Translational research in lung cancer

Pulmonary Effects of Antineoplastic Therapy

Pulmonary toxicity is common after cancer therapy and can result from all therapeutic modalities. The consequential decrease in lung function ranges in severity from subclinical to life-threatening or even fatal and can manifest in the acute setting or many years after completion of therapy. Radiation effects are due to direct insult to the pulmonary parenchyma and, for younger children, impaired thoracic musculoskeletal development. Radiation pneumonitis can occur in the acute/subacute setting, as well as fibrosis with comprised gas exchange as a late effect of direct lung irradiation; thoracic wall malformation can cause restriction of function as a chronic sequela. The pulmonary effects of cytotoxic drugs usually present as acute effects, but there is the potential for significant late morbidity and mortality. Of course, surgical interventions can also cause both acute and/or late pulmonary effects as well, depending on the specific procedure. Although treatment approaches for the management of pediatric cancers are continually adapted to provide optimal therapy while minimizing toxicities, to a varying degree all therapies have the potential for both acute and late pulmonary toxicity. Of note, the cumulative incidence of pulmonary complications rises with increasing time since diagnosis, which suggests that adult survivors of childhood cancer require lifelong monitoring and management of potential new-onset pulmonary morbidity as they age. Knowledge of cytotoxic therapies and an understanding of lung physiology and how it may be altered by therapy facilitate appropriate clinical care and monitoring of long-term survivors.

Bioinformatics methods for learning radiation-induced lung inflammation from heterogeneous retrospective and prospective data

Radiotherapy outcomes are determined by complex interactions between physical and biological factors, reflecting both treatment conditions and underlying genetics. Recent advances in radiotherapy and biotechnology provide new opportunities and challenges for predicting radiation-induced toxicities, particularly radiation pneumonitis (RP), in lung cancer patients. In this work, we utilize datamining methods based on machine learning to build a predictive model of lung injury by retrospective analysis of treatment planning archives. In addition, biomarkers for this model are extracted from a prospective clinical trial that collects blood serum samples at multiple time points. We utilize a 3-way proteomics methodology to screen for differentially expressed proteins that are related to RP. Our preliminary results demonstrate that kernel methods can capture nonlinear dose-volume interactions, but fail to address missing biological factors. Our proteomics strategy yielded promising protein candidates, but their role in RP as well as their interactions with dose-volume metrics remain to be determined.

Identifying set-wise differential co-expression in gene expression microarray data

Background

Previous differential coexpression analyses focused on identification of differentially coexpressed gene pairs, revealing many insightful biological hypotheses. However, this method could not detect coexpression relationships between pairs of gene sets. Considering the success of many set-wise analysis methods for microarray data, a coexpression analysis based on gene sets may elucidate underlying biological processes provoked by the conditional changes. Here, we propose a differentially coexpressed gene sets (dCoxS) algorithm that identifies the differentially coexpressed gene set pairs between conditions.

Results

dCoxS is a two-step analysis method. In each condition, dCoxS measures the interaction score (IS), which represents the expression similarity between two gene sets using Renyi relative entropy. When estimating the relative entropy, multivariate kernel density estimation was used to model gene-gene correlation structure. Statistical tests for the conditional difference between the ISs determined the significance of differential coexpression of the gene set pair. Simulation studies supported that the IS is a representative measure of similarity between gene expression matrices. Single gene coexpression analysis of two publicly available microarray datasets detected no significant results. However, the dCoxS analysis of the datasets revealed differentially coexpressed gene set pairs related to the biological conditions of the datasets.

Conclusion

dCoxS identified differentially coexpressed gene set pairs not found by single gene analysis. The results indicate that set-wise differential coexpression analysis is useful for understanding biological processes induced by conditional changes.

Adverse event reporting and developments in radiation biology after normal tissue injury: International Atomic Energy Agency consultation

PURPOSE

Recent research has enhanced our understanding of radiation injury at the molecular-cellular and tissue levels; significant strides have occurred in standardization of adverse event reporting in clinical trials. In response, the International Atomic Energy Agency, through its Division of Human Health and its section for Applied Radiation Biology and Radiotherapy, organized a consultation meeting in Atlanta (October 2, 2004) to discuss developments in radiobiology, normal tissue reactions, and adverse event reporting.

METHODS AND MATERIALS

Representatives from cooperative groups of African Radiation Oncology Group, Curriculo Radioterapeutica Ibero Latino Americana, European Organization for Research and Treatment of Cancer, National Cancer Institute of Canada Clinical Trials Group, Radiation Therapy Oncology Group, and Trans-Tasman Radiation Oncology Group held the meeting discussion.

RESULTS

Representatives of major radiotherapy groups/organizations and prominent leaders in radiotherapy discussed current understanding of normal tissue radiobiologic effects, the design and implementation of future clinical and translational projects for normal tissue injury, and the standardization of adverse-event reporting worldwide.

CONCLUSIONS

The consensus was to adopt NCI comprehensive adverse event reporting terminology and grading system (CTCAE v3.0) as the new standard for all cooperative group trials. Future plans included the implementation of coordinated research projects focusing on normal tissue biomarkers and data collection methods.

Interleukin (IL)-1A and IL-6: applications to the predictive diagnostic testing of radiation pneumonitis

PURPOSE

To explore the application of interleukin (IL)-1alpha and IL-6 measurements in the predictive diagnostic testing for symptomatic radiation pneumonitis (RP).

METHODS AND MATERIALS

In a prospective protocol investigating RP and cytokines, IL-1alpha and IL-6 values were analyzed by enzyme-linked immunosorbent assay from serial weekly blood samples of patients receiving chest radiation. We analyzed sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) over selected threshold values for both cytokines in the application to diagnostic testing.

RESULTS

The average coefficient of variation was 51% of the weekly mean IL-1alpha level and 39% of the weekly mean IL-6 value. Interleukin 1alpha and IL-6 became positively correlated with time. Specificity for both cytokines was better than sensitivity. IL-6 globally outperformed IL-1alpha in predicting RP, with higher PPV and NPV.

CONCLUSIONS

Our data demonstrate the feasibility of applying IL-1alpha and IL-6 measurements of blood specimens to predict RP. Interleukin-6 measurements offer stronger positive predictive value than IL-1alpha. This application might be further explored in a larger sample of patients.

Mechanism and modification of gastrointestinal soft tissue response to radiation: role of growth factors

PURPOSE

The negative effects of radiation on the bowel critically limit the treatment doses possible for tumors in the abdomen. The purpose of the present study was to measure mRNA levels of inflammatory cytokines in abdominally irradiated mouse bowel.

METHODS AND MATERIALS

Eight- to 12-week-old DBA mice were irradiated to the whole bowel in single fractions of 0 (mock irradiation), 12.5, or 13.5 Gy, and sacrificed 18-25 weeks thereafter. Gross bowel reactions were scored for bowel retraction, bowel wall thickening, mesenteric telangiectasia, and petechia. Tissues were snap frozen and processed for RNase protection assay or reverse transcription polymerase chain reaction assay, or both. Transforming growth factor beta1 (TGFbeta1), TGFbeta2, TGFbeta3, tumor necrosis factor alpha, interleukin-6, and interferon gamma mRNA were measured.

RESULTS

Radiation at 12.5 Gy and at 13.5 Gy produced significant bowel damage. Levels of all cytokines in irradiated mice were significantly increased (p < 0.05).

CONCLUSIONS

Late radiation-related bowel fibrovascular toxicity includes cytokine signal pathways that parallel those of many other normal tissues. These cytokine responses include elevations of tumor necrosis factor alpha, TGFbeta1, and interleukin-6. There exist approaches for lowering these cytokine levels that do not also protect tumor, and thus a therapeutic gain is expected. Opportunities to use these cytokine measurements both to predict clinical toxicity and to develop interventions are discussed.

Use of a transgenic mouse model to identify markers of human lung tumors

Lung cancer remains the leading cause of cancer related deaths worldwide. Despite advances in detection technologies, most patients diagnosed with lung cancer already harbor metastatic lesions. Because early detection is one of the primary determinants of patient outcome, a transgenic mouse model of lung cancer was utilized to identify markers of early lung tumors in humans. DNA microarray analysis of lung tumors arising in MMTV-IGF-II transgenic mice showed 9 genes consistently elevated in the murine lung tumors. Western blot analyses confirmed that several of these proteins were elevated in the lung tumors and immunohistochemical analyses identified 3 proteins, microsomal glutathione-S-transferase 1 (Mgst1), cathepsin H and syndecan 1 as being consistently elevated in the murine lung tumors compared to non-tumor bearing transgenic lung tissue and normal lung tissue surrounding the tumor. These 3 proteins were also elevated in human lung adenocarcinoma and squamous cell carcinomas. Importantly, the proteins were elevated in early stage, node negative tumors indicating their ability to detect early lung lesions that would be amenable to surgical resection. Therefore, our findings indicate that Mgst1, cathepsin H and syndecan 1 should be further evaluated as markers capable of identifying patients with early stage lung tumors.