The investigation of levels of endothelial cell-specific molecule, progranuline, clusterin, and human epididymis protein 4 in the differential diagnosis of malignant pleural effusions

BACKGROUND

Progranulin (PGRN), endothelial cell-specific molecule-1, clusterin (CLU), and human epididymis protein 4 (HE-4) are novel proteins reported to have diagnostic and prognostic potential in lung cancer. Here, we aimed to identify the markers with high sensitivity and specificity in distinguishing malignant pleural fluids from other pleural fluids.

METHODS

This prospective, descriptive study was conducted at a medical faculty hospital between 2016 and 2019. The study population consisted of 90 patients <18 years of age with pleural effusion (PE). Levels of pleural fluids of PGRN, endothelial cell-specific molecule-1, CLU, and HE-4 were measured with enzyme-linked immunosorbent assay kits under the manufacturer's manual.

RESULTS

Of 90 patients, 54 were men, and 36 were women (mean age 65 ± 16 years). Of pleural fluids investigated, 23 (25%) and 67 (74%) were transudates and exudates, respectively. Of exudates, while 27 (40%) and 19 (28%) were parapneumonic PE and tuberculous PE, respectively, 20 (29%) were malignant pleural effusion (MPE). Levels of all biomarkers in exudate fluids were found significantly higher than those of transudate fluids. CLU, HE-4, and PGRN levels in MPE were also found significantly higher than benign fluids (P < .05). Cutoff values were achieved by receiver operating characteristics analysis for CLU, HE-4, and PGRN to distinguish between malignant and benign groups. For diagnosis of MPE, the sensitivity and specificity values were found as 0.66 and 0.67 for a cutoff value of CLU of 18.29 mg/L (P = .00), as 0.76 and 0.76 for a cutoff value of HE-4 of 9.33 mg/L (P = .00), and as 0.66 and 0.67 for a cutoff value of PGRN of 105.91 mg/L (P = .001).

CONCLUSION

HE-4 having high sensitivity and specificity can be a potential diagnostic marker in distinguishing between malignant and benign effusions, and these findings can constitute a basis for future research.

Endocan: a novel circulating proteoglycan

Endocan is a novel endothelium derived soluble dermatan sulfate proteoglycan. It has the property of binding to a wide range of bioactive molecules associated with cellular signaling and adhesion and thus regulating proliferation, differentiation, migration, and adhesion of different cell types in health and disease. An increase in tissue expression or serum level of endocan reflects endothelial activation and neovascularization which are prominent pathophysiological changes associated with inflammation and tumor progression. Consequently, endocan has been used as a blood-based and tissue-based biomarker for various cancers and inflammation and has shown promising results.