A framework for the molecular classification of circulating tumor markers

DNA methylation in repetitive elements and post-traumatic stress disorder: a case-control study of US military service members

AIM

We investigated serum DNA methylation patterns in genomic repetitive elements, LINE-1 and Alu, for post-traumatic stress disorder (PTSD) cases and controls who were US military service members recently deployed to Afghanistan or Iraq.

METHODS

Cases (n = 75) had a postdeployment diagnosis of PTSD. Controls (n = 75) were randomly selected service members with no postdeployment PTSD diagnosis. Pre- and post-deployment sera were accessed, DNA was extracted and DNA methylation (percentage 5-methyl cytosine) was quantified via pyrosequencing. Conditional and unconditional logistic regressions were used to compare: cases post- to pre-deployment; controls post- to pre-deployment; cases to controls predeployment; cases to controls postdeployment.

RESULTS

LINE-1 was hypermethylated in controls post- versus pre-deployment (odds ratio [OR]: 1.33; 95% CI: 1.06-1.65) and hypomethylated in cases versus controls postdeployment (OR: 0.82; 95% CI: 0.67-1.01). Alu was hypermethylated for cases versus controls predeployment (OR: 1.46; 95% CI: 1.08-1.97).

CONCLUSION

Patterns of hypermethylation of LINE-1 in controls postdeployment and of Alu in cases postdeployment are intriguing and may suggest resilience or vulnerability factors.

Tumor markers in clinical practice: General principles and guidelines

Tumor markers are assuming a growing role in all aspects of cancer care, starting from screening to follow-up after treatment, and their judicious application in clinical practice needs a thorough understanding of the basics of pathophysiology, techniques of identification or testing, reasons for out-of-range levels of tumor markers, as well as the knowledge of evidence of their role in any given malignancy. These are, at the most, just an adjunct to diagnosis, and establishing a diagnosis on the basis of tumor markers alone (especially a single result) is fraught with associated pitfalls because of the problem of nonspecificity. In reality an ideal tumor marker does not exist. Detection can be done either in tissue or in body fluids like ascitic or pleural fluid or serum. Clinical uses can be broadly classified into 4 groups: screening and early detection, diagnostic confirmation, prognosis and prediction of therapeutic response and monitoring disease and recurrence. In addition to variable sensitivity and specificity, the prevalence of a particular malignancy may be a major determinant in the application of a particular test as a screening tool. Serum levels, in certain situations, can be used in staging, prognostication or prediction of response to therapy. Monitoring disease is, perhaps, the most common clinical use of serum tumor markers. Rising trend in serum levels may detect recurrence of disease well before any clinical or radiological evidence of disease is apparent ("biochemical recurrence"). Sampling should ideally be repeated after 5-6 half-lives of the marker in question (or the marker with the longest half-life if multiple markers are being considered); but if found elevated, the next sampling after 2-4 weeks, for additional evidence, may be justified.

Circulating nucleosomes predict the response to chemotherapy in patients with advanced non-small cell lung cancer

PURPOSE

We investigated the potential of circulating, nucleosomal DNA for the early prediction of the efficacy of chemotherapy in patients with advanced lung cancer.

EXPERIMENTAL DESIGN

In serum of 212 patients with newly diagnosed non-small cell lung cancer (stages III and IV) undergoing chemotherapy, nucleosomes (ELISA, Roche) were measured at days 1, 3, 5, and 8 of the first cycle and before each new therapeutic cycle. Additionally, carcinoembryonic antigen and cytokeratin 19 fragments (CYFRA 21-1; Elecsys, Roche) were determined before each cycle. The therapeutic success was classified by computed tomography before start of the third cycle according to the World Health Organization criteria.

RESULTS

In univariate analysis, responders (patients with remission) showed significantly (P < 0.05) lower values for the area under the curve of days 1 to 8 (AUC 1-8) of nucleosomes, the pretherapeutic baseline values of cycle 2 (BV2) and cycle 3 (BV3) of nucleosomes, and higher decreases of the baseline values from cycle 1 to 2 (BV1-2) and from cycle 1 to 3 (BV1-3) compared with nonresponders (patients with stable or progressive disease). Additionally, CYFRA 21-1 (BV1, BV2, BV3, BV1-2, BV1-3) and carcinoembryonic antigen (BV1-2) discriminated significantly between both groups. In multivariate analysis including all parameters available until end of the first therapeutic cycle, nucleosomes (AUC 1-8), CYFRA 21-1 (BV1), stage, and age were independent predictors of therapy response with nucleosomes (AUC 1-8) having the strongest impact.

CONCLUSION

Circulating nucleosomes in combination with oncological biomarkers are valuable for the early estimation of the efficacy of chemotherapy in patients with lung cancer.

A BALB/c murine lung alveolar carcinoma used to establish a surgical spontaneous metastasis model

Line-1, a weakly immunogenic lung tumor cell line derived from the BALB/c mouse, metastasizes spontaneously to the lungs of mice following subcutaneous administration. The parameters that influence metastasis as well as the progression of metastatic lung disease following surgical resection of primary subcutaneous tumors were characterized. Histological analysis of the lungs obtained from mice bearing different size subcutaneous tumors demonstrated that >90% of the mice developed micrometastatic disease in the lungs when the tumor exceeded 650 mm3 in size. Surgical resection of subcutaneous tumors resulted in the cure of primary disease in 95% of the mice. Macroscopic tumor nodules were grossly visible in the lungs of 75% of the mice 5 weeks after surgery. Serum amyloid A level correlated with primary tumor burden and was diagnostic for the presence of metastatic disease. The efficiency of metastasis, post-surgical primary tumor recurrence and long-term survival were significantly different between BALB/c mice obtained from different suppliers. The Line-1-BALB/c surgical metastasis model provides a clinically relevant tool for the evaluation of anti-cancer therapies, especially those that are designed to target long-term suppression of minimal residual disease following surgical intervention.

Antibody arrays: an embryonic but rapidly growing technology

Protein arrays are now an attractive proposition as they can measure a diverse range of protein interactions not possible with traditional DNA arrays. Antibody arrays are a specific subset of this technology. Originally conceived as multi-analyte detectors, antibody arrays are now used in a wide variety of applications. For instance, the potential of this technology to diagnose human diseases, such as leukemia, breast cancer and, potentially, heart failure, has stimulated much interest. Furthermore, identification of new protein targets in particular disease states will prove to be an invaluable tool in drug discovery and development. Patient prognosis and treatment are also potential applications of the technology. Antibody arrays have proved to be dynamic in response to these broad range of possibilities. This review examines variations in antibody array design and discusses current and potential applications of this novel and interesting technology.