Inhibition of SF3b1 by pladienolide B evokes cycle arrest, apoptosis induction and p73 splicing in human cervical carcinoma cells.

Pladienolide B is a potent cancer cell growth inhibitor that targets the SF3b1 subunit of the spliceosome. There is considerable interest in the compound as a tool to study SF3b1 function in cancer. However, so far little information is available on the molecular mechanism of SF3b1 eliciting apoptosis in cancer cells. Here, we investigated the molecular mechanism of SF3b1 eliciting apoptosis in human cervical carcinoma cells. We demonstrated that inhibition of SF3b1 by pladienolide B inhibited proliferation of HeLa cells at low nanomolar concentrations in a dose- and time-dependent manner. It also induced G2/M phase arrest and significant rise of apoptotic cells. Moreover, it is indicated that inhibition of SF3b1 by pladienolide B induced Tap73/Delta Np73 expression and consequently down-regulated Bax/Bcl-2 ratio, cytochrome c release and caspase-3 expression. Thus, our results showed that SF3b1 plays a pivotal role in cycle arrest, apoptosis induction, and p73 splicing in human cervical carcinoma cells, suggesting that SF3b1 could be used as a potential candidate for cervical cancer therapy.