Impact of miR-155 and miR-126 as novel biomarkers on the assessment of disease progression and prognosis in adult T-cell leukemia

Objective: Micro RNAs (miRNAs) provide new insight in the development of cancer, but little is known about their clinical relevance as biomarkers in the assessment of diagnosis, classification, progression and prognosis of various cancers. To explore a potential novel biomarker, we examined the cellular and plasma miRNA profiles in adult T-cell leukemia (ATL) characterized by diverse clinical features. Methods and results: Using CD4-positive cells isolated from 2 non-infected healthy individuals, 3 chronic ATL patients and 3 acute ATL patients, cellular miRNAs were profiled by microarray. The microarray screened 5 miRNAs namely miR-155, let-7g, miR-126, miR-130a and let-7b because of the large difference in their expression in diseased vs. that of healthy controls. The expression levels of before 5 miRNAs re-quantified by reverse transcription quantifiable polymerase chain reaction (RT-qPCR) were not always accordant in cells and plasma. The high and low plasma levels of miR-155 and miR-126 changed with ATL stage. Conclusion: The present study revealed that there is a quantitative discrepancy between cellular and plasma miRNAs. The elevation of plasma miR-155 and the reduction in miR-126 correlated with poor prognosis, indicating their usefulness as a novel biomarker for the assessment of disease stage.