Establishment of lung cancer patient-derived xenograft models and primary cell lines for lung cancer study

PPIA dictates NRF2 stability to promote lung cancer progression

Nuclear factor erythroid 2-related factor 2 (NRF2) hyperactivation has been established as an oncogenic driver in a variety of human cancers, including non-small cell lung cancer (NSCLC). However, despite massive efforts, no specific therapy is currently available to target NRF2 hyperactivation. Here, we identify peptidylprolyl isomerase A (PPIA) is required for NRF2 protein stability. Ablation of PPIA promotes NRF2 protein degradation and blocks NRF2-driven growth in NSCLC cells. Mechanistically, PPIA physically binds to NRF2 and blocks the access of ubiquitin/Kelch Like ECH Associated Protein 1 (KEAP1) to NRF2, thus preventing ubiquitin-mediated degradation. Our X-ray co-crystal structure reveals that PPIA directly interacts with a NRF2 interdomain linker via a trans-proline 174-harboring hydrophobic sequence. We further demonstrate that an FDA-approved drug, cyclosporin A (CsA), impairs the interaction of NRF2 with PPIA, inducing NRF2 ubiquitination and degradation. Interestingly, CsA interrupts glutamine metabolism mediated by the NRF2/KLF5/SLC1A5 pathway, consequently suppressing the growth of NRF2-hyperactivated NSCLC cells. CsA and a glutaminase inhibitor combination therapy significantly retard tumor progression in NSCLC patient-derived xenograft (PDX) models with NRF2 hyperactivation. Our study demonstrates that targeting NRF2 protein stability is an actionable therapeutic approach to treat NRF2-hyperactivated NSCLC.

Representation of genomic intratumor heterogeneity in multi-region non-small cell lung cancer patient-derived xenograft models

Patient-derived xenograft (PDX) models are widely used in cancer research. To investigate the genomic fidelity of non-small cell lung cancer PDX models, we established 48 PDX models from 22 patients enrolled in the TRACERx study. Multi-region tumor sampling increased successful PDX engraftment and most models were histologically similar to their parent tumor. Whole-exome sequencing enabled comparison of tumors and PDX models and we provide an adapted mouse reference genome for improved removal of NOD scid gamma (NSG) mouse-derived reads from sequencing data. PDX model establishment caused a genomic bottleneck, with models often representing a single tumor subclone. While distinct tumor subclones were represented in independent models from the same tumor, individual PDX models did not fully recapitulate intratumor heterogeneity. On-going genomic evolution in mice contributed modestly to the genomic distance between tumors and PDX models. Our study highlights the importance of considering primary tumor heterogeneity when using PDX models and emphasizes the benefit of comprehensive tumor sampling.

Pre-clinical lung squamous cell carcinoma mouse models to identify novel biomarkers and therapeutic interventions

Primary lung carcinoma or lung cancer (LC) is classified into small-cell or non-small-cell (NSCLC) lung carcinoma. Lung squamous cell carcinoma (LSCC) is the second most common subtype of NSCLC responsible for 30% of all LCs, and its survival remains low with only 24% of patients living for five years or longer post-diagnosis primarily due to the advanced stage of tumors at the time of diagnosis. The pathogenesis of LSCC is still poorly understood and has hampered the development of effective diagnostics and therapies. This review highlights the known risk factors, genetic and epigenetic alterations, miRNA biomarkers linked to the development and diagnosis of LSCC and the lack of therapeutic strategies to target specifically LSCC. We will also discuss existing animal models of LSCC including carcinogen induced, transgenic and xenograft mouse models, and their advantages and limitations along with the chemopreventive studies and molecular studies conducted using them. The importance of developing new and improved mouse models will also be discussed that will provide further insights into the initiation and progression of LSCC, and enable the identification of new biomarkers and therapeutic targets.

LCN2 secreted by tissue-infiltrating neutrophils induces the ferroptosis and wasting of adipose and muscle tissues in lung cancer cachexia

BACKGROUND

Cancer cachexia is a deadly wasting syndrome that accompanies various diseases (including ~ 50% of cancers). Clinical studies have established that cachexia is not a nutritional deficiency and is linked to expression of certain proteins (e.g., interleukin-6 and C-reactive protein), but much remains unknown about this often fatal syndrome.

METHODS

First, cachexia was created in experimental mouse models of lung cancer. Samples of human lung cancer were used to identify the association between the serum lipocalin 2 (LCN2) level and cachexia progression. Then, mouse models with LCN2 blockade or LCN2 overexpression were used to ascertain the role of LCN2 upon ferroptosis and cachexia. Furthermore, antibody depletion of tissue-infiltrating neutrophils (TI-Neu), as well as myeloid-specific-knockout of Lcn2, were undertaken to reveal if LCN2 secreted by TI-Neu caused cachexia. Finally, chemical inhibition of ferroptosis was conducted to illustrate the effect of ferroptosis upon tissue wasting.

RESULTS

Protein expression of LCN2 was higher in the wasting adipose tissue and muscle tissues of experimental mouse models of lung cancer cachexia. Moreover, evaluation of lung cancer patients revealed an association between the serum LCN2 level and cachexia progression. Inhibition of LCN2 expression reduced cachexia symptoms significantly and inhibited tissue wasting in vivo. Strikingly, we discovered a significant increase in the number of TI-Neu in wasting tissues, and that these innate immune cells secreted high levels of LCN2. Antibody depletion of TI-Neu, as well as myeloid-specific-knockout of Lcn2, prevented ferroptosis and tissue wasting in experimental models of lung cancer cachexia. Chemical inhibition of ferroptosis alleviated tissue wasting significantly and also prolonged the survival of cachectic mice.

CONCLUSIONS

Our study provides new insights into how LCN2-induced ferroptosis functionally impacts tissue wasting. We identified LCN2 as a potential target in the treatment of cancer cachexia.

Prognostic Ability of Enhancer RNAs in Metastasis of Non-Small Cell Lung Cancer

(1) Background: Non-small cell lung cancer (NSCLC) is the most common lung cancer. Enhancer RNA (eRNA) has potential utility in the diagnosis, prognosis and treatment of cancer, but the role of eRNAs in NSCLC metastasis is not clear; (2) Methods: Differentially expressed transcription factors (DETFs), enhancer RNAs (DEEs), and target genes (DETGs) between primary NSCLC and metastatic NSCLC were identified. Prognostic DEEs (PDEEs) were screened by Cox regression analyses and a predicting model for metastatic NSCLC was constructed. We identified DEE interactions with DETFs, DETGs, reverse phase protein arrays (RPPA) protein chips, immunocytes, and pathways to construct a regulation network using Pearson correlation. Finally, the mechanisms and clinical significance were explained using multi-dimensional validation unambiguously; (3) Results: A total of 255 DEEs were identified, and 24 PDEEs were selected into the multivariate Cox regression model (AUC = 0.699). Additionally, the NSCLC metastasis-specific regulation network was constructed, and six key PDEEs were defined (ANXA8L1, CASTOR2, CYP4B1, GTF2H2C, PSMF1 and TNS4); (4) Conclusions: This study focused on the exploration of the prognostic value of eRNAs in the metastasis of NSCLC. Finally, six eRNAs were identified as potential markers for the prediction of metastasis of NSCLC.

Patient-derived xenograft (PDX) models, applications and challenges in cancer research

The establishing of the first cancer models created a new perspective on the identification and evaluation of new anti-cancer therapies in preclinical studies. Patient-derived xenograft models are created by tumor tissue engraftment. These models accurately represent the biology and heterogeneity of different cancers and recapitulate tumor microenvironment. These features have made it a reliable model along with the development of humanized models. Therefore, they are used in many studies, such as the development of anti-cancer drugs, co-clinical trials, personalized medicine, immunotherapy, and PDX biobanks. This review summarizes patient-derived xenograft models development procedures, drug development applications in various cancers, challenges and limitations.

Establishment and characterization of a novel highly malignant lung cancer cell line ZX2021H derived from a metastatic lymph node lesion

Background

Lung cancer is a highly malignant tumor with a poor prognosis. The establishment of faithful ex vivo cell models is essential for investigating the metastatic mechanisms and developing new anticancer agents. In this study, we established and characterized a novel lung cancer cell line derived from metastatic lymph node tissue from a Chinese patient.

Methods

A primary culture of metastatic lymph node tissue from a patient with lung cancer was used to establish a cell line. The phenotypic characteristics of the cell line were characterized by colony‐formation, CCK8, and Transwell assays, and xenografting. The genetic characteristics were evaluated by chromosome analysis, short tandem repeat (STR) profiling, and quantitative real time‐polymerase chain reaction (qRT‐PCR).

Results

A novel lung cancer cell line, named ZX2021H, was successfully established from a metastatic lymph node lesion from a lung cancer patient. The cell line exhibited high capacities for proliferation and invasion, as validated by its phenotypic and genetic characteristics. This cell line had a unique STR profile and karyotype analysis revealed numerical and structural chromosome abnormalities. The growth rate of in vivo xenografted tumors established using ZX2021H cells was higher than that using H1299 cells. The cell stemness‐related gene SOX2 was overexpressed in ZX2021 compared with H1299 cells, as determined by qRT‐PCR.

Conclusion

We successfully established a novel, highly malignant lung cancer cell line, ZX2021H, derived from metastatic lymph node tissue from a Chinese lung cancer patient. This cell line may provide an ideal cell model for further studies of the molecular mechanisms underlying lung cancer metastasis and for the development of new anticancer agents.

Comparative study on the efficacy and exposure of molecular target agents in non-small cell lung cancer PDX models with driver genetic alterations

Patient-derived xenografts (PDXs) can adequately reflect clinical drug efficacy. However, the methods for evaluating drug efficacy are not fully established. We selected five non-small cell lung cancer (NSCLC) PDXs with genetic alterations from established PDXs and the corresponding molecular targeted therapy was administered orally for 21 consecutive days. Genetic analysis, measurement of drug concentrations in blood and tumors using liquid chromatography and tandem mass spectrometry, and analysis of drug distribution in tumors using matrix-assisted laser desorption/ionization mass spectrometry were performed. Fifteen (20%) PDXs were established using samples collected from 76 NSCLC patients with genetic alterations. The genetic alterations observed in original patients were largely maintained in PDXs. We compared the drug efficacy in original patients and PDX models; the efficacies against certain PDXs correlated with the clinical effects, while those against the others did not. We determined blood and intratumor concentrations in the PDX model, but both concentrations were low, and no evident correlation with the drug efficacy could be observed. The intratumoral spatial distribution of the drugs was both homogeneous and heterogeneous for each drug, and the distribution was independent of the expression of the target protein. The evaluation of drug efficacy in PDXs enabled partial reproduction of the therapeutic effect in original patients. A more detailed analysis of systemic and intratumoral pharmacokinetics may help clarify the mode of action of drugs. Further development of evaluation methods and indices to improve the prediction accuracy of clinical efficacy is warranted.

Lung cancer driven by BRAFG469V mutation is targetable by EGFR kinase inhibitors

INTRODUCTION

Mutations in BRAF occur in 2-4% of lung adenocarcinoma (LUAD) patients. Combination dabrafenib/trametinib or single-agent vemurafenib is approved only for patients with cancers driven by the V600E BRAF mutation. Targeted therapy is not currently available for patients harboring non-V600 BRAF mutations.

METHODS

An LUAD patient-derived xenograft (PDX) model (PHLC12) with wild-type and non-amplified epidermal growth factor receptor (EGFR) was tested for response to EGFR tyrosine kinase inhibitors (TKI). A cell line derived from this model (X12CL) was also used to evaluate drug sensitivity and to identify potential drivers by siRNA knockdown. Kinase assays were used to test direct targeting of the candidate driver by the EGFR TKIs. Structural modeling including, molecular dynamics (MD) simulations, and binding assays were conducted to explore the mechanism of off-target inhibition by EGFR TKIs on the model 12 driver.

RESULTS

Both PDX PHLC12 and the X12CL cell line were sensitive to multiple EGFR TKIs. The BRAF^G469V mutation was found to be the only known oncogenic mutation in this model. siRNA knockdown of BRAF, but not the EGFR, killed X12CL, confirming BRAF^G469V as the oncogenic driver. Kinase activity of the BRAF protein isolated from X12CL was inhibited by treatment with the EGFR TKIs gefitinib and osimertinib, and expression of BRAF^G469V in non-EGFR-expressing NR6 cells promoted growth in low serum, which was also sensitive to EGFR TKIs. . Structural modeling, MD simulations, and in vitro binding assays support BRAF^G469V being a direct target of the TKIs.

CONCLUSION

Clinically approved EGFR TKIs can be repurposed to treat NSCLC patients harboring the BRAF^G469V mutation.

Increased Tumor Growth Rate and Mesenchymal Properties of NSCLC-Patient-Derived Xenograft Models during Serial Transplantation

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. The high mortality is very often a consequence of its late diagnosis when the cancer is already locally advanced or has disseminated. Advances in the study of NSCLC tumors have been achieved by using in vivo models, such as patient-derived xenografts. Apart from drug screening, this approach may also be useful for study of the biology of the tumors. In the present study, surgically resected primary lung cancer samples (n = 33) were implanted in immunodeficient mice, and nine were engrafted successfully, including seven adenocarcinomas, one squamous-cell carcinoma, and one large-cell carcinoma. ADC tumors bearing the KRAS-G12C mutation were the most frequently engrafted in our PDX collection. Protein expression of vimentin, ezrin, and Ki67 were evaluated in NSCLC primary tumors and during serial transplantation by immunohistochemistry, using H-score. Our data indicated a more suitable environment for solid adenocarcinoma, compared to other lung tumor subtypes, to grow and preserve its architecture in mice, and a correlation between higher vimentin and ezrin expression in solid adenocarcinomas. A correlation between high vimentin expression and lung adenocarcinoma tumors bearing KRAS-G12C mutation was also observed. In addition, tumor evolution towards more proliferative and mesenchymal phenotypes was already observed in early PDX tumor passages. These PDX models provide a valuable platform for biomarker discovery and drug screening against tumor growth and EMT for lung cancer translational research.

A novel osimertinib-resistant human lung adenocarcinoma cell line harbouring mutant EGFR and activated IGF1R

OBJECTIVE

A third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), osimertinib, is the standard treatment for patients with non-small cell lung cancer harbouring mutant EGFR. Unfortunately, these patients inevitably acquire resistance to EGFR-TKI therapies, including osimertinib. However, the mechanism associated with this resistance remains unclear.

METHODS

A 63-year-old Japanese female with lung adenocarcinoma underwent right upper lobectomy (pT1bN2M0 pStage IIIA, EGFR Ex21 L858R). She manifested post-operative tumour recurrence with multiple lung metastases 8 months later and began gefitinib treatment. The lung lesions re-grew 15 months later, and EGFR T790M mutation was detected in the lung metastasis re-biopsy. She was administered osimertinib; however, it relapsed with pleural effusion 16 months later. We isolated cells from the osimertinib-resistant pleural effusion to establish a novel cell line, ABC-31.

RESULTS

Although the EGFR L858R mutation was detected in ABC-31 cells, the T790M mutation was lost. ABC-31 cells were resistant to EGFR-TKIs, including osimertinib. Phospho-receptor tyrosine kinase array revealed activation of the insulin-like growth factor 1 receptor (IGF1R), whereas overexpression of the IGF1R ligand, IGF2, induced IGF1R activation in ABC-31 cells. Combination therapy using EGFR-TKIs and IGF1R inhibitor acted synergistically in vitro. She was re-administered osimertinib since EGFR-TKIs and IGF1R inhibitor combination therapy was impossible in clinical practice. This had a slight and short-lived effect.

CONCLUSIONS

Taken together, we have successfully established a new osimertinib-resistant lung adenocarcinoma cell line with activated IGF1R. These ABC-31 cells will help develop novel therapeutic strategies for patients with lung adenocarcinoma resistant to specific treatment via IGF1R activation.

Gene expression profiles of the original tumors influence the generation of PDX models of lung squamous cell carcinoma

Patient-derived xenograft (PDX) murine models are employed for preclinical research on cancers, including non-small cell lung cancers (NSCLCs). Even though lung squamous cell carcinomas (LUSCs) show the highest engraftment rate among NSCLCs, half of them nevertheless show PDX failure in immunodeficient mice. Here, using immunohistochemistry and RNA sequencing, we evaluated the distinct immunohistochemical and gene expression profiles of resected LUSCs that showed successful engraftment. Among various LUSCs, including the basal, classical, secretory, and primitive subtypes, those in the non-engrafting (NEG) group showed gene expression profiles similar to the pure secretory subtype with positivity for CK7, whereas those in the engrafting (EG) group were similar to the mixed secretory subtype with positivity for p63. Pathway analysis of 295 genes that demonstrated significant differences in expression between NEG and EG tumors revealed that the former had enriched expression of genes related to the immune system, whereas the latter had enriched expression of genes related to the cell cycle and DNA replication. Interestingly, NEG tumors showed higher infiltration of B cells (CD19+) and follicular dendritic cells (CD23+) in lymph follicles than EG tumors. Taken together, these findings suggest that the PDX cancer model of LUSC represents only a certain population of LUSCs and that CD19- and CD23-positive tumor-infiltrating immune cells in the original tumors may negatively influence PDX engraftment in immunodeficient mice.

LncRNA GAS5 inhibits Invasion and Migration of Lung Cancer through influencing EMT process

Background: Lung cancer is a malignant tumor in mammary gland epithelium with high morbidity and mortality among women worldwide. Long noncoding RNA GAS5 (GAS5) has been proved to be closely related with tumor progression. However, the influence of GAS5 on lung cancer and the specific mechanism remain unclear.

Methods: Cell invasion, cell migration, cell apoptosis and cell cycle were investigated after transfection with pcDNA-GAS5 and sh-GAS5. Sizes of tumors were measured by establishing transplanted tumor model in vivo. E-cadherin and N-cadherin expressions were investigated.

Results: Cell invasion and migration were inhibited markedly in GAS5 overexpressed cell line. Cell cycle results indicated that the percentage of S-phase cells was increased, and G2-phase was reduced in the GAS5 overexpression cell line. Tumor size was suppressed obviously after GAS5 overexpression treatment. GAS5 markedly inhibited the expression of E-cadherin and induced the expression of N-cadherin. GAS5 overexpression significantly inhibited lung cancer cell proliferation by increasing the E-cadherin and decreasing N-cadherin.

Conclusions: These findings provide novel evidence that GAS5 can be viewed as an anti-lung cancer agent through affecting EMT pathway.

A Method for the Establishment of Human Lung Adenocarcinoma Patient-Derived Xenografts in Mice

Patient-derived xenografts (PDXs) are created by implanting human tumor tissue or cells into immunodeficent mice, and enable the study of tumor biology, biomarkers and response to therapy in vivo. This chapter describes a method for lung adenocarcinoma (LAC) PDX generation using subcutaneous implantation of tumor tissue and cell suspensions and incorporating the humanization of PDX models by reconstitution with human immune cells.

A Biobank of Colorectal Cancer Patient-Derived Xenografts

Colorectal cancer (CRC) is a challenging disease, with a high mortality rate and limited effective treatment options, particularly for late-stage disease. Patient-derived xenografts (PDXs) have emerged as an informative, renewable experimental resource to model CRC architecture and biology. Here, we describe the generation of a biobank of CRC PDXs from stage I to stage IV patients. We demonstrate that PDXs within our biobank recapitulate the histopathological and mutation features of the original patient tumor. In addition, we demonstrate the utility of this resource in pre-clinical chemotherapy and targeted treatment studies, highlighting the translational potential of PDX models in the identification of new therapies that will improve the overall survival of CRC patients.

Induction of Lung Tumors and Mutational Analysis in FVB/N Mice Treated with the Tobacco Carcinogen 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone

Lung cancer remains the leading cause of cancer-related deaths worldwide. In order to understand lung cancer biology and evaluate novel therapeutic strategies, preclinical mouse models have been developed that mimic early and advanced-stage lung cancer. Among autochthonous models, carcinogen-induced systems are valuable preclinical tools since tobacco smoking remains the number one risk factor for lung tumor development. Among the several thousand chemicals within cigarette smoke, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent carcinogen with tumorigenic effects described in both mice and humans. Herein, we describe the methodology for inducing lung tumors in mice using the tobacco carcinogen NNK and subsequent lung fixation for quantitative assessment of tumor development and analysis of oncogenic mutations in tumors.

miR-324-5p upregulation potentiates resistance to cisplatin by targeting FBXO11 signalling in non-small cell lung cancer cells

Dysregulation of microRNAs (miRNAs) plays a key role during the pathogenesis of chemoresistance in lung cancer (LCa). Previous study suggests that miR-324-5p may serve as a unique miRNA signature for LCa, but its role and the corresponding molecular basis remain largely explored. Herein, we report that miR-324-5p expression was significantly increased in cisplatin (CDDP)-resistant LCa tissues and cells, and this upregulation predicted a poor post-chemotherapy prognosis in LCa patients. miR-324-5p was further shown to impact CDDP response: Ectopic miR-324-5p expression in drug-naïve LCa cells was sufficient to attenuate sensitivity to CDDP and to confer more robust tumour growth in CDDP-challenged nude mice. Conversely, ablation of miR-324-5p expression in resistant cells effectively potentiated CDDP-suppressed cell growth in vitro and in vivo. Using multiple approaches, we further identified the tumour suppressor FBXO11 as the direct down-stream target of miR-324-5p. Stable expression of FBXO11 could abrogate the pro-survival effects of miR-324-5p in CDDP-challenged LCa cells. Together, these findings suggest that miR-324-5p upregulation mediates, at least partially, the CDDP resistance by directly targeting FBXO11 signalling in LCa cells. In-depth elucidation of the molecular basis underpinning miR-324-5p action bears potential implications for mechanism-based strategies to improve CDDP responses in LCa.

Inhibition of LTA4H by bestatin in human and mouse colorectal cancer

Background

Our preclinical data showed that the leukotriene A4 hydrolase (LTA4H) pathway plays a role in colorectal cancer (CRC). High expression of LTA4H and leukotriene B4 receptor type 1 (BLT1) were also associated with CRC survival probability. Clinical samples were evaluated to determine whether LTA4H could serve as a therapeutic target and whether leukotriene B4 (LTB4) could be used as a biomarker for evaluating the efficacy of bestatin in CRC.

Methods

Patients with Stage I-III CRC did or did not receive bestatin prior to surgery. Evaluable pairwise CRC patient blood samples were collected to evaluate LTB4 concentration. Tissues were processed by immunohistochemistry to detect the LTA4H pathway and Ki-67 expression. We also determined whether LTA4H or BLT1 was associated with CRC survival probability and explored the mechanism of bestatin action in CRC.

Findings

Samples from 13 CRC patients showed a significant decrease in LTB4, the LTA4H signaling pathway, and Ki-67 in the bestatin-treated group compared with the untreated group. LTA4H and BLT1 are overexpressed in CRC and associated with CRC survival probability. Bestatin effectively inhibited LTB4 and tumorigenesis in the Apc^Min/+ and CRC patient-derived xenograft mouse model.

Interpretation

These results demonstrate that LTB4 could serve as a biomarker for evaluating bestatin efficacy in CRC and the antitumor effects of bestatin through its targeting of LTA4H and support further studies focusing on LTA4H inhibition in CRC.