Spectrin isoforms: differential expression in normal hematopoiesis and alterations in neoplastic bone marrow disorders.

ABSTRACT

Spectrins are large, rod-like, multifunctional molecules that participate in maintaining cell structure, signal transmission, and DNA repair. Because little is known about the role of spectrins in normal hematopoiesis and leukemogenesis, we immunohistochemically stained bone marrow biopsy specimens from 81 patients for αI, αII, ßI, and ßII spectrin isoforms in normal reactive marrow (NRM), myelodysplastic syndrome, myeloproliferative neoplasm, acute myeloid leukemia (AML) with well-characterized cytogenetic abnormalities, acute erythroid leukemia (EryL), and acute megakaryoblastic leukemia (MegL). In NRM, spectrin isoforms were differentially expressed according to cell lineage αI and ßI in erythroid precursors; αII and ßII in granulocytes; and ßI and ßII in megakaryocytes. In contrast, 18 (44%) of 41 AMLs lacked αII spectrin and/or aberrantly expressed ßI spectrin (P = .0398; Fisher exact test) and 5 (100%) of 5 EryLs expressed ßII spectrin but lacked ßI spectrin. The frequent loss and/or gain of spectrin isoforms in AMLs suggests a possible role for spectrin in leukemogenesis.