vivo studies are designed and executed and to reshape drug discovery programs. However, acquisition of patient-derived samples, and propagation, annotation and distribution of PDXs are complex processes that require a high degree of coordination among clinic, surgery and laboratory personnel, and are fraught with challenges that are administrative, procedural and technical. Here, we examine in detail the major aspects of this complex process and relate our experience in establishing a PDX Core Laboratory within a large academic institution.

Metabolic features of cancer stem cells: the emerging role of lipid metabolism

Cancer stem cells (CSCs) are an uncommon subset of tumor cells capable of self-renewal, differentiating, and recreating the parental tumor when transplanted into the murine background. Over the past two decades, efforts toward understanding CSC biology culminated into identifying a set of signaling pathways sustaining "stemness". Nevertheless, while metabolic rewiring is nowadays considered a hallmark of cancer, no consensus has been reached on the metabolic features underlying the plastic nature of CSCs, which are capable of residing in a dormant state, and able to rapidly proliferate when the need to repopulate the tumor mass arises. An emerging concept in the field of CSC metabolism is that these cells are extremely reliant on the activity of enzymes involved in lipid metabolism, such as stearoyl-CoA desaturase 1 (SCD1) and 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR). Indeed, SCD1 and HMG-CoAR have been described as key factors for the correct function of a number of concatenated pathways involved in CSC fate decision, such as Hippo and Wnt. In the present review, we describe metabolic futures of CSCs with a special focus on lipid metabolism, which until now represents an underappreciated force in maintaining CSCs and an attractive therapeutic target.

Synergistic antitumor activity of histone deacetylase inhibitors and anti-ErbB3 antibody in NSCLC primary cultures via modulation of ErbB receptors expression

ErbB3, a member of the ErbB family receptors, has a key role in the development and progression of several cancers, including non-small cell lung cancer (NSCLC), and in the establishment of resistance to therapies, leading to the development of anti-ErbB3 therapies.

In this study we demonstrated, in a set of malignant pleural effusion-derived cultures of NSCLC, the synergistic antitumor effect of a histone deacetylase inhibitor (HDACi), such as vorinostat or valproic acid (VPA), in combination with the anti-ErbB3 monoclonal antibody (MoAb) A3. Synergistic interaction was observed in 2D and in 3D cultures conditions, both in fully epithelial cells expressing all ErbB receptors, and in cells that had undergone epithelial to mesenchymal transition and expressed low levels of ErbB3. We provided evidences suggesting that differential modulation of ErbB receptors by vorinostat or VPA, also at low doses corresponding to plasma levels easily reached in treated patients, is responsible for the observed synergism. In details, we showed in epithelial cells that both vorinostat and VPA induced time- and dose-dependent down-regulation of all three ErbB receptors and of downstream signaling. On the contrary, in A3-resistant mesenchymal cells, we observed time- and dose-dependent increase of mRNA and protein levels as well as surface expression of ErbB3, paralleled by down-regulation of EGFR and ErbB2. Our results suggest that the combination of a HDACi plus an anti-ErbB3 MoAb represents a viable strategy that warrants further evaluation for the treatment of NSCLC patients.

Genetic profiling of putative breast cancer stem cells from malignant pleural effusions

A common symptom during late stage breast cancer disease is pleural effusion, which is related to poor prognosis. Malignant cells can be detected in pleural effusions indicating metastatic spread from the primary tumor site. Pleural effusions have been shown to be a useful source for studying metastasis and for isolating cells with putative cancer stem cell (CSC) properties. For the present study, pleural effusion aspirates from 17 metastatic breast cancer patients were processed to propagate CSCs in vitro. Patient-derived aspirates were cultured under sphere forming conditions and isolated primary cultures were further sorted for cancer stem cell subpopulations ALDH1⁺ and CD44⁺CD24^-/low. Additionally, sphere forming efficiency of CSC and non-CSC subpopulations was determined. In order to genetically characterize the different tumor subpopulations, DNA was isolated from pleural effusions before and after cell sorting, and compared with corresponding DNA copy number profiles from primary tumors or bone metastasis using low-coverage whole genome sequencing (SCNA-seq). In general, unsorted cells had a higher potential to form spheres when compared to CSC subpopulations. In most cases, cell sorting did not yield sufficient cells for copy number analysis. A total of five from nine analyzed unsorted pleura samples (55%) showed aberrant copy number profiles similar to the respective primary tumor. However, most sorted subpopulations showed a balanced profile indicating an insufficient amount of tumor cells and low sensitivity of the sequencing method. Finally, we were able to establish a long term cell culture from one pleural effusion sample, which was characterized in detail. In conclusion, we confirm that pleural effusions are a suitable source for enrichment of putative CSC. However, sequencing based molecular characterization is impeded due to insufficient sensitivity along with a high number of normal contaminating cells, which are masking genetic alterations of rare cancer (stem) cells.

NOTCH1 Signaling Regulates Self-Renewal and Platinum Chemoresistance of Cancer Stem-like Cells in Human Non-Small Cell Lung Cancer

Cancer stem-like cells (CSC) are thought to drive tumor initiation, metastasis, relapse, and therapeutic resistance, but their specific pathogenic characters in many cancers, including non-small cell lung cancer (NSCLC), have yet to be well defined. Here, we develop findings that the growth factor HGF promotes CSC sphere formation in NSCLC cell populations. In patient-derived sphere-forming assays (PD-SFA) with HGF, CD49f and CD104 were defined as novel markers of lung CSC (LCSC). In particular, we isolated a subpopulation of CD166⁺CD49f^hiCD104^-Lin^- LCSC present in all human specimens of NSCLC examined, regardless of their histologic subtypes or genetic driver mutations. This specific cell population was tumorigenic and capable of self-renewal, giving rise to tumor spheres in vitro and orthotopic lung tumors in immune-compromised mice. Mechanistic investigations established that NOTCH1 was preferentially expressed in this cell subpopulation and required for self-renewal via the transcription factor HES1. Through a distinct HES1-independent pathway, NOTCH1 also protected LCSCs from cisplatin-induced cell death. Notably, treatment with a γ-secretase inhibitor that blunts NOTCH1 function ablated self-renewing LCSC activity and restored platinum sensitivity in vitro and in vivo Overall, our results define the pathogenic characters of a cancer stem-like subpopulation in lung cancer, the targeting of which may relieve platinum resistance in this disease. Cancer Res; 77(11); 3082-91. ©2017 AACR.

Stearoyl-CoA-desaturase 1 regulates lung cancer stemness via stabilization and nuclear localization of YAP/TAZ

Recent evidences suggest that stearoyl-CoA-desaturase 1 (SCD1), the enzyme involved in monounsaturated fatty acids synthesis, has a role in several cancers. We previously demonstrated that SCD1 is important in lung cancer stem cells survival and propagation. In this article, we first show, using primary cell cultures from human lung adenocarcinoma, that the effectors of the Hippo pathway, Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are required for the generation of lung cancer three-dimensional cultures and that SCD1 knock down and pharmacological inhibition both decrease expression, nuclear localization and transcriptional activity of YAP and TAZ. Regulation of YAP/TAZ by SCD1 is at least in part dependent upon β-catenin pathway activity, as YAP/TAZ downregulation induced by SCD1 blockade can be rescued by the addition of exogenous wnt3a ligand. In addition, SCD1 activation of nuclear YAP/TAZ requires inactivation of the β-catenin destruction complex. In line with the in vitro findings, immunohistochemistry analysis of lung adenocarcinoma samples showed that expression levels of SCD1 co-vary with those of β-catenin and YAP/TAZ. Mining available gene expression data sets allowed to observe that high co-expression levels of SCD1, β-catenin, YAP/TAZ and downstream targets have a strong negative prognostic value in lung adenocarcinoma. Finally, bioinformatics analyses directed to identify which gene combinations had synergistic effects on clinical outcome in lung cancer showed that poor survival is associated with high co-expression of SCD1, β-catenin and the YAP/TAZ downstream target birc5. In summary, our data demonstrate for the first time the involvement of SCD1 in the regulation of the Hippo pathway in lung cancer, and point to fatty acids metabolism as a key regulator of lung cancer stem cells.

The Akt1/IL-6/STAT3 pathway regulates growth of lung tumor initiating cells

Here we report that the PI3K/Akt1/IL-6/STAT3 signalling pathway regulates generation and stem cell-like properties of Non-Small Cell Lung Cancer (NSCLC) tumor initiating cells (TICs). Mutant Akt1, mutant PIK3CA or PTEN loss enhances formation of lung cancer spheroids (LCS), self-renewal, expression of stemness markers and tumorigenic potential of human immortalized bronchial cells (BEAS-2B) whereas Akt inhibition suppresses these activities in established (NCI-H460) and primary NSCLC cells. Matched microarray analysis of Akt1-interfered cells and LCSs identified IL-6 as a critical target of Akt signalling in NSCLC TICs. Accordingly, suppression of Akt in NSCLC cells decreases IL-6 levels, phosphorylation of IkK and IkB, NF-kB transcriptional activity, phosphorylation and transcriptional activity of STAT3 whereas active Akt1 up-regulates them. Exposure of LCSs isolated from NSCLC cells to blocking anti-IL-6 mAbs, shRNA to IL-6 receptor or to STAT3 markedly reduces the capability to generate LCSs, to self-renew and to form tumors, whereas administration of IL-6 to Akt-interfered cells restores the capability to generate LCSs. Finally, immunohistochemical studies in NSCLC patients demonstrated a positive correlative trend between activated Akt, IL-6 expression and STAT3 phosphorylation (n = 94; p < 0.05). In conclusion, our data indicate that aberrant Akt signalling contributes to maintaining stemness in lung cancer TICs through a NF-kB/IL-6/STAT3 pathway and provide novel potential therapeutic targets for eliminating these malignant cells in NSCLC.

Suspension survival mediated by PP2A-STAT3-Col XVII determines tumour initiation and metastasis in cancer stem cells

Targeting tumour-initiating cells (TICs) would lead to new therapies to cure cancer. We previously demonstrated that TICs have the capacity to survive under suspension conditions, while other cells undergo anoikis. Here we show that TICs exhibit increased phosphorylation levels of S727STAT3 because of PP2A inactivation. Collagen 17 gene expression is upregulated in a STAT3-dependent manner, which also stabilizes laminin 5 and engages cells to form hemidesmosome-like junctions in response. Blocking the PP2A-S727STAT3-collagen 17 pathway inhibits the suspension survival of TICs and their ability to form tumours in mice, while activation of the same pathway increases the suspension survival and tumour-initiation capacities of bulk cancer cells. The S727STAT3 phosphorylation levels correlate with collagen 17 expression in colon tumour samples, and correlate inversely with survival. Finally, this signalling axis enhances the ability of TIC to form tumours in mouse models of malignant lung cancer pleural effusion and spontaneous colon cancer metastasis.

Neurotrophin signaling in cancer stem cells

Cancer stem cells (CSCs), are thought to be at the origin of tumor development and resistance to therapies. Thus, a better understanding of the molecular mechanisms involved in the control of CSC stemness is essential to the design of more effective therapies for cancer patients. Cancer cell stemness and the subsequent expansion of CSCs are regulated by micro-environmental signals including neurotrophins. Over the years, the roles of neurotrophins in tumor development have been well established and regularly reviewed. Especially, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are reported to stimulate tumor cell proliferation, survival, migration and/or invasion, and favors tumor angiogenesis. More recently, neurotrophins have been reported to regulate CSCs. This review briefly presents neurotrophins and their receptors, summarizes their roles in different cancers, and discusses the emerging evidence of neurotrophins-induced enrichment of CSCs as well as the involved signaling pathways.

Scaffold-Free Coculture Spheroids of Human Colonic Adenocarcinoma Cells and Normal Colonic Fibroblasts Promote Tumorigenicity in Nude Mice

The aim of this study was to form a scaffold-free coculture spheroid model of colonic adenocarcinoma cells (CACs) and normal colonic fibroblasts (NCFs) and to use the spheroids to investigate the role of NCFs in the tumorigenicity of CACs in nude mice. We analysed three-dimensional (3D) scaffold-free coculture spheroids of CACs and NCFs. CAC Matrigel invasion assays and tumorigenicity assays in nude mice were performed to examine the effect of NCFs on CAC invasive behaviour and tumorigenicity in 3D spheroids. We investigated the expression pattern of fibroblast activation protein-α (FAP-α) by immunohistochemical staining. CAC monocultures did not form densely-packed 3D spheroids, whereas cocultured CACs and NCFs formed 3D spheroids. The 3D coculture spheroids seeded on a Matrigel extracellular matrix showed higher CAC invasiveness compared to CACs alone or CACs and NCFs in suspension. 3D spheroids injected into nude mice generated more and faster-growing tumors compared to CACs alone or mixed suspensions consisting of CACs and NCFs. FAP-α was expressed in NCFs-CACs cocultures and xenograft tumors, whereas monocultures of NCFs or CACs were negative for FAP-α expression. Our findings provide evidence that the interaction between CACs and NCFs is essential for the tumorigenicity of cancer cells as well as for tumor propagation.

Human lung adenocarcinoma cell cultures derived from malignant pleural effusions as model system to predict patients chemosensitivity

Background

Lung cancer is the leading cause of cancer related deaths and Malignant Pleural Effusion (MPE) is a frequent complication. Current therapies suffer from lack of efficacy in a great percentage of cases, especially when cancer is diagnosed at a late stage. Moreover patients’ responses vary and the outcome is unpredictable. Therefore, the identification of patients who will benefit most of chemotherapy treatment is important for accurate prognostication and better outcome. In this study, using malignant pleural effusions (MPE) from non-small cell lung cancer (NSCLC) patients, we established a collection of patient-derived Adenocarcinoma cultures which were characterized for their sensitivity to chemotherapeutic drugs used in the clinical practice.

Methods

Tumor cells present in MPEs of patients with NSCLC were isolated by density gradient centrifugation, placed in culture and genotyped by next generation sequencing. In a subset of cases patient derived xenografts (PDX) were obtained upon tumor cell inoculation in rag2/IL2 knock-out mice. Isolated primary cultures were characterized and tested for drug sensitivity by in vitro proliferation assays. Additivity, antagonism or synergy for combinatorial treatments were determined by analysis with the Calcusyn software.

Results

We have optimized isolation procedures and culture conditions to expand in vitro primary cultures from Malignant Pleural Effusions (MPEs) of patients affected by lung adenocarcinomas, the most frequent form of non small cell lung cancer. Using this approach we have been able to establish 16 primary cultures from MPEs. Cells were banked at low passages and were characterized for their mutational pattern by next generation sequencing for most common driver mutations in lung cancer. Moreover, amplified cultures were shown to engraft with high efficiency when injected in immunocompromised mice. Cancer cell sensitivity to drugs used in standard chemotherapy regimens was assessed either individually or in combination. Differential chemosensitivity and different mutation profiles were observed which suggests that this isolation method could provide a platform for predicting the efficacy of chemotherapy in the clinical setting. Most importantly for six patients it was possible to establish a correlation between drug response in vitro and response to therapy in the clinic.

Conclusions

Results obtained using primary cultured cells from MPEs underscore the heterogeneity of NSCLC in advanced stage as indicated by drug response and mutation profile. Comparison of data obtained from in vitro assays with patients’ responses to therapy leads to the conclusion that this strategy may provide a potentially useful approach for evaluating individual chemosensitivity profile and tailor the therapy accordingly. Furthermore, combining MPE-derived primary cultures with their genomic testing allows to identify patients eligible to trials with novel targeted agents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0816-x) contains supplementary material, which is available to authorized users.

Vorinostat synergizes with EGFR inhibitors in NSCLC cells by increasing ROS via up-regulation of the major mitochondrial porin VDAC1 and modulation of the c-Myc-NRF2-KEAP1 pathway

In non-small-cell lung cancer (NSCLC) patients, the activation of alternative pathways contributes to the limited efficacy of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib. The present study examines a panel of EGFR wild-type, K-Ras mutated, NSCLC lines, which were all intrinsically resistant to EGFR-TKIs, and demonstrates that the histone deacetylase inhibitor vorinostat can improve the therapeutic efficacy of gefitinib or erlotinib, inducing strong synergistic antiproliferative and pro-apoptotic effects that are paralleled by reactive oxygen species accumulation and by increased DNA damage. By knockdown experiments, we suggested that the up-regulation of voltage-dependent anion-selective channel protein 1 (VDAC1), the major mitochondrial porin of the outer mitochondrial membrane, which was induced by vorinostat and further increased by the combination, could be functionally involved in oxidative stress-dependent apoptosis. Significantly, we also observed the attenuation of the expression of both the enzyme hexokinase1, a negative VDAC1 regulator, and the anti-apoptotic porin VDAC2, only in the combination setting, suggesting convergent mechanisms that enhanced mitochondria-dependent apoptosis by targeting VDAC protein functions. Furthermore, the prosurvival capacities of the cells were also inhibited by the combination treatments, as shown by complete pAKT deactivation, increased GSK3β expression, and c-Myc down-regulation. Finally, we observed that the combination treatment of vorinostat and either of the EGFR-TKIs induced the down-regulation of the c-Myc-regulated nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor and the up-regulation of the NRF2 repressor Kelch-like ECH-associated protein 1 regulator (KEAP1). These two genes are crucial for the redox stress response, often dysfunctional in NSCLC, and involved in EGFR-TKI resistance. Taken together, these results are the first to demonstrate that altering redox homeostasis is a new mechanism underlying the observed synergism between vorinostat and EGFR TKIs in NSCLC.

Oncolytic newcastle disease virus triggers cell death of lung cancer spheroids and is enhanced by pharmacological inhibition of autophagy

Lung cancer stem cells (CSCs) have recently been isolated from lung cancer patient samples and have been reported to be responsible for tumor initiation, treatment resistance and tumor recurrence. We have previously shown that oncolytic Newcastle disease virus (NDV), strain FMW (NDV/FMW) induces apoptosis in drug-resistant lung cancer cells. However, how NDV exerts its oncolytic effect on lung CSCs remains to be investigated. Here we show that NDV/FMW replicates in, and lyses CSC-enriched lung cancer spheroids and inhibits the 3D growth potential of lung cancer spheroid and agar colonies. We demonstrate that NDV/FMW triggers caspase-dependent apoptosis in lung cancer spheroids as shown by increased caspase-3 processing and Poly (ADP-ribose) polymerase (PARP) cleavage. Notably, NDV/FMW infection results in the degradation of microtubule-associated protein 1 light chain 3 (LC3) II and P62, two hallmarks of autophagy maturation, indicating that NDV/FMW promotes autophagy flux in lung cancer cell spheroids. This was further confirmed by the appearance of an increased number of double-membrane vesicles as detected by transmission electron microscopy. We also show that NDV/FMW promotes autophagy degradation in lung cancer spheroids via inhibition of the AKT/mTOR pathway. In addition, treatment of spheroids with the autophagy inhibitor, chloroquine increases NDV/FMW-induced cytotoxicity. Collectively, our data show that oncolytic NDV/FMW may be a potential strategy in targeting lung CSCs.

Review: Cell Dynamics in Malignant Pleural Effusions

Malignant pleural effusions (MPEs) are a common manifestation found in patients with lung cancer. After cytological and histological confirmation of malignancy, talc pleurodesis still remains the treatment of choice in patients with MPEs resistant to chemotherapy. Despite this, primary challenges include reduced quality of life and life expectancy in general. Therefore, a better understanding of the cell biology of MPEs, along with improvements in treatment is greatly needed. It has recently been demonstrated that MPEs may represent an excellent source for identification of molecular mechanisms within the tumor and its environment. The present review summarizes the current understanding of MPEs cells and tumor microenvironment, and particularly focuses on dissecting the cross-talk between MPEs and epithelial to mesenchymal transition (EMT), inflammation and cancer stem cells.

Drug sensitivity profiling and molecular characteristics of cells from pleural effusions of patients with lung adenocarcinoma

We propose to assess the therapeutic value of biomarker-guided individualized chemotherapy in patients with metastasizing lung adenocarcinoma. In this study, we used primary cells from pleural effusions from sixteen patients diagnosed with adenocarcinomas originating in the lung and from four patients with no malignant diagnosis. The ex vivo drug sensitivity of primary cells was assessed for 32 chemotherapeutical drugs. Linear regression analyses were performed to examine possible correlations between the drug sensitivity, overall survival and expression of ERCC1 and RRM1. The ex vivo drug sensitivity profiles of the patients revealed considerable heterogeneity in drug response. Vinblastine, vinorelbine, paclitaxel and actinomycin D showed high efficiency against 50% of the tested primary cells. Significant correlation was detected between the ex vivo sensitivity to platinum based drugs and gemcitabine and the level of ERCC1 and RRM1. No significant correlation was however seen between overall survival and drug sensitivity. The heterogeneity of the drug response suggests that optimal care of the adenocarcinoma patients should include the determination of drug sensitivity of the primary cells and would benefit to use personalized therapy.

Cancer Stem Cells Sensitivity Assay (STELLA) in Patients with Advanced Lung and Colorectal Cancer: A Feasibility Study

Background

Cancer stem cells represent a population of immature tumor cells found in most solid tumors. Their peculiar features make them ideal models for studying drug resistance and sensitivity. In this study, we investigated whether cancer stem cells isolation and in vitro sensitivity assay are feasible in a clinical setting.

Methods

Cancer stem cells were isolated from effusions or fresh cancer tissue of 23 patients who progressed after standard therapy failure. Specific culture conditions selected for immature tumor cells that express markers of stemness. These cells were exposed in vitro to chemotherapeutic and targeted agents.

Results

Cancer stem cells were extracted from liver metastases in 6 cases (25%), lung nodules in 2 (8%), lymph node metastases in 3 (12.5%) and pleural/peritoneal/pericardial effusion in 13 (54%). Cancer stem cells were successfully isolated in 15 patients (63%), including 14 with lung cancer (93.3%). A sensitivity assay was successfully performed in 7 patients (30.4%), with a median of 15 drugs/combinations tested (range 5-28) and a median time required for results of 51 days (range 37-95).

Conclusion

The approach used for the STELLA trial allowed isolation of cancer stem cells in a consistent proportion of patients. The low percentage of cases completing the full procedure and the long median time for obtaining results highlights the need for a more efficient procedure.

Trial Registration

ClinalTrials.gov NCT01483001

Pathophysiologically relevant in vitro tumor models for drug screening

The alarming rate of failure of clinical trials is a major hurdle in cancer therapy that partly results from the inadequate use of in vitro tumor models for the screening of promising hits and leads in preclinical studies. 2D cultures of cancer cell lines that are primarily used for drug screening do not adequately recapitulate tumor microenvironment (TME) complexities compared with 3D cancer cell cultures and tumor-derived primary cell cultures. In this review, we focus on the potential use of in vitro tumor models that reproduce in vivo tumor complexities for effective drug selection in the preclinical stages of drug development.

Lung cancer stem cell lose their stemness default state after exposure to microgravity

Microgravity influences cell differentiation by modifying the morphogenetic field in which stem cells are embedded. Preliminary data showed indeed that stem cells are committed to selective differentiation when exposed to real or simulated microgravity. Our study provides evidence that a similar event occurs when cancer stem cells (CSCs) are cultured in microgravity. In the same time, a significant increase in apoptosis was recorded: those data point out that microgravity rescues CSCs from their relative quiescent state, inducing CSCs to lose their stemness features, as documented by the decrease in ALDH and the downregulation of both Nanog and Oct-4 genes. Those traits were stably acquired and preserved by CSCs when cells were placed again on a 1 g field. Studies conducted in microgravity on CSCs may improve our understanding of the fundamental role exerted by biophysical forces in cancer cell growth and function.

Combination therapy with anti-ErbB3 monoclonal antibodies and EGFR TKIs potently inhibits non-small cell lung cancer

Personalized therapy of advanced non-small cell lung cancer (NSCLC) has been improved by the introduction of EGFR tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib. EGFR TKIs induce dramatic objective responses and increase survival in patients bearing sensitizing mutations in the EGFR intracytoplasmic tyrosine kinase domain. However, virtually all patients develop resistance, and this is responsible for disease relapse. Hence several efforts are being undertaken to understand the mechanisms of resistance in order to develop combination treatments capable to sensitize resistant cells to EGFR TKIs. Recent studies have suggested that upregulation of another member of the EGFR receptor family, namely ErbB3 is involved in drug resistance, through increased phosphorylation of its intracytoplasmic domain and activation of PI3K/AKT signaling. In this paper we first show, by using a set of malignant pleural effusion derived cell cultures (MPEDCC) from patients with lung adenocarcinoma, that surface ErbB3 expression correlates with increased AKT phosphorylation. Antibodies against ErbB3, namely A3, which we previously demonstrated to induce receptor internalization and degradation, inhibit growth and induce apoptosis only in cells overexpressing surface ErbB3. Furthermore, combination of anti-ErbB3 antibodies with EGFR TKIs synergistically affect cell proliferation in vitro, cause cell cycle arrest, up-regulate p21 expression and inhibit tumor growth in mouse xenografts. Importantly, potentiation of gefitinib by anti-ErbB3 antibodies occurs both in de novo and in ab initio resistant cells. Anti-ErbB3 mAbs strongly synergize also with the dual EGFR and HER2 inhibitor lapatinib. Our results suggest that combination treatment with EGFR TKI and antibodies against ErbB3 should be a promising approach to pursue in the clinic.

Identification of a population of epidermal squamous cell carcinoma cells with enhanced potential for tumor formation

Epidermal squamous cell carcinoma is among the most common cancers in humans. These tumors are comprised of phenotypically diverse populations of cells that display varying potential for proliferation and differentiation. An important goal is identifying cells from this population that drive tumor formation. To enrich for tumor-forming cells, cancer cells were grown as spheroids in non-attached conditions. We show that spheroid-selected cells form faster growing and larger tumors in immune-compromised mice as compared to non-selected cells. Moreover, spheroid-selected cells gave rise to tumors following injection of as few as one hundred cells, suggesting these cells have enhanced tumor-forming potential. Cells isolated from spheroid-selected tumors retain an enhanced ability to grow as spheroids when grown in non-attached culture conditions. Thus, these tumor-forming cells retain their phenotype following in vivo passage as tumors. Detailed analysis reveals that spheroid-selected cultures are highly enriched for expression of epidermal stem cell and embryonic stem cell markers, including aldehyde dehydrogenase 1, keratin 15, CD200, keratin 19, Oct4, Bmi-1, Ezh2 and trimethylated histone H3. These studies indicate that a subpopulation of cells that possess stem cell-like properties and express stem cell markers can be derived from human epidermal cancer cells and that these cells display enhanced ability to drive tumor formation.

Stearoyl-CoA desaturase-1 is a key factor for lung cancer-initiating cells

In recent years, studies of cancer development and recurrence have been influenced by the cancer stem cells (CSCs)/cancer-initiating cells (CICs) hypothesis. According to this, cancer is sustained by highly positioned, chemoresistant cells with extensive capacity of self renewal, which are responsible for disease relapse after chemotherapy. Growth of cancer cells as three-dimensional non-adherent spheroids is regarded as a useful methodology to enrich for cells endowed with CSC-like features. We have recently reported that cell cultures derived from malignant pleural effusions (MPEs) of patients affected by adenocarcinoma of the lung are able to efficiently form spheroids in non-adherent conditions supplemented with growth factors. By expression profiling, we were able to identify a set of genes whose expression is significantly upregulated in lung tumor spheroids versus adherent cultures. One of the most strongly upregulated gene was stearoyl-CoA desaturase (SCD1), the main enzyme responsible for the conversion of saturated into monounsaturated fatty acids. In the present study, we show both by RNA interference and through the use of a small molecule inhibitor that SCD1 is required for lung cancer spheroids propagation both in stable cell lines and in MPE-derived primary tumor cultures. Morphological examination and image analysis of the tumor spheroids formed in the presence of SCD1 inhibitors showed a different pattern of growth characterized by irregular cell aggregates. Electron microscopy revealed that the treated spheroids displayed several features of cellular damage and immunofluorescence analysis on optical serial sections showed apoptotic cells positive for the M30 marker, most of them positive also for the stemness marker ALDH1A1, thus suggesting that the SCD1 inhibitor is selectively killing cells with stem-like properties. Furthermore, SCD1-inhibited lung cancer cells were strongly impaired in their in vivo tumorigenicity and ALDH1A1 expression. These results suggest that SCD1 is a critical target in lung cancer tumor-initiating cells.

EMT markers in lung adenocarcinoma pleural effusion spheroid cells

Epithelial-to-mesenchymal transition (EMT) is a process in which cells undergo a developmental switch from epithelial to mesenchymal phenotype. This process has been related to embryologic morphogenesis but also to cancer progression and metastasis. The aim of the current study was to investigate the expression of EMT-related markers in adherent and spheroid cell cultures derived from malignant pleural effusions (MPEs) of patients affected by lung adenocarcinoma. On the basis of efficient in vitro propagation, six cases of MPEs were selected and analyzed by immunocytochemistry staining for EMT markers and by RT-PCR for transcription factors known to orchestrate EMT. EMT markers immunostaining showed in spheroids a statistically significant correlation between the loss of E-cadherin immunoreactivity and overexpression of N-cadherin (P < 0.001). Likewise loss of EpCAM epithelial marker was coincident with Vimentin overexpression (P < 0.001). RT-PCR analysis of transcription factors Snail, Slug, and Twist showed a highly variable expression, although a general trend to increase was observed. Importantly, in some selected cases it was possible to establish a precise relationship between spheroid formation, EMT switch and increased upregulation of the marker related to cancer stemness such as ALDH positivity. Therefore, MPE-derived cell cultures, while recapitulating the heterogeneity of lung cancer, are a suitable system to study the mechanisms at the basis of EMT and to understand its relationship with the generation of cancer stem cells.

TrkB is responsible for EMT transition in malignant pleural effusions derived cultures from adenocarcinoma of the lung

Lung cancer is the leading cause of cancer-related mortality worldwide. Recent evidence indicates that tumors contain a subpopulation of cancer stem cells (CSCs) that are responsible for tumor maintenance and spread. CSCs have recently been linked to the occurrence of epithelial-to-mesenchymal transition (EMT). Neurotrophins (NTs) are growth factors that regulate the biology of embryonic stem cells and cancer cells, but still little is known about the role NTs in the progression of lung cancer. In this work, we investigated the role of the NTs and their receptors using as a study system primary cell cultures derived from malignant pleural effusions (MPEs) of patients with adenocarcinoma of the lung. We assessed the expression of NTs and their receptors in MPE-derived adherent cultures vs. spheroids enriched in CSC markers. We observed in spheroids a selectively enhanced expression of TrkB, both at the mRNA and protein levels. Both K252a, a known inhibitor of Trk activity, and a siRNA against TrkB strongly affected spheroid morphology, induced anoikis and decreased spheroid forming efficiency. Treatment with neurotrophins reversed the inhibitory effect of K252a. Importantly, TrkB inhibition caused loss of vimentin expression as well as that of a set of transcription factors known to be linked to EMT. These ex vivo results nicely correlated with an inverse relationship between TrkB and E-cadherin expression measured by immunohistochemistry in a panel of lung adenocarcinoma samples. We conclude that TrkB is involved in full acquisition of EMT in lung cancer, and that its inhibition results in a less aggressive phenotype.