EXPRESSION OF G-ALPHA-16, A G-PROTEIN ALPHA-SUBUNIT SPECIFIC FOR HEMATOPOIESIS IN ACUTE-LEUKEMIA

G-proteins are essential in signal transduction pathways. A G-protein alpha subunit termed G alpha 16 was found to be exclusively expressed in hematopoietic cell lines. In cells derived from patients, G alpha 1 6 expression has been detected in progenitor- and pre-B ALL cells and also in peripheral blood stem cells (PBSC). In this study, we analyzed G alpha 16 expression using a RT-PCR technique by testing elutriated blood cells from normal donors, PBSC from breast cancer patients and b one marrow or peripheral blood cells from acute leukemia patients. Bot h of two ALL patients and 15/16 AML patients expressed G alpha 16. In elutriation experiments, G alpha 16 expression was found in fractions containing the highest number of precursor cells but was absent in mat ure T and B cell fractions. In addition, CD34-enriched PBSC were posit ive for G alpha 16 expression. Further in vitro experiments using the cell line KG1 showed that G alpha 16 expression was not affected by th e growth inhibiting hemoregulatory peptide pEEDCK which has a sequence homology present within G alpha 16. Taken together, these data demons trate that G alpha 16 is expressed in various normal and malignant hem atopoietic progenitors but not in their differentiated counterparts. G alpha 16 could play a vital role in signal transduction pathways cont rolling proliferation in early normal and malignant hematopoiesis.