Tumor promoter-stimulated synthesis of Mason-Pfizer monkey virus

Abstract

The tumor promoter 12-0-tetradecanoyl-phorbol-14-acetate (TPA) increases by severalfold the synthesis of Mason-Pfizer monkey virus (MPMV), a type D retrovirus, when the virus is growing in human embryo kidney (HEK) cells. The effect is transient and paralleled by a striking morphological alteration of the cells. The optimal TPA concentration for stimulation is 5 ng. ml-1. Contrary to infected HEK cells, TPA induces at similar concentrations neither stimulation of MPMV synthesis nor altered morphology in persistently MPMV-infected cells of the continuous human tumor cell line A 204.

Synergistic effect of tamoxifen and phorbol ester TPA on retrovirus synthesis in a human mammary carcinoma cell line

“…Virus production was assayed by particle-associated reverse transcriptase in 24-hr supematants. Our previous studies showed that addition of TPA to the growth medium of virus-producing cells led to a marked (5 to 40 times over basal level) but transient increase in virus production (peaking at 48 hr) at an optimal stimulatory concentration of 8nM (Wunderlich et al, 1982(Wunderlich et al, , 1984. Stimulation occurred on the level of RNA and could be inhibited by an anti-sense v-jun construct (Stein et al, 1991).…”