Serum cytokeratin 19 fragment in advanced lung cancer: could we eventually have a serum tumor marker?

Diagnostic value of α-enolase expression and serum α-enolase autoantibody levels in lung cancer

OBJECTIVE

To investigate the diagnostic value of α-enolase (ENO1) and serum ENO1 autoantibody levels in lung cancer.

METHODS

Immunohistochemistry staining and ELISA were performed to detect ENO1 expression in lung tissue and serum ENO1 autoantibody levels, respectively.

RESULTS

The expression of ENO1 was higher in lung cancer tissues than in benign lung disease tissues (p < 0.001). The proportion of lung cancer samples expressing ENO1 was not significantly different among the various pathological classification groups. The proportion of samples expressing ENO1 was higher in lung cancer patients in stages I/II than in those in stages III/IV (χ2 = 5.445; p = 0.018). The expression of ENO1 in lung cancer tissues was not associated with age, gender, or smoking history. Serum ENO1 antibody levels were significantly higher in the lung cancer group than in the benign lung disease and control groups (p < 0.001). The differences among the pathological classification groups were not statistically significant. Serum ENO1 antibody levels were also in lung cancer patients in stages I/II than in those in stages III/IV (p < 0.01). Serum ENO1 antibody levels were not associated with age, gender, or smoking history in lung cancer patients. The ROC curve representing the diagnosis of lung cancer based on ENO1 antibody levels had an area under the curve of 0.806.

CONCLUSIONS

Our results suggest that high levels of ENO1 are associated with the clinical stage of lung cancer and that ENO1 expression and its serum autoantibody levels show diagnostic value in lung cancer.

Current and Prospective Protein Biomarkers of Lung Cancer

Lung cancer is a malignant lung tumor with various histological variants that arise from different cell types, such as bronchial epithelium, bronchioles, alveoli, or bronchial mucous glands. The clinical course and treatment efficacy of lung cancer depends on the histological variant of the tumor. Therefore, accurate identification of the histological type of cancer and respective protein biomarkers is crucial for adequate therapy. Due to the great diversity in the molecular-biological features of lung cancer histological types, detection is impossible without knowledge of the nature and origin of malignant cells, which release certain protein biomarkers into the bloodstream. To date, different panels of biomarkers are used for screening. Unfortunately, a uniform serum biomarker composition capable of distinguishing lung cancer types is yet to be discovered. As such, histological analyses of tumor biopsies and immunohistochemistry are the most frequently used methods for establishing correct diagnoses. Here, we discuss the recent advances in conventional and prospective aptamer based strategies for biomarker discovery. Aptamers like artificial antibodies can serve as molecular recognition elements for isolation detection and search of novel tumor-associated markers. Here we will describe how these small synthetic single stranded oligonucleotides can be used for lung cancer biomarker discovery and utilized for accurate diagnosis and targeted therapy. Furthermore, we describe the most frequently used in-clinic and novel lung cancer biomarkers, which suggest to have the ability of differentiating between histological types of lung cancer and defining metastasis rate.

EMT influences the expression of CK19 in pleural effusion-derived lung cancer cells and their invasion and metastasis

Lung cancer is the most common cancer after breast and colon cancer, with high rates of mortality, worldwide. There are two main types of lung cancer, small cell lung carcinoma (SCLC), which accounts for approximately 20% of all lung cancer cases and non-SCLC, which accounts for almost 80% of lung cancer cases. Although lung cancer is one of the most aggressive types of cancer, progress in achieving better clinical outcomes has been gradual. Even though a number of markers have been suggested for the diagnosis of lung cancer and monitoring of disease progression, there is no clear way of assessing the invasion, epithelial-mesenchymal transition (EMT) and metastasizing capability of the primary tumor cells. We investigated the incidence of cytokeratin 19 (CK19)-negative expressers in different types of lung cancer from 111 lung cancer patients, their serum and pleural effusion CYFRA21-1 levels and whether induction of EMT in the primary focus cells influences the expression of CK19. In addition, we examined whether CK19-negative lung cancers were more invasive and metastatic. We also examined the propensity of primary focus cells to undergo EMT in the presence of transforming growth factor-β1 (TGF-β1). The results obtained suggested that the invasion and metastasis of lung tumor cells can be assessed by having a complete picture of serum CYFRA21-1 together with the CK19 expression status of primary focus cells and pleural effusion. This assessment may be further improved by examining the propensity of the isolated primary focus cells to undergo TGF-β1 induced EMT in cell culture.