Prognostic Potential of Galectin-9 mRNA Expression in Chronic Lymphocytic Leukemia

SIMPLE SUMMARY: There are still very few studies on Galectin-9 (Gal-9) in chronic lymphocytic leukemia (CLL), and the effect of Gal-9 on CLL pathogenesis. This study considers the possible role of Gal-9 as a new prognostic biomarker in CLL. Gal-9 mRNA expression was quantified with RT-qPCR in purified B-lymphocytes of 100 CLL patients and analyzed in the context of clinical data. Our results revealed the upregulation of Gal-9 mRNA in malignant B-cells. Unfavorable prognostic markers were closely linked to high Gal-9 mRNA expression. An increase in Gal-9 mRNA expression was also correlated with a shorter time to treatment. Gal-9 plays a crucial role in the tumor microenvironment and may become a significant complement to other prognostic indicators. Furthermore, we propose that EBV coinfection may have a detrimental effect on the prognosis of CLL patients, partly due to Gal-9 expression upregulation caused by EBV. ABSTRACT: Galectin-9 (Gal-9), very poorly characterized in chronic lymphocytic leukemia (CLL), was chosen in our study to examine its potential role as a CLL biomarker. The relation of Gal-9 expression in malignant B-cells and other routinely measured CLL markers, as well as its clinical relevance are poorly understood. Gal-9 mRNA expression was quantified with RT-qPCR in purified CD19+ B-cells of 100 CLL patients and analyzed in the context of existing clinical data. Our results revealed the upregulation of Gal-9 mRNA in CLL cells. High Gal-9 mRNA expression was closely associated with unfavorable prognostic markers. In addition, Gal-9 expression in leukemic cells was significantly elevated in CLL patients who did not respond to the first-line therapy compared to those who did respond. This suggests its potential predictive value. Importantly, Gal-9 was an independent predictor for the time to treatment parameters. Thus, we can suggest an adverse role of Gal-9 expression in CLL. Interestingly, it is possible that Gal-9 expression is induced in B-cells by EBV infection, so we determined the patients’ EBV status. Our suggestion is that EBV coinfection could worsen prognosis in CLL, partly due to Gal-9 expression upregulation caused by EBV.