The malignant pleural effusion as a model to investigate intratumoral heterogeneity in lung cancer

Spheroids Generated from Malignant Pleural Effusion as a Tool to Predict the Response of Non-Small Cell Lung Cancer to Treatment

BACKGROUND

Spheroids generated by tumor cells collected from malignant pleural effusion (MPE) were shown to retain the characteristics of the original tumors. This ex vivo model might be used to predict the response of non-small cell lung cancer (NSCLC) to anticancer treatments.

METHODS

The characteristics, epidermal growth factor receptor (EGFR) mutation status, and clinical response to EGFR-TKIs treatment of enrolled patients were recorded. The viability of the spheroids generated from MPE of enrolled patients were evaluated by visualization of the formazan product of the MTT assay.

RESULTS

Spheroids were generated from 14 patients with NSCLC-related MPE. Patients with EGFR L861Q, L858R, or Exon 19 deletion all received EGFR-TKIs, and five of these seven patients responded to treatment. The viability of the spheroids generated from MPE of these five patients who responded to EGFR-TKIs treatment was significantly reduced after gefitinib treatment. On the other hand, gefitinib treatment did not reduce the viability of the spheroids generated from MPE of patients with EGFR wild type, Exon 20 insertion, or patients with sensitive EGFR mutation but did not respond to EGFR-TKIs treatment.

CONCLUSION

Multicellular spheroids generated from NSCLC-related MPE might be used to predict the response of NSCLC to treatment.

Exploratory pilot study to characterize the immune landscapes of malignant pleural effusions and their corresponding primary tumors from patients with breast carcinoma and lung adenocarcinoma

INTRODUCTION

Malignant pleural effusion (MPE) is a frequent complication of advanced malignancies. In this pilot study, we characterized the immune landscapes of MPEs, compared them to their primary tumor (PT) samples from breast carcinoma (BC) and lung adenocarcinoma (LADC), and tested the utility of multiplexed image technology in cytological samples.

MATERIALS AND METHODS

We evaluated the immune contexture of 6 BC and 5 LADC MPEs and their PTs using 3 multiplex immunofluorescence panels. We explored the associations between sample characteristics and pleural effusion-free survival.

RESULTS

No MPE samples had positive programmed death-ligand 1 expression in malignant cells, although 3 of 11 PTs has positive programmed death-ligand 1 expression (more than 1% expression in malignant cells). Overall, in LADC samples, cluster of differentiation 3 (CD3)+ T cells and CD3+CD8+ cytotoxic T cells predominated (median percentages for MPEs versus PTs: 45.6% versus 40.7% and 4.7% versus 6.6%, respectively) compared with BC. CD68+ macrophages predominated in the BC samples (medians for MPEs 61.2% versus PTs for 57.1%) but not in the LADC samples. Generally in PTs, CD3+CD8+ forkhead box P3+ T cells and the median distances from the malignant cells to CD3+CD8+Ki67+ and CD3+ programmed cell death protein 1 + T cells correlated to earlier MPE after PT diagnosis.

CONCLUSIONS

The immune cell phenotypes in the MPEs and PTs were similar within each cancer type but different between BC versus LADC. An MPE analysis can potentially be used as a substitute for a PT analysis, but an expanded study of this topic is essential.

Efficacy of hyperthermic intrathoracic chemotherapy for initially diagnosed lung cancer with symptomatic malignant pleural effusion

Initially diagnosed malignant pleural effusion (MPE) has different systematic treatments, and defining the best drainage regimen according to the responsiveness of MPE to different systematic treatments is important. This study compared the efficacy of hyperthermic intrathoracic chemotherapy (HITHOC) and pleural catheter drainage (IPCD) for initially diagnosed lung cancer with symptomatic MPE. We retrospectively reviewed the medical records of initially diagnosed lung cancer patients with symptomatic MPE between January 2018 and May 2022. The patients were treated with IPCD or HITHOC for local control of MPE after diagnosis. Systematic regimens were conducted during 1 month according to guidelines after local treatment. Intrathoracic MPE progression-free survival (iPFS) and overall survival (OS) were calculated, Univariate and multivariable Cox-regression were used to identify factors associated with iPFS and OS. A total of 33 patients were evaluated; 10 (30.3%) patients received IPCD, and 23 (69.7%) patients received HITHOC. No difference in the MPE control rate at 1 month was found between the IPCD group (90%) and HITHOC group (95.7%). However, this control rate was significantly higher in the HITHOC group (69.6%) than in the IPCD group (30%) at 3 months (P = 0.035). Multivariate analysis showed that receiving tyrosine kinase inhibitors (TKIs) or chemotherapy was a significant protective factor for iPFS (HR = 0.376, 95% CI 0.214-0.659, P = 0.007) and OS (HR = 0.321, 95% CI 0.174-0.594, P < 0.001). According to subgroup analysis, among patients treated with TKIs, those who received HITHOC had longer iPFS and OS than those who received IPCD (P = 0.011 and P = 0.002, respectively), but this difference was not found in the palliative care subgroup. Moreover, no patients treated with chemotherapy showed reaccumulation of MPE. Systematic TKIs or chemotherapy prolonged iPFS and OS for those initially diagnosed with lung cancer with symptomatic MPE. HITHOC prolonged iPFS and OS for those treated with systematic TKIs.

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.

Cellular plasticity and immune microenvironment of malignant pleural effusion are associated with EGFR-TKI resistance in non–small-cell lung carcinoma

Malignant pleural effusion (MPE) is a complication of lung cancer that can be used as an alternative method for tissue sampling because it is generally simple and minimally invasive. Our study evaluated the diagnostic potential of non–small-cell lung carcinoma (NSCLC)-associated MPE in terms of understanding tumor heterogeneity and identifying response factors for EGFR tyrosine kinase inhibitor (TKI) therapy. We performed a single-cell RNA sequencing analysis of 31,743 cells isolated from the MPEs of 9 patients with NSCLC (5 resistant and 4 sensitive to EGFR TKI) with EGFR mutations. Interestingly, lung epithelial precursor-like cells with upregulated GNB2L1 and CAV1 expression were enriched in the EGFR TKI-resistant group. Moreover, GZMK upregulated transitional effector T cells, and plasmacytoid dendritic cells were significantly enriched in the EGFR TKI-resistant patients. Our results suggest that cellular plasticity and immunosuppressive microenvironment in MPEs are potentially associated with the TKI response of patients with EGFR-mutated NSCLC.

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ScRNA-seq reveals associations between cellular plasticity and EGFR-TKI response

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Lung epithelial progenitor-like cells are abundant in the TKI-resistant group

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HLA-II gene expression are upregulated in the epithelial cells of TKI-sensitive group

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Immunosuppressive TME was associated with the TKI resistance in NSCLC

Microtechnology-enabled filtration-based liquid biopsy: challenges and practical considerations

Liquid biopsy, an important enabling technology for early diagnosis and dynamic monitoring of cancer, has drawn extensive attention in the past decade. With the rapid developments of microtechnology, it has been possible to manipulate cells at the single-cell level, which dramatically improves the liquid biopsy capability. As the microtechnology-enabled liquid biopsy matures from proof-of-concept demonstrations towards practical applications, a main challenge it is facing now is to process clinical samples which are usually of a large volume while containing very rare targeted cells in complex backgrounds. Therefore, a high-throughput liquid biopsy which is capable of processing liquid samples with a large volume in a reasonable time along with a high recovery rate of rare targeted cells from complex clinical liquids is in high demand. Moreover, the purity, viability and release feasibility of recovered targeted cells are the other three key impact factors requiring careful considerations. To date, among the developed techniques, micropore-type filtration has been acknowledged as the most promising solution to address the aforementioned challenges in practical applications. However, the presently reported studies about micropore-type filtration are mostly based on trial and error for device designs aiming at different cancer types, which requires lots of efforts. Therefore, there is an urgent need to investigate and elaborate the fundamental theories of micropore-type filtration and key features that influence the working performances in the liquid biopsy of real clinical samples to promote the application efficacy in practical applications. In this review, the state of the art of microtechnology-enabled filtration is systematically and comprehensively summarized. Four key features of the filtration, including throughput, purity, viability and release feasibility of the captured targeted cells, are elaborated to provide the guidelines for filter designs. The recent progress in the filtration mode modulation and sample standardization to improve the filtration performance of real clinical samples is also discussed. Finally, this review concludes with prospective views for future developments of filtration-based liquid biopsy to promote its application efficacy in clinical practice.

Multidisciplinary approaches to the management of malignant pleural effusions: a guide for the clinician

INTRODUCTION

Malignant pleural effusion (MPE) is a complication of advanced cancer, associated with significant mortality and morbidity. This entity is commonly treated by respiratory physicians, oncologists, and thoracic surgeons. There have been various randomized clinical trials assessing the relative merits of chest drain pleurodesis, indwelling pleural catheters, treatment of septated MPEs, the use of thoracoscopy and pleurodesis and pleurodesis through IPCs in the past decade which have addressed some key areas in the management of MPEs, with an increasing focus on patient related outcome.

AREAS COVERED

In this review, we examine and review the literature for management strategies for MPEs and discuss future directions. A detailed search of scientific literature and clinical trial registries published in the past two decades was undertaken.

EXPERT OPINION

Tremendous progress has been made in management of MPE in the past decade and current strategy involves patient preference along with local expertise that is available.

In vitro cell culture of patient derived malignant pleural and peritoneal effusions for personalised drug screening

Background

Malignant serous effusion (MSE) denotes a manifestation of metastatic disease with typical high concentrations of both cancer and immune cells, making them an ideal resource for in vitro cytologic studies. Hence, the aim of the study was to investigate the features of 2D and 3D MSE culture systems as well as their feasibilities for in vitro drug screening.

Methods

Pleural and peritoneal effusions from 8 patients were collected and processed for 2D monolayer and 3D hanging drop cell culture into GravityPLUS™ plates. Representative markers for cell components, proliferation rate and tumour classification were investigated by immunohistochemistry, followed by absolute quantification using a digitalised image analysis approach. Further, we implemented another 3D cell culture model based on a low attachment method for in vitro drug sensitivity testing of carboplatin, pemetrexed and pembrolizumab for 5 patients.

Results

Monolayer cell culture was favourable for the growth of mesothelial cells, while hanging drop culture in GravityPLUS™ plates showed better ability for preserving cancer cells, inducing positive diagnostic markers expression and restraining the growth of mesothelial cells. For in vitro drug testing, MSE from five patients presented various drug sensitivities, and one case showed strong response to PD-1 checkpoint inhibition (pembrolizumab). For some patients, the application of combinatorial drugs had better therapeutic responses compared to monotherapy.

Conclusions

Digitalised quantification of data offers a better understanding of different MSE culture models. More importantly, the proposed platforms are practical and amenable for performing in vitro chemo-/immunotherapeutic drug testing by using routine cytologic MSE in a personalised manner. Next to cell blocks, our work demonstrates the prognostic and predictive value of cytologic effusion samples.

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.

Increased Cytokeratin 19 Fragment Levels Are Positively Correlated with Adenosine Deaminase Activity in Malignant Pleural Effusions from Adenocarcinomas

Adenosine deaminase (ADA) and cytokeratin 19 (CK19) are known pleural biomarkers. Although ADA in humans functions mainly in the immune system, it also appears to be associated with the differentiation of epithelial cells. Keratin filaments are important structural stabilizers of epithelial cells and potent biomarkers in epithelial differentiation. This study aimed to investigate the simultaneous presence of the ADA enzyme and CK19 fragments to assess epithelial differentiation in malignant and benign pleural fluids. Diagnosis of the cause of pleural effusion syndrome was confirmed by means of standard examinations and appropriate surgical procedures. An ADA assay, in which ADA irreversibly catalyzes the conversion of adenosine into inosine, was performed using a commercial kit. The CK19 assay was performed using a CYFRA 21-1 kit, developed to detect quantitative soluble fragments of CK19 using an electrochemiluminescence immunoassay. One hundred nineteen pleural fluid samples were collected from untreated individuals with pleural effusion syndrome due to several causes. ADA levels only correlated with CK19 fragments in adenocarcinomas, with high significance and good correlation (rho = 0.5145, P = 0.0036). However, further studies are required to understand this strong association on epithelial differentiation in metastatic pleural fluids from adenocarcinomas.

Mutant KRAS promotes malignant pleural effusion formation

Malignant pleural effusion (MPE) is the lethal consequence of various human cancers metastatic to the pleural cavity. However, the mechanisms responsible for the development of MPE are still obscure. Here we show that mutant KRAS is important for MPE induction in mice. Pleural disseminated, mutant KRAS bearing tumour cells upregulate and systemically release chemokine ligand 2 (CCL2) into the bloodstream to mobilize myeloid cells from the host bone marrow to the pleural space via the spleen. These cells promote MPE formation, as indicated by splenectomy and splenocyte restoration experiments. In addition, KRAS mutations are frequently detected in human MPE and cell lines isolated thereof, but are often lost during automated analyses, as indicated by manual versus automated examination of Sanger sequencing traces. Finally, the novel KRAS inhibitor deltarasin and a monoclonal antibody directed against CCL2 are equally effective against an experimental mouse model of MPE, a result that holds promise for future efficient therapies against the human condition.

Malignant pleural effusion: from bench to bedside

Malignant pleural effusion (MPE) is a common but serious condition that is related with poor quality of life, morbidity and mortality. Its incidence and associated healthcare costs are rising and its management remains palliative, with median survival ranging from 3 to 12 months. During the last decade there has been significant progress in unravelling the pathophysiology of MPE, as well as its diagnostics, imaging, and management. Nowadays, formerly bed-ridden patients are genotyped, phenotyped, and treated on an ambulatory basis. This article attempts to provide a comprehensive overview of current advances in MPE from bench to bedside. In addition, it highlights unanswered questions in current clinical practice and suggests future directions for basic and clinical research in the field.

Culture and Drug Profiling of Patient Derived Malignant Pleural Effusions for Personalized Cancer Medicine

INTRODUCTION

The use of patients' own cancer cells for in vitro selection of the most promising treatment is an attractive concept in personalized medicine. Human carcinoma cells from malignant pleural effusions (MPEs) are suited for this purpose since they have already adapted to the liquid environment in the patient and do not depend on a stromal cell compartment. Aim of this study was to develop a systematic approach for the in-vitro culture of MPEs to analyze the effect of chemotherapeutic as well as targeted drugs.

METHODS

MPEs from patients with solid tumors were selected for this study. After morphological and molecular characterization, they were cultured in medium supplemented with patient-derived sterile-filtered effusion supernatant. Growth characteristics were monitored in real-time using the xCELLigence system. MPEs were treated with a targeted therapeutic (erlotinib) according to the mutational status or chemotherapeutics based on the recommendation of the oncologists.

RESULTS

We have established a robust system for the ex-vivo culture of MPEs and the application of drug tests in-vitro. The use of an antibody based magnetic cell separation system for epithelial cells before culture allowed treatment of effusions with only moderate tumor cell proportion. Experiments using drugs and drug-combinations revealed dose-dependent and specific growth inhibitory effects of targeted drugs.

CONCLUSIONS

We developed a new approach for the ex-vivo culture of MPEs and the application of drug tests in-vitro using real-time measuring of cell growth, which precisely reproduced the effect of clinically established treatments by standard chemotherapy and targeted drugs. This sets the stage for future studies testing agents against specific targets from genomic profiling of metastatic tumor cells and multiple drug-combinations in a personalized manner.

Lung cancer stem cells-characteristics, phenotype

Lung cancer remains a major cause of cancer-related deaths worldwide with unfavourable prognosis mainly due to the late stage of disease at presentation. High incidence and disease recurrence rates are a fact despite advances in treatment. Ongoing experimental and clinical observations suggest that the malignant phenotype in lung cancer is sustained by lung cancer stem cells (CSCs) which are putative stem cells situated throughout the airways that have the potential of initiating lung cancer formation. These cells share the common characteristic of increased proliferation and differentiation, long life span and resistance to chemotherapy and radiation therapy. This review summarises the current knowledge on their characteristics and phenotype.

Liposome encapsulated curcumin-difluorinated (CDF) inhibits the growth of cisplatin resistant head and neck cancer stem cells

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer, with 600,000 new cases every year worldwide. Although chemotherapeutics exist, five-year survival is only 50%. New strategies to overcome drug resistance are required to improve HNSCC treatment. Curcumin-difluorinated (CDF), a synthetic analog of curcumin, was packaged in liposomes and used to evaluate growth inhibition of cisplatin resistant HNSCC cell lines CCL-23R and UM-SCC-1R generated from the parental cell lines CCL-23 and UM-SCC-1 respectively. Growth inhibition in vitro and expression levels of the CD44 (cancer stem cell marker), cytokines, and growth factors were investigated after liposomal CDF treatment. The in vivo growth inhibitory effect of liposomal CDF was evaluated in the nude mice xenograft tumor model of UM-SCC-1R and the inhibition of CD44 was measured. Treatment of the resistant cell lines in vitro with liposomal CDF resulted in a statistically significant growth inhibition (p < 0.05). The nude mice xenograft study showed a statistically significant tumor growth inhibition of UM-SCC-1R cells and a reduction in the expression of CD44 (p < 0.05), indicating an inhibitory effect of liposomal CDF on CSCs. Our results demonstrate that delivery of CDF through liposomes may be an effective method for the treatment of cisplatin resistant HNSCC.

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.

CD163+ tumor-associated macrophage is a prognostic biomarker and is associated with therapeutic effect on malignant pleural effusion of lung cancer patients

CD163+ tumor-associated macrophages (TAMs) play an important role in the progression of cancer. However, the significance of CD163+ TAMs in malignant pleural effusion (MPE) is still unclear. The aim of this study is to evaluate the prognostic value of CD163+ TAMs in MPE, and the regulatory effect of an immune adjuvant (pseudomonas aeruginosa - mannose-sensitive hemagglutinin, PA-MSHA, which is used for MPE treatment in clinic) on CD163+ TAMs in MPE. Here, we found that the percentage of CD163+ TAMs in MPE was significantly higher than that in non-malignant pleural effusion (P<0.001). More importantly, CD163+ TAMs in MPE patients were an independent prognostic factor for progression-free survival. M2-related cytokines were highly expressed in MPE-derived CD163+ TAMs than in MPE-derived CD163− macrophages (P<0.05). CD163+ TAMs frequency in MPE patients was obviously reduced after PA-MSHA treatment in clinic (P<0.05). After treatment with PA-MSHA, M2 macrophages were re-educated to M1 macrophages in vitro. TLR4 blocking antibody inhibited M2 macrophages polarization to M1 macrophages induced by PA-MSHA. These findings highlight that accumulation of CD163+ TAMs in MPE caused by lung cancer is closely correlated with poor prognosis. CD163+ TAMs are associated with therapeutic effect in MPE. PA-MSHA re-educates CD163+ TAMs to M1 macrophages through TLR4-mediated pathway in MPE.

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.

The Presence of EpCAM(-)/CD49f(+) Cells in Breast Cancer Is Associated with a Poor Clinical Outcome

Purpose

It is well established that breast cancer stem cells (BCSCs) play an essential role in tumor invasion for both local and distant metastasis. The aim of this study was to establish whether BCSCs could act as a prognostic and clinical marker.

Methods

We analyzed tumor tissues from 161 breast cancer patients. Dual immunohistochemistry and immunofluorescence were performed on all the slides, and we analyzed the relationship between EpCAM^-/CD49f⁺ tumor cells and key clinical and prognostic factors.

Results

Univariate survival analysis using the Kaplan-Meier method showed that the presence of EpCAM^-/CD49f⁺ tumor cells in breast cancer was significantly associated with shorter disease-free survival (DFS) and overall survival (OS). Multivariate analysis showed that the presence of EpCAM^-/CD49f⁺ cells was associated with shorter DFS (p=0.010; hazard ratio [HR], 2.070) and OS (p=0.002; HR, 3.235). Tumors containing EpCAM^-/CD49f⁺ cells were also more likely to metastasize after initial surgery (p=0.048).

Conclusion

Our study suggests that breast tumors containing EpCAM^-/CD49f⁺ cells are more likely to undergo distant metastasis after initial surgery and are associated with a shorter DFS and OS.

DUSP1 expression induced by HDAC1 inhibition mediates gefitinib sensitivity in non-small cell lung cancers

PURPOSE

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death worldwide. Patients with NSCLC with EGFR-activating mutation benefit greatly by gefitinib, an EGFR tyrosine kinase inhibitor. However, acquired resistance limits its clinical use. Histone deacetylases (HDAC) are oncoproteins associated with cancer progression and drug resistance. Here, we disclosed that inhibition of HDAC1 induced protein phosphatase DUSP1 upregulation to overcome gefitinib-acquired resistance.

EXPERIMENTAL DESIGN

The effect of HDAC1 inhibition restored gefitinib sensitivity was assessed by in vitro MTT and apoptotic assays, and in vivo xenograft and orthotopic lung cancer mouse models. Protein phosphatase array was used to detect DUSP1 expression. Immunohistochemical staining and quantitative PCR were used to analyze DUSP1 expression in clinical NSCLC specimens.

RESULTS

Gefitinib-resistant NSCLC cells showed HDAC1 overexpression, and its knockdown sensitized resistant cells to gefitinib in vitro and in preclinical models through DUSP1 expression. Overexpression of DUSP1 in resistant cells restored gefitinib sensitivity by inhibiting EGFR signaling and inducing apoptosis, whereas its knockdown in sensitive cells conferred gefitinib resistance. A novel HDAC inhibitor, WJ-26210-2, in combination with gefitinib upregulated DUSP1 expression to exert in vitro and in vivo synergistic effect on inactivation of EGFR signaling, growth inhibition, and apoptosis. Clinically, high DUSP1 level was correlated with delayed emergence of gefitinib-acquired resistance.

CONCLUSIONS

Decreased DUSP1 might be a mechanism responsible for gefitinib resistance, and DUSP1 might be a biomarker for gefitinib efficacy. HDAC1 inhibition-induced DUSP1 upregulation could be a promising strategy to overcome gefitinib-acquired resistance. Clin Cancer Res; 21(2); 428-38. ©2015 AACR.

CD163+CD14+ macrophages, a potential immune biomarker for malignant pleural effusion

BACKGROUND

Malignant pleural effusion (MPE) is a common complication caused by malignant diseases. However, subjectivity, poor sensitivity, and substantial false-negative rates of cytology assay hamper accurate MPE diagnosis. The aim of this study was to assess whether CD163+CD14+ tumor-associated macrophages (TAMs) could be used as a biomarker for enabling sensitive and specific MPE diagnosis.

METHODS

Pleural effusion samples and peripheral blood samples were collected from 50 MPE patients and 50 non-malignant pleural effusion (NMPE) patients, respectively. Flow cytometry was performed to analyze cell phenotypes, and RT-qPCR was used to detect cytokine expression in these monocytes and macrophages. A blinded validation study (n = 40) was subsequently performed to confirm the significance of CD163+CD14+ TAMs in MPE diagnosis. Student's t test, rank sum test, and receiver operating characteristic curve analysis were used for statistical analysis.

RESULTS

Notably, CD163+CD14+ cell frequency in MPE was remarkably higher than that in NMPE (P < 0.001). In a blinded validation study, a sensitivity of 78.9 % and a specificity of 100 % were obtained with CD163+CD14+ TAMs as a MPE biomarker. In total (n = 140), by using a cutoff level of 3.65 %, CD163+CD14+ cells had a sensitivity of 81.2 % and a specificity of 100 % for MPE diagnosis. Notably, MPE diagnosis by estimating CD163+CD14+ cells in pleural effusion could be obtained one week earlier than that obtained by cytological examination.

CONCLUSIONS

CD163+CD14+ macrophages could be potentially used as an immune diagnostic marker for MPE and has better assay sensitivity than that of cytological analysis.

Lung cancer coexisting with ipsilateral pleural effusion

SUMMARY 

Invasion beyond the elastic layer of the visceral pleura and/or diffuse pleural metastatic spread affects negatively survival in lung cancer. Presence of pleural effusion is also associated with poor prognosis, and image techniques can be of great help for diagnosis. When pleural fluid cytology is negative, thoracoscopy is advisable before attempting tumor resection, in order to detect unsuspected pleural metastases. If widespread pleural malignancy is confirmed, chemical pleurodesis using graded talc (with particles larger than 20 µm in diameter) is the best option, unless the lung is unable to re-expand. In this case, or when a previous pleurodesis has failed, or there is a short life expectancy, placement of a indwelling pleural catheter is the treatment of choice.

The expression of aldehyde dehydrogenase family in breast cancer

Purpose

It is widely accepted that aldehyde dehydrogenase (ALDH) activity is a signature of breast cancer stem cells, and high activity has been reported to be associated with poor clinical outcome. The aim of this study was to assess the expression of members of the ALDH family of isozymes in breast cancer tissues and to evaluate the implications of the results.

Methods

We analyzed paraffin-embedded tumor tissue from 160 patients with breast cancer. Immunohistochemistry (IHC) staining was performed on the slides using antibodies against different ALDH family members. We collated the IHC results with patient clinical characteristics and determined their prognostic value. In addition, we analyzed normal, hyperplastic, and carcinomatous tissues in situ to check their ALDH distributions.

Results

All the tested ALDH members were detected in the various tissue types, but at different levels. Only ALDH 1A3 was found to be significantly associated with distant metastasis (p=0.001), disease-free survival (p<0.001), and overall survival (p<0.001).

Conclusion

The level of ALDH 1A3 in breast cancer tissue is a predictive marker of a poor clinical outcome.

Utilization of liquid chromatography mass spectrometry analyses to identify LKB1-APC interaction in modulating Wnt/β-catenin pathway of lung cancer cells

STK11/LKB1, a serine/threonine protein kinase and tumor suppressor, is a key upstream kinase of adenine monophosphate-activated protein kinase, which is a kinase involved in controlling cell polarity and maintaining cellular energy homeostasis. LKB1 is mutated in a significant number of Peutz-Jeghers syndrome (PJS) cases and sporadic cancers, and is most frequently mutated in lung adenocarcinomas; however, little is known about how LKB1 is involved in lung cancer progression. In this study, immunoprecipitation-HPLC tandem mass spectrometry (IP-LC-MS/MS) was performed to identify novel proteins interacting with LKB1 in lung cancer. Interestingly, many LKB1-interacting proteins acquired from the LC-MS/MS approach were mapped, using MetaCore pathway analysis, to the cystic fibrosis transmembrane conductance regulator activation pathway. Moreover, it was determined that LKB1 directly interacts with APC, and this LKB1-APC interaction was further confirmed by reverse immunoprecipitation assays, but GSK3β was dispensable for the association of LKB1 and APC. Importantly, LKB1 binds to APC to suppress the Wnt/β-catenin signaling pathway, which is known to be involved in cell proliferation and migration. Subsequent analysis of the downstream targets of the Wnt/TCF pathway led to the identification of several Wnt-regulated genes, such as CD44, COX-2, survivin, and c-Myc, whose expression levels are downregulated by LKB1. In summary, these results demonstrate that LKB1 regulates the Wnt pathway through a direct interaction with APC to suppress the tumorigenic/metastatic potential of lung tumors.

IMPLICATIONS

LKB1 status influences the molecular circuitry (Wnt/β-catenin pathway), cellular biology, and may serve as a potential therapeutic node in genetically defined subsets of lung cancer.

Small molecule antagonist of the bone morphogenetic protein type I receptors suppresses growth and expression of Id1 and Id3 in lung cancer cells expressing Oct4 or nestin

Background

Bone morphogenetic proteins (BMP) are embryonic morphogens that are aberrantly expressed in lung cancer. BMPs mediate cell fate decisions and self-renewal of stem cells, through transcription regulation of inhibitor of differentiation protein/DNA binding proteins (Id1-3). Inhibition of BMP signaling decreases growth and induces cell death of lung cancer cells lines by downregulating the expression of Id proteins. It is not known whether the BMP signaling cascade regulates growth and the expression of Id proteins of lung cancer cells expressing the stem cell markers Oct4 and/or nestin.

Methods

Lung cancer cells expressing Oct4 or nestin were isolated from lung cancer cell lines by stably transfecting the Oct4 promoter or nestin promoter expression vectors that induce expression of the green fluorescent protein reporter.

Results

Our studies suggest that lung cancer cells expressing Oct4 or nestin are different cell populations. Microarray and quantitative RT-PCR demonstrated that the expression of specific stem cell markers were different between isolated Oct4 and nestin cells. Both the Oct4 and nestin populations were more tumorigenic than controls but histologically they were quite different. The isolated Oct4 and nestin cells also responded differently to inhibition of BMP signaling. Blockade of BMP signaling with the BMP receptor antagonist DMH2 caused significant growth inhibition of both the Oct4 and nestin cell populations but only increased cell death in the nestin population. DMH2 also induced the expression of nestin in the Oct4 population but not in the nestin cells. We also show that BMP signaling is an important regulator of Id1 and Id3 in both the Oct4 and nestin cell populations. Furthermore, we show that NeuN is frequently expressed in NSCLC and provide evidence suggesting that Oct4 cells give rise to cancer cells expressing nestin and/or NeuN.

Conclusion

These studies show that although biologically different, BMP signaling is growth promoting in cancer cells expressing Oct4 or nestin. Inhibition of BMP signaling decreases expression of Id proteins and suppresses growth of cancer cells expressing Oct4 or Nestin. Small molecule antagonists of the BMP type I receptors represent potential novel drugs to target the population of cancer cells expressing stem cell markers.

The CD44(high) tumorigenic subsets in lung cancer biospecimens are enriched for low miR-34a expression

Cellular heterogeneity is an integral part of cancer development and progression. Progression can be associated with emergence of cells that exhibit high phenotypic plasticity (including “de-differentiation” to primitive developmental states), and aggressive behavioral properties (including high tumorigenic potentials). We observed that many biomarkers that are used to identify Cancer Stem Cells (CSC) can label cell subsets in an advanced clinical stage of lung cancer (malignant pleural effusions, or MPE). Thus, CSC-biomarkers may be useful for live sorting functionally distinct cell subsets from individual tumors, which may enable investigators to hone in on the molecular basis for functional heterogeneity. We demonstrate that the CD44^hi (CD44-high) cancer cell subsets display higher clonal, colony forming potential than CD44^lo cells (n = 3) and are also tumorigenic (n = 2/2) when transplanted in mouse xenograft model. The CD44^hi subsets express different levels of embryonal (de-differentiation) markers or chromatin regulators. In archived lung cancer tissues, ALDH markers co-localize more with CD44 in squamous cell carcinoma (n = 5/7) than Adeno Carcinoma (n = 1/12). MPE cancer cells and a lung cancer cell line (NCI-H-2122) exhibit chromosomal abnormalities and 1p36 deletion (n = 3/3). Since miR-34a maps to the 1p36 deletion site, low miR-34a expression levels were detected in these cells. The colony forming efficiency of CD44^hi cells, characteristic property of CSC, can be inhibited by mir-34a replacement in these samples. In addition the highly tumorigenic CD44^hi cells are enriched for cells in the G2 phase of cell cycle.

Genetic alterations defining NSCLC subtypes and their therapeutic implications

Lung cancer is the leading cause of cancer death worldwide, accounting for more deaths than breast, prostate and colon cancer combined. While treatment decisions are determined primarily by stage, therapeutically non small cell lung cancer (NSCLC) has traditionally been treated as a single disease. However, recent findings have led to the recognition of histology and molecular subtypes as important determinants in treatment selection. Identifying the genetic differences that define these molecular and histological subtypes has the potential to impact treatment and as such is currently the focus of much research. Microarray and genomic sequencing efforts have provided unparalleled insight into the genomes of lung cancer subtypes, specifically adenocarcinoma (AC) and squamous cell carcinoma (SqCC), revealing subtype specific genomic alterations and molecular subtypes as well as differences in cell signaling pathways. In this review, we discuss the recurrent genomic alterations characteristic of AC and SqCC (including molecular subtypes), their therapeutic implications and emerging clinical practices aimed at tailoring treatments based on a tumor's molecular alterations with the hope of improving patient response and survival.

Combined gemcitabine and CHK1 inhibitor treatment induces apoptosis resistance in cancer stem cell-like cells enriched with tumor spheroids from a non-small cell lung cancer cell line

Evaluating the effects of novel drugs on appropriate tumor models has become crucial for developing more effective therapies that target highly tumorigenic and drug-resistant cancer stem cell (CSC) populations. In this study, we demonstrate that a subset of cancer cells with CSC properties may be enriched into tumor spheroids under stem cell conditions from a non-small cell lung cancer cell line. Treating these CSC-like cells with gemcitabine alone and a combination of gemcitabine and the novel CHK1 inhibitor PF-00477736 revealed that PF-00477736 enhances the anti-proliferative effect of gemcitabine against both the parental and the CSC-like cell populations. However, the CSC-like cells exhibited resistance to gemcitabine-induced apoptosis. Collectively, the spheroid-forming CSC-like cells may serve as a model system for understanding the mechanism underlying the drug resistance of CSCs and for guiding the development of better therapies that can inhibit tumor growth and eradicate CSCs.

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.

Pulmonary Adenocarcinoma in Malignant Pleural Effusion Enriches Cancer Stem Cell Properties during Metastatic Cascade

BACKGROUND

Metastasis occurs in a series of discrete steps involving invasion, angiogenesis, lymphovascular space permeation, and establishment of secondary tumors. Malignant pleural effusion (MPE), a type of tumor metastasis, is usually a poor prognostic sign for patients with pulmonary adenocarcinoma, although its underlying mechanism has received less attention than other types of metastases have. The objective of the current study was to confirm whether cancer stem cells (CSCs) in MPE contribute to the "metastatic cascade" through the epithelial - mesenchymal transition (EMT), anoikis, and adaptation in the microenvironment.

METHODS

Pulmonary tissue and corresponding cell blocks of MPE samples from 20 patients with primary adenocarcinoma were analyzed by immunohistochemical staining with CSC-representative markers (CD133, Nanog, and OCT-4) and EMT-associated markers (E-cadherin and vimentin). Correlations between these variables and clinico-pathological parameters were analyzed. Primary cultures from eight cases of MPE were investigated to characterize the CSC properties, including marker expression, sphere formation, and differentiation.

RESULTS

Expressions of CSC-representative markers for 20 cases of MPE cell blocks were quite diverse and variable ranging from 15% to 90%. Stronger expression of CSC-representative markers and alteration of EMT-associated markers were found at the invasive fronts and in MPEs compared with the expression in primary pulmonary tumor tissues. The expression of OCT-4 in MPEs significantly related to distant metastasis and stage, as well as inversely correlated with patient survival. Primary cultures confirmed the CSC properties in MPE. Five of eight cases of MPE yielded adequate cell clusters, which also showed variable expressions of CSC markers in addition to sphere formation and the ability for differentiation and metastasis.

CONCLUSION

This pilot study offers a better understanding of the metastatic cascade. Establishing a model of MPE will provide further insight into the role of CSCs in metastasis and may explain the high therapeutic failure rates for patients with MPE.

Prognostic value of cancer stem cells, epithelial-mesenchymal transition and circulating tumor cells in lung cancer

The epithelial-mesenchymal transition (EMT) is a program involved in embryonic development that is often activated during cancer invasion and metastasis. CD133 is the main marker identifying cancer stem cells (CSCs) in lung cancer. Circulating tumor cells (CTCs) are demonstrated to be useful as a biomarker for the diagnosis and treatment of cancer. The aim of this study was to correlate EMT, CSCs and CTCs with patient prognosis to verify whether they can contribute to better stratification of lung cancer patients at risk for recurrent and metastatic disease. Pulmonary venous blood was drawn after major pulmonary surgery in 45 patients with resectable non-small cell lung cancer (NSCLC) in order to identify CTCs. For the same patients, we also constructed prognostic lung tissue microarrays (TMA) for CD133 and c-kit and evaluated CSC and EMT markers using flow cytometry. Cytokeratin-positive cells were detectable in 11 (23.9%) cases. c-kit expression was heterogeneous in prognostic TMAs while CD133 expression was low or absent which was also confirmed by flow cytometry and RT-PCR. Flow cytometric analysis showed that the mean percentage of cells with CD133 expression was 1.6%. CD90 and CD326 markers were co-expressed with a mean percentage of 10.41%. When CD133 and CD90/CD326 expression was correlated with follow-up, CD133 showed a higher correlation with deceased patients when compared with CD90/CD326 co-expression (32.5 vs. 9.5%). CD133 expression demonstrated a strong significant association with patients exhibiting progressive disease when compared to CD90/CD326 expression (15 vs. 7.1%). CD133 may be significantly associated with invasion and metastatic spread of NSCLC. The co-expression of CD90, CD326 and CD133 has definite prognostic value in patients with NSCLC.

Cancer stem cells, microRNAs, and therapeutic strategies including natural products

Embryonic stem cells divide continuously and differentiate into organs through the expression of specific transcription factors at specific time periods. Differentiated adult stem cells on the other hand remain in quiescent state and divide by receiving cues from the environment (extracellular matrix or niche), as in the case of wound healing from tissue injury or inflammation. Similarly, it is believed that cancer stem cells (CSCs), forming a smaller fraction of the tumor bulk, also remain in a quiescent state. These cells are capable of initiating and propagating neoplastic growth upon receiving environmental cues, such as overexpression of growth factors, cytokines, and chemokines. Candidate CSCs express distinct biomarkers that can be utilized for their identification and isolation. This review focuses on the known and candidate cancer stem cell markers identified in various solid tumors and the promising future of disease management and therapy targeted at these markers. The review also provides details on the differential expression of microRNAs (miRNAs), and the miRNA- and natural product-based therapies that could be applied for the treatment of cancer stem cells.

Malignant pleural effusion: tumor-host interactions unleashed

Malignant pleural effusion (MPE) poses a significant clinical problem. Current nonetiologic management is suboptimal in terms of efficacy and safety. In light of recent research progress, we propose herein a new view of MPE development, which may rapidly translate into meaningful changes in therapeutics. In addition to tumor-induced impairment of pleural fluid drainage, pertinent findings point toward another pathway to MPE formation: a vicious loop of interactions between pleural-based tumor cells and the host vasculature and immune system that results in increased net fluid production via enhanced plasma extravasation into the pleural space. The ability of tumor cells to trigger this cascade likely rests on a specific and distinct transcriptional repertoire, which results in important vasoactive events in the pleural space. Although the characterization of tumor-derived factors responsible for MPE development is in the making, an additional, indirect path to MPE was recently demonstrated: tumor cells recruit and co-opt host cells and mediators, which, in turn, amplify tumor cell-primed fluid leakage and impact tumor cell functions. Importantly, recent evidence suggests that the biologic events that culminate in clinical MPE are likely amenable to therapeutic inhibition and even prevention. In this perspective, the scientific basis for an update of current concepts of MPE formation is highlighted. Key questions for future research are posed. Finally, a vision for novel, effective, safe, and convenient treatment modalities that can be offered to outpatients with MPE is set forth.

ALDH-positive lung cancer stem cells confer resistance to epidermal growth factor receptor tyrosine kinase inhibitors

Molecular targeting therapeutics, such as EGFR tyrosine kinase inhibitors (TKIs), are important treatment strategies for lung cancer. Currently, the major challenge confronting targeted cancer therapies is the development of resistance. Cancer stem cells (CSCs) represent a rare population of undifferentiated tumorigenic cells responsible for tumor initiation, maintenance and spreading. Resistance to conventional chemotherapeutic drugs is a common characteristic of CSCs. However, the issue of whether CSCs contribute to EGFR TKI resistance in lung cancer is yet to be established. In the current study, we explored the association of ALDH1A1 expression with EGFR TKI resistance in lung cancer stem cells. ALDH1A1-positive lung cancer cells displayed resistance to gefitinib, compared to ALDH1A1-negative lung cancer cells. Moreover, PC9/gef cells (gefitinib-resistant lung cancer cells) presented a higher proportion of ALDH1A1-positive cells, compared to PC9 cells (gefitinib-sensitive lung cancer cells). Clinical sample studies were consistent with results from cell culture model systems showing that lung cancer cells with resistance to EGFR TKI and chemotherapy drugs contain significantly increased proportions of ALDH1A1-positive cells. These findings collectively suggest that ALDH1A1 positivity in cancer stem cells confers resistance to EGFR TKI in lung cancer.

A minimal connected network of transcription factors regulated in human tumors and its application to the quest for universal cancer biomarkers

A universal cancer biomarker candidate for diagnosis is supposed to distinguish, within a broad range of tumors, between healthy and diseased patients. Recently published studies have explored the universal usefulness of some biomarkers in human tumors. In this study, we present an integrative approach to search for potential common cancer biomarkers. Using the TFactS web-tool with a catalogue of experimentally established gene regulations, we could predict transcription factors (TFs) regulated in 305 different human cancer cell lines covering a large panel of tumor types. We also identified chromosomal regions having significant copy number variation (CNV) in these cell lines. Within the scope of TFactS catalogue, 88 TFs whose activity status were explained by their gene expressions and CNVs were identified. Their minimal connected network (MCN) of protein-protein interactions forms a significant module within the human curated TF proteome. Functional analysis of the proteins included in this MCN revealed enrichment in cancer pathways as well as inflammation. The ten most central proteins in MCN are TFs that trans-regulate 157 known genes encoding secreted and transmembrane proteins. In publicly available collections of gene expression data from 8,525 patient tissues, 86 genes were differentially regulated in cancer compared to inflammatory diseases and controls. From TCGA cancer gene expression data sets, 50 genes were significantly associated to patient survival in at least one tumor type. Enrichment analysis shows that these genes mechanistically interact in common cancer pathways. Among these cancer biomarker candidates, TFRC, MET and VEGFA are commonly amplified genes in tumors and their encoded proteins stained positive in more than 80% of malignancies from public databases. They are linked to angiogenesis and hypoxia, which are common in cancer. They could be interesting for further investigations in cancer diagnostic strategies.

Salinomycin can effectively kill ALDH(high) stem-like cells on gastric cancer

Salinomycin is a novel identified cancer stem cells (CSCs) killer. Higher ALDH activity represents CSCs characterization. Here, we screened ALDH activities on several gastric cancer cell lines and divided them into ALDH(high) and ALDH(low) gastric cancer groups. ALDH(high) cancer cells (NCI-N87 and SNU-1) disclosed more CSCs characteristics, such as higher levels of Sox2, Nanog and Nestin, more floating spheroid bodies, more colony formation and more resistance to conventional chemotherapeutic drugs 5-Fu and CDDP, compared to these parameters observed in ALDH(low) cancer cells (P<0.01). Importantly, ALDH(high) cancer cells are relatively sensitive to salinomycin when compared to ALDH(low) cancer cells (P<0.01). Our results confirmed ALDH as functional marker of CSCs population on gastric cancer. Salinomycin might be selective therapy for CSCs fraction, which is resistant to conventional anticancer drugs 5-Fu and CDDP.

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

Malignant pleural effusions (MPEs) could represent an excellent source to culture a wide variety of cancer cells from different donors. In this study, we set up culture conditions for cancer cells deriving from MPEs of several patients affected by the most frequent form of lung cancer, namely the subset of non small cell lung cancers (NSCLC) classified as Lung Adenocarcinomas (AdenoCa) which account for approximately 40% of lung cancer cases. AdenoCa malignant pleural effusions gave rise to in vitro cultures both in adherent and/or in spheroid conditions in almost all cases analyzed. We characterized in greater detail two samples which showed the most efficient propagation in vitro. In these samples we also compared gene profiles of spheroid vs adherent cultures and identified a set of differentially expressed genes. Finally we achieved efficient tumor engraftment in recipient NOD/SCID mice, also upon inoculation of small number of cells, thus suggesting indirectly the presence of tumor initiating cells.

Non-small cell lung cancer cells expressing CD44 are enriched for stem cell-like properties

BACKGROUND

The cancer stem cell theory hypothesizes that cancers are perpetuated by cancer stem cells (CSC) or tumor initiating cells (TIC) possessing self-renewal and other stem cell-like properties while differentiated non-stem/initiating cells have a finite life span. To investigate whether the hypothesis is applicable to lung cancer, identification of lung CSC and demonstration of these capacities is essential.

METHODOLOGY/PRINCIPAL FINDING

The expression profiles of five stem cell markers (CD34, CD44, CD133, BMI1 and OCT4) were screened by flow cytometry in 10 lung cancer cell lines. CD44 was further investigated by testing for in vitro and in vivo tumorigenecity. Formation of spheroid bodies and in vivo tumor initiation ability were demonstrated in CD44(+) cells of 4 cell lines. Serial in vivo tumor transplantability in nude mice was demonstrated using H1299 cell line. The primary xenografts initiated from CD44(+) cells consisted of mixed CD44(+) and CD44(-) cells in similar ratio as the parental H1299 cell line, supporting in vivo differentiation. Semi-quantitative Real-Time PCR (RT-PCR) showed that both freshly sorted CD44(+) and CD44(+) cells derived from CD44(+)-initiated tumors expressed the pluripotency genes OCT4/POU5F1, NANOG, SOX2. These stemness markers were not expressed by CD44(-) cells. Furthermore, freshly sorted CD44(+) cells were more resistant to cisplatin treatment with lower apoptosis levels than CD44(-) cells. Immunohistochemical analysis of 141 resected non-small cell lung cancers showed tumor cell expression of CD44 in 50.4% of tumors while no CD34, and CD133 expression was observed in tumor cells. CD44 expression was associated with squamous cell carcinoma but unexpectedly, a longer survival was observed in CD44-expressing adenocarcinomas.

CONCLUSION/SIGNIFICANCE

Overall, our results demonstrated that stem cell-like properties are enriched in CD44-expressing subpopulations of some lung cancer cell lines. Further investigation is required to clarify the role of CD44 in tumor cell renewal and cancer propagation in the in vivo environment.

Slug confers resistance to the epidermal growth factor receptor tyrosine kinase inhibitor

RATIONALE

Non-small cell lung cancers carrying epidermal growth factor receptor (EGFR) mutations respond well to EGFR tyrosine kinase inhibitors (TKIs), but patients ultimately develop drug resistance and relapse. Although epithelial-mesenchymal transition (EMT) can predict resistance to EGFR TKIs, the molecular mechanisms are still unknown.

OBJECTIVES

To examine the role of EMT regulators in resistance to gefitinib.

METHODS

The expression level of EMT regulators in gefitinib-sensitive cells (PC9) and gefitinib-resistant cells (PC9/gef) was determined using quantitative real-time reverse transcription-polymerase chain reaction and Western blot analysis. Molecular manipulations (silencing or overexpression) were performed to investigate the effects of EMT regulators on gefitinib resistance in vitro, and a xenograft mouse model was used for in vivo confirmation. In addition, cancer cells from 44 patients with malignant pleural effusions of lung adenocarcinoma were collected for analysis of EMT regulator mRNA by quantitative real-time reverse transcription-polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Slug expression, but not that of snail, twist, or zeb-1, was significantly increased in PC9/gef compared with PC9 cells. Slug knockdown in PC9/gef cells reversed resistance to gefitinib, and overexpression of Slug in PC9 cells protected cells from gefitinib-induced apoptosis. Silencing of Slug in gefitinib-resistant cells restored gefitinib-induced apoptosis primarily through Bim up-regulation and activation of caspase-9. Slug enhanced tumor growth in a xenograft mouse model, even with gefitinib treatment. In clinical samples, Slug expression was significantly higher in cancer cells with resistance to EGFR TKIs than in treatment-naive cancer cells.

CONCLUSIONS

Slug contributes to the resistance to gefitinib and may be a potential therapeutic target for treating resistance to EGFR TKIs.