Expression of SOCS genes in normal and leukemic human leukocytes stimulated by prolactin, growth hormone and cytokines

Abstract

To evaluate the possible role of the recently described family of suppressors of cytokine signaling (SOCS) factors in the human lympho-hemopoietic system, we have monitored SOCS factor expression, both constitutive and induced by either cytokines, prolactin (PRL) or growth hormone (GH), using polymerase chain reaction in normal and leukemic cells. CIS (cytokine-inducible SH2-containing protein), SOCS-2 and SOCS-3 were constitutively expressed in peripheral blood mononuclear leukocytes. SOCS-3 expression was enhanced by PRL or by IFN-gamma. In bone marrow cells and granulocytes, CIS expression was induced and SOCS-2 enhanced by IFN-gamma and by PRL. In tonsillar cells, CIS expression was increased and SOCS-2 was induced by IL-1beta, IL-6, PRL and GH. SOCS-3 expression was enhanced by IL-1beta. The expression of SOCS-7 was increased by IL-6, PRL and GH. In Raji B-lymphoma cells, the expression of SOCS-2 and SOCS-7 was enhanced by IL-1beta. In THP-1 myeloid leukemia cells pretreated with TPA (to induce receptors for IFN-gamma), IFN-gamma induced SOCS-2. Jurkat cells expressed more SOCS-2 when exposed to PRL. Original observations in this work include the first report on SOCS-7 induction by cytokines. Also our data shed new light on the possible involvement of PRL and GH in the cytokine network. These hormones could modulate the transduction of signals originating from receptors for various cytokines.