Overexpression of the ABCB1 drug transporter in acute myeloid leukemia cells is associated with downregulation of latrophilin-1.

Finding new markers with appropriate prognostic levels for the differential diagnosis of neoplastic diseases represents an important issue for biomedical research. Recently, latrophilin-1 (LPHN1) was reported to be expressed in human monocytic leukemia cell lines and in primary human acute myeloid leukemia (AML) cells. However, this expression was found to be absent in healthy leukocytes. LPHN1 was therefore considered a novel biomarker of human AML. In previous papers, we established two P-gp-positive variants (SKM-1/VCR and MOLM-13/VCR) of AML cell lines derived from parental human AML cells SKM-1 and MOLM-13 by selection with VCR. The present paper addresses the measurement of LPHN1 expression in SKM-1 and MOLM-13 cells and their P-gp-positive variants. Both parental AML lines were positive for LPHN1 expression at the mRNA and protein levels. However, the expression of LPHN1 at both the mRNA and protein levels was reduced in both P-gp-positive SKM-1/VCR and MOLM-13/VCR variants of AML cells. Interestingly, we observed an elevation of the latrophilin-3 transcript in P-gp-positive variants of AML cell lines. The combined results suggest that alterations in latrophilin expression occur in AML cells expressing P-gp.