SYNERGY OF IL-7 AND V-HA-RAS IN THE IN-VITRO NEOPLASTIC PROGRESSION OF MURINE PRE-B CELLS

A recombinant retrovirus expressing IL-7 was super-infected into a mur ine pre-B cell line previously infected with a retrovirus expressing v -Ha-ras. Populations of cells polyclonal for integration of the IL-7 v irus and independent of IL-7 for growth were generated. These cells we re highly tumorigenic. Similarly, co-infection of murine bone marrow w ith retroviruses expressing IL-7 and v-Ha-ras generated a pre-B lympho id outgrowth that was tumorigenic. While IL-7 and v-Ha-ras expression are not individually sufficient to induce tumorigenicity, their co-exp ression yields highly tumorigenic pre-B lymphoid cell lines. IL-7 expr ession may be equivalent to v-myc expression for synergy with v-H-ras in the neoplastic transformation of murine pre-B cells.