Antisense-mediated repression of RNA topoisomerase II expression leads to an impairment of HIV-1 replicative cycle

Previously, we have observed a strong restriction of the Moloney murine leu kemia virus (MoMLV) replicative cycle in a cell line displaying resistance to topoisomerase II (topo II)-interactive drugs. Resistance towards these a ntitumoral inhibitors was associated with decreased expression and activity of topo II, suggesting that such a decrease may be responsible for MoMLV r estriction. To more specifically assess the role of topo II during the retr oviral cycle, we have used the antisense strategy to obtain a selective dec rease of cellular topo II expression. The RNA antisense was isolated from a retroviral library expressing random fragments of human topo II (alpha for m). This system allowed us to investigate the HIV-1 replicative cycle in tw o related human CEM cell lines expressing different levels of topo II. Expr ession of the enzyme is decreased four- to sixfold following formation of a sense-antisense RNA hybrid. Repression of the topo II enzyme results in an impairment of the HIV-1 replicative cycle. Using the polymerase chain reac tion, we showed that the number of integration events was decreased in cell s repressing the enzyme, although viral DNA synthesis and circularization w ere equivalent to those in the parent cells.