Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Does Not Improve Paclitaxel Effect in an Orthotopic Mouse Model of Lung Cancer

A Method for Orthotopic Transplantation of Lung Cancer in Mice

Preclinical mouse models of lung cancer have been vital experimental tools to elucidate cancer biology and test novel therapeutic regimens. Two main models are most commonly used-genetically engineered mouse models and xenograft transplantation models. The most common xenograft model employs subcutaneous transplantation of tumor cells. However, the subcutaneous space is a foreign environment to lung cancer cells and does not appropriately model the tumor-stromal interactions of endogenous lung cancers. Here, we present an orthotopic mouse model of lung cancer that utilizes direct injection of cancer cells into the lung parenchyma that allows many potential studies including interactions of lung fibroblast Hedgehog pathway activity and tumor epithelia. The protocol describes this procedure and its potential applications for lung cancer research.

T-Cell Molecular Modulation Responses in Atherosclerosis Anergy

Atherosclerosis continues to be a major cause of death in patients with cardiovascular diseases. The cooperative role of immunity has been recently considered in atherosclerotic plaque inflammation, especially adaptive immune response by T cells. In this review, we examine the possible role of T cells in atherosclerosis-mediated inflammation and conceivable therapeutic strategies that can ameliorate complications of atherosclerosis. The cytokines secreted by T-lymphocyte subsets, different pathophysiological profiles of microRNAs (miRs), and the growth factor/receptor axis have diverse effects on the inflammatory cycle of atherosclerosis. Manipulation of miRNA expression and prominent growth factor receptors involved in inflammatory cytokine secretion in atherosclerosis can be considered diagnostic biomarkers in the induction of anergy and blockade of atherosclerotic development. This manuscript reviews immunomodulation of T cells responses in atherosclerosis anergy.

Evaluation of novel orthotopic nude mouse models for human small-cell lung cancer

INTRODUCTION

Although subcutaneous xenograft models have been widely used to evaluate the antitumor activity of new compounds, these models present a major disadvantage because the tumors do not accurately represent the cancer biology, especially with regard to metastasis and drug sensitivity. Effective murine models of small-cell lung cancer (SCLC) are needed.

METHODS

To provide strategies for studying new therapies and tumor biology, we developed three orthotopic models of human SCLC (H69A, a variant of the National Cancer Institute [NCI]-H69 cell line selected for invasiveness in vitro, NCI-H187, and NCI-N417) in nude mice. Tumor cells were injected into their lungs and new cell lines were established from these tumors (H69ALu, H187Lu, and N417Lu) to select for a reproducible tumor growth pattern and minimize variations in tumor size.

RESULTS

In all three models tumors started as a solitary mass in the left lung and spread to mediastinal and axillary lymph nodes and to the right lung in a pattern similar to that observed in human SCLC. To test the accuracy of this model in representing SCLC as seen in the clinic, we compared the efficacy of chemotherapeutic agents in each model. Irinotecan significantly inhibited the growth and progression of all three human SCLC tumors, and cisplatin, paclitaxel, and etoposide significantly inhibited the growth and progression of H69ALu tumors over the control agent.

CONCLUSIONS

We have established three orthotopic murine models of human SCLC closely resembling the course of human SCLC seen in the clinic including metastasis to lymph nodes and distant organs. They provide a means for better understanding the biology of this disease and will enable evaluation of novel therapeutic strategies.

Stretching mechanotransduction from the lung to the lab: approaches and physiological relevance in drug discovery

Recent years have shown a great deal of interest and research into the understanding of the biological and physiological roles of mechanical forces on cellular behavior. Despite these reports, in vitro screening of new molecular entities for lung ailments is still performed in static cell culture models. Failure to incorporate the effects of mechanical forces during early stages of screening could significantly reduce the success rate of drug candidates in the highly expensive clinical phases of the drug discovery pipeline. The objective of this review is to expand our current understanding of lung mechanotransduction and extend its applicability to cellular physiology and new drug screening paradigms. This review covers early in vivo studies and the importance of mechanical forces in normal lung development, use of different types of bioreactors that simulate in vivo movements in a controlled in vitro cell culture environment, and recent research using dynamic cell culture models. The cells in lungs are subjected to constant stretching (mechanical forces) in regular cycles due to involuntary expansion and contraction during respiration. The effects of stretch on normal and abnormal (disease) lung cells under pathological conditions are discussed. The potential benefits of extending dynamic cell culture models (screening in the presence of forces) and the associated challenges are also discussed in this review. Based on this review, the authors advocate the development of dynamic high throughput screening models that could facilitate the rapid translation of in vitro biology to animal models and clinical efficacy. These concepts are translatable to cardiovascular, digestive, and musculoskeletal tissues and in vitro cell systems employed routinely in drug-screening applications.

Effects of respiratory mechanical forces on the pharmacological response of lung cancer cells to chemotherapeutic agents

In vitro screening of chemotherapeutic agents is routinely carried out in static monolayer cell cultures. However, drugs administered to patients act in the presence of various microenvironments in vivo. For example, in lung tumors, mechanical forces are constantly present and do affect the physiological response of the lung tissue to a variety of therapeutic agents. We hypothesized that mechanical forces may affect the response of lung tumors to chemotherapeutic agents and studied the effects under simulated conditions. First, we examined the effects of simulated forces that approximate normal respiration on the proliferation and morphology of NCI-H358 and A549 cell lines. Then, we studied the effects of the simulated forces on the ability of Paclitaxel, Doxorubicin, Cisplatin, Zactima and an experimental drug to induce cytotoxicity in both cell lines. Cells were treated with the drugs in the presence or absence of simulated forces (20% maximum strain and 15 cycles/minute) that approximate human lung expansion and contraction. Cell proliferation and the effectiveness of the drugs were assessed. Using a standard exponential cell growth model, it was determined that mechanical forces significantly reduced the proliferation of both cell lines. Interestingly, forces also significantly lowered the effectiveness of all drugs except Zactima in A549 cells, while in NCI-H358 cells, Zactima was the only drug that demonstrated an increase in effectiveness owing to applied forces. Our results demonstrate that mechanical forces have significant impact on cell survival and chemotherapeutic efficacy and may be of significance in engineering improved screening assays for antitumor drug discovery.

Proliferation of human lung cancer in an orthotopic transplantation mouse model

The objective of this study was to clarify the growth and proliferation style of human lung cancer grown in an orthotopic transplantation model. The human lung squamous cell carcinoma SQ5 and adenocarcinoma A549 cell lines were used. Tumor cells suspended in serum-free medium were directly injected into the main bronchi of anesthetized female Balb/c athymic nude mice with simultaneous administration of 0.01 M ethylenediaminetetraacetic acid. Bromodeoxyuridine was injected into mice 20 min before sacrifice. Lung tissue with tumor nodules and subcutaneous tumors were fixed and confirmed by histological examinations. Bromodeoxyuridine-labeled cells in the tumor area were counted, and the proliferation index was calculated. Lung tumor colonies of various sizes were obtained in the SQ5- and A549-cell orthotopically transplanted mice. Orthotopic SQ5 tumors whose minor diameter was 40-700 μm and major diameter was 80-830 μm showed no definite necrosis. Orthotopic SQ5 tumors whose minor diameter was 540-5,200 μm and major diameter was 600-6,100 μm showed definite necrosis in the tumor center. Similar results were also found in the orthotopic A549 tumors. The proliferation index was 7.38 (3.03)/10.63 (3.10) in the orthotopic SQ5 tumors with/without necrosis and 6.99 (2.10) in the subcutaneous SQ5 tumors with necrosis, respectively. The proliferation index was 2.70 (0.88)/3.53 (1.70) in the orthotopic A549 tumors with/without necrosis and 3.91 (0.63) in the subcutaneous A549 tumors with necrosis, respectively. The data suggest that this orthotopic transplantation model may provide the proper organ microenvironment for lung cancer growth and may be suitable for the target therapy research of human lung cancer.

EGFR-targeting drugs in combination with cytotoxic agents: from bench to bedside, a contrasted reality

The clinical experience recently reported with epidermal growth factor receptor (EGFR)-targeting drugs confirms the synergistic interactions observed between these compounds and conventional cytotoxic agents, which were previously established at the preclinical stage. There are, however, examples of major gaps between the bench and the bedside. Particularly demonstrative is the failure of the tyrosine kinase inhibitors (TKIs) (gefitinib and erlotinib) combined with chemotherapy in pretreated nonsmall cell lung cancer patients. These discrepancies can be due to several factors such as the methodology used to evaluate TKI plus cytotoxic agent combinations in preclinical models and the insufficient consideration given to the importance of the drug sequences for the tested combinations. Recent advances in understanding the biologic basis of acquired resistance to these agents have great potential to improve their clinical effectiveness. The purpose of this review is to critically examine the experimental conditions of the preclinical background for anti-EGFR drug–cytotoxic agent combinations and to attempt to explain the gap between clinical observations and preclinical data.

Targeted therapy against VEGFR and EGFR with ZD6474 enhances the therapeutic efficacy of irradiation in an orthotopic model of human non-small-cell lung cancer

PURPOSE

Conventional therapies for patients with lung cancer have reached a therapeutic plateau. We therefore evaluated the feasibility of combined vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) and epidermal growth factor (EGF) receptor (EGFR) targeting with radiation therapy in an orthotopic model that closely recapitulates the clinical presentation of human lung cancer.

METHODS AND MATERIALS

Effects of irradiation and/or ZD6474, a small-molecule inhibitor of VEGFR2 and EGFR tyrosine kinases, were studied in vitro for human lung adenocarcinoma cells by using proliferation and clonogenic assays. The feasibility of combining ZD6474 with radiation therapy was then evaluated in an orthotopic model of human lung adenocarcinoma. Lung tumor burden and spread within the thorax were assessed, and tumor and adjacent tissues were analyzed by means of immunohistochemical staining for multiple parameters, including CD31, VEGF, VEGFR2, EGF, EGFR, matrix metalloproteinase-2 and -9, and basic fibroblast growth factor.

RESULTS

ZD6474 enhanced the radioresponse of NCI-H441 human lung adenocarcinoma cells by a factor of 1.37 and markedly inhibited sublethal damage repair. In vivo, the combined blockade of VEGFR2 and EGFR by ZD6474 blocked pleural effusion formation and angiogenesis and enhanced the antivascular and antitumor effects of radiation therapy in the orthotopic human lung cancer model and was superior to chemoradiotherapy.

CONCLUSIONS

When radiation therapy is combined with VEGFR2 and EGFR blockade, significant enhancement of antiangiogenic, antivascular, and antitumor effects are seen in an orthotopic model of lung cancer. These data provide support for clinical trials of biologically targeted and conventional therapies for human lung cancer.

Inhalation delivery and anti-tumor activity of celecoxib in human orthotopic non-small cell lung cancer xenograft model

PURPOSE

To determine the in vivo anti-tumor effect of aerosolized Celecoxib (Cxb) in combination with i.v Docetaxel (Doc) and compare the anti-tumor effect with oral Cxb combined with i.v Doc in human orthotopic non-small cell lung cancer (NSCLC) xenograft model.

MATERIALS AND METHODS

Female Nu/Nu mice were implanted with orthotopic tumors by injecting A549 cells into the lung parenchyma. Seven day after tumor implantation the mice were treated with aerosolized Cxb (30 min exposure/day, 5 mg/ml solution) + i.v Doc (10 mg/kg) and the effect was compared with oral Cxb (150 mg/kg/day) + i.v Doc (10 mg/kg), for 28 days. Small-animal nose only inhalation chamber (CH Technologies, Westwood, NJ) was utilized for aerosol exposure. Therapeutic activity of Cxb (aerosol/oral) + Doc was estimated by differences in lung weight, tumor area and animal body weight. Lung tumor samples isolated from mice were analyzed for (a) PGE2 levels by enzyme immunoassay (EIA) (b) expression of Fas and Factor VIII by immunohistochemistry (c) IL-8 expression using EIA kits and (d) mRNA expression for caspase-3 by Real-Time PCR.

RESULTS

Mice treated with Cxb (aerosol/oral) + Doc showed significant reduction (P < 0.001) in lung weight and tumor area as compared to Cxb or Doc treatments. Cxb (aerosol/oral) + Doc showed increased apoptosis mediated via increased Fas and caspase-3 (P < 0.001) expression as compared to untreated control. Further, the combination treatment showed antiangiogenic effect as demonstrated by reduced expression of Factor VIII, IL-8 (P < 0.001) and PGE2 (P < 0.001) in lung tumors as compared to untreated control. Aerosolized Cxb at a significantly lower therapeutic dose (4.56 mg/kg/day) demonstrated comparable anti-tumor efficacy to orally administered Cxb (150 mg/kg/day).

CONCLUSION

Cxb was formulated and effectively delivered via aerosolization to treat orthotopic lung tumors in combination with i.v Doc. Cxb when administered by aerosol produced same therapeutic effect as oral Cxb, but at lower therapeutic dose and thus shows promise for the treatment of lung cancer.

Development of an orthotopic model to study the biology and therapy of primary human lung cancer in nude mice

PURPOSE

This study was conducted to develop biologically relevant animal models of human lung cancer that are reproducible, inexpensive, and easy to perform.

EXPERIMENTAL DESIGN

Human lung adenocarcinoma (PC14PE6), bronchioloalveolar carcinoma (NCI-H358), squamous cell carcinoma (NCI-H226), poorly differentiated non-small cell lung cancer (NCI-H1299 and A549), or small cell lung cancer (NCI-H69) cells in Matrigel were injected percutaneously into the left lungs of nude mice. The growth pattern of the different lung cancer tumors was studied. For PC14PE6 and NCI-H358, the growth pattern in the subcutis and the response to paclitaxel were also studied.

RESULTS

As is observed for human primary lung cancer, tumors formed from a single focus of disease and progressed to a widespread and fatal thoracic process characterized by diffuse dissemination of lung cancer in both lungs and metastasis to intra- and extrathoracic lymph nodes. When the lung cancer cell lines were implanted s.c., systemic therapy with paclitaxel induced tumor regression. However, only a limited therapeutic response to paclitaxel was observed when the same cells were implanted orthotopically into the lung. Immunohistochemical analysis of tumor tissue revealed increased expression of the proangiogenic factors interleukin 8, basic fibroblast growth factor, and vascular endothelial growth factor/vascular permeability factor.

CONCLUSIONS

Our orthotopic models of human lung cancer confirm the "seed and soil" concept and likely provide more clinically relevant systems for the study of both non-small cell lung cancer and small cell lung cancer biology, and for characterizing novel therapeutic strategies.